NiMH is an abbreviation for nickel-metal hydride, a type of battery technology used in laptop and notebook batteries, among other uses. NiMH batteries are considered more advanced than NiCad batteries, and have more capacity, but have since been mainly replaced by lithium-ion batteries and newer technologies. NiMH still remains the most popular choice for consumer electronics batteries, however.

NiMH laptop batteries use a hydrogen-absorbing alloy instead of the cadmium used by NiCad technologies. This helps reduce the cost and increase the capacity of the batteries.

NiMH laptop and notebook batteries have many advantages over previous technologies. They are well-suited to high current drain devices, such as power user laptops which require a lot of current. In many cases, consumer rechargeable NiMH batteries can produce more current than their alkaline equivalent. NiMH batteries also have a higher shelf life than many technologies, including lithium-ion.

They are also less expensive to produce, in general, than most lithium-ion laptop batteries. Unfortunately, there are some disadvantages to NiMH technology. NiMH have a lower energy density than lithium-ion and other more modern technologies, meaning it takes a larger battery to contain the same amount of energy. This is perhaps the biggest reason that lithium-ion batteries have mainly replaced NiMH for laptop and notebook batteries, because a compact size is so important for portable devices. This is also the case with digital cameras, mp3 players, cell phones, and many other portable electronics, as most of them have replaced NiMH with lithium-ion batteries as well.

Although they are not used for laptop batteries much anymore, NiMH batteries are still the most popular rechargeable batteries for alkaline replacements. Rechargeable NiMH batteries are available in the same sizes as alkaline batteries, such as A, AAA, and C, but can be much less expensive and less harmful to the environment, as they are designed to be recharged instead of thrown away.