Nickel-Cadmium Ni-Cd accumulator

This is one of the oldest technologies, as it was developed in 1900 by Waldemar Jungner. 

The Ni-Cd accumulator uses a cadmium negative electrode and a nickel-hydroxide (NiOOH) positive electrode, which is reduced into nickel hydroxide (Ni(OH)2) during the discharge of the battery. The electrolyte is an aqueous alkaline solution - potassium hydroxide (KOH) or caustic soda (sodium hydroxide, NaOH), and may or may not contain additional lithium hydroxide (LiOH, also known as lithine). 

The electrochemical reactions that occm at the electrodes (from left to right during discharge)  

Lifetime (number of cycles) 500-1000 if the depth of discharge is 100% at each cycle 5000-10000 ifit is 25% 

On the other hand, Ni-Cd accumulators cost around five times as much as Pb accumulators. They also have far poorer Faradaic efficiencies and a higher rate of discharge [FUS 09]. 

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