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Conductive plastics show potential for use in future batteries

2014-10-14

Conductive plastics may be possible to use in batteries of the future, instead of the metal oxides used today. In his thesis, PhD student Christoffer Karlsson has studied and tested a few such polymers and shown that they have potential. The 30 October he will defend his thesis at Uppsala University.

The demand for environmentally friendly batteries has surged in recent years. They play an important role in a sustainable society. For instance, the battery of an electric car needs to be manufactured in a way that signifies an environmental gain compared to a car running on petrol.

Todays lithium ion batteries in electric cars, phones and laptops use metal oxides which are extracted from rock through energy-intensive processes and are not recycled. Christoffer Karlsson has in his thesis investigated a new class of organic materials for this purpose, namely conductive redox polymers, a type of electrically conductive plastics.

The many unique properties of conductive polymers have led to a number of different areas of use for these materials. Metallic conductivity which can be regulated is perhaps their most important property, and the possiblity to manufacture them cheaply at low temperatures. Both conductive polymers and redox polymers have been used for energy storage, and lately there has been greatly increased interest in low molecular weight organic compounds as active materials in battery electrodes. The primary reason for this is that they can be manufactured from renewable sources through environmentally friendly methods at low temperatures, as opposed to today’s inorganic materials.

The thesis shows how a number of conductive redox polymers behave, and gives a few design principles for this type of polymers.

‘They have potential as electrode materials in future environmentally friendly batteries, and it would be possible to make organic batteries purely from polymers. We have also tested one such proof-of-concept battery cell, with different conductive redox polymers as active materials on both electrodes’, says Christoffer Karlsson.