Synergistic Effect of One- and Two-dimensional Connected Coral-like Li$_{6.25}$Al$_{0.25}$La$_3$Zr$_2$O$_{12}$ in PEO-Based Composite Solid State Electrolyte

TL;DR

This paper introduces a novel coral-like Li6.25Al0.25La3Zr2O12 filler in PEO-based electrolytes, significantly enhancing ionic conductivity, mechanical strength, and cycling stability of lithium metal batteries by microstructure tuning.

Contribution

It presents a new coral-like LALZO ceramic filler that improves the electrochemical performance of PEO-based solid electrolytes for lithium batteries.

Findings

Enhanced ionic conductivity and mechanical strength in PEO electrolytes.

Li symmetric cells cycle for 1500 hours without short circuit.

Improved cycling stability of LiFePO4/PLC/Li batteries at different temperatures.

Abstract

As one of the most promising next-generation energy storage device, lithium metal batteries have been extensively investigated. However, the poor safety issue and undesired lithium dendrites growth hinder the development of lithium metal batteries. The application of solid state electrolytes has attracted increasing attention as they can solve the safety issue and partly inhibit the growth of lithium dendrites. Polyethylene oxide (PEO)-based electrolytes are very promising due to their enhanced safety and excellent flexibility. However, PEO-based electrolytes suffer from low ionic conductivity at room temperature and can't effectively inhibit lithium dendrites at high temperature due to the intrinsic semi-crystalline properties and poor mechanical strength. In this work, a novel coral-like Li6.25Al0.25La3Zr2O12 (LALZO) is synthesized to use as an active ceramic filler in PEO. The PEO with LALZO coral (PLC) exhibits increased ionic conductivity and mechanical strength, which leads to the uniform deposition/stripping of lithium metal. The Li symmetric cells with PLC cycle for 1500 h without short circuit at 50 centidegree. The assembled LiFePO4/PLC/Li batteries display excellent cycling stability at both 60 and 50 centidegree. This work reveals that the electrochemical properties of organic and inorganic composite electrolyte can be effectively improved by tuning the microstructure of the filler, such as the coral-like LALZO architecture.