Photochromic Molybdate for Advancing Anode Capacity of Lithium-Ion Battery

Decoupling strategies can effectively enhance lithium-ion battery (LIB) capacity, but suffer from the need for complex equipment, preventing widespread applicability. This work offers, for the first time, a decoupling strategy of electron-transfer photochromism to improve LIB anode performance, without requiring complex equipment. The approach utilizes a new crystalline photochromic molybdate, MV[Mo₉O₂₈] (1, MV = methyl viologen cation) as the LIB anode. After UV irradiation, the initial 1 undergoes electron transfer from O to Mo, accompanied by a color change from colorless to blue and the generation of an ultra-stable charge-separated state with a lifetime of up to 2 years under ambient conditions. The observed capacity increases by 132 ± 14 mAh· g^-1 across various current densities after coloration, along with superior rate performance-retaining 7.6% more capacity than the initial state even at a 100-fold higher current density. Theoretical calculations confirm that the enhanced capacity and rate performance are attributable to the stable charge-separated state. This unprecedented photochromic charge-separated strategy contributes to the exploration of new outstanding anode materials for LIBs.