Introducing an ionic conductive matrix to the cold-sintered Li1.3Al0.3Ti1.7(PO4)3-based composite solid electrolyte to enhance the electrical properties

In the present work, a Polymer-In-Ceramics (PIC) solid electrolyte based on Li1.3Al0.3Ti1.7(PO4)3 (LATP) and PEOn-LiTFSI (poly(ethylene oxide) - lithium bis(trifluoromethanesulfonyl)imide) is obtained via Cold Sintering Process (CSP), at a temperature of 150 °C without any post-heat treatment, this is 900 °C below the traditional sintering temperature. This novel study demonstrates the effect of the Transient Liquid Phase content (TLP) and the composition of the polymeric active filler on the final Composite Solid Electrolyte (CSE) properties, with the sintering process being monitored by in-operando Electrochemical Impedance Spectroscopy (EIS). Firstly, the 15 wt% of TLP is stated as the optimal liquid content based on the electrical answer and workability. Then, the (EO:Li+) molar ratio is studied from (1:1) to (8:1). The highest ionic conductivity of 1.04·10−4 S cm−1 and a relative density above 98% are achieved at room temperature when the TLP content is 15 wt% and the molar ratio (2:1), with the LATP content set in 90 wt%. Moreover, the activation energy (Ea) is drastically reduced, from 0.388 eV (LATP ceramic electrolyte) to 0.298 eV (PIC electrolyte), with a lithium transference number (tLi+) close to 1. Therefore, this research work proposes a potential solid electrolyte to substitute the traditional liquid electrolytes.