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Polymer Electrolyte

Polymer Electrolyte. 공업화학과 / 정보통신소재연구실 / 석사 2 기 이 인 재 2000.11.27. Lithium secondary battery Historical background Electrochemical process Cell configuration Classifications Requirements Ionic Conductivity. Polymer electrolyte Requirements Advantage Ion conduction mechanism

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Polymer Electrolyte

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  1. Polymer Electrolyte 공업화학과/정보통신소재연구실/석사2기 이 인 재 2000.11.27 • Lithium secondary battery • Historical background • Electrochemical process • Cell configuration • Classifications • Requirements • Ionic Conductivity • Polymer electrolyte • Requirements • Advantage • Ion conduction mechanism • Solid Polymer electrolyte • Gel Polymer electrolyte

  2. Cathode LiMO2 Li1-xMO2+xLi+xe Anode C6+xLi+xe LixC Overall LiMO2+C6 LixO6+Li1-xMO2 Charge Discharge Charge Discharge Charge Discharge Linden, Handbook of batteries, 1994 Jang Myoun Ko, Polymer Science ang Technology, 1998, 9, 203 Yang Kook Sun, Prospectives of Industrial chemistry, 2000, 3, 11 Lithium secondary battery Electrochemical Process of Lithium secondary battery 1789 개구리다리로부터 전지현상발견 (Galbani(Italy)) 1799 구리-아연 전지 발명 (Cu/H2SO4/Zn,Volta(Italy)) 1860 연축전지 발명(PbO2/H2SO4/Pb,Plante'(France)) 1867 망간 건전지의 원형 발명(MnO2/NH4Cl.ZnCl2/Zn,Lechlanche(France)) 1899 니켈-카드뮴 전지 발명 (NiOOH/KOH/Cd,Jungner(Sweden)) 1899 니켈-아연 전지 발명 (NiOOH/KOH/Zn) 1900 니켈-철 전지 발명 (NiOOH/KOH/Fe,Edison(USA)) 1909 알카리 망간전지 발명(MnO2/KOH/Zn) 1917 공기 아연전지 발명(O2 in Air/KOH/Zn) 1942 수은전지 발명(HgO/KOH/Zn) 1970 리튬 1차전지실용화 1970 미국 GM Delco 칼슘 MF 연축전지 개발 1973 이산화망간-리튬 1차전지 실용화(MnO2/LiClO4/Li) 1981 리튬 이온2차전지발명 1990 리튬 이온2차전지실용화,생산개시(일본 SONY사) 1990 밀폐형 닉켈-수소전지실용화(NiOOH/KOH/MH) 1990 미국 켈리포니아주 대기정화법(Clean Air Act)통과 세계각국 전기자동차용 전지 본격적인 개발 1995 수은전지 생산중지 Historical Background

  3. Cathode Cell Configuration • Anode • Electrolyte • Solid polymer electrolyte + Lithium salt • Gel polymer electrolyte + Lithium Salt + Solvent Lithium salt ; LiClO4, Li(CF3SO2)2N, LiCF3SO3, LiAsF6, LiPF6, LiBF6 Solvent ; PC, EC, DMC, EMC, DEC, -BL, etc

  4. 이론 용량과 실제 용량 • Faraday’s Low of Electrolysis • ; 1g당량의 원자 또는 원자단이 석출하는데 필요한 전기량은 물질에 관계없이 항상 일정한 • 96487C을 갖는다. • Ex)Li1-xMO2(M=Co, Ni, Mn, …) • LiCoO2(MW=97.87) • 1F=96487C=96487A•s  1h/3600s  1000mA/A = 26800mAh • ∴ 26800mAh/97.87g = 273mAh/g ⇒ LiCoO2의 이론용량 • 실제용량은 x=0.5이하이므로 137mAh/g • Li1-xMn2O4(MW=180.8) • 똑같은 계산으로 26800mAh/180.8g = 148mAh/g • Spinel structure의 Li1-xMn2O4는 x=1이므로 실제용량이 이론용량값과 거의 일치

  5. Classifications of Requirements of Lithium secondary battery Lithium secondary battery • Energy density(Wh/g or Wh/l) Wh=Ah(용량)  V(전압) • Cycle life (100% DOD 기준) • Rate performance (C-Rate) • 작동온도구간 방전;-20~+60℃, 충전;0~40℃ • 보존 특성 (충전보존, 가역성보존) • 자기 방전 • 안전성 • Memory effect • 형상 자유성 • Cost • 환경문제

  6. Ionic Conductivity Richard G. Compton, Giles H.W. Sanders, Electrode Potentials, 1996 Peter G. Bruce, in “Polymer Electrolyte Reviews”, ed. By J.R.MacCallum, 1987, 237 • Measurements of conductivity • Direct current measurement(D.C.) simple, straightforward method conductivity value를 바로 얻음 • Alternating current measurement(A.C.) • Vmax/Imax:the ratio of the voltage and current • maxima •  : the phase difference between the voltage • and current • Impedance Z=f(Vmax/Imax,,) • Z*=Z’-jZ” Resistor : =0, Z=R • Capacitor :  =-2/, Z=1/C • Basic concept •  = 1/ = l/RA Where, =conductivity(-1m-1),=resistivity, R=resistance Conductivity is a property of the chemical nature and composition of the electrolyte solution Ohm’s low V=IR ∴ =(I/A)/(V/l) (I/A=current density, V/l=voltage gradient) • Basic electrical properties of a polymer electrolyte 1)the total conductivity of the electrolyte as a function of Temp. 2)identification of the different charged species contributing to conduction 3)transport numbers, i.e. the proportion of the current carried by each charged species, as a function of Temp.

  7. Requirements of Polymer electrolyte Polymer electrolyte Fiona M. Gray, Polymer Electrolyte, 1997 Peter V. Wright, Br. Polym. J., 1975, 7, 319 Jung Ki Park, Polymer Science and Technology, 1998, 9, 125 한원길역, 폴리머 전지, 2000 Ion Conduction Mechanism • High ion conductivity (≥10-3S/cm @ R.T) • Good compatibility between polymer matrix and liquid electrolyte • Thermal and electrochemical stability • Good mechanical stability • High cation transference number • Availability • Solid polymer electrolyte Low barriers to rotation for atoms in the main chain so as to ensure high flexibility and hence facilitate segmental motion Advantage of Polymer electrolyte • Gel polymer electrolyte • Design flexibility • High energy density • Thin film • No leakage of liquid electrolyte • Low cost Lithium cation dissociated by organic solvent Transported through the free volume or micropore polymer matrix and liquid electrolyte

  8. Solid polymer electrolyte • PEO <10-8S/cm Tg=-64℃ • PPO <10-8S/cm -60℃ • Polyester • Polyamine • Polysulfide 10-5~10-8S/cm @60℃ Second Generation • High molecular weigh amorphous or reduced crystallinity polyether-based host architectures • Random copolymer • Comb-branched copolymer • Network • Gel electrolytes:systems containing low molecular weight solvent • Random polyether POO3  10-8S/cm -66℃

  9. Siloxane-based 10-4S/cm 10-4~10-5S/cm • Comb-branched copolymer PMG 1 10-8S/cm -50℃(amorphous) P(EO/MEEGE) P(EO/MEEGE)-5 (95:5) -61℃ P(EO/MEEGE)-9 (91:9) -65℃ (M. Watanabe, A. Nishimoto, Electrochimica Acta, 1998, 43, 1177) MEEP 10-5S/cm -83℃(amorphous)

  10. P(EO/MEEGE)73/27 Poly((amino)[(2-methoxyethoxy)ethoxy])phosphazenes Tg=-65~-50℃ Improve dimensional stability 1.4  10-3 @ 60℃ 3.3  10-4 @ 40℃ (Nishimoto et al, J. Power Sources, 1999, 81-82, 786) (Y.W.chen-Yang et al, macromolecules, 2000, 33, 1237)

  11. Networks Poly(propylene oxide) PEO based(via thermal with crosslinker) (Nishimoto et al, Solid State Ionics, 1995, 79, 306) Ion conductivity of polymer 4 and polymer 5 (M. Watanabe, N. Ogata, in “Polymer Electrolyte Reviews”, 1987, 39)

  12. PEO based(via photo) P(EO/MEEGE)470 -68.0℃ P(EO/MEEGE)500 –68.9℃ P(EO/MEEGE)710 –68.6℃ P(EO/MEEGE)850 –71.3℃ P(EO/MEEGE)990 –68.7℃ P(EO/MEEGE)1500 –67.4℃ P(EO/MEEGE)2000 –66.7℃ (Nishimoto et al, Macromolecules, 1999, 32, 1541)

  13. Gel Polymer electrolyte PAN/MEEP based PVC based (M. Watanabe, A. Nishimoto, Solid State Ionics, 1996, 86-88, 385) (L.M.Abraham, M.Alamgir, J.Electrochem.Soc., 1990, 137, 1657)

  14. PVdF based Acrylate based (J. Y. Song et al, J. Electrochem. Soc., 2000, 147, 3219) S. I. Moon et al, J. Power Sources, 2000, 87, 213

  15. Poly(p-phenylene) based (Wolfgang H.Meyer, Adv. Mater., 1998, 10, 439 P.Baum, W. H. Meyer, G. Wegner, Polymer, 2000, 41, 965)

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