Understanding intra-pore electrolyte resistances and distributed capacitances in carbon electrodes used in supercapacitors using a robust modeling process to separate the charge-storage occurring into macro-, meso-, and micro-pore structures

• Published in: Journal of energy storage 2024-11, Vol.101, p.113924, Article 113924
• Main Authors: Moreira, Cássio Murilo Rodrigues, Vicentini, Rafael, Venâncio, Raíssa, Zanin, Hudson, Franco, Débora Vilela, De Sousa, Lindomar Gomes, Da Silva, Leonardo Morais
• Format: Article
• Language: English
• Subjects: Associated resistances during capacitance measurements; Discrepancy between the electrochemical techniques; Effective data analysis; Modified generic electrochemical model; Next generation of supercapacitors
• ISSN: 2352-152X
• DOI: 10.1016/j.est.2024.113924

In this study, a Modified Generic Electrochemical (MGE) model is introduced for studying rough/porous carbon-based electrode materials employed in electrical double-layer capacitors (EDLC) which contain different types of surface defects. Instead of adopting the common theoretical approach involving the use of transmission line models or ad hoc equivalent circuits, a rational equivalent circuit model has been devised, which permitted us to derive the different equations for each electrochemical technique. The MGE representing the overall electrochemical behavior of EDLCs obtained using the different techniques (e.g., cyclic voltammetry, chronoamperometry, chronopotentiometry, and impedance) is formally derived based on a simple premise considering that the different inhomogeneous surface defects, which are geometrically arranged under equipotential conditions, are not electrochemically equivalent. In this sense, the presence of hierarchically distributed charge-storage processes with different time constants, accounting for the ionic accumulation at the electrode/solution interface, can be ascertained. We verified that is imperative to avoid the determination of the specific capacitances and resistances in EDLCs using a single electrochemical technique or several techniques whose model equations are based on different theoretical premises. The use of the MGE model unequivocally revealed that isolated measurements of the specific capacitance in the absence of the associated intra-pore resistances are not sufficient to ensure the presence of rapid charge storage allied with high-power characteristics. With the appropriate choice of carbon-based materials with very low intra-pore resistances, substantial progress can be made in ushering in the next generation of EDCLs with very high-power characteristics. Pores in activated carbons with different accessibilities under equipotential conditions and the equivalent circuits derived for GE model (PCs) and the Modified GE model (EDLCs). [Display omitted] •Novel Model Introduction: A novel approach with the Modified Generic Electrochemical (MGE) model for modeling Electrochemical Double-Layer Capacitors (EDLCs).•Addressing Historical Challenges: Challenges related to the correlation of various electrochemical techniques for modeling EDLCs.•Robust Model: A robust model for assessing specific capacitance and intra-pore electrolyte resistance in EDLCs.•Uniform Parameters: Using various techniques with uniform adjustabl