Transforming Supercapacitors by using Metal-Organic Framework Electrodes

Supercapacitors are high power energy storage devices that can complement batteries in a more sustainable future. However, the improvement of supercapacitors is hindered by the disordered structures of the porous carbon electrodes that are used. To date, it has been very challenging to correlate electrode structure with (i) supercapacitor performance, and (ii) the molecular charging mechanism, making it very difficult to design improved devices. The emergence of conducting metal-organic framework (MOF) electrodes with well-defined porous structures provides an excellent opportunity to address these challenges. For the first time, we will use MOFs as model electrode systems to transform our understanding of supercapacitors.

The overarching objective of SUPERMOFS is to correlate electrode structure with the molecular charging mechanism and performance of supercapacitors. To achieve this goal;

1. We will synthesise a series of MOF electrodes where the pore size, surface functional groups, and particle morphologies are varied. Electrochemical measurements on a series of supercapacitors will then reveal the impact of these structural features on energy storage capacities and charging rates. Our use of structurally well-defined electrodes will lead to unprecedented insights into how electrode structure determines supercapacitor performance.

2. Using our series of MOFs, we will reveal how electrode structure determines the molecular charging mechanisms of supercapacitors for the first time. We will develop new in situ nuclear magnetic resonance (NMR) spectroscopy for studying MOF supercapacitors to determine molecular charging mechanisms (ion adsorption, ion exchange etc.), as well as ionic diffusion rates at different cell voltages. These studies will forge a mechanistic bridge between electrode structure and capacitive performance.

Overall, this project will transform our understanding of how supercapacitors work, and will directly lead to improved supercapacitors.