Copper ion conductors

In spite of the extraordinarily high ionic conductivity of silver- and copper-ion conductors, these materials suffer from their low capacity and energy density. In addition, only a few positive electrode materials have been found until now. 

Cul) is not due to point defects but to partial occupation of crystallographic sites. The defective structure is sometimes called structural disorder to distinguish it from point defects. There are a large number of vacant sites for the cations to move into. Thus, ionic conductivity is enabled without use of aliovalent dopants. A common feature of both compounds is that they are composed of extremely polarizable ions. This means that the electron cloud surrounding the ions is easily distorted. This makes the passage of a cation past an anion easier. Due to their high ionic conductivity, silver and copper ion conductors can be used as solid electrolytes in solid-state batteries. 

The first solid electrolytes with high copper ion conductivity at room temperature were discovered in 1973. An example is 7CuBrC6Hi2N4CH3Br, whose conductivity at room temperature is 0.017 cm Several other copper ion conductors have since been described. One of these conductors represented by the formula Rb4Cui6l7Cli3 has a conductivity of 0.34 cm at 25°C. This is the solid... 

The use of known solid silver and copper ion conductors in display devices has also been proposed (U9). 

Viswarath, A.K. and Radhakrishna, S., Copper ion conductors, in High Conductivity Solid Ionic Conductors, Takahashi, T, Ed., World Scientific, Singapore, 1989, 280-326. 

In recent years it has been found that these considerations are not merely academic, but constitute necessary and considerable corrections in many important cases. Thus for YBa2Cu30g+x, even at fairly high temperatures, it is necessary to take accoimt of variable valences for the ionic defects this certainly affects the concentration term in Dq and, probably, the conductivity term in Df, too. The situation is similar for mixed conducting copper ion conductors. A more recent example refers to the transport of different valence states of hydrogen in oxides [434]. The literature should be consulted here for more details [187]. 

For example, consider a system in which metallic zinc is immersed in a solution of copper(II) ions. Copper in the solution is replaced by zinc which is dissolved and metallic copper is deposited on the zinc. The entire change of enthalpy in this process is converted to heat. If, however, this reaction is carried out by immersing a zinc rod into a solution of zinc ions and a copper rod into a solution of copper ions and the solutions are brought into contact (e.g. across a porous diaphragm, to prevent mixing), then zinc will pass into the solution of zinc ions and copper will be deposited from the solution of copper ions only when both metals are connected externally by a conductor so that there is a closed circuit. The cell can then carry out work in the external part of the circuit. In the first arrangement, reversible reaction is impossible but it becomes possible in the second, provided that the other conditions for reversibility are fulfilled. 

The thin film behaves like a free electron conductor. It is proposed that there are sufficient copper ions in the thin film to make it fairly conducting. As the film thickness increases, the conductivity of the film decreases at constant potential and consequently the deposition rate decreases. When the film thickness is above 15 microns there is practically no further deposition of the photopolymer film. 

Oxides containing bismuth oxygen atom double layers include the bismuth calcium copper oxide series of superconductors exemplified by Bi2Sr2CaCu20g (Bi-2212) and the beta phase oxide ion conductors based on the composition Sr Big j 0(2 j)/2. While the details of these two stmcture types are quite different, they have the common feature of containing BiMT double layers that are only weakly bonded. In Bi-2212, the bismuth atoms are four + one coordinated by oxygen atoms whereas, in Srj Bi9 j 0(2 j)/2 they are three + one coordinated and form square and hexagonal layers of Bi-O bonds. Both classes of compounds and be intercalated by iodine atoms that are inserted between the Bi-O double layers. 

Copper, however, is used in applications where purity is important. Copper, when pure, is ductile and an excellent electrical conductor, so it needs to be refined to be used in electrical wiring. Copper anodes (blister copper) are suspended in a water solution containing sulfuric acid and copper sulfate with steel cathodes. Electrolysis results in dissolution of copper from the anode and migration of copper ions to the cathode, where purified metal is deposited. The result is copper of 99.9 percent purity. A similar procedure may be used in recycling copper. Other metals that are electrorefined include aluminum. 

Although most substituted pyrogallol[4]arene capsules have quite reasonable stability based on their 72 hydrogen bond network, Atwood showed that they could be further stabilized by replacing the network with various metals. Atwood, Dalgamo, and coworkers explored these compounds extensively and found that only certain elements were appropriate to the formation of these metal organic nanocapsules, or MONCs [21]. One such metal was copper, which we used in developing a membrane-resident ion conductor as described later in this chapter. 

In [56], microprobe studies on the distribution of the elements in the surface layers of the pipes in the experiments [55] demonstrated areas of chloride and sulphate concentration at the metal/surface layer phase boundary. This gives the surface layers semi-conductor properties, leading to partial separation of regions at vhich anodic and cathodic part reactions proceed. As the concentration of copper ions increases, the cathodic part current is increased, so that pitting corrosion is intensified at the anodic regions. 

Figure 9-20. Schematic representations of conductive filaments that cause electrical shorts in printed circuit boards. Left copper ions formed in the acidic environment around the positive conductor migrate toward the negative conductor, and, as they encounter more basic conditions, precipitate to form a conductive filament of copper hydroxide. Right conductive filament formed between plated-through holes by the same process.

In Daniel cell, zinc dissolves and a potential is set up between the zinc ions and zinc metal in the zinc half cell. In the copper half cell, copper ions are deposited on the copper metal and a potential is set up. Once the half cells are in equilibrium, no further deposition or dissolution would occur. If, now, the two half cells are joined by a conductor, as shown in Fig. 2.2, electrons would flow from zinc (anode) to copper (cathode). As a result of electron flow, the equilibrium in the half cells is distributed, and, therefore zinc will dissolve further according to the anodic reaction (oxidation). 

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