Valve-regulated lead-acid battery and method for manufacturing the same

Abstract

This invention provides a valve-regulated lead-acid battery that can achieve a good lifespan even when repeatedly performing charge-discharge cycles with PSOC. [Solution] The system comprises an electrode group 11 and an electrolyte, the electrode group including a positive electrode plate 3, a negative electrode plate 2 and a separator 4, the negative electrode plate including a negative electrode material, the separator being a nonwoven fabric containing glass fibers, the negative electrode material including a predetermined oxygen-containing organic compound, and the negative electrode material burden A valve-regulated lead-acid battery wherein the oxygen-containing organic compound content Cs in a first region extending to a depth of 50 μm from the surface of the electrode plate, or to the shallower of the depths reaching the negative electrode current collector, is greater than the oxygen-containing organic compound content Cin in a second region of the negative electrode material other than the first region, the ratio (Vn / Ve) of the total pore volume Vn of the negative electrode material to the volume Ve of the electrolyte that can be held in the separator satisfies 0.50 ≤ Vn / Ve ≤ 0.65, and the electrolyte contains sodium sulfate at a concentration of 1.0 g / L or more and 10.0 g / L or less.

Description

[Technical Field]

[0001] The present invention relates to a valve-regulated lead-acid battery and a method for manufacturing the same. [Background technology]

[0002] Patent Document 1 proposes a lead-acid battery comprising a positive electrode plate and a negative electrode plate, wherein the negative electrode plate comprises a negative electrode current collector and a negative electrode material supported by the negative electrode current collector, the negative electrode material comprises a first negative electrode material and a second negative electrode material disposed outside the first negative electrode material, the mass-based content (ppm) of the oxygen-containing organic compound in the first negative electrode material is greater than the mass-based content (ppm) of the oxygen-containing organic compound in the second negative electrode material, and the oxygen-containing organic compound has a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the 1H-NMR spectrum measured using deuterated chloroform as a solvent.

[0003] Patent Document 2 states that the electrode plate group comprises an electrode plate group, an electrolyte, and a battery case containing the electrode plate group and the electrolyte, wherein the electrode plate group comprises a positive electrode plate, a negative electrode plate, and an AGM separator interposed between the positive electrode plate and the negative electrode plate, the pressure applied to the electrode plate group in the battery case in the stacking direction between the positive electrode plate and the negative electrode plate is 10 kPa or more and 40 kPa or less, and the density of the AGM separator when a compressive force of 20 kPa is applied in the thickness direction is 0.14 g / cm³. 3 More than 0.20g / cm 3 The following is proposed: the negative electrode plate includes a negative electrode material, the negative electrode material includes an oxygen-containing organic compound, and the oxygen-containing organic compound has a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the 1H-NMR spectrum measured using deuterated chloroform as a solvent. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-085747 [Patent Document 2] Japanese Patent Publication No. 2022-085750 [Overview of the project] [Problems that the invention aims to solve]

[0005] Lead-acid batteries are sometimes used in a state of undercharge called a partially charged state (PSOC). For example, valve-regulated lead-acid batteries used in industrial or light mobility applications (e.g., motorcycles) are frequently used in PSOC. Because valve-regulated lead-acid batteries have low electrolyte fluidity and low lead ion diffusion, frequent use in PSOC leads to significant accumulation of lead sulfate on the negative electrode plate, and the coarsening (sulfation) of lead sulfate crystals progresses easily. Since lead ions do not easily dissolve from coarse lead sulfate during charging, the charge acceptance decreases, the capacity gradually declines, and the lifespan of the lead-acid battery is shortened. [Means for solving the problem]

[0006] One aspect of the present invention comprises an electrode group and an electrolyte, wherein the electrode group includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, the positive electrode plate includes a positive electrode material, the negative electrode plate includes a negative electrode material, the separator is a nonwoven fabric containing glass fibers, the negative electrode material includes an oxygen-containing organic compound, and the LC / MS spectrum of the oxygen-containing organic compound measured with chloroform as the solvent has a plurality of peaks in the region where the m / z value is 400 or more and 2000 or less, the plurality of peaks are spaced apart with m / z values ​​of 20 or more and 25 or less, or 40 or more and 50 or less, and the oxygen-containing The present invention relates to a valve-regulated lead-acid battery, wherein all oxygen atoms contained in the organic compound are contained in at least one of an ether bond and a hydroxyl group, the ratio of the total mass of oxygen atoms contained in the oxygen-containing organic compound to the mass of the oxygen-containing organic compound is less than 0.320, the content Cs of the oxygen-containing organic compound in a first region of the negative electrode material to a depth of 50 μm from the surface of the negative electrode plate or to the depth reaching the negative electrode current collector, whichever is shallower, is greater than the content Cin of the oxygen-containing organic compound in a second region of the negative electrode material other than the first region, the ratio (Vn / Ve) of the total pore volume Vn of the negative electrode material to the volume Ve of the electrolyte that can be held in the separator satisfies 0.50 ≤ Vn / Ve ≤ 0.65, and the electrolyte contains sodium sulfate at a concentration of 1.0 g / L or more and 10.0 g / L or less. [Effects of the Invention]

[0007] The valve-regulated lead-acid battery according to the present invention can achieve a good lifespan even when repeatedly undergoing charge-discharge cycles in a PSOC (Power Storage Oven). [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view showing the structure of an example of a valve-regulated lead-acid battery according to one embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view showing the structure of an example of a negative electrode plate. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present disclosure will be described with examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and materials may be applied as long as the effects of the present disclosure can be obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "numerical value A or more and numerical value B or less". In the following description, when the lower limit and the upper limit of a numerical value regarding a specific physical property or condition are exemplified, any combination of any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined as long as the lower limit is not more than the upper limit. When a plurality of materials are exemplified, one of them may be selected and used alone, or two or more of them may be combined and used.

[0010] In addition, the present disclosure includes combinations of matters described in two or more claims arbitrarily selected from a plurality of claims described in the appended claims. That is, as long as no technical contradiction occurs, matters described in two or more claims arbitrarily selected from a plurality of claims described in the appended claims can be combined.

[0011] A lead-acid battery includes a positive electrode plate, a negative electrode plate, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolyte. The electrolyte contains sulfuric acid. Charging and discharging proceed by the movement of sulfate ions between the positive electrode plate, the negative electrode plate, and the electrolyte. During discharging, sulfate ions move to the positive electrode plate and the negative electrode plate. During charging, sulfate ions move from the positive electrode plate and the negative electrode plate into the electrolyte.

[0012] A positive electrode plate, a negative electrode plate, and a separator constitute an electrode group. An electrode group typically includes multiple positive electrode plates, multiple negative electrode plates, and a separator interposed between the positive and negative electrode plates. The positive and negative electrode plates are stacked alternately via the separator. The electrode group, together with the electrolyte, constitutes a cell. One electrode group constitutes one cell. A lead-acid battery comprises one or more cells by comprising one or more electrode groups. There is no particular limit to the number of positive and negative electrode plates included in a single electrode group. An electrode group comprising a lead-acid battery according to this disclosure may, for example, include a total of 12 or more positive and negative electrode plates. Multiple electrode groups are typically housed in separate cell chambers and connected in series with one another.

[0013] The positive electrode plate includes a positive electrode current collector and a positive electrode material. The positive electrode material is a positive electrode active material that exhibits capacity through oxidation-reduction reactions, and contains at least lead dioxide during charging and at least lead sulfate during discharge.

[0014] The negative electrode plate includes a negative electrode current collector and a negative electrode material. The negative electrode material is a negative electrode active material that exhibits capacity through oxidation-reduction reactions, and contains at least lead during charging and at least lead sulfate during discharging.

[0015] The battery case has a bottom, side walls rising from the periphery of the bottom, and a lid that closes the open end of the side walls. The inside of the battery case is usually divided into multiple spaces by partitions. The inside of the battery case may be divided into multiple (e.g., six) cell chambers by partitions that are parallel to each other. Multiple partitions may intersect with each other to divide into multiple (e.g., four or more) cell chambers.

[0016] (1) A valve-regulated lead-acid battery according to an embodiment of the present disclosure comprises an electrode plate group and an electrolyte, wherein the electrode plate group includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, the positive electrode plate includes a positive electrode material, the negative electrode plate includes a negative electrode material, the separator is a nonwoven fabric containing glass fibers, the negative electrode material includes an oxygen-containing organic compound, and the LC / MS spectrum of the oxygen-containing organic compound measured with chloroform as a solvent has a plurality of peaks in the region where the m / z value is 400 or more and 2000 or less, and the plurality of peaks are spaced apart with m / z values ​​of 20 or more and 25 or less, or 40 or more and 50 or less. The oxygen-containing organic compound contains all oxygen atoms that are present in at least one of an ether bond and a hydroxyl group, the ratio of the total mass of oxygen atoms contained in the oxygen-containing organic compound to the mass of the oxygen-containing organic compound is less than 0.320, the content Cs of the oxygen-containing organic compound in a first region of the negative electrode material to a depth of 50 μm from the surface of the negative electrode plate or to the shallower of the depth reaching the negative electrode current collector is greater than the content Cin of the oxygen-containing organic compound in a second region of the negative electrode material other than the first region, the ratio (Vn / Ve) of the total pore volume Vn of the negative electrode material to the volume Ve of the electrolyte that can be held in the separator satisfies 0.50 ≤ Vn / Ve ≤ 0.65, and the electrolyte contains sodium sulfate at a concentration of 1.0 g / L or more and 10.0 g / L or less.

[0017] Valve-regulated lead-acid batteries are also known as VRLA (Valve-regulated lead-acid) batteries or sealed lead-acid batteries.

[0018] The valve-regulated lead-acid battery described in (1) above has improved lifespan when repeatedly performing charge-discharge cycles with PSOC (hereinafter also referred to as "PSOC cycle life") because the coarseness of lead sulfate is suppressed.

[0019] The valve-regulated lead-acid battery described in (1) above satisfies the following conditions (A) to (D), as previously stated.

[0020] (A) The separator is a nonwoven fabric containing glass fibers.

[0021] (B) The negative electrode material contains a predetermined oxygen-containing organic compound (hereinafter also referred to as "oxygen-containing organic compound (P)").

[0022] (C) The oxygen-containing organic compound (P) content Cs in the first region of the negative electrode material, from the surface of the negative electrode plate to a depth of 50 μm, or to the shallower of the depths reaching the negative electrode current collector, is greater than the oxygen-containing organic compound (P) content Cin in the second region of the negative electrode material other than the first region.

[0023] Furthermore, the first region is the area from the surface of the negative electrode plate to a depth of 50 μm, or to the depth reaching the negative electrode current collector, whichever is shallower, and therefore is at least a part of the overpaste. Overpaste is the film-like portion of the negative electrode material that extends beyond the negative electrode current collector and covers it. The thickness of the overpaste may be less than 50 μm from the surface of the negative electrode plate. In that case, the first region is the area from the surface of the negative electrode plate to the depth reaching the negative electrode current collector, and the thickness of the first region is equal to the thickness of the overpaste.

[0024] (D) The ratio (Vn / Ve) of the total pore volume Vn of the negative electrode material to the volume Ve of the electrolyte that can be held in the separator satisfies 0.50 ≤ Vn / Ve ≤ 0.65.

[0025] (E) The electrolyte contains sodium sulfate at a concentration of 1.0 g / L or more and 10.0 g / L or less.

[0026] Furthermore, the oxygen-containing organic compound (P) satisfies the following conditions (B1) to (B4).

[0027] (B1) The LC / MS spectrum of oxygen-containing organic compounds (P) measured with chloroform as the solvent has multiple peaks in the region where the m / z value (m is the mass of the ionic species and Z is the charge number of the ionic species) is between 400 and 2000.

[0028] (B2) Multiple peaks exist at intervals of m / z values ​​between 20 and 25, or between 40 and 50. It is also acceptable for peaks with m / z values ​​between 20 and 25 to coexist with peaks with m / z values ​​between 40 and 50.

[0029] (B3) All oxygen atoms in the oxygen-containing organic compound (P) are contained in at least one of the ether bond and the hydroxyl group.

[0030] (B4) The ratio of the total mass of oxygen atoms contained in the oxygen-containing organic compound (P) to the mass of the oxygen-containing organic compound (P) (hereinafter also referred to as "oxygen content (PO)") is less than 0.320.

[0031] One of the factors causing coarsening of lead sulfate is the presence of Pb within the pores of the negative electrode material during the discharge process. 2+ One example is the occurrence of ion supersaturation. In valve-regulated lead-acid batteries, due to the low fluidity of the electrolyte, Pb can form in the pores of the negative electrode material. 2+ Ions are prone to supersaturation. Pb in the pores of the negative electrode material. 2+ When the ions become supersaturated, lead sulfate dissolves (i.e., Pb 2+ This reduces the likelihood of (and the diffusion of sulfate ions into the electrolyte). In such environments, when lead-acid batteries are frequently used in PSOCs, lead sulfate accumulation usually becomes significant on the negative electrode plate, leading to coarsening of the lead sulfate crystals (sulfation) and a shortened cycle life.

[0032] In contrast, if conditions (A) to (D) are met, Pb in the pores of the negative electrode material 2+ Ion supersaturation is suppressed, leading to reduced coarsening of lead sulfate, and thus improving the PSOC cycle lifetime. This is generally thought to be due to the following mechanism.

[0033] The oxygen-containing organic compound (P) present in the first region (the surface layer portion of the negative electrode plate) of the negative electrode plate satisfies the conditions (B1) to (B4), so it has high hydrophilicity and is considered to have the effect of attracting the electrolytic solution in the pores of the negative electrode material toward the separator side (the surface layer portion side of the negative electrode plate). As a result, the diffusion of the electrolytic solution to the separator side is promoted, and Pb 2+ ions also diffuse to the separator side at the same time, and it becomes difficult for Pb 2+ ions to become supersaturated in the pores of the negative electrode material.

[0034] On the other hand, when the ratio (Vn / Ve) of the total pore volume (Vn) of the negative electrode material to the volume (Ve) of the electrolytic solution that can be held by the separator satisfies 0.50 ≤ Vn / Ve, the electrolytic solution in the separator can be easily supplied into the pores of the negative electrode material. In other words, the electrolytic solution can easily circulate between the pores of the separator and the pores of the negative electrode material.

[0035] In addition, when 0.65 < Vn / Ve, the force for the negative electrode plate to suck up the electrolytic solution from the separator becomes extremely large, and the effect of the diffusion of the electrolytic solution to the separator side by the oxygen-containing organic compound (P) (that is, the diffusion of Pb 2+ ions to the separator side) cannot be significantly obtained. Therefore, it is necessary to satisfy 0.50 ≤ Vn / Ve ≤ 0.65.

[0036] However, when the Pb 2+ ion concentration in the pores of the negative electrode material during discharge is properly maintained, the coarsening of lead sulfate is less likely to occur, and the PSOC cycle life is likely to be improved. On the other hand, since the Pb 2+ ion concentration is likely to be high on the separator side, it is likely to cause an osmotic short circuit.

[0037] In contrast, when the electrolytic solution contains sodium sulfate at a concentration of 1.0 g / L or more and 10.0 g / L or less, the osmotic short circuit is suppressed, so the PSOC cycle life is further improved. That is, the configurations (a) and (b) are for Pb in the pores of the separator 2+This configuration increases the number of ions and is prone to osmotic short circuits, but sodium sulfate prevents these short circuits. The inclusion of sodium sulfate in the electrolyte reduces the solubility of lead in the electrolyte, preventing an excess of lead ions and thus suppressing lead deposition within the separator. In other words, osmotic short circuits are prevented.

[0038] While the applications of valve-regulated lead-acid batteries are not particularly limited, the above effects can be particularly noticeable in power sources or stationary batteries for small mobility applications (e.g., motorcycles). This is because these power sources are often used under PSOC (Power Storage Operations Center) conditions.

[0039] (2) In the valve-regulated lead-acid battery described in (1) above, the content of Cs may be 50 ppm or more and 500 ppm or less, and the content of Cin may be 0 ppm or more and 49 ppm or less.

[0040] According to the valve-regulated lead-acid battery described in (2) above, the Cs content is 50 ppm or more, and the condition Cs > Cin is satisfied, so it is thought that a sufficient effect is exerted to draw the electrolyte in the pores of the negative electrode material toward the separator side (the surface layer side of the negative electrode plate). As a result, the electrolyte diffuses toward the separator side, and Pb 2+ The diffusion of ions toward the separator is promoted. Furthermore, because the Cs content is 500 ppm or less, the proportion of the surface of the negative electrode material covered with oxygen-containing organic compounds (P) does not become excessively high, ensuring good high-rate discharge characteristics and charge acceptance, and as a result, the PSOC cycle life is improved.

[0041] (3) In the valve-regulated lead-acid battery described in (1) or (2) above, the difference between the content Cs and the content Cin (Cs-Cin) is 0 <Cs-Cin≦300(ppm)であってもよい。

[0042] According to the control valve type lead-acid battery described in (3) above, since a sufficient concentration difference is ensured in the content of the oxygen-containing organic compound (P) in the first region and the second region of the negative electrode material, it is considered that the action of attracting the electrolyte in the pores of the negative electrode material to the separator side (the surface layer portion side of the negative electrode plate) is enhanced. Therefore, the coarsening of lead sulfate in the negative electrode plate is more significantly suppressed, and a better PSOC cycle life can be obtained.

[0043] (4) In the control valve type lead-acid battery according to any one of (1) to (3) above, the content Css of the oxygen-containing organic compound (P) in the separator in the first region from the facing surface of the separator to the negative electrode plate to a depth of 50 μm may be greater than the content Csin of the oxygen-containing organic compound (P) in the separator in the second region other than the first region of the separator.

[0044] In the control valve type lead-acid battery described in (4) above, the oxygen-containing organic compound (P) contained at the content Css on the facing surface of the separator with the negative electrode plate diffuses into the first region of the negative electrode material (in other words, the surface layer portion of the negative electrode plate). As a result, a structure (1 < Cs / Cin) that satisfies conditions (B) and (C) is obtained. Therefore, in the manufacturing process of the negative electrode plate, it is not necessary to include the oxygen-containing organic compound (P) in the first region of the negative electrode material, and the degree of freedom of the manufacturing process of the lead-acid battery is increased. In addition, since 1 < Css / Csin is satisfied, the electrolyte is not excessively attracted to the separator side, so the negative electrode material can hold a sufficient amount of electrolyte.

[0045] (5) The manufacturing method of the control valve type lead-acid battery according to any one of (1) to (4) above may include a step of preparing the negative electrode plate that does not contain the oxygen-containing organic compound (P), a step of including the oxygen-containing organic compound (P) in the negative electrode plate that does not contain the oxygen-containing organic compound (P), and a step of forming the electrode plate group using the negative electrode plate containing the oxygen-containing organic compound (P). and may be provided.

[0046] In the method for manufacturing a controlled valve type lead storage battery according to (5) above, after manufacturing the negative electrode plate, in order to include the oxygen-containing organic compound (P) in the negative electrode plate, without making a major change to the manufacturing process of the negative electrode plate, it is possible to easily obtain a configuration (1 < Cs / Cin) that satisfies conditions (B) and (C).

[0047] (6) The method for manufacturing a controlled valve type lead storage battery according to any one of (1) to (4) above is a method for manufacturing a controlled valve type lead storage battery according to claim 1, comprising a step of preparing the separator that does not contain the oxygen-containing organic compound (P), a step of applying the oxygen-containing organic compound (P) to the surface of the separator that does not contain the oxygen-containing organic compound (P) and faces the negative electrode plate, a step of forming the electrode plate group using the separator to which the oxygen-containing organic compound (P) has been applied to the surface facing the negative electrode plate, and may be provided.

[0048] The method for manufacturing a controlled valve type lead storage battery according to (6) above is characterized in that the oxygen-containing organic compound (P) is included in the surface of the separator facing the negative electrode plate, and there is no need to make a major change to the manufacturing process of the negative electrode plate. Therefore, it is possible to easily obtain a configuration (1 < Cs / Cin) that satisfies conditions (B) and (C).

[0049] The oxygen-containing organic compound (P) may have the following characteristics. (b1) The LC / MS spectrum of the oxygen-containing organic compound (P) measured using chloroform as a solvent preferably has 10 or more, and more preferably 15 or more peaks in the region where the m / z value is 400 or more and 1200 or less. Such an oxygen-containing organic compound (P) has a particularly good balance between hydrophilicity and hydrophobicity, and thus can suppress excessive movement of the electrolyte to the separator side.

[0050] (b2) The content of oxygen-containing organic compound (P) Cs in the negative electrode material in the first region may be 50% by mass or more and 300% by mass or less. In this case, the difference between the content of Cs and the content of Cin (Cs-Cin) can be controlled to a preferred range of 10 ≤ Cs-Cin ≤ 300 (ppm), while ensuring that the first region contains a sufficient amount of oxygen-containing organic compound (P). As a result, the effect of attracting the electrolyte in the pores of the negative electrode material towards the separator side (the surface layer side of the negative electrode plate) is significantly exhibited.

[0051] (b3) The oxygen-containing organic compound (P) may be an ether compound. The ether compound may have a polyoxyalkylene group and a terminal alkyl group or terminal alkenyl group. The polyoxyalkylene group is typically a polyoxyethylene group.

[0052] The oxygen-containing organic compound (P) may be an ether having a polyoxyethylene group and a terminal alkyl group or terminal alkenyl group (hereinafter also referred to as "polyoxyethylene-alkyl / alkenyl ether"). Polyoxyethylene-alkyl / alkenyl ethers are stable in sulfuric acid, are not easily decomposed, and have appropriate hydrophilicity and hydrophobicity.

[0053] (b4) The number of carbon atoms in the terminal alkyl group or terminal alkenyl group of the oxygen-containing organic compound (P) is, for example, 10 or more, and may be 13 or more. The number of carbon atoms in the terminal alkyl group or terminal alkenyl group is, for example, 20 or less, and may be 18 or less, and may be 17 or less. The number of carbon atoms in the terminal alkyl group is, for example, in the range of 10 to 20, may be 13 to 18, and is preferably in the range of 13 to 17. Polyoxyethylene alkyl / alkenyl ethers having 10 to 20 carbon atoms in the terminal alkyl group or terminal alkenyl group are thought to exhibit suitable hydrophobicity.

[0054] (b5) The number N of oxyethylene units in the polyoxyethylene group of the oxygen-containing organic compound (P) is, for example, 5 to 35, and may be 7 to 25, with 10 to 20 being preferred. When the number N of oxyethylene units is 5 to 35, a more favorable hydrophilicity is exhibited due to the lone pair of electrons of the oxygen atom. In addition, the oxygen content (PO) of the oxygen-containing organic compound (P) can be easily controlled within a suitable range.

[0055] (b6) The oxygen-containing organic compound (P) may be at least one selected from the group consisting of, for example, polyoxyethylene oleyl ether, polyoxyethylene tridecyl ether, and polyoxyethylene cetyl ether. In this case, the effect of attracting the electrolyte in the pores of the negative electrode material toward the separator side (the surface side of the negative electrode plate) is more reliably exerted.

[0056] In this specification, a fully charged state of a valve-regulated lead-acid battery is defined as the state in which charging is performed in an air chamber at 25°C ± 2°C with a current (A) equal to 0.2 times the value (in Ah) stated in the rated capacity, at a constant current and constant voltage of 2.23 to 2.30 V / cell, and charging is terminated when the charging current during constant voltage charging becomes 0.005 times the value (A) stated in the rated capacity. A fully charged lead-acid battery refers to a lead-acid battery manufactured by Kasei that has been fully charged.

[0057] A fully charged lead-acid battery is a lead-acid battery that has been charged to its full capacity after chemical formation. The timing for charging a lead-acid battery to its full capacity can be immediately after chemical formation, or after a certain amount of time has passed since formation (e.g., 720 hours or less). For example, a lead-acid battery that has been chemically formed and is in use (preferably in the early stages of use) may be charged.

[0058] In this specification, a battery in its initial use is a battery that is unused or has not been used for a long time and has not deteriorated much (for example, a battery that has been in use for less than 720 hours, including the time since chemical preparation).

[0059] The following describes the analytical method for oxygen-containing organic compounds (P) contained in the negative electrode material.

[0060] Prior to measurement or analysis, a fully charged lead-acid battery is disassembled to obtain the negative electrode plate to be analyzed.

[0061] Wash the obtained negative electrode plate with water to remove sulfuric acid. Washing should be continued until a pH test paper does not change color when pressed against the surface of the washed negative electrode plate. However, the washing time should be no more than 2 hours. Dry the washed negative electrode plate under reduced pressure at 60±5℃ for about 6 hours. If the negative electrode plate contains adhesive material after drying, remove the adhesive material by peeling it off.

[0062] First, samples for analysis are taken from the first and second regions of the negative electrode material, respectively.

[0063] A sample of the first region of the negative electrode material (hereinafter referred to as Sample A) is taken from the surface layer on both sides of the negative electrode plate (the first region from the surface of the negative electrode plate to a depth of 50 μm, or to the shallower of the depths reaching the negative electrode current collector). For example, the first region sample is taken by scraping the surface layer of the negative electrode material to a depth of 50 μm from the outermost surface on both sides of the negative electrode plate. Normally, the thickness of the overpaste of the negative electrode material is 50 μm or more, in which case the entire sample of the first region is taken from the overpaste portion.

[0064] Typically, more than 1 g of sample can be collected from a single negative electrode plate in the first region. For the analysis of oxygen-containing organic compounds (P), for example, about 5 g of sample from the first region is sufficient. Therefore, it is sufficient to take about 5 negative electrode plates from the valve-regulated lead-acid battery to be analyzed and prepare the sample from the first region (sample A).

[0065] A sample of the second region of the negative electrode material (hereinafter referred to as sample B) is taken, for example, from as close to the center as possible in the thickness direction of the negative electrode plate after removing the overpaste of the negative electrode material.

[0066] <Quantitative analysis> For the analysis, pulverized samples A and B are used. 5.0 ± 0.1 g of sample A or B is added to 5 ± 0.1 mL of chloroform and stirred at 20 ± 5 °C for 16 hours to extract the oxygen-containing organic compound (P). Then, the solids are removed by filtration to obtain a chloroform solution containing dissolved oxygen-containing organic compound (P). The oxygen-containing organic compound (P) content Cpm in the negative electrode material is quantified by analyzing the chloroform solution containing dissolved oxygen-containing organic compound (P) by liquid chromatography. Specifically, the concentration of oxygen-containing organic compound (P) in the chloroform solution containing dissolved oxygen-containing organic compound (P) is determined by a calibration curve method based on the intensity of a specific peak characteristic of oxygen-containing organic compound (P). From the obtained concentration, the oxygen-containing organic compound (P) content Cpm in the negative electrode material is calculated. The calibration curve is prepared in advance using oxygen-containing organic compound (P) identified separately by qualitative analysis.

[0067] <Qualitative analysis> A chloroform solution containing an oxygen-containing organic compound (P) is analyzed by liquid chromatography-mass spectrometry (LC / MS). By analyzing the LC / MS spectrum, it is possible to determine whether there are multiple peaks in the m / z range between 400 and 2000, and the intervals between the m / z values ​​of these peaks. Furthermore, infrared spectroscopy (FT-IR) allows for confirmation of whether all oxygen atoms in the oxygen-containing organic compound (P) are contained within at least one of an ether bond or a hydroxyl group. Other methods, such as ultraviolet-visible absorption spectroscopy, NMR spectroscopy, and pyrolysis GC-MS, can also be used to identify the oxygen-containing organic compound (P). Identifying the oxygen-containing organic compound (P) allows for the determination of the number of carbon atoms in the terminal alkyl or terminal alkenyl group, and the number of oxyethylene units (N) in the polyoxyethylene group.

[0068] The LC / MS spectral measurement conditions are shown below. Equipment: LC section (Agilent Technologies 1100 Series), MS section (Bruker Ductonics microOTOF focus type) Column: Unison UK-C8 (3μm, 2×50mm) Column temperature: 40℃ Mobile phase: A mixture of solutions A and B is used, and the mixing ratio of A and B is gradually changed from 90:10 to 0:100 over 20 minutes, with only solution B used from 20 minutes to 30 minutes. Solution A: 10 mM ammonium formate aqueous solution Solution B: Acetonitrile Flow rate: 0.3mL / min Detection method: ESI (Pos.) Injection volume: 1μL

[0069] The ratio of the total mass of oxygen atoms contained in an oxygen-containing organic compound (P) to the mass of the oxygen-containing organic compound (P) (oxygen content (PO)) is preferably measured by the following method. First, the concentrated extract is heated to 1150°C in a quartz tube filled with carbon particles and burned with nitrogen as the carry gas, causing thermal decomposition by the carbon particles, converting all the oxygen atoms in the resulting decomposition gas into carbon monoxide. The resulting carbon monoxide is oxidized by reacting with copper monoxide to produce carbon dioxide, which is then collected by adsorption by passing it through an absorption tube filled with sodium hydroxide and magnesium perchlorate. The amount of carbon dioxide collected can be determined from the change in mass of the absorption tube at this time. The amount of oxygen in the extract can be determined by converting the amount of carbon dioxide to the amount of oxygen. The oxygen content (PO) can be determined from the amount of oxygen in the extract and the concentration (mass) of the oxygen-containing organic compound (P).

[0070] Next, we will explain the method for analyzing oxygen-containing organic compounds (P) contained in the separator.

[0071] Prior to measurement or analysis, a fully charged lead-acid battery is disassembled to obtain the separator to be analyzed.

[0072] Wash the obtained separator with water to remove sulfuric acid. Continue washing until a pH test strip does not change color when pressed against the surface of the washed separator. Dry the washed separator under reduced pressure at 50±5℃ for approximately 12 hours.

[0073] Next, samples for analysis are taken from the first and second regions of the separator, respectively.

[0074] A sample of the first region of the separator (hereinafter referred to as sample C) is taken from the first region up to a depth of 50 μm from the surface of the separator facing the negative electrode plate. For example, the first region of the separator can be scraped to obtain a sample of the first region.

[0075] A sample of the second region of the separator (hereinafter referred to as sample D) is taken, for example, by scraping off a region up to a depth of 50 μm from both sides of the separator, and then taking a sample from the 50 μm thick region as close to the center as possible in the thickness direction of the separator.

[0076] <Total pore volume Vn of negative electrode material> The total pore volume of the negative electrode material is the sum of the volumes of all pores determined by the mercury intrusion method. The total pore volume of the negative electrode material is measured using a mercury porosimeter (Shimadzu Corporation, Autopore IV9510) with an unground sample of the negative electrode material.

[0077] Unground negative electrode material samples are taken from negative electrode plates removed from fully charged lead-acid batteries. The obtained negative electrode plates are washed with water to remove sulfuric acid. Washing is continued until pH test paper does not change color when pressed against the surface of the washed negative electrode plate. The washed negative electrode plates are dried at 60±5℃ until completely dry. Next, the negative electrode material is separated from the negative electrode plates to obtain an unground sample. The unground sample is placed in the measuring container of a mercury porosimeter, evacuated under reduced pressure, and then mercury is injected at a pressure of 0.05 psia (≒0.345 kPa) to 30000 psia (≒20700 kPa) and the pore volume distribution in the range of pore diameter 5.5 nm to 333 μm is measured.

[0078] <Volume Ve of electrolyte that can be held in the separator> A fully charged lead-acid battery is disassembled to obtain the separator to be analyzed, and its mass in the electrolyte-impregnated state is measured. The separator is then washed with water until it is confirmed that the pH test paper does not change color when pressed against the separator surface. The washed separator is dried under reduced pressure at 50±5℃ for approximately 12 hours. The mass of the dried separator is measured, and the volume of electrolyte that can be held in the separator is calculated from the difference in mass of the separator before and after washing and drying, and the specific gravity of the electrolyte. The Vn / Ve ratio is determined from the total pore volume Vn of the negative electrode material and the volume of electrolyte Ve.

[0079] <Concentration of sodium sulfate in the electrolyte> The concentration of sodium sulfate is obtained by analyzing the electrolyte using inductively coupled plasma atomic emission spectroscopy (ICP-AES). ICP-AES is used to quantitatively evaluate the amount of Na element in the electrolyte.

[0080] Hereinafter, a valve-regulated lead-acid battery according to an embodiment of the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to the following embodiments.

[0081] The following describes examples of components of a valve-regulated lead-acid battery.

[0082] (Positive plate) The positive electrode plate comprises a positive electrode current collector and a positive electrode material. The positive electrode material is held by the positive electrode current collector. The positive electrode material is the portion of the positive electrode plate excluding the positive electrode current collector. Adhesive members such as conductive layers, mats, and pasting paper may be attached to the positive electrode plate. Since the adhesive members are used integrally with the positive electrode plate, they are included as components of the positive electrode plate. When the positive electrode plate includes adhesive members, the positive electrode material is the portion of the positive electrode plate excluding the positive electrode current collector and the adhesive members.

[0083] The positive electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead or lead alloy sheet. Processing methods may include, for example, expansion or punching. Using a grid-like current collector as the positive electrode current collector makes it easier to support the positive electrode material.

[0084] As the lead alloy used for the positive electrode current collector, Pb-Ca alloys and Pb-Ca-Sn alloys, which have excellent corrosion resistance and mechanical strength, are preferred. The positive electrode current collector may have metal layers of different compositions, and the metal layers may be one layer or multiple layers.

[0085] The positive electrode material contains a positive electrode active material that exhibits capacity through a redox reaction. The positive electrode active material includes lead dioxide, lead sulfate, and the like.

[0086] Positive electrodes are obtained by chemically converting unconverted positive electrodes. Unconverted positive electrodes are obtained by filling a positive electrode current collector with positive electrode paste, allowing it to mature, and drying. Positive electrode paste is prepared, for example, by kneading a mixture containing lead powder, water, and sulfuric acid. Such positive electrodes are also called paste-type positive electrodes.

[0087] Chemical treatment may be carried out by immersing the electrode plate group, including the untreated positive electrode plate, in the sulfuric acid-containing electrolyte in the lead-acid battery case and charging the electrode plate group. Chemical treatment may also be carried out before the assembly of the lead-acid battery or the electrode plate group.

[0088] (Negative electrode plate) The negative electrode plate comprises a negative electrode current collector and a negative electrode material. The negative electrode material is held by the negative electrode current collector. The negative electrode material is the portion of the negative electrode plate excluding the negative electrode current collector. Note that adhesive members such as conductive layers, mats, and pasting paper may be attached to the negative electrode plate. The adhesive members are included as components of the negative electrode plate. When the negative electrode plate includes adhesive members, the negative electrode material is the portion of the negative electrode plate excluding the negative electrode current collector and the adhesive members.

[0089] The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead or lead alloy sheet. The processing method may be expansion or punching. Using a grid-like current collector as the negative electrode current collector makes it easier to support the negative electrode material.

[0090] The lead alloy used for the negative electrode current collector may be any of the following: a Pb-Sb alloy, a Pb-Ca alloy, or a Pb-Ca-Sn alloy. The lead alloy used for the negative electrode current collector may also contain at least one additive element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, etc. The negative electrode current collector may have metal layers of different compositions, and the metal layers may be one layer or multiple layers.

[0091] The negative electrode plate is obtained by chemically converting an unconverted negative electrode plate. The unconverted negative electrode plate is obtained by filling a negative electrode current collector with negative electrode paste, allowing it to mature, and drying. The negative electrode paste is prepared by kneading a mixture containing lead powder, water, and sulfuric acid. The negative electrode paste may optionally contain organic shrinkage inhibitors, carbonaceous materials, barium sulfate, etc.

[0092] The chemical treatment may be carried out by immersing the electrode plate group, including the untreated negative electrode plate, in an electrolyte containing sulfuric acid in the lead-acid battery case, thereby charging the electrode plate group. The chemical treatment may also be carried out before the assembly of the lead-acid battery or the electrode plate group. The charged negative electrode active material contains spongy lead.

[0093] The anode electrode material after chemical formation contains an anode active material that exhibits capacity through a redox reaction. The anode active material includes lead, lead sulfate, and the like.

[0094] Organic shrinkage inhibitors that can be used include lignin, lignin derivatives, and synthetic organic shrinkage inhibitors (such as formaldehyde condensates of phenol compounds). Examples of lignin derivatives include lignin sulfonic acid or its salts (such as alkali metal salts). The negative electrode material may contain one organic shrinkage inhibitor or two or more.

[0095] The content of the organic shrinkage inhibitor in the negative electrode material is, for example, 0.01% by mass or more and 1% by mass or less, and may be 0.03% by mass or less and 0.6% by mass or less.

[0096] Carbonaceous materials that can be used include carbon black, artificial graphite, natural graphite, hard carbon, and soft carbon. A single carbonaceous material may be used, or two or more may be used in combination.

[0097] The carbonaceous material content in the negative electrode material is, for example, 0.1% by mass or more and 3% by mass or less.

[0098] The barium sulfate content in the negative electrode material is, for example, 0.1% by mass or more and 3% by mass or less.

[0099] The negative electrode material further contains an oxygen-containing organic compound (P) in at least one region. The method for incorporating the oxygen-containing organic compound (P) into the negative electrode material is not particularly limited.

[0100] As a method for manufacturing a negative electrode plate that satisfies condition (C) (content Cs > content Cin), the following methods can be cited.

[0101] (i) A method of producing an unformed negative electrode plate by filling a negative electrode current collector with negative electrode paste, immersing it in a polymer solution (P) before aging and drying, and then drying and aging it, and then forming the negative electrode plate.

[0102] Here, the polymer solution (P) is a solution obtained by dissolving an oxygen-containing organic compound (P) in a predetermined solvent. For example, water can be used as the solvent. In the polymer solution (P), the concentration of the oxygen-containing organic compound (P) may be, for example, 30% to 90% by mass.

[0103] (ii) A method in which an unconverted negative electrode plate, after maturation and drying, is immersed in a polymer solution (P), then dried, and then converted.

[0104] (iii) A method in which after filling the negative electrode current collector with the first negative electrode paste, a second negative electrode paste containing an oxygen-containing organic compound at a content rate higher than that of the first negative electrode paste is applied to the surface of the first negative electrode paste, followed by drying and aging to produce an unformed negative electrode plate, and then chemical conversion. Note that the first negative electrode paste may or may not contain the polymer solution (P).

[0105] Note that even if an appropriate amount of the oxygen-containing organic compound (P) that does not affect battery performance is added to the electrolytic solution, the oxygen-containing organic compound (P) is not detected from the negative electrode material, or if detected, it is in a very small amount.

[0106] Therefore, the content rate Cs of the oxygen-containing organic compound in the first region of the negative electrode material is preferably 50 ppm or more, may be 100 ppm or more, and may be 200 ppm or more on a mass basis. The content rate Cs is preferably, for example, 500 ppm or less, may be 400 ppm or less, and may be 350 ppm or more. The content rate Cs may be, for example, in the range of 50 ppm to 500 ppm, or may be in the range of 100 ppm to 400 ppm.

[0107] Also, the content rate Cin of the oxygen-containing organic compound in the first region of the negative electrode material is preferably 49 ppm or less, may be 20 ppm or less, may be 10 ppm or less, and may be 0 ppm on a mass basis.

[0108] The difference (Cs - Cin) between the content rate Cs and the content rate Cin preferably satisfies 0 < Cs - Cin ≤ 300, more preferably satisfies 10 ≤ Cs - Cin ≤ 300, and may satisfy 40 ≤ Cs - Cin ≤ 300.

[0109] (Separator) Nonwoven fabrics containing glass fibers are used as separators. Nonwoven fabrics containing glass fibers are also called AGM (Absorbed Glass Mat (Absorbent Glass Mat)) or AGM separators. Nonwoven fabrics containing glass fibers (hereinafter also referred to as "glass fiber nonwoven fabrics") are mats in which glass fibers are intertwined without weaving, and are mainly composed of glass fibers. For example, 60% or more by mass of a glass fiber nonwoven fabric is made up of glass fibers. Glass fiber nonwoven fabrics may also contain components other than glass fibers, such as acid-resistant inorganic powders (e.g., silica powder, glass powder, diatomaceous earth), polymers as binders, etc.

[0110] Glass fiber nonwoven fabric or AGM may contain glass fibers and organic fibers. Preferably, the proportion of glass fibers in the total number of fibers constituting the glass fiber nonwoven fabric or AGM is 60% by mass or more.

[0111] As organic fibers, fibrous materials insoluble in the electrolyte are used. Examples of organic fibers include polymer fibers (polyolefin fibers, acrylic fibers, polyester fibers (such as polyethylene terephthalate fibers)), pulp fibers, etc.

[0112] The thickness of the separator placed between the negative and positive electrodes should be selected according to the distance between the electrodes. The number of separators should be selected according to the number of electrodes.

[0113] (electrolyte) The electrolyte is an aqueous solution containing sulfuric acid, and may be gelled if necessary. The electrolyte contains sodium sulfate (Na) to suppress osmotic short circuits, and may also contain metal cations other than Na ions if necessary. Examples of such metal cations include Li ions, Mg ions, and Al ions.

[0114] The concentration of sodium sulfate in the electrolyte is, for example, 1.0 g / L or more and 7.0 g / L or less, but may also be 1.0 g / L or more and 3.0 g / L or less, or 5.0 g / L or more and 7.0 g / L or less.

[0115] The density of the electrolyte in a fully charged lead-acid battery at 20°C is, for example, 1.20 g / cm³. 3 The above is 1.25 g / cm³. 3 The above may also be acceptable. The density of the electrolyte at 20°C is, for example, 1.35 g / cm³. 3 The following is the value: 1.32 g / cm³ 3 The following is preferable:

[0116] Figure 1 is a schematic cross-sectional view showing the structure of an example of a valve-regulated lead-acid battery. In Figure 1, the lead-acid battery 1 comprises a battery case 10 that houses an electrode plate group 11 and an electrolyte (not shown). The upper opening of the battery case 10 is closed with a lid 12A. The electrode plate group 11 is composed of multiple negative electrode plates 2 and positive electrode plates 3 stacked with separators 4 in between.

[0117] Each of the multiple negative electrode plates 2 has an upward-projecting current-collecting tab (not shown) on its upper part. Each of the multiple positive electrode plates 3 also has an upward-projecting current-collecting tab (not shown) on its upper part. The tabs of the negative electrode plates 2 are connected and integrated by negative electrode straps (not shown). Similarly, the tabs of the positive electrode plates 3 are connected and integrated by positive electrode straps (not shown). The negative electrode straps are connected to negative electrode posts (not shown) which serve as external terminals, and the positive electrode straps are connected to positive electrode posts (not shown) which serve as external terminals.

[0118] Figure 2 is a schematic cross-sectional view showing the structure of the negative electrode plate 2. The negative electrode plate 2 has a negative electrode current collector 21 and a negative electrode material 22. The negative electrode material 22 usually has two regions: an inner layer portion 22c that is filled so as to fit within the grid of the negative electrode current collector 21, and an overpaste 22s that extends beyond the negative electrode current collector 21. In the example in Figure 2, the first region 222 of the negative electrode material 22 is the region from the surface of the negative electrode plate to a depth of 50 μm, and a part of the overpaste 22s (surface layer) becomes the first region 222. The region of the negative electrode material 22 on both sides of the negative electrode plate 22, excluding the first region, is the second region 221. In the example in Figure 2, the inner layer portion 22c and a part of the overpaste 22s continuous with the inner layer portion 22c are included in the second region 221.

[0119] The battery case 10 is divided into multiple (three in the illustrated example) independent cell chambers 10R, and one electrode plate group 11 is housed in each cell chamber 10R. The lid 12 is equipped with an independent exhaust valve 13 for each cell chamber 10R. When the internal pressure of a cell chamber 10R exceeds a predetermined upper limit, the exhaust valve 13 opens, and gas is directly released from the cell chamber 10R to the outside. When the internal pressure of a cell chamber 10R is below the upper limit, the oxygen generated on the positive electrode plate 3 is reduced on the negative electrode plate 2 inside the cell chamber 10R to produce water.

[0120] The structure of the lead-acid battery is not limited to the above. For example, the battery case 10 may be divided into six independent cell chambers 10R, or it may have only one cell chamber. Also, although Figure 1 shows the case where there are three cells in the cell chamber 10R, the battery case 10 may have multiple independent cell chambers, each cell chamber may be equipped with an exhaust valve 13, or the lid may have a central exhaust chamber that communicates with each cell chamber. The central exhaust chamber is equipped with fewer exhaust valves than the number of cell chambers (for example, one).

[0121] [Examples] The present invention will be described in detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0122] The following describes the evaluation method for valve-regulated lead-acid batteries. For evaluation, a lead-acid battery (nominal voltage 12V) with six cells, each consisting of five positive plates and six negative plates, is used. Here, a valve-regulated lead-acid battery with a rated 10-hour rate capacity of 50Ah is used. The evaluation method is described below.

[0123] ≪PSOC Cycle Life≫ First, perform supplemental charging (step (1) below), and then repeat steps (2) to (8) below until the terminal voltage reaches 1.6V / cell in step (3), or until the discharge capacity is 80% or less of the rated capacity in step (6).

[0124] (1) Supplemental charging: Constant voltage charging (2.4V x 4h, maximum 5I) 10 A (25A)) + constant current charging (0.5I 10 A (2.5A x 4h) (2)30% discharge: 2I 10 A (10A) × 1.5h (3)50% discharge: 2I 10 A (10A) × 2.5h (4)50% charge: 2I 10 A (10A) × 2.5h (5) Refresh charge every 50 cycles of steps (3) and (4): Constant voltage charging (2.4V / cell x 4h, maximum 5I) 10 A (25A)) + constant current charging (0.5I 10 A (2.5A x 4h) (6) Capacity test: I 10 A (5A), (FV = 1.6V) (7) Two-stage constant current charging: 2I 10 A (10A) is 80% of the discharge capacity in the capacity test + 0.5I 10 Charge 50% of the discharge capacity in the capacity test at A (2.5A).

[0125] Note that the current (A) which is 1 / n of the Ah value listed in the rated capacity is the n-hour rate current (I n ) is called. n This is the current value (in A) that corresponds to the value obtained by dividing the battery's rated n-hour rate capacity (in Ah) by n. Therefore, the 10-hour rate current I10 This refers to a current (A) that is 1 / 10th of the Ah value listed in the rated capacity.

[0126] 《Lead acid battery R1, C1~C9, E1, E2》 (1) Fabrication of the positive electrode plate A positive electrode paste is prepared by mixing lead oxide, water, and sulfuric acid. The positive electrode paste is filled into the mesh of an expanded grid made of a Pb-Ca-Sn alloy, which serves as the positive electrode current collector, and then aged and dried to obtain an unformed positive electrode plate.

[0127] (2) Fabrication of the negative electrode plate A negative electrode paste is prepared by mixing lead oxide, carbon black, barium sulfate, an organic shrinkage inhibitor, water, and sulfuric acid. The negative electrode paste is filled into the mesh of an expanded grid made of a Pb-Ca-Sn alloy, which is the negative electrode current collector, and then aged and dried to obtain an unformed negative electrode plate. The total pore volume Vn of the negative electrode material is adjusted by changing the water and sulfuric acid content in the negative electrode paste, the particle size of the lead oxide, the concentration of the sulfuric acid aqueous solution, the amount of sulfuric acid aqueous solution added to the lead oxide per unit time, the carbon black content, the barium sulfate content, and the type of organic shrinkage inhibitor.

[0128] The amounts of carbon black, barium sulfate, and organic shrinkage inhibitor are adjusted so that, when measured in the fully charged state of the pre-formulated chemical, they are 0.2% by mass, 0.4% by mass, and 0.1% by mass, respectively.

[0129] If necessary, the aged and dried unformed negative electrode plate is immersed in an aqueous solution of an oxygen-containing organic compound (P) (polymer solution (P)), and then dried to produce a formed negative electrode plate containing an oxygen-containing organic compound (P) with a predetermined content of Cs and Cin. The content of Cs and Cin is controlled by the concentration of the polymer solution (P) and the immersion time of the unformed negative electrode plate in the polymer solution (P). The oxygen-containing organic compound (P) used is shown below.

[0130] <Oxygen-containing organic compounds (P)> As the oxygen-containing organic compound (P), the following polyoxyethylene alkyl / alkenyl ethers that satisfy condition (B) were used.

[0131] (i) POE / TDE (Polyoxyethylene Tridecyl Ether) Number of carbon atoms in the terminal alkyl group = 13 Oxyethylene unit count N = 5 to 22 Number of peaks in the m / z value range of 400 to 1200 = 18 Peak interval (m / z) = 20-25 (22) or 40-50 (44) Oxygen content (PO)=0.309 Oxygen atom = ether group, hydroxyl group

[0132] (3) Separator AGM with a glass fiber content of 90% by mass is used as the separator. The volume Ve of the electrolyte that can be held in the separator is adjusted by changing the density of the AGM separator.

[0133] (4) Preparation of electrolyte A sulfuric acid aqueous solution containing sodium sulfate at a predetermined concentration is prepared as the electrolyte. The density of the electrolyte in the lead-acid battery after chemical conversion is 1.12 to 1.32 g / cm³. 3 It is within the range.

[0134] (5) Manufacturing of lead-acid batteries A valve-regulated lead-acid battery satisfying the various parameters shown in Table 1 will be manufactured. Specifically, five unformed positive plates and six unformed negative plates will be alternately stacked with an AGM (Automated Green Magnet) in between to form an electrode plate group. The tabs of the positive plates and the tabs of the negative plates will be welded to the positive and negative electrode straps, respectively, using the cast-on-strap (COS) method. The electrode plate group will be inserted into a polypropylene battery case, electrolyte will be poured in, and the plate formation will be carried out within the battery case to assemble a valve-regulated lead-acid battery with a nominal voltage of 12V and a rated 10-hour rate capacity of 50Ah as described above.

[0135] (6) Evaluation The fabricated lead-acid battery is fully charged, and its PSOC cycle life is evaluated using the method described above. Table 1 shows the relative values ​​when the evaluation result of battery R1 is set to 100. A larger relative value indicates a better PSOC cycle life.

[0136] [Table 1]

[0137] Referring to Table 1, if the negative electrode material does not contain any oxygen-containing organic compounds (P) from battery R1, C1-C3, no significant change in PSOC cycle life is observed even when the Vn / Ve ratio is changed within the range of 0.50-0.65. On the other hand, if the Vn / Ve ratio is set to 0.4 or 0.70, the PSOC cycle life decreases. When the Vn / Ve ratio is 0.40, the force attracting the electrolyte to the separator side is too strong, which is thought to reduce the diffusibility of the electrolyte into the negative electrode material, causing a decrease in capacity and thus a decrease in cycle life. On the other hand, when the Vn / Ve ratio is 0.7, the force attracting the electrolyte to the negative electrode material side is too strong, which is thought to reduce Pb 2+ It is thought that ions tend to become supersaturated within the pores of the negative electrode material, leading to coarsening of the lead sulfate and a decrease in cycle life.

[0138] From batteries C8, C9, E1, and E2, it can be seen that when an oxygen-containing organic compound (P) is included only in the first region of the negative electrode material, the PSOC cycle life increases significantly when the Vn / Ve ratio is in the range of 0.50 to 0.65. On the other hand, when the Vn / Ve ratio is 0.4, the force attracting the electrolyte to the separator side is too strong, and the oxygen-containing organic compound (P) present in the first region reduces the diffusivity of the electrolyte in the pores of the negative electrode material, which is thought to cause a decrease in capacity and a significant decrease in cycle life. Also, when the Vn / Ve ratio is 0.7, the force attracting the electrolyte to the negative electrode material side is too strong, and it is thought that the effect of the oxygen-containing organic compound (P) does not manifest. Therefore, Pb 2+It is thought that supersaturation easily occurs within the pores of the negative electrode material, leading to the coarsening of lead sulfate. Furthermore, in the first region where oxygen-containing organic compounds (P) are present, the utilization rate of the negative electrode material decreases, which is thought to further reduce the cycle life.

[0139] From battery C4-C7, it can be seen that when oxygen-containing organic compounds (P) are present in equal concentrations in the first and second regions of the negative electrode material, the effect of oxygen-containing organic compounds (P) does not manifest. This is thought to be because there is no concentration difference between Cs and Cin, so the diffusion effect of the electrolyte by oxygen-containing organic compounds (P) does not manifest. Furthermore, it is thought that the utilization rate of the negative electrode material is reduced because the first and second regions contain oxygen-containing organic compounds (P).

[0140] 《Lead acid battery C10~C13, E3~E13》 Aside from varying the concentrations of Cs and Cin as shown in Table 2, a battery was fabricated and evaluated in the same manner as the previously described battery (e.g., battery E1). The results are shown in Table 2.

[0141] [Table 2]

[0142] Referring to Table 2, it can be seen that the PSOC cycle life increases significantly when Cs > Cin for batteries R1, E1, and E3-E13. When Cs > Cin, the force that attracts the electrolyte towards the separator is strong, and it is thought that the diffusivity of the electrolyte is increased. On the other hand, in batteries C10-C13, the effect of increasing the diffusivity of the electrolyte is not observed, and only the effect of reducing the utilization rate of the negative electrode material by oxygen-containing organic compounds (P) is observed. Therefore, the PSOC cycle life decreases as Cin increases.

[0143] 《Lead acid battery C14~C20, E14》 Except for changing the oxygen-containing organic compound (P) to the oxygen-containing organic compound (P) listed in Table 3, or an oxygen-containing organic compound that does not meet condition (B), the battery was fabricated and evaluated in the same manner as the previously described battery (e.g., battery E1). The results are shown in Table 3.

[0144] As the oxygen-containing organic compound (P), the following polyoxyethylene alkyl / alkenyl ethers that satisfy condition (B) were used.

[0145] (ii) POE / STE (Polyoxyethylene cetyl ether) Number of carbon atoms in the terminal alkyl group = 16 Oxyethylene unit count N = 6 to 33 Number of peaks in the m / z value range of 400 to 1200 = 45 Peak interval (m / z) = 20-25 (22) or 40-50 (44) Oxygen content (PO)=0.318 Oxygen atom = ether group, hydroxyl group

[0146] The following oxygen-containing organic compounds were used as examples of compounds that did not satisfy condition (B). (iii) Oleic acid Oxygen content (PO)=0.113

[0147] (iv) PPG (Polyoxypropylene Glycol) Peak interval (m / z) = 58 Oxygen content (PO)=0.283

[0148] (v) PEG oleate (polyoxyethylene oleate) Peak interval (m / z) = 44 Oxygen content (PO)=0.240

[0149] (vi) POE lauryl ether (polyoxyethylene laurate) Peak interval (m / z) = 22, 44 Oxygen content (PO)=0.320

[0150] [Table 3]

[0151] Referring to Table 3, it can be seen that only specific oxygen-containing organic compounds (P) that satisfy conditions (B1) to (B4) possess optimal hydrophilicity, resulting in a significant diffusion of the electrolyte towards the separator and potentially improving the PSOC cycle life. On the other hand, oxygen-containing organic compounds that do not satisfy conditions (B1) to (B4) do not possess appropriate hydrophilicity, disrupting the balance of electrolyte diffusion between the separator and the negative electrode material, and thus failing to improve the PSOC cycle life. Furthermore, the inclusion of oxygen-containing organic compounds (P) in the negative electrode material is thought to reduce the utilization rate of the negative electrode material, thereby actually decreasing the PSOC cycle life.

[0152] 《Lead acid battery C21~C22, E15~E16》 Except for changing the concentration of sodium sulfate in the electrolyte as shown in Table 4, the battery was constructed and evaluated in the same manner as the previously described battery (e.g., battery E1). The results are shown in Table 4.

[0153] [Table 4]

[0154] Table 4 shows that the presence of oxygen-containing organic compounds (P) in the first region results in Pb in the pores of the negative electrode material. 2+ This makes it easier for the Pb to flow into the separator side, and the Pb in the pores of the separator 2+ It can be seen that as the concentration increases, penetration short circuits are more likely to occur (Battery C21). On the other hand, it can be seen that penetration short circuits are significantly suppressed by including sodium sulfate in the electrolyte at a predetermined concentration (Batteries E1, E15, E16). However, it can be seen that if too much sodium sulfate is added to the electrolyte, the charge acceptance decreases and the PSOC cycle life actually decreases (Battery C22).

[0155] 《Lead acid battery E17~E18》 Aside from varying the concentrations of Cs and Cin as shown in Table 5, the battery was fabricated and evaluated in the same manner as the previously described battery (e.g., battery E1). The results are shown in Table 5.

[0156] [Table 5]

[0157] Table 5 shows that the effect of improving PSOC cycle life becomes significant when the difference between the content of Cs and the content of Cin (Cs-Cin) satisfies Cs-Cin ≤ 300, and becomes even more significant when 40 ≤ Cs-Cin ≤ 300. [Industrial applicability]

[0158] The valve-regulated lead-acid battery according to the present invention is suitable, for example, as a power source for small mobility devices such as motorcycles, or as a stationary power source, but its applications are not particularly limited. [Explanation of symbols]

[0159] 1:Lead acid battery 2: Negative plate 21: Negative electrode current collector 22: Negative electrode material 22c: Inner layer 22s: Overpaste 222: First area 221:Second area 3: Positive plate 4: Separator 11: Plate group 10:Battery container 10R: Cell chamber 13: Exhaust valve

Claims

1. It comprises a group of electrode plates and an electrolyte, The electrode plate group includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive electrode material, The aforementioned negative electrode plate includes a negative electrode material, The separator is a nonwoven fabric containing glass fibers. The negative electrode material contains an oxygen-containing organic compound. The LC / MS spectrum of the oxygen-containing organic compound measured using chloroform as a solvent has multiple peaks in the region where the m / z value is between 400 and 2000. The aforementioned multiple peaks exist at intervals of m / z values ​​of 20 to 25, or 40 to 50. All oxygen atoms contained in the aforementioned oxygen-containing organic compound are included in at least one of the ether bond and the hydroxyl group. The ratio of the total mass of oxygen atoms contained in the oxygen-containing organic compound to the mass of the oxygen-containing organic compound is less than 0.

320. The oxygen-containing organic compound content Cs in the first region of the negative electrode material, extending to a depth of 50 μm from the surface of the negative electrode plate or to the shallower of the depths reaching the negative electrode current collector, is greater than the oxygen-containing organic compound content Cin in the second region of the negative electrode material other than the first region. The ratio (Vn / Ve) of the total pore volume Vn of the negative electrode material to the volume Ve of the electrolyte that can be held in the separator satisfies 0.50 ≤ Vn / Ve ≤ 0.

65. A valve-regulated lead-acid battery wherein the electrolyte contains sodium sulfate at a concentration of 1.0 g / L or more and 10.0 g / L or less.

2. The Cs content is 50 ppm or more and 500 ppm or less. The valve-regulated lead-acid battery according to claim 1, wherein the Cin content is 0 ppm or more and 49 ppm or less.

3. The valve-regulated lead-acid battery according to claim 1, wherein the difference between the content Cs and the content Cin (Cs - Cin) is 0 < Cs - Cin ≤ 300.

4. The valve-regulated lead-acid battery according to claim 1, wherein the content of the oxygen-containing organic compound Css in the separator in a first region up to a depth of 50 μm from the surface of the separator facing the negative electrode plate is greater than the content of the oxygen-containing organic compound Csin in a second region of the separator other than the first region.

5. A method for manufacturing a valve-regulated lead-acid battery according to claim 1, A step of preparing the negative electrode plate that does not contain the oxygen-containing organic compound, A step of adding the oxygen-containing organic compound to the negative electrode plate which does not contain the oxygen-containing organic compound, A step of forming the electrode plate group using the negative electrode plate containing the oxygen-containing organic compound, A method for manufacturing a valve-regulated lead-acid battery, comprising the following:

6. A method for manufacturing a valve-regulated lead-acid battery according to claim 1, A step of preparing the separator that does not contain the oxygen-containing organic compound, A step of applying the oxygen-containing organic compound to the surface of the separator that does not contain the oxygen-containing organic compound and faces the negative electrode plate, A method for manufacturing a valve-regulated lead-acid battery, comprising the steps of forming the electrode plate group using the separator on which the oxygen-containing organic compound is applied to the surface facing the negative electrode plate.

Images