Xiang HF, Wang H, Chen CH, Ge XW, Guo S, Sun JH, Hu WQ (2009) Thermal stability of LiPF(6)-based electrolyte and effect of contact with various delithiated cathodes of Li-ion batteries. Journal of Power Sources 191(2), 575-581. [In English]

Web link: http://dx.doi.org/10.1016/j.jpowsour.2009.02.045

Keywords:

Lithium-ion batteries, Thermal stability, Electrolyte, Cathode, Safety, libob ec/dec electrolytes, nonflammable electrolytes, nonaqueous, electrolyte, trimethyl phosphate, lithium batteries, cells, li(ni0.8co0.15al0.05)o-2, lifepo4, li(ni1/3co1/3mn1/3)o-2, performance

Abstract: Thermal stability of electrolyte (1 M LiPF(6)/EC + DMC) was studied by in-situ FTIR spectroscopy and C80 calorimetry, which indicated that the electrolyte underwent furious polymerization and decomposition reactions and sharp heat flow was generated below 225 degrees C The thermal stability of the electrolyte in contact with various delithiated cathodes (Li(x)CoO(2), Li(x)Ni(0.8)Co(0.15)Al(0.05)O(2), Li(x)Ni(1/3)Co(1/3)Mn(1/3)O(2), Li(x)Mn(2)O(4), Li(x)Ni(0.5)Mn(0.5)O(2), Li(x)Ni(0.5)Mn(1.5)O(4) and Li(x)FePO(4)) was also investigated by C80 calorimetry. The results show that the cathode materials except for Li(x)FePO(4) usually have in enhancement effect on the decomposition of the electrolyte, but Li(x)FePO(4) exhibits a suppression effect oil the reactions of the electrolyte. Li(x)FePO(4) is found to be with excellent thermal stability. Among the other cathodes, Li(x)CoO(2), Li(x)Ni(0.8)Co(0.15)Al(0.05)O(2), Li(x)Ni(0.5)Mn(0.5)O(2) and Li(x)Ni(0.5)Mn(1.5)O(4) promote the decomposition of electrolyte by releasing oxygen and thus considered not favorable for safety, but Li(x)Ni(1/3)Co(1/3)Mn(1/3)O(2) with a lesser reaction heat and Li(x)Mn(2)O(4) with even less heat flow in the low temperature range (50-225 degrees C) are believed as promising cathodes for better safety. By comparing X-ray diffraction (XRD) patterns of these cathode materials at room temperature and those heated to 300 degrees C in the presence of the electrolyte, we have found that Li(x)FePO(4) only has experienced tiny structure change, which is greatly different from the other cathode materials. (C) 2009 Elsevier B.V. All rights reserved.