The batteries used to power electric vehicles aren't your everyday Alkaline batteries. Most EVs are powered by lithium-ion batteries, which have long lifespans, can be recharged relatively quickly, and are high-density, offering a lot of energy in a small package. They also have a slow discharge rate, meaning they aren't losing a lot of energy when not in use. Perfect for use in electric cars, but also very difficult to dispose of without harm to the environment.
Rechargeable lithium-ion batteries are also used in cellphones, laptops, power tools and more, and can't simply be thrown away with the kitchen trash. Most EV batteries also contain cobalt, nickel, manganese, silicon and electrolytes. They're not only harmful to the environment, but they can spark fires if not disposed of properly at recycling centers. Then, the recycling process requires special facilities, is expensive, and a time-consuming process.
EV batteries have a life of about 10 to 20 years, so batteries from the first generation of EVs are reaching the end of the road. Rather than simply disposing of them, companies like General Motors are taking a different route; finding new life for these behemoth batteries as vessels for energy storage for wind and solar power. This storage allows wind and solar power to feed the grid at night or when the winds die down, and can power everything from homes to hospitals.