Carbonate-assisted hydrothermal synthesis of porous hierarchical Co₃O₄/CuO composites as high capacity anodes for lithium-ion batteries

Through thermal decomposition of hybrid carbonate (Cu, Co)₂(OH)₂CO₃ precursors synthesized by a simple carbonate-assisted hydrothermal method, porous hierarchical Co₃O₄/CuO composites with different ratios of Co to Cu were successfully fabricated. A cooperative self-assembly effect of different carbonates has been proposed to explain the formation of nanosheets assembled hierarchical (Cu, Co)₂(OH)₂CO₃ precursor. Electrochemical lithium storage properties of all the composites are evaluated as anode materials for lithium-ion batteries. It is found that the ratio of Co to Cu plays a vital role in affecting the morphology, structure and subsequent electrochemical performance of the Co₃O₄/CuO composites. Owing to the superior porous hierarchical structure and synergistic lithium storage effect of both active electrode materials, the Co₃O₄/CuO composites demonstrate higher capacities and enhanced cycling stability compared to pure Co₃O₄ or CuO electrodes. The Co₃O₄/CuO composite (Co: Cu = 6: 1) electrode delivers a high reversible capacity of 1056 mAh g⁻¹ at a current density of 200 mA g⁻¹ for 500 cycles. With the superior electrochemical performance and easy preparation, the porous hierarchical Co₃O₄/CuO composites demonstrate promising application potential as anode materials for next generation high performance LIBs.