Graphene & Batteries

Battery technology is quickly evolving, with dozens of competing alternative chemistries challenging the dominance of lithium-ion batteries

Graphene is a promising material for use in batteries due to its high electrical conductivity and thermal conductivity. A recent discovery by researchers at Swansea University, in collaboration with Wuhan University of Technology and Shenzhen University, could pave the way for the use of graphene in lithium-ion batteries, helping to keep them as the dominant battery technology over alternative chemistries, including graphene-based batteries.

The researchers' publication in Nature Chemical Engineering details the first successful protocol for fabricating defect-free graphene foils on a commercial scale. The method can be used to create graphene foils in lengths ranging from meters to kilometers. In a laboratory setting not designed for mass production, they managed to create a 200-meter-long graphene foil with a thickness of 17 micrometers. The foil is also highly resistant and was demonstrated to retain high electrical conductivity even after being bent over 100,000 times, making it suitable for use in flexible electronics, industrial manufacturing, and other applications where the graphene is used to deploy powerful currents.

The application that the researchers focused on in their study is the use of the graphene foil as a current collector in lithium-ion batteries. Lithium-ion batteries are vulnerable to a key risk, called thermal runaway, which happens when excessive heat accumulates in a part of the battery, leading to battery failure with dangerous fires or explosions. This issue is one of the key reasons many researchers and battery companies are looking beyond lithium-ion with alternative chemistries like sodium-ion. Many alternative solutions are being explored, for example, gel electrolytes.

Thermal runaway mostly happens at the battery's current collectors, where the most power is concentrated. In current lithium-ion batteries, current collectors are usually made of aluminum or copper. The graphene current collectors developed by the research with their graphene foil can display a thermal conductivity as high as 1,400.8 W m−1 K−1. For reference, this is almost 10x higher than copper and aluminum-based current collectors.

Because the graphene foil shows a very fast heat dissipation, it eliminates the risk of local heat concentration when the current is flowing. In turn, this removes the risks of aluminothermic and hydrogen-evolution reactions which are the critical steps leading to propagation of the battery failure and fire hazard.

“Our dense, aligned graphene structure provides a robust barrier against the formation of flammable gases and prevents oxygen from permeating the battery cells, which is crucial for avoiding catastrophic failures,”

Dr Jinlong Yang, co-lead author

Maybe more importantly, the method is already proven to be deployable with mass manufacturing of the graphene foil. So it could be quickly integrated into existing battery manufacturing processes.

“This is a significant step forward for battery technology. Our method allows for the production of graphene current collectors at a scale and quality that can be readily integrated into commercial battery manufacturing. This not only improves battery safety by efficiently managing heat but also enhances energy density and longevity.”

Dr Rui Tan, co-lead author

The researchers are already looking at ways to reduce the thickness of the graphene foils and further enhance their mechanical properties. They are also looking at how the graphene foil could help design better flow batteries and sodium-ion batteries, in collaboration with another research team at Swansea University, under Pr. Serena Margodonna’s leadership.

We previously discussed honeycomb lithium-ion batteries that remove the risk of battery failure from dendrite growth. If thermal runaway also can be suppressed thanks to graphene foil, this could make lithium-ion batteries much more safe and durable than the current version.

This overall follows the pattern of most innovations in one niche of battery technology to be usable in other designs, helping feed the quick progress of the industry.

(You can also learn more about battery technology in our articles “The Future of Mobility – Battery Tech” and “The Future Of Energy Storage – Utility-Scale Batteries Tech”.)

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