Zinc/Silver Oxide Batteries
Alsocalled Silver Zinc Batteries
Characteristics
Common low capacity primary button cell versions aretypically called Silver Oxide batteries. Higher capacityversions available as secondary cells are more often referred to asSilver Zinc batteries. They have an open circuit voltage of1.6 Volts. Two types of Silver Oxide batteries are available, onetype with a sodium hydroxide (NaOH) electrolyte and the other witha potassium hydroxide (KOH) electrolyte.
Because of the high cost of sliver they are available ineither very small sizes as button cells where the amount of silverused is small and not a significant contributor to the overallproduct costs or they are available in very large sizes forcritical applications where the superior performancecharacteristics of the silver oxide chemistry outweigh any costconsiderations.
Advantages
High capacity per unit weight.
Long operating life. A tiny button cell will keep a watchrunning 24 hours per day for 3 to 5 years!!
Low self discharge and hence long shelf life (better thanzinc air)
Better low temperature performance than zincair
Flat discharge characteristics - flatter than the AlkalineManganese Dioxide battery.
Higher voltage than zinc mercury cells..
Shortcomings
Uses expensive materials.
Lower energy density than zinc air.
Poor low temperature performance.
Limited cycle life.
Suffers from dissolving of the Zinc and the formation ofZinc dendrites which pierce the separator.
Applications
A major contribution to miniature powersources.
As a button cell it is well suited for hearing aids,instruments, photographic applications, electronic watches andother low power devices.
Larger size Silver Zinc batteries are used in submarines,missiles, underwater and aerospace applications.
Silver Zinc secondary cells being promoted as a saferalternative to Lithium cells. Plans to mitigate the higher costs byimplementing a recycling programme.
Costs
More expensive than zinc air
Very expensive for high power applications