Nickel–metal hydride battery
A nickel–metal hydride battery is a type of rechargeable battery. The chemical reaction at the positive electrode is similar to that of the nickel-cadmium cell (NiCd), with both using nickel oxide hydroxide (NiOOH). However, the negative electrodes use a hydrogen-absorbing alloy instead of cadmium. NiMH batteries can have two to three times the capacity of NiCd batteries of the same size, with significantly higher energy density, although only about half that of lithium-ion batteries.
Modern Ni–MH rechargeable cells
Disassembled NiMH AA battery: Positive terminal Outer metal casing (also negative terminal) Positive electrode Negative electrode with current collector (metal grid, connected to metal casing) Separator (between electrodes)
NiMH cell that popped its cap due to failed safety valve
High-power Ni–MH battery of Toyota NHW20 Prius, Japan
A rechargeable battery, storage battery, or secondary cell, is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or primary battery, which is supplied fully charged and discarded after use. It is composed of one or more electrochemical cells. The term "accumulator" is used as it accumulates and stores energy through a reversible electrochemical reaction. Rechargeable batteries are produced in many different shapes and sizes, ranging from button cells to megawatt systems connected to stabilize an electrical distribution network. Several different combinations of electrode materials and electrolytes are used, including lead–acid, zinc–air, nickel–cadmium (NiCd), nickel–metal hydride (NiMH), lithium-ion (Li-ion), lithium iron phosphate (LiFePO4), and lithium-ion polymer.
A battery bank used for an uninterruptible power supply in a data center
A rechargeable lithium polymer mobile phone battery
A common consumer battery charger for rechargeable AA and AAA batteries
Cylindrical cell (18650) prior to assembly. Several thousand of them (lithium ion) form the Tesla Model S battery (see Gigafactory).