Clean energy sources like the sun and wind are renewable, free and inexhaustible, but they are intermittent. Therefore, to store the generated energy and use it when there is no sunlight or wind, it is necessary to have good storage systems, in which supercapacitors can be very important parts. Indeed, these devices vastly outperform batteries in terms of their power, which is the speed at which they store energy (charge) and deliver it (discharge).

Seeking to optimize the efficiency of supercapacitors, a team of researchers from Brazilian universities UFVJM and Unicamp developed a mathematical model that should help to minimize undesirable energy losses that occur within these devices and that are commonly disregarded in the scientific literature. The work was carried out in the context of CINE’s Advanced Energy Storage (AES) division.

Using conventional software, the new model is able to provide a realistic analysis of the experimental data of a supercapacitor where internal energy losses are considered. More precisely, with this model it is possible to accurately quantify the electrochemical characteristics of supercapacitors related to their capacitance (the amount of charge the device can store) and resistance (the opposition it offers to the flow of electric current). For this, the model considers the presence of different structural defects, such as pores, fissures and cracks, in the materials that form the supercapacitor electrodes.

According to the authors of the work, the model will help to design the most suitable material for each application of a supercapacitor. “The model makes it possible to understand how the conditions for the synthesis of different conductive materials can influence the real performance of supercapacitors under operating conditions”, says Professor Leonardo Morais da Silva (UFVJM), collaborator researcher at AES and main author of the work. “Thus, one can optimize the average pore size, as well as other types of structural defects, so that energy storage is as efficient as possible”, he adds.

The theoretical model was validated by the authors with experimental data. For this, the researchers produced electrodes from five different materials and performed experiments using four techniques commonly used in the electrochemical characterization of supercapacitors: cyclic voltammetry, chronoamperometry, chronopotentiometry and electrochemical impedance spectroscopy. The excellent agreement between the experimental findings and the simulations confirmed the validity of the model.

The work is the result of ideas and doubts from students and professors that have emerged over the last five years in the context of a collaboration between researchers from UFVJM and Unicamp. The research was funded by Brazilian agencies FAPESP, CNPq, Finep and FAPEMIG, and by Shell, in addition to the strategic support of the ANP.

Paper reference: Proposal of a novel methodology for the electrochemical characterization of well-behaved redox-active materials used in supercapacitors. Leonardo M. Da Silva, Lindomar G. De Sousa, Rafael Vicentini, João Pedro Aguiar, Gustavo Doubek, Hudson Zanin. Electrochimica Acta. Volume 457, 20 July 2023, 142458. https://doi.org/10.1016/j.electacta.2023.142458.
Authors who are CINE members: Leonardo M. Da Silva, Rafael Vicentini, João Pedro Aguiar, Gustavo Doubek, Hudson Zanin.