Dual-Carbon Phase-Encapsulated Prelithiated SiOx Microrod Anode for Lithium-Ion Batteries

Among silicon-based anode family for Li-ion battery technology, SiOx, a nonstoichiometric silicon suboxide holds the potential for significant near-term commercial impact. In this context, this study mainly focuses on demonstrating an innovative SiOx@C anode design that adopts a pre-lithiation strategy based on in situ pyrolysis of Li-salt of silsesquioxane trisilanolate without the need for lithium metal or active lithium compounds and creates dual carbon encapsulation of SiOC nanodomains by simply one-step thermal treatment. This ingenious design ensures the pre-lithiation process and pre-lithiation material with high-environmental stability. Moreover, phenyl-rich organosiloxane clusters and polyacrylonitrile polymers are expected to serve as internal and external carbon source, respectively. The formation of an interpenetrating and continuous carbon matrix network would not only synergistically offer an improved electrochemical accessibility of active sites but also alleviate the volume expansion effect during cycling. As a result, this new type of anode delivered a high reversible capacity, remarkable cycle stability as well as excellent high-rate capability. In particular, the L2-SiOx@C material has a high initial coulomb efficienc of 80.4% and, after 500 cycles, a capacity retention as high as 97.5% at 0.5 A g-1 with a reversible specific capacity of 654.5 mA h g-1.

Dynamic Covalent Bonds Regulate Zinc Plating/Stripping Behaviors for High-Performance Zinc Ion Batteries

Artificial interfaces provide a comprehensive approach to controlling zinc dendrite and surface corrosion in zinc-based aqueous batteries (ZABs). However, due to consistent volume changes during zinc plating/stripping, traditional interfacial layers cannot consistently adapt to the dendrite surface, resulting in uncontrolled dendrite growth and hydrogen evolution. Herein, dynamic covalent bonds exhibit the Janus effect towards zinc deposition at different current densities, presenting a holistic strategy for stabilizing zinc anode. The PBSC intelligent artificial interface consisting of dynamic B-O covalent bonds is developed on zinc anode to mitigate hydrogen evolution and restrict dendrite expansion. Owing to the reversible dynamic bonds, PBSC exhibits shape self-adaptive characteristics at low current rates, which rearranges the network to accommodate volume changes during zinc plating/stripping, resisting hydrogen evolution. Moreover, the rapid association of B-O dynamic bonds enhances mechanical strength at dendrite tips, presenting a shear-thickening effect and suppressing further dendrite growth at high current rates. Therefore, the assembled symmetrical battery with PBSC maintains a stable cycle of 4500 hours without significant performance degradation and the PBSC@Zn||V2O5 pouch cell demonstrates a specific capacity exceeding 170 mAh g-1. Overall, the intelligent interface with dynamic covalent bonds provides innovative approaches for zinc anode interfacial engineering and enhances cycling performance.

Ternary Lithium Nickel Boride with 1D Rapid-Ion-Diffusion Channels as an Anode for Use in Lithium-Ion Batteries

Anode materials with high-rate performances and good electrochemical stabilities are urgently required for the grid-scale application of lithium-ion batteries (LIBs). Theoretically, transition metal borides are desirable candidates because of their appropriate working potentials and good conductivities. However, the reported metal borides exhibit poor performances owing to their lack of favorable Li+ storage sites and poor structural stabilities during long-term charging/discharging. In this work, a ternary alkali metal boride, Li1.2Ni2.5B2, which displays a high Li+ storage capacity and remarkable electrochemical stability and an excellent rate performance is studied. In contrast to conventional transition metal borides, the introduction of Li atoms facilitates the formation of 1D Ni/B-based honeycomb channels during synthesis. This Ni/B framework successfully sustains the strain during Li+ intercalation and deintercalation, and thus, the optimized Li1.2Ni2.5B2 anode exhibits an excellent cycle stability over 500 charge/discharge cycles. This electrode also exhibits superior reversible capacities of 350, 183, and 80 mA h g-1 at 0.1, 1, and 5 A g-1, respectively, indicating the considerable potential of the 1D Ni/B framework as a commercially available fast-charging LIB anode.

Surface-Pore-Modified N-Doped Amorphous Carbon Nanospheres Tailored with Toluene as Anode Materials for Lithium-Ion Batteries

The surface modification of amorphous carbon nanospheres (ACNs) through templates has attracted great attention due to its great success in improving the electrochemical properties of lithium storage materials. Herein, a safe methodology with toluene as a soft template is employed to tailor the nanostructure, resulting in ACNs with tunable surface pores. Extensive characterizations through transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption/desorption isotherms elucidate the impact of surface pore modifications on the external structure, morphology, and surface area. Electrochemical assessments reveal the enhanced performance of the surface-pore-modified carbon nanospheres, particularly ACNs-100 synthesized with the addition of 100 μL toluene, in terms of the initial discharge capacity, rate performance, and cycling stability. The interesting phenomenon of persistent capacity increase is ascribed to lithium ion movement within the graphite-like interlayer, resulting in ACNs-100 experiencing a capacity upswing from an initial 320 mAh g-1 to a zenith of 655 mAh g-1 over a thousand cycles at a rate of 2 C. The findings in this study highlight the pivotal role of tailored nanostructure engineering in optimizing energy storage materials.

Tunable Interfacial Electric Field-Mediated Cobalt-Doped FeSe/Fe3Se4 Heterostructure for High-Efficiency Potassium Storage

The interfacial electric field (IEF) in the heterostructure can accelerate electron transport and ion migration, thereby enhancing the electrochemical performance of potassium-ion batteries (PIBs). Nevertheless, the quantification and modulation of the IEF for high-efficiency PIB anodes currently remains a blank slate. Herein, we achieve for the first time the quantification and tuning of IEF via amorphous carbon-coated undifferentiated cobalt-doped FeSe/Fe3Se4 heterostructure (denoted UN-CoFe4Se5/C) for efficient potassium storage. Co doping can increase the IEF in FeSe/Fe3Se4, thereby improving the electron transport, promoting the potassium adsorption capacity, and lowering the diffusion barrier. As expected, the IEF magnitude in UN-CoFe4Se5/C is experimentally quantified as 62.84 mV, which is 3.65 times larger than that of amorphous carbon-coated FeSe/Fe3Se4 heterostructure (Fe4Se5/C). Benefiting from the strong IEF, UN-CoFe4Se5/C as a PIB anode exhibits superior rate capability (145.8 mAh g-1 at 10.0 A g-1) and long cycle lifespan (capacity retention of 95.1% over 3000 cycles at 1.0 A g-1). Furthermore, this undifferentiated doping strategy can universally regulate the IEF magnitude in CoSe2/Co9Se8 and FeS2/Fe7S8 heterostructures. This work can provide fundamental insights into the design of advanced PIB electrodes.

Synthesis and Characterization of MnIn2S4/Single-Walled Carbon Nanotube Composites as an Anode Material for Lithium-Ion Batteries

In this study, we synthesized a transition metal sulfide (TMS) with a spinel structure, i.e., MnIn2S4 (MIS), using a two-step hydrothermal and sintering process. In the context of lithium-ion battery (LIB) applications, ternary TMSs are being considered as interesting options for anode materials. This consideration arises from their notable attributes, including high theoretical capacity, excellent cycle stability, and cost-effectiveness. However, dramatic volume changes result in the electrochemical performance being severely limited, so we introduced single-walled carbon nanotubes (SWCNTs) and prepared an MIS/SWCNT composite to enhance the structural stability and electronic conductivity. The synthesized MIS/SWCNT composite exhibits better cycle performance than bare MIS. Undergoing 100 cycles, MIS only yields a reversible capacity of 117 mAh/g at 0.1 A/g. However, the MIS/SWCNT composite exhibits a reversible capacity as high as 536 mAh/g after 100 cycles. Moreover, the MIS/SWCNT composite shows a better rate capability. The current density increases with cycling, and the SWCNT composite exhibits high reversible capacities of 232 and 102 mAh/g at 2 A/g and 5 A/g, respectively. Under the same conditions, pristine MIS can only deliver reversible capacities of 21 and 4 mAh/g. The results indicate that MIS/SWCNT composites are promising anode materials for LIBs.

Achieving High-Rate and Stable Sodium-Ion Storage by Constructing Okra-Like NiS2/FeS2@Multichannel Carbon Nanofibers

Transition metal sulfides (TMSs) are considered as promising anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacities. However, the relatively low electrical conductivity, large volume variation, and easy aggregation/pulverization of active materials seriously hinder their practical application. Herein, okra-like NiS2/FeS2 particles encapsulated in multichannel N-doped carbon nanofibers (NiS2/FeS2@MCNFs) are fabricated by a coprecipitation, electrospinning, and carbonization/sulfurization strategy. The combined advantages arising from the hollow multichannel structure in carbon skeleton and heterogeneous NiS2/FeS2 particles with rich interfaces can provide facile ion/electron transfer paths, ensure boosted reaction kinetics, and help maintain the structural integrity, thereby resulting in a high reversible capacity (457 mA h g-1 at 1 A g-1), excellent rate performance (350 mA h g-1 at 5 A g-1), and outstanding long-term cycling stability (93.5% retention after 1100 cycles). This work provides a facile and efficient synthetic strategy to develop TMS-based heterostructured anode materials with high-rate and stable sodium storage properties.

One-step Solid-State Synthesis of V1.13Se2/V2O3 Heterostructure as a High Pseudocapacitance Anode for Fast-Charging Sodium-Ion Batteries

Sodium-ion batteries (SIBs) offer several benefits, including cost-efficiency and fast-charging characteristics, positioning them as attractive substitutes for lithium-ion batteries in energy storage applications. However, the inferior capacity and cycling stability of electrodes in SIBs necessitate further enhancement due to sluggish reaction kinetics. In this respect, the utilization of heterostructures, which can provide an inherent electric field and abundant active sites on the surface, has emerged as a promising strategy for augmenting the cycling stability and rate features of the electrodes. This work delves into the utilization of V1.13Se2/V2O3 heterostructure materials as anodes, initially fabricated via a simplified one-step solid-state sintering technique. The high pseudocapacitance and low characteristic relaxation time constant give the V1.13Se2/V2O3 heterostructure impressive properties, such as a high capacity of 328.5 mAh g-1 even after 1500 cycles at a high current density of 2 A g-1 and rate capability of 278.9 mAh g-1 at 5 A g-1. Moreover, the assembled sodium-ion full battery delivers a capacity of 118.5 mAh g-1 after 1000 cycles at 1 A g-1. These findings provide novel insight and guidance for the rapid synthesis of heterojunction materials and the advancement of SIBs.

Double-Shelled Fe-Fe3C Nanoparticles Embedded on a Porous Carbon Framework for Superior Lithium-Ion Half/Full Batteries

Cost-effective and environmentally friendly Fe-based active materials offer exceptionally high energy capacity in lithium-ion batteries (LIBs) due to their multiple electron redox reactions. However, challenges, such as morphology degradation during cycling, cell pulverization, and electrochemical stability, have hindered their widespread use. Herein, we demonstrated a simple salt-assisted freeze-drying method to design a double-shelled Fe/Fe3C core tightly anchored on a porous carbon framework (FEC). The shell consists of a thin Fe3O4 layer (≈2 nm) and a carbon layer (≈10 nm) on the outermost part. Benefiting from the complex nanostructuring (porous carbon support, core-shell nanoparticles, and Fe3C incorporation), the FEC anode delivered a high discharge capacity of 947 mAh g-1 at 50 mA g-1 and a fast-rate capability of 305 mAh g-1 at 10 A g-1. Notably, the FEC cell still showed 86% reversible capacity retention (794 mAh g-1 at 50 mA g-1) at a high cycling temperature of 80 °C, indicating superior structural integrity during cycling at extreme temperatures. Furthermore, we conducted a simple solid-state fluorination technique using the as-prepared FEC sample and excess NH4F to prepare iron fluoride-carbon composites (FeF2/C) as the positive electrode. The full cell configuration, consisting of the FEC anode and FeF2/C cathode, reached a remarkable capacity of 200 mAh g-1 at a 20 mA g-1 rate or an energy density of approximately 530 Wh kg-1. Thus, the straightforward and simple experimental design holds great potential as a revolutionary Fe-based cathodic-anodic pair candidate for high-energy LIBs.

Advancements in Noble Metal-Decorated Porous Carbon Nanoarchitectures: Key Catalysts for Direct Liquid Fuel Cells

Noble-metal nanocrystals have emerged as essential electrode materials for catalytic oxidation of organic small molecule fuels in direct liquid fuel cells (DLFCs). However, for large-scale commercialization of DLFCs, adopting cost-effective techniques and optimizing their structures using advanced matrices are crucial. Notably, noble metal-decorated porous carbon nanoarchitectures exhibit exceptional electrocatalytic performances owing to their three-dimensional cross-linked porous networks, large accessible surface areas, homogeneous dispersion (of noble metals), reliable structural stability, and outstanding electrical conductivity. Consequently, they can be utilized to develop next-generation anode catalysts for DLFCs. Considering the recent expeditious advancements in this field, this comprehensive review provides an overview of the current progress in noble metal-decorated porous carbon nanoarchitectures. This paper meticulously outlines the associated synthetic strategies, precise microstructure regulation techniques, and their application in electrooxidation of small organic molecules. Furthermore, the review highlights the research challenges and future opportunities in this prospective research field, offering valuable insights for both researchers and industry experts.

In Situ Electrophoretic Decorated Cactus-Type Metallic-Phase MoS2 on CaMn2O4 Nanofibers for Binder-Free Next-Generation LIBs

Ternary manganese-based oxides, such as CaMn2O4 (CMO) nanofibers fabricated via the electrospinning technique, have the potential to offer higher reversible capacity through conversion reactions in comparison to that of carbon-based anodes. However, its poor electrical conductivity hinders its usage in lithium-ion batteries (LIBs). Hence, to mitigate this issue, controlled single-step in situ decoration of highly conducting metallic-phase MoS2@CMO nanofibers has been achieved for the first time via the electrophoretic deposition (EPD) technique and utilized as a binder-free nanocomposite anode for LIBs. Further, the composition of MoS2@CMO nanofibers has also been optimized to attain better electronic and ionic conductivity. The morphological investigation revealed that the flakes of MoS2 nanoflowers are successfully and uniformly decorated over the CMO nanofibers' surface, forming a cactus-type morphology. As a binder-free nanocomposite LIB anode, CMOMS-7 (7 wt % MoS2@CMO) demonstrates a specific capacity of 674 mA h g-1 after 60 cycles at 50 mA g-1 and maintains a capacity of 454 mA h g-1 even after 300 cycles at 1000 mA g-1. Further, the good rate performance (102 mA h g-1 at 5000 mA g-1) of CMOMS-7 can be ascribed to the enhanced electrical conductivity provided by the metallic-phase MoS2. Moreover, the feasibility of CMOMS-7 is thoroughly investigated by using a full Li-ion cell incorporating a binder-free cathode of LiNi0.3Mn0.3Co0.3O2 (NMC). This configuration showcases an impressive energy density of 154 Wh kg-1. Thus, the hierarchical and aligned structure of CMO nanofibers combined with highly conductive MoS2 nanoflowers facilitates charge transportation within the composite electrodes. This synergistic effect significantly enhances the energy density of the conversion-based nanocomposites, making them highly promising anodes for advanced LIBs.

Hybrid-Mechanism Synergistic Flexible Nb2O5@WS2@C Carbon Nanofiber Anode for Superior Sodium Storage

Sodium-ion batteries (SIBs) have demonstrated remarkable development potential and commercial prospects. However, in the current state of research, the development of high-energy-density, long-cycle-life, high-rate-performance anode materials for SIBs remains a huge challenge. Free-standing flexible electrodes, owing to their ability to achieve higher energy density without the need for current collectors, binders, and conductive additives, have garnered significant attention across various fields. In this work, we designed and fabricated a free-standing three-dimensional flexible Nb2O5@WS2@C carbon nanofiber (CNF) anode based on a hybrid adsorption-intercalation-conversion mechanism of sodium storage, using electrospinning and hydrothermal synthesis processes. The hybrid structure, aided by synergistic effects, releases the advantages of all materials, demonstrating a superior rate performance (288, 248, 211, 158, 90, and 48 mA h g-1 at the current density of 0.2, 0.5, 1, 2, 5, and 10 A g-1, respectively) and good cycling stability (160 mA h g-1 after 200 cycles at 1 A g-1). This work provides certain guiding significance for future research on hybrid and flexible anodes of SIBs.

Microporous Sulfur-Carbon Materials with Extended Sodium Storage Window

Developing high-performance carbonaceous anode materials for sodium-ion batteries (SIBs) is still a grand quest for a more sustainable future of energy storage. Introducing sulfur within a carbon framework is one of the most promising attempts toward the development of highly efficient anode materials. Herein, a microporous sulfur-rich carbon anode obtained from a liquid sulfur-containing oligomer is introduced. The sodium storage mechanism shifts from surface-controlled to diffusion-controlled at higher synthesis temperatures. The different storage mechanisms and electrode performances are found to be independent of the bare electrode material's interplanar spacing. Therefore, these differences are attributed to an increased microporosity and a thiophene-rich chemical environment. The combination of these properties enables extending the plateau region to higher potential and achieving reversible overpotential sodium storage. Moreover, in-operando small-angle X-ray scattering (SAXS) reveals reversible electron density variations within the pore structure, in good agreement with the pore-filling sodium storage mechanism occurring in hard carbons (HCs). Eventually, the depicted framework will enable the design of high-performance anode materials for sodium-ion batteries with competitive energy density.

MXene as Promising Anode Material for High-Performance Lithium-Ion Batteries: A Comprehensive Review

Broad adoption has already been started of MXene materials in various energy storage technologies, such as super-capacitors and batteries, due to the increasing versatility of the preparation methods, as well as the ongoing discovery of new members. The essential requirements for an excellent anode material for lithium-ion batteries (LIBs) are high safety, minimal volume expansion during the lithiation/de-lithiation process, high cyclic stability, and high Li+ storage capability. However, most of the anode materials for LIBs, such as graphite, SnO2, Si, Al, and Li4Ti5O12, have at least one issue. Hence, creating novel anode materials continues to be difficult. To date, a few MXenes have been investigated experimentally as anodes of LIBs due to their distinct active voltage windows, large power capabilities, and longer cyclic life. The objective of this review paper is to provide an overview of the synthesis and characterization characteristics of the MXenes as anode materials of LIBs, including their discharge/charge capacity, rate performance, and cycle ability. In addition, a summary of the potential outlook for developments of these materials as anodes is provided.

Porous High-Entropy Oxide Anode Materials for Li-Ion Batteries: Preparation, Characterization, and Applications

High-entropy oxides (HEOs), as a new type of single-phase solid solution with a multi-component design, have shown great potential when they are used as anodes in lithium-ion batteries due to four kinds of effects (thermodynamic high-entropy effect, the structural lattice distortion effect, the kinetic slow diffusion effect, and the electrochemical "cocktail effect"), leading to excellent cycling stability. Although the number of articles on the study of HEO materials has increased significantly, the latest research progress in porous HEO materials in the lithium-ion battery field has not been systematically summarized. This review outlines the progress made in recent years in the design, synthesis, and characterization of porous HEOs and focuses on phase transitions during the cycling process, the role of individual elements, and the lithium storage mechanisms disclosed through some advanced characterization techniques. Finally, the future outlook of HEOs in the energy storage field is presented, providing some guidance for researchers to further improve the design of porous HEOs.

Micron-Sized Cobalt Niobium Oxide with Multiscale Porous Sponge-Like Structure Boosting High-Rate and Long-Life Lithium Storage

Niobium-based oxides show great potential as intercalation-type anodes in lithium-ion batteries due to their relatively high theoretical specific capacity. Nevertheless, their electrochemical properties are unsatisfactorily restricted by the poor electronic conductivity. Here, micron-sized Co0.5Nb24.5O62 with multiscale sponge-like structure is synthesized and demonstrated to be a fast-charging anode material. It can deliver a remarkable capacity of 287 mA h g-1 with a safe average working potential of ≈1.55 V vs Li+/Li and a high initial Coulombic efficiency of 91.1% at 0.1C. Owing to the fast electronic/ionic transport derived from the multiscale porous sponge-like structure, Co0.5Nb24.5O62 exhibits a superior rate capability of 142 mA h g-1 even at 10C. In addition, its maximum volume change during the charge/discharge process is determined to be 9.18%, thus exhibiting excellent cycling stability with 75.3% capacity retention even after 3000 cycles at 10C. The LiFePO4//Co0.5Nb24.5O62 full cells also achieve good rate performance of 101 mA h g-1 at 10C, as well as an excellent cycling performance of 81% capacity retention after 1200 cycles at 5C, further proving the promising application prospect of Co0.5Nb24.5O62.

Enhanced Aluminum-Ion Storage Properties of N-Doped Titanium Dioxide Electrode in Aqueous Aluminum-Ion Batteries

Aqueous aluminum-ion batteries (AIBs) have great potential as devices for future large-scale energy storage systems due to the cost efficiency, environmentally friendly nature, and impressive theoretical energy density of Al. However, currently, available materials used as anodes for aqueous AIBs are scarce. In this study, a novel sol-gel method was used to synthesize nitrogen-doped titanium dioxide (N-TiO2) as a potential anode material for AIBs in water. The annealed N-TiO2 showed a high discharge capacity of 43.2 mAh g-1 at a current density of 3 A g-1. Analysis of the electrode kinetics revealed that the N-TiO2 anodes exhibited rapid diffusion of aluminum ions, low resistance to charge transfer, and high electronic conductivity, enabling good rate performance. The successful implementation of a nitrogen-doping strategy provides a promising approach to enhance the electrochemical characteristics of electrode materials for aqueous AIBs.

Interfacial-Confined Isochronous Conversion to Biphasic Selenide Heterostructure with Enhanced Adsorption Behaviors for Robust High-Rate Na-Ion Storage

Sodium-ion batteries (SIBs) have gradually become one of the most promising energy storage techniques in the current era of post-lithium-ion batteries. For anodes, transitional metal selenides (TMSe) based materials are welcomed choices , owing to relatively higher specific capacities and enriched redox active sites. Nevertheless, current bottlenecks are blamed for their poor intrinsic electronic conductivities, and uncontrollable volume expansion during redox reactions. Given that, an interfacial-confined isochronous conversion strategy is proposed, to prepare orthorhombic/cubic biphasic TMSe heterostructure, namely CuSe/Cu3 VSe4 , through using MXene as the precursor, followed by Cu/Se dual anchorage. As-designed biphasic TMSe heterostructure endows unique hierarchical structure, which contains adequate insertion sites and diffusion spacing for Na ions, besides, the surficial pseudocapacitive storage behaviors can be also proceeded like 2D MXene. By further investigation on electronic structure, the theoretical calculations indicate that biphasic CuSe/Cu3 VSe4 anode exhibits well-enhanced properties, with smaller bandgap and thus greatly improves intrinsic poor conductivities. In addition, the dual redox centers can enhance the electrochemical Na ions storage abilities. As a result, the as-designed biphasic TMSe anode can deliver a reversible specific capacity of 576.8 mAh g-1 at 0.1 A g-1 , favorable Na affinity, and reduced diffusion barriers. This work discloses a synchronous solution toward demerits in conductivities and lifespan, which is inspiring for TMSe-based anode development in SIBs systems.

Hydroxyl-Decorated Carbon Cloth with High Potassium Affinity Enables Stable Potassium Metal Anodes

Highly anticipated potassium metal batteries possess abundant potassium reserves and high theoretical capacity but currently suffer from poor cycling stability as a result of dendritic growth and volume expansion. Here, carbon cloths modified with different functional groups treated with ethylene glycol, ethanolamine, and ethylenediamine are designed as 3D hosts, exhibiting different wettability to molten potassium. Among them, the hydroxyl-decorated carbon cloth with a high affinity for potassium can achieve molten potassium perfusion (K@EG-CC) within 3 s. By efficiently inducing the uniform deposition of metal potassium, buffing its volume expansion, and lowering local current density, the developed K@EG-CC anode alleviates the dendrite growth issue. The K@EG-CC||K@EG-CC symmetric battery can be cycled stably for 2100 h and has only a small voltage hysteresis of ≈93 mV at 0.5 mA cm-2 . Moreover, the high-voltage plateau, high energy density, and long cycle life of K metal full batteries can be realized with a low-cost KFeSO4 F@carbon nanotube cathode. This study provides a simple strategy to promote the commercial applications of potassium metal batteries.

A Defective Disc-Like Cu1.96 S Anode Material with the Efficient Cu Vacancies for High-Performance Sodium-Ion Storage

Due to their significant capacity and reliable reversibility, transition metal sulphides (TMSs) have received attention as potential anode materials for sodium-ion batteries (SIBs). Nonetheless, a prevalent challenge with TMSs lies in their significant volume expansion and sluggish kinetics, impeding their capacity for rapid and enduring Na+ storage. Herein, a Cu1.96 S@NC nanodisc material enriched with copper vacancies is synthesised via a hydrothermal and annealing procedure. Density functional theory (DFT) calculations reveal that the incorporation of copper vacancies significantly boosts electrical conductivity by reducing the energy barrier for ion diffusion, thereby promoting efficient electron/ion transport. Moreover, the presence of copper vacancies creates ample active sites for the integration of sodium ions, streamlines charge transfer, boosts electronic conductivity, and, ultimately, significantly enhances the overall performance of SIBs. This novel anode material, Cu1.96 S@NC, demonstrates a reversible capacity of 339 mAh g-1 after 2000 cycles at a rate of 5 A g-1 . In addition, it maintains a noteworthy reversible capacity of 314 mAh g-1 with an exceptional capacity retention of 96% even after 2000 cycles at 20 A g-1 . The results demonstrate that creating cationic vacancies is a highly effective strategy for engineering anode materials with high capacity and rapid reactivity.

Surface Decoration of TiC Nanocrystals onto the Graphite Anode Enables Fast-Charging Lithium-Ion Batteries

To significantly reduce the charging time of commercial lithium-ion batteries (LIBs), it is essential to control the surface properties of graphite anodes because the charging process involves sluggish interfacial kinetics between graphite and the electrolyte. For the effective surface modification of graphite, herein we demonstrate the surface decoration with titanium carbide (TiC) nanocrystals onto graphite particles via a simple wet-coating process. The high electrical conductivity, low Li+ adsorption energy, and small surface diffusion barrier of the TiC nanocrystals facilitate fast Li+ adsorption and migration in the graphite surface by reducing the overpotential upon the charging process. The feasibility of the TiC nanocrystal-decorated graphite (TiC@AG) anode is thoroughly examined with an in-depth understanding of the interfacial reaction mechanism. Furthermore, the full-cell with a commercial cathode (LiNi0.8Co0.1Mn0.1O2) and TiC@AG anode demonstrates an impressive capacity retention (94.5%) after 300 cycles under fast-charging condition (3 C-charging and 1 C-discharging) without any sign of Li plating. The charging time of the TiC@AG full-cell was estimated at 16.2 min (80% of state of charge), which is substantially shorter than that of the artificial graphite full-cell. Our findings offer practical insights into the design principles of advanced graphite anodes, contributing to the realization of fast-charging LIBs.

Mo-Doped LSCF as a Novel Coke-Resistant Anode for Biofuel-Fed SOFC

Climate change and damage to the environment, as well as the limitations of fossil fuels, have pushed governments to explore infinite renewable energy options such as biofuels. Solid Oxide Fuel Cell (SOFC) is a sustainable energy device that transforms biofuels into power and heat. It is now being researched to function at intermediate temperatures (600-700 °C) in order to prevent material deterioration and improve system life span. However, one of the major disadvantages of reducing the temperature is that carbon deposition impairs the electrochemical performance of the cell with a Ni-YSZ traditional anode. Here, molybdenum was doped into La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCFMo) as an innovative anode material with higher coke resistance and better phase stability under reducing conditions. X-ray diffraction (XRD) analysis showed increasing phase stability by increasing the Mo dopant. Electrochemical measurements proved that the LSCFMo anode is an active catalyst towards the methanol oxidation even at low temperatures as 600 °C, with an open circuit voltage (OCV) of 0.55 V, while GDC10 (Ga0.9Ce0.1O1.95) is used as the electrolyte. As an insightful result, no trace of any carbon deposition was found on the anode side after the tests. The combination of phase composition, morphological, and electrochemical studies demonstrate that LSCFMo is a suitable anode material for SOFCs fed by biofuels.

A Rapid, Scalable Laser-Scribing Process to Prepare Si/Graphene Composites for Lithium-Ion Batteries

Silicon has gained significant attention as a lithium-ion battery anode material due to its high theoretical capacity compared to conventional graphite. Unfortunately, silicon anodes suffer from poor cycling performance caused by their extreme volume change during lithiation and de-lithiation. Compositing silicon particles with 2D carbon materials, such as graphene, can help mitigate this problem. However, an unaddressed challenge remains: a simple, inexpensive synthesis of Si/graphene composites. Here, a one-step laser-scribing method is proposed as a straightforward, rapid (≈3 min), scalable, and less-energy-consuming (≈5 W for a few minutes under air) process to prepare Si/laser-scribed graphene (LSG) composites. In this research, two types of Si particles, Si nanoparticles (SiNPs) and Si microparticles (SiMPs), are used. The rate performance is improved after laser scribing: SiNP/LSG retains 827.6 mAh g-1 at 2.0 A gSi+C -1 , while SiNP/GO (before laser scribing) retains only 463.8 mAh g-1 . This can be attributed to the fast ion transport within the well-exfoliated 3D graphene network formed by laser scribing. The cyclability is also improved: SiNP/LSG retains 88.3% capacity after 100 cycles at 2.0 A gSi+C -1 , while SiNP/GO retains only 57.0%. The same trend is found for SiMPs: the SiMP/LSG shows better rate and cycling performance than SiMP/GO composites.

Synergistically Coupling Atomic-Level Defect-Manipulation and Nanoscopic-Level Interfacial Engineering Enables Fast and Durable Sodium Storage

Through inducing interlayer anionic ligands and functionally modifying conductive carbon-skeleton on the transition metal chalcogenides (TMCs) parent to achieve atomic-level defect-manipulation and nanoscopic-level architecture design is of great significance, which can broaden interlayer distance, optimize electronic structure, and mitigate structural deformation to endow high-efficiency battery performance of TMCs. Herein, an intriguing 3D biconcave hollow-tyre-like anode constituted by carbon-packaged defective-rich SnSSe nanosheet grafting onto Aspergillus niger spores-derived hollow-carbon (ANDC@SnSSe@C) is reported. Systematically experimental investigations and theoretical analyses forcefully demonstrate the existence of anion Se ligand and outer-carbon all-around encapsulation on the ANDC@SnSSe@C can effectively yield abundant structural defects and Na+ -reactivity sites, accelerate rapid ion migration, widen interlayer spacing, as well as relieve volume expansion, thus further resolving the critical issues throughout the charge-discharge processes. As anticipated, as-fabricated ANDC@SnSSe@C anode contributes extraordinary reversible capacity, wonderful cyclic lifespan with 83.4% capacity retention over 2000 cycles at 20.0 A g-1 , and exceptional rate capability. A series of correlated kinetic investigations and ex situ characterizations deeply reveal the underlying springheads for the ion-transport kinetics, as well as synthetically elucidate phase-transformation mechanism of the ANDC@SnSSe@C. Furthermore, the ANDC@SnSSe@C-based sodium ion full cell and hybrid capacitor offer high-capacity contribution and remarkable energy-density output, indicative of its great practicability.

Semi-Coherent Heterointerface Engineering via In Situ Phase Transition for Enhanced Sodium/Lithium-Ions Storage

To improve ion transport kinetics and electronic conductivity between the different phases in sodium/lithium-ion battery (LIB/SIB) anodes, heterointerface engineering is considered as a promising strategy due to the strong built-in electric field. However, the lattice mismatch and defects in the interphase structure can lead to large grain boundary resistance, reducing the ion transport kinetics and electronic conductivity. Herein, monometallic selenide Fe3 Se4 -Fe7 Se8 semi-coherent heterointerface embedded in 3D connected Nitrogen-doped carbon yolk-shell matrix (Fe3 Se4 -Fe7 Se8 @NC) is obtained via an in situ phase transition process. Such semi-coherent heterointerface between Fe3 Se4 and Fe7 Se8 shows the matched interfacial lattice and strong built-in electric field, resulting in the low interface impedance and fast reaction kinetics. Moreover, the yolk-shell structure is designed to confine all monometallic selenide Fe3 Se4 -Fe7 Se8 semi-coherent heterointerface nanoparticles, improving the structural stability and inhibiting the volume expansion effect. In particular, the 3D carbon bridge between multi-yolks shell structure improves the electronic conductivity and shortens the ion transport path. Therefore, the efficient reversible pseudocapacitance and electrochemical conversion reaction are enabled by the Fe3 Se4 -Fe7 Se8 @NC, leading to the high specific capacity of 439 mAh g-1 for SIB and 1010 mAh g-1 for LIB. This work provides a new strategy for constructing heterointerface of the anode for secondary batteries.

Pseudocapacitance-Dominated MnNb2 O6 -C Nanofiber Anode for Li-Ion Batteries

MnNb2 O6 anode has attracted much attention owing to its unique properties for holding Li ions. Unluckily, its application as a Li-ion battery anode is restricted by low capacity because of the inferior electronic conductivity and limited electron transfer. Previous studies suggest that structure and component optimization could improve its reversible capacity. This improvement is always companied by capacity increments, however, the reasons have rarely been identified. Herein, MnNb2 O6 -C nanofibers (NFs) with MnNb2 O6 nanoparticles (~15 nm) confined in carbon NFs, and the counterpart MnNb2 O6 NFs consisting of larger nanoparticles (40-100 nm) are prepared by electrospinning for clarifying this phenomenon. The electrochemical evaluations indicate that the capacity achieved by the MnNb2 O6 NF electrode presents an activation process and a degradation in subsequence. Meanwhile, the MnNb2 O6 -C NF electrode delivers high reversible capacity and ultra-stable cycling performance. Further analysis based on electrochemical behaviors and microstructure changes reveals that the partial structure rearrangement should be in charge of the capacity increment, mainly including pseudocapacitance increment. This work suggests that diminishing the dimensions of MnNb2 O6 nanoparticles and further confining them in a matrix could increase the pseudocapacitance-dominated capacity, providing a novel way to improve the reversible capacity of MnNb2 O6 and other intercalation reaction anodes.

Metal Phosphide Anodes in Sodium-Ion Batteries: Latest Applications and Progress

Sodium-ion batteries (SIBs), as the next-generation high-performance electrochemical energy storage devices, have attracted widespread attention due to their cost-effectiveness and wide geographical distribution of sodium. As a crucial component of the structure of SIBs, the anode material plays a crucial role in determining its electrochemical performance. Significantly, metal phosphide exhibits remarkable application prospects as an anode material for SIBs because of its low redox potential and high theoretical capacity. However, due to volume expansion limitations and other factors, the rate and cycling performance of metal phosphides have gradually declined. To address these challenges, various viable solutions have been explored. In this paper, the recent research progress of metal phosphide materials for SIBs is systematically reviewed, including the synthesis strategy of metal phosphide, the storage mechanism of sodium ions, and the application of metal phosphide in electrochemical aspects. In addition, future challenges and opportunities based on current developments are presented.

Structure-Performance Correlation Inspired Platinum-Assisted Anode with a Homogeneous Ionomer Layer for Proton Exchange Membrane Water Electrolysis

PEMWE is becoming one of the most promising technologies for efficient and green hydrogen production, while the anode OER process is deeply restricted by the now commercially used iridium oxide with sluggish reaction kinetics and super high cost. Deeply exploring the essential relationship between the underlying substrate materials and the performance of PEMWE cells while simultaneously excavating new practical and convenient methods to reduce costs and increase efficiency is full of challenges. Herein, two representative kinds of iridium oxide were studied, and their performance difference in PEMWE was precisely analyzed with electrochemical techniques and physical characterization and further linked to the ionomer/catalyst compound features. A novel anode with a uniform thin ionomer coating was successfully constructed, which simultaneously optimized the ionomer/catalyst aggregates as well as electrical conductivity, resulting in significantly enhanced PEMWE performance. This rigorous qualitative analysis of the structure-performance relationship as well as effective ionomer-affinitive optimization strategies are of great significance to the development of next-generation high-performance PEM water electrolyzers.

A Mechanistic Overview of the Current Status and Future Challenges of Aluminum Anode and Electrolyte in Aluminum-Air Batteries

Aluminum-air batteries (AABs) are regarded as attractive candidates for usage as an electric vehicle power source due to their high theoretical energy density (8100 Wh kg-1 ), which is considerably higher than that of lithium-ion batteries. However, AABs have several issues with commercial applications. In this review, we outline the difficulties and most recent developments in AABs technology, including electrolytes and aluminum anodes, as well as their mechanistic understanding. First, the impact of the Al anode and alloying on battery performance is discussed. Then we focus on the impact of electrolytes on battery performances. The possibility of enhancing electrochemical performances by adding inhibitors to electrolytes is also investigated. Additionally, the use of aqueous and non-aqueous electrolytes in AABs is also discussed. Finally, the challenges and potential future research areas for the advancement of AABs are suggested.

Hierarchical Architecture Engineering of Branch-Leaf-Shaped Cobalt Phosphosulfide Quantum Dots: Enabling Multi-Dimensional Ion-Transport Channels for High-Efficiency Sodium Storage

New-fashioned electrode hosts for sodium-ion batteries (SIBs) are elaborately engineered to involve multifunctional active components that can synergistically conquer the critical issues of severe volume deformation and sluggish reaction kinetics of electrodes toward immensely enhanced battery performance. Herein, it is first reported that single-phase CoPS, a new metal phosphosulfide for SIBs, in the form of quantum dots, is successfully introduced into a leaf-shaped conductive carbon nanosheet, which can be further in situ anchored on a 3D interconnected branch-like N-doped carbon nanofiber (N-CNF) to construct a hierarchical branch-leaf-shaped CoPS@C@N-CNF architecture. Both double carbon decorations and ultrafine crystal of the CoPS in-this exquisite architecture hold many significant superiorities, such as favorable train-relaxation, fast interfacial ion-migration, multi-directional migration pathways, and sufficiently exposed Na+ -storage sites. In consequence, the CoPS@C@N-CNF affords remarkable long-cycle durability over 10 000 cycles at 20.0 A g-1 and superior rate capability. Meanwhile, the CoPS@C@N-CNF-based sodium-ion full cell renders the potential proof-of-feasibility for practical applications in consideration of its high durability over a long-term cyclic lifespan with remarkable reversible capacity. Moreover, the phase transformation mechanism of the CoPS@C@N-CNF and fundamental springhead of the enhanced performance are disclosed by in situ X-ray diffraction, ex situ high-resolution TEM, and theoretical calculations.

Design of Ion Channel Confined Binary Metal Cu-Fe Selenides for All-Climate, High-Capacity Sodium Ion Batteries

Exploring special anode materials with high capacity, stable structure, and extreme temperature feasibility remains a great challenge in secondary sodium based energy systems. Here, a bimetallic Cu-Fe selenide nanosheet with refined nanostructure providing confined internal ion transport channels are reported, in which the structure improves the pseudocapacitance and reduces the charge transfer resistance for making a significant contribution to accelerating the reaction dynamics. The CuFeSe2 nanosheets have a high initial specific capacity of 480.4 mAh g-1 at 0.25 A g-1 , showing impressively excellent rate performance and ultralong cycling life over 1000 cycles with 261.1 mAh g-1 at 2.5 A g-1 . Meanwhile, it exhibits a good sodium storage performance at extreme temperatures from -20 °C to 50 °C, supporting at least 500 cycles. Besides, the CuFeSe2 ||Na3 V2 (PO4 )3 /C full cell delivers a high specific capacity of 168.5 mAh g-1 at 0.5 A g-1 and excellent feasibility for over 600 cycles long cycling. Additionally, the Na+ storage mechanisms are further revealed by ex situ X-ray diffraction (XRD) and in situ transmission electron microscopy (TEM) techniques. A feasible channelized structural design strategy is provided that inspires new instruction into the development of novel materials with high structural stability and low volume expansion rate toward the application of other secondary batteries.

N-Doped Carbon Nanowire-Modified Macroporous Carbon Foam Microbial Fuel Cell Anode: Enrichment of Exoelectrogens and Enhancement of Extracellular Electron Transfer

Microbial fuel cell (MFC) performance is affected by the metabolic activity of bacteria and the extracellular electron transfer (EET) process. The deficiency of nanostructures on macroporous anode obstructs the enrichment of exoelectrogens and the EET. Herein, a N-doped carbon nanowire-modified macroporous carbon foam was prepared and served as an anode in MFCs. The anode has a hierarchical porous structure, which can solve the problem of biofilm blockage, ensure mass transport, favor exoelectrogen enrichment, and enhance the metabolic activity of bacteria. The microscopic morphology, spectroscopy, and electrochemical characterization of the anode confirm that carbon nanowires can penetrate biofilm, decrease charge resistance, and enhance long-distance electron transfer efficiency. In addition, pyrrolic N can effectively reduce the binding energy and electron transfer distance of bacterial outer membrane hemin. With this hierarchical anode, a maximum power density of 5.32 W/m3 was obtained, about 2.5-fold that of bare carbon cloth. The one-dimensional nanomaterial-modified macroporous anodes in this study are a promising strategy to improve the exoelectrogen enrichment and EET for MFCs.

Silicon-Nanodiamond-Based Anode for a Lithium-Ion Battery

Maintaining the physical integrity of a silicon-based anode, which suffers from damage caused by severe volume changes during cycling, is a top priority in its practical applications. The performance of silicon-flake-based anodes has been significantly improved by mixing nanodiamond powders with silicon flakes for the fabrication of anodes for lithium-ion batteries (LIBs). Nanodiamonds adhere to the surfaces of silicon flakes and are distributed in the binder between flakes. A consistent and robust solid electrolyte interphase (SEI) is promoted by the aid of abundant reactive surface-linked functional groups and exposed dangling bonds of nanodiamonds, leading to enhanced physical integrity of the silicon flakes and the anode. The battery's high-rate discharge capabilities and cycle life are thus improved. SEM, Raman spectroscopy, and XRD were applied to examine the structure and morphology of the anode. Electrochemical performance was evaluated to demonstrate a capacity retention of nearly 75% after 200 cycles, with the final specific capacity exceeding 1000 mAh/g at a test current of 4 mA/cm2. This is attributed to the improved stability of the solid electrolyte interphase (SEI) structure that was achieved by integrating nanodiamonds with silicon flakes in the anode, leading to enhanced cycling stability and rapid charge-discharge performance. The results from this study present an effective strategy of achieving high-cycling-performance by adding nanodiamonds to silicon-flake-based anodes.

Operando Investigation of Silicon Anodes During Electrochemical Cycling in Li-ion Batteries

Silicon (Si) is recognized as a promising anode material for next-generation anodes due to its high capacity. However, large volume expansion and active particle pulverization during cycling rapidly deteriorate the battery performance. The relationship between Si anode particle size and particle pulverization, and the structure evolution of Si particles during cycling is not well understood. In this study, a quantitative, time-resolved "operando" small angle X-ray scattering (SAXS) investigation into the morphological change of unwrapped and reduced graphene oxide (rGO) wrapped Si nanoparticles (Si@rGO) is conducted with respect to the operating voltage. The results provide a clear picture of Si particle size change and the role of nonrigid rGO in mitigating Si volume expansion and pulverization. Further, this study demonstrates the advantage of "operando" SAXS in electrochemical environments as compared to other approaches.

Co4S3 Nanoparticles Confined in an MnS Nanorod-Grafted N, S-Codoped Carbon Polyhedron for Highly Efficient Sodium-Ion Batteries

Sodium-ion batteries (SIBs) suffer from limited ion diffusion and structural expansion, generating the urgent demand for Na+ accommodable materials with promising architectures. In this work, the rational exploration for Co4S3 nanoparticles confined in an MnS nanorod-grafted N, S-codoped carbon polyhedron (Co-Mn-S@N-S-C) is achieved by the in situ growth of MOF on MnO2 nanorod along with the subsequent carbonization and sulfurization. Benefiting from the distinctive nanostructure, the Co-Mn-S@N-S-C anode delivers excellent structural stability, resulting in prolonged cycling stability with a capacity retention of 90.2% after 1000 cycles at 2 A g-1. Moreover, the reaction storage mechanism is clarified by the in situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The results indicate that properly designed electrode materials have huge potential applications for highly efficient energy storage devices.

Catalytic Graphitization of Biocarbon for Lithium-Ion Anodes: A Minireview

The demand for electrochemical energy storage is increasing rapidly due to a combination of decreasing costs in renewable electricity, governmental policies promoting electrification, and a desire by the public to decrease CO2 emissions. Lithium-ion batteries are the leading form of electrochemical energy storage for electric vehicles and the electrical grid. Lithium-ion cell anodes are mostly made of graphite, which is derived from geographically constrained, non-renewable resources using energy-intensive and highly polluting processes. Thus, there is a desire to innovate technologies that utilize abundant, affordable, and renewable carbonaceous materials for the sustainable production of graphite anodes under relatively mild process conditions. This review highlights novel attempts to realize the aforementioned benefits through innovative technologies that convert biocarbon resources, including lignocellulose, into high quality graphite for use in lithium-ion anodes.

SrTiO3-SrVO3 Ceramics for Solid Oxide Fuel Cell Anodes: A Route from Oxidized Precursors

Perovskite-type Sr(Ti,V)O3-δ ceramics are promising anode materials for natural gas- and biogas-fueled solid oxide fuel cells, but the instability of these phases under oxidizing conditions complicates their practical application. The present work explores approaches to the fabrication of strontium titanate-vanadate electrodes from oxidized precursors. Porous ceramics with the nominal composition SrTi1-yVyOz (y = 0.1-0.3) were prepared in air via a solid state reaction route. Thermal processing at temperatures not exceeding 1100 °C yielded composite ceramics comprising perovskite-type SrTiO3, pyrovanadate Sr2V2O7 and orthovanadate Sr3(VO4)2 phases, while increasing firing temperatures to 1250-1440 °C enabled the formation of SrTi1-yVyO3 perovskites. Vanadium was found to substitute into the titanium sublattice predominantly as V4+, even under oxidizing conditions at elevated temperatures. Both perovskite and composite oxidized ceramics exhibit moderate thermal expansion coefficients in air, 11.1-12.1 ppm/K at 30-1000 °C, and insignificant dimensional changes induced by reduction in a 10%H2-N2 atmosphere. The electrical conductivity of reduced perovskite samples remains comparatively low, ~10-1 S/cm at 900 °C, whereas the transformation of oxidized vanadate phases into high-conducting SrVO3-δ perovskites upon reduction results in enhancement in conductivity, which reaches ~3 S/cm at 900 °C in porous composite ceramics with nominal composition SrTi0.7V0.3Oz. The electrical performance of the composite is expected to be further improved by optimization of the processing route and microstructure to facilitate the reduction of the oxidized precursor and attain better percolation of the SrVO3 phase.

Structure Dependent Electrochemical Behaviors of Hard Carbon Anode Materials Derived from Natural Polymer for Next-Generation Sodium Ion Battery

Hard carbons are one of the most promising anode materials for next-generation sodium-ion batteries due to their high reversible capacity, long cycle life, and low cost. The advantage in terms of price of hard carbons can be further improved by using cheaper resources such as biomass waste as precursors. Lignin is one of the richest natural bio-polymer in the earth which can be obtained from woods. As the lignin has three-dimensional amorphous polymeric structure, it is considered as good precursor for producing carbonaceous materials under proper carbonization processes for energy storage devices. In this study, structural properties of lignin-derived hard carbons such as interlayer spacing, degree of disorder and surface defects are controlled. Specifically, lignin-derived hard carbons were synthesized at 1000 °C, 1250 °C, and 1500 °C, and it was confirmed that the structure gradually changed from a disordered structure to ordered structure through X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Hard carbons exhibit sloping regions at high voltage and plateau region at low voltage during the electrochemical processes for sodium ions. As the heat treatment temperature increases, the contribution to the overall reversible capacity of the sloping region decreases and the contribution of the plateau region increases. This trend confirms that it affects reversible capacity, rate-capability, and cycling stability, meaning that an understanding of structural properties and related electrochemical properties is necessary when developing hard carbon as a negative electrode material for sodium ion batteries.

Unusual Hybrid Magnesium Storage Mechanism in a New Type of Bi2O2CO3 Anode

Bismuth and bismuth-based compounds have been extensively studied as anodes as prospective candidates for rechargeable magnesium batteries (rMBs). However, the unsatisfactory magnesium-storage capability caused by the typical alloying reaction mechanism severely restricts the practical option for anodes in rMBs. Herein, polyaniline intercalated Bi2O2CO3 nanosheets are prepared by an effective interlayer engineering strategy to fine-tune the layer structure of Bi2O2CO3, achieving enhanced magnesium-storage capacity, rate performance, as well as long cycle life. Excitedly, a stepwise insertion-conversion-alloying reaction is aroused to stabilize the performance, which is elucidated by in/ex situ investigations. Moreover, first-principles calculations confirm that the coupling of Bi2O2CO3 and polyaniline not only increases the conductivity induced by the strong density of states and the interior self-built-in electric field but also significantly reduces the energy barrier of Mg shuttles. Our findings shed light on exploring new electrode materials with an appropriate working mechanism toward high-performance rechargeable batteries.

Lithium Polyacrylate as Lithium and Carbon Source in the Synthesis of Li3 VO4 for High-Rate and Long-Life Li-Ion Batteries

Li3 VO4 is a promising anode material for use in lithium-ion batteries, however, the conventional synthesis methods for Li3 VO4 anodes involve the separate use of lithium and carbon sources, resulting in inefficient contact and low crystalline quality. Herein, lithium polyacrylate (LiPAA) was utilized as a dual-functional source and an in-situ polymerization followed by a spray-drying method was employed to synthesize Li3 VO4 . LiPAA serves a dual purpose, acting as both a lithium source to improve the crystal process and a carbon source to confine the particle size within a desired volume during high-temperature treatment. Additionally, the in-situ synthesis of a porous carbon decorating skeleton prevents the growth and agglomeration of Li3 VO4 particles and provides abundant ion/electron diffusion channels and contact areas. Based on the synthesis route and the constructed primary-secondary structure, the Li3 VO4 anodes obtained in this study exhibit an impressive capacity of 596.2 mAh g-1 . Moreover, they demonstrate enhanced rate performance over 600 cycles during 10 periods of rate testing, as well as a remarkably long lifespan of 5000 cycles at high currents. The utilization of LiPAA as a dual-functional source represents a broad approach that holds great potential for future research on high-performance electrodes requiring both lithium and carbon sources.

Investigating K+ Storage Behavior of Highly Graphitized Carbon Fibers as Anodes for a Potassium-Ion Battery

Many problems of potassium-ion batteries (PIBs) are hidden under a low mass load of the active material. However, developing research based on areal capacity is challenging for PIBs, due to the lack of an anode capable of delivering a stable capacity of more than 1 mAh cm-2. This work investigates the K+ storage behavior of highly graphitized carbon fibers (HG-CF), which exhibit automatic structural adjustments to mitigate voltage polarization. The created defects and residual K+ in the structure favor the reversible insertion/deinsertion of K+. HG-GF after structural adjustment realizes a capacity of 2 mAh (1.13 cm-2) without K deposition and a stable cyclic stability (>500 h). In situ X-ray diffraction and in situ Raman spectra were used to detect defect formation and structural evolution during cycles. This work demonstrates the feasibility of HG-GF as an anode for PIBs and provides a suitable anode for further research of PIBs based on areal capacity.

Bulk Modification of Porous TiNb2 O7 Microsphere to Achieve Superior Lithium-Storage Properties at Low Temperature

TiNb2 O7 , as a promising alternative of Li4 Ti5 O12 , exhibits giant potential as low-temperature anode due to its higher theoretical capacity and comparable structural stability. However, the sluggish electronic conductivity still remains a challenge. Herein, bulk modification of Cu+ doping in porous TiNb2 O7 microsphere is proposed via a simple one-step solvothermal method with subsequent calcination treatment. The results show that the electronic conductivity is improved effectively due to the reduced band gap after doping, while enhanced lithium-ion diffusion is achieved benefiting from the increased interplanar spacing. Therefore, the optimal sample of Cu0.06 Ti0.94 Nb2 O7 exhibits a high reversible capacity of 244.4 mA h g-1 at 100 mA g-1 after 100 cycles, superior rate capability, and long-term cycling stability at 1000 mA g-1 at room temperature. Particularly, it can also display good performance in a wide temperature range from 25 to -30 °C, including a reversible capacity of 76.6 mA h g-1 at -20 °C after 200 cycles at 200 mA g-1 . Moreover, Cu0.06 Ti0.94 Nb2 O7 //LiFePO4 full cell can deliver a high reversible capacity of 177.5 mA h g-1 at 100 mA g-1 . The excellent electrochemical properties at both ambient and low-temperatures demonstrate the great potential of Cu+ -doped TiNb2 O7 in energy-storage applications.

Protective NaSICON Interlayer between a Sodium-Tin Alloy Anode and Sulfide-Based Solid Electrolytes for All-Solid-State Sodium Batteries

This paper presents a suitable combination of different sodium solid electrolytes to surpass the challenge of highly reactive cell components in sodium batteries. The focus is laid on the introduction of ceramic Na3.4Zr2Si2.4P0.6O12 serving as a protective layer for sulfide-based separator electrolytes to avoid the high reactivity with the sodium metal anode. The chemical instability of the anode|sulfide solid electrolyte interface is demonstrated by impedance spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The Na3.4Zr2Si2.4P0.6O12 disk shows chemical stability with the sodium metal anode as well as the sulfide solid electrolyte. Impedance analysis suggests an electrochemically stable interface. Electron microscopy points to a reaction at the Na3.4Zr2Si2.4P0.6O12 surface toward the sulfide solid electrolyte, which does not seem to affect the performance negatively. The results presented prove the chemical stabilization of the anode-separator interface using a Na3.4Zr2Si2.4P0.6O12 interlayer, which is an important step toward a sodium all-solid-state battery. Due to the applied pressure that is mandatory for battery cells with sulfide-based cathode composite, the use of a brittle ceramic in such cells remains challenging.

Cu and Ni Co-Doped Porous Si Nanowire Networks as High-Performance Anode Materials for Lithium-Ion Batteries

Due to its extremely high theoretical mass specific capacity, silicon is considered to be the most promising anode material for lithium-ion batteries (LIBs). However, serious volume expansion and poor conductivity limit its commercial application. Herein, dealloying treatments of spray dryed Al-Si-Cu-Ni particles are performed to obtain a Cu/Ni co-doped Si-based anode material with a porous nanowire network structure. The porous structure enables the material to adapt to the volume changes in the cycle process. Moreover, the density functional theory (DFT) calculations show that the co-doping of Cu and Ni can improve the capture ability towards Li, which can accelerate the electron migration rate of the material. Based on the above advantages, the as-prepared material presents excellent electrochemical performance, delivering a reversible capacity of 1092.4 mAh g-1 after 100 cycles at 100 mA g-1. Even after 500 cycles, it still retains 818.7 mAh g-1 at 500 mA g-1. This study is expected to provide ideas for the preparation and optimization of Si-based anodes with good electrochemical performance.

Ultrathin Cobalt-Based Prussian Blue Analogue Nanosheet-Assembled Nanoboxes Interpenetrated with Carbon Nanotubes as a Fast Electron/Potassium-Ion Conductor for Superior Potassium Storage

Rechargeable potassium-ion batteries (PIBs) are regarded as potential substitutes for industrial lithium-ion batteries in large scale energy storage systems due to the world's abundant potassium supplies. Althogh cobalt hexacyanocobaltate (CoHCC) exhibits broad potential as a PIB anode material, its performance is currently unsatisfactory. Herein, novel 5 nm scale ultrathin CoHCC nanosheet-assembled nanoboxes with interspersed carbon nanotubes (CNTs/CoHCC nanoboxes) are fabricated to realize a highly reactive PIB anode. The ultrathin CoHCC layers substantially accelerate electron conduction and provide numerous active sites, while the connected CNTs provide fast axial electron transport. Consequently, the optimized anode exhibits a remarkable discharge capacity of 580.9 mAh g-1 at 0.1 A g-1 and long-term stability with 71.3% retention over 1000 cycles. In situ and ex situ characterizations and density functional theory calculations are further employed to elucidate the K+ storage process and the reason for the enhanced performance of the CNTs/CoHCC nanoboxes.

High-Rate One-Dimensional α-MnO2 Anode for Lithium-Ion Batteries: Impact of Polymorphic and Crystallographic Features on Lithium Storage

Manganese dioxide (MnO2) exists in a variety of polymorphs and crystallographic structures. The electrochemical performance of Li storage can vary depending on the polymorph and the morphology. In this study, we present a new approach to fabricate polymorph- and aspect-ratio-controlled α-MnO2 nanorods. First, δ-MnO2 nanoparticles were synthesized using a solution plasma process assisted by three types of sugars (sucrose, glucose, and fructose) as reducing promoters; this revealed different morphologies depending on the nucleation rate and reaction time from the molecular structure of the sugars. Based on the morphology of δ-MnO2, the polymorphic-transformed three types of α-MnO2 nanorods showed different aspect ratios (c/a), which highly affected the transport of Li ions. Among them, a relatively small aspect ratio (c/a = 5.1) and wide width of α-MnO2-S nanorods (sucrose-assisted) induced facile Li-ion transport in the interior of the particles through an increased Li-ion pathway. Consequently, α-MnO2-S exhibited superior battery performance with a high-rate capability of 673 mAh g-1 at 2 A g-1, and it delivered a high reversible capacity of 1169 mAh g-1 at 0.5 A g-1 after 200 cycles. Our findings demonstrated that polymorphs and crystallographic properties are crucial factors in the electrode design of high-performance Li-ion batteries.

Superb Li-Ion Storage of Sn-Based Anode Assisted by Conductive Hybrid Buffering Matrix

Although Sn has been intensively studied as one of the most promising anode materials to replace commercialized graphite, its cycling and rate performances are still unsatisfactory owing to the insufficient control of its large volume change during cycling and poor electrochemical kinetics. Herein, we propose a Sn-TiO2-C ternary composite as a promising anode material to overcome these limitations. The hybrid TiO2-C matrix synthesized via two-step high-energy ball milling effectively regulated the irreversible lithiation/delithiation of the active Sn electrode and facilitated Li-ion diffusion. At the appropriate C concentration, Sn-TiO2-C exhibited significantly enhanced cycling performance and rate capability compared with its counterparts (Sn-TiO2 and Sn-C). Sn-TiO2-C delivers good reversible specific capacities (669 mAh g-1 after 100 cycles at 200 mA g-1 and 651 mAh g-1 after 500 cycles at 500 mA g-1) and rate performance (446 mAh g-1 at 3000 mA g-1). The superiority of Sn-TiO2-C over Sn-TiO2 and Sn-C was corroborated with electrochemical impedance spectroscopy, which revealed faster Li-ion diffusion kinetics in the presence of the hybrid TiO2-C matrix than in the presence of TiO2 or C alone. Therefore, Sn-TiO2-C is a potential anode for next-generation Li-ion batteries.

Electrochemical Performance and Mechanism of Bimetallic Organic Framework for Advanced Aqueous Zn Ion Batteries

Widespread interest has been generated by aqueous zinc batteries (AZIBs), which have excellent theoretical capacities (820 mA h g-1), a low redox potential (-0.76 V vs SHE of Zn metal), and high security. Suitable cathodes for constructing high performance AZIBs are of great signification. Metal-organic frameworks (MOFs) with adjustable structure via metals and organic units show great potential in AZIBs. In this work, ZnMn-Squaric acid (ZnMn-SQ) was synthesized using squaric acid through coprecipitation and served as the cathode for AZIBs. The ZnMn-SQ electrode demonstrated a high capacity of 489.1 mA h g-1 at 0.2 A g-1. Meanwhile, ZnMn-SQ can obtain 80.7 mA h g-1 after 1300 cycles, showing an outstanding long cycle life. More importantly, ex situ characterizations of XRD, XPS, and FT-IR revealed that ZnMn-SQ undergoes a structural transformation from the initial ZnMn-SQ framework to manganese oxide accompanied by Zn-SQ and then reduced to MnOOH, ZnMn2O4, and Zn4SO4(OH)6·5H2O (ZHS) in subsequent cycles. In addition, a modified zinc anode using cubic porous Zn-SQ-3d was used to construct ZnMn-SQ // Zn-SQ-3d@Zn(Zn-SQ-3d-coated Zn) high performance AZIBs, the capacity of which reaches 171.3 mA h g-1 at 1 A g-1 after 660 cycles. This work provided chances for constructing high-performance zinc ion batteries using MOF compounds.

Bismuth-Nanoparticles-Embedded Porous Carbon Derived from Seed Husks as High-Performance for Anode Energy Electrode

In energy application technology, the anode part of the electrode is typically composed of carbon-coated materials that exhibit excellent electrochemical performance. The carbon-coated electrodes facilitate electrochemical reactions involving the fuel and the oxidant. Energy electrodes are used in stationary power plants to generate electricity for the grid. These large-scale installations are known as distributed generation systems and contribute to grid stability and reliability. Understanding the practical applications of energy materials remains a significant hurdle in the way of commercialization. An anode electrode has one key limitation, specifically with alloy-type candidates, as they tend to exhibit rapid capacity degradation during cycling due to volume expansion. Herein, biomass-derived carbon from sunflowers (seeds husks) via pyrolysis and then bismuth nanoparticles are treated with carbon via a simple wet-chemical method. The electrode Bi@C offers several structural advantages, such as high capacity, good cycling stability, and exceptional capability at the current rate of 500 mA g-1, delivering a capacity of 731.8 mAh g-1 for 200 cycles. The biomass-derived carbon coating protects the bismuth nanoparticles and contributes to enhanced electronic conductivity. Additionally, we anticipate the use of low-cost biomass with hybrid composition has the potential to foster environment-friendly practices in the development of next-generation advanced fuel cell technology.

Sustainable Polyvinyl Chloride-Derived Soft Carbon Anodes for Potassium-Ion Storage: Electrochemical Behaviors and Mechanism

Soft carbon is a promising anode material for potassium-ion batteries due to its favorable properties such as low cost, high conductivity, stable capacity, and low potential platform. Polyvinyl chloride, as a white pollutant, is a soft carbon precursor that can be carbonized at varying temperatures to produce soft carbons with controllable defect and crystal structures. This work investigates the effect of carbonization temperature on the crystalline structures of the obtained soft carbons. In situ Raman spectroscopy was used to elucidate the adsorption-intercalation charge storage mechanism of potassium ions in soft carbons. Soft carbons prepared at the temperature of 800 °C have a defect-rich, short-range ordered structure, which provides optimal intercalation and adsorption sites for potassium ions, resulting in a satisfactory capacity of 302 mAh g-1 . This work presents new possibilities for designing soft carbon materials from recycling plastics for potassium-ion batteries.