Question

What is in a Nickel Metal Hydride Battery?

Answer 1

Hint: If several cells are connected in series, the structure is called a battery. A Nickel Metal Hydride battery is an example of secondary battery.
Secondary batteries can be recharged by passing an electric current through them and thus can be utilised continually.

Complete Step by Step Solution:
A nickel-metal hydride battery (NiMH) is a kind of rechargeable battery.
It is identical to a Ni-Cd battery.

The anode comprises Hydrogen in the form of interstitial metal hydride. Here M is the intermetallic compound.
The cathode consists of Nickel hydroxide
(\[Ni{(OH)_2}\]).

An alkaline solution like Potassium hydroxide is used as an electrolyte.

It can be recharged by passing a current in the opposite direction. Forward reactions happen during the charging of the battery. Reverse reactions happen during the recharging of the battery.

At anode:\[Ni{(OH)_2} + O{H^ - } \to NiO(OH) + {H_2}O + {e^ - }\]
At cathode: \[{H_2}O + M + {e^ - } \to O{H^ - } + MH\]


These batteries provide a high current while retaining voltage around them. Thus, it has
low internal resistance. Due to this, they provide constant voltage until they are discharged.

So, NiMH batteries can have extra capacity than Ni-Cd batteries of a similar size, with considerably increased energy .

Additional Information: NiMH batteries maintain an increased voltage than Ni-Cd batteries but can get self-discharged handily and have a shorter shelf life. These are used as an alternative to Ni-Cd batteries in cell phones, camcorders, computers, and laptops, among others.

Note: NiMH batteries, due to their high voltage and resistance to leaking, are used as an alternative for non-rechargeable alkaline batteries like Lithium-ion batteries. Lithium-ion batteries have increased energy than nickel-metal hydride batteries but they are considerably costly which is a drawback.