Can ionophobic nanopores enhance the energy storage capacity of electric-double-layer capacitors containing nonaqueous electrolytes?
- East China Univ. of Science and Technology, Shanghai (China). State Key Lab. of Chemical Engineering
- Brigham Young Univ., Provo, UT (United States). Dept. of Chemistry and Biochemistry
- Univ. of California, Riverside, CA (United States). Dept. of Chemical and Environmental Engineering
The ionophobicity effect of nanoporous electrodes on the capacitance and the energy storage capacity of nonaqueous-electrolyte supercapacitors is studied by means of the classical density functional theory (DFT). It has been hypothesized that ionophobic nanopores may create obstacles in charging, but they store energy much more efficiently than ionophilic pores. In this paper, we find that, for both ionic liquids and organic electrolytes, an ionophobic pore exhibits a charging behavior different from that of an ionophilic pore, and that the capacitance–voltage curve changes from a bell shape to a two-hump camel shape when the pore ionophobicity increases. For electric-double-layer capacitors containing organic electrolytes, an increase in the ionophobicity of the nanopores leads to a higher capacity for energy storage. Without taking into account the effects of background screening, the DFT predicts that an ionophobic pore containing an ionic liquid does not enhance the supercapacitor performance within the practical voltage ranges. However, by using an effective dielectric constant to account for ion polarizability, the DFT predicts that, like an organic electrolyte, an ionophobic pore with an ionic liquid is also able to increase the energy stored when the electrode voltage is beyond a certain value. We find that the critical voltage for an enhanced capacitance in an ionic liquid is larger than that in an organic electrolyte. Finally, our theoretical predictions provide further understanding of how chemical modification of porous electrodes affects the performance of supercapacitors.
- Research Organization:
- Brigham Young Univ., Provo, UT (United States); Univ. of California, Riverside, CA (United States); East China Univ. of Science and Technology, Shanghai (China); Energy Frontier Research Centers (EFRC) (United States). Fluid Interface Reactions, Structures and Transport Center (FIRST)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Chinese Scholarship Council (China); National Natural Science Foundation of China (NSFC)
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1340472
- Journal Information:
- Journal of Physics. Condensed Matter, Journal Name: Journal of Physics. Condensed Matter Journal Issue: 41 Vol. 28; ISSN 0953-8984
- Publisher:
- IOP PublishingCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Time-dependent density functional theory for the charging kinetics of electric double layer containing room-temperature ionic liquids
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journal | November 2016 |
The effect of finite pore length on ion structure and charging
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journal | September 2017 |
| The effect of finite pore length on ion structure and charging | text | January 2019 |
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