Hou Junxian, Lu Languang, Wang Li, Ohma Atsushi, Ren Dongsheng, Feng Xuning, Li Yan, Li Yalun, Ootani Issei, Han Xuebing, Ren Weining, He Xiangming, Nitta Yoshiaki, Ouyang Minggao
State Key Laboratory of Automotive Safety and Energy, Tsinghua University, 100084, Beijing, China.
Institute of Nuclear and New Energy Technology, Tsinghua University, 100084, Beijing, China.
Nat Commun. 2020 Oct 9;11(1):5100. doi: 10.1038/s41467-020-18868-w.
Concentrated electrolytes usually demonstrate good electrochemical performance and thermal stability, and are also supposed to be promising when it comes to improving the safety of lithium-ion batteries due to their low flammability. Here, we show that LiN(SOF)-based concentrated electrolytes are incapable of solving the safety issues of lithium-ion batteries. To illustrate, a mechanism based on battery material and characterizations reveals that the tremendous heat in lithium-ion batteries is released due to the reaction between the lithiated graphite and LiN(SOF) triggered thermal runaway of batteries, even if the concentrated electrolyte is non-flammable or low-flammable. Generally, the flammability of an electrolyte represents its behaviors when oxidized by oxygen, while it is the electrolyte reduction that triggers the chain of exothermic reactions in a battery. Thus, this study lights the way to a deeper understanding of the thermal runaway mechanism in batteries as well as the design philosophy of electrolytes for safer lithium-ion batteries.
浓电解质通常表现出良好的电化学性能和热稳定性，并且由于其低可燃性，在提高锂离子电池安全性方面也被认为很有前景。在此，我们表明基于LiN(SOF)的浓电解质无法解决锂离子电池的安全问题。具体而言，基于电池材料和表征的一种机制表明，即使浓电解质不可燃或低易燃，锂离子电池中巨大的热量也是由于锂化石墨与LiN(SOF)之间的反应引发电池热失控而释放的。一般来说，电解质的可燃性代表其被氧气氧化时的行为，而引发电池中放热反应链的是电解质还原。因此，这项研究为更深入理解电池热失控机制以及设计更安全锂离子电池的电解质设计理念指明了方向。
