Lithium-ion-conductive sulfide polymer electrolyte with disulfide bond-linked PS4 tetrahedra for all-solid-state batteries

Due to their high conductivity and interface formability, sulfide electrolytes are attractive for use in high energy density all-solid-state batteries. However, electrode volume changes during charge-discharge cycling typically cause mechanical contact losses at the electrode/electrolyte interface, which leads to capacity fading. Here, to suppress this contact loss, isolated PS 4 3- anions are reacted with iodine to prepare a sulfide polymer electrolyte that forms a sticky gel during dispersion in anisole and drying of the resulting supernatant. This polymer, featuring flexible (–P–S–S–) n chains and enhanced solubility in anisole, is applied as a lithium-ion-conductive binder in sheet-type all-solid-state batteries, creating cells with low resistance and high capacity retention. Solid polymer electrolytes that are resistant to volume changes during charge-discharge cycling are important for all-solid-state batteries. Here, a sulfide polymer electrolyte is fabricated by reacting PS 4 3− anions with iodine, obtaining cells with low resistance and high capacity retention.