A new carbon composite

This composite can be viewed as a substitute to assembling two separate components that could aid electric vehicles by constructing bodywork which stocks power too, thus saving up on space as well as weight.

‘Multifunctional structural energy materials hold great promise in enabling more energy efficient and environmentally-friendly technologies, as they will make a considerable difference in terms of how we store and deliver energy in the future,’ says Guihua Yu, an energy storage specialist at the University of Texas in Austin, US.

Milo Shaffer of Imperial College of London, UK, is of the idea that carbon based materials are the base of various structural composites as well as electrochemical devices. He created a material that combined the strength and stiffness of structural carbon fibers and the ionic conductivity of activated carbon.

A crucial part of the study revolved around increasing the surface area of structural carbon fibers for usage as supercapacitor electrodes. The surface area and specific capacitance could be increased by three orders of magnitude formation of highly porous carbon aerogel around the fibers and this provided added benefits to its mechanical properties.

Shaffer confirms that the main challenge of the study arrived in the form of multifunctional electrolyte which needs to combine mechanical properties with ionic conductivity – two essentially inverse concepts. A balance in the performance levels was achieved by coming up with a bicontinuous structure consisting of an epoxy resin for its mechanical properties and an ionic liquid for purpose of ionic conduction.

The composites have a laminated nature and this helps energy storage devices like for instance lithium ion batteries, and the like. The question remains – ‘Why a supercapacitor then?’ Batteries have a lot of issues with volume expansion and therefore it is a tad bit difficult to make these devices well structured. Shaffer explains, ‘which is why we found supercapacitors interesting; you can have a useful energy function but don’t necessarily have any volume change.’

There is something else that needs a mention too: the power density of the material – which happens to be lower than the current technologically advanced supercapacitors. Nevertheless, Shaffer is conscious of the shortcomings of the material and the development of such a system is no easy task.