With the continuous improvement of the performance, energy conservation and environmental protection requirements of electric vehicles, lithium-ion batteries have gradually replaced lead and acid batteries. However, batteries are not always usable, even high-performance lithium-ion batteries are no exception. After using for a certain period of time, power performance and endurance cannot meet the demand, and only replacement and scrapping can be selected.

Some failures often occur in the use or storage of commercial lithium-ion batteries, including capacity attenuation, internal resistance increase, magnification performance reduction, gas production, liquid leakage, short circuit, deformation, thermal runaway, lithium precipitation, etc., which seriously reduce the use performance, reliability and safety of lithium-ion batteries. The correct analysis and understanding of these failures are of great significance for the improvement of the performance and maintenance technology of lithium ion batteries.

The lithium ion battery is most afraid of overcharge and overdischarge, so the battery pack and external multiple circuit should pass a protection circuit to limit the upper and lower working voltage of the battery. The serial and parallel connection of multiple batteries requires high battery consistency, that is, the capacity, internal resistance and discharge platform of a single 18650 battery must be the same.

From the perspective of science and technology application, the development of new energy vehicles depends more on high-tech, which is also one of the important characteristics of new energy vehicles. Specifically, new energy vehicles should not only use unconventional energy as power fuel, but also lead the development of high-tech in the field of safety performance, which is the development direction of the new energy era in the future automobile industry.