Nickel Hydrogen Battery

Nickel Hydrogen battery is a rechargeable battery which utilizes a hybrid technology with a mix of technology used in Nickel-cadmium cells and fuel cells.

The positive electrode of a Nickel Hydrogen battery is Nickel and electrolyte is Potassium Hydroxide just like in Nickel Cadmium cell, but the negative electrode of a nickle hydrogen cell is made up of gaseous hydrogen in high pressure of up to 1200 psi just like the fuel cell.

Nickel Hydrogen batteries were developed at the US telecommunication company COMCAST during 1970’s , and were deployed for use for the first time in 1977 on the US Navy’s Navigation technology satellite-2 (NTS-2). The Nickel Hydrogen battery is mainly used for aerospace devices and satellites. Hubble Telescope also uses Nickel Hydrogen Battery.

The terminal voltage of a Nickle Hydrogen battery is 1.55 V.
nickel hydrogen battery

Working Principle of Nickel Hydrogen Battery:

The chemical process taking place in a Nickel Hydrogen battery can be summarized by following equations:

At Positive Electrode:  equation at Positive Electrode of nickel hydrogen battery

At Negative Electrode:  equation at negative Electrode of nickel hydrogen battery

Overall Reaction:  overall reaction of nickel hydrogen battery

Advantages / Disadvantages of Nickel Hydrogen Batteries:

Nickel Hydrogen batteries have energy density of about 220 watt per kg ; which is not much but they have a very long life of about 20000 charge cycles. They are maintenance free and can be deep discharged.

Nickle hydrogen batteries have high self discharge rate. The discharge rate depends upon the pressure of hydrogen and the design but it can be as high as up to 20-30 % per day. They require highly pressurized hydrogen which might not be suitable for use in most cases and they are also very costly.