METAL HYDRIDE CELLS FOR HIGH RATE/LOW TEMPERATURE PERFORMANCE

摘要

A metal hydride rechargeable cell is provided that discharges during a test discharge at a rate of 8 C to 18 C and a cell temperature of 0° C. where the voltage remains above 0.2 volts during the half of the discharge curve. The cell comprises a negative electrode of hydrogen storage alloy material having a particle size volume distribution whose d(50) value does not exceed 2(2Dht)½, where Dh is the hydrogen diffusion coefficient for the alloy at 0° C. and t is a time period from about 200 to about 450 seconds. A method of manufacturing the cell of the present invention involves an activation protocol comprising at least one formation cycle, a heat treating step, and a cycling step. This method avoids unnecessary processing of the metal alloy material prior to incorporation into the negative electrode.