Electrochemical performance of Li⁺ insertion/extraction in Ni-substituted ZnCo₂O₄ as an emerging highly efficient...

With the industrial revolution in electronics, the demand for lithium-ion batteries, particularly those designed for electric vehicles and energy storage systems, has accelerated in recent years. This continuously increasing demand requires high-performance electrode materials, as commonly used graphite anodes show limited lithium intercalation. In this context, Ni-substituted ZnCo₂O₄ nanostructures, thanks to their high storage capacity, have potential for use as an anode material in lithium-ion batteries. Structural analysis concludes that the prepared materials show improved crystallinity with increasing Ni at the Zn-site in ZnCo₂O₄. The intermediate composition, Zn_0.5Ni_0.5Co₂O₄, of this series exhibits a specific capacity of 65 mA h g^-1 at an elevated current rate of 10 A g^-1. The lithium insertion/extraction mechanism is investigated via cyclic voltammetry, showing two redox peaks from ZnCo₂O₄ and a single redox peak from NiCo₂O₄. Additionally, the lithium diffusion coefficient in the prepared electrodes is computed to be 2.22 × 10^-12 cm² s^-1 for the intermediate composition, as obtained using cyclic voltammetry. Electrochemical impedance spectroscopy is used to observe the charge transport mechanism and the charge transfer resistance values of all the samples, which are calculated to be in the range of 235 to 306 Ω.