JP2707728B2 - Sealed lead-acid battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sealed lead-acid battery using a glass fiber separator, and more particularly to a sealed lead-acid battery that is taller than its width.

[Prior art] Conventionally, as a sealed lead-acid battery, a papermaking sheet having a predetermined uniform density is formed by a papermaking method or the like by using glass fiber alone or a mixture of acid-resistant synthetic fibers and synthetic pulp. Using a glass fiber separator obtained by cutting to dimensions, interposing this between the anode plate and the cathode plate, assembling the electrode plate group, assembling it in the battery case, and releasing the diluted sulfuric acid electrolyte flowing through the separator It is known that the resin is impregnated to the extent that there is no water.

In particular, in sealed lead-acid batteries that are taller than their width, the tensile strength in the vertical direction (height direction) is greater than the tensile strength in the horizontal direction (width direction) in order to ensure strength in the height direction. A glass fiber separator in which fibers are oriented in a paper making process is used.

When a separator made of such a sheet having a vertical tensile strength larger than that of a horizontal sheet is assembled in such a manner that the height direction of the battery and the vertical direction of the sheet are matched, the sealed lead-acid battery is affected by gravity. The electrolyte in the separator is
The amount of the electrolytic solution is smaller at the upper part of the separator.

Further, since the storage battery performs charging and discharging during use, the sulfuric acid in the electrolytic solution reacts with the electrode plate active material by discharging, and the concentration decreases. Then, upon charging, sulfuric acid is released from the electrode plate active material and the concentration increases.In this process, the sulfuric acid having a high concentration sinks downward due to its high specific gravity, and the concentration of the electrolytic solution in the separator becomes lower. Gradually lower at the upper part and higher at the lower part (so-called stratification phenomenon). For this reason, there is a problem that a density cell is formed in the vertical direction, and the negative electrode active material is sulphated in the lower part, and the characteristics of the storage battery are deteriorated as a whole. This tendency is more pronounced in a storage battery having a higher height, resulting in a shorter life.

In recent years, with the increase in the size of sealed lead-acid batteries, it has been desired to improve the liquid holding power of the separator in the height direction of the battery, so that the distribution of the electrolyte in the vertical direction is uniform and the concentration of the electrolyte is stratified. There is a demand for an excellent sealed lead-acid battery that does not cause the occurrence.

Conventionally, in order to increase the liquid holding power on the upper part of the separator, the fiber diameter of the glass fiber on the upper part of the separator is made thinner (see
No. 60-100363) or the technique of increasing the glass fiber density at the upper part of the separator (Japanese Patent Application Laid-Open No. 62-229657) is provided, and the respective effects are obtained.

[Problems to be Solved by the Invention] However, it is not easy to manufacture a separator in which the fiber diameter of the glass fiber in the upper part of the separator is small and the separator in which the glass fiber density in the upper part of the separator is large, and the manufacturing cost is soaring. Had the disadvantage of doing so.

The inventors of the present invention have conducted intensive studies to improve the liquid holding power of the separator of the sealed lead-acid battery, and have obtained the following findings.

Important factors affecting the liquid holding power of the separator include the adhesion between the separator and the electrode plate, in addition to the liquid retention of the separator itself. In the conventional sealed lead-acid battery, the contact and adhesion between the electrode plate and the separator is not sufficient, so that the descending speed of the liquid increases, and a good liquid holding force cannot be obtained. The main cause of insufficient adhesion between the electrode plate and the separator is that the surface of the separator has irregularities and lacks flatness. That is, the separator is manufactured by the papermaking method as described above, but the papermaking sheet obtained by feeding the papermaking raw material onto the papermaking net usually has a flat surface on the papermaking net side. However, unevenness occurs on the surface opposite to the net (the upper surface side during papermaking), and a flat surface cannot be obtained. Therefore, when such a papermaking sheet having one surface which is non-flat surface is arranged as a separator between the electrode plates and inserted into the battery, as shown in FIG.
The adhesion between 11 and the electrode plates 12 and 13 is the net surface side 11a during papermaking.
Provides good adhesion, but the surface opposite to the net surface
In the case of 11b, since the surface of the separator 11 is not flat, the close contact with the electrode plate 13 is impaired, and sufficient adhesion cannot be obtained. For this reason, the liquid drops from the interface between the separator 11 and the electrode plate 13, and as a result, the liquid holding force of the separator 11 becomes low.

The present invention solves such a problem of the adhesion between the electrode plate and the separator, is excellent in the liquid holding force in the height direction, is less likely to cause stratification of the electrolytic solution, and has good long-life and good battery characteristics. It is an object of the present invention to provide a sealed and inexpensive sealed lead-acid battery.

[Means for Solving the Problems] In the sealed lead-acid battery according to claim (1), a separator made of a papermaking sheet manufactured by supplying a papermaking raw material onto a net and performing papermaking is arranged between the electrode plates. The sealed lead-acid battery of the present invention is characterized in that a separator composed of at least two papermaking sheets and arranged so that the net surface side thereof contacts the positive and negative electrode plate surfaces is used as the separator.

In the sealed lead-acid battery according to claim (2), the separator of the sealed lead-acid battery according to claim (1) is mainly composed of alkali-containing glass fibers having an average fiber diameter of 2 μm or less, and uses a glass fiber having an average fiber diameter of 11 μm or more as 0 to 10 μm. It is characterized by containing 20% by weight.

The sealed lead-acid battery according to claim (3) is characterized in that in the sealed lead-acid battery according to claim (2), the average glass fiber diameter of the separator is 0.4 to 0.9 μm.

[Operation] The separator of the sealed lead-acid battery of the present invention is formed by abutting two or more papermaking sheets such that the net surface side during papermaking, that is, the flat surface side is the electrode plate side. ,
Adhesion between the separator and the electrode plate is remarkably good. Therefore, the problem of liquid overflow in the height direction caused by poor adhesion between the separator and the electrode plate is eliminated, and the liquid holding force in the height direction is greatly improved. On the other hand, the surface opposite to the net surface is a non-flat surface, but when the non-flat surfaces are brought into contact with each other, the elasticity of the paper making sheet itself makes it come into close contact with the non-flat surface, and the same as one paper making sheet. Works.

In addition, when manufacturing the sealed lead-acid battery of the present invention, for example, it is only necessary to use two papermaking sheets obtained by making a paper according to a conventional method and set them simply by changing the arrangement. It can be manufactured easily and inexpensively.

Therefore, a stratified phenomenon is prevented, and a sealed lead-acid battery having a long life and excellent battery characteristics is provided at low cost.

In particular, according to the sealed lead-acid battery of the second aspect, particularly the third aspect of the present invention, a good capillary phenomenon due to the small-diameter glass fiber is obtained, and a remarkably excellent improvement effect of the liquid holding power is achieved.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing one embodiment of the separator arrangement of the sealed lead-acid battery of the present invention.

In the present embodiment, two papermaking sheets 10A and 10B are used as the separator 1, and the net side surfaces 10a and 1
0b is placed on the electrode plates 2 and 3 side by side.

As described above, the side surfaces 10a and 10b of the net at the time of papermaking are plates 2 and 3
By arranging the papermaking sheets 10A and 10B so as to be in contact with the sheet, the adhesion between the flat net side surfaces 10a and 10b and the electrode plates 2 and 3 is sufficiently ensured, and the flow of the liquid due to poor adhesion is prevented. On the other hand, the side surfaces 10c and 10d opposite to the net side surfaces 10a and 10b
Is a surface that is on the upper side during papermaking, and is a non-flat surface on which irregularities are formed as described above.When the non-flat surfaces are abutted and inserted between the electrode plates, the papermaking sheet 10A, Due to the elasticity of 10B itself, it comes into contact with good adhesion and acts in the same manner as one papermaking sheet.

In the present invention, the number of papermaking sheets disposed between the electrode plates as the separator is not limited to two, and may be three or more if the net side surface of the sheet is the electrode side. However, from the viewpoint of the manufacturing process, it is preferable to arrange two papermaking sheets as shown in FIG. In this case, a papermaking sheet having a thickness 1/2 of the desired separator thickness may be prepared and used in advance.

Next, a fiber configuration suitable for the separator of the sealed lead-acid battery of the present invention will be described.

In the present invention, in particular, a separator mainly containing alkali-containing glass fibers having an average fiber diameter of 2 μm or less, and containing 0 to 20% by weight of large-diameter glass fibers having an average fiber diameter of 11 μm or more is preferable.

When the alkali-containing silicate glass fiber is used, a water glass-like substance is generated on the surface of the fiber in a papermaking step of a manufacturing process, and the fibers adhere to each other due to the tackiness of the water glass-like substance. In the present invention, among alkali-containing silicate glass fibers, those having good acid resistance are preferably used because they are used for storage batteries. The degree of acid resistance is desirably that the weight loss is 2% or less when measured according to JISC-2202 in the state of glass fibers having an average fiber diameter of 1 μm or less. Further, the composition of such a glass fiber mainly contains 60 to 75% by weight of SiO ₂ and 8 to 20% of R ₂ O (alkali metal oxide such as Na ₂ O and K ₂ O) ( However, SiO ₂
+ R ₂ O 75 to 90%), Other example _{CaO, MgO, B 2 O 3} , A
Examples include one or two or more of l ₂ O ₃ , ZnO, and Fe ₂ O ₃ . Table 1 below shows an example of a preferable alkali-containing silicate glass.

Further, in the separator, when the diameter of such an alkali-containing glass fiber is excessively large, the maximum pore diameter of the separator becomes large, and the liquid holding power due to the capillary phenomenon is reduced, and the effect of preventing the electrolyte solution from being stratified is sufficiently obtained. Therefore, it is preferable to mainly use a fiber having an average fiber diameter of 2 μm or less. On the other hand, since glass fibers having a small diameter are expensive in terms of cost, glass fibers having a large diameter having an average fiber diameter of 11 μm or more may be added to the glass fiber in an amount of 20% by weight or less.

In addition, if the average fiber diameter of all the constituent glass fibers of the separator is large, the liquid holding power is reduced as described above. Therefore, the average glass fiber diameter is preferably 0.9 μm or less. Conversely, if the average glass fiber diameter is too small, the cost of the separator increases, so it is preferable that the average diameter be 0.4 μm or more, particularly 0.6 μm or more. That is, in claims (2) and (3), the average fiber diameter of the alkali-containing glass fiber used is 2
μm or less, the average glass fiber diameter is
Preferably 0.4 to 0.9 μm, more preferably 0.6 to 0.9 μm
And

In order to manufacture the separator used in the sealed lead-acid battery of the present invention, for example, the following method is advantageous.

That is, a relatively short glass fiber produced by the FA method (flame method), a centrifugal method or another method for producing short glass fiber is prepared, and defibrated, cut and dispersed by a pulper. Or, in the course of supplying this to the paper machine net,
The glass fibers may be cut short by an appropriate cutting means.

The cut glass fibers are made on a net. At this time, the pH in the disintegrator and / or the pH in the papermaking tank is preferably about 3 or less, for example, about 2.5. By performing disintegration and / or wet papermaking in such an acidic region, an adhesive layer of a water glass-like substance is formed on the surface of the glass fiber, which is then heated at a predetermined temperature, for example, 80 to 160 ° C.
By heating the glass fibers to each other, the glass fibers can be adhered to each other by the water glass-like substance on the surface. That is, when the glass fibers constituting the separator have an alkali-containing silicate glass composition, the alkali component and the silica component in the glass fibers react with water for dispersion in an acidic region of about pH 2.5, and water glass is used. A layer is formed on the surface of the glass fibers, and the water glass layer acts as an adhesive to firmly bond the glass fibers to each other.

In such a case, even if the length of the glass fiber is short and the entanglement between the fibers is relatively small, it is possible to obtain a sufficiently adhered and high-strength separator. The wet-formed glass fiber paper sheet is generally dried and manufactured along a drum or a dryer.

In the papermaking, a dispersant may be used when dispersing the fibers in water. Further, by spraying a dialkyl sulfosuccinate onto a wet-processed fiber paper, for example, a fiber paper on a papermaking net, and attaching 0.005 to 10% by weight to the glass fiber, dialkyl sulfosuccinate is obtained. The liquid retaining property of the separator can be improved by the hydrophilic property of the polymer. Instead of spraying dialkis sulfosuccinate as described above, it may be mixed with the dispersion water in the papermaking tank.

The thickness of the separator papermaking sheet of the sealed lead-acid battery of the present invention is not particularly limited, but is preferably not less than the average fiber length of the glass fibers.

 Hereinafter, experimental examples and examples will be described.

EXPERIMENTAL EXAMPLE 1 A 100% glass fiber papermaking sheet was formed using an alkali-containing glass fiber having an average fiber diameter of 0.8 μm and having the composition shown in Table A, and this papermaking sheet was cut into a size of 50 mm × 250 mm. . As shown in FIG. 3 (a), two cut sheets
The separators 21 and 22 were overlapped with each other such that the net surfaces 21a and 22a at the time of papermaking were on the outside (No. 1: Example of the present invention). Further, as shown in FIG. 3 (b), the net surface 21a of one of the sheets 21 at the time of papermaking and the other side 2 of the net surface at the time of papermaking of the sheet 22 are formed.
The separator was superposed such that both 2b and 2b were on the outside (No. 2: Comparative Example). Further, as shown in FIG. 3 (c), the sheets 21 and 22 were overlapped so that the net surfaces 21a and 22a at the time of papermaking were inside, thereby forming a separator (No. 3: Comparative Example). Then, two acrylic plates 23 and 24 (70 to 80 mm in width × 500 mm in length) which are opposed to each other via a spacer.
The above separator Nos. 1 to 3 are set between
o.1 to 3 were prepared. The packing density of each of the sheets 21 and 22 was 0.18 g / cm ³ .

Using the samples Nos. 1 to 3 obtained in this way, the permeation distance of the electrolytic solution was measured by the following method to examine the liquid holding power. The results are shown in FIG.

How to measure the penetration distance of electrolyte Soak the sample in water.

Excess water is removed by a dehydrator (dry suction).

The wet sample is set on the measuring jig.

Gently inject a sulfuric acid solution with a specific gravity of 1: 3 from above the acrylic plate with a pipette.

The injection of the sulfuric acid solution is set to 100 mm from the top of the sample, and the height is kept constant by adding liquid as needed.

The sulfuric acid solution is previously colored with red ink or methyl orange.

The permeation distance (fall distance) is measured with a steel measure at 5 minutes, 10 minutes, 30 minutes, and 60 minutes after the completion of the introduction of the electrolytic solution. Time is measured accurately with a stopwatch.

The measurement is performed three times for each sample.

Example 1 Three types of sealed lead-acid batteries SLA (a), SLA (b), and SLA (c) were manufactured with the same configuration as the separator used in Experimental Example 1, and a cycle life test was performed at a discharge depth of 75%. The results are shown in FIG. The configuration of the SLA (a) separator is as shown in FIG. 3 (a) and is according to the present invention. SLA (b) and SLA (c) are (b) in FIG. 3, respectively.
And (c), which are comparative examples.

4 and 5, it can be seen from FIG. 4 and FIG. 5 that when the sealed lead-acid battery of the present invention is used, the flow of the electrolytic solution is small and the liquid holding power in the height direction is greatly improved, so that the life performance is greatly improved. It is clear that.

[Effects of the Invention] As described above in detail, the sealed lead-acid battery of the present invention has a remarkably high holding force in the height direction of the electrolytic solution of the separator, so that the liquid holding properties in the vertical direction of the separator are equalized. In other words, since stratification is prevented, it has a very long life.

Therefore, not only a small-capacity sealed lead-acid battery but also a large-capacity sealed lead-acid battery having a high electrode plate has a long life with stable and excellent battery performance.

In particular, the sealed lead-acid battery of claim (2), especially claim (3), has a remarkably high effect, and can provide a sealed lead-acid battery that is easy to manufacture and extremely inexpensive.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an arrangement of a separator of a sealed lead-acid battery according to one embodiment of the present invention, FIG. 2 is a cross-sectional view showing a conventional example, and FIG. 3 is a side view showing a sample manufactured in Experimental Example 1. FIG. 4 is a graph showing the results of Experimental Example 1, and FIG.
7 is a graph showing the results of the above. 1 ... separator, 2, 3 ... electrode plate, 10A, 10B ... papermaking sheet.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsumi Kitagawa 6-6 Josai-cho, Takatsuki-shi, Osaka Yuasa Battery Co., Ltd. (72) Junji Mutoh 3-5-1, Doshumachi, Chuo-ku, Osaka-shi, Osaka No. Nippon Sheet Glass Co., Ltd. (72) Inventor Hiroki Kitawaki 3-5-1, Doshomachi, Chuo-ku, Osaka-shi, Osaka Prefecture No. 7 Nippon Sheet Glass Co., Ltd. No. 11 Inside Nippon Sheet Glass Co., Ltd.

Claims (3)

(57) [Claims] 1. A sealed lead-acid battery in which a separator made of a papermaking sheet manufactured by supplying a papermaking raw material on a net and forming the paper is disposed between the electrode plates, wherein the separator comprises at least two papermaking sheets. A sealed lead-acid battery comprising a sheet and arranged such that the net surface side during papermaking is in contact with the positive and negative electrode plate surfaces. 2. The separator according to claim 1, wherein the separator mainly comprises alkali-containing glass fibers having an average fiber diameter of 2 μm or less, and contains 0 to 20% by weight of glass fibers having an average fiber diameter of 11 μm or more.
A sealed lead-acid battery as described in the item. 3. The sealed lead-acid battery according to claim 2, wherein the average glass fiber diameter is 0.4 to 0.9 μm.