Anionic redox in a-(Mo3S11)n polymer cathode for all-solid-state Li-ion battery

Lithium-ion battery that consists of a cathode made of (Mo3S11)n polymer and an anode of Li metal exhibits a high gravimetric-capacity, 673.3 mAh g−1. A flexible structure of the (Mo3S11) n polymer enables consecutive redox reactions of the S22− dimer and the Mo atoms. According to X-ray absorption near-edge spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy, the chemical bonds of Mo–S and S–S in the polymer elongate by accepting electrons up to 16, while the Mo–Mo bond does not change much during the redox reactions. Although the polymer cathode is put in a solid-state electrolyte, the S22− dimer that is redoxed by the reaction of S22− + 2e− → 2S2− forms Li–S–Li bonds, which is an origin of the high capacity of the battery. The redox reactions in the (LixMo3S11)n polymer cathode is theoretically confirmed by first principles calculation.