Oscillation Charging Dynamics in Nanopore Supercapacitors with Organic Electrolyte

Abstract

Nanopore electrodes have the potential to enhance the energy density of supercapacitors but tend to reduce charging dynamics, consequently impacting power density. A comprehensive understanding of their charging mechanisms can provide insights into how to boost charging dynamics. In this work, we conducted constant-potential-based molecular dynamics simulations to explore the charging mechanism of nanopore supercapacitors with organic electrolytes. Contrary to the traditional understanding associating larger pore sizes with faster charging, our results found a complex oscillatory behavior of the charging rate, correlating with nanopore size in organic electrolytes. An anomalously increased charging dynamics was found in the 0.9 nm pore. This anomalous enhancement can be attributed to the improved in-pore ion diffusion and reduced desolvation energy, owing to the orientation transition of the solvate molecules. These results pave a new way for innovative designs of nanoporous electrode supercapacitors that can enlarge both power and energy densities.

Molecular Understanding of Charging Dynamics in Supercapacitors with Porous Electrodes and Ionic Liquids

“…These findings suggest that precise control over the pore size can effectively improve the power and energy characteristics of supercapacitors. The oscillatory charging time has been confirmed in supercapacitors using organic electrolytes, 58 but it has not yet been observed in aqueous electrolytes 59 or experiments. 57 Experimentally, electrodes feature a complex pore size distribution, which may obfuscate the nonmonotonic trends observed in simulations.…”