New lithium-ion polymer battery concept for increased capacity

Free-standing films of graphite anode and LiCoO2 cathode materials were produced using 1 wt.% ultra high molecular weight polyethylene (UHMWPE) as a polymeric binder. The technique of vacuum deposition was used in order to provide the anode and cathode materials with 1 μm thick layers of aluminium and copper, respectively, as current collectors. Porous separators were produced by drawing a UHMWPE film filled with inorganic particles. The anode, separator, and cathode materials were then laminated under heat and pressure to produce a single flat cell. The cells were soaked in a liquid electrolyte and sealed in aluminium laminated plastic bags. Batteries produced in this way were cycled at high rates and after 300 cycles only a slight decrease in capacity was observed. Thanks to the thin current collectors and the small amount of polymeric binder the amount of non-active material in the battery was minimised.