Unlocking the High Rate Performance of Na0.44MnO2 with a Boron Doping Strategy

As the cathode material of sodium-ion battery, sodium manganese oxide has attracted considerable critical attention due to its abundant resources and low cost. However, due to the disproportionation of manganese, sodium manganese oxide often suffers from significant capacity degradation and low rate performance, which hinders its practical application. Here, the electrochemical performance of Na 0.44 MnO 2 is significantly improved by an appropriate amount of B doping. The Na 0.44 Mn 0.95 B 0.05 O 2 shows outstanding rate capability and excellent cycle performance, which could deliver a capacity of 61.0 mAh g −1 at 60 C and a capacity retention of 84.7% for 400 cycles at 30 C. B doping could effectively improve the electronic/ionic conductivity of Na 0.44 MnO 2 , which has been demonstrated. Graphical B-doped tunnel-type Na 0.44 MnO 2 is synthesized using the sol–gel method. The introduction of B expanded the lattice spacing of tunnel-type Na 0.44 MnO 2 , reduced the resistance for Na-ion transport within the tunnels, and enhanced the material's conductivity. Na 0.44 Mn 0.95 B 0.05 O 2 demonstrates a capacity of 61 mAh g −1 at a high current density of 60 C, showing excellent rate performance.