Conventional Cathodes

Cathode materials for SOFCs based on any of the electrolytes described in Section 2.1.1 are of the perovskite structure type, generally La-based with transition metals located on the B site. Several authors have summarised the range of perovskites investigated to date, concentrating on the conductivity, ion transport and compatibility of these materials. As such it is superfluous to continue the discussion in detail here. Instead we will refer to the main cathode types only, leaving the reader to consult the relevant literature for further details. 

4Mn03 composition. Whilst LSM acts as a suitable electrode at these elevated temperatures, there are some fundamental issues with this cathode material that compromise its performance, including the reactivity of LSM with YSZ to form insulating interfacial reaction products of the pyrochlore type, La2Zr207. This is clearly detrimental to the overall performance of the cell as this reaction product acts as a blocking phase for the cathode reactions. 

With LSGM electrolytes similar cathodes have been developed with perhaps some of the most exciting recent results focusing on the Bai xSrxCoi yFey03 5 (BSCF)[ - ° and Smi.xStxCoOs-s compositions. The development of these materials has resulted from the continued interest in substitution of both the lanthanide and transition metal components in the perovskite lattice. A more detailed discussion of these new cathode materials in operation with LSGM, YSZ and CGO electrolytes is given in Section 2.2.2. 

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Tank installations with underground storage tanks and station piping should, if possible, be provided with conventional cathodic protection [3]. This is sometimes not possible because electrical separation cannot be achieved between the protected installation and other parts of the plant (see Section 11.4). The necessity for cathodic protection can be tested as in Ref. 13. In tank farms, a distinction should be made between coated, buried storage tanks and aboveground, flat-bottomed tanks in which the base contacts the soil. 

The anode may be installed in conventional groundbeds or be laid in close proximity to the cathode, e.g. parallel to a pipeline route. The anode may be buried either directly in soil or in carbonaceous backfill. The major applications for this material are tank protection, internal protection, mitigation of poor current distribution and hot spot protection, i.e. to supplement conventional cathodic protection systems and provide increased levels of cathodic protection in areas that exhibit low levels of protection. 

Reinforced concrete structures that are fully immersed or buried in a corrosive environment may generally be protected using conventional cathodic... 

As noted above, the electrocarboxylation process has been widely investigated for the production of some NSAIDs, starting from parent arylethyl halides [6, 7]. On the other hand, the direct process at conventional cathodes requires quite negative potentials, and gives rise in some cases to moderate faradic efficiencies. Furthermore, attempts to scale-up the process in the case of the reduction of l-(3-phenoxyphenyl)-l-chloroethane [18] and l-(4-isobutylphenyl)-l-chloroethane [16] (which are the precursors of fenopren and ibuprofen, respectively) gave very different results with respect to those obtained in syntheses performed in bench-scale systems. In particular, passivation of the cathode surface was observed, and this resulted in lower yields and selectivities. Similar results were also observed during the electrocarboxylation of chloroacetonitrile [19]. 

The reductive cleavage of achiral and optically active quaternary phosphonium and arsonium salts with alkali metal amalgams to form tertiary phosphines and arsines succeeds in high yield with retention of configuration [124]. The reduction with the amalgams was found to give better yields than the conventional cathodic cleavage. 

Sign convention cathodic currents are taken to be negative... 

Operation of the nickel matte refining cell is similar to that of the metal anode cell except that the anodes are enclosed in bags to collect the voluminous sludge. The cathodes are placed in conventional cathode compartments. The anode spacing... 

Recently Hamamatsu announced R3809U MCPs with GaAs, GaAsP, and infrared cathodes for up to 1,700 nm. Although these MCPs are not as fast as the versions with conventional cathodes, they might be the ultimate detectors for combined FCS/lifetime experiments and experiments in the infrared. 

Another application of the H7422 is optical tomography with pulsed NIR lasers. Because the measurements are run in vivo it is essential to acquire a large number of photons in a short measurement time. Particularly in the wavelength range above 800 run, the H7422-50 yields a considerably improved efficiency over PMTs with conventional cathodes. 

Conventional cathode materials such as LCD with a single transition metal element are prepared by a simple solid-phase method, in which cobalt acetate and lithium carbonate are calcined at around 900 °C, and consistent product is easily obtained. For materials with multiple transition metal elements like LMO, on the other hand, it is crucial to obtain product composition that is stoichiometrically precise and to obtain the intended crystal structure. Even slight variations can result in widely divergent characteristics when used as cathode material. Strict control of preparation conditions is thus essential for this class of materials. 

In contrast to power stations with small and large pipes, in refineries there are many small pipelines for fire-fighting water, waste water, products, etc. Furthermore, refineries have a large area. Conventional cathodic protection can possibly be used for the small pipelines, but it is actually susceptible to trouble because of possible electrical bridging of the numerous insulating joints required. 

The conventional cathode material is lithiated nickel oxide that is formed by in situ oxidation during cell conditioning. The porosity and thickness are also around 50 % and 1 mm, respectively. The cathode polarization and dissolution/ deposition, which are very important factors of the performance and lifetime, are strongly influenced by the cathode pore structure, electrolyte composition, and operating conditions. The nickel oxide slowly dissolves into the electrolyte as Ni " with an acidic dissolution mechanism as follows ... 

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