Philips Developing Pre-Shaped Lithium-Ion Batteries

Royal Philips Electronics (the Netherlands) reported that it is developing pre-shaped lithium-ion batteries to enable more design freedom in hand-held electronic products. The cells are based on conventional lithium-ion technology, but are "riveted" together using a polymer. Initial storage capacity of the pre-shaped battery is around 800 mAh; falling to 85% after 400 cycles.

The batteries are built by stacking double-sided electrodes made from standard LiCoO2 material between a single-sided cathode and a single-sided anode. Each electrode is pre-punched with a pattern of small holes around 1 mm in diameter. A sheet of lithylene polymer is placed on the top and bottom of the stack, and separator layers are placed between the electrodes. To create channels through the stack the layers are melted using heated needles.

When the whole stack is annealed at 120 °C the lithylene melts through the holes, and on cooling the stack is mechanically stable. The battery adopts the shape of any pre-form it is cooled over. The final steps are packaging in a polymer-coated aluminium foil, introduction of the electrolyte, evacuation and sealing. The company reports that despite the innovation, reducing the power consumption of devices is still key.