Solid ceramic electrolyte

Ionic conductors, used in electrochemical cells and batteries (Chapter 6), have high point defect populations. Slabs of solid ceramic electrolytes in fuel cells, for instance, often operate under conditions in which one side of the electrolyte is held in oxidizing conditions and the other side in reducing conditions. A signihcant change in the point defect population over the ceramic can be anticipated in these conditions, which may cause the electrolyte to bow or fracture. 

SOE cells utilize solid ceramic electrolytes (e.g. yttria stabilized zirconia) that are good oxygen ion (0 ) conductors at very high temperatures in the range of 1000°C [8]. The operating temperature is decided by the ionic conductivity of the electrolyte. The feed gas, steam mixed with hydrogen, is passed through the cathode compartment. At the cathode side, the reaction is... 

The high ionization potential and the very low density of the metals are promising to make use of them in high-temperature batteries Electrochemical cells using lithium as anode, a solid ceramic electrolyte and lithium polysulphide as cathode may reach a theoretical energy density of 3000 Wh kg- . Problems are caused by the bad compatibility of lithium with ceramic materials. 

The solid oxide fuel cell (SOFC) is based on a thin layer of solid ceramic electrolyte of yttria-stabilized zirconia operating at 600 to 1000°C, which transfers the oxygen ion (O ) from the cathode to the anode. The high temperature is necessary to achieve sufficient ionic conductivity [14]. The electrochemical reaction in an SOFC can be expressed as equation (1.16) to equation (1.18). 

Solid ceramic electrolyte used does not suffer electrolyte vaporization loss or excessive corrosion seen in high-temperature liquid electrolyte systems. 

A unique application of the solid oxygen electrolytes is in dre preparation of mixed oxides from metal vapour deposits. For example, the ceramic superconductors described below, have been prepared from mixtures of the metal vapours in the appropriate proporhons which are deposited on the surface of a solid electrolyte. Oxygen is pumped tluough the electrolyte by the application of a polarizing potential across the electrolyte to provide the oxidant for the metallic layer which is formed. 

A solid oxide fuel cell (SOFC) consists of two electrodes anode and cathode, with a ceramic electrolyte between that transfers oxygen ions. A SOFC typically operates at a temperature between 700 and 1000 °C. at which temperature the ceramic electrolyte begins to exhibit sufficient ionic conductivity. This high operating temperature also accelerates electrochemical reactions therefore, a SOFC does not require precious metal catalysts to promote the reactions. More abundant materials such as nickel have sufficient catalytic activity to be used as SOFC electrodes. In addition, the SOFC is more fuel-flexible than other types of fuel cells, and reforming of hydrocarbon fuels can be performed inside the cell. This allows use of conventional hydrocarbon fuels in a SOFC without an external reformer. 

Kharton VV, Marques FMB, Atkinson A (2004) Transport properties of solid oxide electrolyte ceramics a brief review. Solid State Ionics 174 135-149... 

Unlike molten carbonates, solid oxides use a hard ceramic electrolyte instead of a liquid. That means the fuel cell can be cast into a variety of useful shapes, such as tubes. With higher temperatures, sofcs may be able to cogenerate steam at temperatures as high as i,ooo°f. The Siemens Westinghouse Power Corporation has built the first advanced hybrid system, which combines a gas turbine with a tubular sofc. As of 2003, the 220 kW hybrid system has operated in California for more than 2,000 hours with a respectable 53 percent efficiency, comparable to current combined cycle gas turbines. The ultimate goal is an efficiency of 70 percent or more. 

Figure 30 Schematic of the UHV/antechamber/transfer chamber system for electrochemical measurements involving solid polymer electrolytes. Insert A provides an exploded view of the HOPG(bp) sample holder and Li[C/R]/PE0(LiC104) stainless steel holder (SSH) arrangement attached to both magnetically coupled manipulators. Insert B shows in detail the assembled H0PG(bp)/PE0(LiC104) cell in the UHV chamber. MCM = magnetically coupled manipulator GV = gate valve N = nipple CN = ceramic nipple SSH = stainless steel holder TMP = turbomolecular pump. (From Ref. 6.)...

Low rate solid-electrolyte-based cells For instance, Li/I2 cells used primarily in implantable medical devices are well established. Another example is the developmental all-solid-state Li metal/phosphorous oxynitride (PON)/intercalation cathode cells conceived for use in microelectronic circuits. The PON is a glassy ceramic electrolyte which is stable to over 5 V [25],... 

Badwal, S.P.S. and Foger, K., Solid oxide electrolyte fuel cell review. Ceramics International, 1996, 22, 257-265. 

The solid state synthesis process has also been used to study many other variations of doped lithium titanium phosphate solid ionic conductors. The ionic conductivities and compositions of the most promising lithium-ion ceramic electrolytes are shown in Table 26.2. 

The Synthesis and Fabrication of Ceramics for Special Application 17.3.7. Preparation of Solid State Electrolytes... 

Preparation of Solid State Electrolytes 17.3.7.1. )S-Alumina Ceramic Electrolytes... 

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