Nickel-Caadmium Batteries Advantages And Disadvantages

765 Words 4 Pages
NiCd is the chemical abbreviation for the composition of Nickel-Cadmium batteries, which are a type of secondary (rechargeable) batteries. Nickel-Cadmium batteries contain the chemicals Nickel (Ni) and Cadmium (Cd), in various forms and compositions.
The nickel-cadmium battery, invented by Waldmar Jungner in 1899, offered several advantages over the then only rechargeable battery, lead acid, but the materials were expensive and the early use was restricted. Developments lagged until 1932 when attempts were made to deposit the active materials inside a porous nickel-plated electrode. Further improvements occurred in 1947 by absorbing the gases generated during charge. This led to the modern sealed NiCd battery in use today.

For many years,
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o It is a portable, rechargeable cell o It can be packed in a sealed container o It can be left for long periods of time without any appreciable deterioration as there is no gas produced during discharging or charging. o Energy density about double that of lead acid batteries. o There small size & high rate discharge capacity made portable tools & other consumer application practical for the first time. o The cells are sealed and utilise a recombinant system to prevent electrolyte loss and extend the useful life. o Undergo 100s of discharge – recharge cycles. o However due to toxicity of Cd its usage is discouraged.

• Advantages o It has Low internal resistance o Fast and simple charge even after prolonged storage. o High rate charge and discharge rates possible o Good load performance the NiCd allows recharging at low temperatures. o Flat discharge characteristic (but falls off rapidly at the end of the cycle) o Tolerates deep discharges - can be deep
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o The coulombic efficiency of nickel cadmium is over 80% for a fast charge but can drop to below 50% for slow charging. o The sealed nickel-cadmium cell can be stored in the charged or discharged state without damage. It can be restored for service by recharging several charge/discharge cycles. o The electrolyte is commonly availalable, low cost potassium hydroxide KOH. o Available in a large variety of sizes & capacities.

• Limitations

o Relatively low energy density — compared with newer systems. o Memory effect — the NiCd must periodically be exercised to prevent memory. o Environmentally unfriendly — the NiCd contains toxic metals. Some countries are limiting the use of the NiCd battery. o Has relatively high self-discharge — needs recharging after storage.

Nicad cells are used in calculators, electrical shavers, wireless telephones, emergency lighting, and other applications.
With a relatively low resistance, they can supply high current. This makes them a favourable choice for remote-controlled electric model airplanes, boats, and cars, as well as cordless power tools and camera flash

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