Model carbon materials derived from tannin to assess the importance of pore connectivity in supercapacitors

• Published in: Renewable & sustainable energy reviews Vol. 151; p. 111600
• Main Authors: Castro-Gutiérrez, J., Díez, N., Sevilla, M., Izquierdo, M.T., Celzard, A., Fierro, V.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-11-2021; Elsevier
• Subjects: Chemical Sciences; CO2 activation; Engineering Sciences; Hysteresis scanning; Inorganic chemistry; Materials; Mesoporous carbons; Pore connectivity; Supercapacitors; Tannin; Mesoporous carbons; Supercapacitors; Hysteresis scanning; Tannin; Pore connectivity; CO2 activation
• ISSN: 1364-0321; 1879-0690
• DOI: 10.1016/j.rser.2021.111600

A surfactant-water-assisted mechanochemical mesostructuration method is used to produce model carbon materials with a disordered or ordered mesoporous structure (DMCs or OMCs, respectively) from a sustainable precursor, mimosa tannin. These model materials, differing only in their mesoporous structure, allow assessing the importance of the connectivity of the micro-mesopore network on the electrochemical performance of the resultant supercapacitors (SCs). Connectivity is studied through the scanning of hysteresis loops from nitrogen adsorption-desorption isotherms and, contrary to what it is suggested in the literature, order is not always beneficial for the performance of SCs. A thorough review of the open literature and comparison with our electrodes led us to conclude that CO2-activated DMCs and OMCs are among the best materials reported so far, as they exhibit excellent SC behavior, high-rate capability, and long-term stability in aqueous and organic electrolytes. It is showed that ordered mesopores improve the diffusion of the small-size ions of the aqueous electrolyte and hence favor a better performance at high charging rates, resulting in a 12% higher capacitance retention at 80 A g−1 when compared to that obtained with the disordered materials. However, the more interconnected porosity of the disordered materials allows better diffusion of large-size ions, thus improving the electrochemical performance in the organic electrolyte by 15% at 40 A g−1.
•Ordered and disordered mesoporous carbons of high surface area were produced.•After activation, high-rate capability supercapacitors were obtained from them.•Small-size ions of aqueous electrolyte diffuse better in ordered mesopores.•Large-size ions of organic electrolyte diffuse better in disordered mesopores.•Mesopore connectivity strongly affects electrochemical performances.