Improved Initial Charging Capacity of Na-poor Na0.44MnO2 via Chemical Presodiation Strategy for Low-cost Sodium-ion Batteries

Sodium-ion batteries(SIBs) are promising for grid-scale energy storage applications due to the natural abundance and low cost of sodium. Among various Na insertion cathode materials, Na0.44MnO2 has attracted the most attention because of its cost effectiveness and structural stability. However, the low initial charge capacity for Na-poor Na0.44MnO2 hinders its practical applications. Herein, we developed a facile chemical presodiated method using sodiated biphenly to transform Na-poor Na0.44MnO2 into Na-rich Na0.66MnO2. After presodiation, the initial charge capacity of Na0.44MnO2 is greatly enhanced from 56.5 mA·h/g to 115.7 mA·h/g at 0.1 C(1 C=121 mA/g) and the excellent cycling stability(the capacity retention of 94.1% over 200 cycles at 2 C) is achieved. This presodiation strategy would open a new avenue for promoting the practical applications of Na-poor cathode materials in sodium-ion batteries.