HIGH-SURFACE-AREA, LOW-WEIGHT COMPOSITE NICKEL FIBER ELECTRODES

The energy density and power density of lightweight aerospace batterie s utilizing the nickel oxide electrode are often limited by the micros tructures of both the collector and the resulting active deposit inion the collector. Heretofore, these two microstructures have been intima tely linked to one another by the materials used to prepare the collec tor grid as well as the methods and conditions used to deposit the act ive material. Significant weight and performance advantages have been demonstrated by Britton and Reid at NASA-LeRC using FIBREX nickel mats of similar to 28-32 mu m diameter. Work in our laboratory has investi gated the potential performance advantages offered by nickel fiber com posite electrodes containing a mixture of fibers as small as 2 mu m di ameter (available from Memtec America Corporation). These electrode co llectors possess in excess of an order of magnitude more surface area per gram of collector than FIBREX nickel. The increase in surface area of the collector roughly translates into an order of magnitude thinne r layer of active material. Performance data and advantages of these t hin layer structures will be presented. Attributes and limitations of their electrode microstructure to independently control void volume, p ore structure of the NI(OH)(2) deposition, and resulting electrical pr operties will be discussed.