Comparative Analysis of Aqueous and Nonaqueous Polymer Binders for the Silicon Anode in All‐Solid‐State Batteries

Abstract

Silicon (Si) is anticipated to become one of the most promising anode materials for high‐energy‐density solid‐state battery (SSB) applications owing to its high theoretical specific capacity and low working potential. This work compares the electrochemical behavior of slurry‐cast electrodes in Si|Li6PS5Cl|In/InLi cells, with micron‐sized Si particles (≥99% active electrode material content) and polyacrylic acid (PAA) or polyvinylidene fluoride (PVDF) serving as active material and aqueous/nonaqueous model binder, respectively. The cycling stability of Si‐PVDF cells is found to decrease with increasing binder content (accelerated capacity fade), whereas the Si‐PAA cells show more or less the opposite trend. However, they exhibit a similar performance when using 0.5 wt% binder, with specific capacities of ≈850 mAh g−1 (for −0.51–0.11 V vs In/InLi) and high capacity retention depending on the cutoff potentials. This result suggests that PVDF can be substituted for by PAA in Si anodes for SSBs, thereby potentially decreasing cost and environmental impact.

Keywords

• cutoff potential
• polymer binders
• silicon anodes
• solid-state batteries
• thiophosphate solid electrolytes