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Kinetic-Dominated Charging Mechanism within Representative Aqueous Electrolyte-based Electric Double-Layer Capacitors
Huachao Yang1, Jinyuan Yang1, Zheng Bo1
1State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, College of Energy Engineering, Zhejiang University , Hangzhou, Zhejiang Province 310027, China.
The Journal of Physical Chemistry Letters
|July 26, 2017
Summary
Aqueous electrolytes in electric double-layer capacitors (EDLCs) charge via kinetics, not just ion structure. Ion-solvent interactions, not ion size or valence, are key for EDLC performance.
Area of Science:
- Electrochemistry
- Materials Science
- Physical Chemistry
Background:
- Electrolytes are crucial for electric double-layer capacitors (EDLCs) charge storage.
- The primary charge storage mechanisms in EDLCs are not fully understood and remain controversial.
Purpose of the Study:
- To systematically explore electric double-layer (EDL) structures and kinetics in aqueous electrolytes.
- To investigate the influence of ion size, valence, and mixtures on EDL capacitance and kinetics.
- To elucidate the role of solvent dielectric properties in EDLC charge storage.
Main Methods:
- Numerical simulations of EDL structures and kinetics.
- Experimental electrochemical measurements.
- Analysis of ion-solvent interactions.
Main Results:
- A novel charging mechanism dominated by kinetics was identified, challenging traditional views.
- Diverse ion characteristics (size, valence, mixtures) resulted in similar EDL capacitance.
- Solvent dielectric properties significantly attenuated ionic effects, unlike in solvent-free systems.
- EDL kinetics varied with ionic species and were closely linked to ion-solvent interactions.
Conclusions:
- EDLC performance is primarily regulated by kinetic processes and ion-solvent interactions, rather than solely by interfacial structural variations.
- The dielectric nature of solvents plays a critical role in attenuating the influence of ionic species on EDL capacitance.
- This study provides new insights into the fundamental mechanisms governing EDLC charge storage.
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