Tubular positive plates

Positive plates Tubular plates Flat pasted plates Flat pasted plates... 

The tubular positive plate uses rigid, porous fiber glass tubes covered with a perforated plastic foil as the active material retainer (Fig. 2). Dry lead oxide, PbO, and red lead, Pb O, are typically shaken into the tubes which are threaded over the grid spines. The open end is then sealed by a polyethylene bar. Patents describe a procedure for making a type of tube for the tubular positive plate (90) and a method for filling tubular plates of lead—acid batteries (91). Tubular positive plates are pickled by soaking in a sulfate solution and are then cured. Some proceed directiy to formation and do not requite the curing procedure. 

The production of tubular positive plates is in principle similar to that of pasted plates. A number of manufacturers use the same gray oxide as the basic filling substance. Sometimes the share or red lead or minium (Pb304) is increased above 25 or even to 100wt.%. The latter is more economic when the manufacturer runs his own minium plant then the expense of the chemical oxidation of lead oxide (PbO) to minium (Pb304) may be compensated by reduced formation cost. Furthermore, curing is not required, because of the high oxidation state, and the battery starts with full capacity when formed. 

For vehicles used in rugged terrain, batteries with tubular positive plates are required. As discussed above, SLI batteries are sometimes supplied in a dry charged state, especially for markets where a long shelf life is needed. 

Fig. 5.13 Motive power lead-acid cell with tubular positive plates in which the active material is contained in pre-formed terylene tubes, and negative pasted grid plates surrounded by microporous polyvinyl chloride separator envelopes. The case and lid are formed of heat-sealed polypropylene. (By courtesy of Chloride Industrial Batteries.)...

Fig. l.l. (a) Gaston Plante s cell and battery (b) flat plate (c) tubular positive plate (d) spiral-wound cell. 

FMl. Positive-plate expansion. The use of lead-antimony alloy enhances the creep strength of the positive grid and thus retards growth in the plane of the plate. For the flat design of positive plate, expansion normal to the plate can be moderated by applying a compressive force to the plate group. Tubular positive plates have gauntlets that constrain the active material and reduce its tendency to expand, disconnect, and shed. 

It has been established that on cycling of tubular positive plates with die-cut strap grids (SGTP) or of positive plates with expanded grids with flat ribs, a rapid capacity loss is observed (the PCL-1 effect, see Section 2.3, Chapter 2 and Chapter 9) [54]. The reason for this capacity loss is the formation of groups of PbS04 crystals in the layer of the PAM that contacts the current-collector (Fig. 3.39). These PbS04... 

Fig. 3.4L Capacity curves for strap grid tubular positive plates (SGTP) (a) cast strap grids with smooth surface (b) die-cut strap grids with smooth surface (PCL-1 effect) (c) die-cut strap grids with rough surface obtained after reverse-current treatment prior to formation proper [54].

Tubular plates have been made with chemically prepared lead dioxide and 2.2 or 3.8wt.% sodium sulfate in the positive active-material [44]. Test results on cells cycled at constant-current are shown in Table 4.7. It was concluded that sodium sulfate increases the utilization of material by dissolving to create a more porous structure in the positive plate. It was also noted that graphite has an even greater effect in the same concentration range (see Section 4.4.7). 

The 7-MWh battery consisted of two parallel strings, each of 200 cells with an individual capacity of 9000 Ah. The cells had tubular positive plates and copper... 

This chapter provides an overview of stationary battery applications and presents the different battery types that are currently used, focusing especially on valve-regulated designs. Batteries with capacities of up to about 200 Ah usually have flat positive plates for higher capacities, tubular designs are also used. 

Gravity casting of grids is usually employed for the manufacture of flat positive plates. Flat positive lead-calcium-tin grids are more sensitive and more prone to corrosion than tubular grids. Nevertheless, it must be pointed out that even for batteries with flat positive plates, corrosion has been only one of the limiting factors during standby applications. 

For gel batteries, both tubular and flat positive plates are used. Gel cells with tall plates often have the tubular positives design although there are some with flat positives. Gel cells with small plates, in general, have flat positives, however, a few exceptions will have tubular positives. In comparison with the AGM design, gel batteries have a markedly higher internal electric resistance. This is a clear disadvantage for all high-power applications. 

Sonnenschein was the first company to introduce gel battery technology to the market successfully. They started in 1958 with rather small batteries for flashlights. Since that time, this technology has steadily replaced the conventional, flooded lead-acid battery in various applications [38,71,72]. Phosphoric acid addition for cycling was first introduced in 1965. Larger gel batteries with tubular positive plates were developed for stationary applications in 1978. More recently, gel batteries have been produced for starter and traction applications, and thick, flat positive plates were added for telecommunications applications. 

OCSM cells with tubular positive plates and copper negative grids have been used successfully for various stationary applications. In 1986, for example, a... 

Purpose-built batteries. Gel batteries with either tubular plates or thick, flat plates (> 5 mm) are recommended when a long cycle-life is required. Both designs have a high level of resistance to positive-plate degradation, and can tolerate high levels of positive-grid corrosion. 

Many manufacturers around the world offer tubular-plate gel batteries for heavy-duty RAPS operations. As the name suggests, the batteries have tubes that contain the plate material. This design is employed only for the positive plates, as these are... 

The same year, Ernest Volckmar replaced the lead sheet with lead grid [13] and Scudamore Sellon [7] used lead—antimony grids instead of pure lead grids. S.C. Curie devised tubular positive plates for lead—acid batteries. 

The tubular-plate technology is used in the manufacture of traction and stationary batteries. Figure 2.53 shows die main stages involved in the classical production process of mbular plates. Only the preparation of positive plates will be described briefly, since the other technological stages are identical to those discussed for flat-plate batteries. 

A further advantage is that flie spine is coated with a layer of active material which protects it from corrosion. It has been experimentally established that tubular positive plates with 4—mm-diameter spines can complete 1500 charge/deep-discharge cycles, whereas flat-pasted plates with grids of the same thickness endure only 800 cycles before corrosive attack causes failure. 

When more than 80 wt% Pb304 vs. the total paste amount is used for paste preparation, the formed PAM contains mostly P-Pb02- Such a structure of PAM is rather brittle and easily disintegrates, which shortens the life of the battery substantially. Therefore, the use of high percent loads of Pb304 in the paste is acceptable only for tubular positive plates, where PAM is enclosed in tubes. 

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. 

Tubular positive plates are sometimes used in batteries for deep-discharge applications to reduce shedding of electro-active materials from the plate during cycling. The positive electrode has intercoimected porous tubes that are filled with positive lead paste. Lead rods in the centers of tubes are connected in parallel by a conductive lead bar at the top, and the bar is connected to the positive terminal. 

Tubular batteries have flat negative plates opposing the positive tubular plates. Recent approaches to preventing positive plate shedding with improved separator designs have limited the use of tubular positive plate batteries. They are primarily in applications that have deep-discharges or severe vibration. 

Ftat plate and tubular-positive plate cells arc produced for stationary duty, but where reliability is a prime consideration, Plante cells are used. In a Planti cell, the positive electrodes are manufactured by a quite difTerent process. The oxide is formed by clectrochemica] oxidation (say, 10 mA cm for 20 h) of a lead... 

Lead acid with tubular positive plates (Varta PzS), 500 Ah. Heat generation values referred to 100 Ah of nominal capacity. The figures in the bottom part represent heat generation in total. The sum of the whole charging period amounts to 28.7Wh/100 Ah. Internal resistance 4.5 mQ per 100 Ah of nominal capacity. 

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