JPH0231721Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to the improvement of a spiral electrode group including a positive electrode plate using a sponge-like porous nickel material as a substrate. The purpose of this is to improve the current collecting ability from the positive electrode plate.

Conventionally, the substrate for the positive electrode plate of alkaline batteries is
A sintered body of nickel powder is used, but its porosity is about 70 to 80%, and if the porosity is increased beyond this, its mechanical strength will be significantly reduced, and the porosity within the pores will decrease significantly. When the positive electrode active material is filled in the substrate, there are drawbacks such as deformation and cracking of the substrate and peeling of the active material. In addition, when filling the active material,
Usually, a method called vacuum impregnation method is used, in which the substrate is impregnated under reduced pressure with an aqueous solution of a nickel salt such as nickel nitrate or nickel sulfate, then treated with an alkaline aqueous solution, and then washed with hot water and dried. . However, the amount to be filled in one operation is small, and the amount to be filled from the second operation onwards gradually decreases, so usually 4
It is necessary to repeat the operation ~10 times. Therefore, the manufacturing process is complicated and the economic cost is high.

Therefore, in recent years, attention has been paid to a method in which a sponge-like porous body made of nickel metal having a three-dimensionally continuous structure is directly filled with a positive electrode active material in the form of a paste.

Sponge-like porous nickel material with a three-dimensional continuous structure has a high porosity of 90 to 98%.
Moreover, it has high mechanical strength. Moreover, since the pore diameter is large, filling this porous body with an active material can increase the capacity of the positive electrode plate, and the filling method is extremely simple, making it possible to perform a continuous process and being economically advantageous. However, when a sponge-like porous nickel material is used for the substrate, there is a drawback that it is difficult to attach current collector terminals. That is, when a porous body is filled with an active material, the active material has a large electrical resistance, making it extremely difficult to weld the current collector terminal. Therefore, as shown in Fig. 1, a method can be considered in which a part of the porous body 1 is pressurized into a concave shape in advance to provide a collector terminal attachment part 2, and then filled with active material. Since some active material adheres to portion 2, welding of the current collector terminal may become incomplete. There is no problem if the current collecting terminal is attached before filling the active material, but in that case, there is a drawback that the current collecting terminal becomes an obstruction and the efficiency of filling the active material is significantly reduced. Furthermore, the method described above has the disadvantage that the current collecting terminal 3 protrudes perpendicularly to the longitudinal direction of the positive electrode plate 7 as shown in FIG. 2, resulting in poor efficiency in winding the electrode in a spiral shape. Therefore, the current method of attaching current collector terminals, which is generally used for sintered electrode plates,
That is, as shown in FIG. 3, positive and negative electrode plates are provided with a portion 4 in which the support steel plate of the sintered substrate is exposed parallel to the longitudinal direction of the electrode at one end of the electrode, and a separator is attached as shown in FIG. It is conceivable to use a method of welding the positive and negative electrode current collector terminals 10 and 11, respectively, to the supporting steel plates 5 and 6 of each electrode substrate, which are spirally wound while being shifted in a predetermined direction through the electrode group and protruding from the upper and lower end surfaces of the electrode group. However, when using a sponge-like porous nickel material, even if the porous material is pressurized in advance and the current collector terminal mounting portion 4 is provided, if the degree of pressurization is small and the porosity is not sufficiently reduced. When filling the paste-like active material, a small amount of the active material is filled into the current collecting terminal mounting portion, so that the current collecting terminal may not be completely mounted. On the other hand, if the degree of pressure is too large, the rigidity of the part where the current collecting terminal is attached will decrease, and the pressure applied when welding the current collecting terminal will easily cause bending or deformation, causing problems such as internal short circuits. occurs.

The present invention was developed to solve the above-mentioned problems by applying strong pressure to the porous body over the entire length or part of the edge of the positive electrode plate in parallel to the longitudinal direction of the positive electrode plate, and By providing a collector terminal attachment part with a crack perpendicular to the longitudinal direction of the electrode plate and bending the collector terminal attachment part towards the outside or the center of the spiral electrode group, the electrode can be This improves the efficiency of spirally winding and welding the positive electrode current collector terminal, and also improves the current collecting ability of the positive electrode plate.

Hereinafter, embodiments of the present invention and their effects will be described in detail.

The positive electrode plate used in this invention was manufactured as follows. First, average pore diameter 0.3mm, porosity 94%, thickness
Both ends of a continuous band-shaped sponge-like porous nickel material with a width of 1.1 mm and a width of 81 mm are separated by 3.0 mm as shown in Figure 5.
The collector terminal attachment part 12 is continuously pressurized to a thickness of 0.1 mm with a width of
A substrate was prepared by cutting spaced cracks 13 using a cutter or the like. Next, a mixed powder of 85 parts of nickel hydroxide powder, 10 parts of carbonyl nickel powder, and 5 parts of cobalt powder was made into a paste form with an aqueous carboxymethyl cellulose solution, and after drying, it was impregnated with a dispersion of fluororesin. 0.68mm
The positive electrode plate was formed by pressure molding to a thickness of 1,000 yen and cut into a desired size. The active material adhering to the current collector terminal attachment part could be easily wiped off. The thus obtained positive electrode plate was combined with a conventionally known paste-type cadmium negative electrode plate via a nylon nonwoven fabric separator, and wound into a spiral. Then, after bending the positive electrode current collector terminal attachment part toward the center of the spiral electrode plate group as shown in FIG. 7, the positive and negative electrode current collector terminals 10 and 11 are welded and SG1 is added to the electrolyte. 300 (20
℃) A sealed cylindrical nickel-cadmium storage battery A with a nominal capacity of 2.5Ah was manufactured using a KOH aqueous solution. Here, the current collector terminal 10 was easily attached to the current collector terminal attaching portion 12 of the positive electrode plate, similar to when a sintered electrode plate was used. Note that the current collector terminal mounting portion may be bent to the outside of the electrode plate group. For comparison, battery B was fabricated using a positive electrode plate made by filling a porous body with a concave collector terminal attachment part with an active material and then welding the collector terminal as shown in Figure 1. did. In this case, welding of the current collecting terminal may be difficult due to the active material adhering to the current collecting terminal mounting part, or
When winding the electrode, the current collector terminal got caught in the winding jig, etc., causing it to come off from the positive electrode plate.

The discharge capacity and the relationship between discharge intermediate voltage and discharge rate when these batteries were charged at 20° C. and 0.1 CA for 16 hours and then discharged at various discharge rates are shown in FIGS. 8 and 9, respectively. From the figure, it can be seen that the battery A according to the present invention has a larger discharge capacity and a higher discharge voltage than the battery B according to the conventional method.

In particular, during high rate discharge, the battery A according to the present invention
It can be seen that the discharge performance is excellent.

This is considered to be due to the following reasons. In other words, when the current collector terminal is attached using the conventional method, sufficient conductivity between the current collector terminal and the electrode cannot be obtained because the active material is attached to the current collector terminal attachment part. It is believed that there is. Another possible reason is that since the current collecting terminal is provided at only one location, the active material located further away from the terminal is less likely to be utilized as the rate of discharge increases. However, according to the present invention, the active material does not adhere to the strongly pressurized current collector terminal attachment part, so the conductivity between the current collector terminal and the electrode is extremely good, and current collection is achieved over the entire length of the electrode. Since the active material can be used almost completely, it is considered that the discharge performance is excellent. In addition, since the collector terminal attachment part is bent in advance toward the outside or the center of the spiral electrode plate group, the collector terminal attachment part may deform when welding the collector terminal, causing an internal short circuit. There was nothing to wake me up. Furthermore, when low rate discharge is applied, it has been confirmed that sufficient current collection performance can be obtained by providing a collector terminal attachment part only partially, without providing the collector terminal attachment part over the entire length of the electrode.

As described above, according to the present invention, even when a sponge-like porous nickel material is used as a substrate, it is possible to provide a storage battery in which the current collecting terminal can be easily attached and is equipped with a positive electrode plate having excellent current collecting properties. . It goes without saying that the present invention can also be applied to other alkaline storage batteries in which the negative electrode plate is made of zinc, iron, or the like.

[Brief explanation of the drawing]

Figures 1 and 2 show a conventional method for attaching a current collector terminal to a positive electrode plate using a sponge-like porous nickel material, and Figures 3 and 4 show a method for attaching a current collector terminal using a sintered electrode plate. A diagram showing the current collection method, Fig. 5,
6 and 7 are diagrams showing the current collecting method according to the present invention, and FIGS. 8 and 9 are diagrams comparing the discharge performance of the battery according to the present invention and the battery according to the conventional method. 1... Sponge-like porous nickel material, 2, 12...
... Current collector terminal attachment part, 7 ... Positive electrode plate, 8 ... Negative electrode plate, 9 ... Separator, 10 ... Positive electrode current collector terminal,
11... Negative current collector terminal, 13... Crack.

Claims (1)

[Claim for Utility Model Registration] In a storage battery equipped with a spiral electrode group formed by winding electrode plates, the positive electrode plate is a sponge-like material having a three-dimensional continuous structure of an active material mainly composed of nickel hydroxide. This is a paste-type positive electrode plate held in a porous nickel material, and the positive electrode plate has a compressed part in which the sponge-like porous nickel material is compressed over the entire length or part of the edge of the electrode plate in parallel with the longitudinal direction of the positive electrode plate. The compressed part has a crack perpendicular to the longitudinal direction of the positive electrode plate, and the current collector terminal attachment part is constructed by bending the compressed part parallel to the end surface of the spiral electrode plate group. A storage battery equipped with a spiral plate group characterized by: