Nitrogen-doped carbon encapsulated hollow ZnSe/CoSe2 nanospheres as high performance anodes for lithium-ion batteries

Abstract

Hierarchical nitrogen-doped carbon encapsulated hollow ZnSe/CoSe₂ (ZnSe/CoSe₂@N–C) nanospheres are fabricated by a convenient solvothermal and selenization approach, followed by a carbonization process. The as-obtained ZnSe/CoSe₂@N–C possesses a multilevel nanoscale architecture composed of a thin carbon shell with a size of around 12 nm and hollow selenide nanoparticles as the core with tiny rough grains and rich voids as the subunits. The robust carbon protective shell and synergistic effect between double metal ions boost the electron and ion transportation as well as promote effective extraction and insertion of lithium ions. Hollow ZnSe/CoSe₂@N–C spheres show high reversible capacity with 1153 mA h g⁻¹ remaining over 100 cycles at 100 mA g⁻¹. In particular, the hollow ZnSe/CoSe₂@N–C spheres show an outstanding cycling stability at a high rate of 2000 mA g⁻¹ with the reversible capacity of up to 966 mA h g⁻¹ remaining after 500 cycles. As an advanced anode, ZnSe/CoSe₂@N–C composite shows remarkable cycling stability and exceptional rate capability in the field of energy storage technologies.