Salt concentration and charging velocity determine ion charge storage mechanism in nanoporous supercapacitors.

ABSTRACT: A fundamental understanding of ion charge storage in nanoporous electrodes is essential to improve the performance of supercapacitors or devices for capacitive desalination. Here, we employ in situ X-ray transmission measurements on activated carbon supercapacitors to study ion concentration changes during electrochemical operation. Whereas counter-ion adsorption was found to dominate at small electrolyte salt concentrations and slow cycling speed, ion replacement prevails for high molar concentrations and/or fast cycling. Chronoamperometry measurements reveal two distinct time regimes of ion concentration changes. In the first regime the supercapacitor is charged, and counter- and co-ion concentration changes align with ion replacement and partially co-ion expulsion. In the second regime,

SUBMITTER: Prehal C 

PROVIDER: S-EPMC6175899 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature