Artificial Layer Construction via Cosolvent Enables Stable Ni-Rich Cathodes for Enhanced Lithium Storage.

Ni-rich cathodes have recently gained significant attention as next-generation cathodes for lithium-ion batteries. However, their relatively high oxidative surface should be reduced to control the high surface reactivity because the capacity retention decreases rapidly in the batteries. Herein, a simple and effective method to pretreat LiNiMnCoO (NMC811) particles using a cosolvent for improving the battery performance is reported. Imitating the interfacial reaction in practical cells, an artificial layer is created via a spontaneous redox reaction between the cathode and the organic solvent. The artificial layer comprises metal-organic compounds with reduced transition-metal cations. Benefiting from the artificial layer, the cells deliver high capacity retention at a high current density and better rate capability, which might result from the low and stable interfacial resistance of the modified NMC811 cathode. Our approach can effectively reduce the high oxidative surface of most oxide cathode materials and induce a long cyclic lifespan and high capacity retention in most battery systems.