lead-acid batteries

Abstract

When increasing capacity by reducing the bulk density of the positive electrode material, softening and shedding of the positive electrode material and overcharging are suppressed, resulting in a good cycle life. [Solution] The device comprises a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate contains a positive electrode material, and the negative electrode plate contains a negative electrode material. The negative electrode material contains a carbonaceous material and a fatty acid with 8 to 30 carbon atoms. The carbonaceous material content Cc in the negative electrode material is 0.25% by mass or more. When Y is the DBP oil absorption amount of the carbonaceous material and Cf (ppm) is the mass-based content of the fatty acid in the negative electrode material, the Cf / Y ratio is 0.1 ppm·mL. -1 The positive electrode material weighs 100g or more, contains antimony and resin fibers, has a bonding degree of 10% or more of resin fibers to the positive electrode material, and has a bulk density of 3.9g / cm³. 3 The following is a lead-acid battery.

Description

[Technical Field]

[0001] This invention relates to a lead-acid battery. [Background technology]

[0002] Lead-acid batteries are used in a variety of applications, including automotive and industrial use. A lead-acid battery consists of a negative electrode plate, a positive electrode plate, and an electrolyte. The negative electrode plate includes a current collector and a negative electrode material. The negative electrode material may include carbonaceous materials and organic shrinkage inhibitors. Additives may be added to the components of a lead-acid battery to impart various functions.

[0003] Patent Document 1 proposes a lead-acid battery comprising "a group of electrode plates and an electrolyte, wherein the group of electrode plates comprises a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, where D is the distance between the positive electrode plate and the negative electrode plate and T is the maximum thickness of the separator, so DT ≤ 0.15 mm, the negative electrode plate comprises a negative electrode material, the negative electrode material contains a polymer compound, and the polymer compound has a peak in the chemical shift of the 1H-NMR spectrum in the range of 3.2 ppm to 3.8 ppm."

[0004] Patent Document 2 proposes a lead-acid battery comprising a positive electrode plate, a negative electrode plate, and an electrolyte, wherein the negative electrode plate includes a negative electrode material, the negative electrode material includes an organic shrinkage inhibitor and a carbonaceous material, the organic shrinkage inhibitor includes a bisarene compound unit and a monocyclic aromatic compound unit having a hydroxyl group, and the bisarene compound unit is at least one selected from the group consisting of a bisphenol S compound unit and a bisphenol A compound unit.

[0005] Patent Document 3 proposes a sealed lead-acid battery in which a Pb-Ca alloy is used for the positive electrode grid, and antimony is added to the positive electrode active material to a concentration of 0.005% to 1.0% by weight of the positive electrode active material, characterized in that the density of the positive electrode active material is 3.75 g / cc or more after chemical formation. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2020 / 241884 [Patent Document 2] International Publication No. 2021 / 060323 [Patent Document 3] Japanese Patent Application Publication No. 11-126604 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, the increasing power consumption of vehicle electrical components has led to a demand for high-capacity lead-acid batteries. To increase the capacity of lead-acid batteries, improving the utilization rate by reducing the density of the positive electrode material is effective. However, when the density of the positive electrode material is reduced, the positive electrode material becomes more prone to softening and detachment after repeated charge-discharge cycles. This detached positive electrode material then deposits on the negative electrode plate, promoting hydrogen generation. This increased hydrogen generation leads to an increase in the amount of overcharged electricity, further accelerating the softening and detachment of the positive electrode material, and causing the positive electrode plate to deteriorate at an accelerating rate. [Means for solving the problem]

[0008] The first aspect of this disclosure includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate includes a positive electrode material, the negative electrode plate includes a negative electrode material, the negative electrode material includes a carbonaceous material and a fatty acid having 8 to 30 carbon atoms, the carbonaceous material content Cc in the negative electrode material is 0.25% by mass or more, and when Y is the DBP oil absorption amount of the carbonaceous material and Cf (ppm) is the mass-based content of the fatty acid in the negative electrode material, the Cf / Y ratio is 0.1 ppm·mL -1 The positive electrode material weighs 100g or more, contains antimony and resin fibers, has a degree of adhesion of the resin fibers to the positive electrode material of 10% or more, and has a bulk density of 3.9g / cm³. 3 The following concerns lead-acid batteries.

[0009] A second aspect of the present invention includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate includes a positive electrode material, the negative electrode plate includes a negative electrode material, the negative electrode material includes a fatty acid having 8 to 30 carbon atoms, and the specific surface area of ​​the negative electrode material is Sn(m²). 2 ( / g), when the mass-based content of the fatty acid in the negative electrode material is Cf (ppm), the Cf / Sn ratio is 20 ppm·m -2 The positive electrode material is 3.9 g / cm³ or more, contains antimony and resin fibers, has a degree of adhesion of the resin fibers to the positive electrode material of 10% or more, and has a bulk density of 3.9 g / cm³. 3 The following concerns lead-acid batteries. [Effects of the Invention]

[0010] According to this disclosure, when the capacity of a lead-acid battery is increased by reducing the bulk density of the positive electrode material, softening and shedding of the positive electrode material can be suppressed, and the amount of overcharged electricity can also be suppressed, thereby achieving a good cycle life. [Brief explanation of the drawing]

[0011] [Figure 1]This is a partially cutaway exploded perspective view showing the external appearance and internal structure of a lead-acid battery according to one embodiment of the present invention. [Modes for carrying out the invention]

[0012] The embodiments of this disclosure will be described below with examples, but this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of this disclosure are obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "greater than or equal to numerical value A and less than or equal to numerical value B". In the following description, when lower and upper limits of numerical values ​​relating to specific physical properties or conditions are given as examples, either of the given lower limits and either of the given upper limits can be arbitrarily combined, as long as the lower limit is not greater than or equal to the upper limit. When multiple materials are given as examples, one of them may be selected and used alone, or two or more may be used in combination.

[0013] Furthermore, this disclosure encompasses any combination of matters described in two or more claims, which may be arbitrarily selected from the multiple claims set forth in the attached claims. In other words, any combination of matters described in two or more claims, which may be arbitrarily selected from the multiple claims set forth in the attached claims, is possible, provided that no technical inconsistency arises.

[0014] A lead-acid battery comprises a positive electrode plate, a negative electrode plate, a separator interposed between the positive and negative electrode plates, and an electrolyte. The electrolyte contains sulfuric acid. Charging and discharging proceed through the movement of sulfate ions between the positive and negative electrode plates and the electrolyte. During discharge, sulfate ions move to the positive and negative electrode plates. During charging, sulfate ions move from the positive and negative electrode plates into the electrolyte.

[0015] A positive electrode plate, a negative electrode plate, and a separator constitute an electrode group. The electrode group, together with the electrolyte, constitutes a cell. One electrode group constitutes one cell. A lead-acid battery comprises one or more cells by comprising one or more electrode groups. There is no particular limit to the number of positive and negative electrode plates included in one electrode group. An electrode group comprising a lead-acid battery according to this disclosure may, for example, include a total of 12 or more positive and negative electrode plates. Multiple electrode groups are typically housed in separate cell chambers and connected in series with one another.

[0016] The positive electrode plate includes a positive electrode current collector and a positive electrode material. The positive electrode material is a positive electrode active material that exhibits capacity through oxidation-reduction reactions, and contains at least lead dioxide during charging and at least lead sulfate during discharge.

[0017] The negative electrode plate includes a negative electrode current collector and a negative electrode material. The negative electrode material is a negative electrode active material that exhibits capacity through oxidation-reduction reactions, and contains at least lead during charging and at least lead sulfate during discharging.

[0018] The negative electrode material and the positive electrode material are usually held by the current collector. The electrode material is the portion of the electrode plate excluding the current collector. The electrode plate may have components such as mats or pasting paper (adhesive components) attached to it. Since the adhesive components are used as an integral part of the electrode plate, they are included in the electrode plate. When the electrode plate includes adhesive components, the electrode material is the portion of the electrode plate excluding the current collector and adhesive components.

[0019] (1) A lead-acid battery according to an embodiment of the present disclosure includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate includes a positive electrode material, the negative electrode plate includes a negative electrode material, the negative electrode material includes a carbonaceous material and a fatty acid having 8 to 30 carbon atoms, the carbonaceous material content Cc in the negative electrode material is 0.25% by mass or more, and when Y is the DBP oil absorption amount of the carbonaceous material and Cf (ppm) is the mass-based content of the fatty acid in the negative electrode material, the Cf / Y ratio is 0.1 ppm·mL -1·More than 100 g, the positive electrode material includes antimony and resin fibers, the binding degree of the resin fibers to the positive electrode material is 10% or more, and the bulk density of the positive electrode material is 3.9 g / cm 3 or less, relating to a lead-acid battery.

[0020] (2) The lead-acid battery according to another embodiment of the present disclosure includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive electrode material, the negative electrode plate includes a negative electrode material, the negative electrode material includes a fatty acid having 8 to 30 carbon atoms, and the specific surface area of the negative electrode material is Sn (m 2 / g). When the content rate of the fatty acid in the negative electrode material based on mass is Cf (ppm), the Cf / Sn ratio is 20 ppm·m -2 ·g or more. The positive electrode material includes antimony and resin fibers, the binding degree of the resin fibers to the positive electrode material is 10% or more, and the bulk density of the positive electrode material is 3.9 g / cm 3 or less, relating to a lead-acid battery.

[0021] The lead-acid battery described in (1) or (2) above has a high capacity because the bulk density is reduced to 3.9 g / cm 3 or less. In addition, since the positive electrode material includes antimony and resin fibers, and the binding degree of the resin fibers to the positive electrode material is increased to 10% or more, softening and shedding of the positive electrode material can be suppressed despite the small bulk density. And since the negative electrode material includes a fatty acid having 8 to 30 carbon atoms, even when the positive electrode material falls off, deposition of the fallen particles (especially antimony) on the negative electrode plate is suppressed, liquid reduction and excessive overcharging are suppressed, and accelerated deterioration of the positive electrode plate does not occur. This is considered to be because the fatty acid having 8 to 30 carbon atoms has high insulation, inhibits electron conduction to the fallen particles floating in the electrolyte, and suppresses the reduction reaction of PbO2. As described above, the lead-acid battery can achieve a good cycle life.

[0022] However, if the negative electrode material contains a carbonaceous material, and Y is the amount of DBP oil absorbed by the carbonaceous material, and Cf (ppm) is the mass-based content of fatty acids in the negative electrode material, then the Cf / Y ratio is 0.1 ppm·mL. -1 It must be 100g or more. Carbonaceous materials are effective in improving the charge acceptance of the negative electrode plate and reducing the accumulation of lead sulfate on the negative electrode plate, but the Cf / Y ratio must be 0.1 ppm·mL. -1 If the amount is less than 100g, there will be a deficiency of fatty acids with 8 to 30 carbon atoms, and the effect of suppressing the reduction reaction of PbO2 will not be sufficient. As a result, antimony deposition on the negative electrode plate cannot be sufficiently suppressed, making it difficult to suppress liquid depletion and overcharging.

[0023] Furthermore, the specific surface area of ​​the negative electrode material is Sn(m²). 2 ( / g), when the mass-based content of fatty acids in the negative electrode material is Cf (ppm), the Cf / Sn ratio is 20 ppm·m -2 It must be at least 20 ppm·m. The Cf / Sn ratio must be 20 ppm·m -2 Below 1 / 2g, there is a deficiency of fatty acids with 8 to 30 carbon atoms, and the effect of suppressing the reduction reaction of PbO2 becomes insufficient. As a result, antimony deposition on the negative electrode plate cannot be sufficiently suppressed, and it becomes difficult to suppress liquid depletion and overcharging.

[0024] As described above, in order to fully exhibit the effect of suppressing electrolyte loss and overcharging caused by fatty acids with 8 to 30 carbon atoms (hereinafter also referred to as "first fatty acids") in the lead-acid battery described in (1) or (2) above, Cf / Sn ≥ 20 ppm·m -2 ·g and Cf / Y ≥ 0.1 ppm · mL -1 It is necessary to satisfy at least one of the requirements of 100g.

[0025] The first fatty acid is considered to have an excellent balance of hydrophobicity and hydrophilicity when acting on the negative electrode plate of a lead-acid battery. The first fatty acid has a hydrocarbon structure with one carboxyl group. The hydrocarbon portion of the first fatty acid, with 8 to 30 carbon atoms, exhibits moderate hydrophobicity. On the other hand, the carboxyl group exhibits moderate hydrophilicity. As a result, the first fatty acid can firmly bond to hydroxyl groups or adsorbed water present in the oxide layer on the lead surface via hydrogen bonds (or covalent bonds). Furthermore, if the negative electrode material contains a carbonaceous material, it can selectively adhere to the carbonaceous material. As a result, the first fatty acid tends to remain on the negative electrode material and does not easily dissolve into the electrolyte. Therefore, it is considered that the insulating properties necessary to suppress antimony deposition in the negative electrode material are exhibited over the long term.

[0026] In the mechanism described above, the effect of the first fatty acid in the negative electrode material is easily influenced by the amount of DBP oil absorbed by the carbonaceous material Y and / or the specific surface area Sn of the negative electrode material. Therefore, it becomes necessary to determine the content Cf of the first fatty acid according to the amount of DBP oil absorbed by the carbonaceous material Y or the specific surface area Sn of the negative electrode material.

[0027] Generally, when organic components adhere to the surface of the negative electrode material, the charge acceptance tends to decrease. Also, as the specific surface area of ​​the negative electrode material increases, the charge acceptance tends to increase, and the amount of overcharge tends to increase. In contrast, in the lead-acid batteries described in (1) or (2) above, the lead surface is thought to be very thinly covered with primary fatty acids having 8 to 30 carbon atoms and relatively small molecular weights, thus maintaining high charge acceptance. Therefore, even when the specific surface area of ​​the negative electrode material (Sn) is large, side reactions during overcharging are suppressed, and softening and shedding of the positive electrode material due to overcharging are suppressed.

[0028] (3) In the lead-acid battery described in (1) or (2) above, the content of primary fatty acid Cf may be 20 ppm or more and 600 ppm or less by mass. When the content of primary fatty acid Cf is 20 ppm or more, the effect of suppressing the reduction of detached particles (especially antimony) on the negative electrode plate is greatly increased. On the other hand, when the content of primary fatty acid Cf is 600 ppm or less, higher charge acceptance can be ensured.

[0029] (4) In any one of the lead-acid batteries described in (1) to (3) above, the Cf / Sn ratio is 1000 ppm·m -2 It may be less than or equal to g. In this case, even higher charge acceptance can be ensured. That is, softening and shedding of the positive electrode material due to overcharging is significantly suppressed.

[0030] (5) In any one of the lead-acid batteries described in (1) to (4) above, if the negative electrode material contains a carbonaceous material, the carbonaceous material content Cc in the negative electrode material may be 0.25% by mass or more. In this case, the charge acceptance of the negative electrode plate is significantly improved, and the accumulation of lead sulfate on the negative electrode plate is reduced. As a result, the cycle characteristics are further improved.

[0031] (6) In any one of the lead-acid batteries described in (1) to (5) above, the particle size of the carbonaceous material may be less than 32 μm. In this case, the dispersibility of the carbonaceous material is improved, and the charge acceptance is further improved. The carbonaceous material with a particle size of less than 32 μm may include carbon black. Because carbon black has a well-developed secondary particle structure, it tends to increase the specific surface area Sn of the negative electrode material or the DBP oil absorption Y of the carbonaceous material. Even when carbon black is used as the negative electrode material, the effect of the primary fatty acid is significantly expressed by determining the primary fatty acid content Cf according to the specific surface area Sn or DBP oil absorption Y.

[0032] (7) In any one of the lead-acid batteries described in (1) to (6) above, the carbonaceous material content Cc may be 2% by mass or less. In this case, aggregation of the carbonaceous material in the negative electrode material is suppressed, improving dispersibility, and the handling of the negative electrode paste when manufacturing the negative electrode plate is improved.

[0033] (8) In any one of the lead-acid batteries described in (1) to (7) above, Cf / Sn ≥ 20 ppm·m -2 ·g and Cf / Y ≥ 0.1 ppm · mL -1 Both 100g requirements may be met. In this case, the effects of the primary fatty acid will be more pronounced.

[0034] (9) In any one of the lead-acid batteries described in (1) to (8) above, the Cf / Y ratio is 2 ppm·mL -1 • It may be 100g or less. In this case, higher charge acceptance can be ensured.

[0035] Any one of the lead-acid batteries described in (1) to (9) above is particularly suitable as a liquid-type (vented) lead-acid battery, but may also be a valve-regulated lead-acid battery (VRLA).

[0036] Here, the carbonaceous material content Cc, the primary fatty acid content Cf, the specific surface area Sn of the negative electrode material, and the DBP oil absorption amount Y of the carbonaceous material are values ​​obtained for negative electrode material sampled from a negative electrode plate removed from a fully charged lead-acid battery.

[0037] The specific surface area Sn of the negative electrode material is the specific surface area (BET specific surface area) calculated by the BET (Brunauer-Emmett-Teller) method (unit: m²). 2 The BET specific surface area is calculated using the BET formula by a gas adsorption method that utilizes nitrogen gas as the adsorption gas.

[0038] DBP oil absorption is expressed as the amount (mL) of dibutyl phthalate (DBP) adsorbed or absorbed by 100g of powder. Therefore, the unit of DBP oil absorption is expressed as mL / 100g. The method for measuring DBP oil absorption is specified in JIS K 6217-4-2017. In carbonaceous materials, primary particles aggregate to form secondary particles, and DBP can be absorbed into the voids between primary particles in the secondary particles.

[0039] The fully charged state of a liquid-type lead-acid battery is defined according to JIS D 5301:2019. More specifically, a fully charged state is defined as the state in which a lead-acid battery is charged at a current (A) equal to 0.2 times the rated capacity (a value expressed in Ah) while in a water bath at 25°C ± 2°C, until the terminal voltage (V) during charging, measured every 15 minutes, or the electrolyte density converted to a temperature of 20°C, shows a constant value with three significant figures for three consecutive times.

[0040] In the case of valve-regulated lead-acid batteries, a fully charged state is defined as a state where charging is performed in an air chamber at 25°C ± 2°C with a constant current and constant voltage of 2.23V / cell at a current (A) equal to 0.2 times the value (A) indicated for the rated capacity (a value expressed in Ah), and charging is terminated when the charging current during constant voltage charging reaches 0.005 times the value (A) indicated for the rated capacity (a value expressed in Ah).

[0041] A fully charged lead-acid battery refers to a lead-acid battery that has been fully charged after chemical formation. Full charging of a lead-acid battery can be done immediately after chemical formation, or some time after formation (for example, a lead-acid battery that has been chemically formed and is in use (preferably in the early stages of use) can be fully charged). An early-stage battery refers to a battery that has not been in use for very long and has hardly deteriorated.

[0042] The lead-acid battery related to this disclosure will be described in more detail below, for each major component. Within the limits of what is technically consistent, at least one of (1) to (9) above may be combined with at least one of the elements described below.

[0043] [Lead acid battery] (Negative electrode plate) The negative electrode plate comprises a negative electrode material and a negative electrode current collector.

[0044] (Negative electrode current collector) The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead sheet or a lead alloy sheet. Examples of processing methods include expanding or punching. Using a grid-shaped current collector as the negative electrode current collector is preferable because it makes it easier to support the negative electrode material.

[0045] The lead alloy used for the negative electrode current collector may be a Pb-Sb alloy, a Pb-Ca alloy, or a Pb-Ca-Sn (tin) alloy. These lead or lead alloys may further contain at least one additive element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, etc. The negative electrode current collector may have a surface layer. The surface layer and the inner layer of the negative electrode current collector may have different compositions. The surface layer may be formed to cover the entire negative electrode current collector, or it may be formed on a part of the negative electrode current collector. The surface layer may be formed on the lugs of the negative electrode current collector. The surface layer of the lugs may contain Sn (tin) or a Sn (tin) alloy.

[0046] (Negative electrode material) The negative electrode material comprises a negative electrode active material (specifically, lead or lead sulfate) and a primary fatty acid. The negative electrode material may also contain a carbonaceous material and may further contain additives other than the primary fatty acid and carbonaceous material. Examples of such additives include organic shrinkage inhibitors, barium sulfate, and fibers (such as resin fibers). The negative electrode active material in the charged state is spongy lead. Unformed negative electrode plates are usually made using lead powder.

[0047] (carbonaceous material) The carbonaceous material that may be included in the negative electrode material may be a carbonaceous material with a particle size of less than 32 μm (first carbonaceous material), or it may be both a first carbonaceous material and a carbonaceous material with a particle size of 32 μm or more (second carbonaceous material).

[0048] The content Cc1 of the first carbonaceous material in the negative electrode material is 0.25% by mass or more, may be 0.3% by mass or more, may be 0.4% by mass or more, or may be 0.5% by mass or more. When the content Cc1 is within this range, it is easy to ensure high charge acceptance. The content Cc1 may be 5% by mass or less, or 3% by mass or less. From the viewpoint of easily ensuring higher charge acceptance, a content Cc1 of 2% by mass or less is preferable.

[0049] The content Cc1 of the first carbonaceous material may be 0.25% by mass or more (or 0.3% by mass or more) and 5% by mass or less, 0.25% by mass or more (or 0.3% by mass or more) and 4% by mass or less, 0.3% by mass or more (or 0.4% by mass or more) and 3% by mass or less, or 0.3% by mass or more (or 0.4% by mass or more) and 2% by mass or less.

[0050] The first carbonaceous material preferably contains at least carbon black. Carbon black has a well-developed secondary particle structure, which is susceptible to the binding properties of the first fatty acid. In this case, the content Cf of the first fatty acid is determined according to at least one of the specific surface area Sn of the negative electrode material and the DBP oil absorption Y of the carbonaceous material, thereby achieving a significant effect from the first fatty acid.

[0051] Examples of carbon black include acetylene black, furnace black, and lamp black. The negative electrode material may contain one primary carbonaceous material (for example, these carbon blacks) or a combination of two or more.

[0052] The specific surface area Sc of the first carbonaceous material is, for example, 20 m². 2 / g or more, 25m 2 / g or more or 28m 2 It may be 1500 m² or more. When the specific surface area Sc is within this range, it is easier to suppress the content of the primary fatty acid from becoming excessively high and to ensure high charge acceptance. The specific surface area Sc of the primary carbonaceous material is, for example, 1500 m². 2 It is less than / g and 1300m 2It may be less than / g. The specific surface area Sc is 800m². 2 Preferably less than / g, 200m 2 / g or less or 150m 2 It may be less than / g.

[0053] In this specification, the specific surface area Sc of the first carbonaceous material refers to the specific surface area (BET specific surface area) obtained by the BET method using a gas adsorption method utilizing nitrogen gas (unit: m²). 2 The specific surface area (Sc) of a carbonaceous material is a value obtained for a negative electrode plate removed from a fully charged lead-acid battery.

[0054] The specific surface area (Sc) of the first carbonaceous material is 20 m². 2 / g or more (or 25m 2 / g or more) 1500m 2 / g or less, 20m 2 / g or more (or 25m 2 / g or more) 1300m 2 / g or less, 20m 2 / g or more (or 25m 2 / g or more) 800m 2 / g or less, 20m 2 / g or more (or 25m 2 / g or more)200m 2 / g or less, 20m 2 / g or more (or 25m 2 / g or more) 150m 2 / g or less, 28m 2 / g or more 1500m 2 / g or less (or 1300m 2 / g or less), 28m 2 / g or more 800m 2 / g or less (or 200m 2 (less than / g), or 28m 2 / g or more 150m 2 It may be less than / g.

[0055] The DBP oil absorption Y of the first carbonaceous material is, for example, 30 mL / 100 g or more, may be 50 mL / 100 g or more, or 65 mL / 100 g or more. When the DBP oil absorption Y is within this range, it is easier to suppress an excessively high content of the first fatty acid and to ensure high charge acceptance. The DBP oil absorption Y of the first carbonaceous material is, for example, 600 mL / 100 g or less, may be 500 mL / 100 g or less. The DBP oil absorption Y is preferably 400 mL / 100 g or less, may be 360 ​​mL / 100 g or less, or 200 mL / 100 g or less.

[0056] DBP oil absorption Y is 30 mL / 100g or more and 600 mL / 100g or less (or 500 mL / 100g or less), 30 mL / 100g or more and 400 mL / 100g or less (or 360 mL / 100g or less), 30 mL / 100g or more (or 50 mL / 100g or more) and 200 mL / 100g or less, 50 mL / 100g or more and 600 mL / 100g or less (or 500 mL / 1 It may be 00g or less, 50mL / 100g or more and 400mL / 100g or less (or 360mL / 100g or less), 65mL / 100g or more and 600mL / 100g or less (or 500mL / 100g or less), 65mL / 100g or more and 400mL / 100g or less (or 360mL / 100g or less), or 65mL / 100g or more and 200mL / 100g or less.

[0057] Examples of secondary carbonaceous materials include graphite, hard carbon, and soft carbon. The negative electrode material may contain one secondary carbonaceous material or a combination of two or more. Using a primary carbonaceous material and a secondary carbonaceous material in combination can improve cycle life performance in the PSOC (partially charged state). The secondary carbonaceous material preferably contains at least graphite.

[0058] The content of the secondary carbonaceous material Cc2 in the negative electrode material may be 0.01% by mass or more, or 0.05% by mass or more. When the content Cc2 is within this range, it is easier to obtain higher PSOC lifetime performance and higher charge acceptance. From the viewpoint of easily suppressing the amount of overcharged electricity, the content Cc2 may be 3% by mass or less, or 2% by mass or less.

[0059] The content of the secondary carbonaceous material Cc2 in the negative electrode material may be 0.01% by mass or more (or 0.05% by mass or more) and 3% by mass or less, or 0.01% by mass or more (or 0.05% by mass or more) and 2% by mass or less.

[0060] The proportion of the first carbonaceous material (such as carbon black) to the total amount of the carbonaceous material (for example, the total amount of the first carbonaceous material and the second carbonaceous material) may be, for example, 20% by mass or more, but may also be 50% by mass or more, 80% by mass or more, or 90% by mass or more. When the proportion of the first carbonaceous material (such as carbon black) is within this range, higher charge acceptance can be ensured. The proportion of the first carbonaceous material (such as carbon black) to the total amount of the carbonaceous material (for example, the total amount of the first carbonaceous material and the second carbonaceous material) may also be, for example, 100% by mass or less, or 95% by mass or less. The carbonaceous material may consist only of the first carbonaceous material (or carbon black).

[0061] The proportion of the primary carbonaceous material (such as carbon black) to the total amount of the carbonaceous material (for example, the total amount of the primary carbonaceous material and the secondary carbonaceous material) may be 20% by mass or more and 100% by mass or less (or 95% by mass or less), 50% by mass or more and 100% by mass or less (or 95% by mass or less), 80% by mass or more and 100% by mass or less (or 95% by mass or less), or 90% by mass or more and 100% by mass or less (or 95% by mass or less).

[0062] (1st fatty acid) The number of carbon atoms in the first fatty acid is 8 or more, preferably 9 or more. The number of carbon atoms in the first fatty acid is 30 or less, may be 24 or less, or 20 or less.

[0063] The carbon number of the first fatty acid is 8 or more (or 9 or more) and 30 or less, and may also be 8 or more (or 9 or more) and 24 or less, or 8 or more (or 9 or more) and 20 or less.

[0064] The first fatty acid may be either saturated or unsaturated. The number of carbon-carbon unsaturated bonds in the first fatty acid may be, for example, 6 or less, 4 or less, or 2 or less, depending on the number of carbon atoms in the first fatty acid. The number of carbon-carbon unsaturated bonds in the first fatty acid may be 1 or more. In terms of easily balancing hydrophobicity and hydrophilicity, it is preferable that the first fatty acid has no substituents other than one carboxyl group.

[0065] Specific examples of first fatty acids include octanoic acid, nonanoic acid (pelargonic acid), capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, arachidonic acid, behenic acid, eicosaheptaenoic acid, and docosahexaenoic acid.

[0066] The negative electrode material may contain one type of primary fatty acid, or a combination of two or more types.

[0067] The content of the primary fatty acid Cf in the negative electrode material is, for example, 15 ppm or more by mass, preferably 20 ppm or more, and may be 50 ppm or more. The Cf is, for example, 1000 ppm or less by mass, preferably 600 ppm or less.

[0068] The content of the primary fatty acid Cf in the negative electrode material may be 15 ppm to 1000 ppm (or 600 ppm or less) by mass, 20 ppm to 1000 ppm (or 600 ppm or less), or 50 ppm to 1000 ppm (or 600 ppm or less).

[0069] The ratio Cf / Sn is 20 ppm·m -2 •g or more is also acceptable, up to 23 ppm·m -2It may be greater than or equal to 1000 ppm·m. The ratio Cf / Sn is 1000 ppm·m -2 It may be less than or equal to 910 ppm·m -2 It may be less than or equal to 1g. Note that ppm in the ratio Cf / Sn is derived from the mass-based content of Cf, and therefore is based on mass.

[0070] The ratio Cf / Sn is 20 ppm·m -2 •g or more (or 23 ppm·m) -2 ·g or more) 1000ppm·m -2 Less than 20 ppm·m -2 •g or more (or 23 ppm·m) -2 ·g or more)910ppm·m -2 It may be less than g.

[0071] The ratio Cf / Y is 0.1 ppm·mL -1 • 100g or more is acceptable, and the concentration is 0.12 ppm·mL. -1 • It may be 100g or more. The ratio Cf / Y is, for example, 12 ppm·mL. -1 • Less than 100g, 9.5ppm·mL -1 • It may be 100g or less. The ratio Cf / Y is 5 ppm·mL. -1 • 100g or less or 3.5ppm·mL -1 It may be 100g or less. Note that ppm in the ratio Cf / Y is derived from the mass-based content of Cf, and therefore is based on mass.

[0072] The ratio Cf / Y is 0.1 ppm·mL -1 • 100g or more (or 0.12 ppm / mL) -1 ·100g or more)12ppm·mL -1 ·Less than 100g, 0.1ppm·mL -1 • 100g or more (or 0.12 ppm / mL) -1 ·100g or more)9.5ppm·mL -1 ·Less than 100g, 0.1ppm·mL -1 • 100g or more (or 0.12 ppm / mL) -1 ·100g or more)5ppm·mL -1• 100g or less, or 0.1 ppm·mL -1 • 100g or more (or 0.12 ppm / mL) -1 ·100g or more)3.5ppm·mL -1 It can be 100g or less.

[0073] (Organic shrinkage inhibitor) Examples of organic shrinkage inhibitors include lignin compounds and synthetic organic shrinkage inhibitors. Examples of lignin compounds include lignin, lignin derivatives (e.g., lignin sulfonic acid or its salts (such as alkali metal salts like sodium salts)). Synthetic organic shrinkage inhibitors are organic polymers containing sulfur elements. Examples of synthetic organic shrinkage inhibitors include condensates of compounds having sulfur-containing groups and aromatic rings (phenol compounds, aniline compounds, etc.) with aldehyde compounds (aldehydes or their condensates, such as formaldehyde). However, organic shrinkage inhibitors are not limited to these specific examples.

[0074] The negative electrode material may contain one type of organic shrinkage inhibitor, or it may contain a combination of two or more types.

[0075] The content of the organic shrinkage inhibitor in the negative electrode material is, for example, 0.01% by mass or more. The content of the organic shrinkage inhibitor may be, for example, 1% by mass or less, or 0.5% by mass or less.

[0076] (Barium sulfate) The barium sulfate content in the negative electrode material is, for example, 0.05% by mass or more, and may be 0.1% by mass or more. The barium sulfate content is, for example, 3% by mass or less.

[0077] (Specific surface area of ​​negative electrode material Sn) The specific surface area Sn of the negative electrode material is, for example, 0.3 m². 2 It is 0.5m or more / g 2 Preferably 0.8 m 2 A value of 1 / g or more is more preferable. The specific surface area Sn is, for example, 4m². 2 It is less than / g and 2.7m 2Preferably below 2.5 m / g, more preferably below 1 m / g, still more preferably below 0.88 m / g. The specific surface area Sn of the negative electrode material can be adjusted by, for example, adjusting the specific surface area and / or content rate of the constituent components (particularly, the first carbonaceous material) of the negative electrode material. 2 Preferably below 2.5 m / g, more preferably below 1 m / g, still more preferably below 0.88 m / g. 2 Preferably below 0.88 m / g, more preferably below. The specific surface area Sn of the negative electrode material can be adjusted by, for example, adjusting the specific surface area and / or content rate of the constituent components (particularly, the first carbonaceous material) of the negative electrode material. 2 Preferably below 0.88 m / g, more preferably below.

[0078] The specific surface area Sn of the negative electrode material is 0.3 m / g or more (or 0.5 m / g or more) and 4 m / g or less, 0.3 m / g or more (or 0.5 m / g or more) and 2.7 m / g or less, 0.3 m / g or more (or 0.5 m / g or more) and 2.5 m / g or less, 0.3 m / g or more (or 0.5 m / g or more) and 1 m / g or less, 0.3 m / g or more (or 0.5 m / g or more) and 0.88 m / g or less, 0.8 m / g or more and 4 m / g or less (or 2.7 m / g or less), 0.8 m / g or more and 2.5 m / g or less (or 1 m / g or less), or 0.8 m / g or more and 0.88 m / g or less. 2 / g or more (or 0.5 m / g or more) 2 4 m / g or less 2 0.3 m / g or more (or 0.5 m / g or more) 2 / g or more (or 0.5 m / g or more) 2 2.7 m / g or less 2 0.3 m / g or more (or 0.5 m / g or more) 2 / g or more (or 0.5 m / g or more) 2 2.5 m / g or less 2 0.3 m / g or more (or 0.5 m / g or more) 2 / g or more (or 0.5 m / g or more) 2 1 m / g or less 2 0.3 m / g or more (or 0.5 m / g or more) 2 / g or more (or 0.5 m / g or more) 2 0.88 m / g or less 2 0.8 m / g or more 2 4 m / g or less 2 / g or less (or 2.7 m / g or less) 2 0.8 m / g or more 2 2.5 m / g or less 2 / g or less (or 1 m / g or less) 2 or 0.8 m / g or more 2 0.88 m / g or less 2 may also be the case.

[0079] (Analysis or measurement of the negative electrode material) The following describes the method for analyzing the negative electrode material or its components. Prior to measurement or analysis, a fully charged lead-acid battery is disassembled to obtain the negative electrode plate to be analyzed. The obtained negative electrode plate is washed with water to remove sulfuric acid. Washing is continued until a pH test paper is pressed against the surface of the washed negative electrode plate and the color of the test paper does not change. However, the washing time should be no more than 2 hours. The washed negative electrode plate is dried under reduced pressure at 60±5℃ for about 6 hours. If the negative electrode plate contains adhesive material, remove the adhesive material as necessary. 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 crushed as necessary and subjected to analysis.

[0080] (1) Measurement of the specific surface area Sn of the negative electrode material The BET specific surface area Sn of the negative electrode material is evaluated using the following procedure. First, a fully charged lead-acid battery is disassembled and the negative electrode plate is removed. Next, the sulfuric acid in the negative electrode plate is removed by washing it with water, and then the negative electrode plate is dried. The negative electrode material is collected from the dried negative electrode plate. The collected negative electrode material is pre-treated by heating it in a nitrogen flow at a temperature of 150°C for 1 hour. The BET specific surface area of ​​the pre-treated material is determined by mass measurement, gas adsorption method measurement, and calculation using the BET formula. Specifically, the BET specific surface area is determined by measurement using the following apparatus and conditions, and by calculation using the following calculation method. Measurement device: TriStar3000 manufactured by Micromerities Corporation Adsorption gas: Nitrogen gas with a purity of 99.99% or higher. Adsorption temperature: Boiling point temperature of liquid nitrogen (77K) Method for calculating BET specific surface area: Conforms to JIS Z 8830:2013, section 7.2.

[0081] (2) Analysis of primary fatty acids (2-1) Qualitative analysis of fatty acids The pulverized sample A is used. 150.0 ± 0.1 mL of chloroform is added to 100.0 ± 0.1 g of sample A, and the mixture is stirred at 20 ± 5 °C for 16 hours to extract the fatty acids. The solids are then removed by filtration. The structure of the fatty acids is determined from the chloroform solution containing the extracted fatty acids, or from the fatty acids obtained by drying this chloroform solution, by obtaining information from at least one of the following: infrared spectroscopy, ultraviolet-visible absorption spectroscopy, NMR spectroscopy, LC-MS, and pyrolysis GC-MS.

[0082] (2-2) Quantitative analysis of fatty acids The appropriate amount of fatty acid obtained by drying the above chloroform solution was measured with an accuracy of ±0.0001g. r (g) Dissolve in deuterated chloroform together with tetrachloroethane (TCE), 1 Measure the 1H-NMR spectrum. The integral value of the fatty acid-derived peak located at a chemical shift of 2.34 ppm (S a ) and the integral value of the peak originating from TCE (S r ) is calculated, and the mass-based content C of fatty acids in the negative electrode material is obtained from the following formula. n Calculate (ppm).

[0083] C n =S a / S r ×N r / N a ×M a / M r xm r / m × 1,000,000 (In the formula, M a This is the molecular weight of the structure that shows a chemical shift peak of 2.34 ppm (more specifically, the molecular weight showing the fatty acid structure in the chemical shift), and N a N is the number of hydrogen atoms bonded to the carbon atoms in the main chain. r、 M r (where m(g) is the mass of the negative electrode material used for extraction, and the numbers represent the number of hydrogen atoms in the molecule of the reference substance and the molecular weight of the reference substance, respectively.) Note that the reference substance in this analysis is TCE (trichloroethylene), therefore N r =2, M r = 168. Also, m = 100. For example, if the fatty acid is oleic acid, M a It is 59, N a The answer is 2.

[0084] 1 The H-NMR spectrum is measured under the following conditions. Equipment: AL400 type nuclear magnetic resonance spectrometer manufactured by JEOL Ltd. Observation frequency: 395.88MHz Pulse width: 6.30 μs Pulse repetition time: 74.1411 seconds Total number of times: 32 Measurement temperature: Room temperature (20℃ or higher and 35℃ or lower) Reference: 7.24 ppm Sample tube diameter: 5 mm

[0085] In quantitative analysis, 1 The integral values ​​of the peaks in the H-NMR spectrum are determined using the data processing software "ALICE" manufactured by JEOL Ltd.

[0086] (3) Analysis of carbonaceous materials (3-1) Separation and quantification of carbonaceous materials The pulverized sample A is used. 30 mL of a 60% by mass nitric acid aqueous solution is added to 5 g of sample A, and the mixture is heated at 70°C ± 5°C. Furthermore, 10 g of disodium ethylenediaminetetraacetate, 30 mL of ammonia water (28% by mass), and 100 mL of water are added to 5 g of sample A, and heating is continued to dissolve the soluble components. The sample pretreated in this manner is collected by filtration. The collected sample is passed through a 500 μm sieve to remove larger components such as reinforcing materials, and the components that pass through the sieve are collected as carbonaceous material.

[0087] Next, the first carbonaceous material and the second carbonaceous material are separated using the following procedure. When the recovered carbonaceous material is sieved wet using a sieve with a mesh size of 32 μm, the material that does not pass through the sieve and remains on the sieve is designated as the second carbonaceous material, and the material that passes through the sieve is designated as the first carbonaceous material. In other words, the particle size of each carbonaceous material is based on the mesh size of the sieve. For details on wet sieving, refer to JIS Z8815:1994.

[0088] Specifically, the carbonaceous material is placed on a sieve with a mesh size of 32 μm, and the sieve is gently shaken for 5 minutes while deionized water is sprayed on it to separate the material. The secondary carbonaceous material remaining on the sieve is collected by pouring deionized water over it and separated from the deionized water by filtration. The primary carbonaceous material that has passed through the sieve is collected by filtration using a nitrocellulose membrane filter (mesh size 0.1 μm). The collected primary and secondary carbonaceous materials are each dried at a temperature of 100°C ± 5°C for 2 hours. As the sieve with a mesh size of 32 μm, a sieve with a nominal mesh size of 32 μm as specified in JIS Z 8801-1:2019 is used.

[0089] The proportion of the primary carbonaceous material in the total carbonaceous material is determined by calculating the ratio (mass %) of the measured mass of the primary carbonaceous material to the total mass of the carbonaceous material (the sum of the masses of each carbonaceous material).

[0090] (3-2) Specific surface area of ​​the first carbonaceous material Sc The BET specific surface area Sc of the first carbonaceous material is determined using the BET formula by gas adsorption using the first carbonaceous material separated by the procedure in (3-1) above. The first carbonaceous material is pretreated by heating in a nitrogen flow at a temperature of 150°C for 1 hour to remove moisture. Using the pretreated first carbonaceous material, the BET specific surface area of ​​the first carbonaceous material is determined in accordance with the case of the specific surface area Sn of the negative electrode material in (1) above.

[0091] (3-3) DBP oil absorption amount Y of the first carbonaceous material The amount of DBP absorbed by the first carbonaceous material Y is measured using an absorbometer in accordance with JIS K 6217-4:2017, using the first carbonaceous material separated by the procedure described in (3-1) above. More specifically, a fixed amount of carbonaceous material is placed in the mixing chamber of the absorbometer, and the rotor is rotated at 125 rpm while dibutyl phthalate (DBP) is simultaneously added dropwise from an automatic burette at a rate of 4 ml / min. As time progresses, mixing occurs, and the powder in the mixing chamber turns into a paste, creating resistance to the rotor's rotation. At a certain point, the torque rises sharply in response to an increase in the amount of DBP added, and then follows a downward curve. In the downward curve, the point where the torque reaches 70% of the maximum value is used as the endpoint, and the amount of DBP used is taken as the adsorption amount. The absorbometer used is the S410E manufactured by Asahi Research Institute Co., Ltd. Measurement is performed by ensuring that no air bubbles enter the DBP when adding it to the automatic burette of the absorbometer.

[0092] (others) The negative electrode material may contain fatty acids other than the primary fatty acid (hereinafter referred to as secondary fatty acids). Examples of secondary fatty acids include at least one selected from the group consisting of fatty acids with 7 or fewer carbon atoms and fatty acids with more than 30 carbon atoms. A lower content of secondary fatty acids is preferable. The content of secondary fatty acids in the negative electrode material may be, for example, 10 ppm or less, or 5 ppm or less. It is also preferable that the negative electrode material does not contain secondary fatty acids.

[0093] Unformed negative electrode plates are manufactured, for example, by applying or filling a negative electrode paste onto a negative electrode current collector, followed by aging and drying. More specifically, the negative electrode paste used to manufacture unformed negative electrode plates is prepared, for example, by adding water and sulfuric acid (or an aqueous sulfuric acid solution) to lead powder, carbonaceous material, primary fatty acid, and various additives as needed (organic shrinkage inhibitors, barium sulfate, etc.), and kneading. During aging, it is preferable to age the unformed negative electrode plates at a temperature higher than room temperature and at high humidity. The negative electrode plates are manufactured, for example, by forming the unformed negative electrode plates.

[0094] The chemical conversion can be carried out, for example, by placing an electrode group including an unconverted negative electrode and an electrolyte containing sulfuric acid in the battery case of a lead-acid battery, and then charging the electrode group while the electrolyte has permeated the electrode group. However, the chemical conversion may also be carried out before the assembly of the lead-acid battery or the electrode group. Spongy lead is produced by the chemical conversion.

[0095] (Positive plate) Lead-acid battery positive electrodes are classified into paste-type, clad-type, and others. Either paste-type or clad-type positive electrodes may be used.

[0096] The positive electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead sheet or a lead alloy sheet. Examples of processing methods include expanding and punching. Using a grid-shaped current collector as the positive electrode current collector is preferable because it makes it easier to support the positive electrode material.

[0097] As the lead alloy used for the positive electrode current collector, Pb-Sb alloys, Pb-Ca alloys, and Pb-Ca-Sn (tin) alloys are preferred in terms of corrosion resistance and mechanical strength. The positive electrode current collector may have a surface layer. The surface layer and the inner layer of the positive electrode current collector may have different compositions. The surface layer may be formed to cover the entire positive electrode current collector, or it may be formed on only a part of the positive electrode current collector. The surface layer may be formed only on the grid portion, only on the lug portion, or only on the frame portion of the positive electrode current collector.

[0098] In a clad positive electrode plate, the positive electrode plate comprises multiple porous tubes, a core inserted into each tube, a current collector connecting the multiple cores, a positive electrode material filled into the tubes into which the cores are inserted, and a connecting seat connecting the multiple tubes. In a clad positive electrode plate, the positive electrode material is the portion of the electrode plate excluding the tubes, cores, current collector, and connecting seat. In a clad positive electrode plate, the cores and current collector typically constitute the positive electrode current collector.

[0099] The positive electrode material contains a positive electrode active material (lead dioxide or lead sulfate) that exhibits capacity through a redox reaction, and also contains antimony and resin fibers. The positive electrode material may also contain other additives as needed.

[0100] Antimony can significantly improve cycle life by suppressing the softening of the positive electrode material. However, when antimony is deposited from the positive electrode material to the negative electrode plate via the electrolyte, it lowers the hydrogen overpotential of the negative electrode plate, leading to increased overcharge. In contrast, when the primary fatty acid in the negative electrode material combines with antimony on the positive electrode plate via the electrolyte, the elution of antimony from the positive electrode material is significantly suppressed. As a result, not only is the effect of suppressing the softening of the positive electrode material enhanced, but the deposition of antimony on the negative electrode plate is also suppressed, greatly mitigating the disadvantages of antimony. Furthermore, the primary fatty acid in the negative electrode material also has the effect of suppressing the reduction and adhesion of antimony. Therefore, it is possible to obtain the effect of suppressing the softening of the positive electrode material by antimony while also reducing the amount of overcharge, thus significantly improving cycle life. The bulk density of the positive electrode material is 3.9 g / cm³. 3 If the value exceeds this, the positive electrode material will have a sufficiently strong structure. Therefore, there is little need to include antimony in the positive electrode material, and even if antimony is included, the range of softening suppression will be small.

[0101] The antimony content in the positive electrode material is preferably 0.5% by mass or less. If the positive electrode material contains more antimony than this, the effect of Sb saturates. From the viewpoint of highly suppressing the elution of antimony into the electrolyte, the antimony content in the positive electrode material is preferably 0.4% by mass or less, and more preferably 0.1% by mass or less. Furthermore, to enhance the effect of suppressing the softening of the positive electrode material, the antimony content in the positive electrode material is preferably 0.01% by mass or more, and from the viewpoint of significantly increasing the cycle life, 0.03% by mass or more is more desirable. These lower and upper limits can be combined arbitrarily.

[0102] The antimony content may be 0.01% by mass or more and less than 0.5% by mass, 0.01% by mass or more and 0.4% by mass or less, 0.01% by mass or more and 0.1% by mass or less, 0.03% by mass or more and less than 0.5% by mass, 0.03% by mass or more and 0.4% by mass or less, or 0.03% by mass or more and 0.1% by mass or less.

[0103] The quantitative analysis method for antimony is shown below. First, the positive electrode plate is removed from the lead-acid battery, and sulfuric acid is removed by washing with water within 480 minutes. The positive electrode plate is then dried by air at 60±5°C. Washing is continued until a pH test paper is pressed against the surface of the washed negative electrode plate and the color of the test paper does not change. Next, an appropriate amount of dry positive electrode material is taken from the positive electrode plate, and the mass of the sample is measured. Then, the entire sample is dissolved in a mixed aqueous solution containing tartaric acid, nitric acid, and hydrogen peroxide. Since the resin fibers do not dissolve at this time, they can be separated by filtration. Thus, the resin fiber content in the positive electrode material can be determined. The solution obtained by total dissolution is diluted with deionized water as needed to a fixed volume, and then the emission intensity of Sb in the solution is measured by ICP emission spectroscopy. Then, the mass of Sb contained in the solution is determined using a calibration curve prepared in advance. The ratio of this Sb mass to the mass of the positive electrode active material sample subjected to analysis is determined as the Sb content.

[0104] The average fiber diameter of the resin fibers may be, for example, 500 μm or less, but may also be between 1 μm and 100 μm, or between 1 μm and 30 μm. The average fiber length of the resin fibers may be, for example, between 1 mm and 15 mm. Such resin fibers maintain sufficiently high mechanical strength and have a sufficiently large specific surface area. Therefore, the effect of improving the durability of the positive electrode material by using resin fibers is very significant.

[0105] The material of the resin fiber may be at least one selected from the group consisting of, for example, polyester and polyolefin. Examples of polyester include polyalkylene arylates such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Examples of polyolefins include polyethylene, polypropylene, and ethylene-propylene copolymer. The resin fiber may contain one of these resins or two or more.

[0106] The resin fiber content in the positive electrode material is, for example, 0.01% by mass or more and 0.23% by mass or less, and may also be 0.05% by mass or more and 0.21% by mass or less.

[0107] The degree of adhesion of the resin fibers to the positive electrode material is 10% or more. If the degree of adhesion is less than 10%, it is difficult to sufficiently improve the durability of the positive electrode material. Here, the "degree of adhesion" is calculated as the ratio of the area Spam of the resin fibers coated with the positive electrode active material to the area Sf of the resin fibers (100 × Sf / Spam (%)).

[0108] The method for measuring the degree of binding is shown below. The lead-acid battery is disassembled and the positive electrode plate is removed. It is washed with water to remove sulfuric acid and dried at 60±5℃. After drying, the positive electrode material is crushed in a mortar and pestle, and resin fibers are removed from the crushed positive electrode material with tweezers. The removed resin fibers are imaged with an electron microscope to obtain an image. The outline of the resin fiber is determined in the image, and the area enclosed by the outline is calculated as Sf. Next, the ratio of the area covered by the positive electrode active material (Spam) within the region enclosed by the outline of the resin fiber is determined, and the ratio of Spam to Sf (100 × Sf / Spam (%)) is calculated. The same measurement and calculation are performed for 5 to 10 arbitrarily selected fibers, and the measured values ​​are obtained.

[0109] The bulk density of the positive electrode material is 3.9 g / cm³. 3 The following is acceptable, but 3.8 g / cm³ is not. 3 The following is also acceptable: 3.7 g / cm³ 3The following is also acceptable. The bulk density of the positive electrode material is, for example, 3.4 g / cm³. 3 It may be greater than or equal to 3.5 g / cm³. 3 That's fine too.

[0110] The density of the positive electrode material is 3.4 g / cm³. 3 (or 3.5 g / cm³) 3 or more)3.9g / cm 3 Below, 3.4g / cm 3 More than 3.8g / cm 3 Below, 3.4g / cm 3 (or 3.5 g / cm³) 3 or more)3.7g / cm 3 Below, 3.6g / cm 3 (or 3.65 g / cm³) 3 or more)3.8g / cm 3 The following is also acceptable.

[0111] The bulk density of the positive electrode material is measured as follows: A fully charged lead-acid battery is disassembled, and the electrolyte is removed from the positive electrode plate by washing and drying it. However, the washing time should be no more than 8 hours. The washed positive electrode plate is dried at 60±5℃. If the positive electrode plate contains adhesive material, remove it as necessary. Next, the positive electrode material is separated from the positive electrode plate to obtain an unground sample for measurement. The sample is placed in a measurement container, evacuated, and then filled with mercury at a pressure of 0.5 psia to 0.55 psia (≒ 3.45 kPa to 3.79 kPa) to measure the bulk volume of the positive electrode material. The bulk density of the positive electrode material is determined by dividing the mass of the measurement sample by the bulk volume. Note that the bulk volume is the volume of the measurement container minus the volume of mercury injected.

[0112] The density of the positive electrode material is measured using an automated porosimeter (Autopore IV9505) manufactured by Shimadzu Corporation.

[0113] Chemical treatment may be carried out by immersing the electrode plate group, including the untreated positive electrode plate, in the sulfuric acid-containing electrolyte in the lead-acid battery case and then charging the electrode plate group. However, chemical treatment may also be carried out before the assembly of the lead-acid battery or the electrode plate group.

[0114] (Separator) A separator may be placed between the negative electrode plate and the positive electrode plate. As the separator, at least one selected from nonwoven fabric and microporous membrane can be used.

[0115] Nonwoven fabric is a mat made by intertwining fibers without weaving, and is primarily composed of fibers. For example, a nonwoven fabric is formed of fibers by 60% or more by mass. As fibers, glass fibers, polymer fibers (polyolefin fibers, acrylic fibers, polyester fibers (polyethylene terephthalate fibers, etc.), etc.), pulp fibers, etc. may be used. Among these, glass fibers are preferred. Nonwoven fabric may also contain components other than fibers (for example, acid-resistant inorganic powders, polymers as binders, etc.).

[0116] On the other hand, a microporous membrane is a porous sheet mainly composed of materials other than fiber components. For example, it can be obtained by extruding a composition containing a pore-forming agent into a sheet, and then removing the pore-forming agent to form pores. Microporous membranes are preferably composed of acid-resistant materials, and microporous membranes mainly composed of polymer components are preferred. As polymer components, polyolefins (polyethylene, polypropylene, etc.) are preferred. As pore-forming agents, at least one selected from the group consisting of polymer powders and oils can be used.

[0117] The separator may be composed of, for example, only a nonwoven fabric, or only a microporous membrane. Furthermore, the separator may, as needed, be a laminate of a nonwoven fabric and a microporous membrane, a combination of different or the same type of material, or a combination of different or the same type of material with interlocking protrusions and indentations.

[0118] The separator may be in the form of a sheet or a bag. A single sheet-shaped separator may be placed between the positive and negative electrode plates. Alternatively, the electrodes may be sandwiched between a single folded sheet-shaped separator. In this case, the positive electrode plate sandwiched between the folded sheet-shaped separators and the negative electrode plate sandwiched between the folded sheet-shaped separators may be stacked on top of each other, or one of the positive and negative electrode plates may be sandwiched between the folded sheet-shaped separators and stacked on top of the other electrode plate. When a bag-shaped separator is used, the bag-shaped separator may contain either the positive electrode plate or the negative electrode plate.

[0119] (electrolyte) The electrolyte is an aqueous solution containing sulfuric acid, and may be gelled if necessary.

[0120] The electrolyte may optionally contain cations (e.g., metal cations) and / or anions (e.g., anions other than sulfate anions, such as phosphate ions). Examples of metal cations include at least one selected from the group consisting of Na ions, Li ions, Mg ions, and Al ions.

[0121] The density of the electrolyte in a fully charged lead-acid battery at 20°C is, for example, 1.20 g / cm³. 3 The above is 1.25 g / cm³. 3 The above is also acceptable. The density of the electrolyte at 20°C is 1.35 g / cm³. 3 The following is the value: 1.32 g / cm³ 3 The following is preferable:

[0122] The density of the electrolyte at 20°C is 1.20 g / cm³. 3 More than 1.35g / cm 3 Below, 1.20g / cm 3 More than 1.32g / cm 3 Below 1.25g / cm 3 More than 1.35g / cm 3 The following, or 1.25 g / cm³ 3 More than 1.32g / cm 3 The following is also acceptable.

[0123] Figure 1 shows the appearance of an example of a lead-acid battery according to one embodiment of the present invention. The lead-acid battery 1 comprises a battery case 12 that houses an electrode plate group 11 and an electrolyte (not shown). The battery case 12 is divided into multiple cell chambers 14 by a partition wall 13. Each cell chamber 14 houses one electrode plate group 11. The opening of the battery case 12 is closed with a lid 15 equipped with a negative electrode terminal 16 and a positive electrode terminal 17. The lid 15 is provided with a vent plug 18 for each cell chamber. When replenishing with water, the vent plug 18 is removed and the water is supplied. The vent plug 18 may also have a function of venting gas generated in the cell chamber 14 to the outside of the battery.

[0124] Each electrode plate group 11 is constructed by stacking multiple negative electrode plates 2 and positive electrode plates 3 via separators 4. Here, a bag-shaped separator 4 that houses the negative electrode plates 2 is shown, but the shape of the separator is not particularly limited. In the cell chamber 14 located at one end of the battery case 12, a negative electrode shelf 6 that connects multiple negative electrode plates 2 in parallel is connected to a through connector 8, and a positive electrode shelf 5 that connects multiple positive electrode plates 3 in parallel is connected to a positive electrode column 7. The positive electrode column 7 is connected to a positive electrode terminal 17 on the outside of the lid 15. In the cell chamber 14 located at the other end of the battery case 12, a negative electrode column 9 is connected to the negative electrode shelf 6, and a through connector 8 is connected to the positive electrode shelf 5. The negative electrode column 9 is connected to a negative electrode terminal 16 on the outside of 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.

[0125] The positive electrode shelf 5 is formed by welding together the tabs provided on the upper part of each positive electrode plate 3. The negative electrode shelf 6 is also formed by welding together the tabs provided on the upper part of each negative electrode plate 2.

[0126] [Examples] The present invention will be described below in detail based on examples and comparative examples, but the present invention is not limited to the following examples.

[0127] 《Lead acid batteries A1~A13, R1~R18》 (1) Preparation of lead-acid batteries (a) Fabrication of the negative electrode plate A negative electrode paste is obtained by mixing lead powder, barium sulfate, carbon black (primary carbonaceous material), a fatty acid or polymer compound (polypropylene glycol (PPG), Mn=2000) shown in Tables 1 and 2, and an organic shrinkage inhibitor (sodium ligninsulfonate) with an appropriate amount of sulfuric acid aqueous solution. At this time, the components are mixed so that the content of the fatty acid or polymer compound in the negative electrode material, as determined by the procedure described above, is as shown in Tables 1 and 2, and the content of barium sulfate is 0.6 mass%, the content of carbon black is 0.3 mass%, and the content of organic shrinkage inhibitor is 0.07 mass%. The negative electrode paste is filled into the mesh of an expanded grid made of Pb-Ca-Sn alloy, and aged and dried to obtain an unformed negative electrode plate. The specific surface area Sc and DBP oil absorption Y, as determined by the procedure described above, are shown in Tables 1 and 2.

[0128] (b) Fabrication of the positive electrode plate A positive electrode paste is obtained by mixing lead powder, an antimony compound (antimony trioxide), and resin fibers with an appropriate amount of sulfuric acid aqueous solution. At this time, the antimony content in the positive electrode material (solid content of the positive electrode paste), which is determined by the procedure described above, is as shown in Tables 1 and 2, and the resin fiber content is 0.1% by mass, thereby obtaining the positive electrode paste. The positive electrode paste is filled into the mesh of an expanded grid made of Pb-Ca-Sn alloy, and aged and dried to obtain an unformed positive electrode plate. As the resin fibers, acrylic resin fibers with an average fiber length of 6 mm and an average fiber diameter of 20 μm were used.

[0129] (c) Preparation of test batteries The test battery has a rated voltage of 2V and a rated 5-hour rate capacity of 32Ah. The test battery's electrode assembly consists of 7 positive plates and 7 negative plates. The negative plates are housed in a bag-shaped separator and stacked with the positive plates to form the electrode assembly. The electrode assembly is placed in a polypropylene battery case along with an electrolyte (sulfuric acid aqueous solution), and a chemical conversion is carried out within the case to produce a liquid-type lead-acid battery. The chemical conversion brought the lead-acid battery to a nearly fully charged state. The density of the electrolyte in the fully charged lead-acid battery at 20°C is 1.28 g / cm³.3 That was the case.

[0130] (2) Evaluation (a) Overcharge amount The above lead-acid battery will be used and the following conditions will be followed. To create overcharge conditions beyond the standard 4-minute-10-minute test specified in JIS D5301, a 1-minute discharge-10-minute charge test (1-minute-10-minute test) is performed at 75°C (high-temperature light-load test). The charge-discharge cycle is repeated 1220 times in the high-temperature light-load test. The amount of overcharge (charge amount - discharge amount) in each cycle up to 1220 is summed and averaged to determine the amount of overcharge (Ah) per cycle. The amount of overcharge is evaluated as a relative value, with the amount of overcharge (Ah) per cycle of lead-acid battery R1 set to 100%. A smaller value indicates less overcharge and less electrolyte loss. The results are shown in Tables 1 and 2. Discharge: 25A, 1 minute Charging: 2.47V / cell, 25A, 10 minutes Tank temperature: 75℃

[0131] (b) Cycle life (Shallow cycle) The above lead-acid battery will be used and the following conditions will be followed. In a 30°C water bath, the battery is repeatedly discharged for 12 minutes at a constant current of 32A and charged for 12.6 minutes at a constant current of 32A. The battery is considered to have reached the end of its lifespan when the terminal voltage at the end of discharge falls below 1.60V / cell, and the number of cycles at that point is calculated.

[0132] Table 1 shows the relative values ​​with the result for battery R1 set to 100%. A higher value indicates better cycle life. The results are shown in Tables 1 and 2.

[0133] (c) Capacity A lead-acid battery was placed in a water tank at 25±2°C and discharged from a fully charged state with a constant current of 6.4A. The amount of discharged electricity until the terminal voltage dropped to 10.5V was defined as the capacity (5-hour rate capacity).

[0134] (d) Amount of antimony precipitate The battery, after the cycle life test described above, will be analyzed under the following conditions. The lead-acid battery was disassembled, the negative electrode plate was removed, and sulfuric acid was removed by washing with water within 30 minutes. The negative electrode plate was then dried at 60±5°C under reduced pressure. Next, an appropriate amount of dried negative electrode material was taken from the negative electrode plate, and its mass was measured. Then, the entire sample was dissolved in an aqueous nitric acid solution. The solution obtained by complete dissolution was diluted to a fixed volume with deionized water as needed, and the emission intensity of Sb in the solution was measured by ICP emission spectroscopy. The mass of Sb contained in the solution was then determined using a pre-prepared calibration curve. The ratio of this Sb mass to the mass of the negative electrode active material sample subjected to analysis was determined as the amount of Sb precipitated (ppm). The results are shown in Tables 1 and 2.

[0135] [Table 1]

[0136] [Table 2]

[0137] Tables 1 and 2 show the values ​​of the ratio Cf / Sn and ratio Cf / Y. A1 to A13 are examples, and R1 to R18 are comparative examples.

[0138] In Tables 1 and 2, for R1 to R6, where PPG was used instead of the primary fatty acid as an additive, the bulk density of the positive electrode material was 3.9 g / cm³. 3 It can be understood that reducing the value to the following levels would prevent the suppression of Sb deposition, leading to increased overcharge and a shorter cycle life. Furthermore, R7 and R8 indicate that the bulk density of the positive electrode material is 3.9 g / cm³. 3 Beyond that point, it becomes clear that the battery capacity cannot be increased sufficiently.

[0139] On the other hand, A1 to A13 yielded high capacity, suppressed Sb deposition, low overcharge charge, and good cycle life. However, Cf / Sn ≥ 20 ppm·m -2The condition does not satisfy the requirement of 0.1 ppm·mL, and Cf / Y ≥ 0.1 ppm·mL -1 It can be understood that in R9, R14, and R15, which do not meet the 100g requirement, Sb deposition cannot be suppressed, leading to increased overcharge and a shorter cycle life. Furthermore, it can be understood that in R10 and above, when the number of carbon atoms in the first fatty acid is less than 8, Sb deposition cannot be suppressed, leading to increased overcharge and a shorter cycle life.

[0140] The bulk density of the positive electrode material is 4.1 g / cm³. 3 In R12, which is large and has a low degree of resin fiber bonding (less than 10), the capacity cannot be improved and the cycle life is insufficient. Furthermore, the bulk density of the positive electrode material is 3.6 g / cm³. 3 In R13, which is sufficiently small and has a low degree of resin fiber bonding (less than 10), the capacity can be improved, but the cycle life is insufficient.

[0141] Next, as shown in Table 2, the cycle life is insufficient for R17 and R18, which are positive electrode materials that do not contain Sb. On the other hand, it can be seen that the cycle life is significantly improved when the Sb content in the positive electrode material is increased to 0.1 mass%. [Industrial applicability]

[0142] The lead-acid battery described herein can be suitably used, for example, as a starting power source for vehicles (automobiles, motorcycles, etc.), a power source for auxiliary equipment in vehicles, and as a power source for industrial energy storage devices (e.g., for electric vehicles (forklifts, etc.)). However, these are merely examples, and the applications of the lead-acid battery are not limited to these. [Explanation of symbols]

[0143] 1:Lead acid battery 2: Negative plate 3: Positive plate 4: Separator 5: Positive electrode shelf 6: Negative electrode shelf 7: Positive pole column 8: Through-connector 9: Negative pole column 11: Plate group 12:Battery container 13: Bulkhead 14: Cell Room 15: Lid 16: Negative terminal 17: Positive terminal 18: Liquid outlet stopper

Claims

1. It includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, The positive electrode plate includes a positive electrode material, The aforementioned negative electrode plate includes a negative electrode material, The negative electrode material comprises a carbonaceous material and a fatty acid having 8 to 30 carbon atoms. The carbonaceous material content Cc in the negative electrode material is 0.25% by mass or more. When Y is the amount of DBP oil absorbed by the carbonaceous material, and Cf (ppm) is the mass-based content of the fatty acid in the negative electrode material, the Cf / Y ratio is 0.1 ppm·mL. －１ ・100g or more, The positive electrode material includes antimony and resin fibers. The degree of adhesion of the resin fibers to the positive electrode material is 10% or more. The bulk density of the aforementioned positive electrode material is 3.9 g / cm³. ３ The following is a lead-acid battery.

2. It includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, The positive electrode plate includes a positive electrode material, The aforementioned negative electrode plate includes a negative electrode material, The negative electrode material contains a fatty acid having 8 to 30 carbon atoms. The specific surface area of ​​the negative electrode material is Sn(m ２ ( / g), when the mass-based content of the fatty acid in the negative electrode material is Cf (ppm), the Cf / Sn ratio is 20 ppm·m －２ ・It is 1 g or more, The positive electrode material includes antimony and resin fibers. The degree of adhesion of the resin fibers to the positive electrode material is 10% or more. The bulk density of the aforementioned positive electrode material is 3.9 g / cm³. ３ The following is a lead-acid battery.

3. The lead-acid battery according to claim 1 or 2, wherein the fatty acid content Cf is 20 ppm or more and 600 ppm or less by mass.

4. The Cf / Sn ratio is 1000 ppm·m －２ A lead-acid battery according to claim 2, wherein the value is less than or equal to g.

5. The aforementioned negative electrode material further comprises a carbonaceous material, The lead-acid battery according to claim 2, wherein the carbonaceous material content Cc in the negative electrode material is 0.25% by mass or more.

6. The lead-acid battery according to claim 1 or 5, wherein the particle size of the carbonaceous material is less than 32 μm.

7. The lead-acid battery according to claim 1 or 5, wherein the carbonaceous material content Cc is 2% by mass or less.

8. When Y is the amount of DBP oil absorbed by the carbonaceous material, and Cf (ppm) is the mass-based content of the fatty acid in the negative electrode material, the Cf / Y ratio is 0.1 ppm·mL. －１ A lead-acid battery according to claim 5, wherein the weight is 100g or more.

9. The Cf / Y ratio is 2 ppm·mL. －１ A lead-acid battery according to claim 1 or 8, wherein the weight is 100g or less.

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