Battery Types and Chemistries

What is a Lithium Ion Battery (Li-Ion)?

Lithium Ion batteries use Lithium Oxide and a Carbon compound, usually Graphite as the electrodes. These are separated by a microporous film containing an organic solvent as the electrolyte. Compared to NiCd and NiMH batteries, Li-Ion batteries provide the same capacity inspite of being smaller and lighter. Li-Ion batteries have a higher power to weight ratio. These batteries do not suffer from the dreaded “memory effect”, that affects NiCd batteries. Li-Ion also has a much lower levels of self-discharging. These tend to be comparatively more expensive due to higher production costs. The Department of Chemistry at Oregon State University has an informative and technical page on battery chemistries and how these work.

What is a Nickel Metal Hydride Battery (NiMH)?

This battery uses Nickel and other rare earth metals as its electrodes and Potassium Hydroxide as the electrolyte. These are constructed from non-toxic metals making it environmentally friendly. These batteries do not suffer from the memory effect and has a higher capacity than NiCd batteries. However, the NiMH battery has a much shorter life span than NiCd and Li-Ion batteries.

What is a Nickel Cadmium / Ni-Cad Battery (NiCd)?

This battery uses Nickel and Cadmium as its electrodes and aqueous Potassium Hydroxide as the electrolyte. It is an older type of battery, but is quick to charge and can handle higher loads. These batteries suffer from the “memory effect”. Also due to the presence of heavy metals, they are environmentally unsafe and hazardous.

What is a Lithium-Ion Polymer Battery?

This has similar characteristics to Lithium Ion but uses a plastic like film, a polymer as the electrolyte. The dry polymer design allows the fabrication of this type of battery to be cheaper and smaller.

What is a battery cell?

The cells produce the electricity, a specific amount. A laptop battery comprises of a number of these cells connected together to produce the correct amount of electricity. The most reliable cells are manufactured in Japan, Korea and Hong Kong.