CYCLE LIFE TEST OF LEAD DIOXIDE ELECTRODES IN COMPRESSED LEAD ACID CELLS

Flat pasted lead dioxide electrodes of SLI-type have been studied in compressed lead/acid batteries and tested with respect to cycle life and polarization during galvanostatic charge and discharge cycling. Three different sets of separators have been tested in order to verify the importance of the applied mechanical pressure and the effects of using separators with different permeability. It was found that it was possible to increase the life from about 90 cycles for a non-pressurized cell with standard separators to about 1150 cycles for a pressurized cell with a multilayer separator with a thin polyester fabric closest to the lead dioxide electrode. Cells with glass-fiber mats closest to the lead dioxide electrodes had a lifetime of about 750 cycles. It was found that the changes in the cell voltages with increasing cycle number could be correlated to transformation of the active material and loss of lead dioxide due to shedding. Further, it was observed that the reasons for cell failure were closely related to the permeability of the separators and the applied pressure. It is also concluded that flat pasted electrodes in pressurized cells could be a very attractive alternative to cells with tubular lead dioxide electrodes.