Synthesis and theoretical calculations of N-doped ZnCo2O4 anode for lithium-ion anode via gradient pressure-induced processes and theoretical calculations

The aim of this study is to improve the electrochemical performance of ZnCo₂O₄ (ZCO) anode by two-steps nitrogen doping processes, including hydrothermal reaction process and atmospheric pressure plasma jet process (APPJ). Via the higher-pressure hydrothermal method, nitrogen was doped in the ZCO spinel lattice, while subsequently "atmospheric-pressure" APPJ mainly activated and modified the electrode surface binding with the dangling bond. The uniformity, chemical composition, and crystal structure of ZCO and N-ZCO were examined by electron probe microanalyzer (EPMA), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). First principle calculation based on density functional theory (DFT) results clearly reveal that N-doping could significantly narrow band gap and enhance the electronic transfer towards ZCO framework. Nitrogen doping effectively improves electrochemical performance with superior capacity (1025 mAh⋅g⁻¹) and stability with 63% cycling retention after 100 cycles at a current density of 1C. This study provides a rapid and inexpensive nitrogen doping processes to efficiently promote the ZCO electrochemical performance for anode materials.