Carbon sphere-templated synthesis of porous yolk-shell ZnCo₂O₄ spheres for high-performance lithium storage

Efficient lithium-ion electrodes with impressive long-life cycling and high-rate performance are badly in need for large-scale energy storage systems, but it is challenging as well because of large volume expansion during lithium storage. Here through a facile and general strategy, we construct yolk-shell ZnCo₂O₄ (Y-ZCO) spheres as an efficient anode for LIBs. The method involves a simple solvothermal process and subsequent annealing in air. The as-prepared Y-ZCO spheres reveal a high structural robustness and porous textural property. When acted as electrode material for LIBs, these Y-ZCO spheres show enhanced electrochemical performances. It displays a high specific capacity (1138 mA h g⁻¹ at a current rate of 0.2 A g⁻¹), superior capacity retention, and long-cycling stability (103.5% capacity retention ratio at 0.2 A g⁻¹ for 100 cycles and 92.3% capacity retention ratio at 1 A g⁻¹ for 300 cycles). All these results reveal that the Y-ZCO spheres could be potential anode materials for rechargeable batteries. More importantly, the present route is expedient and facile. It can be expected that the strategy could be spread to prepare other hollow mixed metal oxides with complex interior structures.