Nickel-metal hydride batteries are used in portable electronic devices such as cellphones and portable computers. Lithium-ion batteries have the same applications as nickel-metal hydride batteries; they are used in high-end electronic devices.
According to GreenBatteries.com, lithium-ion batteries operate at higher voltages than nickel-metal hydride batteries. Lithium-ion batteries operate at around 3.7 volts versus 1.2 volts for nickel-metal hydride batteries.
Another advantage that lithium-ion batteries have over nickel-metal hydride batteries is that they have a lower discharge rate. This means that lithium-ion batteries hold a charge for longer than nickel-metal hydride batteries.
Nickel-metal hydride batteries can lose between 1 and 5 percent of their charge per day while in storage. Lithium-ion batteries can retain nearly 100 percent of their charge while in storage.
According to TopBits.com, lithium-ion batteries typically last anywhere between 3 and 5 years. Nickel-metal hydride batteries are typically rated to last for around 3 years. Storage of nickel-metal hydride batteries at higher temperatures reduces their service life while storage at lower temperatures slows aging.