New Reaction Pathway of Superoxide Disproportionation Induced by a Soluble Catalyst in Li-O Batteries.

Aprotic Li-O battery has attracted considerable interest for high theoretical energy density, however the disproportionation of the intermediate of superoxide (O ) during discharge and charge leads to slow reaction kinetics and large voltage hysteresis. Herein, the chemically stable ruthenium tris(bipyridine) (RB) cations are employed as a soluble catalyst to alternate the pathway of O disproportionation and its kinetics in both the discharge and charge processes. RB captures O dimer and promotes their intramolecular charge transfer, and it decreases the energy barrier of the disproportionation reaction from 7.70 to 0.70 kcal mol . This facilitates the discharge and charge processes and simultaneously mitigates O and singlet oxygen related side reactions. These endow the Li-O battery with reduced discharge/charge voltage gap of 0.72 V and prolonged lifespan for over 230 cycles when coupled with RuO catalyst. This work highlights the vital role of superoxide disproportionation for Li-O battery.