SU44501A1 - Method of making material for active masses, especially lead acid batteries - Google Patents

Description

A common method for making lead-acid plates is that pasta is first prepared from glaze and red lead, and then it is put in a wet form into a lattice-shaped and solid base, which also serves as a current conductor. In view of the fact that the paste forms a body after drying, the internal structure of which has an excessive density, more pore-forming substances are often added to it. By reduction in one case and by oxidation in the other, by means of electrolysis of the active mass enclosed in the base, then spongy lead of the negative plate is obtained and lead peroxide is positive.

Such still-used lead elements have many disadvantages; for example,

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The lead base of electrodes only takes part in the electrochemical process to an insignificant degree, at the same time this base, in view of the fact that it must be very massive, significantly increases the already large weight of the element, which in turn makes it necessary to use for the element massive vessels and the further increase in weight. The lack of elasticity of the substrate leads, over time, to an increasingly noticeable weakening of its adhesion to the active mass, which is subject to the phenomena of expansion and contraction. The proximity of lead to lead peroxide on the surface of the positive electrode leads to a rapid self-discharge. Electrodes should be formed, since they only after repeated charging and discharging acquire their full capacity. These drawbacks of conventional lead-acid batteries made them non-profitable as primary cells and significantly limited their use as secondary cells.

Numerous proposals have already been made to eliminate these and other disadvantages of conventional portable elements. These proposals set themselves for the most part as a goal — altogether eliminate the need for a framework. Thus, it was proposed that the usual material from which electrodes for lead accumulators are made, by pressing, be shaped into a plate, and embed a metallic conductor for current into them. It was pointed out that lead peroxide could be used in a material for the manufacture of lead battery plates, as well as lead dust consumption. The results achieved, however, cannot be considered satisfactory.

The inventor has found in a special lead compound a new material, the use of which, with the appropriate method of manufacture, makes it possible to obtain a new type of lead elements.

A known method for producing lead peroxide is obtained by treating red lead with hot nitric acid. The black powder that falls out is lead peroxide. On the contrary, it has until now been known that if minium is exposed to diluted nitric acid and the process is interrupted before a general lead peroxide is formed in general or in a significant amount, then another strong brown lead compound is obtained. Received. after washing the precipitate, the brown powder is a new material that can be obtained, for example, by the described method. In most cases, a new substance contains, as a result of too early or too late termination of the process, either red lead residues, or already formed lead peroxide. In most cases, it is impossible to interrupt the process at exactly the right moment. Practice has confirmed this observation. Small impurities of this kind, however, do not in any way reduce the possibility of using a new material for the manufacture of electrodes from it.

As an example of the production process of the new material, we give the following: 100 g of red lead are stirred up together with 333 cm of distilled water, 6QO cm of nitric acid with a specific weight of 1.4 is diluted at 840 s / h of water. Each liquid, when poured together, must have a temperature of 24 °. After 50 minutes, the process is interrupted and the resulting brown precipitate is washed.

The material manufactured in this way according to the invention usually has a specific gravity lower than 7, generally less than 8, while the specific gravity of common commercially available lead peroxide always exceeds 8. Further criteria can also be given: if measured The volume of 10 g of new matter with the aid of Chancel sulfurimeter showing cubic centimeters on the air, and if the substance is stirred up with ether in such a way that it is completely saturated with it, then we find after the sulfurimeter that the substance is leaking A certain time period quickly settles, after which the sedimentation suddenly changes its character and is made much less noticeable. At this point, the height of the substance in the sulphurimeter is counted and the resulting number is multiplied by 10 to get a value for 100 i. This count will be hereinafter referred to as the Immediate Count. The amount of 100 g of sediment measured in ether, for immediate counting, is usually more than 100 cm for a new substance, while for ordinary lead peroxide it is less than 75 cm.

The oxygen content of lead peroxide, calculated from PbOg, is approximately 99%, in a new substance, approximately 93%. The electrical resistance of a cube with an edge length of 1 cm at a pressure of 100 kg is more than 0.5 ohm for lead peroxide, for a new substance less than 0.2 ohm. By its chemical composition, new material can be skag

approaching lead peroxide hydrate. The above-described lead compound has not yet been used for the manufacture of electric batteries, in particular for lead ones, although such a substance could sometimes be produced during the operation of the cell. In the manufacture of electrodes for lead elements using a new material, it is possible to use conventional manufacturing processes, which is not an outcome of the invention.

First of all, however, the new material makes it possible, under suitable conditions, to prepare electrodes from mass alone without a rigid base, which, compared to conventional lead plates of batteries, are much more productive, and not only in terms of the weight of the entire plate, but and based on the weight of the active mass alone.

In the manufacture of positive electrodes for lead elements from mass alone, the following method can be used, for example. The powdered, air-dried mixture of lead compounds commonly used in the preparation of electrodes for lead elements is combined with a new material and pressed around a metal conductor, after which the compacted object is treated with diluted sulfuric acid, while as far as possible when the acid inside the compacted body and the acid surrounding it does not reach the same density, at least, however, for 10 minutes. After that, the pressed product is dried. A metallic conductor embedded in an electrode, in view of the fact that it should not serve as a rigid foundation for the active mass, but serves solely to distribute the current within the active mass, can have very small dimensions and also be flexible. The finished electrode itself has sufficient strength. Thus prepared, consisting of one mass, the positive electrodes are lighter and smaller than the well-known positive plates of the same capacity. They do not need a special manufacturer-made formation and have only a weak tendency to self-discharge. It is not difficult to establish cheap mass production, including very small and thin copies.

Two relevant illustrative examples for the manufacture of positive electrodes constructed using the method described above show substantially the following composition of basic substances.

Example 1. 30% sponge, lead (mostly with adherent; sulfuric acid, dried in the manner described below), 40Vo brown oxide — a term for a new material, the preparation method of which is described above, 30%. little red lead.

Example 2. 30 / about PbO, 40Uo brown oxide, prepared as described above, 30 / about the red lead.

In both cases, the pressing pressure is 250 kg per 1 cm, while the plate, if it is 1.5 mm thick, should be cured in a solution of sulfuric acid with a specific gravity of 1.18 for about half an hour. The time required to solidify the plate thus depends on its thickness. It should be noted that the density of the sulfuric acid solution used to harden the plate is approximately equal to the density of electrolytes used in lead elements. The curing process can, however, be carried out in any other way.

In order to produce positive electrodes, which, with only a single charge, reach their full capacity, it has proved expedient to take a compressible mass, which contains more than 15% new material.

The positive electrodes made according to the invention can be connected to negative electrodes of the usual form and thus form a finished element. The possibility of using positive 1 electrodes in elements with lead,

however, additional savings in the weight and dimensions of the cell are achieved and achieved if such negative electrodes are also used which consist of only one active mass with a current conductor placed in it. The inventor uses for the manufacture of the same method of pressing, wetting and drying, as well as for the production of positive electrodes, but uses powdered sponge lead mixed with lead sulphate, to which, in case of need, lead oxides can be mixed as the compressible mass. . The mass of this compound has an excellent compacting ability and gives very productive negative electrodes, which can be mounted in the same way as positive ones.

In the manufacture of such a lead sponge mixed with lead sulphate, for example, the following method can be used: lead oxide is reduced by electrolysis in a bath of sulfuric acid and then, together with the sulfuric acid adhered to it, dried and milled. In dry powdered mixtures prepared by pressing electrodes, it is important to always obtain a uniform and uniform structure as possible. In view of the fact that in powders, unlike liquids, the pressing pressure is not evenly distributed over all the space under pressure, but acts on the upper layers of the material being subjected to pressing differently than on the lower ones, it is advisable to give the pressed electrodes the shape of not too thick plates and expose known method simultaneous pressure on both sides of the plate. The embedded metal conductor is, however, an alien body in a plate which, under certain circumstances, can generally make such electrodes unsuitable. The inventor has found that the homogeneity of the internal structure of the pressed electrodes is less disturbed by such an embedded metal conductor, which has a cross section

oblong or rhomboidal shape and, if possible, its edges, i.e. the conductor planes, are inclined to the direction of the pressing pressure, while the conductor is as much as possible laid in the material so that its long axis lies in the direction of the pressing pressure.

In order to achieve the best possible current distribution within the pressed electrodes, the elastic conductor should be provided with lateral processes and branches extending from them. The inventor has found particular advantages in that each lateral process with its branches is not in contact with the neighboring, so that the processes and branches in no way form a frame. Each process and branch has a free end and thus never forms rectangular forms with other processes or branches. Thanks to this construction, it is achieved that the conductor can conveniently follow the expansion and contraction of the active mass.

The combination of positive and negative, consisting of a single mass of electrodes, into ready-made cells presents no particular difficulty, since these elements must be used instead of conventional lead-acid batteries. It is advisable to insert such electrodes consisting only of mass into the shells adapted for this purpose and, in this form, be installed, suspended or otherwise fixed in the battery box.

Diluted sulfuric acid is used as an electrolyte as it is currently used in batteries.

The subject of the patent.

1. A method of manufacturing a material for active masses, especially lead-acid batteries, by the action of diluted nitric acid on red lead, characterized in that the reaction is not completed in order to obtain a special type of lead peroxide, corresponding to the content of active

oxygen, corresponding to approximately 93% lead peroxide and possessing the following physical properties: a lower specific weight than normal lead peroxide; bulk density, measured in ether, approximately equal to one, and

the specific resistance of the dry powder at 1 (30 atm. specific pressure less than 0.2 ohm / hl.

2. The use of the material according to the method of claim 1 in an amount of not less than 15% of the total weight of the active mass.