Cathode multi-layered

Computational modelling of cathodic protection systems for pipelines in multi-layer soil... 

Keywords cathodic protection, multi-layer, Boundary Element Method, transmission pipelines. 

Andres B Peratta, John M W Baynham, and Robert A. Adey. Advances In Cathodic Protection Modelling of Deep Well Casings In Multi-Layered Media. CORROSION 2009, Paper 6555 Atlanta, Georgia. NACE International 2009. 

Dense electrolytes with a thickness of 3 pm have been deposited on warm-pressed anode substrates by a graded multi-layer sol-gel coating method. By applying a LSCF cathode, current density of about 840 mA/cm and power density of 588 mW/cm has been realized. It could be demonstrated that it is possible to produce highly dense YSZ electrolyte for SOFC application via sol-gel route. Enhanced electrochemical performances of single cells are expected in the future work through optimizations of fabrication procedures. 

Electrodes and cell components must be thin to minimise the internal resistance of the batteries the total cell can be less than 0.2 mm thick. Figure 12.11 shows the construction of a multi-layer film, rechargeable lithium polymer battery, using a solid polymer electrolyte. A thin lithium metal foil acts as an anode. The electrolyte is polyethylene oxide containing a lithium salt, and the cathode is a composite of the electrolyte and a... 

Oxygen and nitrogen from air as well as water vapor are diffusing to the electrochemical interface, the cathode catalyst layer, where in a multi-step process oxygen picks up four electrons from the electrode and four protons from the electrolyte to form water. 

P. Holtappels and C. Bagger. Fabrication and performance of advanced multi-layer SOFC cathodes. J. European Cerm. Soc. 22, (2002) 41 8. 

Seigel et al. [51] developed a multi-phase, two-dimensional model. The model was a two-dimensional steady state model, which studied transport limitations due to water build up in the cathode catalyst region. They considered water in three phases liquid, gas and dissolved (membrane phase). They found that treating the catalyst layer as a very thin interface imderestimates the transport limitations due to water build-up. Hence, they modeled the catalyst layer as a finite region. Their model showed that 20-40% of the water building up at the cathode catalyst layer comes fi om water which is transported across the membrane. This problem may be coimteracted by applying a pressure differential to force back diffusion of water, i.e., from cathode to anode. 

Multi-layer configuration for the cathode electrode of polymer electrolyte fuel cell. Electrochim. Acta, 55, 4579-4586. 

Yoon YG, Yang TH, Park GG, Lee WY, Kim CS. A multi-layer structured cathode for the PEMFC. J Power Sources 2003 118 189-92. 

Besides Debe s electrode, Tang et al. [61] produeed a carbon nanotube thin film with ultra-low Pt loading (Pt on multi-walled carbon nanotubes (MWNTs)) through a polycarbonate filtration membrane. Compared to the results presented by both Los Alamos National Lab (LANL) and 3M Corporation, as shown in Figure 19.12, this thin-film cathode catalyst layer with a loading of 6 pg Pt/cm could give a mass activity of 250 A/mg Pt, which is the highest activity reported so far. 

Fig. 5. The dependence of NO conversion on the value of the current for electrochemical reactors with functional multi-layer electrodes (- - 2% and -o- 10% of oxygen) and for a reactor with a monolayer electro-catalytic electrode (- - 2% of oxygen) and a traditional type of electrochemical cell with Pt-YSZ types of cathode (-A- 2% of oxygen).

The cathode is a dense Pt(55vol%)-YSZ(45vol%) composite with a thickness of about 2-3 jjtl The nano- porous NiO-YSZ electro-catalytic electrode with a thickness of about 6-8 )xm was deposited over the cathode. The porous YSZ layer with a thickness of about 2-3 )xm was deposited over the cathode. It is seen that the multi-layer electrode consists from three main fimctional layers 1. Cathode 2. Electro-catalytic electrode 3. Covering layer. 

Fig. 8. SEM images of the cross-section of the multi-layer cells with different YSZ-Pt cathode compositions (a - 15vol% of YSZ, b - 25vol% of YSZ, c - 35vol% of YSZ, d - 45vol% of YSZ).

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