Study of Li-Si Alloy Composition for Anode Materials in Sulfide-Based All-Solid-State-Batteries

Lithium alloys are promising anode materials with high specific capacity for all-solid-state-batteries (ASSBs). In this study, ASSBs were fabricated by consisting of Li-Si alloy anode, sulfide electrolytes and sulfur composite cathode. During discharge-charge cycles, changes in polarization resistance in the anode and cathode were separately traced using three-electrode system of an embedded Indium reference electrode in ASSBs. As de-alloying and alloying in Li-Si anode, Li distribution and phase changes were investigated using x-ray diffraction, optical microscopy and Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMs). A half-cell was fabricated by using Indium foil as a counter electrode to study the Li ion diffusion coefficient in Galvanostatic Intermittent Titration Technique(GITT). It is observed that Li composition (22:5 ~ 1:1) in Li-Si alloy anode affected the chemo-mechanical stability and volume expansion behavior in ASSBs, which were associated with the redox behavior of sulfide solid electrolyte.