What is a Silver-Oxide Battery?

PrintEmailSave

Main Image: 

A silver oxide battery is a primary cell, in which the reaction cannot be reversed by running current into the cell. It is also known as a silver–zinc battery, because they are typically composed of silver-oxide, which is used as the positive electrode, and zinc, which is used as the negative electrode. Silver oxide batteries have a long durability and very high energy/weight ratio, but unaffordable cost for most applications due to the high price of silver. They are available in either very small sizes as button cells where the amount of silver used is small and not a significant contributor to the overall product costs, or in large custom design batteries where the superior performance characteristics of the silver oxide chemistry outweigh cost considerations.

What is the history of Silver-Oxide Battery?

These batteries were mainly developed for aircraft, and they have long been used in space launchers and crewed spacecraft where their short cycle life is not a drawback. Non-rechargeable silver-zinc batteries powered the Apollo Lunar Module (Apollo spacecraft), lunar rover (space exploration vehicle) and life support backpack (“backpack” of a spacesuit). The primary power sources for the command module (one of the spacecraft) were the hydrogen/oxygen fuel cells (electro-chemical cells) in the service module. They provided greater energy densities than any conventional battery. After the Apollo 13 (spacecraft) near-disaster, an auxiliary silver-zinc battery was added to the service module as a backup to the fuel cells.

What is chemistry of Silver-oxide battery?

A silver oxide battery is a small-sized primary battery using silver oxide as the positive electrode (cathode), zinc as the negative electrode (anode) plus an electrolyte (a solution that conducts electricity), usually sodium hydroxide (NaOH) or potassium hydroxide (KOH). Electrode is an electrical conductor. The silver is reduced (gains electrons) at the cathode from and the zinc is oxidized (loss of electrons) at the anode. The chemical reaction that takes place inside the battery is as shown below:

Zinc is the activator in the negative electrode and corrodes (gets rusted) in alkaline solution of KOH or NaOH. When this happens, it becomes difficult to maintain the capacity of the unused battery. The zinc corrosion causes electrolysis (Chemical decomposition produced by passing an electric current through a liquid or solution containing ions) in the electrolyte, resulting in the production of hydrogen gas, a rise of inner pressure and expansion of the You do not have access to view this node.

What are the characteristics of Silver-Oxide batteries?

• Open-circuit voltage: Open-circuit voltage is the difference of electrical potential between two terminals of a device when there is no external load connected, i.e. the circuit is broken or open. Compared to other batteries, a silver oxide battery has a higher open circuit potential. The open circuit voltage of the silver cell is 1.6 V. Typical median operating voltage is 1.5 to 1.2 V.
• Shelf Life: The charge retention of the silver cell is over 84% after two years of storage at 70 degree F. It has a life span that ranges from three to five years.
• Effect of Discharge Load and Temperature: The silver oxide system is capable of discharge at relatively heavy loads. The silver system is best suited for operation from -4 degree F to 130 degree F.
• Operating temperature: 32 degree F to 130 degree F with KOH electrolyte. NaOH electrolyte operates less well at low temperatures.
• Discharge curve: Silver Oxide cells exhibit a very flat operating voltage discharge curve that has a higher voltage than any other You do not have access to view this node.
• Internal resistance: Low internal resistance.

What are the applications of Silver-Oxide battery?

• The smaller button cell silver-oxide batteries can be used in items such as watches and calculators, hearing aids, pagers, photo electric exposure instruments which use only small amounts of silver. Their prices are therefore not as greatly affected, so they tend to be considered more affordable. Silver-oxide batteries of this size are very popular and widely used in a number of devices.
• The large cells found some applications in US military for power in submarines and torpedoes.
• These batteries are not considered environmentally friendly and can be hazardous to the environment, depending on the battery's condition. They should be discarded according to hazardous material standards.

Related Videos: