High temperature solid polymer electrolytes

Arico AS, Creti P, Antonucci PL, Antonucci V. 1998. Comparison of ethanol and methanol oxidation in a liquid-feed solid polymer electrolyte fuel cell at high temperature. Electrochem Sol Lett 1 66-68. 

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. 

Industrial cells are mainly bipolar consisting of a large number of individual plate cells connected back to back and coupled in blocks according to the filter press principle. If the electrolysis is carried out under pressure, the energy consumption can be reduced by 20%. Further recent developments are the use of porous electrodes, high temperature steam electrolysis and the SPE-process (solid polymer electrolyte). Heavy water, D2O, can be produced as a byproduct in water electrolysis through enrichment in the electrolyte. 

Nafion (perfluorosulfonic acid) membranes are currently used in cells with a corrosive environment and high temperature. Many of these cells are designed with the solid polymer electrolyte (SPE) configuration. The merits of the solid polymer electrolyte technology will be discussed in the next section. 

Figure 2. shows the schematic of a cell to synthesize ozone in deionized water from the backside of a three dimensional porous inert anode (lead dioxide) in contact with a solid polymer electrolyte at room temperature [15,16]. High concentrations of dissolved ozone (20 mg/L) are possible at a current density of 1 A/cm Current efficiencies, however, are low (14%). 

The last few years have witnessed a high level of activity pertaining to the research and development of all-solid, thin-film polymer electrolyte batteries most of these use lithium as the active anode material, polymer-based matrices as solid electrolytes, and insertion compounds as active cathode materials. High-performance prototypes of such batteries stand currently under research, whose trends are expected to include the development of amorphous polymers with very low glass-transition temperatures, mixed polymer electrolytes, and fast-ion conductors in which the cationic transport number approaches unity. 

Polymer electrolyte fuel cells, also sometimes called SPEFC (solid polymer electrolyte fuel cells) or PEMFC (polymer electrolyte membrane fuel cell) use a proton exchange membrane as the electrolyte. PEEC are low-temperature fuel cells, generally operating between 40 and 90 °C and therefore need noble metal electrocatalysts (platinum or platinum alloys on anode and cathode). Characteristics of PEEC are the high power density and fast dynamics. A prominent application area is therefore the power train of automobiles, where quick start-up is required. 

For example, a solid polymer electrolyte is a solution of a lithium salt in a PEO matrix the ionic conductivity of such material is due to the mobility of lithium cations and their anions in an electric field. The objective of the electrolyte system is to provide mechanical integrity and ion-conducting properties. PEO is a semicrystalline polymer at room temperature and has an exceptional property to dissolve with high concentration of a wide variety of dopants. 

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