Single-Crystal α-Fe2O3 with Engineered Exposed (001) Facet for High-Rate, Long-Cycle-Life Lithium-Ion Battery Anode

3D hierarchical self-supporting Bi2Se3-based anode for high-performance lithium/sodium-ion batteries

Bi2Se3 is a promising material for anodes in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) due to its abundance, easy preparation, and high capacity. However, its practical application is hindered by low conductivity and significant volume variation during cycling, leading to poor rate capability and cycling stability. Herein, a novel composite consisting of Bi2Se3 nanoplates deposited on carbon cloth (CC) and encapsulated by reduced graphene oxide (rGO) has been designed and synthesized. The composite structure combines the advantages of the Bi2Se3 nanoplates, CC substrate, and rGO encapsulation, leading to enhanced electrochemical properties. The physical vapor deposition of Bi2Se3 nanoplates onto CC ensures a high loading of active material, while the rGO encapsulation provides a conductive and stable framework for the composite. This synergistic design allows for improved electron and ion transport, as well as efficient accommodation of the volume changes during cycling. In LIBs, the composite demonstrates a high reversible capacity of 467.5 mAh/g at 0.1 A/g after 120 cycles. Moreover, it displays an outstanding rate capability, delivering a capacity of 398.6 mAh/g at 5.0 A/g. Similarly, in SIBs, the composite maintains a reversible capacity of 375.3 mAh/g at 0.1 A/g over 100 cycles and exhibits a high-rate capacity of 286.3 mAh/g at 5.0 A/g. This work represents a significant step forward in addressing the challenges associated with Bi2Se3 as an anode material, paving the way for the development of high-performance LIBs and SIBs.

Hierarchical-Structured Fe2O3 Anode with Exposed (001) Facet for Enhanced Lithium Storage Performance

The hierarchical structure is an ideal nanostructure for conversion-type anodes with drastic volume expansion. Here, we demonstrate a tin-doping strategy for constructing Fe₂O₃ brushes, in which nanowires with exposed (001) facets are stacked into the hierarchical structure. Thanks to the tin-doping, the conductivity of the Sn-doped Fe₂O₃ has been improved greatly. Moreover, the volume changes of the Sn-doped Fe₂O₃ anodes can be limited to ~4% vertical expansion and ~13% horizontal expansion, thus resulting in high-rate performance and long-life stability due to the exposed (001) facet and the unique hierarchical structure. As a result, it delivers a high reversible lithium storage capacity of 580 mAh/g at a current density of 0.2C (0.2 A/g), and excellent rate performance of above 400 mAh/g even at a high current density of 2C (2 A/g) over 500 cycles, which is much higher than most of the reported transition metal oxide anodes. This doping strategy and the unique hierarchical structures bring inspiration for nanostructure design of functional materials in energy storage.

Proton solvent-controllable synthesis of manganese oxalate anode material for lithium-ion batteries

Manganese oxalates with different structures and morphologies were prepared by the precipitation method in a mixture of dimethyl sulfoxide (DMSO) and proton solvents. The proton solvents play a key role in determining the structures and morphologies of manganese oxalate. Monoclinic MnC2O4·2H2O microrods are prepared in H2O-DMSO, while MnC2O4·H2O nanorods and nanosheets with low crystallinity are synthesized in ethylene glycol-DMSO and ethanol-DMSO, respectively. The corresponding dehydrated products are mesoporous MnC2O4 microrods, nanorods, and nanosheets, respectively. When used as anode material for Li-ion batteries, mesoporous MnC2O4 microrods, nanorods, and nanosheets deliver a capacity of 800, 838, and 548 mA h g-1 after 120 cycles at 8C, respectively. Even when charged/discharged at 20C, mesoporous MnC2O4 nanorods still provide a reversible capacity of 647 mA h g-1 after 600 cycles, exhibiting better rater performance and cycling stability. The electrochemical performance is greatly influenced by the synergistic effect of surface area, morphology, and size. Therefore, the mesoporous MnC2O4 nanorods are a promising anode material for Li-ion batteries due to their good cycle stability and rate performance.

Self-Assembled Few-Layered MoS2 on SnO2 Anode for Enhancing Lithium-Ion Storage

SnO₂ nanoparticles (NPs) have been used as reversible high-capacity anode materials in lithium-ion batteries, with reversible capacities reaching 740 mAh·g^-1. However, large SnO₂ NPs do not perform well in charge-discharge cycling. In this work, we report the incorporation of MoS₂ nanosheet (NS) layers with SnO₂ NPs. SnO₂ NPs of ~5 nm in diameter synthesized by a facile hydrothermal precipitation method. Meanwhile, MoS₂ NSs of a few hundreds of nanometers to a few micrometers in lateral size were produced by top-down chemical exfoliation. The self-assembly of the MoS₂ NS layer on the gas-liquid interface was first demonstrated to achieve up to 80% coverage of the SnO₂ NP anode surface. The electrochemical properties of the pure SnO₂ NPs and MoS₂-covered SnO₂ NP anodes were investigated. The results showed that the SnO₂ electrode with a single-layer MoS₂ NS film exhibited better electrochemical performance than the pure SnO₂ anode in lithium storage applications.

Recent Developments of Nanomaterials and Nanostructures for High-Rate Lithium Ion Batteries

Lithium ion batteries have been considered as a promising energy-storage solution, the performance of which depends on the electrochemical properties of each component, including cathode, anode, electrolyte and separator. Currently, fast charging is becoming an attractive research field due to the widespread application of batteries in electric vehicles, which are designated to replace conventional diesel automobiles in the future. In these batteries, rate capability, which is closely linked to the topology and morphology of electrode materials, is one of the determining parameters of interest. It has been revealed that nanotechnology is an exceptional tool in designing and preparing cathodes and anodes with outstanding electrochemical kinetics due to the well-known nanosizing effect. Nevertheless, the negative effects of applying nanomaterials in electrodes sometimes outweigh the benefits. To better understand the exact function of nanostructures in solid-state electrodes, herein, a comprehensive review is provided beginning with the fundamental theory of lithium ion transport in solids, which is then followed by a detailed analysis of several major factors affecting the migration of lithium ions in solid-state electrodes. The latest developments in characterisation techniques, based on either electrochemical or radiology methodologies, are covered as well. In addition, state-of-the-art research findings are provided to illustrate the effect of nanomaterials and nanostructures in promoting the rate performance of lithium ion batteries. Finally, several challenges and shortcomings of applying nanotechnology in fabricating high-rate lithium ion batteries are summarised.

Facet-dependent activity of hematite nanocrystals toward the oxygen evolution reaction

Hematite showed facet-dependent OER activity and its origin was investigated based on in situ UV-vis absorption measurements and theoretical calculations.