Influence of Co increment on the electrochemical properties of Li_1.2[Mn_0.52−0.5xNi_0.2−0.5xCo_0.08+x]O₂ cathode materials for lithium-ion batteries

Highlights: • The environment friendly C₃H₅NaO₃ is acted as complexing agent to replace NH₃⋅H₂O. • MCO₃ precursor is synthesized via using co-precipitation method. • Mixtures of MCO₃ and LiOH⋅H₂O are calcined to form cathodes with various Co contents. • Lattice parameters c/a ratio for cathode material increases with the Co increment increasing. • Li_1.2[Mn_0.51Ni_0.19Co_0.1]O₂ cathode shows the best electrochemical properties. - Abstract: MCO₃ precursors are synthesized via co-precipitation method using NaCO₃ as the precipitation, and the environment friendly C₃H₅NaO₃ is acted as complexing agent to replace NH₃⋅H₂O. And then the mixtures of MCO₃ precursors and LiOH⋅H₂O are calcined at 950 °C to form Li_1.2[Mn_0.52−0.5xNi_0.2−0.5xCo_0.08+x]O₂ cathode materials with different Co increments. The influence of Co increment on the microstructure and electrochemical properties of Li_1.2[Mn_0.52−0.5xNi_0.2−0.5xCo_0.08+x]O₂ cathode materials has been analyzed. The results show that the c/a ratio for cathode material becomes higher, and then the layered structure becomes better when the Co increment increases. Among them, Li_1.2[Mn_0.51Ni_0.19Co_0.1]O₂ (x = 0.02) shows the best electrochemical properties with the initial discharge capacity of 261.0 mA h g⁻¹, capacity retention of 99.4% (189.9 mA h g⁻¹) after 100 cycles at the charging and discharging current density of 100 mA g⁻¹ and highest discharge capacity of 157.6 mA h g⁻¹ at the discharging current density of 400 mA g⁻¹