Novel Electrolyte Materials

INORGANIC MATERIALS FOR SOLID OXIDE FUEL CELLS 

Other potential electrolytes with the perovskite-type structure are the SrSni xFex03 g (0 x l) compositions or Ga and Sc doped CaTiOg. It has been found that solid solutions of SrSni Fea 03 5 with low Fe contents ( 0.3) exhibit regimes of predominant ionic and electronic conductivity. For example, SrSno.9Feo.1O3 exhibits p- and n-type electronic conductivity at high and low oxygen partial pressures, respectively. 

Lanthanum molybdate, LaiMoiOg, has been reported to exhibit fast oxide ion conducting properties comparable with the conventional zirconia and ceria compositions. This compound presents a different crystal structure from all known oxide electrolytes, and consists of isolated [Mo04] units in a three-dimensional matrix of [LaiO] . La2Mo209 undergoes a reversible phase transition from the non-conductive monoclinic a-form to the highly conductive cubic -form at approximately 580 °C. Powder X-ray diffraction (XRD) of the phases a and fl are practically identical, because the structural phase transition a is actually a transition from a static to dynamic distribution of the oxygen defects 

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Solid oxide fuel cells have been the subject of extensive research activities over the past 40 years, with significant advances made in the development of materials for anodes and cathodes and the identification of novel electrolyte materials. Developers have selected a relatively narrow compositional space to explore, focussing on the fluorite, AO2, and perovskite, ABO3, structural families. Indeed the materials currently used in SOFCs can be narrowed down to the choice of one of three electrolytes yttria stabilised zirconia (YSZ), gadolinium substituted ceria (GDC) or substituted lanthanum gallates [1], with most interest in YSZ and GDC. For the electrodes there are currently limited choices for developers, with Ni... 

As a further approach for novel electrolytes appropriate for selective cation transport, we have prepared poly(organoboron halide)-imidazole complexes.35 Even though boron-amine complexes are widely known materials reported by the early works of H. C. Brown et al.,52-54 they had not been investigated as solvents or electrolytes to the best of our knowledge. 

Solid polymer and gel polymer electrolytes could be viewed as the special variation of the solution-type electrolyte. In the former, the solvents are polar macromolecules that dissolve salts, while, in the latter, only a small portion of high polymer is employed as the mechanical matrix, which is either soaked with or swollen by essentially the same liquid electrolytes. One exception exists molten salt (ionic liquid) electrolytes where no solvent is present and the dissociation of opposite ions is solely achieved by the thermal disintegration of the salt lattice (melting). Polymer electrolyte will be reviewed in section 8 ( Novel Electrolyte Systems ), although lithium ion technology based on gel polymer electrolytes has in fact entered the market and accounted for 4% of lithium ion cells manufactured in 2000. On the other hand, ionic liquid electrolytes will be omitted, due to both the limited literature concerning this topic and the fact that the application of ionic liquid electrolytes in lithium ion devices remains dubious. Since most of the ionic liquid systems are still in a supercooled state at ambient temperature, it is unlikely that the metastable liquid state could be maintained in an actual electrochemical device, wherein electrode materials would serve as effective nucleation sites for crystallization. 

Catalytic Activity of Cathodic Materials for MCFCs. This project, supported by the Programme for Scientific and Technical Bilateral Cooperation between Portugal and Spain), addressed stability of materials and the electrolyte under operating conditions and consequent loss of catalytic activity. Given the complexity of the problem and the time context for this type of project, the research was limited to the cathode Dissolution of LiNiO cathodes has lead to the search for novel alternative materials that, exhibiting high electronic conductivity and... 

An ionic liquid (IL) , or classically a room-temperature molten salt , is an interesting series of materials being investigated in a drive to find a novel electrolyte system for electrochemical devices. ELs contain anions and cations, and they show a liquid nature at room temperature without the use of any solvents. The combination of anionic and cationic species in ILs gives them a lot of variations in properties, such as viscosity, conductivity, and electrochemical stability. These properties, along with the nonvolatile and flame-resistant nature of ILs, makes this material especially desirable for lithium-ion batteries, whose thermal instability has not yet been resolved despite investigations for a long time. In this chapter we discuss the efforts made for battery application of ILs. 

The development of high-performance electrode and electrolyte materials for SOFC is an important step towards reducing the fuel cell operation temperature to the low and intermediate range (500 - 700 °C). As the operating temperature is reduced, many cell ports, such as the auxiliary components can be easily and cost-efficiently produced. To meet long operational lifetime, material compatibility and thermomechanical resistance would be less critical as the range of possibilities for lower temperature increases. To that end, recent research at UFRN, Natal, Brazil has successfully focused on novel synthesis processes based on microwave-assisted combustion and modified polymeric precursor methods in order to synthesize high performance cobaltite-based composite cathodes for low-intermediary-temp>erature SOFCs. 

The cell producers accomplished the performance improvements through engineering improvements in cell design, new electrode materials, and automated high-speed production to reduce the cost. The capacity of the 18650 cell had reached 2.9 Ah in 2007 based on treated graphite anode and planar-nickel-based cathode and with several kinds of electrolyte additives [12]. With further continuous improvements in all the cell components that includes silicon alloy-type anode materials, lithium-nickel-cobalt-aluminum and nickel-manganese-cobalt cathode materials, novel electrolyte and/or additives, some cell manufacturers are currently able to achieve a maximum capacity of up to 3.4 Ah for the same 18650 cell design. 

Throughout the book, the applicability and multiple roles of techniques—such as electrochemical impedance spectroscopy—for studying and aiding the development and characterization of novel electrode and electrolyte materials are discussed. It is recognized that optimization of separators and study of electrochemical phenomena at the ZBB membrane is an important part of the development process, such as novel graphene oxide-Nafion composite materials [79]. However, this aspect is left for another review focusing on membrane technology for RFB applications. 

As already discussed, the electrolyte is the most important component of a SOFC, the properties of which determine critical parameters such as cell performance and temperature of operation. Because of this, much time has been devoted to developing and understanding the materials and their properties and Raman spectroscopy has been a key tool. This section summarises the key results of studies that have used Raman spectroscopy to investigate electrolytes for SOFCs and is split into three parts. The first focuses on Zirconia based materials the conventional electrolyte of choice. The second will summarise the results of investigations on Ceria based electrolytes the frontrunner electrolyte for intermediate temperature SOFCs. Other novel electrolytes which have some potential for reduced temperature operation will be summarised in the final section. 

Smo.sSro.sCoOa has been used as a cathode material for the LSGM electrolyte, and a low cathodic overpotential of less than 50 mV at 0.5 A/cm was obtained at 873 K [203]. BaCoOa was also investigated as a novel cathode material for the... 

Taking advantage of the possibilities offered by polymer chemistry for creating novel materials, a new generation of polymeric membranes for HT-PEM fuel cells has been designed and developed. The herein presented aromatic polyether sulfones carrying main chain pyridine units have been proven to be a reliable polymer electrolyte material for the HT-PEM fuel cell technology. These materials exhibit certain... 

Determination of tartaric, malic, succinic, acetic, and lactic acids, as well as sulfate in different wines (in 30 mM MES, lOmML-histidine at pH 5.6) as well as saccharides in different soft beverages (in 50 mM NaOH and 0.2 mM CTAB at pH 12.7) were proposed to demonstrate the analytical suitability of this novel microchip material. Of special interest was the suitability of PEEK for sugar determination since the strong background electrolyte (BGE) conditions required are not suitable for other conventional polymers commonly used in polymer microchip fabrication such as PMMA, revealing the role of PEEK in this kind of food applications. 

Therefore ILs have been intensively studied recently as novel, much safer electrolyte materials (Sakaebe, 2007) for electrochemical devices (Ohno 2005) and energy storing devices, such as Li batteries for cellular phones (Xu, 2006), batteries for vehicles, fuel cells, supercapacitors (Sato, 2004), solar cells (Stathatos, 2005.), etc... 

Obviously, the properties of the electrolyte in Li-ion batteries are of crucial importance, and a few comprehensive general review articles have already been pubhshed on the subject [116, 117, 120, 133]. In this chapter, the recent advances and new trends in electrolyte research will be overviewed from a wide angle, with a focus on novel electrolytes and electrolyte additives for high-energy electrode materials. 

To increase the operating temperature of a PEFC to approximately 90 C, the development of advanced technologies, such as materials for high-temperature operation in low-humidity conditions, has to be promoted. Long-term advanced technologies, such as a non-precious-metal catalyst and a novel electrolyte for operation without humidification, have also been studied. We expect that electrical generation efficiency should exceed 36% in terms of the HHV in the future. 

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