Influence of transition metal doping on nano silicon anodes for Li-ion energy storage applications

Silicon is a promising alternative anode material for lithium-ion batteries (LIBs), offering a high theoretical capacity and low working potential versus Li+ /Li. However, massive volume changes during the Li+ charge/ discharge process and the low intrinsic conductivity of Si are limiting factors for its practical applicability in energy storage systems. In this study, transition metal (Mn, Ni)-doped silicon nanoparticles (Si NPs) with different dopant concentrations were prepared using a low-temperature heat treatment approach and studied as anode materials for LIBs. Compared to pure Si anodes, transition metal-doped Si anodes showed improved electrochemical performance. After 100 cycles, 0.5% Mn-and 0.5% Ni-doped Si anodes delivered 2324 mA h g(-1) and 2561mA h g(-1) with 88% and 86% capacity retention, respectively, at 200 mA g(-1) (vs. first reversible capacity). The prepared anodes exhibited a superior rate capability and better Li+ diffusion properties. These significant enhancements in the electrochemical properties are attributed to the metal dopant, which enhances the intrinsic conductivity of the host Si and mitigates volume expansion. Moreover, it provides the required ionic channels for faster Li+ diffusion while reducing the Li+ diffusion length across the host Si. The full cells fabricated from the prelithiated metal-doped Si anodes and commercial LiCoO2 cathodes delivered high energy densities of 371 Wh kg(-1) and 388.5 Wh kg(-1), respectively, and were found to be suitable for Li+ energy storage applications. (c) 2022 Published by Elsevier B.V. CC_BY_NC_ND_4.0

Automated summary

The study finds that transition metal-doped silicon anodes exhibit improved electrochemical performance, including enhanced capacity retention and rate capability. Metal dopants enhance silicon's conductivity, mitigate volume expansion, and provide better Li+ diffusion properties.