Industrial anode materials

Over- voltage range Anode material Electrolyte compo- sition Molarity (C/mol.dm ) Tempe- rature (T/°C) Anodic Tafel slope (fe/mV.logJ ) Exchange current densi decimal logarithm (log,j /A.cm ) Overvoltage at 200 A.m (mV) 

Over- Anode Electrolyte Molarity Tempera- Anodic Exchange Anodic 

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Refractories in the Aluminum Industry. Carbon materials are used in the HaH-Heroult primary aluminum cell as anodes, cathodes, and sidewalls because of the need to withstand the corrosive action of the molten fluorides used in the process (see Aluminumand aluminum alloys). 

Zinc was also already in use for protection in seawater in 1824 (see Section 1.3). In the beginning zinc material that was available from the hot-dip galvanizing industry was used but was less suitable because it became passive. Passivation does not occur with high-purity zinc. Super high grade zinc is the anode material with the least problems [5] and consists of 99.995% Zn and less than 0.0014% Fe without further additions. It is specified in Ref. 6 and permitted by the German Navy [7]. The most important properties of pure zinc are listed in Table 6-1. 

Ru02 is an important electrode material for industrial anodic processes. Special attention is deserved by the so-called dimensionally stable anodes (DSA) invented by H. B. Beer in 1968. These are formed by a layer of a microcrystalline mixture of Ti02 and Ru02 (crystallite size less thn 0.1 jum) on a titanium support (Fig. 5.26). This material is suitable as anode for chlorine and oxygen evolution at high current densities. For industrial chlorine production, it replaced the previously used graphite anodes. These... 

Subcategory A encompasses the manufacture of all batteries in which cadmium is the reactive anode material. Cadmium anode batteries currently manufactured are based on nickel-cadmium, silver-cadmium, and mercury-cadmium couples (Table 32.1). The manufacture of cadmium anode batteries uses various raw materials, which comprises cadmium or cadmium salts (mainly nitrates and oxides) to produce cell cathodes nickel powder and either nickel or nickel-plated steel screen to make the electrode support structures nylon and polypropylene, for use in manufacturing the cell separators and either sodium or potassium hydroxide, for use as process chemicals and as the cell electrolyte. Cobalt salts may be added to some electrodes. Batteries of this subcategory are predominantly rechargeable and find application in calculators, cell phones, laptops, and other portable electronic devices, in addition to a variety of industrial applications.1-4 A typical example is the nickel-cadmium battery described below. 

In nonaqueous media, carbon (graphite) frequently is an optimal anode material, for example, for methoxylation reactions, even in an industrial scale (capillary gap cell, see Fig. 12). It shows an appreciable overvoltage for the oxidation of methanol compared to platinum. 

Ceramic Materials An example of a sufficiently conductive metal oxide is magnetite Fe304, which has been used, for example, in the past as corrosion resistant anode material for industrial chlorine evolution (it can be smelted and casted at 1500 °C, but it is a very brittle material). 

The search for new anode materials that satisfy the requirements of commercial lithium ion batteries has been a long-standing challenge in industrial and academic research. 

When mercury-arc rectifiers were first introduced into industry some time ago many difficulties arose due to so called backfiring this phenomenon is caused by one anode suddenly starting to work as a cathode and so giving rise to a double short circuit. This was overcome by taking meticulous care to see that the anode material was kept free of any impurities capable of emitting electrons. 

Ruthenium dioxide-based materials represent the catalyst for the industrial anodic production of chlorine. There is no doubt that, in the case of dimensionally stable anodes (DSA ), the technological innovation was adopted by industry [21] a few... 

Metalhc hthium has a variety of uses. It is used as an anode material in batteries and as a heat transfer agent. Magnesium-hthium alloys are used to produce armor plate and aerospace materials, while aluminum-hthium alloys find applications in the aircraft industry. Lithium is also used to produce chemical reagents such as LiAlH4 (a reducing agent) and n-butyhthium (a strong base). 

In addition to the well-known application of cathodic corrosion protection to underground pipelines, there has been an increased use for the internal protection of containers and pipes. Initially, galvanic anodes were used to this effect, like the ones currently used, for example, to protect the interiors of tankers and boilers. However, since these anodes are often subject to heavy inherent corrosion, especially with the highly aggressive media often found in the chemical industry, they have largely been replaced by external current systems with insoluble anode material. 

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