Composite Solid Electrolyte Including Lithium Iron Phosphate

A composite solid electrolyte () for lithium batteries can include a solid polymer (), a lithium salt () distributed in the solid polymer (), and lithium iron phosphate () distributed in the solid polymer (). A solid state lithium battery cell () can include a composite solid electrolyte layer (), an anode () containing lithium in contact with a first surface of the composite solid electrolyte layer (); and a cathode () in contact with a second surface of the composite solid electrolyte layer (), The composite solid electrolyte layer () can include a solid polymer (), a lithium salt () distributed in the solid polymer N (), and lithium iron phosphate () distributed in the solid polymer ().