Despite their high power density, aqueous-based electric double-layer capacitors (EDLCs) possess relatively low energy density due to the limitation of potential window (~1.0 V) and low specific capacitance of active materials. To increase the energy density without sacrificing the power density, it is highly desired to achieve a simultaneous improvement of both specific capacitance and potential window of EDLCs. However, this remains a major challenge that is not been solved up to date. This work demonstrates that by inserting a polarized-polyvinylidene fluoride (PVDF) ferroelectric layer underneath the graphene, a simultaneous enhancement of both areal capacitance and potential window is achieved, in which the areal capacitance increases from 5.5 to 7.5 μF/cm2 (i.e., 36%) (or 55 F/cm3 to 75 F/cm3 in terms of volumetric capacitance), and the potential window expands from 1.0 V to 1.5 V. This results in a threefold increase in the areal energy density of the capacitor. The enhancement in capacitance can be explained by the Gouy–Chapman–Stern model. The widening of potential window is due to the shift of the Fermi level of graphene caused by the doping effect of the polarized-PVDF layer.
|Journal||Journal of Power Sources|
|Publication status||Published - 2021 Sept 30|
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government ( MSIT ) (No. 2020R1C1C1007436 ). This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 103.02–2019.47 .
© 2021 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering