Extending Si/C Anode Longevity through the Electrode Structure and Composition Design for All-Solid-State Batteries

Numerous volume changes and sluggish kinetics causing irreversible Li-trapping and, consequently, a dramatic capacity decline during cycling are the main challenges facing Si-based anodes in all-solid-state batteries (ASSBs). The incorporation of carbon and Si significantly combats volume change and enhances electronic transport but cannot eliminate Li-trapping. Herein, we partially solve this issue by adding Li_3.75Si alloy into a Si/C composite as a Li reservoir by making either a bilayer electrode or a blended electrode. We demonstrate that the bilayer electrode has superior cycling performance but suffers from soft shorting problems at high current density. This contrasts with the blended electrode, which exhibits a three-fold higher electrode critical current density (CCD), as captured from a self-designed three-electrode cell, but with limited cycling performance. In addition, we present the positive effect of adding a solid electrolyte (SE) to the blended electrode and show that ASSBs having Ni-rich cathodes and SE-containing blended negative electrode can achieve 500 stable cycles at 0.8 mA/cm² and 183 cycles at 3 mA/cm² due to the enhanced ionic/electronic percolations. Altogether, these results provide further insights into achieving long-lifespan, high-rate, and dendrite-free Si-based ASSBs through regulation of the electrode structure and composition.