Anionic Aggregates Induced Interphase Chemistry Regulation toward Wide-Temperature Silicon-Based Batteries

Abstract

Silicon nanoparticles (SiNPs) show great promise as high-capacity anodes owing to their ability to mitigate mechanical failure. However, the substantial surface area of SiNPs triggers interfacial side reactions and solid electrolyte interphase (SEI) permeation during volume fluctuations. The slow kinetics at low temperatures and the degradation of SEI at high temperatures further hinder the practical application of SiNPs in real-world environments. Here, these challenges are addressed by manipulating the solvation structure through molecular space hindrance. The electrolyte enables anions to aggregate in the outer Helmholtz layer under an electric field, leading to rapid desolvation capabilities and the formation of anion-derived SEI. The resulting double-layer SEI, where inorganic nano-clusters are uniformly dispersed in the amorphous structure, completely encapsulates the particles in the first cycle. The ultra-high modulus of this structure can withstand stress accumulation, preventing electrolyte penetration during repeated expansion and contraction. As a result, SiNPs-based batteries demonstrate exceptional electrochemical performance across a wide temperature range from −20 to 60 °C. Moreover, the assembled 80 mAh SiNPs/LiFePO₄ pouch cells maintain a cycling retention of 85.6% after 150 cycles, marking a significant step forward in the practical application of silicon-based batteries.