How disordered materials could boost supercapacitor performance

Xinyu Liu with a models of graphene (left) and a disordered carbon electrode (right). Credit: Nathan Pitt.

Supercapacitors, devices that charge extremely quickly compared to traditional batteries, could see a significant performance boost thanks to new research from the University of Cambridge.

This study shows that a more chaotic internal structure in these devices might be the key to storing more energy.

Like their name suggests, supercapacitors are a bit like super-charged versions of capacitors, traditional components in electronic devices that store electrical energy temporarily.

They fill up with power in just a few seconds or minutes, endure millions of charge and discharge cycles, and are tougher than regular batteries.

However, they haven’t quite caught up in terms of how much energy they can hold — a measure known as energy density.

This new research, detailed in the journal Science, finds that the more disorderly and “messy” the materials inside supercapacitors are, the better these devices perform. This goes against previous beliefs where a neat, ordered structure was considered ideal.

Dr. Alex Forse, who led the research at Cambridge’s Yusuf Hamied Department of Chemistry, explains that supercapacitors are built using porous carbon electrodes — imagine a sponge-like material that can quickly absorb and release electrical charge.

Researchers have been trying to understand the best way to enhance these electrodes to improve supercapacitors’ energy density.

Traditionally, scientists thought the tiny holes in these porous materials, known as nanopores, needed to be a certain size to optimize energy storage.

However, Forse’s team, using advanced techniques like nuclear magnetic resonance (NMR) spectroscopy — which is somewhat like an MRI but for batteries — discovered that it’s not the size of these holes that matters. Instead, it’s how disorganized the carbon material is.

In their experiments, the Cambridge researchers used NMR spectroscopy to observe how the atoms in these materials behave.

They noticed that more chaotic materials showed different patterns in their NMR spectrum compared to orderly ones. Surprisingly, these messier materials were capable of holding almost double the energy of their tidier counterparts.

Xinyu Liu, a Ph.D. candidate and first author of the study, mentions that this finding was unexpected.

The team wasn’t initially looking for a link between disorder and performance. The discovery came while they were experimenting with various commercially available carbon electrodes.

This breakthrough suggests that embracing the chaos within these materials could be a game-changer for supercapacitors, helping to propel them forward as a viable technology for energy storage.

Such a development is crucial for applications where rapid charging is essential, such as in public transport systems.

Imagine buses, trains, or metros that can charge completely in the few minutes it takes for passengers to board and alight, all without the need for extensive charging infrastructure.

The implications of this research are not just limited to public transport. Supercapacitors can also help manage the unpredictable nature of renewable energy sources like solar and wind, providing quick bursts of power when needed.

Looking ahead, the Cambridge team is excited to explore new ways of manufacturing these disordered materials to maximize their potential.

By further understanding and harnessing this “messiness,” they hope to unlock new possibilities for energy storage that could help transition to a more sustainable future.

This study not only highlights a surprising aspect of materials science but also opens the door to improving a technology that’s been in a bit of a development rut, showing how a little disorder can lead to much better performance.

Source: University of Cambridge.