Scientists have developed a new model that allows for a better understanding of the operating mechanism of the double electric layer (EDL) in supercapacitors and predicting their ability to accumulate charge. This model is consistent with experimental data and will help improve supercapacitors, which play a key role in portable electronics and electric vehicles.
If a battery can be imagined as a container that slowly accumulates energy, then a supercapacitor is a vessel that can be quickly filled and instantly discharged. Supercapacitors operate with very high currents, which makes them especially useful in situations requiring instant and powerful energy output.
The new model, developed by researchers from MIEM HSE University and the N.N. Semenov Research Center for Chemical Physics, deepens our understanding of the double electric layer at the interface between the electrode and the electrolyte solution. The model refines the classical modified Poisson-Boltzmann equation, taking into account the complex interactions between ions and water molecules, the influence of electric fields on the structure of water, as well as the spatial constraints on the movement of ions on the electrode surface. These improvements allow for a more accurate description of how EDL stores charge under various conditions, with a special emphasis on differential capacitance — the ability of EDL to store charge with small changes in voltage.
Using aqueous solutions of sodium perchlorate and potassium hexafluorophosphate with a silver electrode, the researchers confirmed that the predictions of their model are fully consistent with experimental data. The model can be applied not only to simple but also to complex electrolyte systems, demonstrating versatility when working with various types of electrolytes.
This breakthrough will pave the way for the development of more efficient supercapacitors, which will be crucial for improving the performance of modern technologies, such as electric vehicles and portable electronics, by optimizing the ways energy is stored and released. The study will also create a basis for the development of more complex models that take into account even stronger interactions of ions with electrodes, which is relevant for real devices.
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