Preparation And Electrochemical Performance Of Nano CuCo₂O₄ Cathode Materials For Li-O₂ Batteries

Aprotic Lithium-Oxygen（Li-O₂）batteries have drawn significant attentions owing to their superior theoretical specific energy.However,research into non-aqueous Li-O₂ batteries is still in the relatively preliminary stages,some key technical problems need to be solved,including low energy conversion efficiency,poor cycle performance,and low energy density for practical application,etc.Recently,researchers have got some achievements in the development of electrolytes and cathode catalysts.Some results indicated that high activity catalysts with porous structure had a strong influence on the enhancement of the performance.Therefore,in this paper,spinel CuCo₂O₄ with different micro-nano structures has been prepared.Then the crystal phases and micrographs of the composites were characterized by XRD,SEM,XPS,BET and so on.Finally,the electrocatalytic performance of spinel CuCo₂O₄ with different structures has been studied as cathode catalyst for Li-O₂ batteries.Nanoscale CuCo₂O₄-Cu O transition metal oxide composites with hollow structure and CuCo₂O₄-Co₃O₄ transition metal oxide composites with core-shell structure were prepared through a nanocasting method by using Zeolitic Imidazolate Frameworks（ZIF-67）as sacrificial templates.Various characterization results indicate that two kinds of materials exhibit a large specific surface area,with a morphology of rhombic dodecahedron.Li-O₂batteries based on two materials were assembled and tested.At a current density of 100 m A g^-1,Li-O₂ batteries with hollow CuCo₂O₄-Cu O and core-shell CuCo₂O₄-Co₃O₄ nanomaterials delivered the discharge specific capacities of 6684 and 6138 m A h g^-1,respectively.At a cut-off specific capacity of 1000 m A h g^-1 at 0.1 m A cm^-2,Li-O₂ batteries with hollow CuCo₂O₄-Cu O and core-shell CuCo₂O₄-Co₃O₄ cathodes can complete 95 and 79 stable cycles,respectively,with the same overpotential about 0.7 V at the first cycle.CuCo₂O₄ nanowire arrays were grown in-situ on the surface of Ni foam via a hydrothermal method.A carbon-free and free-standing CuCo₂O₄@Ni foam cathode was obtained after the process of calcination.Various characterization results show that CuCo₂O₄@Ni foam has a hierarchical porous structure with macroporous and microporous.Li-O₂ batteries based on CuCo₂O₄@Ni foam cathodes show a superior rate performance and good cycle performance.At 0.1 m A cm^-2,Li-O₂ batteries delivered a discharge specific capacity of 13654 m A h g^-1.At a cut-off specific capacity of 500 and 1000 m A h g^-1 at 0.1 m A cm^-2,Li-O₂ batteries can complete 158 and 76 stable cycles,with small overpotentials about 0.28 and 0.55 V at the first cycle.