The global energy supply is transforming from conventional fossil energy to sustainable energy. Sustainable energy species, for example, solar, wind, and hydro energy, are in an unsteady state and fail to provide a stable energy supply. Energy storage units can collect these unsteady state energies and output as stable energy supply. However, current energy storage units face significant challenges to provide both high-energy density and high-power density. To achieve high energy storage performance of electrochemical capacitor, existing research efforts mainly focus on (1) synthesizing new electrode materials to enlarge specific capacitance, and (2) designing asymmetric capacitor configuration and utilizing organic electrolytes to expand the working potential range. Without changing any internal components, we recently observed a significant capacitance enhancement of up to 155% by solely applying a small external magnetic field (0.072 Tesla). The magnetic field induced capacitance change is called magnetocapacitance.

In this talk, small magnetic field induced capacitance change on carbon nanocomposites will be discussed. Two processes, conventional- and microwave- annealing, were introduced to manufacture desired electroactive carbon nanocomposites decorated with pseudoactive metal oxide nanostructures (for example, Fe₂O₃, NiO and Co₃O₄). Their magnetocapacitances will be measured and compared. The proposed mechanisms will be interpreted by capacitor internal resistance change (solution resistance, charge transfer resistance and leakage resistance), which are based on Magnetohydrodynamics and Magnetoresistance phenomena. These findings will have significant impacts on processes involving proton and electron transfer as used in Li ion battery, fuel cells, electrochemical and biological sensing, and electrocatalytic CO₂ reduction. The perspective for future projects will be discussed as well.