Zinc/Nickel-Doped Hollow Core–Shell Co₃O₄ Derived from a Metal–Organic Framework with High Capacity, Stability, and Rate Performance in Lithium/Sodium-Ion Batteries

Transition-metal oxides are one of the most promising anode materials for energy storage in lithium- and sodium-ion batteries (LIBs and NIBs, respectively). To improve the electrochemical performance of metal oxides (e.g., Co₃O₄), such as capacity and cyclability, a convenient strategy (with a metal–organic framework as a template) is introduced to generate Zn- or Ni-doped Co₃O₄. The obtained hollow core–shell nanosized Co₃O₄ (denoted as Zn/Ni-Co-Oxide) derived from pyrolyzing zinc or nickel co-doped ZIF-67 (Co(mIm)₂; mIm=methylimidazole) shows a drastically enhanced capacity of 1300 mAh g⁻¹ at a high current density of 5000 mA g⁻¹, compared with that of pristine cobalt oxide (800 mAh g⁻¹) in LIBs. A zinc-doped Zn-Co-Oxide demonstrates a stable capacity of 1600 mAh g⁻¹ at 1000 mA g⁻¹ for 700 cycles and an excellent performance in full coin cells (cycled with LiNi_0.5Co_0.3Mn_0.2O₂). Moreover, NIB tests show a stable capacity of 300 mAh g⁻¹ for more than 250 cycles.