The energy density of supercapacitors -- battery-like devices that can charge in seconds or a few minutes -- can be improved by increasing the 'messiness' of their internal structure. Researchers used experimental and computer modelling techniques to study the porous carbon electrodes used in supercapacitors. They found that electrodes with a more disordered chemical structure stored far more energy than electrodes with a highly ordered structure.
Supercapacitors are a key technology for the energy transition and could be useful for certain forms of public transport, as well as for managing intermittent solar and wind energy generation, but their adoption has been limited by poor energy density., represent a breakthrough in the field and could reinvigorate the development of this important net-zero technology.
A bus, train or metro powered by supercapacitors, for example, could fully charge in the time it takes to let passengers off and on, providing it with enough power to reach the next stop. This would eliminate the need to install any charging infrastructure along the line. However, before supercapacitors are put into widespread use, their energy storage capacity needs to be improved.
Many scientists have thought that the size of the tiny holes, or nanopores, in the carbon electrodes was the key to improved energy capacity. However, the Cambridge team analysed a series of commercially available nanoporous carbon electrodes and found there was no link between pore size and storage capacity.
When analysing the electrode materials with NMR spectroscopy, a spectrum with different peaks and valleys is produced. The position of the peak indicates how ordered or disordered the carbon is."It wasn't our plan to look for this, it was a big surprise," said Forse."When we plotted the position of the peak against energy capacity, a striking correlation came through -- the most disordered materials had a capacity almost double that of the most ordered materials.
The research was supported in part by the Cambridge Trusts, the European Research Council, and UK Research and Innovation .Xinyu Liu, Dongxun Lyu, Céline Merlet, Matthew J. A. Leesmith, Xiao Hua, Zhen Xu, Clare P. Grey, Alexander C. Forse.Solid-state batteries pack a lot of energy into a small space, but their electrodes are not good at keeping in touch with their electrolytes. Liquid electrolytes reach every nook and cranny of an ...