Electrode and Electrolyte Materials

The electrode and electrolyte materials used in SC-SOFCs are similar to the ones being used in conventional SOFCs operated with separate fuel and air compartments. However, selectivity and catalytic activity requirements and overheating impose different constraints on the cell component materials under single-chamber operating conditions. 

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Identify electrode and electrolyte material that is inexpensive and readily available in order to achieve a low-cost battery. 

The potential benefits of plasma spraying as an SOFC processing route have generated considerable interest in the process. In the manufacture of tubular SOFCs, APS is already widely used for the deposition of the interconnect layers on tubular cells, and has also been used for the deposition of individual electrode and electrolyte materials, with increasing interest in utilizing APS rather than EVD for electrolyte deposition due to the high cost of the EVD process [48, 51,104],... 

Ceria affords a number of important applications, such as catalysts in redox reactions (Kaspar et al., 1999, 2000 Trovarelli, 2002), electrode and electrolyte materials in fuel cells, optical films, polishing materials, and gas sensors. In order to improve the performance and/or stability of ceria materials, the doped materials, solid solutions and composites based on ceria are fabricated. For example, the ceria-zirconia solid solution is used in the three way catalyst, rare earth (such as Sm, Gd, or Y) doped ceria is used in solid state fuel cells, and ceria-noble metal or ceria-metal oxide composite catalysts are used for water-gas-shift (WGS) reaction and selective CO oxidation. 

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. 

Zheng, C., M. Yoshio, L. Qi, and H. Y. Wang. 2014. A 4 V-electrochemical capacitor using electrode and electrolyte materials free of metals. Journal of Power Sources 260 19-26. 

The results reported above indicate that a proper choice of the battery components enables the intrinsic potentialities of the polymer electrode and electrolyte materials to be exploited for the development of revolutionary electrochemical devices. Accordingly, a number of laboratories are currently seeking to enhance the electrochemical properties of conducting polymers by designing suitable materials, the final goal being to optimise their response in advanced, plastic-like batteries. Undoubtedly, this will be the type of batteries that will dominate the electronic market in the new millennium. 

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. 

In SOFCs, one of the major sources of poIari2ation losses is the ohmic resistance [16]. A possibility for reducing the ohmic resistance is to decrease the electrolyte thickness to a few tens of micrometers [56], which in turn also permits a decrease in the operating temperature. In order to maintain mechanical stabihty, a thick anode is used as support for the thin electrolyte. Anode-supported SC-SOFCs use the same electrode and electrolyte materials as the electrolyte-supported SC-SOFCs. 

Over the past twenty years, the unit cell performance of at least some of the fuel cell technologies has been dramatically improved. These developments resulted from improvements in the three-phase boundary, reducing the thickness of the electrolyte, and developing improved electrode and electrolyte materials which broaden the temperature range over which the cells can be operated. 

Despite marked improvements in recent years in ES electrode and electrolyte material areas, several challenges remain. In this chapter, the market challenges of ES development efforts will be first discussed, followed by defailed discussions of fhe progress and technical challenges facing elec-frode and elecfrolyfe maferial developments. In addition, the computational tools that can be utilized to supplement material development efforts will... 

In SC-SOFCs the same electrode and electrolyte materials are generally used as described in Chapter 8 for conventional SOFCs. For anodes a Ni-cermet with... 

The ohmic loss is inversely proportional to conductivity so developing high-conductivity electrodes and electrolyte materials is critical. From the above examples, we know that ionic charge transport in the electrolyte accounts for most of the ohmic loss. However unfortunately, the development of satisfactory ionic conductors is still challenging because a good fuel cell electrolyte must have high ionic conductivity and stability at the same time. The three most widely used material classes for fuel cells are aqueous electrolytes, polymer electrolytes and ceramic electrolytes. 

An electrode model is especially advantageous if it can be used to relate the kinetic and mass transfer resistance to electrode geometry and microstructure for instance, to thickness, porosity, pore or particle size, contact areas of phases, and/or grain size of electrode and electrolyte materials. A well-tested and validated electrode model, therefore, may serve to assist in the design of optimised electrode structures or electrode/electrolyte interfaces to minimise polarisation loss. 

After over 20 years of their commercialization, lithium-ion batteries have experienced a rapid market growth despite a sluggish worldwide economy. With emerging new markets, lithium-ion batteries need to provide enhanced performance in terms of energy density, power density, calendar life, and safety.This requires the development of new electrode and electrolyte materials capable of storing more lithium at faster rates with higher chemical, thermal, and mechanical stability. 

Finally, the intercalation chemistry that drives lithium-ion batteries can allow only a maximum exchange of two electrons per mole. This rmdoubt-edly limits the overall battery capacity and consequently restricts the energy density to a maximum of 15()-200 Wh kg. To meet the basic requirements of batteries for electric transportation, which include safety, low cost and high energy density, new electrode and electrolyte materials have to be developed. 

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