Nickel-Metal Hydride, commonly known as the NiMH battery, was introduced as an improved alternative to the older Nickel-Cadmium (Ni-Cd) battery. It became popular during the 1990s because it offered better performance while avoiding the use of toxic cadmium.
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Even today, NiMH batteries are widely used in many household electronic devices, especially in the familiar AA and AAA rechargeable battery sizes.
Advantages of NiMH batteries
One of the biggest advantages of NiMH batteries is their higher energy density compared to Ni-Cd batteries. This means they can store more energy while occupying roughly the same amount of space.
A typical NiMH battery has an energy density of around 60–120 Wh/kg, whereas a Ni-Cd battery generally stores less energy for the same weight.
NiMH batteries are also more environmentally friendly because they do not contain cadmium, which is a toxic heavy metal.
Applications
NiMH batteries are commonly used in devices that require moderate to high current for extended periods.
Some common applications include:
- Digital cameras
- Rechargeable AA and AAA batteries
- Wireless keyboards and mice
- Toys
- Cordless telephones
Their relatively low internal resistance allows them to deliver higher currents than many disposable batteries, making them suitable for devices with higher power requirements.
NiMH vs Ni-Cd
Compared to Ni-Cd batteries, NiMH batteries offer several advantages:
- Higher energy density
- Greater capacity for the same size
- More environmentally friendly
- Much less affected by memory effect
Because of these advantages, NiMH batteries gradually replaced Ni-Cd batteries in many consumer electronics.
Summary
Nickel-Metal Hydride batteries are an improved version of the older Ni-Cd technology. They can store more energy, are safer for the environment, and are widely available in rechargeable AA and AAA sizes. Although lithium-ion batteries have become the preferred choice for smartphones and laptops, NiMH batteries continue to be a reliable and economical option for many everyday household devices.