Copolymers highly conductive polymer electrolyte

Many approaches have been developed for the production of ionic liquid-polymer composite membranes. For example, Doyle et al. [165] prepared RTILs/PFSA composite membranes by swelling the Nafion with ionic liquids. When 1-butyl, 3-methyl imidazolium trifluoromethane sulfonate was used as the ionic liquid, the ionic conductivity ofthe composite membrane exceeded 0.1 S cm at 180 °C. A comparison between the ionic liquid-swollen membrane and the liquid itself indicated substantial proton mobility in these composites. Fuller et al. [166] prepared ionic liquid-polymer gel electrolytes by blending hydrophilic RTILs into a poly(vinylidene fiuoridej-hexafluoropropylene copolymer [PVdF(HFP)] matrix. The gel electrolytes prepared with an ionic liquid PVdF(HFP) mass ratio of 2 1 exhibited ionic conductivities >10 Scm at room temperature, and >10 Scm at 100 °C. When Noda and Watanabe [167] investigated the in situ polymerization of vinyl monomers in the RTILs, they produced suitable vinyl monomers that provided transparent, mechanically strong and highly conductive polymer electrolyte films. As an example, a 2-hydroxyethyl methacrylate network polymer in which BPBF4 was dissolved exhibited an ionic conductivity of 10 S cm at 30 °C. 

M. D. Guiver, A new class of highly-conducting polymer electrolyte membranes aromatic ABA triblock copolymers. Energy Environ. Sci. 5 (1) (2012) 5346-5355. 

Copolymers with benzimidazole and benzoxazole units have been prepared and used as a polymer electrolyte material [30,11]. The polymer electrolyte material has both high proton conductivity and excellent mechanical properties even when it is obtained by in situ phosphoric acid doping. The polymer electrolyte material may substitute for the conventional phosphoric acid doped polybenzimidazole in a polymer electrolyte membrane fuel cell, particularly in a high-temperature polymer electrolyte membrane fuel cell. 

Interest in polymer electrolytes has been renewed by Seeo. According to news accounts, Seeo has developed a high-conductivity polymer. According to a patent apphcation [48], the polymer is a block copolymer consisting of polystyrene-block-poly(ethylene oxide) (SEO) diblock copolymer and requires elevated temperature to achieve a conductivity of 10 S cm . ... 

FLORIAI CZYK, Z., KRAWIEC, W., LISTOS, T., WIECZOREK, W. and PRZYLUSKI, J., 1990. Highly conductive polymeric electrolytes based on ethylene oxide copolymers and ter-polymers. Synthetic Metals, 35(1-2), 249-251. 

Nafion is a copolymer of poly(tetrafluoroethylene) and polysulfonyl fluoride vinyl ether. It has fixed anions, which are sulfonic acid sites, and consequently, by electroneutrality, the concentration of positive ions is fixed. Furthermore, the transference number of protons in this system is 1, which greatly simplifies the governing transport equations, as seen below. There can be different forms of Nafion in terms of the positive counterion (e.g., proton, sodium, etc.). Most models deal only with the proton or acid form of Nafion, which is the most common form used in polymer-electrolyte fuel cells due to its high proton conductivity. 

To obtain improved ionic mobility, and thus high conductivity, alternative polymer structures have been developed, for example comb-branched block copolymers such as poly[bis(methoxy ethoxy ethoxide)], usually known as MEEP. Room temperature conductivities of MEEP-based polymer electrolytes of the order of 10-5 S/cm have been achieved, values... 

The electrochemically active electrode materials in Li-ion batteries are a lithium metal oxide for the positive electrode and lithiated carbon for the negative electrode. These materials are adhered to a metal foil current collector with a binder, typically polyvinylidene fluoride (PVDF) or the copolymer polyvinylidene fluoride-hexafluroropropylene (PVDF-HFP), and a conductive diluent, typically a high-surface-area carbon black or graphite. The positive and negative electrodes are electrically isolated by a microporous polyethylene or polypropylene separator film in products that employ a liquid electrolyte, a layer of gel-polymer electrolyte in gel-polymer batteries, or a layer of solid electrolyte in solid-state batteries. 

As two important copolymers of PVDF, the P(VDF-HFP) [4] and P(VDF-CTFE) [23] had been developed for gel polymer electrolyte in LIBs. The introduction of copolymer components was to reduce the crystallinity of the PVDF chain. The reduction of crystallinity could increase the ionic conductivity. Electrospun P(VDF-HFP) and P(VDF-CTFE) fibrous membranes had been proved to show high ionic conductivities in the range of several mS cm which was attributed to the easy transportation of the liquid electrolyte through the fully interconnected pore structure of the membrane. For example, the electrospun P(VDF-HFP) fibrous membrane had high ionic conductivities in the range of 4.59 mS cm", high electrolyte uptake of 425 % at room temperature, and good electrochemical stability with a potential of over 4.5 V versus Li/Li+ [29]. 

DuPont s Nafion is the most advanced commercially available proton conducting polymer material, which is produced in membrane form with thickness between 25 and 250 pm. Nafion is the electrolyte against which other membranes are judged and is in a sense an Industrial Standard . It is a copolymer of tetrafluoroethylene (TFE), and perfluoro (4-methyl-3,6-dioxa-7-octene-l-sulfonyl fluoride) or vinyl ether , as shown in Fig. 3. The methods of creating and adding the side chains are highly complicated and the process involving many steps is proprietary. 

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