A universal multifunctional rare earth oxide coating to stabilize high-voltage lithium layered oxide cathodes

The interfacial instability and bulk structural degradation of the high-voltage lithium layered oxide (LLO) cathodes make them suffer from severe capacity and voltage decay. Here, a universal multi-electron surface engineering strategy has been developed to conquer the root causes of the instability of LLO. The Gd in Gd2O3 with rich high-orbit extranuclear electrons is selected as an exemplary coating material to enhance the lithium storage properties of the LiNi0.6Co0.05Mn0.35O2 (NCM). On one hand, the Gd2O3 coating tunes the H1-H2 phase transition from a two-phase to quasi single-phase reaction and weakens the harmful H3 phase transition, minimizing the mechanical degradation of NCM. On the other hand, the Gd2O3 coating increases the activation energy of surface lattice oxygen loss and delays the phase transition temperature, inhibiting the oxidative decomposition of electrolyte and harmful interface phase transition and enhancing the thermal stability of the material. Thanks to these benefits, the Gd2O3-coated NCM experiences a weaker discharge median voltage decay after 100 cycles, and an 88.1% capacity retention rate could be achieved after 400 cycles. Furthermore, the generalizability of the multi-electron surface engineering strategy is certified by all rare earth metal oxides with boosted electrochemical performance for NCM.