JP7314747B2 - Negative electrode plate for lead-acid battery and lead-acid battery provided with the same - Google Patents

Description

The present invention relates to a negative electrode plate for a lead-acid battery and a lead-acid battery.

Lead-acid batteries are used in a variety of applications, including in-vehicle use and industrial use. A lead-acid battery includes a negative plate, a positive plate, and an electrolyte. The negative plate includes a current collector and a negative electrode material. An organic anti-shrinking agent is added to the negative electrode material. As the organic shrink-proofing agent, naturally occurring organic shrink-proofing agents such as sodium lignosulfonate, as well as synthetic organic shrink-proofing agents are used. Synthetic organic shrink-proofing agents include, for example, condensates of bisphenols.

Patent Document 1 describes a lead-acid battery including a positive electrode, a negative electrode, and an electrolytic solution, wherein the negative electrode includes a negative electrode material and a negative electrode current collector, the negative electrode material includes a bisphenol-based resin and a negative electrode active material, the negative electrode current collector has an ear portion, and the ear portion is formed with a surface layer of Sn or an Sn alloy.

Patent Document 2 describes a flooded lead-acid battery comprising a negative electrode active material containing spongy lead as a main component, a positive electrode active material containing lead dioxide as a main component, and a freely flowing electrolytic solution containing sulfuric acid, wherein the negative electrode active material contains carbon, at least one substance selected from the group consisting of cellulose ether, polycarboxylic acid and salts thereof, and a water-soluble polymer composed of a bisphenol condensate having a sulfonic acid group, and the positive electrode active material contains antimony. .

Patent Document 3 describes a valve-regulated lead-acid battery including a positive electrode plate, a negative electrode plate, and an electrolyte, wherein the negative electrode plate has a negative current collector and a negative electrode material, the density of the negative electrode material is greater than 2.6 g/cm ³ , the negative electrode material contains an organic preservative, and the sulfur element content in the organic preservative is greater than 600 μmol/g.

Patent Document 4 describes a lead-acid battery comprising a negative electrode material, the negative electrode material containing an organic expander, and the organic expander containing sulfur element (S element) of 3000 μmol/g or more.

Lead-acid batteries may also be used in an undercharged state called a partial state of charge (PSOC). For example, a lead-acid battery installed in an idling stop/start (ISS) vehicle is used in a PSOC. When a lead-acid battery is used in a PSOC, the thickness of the ears provided for current collection on the upper portion of the negative electrode plate may be reduced due to corrosion, resulting in reduced life performance. From the viewpoint of suppressing such corrosion of the ears, providing a surface layer on the ears has been studied.

Patent Document 5 describes a lead-acid battery that includes a positive electrode plate, a negative electrode plate that includes an upper edge on the upper portion of a negative electrode grid body that includes a negative electrode active material and an ear portion on the upper portion of the upper edge portion, and an electrolytic solution, in which at least one of the upper edge portion and the ear portion of the negative electrode plate is provided with a surface layer of a Pb—Sn-based alloy, and the electrolytic solution contains Li ions at a concentration of 0.02 mol/L or more and 0.2 mol/L or less. It is described that lignin is used for the negative electrode active material paste.

Patent Document 6 discloses a positive electrode plate using a positive electrode grid made of a lead-calcium-tin alloy, a negative electrode grid portion filled with a negative electrode active material, a negative electrode edge connected to the edge of the negative electrode grid portion, and a negative electrode ear portion for current collection protruding from the negative electrode edge portion. A lead-acid battery is described which includes an inter-cell connecting portion for connecting between cells and an electrode column connected from the strap to a battery terminal, wherein at least the strap is made of a lead-antimony alloy among the strap, the inter-cell connecting portion and the electrode column, the negative electrode ear portion is provided with a lead-tin alloy layer, and the negative electrode active material contains carbon in an amount corresponding to 0.25 to 0.75% of the mass of the negative electrode active material after full charge. It is described that lignin is used for the negative electrode active material paste.

JP 2017-79166 A WO2013/150754 JP 2018-18742 A WO2016/194328 JP 2015-187990 A (claim 1, [0017]) WO 2010/032782 (claim 1, [0036])

When a surface layer containing a lead alloy containing Sn is formed on the negative electrode ear portion, corrosion of the ear portion of the negative electrode plate during charging and discharging of the lead-acid battery with PSOC can be effectively suppressed, and reduction in the thickness of the ear portion can be suppressed, compared to the case where the surface layer is not formed. However, part of the Pb contained in the surface layer may gradually corrode and fall off during charging and discharging. Accompanying this, Sn contained in the surface layer also falls off, so that it may become difficult to maintain the corrosion-suppressing effect of the surface layer on the ears.

One aspect of the present invention includes a negative electrode current collector having ears, and a negative electrode material carried on the negative electrode current collector,
The ears have a surface layer containing a lead alloy containing Sn,
The negative electrode material comprises an organic expander containing units of an aromatic compound,
The organic anti-shrinking agent relates to a negative electrode plate for a lead-acid battery, comprising a first organic anti-shrinking agent (excluding the lignin compound) containing an aromatic compound unit having a hydroxy group.

In a lead-acid battery that is charged and discharged in a PSOC cycle, it is possible to suppress a decrease in the thickness of the ear portion of the negative electrode plate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway exploded perspective view showing the appearance and internal structure of a lead-acid battery according to one aspect of the present invention; 4 is a graph showing the relationship between the Sn content in the surface layer of the negative electrode plate and the thickness reduction amount of the ear portion in Table 3. FIG. 4 is a graph showing the relationship between the molar ratio of phenolsulfonic acid units to the total amount of bisphenol S units and phenolsulfonic acid units in Table 4 and low temperature high rate (HR) discharge performance. 5 is a graph showing the relationship between the molar ratio of phenolsulfonic acid units to the total amount of bisphenol A units and phenolsulfonic acid units in Table 5 and low-temperature HR discharge performance. 6 is a graph showing the relationship between the molar ratio of bisphenol S units to the total amount of bisphenol S units and bisphenol A units in Table 6 and low-temperature HR discharge performance.

A negative electrode plate for a lead-acid battery according to one aspect of the present invention includes a negative electrode current collector having ears, and a negative electrode material carried on the negative electrode current collector. The ear has a surface layer containing a lead alloy containing Sn. The negative electrode material comprises an organic expander containing aromatic units. The organic expanders include a first organic expander (excluding lignin compounds) comprising units of aromatic compounds having hydroxy groups.

A lead-acid battery according to another aspect of the present invention includes the negative electrode plate, the positive electrode plate, and the electrolytic solution.

If a surface layer containing Sn is provided as in Patent Document 5 or Patent Document 6 on the ears provided for current collection on the upper part of the negative electrode plate of a lead-acid battery, corrosion of the ears can be greatly suppressed when charge and discharge are performed in the PSOC cycle compared to the case where the surface layer is not provided. This is because in the PSOC cycle, oxidation and reduction reactions of Sn are less likely to occur within the potential range of the negative electrode plate. However, when the PSOC is repeatedly charged and discharged, part of the Pb contained in the Sn-containing surface layer may gradually corrode and fall off. At this time, Sn contained in the surface layer is also removed together with Pb. If such detachment occurs, it may become difficult to maintain the anti-corrosion effect of the surface layer on the ears.

According to one aspect and another aspect of the present invention, a surface layer containing a lead alloy containing Sn is provided on the ear portion of a negative electrode current collector, and a negative electrode material containing a first organic shrinkage agent is used. Although the first organic expander has high adsorptivity for lead contained in the negative electrode material, part of the first organic expander inevitably elutes from the negative electrode material. However, since the first organic anti-shrinking agent has a high adsorptivity to lead, even if a part of the first organic anti-shrinking agent is eluted, it will be adsorbed on the lugs of the negative electrode plate. Adsorption of the first organic anti-shrinking agent to the lugs reduces the contact area between the sulfuric acid and the surface layer, thereby suppressing corrosion of the surface layer and maintaining the corrosion-inhibiting effect of the surface layer on the lugs. In addition, the adsorption of the first organic anti-shrinking agent to the lugs can reduce the oxidation-reduction reaction area of lead in the lugs, so that the corrosion inhibiting effect itself of the lugs can be enhanced. In this way, the first organic anti-shrinking agent and the surface layer can more effectively suppress the corrosion of the lugs and suppress the reduction in the thickness of the lugs of the negative electrode plate. Such an effect of suppressing the thickness reduction of the selvage portion is more remarkable than expected from the respective effects of the first organic shrink-proofing agent and the surface layer, and it has been clarified that it is a synergistic effect.

The first organic anti-shrinking agent is an organic anti-shrinking agent other than the lignin compound having an aromatic compound unit having a hydroxy group. The first organic expander is a synthetic organic expander. Lignin compounds are excluded from synthetic organic expanders, which are synthetic because they are natural sources. Synthetic organic expanders used in lead-acid batteries are typically organic condensates. Unlike naturally occurring lignin compounds, such condensates tend to form a portion having a planar structure in the molecule. Therefore, the once eluted first organic anti-shrinking agent is likely to be adsorbed to the lead contained in the lugs and surface layer of the negative electrode plate. As a result, the first organic anti-shrinking agent can be effectively adsorbed on the lugs and the surface layer, so that a high anti-corrosion effect on the lugs as described above can be obtained. On the other hand, the lignin compound has a complicated three-dimensional network structure and is easily eluted from the negative electrode material as compared with the first organic shrink-proofing agent. However, the lignin compound is inferior to the first organic anti-shrinking agent in adsorbability to lead contained in the lugs and surface layer of the negative electrode plate. Therefore, in the case of a lignin compound, it is difficult to obtain the above-described high anti-corrosion effect of the lugs, and it is difficult to suppress the decrease in the thickness of the lugs.

As used herein, a lignin compound means lignin and lignin derivatives. Lignin derivatives include those having a lignin-like three-dimensional structure. Examples of lignin derivatives include at least one selected from the group consisting of modified lignin, ligninsulfonic acid, modified ligninsulfonic acid, and salts thereof (alkali metal salts (such as sodium salts), magnesium salts, calcium salts, etc.).

The lead-acid battery may be either a valve-regulated (sealed) lead-acid battery or a flooded (vented) lead-acid battery. A lead-acid battery is particularly useful as a lead-acid battery (for example, an idling stop (IS) lead-acid battery) that is assumed to be charged and discharged in a PSOC.

A lead-acid battery and a negative electrode plate according to embodiments of the present invention will be described below for each main component, but the present invention is not limited to the following embodiments.

[Lead storage battery]
(negative plate)
A negative electrode plate usually includes a negative electrode current collector in addition to a negative electrode material. The negative electrode material is obtained by removing the negative electrode current collector from the negative electrode plate. A member such as a mat or pasting paper may be attached to the negative electrode plate. Since such a member (attaching member) is used integrally with the negative electrode plate, it is included in the negative electrode plate. Moreover, when the negative electrode plate includes a sticking member, the negative electrode material excludes the negative electrode current collector and the sticking member. However, when a pasting member (mat, pasting paper, etc.) is pasted on the separator, the thickness of the pasting member is included in the thickness of the separator.

The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead sheet or a lead alloy sheet. Processing methods include, for example, expanding processing and punching processing. It is preferable to use a grid-like current collector as the negative electrode current collector because it facilitates the support of the negative electrode material.

The lead alloy used for the negative electrode current collector may be either a Pb--Ca alloy or a Pb--Ca--Sn alloy. These lead or lead alloys may further contain at least one selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, etc. as an additive element.

The negative electrode current collector has a surface layer at least on the ears. The surface layer of the ear contains a lead alloy containing Sn. Such a surface layer suppresses the oxidation-reduction reaction of the ears during charging and discharging by the PSOC cycle, so that the corrosion of the ears can be effectively reduced.

The Sn content in the surface layer of the ear portion is, for example, 2% by mass or more, may be 2.5% by mass or more, may be 5% by mass or more, or may be 7.5% by mass or more. When the Sn content in the surface layer of the lugs exceeds 7.5% by mass (preferably 10% by mass or more), the effect of suppressing corrosion of the lugs can be remarkably improved, which is preferable. The Sn content in the surface layer may be 15% by mass or more. From the viewpoint of suppressing capacity reduction due to self-discharge, the Sn content in the surface layer of the ear is preferably less than 50% by mass, and may be 30% by mass or less, 25% by mass or less, or 20% by mass or less.

The content of Sn in the surface layer of the ear is 2% by mass or more and less than 50% by mass (or 30% by mass or less), 2.5% by mass or more and less than 50% by mass (or 30% by mass or less), 5% by mass or more and less than 50% by mass (or 30% by mass or less), 7.5% by mass or more and less than 50% by mass (or 30% by mass or less), 7.5% by mass or more and less than 50% by mass (or 30% by mass or less), 10% by mass or more and less than 50% by mass. (or 30 mass% or less), 15 mass% or more and less than 50 mass% (or 30 mass% or less), 2 mass% or more and 25 mass% or less (or 20 mass% or less), 2.5 mass% or more and 25 mass% or less (or 20 mass% or less), 5 mass% or more and 25 mass% or less (or 20 mass% or less), 7.5 mass% or more and 25 mass% or less (or 20 mass% or less), 7.5 mass% or more and 25 mass% or less (or 20 mass% or less) ), 10% by mass or more and 25% by mass or less (or 20% by mass or less), or 15% by mass or more and 25% by mass or less (or 20% by mass or less).

The amount of Sn contained in the surface layer of the ear can be analyzed according to, for example, lead separation inductively coupled plasma emission spectroscopy described in JIS H2105. Prior to the analysis, the cross section of the tab of the negative electrode plate taken out from the lead-acid battery is observed with a metallurgical microscope. Then, an outer layered portion having different properties (color, state of metal particles, etc.) from the inner side is used as a surface layer, and a portion of the layered portion is scraped off to measure the mass. The sample collected in this way is decomposed with tartaric acid and dilute nitric acid to obtain an aqueous solution. Add hydrochloric acid to the aqueous solution to precipitate lead chloride, filter, and collect the filtrate. Using an ICP emission spectrometer (eg, ICPS-8000 manufactured by Shimadzu Corporation), the Sn concentration in the filtrate is analyzed by the calibration curve method, and converted to the Sn content per mass of the ear surface layer.

The thickness of the surface layer of the ear portion is, for example, 0.01 mm or more. From the viewpoint of ensuring a higher corrosion inhibiting effect, the thickness of the surface layer of the ear may be 0.015 mm or more or 0.02 mm or more. From the viewpoint of reducing self-discharge, the thickness of the surface layer of the ear is preferably 0.1 mm or less, and may be 0.05 mm or less.

The thickness of the surface layer of the ear may be 0.01 mm or more and 0.1 mm or less (or 0.05 mm or less), 0.015 mm or more and 0.1 mm or less (or 0.05 mm or less), or 0.02 mm or more and 0.1 mm or less (or 0.05 mm or less).

The thickness of the surface layer of the ear can be obtained by the following procedure. First, the ears of the negative electrode plate are impregnated with epoxy resin and hardened. Next, the ear portion is cut along the thickness direction of the ear portion, and the cut surface is polished. The polished cut surface is observed with a metallurgical microscope, and the thickness of the surface layer is determined by measuring and averaging the thickness of the surface layer at any five points, with the outer layered portion having different properties (color, state of metal particles, etc.) from the inner side as the surface layer.

The analysis and measurement of the thickness of the surface layer of the lug portion of the negative electrode plate shall be performed on the negative electrode plate of the lead-acid battery in a fully charged state. Prior to the analysis or thickness measurement, the negative electrode plate to be analyzed is obtained by fully charging the chemically formed lead-acid battery and then dismantling it.

In this specification, the fully charged state of a liquid lead-acid battery is defined by JIS D 5301:2006. More specifically, the lead-acid battery is charged in a water tank at 25°C ± 2°C at a current (A) that is 0.2 times the value described as the rated capacity until the terminal voltage during charging measured every 15 minutes or the electrolyte density converted to temperature at 20°C shows a constant value with three significant digits three times consecutively. In the case of a valve-controlled lead-acid battery, the fully charged state is a state in which the lead-acid battery is charged in an air tank at 25° C.±2° C. at a current (A) that is 0.2 times the value described as the rated capacity, and is charged at a constant current and constant voltage of 2.23 V/cell, and charging is completed when the charging current (A) during constant-voltage charging reaches 0.005 times the value described as the rated capacity. In addition, the numerical value described as a rated capacity is a numerical value which made the unit Ah. The unit of current set based on the numerical value described as the rated capacity is A.

A fully-charged lead-acid battery refers to a fully-charged chemical lead-acid battery. The lead-acid battery may be fully charged immediately after the formation as long as it is after the formation, or after some time has passed since the formation (for example, after the formation, a lead-acid battery in use (preferably at the beginning of use) may be fully charged). A battery in the early stage of use means a battery in which not much time has passed since the start of use and which has hardly deteriorated.

The negative electrode current collector may have a surface layer on portions other than the ear portions (for example, at least one of the lattice portion and the frame portion of the positive electrode current collector). The composition of the surface layer of the portion other than the ears may be the same as or different from the composition of the surface layer of the ears. The composition of the surface layer of the portion other than the ear portion and the inner layer may be different. The surface layer of the portion other than the ear portion may be formed on a part of the portion other than the ear portion.

The negative electrode material includes a first organic prescaling agent. The negative electrode material usually further contains a negative electrode active material (lead or lead sulfate) that develops capacity through an oxidation-reduction reaction. The negative electrode material may contain at least one selected from the group consisting of other organic expanders (hereinafter sometimes referred to as second organic expanders), carbonaceous materials, and other additives. Examples of additives include barium sulfate and fibers (resin fibers, etc.), but are not limited to these. The negative electrode active material in the charged state is spongy lead, but the unformed negative electrode plate is usually produced using lead powder.

(Organic shrink-proofing agent)
The negative electrode material contains an organic expander. The term “organic anti-shrinking agent” refers to an organic compound among compounds having a function of suppressing shrinkage of lead, which is a negative electrode active material, when the lead-acid battery is repeatedly charged and discharged. As already mentioned, the negative electrode material contains the first organic expander among the organic expanders as an essential component, and may further contain a second organic expander as necessary. The second organic anti-shrinking agent is an organic anti-shrinking agent other than the first organic anti-shrinking agent. As the organic shrink-proofing agent, for example, one synthesized by a known method may be used, or a commercially available product may be used.

Examples of each organic shrink-proofing agent include organic condensates (hereinafter simply referred to as condensates). Here, a condensate is a compound obtained by utilizing a condensation reaction, and does not include lignin compounds. Condensates are also commonly referred to as synthetic organic expanders. The condensate may contain aromatic compound units (hereinafter also referred to as aromatic compound units). An aromatic compound unit refers to a unit derived from an aromatic compound incorporated into the condensate. That is, the aromatic compound unit is the residue of an aromatic compound. The condensate may contain one or more aromatic compound units.
In addition, the above-mentioned lignin compound is also included in the organic shrink-proofing agent.

Condensates include, for example, condensates of aromatic compounds with aldehyde compounds. Such a condensate can be synthesized by reacting an aromatic compound and an aldehyde compound. Here, a condensate containing a sulfur element can be obtained by performing the reaction between the aromatic compound and the aldehyde compound in the presence of a sulfite, or by using an aromatic compound containing a sulfur element (for example, bisphenol S) as the aromatic compound. For example, the content of elemental sulfur in the condensate can be adjusted by adjusting at least one of the amount of sulfite and the amount of the aromatic compound containing elemental sulfur. This method may also be followed when using other raw materials. One or more aromatic compounds may be condensed to obtain a condensate. The aldehyde compound may be an aldehyde (for example, formaldehyde) or a condensate (or polymer) of aldehyde. Aldehyde condensates (or polymers) include paraformaldehyde, trioxane, tetraoxymethylene and the like. An aldehyde compound may be used individually by 1 type, and may be used in combination of 2 or more types. Formaldehyde is preferable from the viewpoint of high reactivity with aromatic compounds.

Aromatic compounds may have sulfur-containing groups. That is, the condensate may be an organic polymer containing a plurality of aromatic rings in the molecule and containing elemental sulfur as a sulfur-containing group. The sulfur-containing group may be directly attached to the aromatic ring of the aromatic compound, or may be attached to the aromatic ring, for example, as an alkyl chain with the sulfur-containing group. Among the sulfur-containing groups, the stable forms sulfonic acid or sulfonyl groups are preferred. The sulfonic acid group may exist in an acid form or in a salt form such as Na salt.

A benzene ring, a naphthalene ring, etc. are mentioned as an aromatic ring which an aromatic compound has. When the aromatic compound has multiple aromatic rings, the multiple aromatic rings may be directly bonded or linked by a linking group (eg, an alkylene group (including an alkylidene group), a sulfone group), or the like. Such structures include, for example, bisarene structures (biphenyl, bisphenylalkane, bisphenylsulfone, etc.).

Examples of aromatic compounds include compounds having the above aromatic ring and functional groups (hydroxy group, amino group, etc.). The functional group may be attached directly to the aromatic ring or may be attached as an alkyl chain with a functional group. The hydroxy group also includes a salt of a hydroxy group (--OMe). Amino groups also include salts of amino groups (salts with anions). Me includes alkali metals (Li, K, Na, etc.), periodic table Group 2 metals (Ca, Mg, etc.), and the like. The aromatic compound may have a substituent (for example, an alkyl group, an alkoxy group) other than the sulfur-containing group and the above functional groups on the aromatic ring.

The aromatic compound from which the aromatic compound unit is based may be at least one selected from the group consisting of bisarene compounds and monocyclic aromatic compounds.

The bisarene compounds include bisarene compounds having a hydroxyl group (bisphenol compounds, hydroxybiphenyl compounds, etc.) and bisarene compounds having an amino group (bisarylalkane compounds having an amino group, bisarylsulfone compounds having an amino group, biphenyl compounds having an amino group, etc.). Among them, a bisarene compound having a hydroxy group (especially a bisphenol compound) is preferable.

As the bisphenol compound, bisphenol A, bisphenol S, bisphenol F and the like are preferable. For example, the bisphenol compound may contain at least one selected from the group consisting of bisphenol A and bisphenol S. By using bisphenol A or bisphenol S, an excellent anti-shrinking effect on the negative electrode material can be obtained.

The bisphenol compound may have a bisphenol skeleton, and the bisphenol skeleton may have a substituent. That is, bisphenol A should have a bisphenol A skeleton, and the skeleton may have a substituent. Bisphenol S may have a bisphenol S skeleton, and the skeleton may have a substituent.

Preferred monocyclic aromatic compounds include hydroxy monoarene compounds and monocyclic aromatic compounds having an amino group (amino monoarene compounds). Among them, hydroxy monoarene compounds are preferred.

Examples of hydroxy monoarene compounds include hydroxy naphthalene compounds and phenol compounds. For example, it is preferable to use a phenolsulfonic acid compound (phenolsulfonic acid or a substituted product thereof, etc.) which is a phenol compound. As already mentioned, the phenolic hydroxy group includes salts of phenolic hydroxy group (--OMe).

The aminomonoarene compounds include aminonaphthalene compounds and aniline compounds (aminobenzenesulfonic acid, alkylaminobenzenesulfonic acid, etc.).

The elemental sulfur content of the organic shrink-proofing agent other than the lignin compound may be, for example, 2000 μmol/g or more, or may be 3000 μmol/g or more. When an organic expander having such a sulfur element content is used, the colloidal particle size of the organic expander tends to be small, and the structure of the negative electrode material can be kept fine, making it easy to ensure high low-temperature HR discharge performance.

The content of elemental sulfur in the organic anti-shrinking agent being X μmol/g means that the content of elemental sulfur contained in 1 g of the organic anti-shrinking agent is X μmol.

The upper limit of the elemental sulfur content of the organic shrink-proofing agent other than the lignin compound is not particularly limited.

The organic shrink-proofing agents other than lignin compounds include those having a sulfur content of less than 2000 μmol/g. The elemental sulfur content of such organic expanders may be 300 μmol/g or more.

The elemental sulfur content of the organic shrinkage agent other than the lignin compound is, for example, 2000 μmol/g or more (or 3000 μmol/g or more) 9000 μmol/g or less, 2000 μmol/g or more (or 3000 μmol/g or more) 8000 μmol/g or less, 2000 μmol/g or more (or 3000 μmol/g or more) 7000 μmol/g or less, 300 μmol/g or more 90 00 μmol/g or less (or 8000 μmol/g or less), or 300 μmol/g or more and 7000 μmol/g or less (or less than 2000 μmol/g).

The weight-average molecular weight (Mw) of the organic shrink-proofing agent other than the lignin compound is preferably, for example, 7000 or more. The Mw of the organic shrink-proofing agent is, for example, 100,000 or less, and may be 20,000 or less.

The elemental sulfur content of the lignin compound is for example less than 2000 μmol/g, and may be 1000 μmol/g or less or 800 μmol/g or less. Although the lower limit of the elemental sulfur content of the lignin compound is not particularly limited, it is, for example, 400 μmol/g or more.

The Mw of the lignin compound is, for example, less than 7000. The Mw of the lignin compound is, for example, 3000 or more.

In this specification, the Mw of the organic shrink-proofing agent is determined by gel permeation chromatography (GPC). Sodium polystyrene sulfonate is used as a standard substance for determining Mw.
Mw is measured under the following conditions using the following equipment.
GPC device: build-up GPC system SD-8022/DP-8020/AS-8020/CO-8020/UV-8020 (manufactured by Tosoh Corporation)
Column: TSKgel G4000SWXL, G2000SWXL (7.8 mm I.D. × 30 cm) (manufactured by Tosoh Corporation)
Detector: UV detector, λ=210 nm
Eluent: NaCl aqueous solution with a concentration of 1 mol/L: mixed solution of acetonitrile (volume ratio=7:3) Flow rate: 1 mL/min.
Concentration: 10 mg/mL
Injection volume: 10 μL
Standard material: Na polystyrene sulfonate (Mw = 275,000, 35,000, 12,500, 7,500, 5,200, 1,680)

Among the organic anti-shrinking agents, the first organic anti-shrinking agent contains an aromatic compound unit having a hydroxy group among the aromatic compound units. Examples of the aromatic compound unit having a hydroxy group include at least one selected from the group consisting of a unit of a bisarene compound (such as a bisphenol compound) having a hydroxy group and a unit of a monocyclic aromatic compound having a hydroxy group. Having such a unit facilitates the formation of a planar structure in the molecule of the first organic expander, and the planar structure portion can enhance the lead adsorption of the lugs and surface layer of the negative electrode plate.

The hydroxy group possessed by the aromatic compound is preferably a phenolic hydroxy group. A condensate of an aromatic compound having a phenolic hydroxy group with an aldehyde compound is mainly condensed at at least one of the ortho-position and the para-position (particularly the ortho-position) with respect to the phenolic hydroxy group. On the other hand, a condensate of a monocyclic aromatic compound having an amino group with an aldehyde compound is in a condensed state via the amino group. Therefore, when a monocyclic aromatic compound having a phenolic hydroxy group is used, compared with the case of using a monocyclic aromatic compound having an amino group, the aromatic rings in the organic anti-shrinking agent molecule are less twisted, and it is easier to take a planar structure, which makes it easier to act on lead. In addition, since the phenolic hydroxy group is more likely to negatively charge the first organic shrink-proofing agent than is the case of an amino group, etc., high lead adsorption is likely to be obtained.

The first organic shrink-proofing agent preferably contains at least a unit of a monocyclic aromatic compound having a hydroxy group (in particular, a phenolic hydroxy group) (hereinafter sometimes referred to as a first unit). Since the first unit is more likely to have a planar structure than the other units, the first organic shrink-proofing agent is also more likely to have a planar structure. Therefore, the first organic anti-shrinking agent containing the first unit is easily adsorbed to lead on the lugs and surface layer of the negative electrode plate.

Among the above monocyclic aromatic compound units, it is preferable to use the first organic shrink-proofing agent containing the phenolsulfonic acid compound unit as the first unit. Such first organic shrink-proofing agents have phenolic hydroxy groups and sulfonic acid groups. Both the phenolic hydroxy group and the sulfonic acid group have a strong negative polarity and a high affinity with metals. In addition to this, phenolsulfonic acid facilitates the formation of a planar structure in the condensate. Therefore, the condensate containing the phenolsulfonic acid compound unit as the first unit has a higher adsorptivity to lead contained in the tab and surface layer of the negative electrode plate.

The first organic shrink-proofing agent may be one (for example, a condensate) containing a first unit and a unit of a bisarene compound having a hydroxyl group (hereinafter sometimes referred to as a second unit). In the organic shrink-proofing agent containing the second unit, the aromatic ring generally tends to interact between π electrons to form a rigid molecule. However, in the first organic expander, the first unit inhibits the π-electron interaction of the second unit, so that the flexibility of the molecule can be increased. Organic shrink-proofing agents usually have many functional groups with negative polarity. Since the first organic shrink-proofing agent has high molecular flexibility, it is considered that the negative functional groups contained in the first organic shrink-proofing agent tend to be unevenly distributed on the molecular surface. The functional groups unevenly distributed on the surface tend to make the first organic shrink agent negatively charged, and the electrostatic repulsion restricts association or agglomeration of the colloidal particles of the first organic shrink agent. This reduces the colloidal particle size. As a result, it is considered that the pore size of the negative electrode material becomes smaller, and an excellent anti-shrinking effect can be ensured. In addition, in the first organic shrink-proofing agent, the first unit facilitates the formation of a planar structure in the molecule. Such a planar structure and the presence of negatively polarized functional groups unevenly distributed on the surface make it easier for the first organic expander eluted from the negative electrode material to be adsorbed onto the lugs and surface layer of the negative electrode plate. Therefore, a higher corrosion suppression effect can be secured. In addition, the first organic anti-shrinking agent may further contain units of other aromatic compounds, if necessary.

The second unit is preferably at least a bisphenol S compound unit. The first organic shrink-proofing agent may contain a bisphenol S compound unit and a bisphenol A compound unit as the second unit. The bisphenol S skeleton has a structure in which two benzene rings are linked by a sulfonyl group. The bisphenol A skeleton has a structure in which two benzene rings are linked by a dimethylene group. A sulfonyl group protrudes less from the plane of a benzene ring than a dimethylene group. Therefore, compared with the case of the bisphenol A compound unit, the bisphenol S compound unit makes it easier for the first organic shrink-proofing agent to have a planar structure. Also, due to the presence of the sulfonyl group, the first organic shrink-proofing agent is more likely to be negatively charged in the bisphenol S compound unit than in the bisphenol A compound unit. Therefore, when the first organic expander having at least a bisphenol S compound unit is used as the second unit, the adsorption of the first organic expander to lead contained in the lugs and surface layer of the negative electrode plate is further enhanced. Therefore, it is considered that a higher corrosion inhibition effect can be obtained.

When the first organic shrink-proofing agent contains the first unit and the second unit, the molar ratio of the first unit to the total amount of the first unit and the second unit is, for example, 10 mol % or more, and may be 20 mol % or more. When the molar ratio is within such a range, the first organic shrink-proofing agent is more likely to have a planar structure. Therefore, elution from the negative electrode material is reduced, and high low-temperature HR discharge performance is obtained. In addition, the eluted first organic anti-shrinking agent is more likely to be adsorbed on the lugs, thereby further enhancing the effect of suppressing corrosion of the lugs. The molar ratio of the first unit is, for example, 90 mol % or less, and may be 80 mol % or less. When the molar ratio is within this range, the condensate tends to be negatively charged. Therefore, elution from the negative electrode material is reduced, and high low-temperature HR discharge performance can be ensured. In addition, repulsion due to electric charges of the eluted first organic anti-shrinking agent is suppressed, and the lugs are easily adsorbed, thereby further enhancing the effect of suppressing corrosion of the lugs.

The molar ratio of the first unit may be 10 mol % or more (or 20 mol % or more) and 90 mol % or less, or 10 mol % or more (or 20 mol % or more) and 80 mol % or less.

In the first organic shrink-proofing agent, the total ratio (molar ratio) of the first unit and the second unit to the total amount of the aromatic compound units is, for example, 90 mol % or more, and may be 95 mol % or more. Also, the aromatic compound unit may be composed of only the first unit and the second unit.

As the first organic shrink-proofing agent, one having a second unit as a unit of an aromatic compound having a hydroxy group may be used. Among them, as the first organic shrink-proofing agent, one (condensate) containing at least a bisphenol S compound unit as a unit of an aromatic compound having a hydroxy group may be used. As described above, the presence of the sulfonyl group in the bisphenol S compound tends to cause the first organic shrink-proofing agent to be negatively charged. Therefore, the use of the first organic expander having at least a bisphenol S compound unit can more easily increase the adsorption of the first organic expander to lead contained in the lugs and surface layer of the negative electrode plate. In addition, a product (condensate) containing a bisphenol S compound unit and a bisphenol A compound unit may be used as the aromatic compound unit having a hydroxy group. When the first organic anti-shrinking agent having these units is used, an excellent anti-shrinking effect is likely to be obtained.

When the first organic shrink-proofing agent contains a bisphenol S compound unit and a bisphenol A compound unit, the molar ratio of the bisphenol S compound unit to the total amount of these units is, for example, 10 mol% or more, and may be 20 mol% or more. When the molar ratio is within such a range, the effect of the high negative charging property of bisphenol S is likely to be exhibited, so the elution of the first organic shrink-proofing agent from the negative electrode material is suppressed, and high low-temperature HR discharge performance is obtained. In addition, even if the first organic anti-shrinking agent is eluted, it is likely to be adsorbed on the lugs, thereby further enhancing the effect of suppressing corrosion of the lugs. The molar ratio of the units of the bisphenol S compound is, for example, 90 mol % or less, and may be 80 mol % or less. When the molar ratio of the units of the bisphenol S compound is within this range, the charge-induced repulsion of the organic expander eluted from the negative electrode material is suppressed, and the organic expander is easily adsorbed to the lugs. Therefore, the effect of suppressing corrosion of the ears can be further enhanced.

The molar ratio of the units of the bisphenol S compound may be 10 mol % or more (or 20 mol % or more) and 90 mol % or less, or 10 mol % or more (or 20 mol % or more) and 80 mol % or less.

In the first organic shrink-proofing agent having bisphenol S compound units and bisphenol A compound units, the total ratio (molar ratio) of the bisphenol S compound units and the bisphenol A compound units to the total amount of the aromatic compound units is, for example, 90 mol% or more, and may be 95 mol% or more. Alternatively, the aromatic compound unit may be composed of only the bisphenol S compound unit and the bisphenol A compound unit.

The elemental sulfur content and Mw of the first organic shrink-proofing agent can each be selected from the above ranges.

The first organic shrink-proofing agent may be used singly or in combination of two or more.

Among the above organic anti-shrinking agents, examples of the second organic anti-shrinking agent include condensates containing units of lignin compounds and aromatic compounds having amino groups.
The second organic shrink-proofing agent may be used singly or in combination of two or more.

The elemental sulfur content of the lignin compound is for example less than 2000 μmol/g, and may be 1000 μmol/g or less or 800 μmol/g or less. Although the lower limit of the elemental sulfur content of the lignin compound is not particularly limited, it is, for example, 400 μmol/g or more.

The Mw of the lignin compound is, for example, less than 7000. The Mw of the lignin compound is, for example, 3000 or more.

When the first organic shrink-proofing agent and the second organic shrink-proofing agent are used in combination, the mass ratio of these can be arbitrarily selected. Even when the second organic anti-shrinking agent is used in combination, it is possible to obtain the effect of suppressing the outflow of the carbonaceous material according to the mass ratio of the first organic anti-shrinking agent. From the viewpoint of ensuring higher corrosion suppression of the lugs of the negative electrode plate, the ratio of the first organic expander to the total amount of the organic expanders (that is, the total amount of the first organic expander and the second organic expander) is preferably 50% by mass or more, may be 80% by mass or more, or may be 90% by mass or more or 95% by mass or more.

However, when the organic shrink-proofing agent has a nitrogen atom-containing group such as an amino group, the negative chargeability of the organic shrink-proofing agent tends to be low, and the adsorptivity to the ears and surface layer of the negative electrode plate tends to be low. Therefore, it is preferable that the content of the nitrogen atom-containing group in the organic shrink-proofing agent is small. The nitrogen atom content in the organic anti-shrinking agent is preferably 1% by mass or less, and may be 0.1% by mass or less.

The content of the organic shrinkage inhibitor contained in the negative electrode material is, for example, 0.01% by mass or more, and may be 0.05% by mass or more. The content of the organic shrink-proofing agent is, for example, 1.0% by mass or less, and may be 0.5% by mass or less.

The content of the organic shrinkage inhibitor contained in the negative electrode material may be 0.01% by mass or more and 1.0% by mass or less, 0.05% by mass or more and 1.0% by mass or less, 0.01% by mass or more and 0.5% by mass or less, or 0.05% by mass or more and 0.5% by mass or less.

(barium sulfate)
The negative electrode material can include barium sulfate. The content of barium sulfate in the negative electrode material is, for example, 0.05% by mass or more, and may be 0.10% by mass or more. The content of barium sulfate in the negative electrode material is 3% by mass or less, and may be 2% by mass or less.

The content of barium sulfate in the negative electrode material may be 0.05% by mass or more and 3% by mass or less, 0.05% by mass or more and 2% by mass or less, 0.10% by mass or more and 3% by mass or less, or 0.10% by mass or more and 2% by mass or less.

(carbonaceous material)
The negative electrode material can contain a carbonaceous material. Carbon black, graphite, hard carbon, soft carbon and the like can be used as the carbonaceous material. Examples of carbon black include acetylene black, furnace black, and lamp black. Furnace Black also includes Ketjen Black (trade name). Graphite may be a carbonaceous material containing a graphite-type crystal structure, and may be either artificial graphite or natural graphite. A carbonaceous material may be used individually by 1 type, and may combine 2 or more types.

The content of the carbonaceous material in the negative electrode material is preferably, for example, 0.05% by mass or more, and may be 0.10% by mass or more. The content of the carbonaceous material is, for example, 5% by mass or less, and may be 3% by mass or less.

The content of the carbonaceous material in the negative electrode material is, for example, 0.05% by mass or more and 5% by mass or less, 0.05% by mass or more and 3% by mass or less, 0.10% by mass or more and 5% by mass or less, or 0.10% by mass or more and 3% by mass or less.

(Analysis of Components of Negative Electrode Material)
A method for analyzing the negative electrode material or its constituent components will be described below. The analysis of the constituent components of the negative electrode material shall be performed on the negative plate of a lead-acid battery in a fully charged state. Prior to the analysis of the constituent components, the chemically formed lead-acid battery is fully charged and then disassembled to obtain the negative electrode plate to be analyzed.
The obtained negative electrode plate is washed with water to remove sulfuric acid from the negative electrode plate. Washing with water is carried out by pressing a pH test paper against the surface of the washed negative electrode plate until it is confirmed that the color of the test paper does not change. However, the time for washing with water shall be within 2 hours. The washed negative electrode plate is dried at 60±5° C. for about 6 hours under reduced pressure. After drying, if the negative plate contains the sticking member, the sticking member is removed from the negative plate by peeling. Next, a sample (hereinafter referred to as sample A) is obtained by separating the negative electrode material from the negative electrode plate. Sample A is pulverized as necessary and subjected to analysis.

(1) Analysis of Organic Expander (1-1) Qualitative Analysis of Organic Expander in Negative Electrode Material The pulverized sample A is immersed in a 1 mol/L sodium hydroxide (NaOH) aqueous solution to extract the organic expander. If the extract contains more than one organic expander, then each organic expander is separated from the extract. For each isolate containing each organic expander, the insoluble components are removed by filtration and the resulting solution is desalted, concentrated and dried. Desalting is performed using a desalting column, passing the solution through an ion exchange membrane, or placing the solution in a dialysis tube and immersing it in distilled water. By drying this, a powder sample of the organic shrink-proofing agent (hereinafter referred to as sample B) is obtained.

The type of the organic shrink-proofing agent is identified by combining the information obtained from the infrared spectroscopy spectrum measured using Sample B of the organic shrink-proofing agent thus obtained, the ultraviolet-visible absorption spectrum measured by a UV-visible spectrophotometer after diluting Sample B with distilled water, or the NMR spectrum of a solution obtained by dissolving Sample B in a predetermined solvent such as heavy water.

When the above extract contains a plurality of organic expanders, their separation is carried out as follows.

First, the extract is measured by at least one of infrared spectroscopy, NMR, and GC-MS to determine whether it contains multiple organic preservatives. Next, the molecular weight distribution of the extract is measured by GPC analysis, and if a plurality of organic expanders can be separated by molecular weight, the organic expanders are separated by column chromatography based on the difference in molecular weight.

Organic shrink-proofing agents have different solubilities when at least one of the type of functional group and the amount of functional group are different. When it is difficult to separate the organic expanders due to the difference in molecular weight, one of the organic expanders is separated by a sedimentation separation method utilizing such a difference in solubility. For example, when two kinds of organic expanders are contained, an aqueous sulfuric acid solution is added dropwise to a mixture of the extract dissolved in an aqueous NaOH solution to adjust the pH of the mixture, thereby flocculating and separating one of the organic expanders. When separation by aggregation is difficult, the difference in at least one of the type and amount of functional groups is used to separate the organic expander by ion exchange chromatography or affinity chromatography. The separated material is dissolved again in an aqueous NaOH solution, and the insoluble components are removed by filtration as described above. Also, the remaining solution after separating one of the organic expanders is concentrated. The resulting concentrate, containing the other organic expander, is filtered to remove insoluble components as described above.

(1-2) Quantification of Content of Organic Expanding Agent in Negative Electrode Material In the same manner as in (1-1) above, a solution is obtained after removing insoluble components by filtration for each of the separated substances containing the organic expanding agent. An ultraviolet-visible absorption spectrum is measured for each solution obtained. The content of each organic expander in the negative electrode material is determined using the intensity of the peak characteristic of each organic expander and a calibration curve prepared in advance.

When obtaining a lead-acid battery with an unknown content of the organic expander and measuring the content of the organic expander, the same organic expander cannot be used for the calibration curve because the structural formula of the organic expander cannot be specified strictly. In this case, the content of the organic preservative is measured using the ultraviolet-visible absorption spectrum by preparing a calibration curve using a separately available organic polymer exhibiting a shape similar to that of the organic preservative extracted from the negative electrode of the battery, such as the ultraviolet-visible absorption spectrum, infrared spectroscopic spectrum, and NMR spectrum.

(1-3) Content of elemental sulfur in organic expander After obtaining sample B of the organic expander in the same manner as in (1-1) above, 0.1 g of elemental sulfur in the organic expander is converted to sulfuric acid by the oxygen combustion flask method. At this time, by burning the sample B in a flask containing the adsorbent, an eluate in which sulfate ions are dissolved in the adsorbent is obtained. Next, the eluate is titrated with barium perchlorate using thorin as an indicator to determine the sulfur element content (C0) in 0.1 g of the organic shrink-proofing agent. Next, C0 is multiplied by 10 to calculate the content of elemental sulfur (μmol/g) in the organic anti-shrinking agent per gram.

(1-4) Calculation of molar ratio of constituent units of organic expander First, sample B of the organic expander (organic expander to be measured) separated in the same manner as in (1-1) above is dissolved in a heavy aqueous solution of sodium hydroxide (pH 10 to 13) to prepare a measurement sample, and ¹ H-NMR is measured using this measurement sample. A unit contained in the organic expander is identified from the peak of the ¹ H-NMR spectrum. In this ¹ H-NMR spectrum, a peak intensity ratio (first ratio) of peaks derived from each unit is obtained.

Next, an organic expander containing the same units as the identified structure and having a known mole fraction of each unit (reference organic expander) is synthesized. Measure the ¹ H-NMR spectrum of the reference organic expander. In this ¹ H-NMR spectrum, a peak intensity ratio (second ratio) of peaks derived from each unit is obtained.

A lead-acid battery is prepared using the reference organic shrinkage agent and brought to a fully charged state. A sample A is collected in the same manner as described above from a negative electrode plate taken out from a fully charged lead-acid battery. Using this sample A, a sample B is obtained in the same manner as in (1-1) above. The obtained sample B is dissolved in a heavy aqueous solution of sodium hydroxide (pH 10 to 13) to prepare a measurement sample, and ¹ H-NMR is measured using this measurement sample. In this ¹ H-NMR spectrum, a peak intensity ratio (third ratio) of peaks derived from each unit is obtained.

The third ratio may deviate from the second ratio indicating the actual mole fractions. Therefore, for correction, the relationship between the second ratio, the third ratio, and the known mole fraction is obtained. This relationship shows the relationship between the actual mole fraction of each unit and the peak intensity ratio of the peak of each unit of the organic expander when removed from the lead-acid battery. By applying the first ratio to this relationship, the mole fraction of each unit in the organic expander to be measured can be obtained from the first ratio. Then, the ratio (mol%) of the mole fraction of each unit to the total mole fraction of each unit is calculated, and the mole ratio of each unit is calculated.

For example, when the first organic shrink-proofing agent is a condensate of phenolsulfonic acid and bisphenol S with formaldehyde, ^{the 1} H-NMR spectrum shows a peak (P _bs ) derived from the bisphenol S unit in the range of 6.5 ppm or more and 6.6 ppm or less, and a peak (P _ps ) derived from the phenol sulfonic acid unit in the range of 6.6 ppm or more and 7.0 ppm or less. From ¹ H-NMR of the first organic expander with known mole fractions of bisphenol S units and phenolsulfonic acid units, the ratio of peak intensity I _bs of peak P _bs to peak intensity I _bs of peak P _ps (second ratio and third ratio) is determined. A relationship between the second and third ratios and the known mole fractions is then determined. By applying the ratio (first ratio) between the peak intensity I _bs of the peak P _bs and the peak intensity I _ps of the peak P _ps in ¹ H-NMR _of the first organic expander whose molar fraction is unknown to this relationship, the molar fraction m _bs of the bisphenol S unit and the molar fraction m bs of the phenolsulfonic acid unit of the first organic expander are obtained. Then, the ratio (mol _% ) of the mole fraction _mps of the phenolsulfonic acid unit to the sum of the mole fraction mbs and the mole fraction _mps is calculated and defined as the molar ratio of the phenolsulfonic acid unit.

(1-5) Analysis of Elemental Nitrogen Content in Organic Expanding Agent The pulverized sample A is immersed in a 1 mol/L sodium hydroxide (NaOH) aqueous solution to extract the organic expanding agent. After desalting the resulting solution, it is concentrated and dried. As a result, a powder sample of the organic shrink-proofing agent (hereinafter referred to as sample C) is obtained. By analyzing sample C using an organic elemental analyzer (CHN analyzer), the nitrogen atom content in the organic shrinkage agent is determined. Desalting is performed by using a desalting column, by passing the solution through an ion exchange membrane, or by placing the solution in a dialysis tube and immersing it in distilled water.

(2) Quantification of Carbonaceous Material and Barium Sulfate To 10 g of pulverized sample A, 50 ml of nitric acid having a concentration of 20 mass % is added and heated for about 20 minutes to dissolve the lead component as lead nitrate. Next, the solution containing lead nitrate is filtered to remove solids such as carbonaceous materials and barium sulfate.

After dispersing the obtained solid content in water to form a dispersion, a sieve is used to remove components other than the carbonaceous material and barium sulfate (for example, reinforcing material) from the dispersion. Next, the dispersion is subjected to suction filtration using a membrane filter whose mass has been measured in advance, and the membrane filter is dried in a drier at 110° C.±5° C. together with the filtered sample. The obtained sample is a mixed sample of carbonaceous material and barium sulfate (hereinafter referred to as sample D). The mass of the sample D (M _m ) is measured by subtracting the mass of the membrane filter from the total mass of the dried sample D and the membrane filter. Thereafter, the sample D after drying is placed in a crucible together with the membrane filter and is ignited and incinerated at 700° C. or higher. The remaining residue is barium oxide. The mass of barium oxide is converted to the mass of barium sulfate to obtain the mass of barium sulfate (M _B ). The mass of the carbonaceous material is calculated by subtracting the mass M _B from the mass M _m .

(others)
The negative plate can be formed by coating or filling a negative electrode current collector with a negative electrode paste, aging and drying to prepare an unformed negative plate, and then forming the unformed negative plate. The negative electrode paste is prepared by adding water and sulfuric acid to lead powder, an organic anti-shrinking agent, and optionally various additives, and kneading the mixture. When aging, it is preferable to age the unformed negative electrode plate at a temperature and humidity higher than room temperature.

Formation can be performed by charging the electrode plate group including the unformed negative electrode plate while the electrode plate group is immersed in an electrolytic solution containing sulfuric acid in the battery case of the lead-acid battery. However, formation may be performed before assembly of the lead-acid battery or the electrode plate assembly. Formation produces spongy lead.

(Positive plate)
A positive plate of a lead-acid battery typically includes a positive current collector and a positive electrode material. A positive electrode material is held by a positive current collector. Positive plates of lead-acid batteries can be classified into paste type, clad type, and the like. Either paste type or clad type positive electrode plate may be used.

The positive electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead sheet or a lead alloy sheet. Processing methods include, for example, expanding processing and punching processing. It is preferable to use a grid-like current collector as the positive electrode current collector because it facilitates carrying the positive electrode material.

Pb--Sb alloys, Pb--Ca alloys, and Pb--Ca--Sn alloys are preferable as the lead alloy used for the positive electrode current collector in terms of corrosion resistance and mechanical strength. The positive electrode current collector may have a surface layer. The composition of the surface layer and the inner layer of the positive electrode current collector may be different. The surface layer may be formed on part of the positive electrode current collector. The surface layer may be formed only on the lattice portion of the positive electrode current collector, only on the ear portion, or only on the frame portion.

In the pasted positive plate, the positive electrode material is the positive plate excluding the positive current collector. A member such as a mat or pasting paper may be attached to the positive electrode plate. Since such a member (attaching member) is used integrally with the positive electrode plate, it shall be included in the positive electrode plate. Further, when the positive electrode plate includes a sticking member (mat, pasting paper, etc.), the positive electrode material in the pasted positive plate is the positive electrode plate excluding the positive electrode current collector and the sticking member.

The positive electrode material contained in the positive electrode plate includes a positive electrode active material (lead dioxide or lead sulfate) that develops capacity through an oxidation-reduction reaction. The positive electrode material may contain other additives as needed.

An unformed paste-type positive electrode plate is obtained by filling a positive electrode current collector with a positive electrode paste, aging it, and drying it. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid.

A positive electrode plate is obtained by chemically forming an unformed positive electrode plate. Formation can be performed by charging the electrode plate group including the unformed positive electrode plate while immersing the electrode plate group in an electrolytic solution containing sulfuric acid in the battery case of the lead-acid battery. However, formation may be performed before assembly of the lead-acid battery or the electrode plate assembly.

(separator)
A separator can be placed between the negative plate and the positive plate. As the separator, for example, at least one selected from nonwoven fabrics and microporous membranes is used. The thickness of the separator interposed between the negative electrode plate and the positive electrode plate may be selected according to the distance between the electrodes. The number of separators may be selected according to the number of electrodes.

A non-woven fabric is a mat in which fibers are intertwined without being woven, and is mainly composed of fibers. The nonwoven fabric is made up of, for example, 60% by mass or more of fibers. As the fiber, glass fiber, polymer fiber (polyolefin fiber, acrylic fiber, polyester fiber (polyethylene terephthalate fiber, etc.), etc.), pulp fiber, or the like can be used. Among them, glass fiber is preferable. Nonwoven fabrics may contain components other than fibers, such as acid-resistant inorganic powders and polymers as binders.

On the other hand, a microporous membrane is a porous sheet mainly composed of non-fiber components, and is obtained, for example, by extruding a composition containing a pore-forming agent (at least one of polymer powder and oil) into a sheet, and then removing the pore-forming agent to form pores. The microporous membrane is preferably composed of an acid-resistant material, preferably mainly composed of a polymer component. Polyolefins (polyethylene, polypropylene, etc.) are preferred as the polymer component.

The separator may be composed of, for example, only a nonwoven fabric, or may be composed only of a microporous film. The separator may also be a laminate of a nonwoven fabric and a microporous membrane, a laminate of different or the same type of materials, or a combination of different or the same type of materials with interlocking unevenness.

The separator may be sheet-like or may be formed in a bag-like shape. You may arrange|position so that one sheet-like separator may be pinched|interposed between the positive electrode plate and the negative electrode plate. Further, the electrode plates may be arranged so as to be sandwiched between the sheet-shaped separators in a folded state. In this case, the positive electrode plate sandwiched between the folded sheet separators and the negative electrode plate sandwiched between the folded sheet separators may be stacked, or one of the positive electrode plate and the negative electrode plate may be sandwiched between the folded sheet separators and stacked on the other electrode plate. Alternatively, a sheet-shaped separator may be folded into a bellows shape, and the positive electrode plate and the negative electrode plate may be sandwiched between the bellows-shaped separators so that the separator is interposed therebetween. When using a separator bent in a bellows shape, the separator may be arranged so that the bent portion is parallel to the horizontal direction of the lead-acid battery (for example, the bent portion is parallel to the horizontal direction), or the separator may be arranged to be perpendicular to the lead-acid battery (for example, the bent portion is parallel to the vertical direction). In a separator bent in a bellows shape, concave portions are alternately formed on both major surface sides of the separator. Since ears are usually formed on the top of each of the positive electrode plate and the negative electrode plate, when the separator is arranged so that the bent portion is along the horizontal direction of the lead-acid battery, the positive electrode plate and the negative electrode plate are arranged only in the concave portion on one main surface side of the separator (that is, a double separator is interposed between the adjacent positive electrode plate and negative electrode plate). When the separator is arranged so that the bent portion is along the vertical direction of the lead-acid battery, the positive electrode plate can be accommodated in the recess on one main surface side, and the negative electrode plate can be accommodated in the recess on the other main surface side (that is, the separator can be interposed in a single layer between the adjacent positive electrode plate and negative electrode plate). When a bag-shaped separator is used, the bag-shaped separator may contain the positive electrode plate or may contain the negative electrode plate.

In this specification, the vertical direction of the electrode plate is defined with the side on which the ears are provided as the upper side and the side opposite to the ears as the lower side. The vertical direction of the electrode plate may be the same as or different from the vertical direction of the lead-acid battery. That is, the lead-acid battery may be placed vertically or horizontally.

(Electrolyte)
The electrolytic solution is an aqueous solution containing sulfuric acid, and may be gelled if necessary. The electrolyte may optionally contain at least one selected from the group consisting of cations (e.g., metal cations) and anions (e.g., anions other than sulfate anions (phosphate ions, etc.)). Examples of metal cations include at least one selected from the group consisting of sodium ions, lithium ions, magnesium ions, and aluminum ions.

The specific gravity of the electrolyte at 20° C. in a fully charged lead-acid battery is, for example, 1.20 or more, and may be 1.25 or more. The specific gravity of the electrolytic solution at 20° C. is 1.35 or less, preferably 1.32 or less.

The specific gravity of the electrolyte at 20° C. in the fully charged lead-acid battery may be 1.20 or more and 1.35 or less, 1.20 or more and 1.32 or less, 1.25 or more and 1.35 or less, or 1.25 or more and 1.32 or less.

A lead-acid battery can be obtained by a manufacturing method including a step of assembling a lead-acid battery by housing a positive electrode plate, a negative electrode plate, and an electrolytic solution in a container. In the process of assembling a lead-acid battery, the separator is usually arranged so as to be interposed between the positive electrode plate and the negative electrode plate. The step of assembling the lead-acid battery may include, if necessary, the step of forming at least one of the positive plate and the negative plate after the step of housing the positive plate, the negative plate, and the electrolyte in the battery case. A positive electrode plate, a negative electrode plate, an electrolyte, and a separator are each prepared before they are housed in a battery case.

FIG. 1 shows the appearance of an example of a lead-acid battery according to one embodiment of the present invention.
A lead-acid battery 1 includes a battery case 12 that accommodates an electrode plate group 11 and an electrolytic solution (not shown). The interior of the container 12 is partitioned into a plurality of cell chambers 14 by partition walls 13 . Each cell chamber 14 accommodates one electrode plate group 11 . The opening of the container 12 is closed with a lid 15 having a negative terminal 16 and a positive terminal 17 . The lid 15 is provided with a liquid port plug 18 for each cell chamber. When rehydrating, the rehydration liquid is replenished by removing the liquid port plug 18. - 特許庁The liquid port plug 18 may have a function of discharging the gas generated inside the cell chamber 14 to the outside of the battery.

The electrode plate group 11 is configured by stacking a plurality of negative electrode plates 2 and positive electrode plates 3 with separators 4 interposed therebetween. Here, a bag-shaped separator 4 for housing the negative electrode plate 2 is shown, but the shape of the separator is not particularly limited. In a cell chamber 14 located at one end of the battery case 12, a negative electrode shelf portion 6 connecting a plurality of negative electrode plates 2 in parallel is connected to a through connector 8, and a positive electrode shelf portion 5 connecting a plurality of positive electrode plates 3 in parallel is connected to a positive electrode column 7. The positive pole 7 is connected to a positive terminal 17 outside the lid 15 . In the cell chamber 14 located at the other end of the battery case 12 , the negative electrode column 9 is connected to the negative electrode shelf 6 , and the through connector 8 is connected to the positive electrode shelf 5 . The negative electrode column 9 is connected to a negative electrode terminal 16 outside the lid 15 . Each through-connector 8 passes through a through-hole provided in the partition wall 13 and connects the electrode plate groups 11 of adjacent cell chambers 14 in series.

The positive electrode shelf 5 is formed by welding tabs provided on the upper portions of the positive electrode plates 3 to each other by a cast-on-strap method or a burning method. The negative electrode shelf portion 6 is also formed by welding ear portions provided on the upper portions of the negative electrode plates 2 in the same manner as the positive electrode shelf portion 5 .

Although the lid 15 of the lead-acid battery has a single structure (single lid), it is not limited to the illustrated example. The lid 15 may have a double structure including, for example, an inner lid and an outer lid (or upper lid). The lid having a double structure may have a reflux structure between the inner lid and the outer lid for returning the electrolytic solution to the inside of the battery (inside the inner lid) from a reflux port provided in the inner lid.

A negative electrode plate for a lead-acid battery and a lead-acid battery according to one aspect of the present invention are collectively described below.

(1) A negative electrode current collector having ears, and a negative electrode material supported on the negative electrode current collector,
The ears have a surface layer containing a lead alloy containing Sn,
The negative electrode material comprises an organic expander containing units of an aromatic compound,
A negative electrode plate for a lead-acid battery, wherein the organic anti-shrinking agent comprises a first organic anti-shrinking agent (excluding the lignin compound) containing an aromatic compound unit having a hydroxy group.

(2) In (1) above, the content of nitrogen atoms in the first organic anti-shrinking agent may be 1% by mass or less, or 0.1% by mass or less.

(3) In (1) or (2) above, the hydroxy group-containing aromatic compound unit may be at least one selected from the group consisting of a hydroxy group-containing bisarene compound unit and a hydroxy group-containing monocyclic aromatic compound unit.

(4) In (3) above, the first organic shrink-proofing agent may include at least the unit of the monocyclic aromatic compound having the hydroxy group.

(5) In (3) or (4) above, the first organic expander may include a unit of the bisarene compound having the hydroxy group (second unit) and a unit of the monocyclic aromatic compound having the hydroxy group (first unit).

(6) In (5) above, the unit (second unit) of the bisarene compound having a hydroxyl group may be at least a unit of a bisphenol S compound.

(7) In the above (5) or (6), the total ratio of the units of the hydroxy group-containing bisarene compound (second unit) and the units of the monocyclic aromatic compound having a hydroxy group (first unit) to the total amount of the units of the aromatic compound in the first organic expander may be 90 mol% or more, or 95 mol% or more.

(8) In any one of (5) to (7) above, the molar ratio of the first unit to the total amount of the first unit and the second unit may be 10 mol% or more, or 20 mol% or more.

(9) In any one of (5) to (8) above, the molar ratio of the first unit to the total amount of the first unit and the second unit may be 90 mol% or less, or 80 mol% or less.

(10) In any one of (1) to (3) above, the first organic shrink-proofing agent may contain a bisphenol S compound unit and a bisphenol A compound unit as the aromatic compound unit having a hydroxy group.

(11) In (10) above, the total ratio of the bisphenol S compound units and the bisphenol A compound units to the total amount of the aromatic compound units in the first organic anti-shrinking agent may be 90 mol% or more, or 95 mol% or more.

(12) In (10) or (11) above, the molar ratio of the bisphenol S compound unit to the total amount of the bisphenol S compound unit and the bisphenol A compound unit may be 10 mol% or more, or 20 mol% or more.

(13) In any one of (10) to (12) above, the molar ratio of the bisphenol S compound unit to the total amount of the bisphenol S compound unit and the bisphenol A compound unit may be 90 mol% or less, or 80 mol% or less.

(14) In any one of (1) to (13) above, the sulfur element content of the first organic expander may be 300 μmol/g or more, 2000 μmol/g or more, or 3000 μmol/g or more.

(15) In any one of (1) to (14) above, the elemental sulfur content of the first organic expander may be 9000 μmol/g or less, 8000 μmol/g or less, or 7000 μmol/g or less.

(16) In any one of (1) to (13) above, the elemental sulfur content of the first organic shrink-proofing agent may be less than 2000 μmol/g.

(17) In (16) above, the content of elemental sulfur in the first organic shrink-proofing agent may be 300 μmol/g or more.

(18) In any one of (1) to (17) above, the weight average molecular weight (Mw) of the first organic shrink-proofing agent is, for example, 7000 or more.

(19) In any one of (1) to (18) above, the weight average molecular weight (Mw) of the first organic shrink-proofing agent may be 100,000 or less, or 20,000 or less.

(20) In any one of (1) to (19) above, the organic anti-shrinking agent further contains a second organic anti-shrinking agent other than the first organic anti-shrinking agent,
The ratio of the first organic anti-shrinking agent to the total amount of the first organic anti-shrinking agent and the second organic anti-shrinking agent may be 50% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more.

(21) In any one of (1) to (20) above, the content of the organic preservative contained in the negative electrode material may be 0.01% by mass or more, or 0.05% by mass or more.

(22) In any one of (1) to (21) above, the content of the organic preservative contained in the negative electrode material may be 1.0% by mass or less, or 0.5% by mass or less.

(23) In any one of (1) to (22) above, the negative electrode material may further contain barium sulfate.

(24) In (23) above, the content of barium sulfate in the negative electrode material may be 0.05% by mass or more, or 0.10% by mass or more.

(25) In (24) above, the content of barium sulfate in the negative electrode material may be 3% by mass or less, or 2% by mass or less.

(26) In any one of (1) to (25) above, the negative electrode material may further include a carbonaceous material.

(27) In (26) above, the content of the carbonaceous material in the negative electrode material may be 0.05% by mass or more, or 0.10% by mass or more.

(28) In (26) or (27) above, the content of the carbonaceous material in the negative electrode material may be 5% by mass or less, or 3% by mass or less.

(29) In any one of (1) to (28) above, the Sn content in the surface layer may be 2% by mass or more, 2.5% by mass or more, 5% by mass or more, or 7.5% by mass or more, or may be more than 7.5% by mass, or may be 10% by mass or more, or 15% by mass or more.

(30) In any one of (1) to (29) above, the Sn content in the surface layer may be less than 50% by mass, 30% by mass or less, 25% by mass or less, or 20% by mass or less.

(31) In any one of (1) to (30) above, the Sn content in the surface layer may be 10% by mass or more and 30% by mass or less.

(32) In any one of (1) to (31) above, the thickness of the surface layer may be 0.01 mm or more, 0.015 mm or more, or 0.02 mm or more.

(33) In any one of (1) to (32) above, the thickness of the surface layer may be 0.1 mm or less, or 0.05 mm or less.

(34) In any one of (1) to (31) above, the surface layer may have a thickness of 0.015 mm or more and 0.05 mm or less.

(35) A lead-acid battery includes a positive electrode plate, the negative electrode plate according to any one of (1) to (34) above, and an electrolytic solution.

(36) In (35) above, the specific gravity of the electrolyte at 20° C. in the fully charged lead-acid battery may be 1.20 or more, or 1.25 or more.

(37) In (35) or (36) above, the specific gravity at 20° C. of the electrolyte in the lead-acid battery in a fully charged state may be 1.35 or less, or 1.32 or less.

[Example]
EXAMPLES The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to the following examples.

<<Lead-acid batteries E1 to E3 and R1 to R5>>
(1) Production of lead-acid battery (a) Production of negative electrode plate A Pb--Sn alloy sheet is layered on a Pb--Ca--Sn alloy sheet, rolled in this state, and then expanded. As a result, a surface layer of a lead alloy containing Sn is provided on the ears of the expanded lattice made of the Pb--Ca--Sn alloy. The Sn content in the surface layer determined by the procedure described above is 10% by mass. The thickness of the surface layer measured by the procedure described above is 0.015 mm. A grid having a surface layer formed in this manner on the ears is used as a negative electrode current collector.
In the lead-acid batteries R2 to R5, an expanded grid made of a Pb--Ca--Sn alloy with no surface layer on the ears is used.

A negative electrode paste is obtained by mixing lead powder, water, dilute sulfuric acid, carbon black, an organic shrinkage agent, and barium sulfate. At this time, each component is mixed so that the content of the organic shrinkage agent, the content of carbon black, and the content of barium sulfate in the negative electrode material, which are all obtained by the procedure described above, are 0.10% by mass, 0.30% by mass, and 0.60% by mass, respectively. The negative electrode paste is filled in the mesh portion of the negative electrode current collector, aged and dried to obtain an unformed negative electrode plate.

Condensates shown in Table 2 are used as organic shrink-proofing agents. The condensates shown in Table 2 are as follows. The molar ratio of the monomers in each organic anti-shrinking agent corresponds to the molar ratio of the units obtained by the procedure described above. The nitrogen atom content determined by the procedure described above for the organic anti-shrinking agents a1 to a3 is 1% by mass or less (more specifically, 0.1% by mass or less).
a1 (first organic shrink-proofing agent): formaldehyde condensate of bisphenol S and phenolsulfonic acid (= 2:8 (molar ratio)) (elemental sulfur content: 5000 µmol/g, Mw: 8000)
a2 (first organic shrink-proofing agent): formaldehyde condensate of bisphenol A and phenolsulfonic acid (= 2:8 (molar ratio)) (elemental sulfur content: 4000 µmol/g, Mw: 8000)
a3 (first organic shrink-proofing agent): a condensate obtained by condensing bisphenol S and bisphenol A (=2:8 (molar ratio)) with formaldehyde in the presence of sodium sulfite (sulfur element content: 4000 μmol/g, Mw: 9000)
b1 (second organic shrink-proofing agent): sodium ligninsulfonate (sulfur element content: 600 μmol/g, Mw: 5500)

(b) Preparation of positive electrode plate A raw material lead powder is mixed with an aqueous sulfuric acid solution to obtain a positive electrode paste. The positive electrode paste is filled in the mesh part of the expanded lattice made of Pb--Ca--Sn alloy, and aged and dried to obtain an unformed positive electrode plate.

(c) Production of lead-acid battery An unchemically formed negative electrode plate is housed in a bag-shaped separator made of a polyethylene microporous film, and an electrode plate group is formed by five unchemically formed negative electrode plates and four unchemically formed positive electrode plates.
The electrode plate group is inserted into the battery case, the electrolyte is injected, and chemical conversion is performed in the battery case to produce liquid lead-acid batteries E1 to E3 and R1 to R5 with a rated voltage of 12 V and a rated capacity of 30 Ah (5 hour rate). As the electrolytic solution, an aqueous sulfuric acid solution having a specific gravity of 1.28 (20° C.) after chemical conversion is used. Note that the lead-acid battery is fully charged by the chemical conversion.

(2) Evaluation (a) Reduction in Ear Thickness The negative electrode plate is taken out from the lead-acid battery prepared above, washed with water and dried, and the thickness of the ear (initial thickness: t ₀ ) is measured.
The lead-acid battery produced above is charged and discharged according to the pattern shown in Table 1 (PSOC charge/discharge pattern). The negative electrode plate is taken out from the lead-acid battery after charging and discharging, washed with water and dried, and the thickness _t1 of the ear portion is measured. Then, the amount of decrease in the thickness of the ear portion (=t ₀ -t ₁ (mm)) due to charge/discharge cycles is obtained.
The thickness of the ear portion is determined by measuring the thickness of the ear portion at any five points with a vernier caliper and averaging the measured values.
Table 2 shows the results.

As shown in Table 2, when the surface layer was not provided on the lugs, even when the first organic shrink-proofing agent was used, the thickness of the lugs of the negative electrode plates decreased significantly (lead-acid batteries R1 to R4). On the other hand, in the case of using a negative electrode plate having a surface layer containing a lead alloy containing Sn on the lugs, the use of the first organic anti-shrinking agent can reduce the decrease in the thickness of the lugs. More specifically, compared to the lead-acid battery R1 using sodium ligninsulfonate as an organic expander, in the lead-acid batteries E1 to E3 using the first organic expander, the amount of decrease in the thickness of the tab of the negative electrode plate after repeated charging and discharging in the PSOC cycle is reduced. When the surface layer is not provided, the effect of reducing the thickness reduction of the selvage by using the first organic shrink-proofing agent instead of sodium lignosulfonate is 0.05 to 0.12 mm (comparison between R2 to R4 and R5). On the other hand, when a surface layer is provided, the effect of reducing the amount of decrease in the thickness of the ear portion by using the first organic shrink-proofing agent instead of sodium lignosulfonate is 0.08 to 0.2 mm (comparison between E1 to E3 and R1). In other words, in the lead-acid batteries E1 to E3, a higher effect than expected is obtained from the effect of providing the surface layer and the effect of using the first organic shrink-proofing agent. In other words, it can be said that the combination of the surface layer and the first organic shrink-proofing agent synergistically reduces the reduction in the thickness of the lugs. It is believed that this is because the first organic shrink-proofing agent is more likely to be adsorbed to the lugs than sodium lignosulfonate. More specifically, it is believed that the high adsorption property of the first organic anti-shrinking agent to the lugs reduces the lead redox reaction area of the lugs and suppresses the corrosion of the surface layer, thereby maintaining the high anti-corrosion effect of the lugs by the surface layer.

Further, among the first organic anti-shrinking agents, when at least the first organic anti-shrinking agent containing at least a unit of a monocyclic aromatic compound having a hydroxy group is used, the decrease in the thickness of the ear can be reduced (lead-acid batteries E1 and E2).

<<Lead-acid batteries E1-1 to E3-7, and R1-1 to R1-7>>
The Sn content in the Pb—Sn alloy sheet to be used is adjusted so that the Sn content in the surface layer of the ear portion of the negative electrode current collector obtained by the above-described procedure is the value shown in Table 3. As the organic anti-shrinking agent, those shown in Table 3 are used. Except for these, a lead-acid battery is produced and evaluated in the same manner as the lead-acid battery E1.

Table 3 shows the results. Table 3 also shows the results of lead-acid batteries E1 to E3 and R1 to R5. Also, FIG. 2 shows the relationship between the Sn content in Table 3 and the thickness reduction amount of the ear portion.

As shown in Table 3 and FIG. 2, even when the Sn content in the surface layer is changed, the use of the first organic shrink-proofing agent can reduce the reduction in the thickness of the lugs. In particular, when the Sn content in the surface layer is 10% by mass or more, the decrease in the thickness of the lugs is significantly reduced. From FIG. 2, it can be seen that there is a critical point between the Sn content of 7.5 mass % and 10 mass %, and a particularly high effect is obtained at 10 mass % or more. Therefore, from the viewpoint of securing a higher effect of suppressing thickness reduction in the ear portions, the Sn content in the surface layer is preferably 10% by mass or more.

《Lead-acid batteries E4-1 to E10-3》
(1) Preparation of lead-acid battery As an organic anti-shrinking agent, a formaldehyde condensate of bisphenol S containing a phenolsulfonic acid unit and phenolsulfonic acid having a content shown in Table 4 is used. In the lead-acid batteries E4-1 to E4-3, a formaldehyde condensate of bisphenol S is used as an organic anti-shrinking agent. In the lead-acid batteries E10-1 to E10-3, a formaldehyde condensate of phenolsulfonic acid is used as an organic shrinkage agent. Also, the Sn content in the Pb—Sn alloy sheet used is adjusted so that the Sn content in the surface layer of the lug portion of the negative electrode current collector obtained by the above-described procedure is the value shown in Table 4. Except for these, a lead-acid battery was produced in the same manner as the lead-acid battery E1, and the following evaluations were performed.

(2) Evaluation (b) Low-temperature HR discharge performance The produced lead-acid battery (fully charged lead-acid battery) is discharged at a discharge current of 150 A at -15 ° C. ± 0.3 ° C. until the terminal voltage reaches 1 V / cell, and the discharge time (discharge duration) (s) at this time is determined. The ratio (%) when the discharge duration of the lead-acid battery E4-1 is assumed to be 100% is used as an index of the low-temperature HR discharge performance.

Similar evaluations are made for lead-acid batteries E1, E1-5, and E1-7. Table 4 shows the results. FIG. 3 shows the relationship between the content of the phenolsulfonic acid unit in Table 4 and the low-temperature HR discharge performance.

《Lead-acid batteries E11-1 to E16-3》
A formaldehyde condensate of bisphenol A containing a phenolsulfonic acid unit and phenolsulfonic acid having the content shown in Table 5 is used as an organic shrink-proofing agent. In the lead-acid batteries E18-1 to E18-3, a formaldehyde condensate of bisphenol A is used as an organic anti-shrinking agent. In addition, the Sn content in the Pb—Sn alloy sheet used is adjusted so that the Sn content in the surface layer of the lug portion of the negative electrode current collector obtained by the above-described procedure is the value shown in Table 5. Except for these, a lead-acid battery is produced in the same manner as the lead-acid battery E2, and the low-temperature HR discharge performance of (b) above is evaluated.

Similar evaluations are made for lead-acid batteries E2, E2-5, and E2-7. Table 5 shows the results. Table 5 also shows the results of lead-acid batteries E10-1 to E10-3. FIG. 4 shows the relationship between the content of the phenolsulfonic acid unit in Table 5 and the low-temperature HR discharge performance.

As shown in FIGS. 3 and 4, from the viewpoint of ensuring higher low-temperature HR discharge performance, the ratio of the first unit to the total amount of the first unit (such as the phenolsulfonic acid unit) and the second unit is preferably 10 mol% or more, more preferably 20 mol% or more. From the same point of view, the ratio of the first unit is preferably 90 mol % or less, more preferably 80 mol % or less.

《Lead-acid batteries E17-1 to E21-3》
A formaldehyde condensate of bisphenol S and bisphenol A having a content shown in Table 6 and containing a bisphenol S unit is used as an organic shrink-proofing agent. In addition, the Sn content in the Pb—Sn alloy sheet used is adjusted so that the Sn content in the surface layer of the lug portion of the negative electrode current collector obtained by the above-described procedure is the value shown in Table 6. Except for these, a lead-acid battery is produced in the same manner as the lead-acid battery E3, and the low-temperature HR discharge performance of the above (b) is evaluated.

Similar evaluations are made for lead-acid batteries E3, E3-5, and E3-7. Table 6 shows the results. Table 6 also shows the results of lead-acid batteries E4-1 to E4-3 and E11-1 to E11-3. FIG. 5 shows the relationship between the bisphenol S unit content in Table 6 and the low-temperature HR discharge performance.

As shown in FIG. 5, from the viewpoint of ensuring higher low-temperature HR discharge performance, the ratio of the bisphenol S compound unit to the total amount of the bisphenol S compound unit (bisphenol S unit, etc.) and the bisphenol A compound unit (bisphenol A unit, etc.) is preferably 10 mol% or more, more preferably 20 mol% or more. From the same point of view, the ratio of the bisphenol S compound unit is preferably 90 mol % or less, more preferably 80 mol % or less.

A lead-acid battery according to one aspect and another aspect of the present invention is useful as an IS lead-acid battery that is charged and discharged under PSOC conditions. IS lead-acid batteries are suitable for idling stop vehicles. In addition, lead-acid batteries can also be suitably used, for example, as power sources for starting vehicles (automobiles, motorcycles, etc.) and power sources for industrial power storage devices (electric vehicles (forklifts, etc.), etc.). In addition, these uses are mere examples, and are not limited to these uses.

1: Lead storage battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5: Positive electrode shelf 6: Negative electrode shelf 7: Positive electrode column 8: Through connector 9: Negative column 11: Electrode plate group 12: Battery container 13: Partition wall 14: Cell chamber 15: Lid 16: Negative electrode terminal 17: Positive electrode terminal 18: Liquid spout plug

Claims (10)

A negative electrode current collector having ears, and a negative electrode material supported on the negative electrode current collector,
The ears have a surface layer containing a lead alloy containing Sn,
The negative electrode material comprises an organic expander containing units of an aromatic compound,
The organic shrink-proofing agent comprises a first organic shrink-proofing agent (excluding the lignin compound) containing an aromatic compound unit having a hydroxy group,
A negative electrode plate for a lead-acid battery , wherein the nitrogen atom content in the organic shrink-proofing agent is 1% by mass or less . The negative electrode plate for a lead-acid battery according to claim 1 , wherein the aromatic compound unit having a hydroxy group is at least one selected from the group consisting of a bisarene compound unit having a hydroxy group and a monocyclic aromatic compound unit having a hydroxy group. 3. The negative electrode plate for a lead-acid battery according to claim 2 , wherein the organic anti-shrinking agent contains at least the unit of the monocyclic aromatic compound having the hydroxy group. A negative electrode current collector having ears, and a negative electrode material supported on the negative electrode current collector,
The ears have a surface layer containing a lead alloy containing Sn,
The negative electrode material comprises an organic expander containing units of an aromatic compound,
The organic shrink-proofing agent comprises a first organic shrink-proofing agent (excluding the lignin compound) containing an aromatic compound unit having a hydroxy group,
A negative electrode plate for a lead-acid battery, wherein the unit of the aromatic compound having a hydroxy group includes at least the unit of the monocyclic aromatic compound having a hydroxy group. The negative electrode plate for a lead-acid battery according to any one of claims 2 to 4, wherein the organic anti-shrinking agent includes a unit of the bisarene compound having the hydroxyl group and a unit of the monocyclic aromatic compound having the hydroxyl group. 6. The negative electrode plate for a lead-acid battery according to claim 5, wherein the bisarene compound unit having a hydroxyl group is at least a bisphenol S compound unit. 3. The negative electrode plate for a lead-acid battery according to claim 1, wherein said first organic anti-shrinking agent includes a bisphenol S compound unit and a bisphenol A compound unit as said aromatic compound unit having a hydroxy group. 8. The negative electrode plate for a lead-acid battery according to claim 1, wherein the Sn content in said surface layer is 10% by mass or more and 30% by mass or less. 9. The negative electrode plate for a lead-acid battery according to claim 1, wherein said surface layer has a thickness of 0.015 mm or more and 0.05 mm or less. A lead-acid battery comprising a positive plate, a negative plate according to any one of claims 1 to 9, and an electrolytic solution.

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