Cell Design and Assembly

Like many other in situ coupled techniques, the ideal experimental conditions for the collection of specularly reflected neutrons are not ideal for maintaining electrochemical control. This mandates the improvisation of new cell designs. As detailed above, measurements performed in the presence of electrolyte should use an inverted cell geometry. The cell needs to be constructed so that the neutrons 

The major difficulty in cell design for in situ electrochemistry-NR studies is that 

2) The working electrode should be constructed out of a pure material, ideally a single crystal. 

3) The reference electrode should be electrically connected to the cell via high ionic conductivity. 

5) An inert atmosphere to remove faradaic current arising from dissolved oxygen in the electrolyte. 

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Li metal served as a reference electrode and a IM-LiClO propylene carbonate solution was used as an electrolyte. Purification of the chemicals used and cell design and assembly were as previously reported (2). 

Four main aspects are addressed in turn (i) neutron sources and reflectometer operation (ii) choice of substrate, substrate preparation, and characterization (iii) cell design and assembly and (iv) data acquisition and analysis. 

This chapter is intended to provide an overview of the varions aspects of manufacturing lithium-ion (Li-Ion) cells. While the basic principles of cell design and manufacture are well known, each manufacturer maintains proprietary, specific details of their cell designs and assembly and the equipment used in cell fabrication. Nonetheless, the overall principles and processes involved are detailed below. Figure 8.1 shows a schematic of the components of a cell (battery). 

SINGLE CELL DESIGN AND ASSEMBLY 2.6.1. Single Cell Hardware... 

Degradation and durability of a PEM fuel cell or stack can be affected by many internal and external factors, including fuel cell design and assembly, operating conditions (e.g. humidification, temperature, cell voltage), impurities or contaminants in the feeds, environmental conditions (e.g. subffeezing or cold start), and operation modes (e.g. startup, shutdown, potential cycling). 

We wish to thank R. O. Billman for his assistance in designing and assembling the XAS controlled atmosphere cell and the XPS catalyst treatment system. I. Y. Chan did the TEM and SEM experiments. 

In contrast to stationary applications, portable applications require frequent start and stop procedures. Therefore for SOFC, a robust cell design and adapted electrode-electrolyte assemblies are an important issue. Frequent thermal cycles between room temperature and an operation temperature of about 600-800 °C pose challenges to the layered system consisting of solid anode, ceranfic electrolyte and solid cathode with respect to thermal and mechanical stability. For several years, different approaches to developing tubular nficro SOFC have been undertaken but did not lead to a commercial product yet. As SOFC can be operated with pure hydrogen, reformate and hydrocarbons as fuel as well - the latter option means direct internal reforming at the anode catalyst — various investigations focused on reduced operation temperature and a parallel conversion of fuels [21]. 

Gold nanoparticles have also been chosen due to their high electronic conductivity, their thermod5mamically stable interface with C03O4, and the potential to catalyze electrochemical reactions at the nanoscale. Belcher et al. propose hybrid gold-cobalt oxide wires prepared by a virus-templated synthesis. The cell delivered 94% of its theoretical capacity at a rate of 1.12 C and 65% at a rate of 5.19 C. Thus, the authors evidenced that nanoscale battery components can be designed and assembled on the basis of biological principles [54]. 

STACK DESIGN AND ASSEMBLY 2.7.1. Hardware of a Fuel Cell Stack... 

The design and assembly of PEM fuel cell components, such as flow fields and manifolds, can have a significant influence on water management and feed flows, which will in mrn affect the durability of fuel ceU components. For example, an improper design of the flow fields can result in water blockage, and improper manifold design can induce poor cell-to-cell flow distribution, both of which may cause localized fuel starvation. This localized fuel starvation can then induce an increased local anode potential to levels at which carbon oxidation or even water electrolysis may occur to provide the required protons and electrons for the oxygen reduction reaction (ORR) at the cathode. These reactions will induce corrosion of the carbon support and will result in a permanent loss of electrochemically active area at the anode. 

Depending on cell design and construction, the sealing material can come into contact with the catalyst layer of the membrane electrode assembly in these cases care must be taken that the material does not contain any substances which in the presence of the catalyst lead to unwanted side reactions. The sealing materials must neither contain any components which can act as catalyst poisons which will contaminate and thus deactivate the electrocatalyst, leading to reduced cell efficiency. 

In an alternative procedure designed to deal with minute volumes of liquid, Walter38 set up a layer cell based upon the technique employed in instant colour photographic films, Such a cell designed to determine potassium ions made use of two layer assemblies terminating in valinomycin electrodes, so that with a standard potassium chloride solution added to one assembly, and the... 

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