Functional Co2SiO4-coated nano-silicon anodes with synergistic buffering and catalytic effects for high-performance lithium-ion batteries

Abstract

Silicon-based materials are considered promising next-generation anode candidates for lithium-ion batteries due to their high theoretical capacity and natural abundance. However, severe volume expansion (∼300 %) during cycling and intrinsically low electrical conductivity significantly hinder their practical applications. Surface coating modification has been recognized as an effective strategy for silicon-based materials. However, common coating materials, such as C and metal oxides, are limited by weak interfacial bonding, insufficient stress buffering, and cracking of the coating layer, making it challenging to construct uniform, durable, and multifunctional shells. This work constructs a double core-shell structured nanocomposite, Si@Co₂SiO₄@C. The composite leverages the buffering and conductive properties of the double shells, as well as the catalytic effect of newly generated Co⁰, to facilitate reversible lithiation of the Li-Si-O compounds, thereby achieving high capacity and long-term cycling stability. As a result, the composite delivers a reversible capacity of 1296 mA h g⁻¹ after 200 cycles at a current density of 300 mA g⁻¹. The role of the double-shell structure is investigated through electrochemical measurements and structure characterization. This double core-shell structure, utilizing a transition metal silicate intermediate layer, provides a novel approach to developing high-performance Si-based anodes with distinct advantages for balancing high capacity and structural stability.