Heavy Atom-Induced Spin-Orbit Coupling to Quench Singlet Oxygen in a Li-O2 Battery.

Li-O2 batteries have aroused considerable interest due to high theoretical energy density; however, the singlet oxygen (1O2) generated in both discharge and charge processes induces severe parasitic reactions and leads to their low round-trip efficiency and poor rechargeability. Herein, a universal heavy atom-induced quenching mechanism is proposed to suppress 1O2 and related side reactions. Br in tris(4-bromophenyl)amine (TBPA) induces strong heavy atom-induced spin-orbit coupling (SOC), enhancing the interaction between the spin angular momentum and the orbital angular momentum of the electron. It enables TBPA to capture electrophilic 1O2 to form a singlet complex and then effectively drives the spin-forbidden spin-flip process to form a triplet complex. This accelerates the conversion of 1O2 to ground-state 3O2 through a heavy atom-induced intersystem crossing mechanism, and it efficiently eliminates its attack on organic solvents and carbon cathodes. These endow the Li-O2 battery with reduced overvoltages and prolonged lifespan for over 350 cycles when coupled with a RuO2 catalyst. This work highlights the heavy atom-induced SOC to quench 1O2 in oxygen evolution reaction-related devices.