Fagadar-Cosma Eugenia

Fagadar-Cosma Gheorghe

Ilia Gheorghe

Iliescu Smaranda

Macarie Lavinia

Plesu Nicoleta

Popa Adriana

English

University of Szeged

ELECTROCHEMICAL ANALYSIS OF SOLID POLYMER ELECTROLYTE MEMBRANES USED IN LITHIUM-BASED BATTERIES.A literature survey.Gheorghe Fagadar-Cosma1*, Nicoleta Plesu2, Eugenia Fagadar-Cosma2, Gheorghe Ilia2, Smaranda Iliescu2, Lavinia Macarie2, Adriana Popa2’"Politehnica" University of Timisoara, Faculty of Industrial Chemistry and Environmental Engineering, Pta Victoriei 2, 300006-Timisoara, Romania, e-mail: gfagadar@yahoo.cominstitute of Chemistry Timisoara of Romanian Academy, 24 M. Viteazul Ave, 300223-Timisoara, RomaniaPolymer electrolyte membranes used in lithium batteries must possess some mechanical, chemical and electrical properties.The electrochemical characterization of such polymer membranes implies mainly the determination of the membrane ionic conductivity, the lithium transference number, and the electrochemical stability.1. Membrane conductivityIn order to be used as battery membrane, the polymeric material must be an electrical conducting separator. The conductivity is given not by the electron mobility but by the moving of the ions. Direct current measurements are therefore not applicable for measuring the electrical resistance and accordingly the ionic conductivity of the membrane. That is why the conductivity of the membrane is determined using alternating current, where no interface polarizations are occurring. Because of the periodic change of the electric field vector, the charge carrier accumulation is not produced and the current does not decrease with time. It is the case of impedance spectroscopy by applying a sinusoidal excitation voltage signal with low amplitude on the investigated sample. The answering signal is measured and the complex impedance is calculated over a wide frequency rage, usually from 1 Hz to 1 MHz. Two types of results plots are used for data analysis and the determination of the membrane resistance: Nyquist plots and Bode diagrams. The membrane ionic conductivity can be calculated by the formula:a  = (1/R)(L/A),where: R -  the membrane resistance, L -  the height of the sample between the electrodes, A -  the cross-sectional contact area of the measured sample with the electrodes.For experimental determination the polymeric membrane is fixed between the metal electrodes (stainless steel, gold, platinum, etc.). Swagelok cells are very suitable in this case.The described method was applied for determination of polymer electrolyte ionic conductivities. This property of the membrane is crucial for its use in electrochemical cells, and especially in batteries. The target goal for battery membranes is 10‘3 S/cm at room temperature. Some examples using this method are given in Table 1.The ionic conductivities of the polymer electrolytes depend strongly on the composition and temperature. It can change between 10'2 -  10'8 S/cm [12].Table 1.Membrane Conductivity (S/cm) Ref.Siloxane lithium ion conducting polymer electrolytes (poly {[3 - [2,3 (carbonyldioxy)propoxy]propyl] methylsiloxane)lC '-lO '3(7.99x10‘3 at 25°C and 3.69xl0‘2 at 60°C)1Lewis-acid modified polymer LiBF4/ ethylene carbonate + diethyl carbonate + triethylphosphate4-6x1 O'3 (the best values)2Poly (vinylidene fluoride-co-hexafluoropropylene)-based composite polymer electrolyteo u O li.3P, 0  polymers (obtained from polyethylene glycols and organophosphates) containing lithium salts1-4 xlO’3 4Polyphosphonates with lithium perfluoromethyl sulfonimide as the ionic salt0.6-1.0x10~3 at 22°C 5Polyethylene imine) and lithium salts (LiF, LiCI, LiBr, Lil, LiSCN, LiC104 and LiBF4)10~8 (room temp.) 10'3 (150 °C)6Lithium-salt/poly(ethylene oxide)complex polymer electrolytes (LiCF3S0 3 -PE0 x and LiCI04-PEOx)10'3 7Cross-linked polysiloxanes containing oligoethylene oxide units, (OCH2CH2)n, as internal free chains complexed with LiN(CF3S0 2)2 salt2.50x1 O' 3 to 1.62x10'4 8Ternary blends of poly(ethylene oxide), poly(bisphenol A-co-epichlorohydrin) and poly(vinyl ethyl ether), containing lithium perchlorate (LiC104)10‘4 - 10‘3 S/cm (max 4.23xl0'3) (25°C)9Poly(oligo [oxyethylene] oxyterephthaloyl) and LiC104 penetrated into microporous polyethylene3.2xl0 ' 4(25°C)10Solid polymer electrolyte membranes prepared by photo­polymerisation of poly(ethyleglycol)methacrylic oligomers in the presence of a lithium salthigher than 10 ‘4 (60°C)112. Transference numberTransference or transport number characterises the contribution of the charged particles present in the electrolyte to the charge transport across the electrochemical cell. It is a dimensionless parameter and it represents the fraction from the overall current transported by a particular charged species present in the electrolyte (ions and electrons).For the determination of the transference number the Bruce & Vincent method [13] can be used. All necessary equipment will be prepared in a glove box. The cell used is in a symmetrical Li/electrolyte/Li configuration (lithium metal electrodes in a Swagelok type), assembled in glove box due to highly reactivity of metallic lithium towards air constituents. The EIS spectrum is recorded in range of frequencies of lHz-lOOkHz. Potentiostatic polarization to the cell is applied (potential should be in range of 10-20mV vs. lithium) and the current evolution is followed until a steady state is reached (sometimes it can take even tens of hours). After the stabilization of the current, the polarization is stopped and another impedance spectrum (similarly as before) is recorded. The transference number is then calculated using the Bruce-Vincent formula: tu = Iss(V-IoRo) / [Io(V-IssRss)],where: tL; -  lithium transference number, V -  applied potential, I0 -  initial current, ISs -  steady state current, R0 -  initial resistance of the passivation layer, RSs -  resistance of the passivation layer (steady state).Some examples are given in Table 2.Table 2.Membrane tLi+ Ref.Poly (vinylidene fluoride-co-hexafluoropropylene)-based composite polymer electrolyte0.3-0.5 3Composite polymer electrolyte based on polyethyleneoxide)-lithium tetrafluoroborate(addition of sulphatepromoted superacid zirconia)0.42±0.05 (0.68±0.05 with S-Zr02)14Lewis-acid modified polymer (LiBF^ ethylene carbonate + diethyl carbonate + triethylphosphate)~0.6 2Copolymer electrolyte: poly(laurylmethacrylate) and PEO- based poly[oligo(oxyethylene)methacrylate] + polyethylene glycol dimethyl ether and doped with LiCFsSCL0.5(room temp.)15Poly(acrylonitrile)-based gels (using lithium salts like LiN(CF3S02)2 )>0.5(enhanced to 0.7)12Poly(methyl methacrylate) as polimer matrix and different electrolytes0.2-0.7 12, 163. The electrochemical stability windowThe electrochemical stability (decomposition voltage) of the polymer electrolyte membrane can be measured by linear sweep voltammetry. The working electrode is usually a stable metal electrode (platinum, stainless steel) or acetylene black, lithium metal being the counter and reference electrode.The potentials for anodic oxidation (anodic stability) for some membrane electrolytes, obtained by linear voltammetry, are presented in Table 3. The electrochemical stability windows are sufficiently wide for using the membranes in lithium batteries. The high values make them to resist for overcharge abuse in rechargeable Li-based batteries, which have a high working voltage by itself.Table 3.Membrane Anodic limit Ref.Poly (vinylidene fluoride-co-hexafluoropropylene)- based composite polymer electrolyte> 4.7 V vs Li/Li+ 3Polymers containing ethylene oxide groups linked with phosphate groups, LiCICL6 V vs Li/Li+ 4Microporous polyethylene with highly conductive solvent- free polymer electrolyte based on poly(oligo [oxyethylene] oxyterephthaloyl)> 4.4 V vs Li/Li+ 10Solid polymer electrolyte membranes prepared by photo­polymerisation of poly(ethyleglycol)methacrylic oligomers in the presence of a lithium salt5 V vs Li/Li+ 11Copolymerization of methylmethacrylate monomer onto polyethylene separator4.6 V vs Li/Li+ 17Poly(lauryl methacrylate)-6 -poly[oligo(oxyethylene) methacrylate]-based block copolymer electrolytes~4 V vs Li/Li+ 15The 17th Int. Symp. on Analytical and Environmental Problems, Szeged, 19 September 2011 ACKNOWLEGEMENTSThe research leading to these results has received funding from the European Community's Seventh Framework Programme (F P 7 /2007-2013) under g ra n t ag reem en t n° 266090 (SOMABAT).LIST OF REFERENCES[1] Spiegel E.F., Adamic K.J., Sammells A.F. (1998). Advanced High Energy Lithium Polymer Electrolyte Battery, D O D  U.S. Army, C on tract no. D A A B 0 7 -9 8 -C -G 0 0 5 .[2] Lalia B.S., Yoshimoto N., Egashira M., Morita M. (2009). Effects of Lewis-acid polymer on the electrochemical properties of alkylphosphate-based non-flammable gel electrolyte. Journal o f  P o w er Sources, 194, p. 531-535.[3] Xie H., Tang Z., Li Z., He Y., Liu Y., Wang H. (2008). PVDF-HFP composite polymer electrolyte with excellent electrochemical properties for Li-ion batteries. J. S o lid  S ta te  E lectrochem . 12, p. 1497-1502.[4] Morris R.S., Dixon B.G. (2003). A novel approach for development of improved polymer electrolytes for lithium batteries. Jou rnal o f  P o w er  Sources 119-121, p. 487-491.[5] Dixon B.G., Morris R.S., Dallek S. (2004). Non-flammable polyphosphonate electrolytes, Journal o f  P o w er S ou rces 138, p. 274-276.[6] Chiang C.K., Davis G.T., Harding C.A., Takahashi T. (1986). Polymeric electrolyte based on polyethylene imine) and lithium salts, S o lid  S tate Ion ics 18-19, p. 300-305.[7] Weston J.E., Steele B.C.H. (1981). Thermal history-conductivity relationship in lithium salt-poly(ethylene oxide) complex polymer electrolytes, S o lid  S ta te  Ion ics 2, p. 347-354.[8] Zhang Z.C., Jin J.J., Bautista F., Lyons L.J., Shariatzadeh N., Sherlock D., Amine K., West R. (2004). Ion conductive characteristics of cross-linked network polysiloxane-based solid polymer electrolytes, S o lid  S ta te  Ion ics 170, p. 233-238.[9] Rocco A.M., de Assis Carias A., Pereira R.P. (2010). Polymer electrolytes based on a ternary miscible blend of polyethylene oxide), poly(bisphenol A-co-epichlorohydrin) and poly(vinyl ethyl ether), P o lym er  51, p. 5151-5164.[10] Oh J.-S., Kang Y., Kima D.-W. (2006). Lithium polymer batteries using the highly porous membrane filled with solvent-free polymer electrolyte, E lectro ch im ica  A c ta  52, p. 1567-1570.[11] Nair J.R., Gerbaldi C., Destro M., Bongiovanni R., Penazzi N. (2011). Methacrylic-based solid polymer electrolyte membranes for lithium-based batteries by a rapid UV-curing process, R eactive & F unctional P o lym ers  71, p. 409-416.[12] Stephan A.M. (2006). Review on gel polymer electrolytes for lithium batteries, E uropean  P olym er Journal 42, p. 21-42.[13] Bruce P.G., Vincent C.A. (1987). Steady state current flow in solid binary electrolyte cells, J. E lectroanal. Chem. 255, p. 1-17.[14] Croce F., Settimi L., Scrosati B. (2006). Superacid Zr0 2 -added, composite polymer electrolytes with improved transport properties, E lectroch em istry  C om m u nications 8 , p. 364- 368.[15] Soo P.P., Huang B., Jang Y.-I., Chiang Y.-M., Sadoway D.R., Mayes A.M. (1999). Rubbery Block Copolymer Electrolytes for Solid-State Rechargeable Lithium Batteries, Journal o f  The E lec troch em ica l S o c ie ty  146, p. 32-37.[16] Appetecchi G.B., Croce F., Scrosati B. (1995). Kinetics and stability of the lithium electrode in PMMA-based gel electrolytes, E lectrochim . A c ta  40, p. 991.[17] Gao K., Hu X., Yi T., Da C. (2006).PE-g-MMA polymer electrolyte membrane for lithium polymer battery, E lectrochim . A c ta  52, p. 443-449.

Electrochemical analysis of solid polymer electrolyte membranes used in lithium-based batteries : a literature survey

http://acta.bibl.u-szeged.hu/76439/1/proceedings_of_isaep_2011_263-266.pdf

Electrochemical analysis of solid polymer electrolyte membranes used in lithium-based batteries : a literature survey

Abstract

Similar works

Full text

Available Versions

University of Szeged