JP2019102282A - Lead storage battery - Google Patents

Abstract

To provide a lead storage battery capable of properly suppressing a penetration short circuit.SOLUTION: A lead storage battery includes: a positive electrode plate 10; a negative electrode plate 9; a separator 11 disposed between the positive electrode plate 10 and the negative electrode plate 9; and a film body 18 disposed between the positive electrode 10 or the negative electrode 9, and the separator 11. The film body 18 includes fibers of a polymer that includes acrylonitrile as a monomer unit.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a lead storage battery.

  Lead-acid batteries are widely used in industrial applications, for example, as batteries for automobiles, backup power supplies, and main power supplies for electric vehicles. In recent automobiles, an idling stop and start system (hereinafter referred to as "ISS") is adopted to stop the engine at the time of power generation control, waiting for a signal, etc. for the purpose of carbon dioxide emission control measures, fuel economy etc. It has become so.

  During idling stop, power generation by the alternator is not performed, so all power to the electric equipment is supplied from the lead storage battery, and in the lead storage battery, discharge deeper than before is performed. In addition, since the power generation of the alternator is controlled even during traveling, the state of charge is insufficient.

When the deep discharge and the insufficient charge are repeated in the lead storage battery, the battery is gradually overdischarged, and the specific gravity of the electrolytic solution is lowered by the significant consumption of the sulfate ion (SO ₄ ²⁻ ). When the specific gravity of the electrolyte solution decreases, the solubility of lead sulfate (PbSO ₄ ) generated in the negative electrode plate increases, and lead ions (Pb ²⁺ ) easily permeate into the pores in the separator. When charged from the overdischarged state, Pb ²⁺ may be precipitated in the pores of the separator, and a conductive part may be generated between the negative electrode plate and the positive electrode plate (this phenomenon is called a penetration short circuit). If an osmotic short circuit occurs, there is a risk that the lead storage battery may suddenly break. Therefore, in order to improve the reliability of the lead storage battery, it is required to suppress the osmotic short circuit. In an ISS vehicle that is likely to be in an overdischarged state, a technique to suppress the osmotic short circuit is particularly important.

  As a technique for suppressing such an osmotic short circuit, for example, Patent Document 1 has a first fibrous layer, a second fibrous layer, and a microporous polymer layer sandwiched between two fibrous layers, and is microporous A separator is disclosed characterized in that the average pore size of the polymer layer is less than 1 μm and the thickness of the first fibrous layer is at least 0.6 mm.

Japanese Patent Application Publication No. 2005-503649

  However, in the lead storage battery using the separator as described in Patent Document 1, it can not be said that the permeation short circuit is sufficiently suppressed. Then, an object of this invention is to provide the lead storage battery which can suppress an osmotic short circuit suitably.

The inventors of the present invention have found that penetrative short circuit can be suitably suppressed by arranging a film body containing a fiber of an acrylonitrile-based polymer in the vicinity of a positive electrode or a negative electrode. The present inventors speculate that the acrylonitrile-based polymer can suppress the permeation short circuit by reducing the permeation of Pb ²⁺ into the separator during the overdischarge.

  That is, in one aspect, the present invention provides a positive electrode plate, a negative electrode plate, a separator disposed between the positive electrode plate and the negative electrode plate, and a membrane disposed between the positive electrode plate or the negative electrode plate and the separator. The membrane body is a lead acid battery including a fiber of a polymer having acrylonitrile as a monomer unit.

  In one aspect, the above-described polymer is a copolymer.

  In one aspect, the membrane has pores with an average pore size of 20 μm or less.

  In one aspect, the ratio of fibers having a fiber diameter of less than 5 μm to fibers is 60% or more. In one aspect, the ratio of fibers having a fiber diameter of 5 μm to 10 μm in the fibers is 10% or more.

  In one aspect, the separator is a bag-like separator, and the positive electrode plate or the negative electrode plate and the membrane are accommodated in the separator.

  In one aspect, the thickness of the membrane is 0.3 mm or less.

  According to the present invention, osmotic short circuit can be suitably suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows the whole structure and internal structure of the lead acid battery which concern on one Embodiment. It is a perspective view which shows the electrode group of the lead acid battery which concerns on one Embodiment. It is a schematic cross section which shows the arrow cross section along the III-III line in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

  FIG. 1 is a perspective view showing an entire configuration and an internal structure of a lead-acid battery according to an embodiment. As shown in FIG. 1, the lead storage battery 1 according to this embodiment includes a battery case 2 whose upper surface is open, and a lid 3 for closing the battery case 2. The battery case 2 and the lid 3 are made of, for example, polypropylene. The lid 3 is provided with a negative electrode terminal 4, a positive electrode terminal 5, and a liquid plug 6 for closing a liquid injection port provided in the lid 3. Although the lead storage battery 1 shown in FIG. 1 is a liquid lead storage battery, the lead storage battery may be a control valve type lead storage battery.

  Inside the battery case 2, an electrode group 7, a negative electrode post 8 connecting the electrode group 7 to the negative electrode terminal 4, a positive electrode column (not shown) connecting the electrode group 7 to the positive electrode terminal 5, diluted sulfuric acid And the electrolyte solution of

  FIG. 2 is a perspective view showing the electrode group 7. As shown in FIG. 2, the electrode group 7 includes a plate-shaped negative electrode plate 9, a plate-shaped positive electrode plate 10, and a separator 11 disposed between the negative electrode plate 9 and the positive electrode plate 10. The electrode group 7 has a structure in which a plurality of negative electrode plates 9 and a positive electrode plate 10 are alternately stacked in a direction substantially parallel to the opening surface of the battery case 2 via the separators 11. That is, negative electrode plate 9 and positive electrode plate 10 are arranged such that their main surfaces extend in the direction perpendicular to the opening surface of battery case 2.

The negative electrode plate 9 has a negative electrode current collector 12 and a negative electrode material 13 held by the negative electrode current collector 12 and containing metallic lead (Pb) as an active material. The positive electrode plate 10 has a positive electrode current collector 14 and a positive electrode material 15 held on the positive electrode current collector 14 and containing lead dioxide (PbO ₂ ) as an active material. The ear portions 12 a of the negative electrode current collectors 12 in the plurality of negative electrode plates 9 are collectively welded by the negative electrode side strap 16. Similarly, the ear portions 14 a of the positive electrode current collectors 14 in the plurality of positive electrode plates 10 are collectively welded by the positive electrode side strap 17. The negative electrode side strap 16 and the positive electrode side strap 17 are connected to the negative electrode terminal 4 and the positive electrode terminal 5 via the negative electrode column 8 and the positive electrode column, respectively.

  FIG. 3 is a schematic cross-sectional view showing a cross section taken along line III-III in FIG. As shown in FIG. 3, in one embodiment, a film body 18 is provided between the negative electrode plate 9 and the separator 11.

The separator 11 is formed, for example, in a bag shape, and in one embodiment, the negative electrode plate 9 and the membrane 18 are accommodated in the separator 11. Examples of the material forming the separator 11 include polyethylene (PE), polypropylene (PP) and the like. The separator 11 may be obtained by adhering inorganic particles such as SiO ₂ and Al ₂ O ₃ to a woven fabric, a non-woven fabric, a porous film or the like formed of these materials.

  The thickness of the separator 11 is preferably 0.1 mm or more and 0.5 mm or less, more preferably 0.2 mm or more and 0.3 mm or less. When the thickness of the separator 11 is 0.1 mm or more, the strength of the separator can be secured. When the thickness of the separator 11 is 0.5 mm or less, an increase in internal resistance of the battery can be suppressed.

  The average pore diameter of the separator 11 is preferably 10 nm or more and 500 nm or less, more preferably 30 nm or more and 200 nm or less. When the average pore diameter of the separator 11 is 10 nm or more, the sulfate ion can be suitably passed, and the diffusion speed of the sulfate ion can be secured. If the average pore diameter of the separator 11 is 500 nm or less, the growth of lead dendrite is suppressed, and a short circuit hardly occurs.

  In one embodiment, the film body 18 is provided in close contact with the negative electrode plate 9 so as to cover the surface of the negative electrode plate 9. The membrane 18 may be, for example, a sheet or a bag. When the film body 18 is in the form of a sheet, the film body 18 covers the surface of the negative electrode plate 9 so as to be wound around the negative electrode plate 9. When the membrane 18 is in the form of a bag, the negative electrode plate 9 is accommodated in the membrane 18.

  The membrane 18 contains fibers of a polymer having acrylonitrile as a monomer unit (hereinafter also referred to as "acrylonitrile-based polymer"). The acrylonitrile-based polymer may be a homopolymer having only acrylonitrile as a monomer unit, and may be a copolymer having acrylonitrile and other monomers copolymerizable with acrylonitrile as the monomer unit.

  Other monomers may be olefin monomers such as ethylene and propylene, diene monomers such as butadiene, styrene monomers, amide monomers, ester monomers and the like. Other monomers may be halogenated monomers partially substituted with halogen. Examples of halogenated monomers include vinyl chloride, vinyl fluoride, vinylidene chloride and the like.

  The acrylonitrile-based polymer is preferably a copolymer having acrylonitrile and another monomer copolymerizable with acrylonitrile as a monomer unit, and more preferably a copolymer having acrylonitrile and a halogenated monomer as a monomer.

  When the acrylonitrile-based polymer is a copolymer, the content of acrylonitrile units in the acrylonitrile-based polymer is 35% by mass or more, 50% by mass or more, or 70% by mass or more based on the total amount of monomer units constituting the acrylonitrile-based polymer It may be 85% by mass or less.

The membrane 18 is provided with, for example, a non-woven fabric containing the above-described fibers. The non-woven fabric may contain other organic fibers, inorganic fibers and the like in addition to the acrylonitrile polymer fiber. Other organic fibers include synthetic fibers such as polyethylene, polypropylene, polyester, nylon and aramid. Examples of inorganic fibers include fibers of SiO ₂ (glass fibers) and the like. The non-woven fabric may further contain an inorganic powder formed of SiO ₂ or the like.

The membrane 18 is preferably provided with a hydrophilic functional group such as a hydroxyl group, a carboxyl group or a sulfo group by a dry or wet hydrophilization treatment. By imparting a hydrophilic functional group to the film body 18 (particularly the surface thereof), it is possible to secure Pb ²⁺ adsorption sites, and the effect of suppressing osmotic short circuit is further improved.

  The membrane 18 may include a plurality of types of fibers having different fiber diameters. It is considered that a thin fiber having a fiber diameter of less than 5 μm (particularly, about 1 μm to about 2 μm) exerts an effect of suppressing the precipitation of sulfuric acid by increasing the specific surface area of the membrane 18. A thick fiber with a fiber diameter of 5 μm or more (especially 5 μm or more and about 10 μm or less) has the effect of increasing the diffusion coefficient of sulfuric acid by securing the strength of the membrane 18 and increasing the space of the membrane 18. Conceivable. The fiber diameter of the thick fiber is preferably at least 2.5 times the fiber diameter of the thin fiber.

  The proportion of fibers having a fiber diameter of 5 μm or more in all the fibers contained in the membrane 18 is preferably 5% or more, more preferably 7% or more, still more preferably 9% from the viewpoint of increasing the diffusion coefficient of sulfuric acid Or more, particularly preferably 10% or more, and from the viewpoint of suppressing the precipitation of sulfuric acid, preferably 90% or less, more preferably 85% or less, still more preferably 80% or less, particularly preferably 75% or less . It is preferable that the ratio for which the fiber diameter is 5 μm to 10 μm is in the above range.

  The proportion of fibers having a fiber diameter of less than 5 μm in the total fibers contained in the membrane 18 is preferably 60% or more, more preferably 65% or more, still more preferably 70%, from the viewpoint of further suppressing sedimentation of sulfuric acid. Or more, particularly preferably 75% or more, and from the viewpoint of further increasing the diffusion coefficient of sulfuric acid, preferably 95% or less, more preferably 90% or less, still more preferably 85% or less, particularly preferably 80% or less It is. It is preferable that the ratio for which the fiber diameter is 1 μm to 2 μm is in the above range.

  The ratio of fibers having a predetermined fiber diameter to fibers contained in the membrane is measured based on an SEM image obtained by a scanning electron microscope (for example, manufactured by Hitachi High-Technologies Corporation). Specifically, the diameter (the length in the short direction of the fiber in the SEM image (shortest distance)) of 100 fibers in the SEM image is measured, and the distribution of the fiber diameter is determined. Next, the ratio of the number of fibers having a predetermined fiber diameter to the total number of fibers measured is calculated.

  The membrane 18 has pores. The average pore diameter of the membrane 18 is preferably 20 μm or less, 19 μm or less, 18 μm or less, 17 μm or less, 16 μm or less, 15 μm or less, 14 μm or less, 13 μm or less, 12 μm or less, from the viewpoint of suppressing stratification of the electrolyte. It is 11 μm or less or 10 μm or less. The average pore diameter of the membrane 18 is preferably 1 μm or more, 2 μm or more, or 3 μm or more from the viewpoint of improving the output of the battery.

  The average pore size of the membrane body corresponds to an intermediate value between the minimum value and the maximum value in the Y axis (pore volume or pore specific surface area) of the distribution curve in the integrated pore size distribution measured by mercury porosimetry. It is calculated as the median diameter which is the value of the axis (pore diameter). The average pore diameter of the membrane can be measured, for example, by Autopore IV 9500 manufactured by Shimadzu Corporation.

The porosity of the membrane 18 is preferably 60% or more, more preferably 65% or more, and still more preferably, from the viewpoint of further facilitating securing of the diffusibility of sulfate ions and further increasing the space for retaining sulfate ions. Is 70% or more, particularly preferably 75% or more, and most preferably 80% or more. The porosity of the membrane is calculated from the actual volume and the apparent volume in accordance with the following formulas (1) to (3) for a sample cut out of the membrane in a rectangular shape having a suitable size.
Porosity (%) = {1− (actual volume / apparent volume)} × 100 (1)
Actual volume (cm ³ ) = measured value of weight (g) / density (g / cm ³ ) (2)
Apparent volume (cm ³ ) = longitudinal (cm) × horizontal (cm) × thickness (cm) (3)
In addition, as for the length, width, and thickness of the sample at the time of calculating an apparent volume, all use measured values.

  The thickness of the film body 18 is preferably 0.3 mm or less, more preferably 0.25 mm or less, still more preferably 0.2 mm or less, particularly preferably 0.15 mm or less, from the viewpoint of suppressing an increase in internal resistance. . The thickness of the film body 18 is, for example, 0.03 mm or more from the viewpoint of the ability to prevent sedimentation of sulfuric acid, the influence on the cell reaction, the strength and the like. When the membrane 18 includes a non-woven fabric, the thickness of the membrane 18 is determined according to the thickness of the fibers constituting the non-woven fabric.

  In the above embodiment, the film body 18 covers all of the main surface (the surface facing the separator 11), the side surface and the bottom surface of the negative electrode plate 9 and is provided in contact (in close contact) with those surfaces. However, in another embodiment, the film body may be provided between the negative electrode plate 9 and the separator 11 so as to be separated from the negative electrode plate 9. In this case, the film body 18 may be provided, for example, on the surface of the separator 11 on the negative electrode side. From the viewpoint of further suppressing the permeation short circuit, the film body 18 is preferably provided in contact with (in close contact with) the surface of the negative electrode plate 9.

  In the above embodiment, the film body 18 covers all of the main surface (surface facing the separator 11), the side surface and the bottom surface of the negative electrode plate 9, but in the other embodiments, the film body is the main component of the negative electrode plate 9. It may be provided to cover only the surface (surface facing the separator 11).

  Although the film body 18 is provided between the negative electrode plate 9 and the separator 11 in the above embodiment, the film body is provided between the positive electrode plate 10 and the separator 11 in another embodiment. Good. That is, in the description related to the above-mentioned film body, the “negative electrode plate” may be read as the “positive electrode plate”.

Example 1
A paste-type electrode plate was used in which a paste prepared by kneading lead powder containing lead monoxide as a main component with dilute sulfuric acid was filled in a lead alloy grid. Thereafter, the unformed electrode plate was obtained through the aging and drying steps. Incidentally, the positive electrode plate and the negative electrode plate which was not chemically converted is composed both divalent lead monoxide is lead compound (PbO), a mixture of such tribasic dilute lead sulfate _{(3PbO · PbSO 4 · H 2} O) ing. By conversion, the unformed material of the positive electrode plate is oxidized to lead dioxide (PbO ₂ ), and the unformed material of the negative electrode plate is reduced to cancellous lead (Pb) to obtain a preformed electrode plate (positive electrode plate, negative electrode plate) It was done.

  As a film body, a non-woven fabric (average pore diameter: 15 μm, thickness: 0.2 mm) containing a fiber of a copolymer of acrylonitrile and vinyl chloride (acrylonitrile: vinyl chloride = 85: 15 (mass ratio)) is used. Placed in The fibers constituting the non-woven fabric include two types of fibers: fiber 65% with a diameter of 1 to 2 μm and fiber 35% with a diameter of 5 to 10 μm. As the separator, a bag-like polyethylene separator having a thickness of 0.25 mm and an average pore diameter of 30 nm to 200 nm was used, and the negative electrode plate and the membrane were housed in the separator. Rating of D size (JIS D 5301. Width: 173 mm, box height: 204 mm, width of negative electrode plate: 145 mm, height of negative electrode plate (including upper frame part): 113 mm) using dilute sulfuric acid as electrolyte solution A lead-acid battery with a capacity of 35 Ah was produced.

(Calculation of average pore size)
The average pore diameter of the membrane was measured by Autopore IV 9500 manufactured by Shimadzu Corporation. The average pore size of the membrane body corresponds to an intermediate value between the minimum value and the maximum value in the Y axis (pore volume or pore specific surface area) of the distribution curve in the integrated pore size distribution measured by mercury porosimetry. It was calculated as the median diameter which is the value of the axis (pore diameter).

(Penetration short circuit evaluation)
The effect of suppressing the osmotic short circuit was evaluated. The fully charged lead-acid battery was placed in a water bath whose hot water bath temperature was set to 25 ° C. ± 2 ° C. The osmotic short circuit test was performed in the order of the following cycle units (a) to (d). The results are shown in Table 1.
(A) Discharge to 10.5 V at 3.4 A (equivalent to 0.05 C).
(B) Set the temperature of the water tank to 40 ° C. ± 2 ° C., connect a lead storage battery to a 10 W incandescent lamp, and discharge for 5 days.
(C) Re-set the temperature of the water tank to 25 ° C ± 2 ° C, and charge it for 4 hours with 50A (equivalent to 1.43C) as the maximum current value. The charging upper limit voltage was 14V.
(D) Repeat the above (a) to (c), and if the phenomenon that the current is blurred and rises in (c) is observed, it is judged that the osmotic short circuit has occurred, and the test is ended.
According to the number of weeks until the occurrence of the osmotic short circuit, the effect of suppressing the osmotic short circuit was evaluated according to the following criteria. When one cycle of (a) to (c) is repeated, about one week elapses, it is defined that one week has passed when one cycle of (a) to (c) is completed.
A: 13 weeks or more B: 11 to 12 weeks C: 10 weeks or less

Examples 2 to 5
A lead acid battery was prepared and evaluated in the same manner as in Example 1 except that the copolymers of acrylonitrile and vinyl chloride were changed to the following copolymers.
Example 2: Copolymer of acrylonitrile and vinyl fluoride (acrylonitrile: vinyl fluoride = 85:15 (mass ratio))
Example 3: Copolymer of acrylonitrile and styrene (acrylonitrile: styrene = 85: 15 (mass ratio))
Example 4: Copolymer of acrylonitrile and vinylidene chloride (acrylonitrile: vinylidene chloride = 85: 15 (mass ratio))
Example 5: Copolymer of acrylonitrile, styrene and butadiene (acrylonitrile: styrene: butadiene = 80: 10: 10 (mass ratio))

Example 6
LN1 size (EN 50342-2 width: 175 mm, box height: 190 mm) Width of the negative electrode plate: 143 mm, height of the negative electrode plate (including upper frame part): 100 mm. A lead storage battery was produced and evaluated in the same manner as in Example 1 except that the above was changed to

Comparative Example 1
A lead storage battery was prepared and evaluated in the same manner as in Example 1 except that the film was not provided on the negative electrode plate.

Comparative Example 2
A lead storage battery was prepared and evaluated in the same manner as in Example 1 except that an inorganic non-woven fabric (main component: SiO ₂ , average pore diameter: 7 μm, thickness: 0.2 mm) was used as a film body.

Comparative Example 3
As a film body, it is carried out except using organic / inorganic mixed non-woven fabric (porous sheet, non-woven fabric composed of mixed fibers including pulp, glass fiber and silica powder, average pore diameter: 3 μm, thickness: 0.2 mm) A lead-acid battery was prepared and evaluated in the same manner as Example 1.

Comparative Example 4
A lead storage battery was prepared and evaluated in the same manner as in Example 1 except that an organic non-woven fabric (made of polypropylene, average pore diameter: 15 μm, thickness: 0.2 mm) was used as the film body.

  From the above results, it can be seen that the osmotic short circuit is suppressed when the membrane provided between the electrode plate and the separator contains an acrylonitrile polymer fiber. On the other hand, it is understood that the osmotic short circuit is not suppressed when the membrane is not provided and when the inorganic nonwoven fabric or the organic / inorganic mixed nonwoven fabric not containing the acrylonitrile polymer is used.

  In addition, this invention is not limited to said Example, A various modification is included. For example, the above embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to the aspect having all the described configurations.

  DESCRIPTION OF SYMBOLS 1 ... Lead-acid battery, 9 ... Negative electrode plate, 10 ... Positive electrode plate, 11 ... Separator, 18 ... Film body.

Claims (7)

Positive plate,
A negative electrode plate,
A separator disposed between the positive electrode plate and the negative electrode plate;
A membrane disposed between the positive electrode plate or the negative electrode plate and the separator;
Equipped with
The lead-acid battery, wherein the film body contains a fiber of a polymer having acrylonitrile as a monomer unit.   The lead-acid battery of claim 1, wherein the polymer is a copolymer.   The lead acid battery according to claim 1, wherein the membrane has pores having an average pore diameter of 20 μm or less.   The lead storage battery according to any one of claims 1 to 3, wherein a proportion of fibers having a fiber diameter of less than 5 μm in the fibers is 60% or more.   The lead storage battery according to any one of claims 1 to 4, wherein a proportion of fibers having a fiber diameter of 5 μm to 10 μm in the fibers is 10% or more.   The lead storage battery according to any one of claims 1 to 5, wherein the separator is a bag-like separator, and the positive electrode plate or the negative electrode plate and the film body are accommodated in the separator.   The lead storage battery according to any one of claims 1 to 6, wherein a thickness of the film body is 0.3 mm or less.

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