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

Abstract

To provide a valve-regulated lead-acid battery that can suppress PCL (polycarbonate clogging) within the density range of the positive electrode material, which allows for increased capacity. [Solution] The density of the positive electrode material is 3.3 g / cm³. 3 More than 4.0g / cm 3 The following conditions apply: the ratio of the integrated pore volume Vs (pores between 0.01 μm and 1 μm) to the total pore volume Vn of the negative electrode material is between 0.27 and 0.64; the negative electrode material contains an oxygen-containing organic compound; the LC / MS spectrum of the oxygen-containing organic compound measured with chloroform as the solvent has multiple peaks in the region of m / z values ​​between 400 and 2000; the multiple peaks are spaced apart with m / z values ​​between 20 and 25, or between 40 and 50; all oxygen atoms in the oxygen-containing organic compound are contained in at least one of the ether bond and the hydroxyl group; and the ratio of the total mass of oxygen atoms in the oxygen-containing organic compound to the mass of the oxygen-containing organic compound is less than 0.320.

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 describes a valve-regulated lead-acid battery, the lead-acid battery comprising at least one cell having an electrode plate group and an electrolyte, the electrode plate group comprising a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate, the negative electrode plate comprising a negative electrode material, and the negative electrode material being measured using deuterated chloroform as a solvent. 1 The polymer compound has a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the H-NMR spectrum, the positive electrode plate comprises the positive electrode material, and the density of the positive electrode material is 3.70 g / cm³. 3 More than 4.65g / cm 3 The following is proposed: a lead-acid battery.

[0003] Patent Document 2 proposes a lead-acid battery comprising "a group of electrode plates and an electrolyte, wherein the group of electrode plates comprises a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, where D is the distance between the positive electrode plate and the negative electrode plate and T is the maximum thickness of the separator, so DT ≤ 0.15 mm, the negative electrode plate comprises a negative electrode material, the negative electrode material contains a polymer compound, and the polymer compound has a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the 1H-NMR spectrum." [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2022-113635 [Patent Document 2] International Publication No. 2020-241884 [Overview of the project] [Problems that the invention aims to solve]

[0005] Valve-regulated lead-acid batteries are widely used in uninterruptible power supplies, power storage, and automotive applications due to their excellent maintainability. To improve the energy density of lead-acid batteries, methods such as thinning the electrode plates and reducing the density of the electrode material to facilitate the diffusion of the electrolyte into the electrode plates and increase the utilization rate of the active material have been attempted.

[0006] However, with the above method, the electrolyte tends to diffuse easily near the positive electrode current collector on the positive electrode plate, causing insulating lead sulfate to accumulate between the positive electrode current collector and the positive electrode material, resulting in a phenomenon of premature capacity loss (PCL). [Means for solving the problem]

[0007] One aspect of the present invention comprises a positive electrode plate, a negative electrode plate, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolyte, wherein the separator is a nonwoven fabric containing glass fibers, the positive electrode plate contains a positive electrode material, the negative electrode plate contains a negative electrode material, and the density of the positive electrode material is 3.3 g / cm³. 3 More than 4.0g / cm 3 The present invention relates to a valve-regulated lead-acid battery, wherein the ratio of the integrated pore volume Vs (pores between 0.01 μm and 1 μm) to the total pore volume Vn of the negative electrode material (Vs / Vn) is between 0.27 and 0.64, the negative electrode material contains an oxygen-containing organic compound, and the LC / MS spectrum of the oxygen-containing organic compound measured with chloroform as the solvent has multiple peaks in the region of m / z values ​​between 400 and 2000, the multiple peaks are spaced apart with m / z values ​​between 20 and 25, or between 40 and 50, all oxygen atoms contained in the oxygen-containing organic compound are contained in at least one of an ether bond and a hydroxyl group, and 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. [Effects of the Invention]

[0008] The control valve type lead-acid battery according to the present invention can suppress PCL within the density range of the positive electrode material capable of achieving high capacity.

Brief Description of the Drawings

[0009] [Figure 1] It is a cross-sectional view schematically showing an example of the structure of a control valve type lead-acid battery according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0010] 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 made 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 used in combination.

[0011] Further, 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.

[0012] 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.

[0013] The positive electrode plate, the negative electrode plate, and the separator constitute an electrode plate group. The electrode plate group usually includes a plurality of positive electrode plates, a plurality of negative electrode plates, and a separator interposed between the positive electrode plates and the negative electrode plates. The positive electrode plates and the negative electrode plates are alternately stacked via the separator. The electrode plate group and the electrolyte together constitute a cell. One electrode plate group constitutes one cell. A lead-acid battery includes one or more cells by including one or more electrode groups. There is no particular limitation on the number of positive electrode plates and negative electrode plates included in one electrode plate group. The electrode plate group included in the lead-acid battery according to the present disclosure includes, for example, a total of 12 or more positive electrode plates and negative electrode plates. The plurality of electrode plate groups are usually housed in individual cell chambers and connected in series with each other.

[0014] The positive electrode plate includes a positive electrode current collector and a positive electrode electrode material. The positive electrode electrode material includes at least lead dioxide during charging and at least lead sulfate during discharging as a positive electrode active material that exhibits capacitance by an oxidation-reduction reaction.

[0015] The negative electrode plate includes a negative electrode current collector and a negative electrode electrode material. The negative electrode electrode material includes at least lead during charging and at least lead sulfate during discharging as a negative electrode active material that exhibits capacitance by an oxidation-reduction reaction.

[0016] The battery case has a bottom, side walls rising from the periphery of the bottom, and a lid portion closing the open end of the side walls. Inside the battery case, it is usually divided into a plurality of spaces by partition walls. Inside the battery case, for example, it may be divided into a plurality (for example, six) of cell chambers by partition walls parallel to each other. The plurality of partition walls may intersect with each other and be divided into a plurality (for example, four or more) of cell chambers.

[0017] (1) The control valve type lead-acid battery according to an embodiment of the present disclosure 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 separator is a non-woven fabric containing glass fibers. The positive electrode plate contains a positive electrode material, the negative electrode plate contains a negative electrode material, the density of the positive electrode material is 3.3 g / cm 3 or more and 4.0 g / cm 3 or less. The ratio (Vs / Vn) of the integrated pore volume Vs with a pore diameter of 0.01 μm or more and 1 μm or less to the total pore volume Vn of the negative electrode material is 0.27 or more and 0.64 or less. The negative electrode material contains an oxygen-containing organic compound, and the LC / MS spectrum of the oxygen-containing organic compound measured using 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. The plurality of peaks are present at intervals where the m / z value is 20 or more and 25 or less, or 40 or more and 50 or less. All oxygen atoms contained in the oxygen-containing organic compound are contained in at least one of an ether bond and a hydroxy group. The ratio of the total mass of the oxygen atoms contained in the oxygen-containing organic compound to the mass of the oxygen-containing organic compound is less than 0.320.

[0018] Note that the control valve type battery is also referred to as a VRLA (Valve-regulated lead-acid battery) or a sealed battery.

[0019] The control valve type lead-acid battery described in (1) above can achieve high capacity and suppress PCL. Therefore, the capacity maintenance rate is improved when the charge and discharge cycles are repeated.

[0020] The control valve type lead-acid battery described in (1) above satisfies the following conditions (A) to (D) as described above. [[ID=1⑧]](A) The separator is a non-woven fabric containing glass fibers. (B) The density of the positive electrode material is 3.3 g / cm 3 or more and 4.0 g / cm 3 or less. (C) The negative electrode material contains a predetermined oxygen-containing organic compound (hereinafter, also referred to as "oxygen-containing organic compound (P)"). (D) The ratio of the pore volume Vs (pores between 0.01 μm and 1 μm) to the total pore volume Vn of the negative electrode material (Vs / Vn) is between 0.27 and 0.64.

[0021] Furthermore, the oxygen-containing organic compound (P) satisfies the following conditions (C1) to (C4).

[0022] (C1) 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.

[0023] (C2) 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.

[0024] (C3) All oxygen atoms in the oxygen-containing organic compound (P) are contained in at least one of the ether bond and the hydroxyl group.

[0025] (C4) 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.

[0026] In valve-regulated lead-acid batteries that satisfy conditions (A) and (B), the low density of the positive electrode material usually allows the electrolyte (i.e., sulfate ions) to easily diffuse to the vicinity of the positive electrode current collector on the positive electrode plate. This can lead to a phenomenon called PCL (Potential Cement Linear Lithium), where insulating lead sulfate accumulates between the positive electrode current collector and the positive electrode material, causing a premature decrease in capacity.

[0027] In contrast, when conditions (C) and (D) are met, the liquid retention of the negative electrode material is improved, the diffusion of sulfate ions into the positive electrode material is suppressed, and PCL is suppressed.

[0028] Oxygen-containing organic compounds (P) that satisfy conditions (C1) to (C4) have moderate hydrophilicity. Therefore, when oxygen-containing organic compounds (P) are included in the negative electrode material, the amount of electrolyte held on the negative electrode plate increases, and the decrease in electrolyte volume due to battery use is suppressed. Furthermore, when condition (D) is satisfied, the proportion of micropores in the negative electrode material is large, which increases the retention of the negative electrode plate by capillary action. As a result, the movement of electrolyte to the positive electrode plate is reduced, and the diffusion of sulfate ions near the positive electrode current collector decreases. If only one of conditions (C) and (D) is satisfied, the effect of suppressing the movement of electrolyte to the positive electrode plate is small, and it is difficult to effectively suppress PCL.

[0029] Normally, increasing the density of the positive electrode material improves resistance to PCL, but the density of the positive electrode material is 4.0 g / cm³. 3 When the density exceeds 3.3 g / cm³, the diffusivity of the electrolyte in the positive electrode material decreases. As a result, the utilization rate of the active material in the positive electrode material decreases, making it difficult to improve the battery capacity. On the other hand, when the density of the positive electrode material is 3.3 g / cm³ 3 Below this level, the electrolyte retention of the positive electrode plate increases, making it difficult to maintain a good balance of electrolyte volume in the positive electrode plate, negative electrode plate, and separator, and thus making it difficult to maintain capacity when repeating charge-discharge cycles.

[0030] The applications of valve-regulated lead-acid batteries are not particularly limited, but the above effects can be particularly noticeable in power sources or stationary batteries for small mobility devices (e.g., motorcycles).

[0031] (2) In the valve-regulated lead-acid battery described in (1) above, the content Cpm of the oxygen-containing organic compound (P) in the negative electrode material may be 0.01% by mass or more and 0.1% by mass or less.

[0032] In the valve-regulated lead-acid battery described in (2) above, a sufficient amount of oxygen-containing organic compound (P) can be incorporated into the negative electrode material without significantly increasing the resistance of the negative electrode plate. Therefore, the effect of the oxygen-containing organic compound (P) in enhancing the liquid retention of the negative electrode material is fully realized, and PCL is significantly suppressed.

[0033] (3) In the valve-regulated lead-acid battery described in (1) or (2) above, the density of the positive electrode material is 3.43 g / cm³. 3 More than 4.0g / cm 3 The following is also acceptable.

[0034] In the valve-regulated lead-acid battery described in (3) above, the electrolyte retention of the positive electrode plate is optimized, and the balance of electrolyte volume in the positive electrode plate, negative electrode plate, and separator can be maintained more effectively. Therefore, the capacity retention rate is improved when the charge-discharge cycle is repeated.

[0035] (4) In the valve-regulated lead-acid battery described in any one of (1) to (3) above, the Vs / Vn ratio may be 0.36 or more and 0.64 or less.

[0036] In the valve-regulated lead-acid battery described in (4) above, the electrolyte retention of the negative electrode plate is further optimized, and the balance of electrolyte volume in the positive electrode plate, negative electrode plate, and separator can be maintained even better. Therefore, the capacity retention rate is further improved when the charge-discharge cycle is repeated.

[0037] The oxygen-containing organic compound (P) may have the following characteristics: (c1) The LC / MS spectrum of the oxygen-containing organic compound (P) measured with chloroform as the solvent preferably has 10 or more peaks, and more preferably 15 or more, in the region where the m / z value is between 400 and 1200. Since such an oxygen-containing organic compound (P) has a particularly good balance of hydrophilicity and hydrophobicity, it can maintain good liquid retention of the negative electrode plate.

[0038] (c2) 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.

[0039] 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.

[0040] (c3) 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 with 10 to 20 carbon atoms in the terminal alkyl group or terminal alkenyl group are thought to exhibit suitable hydrophobicity.

[0041] (c4) 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 pairs of electrons on the oxygen atoms. Furthermore, the oxygen content (PO) of the oxygen-containing organic compound (P) can be easily controlled within a suitable range.

[0042] (c5) The oxygen-containing organic compound (P) may be, for example, at least one selected from the group consisting of polyoxyethylene oleyl ether, polyoxyethylene tridecyl ether, and polyoxyethylene cetyl ether. These are stable in sulfuric acid, are not easily decomposed, have good hydrophilicity, and have a good balance of hydrophilicity and hydrophobicity.

[0043] In this specification, a fully charged state of a valve-regulated lead-acid battery is defined as a 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 (unit: 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 reaches a value (A) equal to 0.005 times the value (unit: Ah) stated in the rated capacity. A fully charged lead-acid battery refers to a lead-acid battery that has been fully charged after chemical formation. Full charging of a lead-acid battery may be performed immediately after chemical formation, or after some time has passed since chemical formation (for example, a lead-acid battery that has been chemically formed and is in use (preferably in the early stages of use) may be fully charged). An early-stage battery refers to a battery that has not been in use for very long and has hardly deteriorated.

[0044] The following describes the analysis of the negative electrode plate.

[0045] ≪Oxygen-containing organic compound (P)≫ Prior to measurement or analysis, a fully charged lead-acid battery is disassembled to obtain the negative electrode plate to be analyzed.

[0046] The obtained negative electrode plate is washed with water to remove sulfuric acid. Washing is continued until a pH test paper is pressed against the surface of the washed negative electrode plate and the color of the test paper does not change. However, the washing time should be no more than 2 hours. The washed negative electrode plate is dried under reduced pressure at 60±5℃ for about 6 hours. If the negative electrode plate contains adhesive material after drying, the adhesive material is removed by peeling. A sample for analysis (hereinafter referred to as Sample A) is taken from the dried negative electrode material. Sample A is taken from near the center in the planar direction of the negative electrode plate.

[0047] <Quantitative analysis> For the analysis, pulverized sample A is used. 5.0 ± 0.1 g of sample A 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.

[0048] <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.

[0049] 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

[0050] 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).

[0051] ≪Vs / Vn ratio≫ The ratio (Vs / Vn) of the integrated pore volume Vs (pores between 0.01 μm and 1 μm) to the total pore volume Vn of the negative electrode material is determined from the integrated pore volume distribution obtained by the mercury intrusion method. Specifically, an unground sample A 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 30,000 psia (≒20,700 kPa) to measure the pore volume distribution in the range of pore diameters between 5.5 nm and 333 μm. For the measuring device, for example, an automatic porosimeter (Autopore IV9510) manufactured by Shimadzu Corporation can be used. From the measurement results, the total pore volume Vn in the region with a pore diameter of 5.5 nm or more and 333 μm or less, and the integrated pore volume Vs in the region with a diameter of 0.01 μm or more and 1 μm or less are determined, and the Vs / Vn ratio is calculated by dividing Vs by Vn.

[0052] The following describes the analysis of the positive electrode plate.

[0053] ≪Density of positive electrode material≫ Density Dp (g / cm³) of positive electrode material 3 The pH is determined for a positive electrode plate removed from a fully charged lead-acid battery. The removed positive electrode plate is washed with water to remove sulfuric acid. Washing is continued until a pH test paper is pressed against the surface of the washed positive electrode plate and the color of the test paper does not change. The washed positive electrode plate is dried at 60±5℃ until completely dry. If the positive electrode plate contains adhesive material after drying, the adhesive material is removed by peeling. Next, the positive electrode material is separated from the positive electrode plate to obtain an unground sample (hereinafter referred to as sample B), and the mass of sample B (approximately 10g) is measured.

[0054] Sample B is taken from near the center of the positive electrode plate in the plane direction. If the electrode plate group contains one positive electrode plate, the unground sample is taken from that positive electrode plate. If the electrode plate group contains two positive electrode plates, the density of the positive electrode material is the average of the values ​​obtained for the positive electrode material taken from each of the two positive electrode plates. If the electrode plate group contains three positive electrode plates, the density of the positive electrode material is determined for the positive electrode material taken from the central positive electrode plate. If the electrode plate group contains four or more positive electrode plates, the density of the positive electrode material is the average of the values ​​obtained for the positive electrode material taken from two positive electrode plates arbitrarily selected from the positive electrode plates other than those at the ends of the electrode plate group.

[0055] The density Dp is calculated by dividing the mass of the positive electrode material by the "bulk volume" determined by the mercury intrusion method (g / cm³). 3 Specifically, an unground sample (approximately 10g) is placed in the measuring container of a mercury porosimeter, evacuated under reduced pressure, and then filled with mercury at a pressure of 0.5 psia (≒3.45kPa) to 0.55 psia (≒3.79kPa) to measure the "bulk volume" of the sample. For example, an automatic porosimeter (Autopore IV9510) manufactured by Shimadzu Corporation can be used as the measuring device. The "bulk volume" is defined as the volume of the measuring container minus the volume of mercury injected.

[0056] 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.

[0057] The following describes examples of components of a valve-regulated lead-acid battery.

[0058] (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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] (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.

[0065] 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.

[0066] 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.

[0067] 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, an oxygen-containing organic compound, water, and sulfuric acid. The negative electrode paste may optionally contain organic shrinkage inhibitors, carbonaceous materials, barium sulfate, etc.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] The carbonaceous material content in the negative electrode material is, for example, 0.1% by mass or more and 3% by mass or less.

[0074] The barium sulfate content in the negative electrode material is, for example, 0.1% by mass or more and 3% by mass or less.

[0075] The oxygen-containing organic compound (P) can be added to the negative electrode paste, but the method for incorporating the oxygen-containing organic compound (P) into the negative electrode material is not particularly limited.

[0076] The oxygen-containing organic compound content (Cpm) in the negative electrode material is preferably 0.01% by mass or more, may be 0.02% by mass or more, or 0.035% by mass or more. Furthermore, the Cpm content is preferably 0.1% by mass or less, may be 0.05% by mass or less, or 0.04% by mass or less. The Cpm content may be in the range of, for example, 0.01% by mass to 0.1% by mass, 0.01% by mass to 0.05% by mass, or 0.02% by mass to 0.05% by mass.

[0077] (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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] (electrolyte) The electrolyte is an aqueous solution containing sulfuric acid, and may be gelled if necessary. The electrolyte may also contain metal cations such as Na ions, Li ions, Mg ions, and Al ions, if necessary.

[0082] 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 result: 1.32 g / cm³ 3 The following is preferable:

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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).

[0087] [Example] Hereinafter, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.

[0088] First, the evaluation method of the control valve type lead-acid battery will be described. For the evaluation, a lead-acid battery (nominal voltage 12V) having a plate group including two positive plates and three negative plates and six cells is used. Here, a control valve type lead-acid battery with a rated 20-hour rate capacity of 38 Ah is used. Hereinafter, the evaluation method will be described.

[0089] Note that the current (A) of 1 / n of the numerical value of Ah described in the rated capacity is called the n-hour rate current (I n ). I n is a current value (unit: A) corresponding to the value obtained by dividing the rated n-hour rate capacity (unit: Ah) of the battery by n. Therefore, the 10-hour rate current I 10 is the current (A) of 1 / 10 of the numerical value of Ah described in the rated capacity.

[0090] [PCL acceleration test] Every time the charge and discharge under the following condition (i) are repeated 20 cycles at 40 °C, the capacity test under the following condition (ii) is performed at 25 °C. The ratio of the discharge capacity in the capacity test under condition (ii) after 40 cycles of charge and discharge under condition (i) to the initial discharge capacity is obtained as the capacity retention rate.

[0091] (Condition (i)) (40 °C) Discharge: I 10 Discharge for 1.5 hours Charge: I 10 Charge for 1.2 hours and then continue to charge for 5.5 hours at 0.15×I 10

[0092] (Condition (ii)) (25 °C) Discharge: I 10 (Discharge cut-off voltage (F.V.) = 1.8 V / cell) Charge: I 10 Charge 135% of the discharge charge amount

[0093] 《Lead acid batteries C1~C8, E1~E5》 (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.

[0094] (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, sulfuric acid, and, if necessary, an oxygen-containing organic compound (P). 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 Vs / Vn ratio of the negative electrode material is controlled 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.

[0095] 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 mixture, they are, for example, 0.2% by mass, 0.4% by mass, and 0.1% by mass, respectively. The content of oxygen-containing organic compounds (P), Cpm, is adjusted so that, when measured in the fully charged state of the pre-formulated mixture, it is 0.01% by mass to 0.1% by mass.

[0096] <Oxygen-containing organic compounds (P)> As the oxygen-containing organic compound (P), the following polyoxyethylene alkyl / alkenyl ethers that satisfy conditions (C1) to (C4) were used.

[0097] (i) POE / TDE (Polyoxyethylene Tridecyl Ether) Peak interval (m / z) = 20-25 (22) or 40-50 (44) Oxygen content (PO)=0.309 Oxygen atom = ether group, hydroxyl group

[0098] (ii) POE / STE (Polyoxyethylene cetyl ether) Peak interval (m / z) = 20-25 (22) or 40-50 (44) Oxygen content (PO)=0.318 Oxygen atom = ether group, hydroxyl group

[0099] (3) Separator AGM with a glass fiber content of 90% by mass is used as the separator.

[0100] (4) Preparation of electrolyte A sulfuric acid aqueous solution 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.

[0101] (5) Manufacturing of lead-acid batteries A valve-regulated lead-acid battery satisfying the various parameters shown in Table 1 will be manufactured. Specifically, two unformed positive plates and three unformed negative plates will be alternately stacked with an AGM 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 20-hour rate capacity of 38Ah as described above.

[0102] (6) Evaluation The fabricated lead-acid battery was fully charged, and the capacity retention rate was determined using the method described above. The evaluation results are shown in Table 1. A higher value indicates a better cycle life.

[0103] [Table 1]

[0104] Table 1 shows the density Dp of the positive electrode material at 3.43 g / cm³. 3This shows the change in capacity retention rate when the initial Vs / Vn ratio is changed while keeping the initial Vs / Vn ratio constant. When oxygen-containing organic compounds (P) are not used (C1-C6), no significant change is observed in the discharge capacity retention rate even when the Vs / Vn ratio changes. On the other hand, when oxygen-containing organic compounds (P) are used, the capacity retention rate improves in the range where the Vs / Vn ratio is 0.27 or higher.

[0105] It is expected that increasing the number of micropores in the negative electrode material will improve the electrolyte retention of the negative electrode plate due to capillary action. Normally, in valve-regulated lead-acid batteries, the pores in the negative electrode material become coarser and the pores in the positive electrode material become finer as the usage time progresses. As a result, the electrolyte easily moves to the positive electrode plate. In other words, the diffusion of sulfate ions to the vicinity of the positive electrode current collector is promoted, and PCL occurs. On the other hand, it is thought that adding an oxygen-containing organic compound (P) to the negative electrode material suppresses the coarsening of the pores in the negative electrode material, and because the oxygen-containing organic compound (P) has appropriate hydrophilicity, the electrolyte retention of the negative electrode plate is maintained, the distribution balance of the electrolyte is maintained well, PCL due to the diffusion of sulfate ions to the positive electrode plate is suppressed, and the capacity retention rate is improved.

[0106] 《Lead acid battery E6~E7, C9~C20》 A battery was fabricated and evaluated in the same manner as the previously described battery (e.g., battery E1), except that the oxygen-containing organic compound (P) was changed to the following compound. The results are shown in Table 2.

[0107] (iii) Oleic acid Oxygen content (PO)=0.113

[0108] (iv) PPG (Polyoxypropylene Glycol) Peak interval (m / z) = 58 Oxygen content (PO)=0.283

[0109] (v) PEG oleate (polyoxyethylene oleyl ester) Peak interval (m / z) = 44 Oxygen content (PO)=0.240

[0110] (vi) POE / LE (Polyoxyethylene Lauryl Ether) Peak interval (m / z) = 22, 44 Oxygen content (PO)=0.320

[0111] [Table 2]

[0112] Table 2 shows the density Dp of the positive electrode material at 3.43 g / cm³. 3 The figures show the change in capacity retention rate when the type of organic compound is changed, with the initial Vs / Vn ratio set to 0.27 or 0.62, while keeping the initial Vs / Vn ratio constant. No significant change in capacity retention rate is observed when compounds that do not satisfy conditions (C1) to (C4) are used. An improvement in capacity retention rate is observed only when an oxygen-containing organic compound (P) that satisfies conditions (C1) to (C4) is used. This suggests that the oxygen-containing organic compound (P) contained in the negative electrode plate has appropriate hydrophilicity, and the stability of the oxygen-containing organic compound (P) contributed to the improvement in capacity retention rate.

[0113] 《Lead acid batteries E8~E12, C21~C32》 Except for changing the density of the positive electrode material as shown in Table 3, 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.

[0114] [Table 3]

[0115] Table 3 shows the change in capacity retention rate when the Vs / Vn ratio and the density Dp of the positive electrode material are changed. 3 More than 4.0g / cm 3 The capacity retention rate increases in the following case: when the density Dp of the positive electrode material is 3.3 g / cm³. 3 If the value is less than 4.0 g / cm³, the diffusion of sulfate ions into the positive electrode current collector cannot be suppressed, and no improvement in capacity retention rate is observed even when using oxygen-containing organic compounds (P). On the other hand, if the density Dp of the positive electrode material is 4.0 g / cm³,3 If the value exceeds this, the diffusion of sulfate ions to the positive electrode plate becomes too slow, the distribution balance of the electrolyte in the electrode group deteriorates, and the effect of improving the capacity retention rate becomes insufficient. [Industrial applicability]

[0116] 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]

[0117] 1:Lead acid battery 2: Negative plate 3: Positive plate 4: Separator 11: Plate group 10: Battery case 10R: Cell chamber 13: Exhaust valve

Claims

1. The device comprises 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 separator is a nonwoven fabric containing glass fibers. The positive electrode plate includes a positive electrode material, The aforementioned negative electrode plate includes a negative electrode material, The density of the positive electrode material is 3.3 g / cm³. ３ 4.0g / cm or more ３ The following: The ratio of the cumulative pore volume Vs (pores with a diameter of 0.01 μm or more and 1 μm or less) to the total pore volume Vn of the negative electrode material (Vs / Vn) is 0.27 or more and 0.64 or less. 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. A valve-regulated lead-acid battery in which 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.

2. The valve-regulated lead-acid battery according to claim 1, wherein the content Cpm of the oxygen-containing organic compound in the negative electrode material is 0.01% by mass or more and 0.1% by mass or less.

3. The density of the positive electrode material is 3.43 g / cm³. ３ 4.0g / cm or more ３ The following is: The valve-regulated lead-acid battery according to claim 1.

4. The valve-regulated lead-acid battery according to claim 1, wherein the Vs / Vn ratio is 0.36 or more and 0.64 or less.

Images