Cathode material stability enhancement for layered manganese-based sodium-ion batteries by doping titanium

Abstract

The cathode material of layered manganese-based sodium-ion batteries has attracted the extensive attention of industries due to its simple preparation, low cost, and high theoretical specific capacity. However, a quick decay of the specific capacity caused by an irreversible redox reaction still is under investigation. In this paper, titanium doping is used to improve the structural stability of the cathode material. XRD, EDS, XPS, SEM, and TEM were employed to characterize the morphology and structure of cathode material doping by titanium. The pre- and post-doping of titanium are investigated and discussed. The XPS results demonstrated that the modified cathode material after doping titanium (Na_0.77Ni_0.23Mn_0.77Ti_0.02O₂) shows stronger Mn–O bonds and higher energy storage performance. Furthermore, the electrochemical performances of batteries using the modified cathode material are evaluated. The first discharge specific capacity is measured at 202.6 mA h g⁻¹ under a 25 mA g⁻¹ current density and an 85.9% capacity retention rate under 254 mA g⁻¹ current density after 200 cycles.