Quantification of Pseudocapacitive Contribution in Nanocage-Shaped Silicon-Carbon Composite Anode

Abstract

Pseudocapacitive materials have been highlighted as promising electrode materials to overcome slow diffusion-limited redox mechanism in active materials, which impedes fast charging/discharging in energy storage devices. However, previously reported pseudocapacitive properties have been rarely used in lithium-ion batteries (LIBs) and evaluation methods have been limited to those focused on thin-film-type electrodes. Hence, a nanocage-shaped silicon-carbon composite anode is proposed with excellent pseudocapacitive qualities for LIB applications. This composite anode exhibits a superior rate capability compared to other Si-based anodes, including commercial silicon nanoparticles, because of the higher pseudocapacitive contribution coming from ultrathin Si layer. Furthermore, unprecedent 3D pore design in cage shape, which prevents the particle scale expansion even after full lithiation demonstrates the high cycling stability. This concept can potentially be used to realize high-power and high-energy LIB anode materials.