Printable polymers for (future) biodegradable batteries

Researchers inch towards a biodegradable way to power small devices.

What if, instead of a rigid chunk of lithium-ion, your phone was charged by a flexible, printable battery? And what if that battery were biodegradable?

According to a group of Australian and Chinese researchers, this is possible with technology they’re working on. Such batteries would probably only ever be powerful enough to charge small devices but, at least in the lab, they’re rivalling lithium-ion at the small scale.

The research revolves around organic radical batteries, or ORBS. These batteries rely on a carboncontaining polymer to store and transport electrons. They don’t require any metals to make, so while the materials aren’t currently biodegradable, it should be possible to create them from a biodegradable material.

ORBS aren’t a new concept, but so far several features are inferior to commercial batteries, according to Dr Zhongfan Jia, a researcher in chemistry at Flinders University in Adelaide.

The first is the batteries’ voltage: the force with which they can discharge power.

The next problem is capacity – what we might think of as storage. “Capacity is how much energy you can put in,” says Jia.

The third issue is power density.“if you have a fancy racing car, it might be accelerated from 0 to 100 km/h within six or seven seconds. That difference is related to the power density,” says Jia.

Jia and colleagues have found a catalyst that allows these batteries to compete with lithium-ion in both voltage and storage capacity.

In Chemical Engineering Journal, they described a prototype battery with a voltage of 2.8 V – one of the highest voltages ever reported in an ORB.