Rate and Cycling Performance of Ti and Cu Doped β-NaMnO₂ as Cathode of Sodium-ion Battery

Sodium-ion batteries are economical and environmentally sustainable energy storage batteries.Among them, β-NaMnO2, a promising sodium-ion cathode material, is a manganese-based oxide with a corrugated laminar structure, which has attracted significant attention due to its structural robustness and relatively high specific capacity.However, it has short cycle life and poor rate capability.To address these issues, Ti atoms, known for enhancing structural stability, and Cu atoms, which facilitate desodiation, were doped into β-NaMnO2 by first-principles calculation and Crystal Orbital Hamilton Population (COHP) analysis.β-NaMn0.8Ti0.1Cu0.1O2exhibits a notable increase in reversible specific capacity and remarkable rate properties.Operating at a current density of 0.2C (1C = 219 mA•g -1 ) and within a voltage range of 1.8-4.0V, the modified material delivered an initial discharge capacity of 132 mAh•g -1 .After charge/discharge testing at current density of 0.2C, 0.5C, 1C, 3C and 0.2C, the material still maintained capacity of 110 mAh•g -1 .The doping of Ti atoms slows down the changes in the crystal structure, resulting in only minimal variations in the lattice constant c/a during the desodiation process.Mn and Cu engage in reversible redox reactions at voltages below 3.0 V and around 3.5 V, respectively.The extended plateau observed in the discharge curve below 3.0 V signifies that Mn significantly contributes to the overall battery capacity.This study provides insights into modifying β-NaMnO2 as a cathode material, offering experimental evidence and theoretical guidance for enhancing battery performance in Na-ion batteries.