Solid Polymer Electrolyte conductivity

A membrane ionomer, in particular a polyelectrolyte with an inert backbone such as Nation . They require a plasticizer (typically water) to achieve good conductivity levels and are associated primarily, in their protonconducting form, with solid polymer-electrolyte fuel cells. 

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. 

X-Ray Photoelectron Investigation of Phosphotungstic Acid as a 159 Proton-Conducting Medium in Solid Polymer Electrolytes Clovis A. Linkous, Stephen L. Rhoden, and Kirk Scammon... 

The solid polymer electrolyte approach provides enhanced safety, but the poor ambient temperature conductivity excludes their use for battery applications. which require good ambient temperature performance. In contrast, the liquid lithium-ion technology provides better performance over a wider temperature range, but electrolyte leakage remains a constant risk. Midway between the solid polymer electrolyte and the liquid electrolyte is the hybrid polymer electrolyte concept leading to the so-called gel polymer lithium-ion batteries. Gel electrolyte is a two-component system, viz., a polymer matrix... 

Although the literature on electrodeposited electroactive and passivating polymers is vast, surprisingly few studies exist on the solid-state electrical properties of such films, with a focus on systems derived from phenolic monomers, - and apparently none exist on the use of such films as solid polymer electrolytes. To characterize the nature of ultrathin electrodeposited polymers as dielectrics and electrolytes, solid-state electrical measurements are made by electrodeposition of pofy(phenylene oxide) and related polymers onto planar ITO or Au substrates and then using a two-electrode configuration with a soft ohmic contact as the top electrode (see Figure 27). Both dc and ac measurements are taken to determine the electrical and ionic conductivities and the breakdown voltage of the film. 

Interest in new solid polymer electrolytes has driven some research groups to investigate other materials containing proton conducting moieties aside from sulfonic acid. Polymers and copolymers from monomers containing phosphonic-based proton conductors have been reported. Phosphonic and/or phosphinic acid containing polymers have not been well studied because of the rather limited synthetic procedures available for their preparation, compared with sulfonic acid derivatives. Miyatake and Hay... 

Liq./solid/liq. systems offer best prospects, if solid electrolytes can be made thin, tough, and chemically resistant as well as conductive. Turnaround efficiency can be high, in both the Na/3-Al203/S and the H2/solid-polymer-electrolyte/Cl2 systems, as class examples. 

Note 4 An intrinsically conducting polymer should be distinguished from a conducting polymer composite and from a solid polymer electrolyte. 

Note 1 An example of a solid polymer electrolyte is a solution of a lithium salt in a poly(oxyethylene) matrix the ionic conductivity of such material is due to the mobility of lithium cations and their counterions in an electric field. 

Note 6 Electric conductance of a nonconducting polymer can be achieved by dispersing conducting particles (e.g., metal, carbon black) in the polymer. The resulting materials are referred to as conducting polymer composites or solid polymer-electrolyte composites. 

Paddison SJ (2003) Proton conduction mechanism at low degrees of hydration in sulfonic acid-based polymer electrolyte membranes. Ann Rev Mater Res 33 289-319 Rasten E, Hagen G, Tunold R (2003) Electrocatalysts in water electrolysis with solid polymer electrolyte. Electrochimica acta 48 3945-3952... 

The successful synthesis of a transparent solid polymer electrolyte (SPE) based on PEO and alkoxysilanes has been reported (41). The material possessed good mechanical properties and high electrical conductivity (around 1.8 x 10-5 S/cm at 25°C) dependent on the oiganic—inoiganic ratio and PEO chain length. 

A second class of important electrolytes for rechargeable lithium batteries are solid electrolytes Of particular importance is the class known as solid polymer electrolytes (SPEs) SPEs are polymers capable of forming complexes with lithium salts to yield tome conductivity. The best known of the SPEs are the lithium salt complexes of polytethylene oxide) (PEO), -(CH.CH OH 1,-, and polypropylene oxide) (PPO). 

Solid Polymer Electrolyte Fuel Cell Here, there is no apparent liquid solution, or high-temperature ionic conductor. The usual ionic solution between the electrodes is replaced by a well-humidified membrane made of a perfluorosulfonic acid polymer that conducts protons. 

Ion conducting polymers may be preferable in these devices electrolytes because of their flexibility, moldability, easy fabrication and chemical stability (for the same reasons that they have been applied to lithium secondary batteries [19,48,49]). The gel electrolyte systems, which consist of a polymeric matrix, organic solvent (plasticizer) and supporting electrolyte, show high ionic conductivity about 10 5 S cnr1 at ambient temperature and have sufficient mechanical strength [5,7,50,51], Therefore, the gel electrolyte systems are superior to solid polymer electrolytes and organic solvent-based electrolytes as batteries and capacitor materials for ambient temperature operation. 

The solid polymer electrolyte is a solid plastic material which has ion exchange characteristics that make it highly conductive to hydrogen ions. The particular material that is used for the current electrolysis cells is an analogue of TFE teflon to which sulfonic acid groups have been linked. This plastic sheet is the only electrolyte required, there are no free acidic or caustic liquids, and the only liquid used in the system is distilled water. 

In polyelectrolyte gels the variation of pH or salt concentration (cs) causes a swelling or shrinkage. Therefore, in this case chemical energy is transformed to mechanical work (artificial muscles). An increase of cs (or a decrease of temperature) makes the gel shrink. Usually, the shrinking process occurs smoothly, but under certain conditions a tiny addition of salt leads to the collapse of the gel [iii, iv]. Hydration of macroions also plays an important role, e.g., in the case of proton-conductive polymers, such as -> Nafion, which are applied in -rfuel cells, -> chlor-alkali electrolysis, effluent treatment, etc. [v]. Polyelectrolytes have to be distinguished from the solid polymer electrolytes [vi] (- polymer electrolytes) inasmuch as the latter usually contain an undissociable polymer and dissolved small electrolytes. 

A second commercially available electrolyzer technology is the solid polymer electrolyte membrane (PEM). PEM electrolysis (PEME) is also referred to as solid polymer electrolyte (SPE) or polymer electrolyte membrane (also, PEM), but all represent a system that incorporates a solid proton-conducting membrane which is not electrically conductive. The membrane serves a dual purpose, as the gas separation device and ion (proton) conductor. High-purity deionized (DI) water is required in PEM-based electrolysis, and PEM electrolyzer manufacturer regularly recommend a minimum of 1 MQ-cm resistive water to extend stack life. 

Forsyth, M., Meakin, P., MacFarlane, D.R., Hill, A.J. (1993) Free volume and conductivity of plasticized polyether-urethane solid polymer electrolytes . J. Phys. Condens. Matter 7, 7601. 

Fig. 23. Schematic illustrations for solid polymer electrolyte fuel cell and composite electrode with Pt catalyst, carbon conducting material, and binding polymer material.

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