Cryogenic liquid sculpting of vertically aligned architectures for high-rate silicon anodes

Abstract

Despite its exceptionally high theoretical capacity, which far exceeds that of conventional graphite, the silicon anode suffers from severe volumetric expansion and intrinsically low electrical conductivity, factors that critically hinder its practical application in high-energy Li-ion batteries. To overcome these limitations, a vertically aligned Si@MXene (V-Si@MX) composite electrode was fabricated via directional freezing followed by freeze-drying. This architecture offers unidirectional pathways for ion and electron transport, interconnected pores, and strong interfacial bonding between Si and the MXene host, thereby effectively mitigating volume changes while enhancing charge transport. Electrochemical testing revealed superior performance relative to conventional electrodes, including high-rate capability (delivering about 1500 mAh g−1 at up to 3C), long-term cycling stability, low charge-transfer resistance, and a high Li+ diffusion coefficient. These results demonstrate that vertical structural engineering represents a promising and scalable approach for developing high-performance Si-based anodes.