Dual inorganic fillers synergy for enhancing carrier transport performance in all-solid-state lithium-sulfur battery

PEO-based polymer solid-state electrolytes have low capacity and fast decay due to low ionic conductivity. Here, we design and prepare a composite electrolyte based on a PEO-based solid-state electrolyte plus two inorganic fillers. Adding Li₁₀GeP₂S₁₂ improves the ionic conductivity and activates the sulfur reaction to enhance the rate performance and capacity, and Li_1+xAl_xGe_2-x (PO₄)₃ adsorbs and blocks polysulfides to inhibit the shuttle effect and thus enhance the cycling stability. The electrolyte with 10 wt% inorganic fillers has the highest ionic conductivity and lithium-ion transmission number. The lowest overpotential is in the cycling curve of the symmetric cell, and the most negligible impedance is at different temperatures. It has the highest discharge capacity and optimal coulombic efficiency among all-solid-state lithium‑sulfur batteries, with the highest rate performance of 1126.4 mAh g⁻¹, 931.7 mAh g⁻¹, and 764.6 mAh g⁻¹ at 0.1C, 0.3C, and 0.5C, respectively. Notably, it is stable for 1000 cycles at 2C. What's more, in situ electrochemical impedance spectroscopy indicates that the discharge and charge processes of the battery are reversible. This strategy opens up a viable avenue for the development and practical application of high-capacity solid-state energy storage batteries.