Copper oxide cell

Copper oxide cell Consists of Zn anode and CuO as cathode with alkaline electrolyte Zn + OH + CuO —> Cu + HZnO 2... 

The lithium-copper oxide cell is voltage compatible (OCV = 1.5 V), i.e. it may be used as a direct replacement for conventional Leclanche or alkaline zinc cells. CuO has a particularly high volumetric capacity (4.2 Ah/cm3) so that cells are characterized by high specific energy -300 Wh/kg (700 Wh/dm3). The discharge curve shows a single step which may be attributed to the simple displacement reaction ... 

The lithium-copper oxyphosphate cell has similar features to the lithium-copper oxide cell, but has a somewhat higher voltage. The cell reaction is written as... 

The lithium-copper oxide cells used in this investigation were made by SAFT and had a type specification LCOl. Each cell has a negative electrode of lithium metal, an electrolyte of lithium perchlorate in an organic solvent and a positive electrode of copper oxide and carbon. The cell is constructed in the form of a hollow tubular lithium central cylinder which is separated by a thin annular synthetic material from a concentric tubular copper oxide-carbon ring matrix enclosed by an outer steel can. Current collectors are attached to the lithium and steel cylinders. 

Table 9.10 Characteristics of lithium-copper oxide cells...

Figure 30.23 shows a performance comparison of a lithium-copper oxide cell which has been stored at desert temperatures for 5 years (solid line) against that of a new cell (dashed line). 

Figure 30.23 SAFT lithium-copper oxide cells voltage-time shelf-life curves (Courtesyof SAFT)...

Figure30.56 1, SAFT LC01 1.5 V (3.6Ah) lithium-copper oxide cell 2, alkaline K6 zinc-manganese dioxide cell. Capacity versus discharge current at various operating temperatures. The superiority of the lithium-copper oxide couple at low drain is evident (Courtesy...

Bobbin and eylindrieal eell formats are available from Saft. Other suppliers of lithium-copper oxide cells include Eagle Picher and Sanyo (Japan) (button cells). 

The cylindrical cells supplied by SAFT have an open-circuit voltage of 2.8 V and a nominal voltage of 2.8 V, as opposed to the 1.5 V nominal voltage available from lithium-copper oxide cells. These cells are designed to operate at temperatures up to 175°C with high reliability. Details of the available range of these cells are supplied in Table 56.19. 

Copper oxide cells are reliable and fairly cheap, and are widely used as wet cells. The cathodes are porous plates of copper oxide mixed with a suitable binder, the anodes are of zinc and the electrolyte is a concentrated sodium hydroxide solution. Zinc ions from the anode react to give zincate ions, and copper oxide is reduced at the cathode ... 

The earliest cell to be widely used was the Daniell cell. The disadvantages of employing two electrolytes are obvious, and these are avoided in the Leclanche cell, on which are based the majority of dry cells (see dry cell). Other cells with special uses are the mercury cell (q.v.), the copper oxide cell (q.v.), the silver-zinc cell (q.v.), the zinc-air cell (q.v.) and the chloride cell (q.v.). These cells all vary in the cathode reaction but all have zinc anodes, although magnesium is a promising alternative. 

The zinc-air cell employs a zinc anode and a porous cathode of active carbon which is shaped to give a large area of exposure to the air. The electrolyte is sodium or potassium hydroxide. The reactions are similar to those of the copper oxide cell (q.v.), with oxygen from the air replacing CuO as the active cathode material. The electrode reactions are... 

There are many methods of fabricating the electrodes for these cell systems. The eadiest commercially successhil developments used nickel hydroxide [12054-48-7] Ni(OH)2, positive electrodes. These electrodes are commonly called nickel electrodes, disregarding the actual chemical composition. Alkaline cells using the copper oxide—2inc couple preceeded nickel batteries but the CuO system never functioned well as a secondary battery. It was, however, commercially available for many years as a primary battery (see BatterieS-PRIMARY cells). 

By 1927, another metal semiconductor junction solar-cell (In this case made of copper and the semiconductor copper oxide), had been... 

Then add the copper half-cell reduction to the zinc half-cell oxidation and add the half-cell potentials ... 

Additionally, reduction would occur in the copper half cell in accompaniment with the zinc oxidation ... 

One more example demonstrates how to use standard reduction potentials to determine the standard potential of a cell. Let s say you wanted to construct a cell using silver and zinc. This cell resembles the Daniell cell of the previous example except that a silver electrode is substituted for the copper electrode and a silver nitrate solution is used in place of copper sulfate. From Table 14.2, it is determined that when silver and copper interact silver is reduced and copper oxidized. The two relevant reactions are... 

La2Cu04, Sr2Cu04. As we show in chapter 6, when a perovskite forms a composite or intergrowth with other structures, new compounds of interest in catalysis can be formed (such as in high-temperature superconducting copper oxides) and EM is used to determine the structures and properties of these complex compounds. The merits of using perovskites in steam reforming, membrane catalysis and fuel cells are discussed in chapter 6. 

For ethanol and 1-propanol the oxidation at copper oxide electrodes gives similar yields as at the nickel hydroxide electrode However, for 1-butanol the yields are already less satisfactory (copper oxide 77%, 25 °C silver oxide 26%, 25 Copper and silver anodes tend to corrode in alkaline medium, which, however, may be limited by the use of a divided cell... 

Fig. 4.23 Discharge curves of lithium-copper oxide button cells (LC 01) after accelerated shelf testing at 70°C (a) fresh cell (b) after 6 months at 70°C (c) after 12 months at 70°C (d) after Jfi months at 70°C, (By courtesy of SAFT Gipelec.)...

Fig. 4. 25 Comparison of discharge curves at ambient temperature of voltage-compatible lithium-copper oxide button cells and conventional aqueous cells (a) lithium-copper oxide (b) alkaline manganese (c) zinc-silver oxide. Load = 75 k i...

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