On the Influence of Li₃InCl₆-PEDOT:PSS Hybrids in Solid-State Batteries Prepared via an Aqueous One-Pot Approach

Solid-state batteries (SSBs) utilizing halide solid electrolytes (SE) have garnered attention due to their enhanced stability when paired with oxide-based cathode active materials. However, the dynamic interparticle contact during cycling in SSBs poses challenges to their stability and performance. To mitigate this problem, in this study, we present a one-pot, aqueous synthesis of composites that integrate ion conductivity, electron conductivity, and mechanical stability into a single material. The developed composites consist of a halide SE, lithium indium chloride (Li3InCl6), and a conductive polymer (CP), poly(3,4-ethylendioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS). The successful synthesis was verified using spectroscopic, thermal, scattering, and microscopy methods, with Kelvin Probe Force Microscopy (KPFM) demonstrating the distribution of PEDOT:PSS at the grain boundaries between Li3InCl6 particles. Upon incorporating our composite material with lithium nickel manganese cobalt oxide (NMC) cathode active material (CAM) as catholyte, an increase in the partial electronic transport was observed with increasing CP content. A direct correlation between the partial electronic transport of the catholytes and the initial discharge capacities was demonstrated. This study lays the groundwork for the preparation of multi-functional catholytes under more sustainable conditions, without the need for organic solvents, extremely high temperatures, or special environments.