Study On The Improvement Of Lithium-ion Battery Safety By Electrode Safety Additive And Modified Separator

Safety problem has been restricting the development of lithium-ion battery industry.To date, it has become one of the crucial problems in the high energy densitylithium-ion battery and large capacity power battery industrialization. For the safety oflithium-ion battery, the core of it is the internal thermal problem, while internal shortcircuit is the most inevitable problem and it’s also the most difficult problem to preventand improve. In view of the problems above, we established a physical model. Theprocess of internal short circuit is divided into two stages. The first stage is a closedsystem, at this stage, punch-through effect heat plays the leading role. The second stageis the open system，at this time, the heat mainly comes from physical heat productionand chemical decomposition reaction heat production.According to the established physical model，the paper systematically studied twomethods to improve the safety of lithium-ion battery. First of all，we add safety additiveto positive and negative electrode of NCM power battery. We make use of the highresistance insulation electrode of safety additives and endothermic heat transfer effect toreduce internal short circuit heat and slow release speed so that the battery temperaturerise is under control effectively. Nail test and impact test show that safety performanceis greatly improved. Secondly, we improve battery safety performance by adoptingAl2O3ceramic modified separator. The supporting of Al2O3ceramic framework canenhance the heat resistance of the separator, in the meanwhile, thermal resistance offunctional ceramics can counteract local hot spots timely, the results of thermal shocktest and short circuit test show that the use of Al2O3ceramic modified separator canimprove the safety of lithium-ion battery effectively.During the practical application, safety additive and Al2O3ceramic modifiedseparator can all improve safety performance of the batteries when for independent use,but internal thermal will be more controllable and safety performance will be improvedmore greatly if these two are combined. The optimal application results need to befurther researched systematically.