Grid alloy composition

C/5 capacity i/s. cycle number during the TC-69 cycling test at 100% depth of discharge for batteries with lead—calcium—tin—silver grids. The grid alloy compositions are presented in Table 4.5 [83]. 

Influence of grid alloy composition on expander efficiency [22]... 

In order to evaluate the effect of grid alloy composition on expander action, two series of batteries were assembled with PbSb or PbSnCa grids, but with different amount of phenolic... 

If thermopassivation is a result of changes in composition of the corrosion layer, then the grid alloy composition will affect the semiconductor properties of the oxides in this layer through the dopants formed as a result of oxidation of the grid alloying additives. The latter s ions will modify the electrical properties of the oxides in the corrosion layer (Table 13.1) [5,6]. 

Grid Alloy Composition Plate Drying Temperature (°C) Duration of Drying (min) Cathodic Thermopassivation (mV) Reference... 

Positive grid corrosion. The oxygen evolved on the positive plates penetrates through the interface grid/active material and oxidizes the lead alloy of the positive grid (see Chapter 2.11, p. 91). The rate of this process depends on grid alloy composition, cell temperature, positive plate potential and battery duty. 

The rates of the self-discharge reactions also depend on temperature, additives to the active mass, electrolyte formulation, and grid alloy composition. As the surface of the electrodes is covered by PbS04 (the product of the self-discharge reactions), the state of charge of the electrodes begins to affect the rate of the self-discharge process. 

Corrosion of the positive grid [Eq. (28)1 occurs equivalent to about 1 mA/lOOAh at open-circuit voltage and intact passivation layer. It depends on electrode potential, and is at minimum about 40-80mV above the PbS04/Pb02 equilibrium potential. The corrosion rate depends furthermore to some extent on alloy composition and is increased with high anti-monial alloys,... 

As positive grid corrosion is an important influence on the expected lifetime of standby batteries, there have been many investigations of the parameters that influence the corrosion rate. It has been established that many parameters influence grid corrosion and growth. The most important are (i) alloy composition (ii) grid design (iii) casting conditions (iv) positive active material (v) impurities that accelerate corrosion (vi) battery temperature and (vii) potential of the positive plate. 

The quality of cast grids depends on the temperature regimen during casting and on alloy composition and crystallization. The process conditions should be adjusted to the specific alloy composition and grid design. 

Segregation of Sn and Ca advances from the bulk grid alloy towards its siirface. This process has been studied by examining the elemental composition of the grid surface layer (10 nm thick) by X-ray photoelectron spectroscopy (XPS) and that in the bulk grid alloy by atomic absorption spectroscopy (AAS) [16]. 

Table3.1-289 Currently preferred compositions of automotive battery-grid alloys [1.307]...

The rate of grid corrosion is influenced by the composition of the grid alloy and the manufacturing process. Selection of appropriate alloying additives is important to reach the desired service fife. 

Figure 9.3 shows examples of basic grid structures which carry the active masses, with examples of size and the alloy composition. Metallurgists describe the characteristics of alloys made out of different metals by phases or temperature/ concentration diagrams. Within these, the formed phases are located metal components of different constitutions and physical condition are described depending upon the composition and temperature. 

Positive grid corrosion can be caused by the grid alloy, grid casting conditions, and active material composition. Shedding of positive active material can be caused by battery construction, active material structure, battery cycles, DOD, and charge... 

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