Delicate fabrication of ZnO/ZnCo2O4 heterojunction HoMSs as anodes for lithium-ion batteries with high rate capability

Abstract

The high specific capacity of metal oxides cannot cover up their low electron and ion diffusion rate and large volume expansion as anodes of lithium-ion batteries. Hollow multi-shelled structures (HoMSs) could provide more active sites for redox reactions and shorten the ion diffusion path. The free space between the shells could relieve volume expansion during the charging–discharging processes, which ensures outstanding cycling stability. Furthermore, constructing heterojunctions would promote the fast electron diffusion rate at the interface to achieve excellent rate capability. Therefore, designing HoMSs composed of metal oxide heterojunctions can improve the cycling stability and rate capability of anodes for lithium-ion batteries. Herein, ZnO/ZnCo₂O₄ heterojunction HoMSs were synthesized by adjusting the combustion rate of carbon spheres and the crystallization rate of metal oxides. As expected, the ZnO/ZnCo₂O₄ heterojunction hollow quintuple-shelled sphere exhibited a high specific capacity of 1244.5 mA h g⁻¹ at a current density of 0.2 A g⁻¹. Meanwhile, even after 100 cycles at 0.5 A g⁻¹ and 1000 cycles at 5.0 A g⁻¹, specific capacities of 1242.8 and 561.6 mA h g⁻¹ were maintained, respectively. This approach could provide inspiration for designing HoMS materials with high rate capability for lithium-ion batteries.