Development of a Lead-Acid Battery with High Energy and Power Density

摘要

The energy density of lead-acid cells has been increased to more than 50 Wh5/kg by two different ways: firstly, by means of forced electrolyte flow through the active materials, secondly, by means of a new construction method with a chequered electrode arrangement based on minimized electrolytic and electronic conduction paths, and on optimized volume/surface area proportion. This cell shows particularly at higher loads an outstanding capacity behavior; at the one-hour discharge the energy density is twice of that of the MAN-bus cell. From our present experience we conclude that the energy density of the lead-acid system can be increased up to 60 Wh5/kg. As to the cycle life of the positive electrode, the 'antimony-free effect' causing the premature failure of cells in cycle tests, can now be explained on the basis of a model. As a consequence it will be possible to apply corrosion resistant grid materials without antimony also for cells specifically designed for repeated deep discharges. Due to our improved understanding of the expander mechanism we developed the expander depot and a method of rejuvenating negative plates, which failed because of sintering, using special expander materials. This procedure has been applied successfully to a MAN-bus battery. With reference to the battery periphery our experiences on a H2/02 gas recombination device have resulted in a hermetically sealed lead-acid cell for electric vehicles. For the remote control of the state of charge an indicator with automatic temperature compensation has been developed.