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Title: Impurity Effects on Charging Mechanism and Energy Storage of Nanoporous Supercapacitors

Room-temperature ionic liquids (RTILs) have been widely used as electrolytes to enhance the capacitive performance of electrochemical capacitors also known as supercapacitors. Whereas impurities are ubiquitous in RTILs (e.g., water, alkali salts, and organic solvents), little is known about their influences on the electrochemical behavior of electrochemical devices. In this work, we investigate different impurities in RTILs within the micropores of carbon electrodes via the classical density functional theory (CDFT). We find that under certain conditions impurities can significantly change the charging behavior of electric double layers and the shape of differential capacitance curves even at very low concentrations. More interestingly, an impurity with a strong affinity to the nanopore can increase the energy density beyond a critical charging potential. As a result, our theoretical predictions provide further understanding of how impurity in RTILs affects the performance of supercapacitors.
Authors:
 [1] ;  [2] ;  [1] ; ORCiD logo [2]
  1. East China Univ. of Science and Technology, Shanghai (People's Republic of China)
  2. Univ. of California, Riverside, CA (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 26; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Energy Frontier Research Centers (EFRC) (United States). Fluid Interface Reactions, Structures and Transport Center (FIRST)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 25 ENERGY STORAGE
OSTI Identifier:
1399237