Quantifying ion desolvation effects on capacitances of nanoporous electrodes with liquid electrolytes

Abstract

Understanding ion desolvation effect in microporous electrodes is helpful towards high-efficient energy storage. Herein, we evaluate the contribution of ion desolvation to the electrochemical performance of microporous electrodes with a proposed multiscale approach. By combining the molecular density functional theory (DFT) with the simple DFT, we determine the ion solvation diameters in confined liquid acetonitrile, and then predict the capacitances of microporous electrodes involving acetonitrile-based electrolytes through a solvation-diameter-dependent coarse-grained model. We find that the ion solvation diameter displays an oscillatory decline as decreasing the pore size of nanoslit. Integrating this decline relation with the pore size distributions of microporous electrodes we show that the capacitances of practical electrodes can be quantitatively predicted in comparison with experimental measurements. This work not only provides a promising multiscale approach for investigating the properties of confined electrolytes, but also casts insights for the design and preparation of high-performance supercapacitors.