Rokeya Huq

Effect of plasticizers on the properties of new ambient temperature polymer electrolyte

Abstract The effect of different plasticizers on the conductivities and the physical/chemical properties of the radiation-polymerized polyether formed by cross-linking a mixture of acrylate oligomer and dissolved salts has been studied. The plasticizers used were propylene carbonate, ethylene carbonate and a mixture of ethylene carbonate and propylene carbonate. The conductivities of all the compositions studied were in the range 10−3−10−4 S cm−1. In this paper, the relationship of the conductivities to the physical, chemical, and electrochemical properties of these compositions are discussed.

Poly(ethylene oxide) Complexes of Lead Halides New Polymeric Conductors of Pb2

Poly(ethylene oxide) (PEO) easily forms complexes with PbBr/sub 2/, PbI/sub 2/, and PbCl/sub 2/. Compositions over the range of PbBr/sub 2/ . (PEO)/sub 8-30/, PbI/sub 2/ . (PEO)/sub 6-40/, and PbCl/sub 2/ . (PEO)/sub 16/ have been prepared by a two-solvent technique in which PEO is dissolved in acetonitrile and the salt is dissolved in dimethylsulfoxide. The lead halide complexes are stable to nearly 300/sup 0/C and are quite conductive. PbBr/sub 2/ . (PEO)/sub 8/, for example, has an ionic conductivity of 10/sup -6/-10/sup -7/ (..cap omega..-cm)/sup -1/ at 180/sup 0/C and in the range of 10/sup -5/ (..cap omega..-cm)/sup -1/ at 250/sup 0/C. Preliminary transport number measurements have shown that PbBr/sub 2/ . (PEO)/sub 20/ is a reasonably good conductor of Pb/sup 2+/.

Preparation and properties of PEO complexes of divalent cation salts

Abstract Complexes of poly(ethylene oxide) (PEO) with MgCl 2 and PbBr 2 have been prepared by a two-solvent technique. The resulting materials are stable to above 250°C, and generally have fairly high ionic conductivities. The conductivity of MgCl 2 . (PEO) 16 is comparable to that of LiCF 3 SO 3 . (PEO) 9 from 80° to 150°C. Preliminary transport number measurements on PbBr 2 . (PEO) 20 indicate a transport number for Pb 2+ of about 0.6 at 140°C.

Influence of plasticizers on the electrochemical and chemical stability of a Li+ polymer electrolyte☆

Abstract The influence of ethylene carbonate and propylene carbonate in varying proportions with 1M LiAsF 6 as the dissolved salt on the chemical and electrochemical properties of Li + ambient-temperature polymer electrolytes has been studied. Electrolytes with mixed plasticizer compositions of EC : PC were found not only to be thermally more stable than those prepared with pur EC or PC but also to display much improved lithium and cathode (V 6 O 13 ) inerfacial properties and superior mechanical properties. The Li cycling efficiency with the different plasticizer compositions was also investigated.

Thermal and electrical characterization of PEO-based polymer electrolytes containing mixed Co(II) and Li(I)☆

Abstract Results from the thermal and electrical characterization of the mixed electrolyte, CoBr2/LiBr [PEO]16, at different mole ratios are presented. In particular, the effect of CoBr2 on thermal stability, glass transition temperature and electrical conductivity of LiBr[PEO]16 has been examined. The observed changes in the physical properties are interpreted in terms of structural changes resulting from changes in the segmental mobility of the polymer chain and the complexation process with the different compositions. A distinct maximum in conductivity is observed when plotted as a function of CoBr2 mole fraction in the quenched samples.

Ion transport in divalent cation complexes of poly (ethylene oxide)

Abstract Electrolytes formed by dissolving ionic salts in poly (ethylene oxide) (PEO) were first considered from the perspective of crystalline solid electrolytes. It is now clear that they are an unusual form of electrolyte with properties between those of solids and true liquids. The properties of PEO electrolytes vary widely, especially the cation transport number. The most remarkable electrolytes so far are those formed by NiBr2 for which it appears that Ni2+ transport can be activated by controlled hydration/dehydration. This paper discusses the electrochemical and structural characteristics of a variety of PEO electrolytes containing divalent cations, including Cd2+, Ni2+, Co2+, Zn2+, and Pb2+.

Studies of plasticized-polymer electrolytes containing mixed Zn(II) and Li(I)

Abstract Thin solid films of mixtures of PEGDME and PEO containing various ratios of ZnBr 2 and LiBr have been prepared. Equal parts of PEGDME and PEO were used, and the ether oxygen to total metal ratio was kept constant at 16. Thermogravimetric data have shown that the thermal stability of the polymer electrolytes is affected more so by the zinc salt than the lithium salt. Differential scanning calorimetry data show that these electrolytes are inhomogeneous mixtures of amorphous regions and crystalline PEO and PEO/salt complexes. Conductivity data did not show a mixed-cation effect.

Conductivity in PEO-based Zn(II) polymer electrolytes

Abstract PEO-based electrolytes consisting of zinc halides dissolved in poly(ethylene oxide) PEO and poly(ethylene) glycol dimethyl ether [PEGM] were prepared by solution casting. Electrolytes with only PEO as the polymer appear to be principally conductors of anions. PEGM significantly increases electrolyte conductivity, particularly at room temperature, as well as the mobility of Zn(II) species.

Polyacetylene electrodes for non-aqueous lithium batteries

Abstract Polyacetylene can be electrochemically oxidized in a cell of the type Li/LiClO 4 in propylene carbonate/CH x with nearly 100% coulombic efficiency for doping levels ( y in [CH(ClO 4 − ) y ] x ) of less than 0.10. At higher values, the electrochemical potential of the oxidized film is above 3.9 V vs . Li, and the electrolyte is unstable. Reduced polyacetylene (Li y CH) x can serve as a non-aqueous battery anode in the traditional role of lithium. However, stable voltages and high coulombic efficiencies in an electrolyte of 0.8M LiClO 4 in tetrahydrofuran are only observed at reduction levels of y + is 0.5 - 1.5 V positive to that of Li in the same solution. At present, polyacetylene electrodes are rather unstable, sensitive to impurities, and characterized by low volumetric energy density and low-to-moderate gravimetric energy density. They do not appear to offer major advantages for use in high energy density, rechargeable, non-aqueous electrochemical cells.

Ionically-Conductive Solid Solutions of Divalent Cation Salts in Poly(Ethylene Oxide)

Poly(ethylene oxide) (PEO) forms solid solutions with MgCl2, PbI2, PbBr2, and various other salts of divalent cations. DSC analysis and a study of the temperature dependence of conductivity indicate that these materials consist of several crystalline phases, corresponding to pure PEO and salt-rich complexes, and a coexisting elastomeric phase. MgCl2.(PEO) has an ionic conductivity comparable to that of LiCF3 SO3.(PEO) from 10−516 (ohm cm)−1 at 80°C, and the conductivity of PbBr2.(PEO)8 is 1096 − 10−7 (ohm cm)−1 at 180°C and about 10−5 (ohm-cm)−1 at 250°C. The lead halide complexes conduct both Pb2+ and halide anions. All of the divalent halide complexes are stable to nearly 300°C.