Dry approach production of a garnet solid electrolyte membrane for lithium batteries

Abstract

Garnet-based solid electrolytes endow lithium-ion batteries with higher energy density and safety as compared to conventional lithium-ion batteries. Dry electrode technology is a promising method to prepare garnet electrolyte membranes. Nevertheless, the high hardness of garnet particles is a huge obstacle before suitable garnet electrolyte membranes can be produced using this technology. Herein, a dry electrode-based method incorporating pre-mixing and mechanized grinding processes was developed and evaluated for use in preparing garnet electrolyte membranes. Notably, use of the proposed method resulted in the successful production of ultra-thin garnet-based electrolyte membranes (∼20 μm thick). The PTFE–LLZTO-3 electrolyte membrane, which contained 3% polytetrafluoroethylene (PTFE) and 97% LLZTO, possessed good Li⁺ conductivity (6.65 × 10⁻⁴ S cm⁻¹), an ultra-high Li⁺ transference number (0.83), and good interfacial compatibility with the Li anode. Moreover, an LFP/PTFE–LLZTO-3/Li battery incorporating the PTFE–LLZTO-3 electrolyte membrane, a LiFePO₄ cathode, and a Li anode, delivered a high discharge capacity of 162 mA h g⁻¹ at a rate of 0.1C and thus provided excellent rate performance and high first-cycle coulombic efficiency (>99%). Taken together, these results suggest that the proposed dry electrode approach is feasible for preparing solid electrolyte membrane lithium battery components to thereby enhance battery performance and safety.