Temperature and stress-resistant solid state electrolyte for stable lithium-metal batteries

Despite inherent good safety and high energy density, solid state batteries readily suffer from sudden capacity fading that stems from the structure deterioration under external/internal stress and temperature change. Herein, a temperature and stress-resistant solid-state battery is developed by utilizing a composite electrolyte, synthesized by chemically grafting a self-healing polyurethane-urea disulfide polymer (PUS) onto Li7P3S11 via nucleophilic addition. In this way, Li7P3S11 and PUS are kept in close contact ensuring their uniform distribution throughout the composite electrolyte. These chemically bound interfaces restrict PUS chain movement under cooling-heating cycling, and thus avoid phase separation in the composite electrolyte that often occurs in traditional systems. This ensures an unprecedented resilience of both capacity and conductivity (stable at 5 × 10−4 S cm−1) to temperature fluctuations. Moreover, the dynamic S-S bond in PUS provides a fast self-healing rate of the composite electrolyte subjected to mechanical damage (100% current recovery within 3 min). The Li|PUS-LPS|LiFePO4 full cell also displays super high post-damage capacity recovery of 95.1% and excellent cycling stability (95.4% capacity retention after 200 cycles).