Dual metal oxides interconnected by carbon nanotubes for high-capacity Li- and Na-ion batteries

Sb₂O₃ and Co₃O₄ as potential anode materials for Li- and Na-ion batteries exhibit high theoretical capacities and excellent electrochemical stability; however, volume expansion, exfoliation and poor electronic conductivity affect the electrochemical performance to some extent. Here, we design dual metal oxide hybrid composites by one- and two-step solvothermal processes, in which Co₃O₄ with Sb₂O₃ traps Li⁺ ions and carbon nanotubes (CNTs) as a network guarantee for electron transport. Sb₂O₃/CNTs/Co₃O₄ and Sb₂O₃/Co₃O₄/CNTs composites exhibit different morphologies, particles sizes and Li⁺/Na⁺ storage performance. The Sb₂O₃/CNTs/Co₃O₄ composite showes initial capacities of 1790 and 1450 mAh g^-1 after 100 cycles as the anode for a Li-ion battery. The capacity retention of the Sb₂O₃/Co₃O₄/CNTs composite is better than the Sb₂O₃/CNTs/Co₃O₄ composite for Na-ion storage. With charge/discharge cycles, the transition reaction of Sb₂O₃ and Co₃O₄ to Sb and Co repeats, leading to a homogenous distribution in CNTs and further growth of the nanoparticles. This work provides new insights into the design of high-capacity anodes for Li- and Na-ion storage by adjusting their composition and morphology.