Polymer-in-ceramic based poly(epsilon-caprolactone)/ceramic composite electrolyte for all-solid-state batteries

Inspired by the concept of polymer-in-ceramic, a composite poly(epsilon-caprolactone) (PCL)/ceramic containing LiTFSI is prepared and investigated as a solid electrolyte for all-solid-state batteries. The composite with the optimum concentration of 45 wt% LiTFSI and 75 wt% Li1.5Al0.5Ge1.5(PO4)(3) (LAGP, NASICON-type structure) exhibits a high ionic conductivity (o-i= 0.17 mS cm(-1)) at 30 degrees C, a transference number of 0.30, and is stable up to 5.0 V. The composite electrolyte is a flexible and self-standing membrane. Solid-state LiFePO4//Li batteries with this composite electrolyte demonstrate excellent cycling stability with high discharge capacity of 157 mA h g (-1), high capacity retention of 96% and coulombic efficiency of 98.5% after 130 cycles at 30 degrees C and 0.1 C rate. These electrochemical properties are better than other PCL-based all solid-lithium batteries, and validate the concept of polymer-in-ceramic by avoiding the drawback of lower conductivity in prior polymer-in-ceramic electrolyte at high concentration of the ceramic. (c) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Automated summary

The composite poly(epsilon-caprolactone) (PCL)/ceramic with LiTFSI as the solid electrolyte shows high ionic conductivity, stability, and excellent cycling performance in solid-state LiFePO4//Li batteries, surpassing other PCL-based solid lithium batteries. This validates the concept of polymer-in-ceramic and overcomes the lower conductivity issue in prior polymer-in-ceramic electrolytes at high ceramic concentrations.