High-Performance B-Doped Na0.44MnO2 Cathode Materials for Sodium-Ion Batteries

Na0.44MnO2 (NMO) is a promising cathode material for sodium-ion batteries (SIBs) due to its unique tunnel structure and derived sodium storage property. In this study, we prepared the doped cathode material Na0.44Mn0.98B0.02O2(NMOB0.02) and observed that introducing optimal B improves electrochemical stability and air stability. The prepared Na0.44Mn0.98B0.02O2 material releases an initial reversible specific capacity of 100.5 mAh g–1 at 0.2 C (1 C = 120 mA g–1). Compared with the undoped material, the capacity retention rate increases from 69.8 to 86.8% after 350 cycles at 1 C, and this parameter evaluated at 50 °C increases from 63.6 to 88.9% after 100 cycles at 1 C. Both electrochemical impedance spectra (EIS) and GITT test results show that the proper B doping is capable of promoting the diffusion of Na+, and the in situ X-ray diffraction (XRD) technique was employed to demonstrate the high reversibility of NMOB0.02 during the charge and discharge processes. This study provides a helpful reference for other researchers to design and optimize cathode materials for sodium-ion batteries with excellent thermal stability.