Three-dimensional Li_1.2Ni_0.2Mn_0.6O₂ cathode materials synthesized by a novel hydrothermal method for lithium-ion batteries

Three-dimensional (3D) hierarchical Li-rich Li_1.2Ni_0.2Mn_0.6O₂ microspheres are directly prepared by a novel hydrothermal method without calcination. The preparation procedure involves a co-precipitation process for precursor microspheres and subsequent hydrothermal reaction with different concentration of lithium source at 220 °C. The prepared layered materials are composed of stacked nanorods with the length of 100–200 nm. When used as cathode material of lithium-ion battery, the material synthesized by appropriate concentration of lithium source exhibits remarkable electrochemical performances with an initial discharge specific capacity of 269 mA h g⁻¹ and a first Coulombic efficiency of 82.8% at 0.1 C. Meanwhile, a high reversible specific capacity of 121.3 mA h g⁻¹ can be achieved after 100 cycles at 5 C, revealing the good rate capability. These results demonstrate that the direct hydrothermal method without calcination is an effective and energy-saving approach to synthesize 3D Li-rich cathode materials for lithium-ion batteries.