040The Design and Preservation of the Safety of Lithium-ion BatteryLiFePO4 LiCoO2PTCLiFePO4Separator has much influence on the electrical properties and safety of the Cell. Microporous poly-meric membranes must be mechanically strong enough to keep the structure integrity while shutdown activated. Inorganic composite membranes show a higher ability than Microporous polymeric mem-branes to withstand overcharge. Two types of overcharge protector are introduced and each of thesehas a specific redox potential range that suitable for LiFePO4 and LiCoO2 respectively. Phosphor contented fire-retardant additive prevents the cell from overheating. A carbon and polymer compositewith PTC properties is introduced into the cathode preparation. When the cell is heated over themelting point of the polymer, the resistance of the cathode electrode increases drastically and cut-offthe current through it. That prevents the cell from thermal runaway. LiFePO4 has the character of overcharge protector too./Key Words(Thermal Runaway) (Separator) (Overcharge Protector)(Fire-retardant Additive) (PTC Cathode)J. J. Lee1 C. R. Yang2(MCL/ITRI) 1 260 701989 Li/MoS2(1)1990~1991 NagouraSONY Moli0411993 Bellcore 1991PTC (Positive Temperature Coefficient) CID (Current Interrupt Device) (Safety Vent) (Thermal Fuse) (Thermostat)(2)(Thermal Runaway)*PC/EC/DMC(1/1/3) + LiPF 6 (1M)DSC042(Tortuosity)(MD) (TD) (TensileStrength) (Puncture Strength)(Nonwoven Fiber Mats)(Microporous Polymeric Membranes)(Inorganic Composite Membranes)1.60~80% 20~50µm 100~200 µm(3)(4)2.PE PP PE/PPHDPE20 µm40% 1000 kg/cm230090°C 15%(Shutdown)PEPP/PE/PP043HDPE 135°C PE PP PP/PE PE 120~130°C PP3.Sol-Gel (EC, PC, γ-GBL)(5)Ceramic CoatingSupport5 µm100 µm044 SEI1.(Anisole)3.8~4.0 V vs. Li+/Li (6)LiFePO4 −3,5−(Trimethyl-3,5-xylylsilane)4.7 V LiCoO2(7)(Biphenyl)(Aryladamantanes)4.6 V LiCoO2(8) LiBOB(9)LiPF6LiBOB2.Trimethyl Phosphate 1M LiPF61.2 V TMPTMPEC 12%DME 70% (10)Tris(2,2,2-trifluoroethyl) Phosphate0.3V(11) Cyclophosphazene(12)P(III) Tris(2,2,2-trifluoroethyl)Phosphite(13)PTCPTCHDPE045PTC (14)PTC 130°C 100 PTC 130~140°C 3C / PTC PTCPTC(15)70°C 50 Ω 110°C 6980 Ω PTC 80°C 130°CLiFePO 4 4.3 V (16) LiCoO 2/LiFePO 4 LiCoO 2 LiFePO 4 LiCoO 2/LiFePO 4 LiFePO 4/LiCoO 2/AlCurrent CollectorActive Material LayerPTC CompoundBinderActive MaterialPTC(a)(b)(c)PTC (a) LiCoO 2 (b) PTC(c) AlLiCoO 2 LiMn 2O 4 LiFePO 4 25°CLiCoO 2 LiMn 2O 4 LiFePO 4046 LiCoO2/LiFePO4/Al80°C 12 VLiCoO2/LiFePO4/Al/1.J.-I. Yamaki, S.-I. Tobishima, Y. Sakurai, K.-I. Saito, K. Hayashi,J. of Applied Electrochemistry 28 (1998) 135-1402.Ph. Biensan, B. Simon, J.P. Pérès, A. de Guibrt, M. Broussely, J.M. Bodet, F. Perton, J. Power Sources 81-82 (1999) 906-9123.Y.M. Lee, J.W. Kim, N.S. Cho, J.A. Lee, W.H. Seol, J.K. Park, J.Power Source 139 (2005) 2354.P. Kritzer, J. Power Source 161 (2006) 13355.E.P. Roth, D.H. Doughty, D.L. Pile, J. Power Source 174 (2007)5796.M. Adachi, K. Tanaka, K. Sekai, J. Electrochem. Soc. 146 (1999)12567.Y. Watanabe, Y. Yamazaki, K. Yasuda, H. Morimoto, S.I.Tobishima, J. Power Source 160 (2006) 13758.Y. Watanabe, H. Morimoto, S.I. Tobishima, J. Power Source 154(2006) 2469.S.S. Zhang, Electrochem. Commun. 8 (2006) 142310.X. Wang, E. Yasukawa, S. Kasuya, J. Electrochem. Soc. 148(2001) A105811.K. Xu, S.S. Zhang, J.L. Allen, T.R. Jow, J. Electrochem. Soc. 150(2003) A17012.K. Xu, M.S. Ding, S.S. Zhang, J.L. Allen, T.R. Jow, J. Electrochem.Soc. 149 (2002) A62213.T.R. Jow, S.S. Zhang, K. Xu, M.S. Ding, U.S. Patent 6,939,647(2005)14.M. Kise, S. Yoshioka, K. Hamano, D. Takemura, T. Nishimura,H. Urushibata, H. Yoshiyasu, J. Power Source 146 (2005) 77515.X.M. Feng, X.P. Ai, H.X. Yang, Electrochem. Commun. 6 (2004)102116.N. Imachi, Y. Takano, H. Fujimoto, Y. Kida, S. Fujitani, J.Electrochem. Soc. 154 (2007) A412LiCoO2/LiFePO4/Al 3C。