Energy and power performances of binary mixtures of ionic liquids in planar and porous electrodes by molecular dynamics simulations

Author(s)

Ferreira, Pedro H. L. ; Sampaio, Abner M. ; Siqueira, Leonardo J. A.

• Document type: Journal article
• Source: Electrochimica Acta; v. 410, p. 11-pg., 2022-04-01.

Abstract

Binary mixtures of ionic liquids are interesting alternatives to tailor ionic liquids properties. Some of them have been proposed as electrolytes for supercapacitors. Herein, we performed molecular dynamics simulations of planar and porous electrodes with binar y mixtures of ionic liquids comprising the 1-ethyl-3-methyl-imidazoliumbis(trifluoromethane-sulfonyl)imide ([EMIM][NTf2]) and 1-ethyl-3-methyl-imidazoliumtetrafluoroborate ([EMIM] [BF4]), increasing the mole fraction of the latter (xBF4) from 0 to 1. The energy densities calculated from the simulations increase monotonically with x(BF4), accordingly with available experimental results [Angew. Chem. Int. Ed. 2015, 54, 1 - 5]. Considering that the electrode simulations were dealt with the constant potential model, the characteristic charging times were calculated for planar and porous electrodes. The devices containing only [EMIM] [NTf2] charge slower than electrolytes with x(BF4) > 0.0, and the fastest charging happens inx(BF4) = 1.0 V. These features are related to the higher [NTf2]-electrode interaction and also to the smaller size of [BF4](-). For porous electrode, the calculated Ragone plot indicates that [EMIM][BF4] outperforms a l l the other electrolytes with a voltage of 3.0 V in terms of energ y and power densities. In the system of best performance, there are considerable contributions of co-ion desorption and counter-ion adsorption mechanisms in the negative and positive electrodes, respectively. (AU)

• FAPESP's process: 19/18125-0 - Computational study of materials with application in energy storage
• Grantee: Leonardo José Amaral de Siqueira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/11631-2 - CINE: computational materials design based on atomistic simulations, meso-scale, multi-physics, and artificial intelligence for energy applications
• Grantee: Juarez Lopes Ferreira da Silva
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 18/21401-7 - Multi-User Equipment approved in grant 2017/11631-2: cluster computational de alto desempenho - ENIAC
• Grantee: Juarez Lopes Ferreira da Silva
• Support Opportunities: Multi-user Equipment Program