“Lithium-ion” vs. Nickel Metal Hydride (“NiMH”) Batteries

"Lithium Ion" (rechargeable) batteries used pretty exclusively with iPads, iPods, tablets, mobile/cell phones, digital cameras, laptops nowadays.

The most obvious difference (is cost!! - Bob).

The less obvious diff. between Li-ion and NiMH batteries is the material used to store power.

Lithium-ion batteries are made of carbon and highly reactive lithium, which can store a lot of energy.

Nickel metal hydride batteries use hydrogen to store energy, with nickel and another ‘metal’ i.e. the ‘M’ designation in the ‘NiMH’ name, means the ‘other’ metal, such as titanium metal - used to keeping a ‘lid on’ the hydrogen ions.

With these different structures there are, of course, several practical differences, too:

Cost: ‘Nickel metal hydride’ batteries are, right now, the less-expensive technology.

As production of ‘lithium-ion’ cells ramps up, though, economies of scale come into play and the cost of Li-ion cells should drop.

Toxicity – “Li ion” (and NiMH) batteries don't contain toxic materials such as Cadmium and/or Mercury.

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NiCad(mium)* vs. NiMH rechargeable batteries:

* Nickle/Cadmium batteries are not that commonly used/sold anymore.

The main difference between the two is that NiMH battery (the newer technology of the two) offers higher energy density than NiCads.

In other words, the capacity of a NiMH is approximately twice the capacity of its NiCad counterpart.

NiCad batteries tend to suffer from what is called the "memory effect" – loss of full power, with repeated recharging of partly-discharged batteries.

So, avoid NiCd rechargeable batteries, (and Hg/Cd** button-type ones), where-ever possible!

** Mercury/Cadmium

Bob
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