Cathode materials dioxides

Manganese dioxide has found wide use in different electrochemical power sources as cathode material. It is known that the structure and properties of manganese dioxide depend on the method of its synthesis. 

The observed higher rate of mass transfer in nonstoichiometric oxides makes it possible to operate at discharge current densities on the order of 2 - 5 mA/cm2, which is several times greater than that used with the conventional manganese dioxide. Thus, the purposeful disordering of structure of a cathode material of manganese dioxide allows to utilize such power sources in extreme conditions - for element discharge at a low... 

Platinum and carbon are frequently used as counter electrode materials for both anode and cathode. Platinum is resistant to corrosion while carbon is cheap and can be discarded after use. Nickel is a suitable counter cathode material in aqueous solution because of the low overpotential for hydrogen evolution. Titanium coated with platinum and then over coated with mthenium dioxide is a stable counter anode material with a low overpotential for oxygen evolution. 

Electrochemical reduction of carbon monoxide in dry nonaqueous media at moderate to low pressures leads to the formation of the 1,3-cyclobutanedione dianion (squarate) at current efficiencies, up to about 45% depending on the cathode material [1,2]. In aqueous solution, electroreduction can lead to the formation of methane and other hydrocarbon products. The role of the metal/adatom in determining the extent of CO and hence hydrocarbon formation during the reduction of carbon dioxide is related to the ability of the electrode material to favor CO formation (Cu, Au, Ag, Zn, Pd, Ga, Ni, and Pt) and stabilize HCCO [3, 4]. 

Primary alkaline cells use sodium hydroxide or potassium hydroxide as tlie electrolyte. They can be made using a variety of chemistries and physical constructions. The alkaline cells of the 1990s are mostly of the limited electrolyte, dry cell type. Most primary alkaline cells are made sing zinc as the anode material a variety of cathode materials can be used. Primary alkaline cells are commonly divided into tW o classes, based on type of construction the larger, cylindrically shaped batteries, and the miniature, button-type cells. Cylindrical alkaline batteries are mainly produced using zinc-manganese dioxide chemistry, although some cylindrical zinc-mercury oxide cells are made. 

Both the lithium sulfur dioxide (Li-SO and lithium thionyl chloride (Li-SOCy cells may be classified as liquid cathode systems. In these systems, S02 and SOCl2 function as solvents for the electrolyte, and as the active materials at the cathode to provide voltage and ampere capacity. As liquids, these solvents permeate the porous carbon cathode material. Lithium metal serves as the anode, and a polymer-bonded porous carbon is the cathode current collector in both systems. Both cells use a Teflon-bonded acetylene black cathode structure with metallic lithium as the anode. The Li-S02 is used in a spirally wound, jelly-roll construction to increase the surface area and improve... 

The cathode material is usually stainless steel, a nickel alloy, or titanium. Graphite, lead dioxide, platinized titanium, and DSA are some of the materials that have been used as an anode. The cells are operated at a current density of between 0.1 and 0.5 A/cm. The majority of the cells used to produce hypochlorite have the parallel-plate type of geometry [81]. 

Li/S02 Cells Lithium/sulfur dioxide cells (Li/SC>2) are perhaps one of the most advanced lithium battery systems. They belong to the soluble cathode cells category. Liquid SO2 is used as cathode a lithium foil is used as anode, and lithium bromide dissolved in acetonitrile is used as electrolyte. The active cathode material is held on an aluminum mesh with... 

Because of the solid cathode material, these cells are used at moderate and low discharge rates. Their primary market is for memory backup applications. They are also used in watches, calculators, cameras, photoflash, motor drives, and toys. Li/manganese dioxide cells have a great performance at moderate and low discharge rates. Other advantages include high cell voltage and excellent storability even at elevated temperatures. Their major... 

Lead-acid batteries were developed in 1859 by Plante. Scientists including Faure, Volk-mar, Brush, Gladstone, Tudor, Phillipart, and Woodward among others, contributed to improve Plante s cell and to create the lead-acid battery designs that are now available in the market. Lead-acid batteries use lead dioxide as cathode material, metallic lead as negative material, and a sulfuric acid solution as electrolyte. Different materials are used as separator, for example, microporous rubber, cellulose, polyvinyl chloride, polyethylene, and glass fiber. The cell reactions are... 

On the other hand, the medical condition where the heart beats too fast is known as tachycardia. If untreated, tliis condition may lead to ventricular fibrillation, that is, a condition in which the heart stops beating and shakes uncontrollably and is usually fatal. In 1980, a special device was developed and implanted in patients. It could sense the condition and provide a shock that would stop the fibrillation and restore the normal sinus rhythm via an electrode sutured onto the heart. The device was first powered by a lithium/vanadium pentoxide system later it was replaced by a system using a cathode material of silver vanadium oxide (SVO or Ag2V40ii). This is the actual system used in modem ICDs (implantable cardioverter/defibrillator). Another material used is the lithium/manganese dioxide system. Also, a new system using a sandwich cathode design with an inner cathode material of carbon monofluoride and an external cathode layer of silver vanadium oxide is in wide use. 

Unlike some other cathode materials, such as manganese dioxide, which are quite insoluble, silver oxide has a fair degree of solubility in alkaline electrolyte. If the soluble silver species were allowed to be transported to the zinc anode it would react directly with the zinc, and as a result the cell would self-discharge. In order to prevent this from happening, zinc—silver oxide cells use special separator materials such as cellophane [9005-81-6], that are designed to inhibit migration of soluble silver to the anode. 

In alkaline Mn02-Zn systems the same electrochemically active materials, manganese dioxide and zinc, are used as in Leclanche cells. The only difference to the latter system is the cathode sleeve construction and the highly conductive KOH electrolyte (7 M 0.55 (Ocm)-l) as already mentioned. The anode is formed of zinc powder instead of a zinc can. Electrolytic manganese dioxide is used for the cathode material. Due to its low polarization and high voltage characteristic it performs far better than chemically produced manganese dioxide or natural ore. 

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