Improvement of electrochemical performance of NaCrO2 by removing electrochemically inert sodium ions

In this study, we used ultrasonic treatment and ethanol cleaning (UE treatment) to remove a small amount of electrochemically inert Na+ ions from the surface lattice of NaCrO2 to obtain a modified material NaCrO2-UE. Its electrochemical properties were significantly improved. At a rate of 10C, the initial discharge capacity of NaCrO2-UE was 115.8 mAh/g, and the retention rate was 87.0 % after 500 cycles. Moreover, at a higher rate of 40C, it could deliver a discharge capacity of 111.4 mAh/g. In addition, the discharge voltage plateau of NaCrO2-UE reached 2.91 V, while the discharge voltage plateau of pristine NaCrO2 was 2.78 V.