Impact of Processing Methodology on the Performance of Hybrid Sulfide-Polymer Solid State Electrolytes for Lithium Metal Batteries

Hybrid sulfide-polymer composite electrolytes are promising candidates to enable lithium metal batteries because of their high ionic conductivity and flexibility. These composite materials are primarily prepared through solution casting methods to obtain a homogenous distribution of polymer within the inorganic. However, little is known about the influence of the morphology of the polymer and the inorganic on the ionic conductivity and electrochemical behavior of these hybrid systems. In this study, we assess the impact of processing methodology, either solution processing or solvent-free ball milling, on overall performance of hybrid electrolytes containing amorphous Li 3 PS 4 (LPS) and non-reactive polyethylene (PE). We demonstrate that using even non-polar, non-reactive solvents can alter the LPS crystalline structure, leading to a lower ionic conductivity. Additionally, we show that ball milling leads to a non-homogenous distribution of polymer within the inorganic, which leads to a higher ionic conductivity than samples processed via solution casting. Our work demonstrates that the morphology of the polymer and the sulfide plays a key role in the ionic conductivity and subsequent electrochemical stability of these hybrid electrolytes.