Polymer jelly could lead to cheaper lithium batteries

Posted by Kate Taylor

University of Leeds scientists say they've found a way to make cheaper lithium batteries without compromising performance.

The technology is based on a new polymer jelly, which replaces the liquid electrolytes currently used in rechargeable lithium cells. The team says it can be made into a thin, flexible film using a fully-automated process that's fast, efficient and low cost. 

Traditional lithium-ion batteries, found in most consumer gadgets, are based on cells containing a porous polymer film separator plus liquid chemical filler.

This allows lithium ions carrying the charge to flow between the two electrodes and also acts as a barrier, holding the electrodes apart to prevent short-circuiting. 

But the polymer gel developed by Professor Ian Ward and his team removes the need for this separator. A patented manufacturing process called extrusion/lamination sandwiches the gel between an anode and cathode to create a highly-conductive strip that's just nanometres thick. 

The resultant polymer gel film can be cut to any size. 

"The polymer gel looks like a solid film, but it actually contains about 70 percent liquid electrolyte," says 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 technology has been licensed to Polystor Energy Corporation, which is conducting commercial trials.