JPS5945192B2 - Manufacturing method of paste type electrode for lead battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the manufacturing process of a paste wood electrode for electrolyte brewing.

Currently, lead-acid batteries using paste electrodes, which are most commonly used as storage batteries, are very cheap compared to other storage batteries and have excellent high-rate discharge characteristics, but they have a rather short charge-discharge cycle life. Inferior.

Paste type electrode plate number ^ A paste made by kneading lead powder, dilute sulfuric acid, and some resin fiber to maintain strength is mixed into a lead alloy lattice with a small amount of antimony, calcium, or tin metal added. It is painted and fixed.

One of the main causes of deterioration in battery life using this electrode plate.
Secondly, the anode active material gradually softens and falls off during charging and discharging.
In addition to a decrease in capacity, falling substances can cause a short circuit between the anode and cathode. Conventional methods to prevent this have been to apply a certain amount of force to the electrode plates to hold them in the battery case, or to wrap the anode plates in a microporous separator, but this is not enough for wood. OAlso, in order to increase the strength of the electrode, resin fibers are added, but if too much is added, it will interfere with workability and high rate discharge, so 0.1
It's only about 0.5% by weight. The present invention aims to prevent such paste-type electrode plates from softening and falling off due to charging and discharging, and to extend the life of the lead-acid battery without impairing its discharge characteristics.

That is, conventionally, only a small amount of resin fiber was added to the paste, but in the present invention, about 0.1 to 0.5% by weight of thermoplastic resin fiber is further added to the paste, and the paste is further kneaded. After the mixture penetrates into the lattice and becomes fixed, it is heated at a temperature equal to or higher than the melting point of the thermoplastic fibers to melt only the thermoplastic fibers.

According to this method, the parts that are in contact with the resin fibers and the thermoplastic resin fibers are melted and bonded by heat treatment, so that after cooling, a three-dimensional network structure is formed and used as an active material storage medium. *Becomes very strong.

Further, the melted part of the thermoplastic resin partially dissolves into the active material powder, making it possible to strengthen the bond between the powders in the vicinity. Furthermore, since gaps are created in the area occupied by these fibers, the porosity inside the electrode increases, making it easier for the sulfuric acid in the electrolyte to penetrate. Thus, according to the present invention,
Not only does the electrode strength become stronger, but sulfuric acid also diffuses more easily, resulting in a long-life electrode with little loss of capacity.

As the thermoplastic resin fibers used here, those that are acid resistant and readily melt at a relatively low temperature of about TLSlOO~200°C are advantageous in terms of workability and because they do not adversely affect the active material.

Specifically, polyethylene, polypropylene, polyolefin, etc. are suitable because they are easily acid resistant and melt at 100 to 200°C. The heat treatment conditions are as follows: in a normal air atmosphere, at or above the melting point of the fibers,
Treatment at a temperature 30° C. higher for about 30 minutes is sufficient.

Although the purpose can be achieved to some extent by simply mixing thermoplastic resin fibers alone in the paste, the strength of the fibers decreases after heating and melting, so it is necessary to mix them with resin fibers that do not melt. By doing so, a strong three-dimensional network structure can be formed.Of course, it goes without saying that the three-dimensional network structure of the present invention cannot be formed only with resin fibers that are not melted and bonded. Note that even if the non-melting fiber is thermoplastic, it is sufficient if the melting temperature is sufficiently higher than that of the resin to be melted. EXAMPLES The present invention will be explained in more detail with reference to Examples.

The anode paste contains 0.2% by weight of polyethylene fibers with a length of 3 to 7 m&S and a diameter of 20 to 50 μm based on the active material, and a resin fiber of 2 to 4 mm in length that does not melt by heating. , diameter 20~
50μ, melting temperature 180℃ polyester fiber 0.2
After mixing % by weight and kneading this thoroughly, the size of 100
After applying it to a grid of x100wm and thickness of 1Tmri and fixing it, heat treatment was performed at 150°C for 30 minutes.

After cooling, this anode and the normal (c) cloud electrode are stacked alternately through separators to form 5 anodes and 6 cathodes, the lead parts of each are integrated, and this is placed into a battery case. A battery was constructed by injecting dilute sulfuric acid with a specific gravity of 1.265 as an electrolyte solution. This battery is called A. As a comparative example, polyester fiber alone was used at 0.2% by weight and 0.4% by weight, respectively.
A battery using the former electrode is designated as B1, and a battery using the latter is designated as C. Using these three types of batteries, high rate discharge of 150 A was performed at room temperature. The results are shown in FIG.

Next, discharge to 1.7V at 5A, and discharge at 5A to 13V.
The charging and discharging cycles of 0% charging were repeated and the results are shown in FIG. As is clear from FIG. 1, there is almost no difference in high rate discharge. In battery A, compared to battery B, there was no deterioration even though the amount of resin fiber added was large. On the other hand, with C containing the same amount of resin fibers, a slight deterioration is observed. This is thought to be because the treatment of the present invention makes the inside of the electrode plate slightly porous to compensate for the loss of discharge characteristics due to the increased amount of resin, so that it does not deteriorate even in high rate discharge. In FIG. 2, battery A is clearly superior.

It can be assumed that this is because the electrode strength is increased by the three-dimensional structure of the resin fibers over the entire electrode plate. If the fibers were simply increased, the deterioration at the 100th cycle was only slightly reduced from the comparison of B-C. As described above, the present invention can greatly extend the charge/discharge cycle life without adversely affecting the high rate discharge characteristics.

In addition, here, the length of the thermoplastic resin fiber is 3 to 7 m.
! Although polyethylene fibers having a diameter of 20 to 50 μm were selected, other acid-resistant thermoplastic resin fibers such as polypropylene and polyolefin can be similarly applied.

Furthermore, it is also possible to use fibers with diameters and lengths outside the above ranges. In addition, sufficient effects were observed when the amount of these fibers added was less than about 0.1% by weight based on the active material, and the same effect was observed when the amount was more than 0.5% by weight. % or more, some problems will occur in workability, so preferably 0.1 to 0.5% by weight is appropriate. Similarly, the amount of unmelted fiber added is suitably 0.1 to 0.5% by weight based on the active material.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the discharge characteristics of a lead battery using an anode obtained according to the present invention and a battery using a comparative example d-field electrode, and FIG. 2 shows changes in discharge capacity due to charging and discharging.

Claims (1)

[Claims] 1. A paste-type electrode for a lead battery, characterized in that an electrode containing a paste made of a mixture of thermoplastic resin fibers and fibers that do not melt at the melting temperature of the resin is heat-treated to melt the thermoplastic resin fibers. Manufacturing method.