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A 'soft' approach to boosting energy storage

05 August, 2013

Monash University researchers have brought next generation energy storage closer with an engineering first — a graphene-based device that is compact, yet lasts as long as a conventional battery.

Published in Science, a research team led by Professor Dan Li of the Department of Materials Engineering has developed a completely new strategy to engineer graphene-based supercapacitors (SC), making them viable for widespread use in renewable energy storage, portable electronics and electric vehicles.

SCs are generally 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, the drawback of existing SCs is their low energy-storage-to-volume ratio — known as energy density. Low energy density of five to eight Watt-hours per litre, means SCs are unfeasibly large or must be re-charged frequently.

Professor Li's team has created an SC with energy density of 60 Watt-hours per litre — comparable to lead-acid batteries and around 12 times higher than commercially available SCs.

"It has long been a challenge to make SCs smaller, lighter and compact to meet the increasingly demanding needs of many commercial uses," Professor Li said.

Graphene, which is formed when graphite is broken down into layers one atom thick, is very strong, chemically stable and an excellent conductor of electricity.

To make their uniquely compact electrode, Professor Li's team exploited an adaptive graphene gel film they had developed previously. They used liquid electrolytes — generally the conductor in traditional SCs — to control the spacing between graphene sheets on the sub-nanometre scale. In this way the liquid electrolyte played a dual role: maintaining the minute space between the graphene sheets and conducting electricity.

Unlike in traditional 'hard' porous carbon, where space is wasted with unnecessarily large 'pores', density is maximised without compromising porosity in Professor Li's electrode.

To create their material, the research team used a method similar to that used in traditional paper making, meaning the process could be easily and cost-effectively scaled up for industrial use.

"We have created a macroscopic graphene material that is a step beyond what has been achieved previously," Professor Li said.

"It is almost at the stage of moving from the lab to commercial development."

The work was supported by the Australian Research Council.

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Colin Spencer | Monday, August 12, 2013, 11:50 AM
What I need to know is what a storage system would consist of using this technology. I have a 14 kw/hr solar system and I need storage for night usage.
Robert | Monday, August 12, 2013, 12:20 PM
I was thinking the same application. With this system, there will be a quicker transfer to clean energies as you will have fewer losses if you store it yourself. You won't have to rely on the measly buy-back amounts from the electricity companies
jonno | Monday, August 12, 2013, 1:23 PM
At the moment you and I are funding this R&D through the ARC, but when it comes to commercialisation I'll bet there are few companies or individuals willing to invest. Chances are the patents will be sold to some company overseas and we will never see any significant return. We have the people with the skills and ideas, but need more business leaders, future funds and individuals who are willing to accept the risks involved with investing in the development of new technologies and products.
Colin Spencer | Monday, August 12, 2013, 1:23 PM
Also saw an announcement of a new kind of LI battery using a Beryllium anode by a professor from a university at Wollongong, I think. Going into production as we speak. Ten times the storage capacity, and very rapid re-charge. Perhaps we won't have to wait all that long for cheaper storage options.