title: The Influence of Anion Shape on the Electrical Double Layer Microstructure and Capacitance of Ionic Liquids-Based Supercapacitors by Molecular Simulations.
abstract: Room-temperature ionic liquids (RTILs) are an emerging class of electrolytes for supercapacitors. In this work, we investigate the effects of different supercapacitor models and anion shape on the electrical double layers (EDLs) of two different RTILs: 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Emim][Tf₂N]) and 1-ethyl-3-methylimidazolium 2-(cyano)pyrrolide ([Emim][CNPyr]) by molecular dynamics (MD) simulation. The EDL microstructure is represented by number densities of cations and anions, and the potential drop near neutral and charged electrodes reveal that the supercapacitor model with a single electrode has the same EDL structure as the model with two opposite electrodes. Nevertheless, the employment of the one-electrode model without tuning the bulk density of RTILs is more time-saving in contrast to the two-electrode one. With the one-electrode model, our simulation demonstrated that the shapes of anions significantly imposed effects on the microstructure of EDLs. The EDL differential capacitance vs. potential (C-V) curves of [Emim][CNPyr] electrolyte exhibit higher differential capacitance at positive potentials. The modeling study provides microscopic insight into the EDLs structure of RTILs with different anion shapes.
authors.affiliation: State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China. mchen@hust.edu.cn.|Nano Interface Centre for Energy, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China. mchen@hust.edu.cn.
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China. songli@hust.edu.cn.|Nano Interface Centre for Energy, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China. songli@hust.edu.cn.|Shenzhen Research Institute of Huazhong University of Science and Technology, Shenzhen 518057, China. songli@hust.edu.cn.
authors.forename: Song
authors.initials: S
authors.lastname: Li
authors.affiliation: State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China. gfeng@hust.edu.cn.|Nano Interface Centre for Energy, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China. gfeng@hust.edu.cn.
authors.forename: Guang
authors.initials: G
authors.lastname: Feng
mesh_terms: D000838:Anions / Q000737:chemistry*; D025802:Electric Capacitance; D004566:Electrodes; D006108:Graphite / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation
chemical_list: D000838:Anions; D052578:Ionic Liquids; D006108:Graphite
keywords: capacitance; carbon electrode; interfacial structure; ion shape; supercapacitor model