ZnO/Co3O4 supported on carbon nanotubes as anode materials for high-performance lithium-ion batteries†

Abstract

Metallic oxides show great potential in achieving high specific capacity as electrodes for lithium-ion batteries (LIBs). However, their inherent poor conductivity and significant volume expansion often result in inferior rate performance and reduced stability in electrochemical cycles. Here, we report a composite of ZnO and Co₃O₄ wrapped in carbon nanotubes (denoted as ZnO/Co₃O₄@CNTs) with hierarchically porous architecture via pyrolysis–oxidation of a Zn/Co-zeolitic imidazolate framework (ZIF) precursor. The dual-transition metal oxides can undergo abundant redox and alloying reactions with enhanced redox kinetics, while the CNT layers facilitate electron transfer and mitigate volume expansion. As a result, ZnO/Co₃O₄@CNTs exhibits high electrochemical performance with excellent lithium storage capability and high electronic and ionic diffusion kinetics, making it a promising anode material for LIBs. It achieves a high reversible capacity of 1156 mA h g⁻¹ at a current density of 200 mA g⁻¹ after 200 cycles, with an extremely low capacity degradation rate of about 0.54‰ per cycle.