Theoretical Model for Magnetic Supercapacitors—From the Electrode Material to Electrolyte Ion Dependence

Abstract

Recent results have shown that electrochemical energy storage devices can change their characteristics near the magnetic field environment. Mostly, this change is attributed to the magnetically responsive electrode materials. It is still not expected that significant change can also be induced under a magnetic field by replacing nonmagnetic electrolytes. In this paper, it is clearly shown that this 'change' does occur and its magnitude can be as high as 50%. To date, a Nernstian relation across the electrode is used to explain the supercapacitive behavior of a cell, ignoring the contributions from the magnetic field, even if it is present in the surroundings of the device. Therefore, it is necessary to modify these well-established theoretical models to explain the magnetic field-dependent behavior in energy storage devices. It is shown that the Lorentz force plays a consequential role in inducing colossal changes in the specific capacitance of a supercapacitor. Seven different nonmagnetic electrolytes are combined with Fe 2 O 3 electrodes to prove the proposed concept. The modified theory leads to consistent results, which are corroborated with the experimental data.

Hierarchical NaFePO4 nanostructures in combination with an optimized carbon-based electrode to achieve advanced aqueous Na-ion supercapacitors

“…The obtained slurries were drop casted onto the graphite sheets (with 1 cm × 1 cm) and vacuum dried at 80 °C for 12 h. All electrochemical measurements were performed using 2 M aqueous NaOH as an electrolyte. 18 Current collecting graphite sheet coated with slurries containing the active materials was used. Platinum wire and Ag/AgCl (in 3.0 M KCl) were used as the counter and reference electrodes, respectively.…”

2D Flower-like Porous Nanostructures of Layered SnS2 for High-Performance Supercapacitors: Correlating Theoretical and Experimental Studies

“…This fact has been interpreted from the theoretical model using a modified Fick’s law. The process of modeling and mathematical calculations has already been reported by our group. − Employing the model, the theoretical charge–discharge curves were obtained, and subsequently, the diffusion coefficients of the electrolyte ions were calculated. The modified diffusion behavior of electrolyte ions was taken into account to explain the electrochemical activity of solid and porous SnS 2 in three different electrolytes.…”

“…Therefore, two time-dependent equations for potential, one for charging and another for discharging, could be obtained by substituting the analytical expression of C 0 (0, t ) and C R (0, t ). The obtained equations are and where E in eqs and stands for the potential of the electrode surface. The terms E 0 , i , B , D 0 , and D R represent the reference potential of the electrochemical system, current density, magnetic field intensity, and the initial and final diffusion coefficient, respectively.…”

Redox mediator induced electrochemical reactions at the electrode‐electrolyte interface: Making sodium‐ion supercapacitors a competitive technology

“…But, these have an intrinsic restriction of limited operational voltage window (∼1.2 V). [28][29][30][31] Therefore, electrolytes will have to be suitably modified to obtain the desired electrochemical phenomenon. As the number of solvated ions would be limited in a given aqueous electrolyte, the question arises: "how to increase the electrochemical reactions at the electrode-electrolyte interface?"…”