Effect of electronic spatial extents (ESE) of ions on overpotential of lithium ion capacitors

• Published in: Electrochimica acta Vol. 115; pp. 234 - 238
• Main Authors: Xu, Fan, Lee, Chung ho, Koo, Chong Min, Jung, Cheolsoo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2014
• Subjects: Alternating current; Capacitor; Capacitors; Discharge; Electrodes; Electrolytes; Electron density; Electronic spatial extent; Electronics; Nanopore; Nanostructure; Overpotential; Potential drop; Electronic spatial extent; Overpotential; Nanopore; Capacitor; Potential drop
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2013.10.175

•Electronic spatial extent (ESE) of ion characterizes its electron density volume.•The ESE of ion proposes to assess overpotential of nanoporous capacitor.•Anion with low ESE shows low overpotential of the capacitor.•The ESE is more realistic to assess overpotential than conductivity or ion size. The electronic spatial extent (ESE) of ions was defined as a major concept for assessing the cause of overpotential in the charging and discharging processes of a nanoporous activated carbon (AC) electrode. The performance degradation of AC/Li half-cells was caused by the overpotential, which was in discord with the electrolyte conductivity and ion size. Compared to the overpotential with the salt concentration, the AC/Li half-cell with a high concentration had a smaller overpotential, and its discharge patterns were similar to the curves obtained from the half-cells with a smaller ESE of BF4− ion. The ESE is a more realistic solution for determining the overpotential of the nanoporous capacitor, such as supercapacitor and Li ion capacitor, because its capacity is dependent on the electron density at the electric double layer of the capacitor electrode.