Top-Down Strategy to Synthesize Mesoporous Dual Carbon Armored MnO Nanoparticles for Lithium-Ion Battery Anodes

Concisely Constructing S, F Co-Modified MnO Nanoparticles Attached to S, N Co-Doped Carbon Skeleton as a High-Rate Performance Anode Material

The utilization of MnO anodes with high storage capacity is significantly hindered by rapid capacity fading and inadequate rate capability, stemming from substantial volume fluctuations and low electrical conductivity. Crafting a composite comprising sulfur and fluorine co-modified MnO nanoparticles integrated with sulfur and nitrogen co-doped carbon matrices promises enhanced electrochemical performance yet poses formidable obstacles. Here, we present a straightforward synthetic strategy for in situ growth of sulfur and fluorine co-modified MnO nanoparticles onto sulfur and nitrogen co-doped carbon scaffolds. This integration effectively mitigates volume variations and enhances electrical conductivity. As a result, the SF-MnO/SNC composite demonstrates remarkable cycling stability and rate capability when employed as a lithium-ion battery anode. Remarkably, it achieves a high reversible capacity of 975 mAh g-¹ after 80 cycles at 0.1 A g-¹ and retains a substantial capacity of 498 mAh g-¹ even at a high rate of 2.0 A g-¹. The concise synthesis method and exceptional rate properties render the SF-MnO/SNC composite a promising anode material for lithium-ion batteries. The strategy of simultaneously doping oxides and carbon will bring new ideas to the research of oxide anodes.

Multifunctional Cr Substitution Modulates Electrochemical Activity of Mn1-xCrxO for High-Performance Lithium-Ion Battery Anodes

Metal oxides are a promising candidate for lithium-ion battery (LIB) anodes due to their high theoretical capacity and long cycle life but also face inherent poor conductivity and volume variation, making them difficult to promote the application. The cation substitution strategy is an important means to facilitate improved rate and cycling performance. However, the effect of cation substitution on electrochemical activity is multivariate and complex, and a comprehensive and systematic analysis is essential for understanding the relationship between components and properties. Herein, the aliovalent heterogeneous Cr-substituted MnO was used as a model to systematically investigate the effects of Cr substitution on the crystal structure, electron distribution, defect construction, and electrochemical reaction processes. Theoretical calculations and experimental results reveal that Cr substitution can effectively modulate the electronic structure, build a built-in electric field, generate cationic defects, and catalyze the electrochemical reaction process, thereby improving the electrode kinetics and electrochemical activity of active materials. When the optimized Mn_0.94Cr_0.06O was used as the anode for LIBs, a reversible capacity of 1547.3 mAh g^-1 was obtained after 450 cycles at a current density of 1 C (1 C = 756 mA g^-1 for half-cells), and a reversible capacity of up to 1126.2 mAh g^-1 could be maintained even after 700 cycles at a current density of 2 C. The assembled Mn_0.94Cr_0.06O//LiCoO₂ full cell further confirms the scalability of the heterogeneous atom substitution strategy.

Development of silica-coated rare-earth doped strontium aluminate toward superhydrophobic, anti-corrosive and long-persistent photoluminescent epoxy coating

Long-persistent phosphorescent smart paints have the ability to continue glowing in the dark for a prolonged time period to function as energy-saving products. Herein, new epoxy/silica nanocomposite paints were prepared with different concentrations of lanthanide-doped aluminate nanoparticles (LAN; SrAl₂ O₄ : Eu²⁺ , Dy³⁺ ). The LAN pigment was firstly coated with SiO₂ utilizing the heterogeneous precipitation technique to provide LAN-encapsulated between SiO₂ nanoparticles (LAN@SiO₂ ). The epoxy/silica/lanthanide-doped aluminate nanoparticles (ESLAN) nanocomposite paints were coated on steel. The prepared ESLAN paints were studied by transmission electron microscope (TEM), infrared spectra (FTIR), scanning electron microscope (SEM), X-ray fluorescence analysis (XRF), and energy-dispersive X-ray spectra (EDS). The transparency and coloration properties of the nanocomposite coated films were explored by CIE Lab parameters and photoluminescence spectra. The ultraviolet-induced luminescence properties of the transparent coated films demonstrated greenish phosphorescence at 518 nm upon excitation at 368 nm. Both hardness and hydrophobic activities were investigated. The anticorrosion activity of the nanocomposite films coated onto mild steel substrates immersed in NaCl_(aq) (3.5%) was studied by the electrochemical impedance spectral (EIS) analysis. The silica-containing coatings were monitored to exhibit anticorrosion properties. Additionally, the nanocomposite films with LAN@SiO₂ (25%) exhibited the optimized long-lasting luminescence properties in the dark for 90 minutes. The nanocomposite films showed highly reversible and durable long-lived phosphorescence.

Production of photoluminescent transparent poly(methyl methacrylate) for smart windows

Photochromic and long-lasting photoluminescent transparent, rigid, ultraviolet (UV) protective and superhydrophobic poly(methyl methacrylate) (PMMA) plastic able to switch colour beneath UV irradiation was developed. Photoluminescent transparent PMMA plastic was prepared by the simple polymerization process of methyl methacrylate immobilized with alkaline earth aluminate (AEA) nanoparticles. These colourless PMMA plastic substrates showed a colour switch to greenish underneath UV light as proved using CIELAB screening. The morphology of AEA was evaluated using transmission electron microscopy. Conversely, transparent PMMA samples were evaluated using energy-dispersive X-ray spectra, scanning electron microscope, X-ray fluorescence spectroscopy and for hardness properties. Additionally, the photoluminescence properties were explored by studying excitation and emission spectra. The produced luminescence colourless PMMA plastic substrates displayed excitation band at 370 nm, and three emission peaks at 433, 494 and 513 nm. Photoluminescent PMMA with lower contents of AEA showed fast and reversible photochromism under UV light, while PMMA samples with higher contents of AEA showed long-lasting luminescence such as a flashlight with the ability to replace electric power. The findings showed that the produced photoluminescence colourless PMMA plastic substrates exhibited enhanced UV shielding and superhydrophobicity.

Development of Mechanically Reliable and Transparent Photochromic Film Using Solution Blowing Spinning Technology for Anti-Counterfeiting Applications

Photochromic materials have attracted broad interest to enhance the anti-counterfeiting of commercial products. In order to develop anti-counterfeiting mechanically reliable composite materials, it is urgent to improve the engineering process of both the material and matrix. Herein, we report on the development of anti-counterfeiting mechanically reliable nanocomposites composed of rare-earth doped aluminate strontium oxide phosphor (RESA) nanoparticles (NPs) immobilized into the thermoplastic polyurethane-based nanofibrous film successfully fabricated via the simple solution blowing spinning technology. The generated photochromic film exhibits an ultraviolet-stimulated anti-counterfeiting property. Different films of different emissive properties were generated using different total contents of RESA. Transmission electron microscopy was utilized to investigate the morphological properties of RESA NPs to display a particle diameter of 3-17 nm. The morphologies, compositions, optical transmittance, and mechanical performance of the produced photochromic nanofibrous films were investigated. Several analytical methods were employed, including energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier-transform infrared spectrometry. The fibrous diameter of RESA-TPU was in the range of 200-250 nm. In order to ensure the development of transparent RESA-TPU film, RESA must be prepared in the nanosized form to allow better dispersion without agglomeration in the TPU matrix. The luminescent RESA-TPU film displayed an absorbance intensity at 367 nm and two emission intensities at 431 and 517 nm. The generated RESA-TPU films showed an enhanced hydrophobicity without negatively influencing their original appearance and mechanical properties. Upon irradiation with ultraviolet light, the transparent nanofibrous films displayed rapid and reversible photochromism to greenish-yellow without fatigue. The produced anti-counterfeiting films demonstrated stretchable, flexible, and translucent properties. As a simple sort of anti-counterfeiting substrates, the current novel photochromic film provides excellent anti-counterfeiting strength at low-cost as an efficient method to develop versatile materials with high mechanical strength to create an excellent market as well as adding economic and social values.

Multi-core yolk-shell-structured Bi2Se3@C nanocomposite as an anode for high-performance lithium-ion batteries

Emerging Bi₂Se₃-based anode materials are attracting great interest for lithium storage because of their high theoretical capacity. Although quite attractive, Bi₂Se₃ still faces the problem of large volume expansion during lithiation/delithiation, leading to poor cycling stability. Herein, a multi-core yolk-shell Bi₂Se₃@C nanocomposite was designed and synthesized via a solvothermal method followed by heat treatment. The as-prepared yolk-shell nanocomposite consists of two parts: several Bi₂Se₃ nanospheres (diameter of approximately 100 nm) as a core, and carbon (thickness of approximately 16 nm) as the shell. Owing to its unique structural features, multi-core yolk-shell Bi₂Se₃@C nanocomposite demonstrates excellent cycling stability with a capacity of 392.2 mA h g^-1 at 0.2 A g^-1 after 100 cycles for lithium-ion batteries (LIBs). A reversible capacity of 416.9 mA h g^-1 can be maintained even at a higher current density of 1 A g^-1 after 1200 cycles. The reason for the superior electrochemical performance was further explored through electrochemical kinetic analysis and theoretical calculations. This work provides an effective strategy for the preparation of multi-core yolk-shell anode materials, and also affords a new method by which to prepare high-performance LIBs.

Room Temperature Syntheses of ZnO and Their Structures

ZnO has many technological applications which largely depend on its properties, which can be tuned by controlled synthesis. Ideally, the most convenient ZnO synthesis is carried out at room temperature in an aqueous solvent. However, the correct temperature values are often loosely defined. In the current paper, we performed the synthesis of ZnO in an aqueous solvent by varying the reaction and drying temperatures by 10 °C steps, and we monitored the synthesis products primarily by XRD). We found out that a simple direct synthesis of ZnO, without additional surfactant, pumping, or freezing, required both a reaction (TP) and a drying (TD) temperature of 40 °C. Higher temperatures also afforded ZnO, but lowering any of the TP or TD below the threshold value resulted either in the achievement of Zn(OH)2 or a mixture of Zn(OH)2/ZnO. A more detailed Rietveld analysis of the ZnO samples revealed a density variation of about 4% (5.44 to 5.68 gcm−3) with the synthesis temperature, and an increase of the nanoparticles’ average size, which was also verified by SEM images. The average size of the ZnO synthesized at TP = TD = 40 °C was 42 nm, as estimated by XRD, and 53 ± 10 nm, as estimated by SEM. For higher synthesis temperatures, they vary between 76 nm and 71 nm (XRD estimate) or 65 ± 12 nm and 69 ± 11 nm (SEM estimate) for TP = 50 °C, TD = 40 °C, or TP = TD = 60 °C, respectively. At TP = TD = 30 °C, micrometric structures aggregated in foils are obtained, which segregate nanoparticles of ZnO if TD is raised to 40 °C. The optical properties of ZnO obtained by UV-Vis reflectance spectroscopy indicate a red shift of the band gap by ~0.1 eV.

Dual Immobilization of SnOx Nanoparticles by N-Doped Carbon and TiO2 for High-Performance Lithium-Ion Battery Anodes

The grain aggregation engendered kinetics failure is regarded as the main reason for the electrochemical decay of nanosized anode materials. Herein, we proposed a dual immobilization strategy to suppress the migration and aggregation of SnO_x nanoparticles and corresponding lithiation products through constructing SnO_x/TiO₂@PC composites. The N-doped carbon could anchor the tin oxide particles and inhibit their aggregation during the preparation process, leading to a uniform distribution of ultrafine SnO_x nanoparticles in the matrix. Meanwhile, the incorporated TiO₂ component works as parclose to suppress the migration and coarsening of SnO_x and corresponding lithiation products. In addition, the N-doped carbon and TiO₂/Li_xTiO₂ can significantly improve the electrical and ionic conductivities of the composites, enabling a good diffusion and charge-transfer dynamics. Owing to the dual immobilization from the "synergistic effect" of N-doped carbon and the "parclose effect" of TiO₂, the conversion reaction of SnO_x remains fully reversible throughout the cycling. Thereby, the composites exhibit excellent cycling performance in half cells and can be fully utilized in full cells. This work may provide an inspiration for the rational design of tin-based anodes for high-performance lithium-ion batteries.

Nitrogen-Doped Graphene-Buffered Mn2 O3 Nanocomposite Anodes for Fast Charging and High Discharge Capacity Lithium-Ion Batteries

Mn₂ O₃ is a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity and low discharge potential. However, low electronic conductivity and capacity fading limits its practical application. In this work, Mn₂ O₃ with 1D nanowire geometry is synthesized in neutral aqueous solutions by a facile and effective hydrothermal strategy for the first time, and then Mn₂ O₃ nanoparticle and nitrogen-doped reduced graphene oxide (N-rGO) are composited with Mn₂ O₃ nanowires (Mn₂ O₃ -GNCs) to enhance its volume utilization and conductivity. When used as an anode material for LIBs, the Mn₂ O₃ -GNCs exhibit high reversible capacity (1350 mAh g^-1 ), stable cycling stability, and good rate capability. Surprisingly, the Mn₂ O₃ -GNC electrodes can also show fast charging capability; even after 200 cycles (charge: 10 A g^-1 ; discharge: 0.5 A g^-1 ), its discharge capacity can also keep at ≈500 mAh g^-1 . In addition, the Mn₂ O₃ -GNCs also have considerable full cell and supercapacitor performance. The excellent electrochemical performances can be ascribed to the N-rGO network structure and 1D nanowire structure, which can ensure fast ion and electron transportation.

Nonsiliceous Mesoporous Materials: Design and Applications in Energy Conversion and Storage

In this work, the progress in the design of nonsiliceous mesoporous materials (nonSiMPMs) over the last five years from the perspectives of the chemical composition, morphology, loading, and surface modification is summarized. Carbon, metal, and metal oxide are in focus, which are the most promising compositions. Then, representative applications of nonSiMPMs are demonstrated in energy conversion and storage, including recent technical advances in dye-sensitized solar cells, perovskite solar cells, photocatalysts, electrocatalysts, fuel cells, storage batteries, supercapacitors, and hydrogen storage systems. Finally, the requirements and challenges of the design and application of nonSiMPMs are outlined.

MOF-derived manganese monoxide nanosheet-assembled microflowers for enhanced lithium-ion storage

Achieving high energy density, power density and cycling performance is a great challenge for lithium-ion battery (LIB) anodes. To obtain favorable electrochemical properties, an effective approach for designing composite nanomaterials with good stability and large specific surface area has been reported here. In this work, metal-organic framework (MOF)-derived manganese monoxides with a stable macromolecular framework were synthesized by utilizing the template agent 1,2,3,4-butanetetracarboxylic acid (BTCA) and the organic salt manganese acetylacetone, which possess a compact microflower structure assembled by nanosheets. As a synergistic effect, not only the amorphous carbon derived from MOFs enhances the specific capacity and stability, but also the unique nanosheet exhibits a significant nano-effect and high areal capacity, which is in favour of an electrochemical reaction. For further enhancement of the electrochemical performance, reduced graphene oxide (rGO) was introduced. When tested as a LIB anode, the MnO@rGO composite displays superior reversible capacities (1716 mA h g-1 at 0.1 A g-1 and 930 mA h g-1 at 2 A g-1) and remarkable rate performances. The research results of the composite nanomaterials lay a foundation for the fabrication of high-capacity and stable anode materials in LIBs.

Tailoring Three-Dimensional Composite Architecture for Advanced Zinc-Ion Batteries

Rechargeable aqueous Zn-ion batteries (ZIBs) are of considerable interest for future energy storage. Their main limitation, however, is developing suitable cathode materials capable of sustaining the Zn²⁺ repeated intercalation/deintercalation. Herein, a three-dimensional polypyrrole (PPy)-encapsulated Mn₂O₃ composite architecture is developed for advanced ZIBs. The engineering can be easily realized via in situ phase transformation of MnCO₃ microboxes with subsequent self-initiated polymerization of PPy. The abundant open-up pores (∼30 nm) throughout the construction accelerate ion migration and provide a more active interface for Zn²⁺ storage in the Mn₂O₃@PPy bulk electrode. Meanwhile, the PPy skin uniformly wrapped on the Mn₂O₃ microbox not only guarantees a good conductive network for faster electron transport but also inhibits the dissolution of Mn₂O₃ and protects the integrity of the electrode from structural damage. As a result, the Mn₂O₃@PPy electrode can operate at reversible capacity exceeding those of most other cathode materials, but can still provide longer lifetime (no capacity decay over 2000 cycles at 0.4 A g^-1) and higher rate performance than others. Furthermore, theoretical studies show the H⁺ and Zn²⁺ coinsertion storage mechanism and reaction dynamics. The results show that this three-dimensional Mn₂O₃@PPy architecture is a promising cathode material for high-performance ZIBs.

Molten-Salt-Assisted Synthesis of Hierarchical Porous MnO@Biocarbon Composites as Promising Electrode Materials for Supercapacitors and Lithium-Ion Batteries

Biomass-derived carbon composites (e.g., metal oxide/biocarbon) have been used as promising electrode materials for energy storage devices owing to their natural abundance and simple preparation process. However, low loading content/inhomogeneous distribution of metal oxides and inefficient cracking of biocarbon (BC) are intractable obstacles that impede the efficient utilization of biomass. In this work, hierarchical porous MnO/BC composites were prepared by a facile molten-salt-assisted strategy based on the superior salt-water absorption ability of agaric. The addition of NaCl induces a liquid reaction medium by formation of a molten salt mixture at high temperature to effectively realize the activation and cracking of the bulk carbon, and it also acts as a recyclable sacrificial template to form mesopores and macropores in the as-prepared hierarchical porous MnO/BC composites. The highly porous and uniform BC framework effectively enhances ion diffusion and electron-transfer ability, serves as a protective layer to prevent fracturing and agglomeration of MnO, and thus enables superior rate performance and cycling stability of the MnO/BC composite for both supercapacitor electrodes (94 % capacity retention at 20 mA cm^-2 after 5000 cycles) and lithium-ion battery anodes (783 mA h g^-1 after 1000 cycles). Notably, considering the simple and low-cost preparation process, this work opens a promising avenue for the large-scale production of advanced metal oxide/BC hybrid electrode materials for electrochemical energy storage.

In situ synthesis of open hollow tubular MnO/C with high performance anode materials for lithium ion batteries using kapok fiber as carbon matrix

MnO/C materials with a long lifetime and high rate performance via a biomass template strategy for the lithium ion battery (LIB) market are indispensable. Therefore, novel and efficient ways for their synthesis are urgently required to greatly alleviate the pressure of consuming nonrenewable resources. Herein, we fabricate an open hollow tubular MnO/C hybrid based on the transformation of a natural kapok fiber by hydrothermal and thermal treatment. The as-prepared hybrid material was obtained with high synthesis efficiency and exhibited an extremely stable structure attributed to the in situ growth strategy, overcoming volumetric expansion and self-aggregation of MnO. As an anode material for LIBs, this typical MnO/C electrode demonstrated a high reversible capacity of 1917 mAh · g^-1 at 300 mA · g^-1 and an excellent rate performance of 693.1 mAh · g^-1 at 5000 mA · g^-1. More importantly, this biomass carbon-based material demonstrates a superior cycling stability of 1433.1 mAh · g^-1 at a high current density of 5000 mA · g^-1 after 1000 cycles. The significant electrical performance of this new type of green material is promising for the development of LIBs.

In situ synthesis of ultrasmall MnO nanoparticles encapsulated by a nitrogen-doped carbon matrix for high-performance lithium-ion batteries

Ultrasmall MnO nanoparticles encapsulated into the nitrogen-rich doped carbon matrix hybrids are synthesized by annealing Mn₂(EDTA) precursors and exhibit outstanding electrochemical performance as advanced anode material for lithium-ion batteries.

Facile fabrication of 3D porous MnO@GS/CNT architecture as advanced anode materials for high-performance lithium-ion battery

To overcome inferior rate capability and cycle stability of MnO-based anode materials for lithium-ion batteries (LIBs), we reported a novel 3D porous MnO@GS/CNT composite, consisting of MnO nanoparticles homogeneously distributed on the conductive interconnected framework based on 2D graphene sheets (GS) and 1D carbon nanotubes (CNTs). The distinctive architecture offers highly interpenetrated network along with efficient porous channels for fast electron transfer and ionic diffusion as well as abundant stress buffer space to accommodate the volume expansion of the MnO nanoparticles. The MnO@GS/CNT anode exhibits an ultrahigh capacity of 1115 mAh g^-1 at 0.2 A g^-1 after 150 cycles and outstanding rate capacity of 306 mAh g^-1 at 10.0 A g^-1. Moreover, a stable capacity of 405 mAh g^-1 after 3200 cycles can still be achieved, even at a large current density of 5.0 A g^-1. When coupled with LiMn₂O₄ (LMO) cathode, the LMO [Formula: see text] MnO@GS/CNT full cell characterizes an excellent cycling stability and rate capability, indicating the promising application of MnO@GS/CNT anode in the next-generation LIBs.

Highly durable and cycle-stable lithium storage based on MnO nanoparticle-decorated 3D interconnected CNT/graphene architecture

To accommodate huge volume change and boost the inferior electrochemical reaction kinetics of manganous oxide anodes for lithium-ion batteries, a unique 3D porous CNT/graphene-MnO architecture has been synthesized, with MnO nanoparticles homogeneously decorated on 3D interconnected CNT/graphene (3DCG) conductive networks. This porous 3DCG matrix with its abundant open pores and large surface area can provide efficient channels for fast charge transport and allow full contact between the electrode and electrolyte, leading to improved electrochemical activity. The robust 3D architecture offers abundant stress buffer space to tolerate volume expansion and ensures robust structural stability during the electrochemical processes. The synergistic effect between components endows the 3DCG/MnO electrodes with excellent electrochemical performance, retaining a high specific capacity of 526.7 mA h g-1 at 2.0 A g-1 with 98% capacity retention over 1400 cycles. This work provides a promising route for the practical application of fast and durable lithium-ion batteries and suggests insights for rational structural designs with other transition metal oxides.

Si@void@C Nanofibers Fabricated Using a Self-Powered Electrospinning System for Lithium-Ion Batteries

In recent years, research in lithium-ion batteries (LIBs) has been focused on improving their performance in various ways, such as density, capacity, and lifetime, but little attention has been paid to the energy consumption cost in the manufacturing process. Herein, we report an energy-efficient preparation method of anode materials for LIBs based on a self-powered electrospinning system without an external power source, which consists of a rotatory triboelectric nanogenerator (r-TENG), a power management circuit, and an electrospinning unit. By harvesting kinetic energy from a handle rotation, the r-TENG is able to fully power the electrospinning system to fabricate nanofibers for LIBs. The as-obtained Si@void@C nanofibers present outstanding cyclic performance with a discharge capacity of 1045.2 mA h g^-1 after 100 cycles and 88% capacity retention, along with an excellent high rate capacity of 400 mA h g^-1 at a current density of 5 A g^-1, which are completely comparable with those made by commercial electrospinning equipment. Our study demonstrates an innovative and distinct approach toward an extremely low-cost preparation procedure of electrode materials, leading to a great breakthrough for the LIB production industry.

Free-anchored Nb2O5@graphene networks for ultrafast-stable lithium storage

Orthorhombic Nb₂O₅ (T-Nb₂O₅) has structural merit but poor electrical conductivity, limiting their applications in energy storage. Although graphene is frequently adopted to effectively improve its electrochemical properties, the ordinary modified methods cannot meet the growing demands for high-performance. Here, we demonstrate that different graphene modified routes play a vital role in affecting the electrochemical performances of T-Nb₂O₅. By only manual shaking within one minute, Nb₂O₅ nano-particles can be rapidly adsorbed onto graphene, then the free-anchored T-Nb₂O₅@graphene three-dimensional networks can be successfully prepared based on hydrogel method. As for the application in lithium-ion batteries, it performs outstanding rate character (129 mA h g^-1 (25C rate), 110 mA h g^-1 (50C rate) and 90 mA h g^-1 (100C rate), correspond to 79%, 67% and 55% capacity of 0.5C rate, respectively) and excellent long-term cycling feature (∼70% capacity retention after 20000 cycles). Moreover, it still maintains similar ultrafast-stable lithium storage performances when Cu foil is substituted by Al foil as current collector. In addition, relevant kinetics mechanisms are also expounded. This work provides a versatile strategy for the preparation of graphene modified Nb₂O₅ or other types of nanoparticles.

Highly Porous Mn3 O4 Micro/Nanocuboids with In Situ Coated Carbon as Advanced Anode Material for Lithium-Ion Batteries

The electrochemical performance of most transition metal oxides based on the conversion mechanism is greatly restricted by inferior cycling stability, rate capability, high overpotential induced by the serious irreversible reactions, low electrical conductivity, and poor ion diffusivity. To mitigate these problems, highly porous Mn₃ O₄ micro/nanocuboids with in situ formed carbon matrix (denoted as Mn₃ O₄ @C micro/nanocuboids) are designed and synthesized via a one-pot hydrothermal method, in which glucose plays the roles of a reductive agent and a carbon source simultaneously. The carbon content, particle size, and pore structure in the composite can be facilely controlled, resulting in continuous carbon matrix with abundant pores in the cuboids. The as-fabricated Mn₃ O₄ @C micro/nanocuboids exhibit large reversible specific capacity (879 mAh g^-1 at the current density of 100 mA g^-1 ) as well as outstanding cycling stability (86% capacity retention after 500 cycles) and rate capability, making it a potential candidate as anode material for lithium-ion batteries. Moreover, this facile and effective synthetic strategy can be further explored as a universal approach for the synthesis of other hierarchical transition metal oxides and carbon hybrids with subtle structure engineering.

High-capacity and long-life lithium storage boosted by pseudocapacitance in three-dimensional MnO-Cu-CNT/graphene anodes

Boosting the lifespan of MnO-based materials for future lithium ion batteries is one of the primary challenges due to the intrinsic low ionic conductivity and volume expansion during the conversion process. Herein, superior lithium storage in a new quaternary MnO-Cu-CNT/graphene composite has been demonstrated, which is boosted by pseudocapacitance benefitting from the three-dimensional CNT/graphene and nanosized Cu additives. Such architecture offers highly interpenetrated porous conductive networks in intimate contact with MnO-Cu grains and abundant stress buffer space for effective charge transport upon cycling. The ternary MnO-Cu-graphene electrode contributes an ever-increasing reversible capacity of 938.3 mA h g^-1 after 800 cycles at 0.8 A g^-1. In particular, the quaternary MnO-Cu-CNT/graphene electrode demonstrates a high specific capacity of 1334 mA h g^-1 at 0.8 A g^-1 after 800 cycles and long lifetimes of more than 3500 cycles at 5 A g^-1 with a capacity of 557.9 mA h g^-1 and close-to-100% Coulombic efficiency. The boosted pseudocapacitive lithium storage together with the simple material fabrication method in a MnO-Cu-CNT/graphene hybrid could pave the way for the development of high-capacity and long-life energy storage devices.

Formation of Mn–Cr mixed oxide nanosheets with enhanced lithium storage properties

Novel carbon-free Mn₂O₃/MnCr₂O₄ hybrid nanosheets are synthesized. As an anode for lithium-ion batteries, they deliver a wonderful electrochemical performance.

Preparation of porous MoP-C microspheres without a hydrothermal process as a high capacity anode for lithium ion batteries

Molybdenum phosphide (MoP) is one promising electro-active material for lithium ion batteries (LIBs) in view of its high theoretical capacity.

Graphene-oxide-wrapped ZnMn2O4 as a high performance lithium-ion battery anode

Cation distribution between tetrahedral and octahedral sites within the ZnMn₂O₄ spinel lattice, along with microstructural features, is affected greatly by the temperature of heat treatment. Inversion parameters can easily be tuned, from 5%-19%, depending on the annealing temperature. The upper limit of inversion is found for T = 400 °C as confirmed by x-ray powder diffraction and Raman spectroscopy. Excellent battery behavior is found for samples annealed at lower temperatures; after 500 cycles the specific capacity for as-prepared ZnMn₂O₄ is 909 mAh g^-1, while ZnMn₂O₄ heat-treated at 300 °C is 1179 mAh g^-1, which amounts to 101% of its initial capacity. Despite the excellent performance of a sample processed at 300 °C at lower charge/discharge rates (100 mAh g^-1), a drop in the specific capacity is observed with rate increase. This issue is solved by graphene-oxide wrapping: the specific capacity obtained after the 400th cycle for graphene-oxide-wrapped ZnMn₂O₄ heat-treated at 300 °C is 799 mAh g^-1 at a charge/discharge rate 0.5 A g^-1, which is higher by a factor of 6 compared to samples without graphene -oxide wrapping.