Passivating the Surface of Li-Excess Layered Oxide Cathode Materials through Guided Self-Assembly of Metal Hydroxide Thin Films

Lithium-excess layered oxide (LLO) cathode materials offer hope for lithium-ion batteries with energy densities exceeding 400 Wh kg-1. However, their practical applications have long been hindered by chemical and structural instabilities both in the bulk and at the electrode-electrolyte interface. Here, we report a room-temperature coating method based on the molecular self-assembly of metal precursors guided by the high density of OH groups on a thin, surface-adherent polydopamine (PDA) film deposited on LLO particles. In particular, a nanoscale Zr(OH)4 surface coating significantly improved the cycle performance of a high-capacity LLO cathode (∼300 mAh g-1), which retained more than 82.3% of the initial capacity after 150 charge-discharge cycles (vs 53.7% for the bare LLO). This coating method may be applied to stabilizing other battery cathode materials with aggressive chemistries or operating in extreme potentials.