High performance magnetic pseudocapacitors - Direct correlation between specific capacitance and diffusion coefficients

Till date, magnetic field dependent variations in specific capacitance have only been reported in simple binary oxides or alloys. Ternary spinels are often considered to be a composite of two or more mono-cationic entities, which allows them to deliver high specific capacitance. This paper deals with one such spinel i.e. NiCo₂O₄ (NCO), with 2-dimentional porous morphology, for obtaining highly responsive magnetic supercapacitors. Compared to the constituent oxides viz., NiO and Co₃O₄, NiCo₂O₄ shows nearly 100% higher response under magnetic field. Such results make this spinel furthermore useful for industrial applications. The results can be explained by the variation in dielectric constant, ESR, and ion diffusion as a function of applied magnetic fields. In such 2-dimentional porous oxides, a modified theoretical model has to be utilized to explain the magnetic field induced specific capacitance changes. There is a need to consider the impact of diffusion coefficient and additional convection term that is induced by the Fick's law. Another aspect, related with the carbon footprint for the materials, is determined using the life cycle assessment studies. This shows another advantage of using NiCo₂O₄ in energy storage devices.