Increasing (010) active plane of P2-type layered cathodes with hexagonal prism towards improved sodium-storage

Na-ion cathode materials with a fast charge and discharge behavior are needed to develop future high-energy sodium-ion batteries (SIBs). However, inevitably complicated phase transitions and sluggish kinetics during insertion and removal of Na+ in P2-type layered transition metal oxides generate structural instability and severe capacity decay. To get rid of such a dilemma, we report a structural optimization strategy to promote P2-type layered transition metal oxides with more (010) active planes as an efficient cathode for SIBs. As a result, as-prepared hexagonal-prism P2-type layered Na0.71Li0.09Mn0.6Co0.16Ni0.16O2 cathode with more (010) active planes delivers a reversible capacity of 120.1 mAh/g at 0.1 C, impressive rate capability of 52.7 mAh/g at 10 C, and long-term cycling stability (capacity retention of 95.6% over 200 cycles). The outstanding electrochemical performance benefited from the unique hexagonal-prism with more (010) active facets, which can effectively shorten the diffusion distances of Na+, increase the Na-ion migration dynamics and nanostructural stability during cycling verified by morphology characterization, Rietveld refinement, GITT, density functional theory calculations and operando XRD.