Microscopic energy storage mechanism of dielectric polymer-coated supercapacitors

WH Gao and T Zhao and S Dong and XY Huang and ZL Xu, JOURNAL OF ENERGY STORAGE, 72, 108174 (2023).

DOI: 10.1016/j.est.2023.108174

Supercapacitors have been attracting significant attention as promising energy storage devices. However, the voltage window limitation associated with electrolyte solutions has hindered the improvement of their capaci-tance. To address this issue and enhance the energy storage capabilities of general traditional supercapacitors, we put forward the dipole-induced effects observed in the theoretical framework of the electric double-layer structure. The molecular dynamics results demonstrate that, compared to traditional systems, an improvement of over 50% in integral capacitance at low voltages is achieved. Moreover, a new material-based experimental results obtained from a dielectric supercapacitor employing a hydrated electrolyte solution corroborated the effectiveness of our proposed model, yielding consistent outcomes. We attribute the large capacitance variation to the reorientation of the dipoles, which induces the neutral-to-bilayer transition and the overscreening-to-steric transition, consistent with the polarization process of the polymer in the experiment. We further investigate the capacitance variations under different dipole parameters, such as varying the number of layers, different number densities and different spacings, thereby enriching the experimental results with additional conclusions not previously obtained. This work presents a novel approach that exploits dipole-induced capacitance effects, paving the way for further advances in the field of energy storage technology.

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