磷酸铁锂动力电池的高低温性能解决途径.

1、UniversityApproaches to improve the electrochemicalperformance of LiFePO4-based lithium ionbatteries working in a wide temperature range磷酸铁锂动力电池的高低温性能解决途径Zi-Feng MaDepartment of Chemical EngineeringShanghai Jiao Tong University,Shanghai 200240, ChinaEmail: zfmaIntroduction前期工作基础:上海交通大学在LiFePO4正极材料制备

2、新工艺方面，获得6项中国发明专利（专利号:ZL 200410018476.4等）；2004年开始与浙江横店东磁股份有限公司合作开展产业 化技术开发，获得2006年浙江省产业化转化项目，2008年初完成中试线。Mechanical chemical reactionFe+2FePO4+U3PO4.0.5H2O -*3LiFePO4 + 0.5H2O Xiao-Zhen Liao. Zi-Fcng Ma*, Liang Wang, Xiao-Ming Zhang, Yi Jiang, Yu-Shi He, Electrochem. Solid-State Lett. 2004, 7(12)： A5

3、22-525 (SCI Cited 33) Xiao-Zhen Liao, Zi-Feng Maj Yu-Shi He, Xia<)-Min> Zhanj>9 Lian* Wang, Journal of the Electrochemical Society. 2005, 152(10):A1969-1972 (SCI cited 25)200X年全国优秀博士学位论文提名奖：2007年上海市优秀博士学位论文Unkveralty再分级处理现有生产能力：年产150吨磷酸铁锂正极材料 近期目标：合资建立磷酸铁锂动力电池生产线IntroductionIn winter, the e

4、lectric vehicle have to be started at low temperature and the battery need to keep better performanceIntroductionApproaches to enhance the performance of LiFePO4/C cathode at low temperatureCathode: particle size minimization or dopingElectrolyte:Solvent selection: affects liquid temperature range a

5、nd viscosity, and participating in the formation of a solid electrolyte interface (SEI), the resistance of which is main resistance in the full czll(两元.三元或四元) Lithium salt: LiPF6, LiBF4, LiBOB et alK. Amine9 J. Lili, I. Belharouak, Electrochein. Commiin. 7 (2005) 669.LiFePO4/C低温性能研究L()m(0.9LiBF4-()J

6、LiBOB) 1:1:3 PC/EC/EMC electrolyte/vgfso>-O- x«13Capacity / mAh g'1r20406080Capacity / mAh g'1Discharge curves of Li/LiFePO4 cell with a 1.0m(0.9UBF4-0.1UBOB) 1:1:3 PC/EC/EMC electrolyte, which were recorded at 1C by charging the cell at 20 «C and then discharging at a specific

7、temperatureEffect of salt ratio on the discharge voltage of Li/LiFePO4 cells, which was measured at 1C by charging the cell at 20 °C and then discharging at -30 “C.S.S.Zhang9 K.Xi“ T.R.Jow J Power Sources 159(2006) 702-707LiFePO4/C低温性能研究leOM LiPFe/EC+DMC+DEC+EMCv/v) electrolyte02040608010012014

8、0Capacity / mAh/gn、n .5 > / gsoAn.n s> O6el-OA020406080100120140160Capacity / mAh/gWe studied the low temperature performanee of LiFePO/C cathode in a quaternary carbonate-based electrolyte The discharge capacities of the LiFePO/C cathode were about 134.5 mAh/g (20°C), 114 mAh/g (0°C

9、), 90 mAh/g (-20"C) and 69 mAh/g (40°C) using a 1C charge-discharge rate.X.-Z. Liao et al. / Electrochemistry Communications 10 (2008) 691-694UniversityLiFePO4/C低温性能研究uimo/ze-tTOO 200300SOO »X只TempRQ)Rp(ft)R")D (cm%)20° C4.6786.968.2I.70X !0120* C5.93101.1124.3l.55XK)n-20

10、76; C7.88120.0315.12.05 XIO1340。C13.04126.32005.42.I2XIO*4Re Z / OhmThe improving of the reaction activity of the electrolyte-active material in terface by surface modification and electrolyte optimization, increasing the lithium diffusion abilityUniversityLiFePO4/C高温性能研究Three solutions to enhance t

11、he cycling performance of LiFePO4/C cathode working at high temperature It is based on similar reason that is to prevent Fe( II) ions dissolving. Electrolyte Anode CathodeJiao Tong UniversityElectrolyte Design1-2M LiPF6/ EC+PC+DMC (1:1:3) electrolyte0.7M LiBOB/ EC+PC+DMC (1:1:3) electrolyteFig. 9. A

12、mount of Fc'* ions dissolved from C-LiFcPO4 powder that lusbeenagedin I2M LiPFCPC DMC U:l:3)and 0.7 M LiBOB/ tC:PC DMC (1:1:3) for one week al 55 °CEaa wuo。丄0.0-1 1.204060Cyde Number80 100Eig. & Cycling pcrfbnuance of C-LiFePOyLuTisO:： cell al 55 °C usinu 1.2 M LiPF. ECfPC/DMC (I 1

13、:3) dectrolvtc.2 0 8 6 4 2 1.1.O Q a o 66 woBdB。poNaEJONK.Amine9 J.Liu, I.BeUiarouak, Electrochem. Commun. 7(2005)669-673Jiao Tong University1.0m(0.9LiBF4-(h 1 LiBOB) 1:1:3 PC/EC/EMC electrolytel6 ll<lu / Aloedeo500050Cycle NumberComparison of the cycling performance at high temperature for the L

14、i/LiFePO4 cells with different electrolytes, in which the cells were charged and discharged at 1C.S.S.Zhang, K.Xu, T.R.Jow, J Power Sources 159(2006) 702-707"JTTETTESriUnlverftityAnode coatingLiFePO4 particles were coated with TiO2 (molar ratio = 3%) via a sol-gel processCycle performance of Li

15、FePC)4/MCMB cells with different metal coatings, including Au, Cu, Fe, Co, Ni, and Ti on the MCMB electrode surface. All the cells were cycled at 1 C charge/discharge rate at 55 C in the voltage window of 2.54.0 V.Chang et al. / Journal of Power Sources 185 (2008) 466-472LiFe(PO4)1.xFx/C cathode6010

16、0200300Cycle number80z4020ga0111116ZVUJ - A_oeds18016014012010080606左圣-100200300400Cycle number/./. Chang, II.C. Wu9 N.L. Wu9 Electrochem Comtnun. 10(2008)1823-1826LiFe (PO4) 0.9F0./C材料的循环容量在200次循环后才开始衰减，但衰减程度明 显比其他三种材料小，到500次循环容量保持在121 mAh/go可见掺LiF对提高材 料高温循环稳定性很有好处。Xiao-Zhen Liao, Yu-Shi He9 Zi-Fen

17、g Ma, Liang Wang, Xiao-Ming Zhang J. Power Sources 174(2007)720”支唯心皈 LiFePO4/C cathode modification2.0020406080 100 120 140 160 180Capacity: mAh g£.0.53 3 22.020406080 100 120 140 160 180Capacity / mAh/g.5Q.53 3 2 WAA4>#OA【代对LiFePO4结构的影响f <R 3 刃4)刃掺入LiF量较少时，F元素以LiF形式固溶 :需曲到LiFePOq晶格结构中；而掺

18、LiF量较多 °的LiFe(P04)o.9F°.i/C材料，部分LiF生成Fe2(PO4)F, F以LiF和Fe2(PO4)F两种状 态固溶到LiFePO4晶格结构中。XPS研究表明，Fe(2P1/2, 2P3/2)峰位随掺F量增 大而向高键合能方向偏移.可见F确实已固溶到 LiFePO4晶格结构，对晶格中的Fe有彩响F1sBnmIm Enemy eV073070700PPy coating LiFePO4/C cathode5 0 5 03 3 2 2 n、+n 0 > a6e_o>包覆后的倍率性能从8C 提高到40C,放电平台髙Cycle performan

19、ce of PPy LiFePO4/C composite at different temperatures1.5020406080100120140160Capacity (mAh/g)20C 15C 8C5C 2C1CRate capabilities of LiFePO4/C and PPy- LiFePO4/C electrodes (active material : carbon black: PVDF=75:15:10)100200300400500Cycle numberPPy coating LiFePO4/C cathodeDischarge curves of LiFe

20、PO4/C and PPy-LiFePO4/Ccomposite cathode materials at 5C working in 55°C20406080100120140160Capacity (mAh/g)64208642083.3.3.3.222221.n4n .5 > &2-0>2020406080100120140160180Capacity (mAtVg)PPy 丄 iFePO/CLiFePO/CPPy coating LiFePO4/C cathode170 r160 k150140130120110100908070605040302010U

21、niversityH刨喷!l LiFcPO4/C-PPy LiFePO4/CCycling performance of the Li-LiFePO4/C cell at 5；C <?如恨clFch°rge rat# at §5匸 )100200300400500600Cycle numblesThe discharge curves of the cathodes at different cycles.Yang Kz/ig, Xiao-Zhen Liao, Zi-Feng Ma, Bao-Feng Wang, Yu-Shi He9 Li He Electroche

22、m. Comnuui. 11(2009)1277-1280UniversitySummarySeveral approaches can be used to enhance the cycling performance of LiFePO4/C cathode working in a wide temperature range. The new electrolytes design and preparation are mostly significant to improve the low temperature performance.Thus improving the reaction activity of the electrolyte-active material interface by surface modification and electrolyte optimization, increasing the lithium diffusion ability by modifying the crystal structure and minimizing the particle size are considered to be effective approaches to improve the low