Ultrathin Li7La3Zr2O12@PAN composite polymer electrolyte with high conductivity for all-solid-state lithium-ion battery

Composite polymer electrolyte is promising in future lithium-ion battery due to its high safety, easy-processing feature and electrochemical stability. However, it is still a great challenge to obtain the electrolyte with both low thickness and high conductivity. In this work, we synthesize a ~25 μm thin electrolyte membrane with the Li 7 La 3 Zr 2 O 12 -embedded polyacrylonitrile-based fiber as the 3D backbone and the in-situ polymerized gel electrolyte as the fillers. The electrolyte with the multi-dimensional lithium ion conducting channels exhibits a high conductivity of 1.60 × 10 − 3  S·cm − 1 at 25 °C. The wide electrochemical window of 4.5 V vs. Li/Li + enables the electrolyte to match with high voltage cathode materials. The Li||Li symmetric cell with the electrolyte shows a high cycling stability with more than 350 h at a current density of 0.1 mA·cm − 2 . In addition, the solid-state LiFePO 4 ||Li full cell has a stable charge-discharge cycle at 25 °C. This thin electrolyte can be used in lithium-ion batteries to improve energy density . The method of preparing thin composite polymer electrolyte membrane can also be extended to other polymer-filler systems.