Redox Mo-chloro-species-coupled Se oxidation conversion in low-corrosion ionic liquids for fast-kinetics and durable Zn batteries

Despite being promising for high-energy multivalent metal-ion batteries, high-potential and multi-electron-involving Se oxidation conversion usually suffers from rigorous performance decay spawned by sluggish kinetics and active intermediate shuttle/dissolution, especially in ionic liquid (IL) electrolytes. Herein, with a novel low-corrosion ZnCl2-based IL electrolyte, we initially report a dual-conversion strategy by in situ activating redox Mo-chloro species to join Se oxidation conversion of the 1T-MoSe2 cathode towards fast-kinetics and durable Zn batteries. The Mo composition in the MoSe2 cathode experiences an unexpected Mo4+ <-> Mo5+ <-> Mo6+ transition, which merges with the redox conversion (Se2- <-> Se0 <-> Se2+ <-> Se4+) of Se to form low-dissolution complex charged products. Compared with the conventional Se cathode, the introduction of redox Mo-chloro species catalytically boosts the Se conversion kinetics, remarkably enhancing the reversible capacity and rate capability. Consequently, the Zn-MoSe2 battery exhibits a high discharge plateau of similar to 1.47 V, an appreciable capacity of similar to 500 mA h g-1 at 0.2 A g-1, and an ultralong lifespan of over 9000 cycles at 5 A g-1 with excellent capacity retention of 99%. The as-assembled Zn-MoSe2 pouch-cell in the IL electrolyte shows decent power supply capacity and extreme safety even when being used under various abuse scenarios. This dual-conversion strategy of transition metal redox chloro-species-coupled chalcogen conversion chemistry sheds new light on unlocking other advanced metal-chalcogenide batteries. By incorporating in situ-activated redox Mo-chloro species into Se conversion reactions of the 1T-MoSe2 cathode, a Zn-MoSe2 battery with boosted kinetics and ultralong cyclability is initially achieved with a novel low-corrosion ionic liquid electrolyte.