Abstract
Understanding how electrolyte-filled porous electrodes respond to an applied potential is important to many electrochemical technologies. Here, we consider a model supercapacitor of two blocking cylindrical pores on either side of a cylindrical electrolyte reservoir. A stepwise potential difference 2φ between the pores drives ionic fluxes in the setup, which we study through the modified Poisson-Nernst-Planck equations, solved with finite elements. We focus our discussion on the dominant timescales with which the pores charge and how these timescales depend on three dimensionless numbers. Next to the dimensionless applied potential φ, we consider the ratio R/Rb of the pore's resistance R to the bulk reservoir resistance Rb and the ratio rp/λ of the pore radius rp to the Debye length λ. We compare our data to theoretical predictions by Aslyamov and Janssen (φ), Posey and Morozumi (R/Rb), and Henrique, Zuk, and Gupta (rp/λ). Through our numerical approach, we delineate the validity of these theories and the assumptions on which they were based.
| Original language | English |
|---|---|
| Article number | 214105 |
| Pages (from-to) | 1-12 |
| Journal | Journal of Chemical Physics |
| Volume | 156 |
| Issue number | 21 |
| DOIs | |
| Publication status | Published - 7 Jun 2022 |
Bibliographical note
Funding Information:This work was sponsored by the National Natural Science Foundation of China (Grant No. 22078088) and the Shanghai Rising-Star Program (Grant No. 21QA1401900). This work was also part of the D-ITP consortium, a program of the Netherlands Organization for Scientific Research (NWO) that is funded by the Dutch Ministry of Education, Culture and Science (OCW). J.Y. acknowledges the Chinese Scholarship Council for a visiting fellowship. C.L. and R.v.R acknowledge the EU-FET project NANOPHLOW (Grant No. REP-766972-1) and helpful discussion with Professor Honglai Liu and Willem Boon. The authors thank Timur Aslyamov for his useful comments on the manuscript.
Publisher Copyright:
© 2022 Author(s).