JP2003308819A - Separator for sealed lead storage battery, its manufacturing method, and sealed lead storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator attaining high following characteristic to expansion and contraction of polar plates, and to provide its manufacturing method and a sealed lead storage battery with the same separator. <P>SOLUTION: This separator is characterized in comprising a porous mat sheet having acid-resistance glass fibers as its main components, and having a repetitive restoring force, or a value of (T<SB>1</SB>-T<SB>50</SB>)/T<SB>20</SB>×100 of 20% or more, and the tensile strength 3 N/10 mm<SP>2</SP>. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is particularly applicable to a depth of discharge of 50.
% It is used for the cycle applications where charging and discharging are repeated more than 100%, and is related to the improvement of a large sealed lead-acid battery in which the electrode plate group is arranged horizontally in the battery case, and follows the expansion and contraction of the electrode plate. The present invention relates to a separator, a manufacturing method thereof, and a sealed lead-acid battery using the separator and having a long cycle life.

[0002]

2. Description of the Related Art In a sealed lead-acid battery for cycle use, when charge and discharge are repeated, a difference in specific gravity occurs in the electrolyte concentration above and below a separator holding an electrolyte. That is, a stratification phenomenon occurs in which the electrolytic solution concentration at the bottom of the separator increases. As a result, it becomes a concentrated battery above and below the battery, and self-discharge occurs, which shortens the cycle life. In order to prevent this, measures such as using a separator made of glass fiber as thin as possible and introducing silicate powder have been made.However, the finer the glass fiber, the more expensive it is, and the price is low for practical use. Due to technical problems, the application range is narrowed down and limited to special applications. Further, when the silicic acid powder is introduced, the space for holding 90% or more of the electrolytic solution obtained with the glass fiber is filled, and the battery capacity is lowered and the oxygen gas generated at the anode is smoothly transmitted to the cathode. However, there is a problem that the internal pressure of the battery becomes high, the gas and the electrolytic solution escape from the gas valve and the battery wall, the amount of the electrolytic solution decreases, and the battery life is shortened. Therefore, in a large-sized sealed lead-acid battery for cycle use, a method of horizontally arranging the electrode plate group in a battery case is adopted as a method of preventing the stratification phenomenon. On the other hand, as a new method of using such a large-sized sealed lead-acid battery for cycle use, application to a storage system for leveling the electric power by using inexpensive nighttime electric power has recently been considered. In this application, the battery is repeatedly charged and discharged during one day, and the depth of discharge is 70% and used for several hours.
In addition, it becomes a severe use condition that rapid charging is performed within 10 hours. Therefore, PbO ₂ (lead oxide) and Pb (pure lead) in the electrode plate are converted to PbSO ₄ (lead sulfate),
Since the expansion and contraction of the electrode plate are repeated every day, a separator that can follow the pressure fluctuation due to the change of the electrode plate is required. However, in a large sealed lead-acid battery in which the plate group is arranged horizontally in the battery case, the separator bears the weight of the plate group itself, so the separator is subject to a greater pressure. . Therefore, the separator is required to have a higher degree of compliance with the expansion and contraction of the electrode plate.

[0003]

Therefore, the present invention provides a separator capable of achieving a higher degree of compliance with expansion and contraction of an electrode plate, a method for manufacturing the separator, and a sealed lead-acid battery equipped with such a separator. The purpose is to do.

[0004]

Means for Solving the Problems The present inventors have
As a result of diligent study to achieve the
From glass fiber mat obtained by wet papermaking of body material
In a sealed lead-acid battery separator consisting of
Good followability to the expansion and contraction of rebound
In order to achieve this, when repeatedly applying pressure to the separator,
Thickness restoration (repeated restoration) is used as an index, and this is set to 20% or less.
I found it necessary to do the above. And anti
By setting the restoration stability to 20% or more,
When handling during manufacturing, during the battery assembly process, or when
When gas is generated during pond formation, the separator may break.
At least the mechanical strength to prevent rubbing
Tensile strength is 3N / 10mm²You know that you need more
It was. In addition, in the method of manufacturing the separator, p
Papermaking using an acidic solution with H of about 2.5 to 3.0
As a result, fibers are made of silicate that is eluted from the glass during papermaking.
Adhesion is made at the intersection (= inorganic binder
Effect), but to make iterative restoration more than 20%
Is a little to suppress this inorganic binder effect,
Therefore, it is necessary to set the pH during papermaking to a slightly higher value.
I understood. That is, the pH of the papermaking solution is 3.5 to 4.0.
Wet papermaking of the separator by setting it in a specific range
And the repeatability is 20% or more and the tensile strength is 3N.
/ 10 mm ²The sealed lead acid battery separator above
It was found that it can be obtained. The sealed lead storage of the present invention
The battery separator was made based on this knowledge.
As described in claim 1, mainly acid-resistant glass fiber is used.
The porous mat-like sheet with
₁-T₅₀) / T₂₀The value of × 100 is 20% or more, and
Tensile strength is 3N / 10mm²It is characterized by the above
It Also, the production of the sealed lead-acid battery separator of the present invention
The method is a sealed lead-acid battery separator according to claim 1.
The manufacturing method of
An acidic solution having a pH of 3.5 to 4.0 during wet papermaking
It is characterized in that papermaking is performed by using. Also, the present invention
The sealed lead-acid battery according to claim 1, according to claim 1,
Obtained by the manufacturing method according to claim 2 or claim 2.
It is characterized by using a lead-acid battery separator.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The sealed lead-acid battery separator of the present invention comprises a porous mat-like sheet mainly composed of acid-resistant glass fiber, and has a repeated restoration property (T ₁ -T ₅₀ ) /
The value of T ₂₀ × 100 is 20% or more and the tensile strength is 3N.
/ 10 mm ² or more is required.

The repetitive restoration property mentioned here will be described below. [Repetitive Restorability] Ten separators cut into 10 cm × 10 cm are stacked and used as a sample. A sample sufficiently impregnated with water was placed in a polyethylene bag, which was sandwiched between a fixed plate and a pressure plate composed of a movable plate of a horizontal compression tester (horizontal load measuring device MODEL-2152DW manufactured by Aiko Engineering Co., Ltd.) to form a movable plate. Is moved to the fixed plate side at a speed of 1 mm / min, the sample is pressurized and compressed to 50 kPa, and the movable plate is stopped.
Hold for a second. When compressing the sample to 50 kPa, the distance between the pressure plates at the time of 20 kPa, which is an intermediate step, that is, the thickness of the sample was measured and designated as T ₂₀ . After holding for 60 seconds, move the movable plate at a speed of 1 mm / min in the direction opposite to that at the time of pressurization, and the pressure between the pressure plates is 1 kP.
It was opened to a and the movable plate was stopped and held for 60 seconds. Subsequently, the compression (50 kPa) and the opening (1 kPa) operations were repeated while sandwiching a holding period of 60 seconds for each operation, and a total of 10 repeated operations were performed. After completion of this repeated operation, the distance between the pressure plates at 1 kPa pressurization, that is, the thickness of the sample, and the distance between the pressure plates at 50 kPa pressurization, that is, the thickness of the sample were measured, and these were measured as T ₁ , T ₅₀ did. The repetitive restoration property was calculated by the following formula. Repetitive resilient _{= (T 1 -T 50) /} T 20 × 100

Iterative restoration (T ₁ -T ₅₀ ) / T ₂₀ ×
The value of 100 needs to be 20% or more,
The repetitive recoverability of the conventional sealed lead-acid battery separator for general use is about 10 to 18%, and in the present invention, as described above, it is particularly used for cycle applications in which charge / discharge is repeated at a discharge depth of 50% or more. It is used for large sealed lead-acid batteries in which the electrode plate group is arranged horizontally in the battery case, and has a higher degree of followability to expansion and contraction of the electrode plate. This is also because high repeatability is required. In cycle applications, the higher the repeatability is, the better the followability to expansion and contraction of the electrode plate is. Therefore, the higher the repeatability is, the better. However, if the repeatability is too high, the tensile strength is decreased. Therefore, it is necessary to set the upper limit of the repeatability to a range in which a tensile strength of 3 N / 10 mm ² or more can be secured. Further, here, in consideration of the balance with the tensile strength having such a contradictory tendency, a minimum required value of 20% or more for achieving the above-mentioned purpose (high followability to expansion and contraction of the electrode plate) However, if it is 22% or more, the above object can be more sufficiently achieved.

The tensile strength is 3 N / 10 mm.²Above
What was needed was handling during separator manufacturing
Or during the battery assembly process or during battery formation.
To the extent that the separator does not break, etc.
As the mechanical strength of
It is set as the minimum required value in consideration of
is there. Separator for conventional sealed lead acid batteries for general use
4N / 10mm ²From the above, the book
Also in the separator of the invention, 4 N / 10 mm²Above
More preferably. In the case of the above-mentioned iterative restoration,
The higher the tensile strength, the better, but the higher the tensile strength,
On the contrary, if it passes, it will decrease the iterative resilience, so
The upper limit of tensile strength is within the range where it is possible to secure a repeatability of 20% or more.
You need to surround it.

The method for producing the sealed lead-acid battery separator of the present invention is not particularly limited as long as the above-mentioned separator characteristics (repeating resilience and tensile strength) are satisfied. When fiber-fiber adhesion is performed by the eluted silicate, that is, in the case of the acidic papermaking method, it is preferable to perform wet papermaking using an acidic solution having a pH of 3.5 to 4.0. this is,
If the pH at the time of papermaking is less than 3.5, the binder effect is enhanced and the interfiber adhesion becomes too strong, and the target repetitive restoration property cannot be obtained, which is not preferable, and if the pH exceeds 4.0, the binder effect is obtained. This is because it becomes low and the adhesion between fibers becomes too weak to obtain the target tensile strength, which is not preferable.

[0010]

EXAMPLES Next, specific examples of the present invention will be described together with conventional examples and comparative examples. (Examples 1 to 3, Conventional Examples 1 to 2, Comparative Examples 1 to 5) As shown in Table 1, 50% by mass of glass fibers having an average fiber diameter of 0.7 µm and glass fibers 50 having an average fiber diameter of 4.0 µm. mass%
Using the above materials, the pH conditions were changed as shown in Table 1 by a normal wet papermaking method to produce the sealed lead-acid battery separators of Examples 1 to 3, Conventional Examples 1 and 2, and Comparative Examples 1 to 5. . Regarding the pH control method, in the conventional examples 1 and 2, since the pH is 2.5 to 3.0 and the pH control is relatively easy, it can be produced using a low-precision pH control device. did it. On the other hand, in Examples 1 to 3, since the pH was 3.5 to 4.0 and the pH control was relatively difficult, a highly accurate pH control device was used.

With respect to each of the obtained separators, the separator characteristics are density, repetitive restoration property, tensile strength, air permeability,
Each item of the degree of liquid injection disintegration and appearance, and the battery characteristics,
Each item of the initial capacity and the number of cycles was measured or confirmed and evaluated. The results are shown in Table 1. In addition, p at the time of papermaking
The H control was performed as follows. The papermaking process of the separator is roughly divided into a pulper for disaggregating the raw material, a stock tank for storing the disaggregated raw material, and a papermaking section for forming the separator structure. The pH was controlled at each of the pulper tank, the stock tank and the papermaking section so that the pH values at the three locations were always constant. The papermaking pH shown in Table 1 indicates the pH value in this papermaking part, and is the value measured immediately before forming the separator structure in the papermaking part. Further, the pH value in the papermaking part has a great influence on the separator characteristics.

The method of evaluating other characteristic items was as follows. (Characteristic of Separator) [Repeatability] By the method described above. [Tensile Strength] The tensile strength was measured according to SBA S 0402. [Air permeability (300 cc)] The air permeability was measured according to JIS P 8117. [Disintegration of liquid injection] After immersing the separator in sulfuric acid for 1 hour,
Observing the state of the separator when lifted with tweezers, those with no shape deformation and no cracks or tears are marked with "○", those with shape deformation but no cracks or tears are marked with "△", cracks or tears There was such a phenomenon that the shape could not be maintained, and it was designated as “x”. The degree of liquid injection disintegration is an evaluation item taken as an index as to whether or not the separator does not disintegrate due to gas generated during battery formation. [Appearance] An observation of the unevenness of the separator surface.
With the separator of Conventional Example 1 as a reference, those having the same degree as this were marked with “◯”, those having slightly more unevenness than the conventional example were marked with “Δ”, and those having more unevenness than the conventional example were marked with “x”. In addition, as the unevenness is smaller and the surface is smoother, the adhesion to the electrode plate is improved and the battery characteristics can be sufficiently obtained. (Battery characteristics) A large sealed lead-acid battery (2V-20) in which the above-mentioned separator has the electrode plate group horizontally arranged in the battery case.
0Ah) and tested. [Initial capacity] The initial capacity of the battery was measured and expressed as a relative value with the value of Conventional Example 1 set to 100. The initial capacity may not be sufficiently drawn out depending on the unevenness of the separator and the degree of liquid injection collapse. [Cycle number] The battery life was measured under the condition that the discharge depth was 70% and the operation of one charge and one discharge was one cycle. The value of Conventional Example 1 was set to 100, and the relative value is shown. did. The number of cycles becomes the longest when all three characteristic items such as repetitive restoration property, degree of liquid injection collapse, and appearance (surface irregularity state) are excellent.

[0013]

[Table 1]

As is clear from Table 1, Examples 1 to 3
In the separator of No. 2, since the repeatability is 20% or more and the tensile strength is 3N / 10 mm ² or more, the number of cycles is about 20 times compared with the conventional separator.
It was possible to improve by more than%. In addition, Examples 1 to 3
In the separator of No. 3, the wet-papermaking is performed by setting the pH at the time of papermaking to a specific range of 3.5 to 4.0, so that the repeatability is 20% or more and the tensile strength is 3N / 10 mm ² or more. I was able to.

[0015]

As described above, according to the sealed lead-acid battery separator of the present invention, the sheet is made of a porous mat-like sheet mainly composed of acid-resistant glass fiber, and has a repetitive restoration property of 20% or more and a tensile strength. Since the separator has a strength of 3 N / 10 mm ² or more, it is a large-sized sealed lead acid battery in which the electrode plate group is horizontally arranged in the battery case, which is particularly used for cycle applications in which charge / discharge is repeated at a discharge depth of 50% or more. Even when used as a separator, it can follow the expansion and contraction of the electrode plate while maintaining the strength that does not cause separator breakage during gas production during handling during separator manufacturing or during battery assembly process or during battery formation. Can be exhibited and the battery life can be extended. Also,
The sealed lead acid battery separator of the present invention has a pH of 3.5.
Since the fiber-to-fiber adhesion can be performed by the silicate that is eluted from the glass at the time of papermaking, by producing by wet papermaking using a papermaking solution set to a specific range of to 4.0,
Repeated recovery is 20% or more and tensile strength is 3N / without the need for separate mixing and post-addition of binder materials.
A separator having a size of 10 mm ² or more can be easily obtained.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takuo Mitani             630 Tarui-cho, Fuwa-gun, Gifu Japan Inorganic Stock Association             Inside the company Tarui factory F-term (reference) 5H021 BB08 CC01 CC02 CC08 EE28                       HH01 HH06 HH07                 5H028 AA01 BB15 CC07 CC21 EE04                       FF02 FF04 HH01 HH03

Claims (3)

[Claims] 1. A porous mat-like sheet mainly composed of acid-resistant glass fiber, which has a repeated restoring property (T ₁ -T ₅₀ ) /
The value of T ₂₀ × 100 is 20% or more and the tensile strength is 3N.
/ 10 mm ² or more, a sealed lead-acid battery separator. 2. The method for producing a sealed lead-acid battery separator according to claim 1, wherein the acidic solution having a pH of 3.5 to 4.0 is used in the wet papermaking of an acid resistant glass fiber-based material. A method for manufacturing a sealed lead-acid battery separator, characterized in that the papermaking is performed using. 3. A sealed lead-acid battery using the lead-acid battery separator obtained by the method according to claim 1 or 2.