Electronic Modulation and Structural Engineering of Carbon-Based Anodes for Low-Temperature Lithium-Ion Batteries: A Review

Unlocking the structure and cation synergistic modulation of Prussian blue analogues with double redox mechanism for improved aqueous nonmetallic ion storage

Prussian blue analogs (PBAs) exhibit high energy density and a good electrochemical stability window in aqueous non-metallic ion batteries, which is conducive to achieving high energy output and stable operation. Additionally, their synthesis process is simple and environmentally friendly, meeting the demands of sustainable development. However, the poor conductivity, structural stability issues, and inadequate ion diffusion pathways limit their application in batteries. To overcome these challenges, researchers have adopted various optimization strategies: enhancing the conductivity of PBAs by compositing with high-conductivity carbon materials such as graphite, carbon nanotubes, or graphene; optimizing synthesis conditions such as temperature and reaction time to improve the defect and structural water content of PBAs, thereby enhancing their stability and electrochemical performance; employing surface modification techniques, such as conductive polymer encapsulation and acid etching, to improve their electrochemical stability and ion transport performance; and optimizing ion diffusion efficiency and battery kinetics by selecting suitable electrolytes and additives. These comprehensive measures contribute to improving the electrochemical performance of PBAs and promoting the development of their commercial applications. Based on prior research advancements, we introduce a novel synergistic regulation strategy: the creation of multi-redox-active centers to augment the transport capability of non-metallic ions and the optimization of defect structures through the establishment of a metal ion concentration gradient, thereby enhancing both electrochemical stability and performance.

A review of improvements on electric vehicle battery

The development of efficient and high-performance electric vehicle (EV) batteries relies on improving various components, such as the anode and cathode electrodes, separators, and electrolytes. This review paper offers an elaborate overview of different materials for these components, emphasizing their respective contributions to the improvement of EV battery performance. Carbon-based materials, metal composites, and polymer nanocomposites are explored for the anode, offering high energy density and capacity. However, they are noted to be susceptible to Li plating. Unique structures, such as Titanium niobium oxide (TiNb2O7), offer high theoretical capacity, quick Li+ intercalation, and an extended lifecycle. Meanwhile, molybdenum disulfide (MoS2), with 2D and 3D structures, exhibits high reversible specific capacity, outstanding rate performance, and cyclic stability, showing promising properties as anode material. For cathodes, lithium-iron phosphate (LFP), lithium-cobalt oxide (LCO), lithium-nickel-cobalt-aluminum oxide (NCA), lithium-nickel-manganese-cobalt oxide (NMC), and cobalt-free lithium-nickel-manganese oxide (NMO) are considered, offering specific energy and capacity advantages. For instance, LFP cathode electrodes show good thermal stability, good electrochemical performance, and long lifespan, while NMC exhibits high specific energy, relatively high capacity, and cost savings. NCA has a high specific energy, decent specific power, large capacity, and a long lifecycle. NMO shows excellent rate capability, cyclic stability, and cost-effectiveness but with limited cycle performance. Separator innovations, including polyolefin materials, nanofiber separators, graphene-based composites, and ceramic-polymer composites, are analyzed for use as separators, considering mechanical strength, porosity, wettability with the electrolyte, electrolytic absorption, cycling efficiency, and ionic conductivity. The electrolyte comprises lithium salts such as lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), and other salts dissolved in carbonate solvents. This improves energy density, capacity, and cycling stability and provides high ion mobility and resistance to decomposition. By examining the existing literature, this review also explores research on the solid electrolyte interface (SEI) and lithium plating, providing valuable insights into understanding and mitigating these critical issues. Despite the progress, limitations such as practical implementation challenges, potential cost implications, and the need for further research on scale-up feasibility and long-term durability are acknowledged. These efforts to enhance the electrochemical characteristics of key battery parameters-positive and negative electrodes, separators, and electrolytes-aim to improve capacity, specific energy density, and overall energy density. These continuous endeavours strive for faster charging of EV batteries and longer travel ranges, contributing to the ongoing evolution of EV energy storage systems. Thus, this review paper not only explores remarkable strides in EV battery technology but also underscores the imperative of addressing challenges and propelling future research for sustainable and high-performance electric vehicle energy storage systems.

Bio-Inspired Electrodes with Rational Spatiotemporal Management for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are currently the predominant energy storage power source. However, the urgent issues of enhancing electrochemical performance, prolonging lifetime, preventing thermal runaway-caused fires, and intelligent application are obstacles to their applications. Herein, bio-inspired electrodes owning spatiotemporal management of self-healing, fast ion transport, fire-extinguishing, thermoresponsive switching, recycling, and flexibility are overviewed comprehensively, showing great promising potentials in practical application due to the significantly enhanced durability and thermal safety of LIBs. Taking advantage of the self-healing core-shell structures, binders, capsules, or liquid metal alloys, these electrodes can maintain the mechanical integrity during the lithiation-delithiation cycling. After the incorporation of fire-extinguishing binders, current collectors, or capsules, flame retardants can be released spatiotemporally during thermal runaway to ensure safety. Thermoresponsive switching electrodes are also constructed though adding thermally responsive components, which can rapidly switch LIB off under abnormal conditions and resume their functions quickly when normal operating conditions return. Finally, the challenges of bio-inspired electrode designs are presented to optimize the spatiotemporal management of LIBs. It is anticipated that the proposed electrodes with spatiotemporal management will not only promote industrial application, but also strengthen the fundamental research of bionics in energy storage.

Optimizing Mn in Prussian blue analogs with double redox active sites to induce boosted Zn2+ storage

Prussian Blue analogs (PBAs) are a suitable aqueous zinc-ion batteries (AZIBs) cathode material, but they face issues related to low specific capacity and cycling lifespan due to insufficient active sites and poor ion de-intercalation structural stability. In this study, Mn-Prussian Blue Analog (Mn-PBA) is fabricated using a simple co-precipitation method and the morphology of Mn-PBA is further optimized through artificially manipulating concentration gradients strategy, effectively enhancing the structural stability of Zn2+ de-intercalation. Furthermore, the introduction of Mn established dual Zn2+ active centers in Mn-PBA (Mn-O and Fe(CN)6]4-/[Fe(CN)6]3-), leading to an increased specific capacity. As a proof of concept for AZIBs, the optimized Mn-PBA-3 cathode exhibits a high reversible specific capacity of 143.5 mAh/g and maintains a capacity retention of 88.5 % after 250 cycles at 1 A/g, surpassing commercial MnO2 (30.5 mAh/g after 100 cycles). Mn-PBA-3 also delivers a high capacity of 79.0 mA h g-1 after 2000 cycles of 10 A/g. The mechanism of the Zn2+ double redox reaction of Mn-PBA-3 has been revealed in detail by in situ Raman and a series of ex situ techniques. Under a high operating voltage window of 0-1.9 V, Zn//Mn-PBA-3 demonstrates a capacity of 99.3 mAh/g after 800 cycles (5 A/g) by assembling zinc ion button battery. This work has reference significance for structurally modulated PBAs used in high performance AZIBs.

Morphology design and electronic configuration of MoSe2 anchored on TiO2 nanospheres for high energy density sodium-ion half/full batteries

Molybdenum selenide (MoSe2) has shown potential sodium storage properties due to its large layer spacing (0.646 nm) and high theoretical capacity and narrow band gap. However, as the anode material of sodium ion batteries (SIBs), the MoSe2's performance is not ideal, especially due to the layer agglomeration and stacking caused by volume expansion and low intrinsic conductivity. Hence, morphology design and electronic configuration of MoSe2 is proposed via building MoSe2 nanosheets and auxiliary sulfur doping on the surface of the TiO2 hollow nanosphere (S-MoSe2@TiO2). The hierarchical shaped S-MoSe2@TiO2 effectively overcomes the shortcomings of high surface energy and weak interlayer van der Waals force of MoSe2. As anode for SIBs, S-MoSe2@TiO2 delivers enhanced cycling life and rate capability (308 mAh/g at 10 A/g after 1000 cycles) with the comparison of MoSe2@TiO2 or pure MoSe2 and TiO2. Such excellent sodium storage performance is due to the fast diffusion kinetics of Na+. When it is applied in sodium ion full batteries, the S-MoSe2@TiO2 anode based cell can reach a high energy density of 187.8 W h kg-1 at 148.3 W kg-1. The design of the new MoSe2-based hybrid provides a novel scheme for the preparation of advanced anode in SIBs.

A carbonyl-rich conjugated organic compound for aqueous rechargeable Na+ storage with wide voltage window workability

Organic compounds have become an important electrode material for aqueous electrochemical energy storage. However, organic electrodes still face poor performance in aqueous batteries due to insufficient electrochemical activity. In this work, a novel conjugated quinone compound containing a rich carbonyl group was designed. The quinone compound was synthesized by a simple dehydration reaction of pyrene-4,5,9,10-tetrone (PTO) and 1,2-diaminoanthraquinone (1,2-AQ); it contains 4 pyrazines (CN) from AQ and 4 carbonyl groups (CO), as well as a large number of active sites and the excellent conductivity brought by its conjugated structure ensures the high theoretical capacity of PTO-AQ. In the context of aqueous sodium ion batteries (ASIBs), the electrode material known as PTO-AQ exhibits a notable reversible discharge capacity of 117.9 mAh/g when subjected to a current density of 1 A/g; impressively, it maintained a capacity retention rate of 74.3 % even after undergoing 500 charge and discharge cycles, a performance significantly surpassing that of pristine PTO and AQ. Notably, PTO-AQ exhibits a wide operating voltage range (-1.0-0.5 V) and a cycle life of up to 10,000 cycles. In situ Raman and ex situ measurements were used to analyze the structural changes of PTO-AQ during charge and discharge and the energy storage mechanism in NaAC. The effective promotion of Na+ storage brought by a rich carbonyl group was obtained. The structural energy level and electrostatic potential of PTO-AQ were calculated, and the active center distribution of PTO-AQ was obtained. This work serves as a guide for designing high-performance aqueous organic electrode materials that operate across a wide voltage range while also explaining their energy storage mechanism.

Structural Engineering of Anode Materials for Low-Temperature Lithium-Ion Batteries: Mechanisms, Strategies, and Prospects

The severe degradation of electrochemical performance for lithium-ion batteries (LIBs) at low temperatures poses a significant challenge to their practical applications. Consequently, extensive efforts have been contributed to explore novel anode materials with high electronic conductivity and rapid Li+ diffusion kinetics for achieving favorable low-temperature performance of LIBs. Herein, we try to review the recent reports on the synthesis and characterizations of low-temperature anode materials. First, we summarize the underlying mechanisms responsible for the performance degradation of anode materials at subzero temperatures. Second, detailed discussions concerning the key pathways (boosting electronic conductivity, enhancing Li+ diffusion kinetics, and inhibiting lithium dendrite) for improving the low-temperature performance of anode materials are presented. Third, several commonly used low-temperature anode materials are briefly introduced. Fourth, recent progress in the engineering of these low-temperature anode materials is summarized in terms of structural design, morphology control, surface & interface modifications, and multiphase materials. Finally, the challenges that remain to be solved in the field of low-temperature anode materials are discussed. This review was organized to offer valuable insights and guidance for next-generation LIBs with excellent low-temperature electrochemical performance.

Metal-injection and interface density engineering induced nickel diselenide with rapid kinetics for high-energy sodium storage

The key to the innovation of sodium-ion batteries (SIBs) is to find efficient sodium-storage electrode. Here, metal Mo doping of NiSe2 is proposed by modified electrospinning strategy followed by in situ conversion process. The Mo-NiSe2 anchoring on hollow carbon nanofibers (HCNFs) would make full use of the multi-channel HCNFs in the inner layer and the active sites of Mo-NiSe2 in the outer layer, which plays an important role in buffering the volume stress of Na+ (de)insertion and reducing the adsorption energy barrier of Na+. Innovatively, it is proposed to jointly regulate the SIBs performance of NiSe2 by both metal atom doping and interface effects, thereby adjusting the sodium ion adsorption barrier of NiSe2. The Mo-NiSe2@HCNFs exhibits remarkable performance in SIBs, demonstrating a high specific capacity of 396 mAh/g after 100 cycles at 1 A/g. Moreover, it maintains outstanding cycling stability, retaining 77.6 % of its capacity (211 mAh/g) even after 1000 cycles at 10 A/g. This comprehensive electrochemical performances are due to the structural stability and outstanding electronic conductance of the Mo-NiSe2@HCNFs, as evidenced by the diffusion analysis and ex situ charge-discharge process characterization. Furthermore, coupled with the Na3V2(PO4)2O2F cathodes, the full cell also achieves a high energy density of 123 Wh kg-1. The theoretical calculation of the hypervalent Mo doing further proves the benefit of its Na+ adsorption and denser conduction band distribution. This study provides a reference for the construction of transition metal selenide via doping and interface engineering in sodium storage.

Vanadium Hexacyanoferrate Prussian Blue Analogs for Aqueous Proton Storage: Excellent Electrochemical Properties and Mechanism Insights

The significant attraction toward aqueous proton batteries (APBs) is attributable to their expedited kinetics, elevated safety profile, and economical feasibility. Nevertheless, their practical implement is significantly blocked by the unsatisfactory energy density due to the limited cathode materials. Herein, vanadium hexacyanoferrate Prussian blue analog (VOHCF) is introduced as a potentially favorable cathode material for APBs. The findings demonstrate that this VOHCF electrode exhibits a notable reversible capacity of 102.7 mAh g-1 and exceptional cycling stability, with 95.4% capacity retention over 10 000 cycles at 10 A g-1 . It is noteworthy that this is the detailed instance of VOHCF being proposed as a cathode for APBs. Combining the in situ characterization techniques and theoretical simulations, the origins of excellent proton storage performance are revealed as the multiple redox mechanisms with double active centers of ─C≡N group and V═O bond in VOHCF as well as the robust structure stability. A proton full cell with excellent performance is further achieved by coupling the VOHCF cathode and diquinoxalino[2,3-a:2',3'-c] phenazine (HATN) anode, demonstrating the great potential of VOHCF in practical applications. This work could provide fundamental understanding to the development of feasible cathode materials for proton storage device.

Aliovalent doping and structural design of MoSe2 with fast reaction kinetics for high-stable sodium-ion half/full batteries

The development of high-quality anode materials is critical for the advancement of sodium-ion batteries (SIBs). MoSe2 is a candidate anode for SIBs, while its inherent limitations, such as the agglomeration of nanosheets, poor electron conductance and mechanical strain due to volume changes during cycling, which can lead to decreased performance and durability in SIBs. To overcome the challenges, a novel aliovalent doping and structural engineering was taken to prepare reduced graphene oxide (rGO) functionalized and phosphorus-doped MoSe2 flake (P-MoSe2@rGO) via in situ growth technique. The unique structural design of P-MoSe2@rGO addresses material limitations and optimizes performance by providing a high conductive grid for ion/electron transfer, a large surface area for full electrolyte penetration, and effective suppression of MoSe2 nanosheet agglomeration and mechanical strain due to volume change during charge/discharge in SIBs. The P-MoSe2@rGO inherits the enhanced electronic conductivity and enlarged layer spacing (from 0.652 to 0.668 nm), which boosts the reaction kinetics and facilitates the insertion/extraction of sodium ions. The P-MoSe2@rGO exhibits excellent long-cycle properties with a high reversible capacity of 384 mAh/g at 2 A/g and 338 mAh/g at 10 A/g after 1450 circulations. Detailed discussion of reaction kinetics is conducted. Theoretical calculations prove that doping of P atoms in MoSe2 reduces the forbidden band gap from 1.443 to 1.397 eV and accelerates ion and electron migration. Furthermore, the full cell P-MoSe2@rGO//Na3V2(PO4)3@C (NVP@C) demonstrates a remarkable cycling durability of 326 mAh/g after 200 cycles and a high energy density of 159.6 Wh kg-1. This process provides a reference for the adjustment and modification of MoSe2 to adapt to high performance SIBs anode.

Modified separators boost polysulfides adsorption-catalysis in lithium-sulfur batteries from Ni@Co hetero-nanocrystals into CNT-porous carbon dual frameworks

In this manuscript, nickel/cobalt bimetallic nanocrystals confining into three-dimensional interpenetrating dual-carbon conductive structure (NiCo@C/CNTs) were successfully manufactured by annealing its core-shell structure (Ni-ZIF-67@ZIF-8) precursor under the high temperature. The results presented that the bimetallic nickel and cobalt nanocrystals with superior catalytic activity could quickly convert solid Li2S/Li2S2into soluble LiPSs and effectively decrease the energy barrier. While the hierarchical CNT-porous carbon dual frameworks can provide quick electron/ion transport because of their large specific surface area and the exposure of enough active sites. When used as the separator modifier for lithium sulfur batteries, the battery properties were significantly improved with high specific capacity, outstanding rate capability, and long-term cycle stability. Specifically, its initial specific capacity can achieve to 1038.51 mAh g-1 at 0.5C. At the high rate of 3C, it still delivers satisfactory discharge capacity of 555 mAhg-1 and the capacity decay rate is only 0.065% per cycle after 1000 cycles at 1C. Furthermore, even exposed to heavy sulfur loading (3.61 mg/cm2), they still maintain promising cycle stability. Therefore, such kinds of MOFs derivative with powerful chemical immobilization and catalytic conversion for polysulfides provides a novel guidance for the modification separator and the potential application in the field of high-performance Li-S batteries.

Structural regulation enabled stable hollow molybdenum diselenide nanosheet anode for ultrahigh energy density sodium ion pouch cell

For the continued use of sodium-ion batteries (SIBs), which require matching anode materials, it is crucial to create high energy density energy storage devices. Here, hollow nanoboxes shaped carbon supported sulfur-doped MoSe2 nanosheets (S-MoSe2@NC) are fabricated by in situ growth and heterodoping strategy. This ensures that the MoSe2 nanosheets are tightly anchored to the nanoboxes carbon, and the structure can effectively buffer the volume stress caused by sodium ion (de)intercalation, as well as providing abundant ion/electron migration transportations. As anode for SIBs, the S-MoSe2@NC shows a higher rate capability and excellent cycling stability (431.1 mAh/g after 1100 cycles at 10 A/g). This excellent cycle life and high rate ability are due to the structural stability and outstanding electronic conductance with reduced band gap of the S-MoSe2@NC, as evidenced by the diffusion analysis and theoretical calculation. In order to promote the application of SIBs, the S-MoSe2@NC and NaNi1/3Fe1/3Mn1/3O2 were assembled into a pouch cell, and the test found that besides the excellent cycle rate performance, the ultrahigh energy density of 256 Wh kg-1 and flexible characteristics can be achieved. This study has proven that building a structure with a rock-steady foundation and quick ion migration may efficiently control sodium storage and pave the way for novel applications of high-performance transition metal dichalcogenides in sodium storage.

Quinone-amine polymer nanospheres with enhanced redox activity for aqueous proton storage

One of the biggest obstacles to the development of aqueous proton batteries (APBs), despite numerous optimization techniques, is the preparation and use of high-performance electrode materials. In this work, to improve the high solubility, limited capacity and poor cycle life of small organic molecules in APBs, homogeneous dispersed quinone-amine polymer nanospheres (PQANS) (average diameter: 220 nm) were synthesized by a polymerization reaction based on 3,3'-diaminobenzidine (DAB) and benzoquinone (BQ), making them suitable for proton storage in aqueous systems. As an anode for APBs, the obtained PQANS exhibits an improved reversible capacity of 126.2 mAh/g at 1 A/g after 300 cycles. The durable stable measurement of PQANS at 10 A/g was also conducted with a specific capacity of 66.8 mAh/g after 12,000 cycles. A series of in situ or ex situ measurements were used to establish the superior H+ storage mechanism of PQANS. A novel reaction mechanism of redox enhancement was revealed due to the existence of more carbonyl groups after the first cycle. Theoretical calculations were conducted to help illustrate the principle of binding protons with functional groups in PQANS. Finally, a PQANS anode-based aqueous proton full battery was constructed to demonstrate its potential application, which exhibits a specific capacity of 50.6 mAh/g at 1 A/g (600 cycles). This work provides a reference for preparing high-performance polymer-based electrode materials in aqueous batteries.

In situ Cu doping of ultralarge CoSe nanosheets with accelerated electronic migration for superior sodium-ion storage

The progress of sodium-ion batteries is currently confronted with a noteworthy obstacle, specifically the paucity of electrode materials that can store large quantities of Na+ in a reversible fashion while maintaining competitiveness. Herein, ultrafast and long-life sodium storage of metal selenides is rationally demonstrated by employing micron-sized nanosheets (Cu-CoSe@NC) through electron accumulation engineering. The nanosheet structure proves to be effective in reducing the transport distance of sodium ions. Furthermore, the addition of Cu ions enhances the electron conductivity of CoSe and accelerates charge delocalization. As an anode for sodium-ion batteries, Cu-CoSe@NC exhibits a noticeably enhanced specific capacity of 527.2 mA h g-1 at 1.0 A g-1 after 100 cycles. Additionally, Cu-CoSe@NC maintains a capacity of 428.5 mA h g-1 at 5.0 A g-1 after 800 cycles. It is possible to create sodium-ion full batteries with a high energy density of 101.1 W h kg-1. The superior sodium storage performance of Cu-CoSe@NC is attributed to the high pseudo-capacitance and diffusion control mechanisms, as evidenced by theoretical calculations and ex situ measurements.

Optimized Morphology and Tuning the Mn3+ Content of LiNi0.5Mn1.5O4 Cathode Material for Li-Ion Batteries

The advantages of cobalt-free, high specific capacity, high operating voltage, low cost, and environmental friendliness of spinel LiNi_0.5Mn_1.5O₄ (LNMO) material make it one of the most promising cathode materials for next-generation lithium-ion batteries. The disproportionation reaction of Mn³⁺ leads to Jahn-Teller distortion, which is the key issue in reducing the crystal structure stability and limiting the electrochemical stability of the material. In this work, single-crystal LNMO was synthesized successfully by the sol-gel method. The morphology and the Mn³⁺ content of the as-prepared LNMO were tuned by altering the synthesis temperature. The results demonstrated that the LNMO_110 material exhibited the most uniform particle distribution as well as the presence of the lowest concentration of Mn³⁺, which was beneficial to ion diffusion and electronic conductivity. As a result, this LNMO cathode material had an optimized electrochemical rate performance of 105.6 mAh g^-1 at 1 C and cycling stability of 116.8 mAh g^-1 at 0.1 C after 100 cycles.

Synergy of oxygen defects and structural modulation on titanium niobium oxide with a constructed conductive network for high-rate lithium-ion half/full batteries

Titanium niobium oxide as an electrode material for lithium-ion batteries (LIBs) has relatively high working potential and theoretical capacity, which is expected to replace a graphite anode.