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

Abstract

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.