Rational design of NiCo₂O₄/g-C₃N₄ composite as practical anode of lithium-ion batteries with outstanding electrochemical performance from multiple aspects

The spinel oxide NiCo₂O₄ is regarded as a desirable electrode material in lithium-ion batteries with high performance due to its better electrochemical activity and higher capacity compared to traditional simple oxides. However, lithium-ion batteries with this conversion reaction anode still suffer from low initial Coulombic efficiency accompanied by the generation of solid electrolyte interface layer. Herein, a facile strategy is proposed to couple nanoparticulate NiCo₂O₄ with g-C₃N₄, which effectively reduces solid electrolyte interface formation and leads to a high initial Coulombic efficiency. Various characterization techniques confirm that NiCo₂O₄ nanoparticles grow homogeneously on g-C₃N₄ nanosheets. This NiCo₂O₄/g-C₃N₄ hybrid, as an anode material for lithium-ion batteries, can reach an initial Coulombic efficiency of 84.5%, which is attributed to low interfacial surface area and high discharge potential of electrodes. Owing to the synergistic effect in the NiCo₂O₄/g-C₃N₄ hybrid, excellent reversible capacities of 1252 and 476 mAh g⁻¹ are maintained at respective current densities of 100 and 500 mA g⁻¹ after 100 cycles. The highly reversible lithium storage is a result of high NiCo₂O₄ electrode performance, unique layered structure, and excellent g-C₃N₄ properties.