Process points way to cheaper, more flexible lithium batteries

Cheaper, flexible lithium batteries could be on their way thanks to a new manufacturing process developed at Leeds University.

Scientists led by physics professor Ian Ward have found a way to replace the liquid electrolyte that carries ions between the battery’s electrodes with a gel-like polymer substance.

This means the battery wouldn’t need a porous separator to stop the two sections of electrolyte from mixing or a rigid container to prevent the liquid from leaking out.

‘With having [a battery] that is ultra-thin, flexible, conformable, I think we’re going to revolutionise product design,’ Hugh Rudden, a consultant helping the Leeds team to commercialise the technology, told The Engineer.

‘We need to integrate other parts of the battery and that’s what we’re working on. But the thing that stops a battery from being flexible at the moment is the container.’

The new extrusion manufacturing process is what makes having a flexible solid electrolyte possible, he added.

The gel is sandwiched between an anode and cathode at high speeds of 10m per minute to create a highly conductive strip that is nanometres thick and can be cut into any size.

This permits a fully automated process that also seals the electrodes together so that there is no excess flammable solvent and liquid electrolyte. 

‘The polymer gel looks like a solid film, but it actually contains about 70 per cent liquid electrolyte,’ said Ward.

‘It’s made using the same principles as making a jelly: you add lots of hot water to “gelatine” — in this case there is a polymer and electrolyte mix — and as it cools it sets to form a solid but flexible mass.’

The team is looking for partners from the electronics, automotive and energy industries to help commercialise the technology for practical application. Smaller batteries could be made available within 18 months.