Final published version
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Solvation effects on aqueous ion adsorption and electrosorption in carbon micropores
AU - Bragg, Ryan J.
AU - Griffiths, Kieran
AU - Hwang, Imgon
AU - Leketas, Mantas
AU - Polus, Kacper
AU - Presser, Volker
AU - Dryfe, Robert A.W.
AU - Griffin, John M.
PY - 2024/10/31
Y1 - 2024/10/31
N2 - Microporous carbonaceous electrode materials store charge by ion electrosorption onto the electrode surface. Despite significant efforts to understand this phenomenon, a definitive picture of the adsorption mechanisms within these complex nanoscale structures is lacking. Here, we use nuclear magnetic resonance (NMR) spectroscopy to directly observe and quantify aqueous adsorbate and adsorbent partitioning behavior driven by spontaneous physisorption within the micropores. Our results show that the solvation properties of the electrolyte ions influence the ionophilicity/ionophobicity of the adsorbate-carbon system, with ionophilic and ionophobic systems exhibiting distinct behavior concerning the electrolyte loading volume. Micropore diameter is also shown to influence spontaneous electrolyte partitioning behavior and disturb ion solvation. In situ NMR spectroscopy using a working supercapacitor comprising microporous carbon electrodes with aqueous sodium sulfate and aqueous sodium bis(trifluoromethane)sulfonimide electrolytes indicates that spontaneous electrolyte partitioning behavior influences the charge-balancing mechanism. Our results suggest that spontaneously ionophilic systems favor charge-balancing by counter-ion adsorption under an applied voltage, and spontaneously ionophobic systems favor a co-ion ejection mechanism under an applied potential. These results provide new molecular-level insight into the role of electrolyte properties on spontaneous physisorption behavior and charged electrosorption behavior within microporous carbon electrodes.
AB - Microporous carbonaceous electrode materials store charge by ion electrosorption onto the electrode surface. Despite significant efforts to understand this phenomenon, a definitive picture of the adsorption mechanisms within these complex nanoscale structures is lacking. Here, we use nuclear magnetic resonance (NMR) spectroscopy to directly observe and quantify aqueous adsorbate and adsorbent partitioning behavior driven by spontaneous physisorption within the micropores. Our results show that the solvation properties of the electrolyte ions influence the ionophilicity/ionophobicity of the adsorbate-carbon system, with ionophilic and ionophobic systems exhibiting distinct behavior concerning the electrolyte loading volume. Micropore diameter is also shown to influence spontaneous electrolyte partitioning behavior and disturb ion solvation. In situ NMR spectroscopy using a working supercapacitor comprising microporous carbon electrodes with aqueous sodium sulfate and aqueous sodium bis(trifluoromethane)sulfonimide electrolytes indicates that spontaneous electrolyte partitioning behavior influences the charge-balancing mechanism. Our results suggest that spontaneously ionophilic systems favor charge-balancing by counter-ion adsorption under an applied voltage, and spontaneously ionophobic systems favor a co-ion ejection mechanism under an applied potential. These results provide new molecular-level insight into the role of electrolyte properties on spontaneous physisorption behavior and charged electrosorption behavior within microporous carbon electrodes.
U2 - 10.1016/j.carbon.2024.119531
DO - 10.1016/j.carbon.2024.119531
M3 - Journal article
VL - 229
JO - Carbon
JF - Carbon
SN - 0008-6223
M1 - 119531
ER -