N-doped 3D carbon encapsulating nickel selenide nanoarchitecture with cation defect engineering: An ultrafast and long-life anode for sodium-ion batteries

Transition metal chalcogenides (TMCs) hold great potential for sodium-ion batteries (SIBs) owing to their multielectron conversion reactions, yet face challenges of poor intrinsic conductivity, sluggish diffusion kinetics, severe phase transitions, and structural collapse during cycling. Herein, a self-templating strategy is proposed for the synthesis of a class of metal cobalt-doped NiSe nanoparticles confined within three-dimensional (3D) N-doped macroporous carbon matrix nanohybrids (Co-NiSe/NMC). The cation defect engineering within the developed Co-NiSe and 3D N-doped carbon plays a crucial role in enhancing intrinsic conductivity, reinforcing structural stability, and reducing the barrier to sodium ion diffusion, which are verified by a series of electrochemical kinetic analyses and density functional theory calculations. Significantly, such cation defect engineering not only reduces overpotential but also accelerates conversion reaction kinetics, ensuring both exceptional high-rate capability and extended durability. Consequently, the optimally engineered Co-NiSe/NMC demonstrates a remarkable rate performance, delivering 390 mAh g-1 at 10 A g-1. Moreover, it exhibits an unprecedented lifespan, maintaining a remarkable capacity of 403 mAh g-1 after 1400 cycles and 318 mAh g-1 after 4000 cycles, even at high rates of 1.0 and 2.0 A g-1, respectively. This work marks a substantial advancement in achieving both high performance and prolonged cycle life in sodium-ion batteries.

Double-Walled NiTeSe-NiSe2 Nanotubes Anode for Stable and High-Rate Sodium-Ion Batteries

Electrodes made of composites with heterogeneous structure hold great potential for boosting ionic and charge transfer and accelerating electrochemical reaction kinetics. Herein, hierarchical and porous double-walled NiTeSe-NiSe₂ nanotubes are synthesized by a hydrothermal process assisted in situ selenization. Impressively, the nanotubes have abundant pores and multiple active sites, which shorten the ion diffusion length, decrease Na⁺ diffusion barriers, and increase the capacitance contribution ratio of the material at a high rate. Consequently, the anode shows a satisfactory initial capacity (582.5 mA h g^-1 at 0.5 A g^-1 ), a high-rate capability, and long cycling stability (1400 cycles, 398.6 mAh g^-1 at 10 A g^-1 , 90.5% capacity retention). Moreover, the sodiation process of NiTeSe-NiSe₂ double-walled nanotubes and underlying mechanism of the enhanced performance are revealed by in situ and ex situ transmission electron microscopy and theoretical calculations.

Innovative Materials for Energy Storage and Conversion

The metal chalcogenides (MCs) for sodium-ion batteries (SIBs) have gained increasing attention owing to their low cost and high theoretical capacity. However, the poor electrochemical stability and slow kinetic behaviors hinder its practical application as anodes for SIBs. Hence, various strategies have been used to solve the above problems, such as dimensions reduction, composition formation, doping functionalization, morphology control, coating encapsulation, electrolyte modification, etc. In this work, the recent progress of MCs as electrodes for SIBs has been comprehensively reviewed. Moreover, the summarization of metal chalcogenides contains the synthesis methods, modification strategies and corresponding basic reaction mechanisms of MCs with layered and non-layered structures. Finally, the challenges, potential solutions and future prospects of metal chalcogenides as SIBs anode materials are also proposed.

Topological transformation construction of CoSe2/N-doped carbon heterojunction with three-dimensional porous structure for high-performance sodium-ion half/full batteries

Transition metal selenides have been widely used as anode materials for sodium-ion batteries (SIBs) because of their considerable theoretical capacity and good conductivity. Nevertheless, the volume expansion is a serious...

The rational design of nickel-cobalt selenides@selenium nanostructures by adjusting the synthesis environment for high-performance sodium-ion batteries

Different selenization products (from the perspectives of micromorphology and sodium storage performance) can be obtained via regulating the selenization environment.