Abstract:

Aqueous zinc-ion batteries have a high energy density, good stability, and high safety factor; as a double transition metal oxide, NiCo₂O₄ has excellent electrical conductivity and electrochemical activity. Therefore, herein, NiCo₂O₄ was novelly used as a novel cathode material for aqueous zinc-ion batteries. The solid spinel NiCo₂O₄ material was prepared by the sol-gel and calcination heat methods. Using scanning electron microscopy, transmission electron microscope, energy dispersive spectroscopy, and electrochemical technology, the morphology and electrochemical properties of the cathode material of the new aqueous zinc-ion batteries were analyzed. The results show that the spinel NiCo₂O₄ material has excellent purity and crystallinity, and the particles are evenly dispersed without agglomeration and impurity. Moreover, it has good and stable charge-discharge performance. At a current density of 100 mA·g^-1, the initial specific discharge capacity of the electrode is 92 mA·h·g^-1, 60 mA·h·g^-1 after 100 cycles, and 44 mA·h·g^-1 after 200 cycles. However, when the current density is high, the specific capacitance of the NiCo₂O₄ electrode decreases by 27 mA·h·g^-1, which has irreversible impact damage to a certain extent. This study highlights that NiCo₂O₄ material improves the performance of aqueous zinc-ion batteries, which can guide the future design of aqueous zinc-ion batteries.

Key words: aqueous zinc-ion battery, cathode material, NiCo₂O₄, sol-gel method