To curb greenhouse gas emissions and reduce air pollution problems, the use of renewable energy to replace fossil fuels is now considered the best solution. This points at strong demand for new and improved energy storage technology.
Meanwhile, as part of the effort for the improvement of this technology, recently, a research group found that ionophobic electrodes can boost the performance of energy storage.
The study is published in the Journals of Materials Chemistry.
Working as a new device to store energy, electric double-layer capacitors with ionic liquids can fill the gap between energy density of conventional capacitors and power density of batteries. However, the ionic liquids in nanopores often display slow diffusion dynamics, which slows high power density.
For the study, researchers proposed a new strategy to improve the energy density synergistically and power density of electric double-layer capacitors with ionic liquids based on massive molecular dynamics simulations.
To undertake this, the research group built a series of electric double-layer capacitors with different wettability, wherein 1-ethyl-3-methylimidazolium tetrafluoroborate is used the electrolyte.
The comparison of electric double-layer with an ionophilic electrode with an one with an extremely ionophobic electrode revealed that the charging time for the latter reduced by nearly 80%, and the capacitance increased by almost 100%.
In fact, for electric double-layer capacitors with an ionophobic electrode, ionic liquids are unable to spontaneously enter the porous electrode without charging. The increase of charging voltage enables the counter ion and co-ion to start to enter the nanopore when the voltage is beyond one critical figure. This is complemented with faster diffusion dynamics of ions than bulk ionic liquids due to fewer ions in the pore.