Zeolitic imidazolate framework-derived ZnO polyhedrons wrapped by Co nanoparticle embedded in N-doped carbon for high-performance lithium and potassium storage

Metal oxides are considered as promising anodes for alkali-ion batteries due to their high theoretical capacity and moderate volume expansion. However, they still suffer from the low electrical conductivity and capacity decay, resulting poor rate capability and cyclic stability. In this work, core-shell ZnO polyhedrons coated by Co nanoparticle embedded in N-doped carbon (ZnO@Co/NC) were prepared via a convenient route using zeolitic imidazolate frameworks as precursors. The unique structural design not only synergistically forms a three-dimensional conductive network to promote the transfer and storage of Li⁺/K⁺ ions, but also restrains the volume changes of ZnO polyhedron during repeated lithiation/potassiation processes, contributing to enhanced lithium and potassium storage performances. The ZnO@Co/NC anode delivers 458.3 mAh g⁻¹ after 1000 cycles at an ultrahigh current density of 10 A g⁻¹ with a capacity retention of 95% for LIBs, and remains 181.5 mAh g⁻¹ after 1000 cycles at 200 mA g⁻¹ with 84% retention for KIBs. When coupled with commercial LiFePO₄ cathode, the full cell delivers a capacity of 140.6 mAh g⁻¹ after 250 cycles at 1 A g⁻¹. This work not only shows the promising potential ZnO-based materials for long-term and high-rate lithium-ion batteries, but also gives an insight into the design of ZnO-based anodes for potassium storage.