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Title: Impurity effects on ionic-liquid-based supercapacitors

Small amounts of an impurity may affect the key properties of an ionic liquid and such effects can be dramatically amplified when the electrolyte is under confinement. Here the classical density functional theory is employed to investigate the impurity effects on the microscopic structure and the performance of ionic-liquid-based electrical double-layer capacitors, also known as supercapacitors. Using a primitive model for ionic species, we study the effects of an impurity on the double layer structure and the integral capacitance of a room temperature ionic liquid in model electrode pores and find that an impurity strongly binding to the surface of a porous electrode can significantly alter the electric double layer structure and dampen the oscillatory dependence of the capacitance with the pore size of the electrode. Meanwhile, a strong affinity of the impurity with the ionic species affects the dependence of the integral capacitance on the pore size. Up to 30% increase in the integral capacitance can be achieved even at a very low impurity bulk concentration. As a result, by comparing with an ionic liquid mixture containing modified ionic species, we find that the cooperative effect of the bounded impurities is mainly responsible for the significant enhancement of themore » supercapacitor performance.« less
 [1] ;  [2] ;  [3] ;  [1]
  1. Univ. of California, Riverside, CA (United States)
  2. Univ. of California, Riverside, CA (United States); East China Univ. of Science and Technology, Shanghai (People's Republic of China)
  3. Brigham Young Univ., Provo, UT (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Molecular Physics
Additional Journal Information:
Journal Volume: 115; Journal Issue: 4; Journal ID: ISSN 0026-8976
Taylor & Francis
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 25 ENERGY STORAGE; electrical double layer; energy storage; classical density functional theory
OSTI Identifier: