Why so many power batteries cannotwork once the winter came. In the low temperature environment, what happen inthe battery internal?
Look at LiFePO4 battery used inelectric bus, for example. This battery has high security performance, and itslife of single cell is slightly long. But its low temperature performance islower than other batteries. Lowe temperature has impact on the LiFePO4batteries’ anode and cathode, electrolyte, adhesives, etc. For example, the electronicconductivity of LiFePO4 battery positive is poor. It is easy to bring polarizationin the low temperature environment, and then, cut down the battery capacity. Influencedby low temperature, the speed of embed Li in graphite will be slow. It willeasy to separate lithium metal out in the surface of negative. After charged, Ifyou use the battery without enough laying aside time, the lithium metal cannotbe embed again into the graphite internal. Some lithium metal will leave on thesurface of negative continuously. In this situation, it is very likely to be lithiumdendrites, and has impact on battery security. In the low temperature environment,the electrolyte viscosity will increase, and then, the impedance of li-ion movewill also increase. In additional, in the manufacturing technique of LiFePO4, adhesivesis also a very important factor. Low temperature also has a big impact on the adhesivesperformance.
The other problem brought by lowtemperature is extending the charging time. Charging under the low temperature,battery is easy to separate Li out. So, before charging, in general, batteryshould be heated slowly, after battery temperature reach to normal temperature,it can be charged again.