Suppressing Cascade Degradation of Lithium-Rich Manganese-Based Cathodes via Singlet Oxygen/Free Radical-Intercepting Binder

Lithium-rich manganese-based layered oxides with high capacity are regarded as highly attractive cathodes for high-energy-density lithium-ion batteries. However, the redox reactions in this cathode usually generate highly reactive singlet oxygen and electrolyte-derived free radicals during high-voltage cycling, which accelerate electrolyte oxidative decomposition and trigger cascading side reactions, leading to a rapid capacity fade. Herein, we report a targeted scavenging strategy employing a hindered amine-functionalized triblock binder to trap singlet oxygen and free radicals, improving the long-cycle stability of the cathodes. The amino groups (N-H) in the hindered amine structure can continuously scavenge singlet oxygen and generate nitroxide radicals (N-O·). Both the parent N-H groups and the resulting N-O· radicals further act as effective traps for free radicals derived from electrolyte decomposition, stabilizing the interfacial stability and transport kinetics of the cathode under 4.8 V. Consequently, the full cell with this binder exhibits a significantly reduced capacity decay rate of 0.175% per cycle over 200 cycles. Our work provides a viable solution for enhancing the cycling stability of lithium-rich manganese-based cathodes, promoting the development of high-energy-density lithium-ion batteries.