Prussian Blue Analogue-Derived ZnO/ZnFe₂O₄ Core-Shell Nanospheres as High-Performance Anodes for Lithium-Ion and Potassium-Ion Batteries

Herein, core-shell nanostructured ZnO/derived from self-sacrifice template method with Prussian blue analogue (i. e., Zn₃[Fe(CN)₆]₂) as precursor has been successfully synthesized by controlling the calcination temperatures and heating rates. The formation mechanism of core-shell nanostructures has been explored through the morphology transformation under different synthetic conditions. Impressively, ZnO/ZnFe₂O₄ hybrid material with core-double shell nanostructure shows good cycling performance as anodes of lithium-ion batteries (1137 mAh g⁻¹ at 1 A g⁻¹ after 80 cycles) and potassium-ion batteries (217 mAh g⁻¹ at 0.1 A g⁻¹ after 400 cycles). The excellent performances can be attributed to the unique core-double shell nanostructure as well as synergistic effects of ZnO and ZnFe₂O₄. The results indicate that the strategy of designing nanostructures could successfully improve the electrochemical performances of ZnO/ZnFe₂O₄ and effectively expand the commercial application of transition metal oxides.