This work has demonstrated the application of solid-state NMR spectroscopy for understanding the ion adsorption and charge storage mechanisms of conductive layered metal-organic frameworks. Importantly, our NMR spectra of Ni3(HITP)2 soaked with a traditional supercapacitor organic electrolyte reveal distinct resonances for in-pore and ex-pore BF4 -anions, providing the opportunity to study the electric double layer in these materials during charging. The chemical shift of the in-pore resonance was further revealed to be determined by specific anion-MOF interactions, an observation which was supported by QM/MM and DFT simulations. Solid-state NMR has also demonstrated potential for high throughput screening of the electrochemical performance of layered MOFs, with significantly improved efficiency compared to traditional N2 gas sorption experiments. Furthermore, for the first time, ex-situ NMR measurements were used to gain experimental insights into the charging mechanism of a layered MOF, Ni3(HITP)2, with organic electrolytes, and revealed only a minimal contribution of anions. Subtle changes in the in-pore chemical shift were seen on charging, which in combination with QM/MM simulations, are linked to a redistribution of anions between two key in-pore environments. Given the coupled experimental challenges of obtaining peak resolution in NMR (i) under static conditions and (ii) of the cation environments in this system, we emphasise the need for both the development of spinning in-situ NMR systems and combining NMR with other techniques for a complete mechanistic study. As such, EQCM experiments supported the idea that cations are the dominant charge carriers in this system, and additionally highlighted the importance of the solvent in the charging mechanism, a contribution which is yet to be fully understood in these systems. The specific MOF-electrolyte interactions observed by NMR in these systems is in contrast with activated carbons typically used in supercapacitors and therefore presents a unique opportunity for MOF-based systems. These interactions may be explored and exploited further to modify their strength, and therefore to both modulate the charging mechanism, and optimise supercapacitor performance. As such, this work offers a number of pathways for solid-state NMR to be used to aid the future design of supercapacitors.