Flat plate cells, lead acid

Flat plate cells are usually made with electrodes spread on screens or grids like lead-acid batteries or industrial Ni-Cd batteries. In these types of batteries the electrodes itself are good metallic conductors To build manganese dioxide batteries as plate cells good conductive screens would be needed. A well known example for a bipolar Mn02-Zn cell in commercial production is the 6 Volt Polaroid camera film battery, a primary battery with a weakly acidic electrolyte. 

Flat plate and tubular positive plate cells are produced for stationary duty, but where reliability is a prime consideration, Plante cells are used. In a Plants cell, the positive electrodes are manufactured by a quite different process. The oxide is formed by electrochemical oxidation (say, 10 mA cm for 20 h) of a lead baseplate or grid, often shaped to increase its surface area, in an electrolyte which contains sulphuric acid and an anion (perchlorate or nitrate) wliich forms a soluble Pb " salt. This leads to a layer of thick porous oxide the nitrate or perchlorate is present to prevent total passivation of the lead surface. The resulting plate, thickness 6—12 mm, is then reduced to form spongy lead metal, is washed thoroughly, and is recharged when in a fabricated cell. The active material formed in this way adheres to the base lead better than pasted materials and therefore cycles more reUably. Against this, there is less active material on each plate and, inevitably, the energy density of the battery will suffer 7—12 Wh kg is typical. 

Figure 2.6 Useable fraction of the energy/weight ratio in Wh/kg of lead acid PzS cells, PzF cells, and GF cells (GF = flat plate type).

FIGURE 24,5 Exploded view of typical thin, flat sealed lead-acid cell. Metal plates, each approximately 0.3 mm thick, are laminated with special resin films to negative and positive electrode plates, both physically and electrically. They are then fused to a resin frame by a pressurized thermal bonding process. ( Courtesy of Panasonic Industrial Co.)... 

Flat-plate and tubular-positive plate cells are produced for stationary duty, but where reliability is a prime consideration, Plante cells are used. In a Plante cell, the positive electrodes are manufactured by a quite different process. The oxide is formed by electrochemical oxidation (say, 10 mA cm " for 20 h) of a lead baseplate or grid, often shaped to increase its surface area, in an electrolyte which contains sulphuric acid and an anion (perchlorate or nitrate) which forms a... 

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