Water-mediated synthesis of halide solid electrolyte and conducting polymer hybrid materials for all solid-state batteries

Abstract

Over the last decades, we have seen an increase in the number of new materials that can be incorporated into all-solid-state batteries (ASSBs). Halide solid electrolytes have attracted significant attention due to their superior stability against oxide-based cathode active materials when compared to sulfide-based solid electrolytes. Nonetheless, the dynamicity of interparticle contact during cycling in ASSBs hinders their stability and performance. Therefore, inactive materials such as electronically conductive additives and polymer binders are needed to compensate the contact-loss reducing the energy density of the resulting cells. Here, we present an aqueous approach for the preparation of halide solid electrolyte-conductive polymer hybrid composites with Li3InCl6 and poly(3,4-ethylendioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) in one-pot. The resulting composites combine the properties of a solid electrolyte with a conductive additive and a binder together with into a single hybrid material. Together with other analytical techniques, Kelvin Probe Force Microscopy (KPFM) imaging showed a successful synthesis of the hybrid materials and revealed that the conductive polymer (CP), namely PEDOT:PSS, is located at the surface/grain of the Li3InCl6. Upon incorporation of such composites in sulfide solid-state half-cells with lithium nickel manganese cobalt oxide (NMC) cathode active material (CAM) we observe an increase in the partial electronic transport of the catholytes with increasing CP content, which correlates an increase in the initial discharge capacities. This study sets the stage to explore the preparation of multi-functional catholytes without the necessity of organic solvents, extremely high temperatures or special environments.