Atomistic Insight on the Charging Energetics in Sub-nanometer Pore Supercacitors
- ORNL
- Clemson University
Electrodes featuring sub-nanometer pores can significantly enhance the capacitance and energy density of supercapacitors. However, ions must pay an energy penalty to enter sub-nanometer pores as they have to shed part of their solvation shell. The magnitude of such energy penalty plays a key role in determining the accessibility and charging/discharging of these sub-nanometer pores. Here we report on the atomistic simulation of Na+ and Cl ions entering a polarizable slit pore with a width of 0.82 nm. We show that the free energy penalty for these ions to enter the pore is less than 14 kJ/mol for both Na+ and Cl ions. The surprisingly small energy penalty is caused by the van der Waals attractions between ion and pore walls, the image charge effects, the moderate (19-26%) de-hydration of the ions inside the pore, and the strengthened interactions between ions and their hydration water molecules in the sub-nanometer pore. The results provide strong impetus for further developing nanoporous electrodes featuring sub- nanometer pores.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Sciences (NCCS)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 991682
- Journal Information:
- Journal of Physical Chemistry C, Vol. 114, Issue 41; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- English
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