Safety Design of Lithium Battery

In order to avoid overdischarge or overcharge of batteries due to improper use, a triple protection mechanism is installed in a single lithium-ion battery. Firstly, when the temperature in the battery rises, its resistance will rise, and when the temperature is too high, the power supply will automatically stop; secondly, when the temperature rises to a certain value, the micro-holes in the separator will dissolve automatically, so that the lithium ion can not pass through and the internal reaction of the battery will stop; thirdly, the safety valve (that is, the battery) will be set up. When the pressure inside the battery rises to a certain value, the safety valve opens automatically to ensure the safety of the battery. Sometimes, although the battery itself has safety control measures, but for some reasons, control failure, lack of safety valve or gas to release through the safety valve, the battery internal pressure will rise sharply and cause explosion. Generally, the total energy stored in lithium-ion batteries is inversely proportional to their safety. With the increase of battery capacity, the volume of batteries is also increasing, and their heat dissipation performance becomes worse. The possibility of accidents will be greatly increased. For mobile phone lithium-ion batteries, the basic requirement is that the probability of safety accidents is less than one in a million, which is also the lowest acceptable standard for the public. For large capacity lithium-ion batteries, especially for automobiles and other large capacity lithium-ion batteries, the use of forced heat dissipation is particularly important. Choosing safer electrode material and lithium manganate material ensures that the lithium ion of the positive electrode has been completely embedded in the carbon pore of the negative electrode in the full charge state in terms of molecular structure, which fundamentally avoids dendrite formation. At the same time, the stable structure of lithium manganate makes its oxidation performance far lower than that of lithium cobalt oxide. The decomposition temperature exceeds 100 C of lithium cobalt oxide. Even if the internal short circuit (needling), external short circuit and overcharge occur due to external force, the danger of combustion and explosion caused by the precipitation of lithium metal can be completely avoided.