A lithium-sulfur battery includes: a substrate; a composite cathode disposed on the substrate; a solid-state electrolyte disposed on the composite cathode; and a lithium anode disposed on the solid-state electrolyte, such that the composite cathode comprises: active elemental sulfur, conductive carbon, and sulfide electrolyte, and the sulfide electrolyte is uniformly coated on at least one surface of the conductive carbon. A method of forming a composite cathode for a lithium-sulfur battery includes: synthesizing dispersed carbon fiber from cotton to form carbonized dispersed cotton fiber (CDCF) powder; in-situ coating of the CDCF with an electrolyte component to form a composite powder; and mixing active elemental sulfur powder with the composite powder to form the composite cathode.