Synthetic-Clay-Assisted Carrier Transport in Solid Polymer Electrolytes for Enhanced All-Solid-State Lithium Metal Batteries.

Abstract

As a potential alternative to liquid organic electrolytes, solid polymer electrolytes provide good processability and interfacial properties. However, insufficient ionic conductivity limits its further development. To overcome these challenges, we propose the solution of synthetic clay Laponite as a filler in this work. Specifically, the ionic conductivity increases to 1.71×10-4 S cm-1 (60 °C) after adding 5 wt.% of Laponite to the PEO-LiClO4 system. The Laponite surface's negative charge enhances lithium ions dissociation and transport in the electrolyte: the lithium-ion transference number increases from 0.17 to 0.34, and the exchange current density increases from 46.84 μA cm-2 to 83.68 μA cm-2 . The improved electrochemical properties of composite electrolytes improve the symmetric cell's stability to at least 600 h. Meanwhile, the Li||LiFePO4 cells' rate and long-cycle performance are also significantly enhanced. This work's concept of Laponite filler demonstrates a novel strategy to enhance ion transport in polymer-based electrolytes for solid-state batteries.