TWI has worked with a national utility company to develop specialised joining techniques for a large-scale energy storage system. At the heart of the system is a fuel cell module comprising electrodes, ion selective membranes and protective housings. The integrity of the joints between these elements is critical. Any leakage across these components would affect the efficiency of the energy storage process, in some cases leading to complete failure.
TWI and the utility worked together to develop the technology for joining the electrodes to their protective frame using transmission laser welding. Laser welding was selected following comparison with many other plastics processes because of the ability to make high speed sealed joints between components with a seam length over 3m long. A technique using clamped components and a robotically manipulated laser was found to be successful.
TWI has also contributed to several other aspects of the development of the cell manufacture including investigating methods to join the membrane to the supporting frames and the surfacing of electrodes.
As well as ensuring the integrity of the joints the processes developed promise substantial savings in production costs.