JP2017174822A - Lead acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead acid battery excellent in life performance in an environment involving deep discharge such as PSOC, in which penetration short circuit due to graphite or carbon fibers is less likely to occur.SOLUTION: Negative electrode material of a negative electrode plate 4 of a lead acid battery contains graphite or carbon fibers, and barium sulphate, the ratio S/W of the average pole plate interval S' of the negative electrode plate 4 and a positive electrode plate 6, to the mass W of the negative electrode material 14 per negative electrode plate 4 is 0.01 mm/g or more, the average pole plate interval S' is 0.4-1.0 mm, and the negative electrode material contains 1.2 mass% or more of barium sulphate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lead storage battery, and more particularly to a lead storage battery used in an environment with deep discharge.

  With the advent of the idling stop vehicle, the lead-acid battery has been discharged more deeply than before. For example, a lead-acid battery for an idling stop vehicle is assumed to be used in a partial state of charge (PSOC). Further, as for forklifts, lead storage batteries for cycle use have been conventionally used at a deep depth of discharge (DOD). When used in a partially charged state, the lead-acid battery has a short life due to accumulation of lead sulfate on the positive electrode or sulfation of the negative electrode. And in a partially charged state, since stirring of the electrolyte solution due to gas generation is insufficient, the electrolyte solution is easily stratified, and the life of the lead storage battery is further shortened.

  On the other hand, when the lead storage battery falls into an overdischarge from a partially charged state because the vehicle is left for a long period of time, an infiltration short circuit in which the metallic lead penetrates the separator and the positive and negative bipolar plates are short-circuited easily occurs. The concentration of sulfate ions in the electrolytic solution decreases due to overdischarge, and the concentration of lead ions in the electrolytic solution increases accordingly. The lead ions are reduced by the negative electrode plate during charging, metal lead dendrites grow through the holes in the separator, and the positive electrode plate and the negative electrode plate are short-circuited through the separator.

  The applicant has proposed to improve the life of the lead-acid battery in PSOC by including graphite in the negative electrode material. For example, Patent Document 1 (WO2011 / 90113) discloses that a negative electrode material contains 0.02-2.20 mass% graphite, 0.5 mass% barium sulfate, and 0.02-2.20 mass% carbon black. Patent Document 2 (WO2011 / 52438) discloses that negative electrode material contains 0.5-3.0 mass% expanded graphite and 0.6 mass% barium sulfate. In a document other than the applicant, for example, Patent Document 3 (JP5584216B) discloses that 1-3 mass% graphite, 0.8 mass% barium sulfate, and 0.1-2 mass% carbon black are contained in the negative electrode material. ing.

WO2011 / 90113 WO2011 / 52438 JP5584216B

  The graphite particles facilitate the charging of the negative electrode by providing a path for electrons to lead sulfate. The inventor found that in the process of improving the PSOC life, graphite in the negative electrode material causes an infiltration short circuit. As a cause of this, if the graphite particles are exposed on the surface of the negative electrode plate or protrude from the surface, it is considered that the exposed portion of the graphite particles becomes the center of precipitation of metallic lead. As a result, it is believed that dendrites of metallic lead grow from the exposed graphite particles and penetrate the separator to cause a short circuit. It has not been known so far that graphite in the negative electrode material causes an infiltration short circuit, and the inventors have discovered for the first time.

The subject of this invention is
・ Penetration short circuit due to graphite or carbon fiber hardly occurs,
-To provide a lead-acid battery with excellent life performance in an environment with deep discharge such as PSOC.

  The present invention relates to a lead-acid battery having a negative electrode plate, a positive electrode plate, an electrolyte solution, and a separator, wherein the negative electrode material of the negative electrode plate contains graphite or carbon fiber, and barium sulfate, and the negative electrode plate and the The ratio S / W between the average electrode plate spacing S with respect to the positive electrode plate and the mass W of the negative electrode material per negative electrode plate is 0.01 mm / g or more.

  The graphite may be natural graphite such as scaly graphite or earthy graphite, artificial graphite, or expanded graphite, in addition to the flaky graphite and expanded graphite of the examples. Scaly graphite and expanded graphite are preferable, and flaky graphite is particularly preferable. Expanded graphite is expanded graphite. Carbon fiber has the same effect as graphite. For example, a carbon fiber having a length of 5 μm or more and 500 μm or less is used.

  Graphite or carbon fiber (hereinafter referred to as graphite, etc.) provides a path for electrons to lead sulfate in the negative electrode material, facilitating reduction of lead sulfate, so that the lead storage battery is fully charged, such as the PSOC life of the lead storage battery Improves life performance when not in use. On the other hand, it has been clarified that when the negative electrode material contains graphite or the like, an infiltration short circuit easily occurs. Until now, it has not been known that when a negative electrode material of a lead storage battery contains graphite or the like, an infiltration short circuit is likely to occur.

  In view of this, the inventor studied to suppress the occurrence of an infiltration short circuit while improving the PSOC life by incorporating graphite or the like into the negative electrode material. As a result, even if the negative electrode material contains graphite or the like, the negative electrode material contains barium sulfate, the average electrode plate spacing S between the negative electrode plate and the positive electrode plate, and the negative electrode material per negative electrode plate It has been found that when the ratio S / W with respect to mass W (hereinafter referred to as “electrode ratio”) is 0.01 mm / g or more, a lead-acid battery having excellent PSOC life performance and excellent permeation short-circuit performance can be obtained.

  In addition, it may replace with barium sulfate and may use barium compounds, such as simple substance barium carbonate. This is because even if a single barium or barium compound is added to the negative electrode material, it changes to barium sulfate after the addition.

  If the content of graphite or the like in the negative electrode material is 0.5 mass% or more, the PSOC life is greatly improved, which is preferable. Further, if the content of graphite or the like in the negative electrode material is 1.5 mass% or more, the PSOC life is particularly improved, which is more preferable.

  When the content of graphite or the like in the negative electrode material is less than 2.5 mass%, it is preferable because the penetration short circuit can be suppressed. Moreover, when the content of graphite or the like in the negative electrode material is set to 2.0 mass% or less, it is more preferable because the penetration short circuit can be further suppressed.

  It is preferable that the content of barium sulfate in the negative electrode material is 0.6 mass% (0.35 mass% in terms of barium element) or more because the effect of suppressing penetration short circuit is large. In addition, it is more preferable that the content of barium sulfate in the negative electrode material is 1.2 mass% (0.7 mass% in terms of barium element) or more because the effect of suppressing the penetration short circuit is particularly large.

  PSOC life will be improved if the barium sulfate content in the negative electrode material is 3.5 mass% or less, so the barium sulfate content in the negative electrode material is 3.5 mass% (2.05 mass% in terms of barium element) or less. It is preferable. If the barium sulfate content in the negative electrode material is 3.0 mass% or less, the PSOC life will be greatly improved. Therefore, the barium sulfate content in the negative electrode material is 3.0 mass% (1.75 mass% in terms of barium element) or less. More preferably.

  Since the PSOC life is improved when the inter-electrode ratio S / W is 0.02 mm / g or less, the inter-electrode ratio S / W is preferably 0.02 mm / g or less. It is more preferable that the electrode-to-electrode ratio S / W is 0.016 mm / g or less because the PSOC life is greatly improved.

  Even if the negative electrode material contains graphite or carbon fiber and barium sulfate and the electrode-to-electrode ratio S / W is 0.01 mm / g or more, there are cases where the permeation short circuit cannot be completely suppressed. Therefore, the inventor studied to further suppress the penetration short circuit.

  The penetration short circuit is further suppressed by setting the electrical resistivity (hereinafter simply referred to as “resistivity”) of graphite or the like in the negative electrode material to 0.01 Ω · cm or less by a four-terminal method. Therefore, the resistivity of graphite or the like in the negative electrode material is preferably 0.01 Ω · cm or less.

  When the average particle diameter of graphite in the negative electrode material is 30 μm or more, the PSOC life is improved. Therefore, the average particle diameter of graphite is preferably 30 μm or more. When the average particle diameter of graphite is 100 μm or more, the PSOC life is greatly improved. Therefore, the average particle diameter of graphite is preferably 100 μm or more.

  When carbon black is further contained in the negative electrode material containing graphite or the like and barium sulfate, the permeation short circuit can be further suppressed. The effect of carbon black suppressing penetration short circuit becomes significant when the carbon black content in the negative electrode material is 0.05 mass% or more, so the carbon black content in the negative electrode material may be 0.05 mass% or more. preferable. On the other hand, if the carbon black content in the negative electrode material exceeds 1.0 mass%, the paste of the negative electrode material becomes too hard and it becomes difficult to fill the current collector. Accordingly, the carbon black content in the negative electrode material is preferably 1.0 mass% or less.

  When the carbon black content in the negative electrode material is 0.1 mass% or more, the effect of improving the PSOC life is increased. Therefore, the carbon black content in the negative electrode material is preferably 0.1 mass% or more.

When the oil absorption of barium sulfate in the negative electrode material is 12 mL / 100 g or more, the osmotic short circuit can be further suppressed. Therefore, the oil absorption amount of barium sulfate in the negative electrode material is preferably 12 mL / 100 g or more. If the oil absorption of barium sulfate in the negative electrode material is 12.5 mL / 100 g or more, the effect of suppressing osmotic short-circuiting will be greater, so the oil absorption of barium sulfate in the negative electrode material should be 12.5 mL / 100 g or more. Is more preferable.

When a separator made of a synthetic resin such as polyolefin is used as the separator, and the silica (SiO ₂ ) content of the separator is 60 mass% or more, the permeation short circuit can be further suppressed. Therefore, the separator is preferably a synthetic resin separator having a silica (SiO ₂ ) content of 60 mass% or more. When the silica (SiO ₂ ) content of the synthetic resin separator is 70 mass% or more, the permeation short circuit can be remarkably suppressed. Therefore, the separator is more preferably a synthetic resin separator having a silica (SiO ₂ ) content of 70 mass% or more. On the other hand, if the silica (SiO ₂ ) content of the synthetic resin separator exceeds 80 mass%, the PSOC life will be reduced, so the separator is preferably a synthetic resin separator with a silica (SiO ₂ ) content of 80 mass% or less. .

  When the electrolytic solution contains aluminum ions in an amount of 0.02 mol / L or more, the PSOC life is greatly improved. Therefore, the concentration of aluminum ions in the electrolytic solution is preferably 0.02 mol / L or more. If the electrolytic solution contains aluminum ions in an amount of 0.03 mol / L or more, the PSOC life is remarkably improved. Therefore, the concentration of aluminum ions in the electrolytic solution is preferably 0.03 mol / L or more.

  When aluminum ions are contained in the electrolytic solution, the penetration short circuit can be further suppressed. When the electrolytic solution contains 0.06 mol / L or more of aluminum ions, a permeation short circuit can be made remarkable. Therefore, the concentration of aluminum ions in the electrolytic solution is preferably 0.06 mol / L or more.

  If aluminum ions are contained in the electrolytic solution in an amount of 0.15 mol / L or less, the PSOC lifetime is greatly improved. Therefore, the concentration of aluminum ions in the electrolytic solution is preferably 0.15 mol / L or less. When aluminum ions are contained in the electrolytic solution in an amount of 0.12 mol / L or less, the PSOC life is remarkably improved. Therefore, the concentration of aluminum ions in the electrolytic solution is preferably 0.12 mol / L or less.

  When lithium ions are contained in the electrolytic solution, the osmotic short circuit can be further suppressed. Moreover, when lithium ions are contained in the electrolytic solution in an amount of 0.01 mol / L or more, the osmotic short circuit can be remarkably suppressed. Therefore, the concentration of lithium ions in the electrolytic solution is preferably 0.01 mol / L or more.

  When the concentration of lithium ions in the electrolytic solution is 0.02 mol / L or more, the PSOC life is remarkably improved. Therefore, the concentration of lithium ions in the electrolytic solution is preferably 0.02 mol / L or less.

  If the concentration of lithium ions in the electrolytic solution is 0.22 mol / L or less, the PSOC life is greatly improved. Therefore, the concentration of lithium ions in the electrolytic solution is preferably 0.22 mol / L or less. When the concentration of lithium ions in the electrolytic solution is 0.18 mol / L or less, the PSOC life is remarkably improved. Therefore, the concentration of lithium ions in the electrolytic solution is preferably 0.18 mol / L or less.

  Since the lead-acid battery according to the present invention is less likely to cause an osmotic short circuit when used in a PSOC environment, it can be used for cycle applications such as for forklifts as well as for idling stop vehicles used in a PSOC environment. In the embodiment, the lead storage battery is a liquid type, but may be a control valve type. The lead acid battery of the present invention is preferably a liquid type lead acid battery. Further, the lead storage battery of the present invention is suitable for a lead storage battery used in a partially charged state because it does not easily cause an infiltration short circuit even when used in a partially charged state.

Sectional drawing of the principal part of the lead acid battery of an Example The figure which shows the PSOC life test in the execution example Characteristic chart showing the effect of graphite content (Sample 5-9 in Table 3) Characteristic diagram showing the effect of the gap ratio (Samples 5, 15C, 16-18 in Table 3) Characteristic diagram showing the effect of the electrode gap ratio (Samples 5, 19C, 20, 23, 25 in Table 3) Characteristic chart showing the effect of barium sulfate content (Samples 3, 10C and 11-14 in Table 3) Characteristic diagram showing the effect of resistivity of graphite (Samples 26, 27 and 29 in Table 3) Characteristic diagram showing the effect of graphite particle size (Sample 5, 28-30 in Table 3) Characteristic chart showing the effect of carbon black content (Sample 5, 41-43 in Table 3) Characteristic chart showing the effect of oil absorption of barium sulfate (samples 5, 54 and 55 in Table 3) Characteristic chart showing the effect of silica (SiO ₂ ) content in synthetic resin separator (Sample 5, 48-51 in Table 3) Characteristic chart showing the effect of aluminum ion content (Sample 5, Table 31-35 in Table 3) Characteristic chart showing the effect of lithium ion content (Sample 5, 36-40 in Table 3)

  Hereinafter, an optimum embodiment of the present invention will be described. In carrying out the present invention, the embodiments can be appropriately changed in accordance with common sense of those skilled in the art and disclosure of prior art. In Examples, the negative electrode material may be referred to as a negative electrode active material, and the positive electrode material may be referred to as a positive electrode active material. The negative electrode plate comprises a negative electrode current collector (negative electrode lattice) and a negative electrode active material (negative electrode material), and the positive electrode plate comprises a positive electrode current collector (positive electrode lattice) and a positive electrode active material (positive electrode material). The solid components other than the current collector belong to the active material (electrode material).

  The negative electrode active material paste was prepared by mixing lead powder by a ball mill method with graphite, barium sulfate, lignin as a shrink-preventing agent, and synthetic resin fibers as a reinforcing material, and further containing carbon black. Hereinafter, the content is indicated by a mass% concentration in a negative electrode active material that is already formed and is fully charged. In addition, a full charge means the state which charged with the 5-hour rate electric current until the terminal voltage during charge measured every 15 minutes showed the constant value (± 0.01V) 3 times continuously.

  The graphite content was varied in the range of 0 mass% to 2.5 mass% with respect to the mass of the fully charged negative electrode active material. As the graphite, scaly graphite and expanded graphite are used, but other graphite such as earth graphite and artificial graphite may be used, and carbon fiber may be used. Of graphite and carbon fiber, scaly graphite or expanded graphite is preferable, and scaly graphite is particularly preferable. The average particle size of the flaky graphite was changed in the range of 5 μm to 300 μm. The resistivity of the scaly graphite and expanded graphite by the 4-terminal method was varied in the range of 0.001 Ω · cm to 0.012 Ω · cm (resistivity under 2.5 MPa pressure).

  The barium sulfate content was varied in the range of 0 mass% to 3.5 mass% with respect to the mass of the fully charged negative electrode active material. The oil absorption of barium sulfate (the oil absorption according to JIS K-5101-13-2: 2004) was varied in the range of 11.5 mL / 100 g to 14.4 mL / 100 g. The average primary particle diameter of barium sulfate is, for example, 0.3 μm to 2.0 μm, and the average secondary particle diameter is, for example, 1.0 μm to 10 μm. The lignin content is 0.2 mass%, but the content is arbitrary, and a synthetic anti-shrinkage agent such as a sulfonated bisphenol condensate may be used instead of lignin. The reinforcing material content is 0.1 mass%, but the content and the type of synthetic resin fiber are arbitrary. Moreover, the manufacturing method of lead powder, oxygen content, etc. are arbitrary, and you may contain other additives, for example, a water-soluble synthetic polymer.

Paste the above mixture with water and sulfuric acid, fill it into an expandable negative electrode grid (110mm high x 100mm wide x 1.0mm thick) made of an antimony-free Pb-Ca-Sn alloy, age and dry gave. The negative electrode lattice may be a cast lattice, a punched lattice, or the like. The mass of the negative electrode active material per negative electrode plate was adjusted in the range of 30 g to 80 g. The density of the negative electrode active material after chemical conversion may be, for example, 3.6 g / cm ³ or more and 4.0 g / cm ³ or less.

  The positive electrode active material paste is made by mixing 0.1 mass% of the synthetic resin fiber of the reinforcing material with lead powder by ball mill method and the mass of the positive electrode active material that is already formed and fully charged, and paste it with water and sulfuric acid. Was used. This paste was filled in an expanded positive electrode grid (height 110 mm × width 100 mm × thickness 1.2 mm) made of an antimony-free Pb—Ca—Sn alloy, and aged and dried. The kind of lead powder and manufacturing conditions are arbitrary. The positive grid may be a cast grid, a punched grid, or the like.

  The unformed negative electrode plate is wrapped in a polyethylene separator with ribs protruding from the base, and seven unformed negative electrode plates and six unformed positive electrode plates are alternately laminated, and the negative electrode plate and the positive electrode plate are connected with straps. Electrode plate group. The base thickness of the separator may be, for example, 0.15 mm or more and 0.25 mm or less. 6 electrode plates are connected in series and stored in the cell chamber of the battery case. At 20 ° C, sulfuric acid with a specific gravity of 1.230 is added and formed in the battery case. B20 size is a liquid with a 5 hour rate capacity of 30 Ah. A lead-acid battery was used. The average electrode plate spacing S between the positive electrode plate and the negative electrode plate (hereinafter abbreviated and sometimes referred to as “between electrodes”) was adjusted in the range of 0.3 mm to 1.0 mm. Further, the ratio N / P of the mass P of the positive electrode active material and the mass N of the negative electrode active material per lead storage battery may be, for example, 0.62 or more and 0.95 or less.

  FIG. 1 shows a main part of the lead storage battery 2, 4 is a negative electrode plate, 6 is a positive electrode plate, 8 is a separator, and 10 is an electrolyte containing sulfuric acid as a main component. The negative electrode plate 4 includes a negative electrode grid 12 and a negative electrode active material 14, and the positive electrode plate 6 includes a positive electrode grid 16 and a positive electrode active material 18. The separator 8 has a bag shape including a base 20 and a rib 22, and a negative electrode is accommodated in the bag, and the rib 22 faces the positive electrode plate 6 side. However, the positive electrode plate 6 may be accommodated in the separator 8 with the rib 22 facing the positive electrode plate. The separator need not be in the form of a bag as long as the positive electrode plate and the negative electrode plate are separated from each other. For example, a leaflet-shaped glass mat or a retainer mat may be used. S ′ is an interval between the electrode plates (interval between the positive electrode active material surface and the negative electrode active material surface), and this average value is the average electrode plate interval S. When the direction in which the ears of the positive and negative electrode plates protrude is the upward direction, the interval between the electrode plates at the upper end of the active material surface of the positive and negative electrode plates is S ′.

  The average electrode plate interval (between electrodes) S is obtained by excluding the thickness of the negative electrode plate and the thickness of the positive electrode plate from the thickness of the electrode plate group, and dividing by the total number of electrode plates per electrode plate group. The thickness of the electrode plate group is the length between the outer ends in the stacking direction of the electrode plates located at both ends of the electrode group, in other words, the length between the active material surfaces on the outer sides in the stacking direction of the electrode plates positioned at both ends of the electrode group. That's it. The thickness of the electrode plate group, the thickness of the positive electrode plate, and the thickness of the negative electrode plate are all measured at the upper end of the active material surface of the positive and negative electrode plates. The average electrode plate interval S and the thickness of the electrode plate group are the dimensions when the electrode plate group is housed in the battery case and fully charged.

  The barium content contained in the pre-formed negative electrode active material is quantified as follows. The fully charged lead-acid battery is disassembled, the negative electrode plate is washed with water and dried to remove sulfuric acid, and the negative electrode active material is collected. The negative electrode active material was crushed, 300 g / L of hydrogen peroxide water was added at 20 mL per 100 g of negative electrode active material, and 60 mass% concentrated nitric acid was diluted with 3 times its volume of ion-exchanged water (1 + 3) In addition, heat for 5 hours under stirring to dissolve lead as lead nitrate. Further, barium sulfate is dissolved, and the barium concentration in the solution is quantified by an atomic absorption measurement method and converted to the barium content in the negative electrode active material. Furthermore, the barium sulfate content in the negative electrode active material can be determined from the barium content in the negative electrode active material.

  The mass of the negative electrode active material per negative electrode plate and the contents of graphite and carbon black contained in the already formed negative electrode active material are quantified as follows. The lead-acid battery 2 in a fully charged state is disassembled, the negative electrode plate 4 is washed and dried to remove sulfuric acid, the negative electrode active material 14 is collected, and the mass of the negative electrode active material per negative electrode plate is measured. The negative electrode active material was pulverized, 20 mL of 300 g / L hydrogen peroxide was added per 100 g of negative electrode active material, and 60 mass% concentrated nitric acid was diluted with 3 times its volume of ion-exchanged water (1 + 3) nitric acid And heat for 5 hours under stirring to dissolve lead as lead nitrate. Further, barium sulfate is dissolved, and then graphite, carbon black, and reinforcing material are separated by filtration.

  The solid content (graphite, carbon black, reinforcing material) obtained by filtration is dispersed in water. Carbon black and graphite are separated by using a sieve through which the reinforcing material does not pass, for example, a sieve having a diameter of 1.4 mm, sieving the dispersion twice, washing with water and removing the reinforcing material.

  In the negative electrode active material paste, carbon black and graphite are added together with an organic shrinkage agent such as lignin. In the negative electrode active material after conversion, carbon black and graphite are aggregated due to the surface active effect of the organic shrinkage agent. Exists in a collapsed state. However, in the above series of separation operations, the organic shrunk agent is dissolved and lost in water, so after carbon black and graphite are dispersed in water, the organic shrunk agent is added and stirred, The following separation operation is performed in a state where the aggregate is broken again.

  The organic shrunk agent may be any material that can be added to a lead-acid battery. In the examples, Vanillex N manufactured by Nippon Paper Industries Co., Ltd., which is a lignin sulfonate, was used. Further, in the examples, 15 g of the organic anti-shrink agent was added to 100 mL of water, and the stirring operation was performed.

  After the above operation, the suspension containing carbon black and graphite is separated by passing through a sieve through which carbon black passes substantially without passing through the graphite. In the examples, a sieve having a size of 20 μm was used. Even when graphite having a smaller particle diameter is used, graphite having a particle diameter of 3 μm or more does not substantially pass through the sieve due to clogging of the sieve. By this operation, graphite remains on the sieve, and carbon black is contained in the liquid that has passed through the sieve.

  After the graphite and carbon black separated by the above series of operations are washed and dried, their respective weights are weighed. Carbon fiber can be separated in the same manner as graphite.

  The average particle diameter (volume average diameter) of graphite is measured by a light scattering method, and if there is a part having a particle diameter of less than 3 μm, it is ignored as an impurity such as carbon black. The resistivity of graphite is measured by a four-terminal method by applying a pressure of 2.5 MPa to graphite powder that has been washed and dried.

  The oil absorption of barium sulfate in the negative electrode active material is measured as follows. The fully charged lead storage battery 2 is disassembled, the negative electrode plate 4 is washed with water and dried to remove sulfuric acid, and the negative electrode active material 14 is collected. The negative electrode active material was pulverized, 20 mL of 300 g / L hydrogen peroxide was added per 100 g of negative electrode active material, and 60 mass% concentrated nitric acid was diluted with 3 times its volume of ion-exchanged water (1 + 3) nitric acid And heat for 5 hours under stirring to dissolve lead as lead nitrate. Next, the graphite, carbon black, barium sulfate, and reinforcing material are separated by filtration.

  The solid obtained by filtration is dispersed in water. Use a sieve that does not allow the reinforcement to pass through, for example, a sieve with a diameter of 1.4 mm. Sift the dispersion twice and wash with water to remove the reinforcement. Next, the dispersion from which the reinforcing material has been removed is centrifuged at 3000 rpm for 5 minutes. The supernatant and the upper layer of the precipitate contain carbon black and graphite and are removed, and barium sulfate is extracted from the lower layer of the precipitate. The extracted barium sulfate is washed with water and dried, and the oil absorption is measured according to JIS K-5101-13-2: 2004.

  Aluminum ions and lithium ions in the electrolyte are extracted from the electrolyte and quantified by ICP emission spectroscopy.

The silica (SiO ₂ ) content in the separator is quantified as follows. First, the separator taken out of the lead storage battery 2 is washed with water and dried, and the dry weight is measured. Next, the separator is completely burned, and the Si content in the residue after burning is quantified by ICP emission spectroscopy. The silica (SiO ₂ ) content in the separator is calculated from the dry weight of the separator and the Si content in the residue after combustion.

  The lead-acid battery 2 in a fully charged state was subjected to a penetration short circuit acceleration test and a PSOC life test. The contents of the PSOC life test are shown in FIG. 2 and Table 1. For example, 1CA is 30A in the case of a battery having a 5-hour rate capacity of 30 Ah, and 40 ° C. air is tested in a 40 ° C. air tank. In the test pattern of Table 1, the number of cycles until the terminal voltage reaches 1.2V / cell is defined as the PSOC life. Table 2 shows the contents of the penetration short circuit acceleration test. This test is a test performed under conditions that promote the occurrence of permeation shorts, and the incidence of permeation shorts is significantly higher than the actual use conditions of lead-acid batteries. 5 cycles of the penetration short circuit acceleration test pattern shown in Table 2 were taken, and the lead storage battery was disassembled after 5 cycles, and the ratio of lead storage batteries in which short circuit occurred (incidence rate of penetration short circuit) was examined. In addition, 25 degreeC water shows having tested in the 25 degreeC water tank. In Tables 1 and 2, CC discharge means constant current discharge, CV charge means constant voltage charge, and CC charge means constant current charge.

The results of PSOC life test and penetration short circuit acceleration test are shown in Table 3, and the main results are extracted in FIGS. The PSOC lifetime data is shown as a relative value with Sample 1C as 1. The graphite used in Table 3 is as follows.
Graphite 1: flake graphite with an average particle size of 100 μm, resistivity of 0.001 Ω · cm,
Graphite 2: expanded graphite with an average particle size of 30 μm, resistivity of 0.01 Ω · cm,
Graphite 3: expanded graphite with an average particle size of 30 μm, resistivity of 0.012 Ω · cm,
Graphite 4: scale-like graphite with an average particle diameter of 5 μm, resistivity of 0.001 Ω · cm,
Graphite 5: flaky graphite with an average particle size of 30 μm, resistivity of 0.001 Ω · cm,
Graphite 6: scaly graphite with an average particle size of 300 μm and a resistivity of 0.001 Ω · cm.

* Paste is hard and cannot be prepared.
1C, 3C, 4C, 10C, 15C, 19C: Comparative examples

  From Table 3 and Fig. 3, PSOC life is improved when graphite is contained in the negative electrode active material, PSOC life is greatly improved when graphite is contained at 0.5 mass% or more, and PSOC life is improved when graphite is contained at 1.5 mass% or more. It turns out that it improves notably. On the other hand, when 2.5 mass% or more of graphite is contained in the negative electrode active material, an infiltration short circuit is likely to occur, and by making the content of graphite in the negative electrode active material less than 2.5 mass%, the infiltration short circuit is suppressed. I understand that. When the content of graphite in the negative electrode active material is 2.0 mass% or less, the effect of suppressing penetration short circuit is particularly great. Since it has not been known so far that graphite in the negative electrode active material is related to the penetration short circuit, such an effect cannot be expected.

  Therefore, the inventor studied to suppress the occurrence of the penetration short circuit while improving the PSOC life by adding graphite to the negative electrode active material. As a result, the negative electrode active material contains graphite and barium sulfate, and the electrode-to-electrode ratio S / W is 0.01 mm / g or more. It was found that a lead storage battery having better PSOC life performance than a lead storage battery that is not allowed to be obtained (Sample 5-8 in Table 3). In general, if the average electrode plate spacing S is small, the distance between the positive and negative electrode plates is short, so it is considered that the penetration short circuit is likely to occur and the effect of suppressing the penetration short circuit is low. In this case, the osmotic short-circuit suppression effect is large (Sample 24 in Table 3). On the other hand, even when S is larger than that of sample 24, if W is large, the permeation short-circuit suppressing effect is small (sample 19C in Table 3). Therefore, the permeation short circuit suppression effect is not determined only by S or W, both S and W are related to the permeation short circuit, in order to suppress the permeation short circuit, the electrode ratio S / W is 0.01 mm / It is important to make it g or more.

  If any one of the following: graphite is included in the negative electrode active material, barium sulfate is included in the negative electrode active material, and the interelectrode ratio S / W is 0.01 mm / g or more, PSOC life performance and It is not possible to obtain a lead storage battery excellent in permeation resistance short circuit performance. For example, even if the negative electrode active material contains barium sulfate and the electrode ratio S / W is 0.01 mm / g or more, if the negative electrode active material does not contain graphite, the PSOC life performance is low (sample 3C in Table 3). . Moreover, even if graphite is contained in the negative electrode active material and the electrode-to-electrode ratio S / W is 0.01 mm / g or more, the penetration short circuit cannot be sufficiently suppressed unless the negative electrode active material contains barium sulfate (Table 3). Sample 10C). Similarly, even if graphite and barium sulfate are contained in the negative electrode active material, the penetration short circuit cannot be sufficiently suppressed when the electrode-to-electrode ratio S / W is less than 0.01 mm / g (samples 15C and 19C in Table 3). Therefore, the PSOC lifetime is not achieved unless the negative electrode active material contains graphite, the negative electrode active material contains barium sulfate, and the interelectrode ratio S / W is 0.01 mm / g or more. It can be said that a lead storage battery excellent in performance and permeation resistance short circuit performance can be obtained. Since it has not been known so far that barium sulfate in the negative electrode active material is related to the occurrence of permeation short circuit, those skilled in the art conceive of containing barium sulfate in the negative electrode active material in order to suppress permeation short circuit. It is not easy. Moreover, since it has not been known so far that the electrode-to-electrode ratio S / W is related to the occurrence of osmotic short-circuit, those skilled in the art have set the electrode-to-electrode ratio S / W to 0.01 mm / g or more to suppress the osmotic short-circuit. It is not easy to conceive. Furthermore, it has not been known so far that when the negative electrode active material contains graphite, an infiltration short circuit is likely to occur. Therefore, in order to suppress the penetration short circuit that is likely to occur when graphite is contained in the negative electrode active material, the negative electrode active material contains barium sulfate and the electrode ratio S / W is 0.01 mm / g or more. It is very difficult for those skilled in the art to conceive of this.

  The influence of the electrode-to-electrode ratio S / W is shown in FIGS. FIG. 4 shows the results when the amount of negative electrode active material per negative electrode plate W is constant and the distance between electrodes (average electrode plate interval) S is changed. Further, FIG. 5 shows the result when the gap S is kept constant and the negative electrode active material amount W per one negative electrode plate is changed. The results were the same when the gap S was changed and when the negative electrode active material amount W per negative electrode plate was changed. Even if S / W is changed by changing S and S / W is changed by changing W, the same result is obtained. It turns out that it has. 4 and 5, when the negative electrode active material contains graphite and barium sulfate, the effect of suppressing the penetration short circuit is completely different between the electrode ratio S / W of less than 0.01 mm / g and 0.01 mm / g. I understand that. Therefore, it can be said that there is a critical significance in setting the inter-electrode ratio S / W to 0.01 mm / g or more.

  4 and 5, it can be seen that the PSOC life performance is improved when the electrode-to-electrode ratio S / W is 0.02 mm / g or less. PSOC life performance is greatly improved when the electrode-to-electrode ratio S / W is 0.16 mm / g or less.

  From FIG. 6, it can be seen that when the content of barium sulfate in the negative electrode active material is 0.6 mass% or more, the effect of suppressing the penetration short circuit is large. Since it has not been known so far that barium sulfate in the negative electrode active material is related to osmotic short-circuiting, such an effect cannot be expected. In addition, when the content of barium sulfate in the negative electrode active material is 1.2 mass% or more, the effect of suppressing the penetration short circuit is particularly large, and when the content of barium sulfate is less than 1.2 mass% and 1.2 mass% or more, the effect of suppressing the penetration short circuit Is completely different. Therefore, it can be said that it is critical to make the barium sulfate content 1.2 mass% or more.

  From Fig. 6, PSOC life performance is improved when the content of barium sulfate in the negative electrode active material is 3.5 mass% or less, and PSOC life performance is increased when the content of barium sulfate in the negative electrode active material is 3.0 mass% or less. It turns out that it improves.

  From Table 3, when the negative electrode active material contains graphite, even if the negative electrode active material contains barium sulfate and the electrode-to-electrode ratio S / W is 0.01 mm / g or more, the permeation short circuit may not be completely suppressed. (Sample 5 in Table 3 etc.) Therefore, the inventor further studied to suppress the penetration short circuit.

  FIG. 7 shows that the penetration short circuit is further suppressed when the resistivity of the graphite in the negative electrode active material is 0.01 Ω · cm or less. It has not been known so far that graphite in the negative electrode active material is related to penetration short circuit, so it can be expected that the penetration short circuit suppression effect will be increased by changing the resistivity of graphite in the negative electrode active material is not.

  FIG. 8 shows that the PSOC life is improved by setting the average particle diameter of graphite to 30 μm or more, and the PSOC life is further improved by setting the average particle diameter of graphite to 100 μm or more.

  FIG. 9 shows the influence of carbon black in the negative electrode active material. It can be seen that when carbon black is contained in the negative electrode active material, the occurrence of permeation short circuit is further suppressed. It has not been known so far that carbon black in the negative electrode active material is related to the penetration short circuit. Therefore, it cannot be expected that the penetration short-circuit suppressing effect is increased by adding carbon black to the negative electrode active material. Further, from comparison between Sample 1 and Sample 3 in Table 3, it can be seen that when the negative electrode active material does not contain graphite, the penetration short circuit suppressing effect cannot be obtained even if carbon black is contained in the negative electrode active material. Accordingly, it can be said that the effect of suppressing the penetration short circuit by the carbon black can be obtained only when the negative electrode active material contains graphite.

  The effect of suppressing the penetration short circuit by carbon black is noticeable when the carbon black content of the negative electrode active material is 0.05 mass% or more (FIG. 9). In addition, when the carbon black content in the negative electrode active material is 0.1 mass% or more, the effect of improving the PSOC life is greater than when the carbon black content in the negative electrode material is less than 0.1 mass% (FIG. 9). ). On the other hand, when the negative electrode active material contained carbon black exceeding 1.0 mass%, the active material paste was too hard and it was difficult to fill the negative electrode current collector.

  FIG. 10 shows the influence of the oil absorption of barium sulfate in the negative electrode active material. FIG. 10 shows that the penetration short circuit is further suppressed when the oil absorption of barium sulfate in the negative electrode active material is 12 mL / 100 g or more. Since it has not been known so far that barium sulfate in the negative electrode active material is related to osmotic short circuit, it can be expected that the effect of suppressing osmotic short circuit will increase by changing the oil absorption of barium sulfate in the negative electrode active material is not. When the oil absorption of barium sulfate in the negative electrode active material is 12.5 mL / 100 g or more, the effect of suppressing the osmotic short circuit is particularly great.

Separator made of synthetic resin such as polyolefin including polyethylene contains silica (SiO ₂ ) to impart porosity, and the same applies to other synthetic resin separators. FIG. 11 shows the influence of the silica (SiO ₂ ) content in the separator. From FIG. 11, it can be seen that the permeation short circuit can be further suppressed by setting the content of silica (SiO ₂ ) in the separator to 60 mass% or more. Since the silica in the separator (SiO ₂₎ content is related to penetration short has not been known so far, the permeation short suppressing effect by changing the silica (SiO ₂₎ content in the separator is increased It ’s not something you can expect. When the content of silica (SiO ₂ ) in the separator is 70 mass% or more, the effect of suppressing the penetration short circuit is particularly large. Further, when the silica (SiO ₂ ) content in the separator exceeds 80 mass%, the PSOC life is reduced (FIG. 11).

  FIG. 12 shows the influence of aluminum ions in the electrolyte. It can be seen that the osmotic short circuit can be further suppressed by the aluminum ions in the electrolytic solution. The effect of suppressing osmotic short-circuiting by aluminum ions is noticeable when the content is 0.06 mol / L or more. From comparison between Sample 1 and Sample 4 in Table 3, it can be seen that when the negative electrode active material does not contain graphite, the permeation short-circuit suppressing effect cannot be obtained even if aluminum ions are contained in the electrolytic solution. Therefore, it can be said that the effect of suppressing the osmotic short circuit by aluminum ions is obtained only when the negative electrode active material contains graphite.

  When the aluminum ion concentration in the electrolyte is 0.02 mol / L or more, the PSOC life performance is greatly improved, and when the aluminum ion concentration in the electrolyte is 0.03 mol / L or more, the PSOC life performance is significantly improved (FIG. 12). . In addition, when the aluminum ion concentration in the electrolyte is 0.15 mol / L or less, the PSOC life performance is greatly improved, and when the aluminum ion concentration in the electrolyte is 0.12 mol / L or less, the PSOC life performance is significantly improved (Fig. 12).

  FIG. 13 shows the effect of lithium ions. It can be seen that the osmotic short circuit can be further suppressed by the lithium ions in the electrolytic solution. The effect of suppressing osmotic short-circuiting by lithium ions is noticeable when the content is 0.01 mol / L or more. From the comparison of Sample 1 and Sample 4 in Table 3, it can be seen that when the negative electrode active material does not contain graphite, the penetration short circuit suppressing effect cannot be obtained even if lithium ions are contained in the electrolyte. Therefore, it can be said that the effect of suppressing the penetration short circuit by lithium ions is obtained only when the negative electrode active material contains graphite.

  When the lithium ion concentration in the electrolyte is 0.01 mol / L or more, the PSOC life performance is greatly improved, and when the lithium ion concentration in the electrolyte is 0.02 mol / L or more, the PSOC life performance is significantly improved (FIG. 13). . PSOC lifetime performance is greatly improved when the lithium ion concentration in the electrolyte is 0.22 mol / L or less, and PSOC lifetime performance is significantly improved when the lithium ion concentration in the electrolyte is 0.18 mol / L or less (Fig. 13).

In the embodiment, a lead storage battery having excellent PSOC life and less permeation short-circuit can be obtained. Therefore, a control valve type lead storage battery may be used as the separator.

2 Lead acid battery 4 Negative electrode plate 6 Positive electrode plate 8 Separator 10 Electrolytic solution 12 Negative electrode lattice 14 Negative electrode active material 16 Positive electrode lattice 18 Positive electrode active material 20 Base 22 Rib

S 'plate spacing

Claims (5)

In a lead storage battery having a negative electrode plate, a positive electrode plate, an electrolyte and a separator,
The negative electrode material of the negative electrode plate contains graphite or carbon fiber, and barium sulfate,
And, the ratio S / W of the average electrode plate interval S between the negative electrode plate and the positive electrode plate and the mass W of the negative electrode material per one negative electrode plate is 0.01 mm / g or more, and the average electrode plate interval S Is 0.4mm to 1.0mm,
The lead-acid battery, wherein the negative electrode material contains 1.2 mass% or more of barium sulfate.   The lead acid battery according to claim 1, wherein the negative electrode material contains carbon black.   The lead-acid battery according to claim 1 or 2, wherein the negative electrode material contains less than 2.5 mass% graphite or less than 2.5 mass% carbon fiber.   The lead acid battery according to claim 1, wherein the electrolytic solution contains aluminum ions.   The lead-acid battery according to claim 1, wherein the separator is a bag-like separator made of polyethylene.