Facile Synthesis of Porous ZnCo₂O₄ Nanosheets and the Superior Electrochemical Properties for Sodium Ion Batteries.

ZnCo₂O₄ nanosheets with large surface area and mesoporous structure were synthesized using a facile hydrothermal method followed with a calcination process. When applied as the anode material in sodium ion batteries, the ZnCo₂O₄ nanosheets demonstrated a high initial charge capacity of 415.1 mAh/g at the current density of 100 mA/g. Even though the reversible capacity decreased in the first 20 cycles, it stayed relatively stable afterwards and retained 330 mAh/g after 100 cycles. This result was superior to those of many reported works of ZnO- and Co₃O₄-based anodes for sodium ion batteries, which might be due to the synergistic effect of both Zn and Co, and the refined porous nanosheet-like structure which facilitates electrochemical reactions by providing more reaction sites and ensures cycling stability by providing more space to accommodate the structural strains during cycles.