PNNL

Abstract

O3-layered metal oxides are promising cathode materials for high-energy Na-ion batteries (SIBs), which, however, suffer from fast capacity fade and poor air stability. Here, we develop a high-performance and air stable O3-NaNi0.68Mn0.22Co0.10O2 cathode for SIBs towards practical applications by controlling the cathode surface phase transition and chemical reactivity. The cathode, by suppressing the formation of rock salt surface layer with advanced electrolyte, can deliver a high specific capacity of ~196 mAh g-1 and demonstrate >80% capacity retention over 1000 cycles. With appropriate polymer coating to mitigate the chemical reaction with moisture, the cathode achieves good air stability while maintains its original electrochemical performance. NaNi0.68Mn0.22Co0.10O2-hard carbon full-cells with practical loading (>2.5 mAh cm-2) and lean electrolyte demonstrate ~91% capacity retention after 200 cycles. This work represents a significant leap in the SIB development and brings new insights to the development of advanced layered metal oxide cathodes for alkaline-ion batteries.