New Graphene-Based Supercapacitors Hold Potential for Renewable Energy Storage

Energy storage is a huge issue for our society. More efficient storage could mean that we'd need to use fewer natural resources, which could allow us to help prevent long-term environmental impacts. Now, scientists have developed a new generation energy storage system that is compact, yet lasts as long as a conventional battery.

Graphene-based supercapacitors (SC) are viewed as a prime target for research when it comes to making renewable energy storage. SCs themselves are usually made of highly porous carbon impregnated with a liquid electrolyte to transport the electrical charge. Known for their almost indefinite lifespan and the ability to re-charge in seconds, their only drawback is their low energy-storage-to-volume ratio, known as energy density. This means that powerful SCS are usually too large to be practical.

"It has long been a challenge to make SCs smaller, lighter and compact to meet the increasingly demanding needs of many commercial uses," said Dan Li, one of the researchers, in a news release.

This newest SC, though, takes energy storage to another level. The creation has an energy density of 60 Watts-hours per liter. That's comparable to lead-acid batteries and is around 12 times higher than commercially available SCs. In order to create the new compact electrode, the researchers used an adaptive graphene gel film. They then employed liquid electrolytes to control the spacing between graphene sheets on the sub-nanometer scale. In this way, the liquid electrolyte played a dual role; it maintained the minute space between the graphene sheets and conducted electricity.

"We have created a microscopic graphene material that is a step beyond what has been achieved previously," said Li. "It is almost at the stage of moving from the lab to commercial development."

In fact, the material is made using a method that's similar to that used in traditional paper making. This means that the process could be easily scaled up for industrial use.

The findings are published in the journal Science.