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, Na_0.44MnO₂ has attracted the most attention because of its cost effectiveness and structural stability. However, the low initial charge capacity for Na-poor Na_0.44MnO₂ hinders its practical applications. Herein, we developed a facile chemical presodiated method using sodiated biphenly to transform Na-poor Na_0.44MnO₂ into Na-rich Na_0.66MnO₂. After presodiation, the initial charge capacity of Na_0.44MnO₂ 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.