Electrochemical properties of carbon xerogel-based supercapacitors using non-aqueous electrolytes
S. Veleva1, B. Karamanova1, A. Stoyanova1, A. Arenillas2
1Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, 10 G. Bonchev Str., 1113 Sofia, Bulgaria
3Instituto de Ciencia y Tecnología del Carbono, INCAR-CSIC. Francisco Pintado Fe, 26, 33011, Oviedo, Spain
* svetlana_veleva@iees.bas.bg
Supercapacitors are energy storage devices that have attracted much attention because they are able to provide high power densities of up to 10 kW kg-1 (unlike batteries) and have long lifetimes1. However, their main drawback is the inability to store high energy density, which has prompted research into new carbon electrode materials. When selecting them, it should be kept in mind that the efficiency of supercapacitors depends on both their porosity and their electrical conductivity, and the higher their microporosity, the higher the charge that can be stored2. The use of an organic electrolyte, which allows a much wider and stable potential window compared to aqueous one, is also a prerequisite for obtaining a high energy density devices3.
The present study aims to show the relationship between the surface chemistry of carbon xerogel and its electrochemical properties as an electrode material in symmetric supercapacitors with organic electrolytes.
Carbon xerogels were synthesized by polycondensation of resorcinol and formaldehyde followed by carbonization and activation. Their porous properties were modulated by changing the pH of the precursor solutions and characterized by N2 adsorption-desorption isotherms, a helium pycnometer and a shell density analyzer. The obtained samples were characterized physiochemically by DTA/TGA, TEM, XRD, SEM analyses. The results show that the synthesized carbon xerogels are porous with a high specific surface area, which is a necessary condition for their good electrochemical performance as electrode materials in supercapacitors.
With the resulting carbon xerogel and organic electrolytes (LiBF4 EC:DMC 1:1 and 1-ethyl-3-methylimidazolium tetrafluoroborate), two-electrode symmetric supercapacitor cells were assembled and investigated by galvanostatic charge/discharge measurements and cyclic voltammetry to assess their lifetime stability and electrochemical performance. Specific capacitances, energy and power densities, Columbus efficiency and energy efficiency were also calculated.The highest stability is shown by the symmetric carbon xerogel supercapacitor in LiBF4/1-ethyl-3-methylimidazolium tetrafluoroborate electrolyte than in LiBF4 electrolyte.
References:
1. B.E. Conway, Electrochemical supercapacitors: scientific fundamentals and technological applications, Springer Science & Business Media2013
2. V.P. Béguin, A. Balducci, E. Frackowiak, Carbons and Electrolytes for Advanced Supercapacitors, Adv Mater, 26, 2014, 2219.
3. S.Biswas, A. Chowdhury, Organic Supercapacitors as the Next Generation Energy Storage Device: Emergence, Opportunity, and Challenges, ChemPhysChem, 24, 2023, e20220056
Acknowledgements: This research is funded by the Ministry of Education and Science of Bulgaria under the National Program "European Scientific Networks" (Agreement D01-286 / 07.10.2020, D01-78/30.03.2021). Authors gratefully acknowledge.