Preparation of new composite electrolytes for solid-state lithium rechargeable batteries by compounding LiTFSI, PVDF-HFP and LLZTO

The addition of Li 7 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) particles to polymer electrolytes can reduce the crystallinity of polymer materials, promote the migration of lithium ions, and then improve the ionic conductivity of polymer solid electrolytes. Oxide-polymer composite solid electrolytes with different contents of LLZTO were prepared from Lithium bis(trifluoromethylsulphonyl)imide (LiTFSI), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and LLZTO powder as raw materials. The study has found that the solid electrolyte with 15 wt% LLZTO has higher ionic conductivity and mechanical strength, and has a wider electrochemical window (5.5V). The prepared composite cathode electrode/solid electrolyte/composite anode electrode solid-state lithium ion battery has a charge-discharge specific capacity of 179.56 mAh/g and 146.73 mAh/g for the first cycle, the coulombic efficiency is of 84%, and the discharge capacity retention rate after 30 cycles is above 94%. In addition, the change of impedance before and after the cycle is small, showing good interface stability.