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Effects of Surface Transition and Adsorption on Ionic Liquid Capacitors
Huikuan Chao1, Zhen-Gang Wang1
1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
The Journal of Physical Chemistry Letters
|February 11, 2020
Summary
Room-temperature ionic liquids (RTILs) offer superior electrochemical stability for capacitors. This study reveals spontaneous surface charge separation in RTILs, enhancing energy storage through tailored electrode treatments.
Area of Science:
- Electrochemistry
- Materials Science
- Physical Chemistry
Background:
- Room-temperature ionic liquids (RTILs) possess superior electrochemical stability compared to aqueous electrolytes, enabling wider electrochemical windows for capacitor applications.
- Existing RTIL models often do not fully account for ion-ion correlations and nonelectrostatic interactions in solvent-free systems.
Purpose of the Study:
- To propose and utilize an advanced RTIL model incorporating ion-ion correlations and nonelectrostatic interactions.
- To investigate spontaneous surface charge separation in RTIL-based capacitors.
- To explore the impact of asymmetric ion adsorption on charge separation and energy storage.
Main Methods:
- Development of a modified RTIL model accounting for ion-ion correlations and nonelectrostatic interactions.
- Simulation and analysis of spontaneous surface charge separation in RTIL capacitors.
- Investigation of preferential ion adsorption effects on charge separation transitions.
Main Results:
- Spontaneous surface charge separation is identified as a common phenomenon in most RTILs under realistic model parameters.
- Asymmetric preferential ion adsorption significantly influences the charge separation transition.
- Enhanced energy storage is achievable when the charge separation transition is approached.
Conclusions:
- Differential chemical treatment of electrodes is a practical strategy for optimizing energy storage in RTIL capacitors.
- The proposed RTIL model provides valuable insights into the behavior of solvent-free ionic liquid electrolytes.
- Understanding and controlling ion adsorption is key to maximizing the performance of RTIL-based energy storage devices.
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