Lead-acid battery, power supply device, and method of using power supply device

Abstract

To provide a lead-acid battery in which deterioration of low-temperature high-rate performance is significantly suppressed when a charge / discharge cycle is repeated.SOLUTION: A lead-acid battery includes a cell, an electrolytic solution in which the cell is immersed, a container 10 that accommodates the cell and the electrolytic solution, a lid 12 that seals an opening of the container, and an auxiliary member that assists stirring of the electrolytic solution, wherein the cell includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, and the negative electrode plate includes a negative electrode current collector and a negative electrode material, and the negative electrode material includes an organic condensate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a lead-acid battery, a power supply device, and a method for using the power supply device. [Background technology]

[0002] Lead-acid batteries are used in a variety of applications, including automotive and industrial use. A lead-acid battery includes a negative electrode plate, a positive electrode plate, and an electrolyte. The negative electrode plate includes a current collector and a negative electrode material. An organic shrinkage preventer is added to the negative electrode material. As the organic shrinkage preventer, natural organic shrinkage preventers such as sodium lignosulfonate as well as synthetic organic shrinkage preventers are used (see Patent Document 1).

[0003] In lead-acid batteries, a stratification phenomenon occurs in which the concentration of the electrolyte in the upper part of the battery container (hereinafter also referred to as the upper electrolyte) becomes low and the concentration of the electrolyte in the lower part (hereinafter also referred to as the lower electrolyte) becomes high. When stratification occurs, the sulfuric acid specific gravity of the lower electrolyte increases, sulfation progresses below the negative electrode plate, and the low-temperature high-rate performance of the lead-acid battery deteriorates. Therefore, a common method of eliminating stratification is to overcharge the lead-acid battery to generate gas, which then causes the electrolyte to flow using the gas.

[0004] However, an increase in the amount of overcharge electricity not only accelerates corrosion of the positive electrode current collector, shortening the battery life, but also leads to increased frequency of replenishment due to a decrease in the water content of the electrolyte, and longer charging times.In addition, an increase in the amount of overcharge electricity also causes an increase in the temperature of the electrolyte, which accelerates the deterioration of the electrode plates.

[0005] Therefore, Patent Document 2 proposes an electrolyte stirring device characterized in that the cylindrical container has a liquid inlet near the bottom of the battery, a liquid outlet near the electrolyte surface, a gas inlet within the battery above the electrolyte surface, and a gas outlet at the top that is open to the atmosphere, and has an axis connecting two pistons at the top and bottom, the upper piston can move from above the gas inlet to above the gas outlet, and the lower piston has a valve that allows electrolyte to pass only from below to above the lower piston, and can move from above the liquid inlet to below the liquid outlet, and the cylindrical container is positioned between the electrode plate group and the inner wall of the battery case.

[0006] In addition, Patent Document 3 discloses a battery electrolyte mixing device for mixing a low specific gravity electrolyte of a battery with a high specific gravity electrolyte below, the mixing device having a support base that is installed so as to have a space separated from the inner wall surface of the battery case as a wall surface that protrudes upward; a bottom portion extending in one direction from the bottom surface to form a bottom surface; a bottom portion projecting upward from one side of the top surface of the bottom portion; a side portion extending along one side corner of the bottom; and a side portion projecting upward from the other upper surface of the bottom. and another side portion extending to a front side corner of the portion; and the one side portion and the other side portion are spaced apart from each other from their ends. the support base is installed to be spaced apart from the inner wall surface of the battery case, forming a vertical flow path so that the electrolyte flowing between the one side and the other side moves up and down by kinetic energy applied to the electrolyte.

[0007] Patent document 4 also discloses a mixing element (1) designed to be installed in the housing of an electrochemical accumulator operated by an electrolyte, in order to mix the electrolyte as a result of the force and / or movement applied to the accumulator during operation, the mixing element being designed as a hollow body provided with at least one opening in each of opposite end regions, and a channel communicating with the at least one opening in the opposite end regions being defined around the periphery by the material of the mixing element and formed in the hollow body, the mixing element having a protruding outer surface for fixing the mixing element in the accumulator, and / or The present invention proposes a mixing element characterized in that it has one or more mounting and / or spacer ribs designed to come into contact with parts of the accumulator housing in order to mount specific parts of the mixing element relative to said housing parts.

[0008] Furthermore, Patent Document 5 teaches an on-vehicle electrolyte agitator having a pump for supplying gas such as atmospheric air, an air header for storing the gas supplied from the pump, a hose extending from the air header to the vicinity of the bottom of the battery container via a liquid outlet plug, and a control unit for controlling the pump. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2013 / 150754 Brochure [Patent Document 2] Japanese Patent Application Publication No. 60-37651 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-232395 [Patent Document 4] Special Publication No. 2017-505506 [Patent Document 5] Japanese Patent Application Laid-Open No. 2016-177982 Summary of the Invention [Problem to be solved by the invention]

[0010] At the end of charging a lead-acid battery, power is consumed to generate gas, so for example, a fully charged state (SOC 100%) can be achieved by charging with power equivalent to about 110% of the rated capacity. After that, overcharging continues until the amount of charged electricity reaches about 120% of the rated capacity, stirring the electrolyte with gas. In other words, overcharging is usually performed by about 20%.

[0011] On the other hand, as in Patent Documents 2 and 3, lead-acid batteries equipped with a mechanism for stirring the electrolyte can omit overcharging to eliminate stratification, and therefore can reduce the amount of overcharge electricity by about 10% compared to lead-acid batteries without such a mechanism.

[0012] However, with repeated charge and discharge, the effect of stirring gradually saturates, and the progression of stratification can no longer be suppressed, resulting in a decline in low-temperature high-rate performance. For example, if a battery is discharged for three hours at a current (A) 0.25 times the rated capacity (Ah), and then charged to a state of charge (SOC) of 110% at a current (A) 0.18 times the rated capacity (Ah), the effect of stirring saturates after about 300 cycles, and low-temperature high-rate performance declines significantly after about 500 cycles. [Means for solving the problem]

[0013] One aspect of the present invention relates to a lead-acid battery comprising: a cell; an electrolyte in which the cell is immersed; a battery case that accommodates the cell and the electrolyte; a lid that seals an opening of the battery case; and an auxiliary member that assists in stirring the electrolyte, wherein the cell comprises a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, the negative electrode plate comprises a negative electrode current collector and a negative electrode material, and the negative electrode material includes an organic condensate. [Effects of the Invention]

[0014] According to the present invention, the deterioration of low-temperature high-rate performance is significantly suppressed when the lead-acid battery is repeatedly charged and discharged. [Brief explanation of the drawings]

[0015] [Figure 1] 1A is a front view, FIG. 1B is a top view, and FIG. 1C is a side view of an example of a lead-acid battery according to the present invention. [Figure 2] 2 is a cross-sectional view of the lead-acid battery of FIG. 1 taken along line II-II. [Figure 3] FIG. 2 is a front view schematically illustrating the appearance of an example of an air duct. [Figure 4] FIG. 1 is a conceptual diagram showing a part of an example of a battery pack in which a plurality of air ducts are connected. [Figure 5] 1 is a block diagram showing a configuration of an example of a power supply device according to the present invention; [Figure 6] 1A and 1B are a perspective view and a cross-sectional view, respectively, schematically illustrating an example of a rocking stirring device. [Figure 7] FIG. 2 is an explanatory diagram showing the principle of stirring an electrolyte solution by a rocking stirring device. [Figure 8] FIG. 1 is a graph showing the relationship between the low-temperature high-rate discharge performance and the number of charge-discharge cycles for batteries R1, R2, and E1 to E3. [Figure 9] FIG. 10 is a graph comparing the low-temperature high-rate discharge performance at the 500th cycle of batteries R1, R2, R3 to R5, and E1 to E3. [Figure 10] FIG. 1 is a graph showing the relationship between the content of an organic shrinkage preventer other than lignin contained in a negative electrode material and low-temperature high-rate discharge performance at the 500th cycle. [Figure 11] FIG. 1 is a graph showing the relationship between the content of an organic shrinkage preventer other than lignin contained in a negative electrode material and the initial capacity. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Lead acid battery] A lead-acid battery according to an embodiment of the present invention includes a cell, an electrolyte in which the cell is immersed, a battery case containing the cell and the electrolyte, a lid for sealing the opening of the battery case, and an auxiliary member for assisting in stirring the electrolyte. The cell includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive and negative electrode plates. The negative electrode plate includes a negative electrode current collector and a negative electrode material, which includes an organic condensation product as an organic shrinkage preventer. The organic shrinkage preventer is an organic compound that functions to suppress shrinkage of lead, the negative electrode active material, during repeated charge and discharge of a lead-acid battery. In addition to organic condensation preventers, organic shrinkage preventers also include lignin compounds. Organic condensation preventers are synthetic compounds that can be obtained using a condensation reaction and do not include lignin compounds. Note that lignin compounds commonly used in lead-acid batteries are natural materials and therefore excluded from the category of synthetic organic condensation preventers. Synthetic shrinkage preventers used in lead-acid batteries are typically organic condensation preventers.

[0017] When a lead-acid battery is equipped with an auxiliary member that assists in stirring the electrolyte, even when the overcharge quantity of electricity is reduced, it is possible to stir the electrolyte at a predetermined timing or constantly, for example, by inertial force due to the movement of the lead-acid battery. Therefore, in the early stages of charge / discharge cycles, stratification can be eliminated even if the overcharge quantity of electricity is reduced by about 10%. However, once the number of charge / discharge cycles exceeds 300, it becomes difficult to sufficiently stir the electrolyte, even when an auxiliary member that assists in stirring the electrolyte is provided. Therefore, reducing the overcharge quantity of electricity by about 10% reduces the low-temperature high-rate performance to the same extent as when the auxiliary member that assists in stirring the electrolyte is not provided and the overcharge quantity of electricity is not reduced. In other words, the benefits of using an auxiliary member that assists in stirring the electrolyte are greatly diminished.

[0018] Even when auxiliary components are used to assist electrolyte stirring, repeated charge-discharge cycles cause the negative electrode material to gradually expand, narrowing the gap between the positive and negative plates and reducing the electrolyte stirring efficiency. Therefore, although corrosion of the positive electrode current collector due to reduced overcharge electricity, reduction in water content in the electrolyte, and deterioration of the electrode plates due to increased electrolyte temperature can be suppressed, stratification progresses. As stratification progresses, it becomes difficult to adequately suppress the progression of sulfation at the bottom of the negative plate, which is thought to result in a decline in the low-temperature, high-rate performance of lead-acid batteries.

[0019] On the other hand, when the negative electrode material contains an organic condensation product, the organic condensation product acts as a shrinkage inhibitor and suppresses the expansion of the negative electrode material during charge / discharge cycles, so that the stirring efficiency of the electrolyte solution using the auxiliary member remains high and stratification is suppressed for a long period of time. This suppresses the progression of sulfation at the bottom of the negative electrode plate, significantly reduces the amount of lead sulfate accumulation, and makes it easier to break down lead sulfate that may accumulate on the negative electrode plate. For example, even when the charge / discharge cycle is repeated about 500 times, the deterioration of the low-temperature high-rate performance of the lead-acid battery is significantly suppressed. Specifically, when the battery is discharged for 3 hours at a current (A) 0.25 times the value of the rated capacity in Ah, and then charged to a state of charge (SOC) of 110% at a current (A) 0.18 times the value of the rated capacity in Ah, the effect of stirring the electrolyte by using auxiliary parts does not saturate even after about 500 cycles, and the low-temperature high-rate performance is well maintained.

[0020] The auxiliary member may be, for example, a ventilator that sends air to the electrolyte. The ventilator is preferably, for example, tubular and capable of sending air to the electrolyte from the bottom of the battery case. One end of the ventilator is installed near the lower end of the electrode plate assembly so as not to be close to the bottom of the battery case. This makes it possible to prevent sediment from being lifted up even if it has accumulated at the bottom of the battery case.

[0021] For example, at least one through-hole may be provided in the lid, and the air duct may be inserted into the through-hole. The through-hole may be a so-called liquid injection hole or gas vent hole, but to avoid complicating the structure, it is preferable to provide a dedicated through-hole for passing the air duct through, separate from the liquid injection hole or gas vent hole. The through-hole may be provided, for example, in at least one of the four corners of the lid, or in the center of a short side surface of the lid. One end of the air duct may be immersed in the electrolyte, and the other end may be connected to the outside of the lid via the through-hole. The other end may be connected to an air supply device that pressurizes and delivers air.

[0022] When a battery pack is made up of multiple lead-acid batteries, the air duct may be branched into multiple branches and connected to the multiple lead-acid batteries, making it possible to simultaneously circulate air through the multiple lead-acid batteries using a single air supply device.

[0023] A power supply device is constructed by combining a lead-acid battery equipped with an air duct with an air supply device that sends air to the air duct. The air supply device may be configured so that it can be connected to the air duct at any time, and may be configured so that it can be separated from the air supply device while the lead-acid battery is in use or discharging. The air supply device is not particularly limited, and a turbo or positive displacement pump or compressor can be used.

[0024] The power supply device may include a charger for charging the lead-acid battery. The timing for supplying air from the air duct into the electrolyte of the lead-acid battery is suitable when the lead-acid battery is being charged. By incorporating an air supply device in the charger, convenience is improved when supplying air into the electrolyte when the lead-acid battery is being charged. That is, a method for using the power supply device includes a step of operating the air supply device during or after charging the lead-acid battery with the charger to send air into the electrolyte through the air duct and agitate the electrolyte. Incidentally, incorporating an air supply device in the charger also has the advantage of allowing the power supply device to be configured compactly. Naturally, the air supply device does not necessarily need to be incorporated in the charger, and the power supply device may include the charger and the air supply device separately.

[0025] The auxiliary member may be an agitator that moves within the lead-acid battery to agitate the electrolyte. Such an agitator may have the function of agitating the electrolyte by moving in response to changes in the battery container without requiring the supply of power to operate the agitator. Hereinafter, an agitator that moves within the lead-acid battery to agitate the electrolyte will be referred to as a mixing element. The movement of the mixing element within the lead-acid battery may be relative to the electrolyte.

[0026] The mixing element usually has a structure that allows it to be housed in the battery case of the lead-acid battery together with the cells and the electrolyte. The mixing element is not particularly limited, and a known device can be used. The mixing element may be, for example, a device that can be easily moved depending on the inertial force applied to the lead-acid battery. Alternatively, the electrolyte is stirred by moving in response to changes in the pressure inside the battery container. Examples of such devices include those described in the already mentioned Patent Documents 2 to 4. That is, a piston-type stirring device that mixes the upper and lower electrolytes in response to changes in the pressure inside the battery container, or a swing-type stirring device that mixes the upper and lower electrolytes by the inertial force generated when the vehicle moves, may be used. The inertial force imparts movement energy to the electrolyte inside the battery container.

[0027] The lead-acid battery may be a flooded (vented) lead-acid battery. The configuration of the lead-acid battery according to this embodiment is particularly advantageous for tall lead-acid batteries (particularly lead-acid batteries for electric vehicles) that are prone to stratification. The height of the lead-acid battery for electric vehicles may be, for example, 280 mm or more, 320 mm or more, 350 mm or more, or 400 mm or more.

[0028] In this specification, the fully charged state of a flooded lead-acid battery is defined as the state defined in JIS D 5301:2006. More specifically, a lead-acid battery is fully charged when it is placed in a water tank at 25°C ± 2°C and charged at a current (A) that is 0.2 times the value in Ah listed as the rated capacity, until the terminal voltage during charging, measured every 15 minutes, or the electrolyte density converted to a temperature of 20°C, shows a constant value to three significant digits for three consecutive measurements. The value listed as the rated capacity is in Ah. The unit of current set based on the value listed as the rated capacity is A.

[0029] A fully charged lead-acid battery refers to a fully charged lead-acid battery that has already been formed. A lead-acid battery can be fully charged immediately after formation, or after some time has passed since formation. For example, a lead-acid battery that has been in use (preferably in the early stages of use) after formation can be fully charged. A battery in the early stages of use refers to a battery that has not been in use for very long and has hardly deteriorated.

[0030] Hereinafter, the lead-acid battery according to the embodiment of the present invention will be described in detail for each of its main components, but the present invention is not limited to the following embodiment.

[0031] (negative plate) The negative electrode plate includes a negative electrode current collector and a negative electrode material. The negative electrode material is the portion of the negative electrode plate excluding the negative electrode current collector. The negative electrode material includes an organic condensation product as an organic shrinkage preventer.

[0032] Note that a mat, pasting paper, or other member may be attached to the negative electrode plate. Such a member (attaching member) is used integrally with the negative electrode plate and is therefore included in the negative electrode plate. Furthermore, when the negative electrode plate includes an attaching member, the negative electrode material is the portion of the negative electrode plate excluding the negative electrode current collector and the attaching member. However, when an attaching member such as a mat is attached to the separator, the thickness of the attaching member is included in the thickness of the separator.

[0033] The negative electrode plate can be formed by applying or filling a negative electrode paste to a negative electrode current collector, aging and drying the paste to produce an unformed negative electrode plate, and then chemically forming the unformed negative electrode plate. The negative electrode paste is produced by adding water and sulfuric acid to lead powder, an organic shrinkage inhibitor, and various additives as needed, and kneading the mixture. During aging, the unformed negative electrode plate is preferably aged at a temperature higher than room temperature and at a high humidity.

[0034] The formation can be carried out by immersing an electrode plate assembly including unformed negative plates in an electrolyte containing sulfuric acid in a battery jar of a lead-acid battery and then charging the electrode plate assembly. However, the formation can also be carried out before assembling the lead-acid battery or the electrode plate assembly. The formation produces spongy lead.

[0035] (Negative electrode current collector) The negative electrode current collector has a frame portion having tabs and a lattice portion continuous with the frame portion. It has a number of square squares.

[0036] 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 and punching. Using a negative electrode grid as the negative electrode current collector is preferable because it makes it easier to support the negative electrode material.

[0037] The lead alloy used for the negative electrode current collector may be any of a Pb-Sb alloy, a Pb-Ca alloy, and a Pb-Ca-Sn 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, and the like. 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 on a part of the negative electrode current collector. The surface layer may be formed on an edge portion of the negative electrode current collector. The surface layer of the edge portion may contain Sn or an Sn alloy.

[0038] (Negative electrode material) The negative electrode material includes a negative electrode active material (lead or lead sulfate) that develops capacity through a redox reaction. The negative electrode material may also include a shrinkage inhibitor, a carbonaceous material, and / or other additives. Examples of additives include, but are not limited to, barium sulfate and fibers (e.g., resin fibers). The negative electrode active material in a charged state is spongy lead, and unformed negative plates are typically made using lead powder.

[0039] (organic shrinkage preventer) As already mentioned, the negative electrode material contains an organic condensate as an organic shrinkage inhibitor. The organic condensate may be synthesized by a known method, or a commercially available product may be used. The negative electrode material may contain one type of organic shrinkage inhibitor, or two or more types.

[0040] The negative electrode material may contain a lignin compound as an organic shrinkage preventer, but it is necessary to contain an organic condensate as an organic shrinkage preventer other than the lignin compound. When the negative electrode material contains an organic condensate, expansion of the negative electrode material during charge / discharge cycles is significantly suppressed, making it less likely that the flow of electrolyte between the positive and negative electrode plates will be impeded over a long period of time. As a result, the stirring efficiency of the electrolyte, which is achieved by using an auxiliary member, is maintained at a high level, and stratification is suppressed over a long period of time. This suppresses the progression of sulfation and the coarsening of lead sulfate crystals, and the low-temperature high-rate performance of the lead-acid battery is maintained satisfactorily, even after approximately 500 charge / discharge cycles, for example.

[0041] When gas is generated by overcharging, the gas is generated between the positive and negative electrodes. Therefore, while the agitation of the electrolyte is weaker than, for example, when air is supplied to the bottom of the electrolyte using an air supply device, the flow of the electrolyte between the positive and negative electrodes is relatively unimpeded. On the other hand, in lead-acid batteries that actively agitate the electrolyte using auxiliary members to assist in agitation of the electrolyte, it is difficult to ensure uniform gas flow between the positive and negative electrodes. Therefore, the expansion of the negative electrode material is thought to significantly affect the progression of stratification. In other words, the progression of stratification due to the expansion of the negative electrode material is a problem unique to lead-acid batteries that actively agitate the electrolyte using auxiliary members to assist in agitation of the electrolyte. The use of organic condensates (especially specific condensates) can effectively solve this problem.

[0042] Unlike naturally occurring lignin compounds, organic condensates are prone to form planar moieties in their molecules. Therefore, once eluted, the organic condensates are prone to adsorb to the lead contained in the negative electrode plate. The organic condensates adsorbed to the lead refine the structure of the spongy lead, improve the mechanical strength of the spongy lead, and improve the binding strength between the lead itself or between the negative electrode current collector and the negative electrode material, resulting in the negative electrode material. In contrast, lignin compounds have a complex three-dimensional network structure and are more likely to leach out of the negative electrode material than organic condensation products. Furthermore, lignin compounds are less adsorbent to lead contained in the negative electrode plate than organic condensation products. Therefore, it is difficult to achieve the effects of improving the binding strength and suppressing the expansion of the negative electrode material described above using lignin compounds.

[0043] Furthermore, when an organic condensation product is used, the amount of sediment generation is significantly reduced. In lead-acid batteries that are equipped with an auxiliary member to assist in stirring the electrolyte and actively stir the electrolyte, sediment is raised up as the electrolyte is stirred. In particular, when one end of the air duct is installed near the bottom of the battery case and air is supplied to the bottom of the electrolyte using an air supply device, the stirring power is significantly greater than when the electrolyte is stirred by generating gas through overcharging. It has been found that when a lignin compound is used as an organic shrinkage preventer, sediment generation is relatively high, and sediment raising becomes unexpectedly severe, resulting in sediment accumulation on the upper strap portion of the cell, making it very likely to cause an upper short circuit. Such an upper short circuit can also be considered a problem unique to lead-acid batteries that actively stir the electrolyte using an auxiliary member to assist in stirring the electrolyte. On the other hand, when an organic condensation product is used, the problem of such an upper short circuit is significantly reduced.

[0044] When a lead-acid battery is subjected to repeated deep discharge cycles, the negative electrode material expands and contracts repeatedly, gradually expanding overall and gradually falling off, forming sediment. The reason why the amount of sediment generated is reduced when an organic condensate is used is thought to be because the pore size of the negative electrode material is more easily maintained, which is effective in suppressing the expansion of the negative electrode material. On the other hand, when a lignin compound is used, the effect of suppressing the expansion of the negative electrode material is smaller, resulting in a greater amount of sediment generated.

[0045] Here, the lignin compound includes lignin as well as lignin derivatives. Lignin derivatives include compounds having a lignin-like three-dimensional structure. Examples of the lignin derivative include at least one selected from the group consisting of modified lignin, lignosulfonic acid, modified lignosulfonic acid, and salts thereof (alkali metal salts (such as sodium salts), magnesium salts, calcium salts, etc.).

[0046] An organic condensate (hereinafter simply referred to as a condensate) as an organic shrinkage preventer is a synthetic product, and is also generally referred to as a synthetic shrinkage preventer. The condensate may contain an aromatic compound unit (hereinafter also referred to as an aromatic compound unit). The aromatic compound unit refers to a unit derived from an aromatic compound incorporated into the condensate. In other words, the aromatic compound unit is a residue of an aromatic compound. The condensate may contain one type of aromatic compound unit or multiple types.

[0047] An example of a condensate is a condensate of an aromatic compound with an aldehyde compound. Such a condensate can be synthesized by reacting an aromatic compound with an aldehyde compound. Here, a condensate containing sulfur element can be obtained by reacting an aromatic compound with an aldehyde compound in the presence of a sulfite or by using an aromatic compound containing sulfur element (e.g., bisphenol S) as the aromatic compound. For example, the sulfur element content in the condensate can be adjusted by adjusting the amount of sulfite and / or the amount of the aromatic compound containing sulfur element. This method can also be used when using other raw materials. One or more aromatic compounds may be condensed to obtain a condensate. The aldehyde compound may be an aldehyde (e.g., formaldehyde) or a condensate of an aldehyde.

[0048] The aromatic compound may have a sulfur-containing group. The organic polymer may contain an aromatic ring and a sulfur element as a sulfur-containing group. The sulfur-containing group may be directly bonded to the aromatic ring of the aromatic compound, or may be bonded to the aromatic ring as an alkyl chain having a sulfur-containing group. Among the sulfur-containing groups, a sulfonic acid group or a sulfonyl group, which are stable, is preferred. The sulfonic acid group may exist in an acid form or in a salt form such as a sodium salt.

[0049] Sulfur-containing groups are functional groups with strong negative polarity. In electrolytes, these functional groups form stable bonds with water molecules, hydrogen ions, and hydrogen sulfate ions, and therefore tend to be unevenly distributed on the surface of the condensate. Because the functional groups unevenly distributed on the surface carry a charge, electrostatic repulsion occurs between condensate aggregates, limiting the aggregation of colloidal particles of the condensate and reducing the colloidal particle size. As a result, the pore size of the negative electrode material is thought to be small and the resistivity of the negative electrode material is likely to be reduced. In this regard, condensates containing aromatic compound units having sulfur-containing groups are thought to significantly refine the structure of spongy lead at the interface between lead molecules or between the current collector and the negative electrode material, thereby improving the mechanical strength of the spongy lead. For these reasons, condensates containing aromatic compound units having sulfur-containing groups are thought to be effective in suppressing the expansion of the negative electrode material.

[0050] Examples of aromatic rings that aromatic compounds have include benzene rings and naphthalene rings. When an aromatic compound has multiple aromatic rings, the multiple aromatic rings may be linked by a direct bond or a linking group (e.g., an alkylene group (including an alkylidene group), a sulfone group, etc.). Examples of such structures include bisarene structures (biphenyl, bisphenylalkane, bisphenylsulfone, etc.).

[0051] Examples of aromatic compounds include compounds having the above-mentioned aromatic ring and a functional group such as a hydroxy group or an amino group. The functional group such as a hydroxy group or an amino group may be directly bonded to the aromatic ring, or may be bonded as an alkyl chain having the functional group. The hydroxy group also includes a salt of the hydroxy group (-OMe). The amino group also includes a salt of the amino group (a salt with an anion). Examples of Me include alkali metals (Li, K, Na, etc.) and metals of Group 2 of the periodic table (Ca, Mg, etc.).

[0052] The hydroxy group of the aromatic compound is preferably a phenolic hydroxy group. In the condensation product of an aromatic compound having a phenolic hydroxy group with an aldehyde compound, the condensation occurs primarily at at least one of the ortho and para positions (particularly the ortho position) relative to the phenolic hydroxy group. On the other hand, in the condensation product of a monocyclic aromatic compound having an amino group with an aldehyde compound, the condensation occurs via the amino group. Therefore, when a monocyclic aromatic compound having a phenolic hydroxy group is used, the aromatic rings in the organic shrink-preventing agent molecule are less twisted than when a monocyclic aromatic compound having an amino group is used, making it easier to form a planar structure, which is thought to facilitate its action on lead. Furthermore, the phenolic hydroxy group makes it easier for the organic condensation product to be negatively charged compared to when an amino group is used, and therefore, it is easier to obtain high adsorption to lead.

[0053] On the other hand, when the organic condensate has a nitrogen atom-containing group such as an amino group, the organic condensate has a low negative chargeability. Therefore, the content of the nitrogen atom-containing group in the organic condensate is preferably low. The nitrogen atom content in the organic shrink-preventing agent is preferably 1% by mass or less, and may be 0.1% by mass or less.

[0054] The aromatic compound that is the basis of the aromatic compound unit may contain at least one selected from the group consisting of bisarene compounds and monocyclic compounds. In this case, even if the lead-acid battery experiences a temperature environment higher than room temperature, the low-temperature high-rate performance tends to be less likely to be impaired. Although the details of the mechanism are not clear, it is believed that the low-temperature high-rate performance is less likely to be impaired. This is thought to be because the amount of organic condensation product eluted from the negative electrode material into the electrolyte (aqueous sulfuric acid solution) at high temperatures decreases.

[0055] Examples of bisarene compounds include bisphenol compounds, hydroxybiphenyl compounds, and bisarene compounds having an amino group (such as bisarylalkane compounds having an amino group, bisarylsulfone compounds having an amino group, and biphenyl compounds having an amino group). Among these, bisphenol compounds are preferred.

[0056] Preferred bisphenol compounds include bisphenol A, bisphenol S, and bisphenol F. For example, the bisphenol compound may contain at least one selected from the group consisting of bisphenol A and bisphenol S. Among these, condensates containing bisphenol S units have sulfur-containing groups, which tend to reduce the colloidal particle size and make it easier to maintain a small pore size in the negative electrode material, thereby providing a greater effect in suppressing expansion of the negative electrode material. When the bisphenol compound contains both bisphenol A and bisphenol S, the molar ratio of bisphenol A to bisphenol S may be, for example, in the range of 1:9 to 9:1, and preferably in the range of 2:8 to 8:2.

[0057] The bisphenol compound may have a bisphenol skeleton, and the bisphenol skeleton may have a substituent. That is, bisphenol A may have a bisphenol A skeleton, and the skeleton may have a substituent. Bisphenol S may have a bisphenol S skeleton, and the skeleton may have a substituent.

[0058] Preferred monocyclic compounds include hydroxyarene compounds and aminoarene compounds, with hydroxyarene compounds being particularly preferred.

[0059] Examples of hydroxyarene compounds include hydroxynaphthalene compounds and phenol compounds. For example, it is preferable to use a phenolic compound, such as a phenolsulfonic acid compound (e.g., phenolsulfonic acid or its substitution product). Condensates containing phenolsulfonic acid compound units have a phenolic hydroxy group and a sulfonic acid group. Both the phenolic hydroxy group and the sulfonic acid group have strong negative polarity and high affinity with metals. In addition, phenolsulfonic acid facilitates the formation of a planar structure in the condensate. Therefore, condensates containing phenolsulfonic acid compound units are easily adsorbed to the negative electrode current collector, effectively enhancing the bonding strength between the negative electrode current collector and the negative electrode material. Furthermore, condensates containing phenolsulfonic acid compound units have low solubility in the electrolyte (sulfuric acid aqueous solution) and tend to remain in the negative electrode material even after repeated deep discharge cycles. Therefore, they are even more effective in suppressing the expansion of the negative electrode material. As already mentioned, the phenolic hydroxy group also includes a salt of the phenolic hydroxy group (-OMe).

[0060] Examples of the aminoarene compound include aminonaphthalene compounds and aniline compounds (aminobenzenesulfonic acid, alkylaminobenzenesulfonic acid, etc.).

[0061] The aromatic compound from which the aromatic compound unit is derived may contain both a bisarene compound and a monocyclic compound. In this case, the organic condensate has even lower solubility in the electrolyte (sulfuric acid aqueous solution), and most of it tends to remain in the negative electrode material even after deep discharge cycles. Therefore, the effect of suppressing expansion of the negative electrode material is even greater.

[0062] When the aromatic compound that is the source of the aromatic compound unit contains both a bisarene compound and a monocyclic compound, the molar ratio of the bisarene compound to the monocyclic compound may be, for example, in the range of 1:9 to 9:1, and preferably in the range of 2:8 to 8:2.

[0063] The sulfur element content of the organic condensate may be, for example, 2000 μmol / g or more, preferably 3000 μmol / g or more. In this case, the amount of sulfur-containing groups in the organic condensate is large, and the colloidal particle size of the organic condensate is likely to be small, thereby further suppressing the expansion of the negative electrode material. However, the organic condensate may also include one having a sulfur element content of less than 2000 μmol / g.

[0064] The sulfur element content in the organic shrink-preventing agent being X μmol / g means that the sulfur element content contained in 1 g of the organic shrink-preventing agent is X μmol.

[0065] The upper limit of the sulfur element content of the organic condensate is not particularly limited, but may be, for example, 9000 μmol / g or less, 8000 μmol / g or less, or 7000 μmol / g or less. These lower and upper limits can be combined in any desired manner.

[0066] The sulfur element content of the organic condensate may be, for example, 2000 μmol / g or more (or 3000 μmol / g or more) and 9000 μmol / g or less, 2000 μmol / g or more (or 3000 μmol / g or more) and 8000 μmol / g or less, or 2000 μmol / g or more (or 3000 μmol / g or more) and 7000 μmol / g or less.

[0067] The weight average molecular weight (Mw) of the organic condensate is, for example, preferably not less than 7000. The Mw of the organic condensate is, for example, not more than 100,000, and may be not more than 20,000.

[0068] In this specification, the Mw of the organic condensate or organic shrink-preventing agent is determined by GPC. The standard substance used to determine the Mw is sodium polystyrene sulfonate. Mw is measured using the following apparatus under the following conditions. GPC equipment: Build-up GPC system SD-8022 / DP-8020 / AS-8020 / CO-8020 / UV-8020 (Tosoh Corporation) Column: TSKgel G4000SWXL, G2000SWXL (7.8 mm I.D. x 30 cm) (Tosoh Corporation) Detector: UV detector, λ=210nm Eluent: A mixture of 1 mol / L NaCl aqueous solution and acetonitrile (volume ratio = 7:3) Flow rate: 1mL / min. Concentration: 10mg / mL Injection volume: 10μL Standard substance: Polystyrene sulfonate sodium (Mw = 275,000, 35,000, 12,500, 7,500, 5,200, 1,680)

[0069] When the negative electrode material contains a lignin compound in addition to the organic condensate, the sulfur element content of the lignin compound is, for example, 1000 μmol / g or less, and may be 800 μmol / g or less. The lower limit of the sulfur element content of the lignin compound is not particularly limited, but is, for example, 400 μmol / g or more.

[0070] The Mw of the lignin compound is, for example, less than 7000. The Mw of the lignin compound is, for example, 3000 or more.

[0071] When an organic condensate and a lignin compound are used in combination, the mass ratio thereof can be selected arbitrarily. However, from the viewpoint of significantly improving the binding strength between the negative electrode current collector and the negative electrode material, the ratio of the organic condensate to the total amount of the organic condensate and the lignin compound is preferably 20 mass% or more, or may be 50 mass% or more, or may be 80 mass% or more.

[0072] The higher the content of the organic shrinkage inhibitor in the negative electrode material, the more advantageous it is for maintaining the low-temperature high-rate performance of the lead-acid battery when repeated charge-discharge cycles are performed. However, if the content of the organic shrinkage inhibitor in the negative electrode material is excessively high, the initial capacity of the lead-acid battery tends to decrease. For these reasons, the content of the organic shrinkage inhibitor in the negative electrode material is, for example, 0.01% by mass or more, and may be 0.03% by mass or more. The content of the organic shrinkage inhibitor may be, for example, 0.5% by mass or less, and may be 0.3% by mass or less. These lower and upper limits can be combined in any desired manner.

[0073] The content of the organic shrinkage inhibitor in the negative electrode material may be 0.01% by mass or more and 0.5% by mass or less, 0.03% by mass or more and 0.5% by mass or less, 0.01% by mass or more and 0.3% by mass or less, or 0.03% by mass or more and 0.3% by mass or less.

[0074] (barium sulfate) The negative electrode material may contain barium sulfate. The content of barium sulfate in the negative electrode material is, for example, 0.05% by mass or more, and may be 0.10% by mass or more. The content of barium sulfate in the negative electrode material is 3% by mass or less, and may be 2% by mass or less. These lower and upper limits may be combined in any desired manner.

[0075] The content of barium sulfate in the negative electrode material may be 0.05% by mass to 3% by mass, 0.05% by mass to 2% by mass, 0.10% by mass to 3% by mass, or 0.10% by mass to 2% by mass.

[0076] (carbonaceous material) The negative electrode material may contain a carbonaceous material. Examples of the carbonaceous material that can be used include carbon black, graphite, hard carbon, and soft carbon. Examples of carbon black include acetylene black, furnace black, and lamp black. Furnace black also includes Ketjen Black (trade name). The graphite may be any carbonaceous material that contains a graphite-type crystalline structure, and may be either artificial graphite or natural graphite. One type of carbonaceous material may be used alone, or two or more types may be used in combination.

[0077] The content of the carbonaceous material in the negative electrode material is, for example, preferably 0.05% by mass or more, and may be 0.10% by mass or more. The content of the carbonaceous material is, for example, 5% by mass or less, and may be 3% by mass or less. These lower and upper limits can be combined arbitrarily.

[0078] The content of the carbonaceous material in the negative electrode material may be, for example, 0.05% by mass or more and 5% by mass or less, 0.05% by mass or more and 3% by mass or less, 0.10% by mass or more and 5% by mass or less, or 0.10% by mass or more and 3% by mass or less.

[0079] (Analysis of the components of negative electrode materials) The following describes a method for analyzing negative electrode materials or their constituents. Prior to analysis, a lead-acid battery is fully charged after chemical conversion and then disassembled to obtain the negative electrode plate to be analyzed. The obtained negative electrode plate is washed with water to remove sulfuric acid from the negative electrode plate. The washing is continued until a pH test paper is pressed against the washed surface of the negative electrode plate and no color change is confirmed. However, the washing time should be within two hours. The washed negative electrode plate is dried in a reduced pressure environment at 60±5°C for approximately six hours. After drying, if the negative electrode plate contains an adhesive material, the adhesive material is removed from the negative electrode plate by peeling. Next, the negative electrode material is separated from the negative electrode plate to obtain a sample (hereinafter referred to as Sample A). Sample A is crushed as necessary and used for analysis.

[0080] (1) Analysis of organic shrinkage inhibitors (1-1) Qualitative analysis of organic shrinkage inhibitors (or organic condensates) in negative electrode materials The crushed sample A is immersed in a 1 mol / L aqueous solution of sodium hydroxide (NaOH) to extract the organic shrink-regulating agent. Next, if the extract contains multiple organic shrink-regulating agents, the multiple organic shrink-regulating agents are separated from the extract. For each of the isolated organic shrink-regulating agents, insoluble components are removed by filtration, and the resulting solution is desalted, concentrated, and dried. Desalting is performed using a desalting column, by passing the solution through an ion exchange membrane, or by placing the solution in a dialysis tube and immersing it in distilled water. Drying this yields a powder sample of the organic shrink-regulating agent (hereinafter referred to as sample B).

[0081] The type of organic shrink-preventing agent is identified by combining information obtained from the infrared spectrum measured using sample B of the organic shrink-preventing agent obtained in this manner, the ultraviolet-visible absorption spectrum measured using an ultraviolet-visible spectrophotometer after diluting sample B with distilled water or the like, or the NMR spectrum of a solution obtained by dissolving sample B in a specified solvent such as heavy water.

[0082] When the extract contains a plurality of organic shrink-preventing agents, they are separated as follows.

[0083] First, the extract is analyzed by at least one of infrared spectroscopy, NMR, and GC-MS to determine whether it contains multiple organic shrink-preventing agents. Next, the extract is analyzed by GPC to measure the molecular weight distribution. If the multiple organic shrink-preventing agents can be separated by molecular weight, the organic shrink-preventing agents are separated by column chromatography based on their molecular weight differences.

[0084] Organic shrink-regulating agents differ in solubility if they differ in at least one of the type and amount of functional groups. When it is difficult to separate organic shrink-regulating agents due to differences in molecular weight, this difference in solubility can be exploited to separate one of the organic shrink-regulating agents by precipitation separation. For example, when two organic shrink-regulating agents are contained, the extract is dissolved in aqueous NaOH solution, and then a sulfuric acid solution is added dropwise to the mixture to adjust the pH of the mixture, thereby flocculating and separating one of the organic shrink-regulating agents. When separation by flocculation is difficult, the organic shrink-regulating agent can be separated by ion exchange chromatography or affinity chromatography, exploiting the difference in at least one of the type and amount of functional groups. The separated material is then redissolved in aqueous NaOH solution, and the insoluble components are removed by filtration as described above. Furthermore, the remaining solution after separating one of the organic shrink-regulating agents is concentrated. The resulting concentrate contains the other organic shrink-regulating agent, and the insoluble components are removed from this concentrate by filtration as described above.

[0085] (1-2) Quantitative determination of the content of organic shrinkage inhibitor in negative electrode material As in (1-1) above, for each of the separated products containing the organic shrinkage inhibitor, insoluble components are removed by filtration to obtain a solution. The ultraviolet-visible absorption spectrum of each of the obtained solutions is measured. The content of each organic shrinkage inhibitor in the negative electrode material is determined using the intensity of the peak characteristic of each organic shrinkage inhibitor and a previously prepared calibration curve.

[0086] When obtaining a lead-acid battery with an unknown content of organic shrinkage inhibitor and measuring the content of the organic shrinkage inhibitor, it may be impossible to precisely identify the structural formula of the organic shrinkage inhibitor, and therefore it may not be possible to use the same organic shrinkage inhibitor for the calibration curve. In such cases, a calibration curve is created using a separately available organic polymer that shows similar shapes in the ultraviolet-visible absorption spectrum, infrared spectroscopy spectrum, NMR spectrum, etc. to the organic shrinkage inhibitor extracted from the negative electrode of the battery, and the content of the organic shrinkage inhibitor is measured using the ultraviolet-visible absorption spectrum.

[0087] (1-3) Sulfur content in organic shrinkage inhibitors As in (1-1) above, after obtaining sample B of the organic shrink-proofing agent, the sulfur element in 0.1 g of the organic shrink-proofing agent is converted to sulfuric acid using the oxygen combustion flask method. Sample B is then burned in a flask containing an adsorption solution, yielding an eluate in which sulfate ions have dissolved in the adsorption solution. The sulfur element content (C1) in 0.1 g of the organic shrink-proofing agent is then determined by titrating the eluate with barium perchlorate using thorin as an indicator. Next, C1 is multiplied by 10 to calculate the sulfur element content (μmol / g) per gram of the organic shrink-proofing agent.

[0088] (1-4) Analysis of nitrogen element content in organic shrinkage preventers As in the above (1-1), after obtaining sample B of the organic shrink-preventing agent, sample B is analyzed using an organic elemental analyzer (CHN analyzer) to determine the nitrogen atom content in the organic shrink-preventing agent.

[0089] (2) Quantitative analysis of carbonaceous materials and barium sulfate 50 ml of 20% nitric acid by mass was added to 10 g of the crushed sample A, and the mixture was heated for approximately 20 minutes to dissolve the lead component as lead nitrate. Next, the solution containing lead nitrate was filtered to separate out the solid components such as carbonaceous materials and barium sulfate.

[0090] The obtained solid content is dispersed in water to form a dispersion, and then components other than the carbonaceous material and barium sulfate (e.g., reinforcing material) are removed from the dispersion using a sieve. Next, the dispersion is subjected to suction filtration using a membrane filter whose mass has been measured in advance, and the membrane filter together with the filtered sample is dried in a dryer at 110°C ± 5°C. The obtained sample is a mixed sample of the carbonaceous material and barium sulfate (hereinafter referred to as Sample C). The mass of the membrane filter is subtracted from the total mass of Sample C and the membrane filter after drying to determine the mass of Sample C (M m ) is measured. After that, the dried sample C is placed in a crucible together with the membrane filter and burnt at 700°C or higher to be incinerated. The remaining residue is barium oxide. The mass of barium oxide is converted to the mass of barium sulfate to determine the mass of barium sulfate (M B ) to find the mass M m to mass MB The mass of the carbonaceous material is calculated by subtracting the above.

[0091] (positive electrode plate) Positive electrode plates for lead-acid batteries can be classified into paste-type and clad-type. Paste-type positive electrode plates include a positive electrode collector and a positive electrode material. The positive electrode material is held by the positive electrode collector. In a paste-type positive electrode plate, the positive electrode material is the portion of the positive electrode plate excluding the positive electrode collector. The positive electrode 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. A lattice-shaped current collector is preferred as the positive electrode collector because it facilitates the support of the positive electrode material. A clad-type positive electrode plate includes multiple porous tubes, cores inserted into each tube, a current collector connecting the multiple cores, positive electrode material filled in the tubes with the cores inserted, and a connecting seat connecting the multiple tubes. In a clad-type positive electrode plate, the positive electrode material is the positive electrode plate excluding the tube, the core metal, the current collector, and the connecting seat. In a clad-type positive electrode plate, the core metal and the current collector are sometimes collectively referred to as the positive electrode current collector.

[0092] A positive electrode plate may have a mat, pasting paper, or other material attached to it. Such materials (attaching materials) are used integrally with the positive electrode plate and are therefore considered to be included in the positive electrode plate. Furthermore, when the positive electrode plate includes such materials, the positive electrode material, in the case of a paste-type positive electrode plate, is the portion of the positive electrode plate excluding the positive electrode current collector and the adhesive material.

[0093] The lead alloy used for the positive electrode current collector is preferably a Pb-Sb alloy, a Pb-Ca alloy, or a Pb-Ca-Sn alloy 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 on a part of the positive electrode current collector, such as only the grid portion, only the edge portion, or only the frame portion of the positive electrode current collector.

[0094] The positive electrode material contained in the positive electrode plate includes a positive electrode active material (lead dioxide or lead sulfate) that generates capacity through an oxidation-reduction reaction. The positive electrode material may also contain other additives as needed.

[0095] Unformed paste-type positive plates are obtained by filling a positive current collector with positive electrode paste, aging it, and drying it. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid. Unformed clad-type positive plates are formed by filling porous tubes with lead powder or lead powder slurry, into which core metals connected by current collectors are inserted, and then connecting multiple tubes with a connecting rod. These unformed positive plates are then chemically formed to obtain positive plates. Chemical formation can be performed by charging a plate group including unformed positive plates while immersing them in an electrolyte containing sulfuric acid in a lead-acid battery container. However, chemical formation may also be performed before assembling the lead-acid battery or plate group.

[0096] The formation can be performed by immersing an electrode plate assembly including unformed positive electrode plates in an electrolyte containing sulfuric acid in a battery container of a lead-acid battery and charging the electrode plate assembly, but the formation may also be performed before assembling the lead-acid battery or the electrode plate assembly.

[0097] (separator) A separator can be disposed between the negative electrode plate and the positive electrode plate. The separator can be at least one selected from a nonwoven fabric and a microporous membrane. The thickness of the separator disposed between the negative electrode plate and the positive electrode plate can be selected according to the distance between the electrodes. The number of separators can be selected according to the number of gaps between the electrodes.

[0098] A nonwoven fabric is a mat of intertwined fibers without being woven, and is primarily composed of fibers. For example, 60% by mass or more of the nonwoven fabric is made of fibers. Examples of fibers that can be used include glass fibers, polymer fibers (polyolefin fibers, acrylic fibers, polyester fibers (polyethylene terephthalate fibers, etc.)), and pulp fibers. Of these, glass fibers are preferred. The nonwoven fabric may contain components other than fibers, such as acid-resistant inorganic powders and polymers as binders.

[0099] On the other hand, a microporous membrane is a porous sheet mainly composed of components other than fiber components, and can be obtained, for example, by extruding a composition containing a pore-forming agent (such as a polymer powder and / or oil) into a sheet, and then removing the pore-forming agent to form pores. Microporous membranes are preferably made of an acid-resistant material, and are preferably made mainly of a polymer component. The polymer component is preferably a polyolefin (such as polyethylene or polypropylene).

[0100] The separator may be made of, for example, only a nonwoven fabric or only a microporous membrane. Furthermore, the separator may be a laminate of a nonwoven fabric and a microporous membrane, a laminate of different or the same materials, or a laminate of different or the same materials with recesses and protrusions interlocked, as needed.

[0101] The separator may be in a sheet form or may be formed in a bag form. A single sheet-like separator may be sandwiched between the positive electrode plate and the negative electrode plate. Alternatively, the electrode plates may be sandwiched between a single folded sheet-like separator. In this case, a positive electrode plate sandwiched between folded sheet-like separators and a negative electrode plate sandwiched between folded sheet-like separators may be stacked, or one of the positive electrode plate and the negative electrode plate may be folded to form a sheet-like separator. The separator may be sandwiched between two plates and then overlapped with the other plate. Alternatively, a sheet-like separator may be folded into an accordion shape, and the positive and negative plates may be sandwiched between the separators so that the separator is interposed between them. When a separator folded into an accordion shape is used, the separator may be arranged so that the folded portions are aligned with the horizontal direction of the lead-acid battery (e.g., parallel to the horizontal direction) or aligned with the vertical direction (e.g., parallel to the vertical direction). In a separator folded into an accordion shape, recesses are formed alternately on both main surfaces of the separator. Since the positive and negative plates usually have lugs on their tops, when the separator is arranged so that the folded portions are aligned with the horizontal direction of the lead-acid battery, the positive and negative plates are positioned in the recesses on only one main surface of the separator (i.e., a double separator is interposed between adjacent positive and negative plates). When the separator is arranged so that the folded portion is aligned with the vertical direction of the lead-acid battery, the positive electrode plate can be accommodated in the recess on one main surface side, and the negative electrode plate can be accommodated in the recess on the other main surface side (that is, a single separator can be interposed between adjacent positive and negative electrode plates.) When a pouch-shaped separator is used, the pouch-shaped separator may accommodate either the positive electrode plate or the negative electrode plate.

[0102] In this specification, the up-down direction of the electrode plate means the up-down direction in the vertical direction of the lead-acid battery.

[0103] (electrolyte) The electrolyte is an aqueous solution containing sulfuric acid, which may be gelled as necessary. The electrolyte may contain at least one selected from the group consisting of cations (e.g., metal cations) and anions (e.g., anions other than sulfate anions (e.g., phosphate ions)). Examples of metal cations include at least one selected from the group consisting of sodium ions, lithium ions, magnesium ions, and aluminum ions.

[0104] The specific gravity of the electrolyte at 20°C in a fully charged lead-acid battery is, for example, 1.20 or more, and may be 1.25 or more. The specific gravity of the electrolyte at 20°C is 1.35 or less, and preferably 1.32 or less. These lower and upper limits can be combined arbitrarily. The specific gravity of the electrolyte at 20°C may be 1.20 or more and 1.35 or less, 1.20 or more and 1.32 or less, 1.25 or more and 1.35 or less, or 1.25 or more and 1.32 or less.

[0105] A lead-acid battery can be obtained by a manufacturing method including a step of assembling a lead-acid battery by placing a positive electrode plate, a negative electrode plate, and an electrolyte in a battery case. In the step of assembling a lead-acid battery, a separator is usually disposed between the positive electrode plate and the negative electrode plate. The step of assembling a lead-acid battery may include a step of chemically converting at least one of the positive electrode plate and the negative electrode plate, if necessary, after the step of placing the positive electrode plate, the negative electrode plate, and the electrolyte in the battery case. The positive electrode plate, the negative electrode plate, the electrolyte, and the separator are each prepared before being placed in the battery case.

[0106] Fig. 1 shows a front view (a), a top view (b), and a side view (c) of an example of a lead-acid battery according to the present invention, and Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1(a).

[0107] The lead-acid battery 1 includes a plate pack 11, an electrolyte (not shown), a battery case 10 that accommodates these, and a lid 12 that closes the opening of the battery case 10. The plate pack 11 is formed by stacking a plurality of negative electrode plates 2 and positive electrode plates 3 with separators 4 interposed between them. A through-hole is provided in one of the four corners of the lid, and an air duct 13 is inserted into the through-hole.

[0108] Each of the negative electrode plates 2 has a current collecting lug (not shown) protruding upward from the top thereof. The lugs of the negative electrode plates 2 are connected and integrated by a negative electrode strap 5a. Similarly, the upper portions of the multiple positive electrode plates 3 are each provided with a current collecting lug (not shown) that protrudes upward, and the lugs of the positive electrode plates 3 are connected and integrated by a positive electrode strap 5b. A negative electrode pole 6a is fixed to the negative electrode strap 5a, and a positive electrode pole 6b is fixed to the positive electrode strap 5b.

[0109] FIG. 3 shows a schematic view of an example of an air duct. The air duct 13 is composed of an air duct 131 and a connector 132. The air duct 131 has a lower end 131a disposed at the bottom of the battery case 10 and an upper end 131b connected to the connector 132. The connector 132 has a cylindrical insertion portion 132a inserted into a through-hole provided in the lid 12 and a T-shaped portion 132b disposed entirely outside the lid 12. The upper end 131b of the air duct 131 is inserted and connected to the insertion portion 132a. As shown in FIG. 1, the T-shaped portion 132b is connected to the air supply device 14 via another air duct. When a battery pack is constructed using multiple lead-acid batteries 1, multiple air ducts 13 are connected using the T-shaped portions 132b, as shown in FIG. 4.

[0110] Figure 5 is a block diagram showing the configuration of an example of a power supply device according to the present invention. Power supply device 100 includes a charger 15 that charges a lead-acid battery. Air supply device 14 is mounted on charger 15 and is configured integrally with charger 15. In power supply device 100, air supply device 14 is operated during or after charging of the lead-acid battery with charger 15, and air is sent into the electrolyte via air duct 13, stirring the electrolyte.

[0111] Next, a case where the auxiliary member is a mixing element will be described with reference to Figures 6 and 7. Figure 6 is a perspective view (a) and a cross-sectional view (b) showing an example of a rocking stirrer. Figure 7 is an explanatory diagram showing the principle of stirring the electrolyte solution using a rocking stirrer.

[0112] The agitator 16 has a hollow structure as a whole, with an upper opening 16a and a lower opening 16b at the upper and lower ends in the vertical direction, respectively. The cross-sectional area S of the hollow, perpendicular to the vertical direction, decreases from top to bottom, with the cross-sectional area S being larger at the top of the agitator 16 and smaller at the bottom. The upper opening 16a opens wide vertically upward.

[0113] The upper opening 16a is positioned above the liquid level of the electrolyte. When the electrolyte is not subjected to inertial force, the liquid level inside the upper opening 16a is at the same level as the liquid level in the battery case 10, as shown in FIG. 7(a). When an inertial force acts on the electrolyte and the lower part of the agitator 16 is tilted to the left at a predetermined angle, as shown in FIG. 7(b), the liquid level inside the upper opening 16a becomes lower than the liquid level in the battery case 10. That is, the agitator 16 moves relative to the electrolyte. At this time, the electrolyte remaining at the bottom of the battery case flows into the agitator 16 through the lower opening 16b of the agitator 16 and moves upward. Next, when the lower part of the agitator 16 is tilted to the right at a predetermined angle, as shown in FIG. 7(c), the liquid level inside the upper opening 16a becomes higher than the liquid level in the battery case 10. At this time, the agitator 16 also moves relative to the electrolyte. Therefore, the electrolyte in the agitator 16 flows out from the lower opening 16b to the bottom of the battery case, and the electrolyte is agitated. Note that, for example, when a lead-acid battery is mounted on a vehicle, the inertial force is generated spontaneously as the vehicle moves, and there is no need to supply power in order to generate the inertial force.

[0114] The lead-acid battery according to the present invention will be summarized below. (1) A cell, an electrolyte in which the cell is immersed, a battery case that accommodates the cell and the electrolyte, a lid that seals the opening of the battery case, and an auxiliary member that assists in stirring the electrolyte; Equipped with The cell includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, the negative electrode plate comprises a negative electrode current collector and a negative electrode material, The lead-acid battery, wherein the negative electrode material comprises an organic condensation product.

[0115] (2) In the above (1), the lead acid battery according to claim 1, wherein the content of the organic condensate in the negative electrode material is 0.03 mass % or more and 0.3 mass % or less.

[0116] (3) In the above (1) or (2), the organic condensate contains an aromatic compound unit, The aromatic compound has a sulfur-containing group.

[0117] (4) In the lead-acid battery described above in (3), the aromatic compound includes at least one selected from the group consisting of bisarene compounds and monocyclic compounds.

[0118] (5) In the lead-acid battery described above in (4), the aromatic compound includes both a bisarene compound and a monocyclic compound.

[0119] (6) In the lead-acid battery described in (4) or (5) above, the bisarene compound includes a bisphenol compound.

[0120] (7) In the lead-acid battery described above in (6), the bisphenol compound includes at least one selected from the group consisting of bisphenol A and bisphenol S.

[0121] (8) The lead-acid battery according to any one of the above (4) to (7), wherein the monocyclic compound includes a hydroxyarene compound.

[0122] (9) In the lead-acid battery described above in (8), the hydroxyarene compound includes a phenolsulfonic acid compound.

[0123] (10) The lead-acid battery according to any one of the above (1) to (9), wherein the organic condensate has a sulfur element content of 2000 μmol / g or more.

[0124] (11) The lead-acid battery according to any one of the above (1) to (10), wherein the auxiliary member is an air pipe for sending air to the electrolyte.

[0125] (12) In the above (11), a through hole is provided in the lid, The air duct is inserted into the through hole, one end of the air duct is immersed in the electrolyte, and the other end of the air duct communicates with the outside of the lid.

[0126] (13) A power supply device comprising the lead-acid battery according to (11) or (12) above and an air supply device that sends air to the air duct.

[0127] (14) In the above (13), further comprising a charger for charging the lead-acid battery, The power supply device, wherein the air supply device is mounted on the charger.

[0128] (15) The lead-acid battery according to any one of the above (1) to (11), wherein the auxiliary member is an agitator that moves within the lead-acid battery to agitate the electrolyte.

[0129] (16) A method of using the power supply device according to (14) above, and operating the air supply device to supply air into the electrolyte through the air pipe during or after charging the lead-acid battery with the charger, thereby agitating the electrolyte.

[0130] [Example] The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0131] Lead-acid battery R1 (a) Preparation of the negative electrode plate The raw materials, lead powder, barium sulfate, carbon black, and the organic shrinkage preventer sodium lignosulfonate (sulfur element content: 600 μmol / g, Mw=5500) were mixed with an appropriate amount of sulfuric acid aqueous solution to obtain a negative electrode paste. The components were mixed so that the negative electrode material contained 1.5% by weight of barium sulfate, 0.3% by weight of carbon black, and 0.1% by weight of the organic shrinkage preventer, all of which were determined using the previously described procedures. The negative electrode paste was then filled into the mesh area of ​​a cast grid made of a Pb-Sb alloy, which served as a negative electrode current collector, and the resulting mixture was aged and dried to obtain an unformed negative electrode plate.

[0132] (b) Preparation of the positive electrode plate The clad type positive electrode plate is produced by the following procedure. First, multiple mandrels, each with one longitudinal end integrated with a current collector having a lug, are housed in multiple tubes. The current collector and the longitudinal end of the tube on the current collector side are covered with resin so that the lug is exposed, forming a resin upper connecting seat. The mandrels and current collector are made of a Pb-Sb alloy. A porous tube made of glass fiber is used as the tube.

[0133] A positive electrode slurry prepared by kneading lead powder (containing 80% by mass of lead oxide and 20% by mass of metallic lead), red lead, water, and dilute sulfuric acid is filled into the opening at the other end of the tube in the longitudinal direction. The mass ratio of lead powder to red lead is 8:2. The opening at the other end of the tube is then sealed with a lower connecting member and allowed to dry. In this way, an unformed clad positive electrode plate is produced.

[0134] (c) Preparation of test battery A liquid-type battery with a rated voltage of 2V and a rated 5-hour rate capacity of 165Ah was fabricated. The test battery's plate assembly consisted of three positive plates sandwiched between four negative plates. The positive and negative plates were stacked with a glass fiber nonwoven separator between them to form a plate assembly. The plate assembly was placed in a polyethylene container together with an electrolyte (aqueous sulfuric acid solution), and the container was closed and subjected to chemical formation to fabricate a liquid-type lead-acid battery R1. The specific gravity of the electrolyte after chemical formation at 20°C was 1.28. The battery height was 426mm (height from the bottom of the container to the liquid surface: 338mm), and the volume of the electrolyte was 1700mL. Lead-acid battery R1 was a comparative example.

[0135] [Rating 1] The charge / discharge cycle of the lead-acid battery is repeated at a temperature of 30°C ± 0.5°C under the following conditions specified in JIS D5303. Discharge: Discharge for 3 hours at a current (A) of 0.25 times the Ah value listed as the rated capacity. Charging: Charge 110% of the discharged amount of electricity at a current (A) that is 0.18 times the Ah value listed as the rated capacity.

[0136] During the above charge-discharge cycles, the low-temperature high-rate discharge performance is measured every 100 cycles. After fully charging, the test battery was discharged at a current of 165A at -15°C until the terminal voltage reached 1.0V / cell. The battery is discharged until it reaches this temperature, and the discharge time at this point is calculated. The longer the discharge duration, the better the low-temperature high-rate discharge performance. The low-temperature high-rate discharge performance (referred to as LTHR performance in the table) of each battery is evaluated as a percentage of the initial discharge duration (after one cycle) of lead-acid battery R1, taken as 100.

[0137] 《Lead acid battery R2》 A 5 mm diameter air duct was prepared as shown in Figure 3. A through hole was drilled in one corner of the lid of a battery fabricated in the same manner as battery R1, and the air duct was attached to the through hole so that the lower end of the air duct reached near the bottom of the battery case, creating battery R2. During charging, air was supplied from a compressor to the air duct, and the air was circulated from the lower end of the air duct into the electrolyte at a flow rate of 350 mL / min. Battery R2 was evaluated in the same manner as battery R1. Lead-acid battery R2 is a comparative example.

[0138] 《Lead acid battery R3~R5》 Batteries R3 to R5 were fabricated in the same manner as battery R1, except that the following organic shrinkage inhibitor was used instead of sodium lignosulfonate, and were evaluated in the same manner. Lead-acid batteries R3 to R5 are comparative batteries. Battery R3 uses condensate A, R4 uses condensate B, and R5 uses condensate C.

[0139] Condensate A: Condensate of a sulfonic acid group-introduced bisphenol A compound and a bisphenol S compound with formaldehyde (sulfur element content: 4000 μmol / g, Mw=9000)

[0140] Condensate B: Condensate of bisphenol S compound and phenolsulfonic acid with formaldehyde (sulfur element content: 4000 μmol / g, Mw=8000)

[0141] Condensate C: Condensate of a sulfonic acid group-introduced bisphenol A compound and phenolsulfonic acid with formaldehyde (sulfur element content: 4000 μmol / g, Mw=8000)

[0142] 《Lead acid batteries E1~E3》 Batteries E1 to E3 were fabricated in the same manner as battery R2, except that the above-mentioned condensates A, B, and C were used instead of sodium lignosulfonate, and were evaluated in the same manner. Lead-acid batteries E1 to E3 are batteries of the example. Battery E1 uses condensate A, E2 uses condensate B, and E3 uses condensate C.

[0143] Table 1 shows the low-temperature high-rate discharge performance (LTHR performance) of batteries R1, R2, and E1 to E3 up to 300 cycles. The lignin compound, sodium lignosulfonate, is referred to simply as "lignin." The values ​​are the percentages when the initial discharge duration (after one cycle) of battery R1 is taken as 100; the higher the value, the better.

[0144] [Table 1]

[0145] Next, Figure 8 shows the relationship between the low-temperature high-rate discharge performance and the number of charge-discharge cycles for batteries R1, R2, and E1 to E3. Table 1 and Figure 8 show that even when a lignin compound is used as an organic shrinkage inhibitor, stratification in battery R2, which allows air to circulate through the electrolyte during charging, is suppressed up to approximately 100 to 200 cycles, and good low-temperature high-rate discharge performance is maintained. However, after approximately 300 charge-discharge cycles, the effect of stirring the electrolyte saturates, the progression of stratification can no longer be suppressed, and the low-temperature high-rate discharge performance of battery R2 deteriorates to the same level as battery R1.

[0146] On the other hand, when an organic condensation polymer is used, the low-temperature high-rate discharge performance is maintained well even after more than 300 charge-discharge cycles. This is thought to be because the expansion of the negative electrode material is suppressed, preventing saturation of the electrolyte stirring efficiency and suppressing stratification over the long term.

[0147] Next, the low-temperature high-rate discharge performance (LTHR performance) at the 500th cycle of batteries R1, R2, R3 to R5, and E1 to E3 is shown in Table 2. As in Table 1, the values ​​are the ratio (%) of the initial discharge duration (after 1 cycle) of battery R1, taken as 100, and the higher the value, the better.

[0148] [Table 2]

[0149] Figure 9 compares the low-temperature high-rate discharge performance at the 500th cycle for batteries R1, R2, R3-R5, and E1-E3. Table 2 and Figure 9 show that when a lignin compound is used as the organic shrinkage inhibitor, low-temperature high-rate discharge performance is significantly reduced even when air is circulated through the electrolyte during charging. On the other hand, when an organic condensate is used, low-temperature high-rate discharge performance is maintained well even after 500 charge-discharge cycles. Comparing the difference in low-temperature high-rate discharge performance between battery R1 and the other batteries, the distinct advantages of batteries E1-E3 are readily apparent. The use of condensate B is particularly advantageous.

[0150] The sulfur content of the organic shrinkage inhibitor is presumed to influence this ranking. The sulfur content of the lignin compound is 600 μmol / g, while that of condensates A, B, and C is 2000 μmol / g or more. Furthermore, condensates B and C contain both bisarene compound and monocyclic compound (especially hydroxyarene compound) units, while condensate A contains bisarene compound units. These structural differences are thought to be related to the differences in the suppression effect on the expansion of negative electrode materials.

[0151] [Rating 2] Next, the incidence of upper short circuits was evaluated for batteries R1, R2, and E1 to E3. Specifically, 18 cells with the same configuration were prepared and subjected to a charge-discharge cycle test under the same conditions as in Evaluation 1 above. The percentage of cells in which a sudden drop in capacity occurred at the end of discharge and an upper short circuit was confirmed was evaluated. The results are shown in Table 3.

[0152] [Table 3]

[0153] Table 3 shows that the incidence of upper short circuits is significantly reduced when organic condensation products are used. The incidence of such upper short circuits is significantly higher in battery R2 than in battery R1, and is a problem specific to lead-acid batteries that actively stir the electrolyte using auxiliary components to assist in stirring the electrolyte (i.e., batteries prone to sediment winding). On the other hand, when organic condensation products are used, as in batteries E1 to E3, the problem of upper short circuits is significantly reduced.

[0154] 《Lead acid batteries E11~E17》 Lead-acid batteries E11 to E17 were fabricated in the same manner as battery E1, except that the content of condensate A in the negative electrode material was changed as shown in Table 4. Similarly to battery E1, the low-temperature high-rate discharge performance (LTHR performance) at the 500th cycle was evaluated. An initial capacity test for the lead-acid batteries was also conducted at 30°C under the following conditions. The results are shown in Table 4. The initial capacity is a relative value, with battery E12 set to 100. The LTHR performance values, as in Table 1, are a percentage of the initial discharge duration (after one cycle) of battery R1 set to 100.

[0155] [Rating 3] <Initial capacity test> Discharge: Discharge at a current (A) equal to 0.2 times the rated capacity (Ah) until the final voltage reaches 1.7V / cell. Charging: Charge 130% of the discharged amount of electricity at a current (A) of 0.2 times the Ah value listed as the rated capacity.

[0156] [Table 4]

[0157] 《Lead acid batteries E21~E27》 Lead-acid batteries E21 to E27 were fabricated in the same manner as battery E2, except that the content of condensate B in the negative electrode material was changed as shown in Table 5. The low-temperature high-rate discharge performance (LTHR performance) at the 500th cycle was evaluated in the same manner as battery E2. The results are shown in Table 5. As in Table 1, the LTHR performance values ​​are expressed as a percentage when the initial discharge duration (after one cycle) of battery R1 is set to 100.

[0158] [Table 5]

[0159] 《Lead acid batteries E31~E37》 Lead-acid batteries E31 to E37 were fabricated in the same manner as battery E3, except that the content of condensate C in the negative electrode material was changed as shown in Table 6. The low-temperature high-rate discharge performance (LTHR performance) at the 500th cycle was evaluated in the same manner as battery E3. The results are shown in Table 6. As in Table 1, the LTHR performance values ​​are expressed as a percentage when the initial discharge duration (after one cycle) of battery R1 is set to 100.

[0160] [Table 6]

[0161] Figure 10 shows the relationship between the content of organic condensation product in the negative electrode material and the low-temperature high-rate discharge performance at the 500th cycle. Figure 11 shows the relationship between the content of organic condensation product in the negative electrode material and the initial capacity. Tables 4 to 6 and Figures 10 and 11 show that the higher the content of organic condensation product, the better the low-temperature high-rate discharge performance at the 500th cycle is maintained. However, as shown in Table 4, if the content of organic condensation product is excessively high, the initial capacity tends to decrease. From the perspective of balancing the low-temperature high-rate discharge performance and the initial capacity, the content of organic condensation product in the negative electrode material is optimally in the range of 0.03 to 0.3 mass%. [Explanation of symbols]

[0162] 1:Lead acid battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5a: Negative electrode strap 5b: Positive electrode strap 6a: Negative electrode column 6b: Positive pole 10: Battery case 11: Plate group 12: Lid 13:Air pipe 131: Air blower tube 131a: Bottom end 131b: Upper end 132: Connector 132a: Insertion part 132b:T-shaped part 14: Air supply device 15: Charger 16: Stirring device 16a:Top opening 16b: Bottom opening 100: Power supply

Claims

1. a cell; an electrolytic solution in which the cell is immersed; a battery case that accommodates the cell and the electrolytic solution; a lid that seals an opening of the battery case; and an auxiliary member that assists in stirring the electrolytic solution; The cell includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, the negative electrode plate comprises a negative electrode current collector and a negative electrode material, The lead-acid battery, wherein the negative electrode material comprises an organic condensation product.

2. 2. The lead-acid battery according to claim 1, wherein the content of the organic condensate in the negative electrode material is 0.03 mass % or more and 0.3 mass % or less.

3. the organic condensate contains an aromatic compound unit, 3. The lead-acid battery according to claim 1, wherein the aromatic compound has a sulfur-containing group.

4. 4. The lead-acid battery according to claim 3, wherein the aromatic compound comprises at least one selected from the group consisting of bisarene compounds and monocyclic compounds.

5. 5. The lead-acid battery according to claim 4, wherein the aromatic compound includes both a bisarene compound and a monocyclic compound.

6. The lead acid battery according to claim 4 or 5, wherein the bisarene compound includes a bisphenol compound.

7. The lead-acid battery according to claim 6, wherein the bisphenol compound comprises at least one selected from the group consisting of bisphenol A and bisphenol S.

8. The lead acid battery according to any one of claims 4 to 7, wherein the monocyclic compound includes a hydroxyarene compound.

9. 9. The lead acid battery of claim 8, wherein the hydroxyarene compound comprises a phenolsulfonic acid compound.

10. The lead acid battery according to any one of claims 1 to 9, wherein the sulfur element content of the organic condensate is 2000 µmol / g or more.

11. The lead acid battery according to any one of claims 1 to 10, wherein the auxiliary member is an air blower pipe for sending air to the electrolyte.

12. The lid is provided with a through hole, The lead-acid battery according to claim 11 , wherein the air duct is inserted into the through-hole, one end of the air duct is immersed in the electrolyte, and the other end of the air duct communicates with the outside of the lid.

13. A power supply device comprising: the lead-acid battery according to any one of claims 11 to 12; and an air supply device that supplies air to the air duct.

14. Further, a charger for charging the lead-acid battery is provided, The power supply device of claim 13 , wherein the air supply device is mounted on the charger.

15. The lead-acid battery according to any one of claims 1 to 10, wherein the auxiliary member is an agitator that agitates the electrolyte by moving within the lead-acid battery.

16. A method of using the power supply device of claim 14, comprising: during or after charging the lead-acid battery with the charger, operating the air supply device to send air into the electrolyte through the air blower pipe and agitate the electrolyte.

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