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Title: On the hydrophilicity of electrodes for capacitive energy extraction

The so-called Capmix technique for energy extraction is based on the cyclic expansion of electrical double layers to harvest dissipative energy arising from the salinity difference between freshwater and seawater. Its optimal performance requires a careful selection of the electrical potentials for the charging and discharging processes, which must be matched with the pore characteristics of the electrode materials. While a number of recent studies have examined the effects of the electrode pore size and geometry on the capacitive energy extraction processes, there is little knowledge on how the surface properties of the electrodes affect the thermodynamic efficiency. In this paper, we investigate the Capmix processes using the classical density functional theory for a realistic model of electrolyte solutions. The theoretical predictions allow us to identify optimal operation parameters for capacitive energy extraction with porous electrodes of different surface hydrophobicity. Finally, in agreement with recent experiments, we find that the thermodynamic efficiency can be much improved by using most hydrophilic electrodes.
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [1]
  1. Univ. of California, Riverside, CA (United States). Dept. of Chemical and Environmental Engineering. Dept. of Mathematics
  2. (China). State Key Lab. of Chemical Engineering
  3. (China). Dept. of Chemical Engineering
  4. East China Univ. of Science and Technology, Shanghai (China). State Key Lab. of Chemical Engineering
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Physics. Condensed Matter
Additional Journal Information:
Journal Volume: 28; Journal Issue: 46; Journal ID: ISSN 0953-8984
IOP Publishing
Research Org:
Univ. of California, Riverside, CA (United States); East China Univ. of Science and Technology, Shanghai (China)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Chinese Scholarship Council
Contributing Orgs:
Tsinghua Univ., Beijing (China)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; energy extraction; salinity exchange; electric double layer; classical density functional theory
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1324475