Spinning a solid-state carbon nanofibre supercapacitor

Technology News |
By Nick Flaherty

The design for a new supercapacitor by Dr Vibha Kalra, a professor in Drexel’s College of Engineering, uses am ion-rich gel electrolyte absorbed into a freestanding mat of porous carbon nanofibres created by electrospinning. This eliminates the volatile solvents that can cause fires.

“We have completely eliminated the component that can catch fire in these devices,” said Kalra. “In doing so, we have also created an electrode that could enable energy storage devices to become lighter and better.”

The process deposits a carbon precursor polymer solution in the form of a fibrous mat by extruding it through a rotating electric field. The ionogel is then absorbed in the carbon fibre mat to create a complete electrode-electrolyte network with the electrode and electrolyte making contact over a larger surface area.

Not only is the group’s supercapacitor solvent-free but the compact design is also more durable and its energy storage capacity and charge-discharge lifespan are better than comparable devices currently being used and can operate up to 300 ºC.

“To allow industrially relevant electrode thickness and loading, we have developed a cloth-like electrode composed of nanofibers that provides a well-defined three-dimensional open pore structure for easy infusion of the solid electrolyte precursor,” she said. “The open-pore electrode is also free of binding agents that act as insulators and diminish performance. State of the art electrodes are composed of fine powders that need to be blended with binding agents and made into a slurry, which is then applied into the device. These binders add dead weight to the device, as they are not conductive materials, and they actually hinder its performance. Our electrodes are freestanding, thus eliminating the need for binders, whose processing can account for as much as 20 percent of the cost of manufacturing an electrode.”

The next step for Kalra’s group will be applying this technique to the production of solid-state batteries as well as exploring its application for smart fabrics.

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