As electric cars become more common, attention is turning to what happens to their batteries at the end of their lives. A typical car battery is designed to last for many years, but its capacity gradually falls. When it can no longer provide enough range for driving, it usually still holds a considerable amount of energy. One option is to give these batteries a "second life". Used car batteries can be combined and installed in buildings, where they store electricity generated by solar panels during the day for use in the evening. Because such storage systems do not need to be light or compact, batteries that are no longer suitable for vehicles can still be useful. Eventually, however, every battery must be recycled. Recovering valuable metals such as lithium, nickel and cobalt is technically possible, but current processes can be expensive and energy-intensive. Engineers are trying to design batteries that are easier to take apart, since at present many are assembled with strong glues that make separation difficult. Several governments are also considering rules that would require manufacturers to take responsibility for collecting old batteries.

Battery storage systems in buildings do not need to be as light or compact as batteries in vehicles.