Lead-acid battery

Abstract

This lead-acid battery is provided with a positive electrode plate, a negative electrode plate, an electrolyte solution, and a separator interposed between the positive electrode plate and the negative electrode plate. The positive electrode plate contains a positive electrode material, the positive electrode material contains fibers, and the surface area of the fibers per 1 g of the positive electrode material is 1.35 cm2 or more.

Description

lead acid battery 【0001】 This invention relates to a lead-acid battery. 【0002】 Patent Document 1 states that "the density of the active material after chemical conversion is 4.5 g / cm³." ３ In the positive electrode plate for a lead-acid battery described above, the amount of pure sulfuric acid added during the mixing of the positive electrode paste is 2.0% by mass or more and 4.5% by mass or less relative to the mass of lead powder, and furthermore, the amount of red lead added is 5.0% by mass or more and 25.0% by mass or less relative to the total amount of lead powder and red lead, and it is proposed that short fibers made of polyethylene terephthalate be added to the positive electrode plate at an amount of 0.09% by mass or more and 0.20% by mass or less relative to the mass of lead powder. 【0003】 Patent Document 2 proposes a "positive electrode plate for a lead-acid battery, comprising a positive electrode current collector and a positive electrode active material held by the positive electrode current collector, wherein the positive electrode active material includes fibers with a liquid retention rate of 125% or more." 【0004】 Patent Document 3 proposes a lead-acid battery comprising a paste-type positive electrode plate, a retainer or separator, and a paste-type negative electrode plate laminated together, characterized in that the paste-type positive electrode plate and / or the paste-type negative electrode plate contain hydrophilic short fibers. 【0005】 Japanese Patent Publication No. 2017-183283, Japanese Patent Publication No. 2021-061235, Japanese Patent Publication No. 2006-004688 【0006】 To improve the utilization rate of the positive electrode material, it has been proposed to add fibers to the positive electrode material (see Patent Documents 1-3). In recent years, with the advent of OTA (Over The Air) technology, the load on lead-acid batteries has been increasing. Repeated deep charge-discharge cycles make the positive electrode material of lead-acid batteries more prone to softening and detachment, leading to a premature end of life for the battery. 【0007】 One aspect of the present invention comprises a positive electrode plate, a negative electrode plate, an electrolyte, and a separator interposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate includes a positive electrode material, the positive electrode material includes fibers, and the surface area of ​​the fibers per gram of the positive electrode material is 1.35 cm². ２That concludes the discussion regarding lead-acid batteries. 【0008】 The lead-acid battery according to the present invention can ensure good lifespan performance when repeatedly performing deep depth charge and discharge cycles. 【0009】 This is a schematic diagram showing an example of a positive electrode current collector according to one embodiment of the present invention. This is an enlarged view of a part of the grid portion of Figure 2A. This is a partially cutaway perspective view showing the external appearance and internal structure of a lead-acid battery according to one embodiment of the present invention. This is an SEM image showing the external appearance of an example of polyester fiber. This is an SEM image showing the external appearance of an example of acrylic fiber. 【0010】 While novel features of the present invention are described in the appended claims, the present invention, both in terms of its structure and content, will be better understood by the following detailed description in conjunction with the drawings, in conjunction with other objects and features of the present invention. 【0011】 The embodiments of this disclosure will be described below with examples, but this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of this disclosure are obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "greater than or equal to numerical value A and less than or equal to numerical value B". In the following description, when lower and upper limits of numerical values ​​relating to specific physical properties or conditions are given as examples, either of the given lower limits and either of the given upper limits can be arbitrarily combined, as long as the lower limit is not greater than or equal to the upper limit. When multiple materials are given as examples, one of them may be selected and used alone, or two or more may be used in combination. 【0012】 Furthermore, this disclosure encompasses any combination of matters described in two or more claims, which may be arbitrarily selected from the multiple claims set forth in the attached claims. In other words, any combination of matters described in two or more claims, which may be arbitrarily selected from the multiple claims set forth in the attached claims, is possible, provided that no technical inconsistency arises. 【0013】The lead-acid battery according to this disclosure can more significantly improve the deep discharge life in liquid-type batteries (vented batteries) where softening and detachment of the positive electrode material are prone to occur. However, the lead-acid battery according to this disclosure may also be a valve-regulated lead-acid battery (VRLA type battery). 【0014】 A lead-acid battery comprises a positive electrode plate, a negative electrode plate, a separator interposed between the positive and negative electrode plates, and an electrolyte. The electrolyte contains sulfuric acid. Charging and discharging proceed through the movement of sulfate ions between the positive and negative electrode plates and the electrolyte. During discharge, sulfate ions move to the positive and negative electrode plates. During charging, sulfate ions move from the positive and negative electrode plates into the electrolyte. 【0015】 The positive electrode plate, the negative electrode plate, and the separator constitute an electrode group. The electrode group, together with the electrolyte, constitutes a cell. One electrode group constitutes one cell. A lead-acid battery comprises one or more cells by comprising one or more electrode groups. There is no particular limit to the number of positive and negative electrode plates included in one electrode group. An electrode group comprising a lead-acid battery according to this disclosure may include, for example, a total of 12 or more positive and negative electrode plates. Multiple electrode groups are usually housed in separate cell chambers and connected in series with one another. 【0016】 The positive electrode plate includes a positive electrode material. The positive electrode material, as a positive electrode active material that exhibits capacity through oxidation-reduction reactions, contains at least lead dioxide during charging and at least lead sulfate during discharge. 【0017】 The negative electrode plate includes a negative electrode material. The negative electrode material is a negative electrode active material that exhibits capacity through an oxidation-reduction reaction, and contains at least lead during charging and at least lead sulfate during discharging. 【0018】 (1) A lead-acid battery according to an embodiment of the present disclosure comprises a positive electrode plate, a negative electrode plate, an electrolyte, and a separator interposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode material includes fibers, and the surface area of ​​the fibers per gram of the positive electrode material is 1.35 cm². ２ The above concerns lead-acid batteries. The fibers function as a reinforcing material for the positive electrode material. 【0019】In the lead-acid battery described in (1) above, the bonding force between the positive electrode materials is significantly enhanced by the use of fibers. Therefore, even when repeated deep charge-discharge cycles (DOD), softening and detachment of the positive electrode material are suppressed, ensuring good lifespan performance. 【0020】 The lifespan performance when repeatedly performing deep-depth charge-discharge cycles can be evaluated using "Lifespan Test Method A" described later. 【0021】 In the charged state, the positive electrode material forms a network of bonded lead dioxide particles. When the discharge reaction changes the lead dioxide to lead sulfate, its volume expands by approximately 1.5 times. Repeated charge-discharge cycles with deep discharge depths typically cause the bonds between lead compound particles in the positive electrode material to break, isolating some of the lead compounds. As a result, softening progresses from the surface of the positive electrode plate, leading to the detachment of the positive electrode material. To suppress such softening and detachment, it is considered necessary that the contact area between the fibers (i.e., reinforcing material) contained in the positive electrode material and the positive electrode material itself be sufficiently large. 【0022】 The surface area of ​​the fibers per gram of positive electrode material is 1.35 cm². ２ In the above case, the contact area between the lead compound constituting the positive electrode material and the fibers is also approximately 1.35 cm² per gram of positive electrode material. ２ It can be concluded that, due to the large contact area between the fibers and the lead compound, the binding force between the lead compounds is increased, and the deep discharge life of the lead-acid battery is significantly improved. 【0023】 The surface area of ​​fibers per gram of positive electrode material is calculated as the surface area of ​​the fibers contained in 1 gram of positive electrode material. Specifically, if X grams of positive electrode material contains Y grams of fibers, and the surface area of ​​Y grams of fibers is Z cm², then... ２ In this case, the surface area of ​​the fibers per gram of positive electrode material is Z / X (cm²). ２ / (g)). Assuming that the shape of the fiber is cylindrical with a length L, when the average fiber diameter is D, the surface area of one fiber is calculated as πDL. When the positive electrode material W g contains N fibers, the surface area of the fibers per gram of the positive electrode material is calculated as NπDL / W. Also, since the volume of a cylinder with a surface area of NπDL is π(D / 2) ２ NL, in the case of a fiber density d (g / cm ３ ), if the mass w of the fibers contained in the positive electrode material W g and the average fiber diameter D are known, from the relational expression of w / d = π(D / 2) ２ NL, NL (= w / d·π(D / 2) ２ ) can be obtained, and NπDL / W can be calculated. 【0024】 Here, the fiber density d (g / cm ３ ) is the standard fiber density described in books or technical materials. A resin sample can be prepared and measured in accordance with the "Method for Measuring the Density and Specific Gravity of Plastics - Non-Foamed Plastics" specified in JIS K 7112:1999. For example, the "3rd Edition Fiber Handbook" edited by the Fiber Society of Japan and published by Maruzen Publishing Co., Ltd. (2004) lists the specific gravity of fibers. The numerical value of the specific gravity of the fiber coincides with the numerical value of the fiber density d. When there is a range in the fiber density or specific gravity described in books or technical materials, the average value of the described numerical range may be used as the fiber density d. For example, the "3rd Edition Fiber Handbook" states that the specific gravity of acrylic fibers is 1.14 to 1.17. In that case, the fiber density d (g / cm ３ ) of acrylic fibers may be regarded as 1.155 ≈ 1.16 (g / cm ３ ). 【0025】 The type of resin constituting the fibers contained in the positive electrode material can be identified by analyzing the fibers recovered from the positive electrode material by the method described in JIS L 1030-1:2024. Fibers may be recovered by pulling them out with tweezers from the positive electrode material, or fibers may be recovered from the residue after dissolving the lead compounds contained in the positive electrode material. 【0026】(2) In the lead-acid battery described in (1) above, the surface area of ​​the fibers per gram of the positive electrode material is 1.70 cm². ２ It is preferable that the above conditions are met. 【0027】 In the lead-acid battery described in (2) above, the fibers and lead compounds are intertwined over an even larger contact area, which significantly increases the bonding force between the lead compounds and further improves the deep discharge life of the lead-acid battery. 【0028】 (3) In the lead-acid battery described in (1) or (2) above, the cumulative pore volume of the positive electrode material in the range of pore diameter 0.006 μm to 15 μm is 0.167 cm³. ３ It may be less than / g. 【0029】 In the lead-acid battery described in (3) above, the cumulative pore volume of the positive electrode material in the range of pore diameters from 0.006 μm to 15 μm is 0.167 cm³. ３ Because the density is less than / g, the density of the positive electrode material is relatively high, and the positive electrode material is less likely to collapse. Therefore, the cumulative pore volume of the positive electrode material in the range of pore diameter 0.006 μm to 15 μm is 0.167 cm³. ３ The density is less than or equal to / g, and the surface area of ​​the fibers per gram of positive electrode material is 1.35 cm². ２ In the above cases, the effect of improving lifespan performance is significantly demonstrated. 【0030】 (4) In the lead-acid battery described in any one of (1) to (3) above, the cumulative pore volume of the positive electrode material in the range of pore diameter 0.006 μm to 15 μm is 0.080 cm³. ３ / g or more, 0.130cm ３ It may be less than / g. 【0031】 In the lead-acid battery described in (4) above, the density of the positive electrode material is high, and the structure of the positive electrode material is less prone to collapse. Therefore, the effect of improving the deep discharge life by using fibers becomes even more pronounced. In addition, the cumulative pore volume of the positive electrode material in the range of pore diameter 0.006 μm to 15 μm is 0.080 cm³. ３ When the concentration is greater than or equal to g / g, sufficient pore size is ensured, which increases the diffusivity of sulfate ions and makes it easier to achieve high output. 【0032】(5) In the lead-acid battery described in any one of (1) to (4) above, the fiber density is 1.40 g / cm³. ３ The following is preferable: 【0033】 In the lead-acid battery described in (5) above, the fiber density is sufficiently low, making it easy to design a large surface area of ​​fibers per gram of positive electrode material. As previously mentioned, the fiber density d (g / cm³) ３ In this case, if the mass w and average fiber diameter D of the fibers contained in the positive electrode material Wg are determined, the surface area of ​​the fibers per gram of the positive electrode material can be calculated. The smaller the fiber density d, the larger the surface area that can be secured with a smaller mass of fibers. The positive electrode paste containing the positive electrode material prepared in the manufacturing process of the positive electrode plate has better fluidity the smaller the fiber content in the positive electrode material. Therefore, if the fiber density is 1.40 g / cm³ ３ The following conditions make it easier to improve the bonding strength between positive electrode materials and improve the efficiency of the manufacturing process for positive electrodes. 【0034】 (6) In the lead-acid battery described in any one of (1) to (5) above, it is preferable that the surface of the fiber has irregularities. Furthermore, it is preferable that the irregularities on the surface of the fiber are formed along the circumferential direction of the fiber. The circumferential direction of the fiber is any direction that intersects the longitudinal direction of the fiber. Such a direction is, for example, a direction that has an angle of 45° or more on average with the longitudinal direction of the fiber. 【0035】 In the lead-acid battery described in (6) above, the surface area of ​​the fibers is increased due to the irregularities on the fiber surface, and the friction between the lead compound particles and the fibers is also increased. In particular, when the irregularities on the fiber surface are formed along the circumferential direction of the fiber, the friction is greater when the lead compound particles try to move in the longitudinal direction of the fiber. Therefore, it has a great effect in suppressing the expansion of the positive electrode material along the longitudinal direction of the fiber. 【0036】 (7) In the lead-acid battery described in (6) above, the surface irregularities of the fibers may be formed in a ripple pattern along the circumferential direction of the fibers. 【0037】In the lead-acid battery described in (7) above, the trajectories of the ripple-like irregularities extending on the surface of the fibers are long and the shape of the irregularities is complex. Therefore, such irregularities easily engage with lead compound particles that are trying to move in the longitudinal direction of the fibers. Thus, the effect of suppressing the expansion of the positive electrode material along the longitudinal direction of the fibers becomes even greater. 【0038】 The effect of suppressing softening and shedding by fibers can also depend on the material of the fibers. It is preferable that the fibers are made of a resin that is strong even when thin and stable in the presence of sulfuric acid. For example, fibers made of polyester and / or polyolefin satisfy these conditions. 【0039】 (8) In the lead-acid battery described in (1) to (7) above, the fiber content in the positive electrode material may be, for example, 0.01% by mass or more and 0.23% by mass or less, or 0.05% by mass or more and 0.21% by mass or less. 【0040】The fiber content in the positive electrode material may be, for example, 0.01% by mass or more and 0.21% by mass or less, 0.01% by mass or more and 0.18% by mass or less, 0.01% by mass or more and 0.15% by mass or less, 0.01% by mass or more and 0.12% by mass or less, 0.01% by mass or more and 0.10% by mass or less, 0.01% by mass or more and 0.07% by mass or less, 0.01% by mass or more and 0.05% by mass or less, or 0.03% by mass or more and 0.23% by mass. It may also be less than or equal to 0.03% by mass or more and 0.21% by mass or less, it may be 0.03% by mass or more and 0.18% by mass or less, it may be 0.03% by mass or more and 0.15% by mass or less, it may be 0.03% by mass or more and 0.12% by mass or less, it may be 0.03% by mass or more and 0.10% by mass or less, it may be 0.03% by mass or more and 0.07% by mass or less, it may be 0.05% by mass or more and 0.23% by mass or less, it may be 0.05% by mass or more and 0.18% by mass or less, and 0.05 It may be 0.15% by mass or more, 0.05% by mass or more and 0.12% by mass or less, 0.05% by mass or more and 0.10% by mass or less, 0.05% by mass or more and 0.07% by mass or less, 0.07% by mass or more and 0.23% by mass or less, 0.07% by mass or more and 0.21% by mass or less, 0.07% by mass or more and 0.18% by mass or less, 0.07% by mass or more and 0.15% by mass or less, 0.07% by mass or more and 0.12% by mass It may be less than or equal to %; it may be 0.07% by mass or more and 0.10% by mass or less; it may be 0.10% by mass or more and 0.23% by mass or less; it may be 0.10% by mass or more and 0.21% by mass or less; it may be 0.10% by mass or more and 0.18% by mass or less; it may be 0.10% by mass or more and 0.15% by mass or less; it may be 0.12% by mass or more and 0.23% by mass or less; it may be 0.12% by mass or more and 0.21% by mass or less; and it may be 0.12% by mass or more and 0.18% by mass or less. 【0041】 The lead-acid battery described in (8) above has very good fluidity of the positive electrode paste in the manufacturing process of the positive electrode plate, and the effect of improving the deep discharge life of the lead-acid battery by using fibers is significant. 【0042】 (9) In the lead-acid battery described in any one of (1) to (8) above, the resin constituting the fibers may be, for example, polyethylene terephthalate (hereinafter also referred to as "PET"). 【0043】 PET has excellent acid resistance and mechanical strength. Therefore, PET fibers can have a fine average fiber diameter, and even a small amount can secure a large surface area, which greatly improves the deep discharge life of lead-acid batteries. Furthermore, PET fibers are inexpensive. 【0044】 (10) In the lead-acid battery described in any one of (1) to (9) above, the average fiber diameter of the fibers may be 1 μm or more and 13 μm or less. 【0045】 The average fiber diameter of the fibers may be 1 μm or more and 11 μm or less, or 1 μm or more and 9 μm or less. 【0046】 In the lead-acid battery described in (10) above, the fibers are sufficiently fine, resulting in a large specific surface area. Therefore, the contact area between the lead compound constituting the positive electrode material and the fibers tends to be large, and the effect of improving the bonding strength between the positive electrode materials by the fibers is greatly enhanced. Consequently, a lead-acid battery with excellent deep discharge life performance can be provided. 【0047】 (11) In the lead-acid battery described in any one of (1) to (10) above, the average fiber diameter of the fibers may be 1 μm or more and 8 μm or less. 【0048】 The average fiber diameter of the fibers may be 1 μm or more and 7 μm or less, 1 μm or more and 6 μm or less, 1 μm or more and 5 μm or less, 2 μm or more and 8 μm or less, 2 μm or more and 7 μm or less, 2 μm or more and 6 μm or less, 2 μm or more and 5 μm or less, 3 μm or more and 8 μm or less, 3 μm or more and 7 μm or less, 3 μm or more and 6 μm or less, or 3 μm or more and 5 μm or less. 【0049】In the lead-acid battery described in (11) above, the fibers are even finer, resulting in a larger specific surface area. Therefore, the contact area between the lead compound constituting the positive electrode material and the fibers tends to increase, and the effect of the fibers on improving the bonding strength between the positive electrode materials becomes very significant. Consequently, a lead-acid battery with excellent deep discharge life performance can be provided. 【0050】 (12) In the lead-acid battery described in any one of (1) to (5) and (8) to (11) above, the average surface roughness Ra of the fibers may be 0.1 μm or more and 1.3 μm or less. 【0051】 Recent vehicles equipped with idle stop (IS) (or idle stop start (ISS)) systems are fitted with many electrical components such as drive recorders and electronic mirrors. In IS applications, lead-acid batteries are used in a state of undercharge called a partial charge state (PSOC). When lead-acid batteries are frequently charged and discharged in a PSOC state, the positive electrode material is prone to softening and detachment, leading to a premature end of life for the lead-acid battery. Adding fibers with a large specific surface area to the positive electrode material improves the lifespan performance when using lead-acid batteries as a power source for IS vehicles (hereinafter also referred to as "IS lifespan"), but there may be room for improvement in lifespan performance when subjected to repeated high-temperature overcharging (hereinafter also referred to as "high-temperature overcharge lifespan"). 【0052】 In the lead-acid battery described in (12) above, the average surface roughness Ra of the fibers contained in the positive electrode material is 0.1 μm or more, so the surface of the fibers has a moderate roughness. Fibers with a larger average roughness Ra can exhibit a higher anchoring effect, making it less likely for the positive electrode material to detach from the positive electrode plate, thus ensuring a good IS life. On the other hand, when the average surface roughness Ra of the fibers is 1.3 μm or less, the surface of the fibers does not have excessive irregularities. Therefore, even when high-temperature overcharging is repeated, oxidative degradation of the fiber surface is less likely to progress. As a result, a state of high adhesion between the fibers and the positive electrode material is maintained for a long period of time, and a good high-temperature overcharging life can also be ensured. 【0053】 The IS lifespan and high-temperature overcharge lifespan of lead-acid batteries can be evaluated using the "IS Lifespan Test Method" and "High-Temperature Overcharge Lifespan Test" described below. 【0054】 If the average surface roughness Ra of the fibers exceeds 1.3 μm, and the fiber surface has excessive irregularities, the positive electrode material can easily penetrate the depressions on the fiber surface, and the convex parts of the fiber surface can easily penetrate the gaps in the positive electrode material. As a result, the adhesion between the fibers and the positive electrode material increases. Since the positive electrode material is a strong oxidizing agent, if the adhesion between the fibers and the positive electrode material is too high, repeated high-temperature overcharging can easily lead to oxidative degradation of the fibers starting from the irregularities. More specifically, oxidative degradation mainly progresses on the convex parts of the fibers, making the fibers brittle and prone to breakage starting from the convex parts. This reduces the adhesion between the fibers and the positive electrode material, and it may become difficult to prevent the detachment of the positive electrode material. 【0055】 The inventors believed that the larger the specific surface area of ​​the fibers, the more effectively the softening and shedding of the positive electrode material could be suppressed. However, the inventors discovered that the effect of suppressing the softening and shedding of the positive electrode material could be further enhanced not only by increasing the specific surface area of ​​the fibers, but also by controlling the average surface roughness Ra of the fiber surface. This is because, by increasing the specific surface area of ​​the fibers while limiting the irregularities on the fiber surface that are prone to oxidative degradation, the phenomenon of the fibers being oxidized by the positive electrode material, mainly during high-temperature overcharging, is suppressed. Controlling the average surface roughness Ra of the fibers is effective in suppressing oxidative degradation of the fibers. 【0056】 When the average surface roughness Ra of the fibers is controlled to be between 0.1 μm and 1.3 μm, the fibers can have a sufficient anchoring effect and ensure good oxidation resistance. As a result, it becomes possible to obtain a lead-acid battery with excellent IS life and high-temperature overcharge life. More preferably, the average surface roughness Ra of the fibers may be between 0.2 μm and 1.3 μm, between 0.3 μm and 1.3 μm, between 0.1 μm and 1.0 μm, between 0.2 μm and 1.0 μm, between 0.3 μm and 1.0 μm, between 0.1 μm and 0.8 μm, between 0.2 μm and 0.8 μm, or between 0.3 μm and 0.8 μm. 【0057】The high-temperature overcharge life of lead-acid batteries can be evaluated in the "high-temperature overcharge life test" described below. 【0058】 (13) In a lead-acid battery described in any one of (1) to (12) above, the BET specific surface area measured using krypton gas as the adsorbent gas is 0.3 m² ２ / g or more 1.0m ２ It may be less than / g. 【0059】 In the lead-acid battery described in (13) above, the BET specific surface area measured using krypton gas from the fibers contained in the positive electrode material as the adsorbent gas is 0.3 m². ２ Because the particle size is moderately large, at or above 1 / g, a sufficient contact area with the positive electrode material can be secured, resulting in a high effectiveness in suppressing the shedding of the positive electrode material. Furthermore, when the average surface roughness Ra of the fibers is between 0.1 μm and 1.3 μm, the surface of the fibers tends to be smooth, the number of protrusions that can be formed on the surface of the fibers is small, and oxidative degradation by the positive electrode material is less likely to progress. With such fibers, a sufficient contact area with the positive electrode material can be secured while oxidative degradation by the positive electrode material is less likely to progress. In other words, a good balance between the anchoring effect and oxidation resistance of the fibers can be easily secured. 【0060】 Furthermore, the BET specific surface area of ​​the fiber measured using krypton gas as the adsorption gas was 1.0 m². ２ When the density is less than / g, contact between the fibers and the positive electrode material is moderately suppressed, making it difficult for the insulating fibers to interrupt the conductive path. Therefore, the conductive path of the positive electrode material is easily secured. As a result, the positive electrode plate can ensure good conductivity, and it becomes possible to obtain a lead-acid battery with superior IS life. 【0061】 As described above, the BET specific surface area of ​​the fiber measured using krypton gas as the adsorption gas is 0.3 m². ２ / g or more 1.0m ２ By controlling the load to less than / g, it becomes possible to obtain a lead-acid battery with superior performance in both IS lifespan and high-temperature overcharge lifespan. 【0062】(14) In the lead-acid battery described in (12) or (13) above, the fiber content in the positive electrode material may be 0.05% by mass or more and 0.23% by mass or less. 【0063】 In the lead-acid battery described in (14) above, the effect of the fibers is fully realized, making it possible to obtain a lead-acid battery with even better IS life and high-temperature overcharge life. Furthermore, because the fiber content in the positive electrode material is appropriate, the insulating fibers are less likely to interrupt the conductive path. Therefore, the conductive path of the positive electrode material is easily secured. Thus, the positive electrode plate can ensure good conductivity, making it possible to obtain a lead-acid battery with superior IS life. 【0064】 (Method for measuring the average surface roughness Ra of fibers) The average surface roughness Ra of fibers is determined by the following procedure. Fibers taken from the positive electrode material of a fully charged lead-acid battery are used for the measurement. 【0065】 The positive electrode material is recovered from the positive electrode plate by the following procedure. First, a fully charged lead-acid battery is disassembled, and the obtained positive electrode plate is washed with water for 3 to 4 hours to remove the electrolyte from the positive electrode plate. The washed positive electrode plate is then dried in a constant temperature bath at 60°C ± 5°C for at least 5 hours. 【0066】 A separator made of an adhesive material containing fibers, such as a mat, and / or a nonwoven fabric may be attached to the positive electrode plate. The fibers contained in the adhesive material and the nonwoven fabric are not included in the fibers of the present invention. If an adhesive material and / or a nonwoven fabric is attached to the positive electrode plate, the surface of the positive electrode plate is scraped off until the residue of the adhesive material and / or nonwoven fabric is removed, in order to prevent fibers derived from the adhesive material and / or nonwoven fabric from mixing into the positive electrode material, before the positive electrode material is taken. For example, the residue may be scraped evenly from the surface layers on both sides of the positive electrode plate before the positive electrode material is taken. In this case, it is desirable to scrape to a depth of about 0.03 mm to 0.20 mm per side. 【0067】 Subsequently, a sample of the positive electrode material for analysis is obtained by taking a sample of the positive electrode material from near the center of the positive electrode plate when viewed from the front, without crushing it. 【0068】 The fibers are recovered from the positive electrode material sample by the following procedure. First, the positive electrode material sample is crushed. At this time, the positive electrode material contained in one or more positive electrode plates may be used as the sample. 【0069】 Next, the pulverized sample is added to a mixed solution of acetic acid-sodium acetate solution and sodium thiosulfate solution (acetic acid concentration 1.7 mol / L, sodium acetate concentration 6.1 mol / L, sodium thiosulfate concentration 0.5 mol / L), and the soluble components are dissolved while stirring at room temperature. Then, the resulting residue is filtered using a membrane filter (average pore size: 0.45 μm or less). During filtration, the residue (fibers) is washed with deionized water. This allows the fibers contained in the positive electrode material to be obtained as solid matter on the filter paper. If carbonaceous material is contained in the obtained solid matter, only the fibers contained in the sample are recovered as solid matter by centrifuging or sieving. 【0070】 A fiber sample for analysis is obtained by washing and drying the resulting solid material. The average surface roughness Ra of the fiber is determined using a laser microscope in accordance with ISO 4287:1997. Specifically, an image for analysis is acquired with a 20x objective lens. The acquired image for analysis is subjected to automatic correction processing for noise reduction and tilt correction using an analysis application. An image for analysis is acquired from five or more fibers, and the analysis is performed using the line roughness measurement function of the analysis application to measure the surface roughness Ra of each fiber. The average surface roughness Ra of the fiber is determined by averaging the measured values ​​of five or more fibers. The analysis is performed with all filter conditions (F calculation, S filter, L filter) set to none. 【0071】 The following can be used as measuring equipment: Laser microscope: VK-X3000, manufactured by Keyence Corporation Objective lens: Plan x20 NA 0.46 WD 3.1 mm, manufactured by Nikon Corporation Analysis application: VK-A3, manufactured by Keyence Corporation 【0072】(Measurement of BET specific surface area) The BET specific surface area of ​​fibers measured using krypton gas as the adsorption gas is determined for fibers taken from the positive electrode material of a fully charged lead-acid battery. For the fiber sample for analysis obtained by the procedure described above, the BET specific surface area is determined using krypton gas as the adsorption gas in accordance with the calculation method for BET specific surface area in JIS Z 8830:2013, 7.2. 【0073】 The following can be used as measuring equipment. Preferred measuring conditions are also shown below. Measuring equipment: Shimadzu Corporation, Tristar II 3020 series; Adsorbent gas: Krypton gas with a purity of 99.99% or higher; Adsorption temperature: -196°C 【0074】 (Measurement of Fiber Content) The fiber content in the positive electrode material is determined from fibers collected from the positive electrode material of a fully charged lead-acid battery. First, the mass W (g) of the positive electrode material recovered by the procedure described above is measured in advance. Next, the mass w (g) of the fiber sample for analysis obtained from the positive electrode material mass W (g) by the procedure described above is measured. The ratio (percentage) of the mass w of the fiber sample to the mass W of the positive electrode material sample is the fiber content in the positive electrode material. 【0075】 (15) In the lead-acid battery described in any one of (1) to (5) and (8) to (14) above, the maximum surface height Rz of the fiber may be 0.17 μm or more and 1.90 μm or less. 【0076】 To improve the lifespan performance of deep discharges with relatively shallow DOD (e.g., DOD 12% or less), increasing the surface area of ​​the fibers per gram of positive electrode material is effective. On the other hand, to improve the lifespan performance of even deeper discharges (e.g., DOD 50% or more), this alone was sometimes insufficient. Such cases were observed when there were deep wrinkles on the surface of the fibers. Therefore, the inventors investigated improving the lifespan performance of deep discharges (e.g., DOD 50% or more) by controlling the maximum surface height Rz of the fibers. 【0077】If there are deep wrinkles on the surface of the fibers, the charge-discharge reaction may be inhibited if the positive electrode material enters the space inside the wrinkles, or if sulfate ions are trapped. Because the space inside the wrinkles has low ion diffusion, if the positive electrode material enters such a space, the uptake of sulfate ions by the positive electrode material and the release of sulfate ions from the positive electrode material become difficult to carry out. Therefore, in the space inside the wrinkles and in the vicinity of wrinkles that are susceptible to the effects of wrinkles, the charge-discharge reaction by the positive electrode material does not proceed sufficiently, leading to a decrease in the capacity of the lead-acid battery. Even if the positive electrode material does not enter the space inside the wrinkles, sulfate ions present inside the wrinkles interact with the wrinkle walls and become difficult to diffuse, so sulfate ions are not effectively utilized and the charge-discharge reaction may be inhibited. In particular, in deep life tests with a DOD of 50%, the sulfate ion concentration in the electrolyte becomes low, so the effect of wrinkles becomes more pronounced, and the discharge reaction is especially likely to be inhibited. As a result, the deep discharge life (50% DOD) may be more likely to decrease. 【0078】 In the lead-acid battery described in (15) above, since the maximum surface height Rz of the fibers is 1.90 μm or less, the unevenness caused by wrinkles on the surface of the fibers is sufficiently small and is not thought to form enough space for a large amount of positive electrode material and sulfate ions to enter. Furthermore, when the maximum surface height Rz of the fibers is 0.17 μm or more, it can be said that the surface of the fibers has enough unevenness to exhibit a high anchoring effect. Wrinkles on the surface of the fibers can enhance the effect of the fibers in suppressing the detachment of positive electrode material from the positive electrode plate. In other words, when the maximum height Rz is between 0.17 μm and 1.90 μm, the charge-discharge reaction is less likely to be inhibited by the fibers and a high anchoring effect is also exhibited, making it possible to ensure a good deep discharge life (50% DOD). 【0079】 The lifespan performance at a discharge depth of 50% (when repeated charging and discharging deeper than that described in "Lifespan Test Method A" below) can be evaluated using "Lifespan Test Method B" below. 【0080】By setting the maximum surface height Rz of the fiber to 1.90 μm or less, the degree of unevenness caused by wrinkles on the fiber surface is considered to be appropriate. As a result, a large amount of positive electrode material and sulfate ions can enter the spaces inside the wrinkles, which may inhibit the charge-discharge reaction. When the maximum surface height Rz of the fiber is 0.17 μm or more, the unevenness formed on the fiber surface is considered to be sufficiently large, and therefore the high anchoring effect is not inhibited. In that case, the charge-discharge reaction is not significantly inhibited by the fiber, and the effect of suppressing the softening and detachment of the positive electrode material by the fiber is also sufficiently ensured. 【0081】 As described above, when the maximum surface height Rz of the fiber is between 0.17 μm and 1.90 μm, the fiber surface can be said to have a degree of unevenness that does not have excessively large wrinkles, while at the same time enhancing the fiber's reinforcing effect. 【0082】 The maximum surface height Rz of the fiber may be 0.20 μm or more and 1.90 μm or less, 0.30 μm or more and 1.90 μm or less, 0.30 μm or more and 1.90 μm or less, 0.40 μm or more and 1.90 μm or less, 0.17 μm or more and 1.70 μm or less, 0.20 μm or more and 1.70 μm or less, 0.30 μm or more and 1.70 μm or less, 0.30 μm or more and 1.70 μm or less, 0.40 μm or more and 1.70 μm or less, 0.17 μm or more and 1.50 μm or less, 0.20 μm or more and 1.50 μm or less, 0.30 μm or more and 1.50 μm or less, or 0.40 μm or more and 1.50 μm or less. 【0083】 (Method for measuring the maximum surface height Rz of the fiber) The maximum surface height Rz of the fiber is determined for fibers taken from the positive electrode material of a fully charged lead-acid battery using the same procedure as for the average surface roughness Ra of the fiber. 【0084】Specifically, for the fiber samples obtained for analysis using the method described above, the maximum surface height Rz of the fibers is determined using a laser microscope in accordance with ISO 4287:1997. More precisely, an image for analysis is acquired under the condition of a 20x objective lens. The acquired image for analysis is subjected to automatic correction processing for noise reduction and tilt correction using an analysis application. An image for analysis is acquired from five or more fibers, and the analysis is performed using the line roughness measurement of the analysis application to measure the maximum surface height Rz of each fiber. The maximum surface height Rz of the fibers is determined by averaging the measured values ​​of the five or more maximum surface heights Rz. 【0085】 The average surface roughness Ra and maximum height Rz of the fibers may be adjusted in advance by surface treatment of the fibers. The average surface roughness Ra and maximum height Rz of fibers that have not been adjusted may be adjusted by a predetermined method. The average surface roughness Ra and maximum height Rz of the fibers may be adjusted during the manufacturing process of the lead-acid battery. 【0086】 One method for adjusting the average surface roughness Ra and maximum height Rz of fibers is chemical treatment, which modifies the fiber surface using chemicals such as acids and alkalis. Other methods for adjusting the average surface roughness Ra and maximum height Rz of fibers include plasma treatment, which modifies the fiber surface using plasma; corona treatment, which modifies the fiber surface using high-voltage discharge; and UV irradiation treatment, which modifies the fiber surface using ultraviolet light. Yet another method is sandblasting, which involves impacting the fibers with fine powder harder than the fibers themselves. 【0087】 For example, when performing plasma treatment, corona treatment, or UV irradiation as a method for treating the surface of fibers, the average surface roughness Ra and maximum height Rz of the fibers may be adjusted by changing the output value of the processing apparatus, the processing time, or both. In sandblasting, the speed of the fine powder impacting the fibers and the processing time can also be changed. The average surface roughness Ra and maximum height Rz may also be controlled by the heat treatment conditions of the fibers, the polishing conditions of the fiber surface, etc. 【0088】The surface area of ​​the fibers per gram of positive electrode material is 1.67 cm², which is the point at which the anchoring effect by the fibers is most pronounced. ２ It is more preferable that the above is true, and 1.70 cm ２ or more, or 2.00 cm ２ The above is also acceptable. The surface area of ​​the fibers per gram of positive electrode material is 5.00 cm². ２ The following is preferable, and by controlling it within this range, sufficient conductive paths can be secured within the positive electrode material, thereby improving the capacity retention rate. 【0089】 (16) In the lead-acid battery described in any one of (1) to (5) and (8) to (15) above, it is preferable that the maximum surface height Rz of the fibers is 1.40 μm or less. When the maximum surface height Rz of the fibers is within the above range, inhibition of the charge-discharge reaction by the fibers is significantly suppressed, while the anchoring effect of the fibers is fully expressed. As a result, a better deep discharge life (50% DOD) can be ensured. In addition, when charge-discharge cycles are repeated at a shallower discharge depth, the charge-discharge reaction is less likely to be inhibited by the fibers, making it easier to improve the capacity retention rate. 【0090】 The maximum surface height Rz of the fiber may be 0.17 μm or more and 1.40 μm or less, 0.20 μm or more and 1.40 μm or less, 0.30 μm or more and 1.40 μm or less, 0.40 μm or more and 1.40 μm or less, 0.60 μm or more and 1.40 μm or less, 0.17 μm or more and 1.20 μm or less, 0.20 μm or more and 1.20 μm or less, 0.30 μm or more and 1.20 μm or less, 0.40 μm or more and 1.20 μm or less, 0.17 μm or more and 1.00 μm or less, 0.20 μm or more and 1.00 μm or less, 0.30 μm or more and 1.00 μm or less, or 0.40 μm or more and 1.00 μm or less. From the viewpoint of obtaining a better deep discharge lifetime (50% DOD) and capacity retention rate, the maximum surface height Rz of the fiber may be set to 0.60 μm or more and 1.20 μm or less. 【0091】(17) In the lead-acid battery described in (15) or (16) above, the average fiber diameter of the fibers is preferably 1 μm or more and 9 μm or less. More preferably, the average fiber diameter of the fibers may be 1 μm or more and 8 μm or less, 1 μm or more and 6 μm or less, 1 μm or more and 5 μm or less, 2 μm or more and 9 μm or less, 2 μm or more and 8 μm or less, 2 μm or more and 6 μm or less, 2 μm or more and 5 μm or less, 4 μm or more and 9 μm or less, or 4 μm or more and 8 μm or less. Such fibers maintain sufficiently high mechanical strength and can have a large specific surface area. Also, even with the same fiber content, the number of fibers increases, so that the structure in which the fibers are interwoven within the positive electrode material tends to be formed. Therefore, the contact area between the fibers and the positive electrode material becomes sufficiently large, and it becomes possible to ensure a good deep discharge life (50% DOD). 【0092】 (18) In the lead-acid battery described in any one of (15) to (17) above, the surface area of ​​the fibers per gram of the positive electrode material is 3.00 cm². ２ The above is preferable. In terms of further enhancing the anchoring effect by the fibers, the surface area of ​​the fibers per gram of positive electrode material should be 3.00 cm². ２ It is more preferable that the length be greater than or equal to 3.40 cm. ２ or more, or 3.70 cm ２ Above, 4.00cm ２ The above is also acceptable. Furthermore, it is thought that the entanglement of the fibers and lead compounds over a larger contact area will enhance the anchoring effect of the fibers, increase the bonding strength between the lead compounds, and significantly improve the deep discharge life (50% DOD) of the lead-acid battery. 【0093】 (19) In the lead-acid battery described in any one of (1) to (18) above, the area of ​​the opening of the grid portion in the positive electrode current collector is 50 mm ２ It is acceptable to satisfy more than one of these conditions. 【0094】The positive electrode current collector comprises a grid section, a first transverse rib section continuous with the grid section, and an ear section continuous with the first transverse rib section. The first transverse rib section is provided at the upper end of the grid section. The ear section protrudes upward from the first transverse rib section. The shape of the positive electrode current collector, excluding the ear section, is generally rectangular. The positive electrode current collector may be an expanded grid, a punched grid, or a cast grid. 【0095】 The area of ​​the openings in the grid is calculated starting from the largest opening. For example, in the case of an expanded grid, the area of ​​the openings in the grid increases progressively downwards from the first horizontal beam. In this case, the area of ​​the openings is calculated as the average value of the lowest, perfectly diamond-shaped openings. 【0096】 In this specification, the vertical direction of a lead-acid battery or its components (plates, case, separator, etc.) refers to the vertical direction of the lead-acid battery in its operating state. 【0097】 If the amount of positive electrode material remains the same, increasing the area of ​​the lattice openings allows for a reduction in the thickness of the positive electrode plate. This makes it possible to increase the amount of electrolyte, and since the diffusivity of the electrolyte also improves, the capacity is increased. 【0098】 In the lead-acid battery described in (19) above, the bonding force between the positive electrode materials is significantly increased by the fibers, so the area of ​​the opening in the grid is 50 mm ２ Even when the number of electrodes is increased to more than one, softening and detachment of the positive electrode material are suppressed when deep charge-discharge cycles are repeated, ensuring good lifespan performance. The area of ​​the lattice opening is 65 mm². ２ There may be more than one, and 75 mm ２ There may be more than one, and 85 mm ２ It may be more than one unit, and 100 mm ２ It may be more than one per unit. Furthermore, because the bonding force between the positive electrode materials is significantly increased, even if the mesh of the grid becomes coarser, the current collection performance of the positive electrode plate does not easily decrease, and the reaction proceeds more uniformly. The area of ​​the opening in the grid of the positive electrode current collector is 135 mm². ２ Preferably, the number is 125 mm or less. ２ It may be less than or equal to 115 mm２ The number may be less than or equal to one per unit. By controlling it within this range, softening and detachment of the positive electrode material can be sufficiently suppressed, ensuring good lifespan performance. 【0099】 (20) The lead-acid battery described in any one of (1) to (19) above may be a lead-acid battery used to supply power to an in-vehicle device that transmits and receives data via wireless communication. 【0100】 With the advent of OTA technology and the widespread use of dashcams, the current values ​​of lead-acid batteries used in vehicles for auxiliary applications such as air conditioners and electrical components tend to increase while the vehicle is stopped. For such auxiliary lead-acid batteries, there is a stronger need to improve durability when repeatedly performing high-capacity and deep-depth charge-discharge cycles, rather than prioritizing starting performance (high-current discharge) or high-temperature durability, which have been important until now. 【0101】 In other words, the lead-acid battery described in (20) above is suitable as a lead-acid battery used to supply power to in-vehicle equipment that transmits and receives data via wireless communication. 【0102】 (21) The lead-acid battery described in any one of (1) to (20) above may be a lead-acid battery used as an auxiliary battery for a hybrid vehicle or an electric vehicle. Such a lead-acid battery is not for starting the engine, but rather for supplying electricity necessary for the operation of electronic equipment and control systems installed in the vehicle, for example. 【0103】 (22) In the lead-acid battery described in any one of (1) to (21) above, at least one of the pair of lower corners of the positive electrode plate may be chamfered. 【0104】In the lead-acid battery described in (22) above, a space is formed at the bottom of the battery case in the area where the lower corner of the positive electrode plate has been chamfered. Therefore, even if deep charge and discharge cycles are repeated over a long period and the positive electrode material falls off, the fallen positive electrode material will accumulate in the space formed at the bottom of the battery case. In this space, the charge and discharge reaction hardly occurs and the amount of gas generated is small, so the floating of the accumulated positive electrode material is reduced. This suppresses the occurrence of short circuits caused by the fallen positive electrode material. The larger the area of ​​the opening in the grid portion of the positive electrode current collector, the more likely the positive electrode material is to soften and fall off, so the effect of this chamfering becomes more pronounced. 【0105】 Furthermore, if the corners of the positive electrode plate deform during the manufacturing process, a short circuit may occur in the early stages of a lead-acid battery by piercing the separator. In the lead-acid battery described in (22) above, the occurrence of such early short circuits due to corner deformation is reduced. This effect is particularly noticeable when the positive electrode current collector is an expanded grid. This is because expanded grids do not have vertical frame supports, making them prone to deformation of the corners of the positive electrode plate. 【0106】 The chamfering of the lower corners can be achieved, for example, in the case of an expanded grid, by removing a portion of the corner of a rectangularly manufactured electrode plate. However, the method of chamfering is not limited to this. In the case of a punched or cast grid, the frame may be formed such that the corners have a chamfered or curved outer edge. 【0107】 The surface area of ​​the fibers per gram of positive electrode material is 1.35 cm². ２ As described above, softening and detachment of the positive electrode material can be suppressed, and the risk of much of the detached positive electrode material floating around without being contained in the space formed at the bottom of the battery case by the chamfering is reduced, which is preferable. Therefore, the effect of suppressing short circuits by chamfering is easily achieved. 【0108】The reduction in electrode surface area due to chamfering (hereinafter referred to as "chamfered area") may be 1% or more of the surface area of ​​the positive electrode plate before chamfering. The ratio M1 of the chamfered area to the surface area of ​​the positive electrode plate before chamfering is sufficient if it is 1% or more, and is preferably 6% or less from the viewpoint of ensuring high capacitance. The ratio M1 may be 2% or more and 4% or less. 【0109】 (23) In the lead-acid battery described in any one of (1) to (22) above, the negative electrode plate may contain a negative electrode material containing a carbon material, and the carbon material content may be 0.35% by mass or more and 0.80% by mass or less. 【0110】 In the lead-acid battery described in (23) above, the negative electrode material contains a carbon material within the above range, thereby suppressing sulfation near the negative electrode and improving the IS life. Examples of carbon materials include carbon black, non-graphitizable carbon, easily graphitizable carbon, and graphite. Among these, carbon black is preferred from the viewpoint of having a high surface area and high conductivity. By adding carbon black, conductive paths are formed within the negative electrode material by the carbon black. As a result, the following charging reaction proceeds smoothly even inside the negative electrode material, and a significant effect in eliminating sulfation is obtained. PbSO ４ +2H ＋ +2e － →Pb+H ２ SO ４ 【0111】 Preferred carbon blacks include acetylene black and furnace black. Examples of acetylene black include Denka Black (registered trademark). Examples of furnace black include Ketjen Black (registered trademark). 【0112】 (24) In the lead-acid battery described in any one of (1) to (22) above, the density of the positive electrode material is 4.0 g / cm³ ３ The following is also acceptable. 【0113】In the lead-acid battery described in (24) above, the utilization rate of the electrode material (active material) can be improved by lowering the density of the positive electrode material, thereby reducing the amount of lead used or increasing the initial capacity. On the other hand, lowering the density has the drawback that the positive electrode material is more prone to softening and shedding. However, by using the fibers of the present invention, it is possible to make softening and shedding less likely to occur even when using a low-density positive electrode material, thereby ensuring good lifespan performance. The lower limit of the density of the positive electrode material is not particularly limited. For example, the density of the positive electrode material can be 3.4 g / cm³. ３ This is preferable because it sufficiently suppresses the softening and shedding of the positive electrode material by the fibers of the present invention. 【0114】 (25) In the lead-acid battery described in any one of (1) to (24) above, the electrolyte may contain Mg ions, or the electrolyte may contain 2.0 to 10 g / L of Mg ions. 【0115】 In the lead-acid battery described in (25) above, the presence of Mg ions in the electrolyte allows the ions to remain present in the electrolyte even if the lead-acid battery enters an over-discharge state and the sulfuric acid concentration in the electrolyte becomes dilute. This suppresses the dissolution of lead into the electrolyte when an over-discharge state occurs, thereby suppressing the growth of lead dendrites and, as a result, preventing penetration short circuits. Furthermore, Mg ions have the effect of increasing the conductivity of the electrolyte when the lead-acid battery enters an over-discharge state, thus improving the charge acceptance performance in the over-discharge state. These effects can be more pronounced when the Mg ions in the electrolyte are within the above range. Na ions or Li ions may be used instead of Mg ions. However, Na ions have the drawback of reducing regenerative charge acceptance, and Li ions are expensive, so Mg ions are preferred. 【0116】 (26) In the lead-acid battery described in any one of (1) to (25) above, the positive electrode plate further comprises a positive electrode current collector, and the positive electrode current collector may have an Sb content of 1.5% by mass or more and 4.0% by mass or less. The deep discharge life performance is improved by the positive electrode current collector containing antimony within the above range. 【0117】In this specification, the fully charged state of a liquid lead-acid battery is defined according to the definition in JIS D5301:2019. More specifically, the 20-hour rate current I is used until the terminal voltage (in volts) during charging, measured every 15 minutes in a water bath at 25°C ± 2°C, or the electrolyte density converted to a temperature of 20°C, shows a constant value with three significant figures for three consecutive times. ２０ Twice the current 2I ２０ (Unit: A) The fully charged state is defined as the state in which the lead-acid battery has been charged. Note that the 20-hour rate current I ２０ This refers to a current (A) that is 1 / 20 of the Ah value listed in the rated capacity. The value listed as the rated capacity is a value with the unit Ah (ampere-hour). The unit of the current set based on the value listed as the rated capacity is A (ampere). Note that a current (A) that is 1 / n of the Ah value listed in the rated capacity is called 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. 【0118】 Furthermore, in the case of a valve-regulated lead-acid battery, a fully charged state is defined as a 20-hour rate current of I in an air chamber at 25°C ± 2°C. ２０ Five times the current 5I ２０ The battery was then charged at a constant current and voltage of 2.67V / cell (16.00V for a lead-acid battery with a nominal voltage of 12V), and the charging process was terminated when the total charging time reached 24 hours. 【0119】 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 some time has passed since chemical formation (for example, 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. 【0120】 In this specification, a battery in its initial use refers to a battery that has not been used for very long and has not deteriorated much (for example, a battery that has been in use for less than 720 hours, including the time elapsed since chemical preparation). 【0121】The lead-acid battery according to an embodiment of the present invention will be described in more detail below with reference to the drawings. However, the present invention is not limited to the following embodiments. 【0122】 The following describes examples of components of a lead-acid battery. 【0123】 (Positive electrode 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. Note that 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. 【0124】 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. The processing method may be, for example, expansion or punching. In other words, the positive electrode current collector may be an expanded grid, a punched grid, or a cast grid. 【0125】 Figure 1A is a schematic diagram of an example of a positive electrode current collector 100 which is an expanded grid, and Figure 1B is an enlarged view of a part of the grid portion of the positive electrode current collector in Figure 1A. 【0126】 The positive electrode current collector 100 comprises a grid portion 101, a first transverse bone portion 102, and an ear portion 103. The first transverse bone portion 102 is provided at the upper end of the grid portion 101. The ear portion 103 is provided so as to protrude upward from the first transverse bone portion 102. 【0127】 The shape of the positive electrode current collector 100, excluding the ear portion 103, is generally rectangular in width W and height H. The corner portion of the grid portion 101 opposite to the first horizontal bone portion 102 is chamfered. 【0128】In the case of Figure 1B, the area of ​​the opening can be calculated as A × B. In expanded grids, the area of ​​the opening can be freely changed by adjusting the cutting width and unfolding dimensions applied to the lead alloy sheet, which is the raw material, when manufacturing the positive electrode current collector. In cast grids, it can be freely changed by adjusting the mold, and in punched grids, it can be freely changed by adjusting the punching die. 【0129】 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 with different compositions, and the metal layers may be one layer or multiple layers. 【0130】 The positive electrode material includes a positive electrode active material that exhibits capacity through a redox reaction. The positive electrode active material includes lead dioxide, lead sulfate, etc. The positive electrode material also includes fibers as a reinforcing material and may include antimony compounds, etc., as needed. 【0131】 The surface area of ​​the fibers per gram of positive electrode material is 1.35 cm². ２ That's all, 1.70 cm ２ Preferably, it should be 2.00 cm or more. ２ It is even more preferable that the above is 3.00 cm. ２ The above is also acceptable. The upper limit of the surface area of ​​the fibers per gram of positive electrode material is, for example, 4.00 cm². ２ It is possible, but not particularly limited. 【0132】 The average fiber diameter D of the fibers is, for example, 20 μm or less or 18 μm or less, and may be 13 μm, and more preferably 1 μm or more and 8 μm or less. Such fibers have sufficiently high mechanical strength and a sufficiently large specific surface area. Therefore, the effect of the fibers on improving the deep discharge life of lead-acid batteries is very large. 【0133】The resin constituting the fiber may be polyester, polyolefin, polystyrene, polyvinyl chloride, etc. Among these, at least one selected from the group consisting of polyester and polyolefin is preferred. Examples of polyester include polyethylene terephthalate (PET) and polyalkylene arylates such as polybutylene terephthalate (PBT). Examples of polyolefins include polyethylene, polypropylene, and ethylene-propylene copolymer. The fiber may contain one of these resins or two or more. Furthermore, the positive electrode material may contain multiple fibers formed of different resins. In particular, using PET makes it easier to improve the deep discharge life of the lead-acid battery. 【0134】 For example, 85% or more of the fiber may be at least one selected from the group consisting of polyester and polyolefin. Fibers containing polyester with such a high mass content are usually called polyester fibers. Similarly, fibers containing polyolefin with such a high mass content are usually called polyolefin fibers. 【0135】 The surface of the fiber may have various irregularities. It is preferable that the irregularities on the fiber surface are formed along the circumferential direction of the fiber. Irregularities along the circumferential direction of the fiber cause greater friction with the particles of the positive electrode active material (lead compound) that tend to move in the longitudinal direction of the fiber, and thus have a significant effect in suppressing the expansion of the positive electrode material. The irregularities on the fiber surface may also be observed using a scanning electron microscope (SEM) image of the fiber. 【0136】The irregularities may be formed on the fibers beforehand, or they may be formed on smooth fibers by a predetermined method, or they may be formed during the manufacturing process of the lead-acid battery. One method for forming irregularities on the surface of fibers is chemical treatment, which modifies the fiber surface using chemicals such as acids and alkalis. Other methods for forming irregularities on the surface of fibers include plasma treatment, which modifies the fiber surface using plasma, corona treatment, which modifies the fiber surface using high-voltage discharge, and UV irradiation treatment, which modifies the fiber surface using ultraviolet light. Yet another method is sandblasting, for example. Sandblasting is a process in which fine powder harder than the fiber is impacted onto the fiber. 【0137】 When using methods such as plasma treatment, corona treatment, or UV irradiation to create irregularities on fibers, the state of the irregularities may be altered by changing the output value of the processing device, the processing time, or both. In sandblasting, the speed of the fine powder impacting the fibers and the processing time can also be changed. 【0138】 It is more preferable that the surface irregularities of the fiber are formed in a wave-like pattern along the circumferential direction of the fiber. The wave-like irregularities have a very high friction with the particles of the positive electrode active material that try to move in the longitudinal direction of the fiber, thus further enhancing the effect of suppressing the expansion of the positive electrode material. For example, the surface of a fiber made of PET is also preferable because it can have irregularities formed in a wave-like pattern along the circumferential direction. 【0139】 The average surface roughness Ra of the fibers is preferably between 0.1 μm and 1.3 μm. In this case, it is easier to form irregularities on the fiber surface that enhance the anchoring effect, and oxidative degradation of the fibers by the positive electrode material is suppressed. 【0140】 The maximum surface height Rz of the fibers is preferably 0.17 μm or more and 1.90 μm or less. In this case, the charge-discharge reaction is less likely to be inhibited by the fibers, and a high anchoring effect is also exhibited, making it possible to ensure a better deep discharge life (50% DOD). 【0141】 The fiber has a BET specific surface area measured using krypton gas as the adsorbent gas, for example, 0.3 m².２ / g or more 1.0m ２ It may be less than / g. The BET specific surface area of ​​the fiber measured using krypton gas as the adsorbent gas is 0.3 m². ２ When the value is 1 / g or higher, it is easier to ensure even better lifespan performance. In addition, the BET specific surface area of ​​the fiber measured using krypton gas as the adsorption gas is 1.0 m². ２ When the value is less than / g, the oxidation resistance of the fibers improves, and the positive electrode plate can more easily ensure sufficient conductivity. 【0142】 The BET specific surface area of ​​a fiber may be adjusted, for example, by surface treatment of the fiber, similar to the adjustment of the average surface roughness Ra and maximum height Rz of the fiber surface. Alternatively, the average surface roughness Ra and maximum height Rz, as well as the BET specific surface area of ​​the fiber, may be adjusted simultaneously by surface treatment of the fiber. The methods described above can be used as methods for treating the fiber surface. 【0143】 The cumulative pore volume of the positive electrode material with pore diameters ranging from 0.006 μm to 15 μm is, for example, 0.167 cm³. ３ It is less than / g and 0.080 cm ３ / g or more, 0.130cm ３ The density may be less than or equal to / g. In this case, the density of the positive electrode material is sufficiently high, and the positive electrode material is less likely to collapse, so the effect of improving the deep discharge life by the fibers is significantly enhanced. Also, when the cumulative pore volume in the range of pore diameter 0.006 μm to 15 μm is within the above range, the diffusivity of sulfate ions is increased, making it easier to secure higher output. Furthermore, even after repeated charging and discharging, contact between lead and lead sulfate particles is easily maintained, so the decrease in the binding force of the positive electrode material is suppressed. As a result, the effect of suppressing the shedding of the positive electrode material is further enhanced, so good life performance can be ensured when repeated deep charging and discharging is performed. 【0144】 The cumulative pore volume of the positive electrode material with pore sizes ranging from 0.006 μm to 15 μm is 0.080 cm³. ３ / g or more (or 0.090 cm) ３ / g or more) 0.167cm ３ It can be less than / g, or 0.080 cm ３ / g or more (or 0.090 cm) ３ / g or more) 0.130cm ３ It can be less than / g, or 0.080 cm ３ / g or more (or 0.090 cm) ３ / g or more) 0.110cm ３ It is also acceptable to use less than / g. 【0145】 The cumulative pore volume (V(all)) of the positive electrode material with pore diameters ranging from 0.006 μm to 15 μm is determined by the mercury intrusion method. For example, V(all) is measured using a mercury porosimeter (Shimadzu Corporation, Autopore IV9510) with an unground sample of the positive electrode material. The measurement pressure range is from 1 psia (≈6.9 kPa) to 60,000 psia (≈414 MPa). 【0146】 Samples of uncrushed positive electrode material are taken from positive electrode plates removed from fully charged lead-acid batteries. 【0147】 The positive electrode material is recovered from the positive electrode plate by the following procedure. First, a fully charged lead-acid battery is disassembled, and the obtained positive electrode plate is washed with water for 3 to 4 hours to remove the electrolyte from the positive electrode plate. The washed positive electrode plate is dried in a constant temperature bath at 60°C ± 5°C for 5 hours or more. After drying, if the positive electrode plate contains adhesive material, the adhesive material is removed from the positive electrode plate by peeling. A sample of the positive electrode material for analysis can be obtained by taking a sample of the positive electrode material without crushing it from near the center of the top, bottom, left, and right sides when viewed from the front of the positive electrode plate. For V(all) measurement, a sample of about 1.2 g is sufficient. 【0148】 The fibers are recovered from a sample of positive electrode material weighing approximately 70g (Wg) using the following procedure. First, the Wg sample of positive electrode material is crushed and accurately weighed. At this time, the sample may consist of positive electrode material from one or more positive electrode plates. 【0149】Next, the pulverized sample is added to a mixed solution of acetic acid-sodium acetate solution and sodium thiosulfate solution (acetic acid concentration 1.7 mol / L, sodium acetate concentration 6.1 mol / L, sodium thiosulfate concentration 0.5 mol / L), and the soluble components are dissolved while stirring at room temperature. After that, it is washed with deionized water. Then, the resulting residue is filtered using a membrane filter (average pore size: 0.45 μm or less). This allows the fibers contained in the positive electrode material to be obtained as solid matter on the filter paper. If carbonaceous material is contained in the obtained solid matter, only the fibers contained in the sample are recovered as solid matter by centrifugation or sieving. 【0150】 A fiber sample for analysis is obtained by washing and drying the resulting solid. The mass w of the fiber sample is measured. The percentage of the mass w of the fiber sample relative to the mass W of the positive electrode material sample is the fiber content in the positive electrode material. 【0151】 The resin constituting the fibers can be identified by analyzing the infrared absorption spectrum of the fiber sample. Method B (film method) as specified in JIS L 1030-1:2024 may be used as the analytical method. 【0152】 Specifically, the fiber sample is dissolved in an appropriate dissolving reagent (see Table A), poured into an evaporating dish, and vacuum-dried or heated to a degree that does not decompose the sample. Next, the dried film is peeled off without tearing, cut to an appropriate size, and the infrared absorption spectrum is measured in accordance with JIS K 0117 2017. The film should be transparent. Also, the size of the film will vary depending on the infrared spectrophotometer used, so it should be at least 1 cm. ２ That concludes this section. 【0153】 Table A exemplifies the main absorption bands and characteristic wavenumbers of the infrared absorption spectra of major fibers, as well as the dissolving reagents. The absorption bands and characteristic wavenumbers of each fiber vary by ±20 cm depending on the infrared spectrophotometer used. －１ There are differences in degree. 【0154】 【0155】 The average fiber diameter D of a fiber can be determined by selecting any 20 fibers from a fiber sample, measuring the fiber diameter (the dimension perpendicular to the length of the fiber) at any point on each fiber, and taking the arithmetic mean of the measured values. The average fiber diameter D of a fiber may also be measured using a scanning electron microscope (SEM) image of the fiber. 【0156】 By identifying the resin that makes up the fibers, the fiber density d (g / cm³) can be determined. ３ The following is determined: fiber density d, mass w of fibers contained in the positive electrode material Wg, average fiber diameter D, and w / d = π(D / 2) ２ From the NL relationship, the surface area of ​​the fibers per gram of positive electrode material (NπDL / W) can be calculated. 【0157】 Unformed positive electrode plates are obtained by maturing and drying a positive electrode current collector and a positive electrode paste filled in the positive electrode current collector. The positive electrode paste is prepared by kneading a mixture containing lead powder, fibers, water, and sulfuric acid. The positive electrode paste may contain additives as needed. These additives may include antimony compounds, for example. Such positive electrode plates are also called paste-type positive electrode plates. 【0158】 A positive electrode plate can be obtained by chemically treating an untreated positive electrode plate. Chemical treatment may be carried out by immersing the electrode plate group, including the untreated positive electrode plate, in an electrolyte containing sulfuric acid in the battery case of a lead-acid battery, 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. 【0159】 (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. 【0160】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. 【0161】 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. 【0162】 The negative electrode material contains a negative electrode active material that exhibits capacity through an oxidation-reduction reaction. The negative electrode active material includes lead, lead sulfate, etc. The negative electrode material may also contain 100 ppm to 300 ppm of element Bi by mass. The negative electrode material may contain other additives as needed. The additives may include organic shrinkage inhibitors, carbonaceous materials, barium sulfate, etc. 【0163】 Examples of organic shrinkage inhibitors include lignin, lignin sulfonic acid, and synthetic organic shrinkage inhibitors. Synthetic organic shrinkage inhibitors may include, for example, formaldehyde condensates of phenolic compounds. Organic shrinkage inhibitors may be used individually or in combination of two or more. The content of organic shrinkage inhibitors in the negative electrode material is, for example, 0.01% by mass or more and 1% by mass or less. 【0164】 As carbonaceous materials, carbon black, artificial graphite, natural graphite, hard carbon, soft carbon, etc., can be used. One type of carbonaceous material may be used alone, or two or more types may be used in combination. The carbonaceous material content in the negative electrode material is, for example, 0.1% by mass or more and 3% by mass or less. 【0165】 The barium sulfate content in the negative electrode material is, for example, 0.1% by mass or more and 3% by mass or less. 【0166】Unformed negative electrode plates are obtained by aging and drying a negative electrode current collector and a negative electrode paste filled in the negative electrode current collector. Aging is preferably carried out in an atmosphere with a temperature higher than room temperature and high humidity. The negative electrode paste is prepared by kneading a mixture containing lead powder, water, and sulfuric acid. The negative electrode paste may contain additives as needed. Additives may include bismuth compounds (e.g., bismuth sulfate), organic shrinkage inhibitors, carbonaceous materials, barium sulfate, etc. 【0167】 A negative electrode plate can be obtained by chemically treating an untreated negative electrode plate. Chemical treatment may be carried out by immersing a group of electrode plates, including the untreated negative electrode plate, in an electrolyte containing sulfuric acid in the battery case of a lead-acid battery, 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. The charged negative electrode active material contains spongy lead. 【0168】 (Separator) Lead-acid batteries typically have a separator interposed between the negative and positive electrodes. The separator may be a microporous membrane or a glass fiber mat (AGM (Absorbed Glass Mat)). 【0169】 A microporous membrane is a porous sheet mainly composed of materials other than fiber components. Preferably, the amount of materials other than fiber components is, for example, 60% by mass or more. A microporous membrane can be obtained, for example, by extruding a resin composition containing a pore-forming agent into a sheet, and then removing the pore-forming agent to form pores. A microporous membrane is preferably composed of an acid-resistant polymer component. Polyolefin is preferred as the polymer component. On the other hand, a glass fiber mat preferably contains, for example, 60% by mass or more glass fibers. 【0170】 The thickness of the separator placed between the negative electrode plate and the positive electrode plate should be selected according to the distance between the two plates. 【0171】(Electrolyte Solution) The electrolyte solution is an aqueous solution containing sulfuric acid. The electrolyte solution may be gelled as needed. The electrolyte solution may contain cations (e.g., metal cations) and / or anions (e.g., phosphate ions) not derived from sulfuric acid as needed. Examples of metal cations include at least one selected from the group consisting of Na ions, Li ions, Mg ions, and Al ions. 【0172】 The density of the electrolyte solution at 20°C in a fully charged lead storage battery is, for example, 1.20 g / cm ３ or more, and may be 1.25 g / cm ３ or more. The specific gravity of the electrolyte solution at 20°C is 1.35 g / cm ３ or less, and preferably 1.32 g / cm ３ or less. 【0173】 (Example of Lead Storage Battery) FIG. 2 shows the appearance and part of the internal structure of a lead storage battery according to an embodiment. The lead storage battery 1 includes a battery case 12 that houses a group of electrode plates 11 and an electrolyte solution (not shown). Inside the battery case 12, it is partitioned into a plurality of cell chambers 14 by a partition wall 13. One group of electrode plates 11 is housed in each cell chamber 14. The opening of the battery case 12 is closed by a lid 15 having a negative electrode terminal 16 and a positive electrode terminal 17. The lid 15 is provided with a liquid port plug 18 for each cell chamber. When replenishing water, the liquid port plug 18 is removed and replenishing liquid is supplied. The liquid port plug 18 may have a function of discharging the gas generated inside the cell chamber 14 to the outside of the battery. 【0174】Each electrode plate group 11 is constructed by stacking multiple negative electrode plates 2 and positive electrode plates 3 via separators 4. Here, a bag-shaped separator 4 that houses the negative electrode plates 2 is shown, but the shape of the separator is not particularly limited. In the cell chamber 14 located at one end of the battery case 12, a negative electrode strap 6 that connects multiple negative electrode plates 2 in parallel is connected to a through connector 8, and a positive electrode strap 5 that connects multiple positive electrode plates 3 in parallel is connected to a positive electrode column 7. The positive electrode column 7 is connected to a positive electrode terminal 17 on the outside of the lid 15. In the cell chamber 14 located at the other end of the battery case 12, a negative electrode column 9 is connected to the negative electrode strap 6, and a through connector 8 is connected to the positive electrode strap 5. The negative electrode column 9 is connected to a negative electrode terminal 16 on the outside of the lid 15. Each through connector 8 passes through a through hole provided in the partition wall 13 and connects the electrode plate groups 11 of adjacent cell chambers 14 in series. 【0175】 Note that Figure 2 is merely one example of a liquid-type lead-acid battery, and the structure of the lead-acid battery according to this disclosure is not limited to the example shown. 【0176】 [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. 【0177】 The following describes the evaluation method for lead-acid batteries. 【0178】 (Life Test Method A) The deep discharge life of a lead-acid battery is evaluated by the number of charge-discharge cycles in a life test (12% DOD) that involves repeated deep charge-discharge cycles. 【0179】 A fully charged lead-acid battery with a nominal voltage of 12V will be subjected to repeated discharge and charging under the following conditions. Except for the water replenishment in (b) and (g), (a) to (h) will be carried out in a water tank environment at 25°C ± 2°C. 【0180】 (a) 20 hour rate current I ２０ Charging is performed at twice the normal current until the terminal voltage, measured every 15 minutes, shows a constant value for three consecutive times. 【0181】 (b) Refill with distilled water up to the upper level. 【0182】 (c) 20 hour rate current I ２０Discharge at a constant current for 12 minutes with a current 12 times that value. 【0183】 (d) The 20 - hour rate current I ２０ Charge at a constant current for 11.4 minutes with a current 12 times that value. 【0184】 (e) The 20 - hour rate current I ２０ Perform constant - current charging for 4.8 minutes with a current value 3 times that value. 【0185】 (f) Repeat steps (c) to (e) 350 times. 【0186】 (g) Refill with purified water up to the upper level. 【0187】 (h) Repeat steps (c) to (g) until the lead - acid battery reaches the end of its life. The end of life is defined as the point when the battery voltage drops below 7.2 V during the discharge in step (c). 【0188】 (Reserve Capacity Test Method) For a lead - acid battery with a nominal voltage of 12 V in a fully - charged state, in a water bath at 25 °C ± 2 °C, determine the discharge capacity of the lead - acid battery in the following manner. 【0189】 (a) Discharge at a constant current of 25 A until the voltage reaches 1.75 V / cell. 【0190】 (b) Then, charge with a 5 - hour rate current I ５ (i.e., a current (A) that is 1 / 5 of the Ah value described in the rated capacity) with an amount of electricity 135% of the discharged amount of electricity. 【0191】 (c) Repeat the cycle of the discharge in (a) and the charge in (b) a total of 3 times, and determine the discharge duration of the third cycle. Based on this discharge duration, evaluate the capacity of the lead - acid battery. 【0192】 (IS Life Test Method) The IS life of a lead - acid battery is evaluated by the number of charge - discharge cycles in the IS life test (SBA S 0101:2014). 【0193】 For a lead - acid battery with a nominal voltage of 12 V in a fully - charged state, proceed according to the following steps (a) and (b). 【0194】 (a) Throughout the entire test period, place the lead - acid battery in a gas phase at 25 ± 2 °C. The wind speed near the lead - acid battery should be 2.0 m / s or less. 【0195】 (b) Connect the lead-acid battery to the life test device and perform the following discharge (discharge 1 and discharge 2) and charge. This discharge and charge constitutes one cycle of discharge and charge. Then, repeat the discharge and charge cycle continuously. 【0196】 Discharge 1: Discharge current I Ｄ 59.0 ± 0.2 seconds at ±1A (where, I Ｄ This is calculated using the following conversion formula and rounded to the first decimal place. Ｄ = 18.3 × I ２０ ) 【0197】 Discharge 2: Discharge current 300 ± 1 A for 1.0 ± 0.2 seconds 【0198】 Charging: Charging voltage 14.00 ± 0.03V (limiting current 100.0 ± 0.5A) for 60.0 ± 0.3 seconds 【0199】 After every 3600 cycles, leave the system idle for 40-48 hours before starting the cycle again. Do not add water until the 30,000th cycle. 【0200】 The discharge termination voltage (terminal voltage) of discharge 2 is measured, and the number of cycles until it reaches 7.2V is determined and used as an indicator of IS life. 【0201】 (High-Temperature Overcharge Life Test Method) The high-temperature overcharge life of a lead-acid battery is evaluated by the number of charge-discharge cycles in the high-temperature overcharge life test using the following procedure. 【0202】 For a fully charged lead-acid battery with a nominal voltage of 12V, the procedure can be carried out according to the steps (a) to (d) below. 【0203】 (a) The lead-acid battery will be placed in the gas phase at 75 ± 3°C throughout the entire test period. 【0204】 (b) Connect the lead-acid battery to the life test device and continuously repeat the following discharge and charge cycles. Each of these discharge and charge cycles constitutes one life cycle. 【0205】 Discharge: 60 seconds ± 1 second at a discharge current of 25.0A ± 0.1A. Charging: 600 seconds ± 1 second at a charging voltage of 14.80V ± 0.03V (limiting current 25.0A ± 0.1A). 【0206】(c) During testing, leave the system idle for 56 hours every 480 cycles, and then apply the rated cold cranking current I ｃｃ Perform a continuous discharge for 30 seconds and record the voltage at the 30-second mark. Then, perform the charging procedure described in (b). Note that these discharge and charge cycles are also added to the lifespan (number of cycles). 【0207】 The test is terminated when the voltage measured at 30 seconds in tests (d) and (c) is 7.2V or less and does not rise again, and the total number of cycles at this point is used as an indicator of high-temperature overcharge life. 【0208】 Note that the rated cold cranking current I ｃｃ This refers to the current value corresponding to the performance rank specified in JIS D 5301:2019. 【0209】 (Life Test Method B) The deep discharge life (50% DOD) is evaluated in accordance with JIS D 5301:2019. Here, for a fully charged lead-acid battery, discharge and charge are repeated under the following conditions, and the number of cycles until the deep discharge life (50% DOD) is reached is evaluated. 【0210】 The life test will be conducted according to the following procedures (a) to (d). 【0211】 a) Charging: Fully charge the lead-acid battery using the method described above. 【0212】 b) Installation: Place the lead-acid battery in a water tank at 25±2°C. The water level should be 15mm to 25mm above the top of the lead-acid battery. Water may be added as needed using distilled water. 【0213】 c) Charging and discharging: Connect the lead-acid battery to the life test device and repeat the cycle described below. 【0214】 1) Discharge: 5×I ２０ Then discharge for 2 hours. 【0215】 2) Charging: 15.6V ± 0.03V (limiting current 5 × I) ２０ Charge for 5 hours. Stop charging when the ratio CR (2 × charge amount / 20-hour rate capacity) of the amount of charge to the 20-hour rate capacity reaches 1.1 or higher. 【0216】 3) When CR is 1.1 or less, constant current 2.5 × I２０ Charge until the CR ratio reaches 1.1. However, the charging time should be limited to a maximum of 1 hour. 【0217】 d) The test shall be terminated when the voltage in test c) becomes 10.5V or less. 【0218】 (Capacity Test Method) The capacity retention rate is evaluated by repeatedly discharging and charging the lead-acid battery under the following conditions. 【0219】 After repeating the charge-discharge cycle under condition (i) below for 20 cycles at 40°C, a capacity test under condition (ii) below is performed at 25°C. The ratio of the discharge capacity in the capacity test under condition (ii) after 40 charge-discharge cycles under condition (i) to the initial discharge capacity is calculated as the capacity retention rate as follows. 【0220】 Capacity retention rate (%) = (Discharge capacity after 40 cycles / Initial discharge capacity) × 100 【0221】 (Condition (i)) (40°C) Discharge: I ２０ Discharge and charge for 1.5 hours: I ２０ After charging for 1.2 hours, continue with 0.15 × I ２０ 5.5 hours to charge 【0222】 (Condition (ii)) (25℃) Discharge: I ２０ (Discharge termination voltage (F.V.) = 1.8V / cell) Charging: I ２０ This charges 135% of the discharged electricity. 【0223】 The resins that make up the fibers used are as follows: PET: polyethylene terephthalate, Vinylon: synthetic fiber obtained by acetalizing polyvinyl alcohol, Acrylic: acrylic resin, PE: polyethylene, PU: polyurethane, PP: polypropylene, PS: polystyrene 【0224】《A Series》 《Lead-acid batteries E1-E23 and R1-R12》 (1) Preparation of negative electrode plate A negative electrode paste is prepared by mixing lead oxide, carbon black, barium sulfate, lignin, water and sulfuric acid. The negative electrode paste is filled into the grid of an expanded grid made of antimony-free Pb-Ca-Sn alloy, and then aged and dried to obtain an unformed negative electrode plate of JIS B size. The amounts of carbon black, barium sulfate and lignin are adjusted so that when measured in a fully charged state after formation, they are 0.3 mass%, 2.1 mass%, and 0.1 mass%, respectively. 【0225】 (2) Preparation of the positive electrode plate A positive electrode paste is prepared by mixing lead oxide, fibers, water, and sulfuric acid. At this time, the amounts of water and sulfuric acid are adjusted so that the cumulative pore volume (V(all)) of the positive electrode material in the range of pore diameters from 0.006 μm to 15 μm, as measured by the procedure described above, is as shown in Table 1. In addition, fibers with an uneven surface are added to the positive electrode paste so that the surface area of ​​the fibers per gram of the positive electrode material (S( / 1g)), as determined by the method described above, is as shown in Table 1. The positive electrode paste is filled into the lattice of an expanded lattice made of antimony-free Pb-Ca-Sn alloy, and then aged and dried to obtain an unformed positive electrode plate of JIS B size. 【0226】 Batteries E1 to E16 and R1 to R12 use fibers with irregularities on the surface that extend along the circumferential direction of the fibers, while batteries E17 and E18 use fibers without irregularities. 【0227】 Figure 3 shows an SEM image of a PET fiber with surface irregularities extending along the circumferential direction of the fiber. Figure 4 shows an SEM image of an acrylic fiber with surface irregularities extending along the longitudinal direction of the fiber. To suppress charge-up during SEM imaging, a conductive material (gold or carbon) may be deposited on the fiber surface before imaging. 【0228】 The surface of PET fibers exhibits complex, wavy-shaped irregularities that extend along the circumferential direction of the fiber. On the other hand, the surface of acrylic fibers exhibits linear irregularities that extend along the length of the fiber, but no irregularities that extend along the circumferential direction of the fiber. 【0229】(3) Preparation of separators Prepare a bag-shaped separator by folding a polyethylene microporous membrane in half. 【0230】 (4) Fabrication of a lead-acid battery Here, a lead-acid battery (nominal voltage 12V) is used, which has six cells (connected in series) each consisting of four JIS B size positive electrodes and five JIS B size negative electrodes. This lead-acid battery is designed so that the positive electrodes are prone to degradation, and is configured to reach the end of its lifespan due to the degradation of the positive electrodes. 【0231】 Each unformed negative electrode plate is placed in a bag-shaped separator, and five unformed negative electrode plates and four unformed positive electrode plates are stacked alternately to form an electrode plate group. The tabs of the positive electrode plates and the tabs of the negative electrode plates are welded to the positive and negative electrode straps, respectively, using the cast-on-strap (COS) method. The electrode plate group is inserted into a polypropylene battery case, electrolyte is poured in, and the electrode formation process is carried out inside the case to assemble a liquid-type lead-acid battery with a nominal voltage of 12V and a rated capacity of 30Ah (20-hour rate capacity). Six electrode plate groups are connected in series inside the battery case. The 20-hour rate capacity is the capacity when discharged at a current (A) of 1 / 20 of the Ah value indicated in the rated capacity. 【0232】 The density of the electrolyte after chemical conversion is 1.28 ± 0.03 g / cm³. ３ Adjust within the range. 【0233】 (5) The evaluated lead-acid battery is fully charged using the procedure described above, and its lifespan performance (number of cycles until the terminal voltage of the lead-acid battery falls below 7.2V) is determined using the lifespan test method A described above. The results are shown in Table 1. Each evaluation is shown as a relative value (%) with the result of lead-acid battery R8 set to 100%. 【0234】 【0235】 Lead-acid batteries E24, E25, and E26 were manufactured and evaluated in the same manner as batteries E3, E7, and E10, except that smooth fibers with no surface irregularities were used. The results are shown in Table 2. 【0236】 【0237】Table 1 shows that the surface area of ​​the fibers per gram of positive electrode material (S ( / 1g)) is 1.35 cm². ２ It can be seen that the lifespan performance is significantly improved when the above conditions are met. Furthermore, it can be seen that the lifespan performance is more likely to improve significantly when the average fiber diameter D is thinner. From Table 2, it can be seen that the lifespan performance is significantly improved by using fibers with irregularities on the surface. 【0238】 In batteries R10 to R12, the cumulative pore volume (V(all)) is 0.167 cm³. ３ Because the density is relatively high at 1g, the lifespan performance is reduced. However, in batteries E17 to E23, the surface area of ​​the fibers per gram of positive electrode material is 1.35 cm². ２ The above conditions ensure that sufficient lifespan performance is maintained. 【0239】 Lead-acid batteries E27 to E31 are manufactured in the same manner as battery E3, except that the design capacity of the positive electrode plate is kept constant and the area of ​​each opening in the grid of the expanded grid is changed as shown in Table 3. 【0240】 Lead-acid batteries R13 to R17 are manufactured in the same manner as battery R4, except that the design capacity of the positive electrode plate is kept constant and the area of ​​each opening in the expanded grid is changed as shown in Table 3. 【0241】 Lead-acid batteries E32 to E35 are manufactured in the same manner as battery E10, except that the design capacity of the positive electrode plate is kept constant and the area of ​​each opening in the grid of the expanded grid is changed as shown in Table 3. 【0242】 Lead-acid batteries E36-E49, R18-R19: Except for keeping the design capacity of the positive electrode plate constant and changing each parameter as shown in Table 3, batteries E36-E49 and R18-R19 are manufactured in the same manner as battery E10. 【0243】 In batteries E37, E39, E41, R18, E43, E45, E47, R19, and E49, chamfers are formed on the corners at both ends of the lower part of the positive electrode plate. The ratio M1 of the chamfered area to the area of ​​the positive electrode plate before chamfering is 3% in all cases. 【0244】Batteries E40, E41, E46, and E47 use a cast grid for the positive electrode current collector. The amount of lead used in the positive electrode current collector of batteries E40 and E41 is the same as that of battery E36, and the amount of lead used in the positive electrode current collector of batteries E46 and E47 is the same as that of battery E42. 【0245】 Batteries E38, E39, E44, and E45 use a punched grid as the positive electrode current collector. The amount of lead used in the positive electrode current collector of these batteries is the same as that of battery E42. 【0246】 The fabricated lead-acid battery was fully charged using the procedure described above, and its lifespan performance was determined using the lifespan test method A described above. Its capacity (discharge duration) was also determined using the reserve capacity test method described above. The results are shown in Table 3. Each evaluation is expressed as a relative value (%) with the result of lead-acid battery R8 set to 100%. 【0247】 【0248】 Table 3 shows that the surface area of ​​the fibers per gram of positive electrode material (S ( / 1g)) is 1.35 cm². ２ The above conditions are met, and the opening area of ​​the lattice section is 50 mm². ２ In the above case, it can be seen that the lifespan performance is significantly improved and the capacity is also increased. The reason for the increase in capacity is thought to be the improved diffusivity of the electrolyte. Note that the opening area is 75 mm². ２ Even with such a large increase, the pores near the surface of the positive electrode material are blocked by lead sulfate, a discharge product, which inhibits the diffusion of sulfate ions into the positive electrode plate, thus preventing any further increase in capacity. 【0249】 Furthermore, the surface area of ​​the fibers per gram of positive electrode material is 1.35 cm². ２ The above batteries demonstrate the effect of the chamfering applied to the corners at both ends of the lower part of the positive electrode plate. However, the surface area of ​​the fibers per gram of positive electrode material is 1.35 cm². ２In batteries R14, R18, R16, and R19, chamfering does not improve lifespan performance. This is thought to be because the softening and detachment of the positive electrode material cannot be prevented. Furthermore, in batteries E48 and E49, the effect of chamfering on improving lifespan performance is small. This is because the opening area of ​​the grid portion of the positive electrode current collector is small, and softening and detachment of the positive electrode material are not a problem in the first place. In batteries E48 and E49, the capacity performance is also lower due to the decrease in the opening area of ​​the grid portion. 【0250】 《B Series》 《Lead-Acid Batteries E1 to E18》 (1) Preparation of Negative Electrode Plate A negative electrode paste is prepared by mixing lead oxide, carbon black, barium sulfate, lignin, water, and sulfuric acid. The negative electrode paste is filled into the grid of an expanded grid made of antimony-free Pb-Ca-Sn alloy, and then aged and dried to obtain an unformed negative electrode plate of JIS B size. The amounts of carbon black, barium sulfate, and lignin are adjusted so that when measured in a fully charged state after formation, they are 0.3 mass%, 2.1 mass%, and 0.1 mass%, respectively. 【0251】 (2) Preparation of the positive electrode plate A positive electrode paste is prepared by mixing lead oxide, fibers, water, and sulfuric acid. At this time, the surface irregularities of the fibers are adjusted by one of the methods described above so that the average surface roughness Ra of the fibers, which is determined by the method described above, and the BET specific surface area of ​​the fibers, which is determined using krypton gas as the adsorbent gas, are the values ​​shown in Table 4. In addition, the fibers are added to the positive electrode paste so that the fiber content in the positive electrode material, which is determined by the method described above, is the value shown in Table 4. The positive electrode paste is filled into the lattice of an expanded lattice made of antimony-free Pb-Ca-Sn alloy, and then aged and dried to obtain an unformed positive electrode plate of JIS B size. 【0252】 (3) Preparation of separators Prepare a bag-shaped separator by folding a polyethylene microporous membrane in half. 【0253】(4) Manufacturing of the lead-acid battery Each untreated negative electrode plate is placed in a bag-shaped separator, and five untreated negative electrode plates and four untreated positive electrode plates are stacked alternately to form an electrode plate group. The tabs of the positive electrode plates and the tabs of the negative electrode plates are welded to the positive and negative electrode straps, respectively, using the cast-on-strap (COS) method. The electrode plate group is inserted into a polypropylene battery case, electrolyte is poured in, and the electrode plate group is treated inside the battery case to assemble a liquid-type lead-acid battery with a nominal voltage of 12V and a rated capacity of 30Ah (20-hour rate capacity). Six electrode plate groups are connected in series inside the battery case. 【0254】 The density of the electrolyte after chemical conversion is 1.28 ± 0.03 g / cm³. ３ Adjust within the range. 【0255】 (5) The prepared lead-acid battery is fully charged using the procedure described above, and the IS life (number of cycles until the terminal voltage of the lead-acid battery falls below 7.2V) and high-temperature overcharge life (number of cycles until the voltage of the lead-acid battery at 30 seconds falls below 7.2V) are determined using the method described above. The results are shown in Table 4. Each evaluation is shown as a relative value (%) with the result of lead-acid battery R2 set to 100%. 【0256】 【0257】 Lead-acid batteries E19-E21 and R1-R2: Except for adjusting the surface irregularities of the fibers by surface treatment so that the average surface roughness Ra of the fibers, obtained by the method described above, and the BET specific surface area of ​​the fibers, obtained using krypton gas as the adsorbent gas, are the values ​​shown in Table 5, batteries E19-E21 and R1-R2 were manufactured and evaluated in the same manner as battery E3. The results are shown in Table 5. 【0258】 【0259】 Lead-acid batteries E22-E23 and R3-R4: Batteries E22-E23 and R3-R4 were prepared in the same manner as battery E1, except that the fibers were incorporated into the positive electrode paste so that the fiber content in the positive electrode material and the surface area of ​​fibers per gram of positive electrode material (S ( / 1g)), determined by the method described above, were as shown in Table 6, and were evaluated in the same manner. The results are shown in Table 6. 【0260】 【0261】 From the results for batteries E1 to E18 in Table 4, it can be seen that when the average surface roughness Ra of the fibers is between 0.1 μm and 1.3 μm, a good IS life and a good high-temperature overcharge life can be ensured. It is thought that fibers with a larger average surface roughness Ra can exhibit a higher anchoring effect, making it less likely for the positive electrode material to detach from the positive electrode plate, thus ensuring a good IS life. Furthermore, when the average surface roughness Ra of the fibers is 1.3 μm or less, oxidative degradation of the fibers is less likely to progress even when high-temperature overcharging is repeated, and the fibers can remain in the positive electrode material for a longer period. As a result, it is thought that a state of high adhesion between the fibers and the positive electrode material is maintained for a long period, and a good high-temperature overcharge life can be ensured. 【0262】 From the results for batteries E4 and E20 in Table 5, the BET specific surface area of ​​the fiber measured using krypton gas as the adsorption gas is 0.3 m². ２ / g or more 1.0m ２ When the value is less than / g, it can be seen that an even better IS lifespan and an even better high-temperature overcharge lifespan can be ensured. 【0263】 From the results for batteries E4 and E13 in Table 6, it can be seen that when the fiber content in the positive electrode material is 0.05% by mass or more and 0.23% by mass or less, an even better IS life and an even better high-temperature overcharge life can be ensured. 【0264】 《C Series》 《Batteries E1 to E29 and Batteries R1 to R10》 (1) Preparation of positive electrode plate A positive electrode paste is prepared by mixing lead oxide, fibers, water and sulfuric acid. At this time, the predetermined amount of fibers is added to the positive electrode paste so that the maximum surface height Rz of the fibers taken from a fully charged battery, and the surface area of ​​the fibers per gram of positive electrode material taken from a fully charged battery (S ( / 1g)), which are measured by the procedure described above, are the values ​​shown in Table 7. The average fiber diameter of the fibers measured by the procedure described above is as shown in Table 7. The positive electrode paste is filled into the mesh of an expanded grid, which is a positive electrode current collector made of lead alloy, and cured and dried to obtain an unformed positive electrode plate with a width of 100 mm, a height of 110 mm and a thickness of 1.6 mm. 【0265】 (2) Preparation of the negative electrode plate A negative electrode paste is prepared by mixing lead oxide, carbon black, barium sulfate, lignin, 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 cured and dried to obtain an unformed negative electrode plate with a width of 100 mm, a height of 110 mm, and a thickness of 1.3 mm. 【0266】 The amounts of carbon black, barium sulfate, and lignin used are adjusted so that the content of each component in the negative electrode plate removed from a fully charged lead-acid battery is 0.3% by mass, 2.1% by mass, and 0.1% by mass, respectively. 【0267】 (3) Manufacturing of lead-acid batteries The untreated negative electrode plates are placed in a bag-shaped separator made of a microporous polyethylene membrane and stacked with the positive electrode plates to form an electrode plate group consisting of seven untreated negative electrode plates and six untreated positive electrode plates. 【0268】 Positive and negative electrode straps are provided using a cast-on strap (COS) method, connecting the tabs of the positive electrode plate and the tabs of the negative electrode plate, respectively. The six electrode plate groups are inserted into a polypropylene battery case, connected in series, electrolyte is poured in, and chemical conversion is performed within the battery case to assemble a liquid lead-acid battery with a nominal voltage of 12V and a 20-hour rate capacity of 30Ah. 【0269】 A sulfuric acid aqueous solution is used as the electrolyte. The density of the electrolyte after chemical conversion at 20°C is 1.28 ± 0.03 g / cm³. ３ Adjust within the range. 【0270】 (4) The life test method B and capacity test of the evaluated lead-acid battery are performed according to the procedure described above and evaluated. Table 1 shows the relative value (%) of the deep discharge life (50% DOD) and the capacity retention rate (%) for each example. The relative value is the relative value (%) when the deep discharge life (50% DOD) and capacity retention rate of battery R2 are set to 100%. 【0271】 【0272】Table 7 shows that, compared to batteries E27-E29 and R9-R10, where the maximum fiber surface height Rz is in the range of 0.17 μm to 1.90 μm, batteries E1-E26 and R1-R8, where the maximum fiber surface height Rz is in the range of 0.17 μm to 1.90 μm, can ensure a good deep discharge life (50% DOD). This is thought to be because the charge-discharge reaction is less inhibited by the fibers, and a high anchoring effect is also exhibited. In particular, the results for batteries E1-E5 show that when the maximum fiber surface height Rz is in the range of 0.60 μm to 1.40 μm, an even better deep discharge life (50% DOD) can be ensured. 【0273】 Based on the results for batteries E3, E6-E9, when comparing batteries with the same maximum height Rz, the surface area of ​​the fibers per gram of positive electrode material (S ( / 1g)) was 1.35 cm². ２ Compared to battery E6, which has a value of less than 1.35 cm³, S ( / 1g) is 1.35 cm³. ２ As shown above, batteries E3, E7-E9 exhibit good deep discharge life (50% DOD). This is thought to be because the large contact area allows the fibers and lead compound to intertwine, resulting in a higher anchoring effect from the fibers. 【0274】 Based on the results for batteries E28, E29, and R10, it is considered that when the maximum surface height Rz of the fibers exceeds 1.90 μm, the capacity retention rate tends to decrease as the surface area of ​​fibers per gram of positive electrode material (S( / 1g)) increases. On the other hand, a comprehensive assessment of Table 7 shows that when the maximum surface height Rz of the fibers is less than 1.90 μm, the decrease in capacity retention rate is suppressed even if the surface area of ​​fibers per gram of positive electrode material (S( / 1g)) increases. In particular, when the maximum surface height Rz of the fibers is between 0.17 μm and 1.40 μm, the decrease in capacity retention rate when the surface area of ​​fibers per gram of positive electrode material (S( / 1g)) increases is significantly suppressed. 【0275】The lead-acid battery according to the above aspects of the present invention can be suitably used, for example, as a starting power source for IS (idle stop) applications (for lead-acid batteries in ISS (idle stop start) vehicles), as an auxiliary power source for electric vehicles and hybrid vehicles, and as a power source for industrial energy storage devices such as electric vehicles (forklifts, etc.). However, these applications are merely examples, and the lead-acid battery according to the above aspects of the present invention is not limited to these applications. 【0276】 Although the present invention has been described in relation to preferred embodiments at present, such disclosure should not be interpreted restrictively. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the field to which the invention pertains by reading the above disclosure. Accordingly, the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention. 【0277】 1: Lead-acid battery, 2: Negative electrode plate, 3: Positive electrode plate, 4: Separator, 5: Positive electrode strap, 6: Negative electrode strap, 7: Positive electrode column, 8: Through connector, 9: Negative electrode column, 11: Electrode plate group, 12: Battery case, 13: Partition wall, 14: Cell chamber, 15: Cover, 16: Negative electrode terminal, 17: Positive electrode terminal, 18: Electrode cap

Claims

1. The device comprises a positive electrode plate, a negative electrode plate, an electrolyte, and a separator interposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate includes a positive electrode current collector and a positive electrode material, the positive electrode material includes fibers, and the surface area of ​​the fibers per gram of the positive electrode material is 1.35 cm². ２ That concludes the explanation of lead-acid batteries.

2. The surface area of ​​the fibers per gram of the positive electrode material is 1.70 cm². ２ The lead-acid battery according to claim 1.

3. The surface area of ​​the fibers per gram of the positive electrode material is 3.00 cm². ２ The lead-acid battery according to claim 1.

4. The cumulative pore volume of the positive electrode material in the range of pore diameters from 0.006 μm to 15 μm is 0.167 cm³. ３ The lead-acid battery according to claim 1, wherein the value is less than or equal to / g.

5. The cumulative pore volume of the positive electrode material in the range of pore diameters from 0.006 μm to 15 μm is 0.080 cm³. ３ / g or more, 0.130cm ３ The lead-acid battery according to claim 1, wherein the value is less than or equal to / g.

6. The fiber density is 1.40 g / cm³. ３ The lead-acid battery according to claim 1, which is as follows:

7. The lead-acid battery according to claim 1, wherein the surface of the fiber has irregularities, and the irregularities are formed along the circumferential direction of the fiber.

8. The lead-acid battery according to claim 1, wherein the average surface roughness Ra of the fibers is 0.1 μm or more and 1.3 μm or less.

9. The BET specific surface area of the fiber measured using krypton gas as the adsorption gas is 0.3 m ２ / g or more and 1.0 m ２ / g or less. The lead storage battery according to claim 1.

10. The lead-acid battery according to claim 1, wherein the maximum surface height Rz of the fiber is 0.17 μm or more and 1.90 μm or less.

11. The lead-acid battery according to claim 1, wherein the average fiber diameter of the fibers is 1 μm or more and 8 μm or less.

12. The lead-acid battery according to claim 1, wherein the resin constituting the fibers is polyethylene terephthalate.

13. The lead-acid battery according to claim 1, wherein the fiber content in the positive electrode material is 0.05% by mass or more and 0.23% by mass or less.

14. The area of ​​the opening in the grid portion of the positive electrode current collector is 50 mm². ２ A lead-acid battery according to claim 1, satisfying the requirement of one or more units.

15. The lead-acid battery according to claim 1, wherein at least one of a pair of lower corners of the positive electrode plate is chamfered.

16. The lead-acid battery according to claim 1, used for supplying power to in-vehicle equipment that transmits and receives data via wireless communication.

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