Due to the toxicity of cadmium in Ni-Cd batteries, the waste batteries are complicated to be treated and the environment is polluted. Therefore, it will be replaced by Ni-MH rechargeable batteries made of hydrogen storage alloys.

In terms of battery power, Ni-MH rechargeable batteries of the same size are about 1.5-2 times higher than Ni-Cd batteries, and are free of cadmium pollution. They have been widely used in mobile communications, notebook computers and other small portable electronic devices. Nickel-hydrogen batteries with larger capacity have been used in gasoline/electric hybrid vehicles. Nickel-hydrogen batteries can be used to charge and discharge gasoline rapidly. When a vehicle is running at high speed, the electricity generated by the generator can be stored in the nickel-hydrogen batteries on the vehicle. When the vehicle is running at low speed, it usually consumes more gasoline than at high speed. In order to save gasoline, nickel-hydrogen batteries can be used to drive the motor instead of the internal combustion engine, which not only ensures the normal operation of the car, but also saves a lot of gasoline. Therefore, hybrid vehicles have a greater market potential than traditional vehicles, and all countries in the world are accelerating research in this area.