TABLE OF CONTENTS The rechargeable nickel-zinc battery was invented in 1899 and in the 1920s batteries were constructed but found to have a short cycle life. This was shown to be due to the growth of dendrites on the zinc plate during charging, a condition which short-circuited the battery. At the time no further development was done, but in recent years the high-energy density and power density possible with this battery has increased interest in its use in electric vehicles. Although an energy density of 70 Wh/kg and a power density of 150 W/kg has been obtained, the fundamental problem of dendrite growth (common to all zinc-based batteries), which limits the maximum number of deep discharge cycles to less than 300, has, although improved, not been overcome. It is caused by the high solubility of zinc oxide which is a discharge product of the negative zinc electrode in the alkaline potassium hydroxide electrolyte. This high solubility results in zinc dendrite formation during charging, as well as shape change and densification of the negative electrode on repeated charge/discharge cycles. Also, active material is lost from the negative electrodes by deposition of zinc oxide in the separators.
Lifetime has been improved to 300 cycles of deep discharge by the use of electrochemically impregnated sintered nickel positive electrodes, rollbonded zinc oxide negative electrodes and special microporous separators which have to be designed to optimise mass transfer while retaining adequate dendrite penetration resistance.
Work has also been done to inhibit dendrite growth by various other...
