Dipping Electrodes in Carbon Nanotubes may improve ultracapacitors and batteries

 

Image sources: Wikipedia, TechnologyReview

Ultracapacitors are capacitors with higher energy density - typically hundreds of times greater than conventional electrolytic capacitors. They provide quick bursts of power and can be recharged infinitely without losing storage capacity, but at most they can only store a 1/10 as much energy as batteries. A new technique developed by Stanford University researchers enabled the use of new types of nanostructured electrode materials that store more energy. More details after the break.


In order to improve the their energy density, researchers have focused on the use of electrode materials with greater surface area - graphene and carbon nanotubes for example, which holds more charge-carrying ions. Based on the top right image, graphic A shows carbon nanotubes (CNT) while graphic D shows Poly(3,4-ethylenedioxythiophene) or simply PEDOT. PEDOT nanofibers are produced from vanadium pentoxide nanofibers by a nanofiber seeding method.

The Stanford team led by Yi Cui and Zhenan Bao used composite electrodes made from graphene and manganese oxide. Manganese oxide is ideal due to its abundance and excellent cost-to-usage ratio, on top of high theoretical capacity to store ions for supercapacitors. Previously the idea was scrapped due to its low conductivity, which resulted in a difficulty of ion transfer. The researchers dipped the composite electrodes into either a carbon nanotube solution or a conductive polymer solution which provides a coating that improves the electrodes' conductivity by 20% and charge storage by 45%. Read the link below for the complete article.

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