Hot Melt Extruded Solid State Battery Components

A method of co-extruding battery components includes forming a first thin film battery component via hot melt extrusion, and forming a second thin film battery component via hot melt extrusion. A surface treatment is applied to a surface region of at least one of the first and second components so that, relative to a remainder of the at least one component, the surface region has at least one of a decreased inter-particle distance, a decreased amount of polymer binder material, and an increased amount of exposed ionically conductive material. The first and second components are fed through a co-extrusion die to form a co-extruded multilayer thin film.