P2-Type Layered Na0.75Ni1/3Ru1/6Mn1/2O2 Cathode Material with Excellent Rate Performance for Sodium-Ion Batteries

Layered oxides acting as sodium hosts have attracted extensive attention due to their structural flexibility and large theoretical capacity. However, the diffusion of Na ions always presents sluggish kinetics due to the larger ionic radius sand mass of Na compared to Li. Herein, we report a P2-type layered cathode material, namely, Na0.75Ni1/3Ru1/6Mn1/2O2 with superfast ion transport, where the Na+ diffusion coefficient is calculated mainly in the region of 10–10 to 10–11 cm2 s–1 during the charge and discharge process. The electrochemical tests also show that this cathode material exhibits a high capacity of 161.5 mAh g–1, excellent rate performance (when the rate increases from 0.2C–10C, the capacity retention is 74%), and outstanding cyclic performance (maintaining 79.5% for 500 cycles even at a high rate of 10C). Our findings provide new insights for the design of the open framework for fast transport of Na and promote the high-power performance of sodium-ion batteries (SIBs).