JPH06103628B2 - Lead acid battery - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed or semi-sealed lead-acid battery separator structure.

2. Description of the Related Art In a negative electrode absorption type lead-acid battery (hereinafter simply referred to as "conventional battery") that uses a conventional mat-shaped separator and absorbs oxygen gas generated from the positive electrode at the negative electrode, the mat is 2 μm.
A glass fiber of m or less is used as a main component, and it is made in a substantially uniform state as a whole, but this ultrafine glass fiber is extremely expensive. Furthermore, this material is weak in binding force between fibers and easily broken, and poor in handling such as transportation, which makes automation difficult and requires careful manual work.

Problems to be Solved by the Invention Here, focusing on the basic function of the mat as a separator in the negative electrode absorption type lead-acid battery, it has a liquid content enough to supply a sufficient amount of dilute sulfuric acid to the positive electrode for the discharge reaction. , Having a separating property for preventing the detached loose particles of the positive electrode active material from reaching the negative electrode, and having a kind of air permeability for carrying and absorbing a certain amount of oxygen to the negative electrode. The above-mentioned conventional battery uses the ultrafine glass fiber and almost completely fulfills the above three functions. However, the ultrafine fiber of this glass is high in cost and extremely poor in workability as described above. The cost of the lead-acid battery using is drastically raised.

Therefore, as conventional mat-shaped separators that have been improved so as to reduce the cost, some have been tried that have the following structural characteristics.

Increase the fiber distribution density on the positive electrode side in order to supply a sufficient amount of dilute sulfuric acid to the positive electrode.

In order to prevent free particles of the positive electrode active material from moving and reaching the negative electrode, a large amount of inorganic powder is filled on the negative electrode side.

The following improvement examples including these two features are mainly those in which glass fiber having a medium thickness of 5 to 10 μ is the main material, but depending on the blending degree of the powder as the sub material,
It was impossible to satisfy all of the above, because the achievement levels of the basic functions 1 to 4 were different.

Improvement example 1: Glass fiber of medium thickness, thickness of 5 to 20 μm
A synthetic resin fiber and an inorganic powder having a particle size of 1 μm or less are added and paper is made together, and a small amount of binder is added to form a mat. In the papermaking process, the properties of the fibers are biased to the front side of the paper and the inorganic powder is biased to the back side, so that the above functions (liquid-containing property on the positive electrode side and particle blocking function on the negative electrode side) can be satisfied. It was However, regarding the effect (air permeability on the negative electrode side), the mat surface on the negative electrode facing side, which is the back of the paper, becomes too dense, and sufficient oxygen cannot be passed through the negative electrode.
Oxygen gas absorption at the negative electrode could not be sufficiently achieved.

Improvement Example 2: For the purpose of correcting Example 1, paper was made so that the inorganic powder on the back side of the paper was slightly reduced to reduce the particle density. Specifically, a method of reducing the powder concentration of the liquid when making paper,
An attempt was made to weaken the suction force of the drainage of the net when making. However, there was a tendency that the effects of any improvement were rather decreased.

Improvement example 3: A method of further reducing the degree of denseness on the back side of the paper was also tried, but in this case, the front and back sides of the paper have almost the same coarse and dense state, and the effect of is considerably improved, but the effect is a little. And the effect of was greatly reduced, and the life was shortened.

After all, the conventional basic type and its improved example are summarized. Although the conventional basic type sufficiently satisfies the required level in performance, the material cost is high and the workability is poor. Further, in the conventional improvement example 1, although the cost is low, the supply of oxygen gas to the negative electrode becomes poor, and the sealed battery cannot be obtained. In improvement example 2, there is a problem in battery life, and oxygen supply to the negative electrode is insufficient. The improvement example 3 had a drawback that the battery life was remarkably shortened.

The present invention is intended to provide a novel mat structure for a negative electrode absorption lead-acid battery that solves the above-mentioned various drawbacks.

Means for Solving the Problems The mat-shaped separator for a lead storage battery of the present invention has a thickness of 5 to 10 μm and a thickness of 5 in order to achieve the above object.
-20 μm heat-sealable synthetic resin fiber and inorganic powder having an average particle size of 1 μm or less, which are repeatedly made about 2 to 5 times by a papermaking method, and the last one layer is the above-mentioned synthetic material. Add 1/2 to 2 of resin fiber to the total amount of components other than water
A multi-layer mat formed by increasing the number to about 1/3 is brought into contact with the positive electrode plate with a layer containing a large amount of synthetic resin fiber, and a positive electrode plate that is one size smaller than the mat is sandwiched, and ultrasonic waves or a heat fusion method is applied around the mat. Welded by As a result, the positive electrode plate is wrapped in a direction in which it touches the surface of the mat having the largest amount of synthetic resin fibers.

Thus, in the mat-shaped separator of the present invention having the above-described structure, the electrolyte is supplied to the positive electrode mainly by the synthetic resin fiber having a relatively thick layer (5 to 20 μm) in direct contact with the positive electrode plate. It's easy because it's done.

A short circuit between the positive and negative electrodes through the mat does not occur because the layer of inorganic powder, which is repeated 2 to 5 times, blocks the movement of free particles.

Oxygen is supplied to the negative electrode in a very dense structure (inorganic structure), because the layer with many inorganic substances that is in direct contact with it is relatively thin and the multilayer structure in which it is repeated multiple times has sufficient ability to prevent free particles from moving in the entire thickness. Since the powder does not have to be in a tightly pinched state, it is sufficiently performed.

In addition, since all the materials are relatively inexpensive and the existing papermaking process having extremely high productivity can be used, the material cost can be reduced.

Ultrasonic waves, sheet seals, etc. can be adopted, and since the high-strength electrode plate is the core, it is easy to carry and handle.
Further, since the sealed portion is crushed with a considerably high pressure, the strength of the peripheral portion is higher than that of the mat alone, and there is an advantage that mechanization and automation are easy in the steps after forming the electrode plate group. .

The operation and the like of the present invention as described above are shown in Table 1 in comparison with the features of the conventional example described above.

Examples Examples of the present invention will be described below.

Medium thickness, 5-10μ, which is relatively inexpensive for glass fiber
The thickness of synthetic resin fiber with a thickness of 5 to 20 μm, which can be heat-welded, and the inorganic powder is about 1/3 of the thickness of the mat (0.5 to 3 mm). Next, make a similar blended material with a thickness of about 1/3 on top of this, and make synthetic resin fiber more than about 1.5 times the density up to that and also about 1/3 Cut to thickness. This usually results in a rough layer with many fibers on the front side of the paper (upper side of the papermaking) and more inorganic powder on the backside of the paper (on the mesh side of the papermaking). A mat with such a three-layer structure can be formed. In the mat (3), (4) is a layer having a large amount of fibrous material, and (5) is a layer having a large amount of inorganic powder. In this case, if the side in contact with the positive electrode plate (1) is the last fiber layer (4 '), this layer (4') has more synthetic resin fibers than other fiber layers, so that the positive electrode is easily formed. The bag-shaped separator having the plate (1) inside can be completed by heat welding or ultrasonic welding. In addition, (2) on the outside of the separator is a negative electrode plate.

The bag-shaped separator containing the positive electrode plate (1) is made of an original material because of the hardness of the positive electrode plate (1) and the hardness obtained by pressure bonding both sides with heat or ultrasonic waves during sealing. The low mechanical strength that it possesses can be largely compensated for, and it is easy to transport and handle, so that it can be easily assembled by an automatic machine. The distribution of fibers and powder is determined by the material distribution ratio (concentration)
It is possible to adjust by the force of suction under the net, the moving speed of the net, etc. during paper making. Using the three-layer structure mat produced in this way, an actual battery was assembled and compared with a conventional battery and its improvement examples 1 to 3, discharge performance, life performance, negative electrode absorption performance (liquid (Holding performance). These characteristic curves are shown in FIGS. 2 to 4 except for the conventional type, and their comprehensive evaluation is shown in Table 2.
Summarized in.

That is, (6), (7), and (8) in the characteristic curve are those of the conventional improvement examples 1, 2, and 3, respectively, and (9)
Is according to the invention. The mat-shaped separator structure of the present invention substantially corresponds to the best example (6) of the conventional improvement examples in the discharge performance (Fig. 2) and the life performance (Fig. 3), and the liquid retention characteristic (Fig. 4). In the figure, it was far superior to the third example (8), which was the most excellent of the conventional improvement examples.

The comparison of these characteristics and the comprehensive evaluation including the known characteristics of the conventional basic type and the cost aspect are shown in Table 2 above, and the battery using the mat-shaped separator of the present invention is inexpensive and excellent in performance. You can see that it will be a good thing.

EFFECTS OF THE INVENTION The superiority of the present invention is considered to be due to the following reasons.

That is, in order for free particles of the positive electrode active material to reach the negative electrode, it is necessary to cross the dense layer a plurality of times (three times in the embodiment), and the traveling speed in the thickness direction becomes slower. The short circuit in the separator does not occur until the original life of the product. Therefore, since it is not necessary to increase the degree of denseness of the mat on the negative electrode side, oxygen can pass through the mat facing the negative electrode, and the relatively dense layer in contact with the negative electrode side is thin. It also improves the oxygen flow.
As a result, it is industrially significant that it is possible to manufacture a negative electrode absorption lead-acid battery that is inexpensive and has excellent discharge performance, life performance, and liquid retention. Although three layers are taken in the example of the present invention, the number of this layer is suitably 2 to 5, and if it is more than this, it will be close to 3 of the conventional improvement example, and the effect will be improved. Not only the reduction, but also the productivity of the mat-shaped separator is deteriorated, resulting in an increase in cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a graph showing the 5-hour discharge performance of the battery of the present invention and the conventional method, and FIG. 3 is a graph of the battery of the present invention and the conventional method. FIG. 4 is a graph showing a comparison between voltage system life performances, and FIG. 4 is a graph showing a comparison between the liquid retention performances of the battery of the present invention and the conventional method during trickle charging. (1) …… Positive electrode plate (2) …… Negative electrode plate (3) …… Matt-shaped separator (4) …… Matt-shaped separator with a high fibrous layer (4 ′) …… Matt-shaped separator synthetic resin fiber material Layer with a lot of particles (5) …… Layer with a lot of inorganic powder of mat-shaped separator (6) …… Characteristics according to Conventional Improvement Example 1 (7) …… Characteristics according to Conventional Improvement Example 2 (8) …… According to Conventional Improvement Example 3 Characteristics (9) ... Characteristics according to the present invention

Claims (1)

[Claims] 1. A structure in which a mat-shaped separator is interposed between a positive electrode and a negative electrode, wherein the mat-shaped separator has a layer in which a large amount of fibrous material is arranged on the side facing the positive electrode and a large amount of inorganic powder is arranged on the side facing the negative electrode. Having multiple layers of this layer, it was made by making only a layer in contact with the positive electrode have more heat-sealable synthetic resin fiber components than other layers, and the positive electrode was surrounded by this separator. Characteristic lead acid battery.