FIRE SAFETY PROBLEMS OF THE THERMAL ACCELERATION MODE IN LITHIUM STORAGE BATTERIES

На основе анализа результатов многочисленных зарубежных и национальных исследований установлены виды аварийных режимов, вызывающих загорания литиевых аккумуляторных батарей, а также даны рекомендации по их превентивной защите. Рассмотрено такое явление, как тепловой разгон литиевого аккумулятора. Отмечается, что условием возникновения теплового самовоспламенения, т. е. перехода медленной реакции окисления в горение (при определенных условиях - во взрыв) является нагрев смеси до температуры, при которой скорость тепловыделения за счет реакции окисления превышает скорость теплоотвода из зоны горения. Описаны виды испытаний, связанных с явлением теплового разгона литиевых аккумуляторов, и способы предотвращения таких пожаров.
 It is difficult to imagine modern life, including the production activities of industrial enterprises, without the use of lithium batteries. They are everywhere: electronics, consumer electronics, cordless tools, electric vehicles, various types of forklifts and electric cars, and much more. In the energy sector, these are energy storage devices (wind, solar) and, of course, uninterruptible power supply devices, taking into account especially important consumers of the first category in terms of power supply reliability, including fire protection systems. But there is a very significant problem, which, to a certain extent, holds back the area expansion of lithium batteries application: the constant increase in the number of fires and even explosions. Data are given on the occurrence of numerous cases of their ignition in the United States, as well as cases of such fires in recent years in transport in the Russian Federation. Based on the analysis of foreign and domestic publications, there are considered the classification and operating principles of lithium batteries. Analytical issues of the phenomenon of thermal acceleration in lithium batteries are discussed. A diagram of the battery pack design with various options for battery modules and cell configurations is provided. A separate section of the article is devoted to experimental studies related to the testing of lithium batteries for fire hazard, in accordance with the requirements of national standards. Test methods for overcharging, mechanical damage, thermal and other types of tests are briefly outlined. In the final part of the article there are given ways to prevent fires. The first category contains preventive measures, at which flame retardants are added to polymeric materials for thermal stability of the battery. The second category includes design measures that increase the fault tolerance of lithium batteries and reduce damage when thermal acceleration occurs. There is an installation of shut-off separators, safety valves that respond to excess pressure or temperature, ventilation of the cell, etc.