Safe solid-state PEO/TPU/LLZO nano network polymer composite gel electrolyte for solid state lithium batteries

Herein, Li7La3Zr2O12 (LLZO) ceramic nano-networks were introduced by electrostatic spinning into the polyethylene oxide (PEO)/thermoplastic polyurethane (TPU)/LiTFSI matrix (PTL) to constitute novel composite solid electrolytes due to the synergy between the nano-networks and the electrolyte matrix. By adjusting the LLZO nanonetwork with different weight ratios (5 wt%, 10 wt%, and 15 wt%) relative to the total weight of the PEO/TPU/LiTFSI/LLZO (PTLL) composite electrolyte, the electrochemical behavior of the gel electrolyte was optimized. When filled with a 10 wt% Li7La3Zr2O12 nano-network, the PTLL has a maximum ionic conductivity of 1.33 × 10−3 S cm−1 at 60 °C and an electrochemical stability window of 5.6 V. Furthermore, the LiFePO4/PTLL/Li battery presents an initial specific discharge capacity of 170 mA h g−1 at 0.1 C. After 100 cycles, it demonstrated superior cycle durability at 0.5 C at 60 °C, representing 96.1 % of the initial capacity. These results indicate that the PTLL electrolyte is a promising candidate for advanced solid state lithium batteries.