This study investigates the adsorption of aqueous lithium bis-(trifluoromethanesulfonyl)-imide (LiTFSI) electrolyte in porous carbon, specifically YP-50F, using nuclear magnetic resonance (NMR) spectroscopy. The research aims to understand the impact of hydronium (H₃O⁺) and hydroxide (OH⁻) ions on ion adsorption and surface charge distribution. Key findings include: 1. **Pore Size Distribution and Characterization**: The pore size distribution of YP-50F was characterized using nitrogen gas sorption isotherms, revealing extensive microporosity. 2. **H₂O⁺ Adsorption**: pH measurements were used to quantify H₃O⁺ ion adsorption, indicating that YP-50F has a very basic point of zero charge (PZC) of 10.6 ± 0.2, suggesting strong basicity. 3. **Surface Functional Groups**: Boehm acid-base titrations and X-ray photoelectron spectroscopy (XPS) were used to identify and quantify the functional groups on the carbon surface, revealing a higher concentration of basic groups (0.243 ± 0.015 mmol g⁻¹) compared to acidic groups (0.023 ± 0.002 mmol g⁻¹). 4. **NMR Spectroscopy**: Solid-state NMR experiments were conducted to study the adsorption of LiTFSI electrolyte in YP-50F. The results showed rapid exchange between ions in the bulk electrolyte and in carbon pores, with significant H₃O⁺ adsorption under acidic conditions. 5. **Quantitative Analysis**: A two-site exchange model was used to deconvolute NMR spectra, quantifying the total in-pore Li⁺ and TFSI⁻ concentrations as 1.6 ± 0.1 and 1.7 ± 0.1 mmol g⁻¹, respectively. 6. **Electrochemical Characterization**: Symmetric two-electrode supercapacitors were assembled to study the impact of pH on capacitance. The results showed a maximum capacitance of 141 F/g in acidic electrolytes (pH = 0.51), followed by 96 and 83 F/g in neutral and basic electrolytes (pH = 7.03 and 11.48), respectively. The study highlights the importance of considering H₃O⁺ and OH⁻ ions in understanding ion adsorption and charge storage mechanisms in porous carbons, providing a methodology to relate local structure to function and performance in energy applications.This study investigates the adsorption of aqueous lithium bis-(trifluoromethanesulfonyl)-imide (LiTFSI) electrolyte in porous carbon, specifically YP-50F, using nuclear magnetic resonance (NMR) spectroscopy. The research aims to understand the impact of hydronium (H₃O⁺) and hydroxide (OH⁻) ions on ion adsorption and surface charge distribution. Key findings include: 1. **Pore Size Distribution and Characterization**: The pore size distribution of YP-50F was characterized using nitrogen gas sorption isotherms, revealing extensive microporosity. 2. **H₂O⁺ Adsorption**: pH measurements were used to quantify H₃O⁺ ion adsorption, indicating that YP-50F has a very basic point of zero charge (PZC) of 10.6 ± 0.2, suggesting strong basicity. 3. **Surface Functional Groups**: Boehm acid-base titrations and X-ray photoelectron spectroscopy (XPS) were used to identify and quantify the functional groups on the carbon surface, revealing a higher concentration of basic groups (0.243 ± 0.015 mmol g⁻¹) compared to acidic groups (0.023 ± 0.002 mmol g⁻¹). 4. **NMR Spectroscopy**: Solid-state NMR experiments were conducted to study the adsorption of LiTFSI electrolyte in YP-50F. The results showed rapid exchange between ions in the bulk electrolyte and in carbon pores, with significant H₃O⁺ adsorption under acidic conditions. 5. **Quantitative Analysis**: A two-site exchange model was used to deconvolute NMR spectra, quantifying the total in-pore Li⁺ and TFSI⁻ concentrations as 1.6 ± 0.1 and 1.7 ± 0.1 mmol g⁻¹, respectively. 6. **Electrochemical Characterization**: Symmetric two-electrode supercapacitors were assembled to study the impact of pH on capacitance. The results showed a maximum capacitance of 141 F/g in acidic electrolytes (pH = 0.51), followed by 96 and 83 F/g in neutral and basic electrolytes (pH = 7.03 and 11.48), respectively. The study highlights the importance of considering H₃O⁺ and OH⁻ ions in understanding ion adsorption and charge storage mechanisms in porous carbons, providing a methodology to relate local structure to function and performance in energy applications.