JPWO2016052512A1 - Lead acid battery - Google Patents

Abstract

Provided is a lead storage battery capable of achieving both high-level suppression of electrolyte stratification and reduction of high-rate discharge performance. According to a first aspect of the lead-acid battery of the present invention, a porous membrane (8) capable of transmitting an electrolytic solution is provided around the negative electrode plate (5), and the porous membrane (8) is a hydrophobic functional group. And a hydrophilic coating (9) formed on the surface of the substrate (12), the hydrophilic coating (9) comprising a hydrophilic material (10) and a binder (11). The binder (11) has a hydrophobic functional group and a hydrophilic functional group, and the hydrophobic functional group of the binder (11) and the hydrophobic functional group of the substrate (12) are bonded to each other. The binder (11) has the hydrophilic functional group at the end of the hydrophilic coating on the surface side.

Description

  The present invention relates to a lead-acid battery.

  Lead-acid batteries are widely used for industrial purposes, and are used, for example, for automobile batteries, backup power supplies, and main power supplies for electric vehicles. In recent automobiles, an idling stop and start system (hereinafter referred to as “ISS”) that stops the engine during power generation control and signal waiting has been adopted for the purpose of carbon dioxide emission regulation measures and fuel efficiency reduction. .

  Since no power is generated by the alternator during idling stop, all electric power to the electric equipment is supplied from the lead-acid battery, and the lead-acid battery is discharged deeper than before. Further, since the power generation of the alternator is controlled even during traveling, the battery is in a state of insufficient charging. For this reason, in lead storage batteries, deep discharge and insufficient charging are repeated, and stratification (a phenomenon in which the specific gravity of the electrolyte varies in the upper and lower parts of the battery case due to repeated charge and discharge) is a factor in shortening the life of lead storage batteries. It has become apparent. In the positive electrode of a lead-acid battery, water generated during discharge stirs the electrolyte solution, so the effect of stratification is small, but in the negative electrode, there is no such effect, so stratification is likely to occur.

  Further, in the lead storage battery for ISS, in addition to extending the life by suppressing the stratification of the electrolytic solution, improvement of battery performance such as high rate discharge performance, internal resistance, and charge acceptability, which are engine startability, is also a problem. In particular, extending the life and improving battery performance are indispensable for improving the performance of lead storage batteries for ISS used in harsh environments.

  In Patent Document 1 (Japanese Patent Laid-Open No. 6-325745), a web layer containing glass fiber, polyester fiber, silica powder and an acrylic resin binder, and a glass fiber layer containing an alkali-containing glass fiber and an acrylic resin are reactive hot melt. A liquid lead-acid battery separator formed by bonding with an adhesive is disclosed. According to Patent Document 1, a separator for a liquid lead-acid battery that is easy to manufacture and can be manufactured easily and efficiently at low cost is provided.

  Patent Document 2 (Japanese Patent Laid-Open No. 3-122966) discloses a sealed lead-acid battery including a porous electrolytic solution holding body mainly composed of acid-resistant inorganic powder and glass fiber, and the electrolytic solution holding body Discloses a sealed lead-acid battery having a maximum pore diameter of less than 30 μm. According to Patent Document 2, the stratification phenomenon of the electrolytic solution can be prevented, the cycle characteristics and life of the battery are improved, and the battery performance by stratification in a large sealed lead-acid battery that is long in the height direction. It is said that it is possible to suppress the decrease of

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2003-077445) discloses a lead-acid battery having a glass mat made of glass fiber as a separator, and has a porous perforation function between the positive and negative electrode plates and the glass mat. The lead acid battery characterized by having arrange | positioned the property sheet | seat is disclosed. According to Patent Document 3, in a lead storage battery having a glass mat as a separator, accumulation of bubbles in the glass mat can be prevented, an increase in internal impedance with the progress of operation, stratification of the electrolyte solution, and It is said that it is possible to provide a lead storage battery that is less likely to cause characteristic deterioration due to sulfation.

  In Patent Document 4 (Japanese Patent Laid-Open No. 2007-250360), a fiber mat separator having a porosity of 25% or less is disposed between a positive electrode plate and a negative electrode plate, and the height of the electrolyte surface is at least the positive electrode plate. And filled in the fiber mat separator with respect to the positive electrode active material and the electrolyte volume (A) contained in the negative electrode active material, which are above the height of the electrode plate surface of the negative electrode plate and filled in the positive electrode plate and the negative electrode plate, respectively. There is disclosed a lead storage battery in which the ratio (B / A) of the electrolyte volume (B) is 1.30 or less and the battery exterior is provided with a valve mechanism that opens and closes according to the battery internal pressure. According to Patent Document 4, stratification of the electrolytic solution that occurs when charging and discharging is repeated is further suppressed, and in particular, sulfation of the negative electrode plate is suppressed, and a decrease in battery capacity is suppressed.

  Patent Document 5 (Japanese Patent Application Laid-Open No. 2013-206571) describes at least an acid-resistant microporous resin film sheet having an average pore diameter of 1 μm or less by a mercury intrusion method and a porosity of 50 to 90% by a mercury intrusion method. One layer and a wet glass fiber having an average fiber diameter of 2 to 4.5 μm composed of 50% by mass or more, an average pore diameter of 20 to 100 μm by a bubble point method, and a liquid absorption speed of 20 mm / min or more. A separator for a liquid lead-acid battery is disclosed in which at least one layer of a paper-made acid-resistant non-woven fabric sheet is configured in a laminated state. According to Patent Document 5, in a separator for a liquid lead storage battery in which a microporous resin film sheet and a glass fiber mat-like nonwoven sheet (glass fiber mat material) are combined in a laminated state, the glass fiber mat-like nonwoven sheet is good. Separator having good elongation that can provide an active electrode plate active material protection function, a good gas discharge function, and a good anti-electrolyte stratification prevention function, and can follow the elongation of the electrode plate due to battery reaction, and the like It is said that it is possible to provide a liquid lead-acid battery using the above.

JP-A-6-325745 JP-A-3-122966 Japanese Patent Laid-Open No. 2003-077445 JP 2007-250360 A JP 2013-206571 A

  In general, when a physical barrier is provided in the electrolytic solution for the purpose of suppressing stratification of the electrolytic solution, the movement of sulfate ions in the electrolytic solution is hindered, the internal resistance of the battery increases, and the high rate discharge performance decreases. . That is, the suppression of stratification and the suppression of high rate discharge performance are in a so-called trade-off relationship, and further improvement has been desired in terms of achieving both at a high level.

  In view of the above circumstances, an object of the present invention is to provide a lead storage battery capable of achieving both suppression of stratification of an electrolytic solution and suppression of a decrease in high-rate discharge performance at a high level.

  In order to achieve the above object, the lead storage battery according to the present invention is basically configured as follows. That is, the first aspect includes a positive electrode plate containing lead dioxide, a negative electrode plate containing metallic lead, a separator disposed between the positive electrode plate and the negative electrode plate, dilute sulfuric acid, and the positive electrode plate An electrolyte solution in which an electrode plate group including the negative electrode plate and the separator is immersed, and a battery case that stores the electrode plate group and the electrolyte solution, and the electrolyte solution is disposed around the negative electrode plate. Is provided, and the porous film includes a substrate having a hydrophobic functional group and a hydrophilic film formed on the surface of the substrate, and the hydrophilic film includes a hydrophilic material and A binder, the binder having a hydrophobic functional group and a hydrophilic functional group, wherein the binder has a structure in which the hydrophobic functional group of the binder and the hydrophobic functional group of the base material are bonded to each other. Has the hydrophilic functional group at the end of the hydrophilic coating on the surface side. .

  Further, the second aspect includes a positive electrode plate containing lead dioxide, a negative electrode plate containing metallic lead, a separator disposed between the positive electrode plate and the negative electrode plate, dilute sulfuric acid, and the positive electrode plate An electrolyte solution in which an electrode plate group including the negative electrode plate and the separator is immersed, and a battery case that stores the electrode plate group and the electrolyte solution, and the electrolyte solution is disposed around the negative electrode plate. Is provided, and the porous film includes a base material having a hydrophilic functional group and a hydrophilic film formed on the surface of the base material, and the hydrophilic film includes a hydrophilic material and A binder, the binder having a first hydrophilic functional group and a second hydrophilic functional group, wherein the first hydrophilic functional group of the binder and the hydrophilic functional group of the substrate are And the binder has the second hydrophilic functional group at an end on the surface side of the hydrophilic coating. Characterized in that it.

  According to the lead storage battery according to the present invention, it is possible to achieve both suppression of stratification of the electrolytic solution and suppression of decrease in high-rate discharge performance at a high level.

It is a perspective view showing typically one embodiment of a lead acid battery concerning the present invention. It is sectional drawing which shows typically a part of electrode group of FIG. 1A. It is a perspective view which shows typically a part of electrode group of FIG. 1A. It is a figure which shows typically the structure of a part (especially circumference | surroundings of negative electrode plate) of the electrode group 4 of FIG. 1A. It is a figure which shows typically an example of the structure of the base material (no surface treatment) based on this invention. It is a figure which shows typically an example of the structure of the base material which concerns on this invention, and a hydrophilic film. It is a figure which shows typically the other example of the structure of the base material (with surface treatment) concerning this invention. It is a figure which shows typically the other example of the structure of the base material which concerns on this invention, and a hydrophilic film.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiment taken up here, and can be appropriately combined and improved without departing from the scope of the invention.

  As described above, the lead-acid battery according to the present invention includes a porous film that allows the electrolytic solution to pass around the negative electrode plate. The porous film includes a base material and a hydrophilic film formed on the surface of the base material, and the hydrophilic film includes a hydrophilic material and a binder. Hereinafter, the configuration and operation effects of the porous membrane will be described in detail.

(1) Suppression of stratification of electrolyte solution Stratification of the electrolyte solution is a phenomenon in which sulfate ions and hydrogen sulfate ions in the electrolyte solution are settled, and the specific gravity of the electrolyte solution is different between the upper and lower parts of the battery case. Hereinafter, sulfate ions (SO ₄ ²⁻ ) and hydrogen sulfate ions (HSO ₄ ⁻ ) are collectively referred to as “sulfate ions”. In the present invention, by setting a porous membrane around the negative electrode and providing a physical barrier that inhibits the precipitation of sulfate ions, the precipitation of sulfate ions in the battery case can be prevented. Further, the hydrophilic film provided on the surface of the porous film is made of sulfuric acid that stays in the lower part of the battery case due to the action of the hydrophilic functional group contained in the hydrophilic material and the binder (details will be described later) constituting the hydrophilic film. Ions can be raised to the top. Therefore, it is possible to keep the concentration of sulfate ions inside the battery case uniform.

(2) High-rate discharge performance reduction suppression As a result of the study by the present inventors, the high-rate discharge performance is superior to the case where the hydrophilic coating is not provided when the hydrophilic coating is provided on the porous membrane substrate. I found out. This is presumably because a chemical interaction works between the sulfate ion and the hydrophilic film. Specifically, —OH groups are generated on the surface of SiO ₂ , Al ₂ O ₃ , BaSO ₄ or TiO ₂ used for the hydrophilic film (hydrophilic material). The —OH group on the surface of the hydrophilic film exists in the form of —OH ₂ ⁺ as a result of protonation in an aqueous sulfuric acid solution that is an electrolyte. It is considered that sulfate ions (SO ₄ ²⁻ and HSO ₄ ⁻ ) are attracted to this —OH ₂ ⁺ to cause a chemical interaction. That is, it is considered that the hydrophilic coating provided on the porous membrane interacts with sulfate ions, adsorbs and collects sulfate ions, and supplies them to the electrode (negative electrode). For this reason, it is considered that the supply efficiency of sulfate ions from the hydrophilic coating to the electrode determines the high rate discharge performance. Therefore, in order to improve the supply efficiency of sulfate ions from the hydrophilic coating to the electrode, the material of the hydrophilic coating was examined based on the following points.

  If the amount of hydrophilic functional groups such as -OH groups present on the surface of the hydrophilic coating is large, that is, if the hydrophilicity is high, sulfate ions are pulled up in the direction opposite to the gravitational direction, eliminating the concentration distribution of sulfuric acid in the battery case. Therefore, it is considered that the supply rate of sulfate ions to the electrode is improved. In order to construct such a hydrophilic coating surface, it is necessary to control the orientation of functional groups on the hydrophilic coating surface. That is, it is necessary to control the hydrophilic functional group to be oriented on the surface of the hydrophilic film. If the orientation of the functional group on the surface of the hydrophilic film is not controlled, the hydrophilic material surface may be coated with the hydrophobic functional group derived from the binder inside the hydrophilic film, which is not preferable. In general, a contact angle is used as a hydrophilicity index. However, when the contact angle of water or sulfuric acid of the hydrophilic coating is 10 ° or less, the hydrophilicity is particularly excellent and preferable. In order to control the functional group on the surface of the hydrophilic coating, it is necessary to select a binder in accordance with the functional group composition on the surface of the substrate (organic woven fabric, organic nonwoven fabric) of the hydrophilic coating.

  Hereinafter, the base material, the hydrophilic material and the binder constituting the porous film will be described in more detail.

[1] Porous Membrane Substrate As a porous membrane substrate through which the electrolytic solution can permeate, a fibrous woven fabric, a nonwoven fabric, or a porous body having pores can be used. The porous film may be organic or inorganic. Examples of the porous membrane material include polypropylene, cellulose, polyethylene, nylon, aramid, polyester, glass wool, and the like. Organic woven fabrics and organic nonwoven fabrics are particularly preferred because they have the advantage of being easier to manufacture than inorganic woven fabrics and inorganic nonwoven fabrics.

  The thickness of the substrate is preferably 0.03 mm to 0.1 mm in consideration of the ability to prevent the precipitation of sulfate ions, the influence on the battery reaction, the strength, and the like. If it is less than 0.03 mm, the strength is insufficient, and if it is more than 0.1 mm, the internal resistance becomes too large. Within this range, it is preferable to determine according to the material of the woven fabric and the nonwoven fabric and the size of the pores (voids). In this specification, “0.03 mm to 0.1 mm” means “0.03 mm to 0.1 mm”. The thickness of the substrate can be measured with an optical microscope or a micrometer.

  The size of the pores of the substrate is preferably a size that can hold sulfate ions. More specifically, the pore diameter is preferably 100 nm to 100 μm, more preferably 1 μm to 50 μm. When the hole which a base material has is the size mentioned above, it becomes possible to hold | maintain the sulfate ion in electrolyte solution, and to supply it efficiently to a negative electrode plate, and can contribute to suppression of internal resistance fall. If the pore size is smaller than 100 nm, sulfate ions cannot be inserted, and if it is larger than 100 μm, sulfate ions cannot be retained. Usually, the pore diameter of a separator (for example, a polymer material such as polyolefin resin) is about 30 to 40 nm, and it is difficult to retain sulfate ions with pores of this size. The pore structure of the substrate may be a regular structure such as an organic woven fabric or an irregular structure such as an organic nonwoven fabric.

  A hydrophilic coating can be formed on the surface of the base material by applying the hydrophilic paint described below to the base material described above, and heating and curing it. At this time, a hydrophilic film is formed on the fiber (skeleton) of the base material while maintaining the pores of the base material. The base material may be untreated or hydrophilized. The hydrophilization treatment may be either a surface treatment such as application of a surfactant such as polyglycerin or silicone, or a dry surface treatment such as plasma treatment. However, the binder contained in the hydrophilic paint is selected according to the type of functional group present on the surface of the substrate, and will be described in detail in [2] (b) Binder.

[2] Hydrophilic paint The hydrophilic paint for forming the hydrophilic film is composed of (a) a hydrophilic material, (b) a binder, and (c) a solvent. Both the hydrophilic material and the binder are present in the dispersion medium at a constant concentration to form a dispersion. The mass ratio of the addition amount of the solid component of the hydrophilic material and the solid component of the binder is preferably 90:10 to 70:30. When the mass ratio of the solid components is within this range, it is suitable for preparing a hydrophilic paint by mixing a hydrophilic material and a binder (good workability). After mixing the dispersion containing the hydrophilic material and the dispersion containing the binder, this mixing is performed so that the total concentration of the solid components of the hydrophilic material and the binder is 0.5 to 5 wt% with respect to the mixed dispersion. The liquid is diluted with a water-soluble solvent (for example, an alcohol solvent or water). If the concentration of the solid component is less than 0.5 wt%, the thickness of the hydrophilic film becomes non-uniform, and if it is more than 5 wt%, it is difficult to form a hydrophilic film, which is not preferable.

(A) Hydrophilic material In consideration of the chemical interaction acting between the sulfate ion and the hydrophilic film, the hydrophilic material is at least one selected from the group consisting of SiO ₂ , Al ₂ O ₃ , BaSO ₄ and TiO _2. It is preferable to use seeds. In particular, a mixture of SiO ₂ and Al ₂ O ₃ is preferable. SiO ₂ has a small contact angle with respect to the electrolytic solution, and Al ₂ O ₃ has many sulfate ion adsorption points (OH groups), which is considered advantageous in terms of suppressing stratification and improving discharge efficiency. When Al ₂ O ₃ is used, hydrophilic alumina sol can be used as the hydrophilic material. When a mixture of Al ₂ O ₃ and SiO ₂ is used, alumina sol and silica sol (colloidal silica) are used as the hydrophilic material. A mixture of can be used.

  An inorganic material that does not dissolve even when immersed in an acidic aqueous solution is preferable as a hydrophilic material because it can maintain hydrophilicity for a long period of time. Examples of such inorganic materials include hydrophilic silica particles and hydrophilic alumina sol. Specifically, silica sol (product name: IPA-ST-UP, IPA-ST, ST-OXS, ST-K2 and LSS-35) manufactured by Nissan Chemical Industries, Ltd., alumina sol manufactured by Nissan Chemical Industries (product) Name: AS-200). Since silica sol uses alcohol as a dispersion medium and alumina sol uses water as a dispersion medium, these can be easily mixed together.

Sol specific surface area of preferably used particles is 130m ² / g~1000m ² / g approximately. Assuming that the silica sol has a spherical shape, the particle diameter is 2 nm to 20 nm. Alumina sol, preferably the specific surface area of the contained alumina particles to use those which are 200m ² / g~400m ² / g approximately. Assuming that the shape of the alumina particles is plate-like, for example, an alumina sol containing alumina particles having dimensions (length, width, and height) of 10 nm × 10 nm × 100 nm can be used. The specific surface area of the silica sol and alumina sol is a factor that affects the adsorption point (-OH group) of sulfate ions, and the particle size is a factor that affects the specific surface area. The particle size is also a factor that affects the coating properties of the hydrophilic coating on the substrate.

(B) Binder An organic polymer material or an inorganic material can be used for the binder. Examples of the organic polymer material used for the binder include a polymer obtained by heating polyethylene glycol, polyvinyl alcohol, or the like. Examples of the inorganic material used for the binder include a material that becomes a holding body by heating, such as silica sol and a silane coupling agent. Among them, acrylamide, alkoxysilane, silica sol, and silane coupling agent are excellent in long-term stability in an acidic aqueous solution. In particular, a silane coupling agent is preferable because the orientation of the binder can be controlled as follows depending on the type of functional group constituting the silane coupling agent.

FIG. 3A is a diagram schematically showing an example of the structure of the base material (no surface treatment) according to the present invention, and FIG. 3B is a diagram schematically showing an example of the structure of the base material and the hydrophilic film according to the present invention. is there. 4A is a diagram schematically showing another example of the structure of the substrate according to the present invention, and FIG. 4B is a diagram schematically showing another example of the structure of the substrate and the hydrophilic film according to the present invention. It is. As shown in FIGS. 3A and 3B, the base material 12 is considered to have a surface with many hydrophobic functional groups (lipophilic functional groups) when the surface is not chemically treated. Examples of the hydrophobic functional group present on the surface of the substrate 12 include a methyl group (—CH ₃ group) and a methylene group (—CH ₂ group). In that case, a vinyl group (—CH═CH 2), a methacryl group (COC (CH ₃ ) ═CH ₂ ), an acrylic group (—COCH═CH ₂ ), or a styryl group (—CH═CHC), which is a hydrophobic functional group. _When a binder having a functional group such as ₆ H ₅ ) is selected, the hydrophobic functional group of the binder and the hydrophobic functional group of the base material are bonded, while the hydrophilic functional group of the binder is opposite to the base material ( It is arrange | positioned at the edge part of the surface of a hydrophilic film.

  For example, when a silane coupling agent having a vinyl group, methacryl group, acrylic group or styryl is selected as the binder, the vinyl group, methacryl group, acrylic group or styryl group is oriented to the substrate side, and is also generated by a hydrolysis reaction. The hydrophilic silanol group is considered to be oriented toward the opposite side (the surface side of the hydrophilic film).

On the other hand, as shown to FIG. 4A and 4B, when the surface of the base material 12 is hydrophilized, it is thought that it is a surface with many hydrophilic functional groups. Examples of the hydrophilic functional group include a hydroxyl group (—OH group), a carboxyl group (—COOH group), and an amino group (—NH ₂ ). In that case, if a binder having a hydrophilic isocyanate group (—N═C═O), an amino group (—NH ₂ ), or an epoxy group (first hydrophilic functional group) is selected, the first of the binder is selected. The hydrophilic functional group and the hydrophilic functional group of the substrate are bonded to each other, while the second hydrophilic functional group different from the first hydrophilic functional group of the binder is opposite to the substrate (hydrophilic coating (On the surface side).

  For example, when a silane coupling agent having an isocyanate group, amino group, or epoxy group is selected as the binder, the isocyanate group, amino group, or epoxy group reacts with the functional group on the substrate surface. It is considered that the hydrophilic silanol group generated by the decomposition is oriented toward the opposite side (the surface side of the hydrophilic film).

  Thus, the orientation of the functional group can be controlled by selecting the binder in accordance with the type of the functional group on the surface of the substrate, and the hydrophilic functional group (such as a silanol group) is oriented on the outermost surface side of the hydrophilic film. And a large number of —OH groups can be generated on the surface of the hydrophilic coating. As a result, it is possible to adsorb and raise sulfate ions staying in the lower part of the battery case to suppress stratification of the electrolytic solution. In addition, since sulfate ions are adsorbed and collected on the surface of the hydrophilic coating and supplied to the electrode plate, the supply efficiency of sulfate ions from the hydrophilic film to the electrode plate is improved, and a decrease in high-rate discharge performance can be suppressed.

  In particular, it is important to select a base material without surface treatment (having a hydrophobic functional group on the surface) and one having a functional group such as a vinyl group, a methacryl group, an acrylic group or a styryl group as a hydrophilic functional group. Since the control of the orientation of the group and the hydrophilic treatment of the substrate are unnecessary, it is preferable because the process can be shortened. In addition, the functional group of the base material and the binder can be analyzed by FT-IR (Fourier Transform Infrared Spectroscopy).

(C) Solvent The solvent used for diluting the liquid mixture of the hydrophilic material and the binder is preferably a solvent having good dispersibility and compatibility between the hydrophilic material and the binder, and the solvent is likely to volatilize during thermosetting. As a solvent satisfying these conditions, an alcohol solvent or water is preferable. Furthermore, in consideration of the heat resistance of the substrate, the boiling point is more preferably 100 ° C. or lower. Specific examples of the solvent include water, methanol, ethanol, and isopropyl alcohol.

  The hydrophilic film is preferably formed with a thickness of 10 nm to 100 nm. If it is thinner than 10 nm, the effect of adsorbing and holding sulfate ions is reduced, and if it is thicker than 100 nm, the internal resistance of the battery is increased. The thickness of the hydrophilic film can be measured by observing the cross section with SEM (Scanning Electron Microscope).

  By providing a porous film on which a hydrophilic film is formed around the negative electrode plate, it is possible to suppress stratification of the electrolyte and decrease in high-rate discharge performance in the lead-acid battery.

  In particular, in the lead-acid battery according to the present invention, when a porous film having a hydrophilic film is provided around the negative electrode plate separately from the separator, the porous film is disposed in a state of being more closely attached to the negative electrode plate. The effect of suppressing the stratification is higher than that when the effect of suppressing the stratification is given.

[3] Lead Acid Battery FIG. 1A is a perspective view schematically showing one embodiment of a lead acid battery according to the present invention, and FIG. 1B is a cross sectional view schematically showing a part of the electrode plate group of FIG. 1A. FIG. 1C is a perspective view schematically showing a part of the electrode plate group of FIG. 1A. As shown in FIGS. 1A to 1C, the lead storage battery 100 according to this embodiment includes a battery case 1 and a terminal 2 as an exterior part. Inside the battery case 1, a pole column 3 and a plate group 4 are provided. The pole 3 connects the electrode plate group 4 and the terminal 2. The electrode plate group 4 includes a negative electrode plate 5 including metal lead (Pb) as an active material, a positive electrode plate 7 including lead dioxide (PbO ₂ ), and a separator 6 disposed between the negative electrode plate 5 and the positive electrode plate 7. With.

  The negative electrode plate 5 and the positive electrode plate 7 are plate-like, and the negative electrode plate 5 and the positive electrode plate 7 are alternately laminated via the separator 6 to constitute the electrode plate group 4. In the embodiment shown in FIGS. 1A to 1C, the separator 6 has a bag shape and is configured to be disposed between the negative electrode plate 5 and the positive electrode plate 7 by housing the plate-like negative electrode plate 5. The separator 6 may be plate-shaped. The electrode plate group 4 is immersed in an electrolytic solution (not shown) containing dilute sulfuric acid and accommodated in the battery case 1 to constitute a lead storage battery.

  FIG. 2 is a diagram schematically showing the structure of a part of the electrode plate group 4 in FIG. 1A (particularly around the negative electrode plate). Around the negative electrode plate 5, a porous film 8 that is permeable to an electrolytic solution is provided. The separator 6 is disposed between the porous film 8 provided around the negative electrode plate 5 and the positive electrode plate 7. When the separator 6 is bag-shaped, the negative electrode plate 5 and the porous film 8 are accommodated. The porous membrane 8 has a base material 12 and a hydrophilic film 9 formed on the surface of the base material 12. The hydrophilic film 9 includes a hydrophilic material 10 and a binder (holding material) 11 having a hydrophilic functional group. The porous film 8 is preferably disposed so as to cover at least the entire one side surface of the negative electrode plate 5 facing the separator 6. As shown in FIG. 2, it is more preferable that the negative electrode plate 5 is disposed so as to cover both side surfaces (a surface facing the separator 6 and a surface opposite to this surface) and a bottom surface. The negative electrode plate 5 and the porous film 8 are preferably in contact with each other.

  The porous membrane 8 may store the negative electrode plate 5 in a bag shape like the separator 6 shown in FIG. 1C. Further, the hydrophilic film 9 may be formed on the surface of the separator 6 in addition to the porous film 8.

[Example 1]

  The lead storage battery according to the present invention described above was produced and tested. Table 1 is a table showing the configurations of the lead storage batteries of Examples and Comparative Examples of the present invention, and Table 2 is a table showing the evaluation of the effect of suppressing the stratification of the electrolytic solution and the evaluation of the high rate discharge performance. . The composition of the lead-acid battery includes the material of the base material (organic woven fabric), the composition of the surface functional groups of the base material, the hydrophilic material (X) and binder (holding material) (Y) of the hydrophilic film, and the mass of these solid components. The ratio (X: Y) is shown. As the material of the organic nonwoven fabric, polypropylene is represented by “PP” and polyethylene is represented by “PE”.

  Table 1 also shows a lead storage battery manufactured as a comparative example. In the following examples and comparative examples, an organic nonwoven fabric was provided around the negative electrode plate 5. In the examples, the thickness of the organic nonwoven fabric was unified to 0.1 mm, and the thickness of the hydrophilic film was unified to 100 nm. The following examples and comparative examples were examined by changing the surface functional group of the organic nonwoven fabric, the composition ratio of the hydrophilic material, and the type of the binder.

  The lead-acid battery according to Example 1 is provided with an organic nonwoven fabric made of PP on which a hydrophilic film 9 is formed around the negative electrode plate 5 as shown in FIG. A hydrophilic coating 9 was formed on the surface of the organic nonwoven fabric as follows.

An untreated polypropylene (PP) product was used as the organic nonwoven fabric. Only silica sol (SiO ₂ ) was used as the hydrophilic material 10, and a silane coupling agent having a vinyl group was used as the binder 11. That is, the hydrophilic material 10 contains 100 wt% silica sol (SiO ₂ ). Specifically, silica sol (product name: IPA-ST-UP) manufactured by Nissan Chemical Industries, Ltd. is used as the silica sol, and vinyltriethoxysilane (product name: KBE) manufactured by Shin-Etsu Chemical Co., Ltd. is used as the silane coupling agent. -1003) was used.

  The hydrophilic material 10 and the binder 11 were mixed so that the mass ratio (X: Y) of the solid components of the hydrophilic material 10 (X) and the binder 11 (Y) was 80:20. A hydrophilic paint was prepared by diluting this mixed solution with ethanol so that the concentration of the solid component was 5 wt%.

  After immersing the organic nonwoven fabric in this hydrophilic paint, the organic nonwoven fabric was pulled up at a speed of 156 mm / min. After removing the excess hydrophilic paint adhering to the organic nonwoven fabric by rolling the roller from above with the organic nonwoven fabric coated with hydrophilic paint sandwiched between Kim Towel (registered trademark), the organic nonwoven fabric is heated to 60 ° C in a constant temperature bath For 1 hour to remove the solvent. In this way, a hydrophilic film was formed on the surface of the organic nonwoven fabric. The hydrophilic film had a thickness of 100 nm. A lead-acid battery as shown in FIG. 1 in which an organic non-woven fabric with a hydrophilic coating 9 formed is placed around the negative electrode plate 5 (disposed so as to cover the side and bottom surfaces on both sides of the negative electrode plate) and dilute sulfuric acid is used as the electrolyte. Was made.

This lead storage battery was first evaluated for the effect of suppressing stratification of the electrolyte.
In the cycle test, the lead storage battery was placed in an atmosphere at 25 ° C., and the following (i), (ii), and (iii) were taken as one cycle, and this cycle was repeated 3600 times (according to the battery industry association standard SBAS0102).
(I) Discharge for 45 seconds at a discharge current of 45A (ii) Discharge for 1 second at a discharge current of 300A (iii) Constant current and constant voltage charge at a charge voltage of 14V (limit current of 100A) for 60 seconds 3600th time The specific gravity difference of the electrolyte in the lower part was used as an index for stratification. That is, in the 3600th cycle, the specific gravity of the electrolyte solution in the lower part of the battery case and the specific gravity of the electrolyte solution in the upper part are measured, and these specific gravities are obtained. evaluated. The specific gravity was converted to 20 ° C. The upper part in the battery case is a position 1 cm above the upper end of the electrode plate group 4, and the lower part in the battery case is a position 1 cm below the lower end of the electrode plate group 4. The height of the electrode plate group 4 indicates a length of 116 mm from the lower part of the electrode plate group 4 to the upper end of the separator 6. The specific evaluation criteria are “A” when the specific gravity difference is 0.02 or less, “B” when 0.04 or less and greater than 0.02 and 0.07 or less and greater than 0.04. The case where “C” was greater than 0.07 was designated “D”. In this evaluation standard, stratification is suppressed in the order of A, B, C, and D.

  The lead battery according to this example has a small specific gravity difference of 0.03, which is evaluated as B, indicating that stratification is suppressed.

  Next, the high rate discharge performance of the lead storage battery was evaluated. The high rate discharge performance was measured in accordance with the JIS standard (JIS 5301: 2006) with a discharge current of 150 A and a final voltage of 6 V after the lead storage battery was allowed to stand for 16 hours under a temperature condition of −15 ° C. In general, it is known that when a porous film 8 is installed inside a lead-acid battery, high-rate discharge performance is degraded. Therefore, when the high-rate discharge performance when the porous film 8 is not installed around the negative electrode plate 5 is 100, the decrease in the high-rate discharge performance is small (when the high-rate discharge performance is close to 100). It was evaluated that the decrease in performance could be suppressed.

  Specific evaluation criteria were high rate discharge performance of 100 or less and 95 or more as “A”, less than 95 or 91 or more as “B”, less than 91 or 87 or more as “C”, and less than 87 as “D”. In this evaluation standard, a decrease in the high rate discharge performance is suppressed in the order of A, B, C, and D.

The lead storage battery according to this example has an evaluation A of high-rate discharge performance of 95, and it was found that the decrease in high-rate discharge performance is extremely small. That is, it turned out that the lead acid battery by a present Example can suppress the fall of high rate discharge performance.
[Example 2]

  The lead storage battery of Example 2 has the same configuration as the lead storage battery of Example 1, but the following points are different. In the following, differences will be mainly described.

In the lead storage battery of this example, a PP organic nonwoven fabric that had been subjected to a hydrophilic treatment to generate —OH groups and —COOH groups on the surface of the organic nonwoven fabric was used. Only silica sol (SiO ₂ ) was used as the hydrophilic material 10, and a silane coupling agent having an epoxy group was used as the binder 11. That is, the hydrophilic material contains 100 wt% silica sol (SiO ₂ ). Specifically, silica sol (product name: IPA-ST-UP) manufactured by Nissan Chemical Co., Ltd. is used as the silica sol, and 3-glycidoxypropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) is used as the silane coupling agent. Product name: KBM-403) was used.

  The hydrophilic material 10 and the support material 11 were mixed so that the mass ratio (X: Y) of the solid components of the hydrophilic material 10 (X) and the binder 11 (Y) was 80:20. A hydrophilic paint was prepared by diluting this mixed solution with ethanol so that the concentration of the solid component was 5 wt%.

The lead acid battery according to this example has a small specific gravity difference of 0.04, which is evaluated as B, indicating that stratification is suppressed. Moreover, the lead acid battery by a present Example was set to evaluation A with high-rate discharge performance 95, and it turned out that the fall of high-rate discharge performance can be suppressed.
[Example 3]

  The lead acid battery according to Example 3 has the same configuration as that of the lead acid battery according to Example 1, except for the following points. In the following, differences will be mainly described.

In the lead storage battery of this example, untreated polypropylene (PP) was used as the organic nonwoven fabric. As the hydrophilic material 10, only alumina sol (Al ₂ O ₃ ) was used, and as the binder 11, a silane coupling agent having a methacryl group was used. That is, the hydrophilic material contains 100 wt% alumina sol (Al ₂ O ₃ ). Specifically, alumina sol (product name: AS-200) manufactured by Nissan Chemical Industries, Ltd. as the alumina sol, and 3-methacryloxypropyltriethoxysilane (product name) manufactured by Shin-Etsu Chemical Co., Ltd., as the silane coupling agent. : KBE-503) was used.

  The hydrophilic material 10 and the binder 11 were mixed so that the mass ratio (X: Y) of the solid components of the hydrophilic material 10 (X) and the binder 11 (Y) was 90:10. A hydrophilic paint was prepared by diluting this mixed solution with ethanol so that the concentration of the solid component was 5 wt%.

In the lead storage battery of this example, the specific gravity difference of the electrolytic solution was as small as 0.04, which was evaluated as B, and it was found that stratification was suppressed. Moreover, the lead acid battery of a present Example became evaluation B with high-rate discharge performance 93, and it turned out that the fall of high-rate discharge performance can be suppressed.
[Example 4]

  The lead acid battery according to Example 4 has the same configuration as that of the lead acid battery according to Example 1, except for the following points. In the following, differences will be mainly described.

In the lead storage battery of this example, untreated polyethylene (PE) was used as the organic nonwoven fabric. Silica sol (SiO ₂ ) and alumina sol (Al ₂ O ₃ ) were used as the hydrophilic material 10, and a silane coupling agent having a vinyl group was used as the binder 11. In the hydrophilic material, the mass ratio of alumina sol to silica sol was 80:20. That is, the hydrophilic material 10 contains 80 wt% alumina sol (Al ₂ O ₃ ). Specifically, silica sol (product name: IPA-ST-UP) manufactured by Nissan Chemical Industries, Ltd. is used as the silica sol, alumina sol (product name: AS-200) manufactured by Nissan Chemical Industries, Ltd. is used as the alumina sol, and silane. As the coupling agent, vinyltriethoxysilane (product name: KBE-1003) manufactured by Shin-Etsu Chemical Co., Ltd. was used.

  The hydrophilic material 10 and the binder 11 were mixed so that the mass ratio (X: Y) of the solid components of the hydrophilic material 10 (X) and the binder 11 (Y) was 80:20. A hydrophilic paint was prepared by diluting this mixed solution with ethanol so that the concentration of the solid component was 5 wt%.

In the lead storage battery of this example, the specific gravity difference of the electrolytic solution was as small as 0.04, which was evaluated as B, and it was found that stratification was suppressed. Moreover, the lead acid battery of a present Example became evaluation B with high-rate discharge performance 93, and it turned out that the fall of high-rate discharge performance can be suppressed.
[Example 5]

  The lead storage battery of Example 5 has the same configuration as the lead storage battery of Example 1, but the following points are different. In the following, differences will be mainly described.

In the lead storage battery of this example, a PE organic non-woven fabric that had been subjected to a hydrophilic treatment to generate —OH groups and —COOH groups on the surface of the organic non-woven fabric was used. Silica sol (SiO ₂ ) and alumina sol (Al ₂ O ₃ ) were used as the hydrophilic material 10, and a silane coupling agent having a vinyl group was used as the binder 11. Specifically, silica sol (product name: IPA-ST-UP) manufactured by Nissan Chemical Industries, Ltd. is used as the silica sol, alumina sol (product name: AS-200) manufactured by Nissan Chemical Industries, Ltd. is used as the alumina sol, and silane. As a coupling agent, 3-glycidoxypropyltrimethoxysilane (product name: KBM-403) manufactured by Shin-Etsu Chemical Co., Ltd. was used. In the hydrophilic material, the mass ratio of alumina sol to silica sol was set to 70:30. That is, the hydrophilic material 10 includes 70 wt% alumina sol (Al ₂ O ₃ ).

  The hydrophilic material 10 and the binder 11 were mixed so that the mass ratio (X: Y) of the solid components of the hydrophilic material 10 (X) and the binder 11 (Y) was 70:30. A hydrophilic paint was prepared by diluting this mixed solution with ethanol so that the concentration of the solid component was 5 wt%.

In the lead storage battery of this example, the specific gravity difference of the electrolytic solution was as small as 0.04, which was evaluated as B, and it was found that stratification was suppressed. Moreover, the lead acid battery of a present Example became evaluation B with high-rate discharge performance 94, and it turned out that the fall of high-rate discharge performance can be suppressed.
[Comparative Example 1]

  The lead acid battery according to Comparative Example 1 has the same configuration as that of the lead acid battery according to Example 1, except for the following points. In the following, differences will be mainly described.

  In the lead storage battery of this comparative example, the porous film 8 was not provided around the negative electrode plate 5.

  The lead acid battery according to this comparative example has an extremely large specific gravity difference of 0.08, which is evaluated as D, and it has been found that stratification cannot be suppressed. Moreover, since the lead acid battery according to this comparative example does not have the porous film 8 around the negative electrode plate 5, the high rate discharge performance is 100 as an evaluation standard.

By providing the porous film 8 around the negative electrode plate 5 according to this comparative example and Examples 1 to 5, it was confirmed that the specific gravity difference of the electrolytic solution can be reduced and the stratification of the electrolytic solution can be suppressed. .
[Comparative Example 2]

  The lead acid battery according to Comparative Example 2 has the same configuration as that of the lead acid battery according to Example 1, except for the following points. In the following, differences will be mainly described.

  In the lead storage battery according to this comparative example, the organic nonwoven fabric made of PP was provided around the negative electrode plate 5, but the hydrophilic film 9 was not formed on the organic nonwoven fabric.

The lead acid battery according to this comparative example was evaluated C when the specific gravity difference of the electrolyte was 0.05, and was evaluated B when the high rate discharge performance was 91. Since the surface of the organic nonwoven fabric does not have a hydrophilic film, both the suppression of the stratification of the electrolyte and the suppression of the deterioration of the high rate discharge characteristics were inferior to those of Example 1.
[Comparative Example 3]

  The lead acid battery according to Comparative Example 3 has the same configuration as that of the lead acid battery according to Example 1, except for the following points. In the following, differences will be mainly described.

  In the lead storage battery of this comparative example, the hydrophilic film 9 was formed on the surface of the organic nonwoven fabric 8 provided around the negative electrode plate 5 as follows. An untreated polypropylene (PP) product was used as the organic nonwoven fabric. The composition of the hydrophilic film was the same as in Example 1, but a hydrophilic coating was prepared by diluting with ethanol so that the concentration of the solid component was 0.3 wt%.

When this paint was used, the film thickness of the hydrophilic film 9 became non-uniform, and a portion where the organic nonwoven fabric 8 was not covered was also observed. The lead acid battery according to this example was evaluated C when the specific gravity difference of the electrolyte was 0.05, and evaluated B when the high-rate discharge performance was 91. When it was outside the specified range (10 nm to 100 nm) of the hydrophilic coating, both the stratification suppression and the high rate discharge performance were inferior to those of Example 1.
[Comparative Example 4]

  The lead acid battery according to Comparative Example 4 has the same configuration as that of the lead acid battery according to Example 1, except for the following points. In the following, differences will be mainly described.

  In the lead storage battery according to this comparative example, the hydrophilic film 9 was formed on the surface of the organic nonwoven fabric 8 provided around the negative electrode plate 5 as follows. As the organic nonwoven fabric, an untreated polypropylene (PP) product having a film thickness of 0.3 mm was used. The preparation method and composition of the hydrophilic film were the same as in Example 1.

The lead acid battery according to this example was evaluated C when the specific gravity difference of the electrolyte was 0.05, and was evaluated D when the high rate discharge performance was 86. When the film thickness of the organic nonwoven fabric 8 was outside the specified range (0.03 mm to 0.1 mm), the internal resistance increased, resulting in particularly inferior high rate discharge performance as compared with Example 1.
[Comparative Example 5]

  The lead storage battery of Comparative Example 5 has the same configuration as the lead storage battery of Example 1, but the following points are different. In the following, differences will be mainly described.

  In the lead storage battery according to this comparative example, the hydrophilic film 9 having the same composition as that of Example 1 was formed on the separator 6, and the porous film 8 was not provided around the negative electrode. The lead acid battery of this example was evaluated D when the specific gravity difference of the electrolyte was 0.08, and was evaluated as A when the high rate discharge performance was 98. As shown in this comparative example, it was found that even when a hydrophilic film was formed on the separator, the same stratification inhibitory effect as when a hydrophilic film was formed on the organic nonwoven fabric could not be obtained.

  Regarding the specific gravity difference and high-rate discharge performance of the electrolyte solution, both of which are compatible at a high level (specific gravity difference of the electrolyte solution: 0.04 or less and high-rate discharge performance: 93 or more) are evaluated as “◯”. Those not satisfying one or both were evaluated as “Δ” (Table 2). Examples 1 to 5 were all “◯”, but Comparative Examples 1 to 5 were all “Δ”.

  From the above results, it was shown that the lead storage battery according to this example can achieve both high levels of suppression of stratification and suppression of deterioration of high-rate discharge performance.

  In addition, this invention is not limited to said Example, Various modifications are included. For example, the above-described embodiments are described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to an aspect including all the configurations described.

  DESCRIPTION OF SYMBOLS 1 ... Battery case, 2 ... Terminal, 3 ... Polar pole, 4 ... Electrode plate group, 5 ... Negative electrode plate, 6 ... Separator, 7 ... Positive electrode plate, 8 ... Porous membrane, 9 ... Hydrophilic film, 10 ... Hydrophilic material, DESCRIPTION OF SYMBOLS 11 ... Binder, 12 ... Base material, 100 ... Lead acid battery.

Claims (12)

A positive electrode plate containing lead dioxide;
A negative electrode plate containing metallic lead;
A separator disposed between the positive electrode plate and the negative electrode plate;
An electrolyte containing dilute sulfuric acid, in which an electrode plate group including the positive electrode plate, the negative electrode plate, and the separator is immersed;
A battery case for storing the electrode plate group and the electrolytic solution;
Around the negative electrode plate is provided a porous membrane that allows the electrolyte to pass through,
The porous membrane includes a base material having a hydrophobic functional group, and a hydrophilic film formed on the surface of the base material,
The hydrophilic coating includes a hydrophilic material and a binder,
The binder has a hydrophobic functional group and a hydrophilic functional group,
Having a configuration in which the hydrophobic functional group of the binder and the hydrophobic functional group of the substrate are bonded,
The lead acid battery according to claim 1, wherein the binder has the hydrophilic functional group at an end portion on a surface side of the hydrophilic coating. A positive electrode plate containing lead dioxide;
A negative electrode plate containing metallic lead;
A separator disposed between the positive electrode plate and the negative electrode plate;
An electrolyte containing dilute sulfuric acid, in which an electrode plate group including the positive electrode plate, the negative electrode plate, and the separator is immersed;
A battery case for storing the electrode plate group and the electrolytic solution;
Around the negative electrode plate is provided a porous membrane that allows the electrolyte to pass through,
The porous membrane includes a base material having a hydrophilic functional group, and a hydrophilic film formed on the surface of the base material,
The hydrophilic coating includes a hydrophilic material and a binder,
The binder has a first hydrophilic functional group and a second hydrophilic functional group,
The binder has a configuration in which the first hydrophilic functional group of the binder and the hydrophilic functional group of the substrate are bonded to each other;
The lead acid battery according to claim 1, wherein the binder has the second hydrophilic functional group at an end portion on a surface side of the hydrophilic coating.   The lead acid battery according to claim 1, wherein the hydrophobic functional group of the binder is a vinyl group, a methacryl group, an acrylic group, or a styryl group.   The lead acid battery according to claim 2, wherein the first hydrophilic functional group of the binder is an amino group, an isocyanate group or an epoxy group.   The lead acid battery according to any one of claims 1 to 4, wherein the porous film is an organic woven fabric or an organic nonwoven fabric. The lead acid battery according to claim 1, wherein the hydrophilic material is at least one selected from the group consisting of SiO ₂ , Al ₂ O ₃ , BaSO _4, and TiO _2. .   The lead acid battery according to any one of claims 1 to 6, wherein the added hydrophilic material and the solid component of the binder have a mass ratio of 90:10 to 70:30.   The lead acid battery according to any one of claims 1 to 7, wherein the hydrophilic coating has a thickness of 10 nm to 100 nm.   The lead acid battery according to any one of claims 1 to 8, wherein the base material has a thickness of 0.03 mm to 0.1 mm.   The lead-acid battery according to any one of claims 1 to 9, wherein the pores of the porous film have a pore diameter of 100 nm to 100 µm.   The lead acid battery according to any one of claims 1 to 10, wherein the porous film is disposed so as to cover a side surface and a bottom surface on both sides of the negative electrode plate.   Furthermore, the said hydrophilic film is formed in the surface of the said separator, The lead acid battery of any one of the Claims 1 thru | or 11 characterized by the above-mentioned.

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