JP2005100794A - Sealed type lead-acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed type lead-acid battery in which the stratification of an electrolytic solution is hard to occur, and which has a long life and is highly reliable. <P>SOLUTION: (1) In the sealed type lead-acid battery which is provided with an electrode plate group composed of a positive electrode plate, a negative electrode plate, and a separator which has glass fibers as a main body and has mixed silica powder, the electrode plate group is assembled so that a compression force is 60 kpa or larger and the group is inserted into an electrical container. (2) In the sealed type lead-acid battery, the filling rate of the electrolytic solution as opposed to the total hole volume of the electrode plate group is made to be 92% or less. Or, (1) and (2) are combined. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sealed lead-acid battery, and more particularly to a long-life, high-reliability sealed lead-acid battery including a separator mainly composed of glass fiber.

  In sealed lead-acid batteries for automobiles and electric cars, glass fiber mat-like sheets have been put into practical use as separators, but as an attempt to improve the electrolyte retention by further increasing the liquid absorption of the separator, A combination of glass fiber and inorganic powder is known.

As such a separator, a fiber mainly composed of an alkali-containing silicate glass fiber having an average diameter of 0.5 to 1.0 μm and a powder mainly composed of silica powder having a specific surface area of 100 m ² / g or more are wet-mixed. There is a lead-acid battery separator in which the fibers are entangled and the powder particles are interposed between the fibers (see Patent Document 1).

JP-A-60-221954 (Claims, page 1, lower left column to second line to lower right column, seventh line, second page upper right column, first line to fifth line, second page, lower left column) (Line 4 to line 11, page 3, lower left column line 6 to line 11)

  In Patent Document 1, in a sealed lead-acid battery that uses a glass fiber mat-like sheet having an average diameter of 1 μm or less as a separator, when a large battery with an electrode plate height of, for example, 180 mm or more, is caused by the capillary action of fibers. Since the liquid absorption height is lowered, the amount of electrolyte held in the upper part of the mat-like sheet is considerably less than that in the lower part, so-called stratification of the electrolyte occurs, and there is a problem that desired performance cannot be obtained. Although described, the invention of Patent Document 1 includes this problem using an alkali-containing silicate glass fiber having an average diameter of 0.5 to 1.0 μm and a silica powder having a specific surface area of 100 m 2 / g or more. It is solved by adhering both from the water-glass-like adhesive layer formed on the surface of the fiber of the alkali silicate glass. By adjusting the pressing force of the electrode plate group and the filling rate of the electrolyte solution It is not a solution.

  In addition, in order to prevent stratification of the electrolyte, etc., in the sealed lead-acid battery, the electrode group separator is a retainer mainly composed of glass fibers having an average fiber diameter of 6 μm or more. Add up to 2% of inorganic powder that can hold the liquid, and press against the electrode plate group consisting of the positive electrode plate, negative electrode plate, and retainer at a pressure of 10 to 50 kg / dm 2 in the dry state before injecting the electrolyte. (See Patent Document 2).

JP-A-7-94206 (Claim 2, Claims, Paragraphs [0004] to [0005], Paragraph [0015])

Patent Document 2 shows that pressing the electrode plate group makes it difficult for a gap to be formed between the electrode plate and the retainer, thereby preventing stratification. However, the electrode plate group is reduced to 50 kg / dm ^2. It is described that the battery case swells when pressed with a pressure exceeding 1, and it is impossible to uniformly apply pressure. In addition, inorganic powder is added to the electrolyte and is mainly composed of glass fiber. In order to prevent stratification of the electrolyte, the positive electrode plate, the negative electrode plate, and the electrode plate group consisting of separators mainly made of glass fibers and added with inorganic powder are not added to the retainer (separator). Therefore, it cannot be said that compression is performed at a pressure exceeding 50 kg / dm ² (about 49 kpa).

As a conventional technology that gives a high pressing force to the electrode plate group (electrode group) of a lead storage battery, a clad positive electrode plate and a paste negative electrode plate are alternately laminated via a flat liquid retaining separator. A sealed clad lead storage battery in which a group of electrodes is pressed with a pressure of 40 kg / dm ² or more, and a liquid retaining separator is made of glass fibers having an average fiber diameter of 0.4 microns or less. A sealed clad lead storage battery (see Patent Document 3), which is the main component, and a pole group in which a glass mat is sandwiched between a positive electrode plate and a negative electrode plate, and the pressing force of the electrode group is set to 30 to 80 kg / dm ² A negative electrode absorption type sealed lead-acid battery (see Patent Document 4) housed in a battery case, and an electrode plate group obtained by laminating a positive electrode plate and a negative electrode plate via a mat separator made of glass fiber or the like were housed in the battery case. In a sealed lead-acid battery, the electrode plate group Has a sealed lead-acid battery (see Patent Document 5) in which a group pressure of 39200 N / m ² or more is applied in the stacking direction.

JP 5-198311 A (claims, paragraphs [0005], [0009])

JP-A-11-185564 (Claim 3 of the Claims, Paragraphs [0018] and [0023])

JP 2002-42857 A (Claim 1 of the claims, paragraphs [0014] to [0019], [0034] to [0038])

Patent Document 3 shows that when the degree of compression is 80 kg / dm ² (about 78.4 kpa), the contact area between the positive electrode plate and the separator increases, and the discharge capacity increases. There is no suggestion of a lifetime, and the invention of Patent Document 4 presses the positive electrode plate, suppresses elongation, and provides a long-life sealed lead-acid battery. but is intended to 80 kg / dm ^2, compressive force is specifically shown, is up to 35 kg / dm ² (about 34.3Kpa), the invention of Patent Document 5, the positive electrode plate and deformation of the negative electrode plate In order to suppress this, a group pressure is gradually applied as the electrode plate group is housed in the battery case, and a group pressure of 39200 N / m ² (39.2 kpa) to 98000 N / m ² (98 kpa) is applied. To improve the life and high rate discharge characteristics. However, when the electrode plate group is inserted into the battery case, the group pressure of 39.2 kpa or more is not applied to the electrode plate group at the beginning of insertion, and any invention also uses a separator containing silica powder. It is not used, nor is it intended to prevent stratification of the electrolyte.

  In addition, with respect to the amount of electrolyte, a sealed lead-acid battery in which the electrode plate group is impregnated and held with an electrolyte amount in the range of 0.9 to 1.0 times the volume of the electrode plate group stored in the battery case (Patent Document) 6).

JP 60-185370 A (Claims, page 2, upper left column, lines 15 to 18)

  In the invention of Patent Document 6, when the amount of the electrolyte is less than 0.9 of the electrode group space volume, the gas absorption reaction occurs, but the capacity is not reduced, and the range is 0.9 to 1.0 times. Therefore, it cannot be said that the amount of the electrolytic solution is less than 0.9 of the electrode plate group space volume.

  In a large capacity sealed lead-acid battery with a high electrode plate, a sealed lead-acid battery is used to prevent the uneven distribution of electrolyte (stratification of the electrolyte) above and below the battery, resulting in a high-performance and long-life battery. The amount of the electrolyte solution is reduced to an appropriate range, and the electrolyte solution inside the electrode plate is fixed to the positive / negative electrode plate and the pore of the retainer (see Patent Document 7).

Japanese Patent Application Laid-Open No. 60-243976 (claims 1st and 2nd paragraphs, from the lower right column on the first page to the fifth line to the upper left column on the second page, the fourth line)

  Patent Document 7 discloses that the amount of electrolyte per cell is 2.3 to 3.5 times the total pore volume of the positive and negative electrode plates, but an electrode plate including a retainer (separator). It is not shown how much of the total pore volume will be.

  By the way, in sealed lead-acid batteries for automobiles and electric cars that require high output, a technique for reducing the liquid resistance by, for example, shortening the distance between the electrode plates is used. However, if the distance between the electrode plates is shortened, an osmotic short-circuit may occur, and the silica powder described in the known literature has an effect of preventing the osmotic short-circuit as well as the effect of retaining the electrolyte solution. When a separator in which silica powder is mixed in glass fiber is used for a sealed lead-acid battery, it has been found that there is a problem that the electrolyte solution is stratified even in a battery having an electrode plate height of about 130 mm.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a long-life, high-reliability sealed lead-acid battery in which stratification of an electrolytic solution hardly occurs.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive studies, and as a result, made the electrolytic solution by making the filling rate of the electrolytic solution with respect to the compression force of the electrode plate group and the total pore volume of the electrode plate group within a specific range. The liquid stratification is less likely to occur, and it has been found that a sealed lead-acid battery having a long life and high reliability can be obtained.

  The present invention provides (1) a sealed lead-acid battery comprising a positive electrode plate, a negative electrode plate, and an electrode plate group mainly composed of glass fibers and mixed with silica powder. In the sealed lead-acid battery, the pressing force of the electrode plate group is 60 kpa or more. Thus, the sealed lead-acid battery is assembled and inserted into the battery case (Claim 1).

(2) The sealed lead-acid battery according to (1), wherein the electrode plate group is assembled so that the pressing force is 60 kpa or more and 140 kpa or less (Claim 2).

  The present invention also relates to (3) a sealed lead-acid battery comprising a positive electrode plate, a negative electrode plate, and an electrode plate group mainly composed of glass fibers and mixed with silica powder. A sealed lead-acid battery characterized in that the liquid filling rate is set to 92% or less (claim 3).

(4) The sealed lead-acid battery according to (3), wherein a filling rate of the electrolyte with respect to the total pore volume of the electrode plate group is 76% or more and 92% or less (claim 4).

  Further, the present invention is an electrode plate group consisting of a positive electrode plate, a negative electrode plate, and a separator mainly composed of glass fibers mixed with silica powder, which is a combination of the invention of (1) and the invention of (3). In the sealed lead-acid battery having the above structure, the electrode plate group is assembled so that the pressing force is 60 kpa or more and inserted into the battery case, and the filling rate of the electrolyte with respect to the total hole volume of the electrode plate group is set to 92% or less. This is a sealed lead-acid battery (claim 5).

(6) The electrode plate group is assembled so that the pressing force is not less than 60 kpa and not more than 140 kpa, and the filling rate of the electrolyte with respect to the total hole volume of the electrode plate group is not less than 76% and not more than 92%. The sealed lead-acid battery according to (5) (Claim 6).

  In the present invention, the pressing force of the electrode plate group is set to 60 kpa or more, the filling rate of the electrolyte solution to the electrode plate group total pore volume is set to 92% or less, or a combination of the two is used. It is possible to provide a sealed lead-acid battery that is less likely to be stratified (small difference in upper and lower electrolyte specific gravity between electrode plates), has a long life, and is highly reliable.

Embodiments of the present invention will be exemplified below, but the present invention is not limited to the following embodiments.
As glass fiber, the commercially available glass fiber normally used for the separator can be used. The average diameter is not limited, but is preferably 0.8 to 3.5 μm.

As the silica powder, dry method SiO ₂ , wet method SiO ₂ , diatomaceous earth and the like which are usually used for separators can be used, and among them, those having a specific surface area of 100 m ² / g or more are preferable. This is because the wetness to acid is good and the larger the specific surface area, the finer the powder becomes, and the better the dispersion stability in water.

  The content of the sulfuric acid-resistant silica powder is not limited, but can be 1 to 40% by weight of the separator weight, and preferably 5 to 30% by weight. If it is less than 1% by weight of the separator weight, the effect of improving the liquid absorbency is poor.

  Glass fiber and sulfuric acid-resistant inorganic powder are mixed and wet-made. However, in addition to glass fiber, synthetic fiber such as polyester fiber can be mixed.

  The pressing force of the electrode plate group is a pressure per unit area when the electrode plate group in a dry state is pressed in the stacking direction. The compression force gradually decreases from a dry state until the electrolyte filling rate reaches about 70%, and then gradually increases until the filling rate reaches about 80 to 90%, from which the electrolysis is performed. When the filling rate of the liquid is increased from about 80 to 90% to about 70%, the pressing force becomes lower than when the dry state is increased to about 70%. For example, when the compression force in the dry state is 60 kpa and the filling rate of the electrolyte is about 70%, the compression force becomes about 30 kpa, and when the filling rate is about 90% after that, the compression force becomes about 40 kpa. When the filling rate is about 70%, the compression force is about 20 kpa.

When the pressing force of the electrode plate group is 60 kpa or more, the specific gravity difference between the upper and lower electrolytes between the electrode plates becomes 0.04 d or less, and the cycle life is remarkably improved. If it is less than 60 kpa, the specific gravity difference between the upper and lower electrolytes between the electrode plates exceeds 0.04d and the cycle life is shortened even if the filling rate of the electrolyte solution with respect to the total pore volume of the electrode plate group is 92%.
Even if the compression force of the electrode plate group is 60 kpa or more, if the filling ratio of the electrolyte solution to the electrode plate group total pore volume is larger than 92%, the specific gravity difference between the upper and lower electrolyte solutions between the electrode plates exceeds 0.04d. In some cases, the specific gravity difference between the upper and lower electrolytes between the electrode plates is smaller than that when the pressing force of the electrode group is less than 60 kpa, and the cycle life is improved.
Although the upper limit of the pressing force of the electrode plate group is not limited, 140 kpa or less is preferable from the viewpoint of ease of assembly of the electrode plate group.

The electrode group total pore volume is obtained by the following formula, and the electrolyte filling ratio relative to the electrode plate group total void volume is obtained by dividing the volume of the electrolyte injected into the battery case by the electrode plate group total hole volume. Calculated by
Total plate hole volume = positive electrode plate hole volume + negative electrode plate hole volume + separator hole volume positive electrode plate hole volume = positive electrode plate volume-positive electrode active material volume-positive electrode lattice volume negative electrode plate hole volume = negative electrode Plate volume-negative electrode active material volume-negative electrode lattice volume separator pore volume = separator volume x (separator porosity)

When the filling rate of the electrolyte with respect to the total pore volume of the electrode plate group is set to 92% or less, the specific gravity difference between the upper and lower electrolyte solutions between the electrode plates becomes 0.04 d or less, and the cycle life is remarkably improved. If it is greater than 92%, even if the pressing force of the electrode plate group is 60 kpa, the specific gravity difference between the upper and lower electrolytes between the electrode plates exceeds 0.04 d, and the cycle life is shortened.
Even if the filling rate of the electrolyte solution with respect to the total pore volume of the electrode plate group is 92% or less, if the pressing force of the electrode plate group is less than 60 kpa, the specific gravity difference between the upper and lower electrolyte solutions between the electrode plates is 0.04d. Even in such a case, the difference in specific gravity of the upper and lower electrolytes between the electrode plates is smaller than that in the case where the filling rate of the electrolyte solution with respect to the total pore volume of the electrode plate group is larger than 92%, and the cycle life is reduced. Will improve.
The lower limit of the filling rate of the electrolytic solution is not limited. However, when it is less than 76%, the amount of sulfuric acid (the amount of the electrolytic solution) decreases, the discharge capacity decreases, and the contact between the electrolytic solution and the active material. Since the area is reduced and the high rate discharge characteristics are lowered, it is preferable to be 76% or more.

  Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited by the following description, and the positive electrode plate, the negative electrode plate, the positive electrode active material, the negative electrode active material of the test method and the constituent battery are not limited thereto. The substance, separator, electrolyte, battery shape, etc. are arbitrary.

The sealed lead-acid battery of this example has five unformed positive plates (thickness 1.3 mm) and six negative plates (thickness 1.1 mm) having a height of 130 mm and a width of 75 mm, glass fiber, and 10% by weight. After assembling the electrode plate group so that the pressing force is every 20 kpa in the range of 20 to 140 kpa, the electrode plate is assembled into a battery case. It was inserted into the inside, and an electrolytic solution was injected to form an electrode plate in the battery case.
The electrode group total pore volume per cell of the battery is 142 ml, the electrolyte filling rate with respect to the electrode plate group total hole volume is 92%, and the electrolyte specific gravity of the finished battery after the formation is 1.300d. It was formed to become.
In addition, the electrode plate group total pore volume was calculated as follows.
Positive electrode plate pore volume = positive electrode plate volume-positive electrode active material volume-positive electrode grid volume
= 63.4 cm ³ -19.5 cm ³ -16.4 cm ³
= 27.5cm3
Positive electrode plate volume: (13.0 cm × 7.5 cm × 0.13 cm) × 5 = 63.4 cm ³
The positive electrode active material volume: 19.5cm ³ (weight 36 g ÷ density 9.2g / cm ³⁾ × 5 MaiTadashikyoku grid volume: 3.28cm ³ × 5 sheets = 16.4 cm ³
Negative electrode plate pore volume = negative electrode plate volume-negative electrode active material volume-negative electrode lattice volume
= 64.4 cm ³ -15.6 cm ³ -15.3 cm ³
= 33.5cm ³
Negative electrode plate volume: (13.0 cm × 7.5 cm × 0.11 cm) × 6 sheets = 64.4 cm ³
Negative electrode active material volume: 15.6cm ³ (weight 29.3 g ÷ density 11.3g / cm ³⁾ × 6 Maimakekyoku grid volume: 2.55 cm ³ × 6 Like = 15.3 cm ³
Separator pore volume = separator volume x separator porosity
= 90cm ³ × 90% = 81cm ³
Separator volume: (8.4 cm × 26.8 cm × 0.08 cm) × 5 sheets = 90 cm ³
Separator porosity: 90%
Total hole volume of electrode plate group = positive electrode plate hole volume + negative electrode plate hole volume + separator hole volume
^{= 27.5cm 3 + 33.5cm 3 + 81cm} 3
= 142cm ³
These batteries were subjected to a 5-hour rate initial capacity test at 25 ° C., and then the batteries were disassembled to measure the electrolyte specific gravity at the upper and lower parts of the electrode plate, and the specific gravity difference was calculated.
FIG. 1 shows the relationship between the pressing force of the electrode plate group and the upper and lower electrolyte specific gravity differences between the electrode plates.

According to FIG. 1, when the filling rate of the electrolytic solution is 92%, when the pressing force of the electrode plate group is 60 kpa or less, the upper and lower electrolyte specific gravity difference is 0.04d or more, and the pressing force of the electrode plate group is Is 60 kpa or more, the upper and lower electrolyte specific gravity difference between the electrode plates is 0.04 d or less.
Further, even if the pressing force of the electrode plate group is 60 kpa or more, if the filling rate of the electrolyte is greater than 92%, the specific gravity difference between the upper and lower electrolytes between the electrodes may exceed 0.04d. Even in this case, it is clear that the specific gravity difference between the upper and lower electrolytes between the electrode plates is smaller than when the pressing force of the electrode plate group is less than 60 kpa.
The reason why the pressing force of the electrode plate group is not more than 140 kpa is that the current device exceeds 140 kpa in the electrode plate group insertion process in which the electrode plate group is inserted into each cell chamber of the battery case during battery assembly. This is because the pressing force could not be applied, and there is no limitation as long as it is possible to apply a pressing force of 140 kpa or more on the apparatus.

The same positive electrode plate, negative electrode plate and separator as in Example 1 were used. The compression force of the electrode plate group was 60 kpa, and the electrolyte filling rate was every 4% within the range of 76 to 100%. Chemical conversion was performed so that the liquid specific gravity was 1.300 d.
About these batteries, the specific gravity of electrolyte solution of the upper part and lower part of an electrode plate was measured similarly to Example 1, and the specific gravity difference was computed.
FIG. 2 shows the relationship between the filling rate of the electrolyte with respect to the total pores and the upper and lower electrolyte specific gravity differences between the electrode plates.

According to FIG. 2, when the pressing force of the electrode plate group is 60 kpa, when the electrolytic solution filling rate is 92% or more, the upper and lower electrolytic solution specific gravity difference is 0.04d or more, and the electrolytic solution filling rate is Below 92%, the upper and lower electrolyte specific gravity difference between the electrode plates was 0.04 d or less.
Moreover, even if the filling rate of the electrolyte solution is 92% or less, if the pressing force of the electrode plate group is less than 60 kpa, the specific gravity difference between the upper and lower electrolyte solutions between the electrode plates may exceed 0.04d. Even in such a case, it is clear that the specific gravity difference between the upper and lower electrolyte solutions between the electrode plates is smaller than when the filling rate of the electrolyte solution is greater than 92%.

The batteries shown in Example 1 and Example 2 were subjected to a DST (dynamic stress test) life test at an environmental temperature of 25 ° C.
FIG. 3 shows the relationship between the upper and lower electrolyte specific gravity difference between the electrode plates and the cycle life.

According to FIG. 3, in the batteries where the upper and lower electrolyte specific gravity difference between the electrode plates exceeds 0.04d (0.06d, 0.07d), the cycle life decreases greatly as the specific gravity difference increases. It was found that the cycle life of the battery having a difference in specific gravity between the upper and lower electrolyte plates of 0.04 d or less was significantly improved.
The reason for the decrease in cycle life performance is that when the difference in specific gravity between the upper and lower electrolyte plates increases, the lower part of the electrode plate is difficult to be charged due to its high specific gravity. A battery is produced, and the lower part of the electrode plate is discharged. As a result, the lower part of the electrode plate is discharged by the concentration battery, but it is difficult to be charged, so that the lower part of the negative electrode plate is susceptible to sulfation.

It is a figure which shows the relationship between the compression force of an electrode group, and the electrolyte solution specific gravity difference between the upper and lower sides between electrode plates. It is a figure which shows the relationship between the filling rate of the electrolyte solution with respect to electrode plate group total void | hole volume, and the electrolyte solution specific gravity difference of the upper and lower sides between electrode plates. It is a figure which shows the relationship between the electrolyte solution specific gravity difference between electrode plates, and cycle life.

Claims (6)

  In a sealed lead-acid battery including a positive electrode plate, a negative electrode plate, and an electrode plate group mainly composed of glass fibers and mixed with silica powder, the electrode plate group is assembled to a battery case so that the pressing force is 60 kpa or more. A sealed lead-acid battery characterized by being inserted.   2. The sealed lead-acid battery according to claim 1, wherein the electrode plate group is assembled so that a pressing force is 60 kpa or more and 140 kpa or less.   In a sealed lead-acid battery including a positive electrode plate, a negative electrode plate, and an electrode plate group mainly composed of glass fibers and mixed with silica powder, the filling rate of the electrolytic solution with respect to the total hole volume of the electrode plate group is set to 92% or less. A sealed lead-acid battery.   The sealed lead-acid battery according to claim 3, wherein a filling rate of the electrolytic solution with respect to the total pore volume of the electrode plate group is 76% or more and 92% or less.   In a sealed lead-acid battery having a positive electrode plate, a negative electrode plate, and a sealed lead-acid battery comprising a separator composed mainly of glass fiber and mixed with silica powder, the electrode plate group is assembled to a battery case so that the pressing force is 60 kpa or more. A sealed lead-acid battery that is inserted and has an electrolyte filling rate of 92% or less relative to the total pore volume of the electrode plate group. 6. The electrode plate group is assembled so that the pressing force is 60 kpa or more and 140 kpa or less, and the filling ratio of the electrolyte with respect to the total hole volume of the electrode plate group is 76% or more and 92% or less. The sealed lead-acid battery described in 1.