Solid polymer electrolytes structure

Incorporation into a Polymer Layer In recent years a new electrode type is investigated which represents a layer of conducting polymer (such as polyaniline) into which a metal catalyst is incorporated by chemical or electrochemical deposition. In some cases the specific catalytic activity of the platinum crystallites incorporated into the polymer layer was found to be higher than that of ordinary dispersed platinum, probably because of special structural features of the platinum crystallites produced within the polymer matrix. A variant of this approach is that of incorporating the disperse catalyst directly into the surface layer of a solid polymer electrolyte. 

Ding, J. F, Chuy, C. and Holdcroft, S. 2002. Solid polymer electrolytes based on ionic graft polymers Effect of graft chain length on nano-structured, ionic networks. Advanced Functional Materials 12 389-394. 

The MEA consists of a thin (10-200 pm) solid polymer electrolyte (a protonic membrane, such as Nation) on both sides of which are pasted the electrode structures (fuel anode and oxygen cathode) (Figure 9.5). The electrode structure comprises several layers the first layer made of carbon paper (or cloth) to strength the structure, on which are coated the GDL, and then the catalyst layer (CL), directly in contact with the protonic membrane (usually Nafion). 

Figure 1 Structure of solid polymer electrolyte electrolyzer (SPE).

Figure 3.23 Chemical structure of perfluorocarbon sulfonic acid membranes as solid polymer electrolytes for fuel cells.

M. Inaba, J.T. Hinatsu, Z. Ogumi and Z. Takehara, Application of the solid polymer electrolyte method to organic electrochemistry. XV. Influence of the multiphase structure of Nafion on electroreduction of substituted aromatic nitro compounds on Cu, Pt-Nafion, J. Electrochem. Soc., 1993, 140, 706 M. Inaba, Z. Ogumi and Z. Takehara, Application of the solid polymer electrolyte method to organic electro-... 

In addition to the modified electrodes described in the previous sections, which usually involve a conductive substrate and a single film of modifying material, more complicated structures have been described. Typical examples (Figure 14.2.4) include multiple films of different polymers (e.g., bilayer structures), metal films formed on the polymer layer (sandwich structures), multiple conductive substrates under the polymer film (electrode arrays), intermixed films of ionic and electronic conductor (biconductive layers), and polymer layers with porous metal or minigrid supports (solid polymer electrolyte or ion-gate structures) (6,7). These often show different electrochemical properties than the simpler modified electrodes and may be useful in applications such as switches, amplifiers, and sensors. 

Poly(oxyethylene) combinations with various other comonomers [46], are of interest as solid polymer electrolytes after complex formation with Li(I) (complexation with Na(I), K(I), Mg(II), Ba(II), etc. has also been studied) [1,5,46-48]. The synthesis is carried out by direct interaction of the ligand and metal ions in solution or, if cross-linked poly(oxyethylene) is employed, by immersing the polymer ligand into a solution of the metal salt. Poly(oxypropylene), modified polysiloxanes, cross-linked phosphate esters and ethers [46,49,50], and structurally different ligands such as 2,5-dimercapto-1,3,4-thiadiazol-polyaniline [51] have also been used as polymer ligands, The developments in this field are reviewed in [46], In this review the segmental motion of Li(I) in a poly(oxyethylene) is described as shown in Fig. 5-4. 

Agapov, A.L., Sokolov, A.P., 2011. Decoupling ionic conductivity from structural relaxation a way to solid polymer electrolytes Macromolecules 44,4410-4414. 

Qiao, J., Fu, J., Lin, R., Ma, J., Liu, J., 2010. AUcaUne solid polymer electrolyte membranes based on structurally modified PVA/PVP with improved alkali stability. Polymer 51,4850-4859. 

As documented in and expressed by these various contributions, the topic Polymers for Fuel Cells is a vast one and concerns numerous synthetic and physico-chemical aspects, derived from the particular application as a solid polymer electrolyte. In this collection of contributions, we have emphasized work which has already led to tests of these polymers in the real fuel cell environment. There exist other synthetic routes for proton-conducting membrane preparation, which are not discussed in this edition. Furthermore, certain polymers are utilized as fuel-cell structure materials, e.g., as gaskets or additives (binder, surface coating) to bipolar plate materials. These aspects are not covered here. 

R. Neat, M. Glasse, R. Linford, A. Hooper, Solid State Ionics 1986, 18—19, 1088-1092. Thermal history and polymer electrolyte structure implications for solid-state battery design. 

In Chapter 10, the authors will demonstrate the preparation techniques for ASPEM and the characterization results. The relationship between structure and properties will be discussed and compared. The double-layer carbon air cathodes were also prepared for solid-state alkaline metal fuel cell fabrication. The alkaline solid state electrochemical systems, sueh as Ni-MH, Zn-air fuel cells, Al-air fuel cells, Zn-Mn02 and Al-Mn02 cells, were assembled with anodes, cathodes and alkaline solid polymer electrolyte membranes. The electrochemical cells showed excellent cell power density and high electrode utilization. Therefore, these PVA-based solid polymer electrolyte membranes have great advantages in the applications for all-solid-state alkaline fuel cells. Some other potential applieations include small electrochemical devices, sueh as supercapacitors and 3C electronic products. 

Li, J., Pratt, L. M., and Khan, I. M., Poly(ethylene oxide)/poly(2-vinylpyridine)/lith-ium perchlorate blends as solid polymer electrolytes. Composition/property/structure interrelationship, J. Polym. Sci. Chem. Ed., 33, 1657-1663 (1995). 

To improve effectiveness of the platinum catalyst, a soluble form of the polymer is incorporated into the pores of the carbon support structure. This increases the interface between the electrocatalyst and the solid polymer electrolyte. Two methods are used to incorporate the polymer solution within the catalyst. In Type A, the polymer is introduced after fabrication of the electrode in Type B, it is introduced before fabrication. 

By combining an electrically conductive polymer (e.g. POT) prepared by spin coating from solution with a solid polymer electrolyte and a metal oxide, a sohd state electrochromic device is constructed [713]. Substrates coated with PT can be used in electrochromic displays, in solar cells (cf Sect. 6.3), and for corrosion protection [714]. Poly(3,4-ethylenedioxythiophene-2,5-diyl), which has good electrochromic properties, (for structure cf Sect. 1.2) can used as an electrode in a solid state electrochromic cell (cf Sect. 3.4.3) [43]. PITN can be reversibly cation- and anion-doped without decomposition. This polymer, with... 

Fedkiw Jr PS. Preparing in situ electrocatalytic films in solid polymer electrolyte membranes, composite microelectrode structures produced thereby and chloralkali process utilizing the same. United States patent US 4959132. 1990 Sep 25. 

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