Electrochemical Failure Mechanism of Diffusion-Dependent Silicon Anode in Sulfide-based All-Solid-State Batteries

Abstract

Solid electrolyte-free diffusion-dependent silicon (Si) is a highly promising anode for all-solid-state batteries (ASSBs), owing to its exceptional specific capacity and favorable lithiation potential. However, its practical implementation is significantly limited by rapid capacity degradation during cycling. To further elucidate the electrochemical failure mechanisms of Si anodes, this study systematically investigates the influence of particle size and mass loading on their electrochemical performances. The results indicate that mass loading of active material exerts a more pronounced impact on the performance degradation compared to particle size. Utilizing distribution of relaxation times (DRT) analysis derived from in situ electrochemical impedance spectroscopy (EIS), the kinetic behaviors of Si anodes were revealed across multiple time scales. Furthermore, capacity loss in the Si anode was quantified, demonstrating that nearly 50% of the total capacity loss originates from lithium trapping within the Si anode. These findings provide critical insights into the electrochemical fading mechanisms of diffusion-dependent Si anode, offering valuable guidance for optimizing electrode design and enhancing the performance of Si-based ASSBs.