title: Non-Faradaic Energy Storage by Room Temperature Ionic Liquids in Nanoporous Electrodes.
abstract: The enhancement of non-Faradaic charge and energy density stored by ionic electrolytes in nanostructured electrodes is an intriguing issue of great practical importance for energy storage in electric double layer capacitors. On the basis of extensive molecular dynamics simulations of various carbon-based nanoporous electrodes and room temperature ionic liquid (RTIL) electrolytes, we identify atomistic mechanisms and correlations between electrode/electrolyte structures that lead to capacitance enhancement. In the symmetric electrode setup with nanopores having atomically smooth walls, most RTILs showed up to 50% capacitance increase compared to infinitely wide pore. Extensive simulations using asymmetric electrodes and pores with atomically rough surfaces demonstrated that tuning of electrode nanostructure could lead to further substantial capacitance enhancement. Therefore, the capacitance in nanoporous electrodes can be increased due to a combination of two effects: (i) the screening of ionic interactions by nanopore walls upon electrolyte nanoconfinement, and (ii) the optimization of nanopore structure (volume, surface roughness) to take into account the asymmetry between cation and anion chemical structures.
authors.affiliation: Material Sciences and Engineering Department, University of Utah, 122 South Central Campus Drive, Salt Lake City, Utah 84112, United States.
authors.forename: Jenel
authors.initials: J
authors.lastname: Vatamanu
authors.affiliation: Material Sciences and Engineering Department, University of Utah, 122 South Central Campus Drive, Salt Lake City, Utah 84112, United States.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Vatamanu
authors.affiliation: Material Sciences and Engineering Department, University of Utah, 122 South Central Campus Drive, Salt Lake City, Utah 84112, United States.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Bedrov
keywords: capacitance; electric double layer; energy storage; nanoconfinement; nanoporous electrodes; room temperature ionic liquids; supercapacitors