JPH0211980B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a paste-type electrode plate using a lightweight grid in which thin and sparsely arranged grids are formed by casting or expanding a lead alloy sheet. Reducing the weight of the grid is effective in reducing the weight of the battery, but if the thin grids are sparsely arranged, it is not only difficult to fill with paste, but also the active material tends to fall off. One way to make paste filling easier is to press paper made of pulp fiber to adhere to the paste, but it peels off after drying, making assembly difficult, and it decomposes into organic acids in the battery. may cause damage to the positive electrode plate. The use of mats made of plastic fibers has similar drawbacks, and furthermore, it impairs the diffusion of the electrolyte, thereby deteriorating the battery characteristics. An object of the present invention is to provide a lightweight electrode plate that does not interfere with battery manufacturing operations and has excellent initial capacity and life performance. The gist is that a thin glass mat with a thickness of 0.3 mm or less is bonded to the surface of a paste filled in a lattice so as to bury most of the wood by rheological deformation of the paste, and a plastic solution or emulsion is applied to the surface. The purpose is to attach it and heat it to harden it. Filling a grid with thin and sparsely arranged paste with paste is a difficult process because the problem is keeping the paste in the grid. If you place the grid on a porous sheet such as paper or matte and fill it with paste, then press the porous sheet on top of it to rheologically deform the paste and sink it into the holes in the porous sheet to combine the two. , paste filling can be carried out without any problem. Various types of porous sheets were experimentally tested, and the resulting electrode plates had a capacity of 20 hours (hR) and a capacity of 35
Assemble ampere hour (Ah) car batteries,
After forming the container, the capacity was measured. Table 1 shows the state of the paste-filled electrode plate after aging and drying and the 1 hR discharge capacity. In addition, when assembling the battery, we used electrode plates that were in good condition and were pushed out.

[Table] Looking at the state of the electrode plate after drying, only porous sheets with a sparse texture and small basis weight, that is, those made of glass matte, PP nonwoven fabric, and natural pulp paper, with the grid embedded in the paste, were porous. The results were good, with no peeling of the sheet or falling of the paste. With other electrode plates filled with paste so that the lattice bars are exposed, even if the porous sheet is pressed against the paste surface, the paste cannot be rheologically deformed when it hits the lattice bars, and the holes in the porous sheet are It becomes difficult to put it in. Further, in the case of a glass woven fabric having a high weave density, the pores are too small and the paste surface is uniformly compressed, making it impossible to force the paste into the pores. Most of the discharge capacity using porous sheets decreased, but only the discharge capacity using thin, sparse glass mats improved. Even if it is a glass mat, the thicker the mat, the lower the capacity. In a normal battery using a glass mat, the electrode plate and the mat are not integrated, but are simply brought into contact and pressed together. In the test battery shown in Table 1, the porous sheet such as glass mat was penetrated with paste and became integrated with the electrode plate. This structural factor impedes the diffusion or outgassing of the electrolyte, resulting in the capacity reduction shown above. When some of the batteries shown in Table 1 were subjected to a charge/discharge cycle life test, the porous sheet attached to the paste peeled off from the electrode plate, and because the grid was lightweight, the active material often fell off, resulting in a short life. Therefore, by attaching plastic to the surface of an electrode plate made by combining glass mats made of fibers with a diameter of 10 microns (μ) by rheological deformation of the paste using various methods, we fabricated a prototype electrode plate in which the glass mats and paste were fixed. A cycle life test was conducted. The results are shown in Table 2.

[Table] For emulsion spraying, use a methacrylic acid ester resin with a concentration of 10% by weight.
6 g/dm ² of resin was deposited on one side of the electrode plate.
For peripheral coating, use 30% polystyrene in styrene monomer.
% dissolved and an appropriate amount of polymerization catalyst added thereto was applied to the periphery of the electrode plate excluding the edges. In the mesh application, the same solution was applied in a mesh pattern at intervals of approximately 10 mm in length and approximately 20 mm in width. All of these operations are performed within 10 minutes when the paste contains moisture, that is, the paste is filled into the grid, and then heated in a drying oven at 160℃ for 5 minutes to remove moisture from the surface of the electrode plate and at the same time solidify the plastic. I let it happen. This electrode plate was allowed to stand at room temperature, sufficiently dried, and then chemically formed and subjected to a charge/discharge test. As is clear from the results in Table 2, the thickness of the glass mat is preferably 0.3 mm or less; if it is too thick, not only will the initial capacity be low, but the mat will peel off during the cycle test and no effect on improving life performance will be seen. .
When the diameter is 0.3 mm or less, no matter which method is used to fix the plastic, there is almost no decrease in the initial capacity and the life performance is significantly improved. This improvement in life performance was achieved because the plastic adhered to both the glass mat and the paste and strongly bonded them together, suppressing the softening and falling off of the active material. Therefore, simply allowing the plastic to adhere to and harden on the glass mat before combining it into a paste is not effective. Glass mats vary in fiber diameter, from long fibers of about 20μ, which is the most common type, to about 10μ, which is used in closed-type tubes, to short fibers, of several micrometers, which are used in sealed batteries, and of less than 1μ. Depending on the manufacturing method, it can be divided into dry method and wet method of paper making method. Among these,
The 20μ mat with thick fibers had low strength when the thickness was 0.3 mm or less, and the pores were too large, making it difficult to combine with the paste, but all other mats were good. All glass mats are made of methyl methacrylic polymer for ease of handling.
% attached. It is clear that the pattern for partially fixing the surface of the electrode plate is not limited to a net shape, but may also be a plurality of lines or a large number of dots.

Claims (1)

[Claims] 1. A thin glass mat with a thickness of 0.3 mm or less is placed on the surface of the paste filled in a grid so as to bury most of the berms, by rheologically deforming the paste. A plastic solution or emulsion is applied to the surface of the glass mat by coating or spraying, and this is heated and hardened. A method for producing a paste-type electrode plate that is an unformed electrode plate. 2. A method for manufacturing a paste-type electrode plate according to claim 1, characterized in that a plastic solution or emulsion is applied to the periphery. 3. The method for manufacturing a paste-type electrode plate according to claim 1, characterized in that the plastic solution or emulsion is deposited on the surface in the form of points, lines or networks.