Theoretical Specific Capacity and Metal Ion Diffusion Pathway of NiMoO Microspheres for Hybrid Supercapacitors.

Transition metal molybdates are one of the most prominent materials for energy storage devices. The present investigation establishes a strong correlation between the structure and electrochemical performance of NiMoO through Density Functional Theory (DFT). Initially, the NiMoO microspheres are directly deposited on nickel foam using a hydrothermal method by tuning experimental parameters. When employed as electrode materials, the NiMoO microspheres deliver a specific capacity of 168.9 mAh g at 1 A g. In addition, the material retains 80% capacity over 7000 charge-discharge cycles with 98.3% coulombic efficiency, implying its excellent stability. DFT calculations are used to determine specific capacity and potassium ion diffusion for 5 layers of [110] planes of NiMoO. The potential energy landscape is created for [110] plane using the potassium atom minimum hopping algorithm and atomic simulation environment. The DFT results clearly align with the theoretical capacity of 203 mAh g close to the experimental results. A hybrid supercapacitor (HSC) is also developed with NiMoO//AC cell delivers a specific energy of 56.3 Wh kg at a specific power of 421 W kg with negligible capacity loss over 15 000 cycles. This investigation offers the development of battery-type electrodes for hybrid supercapacitors using the fundamental understanding of ion-diffusion in the materials' structure.