LIVERMORE, CALIF. (Sept. 12, 12:30 p.m. ET) — University of Leeds scientists have invented a new type of polymer gel that can be used to manufacture cheaper lithium batteries without compromising performance.
The technology, developed by Professor Ian Ward FRS, has been licensed to Livermore-based Polystor Energy Corp., which is conducting trials to commercialize cells for portable consumer electronics.
Ward believes the new material could replace the liquid electrolytes currently used in rechargeable lithium cells. Furthermore, the gel can be made into a thin, flexible film via a fully automated process that is fast, efficient and potentially inexpensive.
Rechargeable lithium-ion batteries are the preferred power source for a wide range of portable consumer electronics such as laptops, digital cameras, mobile phones and MP3 players.
The traditional configuration for the batteries is based on cells (sealed containers), which contain a liquid chemical filler and a porous polymer film separator. Lithium ions carry an electrical charge between the two battery electrodes, while the separator holds the electrodes apart to prevent short-circuiting.
The polymer gel developed by Ward and his team removes the need for the separator. They have also developed a patented manufacturing process called extrusion/lamination which sandwiches the gel between an anode and cathode at high speed (10m per minute) to create a highly conductive strip only nanometers thick.
The resulting polymer gel film can be cut to any size, permitting a fully-automated process which is cited as both cost effective and safe. The lamination process also seals the electrodes together so that there is no excess flammable solvent or free liquid electrolyte.
“The polymer gel looks like a solid film, but it actually contains about 70 percent liquid electrolyte,” Ward said. “It's made using the same principles as producing an edible jelly: you add lots of hot water to a polymer/electrolyte mix, rather than gelatine. As the solution cools it sets to form a solid but flexible mass.”
As well as being safe and damage-tolerant, the flexible cells can be shaped and bent to fit the geometries of virtually any device.
The Leeds research was funded by the Engineering and Physical Sciences Research Council and Yorkshire Concept.