JP6950365B2 - Negative electrode material paste, negative electrode and lead acid battery, and their manufacturing method - Google Patents

Description

The present invention relates to a negative electrode material paste, a negative electrode and a lead storage battery, and a method for producing them.

Lead-acid batteries are widely used in industry, for example, in automobile batteries, backup power supplies, and main power supplies for electric vehicles. In recent years, for the purpose of carbon dioxide emission regulation measures, fuel efficiency, etc., an idling stop system vehicle (hereinafter referred to as "ISS vehicle") equipped with a system that stops the engine when controlling power generation, waiting for a signal, etc. has been studied. It has been. In the ISS vehicle, the amount of power generated by the alternator is small, and the lead-acid battery is charged intermittently, so that charging tends to be insufficient.

To solve such a problem, it has been studied to add a resin having a structural unit derived from a phenolic compound (also called a shrink-proofing agent) and a carbon material to the negative electrode of a lead-acid battery. For example, Patent Document 1 describes synthetic lignin sulfonic acid having a molecular weight of 17,000 to 20,000 or a salt thereof (bisphenol sulfonic acid polymer condensate) and a specific surface area of 150 to 150 as additives in the negative electrode active material. A lead-acid battery characterized by a combination of carbon black made from heavy oil having an apparent density of 0.2 to 0.35 g / cm ³ at 300 m ^{2 / g improves the charge acceptability of the lead-acid battery.} Is disclosed.

Japanese Unexamined Patent Publication No. 2006-196191

However, there is still room for improvement in the charge acceptance performance of lead-acid batteries. Further, the lead storage battery is required to have excellent discharge performance in addition to charge acceptability.

Therefore, an object of the present invention is to provide a lead storage battery having excellent charge acceptance performance and discharge performance and a method for manufacturing the same, and a negative electrode material paste, a negative electrode and a method for manufacturing the same, which are used for the lead storage battery.

The present invention is a method for producing a negative electrode material paste, comprising a step of mixing lead powder, a carbon material, a resin having a structural unit derived from a phenolic compound, and water in one embodiment. And at least one of the resins is a production method that is subjected to the process as a mixture premixed with water.

In the above production method, the carbon material may be subjected to the step as a mixture previously mixed with water, or the resin may be subjected to the step as a mixture previously mixed with water, and the carbon material and the resin may be subjected to the step. Both may be subjected to the process as a mixture, each premixed with water.

In another aspect, the present invention is a method for manufacturing a negative electrode, comprising a step of holding the negative electrode material paste obtained by the above method for producing a negative electrode material paste on a current collector.

The present invention is, in another aspect, a method for manufacturing a lead-acid battery, which obtains a lead-acid battery using the negative electrode obtained by the above-mentioned method for manufacturing a negative electrode.

The present invention is, in another aspect, a negative electrode material paste or a negative electrode obtained by the above-mentioned negative electrode material paste or the method for producing a negative electrode, and a lead storage battery including the negative electrode.

According to the present invention, it is possible to provide a lead storage battery excellent in both charge acceptance performance and discharge performance and a method for manufacturing the same, and a negative electrode material paste, a negative electrode and a method for manufacturing the same, which are used for the lead storage battery.

It is a perspective view which shows the whole structure and the internal structure of the lead storage battery which concerns on one Embodiment. It is a perspective view which shows the electrode group of the lead storage battery which concerns on one Embodiment.

Hereinafter, embodiments of the present invention will be described in detail.

FIG. 1 is a perspective view showing the overall configuration and internal structure of the lead storage battery according to the embodiment. As shown in FIG. 1, the lead-acid battery 1 is a liquid lead-acid battery including an electric tank 2 having an open upper surface and a lid 3 for closing the opening of the electric tank 2. The battery case 2 and the lid 3 are made of polypropylene, for example. The lid 3 is provided with a negative electrode terminal 4, a positive electrode terminal 5, and a liquid port plug 6 for closing the liquid injection port provided in the lid 3.

Inside the battery case 2, an electrode group 7, a negative electrode column 8 connecting the electrode group 7 to the negative electrode terminal 4, a positive electrode column (not shown) connecting the electrode group 7 to the positive electrode terminal 5, dilute sulfuric acid, etc. Electrolyte and is stored.

FIG. 2 is a perspective view showing the electrode group 7. As shown in FIG. 2, the electrode group 7 includes a plate-shaped negative electrode (negative electrode plate) 9, a plate-shaped positive electrode (positive electrode plate) 10, and a separator 11 arranged between the negative electrode 9 and the positive electrode 10. It has. The negative electrode 9 has a current collector (negative electrode current collector) and a negative electrode material held by the current collector. The positive electrode 10 has a current collector (positive electrode current collector) and a positive electrode material held by the current collector.

The electrode group 7 has a structure in which a plurality of positive electrodes 10 and 9 are alternately laminated in a direction substantially parallel to the opening surface of the battery case 2 via a separator 11. That is, the positive electrode 10 and the negative electrode 9 are arranged so that their main surfaces extend in the direction perpendicular to the opening surface of the battery case 2. In the electrode group 7, the ears 9a of the plurality of negative electrodes 9 are collectively welded by the negative electrode side strap 12. Similarly, the ears 10a of the plurality of positive electrodes 10 are collectively welded by the positive electrode side strap 13. Each of the negative electrode side strap 12 and the positive electrode side strap 13 is connected to the negative electrode terminal 4 and the positive electrode terminal 5 via the negative electrode column 8 and the positive electrode column.

The manufacturing method of the lead-acid battery 1 described above will be described below. The method for manufacturing a lead-acid battery 1 according to an embodiment includes an electrode manufacturing step for obtaining electrodes (negative electrode 9 and positive electrode 10) and an assembly step for assembling constituent members including the electrodes to obtain the lead-acid battery 1.

In the electrode manufacturing process, for example, for each of the negative electrode 9 and the positive electrode 10, the electrode material paste (negative electrode material paste and positive electrode material paste) is held (filled) in the current collector, and then aged and dried. Obtain a chemical electrode.

The current collector may be a cast lattice body obtained by a casting method, an expanded lattice body obtained by an expand method, or the like. The current collector may be formed of, for example, a lead-calcium-tin alloy, a lead-antimony alloy, or the like, and a small amount of selenium, silver, bismuth, or the like may be added to these alloys. The current collectors of the negative electrode 9 and the positive electrode 10 may be the same as each other or may be different from each other.

The positive electrode material paste can be obtained, for example, by adding an additive (reinforcing short fibers or the like) and water to the raw material of the positive electrode active material, then adding dilute sulfuric acid, and then kneading. The raw material of the positive electrode active material may be lead powder, lead tan (Pb ₃ O ₄ ) or the like.

After the positive electrode material paste is held (filled) in the current collector, it is aged for 15 to 60 hours in an atmosphere of, for example, a temperature of 35 to 85 ° C. and a humidity of 50 to 98 RH%, and aged at a temperature of 45 to 80 ° C. for 15 to 30. By drying for a time, an unchemical positive electrode is obtained.

The negative electrode material paste is, for example, a mixture of lead powder, which is a raw material for a negative electrode active material, a carbon material, a resin having a structural unit derived from a phenol-based compound (hereinafter, also referred to as “phenol-based resin”), and water. Obtained by

The lead powder is, for example, lead powder produced by a ball mill type lead powder manufacturing machine or a barton pot type lead powder manufacturing machine (in the ball mill type lead powder manufacturing machine, a mixture of powder of the main component PbO and scaly metal lead). ) May be. The carbon material may be, for example, carbon black, graphite or the like. The carbon black may be, for example, furnace black, channel black, acetylene black, thermal black or the like.

The phenol-based resin may have a structural unit derived from the phenol-based compound. The phenolic resin preferably further has a sulfonic acid group (sulfo group) or a sulfonic acid base. In this case, the sulfonic acid group or the sulfonic acid base may be contained in the structural unit derived from the phenolic compound, or may be contained in the structural unit different from the structural unit derived from the phenolic compound. good.

In one embodiment, the phenolic resin has a structural unit derived from a phenolic compound and a structural unit having a sulfonic acid group or a sulfonic acid base. Such a phenol-based resin is, for example, a bisphenol-based resin containing a sulfonic acid group or a sulfonic acid base (hereinafter, also referred to as “bisphenol-based resin”), lignin sulfonic acid or a salt thereof (hereinafter, also referred to as “lignin sulfonic acid (salt)”). It may be) or the like.

The bisphenol resin has a structural unit derived from the bisphenol compound as a structural unit derived from the phenol compound. The bisphenol resin is, for example, (a) a bisphenol compound (hereinafter, also referred to as “(a) component”) and (b) a compound having a sulfonic acid group (sulfo group) (hereinafter, also referred to as “(b) component”). And, if necessary, it can be obtained by substituting the hydrogen atom of the sulfonic acid group with, for example, a metal atom. In the reaction of the component (a) and the component (b), at least one selected from the group consisting of (c) formaldehyde and a formaldehyde derivative (hereinafter, also referred to as “component (c)”) may be further reacted.

Examples of the component (a) include 2,2-bis (4-hydroxyphenyl) propane (hereinafter, also referred to as “bisphenol A”), bis (4-hydroxyphenyl) methane, and 1,1-bis (4-hydroxyphenyl). ) Etan, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 2,2-bis (4-hydroxyphenyl) butane, bis ( 4-Hydroxyphenyl) diphenylmethane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, and bis (4-hydroxyphenyl) Examples include sulfone (hereinafter, also referred to as "bisphenol S"). As the component (a), one type can be used alone or two or more types can be used in combination. The component (a) is preferably bisphenol A from the viewpoint of further excellent charge acceptability, and preferably bisphenol S from the viewpoint of further excellent discharge characteristics.

As the component (a), it is preferable to use bisphenol A and bisphenol S in combination from the viewpoint of improving charge acceptability, discharge characteristics and cycle characteristics in a well-balanced manner. In this case, the content of bisphenol A in the reaction for obtaining the bisphenol resin is preferably based on the total amount of bisphenol A and bisphenol S from the viewpoint of improving charge acceptability, discharge characteristics and cycle characteristics in a well-balanced manner. It is 70 mol% or more, more preferably 75 mol% or more, still more preferably 80 mol% or more. The content of bisphenol A is preferably 99 mol% or less, more preferably 98 mol% or less, based on the total amount of bisphenol A and bisphenol S, from the viewpoint of improving charge acceptability, discharge characteristics and cycle characteristics in a well-balanced manner. , More preferably 97 mol% or less.

The component (b) may be a compound having an amino group and a sulfonic acid group. Examples of the compound having an amino group and a sulfonic acid group include 4-aminobenzenesulfonic acid (also known as sulfanic acid), aminoethylsulfonic acid (also known as taurine), and 5-amino-1-naphthalenesulfonic acid (also known as laurent acid). ).

As the component (b), one type can be used alone or two or more types can be used in combination. The component (b) is preferably 4-aminobenzenesulfonic acid from the viewpoint of further improving charge acceptability.

The content of the component (b) in the reaction for obtaining the bisphenol resin is preferably 0.5 mol or more, more preferably 0. Mol, with respect to 1 mol of the component (a) from the viewpoint of further improving the discharge characteristics. It is 6 mol or more, more preferably 0.7 mol or more, and particularly preferably 0.8 mol or more. The content of the component (b) is preferably 2.0 mol or less, more preferably 1.5 mol or less, and further, with respect to 1 mol of the component (a), from the viewpoint that the discharge characteristics and the cycle characteristics can be further improved. It is preferably 1.3 mol or less, and particularly preferably 1.0 mol or less.

As the formaldehyde as the component (c), formaldehyde in formalin (for example, an aqueous solution of 37% by mass of formaldehyde) may be used. Examples of formaldehyde derivatives include paraformaldehyde, hexamethylenetetramine and trioxane. As the component (c), one type can be used alone or two or more types can be used in combination. Formaldehyde and formaldehyde derivative may be used in combination as the component (c).

The component (c) is preferably a formaldehyde derivative, more preferably paraformaldehyde, from the viewpoint that excellent cycle characteristics can be easily obtained. Paraformaldehyde has, for example, a structure represented by the following formula (1).
HO (CH ₂ O) _n1 H ... (1)
In the formula (1), n1 represents an integer of 2 to 100.

The formaldehyde-equivalent amount of the component (c) in the reaction for obtaining the bisphenol resin is preferably 2 mol or more with respect to 1 mol of the component (a) from the viewpoint of improving the reactivity of the component (b). It is more preferably 2.2 mol or more, still more preferably 2.4 mol or more. The formaldehyde-equivalent amount of the component (c) is obtained by the reaction of the component (a), the component (b) and the component (c), and the structural unit having a benzoxazine ring can be easily reduced. With respect to 1 mol, it is preferably 3.5 mol or less, more preferably 3.2 mol or less, still more preferably 3 mol or less, particularly preferably less than 2.8 mol, and extremely preferably 2.5 mol or less.

The bisphenol resin preferably has at least one of a structural unit represented by the following formula (I) and a structural unit represented by the following formula (II).

式（Ｉ）中、Ｘ^１は２価の基を示し、Ｙ^１は、２価の芳香族炭化水素基、脂肪族炭化水素基又は脂環式炭化水素基を示し、Ｒ^１１、Ｒ^１２及びＲ^１３は、それぞれ独立に、金属原子又は水素原子を示し、ｎ１１は、１〜３００の整数を示し、ｎ１２は、１〜３の整数を示す。ベンゼン環を構成する炭素原子に直接結合している水素原子は、炭素数１〜５のアルキル基で置換されていてもよい。

In formula (I), X ¹ represents a divalent group, Y ¹ represents a divalent aromatic hydrocarbon group, an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, and R ¹¹ , R ¹² and R ¹³ independently represents a metal atom or a hydrogen atom, n11 represents an integer of 1 to 300, and n12 represents an integer of 1 to 3. The hydrogen atom directly bonded to the carbon atom constituting the benzene ring may be substituted with an alkyl group having 1 to 5 carbon atoms.

式（ＩＩ）中、Ｘ^２は２価の基を示し、Ｙ^２は、２価の芳香族炭化水素基、脂肪族炭化水素基又は脂環式炭化水素基を示し、Ｒ^２１、Ｒ^２２及びＲ^２３は、それぞれ独立に、金属原子又は水素原子を示し、ｎ２１は、１〜３００の整数を示し、ｎ２２は、１〜３の整数を示す。ベンゼン環を構成する炭素原子に直接結合している水素原子は、炭素数１〜５のアルキル基で置換されていてもよい。

In formula (II), X ² represents a divalent group, Y ² represents a divalent aromatic hydrocarbon group, an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, and R ²¹ , R ²² and R ²³ independently represents a metal atom or a hydrogen atom, n21 represents an integer of 1 to 300, and n 22 represents an integer of 1 to 3. The hydrogen atom directly bonded to the carbon atom constituting the benzene ring may be substituted with an alkyl group having 1 to 5 carbon atoms.

The ratio of the structural unit represented by the formula (I) and the structural unit represented by the formula (II) is not particularly limited and may change depending on the synthesis conditions and the like. As the bisphenol resin, a resin having only one of the structural unit represented by the formula (I) and the structural unit represented by the formula (II) may be used.

Examples of X ¹ and X ² include an alkylidene group (for example, a methylidene group, an ethylidene group, an isopropylidene group and a sec-butylidene group), a cycloalkylidene group (for example, a cyclohexylidene group), and a phenylalkylidene group (for example, a diphenylmethylidene group and a phenyl group). Organic groups such as ethylidene group; sulfonyl group and the like can be mentioned. The X ¹ and ^{X 2,} further excellent isopropylidene group from the viewpoint to the charge acceptance _{(-C (CH 3) 2 -} ) group are preferred, and excellent from the viewpoint sulfonyl group discharge characteristics _(-SO 2 -) Is preferable. X ¹ and X ² may be substituted with a halogen atom such as a fluorine atom. When X ¹ or X ² is a cycloalkylidene group, the hydrocarbon ring may be substituted with an alkyl group or the like.

The ^{divalent aromatic hydrocarbon group represented by Y 1} or Y ² includes, for example, a phenylene group and a naphthylene group, and the divalent aliphatic hydrocarbon group includes, for example, an ethylene group and a trimethylene group, and a divalent alicyclic group. Examples of the type hydrocarbon group include a cyclohexylidene group. Y ¹ and Y ² are preferably a phenylene group or a naphthylene group from the viewpoint of further excellent charge acceptability. The divalent aromatic hydrocarbon group, aliphatic hydrocarbon group or alicyclic hydrocarbon group represented by ^{Y 1} and Y ^{2 may be substituted with halogen atoms such as fluorine atoms, respectively.}

The ^{metal atom represented by R 11} , R ¹² , R ¹³ , R ²¹ , R ²² or R ²³ is, for example, a sodium atom, a potassium atom, a magnesium atom or a calcium atom.

The bisphenol resin may have, for example, structural units represented by the following formulas (III) to (VI). It is presumed that the reason why the structural units represented by the formulas (III) to (VI) are generated is that the formaldehyde component undergoes an addition reaction to the benzene ring of the component (a).

X ³ , X ⁴ , X ⁵ and X ⁶ are synonymous with ^{X 1} and X ² , respectively ^{, R 31} , R ³² , R ³³ , R ⁴¹ , R ⁴² , R ⁴³ , R ⁵¹ , R ⁵² , R ^61. And R ⁶² are independently ^{synonymous with R 21} , R ²² and R ²³ , respectively, n31, n41, n51 and n61 are independently synonymous with n11 and n21, respectively, and n32 and n42 are independently synonymous with n12, respectively. And n22 are synonymous with. The hydrogen atom directly bonded to the carbon atom constituting the benzene ring may be substituted with an alkyl group having 1 to 5 carbon atoms.

The weight average molecular weight of the bisphenol resin is preferably 20,000 or more, more preferably 30,000 or more, still more preferably 40,000 or more, and particularly preferably 50,000 or more, from the viewpoint of further improving the cycle characteristics. The weight average molecular weight of the bisphenol resin is preferably 80,000 or less, more preferably 70,000 or less, still more preferably 60,000 or less, from the viewpoint of further improving the cycle characteristics. From these viewpoints, the weight average molecular weight of the bisphenol resin is preferably 20000 to 80,000, more preferably 30,000 to 70,000, still more preferably 40,000 to 60,000, and particularly preferably 50,000 to 60,000.

The weight average molecular weight of the bisphenol resin can be measured, for example, by gel permeation chromatography (hereinafter referred to as "GPC") under the following conditions.
(GPC condition)
Equipment: High Performance Liquid Chromatograph LC-2200 Plus (manufactured by JASCO Corporation)
Pump: PU-2080
Differential refractometer: RI-2031
Detector: Ultraviolet-visible absorptiometer UV-2075 (λ: 254 nm)
Column oven: CO-2065
Columns: TSKgel SuperAW (4000), TSKgel SuperAW (3000), TSKgel SuperAW (2500) (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Eluent: Methanol solution containing LiBr (10 mM) and triethylamine (200 mM) Flow velocity: 0.6 mL / min Molecular weight Standard sample: Polyethylene glycol (Molecular weight: 1.10 x 10 ⁶ , 5.80 x 10 ⁵ , 2.55 × 10 ⁵ , 1.46 × 10 ⁵ , 1.01 × 10 ⁵ , 4.49 × 10 ⁴ , 2.70 × 10 ⁴ , 2.10 × 10 ⁴ ; manufactured by Toso Co., Ltd., diethylene glycol (molecular weight: 1) .06 × 10 ^2; manufactured by Kishida chemical Co., Ltd.), dibutylhydroxytoluene (molecular weight: 2.20 × 10 ^2; manufactured by Kishida chemical Co., Ltd.)

The method for producing a bisphenol-based resin includes, for example, a resin manufacturing process for obtaining a bisphenol-based resin by reacting the component (a), the component (b), and the component (c). The bisphenol resin can be obtained, for example, by reacting the component (a), the component (b) and the component (c) in a reaction solvent. The reaction solvent is preferably water (for example, ion-exchanged water). In this step, an organic solvent, a catalyst, an additive or the like may be used to accelerate the reaction.

In the resin manufacturing process, from the viewpoint of further improving the cycle characteristics, the blending amount of the component (b) is 0.5 to 2.0 mol with respect to 1 mol of the component (a), and the blending of the component (c) is performed. It is preferable that the amount is 2 to 3.5 mol in terms of formaldehyde with respect to 1 mol of the component (a), and the blending amount of the component (b) is 0.5 to 2.0 with respect to 1 mol of the component (a). It is more preferable that the amount is mol and the amount of the component (c) blended is 2 to 2.5 mol in terms of formaldehyde with respect to 1 mol of the component (a). The preferable blending amount of the component (b) and the component (c) is in the above-mentioned range for each of the blending amounts of the component (b) and the component (c).

The bisphenol resin is preferably obtained by reacting the component (a), the component (b) and the component (c) under basic conditions (alkaline conditions) from the viewpoint that a sufficient amount of the bisphenol resin can be easily obtained. .. In order to adjust to basic conditions, a basic compound may be used. Examples of the basic compound include potassium hydroxide and potassium carbonate. The basic compound may be used alone or in combination of two or more. The basic compound is preferably potassium hydroxide from the viewpoint of excellent reactivity.

If the reaction solution at the time of the reaction is neutral (pH = 7), the reaction for producing the bisphenol resin may be difficult to proceed, and if the reaction solution is acidic (pH <7), a side reaction (for example, benzo) may occur. A reaction to form a structural unit having an oxazine ring) may proceed. Therefore, the pH of the reaction solution at the time of the reaction is preferably alkaline (more than 7), more preferably 7. It is 1 or more, more preferably 7.2 or more. The pH of the reaction solution is preferably 12 or less, more preferably 10 or less, still more preferably 9 or less, from the viewpoint of suppressing the progress of hydrolysis of the group derived from the component (b) in the bisphenol resin. The pH of the reaction solution can be measured, for example, with a twin pH meter AS-212 manufactured by HORIBA, Ltd. pH is defined as pH at 25 ° C.

Since it is easy to adjust the pH as described above, the blending amount of the strong basic compound is preferably 1.01 mol or more, more preferably 1.02 mol or more, still more preferably 1.02 mol or more, based on 1 mol of the component (b). Is 1.03 mol or more. From the same viewpoint, the blending amount of the strong basic compound is preferably 1.1 mol or less, more preferably 1.08 mol or less, still more preferably 1.07 mol or less, based on 1 mol of the component (b). be. Examples of the strong basic compound include potassium hydroxide and potassium carbonate.

In the synthesis reaction of the bisphenol resin, it is sufficient that the component (a), the component (b) and the component (c) react to obtain the bisphenol resin. For example, the component (a), the component (b) and the component (c) are required. The components may be reacted at the same time, or two components of the component (a), the component (b) and the component (c) may be reacted, and then the remaining one component may be reacted.

The synthetic reaction of the bisphenol resin is preferably carried out in two steps as follows. In the first step reaction, for example, the component (b), the solvent (water, etc.) and the basic compound are charged and then stirred, and the hydrogen atom of the sulfo group in the component (b) is replaced with a metal atom such as a potassium atom. (B) Obtain a metal salt such as the potassium salt of the component. This makes it easier to suppress side reactions in the condensation reaction described below. The temperature of the reaction system is preferably 0 ° C. or higher, more preferably 25 ° C. or higher, from the viewpoint of excellent solubility of the component (b) in a solvent (water or the like). The temperature of the reaction system is preferably 80 ° C. or lower, more preferably 70 ° C. or lower, still more preferably 65 ° C. or lower, from the viewpoint of easily suppressing side reactions. The reaction time is, for example, 30 minutes.

In the reaction of the second step, for example, a bisphenol resin is obtained by adding the component (a) and the component (c) to the reaction product obtained in the first step and subjecting them to a condensation reaction. The temperature of the reaction system is preferably 75 ° C. or higher, more preferably 85, from the viewpoint of excellent reactivity of the components (a), (b) and (c), and from the viewpoint of reducing side reaction products. ° C. or higher, more preferably 92 ° C. or higher. The temperature of the reaction system is preferably 100 ° C. or lower, more preferably 98 ° C. or lower, still more preferably 96 ° C. or lower, from the viewpoint of easily suppressing side reactions. The reaction time is, for example, 5 to 20 hours.

式（２）中、Ｒ^７は、金属原子又は水素原子を示す。該金属原子は、例えば、ナトリウム原子、カリウム原子、マグネシウム原子又はカルシウム原子である。 The lignin sulfonic acid (salt) is lignin sulfonic acid or a salt thereof in which a part of the lignin decomposition product is sulfonated. The lignin sulfonic acid (salt) has a structural unit derived from lignin as a structural unit derived from a phenolic compound, and also has a sulfonic acid group or a sulfonic acid base. The lignin sulfonic acid (salt) has, for example, a structure in which a sulfonic acid group or a sulfonic acid base is bonded to a carbon atom at the α-position adjacent to a phenylene group. The lignin sulfonic acid (salt) has, for example, a structure represented by the following formula (2).

In formula (2), R ⁷ represents a metal atom or a hydrogen atom. The metal atom is, for example, a sodium atom, a potassium atom, a magnesium atom or a calcium atom.

Ligno sulfonic acid (salt) can be obtained, for example, by neutralizing the black liquor remaining after evaporating wood chips to remove cellulose with sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, or the like. Can be done.

The weight average molecular weight of the lignin sulfonic acid (salt) is preferably 3000 or more from the viewpoint of suppressing elution of the lignin sulfonic acid (salt) from the electrode into the electrolytic solution in the lead storage battery and obtaining more excellent cycle characteristics. It is more preferably 7,000 or more, still more preferably 8,000 or more. The weight average molecular weight of lignin sulfonic acid (salt) is preferably 70,000 or less, more preferably 50,000 or less, still more preferably 40,000 or less, particularly preferably 30,000 or less, and extremely preferably 20,000, from the viewpoint of excellent dispersibility of the electrode active material. It is as follows. From these viewpoints, the weight average molecular weight of lignin sulfonic acid (salt) is preferably 3000 to 70000, more preferably 3000 to 50000, still more preferably 3000 to 40,000, particularly preferably 700 to 30000, and extremely preferably 800 to 20000. Is. The weight average molecular weight of lignin sulfonic acid (salt) can be measured by the same method as the weight average molecular weight of bisphenol resin.

The negative electrode material paste may further contain other additives such as barium sulfate and short reinforcing fibers (acrylic fiber, polyethylene fiber, polypropylene fiber, polyethylene terephthalate fiber, etc.), and may contain dilute sulfuric acid. good.

After the negative electrode material paste is held (filled) in the current collector, it is aged for 15 to 30 hours in an atmosphere of, for example, a temperature of 45 to 65 ° C. and a humidity of 70 to 98 RH%, and aged at a temperature of 45 to 60 ° C. for 15 to 30. By drying for a time, a non-chemical negative electrode is obtained. That is, the method for manufacturing a negative electrode according to one embodiment includes a step of holding (filling) the negative electrode material paste in the current collector, and a step of obtaining an unchemicald negative electrode by aging and drying following the step. And have.

In the assembly process, for example, the unchemical negative electrode and the unchemical positive electrode are alternately laminated via the separator 11, and the selvage 9a of the negative electrode 9 and the selvage 10a of the positive electrode 10 are connected by straps (welding, etc.). ) To obtain the electrode group 7. The electrode group 7 is arranged in the battery case 2 to produce a non-chemical battery. Next, after injecting an electrolytic solution (dilute sulfuric acid or the like) into a non-chemical battery, a direct current is applied to form an electric tank. The lead storage battery 1 can be obtained by adjusting the specific gravity of the electrolytic solution after chemical conversion to an appropriate specific density.

The chemical conversion conditions and the specific gravity of sulfuric acid can be adjusted according to the properties of the electrode active material. Instead of being carried out after the assembly step, the chemical conversion treatment may be carried out by immersing a large number of electrodes after aging and drying in the electrode manufacturing step together in a chemical conversion tank (tank chemical conversion).

Hereinafter, the method for producing the negative electrode material paste will be described in more detail. The method for producing a negative electrode material paste according to one embodiment includes a step (mixing step) of mixing lead powder, a carbon material, a phenolic resin, and water. The blending amount of the carbon material may be appropriately selected according to the type of carbon material (for example, specific surface area), and may be, for example, 0.1 to 8.0 parts by mass with respect to 100 parts by mass of lead powder. The blending amount of the phenolic resin is, for example, preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, and further preferably 0 in terms of resin solid content with respect to 100 parts by mass of lead powder. .05 to 1 parts by mass, particularly preferably 0.05 to 0.5 parts by mass, extremely preferably 0.07 to 0.5 parts by mass, very preferably 0.1 to 0.5 parts by mass, even more preferably. Is 0.1 to 0.3 parts by mass. The water may be, for example, ion-exchanged water (hereinafter, the same applies to water used in other steps).

The negative electrode material paste is produced by premixing the carbon material with water to obtain a first mixture (first premixing step) and / or premixing the phenolic resin with water before the mixing step. It includes a step of mixing to obtain a second mixture (second premixing step). That is, in this method for producing a negative electrode material paste, at least one of the carbon material and the phenol-based resin is subjected to the mixing step as a mixture previously mixed with water.

The method for producing the negative electrode material paste may include only the first premixing step of the first and second premixing steps before the mixing step, and includes only the second premixing step. It may include both a first premixing step and a second premixing step. That is, in the method for producing a negative electrode material paste, the material (raw material) to be subjected to the mixing step as a mixture previously mixed with water may be only a carbon material, may be only a phenolic resin, or may be carbon. It may be both a material and a phenolic resin. When the method for producing the negative electrode material paste includes both the first premixing step and the second premixing step, the order of performing the first premixing step and the second premixing step is interchanged with each other. It is possible.

In the first premixing step, the carbon material is immersed (immersed) in water to obtain a first mixture containing the carbon material and water. As the carbon material, a hydrophilic carbon material is preferably used from the viewpoint of excellent affinity with water. In this step, after mixing the same volume of water as the carbon material and kneading (solid kneading) to loosen the aggregated state, for example, a dispersion liquid having a concentration of 5 to 15% by mass (preferably about 10% by mass). It is preferable to dilute to. By kneading with a small amount of water, the higher the viscosity, the higher the shearing force, so it becomes easier to unaggregate the powder.

The flooding time varies depending on the hydrophilicity of the carbon, but may be, for example, 30 minutes to 3 hours. When the carbon material is flooded, the mixture may be agitated or the mixture may be pressurized for the purpose of shortening the flooding time. In particular, when the carbon material is a hydrophobic carbon material, the flooding time can be suitably shortened by pressurizing the mixture. By this step, the inside of the pores of the carbon material is uniformly filled with water. In this step, after the carbon material is flooded, it may be further diluted with water to obtain the first mixture.

In the second premixing step, the phenolic resin is dissolved in water to obtain a second mixture (aqueous solution) containing the phenolic resin and water. In this step, from the viewpoint of suppressing the aggregation of the phenol-based resin, it is preferable to dissolve the phenol-based resin little by little in the stirring water. The blending amount of the phenol-based resin is preferably 30 parts by mass or less with respect to 100 parts by mass of water from the viewpoint of suppressing a decrease in dispersibility due to an increase in the viscosity of the aqueous solution. The blending amount of the phenol-based resin may be, for example, 10 parts by mass or more with respect to 100 parts by mass of water. In this step, the longer the stirring time for dissolution is, the better, and it is preferable to stir for 24 hours or more, and more preferably for about one week, provided that the phenol-based resin does not deteriorate.

In the mixing step, in one embodiment (first embodiment), a lead powder (not previously mixed with water), a first mixture containing a carbon material and water, and a phenolic resin (preliminarily mixed with water) are used. Not) and mix. Specifically, for example, first, lead powder, a phenolic resin, and other additives (barium sulfate, reinforcing short fibers, etc.) added as needed are kneaded, and then the obtained mixture is obtained. On the other hand, the first mixture containing the carbon material and water is further kneaded.

In the mixing step, in another embodiment (second embodiment), lead powder (not previously mixed with water), a carbon material (not previously mixed with water), a phenolic resin, and water are contained. Mix with the second mixture. Specifically, for example, first, a second mixture containing lead powder, a phenolic resin and water, and other additives (barium sulfate, reinforcing short fibers, etc.) added as needed are added. Knead, then the carbon material is further kneaded with respect to the resulting mixture.

In the mixing step, in another embodiment (third embodiment), the lead powder (not previously mixed with water), the first mixture containing the carbon material and water, and the phenolic resin and water are contained. Mix with the second mixture. Specifically, for example, first, a second mixture containing lead powder, a phenolic resin and water, and other additives (barium sulfate, short reinforcing fibers, etc.) added as needed are added. The mixture is kneaded, and then the first mixture containing the carbon material and water is further kneaded with respect to the obtained mixture.

This method for producing the negative electrode material paste includes at least one of the first premixing step and the second premixing step before the mixing step, so that the premixing step is not provided and the water is previously prepared. It enables the production of lead-acid batteries which are superior in both charge acceptance performance and discharge performance as compared with the production method in which a carbon material and a phenolic resin which are not mixed with lead powder are mixed with lead powder. Although such effects can be obtained in any of the above-mentioned first to third embodiments, from the viewpoint of obtaining a lead storage battery having a higher level of superior charge acceptance performance and discharge performance, the third embodiment Is preferable. From the viewpoint of obtaining a lead-acid battery having excellent cycle performance in addition to charge acceptance performance and discharge performance, the first embodiment and the third embodiment are preferable, and the first embodiment is more preferable. That is, in the case of the first embodiment and the third embodiment (particularly the first embodiment), in addition to the charge acceptance performance and the discharge performance, the ISS is required to have durability in PSOC (Partial State Of Charge). It can be suitably used for a lead storage battery for a car.

Although the present inventor has not been able to specify the structure, physical properties, etc. of the negative electrode material paste obtained by carrying out the first premixing step, the action and effect of the first premixing step are inferred as follows. There is. In the first premixing step, the pores of the carbon material are filled with water in advance by flooding the carbon material. Therefore, when the carbon material is mixed with the phenolic resin in the mixing step, the phenolic resin is formed. It is possible to suppress the invasion into the pores of the carbon material. As a result, the phenol-based resin stays on the surface of the carbon material even when it is adsorbed on the carbon material, and can more preferably exhibit its original function as compared with the case where it penetrates into the pores of the carbon material.

In addition, if the phenolic resin invades the pores of the carbon material, it not only cannot perform its original function, but also elutes into the electrolytic solution after the lead-acid battery is completed, accelerating the muddy positive electrode or the corrosion of the polar columns. Therefore, these points can be improved by the first premixing step. In addition, since the carbon material is mixed with lead powder (negative electrode active material) in a state of being suitably dispersed by the first premixing step, the effect of improving conductivity in the negative electrode active material is enhanced, and the carbon material is generated by electric discharge. It suppresses the production of lead sulfate and promotes the dissolution of lead sulfate.

Although the present inventor has not been able to specify the structure, physical properties, etc. of the negative electrode material paste obtained by carrying out the second premixing step, the action and effect of the second premixing step are inferred as follows. There is. Phenolic resins have both a hydrophilic part and a hydrophobic part in the molecule, and if they exist in a powder state (a state in which they are not dissolved in water), the water originally contained in the powder will be removed. At the center, an aggregate is formed with the hydrophilic part on the inside and the hydrophobic part on the outside. Such aggregates are called micelles, and in the micelleized state, they may not be sufficiently dissolved even if mixed with water after the fact, and may be difficult to be adsorbed on lead powder, and the function of the phenolic resin is sufficient. However, these points can be improved by the second premixing step.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples.

<Example 1>
(Manufacturing of negative electrode plate)
As the first premixing step, 100 parts by volume of oil furnace black (Vulcan XC72, manufactured by Cabot) having an average primary particle size of 50 nm or less is mixed with 100 parts by volume of water and kneaded, and water is further added. 10% dispersion (first mixture). The water used at this time was ion-exchanged water, which was the same as the water used for paste kneading described later.

Subsequently, 0.2 parts by mass of sodium lignin sulfonate was kneaded with respect to 100 parts by mass of lead powder having an average primary particle size of 1 μm, and then 1.0 with respect to 100 parts by mass of the first mixture described above, lead powder. A mass portion of barium sulfate and water were mixed and further kneaded. The first mixture was blended so that the blending amount of the carbon material was 0.2 parts by mass with respect to 100 parts by mass of the lead powder.

Next, dilute sulfuric acid (specific gravity 1.26 (converted to 20 ° C.)) and water were added and further kneaded to prepare a negative electrode material paste. An expanded current collector (lead-calcium-tin alloy) having a thickness of 1.0 mm was filled with a negative electrode material paste to prepare a negative electrode plate. The negative electrode plate was aged for 20 hours in an atmosphere of a temperature of 50 ° C. and a humidity of 95%, and then dried in an atmosphere of a temperature of 50 ° C. to obtain an unmodified negative electrode plate.

(Manufacturing of positive electrode plate)
To the lead powder having an average particle diameter of 1 μm, 0.1% by mass of reinforcing short fibers (acrylic fibers) were added based on the total mass of the lead powder, and then dry-mixed. Next, dilute sulfuric acid (specific gravity 1.28 (20 ° C. conversion)) and water were added and kneaded to prepare a positive electrode material paste. An expanded current collector (lead-calcium-tin alloy) is filled with a positive electrode material paste, aged for 20 hours in an atmosphere of a temperature of 50 ° C. and a humidity of 95%, and then dried in an atmosphere of a temperature of 50 ° C. and not yet dried. A chemical positive electrode plate was obtained.

(Assembly of lead-acid battery)
Six unchemicald negative electrode plates and five unchemicald positive electrode plates are laminated via a polyethylene separator so that the unmodified negative electrode plates and the unmodified positive electrode plates are alternately laminated, and then have the same polarity. A group of electrode plates was produced by welding the current collectors with straps. A 2V single cell battery was assembled by inserting the electrode plates into the battery case. After injecting dilute sulfuric acid (specific gravity 1.26 (converted to 20 ° C.)) into this battery, it was formed in a water tank at 40 ° C. under the condition of an energizing current of 10.0 A for 15 hours. After the completion of the chemical conversion, the lead-acid battery of Example 1 was obtained by adjusting the amount to 1.28 (20 ° C. equivalent) dilute sulfuric acid.

<Example 2>
As a second premixing step without carrying out the first premixing step, a step of mixing sodium lignin sulfonate while stirring water to prepare a 10% by mass aqueous solution (second mixture) in advance. Was carried out. That is, in Example 1, an oil furnace black that was not mixed with water was used in place of the first mixture, and a second mixture was used in place of sodium lignin sulfonate that was not mixed with water. Except for this, a negative electrode material paste was prepared in the same manner as in Example 1, a negative electrode plate and a positive electrode plate were prepared, and a lead storage battery was assembled.

<Example 3>
In addition to the first premixing step, the same second premixing step as in Example 2 was carried out. That is, in Example 1, a second mixture was used instead of sodium lignin sulfonate, which was not mixed with water. Except for this, a negative electrode material paste was prepared in the same manner as in Example 1, a negative electrode plate and a positive electrode plate were prepared, and a lead storage battery was assembled.

<Comparative example 1>
The first premixing step was not carried out. That is, in Example 1, oil furnace black not mixed with water was used instead of the first mixture. Except for this, a negative electrode material paste was prepared in the same manner as in Example 1, a negative electrode plate and a positive electrode plate were prepared, and a lead storage battery was assembled.

[Evaluation of charge acceptance performance]
The charge acceptance performance was evaluated for each of the lead-acid batteries of Examples 1 to 3 and Comparative Example 1. Specifically, as the charge acceptance performance, the state of charge (SOC) of the battery is 90% (that is, 10% of the battery capacity is discharged from the fully charged state, and the constant voltage is 2.33 V. The charge capacity 5 seconds after the start of charging in the charged state) was measured. The larger the charge capacity after 5 seconds, the better the charge acceptability of the battery. Table 1 shows the relative values when the charge acceptance performance of the lead storage battery of Comparative Example 1 is 100.

[Evaluation of discharge performance]
The discharge performance of each of the lead-acid batteries of Examples 1 to 3 and Comparative Example 1 was evaluated. Specifically, as the discharge performance, a constant current discharge was performed at 5 C at −15 ° C., and the discharge duration until the battery voltage reached 1.0 V was measured. The longer the discharge duration, the better the discharge characteristics of the battery. The C is a relative representation of the magnitude of the current when the rated capacity is discharged at a constant current from the fully charged state. For example, the current capable of discharging the rated capacity in 1 hour is expressed as 1C, and the current capable of discharging the rated capacity in 2 hours is expressed as 0.5C. Table 1 shows the relative values when the charge acceptance performance of the lead storage battery of Comparative Example 1 is 100.

[Evaluation of cycle performance]
The cycle performance was further evaluated for each of the lead-acid batteries of Examples 1 to 3 which were excellent in charge acceptance performance and discharge performance. Specifically, as the cycle performance, the number of cycles was evaluated by a method according to the idling stop life test of the Japan Battery Industry Association standard (SBAS 0101). The larger the number of cycles, the higher the cycle performance (idling stop durability) of the battery. Table 1 shows the relative values when the cycle performance of the lead-acid battery of Example 2 is 100.

1 ... Lead-acid battery, 2 ... Battery tank, 3 ... Lid, 4 ... Negative electrode terminal, 5 ... Positive electrode terminal, 6 ... Liquid spout, 7 ... Electrode group, 8 ... Negative electrode column, 9 ... Negative electrode, 10 ... Positive electrode, 11 ... Separator, 12 ... Negative electrode side strap, 13 ... Positive electrode side strap.

Claims (3)

A method for producing a negative electrode material paste, which comprises a step of mixing lead powder, a carbon material, a resin having a structural unit derived from a phenolic compound, and water.
A production method in which both the carbon material and the resin are subjected to the step as a mixture in which water is mixed in advance. A method for manufacturing a negative electrode, comprising a step of holding the negative electrode material paste obtained by the manufacturing method according to claim 1 in a current collector. A method for manufacturing a lead-acid battery, wherein a lead-acid battery is obtained by using the negative electrode obtained by the manufacturing method according to claim 2.

Images