Liquid lead-acid battery

Abstract

A liquid lead-acid battery with excellent lifespan characteristics is provided. The positive current collector (5) constituting the liquid lead-acid battery of the present invention is formed of a lead alloy having a rolled structure, and the grid-shaped substrate (51) of the positive current collector has a frame skeleton and a plurality of middle skeletons. The frame skeleton has: an upper frame skeleton (511) located on the upper side of the grid-shaped substrate and extending laterally; a lower frame skeleton (512) located on the lower side and extending laterally; and a pair of longitudinal frame skeletons (513, 514) extending longitudinally. The tab (22) protrudes upward from a position offset from the center of the long side of the upper frame skeleton toward one side close to either of the pair of longitudinal frame skeletons. The middle skeleton has: a plurality of longitudinal middle skeletons (516) from each position of the upper frame skeleton toward the lower frame skeleton side; and a plurality of transverse middle skeletons (517) connecting the pair of longitudinal frame skeletons. At least one of the multiple transverse central frames is a coarse transverse central frame (517a, 517b) with a cross-sectional area B that is larger than the average cross-sectional area A of the multiple transverse central frames, and the ratio of the cross-sectional areas B / A is 1.15 or more.

Description

Technical Field

[0001] This invention relates to liquid lead-acid batteries. Background Technology

[0002] In response to the deepening environmental problems and emission restrictions in recent years, cars equipped with idle stop systems (hereinafter referred to as "ISS cars") have gradually become more common. ISS cars suppress fuel consumption by stopping the engine when stopped, such as while waiting at traffic lights, thus improving fuel efficiency and further reducing emissions.

[0003] It is known that lead-acid batteries installed in ISS vehicles, as described above, tend to reach the end of their lifespan relatively quickly. The reason is as follows: In ISS vehicles, lead-acid batteries are used to a deep discharge level to supply power to systems such as the air conditioner, lights, wipers, and navigation system when the engine stops while waiting at traffic lights, etc. Furthermore, they are repeatedly discharged to restart the engine during start-up and charged by the alternator and regenerative braking system. Due to this harsh use, lead-acid batteries suffer significant damage, especially to their power generation components.

[0004] In a typical liquid lead-acid battery, the electrode assembly, which is a power generation element, is a laminate consisting of multiple alternating positive electrodes, a negative electrode, and a separator disposed between the positive and negative electrodes. Furthermore, the positive electrode has a positive current collector and a positive electrode binder containing positive active material. The positive active material contains lead dioxide. The positive current collector has a rectangular grid-like substrate and tabs (also called "current collector tabs") continuous with the grid-like substrate. The positive electrode binder is held in the grid-like substrate. The tabs of multiple positive electrodes are connected by positive electrode connecting pieces.

[0005] The negative electrode plate has a negative current collector and a negative electrode mixture containing a negative active material. The negative active material contains metallic lead. The negative current collector has a rectangular grid-like substrate and tabs continuous with the grid-like substrate. The negative electrode mixture is held in the grid-like substrate. The tabs of multiple negative electrode plates are connected by negative electrode connecting pieces. The positive and negative current collectors are mainly made of lead or lead alloys.

[0006] An example of a grid-like substrate is shown, comprising a frame skeleton with four rectangular sides and a plurality of middle frames connected to the frame skeleton and located on the inner side of the frame skeleton. In this grid-like substrate, the frame skeleton comprises: an upper frame skeleton located on the upper side of the grid-like substrate and extending laterally; a lower frame skeleton located on the lower side of the grid-like substrate and extending laterally; and a pair of longitudinal frame skeletons extending longitudinally. An electrode lug protrudes upward from a position offset from the center of the long side of the upper frame skeleton towards one side of either of the pair of longitudinal frame skeletons. The plurality of middle frames comprises: a plurality of longitudinal middle frames extending from the upper frame skeleton towards the lower frame skeleton or from the lower frame skeleton towards the upper frame skeleton; and a plurality of transverse middle frames extending from one side of the pair of longitudinal frame skeletons towards the other side or from the other side of the pair of longitudinal frame skeletons towards one side. Furthermore, the space enclosed by the frame skeleton and the plurality of middle frames, or the space enclosed only by the plurality of middle frames, exists as an opening in the grid-like substrate.

[0007] The positive electrode binder fills at least the opening of the grid-shaped substrate of the positive electrode current collector. The negative electrode binder fills at least the opening of the grid-shaped substrate of the negative electrode current collector.

[0008] The battery case of a liquid lead-acid battery is a box-shaped structure with an opening at the top, and has multiple cell compartments for housing the electrode plates. These cell compartments are separated by partitions. The opening of the battery case is sealed with a cover.

[0009] The cover insert has a metal component that forms a terminal (e.g., a bushing). Additionally, the cover has a communication port (also called a "liquid port") for injecting electrolyte. The position and number of liquid ports correspond to the position and number of the cell compartments in the battery cell. Both the battery cell and the cover are formed of an acid-resistant resin. Examples of acid-resistant resins include polypropylene, polyester, and ABS.

[0010] As the electrolyte, dilute sulfuric acid at a concentration of approximately 1.28 is used. Sometimes, depending on the desired performance of the liquid lead-acid battery, additives such as aluminum sulfate are added to the electrolyte.

[0011] In designing high-durability liquid lead-acid batteries, countermeasures against cell growth are necessary. Growth is a phenomenon caused by the corrosion of the positive electrode grid (the grid-like substrate of the positive current collector), resulting in the overall expansion and deformation of the positive electrode grid. If growth occurs, the positive electrode grid may locally bend and break, with the broken end piercing the separator, potentially causing contact with the opposite negative electrode plate or expanding upwards to partially contact the negative electrode connector or other negative electrode components, leading to an internal short circuit. Furthermore, deformation of the positive electrode grid causes the positive electrode binder to peel off or detach, resulting in premature capacity reduction.

[0012] The mechanism of growth is believed to be as follows. Not limited to liquid-type batteries, corrosion of the positive grid in lead-acid batteries is due to the lead or lead alloy forming the positive grid reacting primarily with sulfate ions contained in the electrolyte and positive electrode agent, leading to corrosion of PbO. x The corrosion is caused by an oxidation reaction resulting in a multilayered structure of corrosion products, including (x: 1-2), PbSO4, etc. This corrosion is primarily exacerbated by repeated charging and discharging. In particular, the growth of the corrosion product layer is significant on the surface of the positive electrode grid in contact with sulfate ions. This growth generates a pulling force that causes the surface of the positive electrode grid to expand. On the other hand, the lead alloy in the central portion, away from the surface, attempts to prevent surface deformation. Therefore, if corrosion intensifies, complex stresses are generated, and deformation preferentially begins from the areas with significant stress differences. As a result, the positive electrode grid expands overall, resulting in growth.

[0013] The growth is effective in preventing corrosion of the positive electrode grid and improving mechanical strength.

[0014] The potential distribution of the positive electrode grid is closely related to the corrosion rate. For the portion of the positive electrode grid furthest from the tab (the area near the corner formed by the longitudinal and lower frame frames on the side furthest from the tab: the diagonal region), the current path is longer than in other parts, thus, according to Ohm's law, the DC resistance increases. Therefore, the polarization near the tab is smaller, and the diagonal region is larger for current extraction. It is known that the closer to the tab, the easier it is for a large current to flow through the positive electrode grid, and the more severe the corrosion. Furthermore, it is also known that the active material near the tab preferentially participates in the charge-discharge reaction; therefore, deterioration such as softening and detachment of the positive electrode binder is more easily aggravated.

[0015] The potential distribution varies significantly depending on the shape and configuration of the longitudinal and transverse frame skeletons. The closer the longitudinal frame skeleton is to being vertical or the closer the transverse frame skeleton is to being horizontal, the greater the potential difference between the area near the electrode and the diagonal region. In other words, the closer the angle between the upper and lower frame skeletons and the longitudinal frame skeleton is to 90°, or the closer the angle between each longitudinal frame skeleton and the transverse frame skeleton is to 90°, the greater the potential difference between the area near the electrode and the diagonal region.

[0016] Therefore, the difference in the deterioration of a simple grid-shaped positive electrode plate grid with all longitudinal and transverse cores being orthogonal is easily amplified depending on the location when viewed from above, and this imbalance can lead to a problem of short lifespan.

[0017] In contrast, Patent Documents 1 and 2 disclose grids for liquid lead-acid batteries that are not simply grid-shaped.

[0018] In patent document 1 Figure 4In the illustrated positive electrode grid, the protruding position of the tab is offset to the right from the center of the long side of the upper frame. All the longitudinal frames are arranged along a diagonal line that starts from a point on a line extending upwards from the center line of the tab's width direction and ends at the lower frame or the left and right longitudinal frames. Furthermore, as the connection points of the longitudinal frames located to the right and left of the aforementioned baseline, respectively, with the upper frame of the longitudinal frame, move away from the tab, the starting point of the aforementioned diagonal line points upwards. As a result, compared to a simple grid-shaped positive electrode grid, the current path from the diagonal region to the tab is shortened.

[0019] Therefore, compared to a simple grid shape, the resistance is lower, resulting in a better in-plane potential distribution. However, in this type of positive electrode grid, the area of ​​the opening increases further away from the tab. Consequently, under conditions of vibration and impact, such as during vehicle use, the active material is prone to detachment, leading to a decrease in discharge capacity and thus a reduction in lifespan.

[0020] In the grid disclosed in Patent Document 2, the longitudinal central skeleton on the side near the awl extends vertically relative to the upper frame skeleton and the lower frame skeleton. Other longitudinal central skeletons extend obliquely and radially (along multiple lines extending from a single point) from the lower frame skeleton side in the diagonal region toward the upper frame side or toward the vertically extending longitudinal central skeleton side. Furthermore, there are seven radially expanding longitudinal central skeletons, four of which are directly connected to the upper frame skeleton, and the remaining three are directly connected to the vertically extending longitudinal central skeletons.

[0021] In a liquid lead-acid battery with such a grid shape, if a large current is required for applications such as engine starting, according to Kirchhoff's first law, a large current is concentrated in the vertically extending longitudinal frame near the tabs. As a result, corrosion rapidly intensifies and resistance increases for the vertically extending longitudinal frame. If corrosion worsens further, it may lead to breakage or fracture. Consequently, the current drawn from the radially expanding longitudinal frame decreases, and therefore, the battery performance is likely to deteriorate drastically.

[0022] Patent document 3 describes that, in order to prevent accelerated upward growth, a transverse rib (transverse middle frame) with a large cross-sectional area is provided in the upper region of the frame on the opposite side of the position where the positive electrode collector tab is connected.

[0023] Existing technical documents

[0024] Patent documents

[0025] Patent Document 1: Japanese Patent Application Publication No. 2019-67522

[0026] Patent Document 2: Japanese Patent Application Publication No. 2002-42821

[0027] Patent Document 3: Japanese Patent No. 6456537 Summary of the Invention

[0028] The technical problem that the invention aims to solve

[0029] The objective of this invention is to provide a liquid lead-acid battery with excellent lifespan characteristics.

[0030] Solutions for solving technical problems

[0031] The first aspect of the present invention provided to solve the above-mentioned problems is a liquid lead-acid battery having the following structures (1) to (4).

[0032] (1) A liquid lead-acid battery comprising a unit cell housing an electrolyte and an electrode assembly, the electrode assembly being a laminate composed of alternating positive and negative electrode plates and a separator disposed between the positive and negative electrode plates. The positive electrode plate has a positive current collector and a positive electrode binder containing a positive active material, the positive active material containing lead dioxide. The positive current collector has a rectangular grid-like substrate and tabs continuous with the grid-like substrate. The positive electrode binder is held in the grid-like substrate.

[0033] (2) The positive current collector is formed of a lead alloy with a rolled structure. The grid-shaped substrate has: a frame skeleton that forms the rectangular four sides of the grid-shaped substrate; and a plurality of middle frames connected to the frame skeleton and existing inside the frame skeleton. The frame skeleton has: an upper frame skeleton located on the upper side of the grid-shaped substrate and extending laterally; a lower frame skeleton located on the lower side of the grid-shaped substrate and extending laterally; and a pair of longitudinal frame skeletons extending longitudinally.

[0034] (3) The tabs protrude upwards from a position offset from the center of the long side of the upper frame towards one side of either of the pair of longitudinal frame frames. The multiple middle frames have: multiple longitudinal middle frames extending from various positions of the upper frame towards the lower frame frame; and multiple transverse middle frames connecting the pair of longitudinal frame frames.

[0035] (4) At least one of the multiple transverse central frames is a coarse transverse central frame with a cross-sectional area B that is larger than the average cross-sectional area A of the multiple transverse central frames, and the ratio of the cross-sectional areas B / A is greater than 1.15.

[0036] In addition, the average value A is the average cross-sectional area of ​​all horizontal skeletons, including the thick horizontal skeleton.

[0037] In addition, a "positive current collector formed of a lead alloy with a rolled structure" can be obtained, for example, by punching or drawing a rolled plate relative to a lead alloy slab rolled to a predetermined thickness using a multi-stage rolling mill.

[0038] Furthermore, the horizontal central frame can have two cases: one where the cross-sectional area is uniform along its long side; and another where the cross-sectional area varies along its long side, such that the cross-sectional area decreases from at least one of the longitudinally extending right and left frame frames towards the center. In the case where the cross-sectional area varies along its long side, the minimum value of the cross-sectional area is used to calculate the ratio B / A.

[0039] The second aspect of the present invention provided to solve the above-mentioned problems is a liquid lead-acid battery having the above-described structures (1) to (3) and the following structures (5) and (6).

[0040] (5) It has: a plurality of first longitudinal central frames as the aforementioned longitudinal central frames, which extend from the position directly below the aforementioned tab of the aforementioned lower frame in a way that is inclined toward the aforementioned lower frame from each position of the aforementioned upper frame frame; and a second longitudinal central frame as the aforementioned longitudinal central frames, which is arranged at the position closest to the first longitudinal frame frames as the aforementioned longitudinal frame frames and reaches the aforementioned lower frame frame, wherein the aforementioned longitudinal frame frames are located on the side away from the aforementioned tab.

[0041] (6) The angle θ between the straight line representing the direction of extension of the second longitudinal frame and the straight line representing the direction of extension of the first longitudinal frame. L It is between -10° and 10°.

[0042] Additionally, angle θ L The sign of is defined as follows: negative when the second longitudinal frame moves from the upper frame to the lower frame and towards the longitudinal frame (second longitudinal frame) on one side closer to the pole lug, and positive when it moves towards the first longitudinal frame.

[0043] Invention Effects

[0044] According to the present invention, it is expected to provide a liquid lead-acid battery with excellent lifespan characteristics. Attached Figure Description

[0045] Figure 1 This is a partial cross-sectional view illustrating the structure of a liquid lead-acid battery according to an embodiment of the present invention.

[0046] Figure 2 This is a front view showing the positive current collector of the liquid lead-acid battery according to the first embodiment of the present invention.

[0047] Figure 3 This is a front view showing the positive current collector of the liquid lead-acid battery according to the second embodiment of the present invention.

[0048] Figure 4 This is a front view showing the positive current collector of the liquid lead-acid battery according to the third embodiment of the present invention. Detailed Implementation

[0049] [The inventor's insights]

[0050] [Discovery of the first topic]

[0051] As disclosed in the embodiment of Patent Document 3 (refer to paragraph 0128 of Patent Document 3), when the positive electrode grid (grid-shaped substrate of the positive electrode current collector) is a longitudinally elongated shape with a longitudinal dimension (excluding the tab) larger than the transverse dimension, the longitudinal growth tends to increase, and short circuits between the positive electrode and the negative electrode connecting piece above become a factor affecting the lifespan.

[0052] However, the inventors' research shows that when the positive electrode grid has a transversely elongated shape where the lateral dimension is larger than the longitudinal dimension (excluding the tabs), lateral growth tends to be greater than longitudinal growth. Furthermore, it is known that if lateral growth is aggravated, the expanding positive electrode plate's left and right frame structures sometimes stretch and tear the contact separator. As a result, the positive and negative electrodes, which are stacked together through the separator, short-circuit, reaching their lifespan earlier. Additionally, even if the separator isn't torn, corrosion-damaged positive electrode grids can partially puncture the separator, causing a short circuit with the negative electrode plate and also reaching their lifespan earlier.

[0053] Current collectors formed from lead alloys with rolled structures (e.g., obtained by punching or drawing a rolled sheet relative to a lead alloy) have a rolled structure consisting of tiny fibrous crystalline structures composed of lead alloy grains oriented in a constant direction. Therefore, growth associated with corrosion is easily aggravated. On the other hand, current collectors (cast sheets) obtained by casting lead alloys are known to have coarse granular crystalline structures, with preferential corrosion at grain boundaries; therefore, growth is less likely to be aggravated. The significant difference in growth rate is greatly influenced by the crystalline structure (small grain boundaries with active dislocation movement promote creep); therefore, growth is significantly aggravated in rolled sheets compared to cast sheets.

[0054] In addition, grid-shaped substrates formed by casting and punching methods usually have thicker frame skeletons at the top and bottom compared to the left and right frame skeletons. Therefore, the upper and lower parts have high mechanical strength and are less prone to lateral elongation compared to the longitudinal direction.

[0055] On the other hand, a relatively thinner intermediate frame is arranged on the inner side of the frame skeleton, particularly near the central portion in the vertical direction. Because it is far from the upper and lower frame skeletons, its mechanical strength is insufficient compared to the upper and lower parts of the grid-like substrate. When using such a grid-like substrate, if corrosion generates a force that causes the entire electrode plate to expand, a barrel-shaped deformation is visible laterally, with smaller changes at the upper and lower parts and a larger change in the central part. This barrel-shaped deformation is more pronounced in the transversely elongated positive electrode grid compared to the longitudinally elongated positive electrode grid.

[0056] The reason is unclear, but it is inferred that, in addition to the expansion and contraction of the positive electrode active material in the positive electrode mixture filling the opening of the positive electrode grid due to charging and discharging, the expansion and contraction forces propagate from the center of the positive electrode grid towards the outer periphery, and the large force is exerted near the outer periphery due to the sum of the propagation forces. Furthermore, the expansion and contraction forces are proportional to the volume of the positive electrode active material. In summary, when the positive electrode grid is longitudinally elongated, a larger expansion force is easily generated in the vertical direction, and when it is transversely elongated, a larger expansion force is easily generated in the horizontal direction. In particular, in the case of transverse elongation, the mechanical strength of the central part in the vertical direction is smaller than that of the upper and lower parts; therefore, significant barrel-shaped deformation is observed.

[0057] Furthermore, it is known that when the horizontally elongated positive electrode grid deforms into a barrel shape as described above, and further use leads to increased growth and weight, the deformation of the positive electrode grid does not stop at the central part. Instead, the lower part, which has less mechanical strength than the upper part, deforms, and the shape of the positive electrode grid changes from a barrel shape to a mountain shape. This mountain-shaped deformation is a new problem discovered by the inventors in their research on liquid lead-acid batteries that suppress upper short circuits and extend battery life by utilizing the invention described in Patent Document 3.

[0058] The difference in mechanical strength between the upper and lower parts of the positive electrode grid is briefly described.

[0059] First, the positive electrode grid is typically designed to exhibit a uniform potential distribution from top to bottom, allowing the positive electrode active material to be used during charging and discharging. Therefore, a method is employed where multiple reinforcing mid-frames are provided in the upper part of the positive electrode grid to reduce the area of ​​the opening near the current collector tabs and improve the current collection efficiency of the positive electrode active material. On the other hand, due to the need for lightweight design, reinforcing mid-frames are often not provided in the lower part of the positive electrode grid. This results in a higher mechanical strength in the upper part of the positive electrode grid due to the higher density of the mid-frames compared to the lower part.

[0060] In addition, in the invention described in Patent Document 3, in order to prevent accelerated upward growth, a horizontal rib with a large cross-sectional area (horizontal middle rib) is arranged in the upper region of the frame frame on the opposite side of the position where the positive electrode collector tab is connected, so that the difference in mechanical strength between the upper and lower parts of the positive electrode grid is greater.

[0061] As mentioned above, if a positive electrode plate with a horizontally elongated grid-like substrate is used for a long period of time, the grid-like substrate will deform into a barrel shape, which may cause the separator to tear laterally and cause a short circuit between it and the negative electrode plate.

[0062] [The function and effect of the lead-acid battery of the first embodiment of the present invention]

[0063] In contrast, the lead-acid battery of the first aspect of the present invention has the above-described structure (4) in the lead-acid battery having the above-described structures (1) to (3). In other words, at least one of the plurality of transverse central frames is a thick transverse central frame with a cross-sectional area B that is larger than the average cross-sectional area A of the plurality of transverse central frames, and the ratio of the cross-sectional areas B / A is 1.15 or more. As a result, the mechanical strength of the positive plate is improved and it is not easy to elongate in the lateral direction, and the barrel-shaped or mountain-shaped deformation of the positive plate grid (grid-shaped substrate of the positive current collector) can be suppressed.

[0064] In other words, by providing at least one thick transverse frame in the longitudinal direction of the positive electrode grid, which is prone to lateral elongation, below the central portion, the mechanical strength is improved, making it less prone to lateral elongation and suppressing barrel-shaped or mountain-shaped deformation of the positive electrode grid. Furthermore, preventing deformation of the positive electrode grid also suppresses the peeling and shedding of the active material. Therefore, in addition to suppressing the decrease in discharge capacity, it also prevents corrosion of the grid-like substrate caused by the intrusion of electrolyte into the areas resulting from the peeling and shedding of the active material, and prevents premature end of life due to accelerated growth.

[0065] In other words, according to one aspect of the invention, a lead-acid battery with a long lifespan is provided by suppressing the growth associated with corrosion of the grid-like substrate in the positive current collector made of rolled plate, thereby suppressing short circuits caused by contact between the positive and negative plates.

[0066] Furthermore, the more coarse horizontal cores there are, the larger the cross-sectional area of ​​the coarse horizontal cores will be, and the greater the effect of suppressing deformation, but it will increase the weight of the battery. Therefore, from the viewpoint of not hindering the lightweighting of lead-acid batteries, it is preferable that the cross-sectional area ratio B / A is 1.25 or less.

[0067] [Discovery of the second topic]

[0068] It is known that in a configuration where the positive electrode grid is horizontally elongated and the longitudinal central skeleton extends obliquely from each position of the upper frame skeleton towards the lower frame skeleton, directly below the tab of the lower frame skeleton, and the tab protrudes upward from a position offset from the center of the long side of the upper frame skeleton towards the side closer to the right frame skeleton, deformation of the left frame skeleton (as the first longitudinal frame skeleton of the longitudinal frame skeleton on the side furthest from the tab) promotes the peeling and detachment of the positive electrode adhesive. Particular attention should be paid to the peeling and detachment of the positive electrode adhesive filling the multiple openings adjacent to the left frame skeleton. For ease of explanation, the positive electrode adhesive filling the multiple openings adjacent to this left frame skeleton is referred to as the left-end positive electrode adhesive. Furthermore, the opening filled with the left-end positive electrode adhesive is referred to as the left-end opening. And, the longitudinal central skeleton forming the left-end opening is referred to as the left-end longitudinal central skeleton (the longitudinal central skeleton furthest from the tab). That is, in this case, the left-end longitudinal central skeleton is the longitudinal central skeleton positioned closest to the left frame skeleton (the first longitudinal frame skeleton).

[0069] The relationship between the peeling and shedding of the positive electrode compound on the left end and the shape of the positive electrode grid is explained.

[0070] The positive electrode adhesive on the left end adheres tightly to the left frame skeleton like cement, preventing contact between the left frame skeleton and the electrolyte, and preventing deformation such as elongation and bending of the left frame skeleton. Therefore, if the positive electrode adhesive on the left end peels off from the left frame skeleton or falls off from the left end opening, it fails to prevent surface corrosion of the left frame skeleton, and the aforementioned accelerated growth is aggravated. Once peeled off, the positive electrode adhesive on the left end also lacks the force to prevent such deformation of the left frame skeleton.

[0071] The larger the opening area of ​​the left-end opening when viewed from above, the easier it is for the positive electrode compound on the left end to peel off / detach. This is because the contact area per unit volume of the positive electrode compound with the positive electrode grid becomes smaller. Furthermore, the more it is used in a partially charged state, such as when installed in an ISS vehicle, the more severe the softening becomes, thus making it easier to peel off / detach. In particular, external vibrations during vehicle use can easily cause the softened positive electrode compound to peel off / detach.

[0072] In a configuration where all longitudinal frames extend obliquely from various positions of the upper frame towards the lower frame, directly below the tabs of the lower frame, the opening area is larger when viewed from above as it is further away from the tab. Therefore, the opening at the left end, furthest from the tab, has a relatively large area, making it more prone to peeling and detachment compared to the positive electrode filler used in other openings.

[0073] Based on the above, when the positive electrode grid is horizontally elongated and the longitudinal frame is configured as described above, the positive electrode filler at the left opening is particularly prone to peeling and shedding. This may be the reason for the short lifespan of liquid lead-acid batteries used in partially charged states, such as those in ISS vehicles.

[0074] [The function and effect of the lead-acid battery of the second aspect of the present invention]

[0075] In contrast, in the liquid lead-acid battery of the second aspect of the present invention, it is known that: in the lead-acid battery having the above-described structures (1) to (4), the above-described structures (5) and (6) are also included; in other words, the angle θ is... L The temperature range is between -10° and 10°, thus significantly suppressing the peeling and shedding of the positive electrode compound (the "left-end positive electrode compound") disposed in the opening (the "left-end opening") formed by the first longitudinal frame skeleton (the longitudinal frame skeleton on the side away from the tab), the second longitudinal middle frame skeleton (the aforementioned longitudinal middle frame skeleton disposed at the position closest to the first longitudinal frame skeleton and reaching the lower frame skeleton), and a pair of transverse middle frames (or the transverse middle frame skeleton and the upper frame skeleton or the lower frame skeleton).

[0076] From the perspective of improving lifespan, angle θ L Preferably -5° to 5°, more preferably -2° to 3°.

[0077] The reason is unclear, but it is believed to be as follows.

[0078] It is known that the growth of the first longitudinal frame of the positive electrode grid (the aforementioned "left frame frame") is accelerated and aggravated by the peeling and shedding of the left-end positive electrode compound filling the left-end opening. Moreover, the accelerated growth aggravates the deformation of the left frame frame and its surrounding longitudinal frames, further accelerating the peeling and shedding of the left-end positive electrode compound. Therefore, in order to prevent such peeling and shedding of the left-end positive electrode compound and thus extend the lifespan of the liquid lead-acid battery, it can be said that the key is to delay the "initial peeling or shedding of the left-end positive electrode compound".

[0079] When viewed from above, the angle θ L The closer the area difference is to 0, the smaller the vertical area difference between the multiple left-end openings. As mentioned above, the area difference between the openings is positively correlated with the ease with which the positive electrode filler filled there will peel off or detach. That is, by reducing the vertical area difference between the multiple left-end openings, the initial peeling off or detachment of the left-end positive electrode filler can be delayed.

[0080] In addition, the minimum separation distance d between the first vertical frame and the second vertical frame is... L The thickness is between 5.0 mm and 10.0 mm. The reasons are as follows.

[0081] If the opening area at the left end is too small, the pressure needs to be increased during the pressing process based on pressure rollers, etc., in the process of filling the positive electrode grid with positive electrode paste. If the distance d LIf the diameter is 5.0 mm or more and 10.0 mm or less, the opening at the left end becomes an opening area suitable for filling with paste, thus reducing manufacturing costs.

[0082] Distance d L A range of 5.0 mm to 10.0 mm is particularly suitable for the flowability of positive electrode paste in ISS automotive liquid lead-acid batteries. The flowability of the positive electrode paste varies depending on the density of the positive electrode compound, reinforcing materials, and additives. The greater the emphasis on the durability of the liquid lead-acid battery, the more likely the flowability of the positive electrode paste will decrease, and the greater the pressure required during filling will be. From the viewpoint of further extending battery life, an angle θ is particularly preferred. L =0 and 3.0mm≤d L ≤10.0mm.

[0083] [Implementation Method]

[0084] Embodiments of the present invention will be described below. Furthermore, the embodiments described below illustrate examples of the present invention, and the present invention is not limited to these embodiments. In addition, various modifications or improvements can be made to these embodiments, and forms in which such modifications or improvements are made may also be included in the present invention.

[0085] [Overall structure of the liquid lead-acid battery according to the embodiment]

[0086] The liquid lead-acid battery of the first embodiment, the second embodiment, and the third embodiment, such as Figure 1 As shown, a plurality of alternating electrode groups 1, comprising positive electrode 10 and negative electrode 20 separated by a ribbed separator 30, are arranged. The electrode groups 1 are housed together with an electrolyte (not shown) in a cell chamber of a battery cell 41, with their stacking direction along the horizontal direction (i.e., with the surfaces of the positive electrode 10 and negative electrode 20 along the vertical direction), and are immersed in the electrolyte within the cell chamber of the battery cell 41. In other words, the liquid lead-acid battery according to this embodiment includes: electrode groups 1 and a battery cell 41 having cell chambers, wherein the cell chambers house the electrode groups 1 together with the electrolyte, one electrode group 1 is housed in one cell chamber, and the number of positive electrode 10 constituting the electrode group 1 is less than or equal to the number of negative electrode 20.

[0087] The positive electrode plate 10 has a positive current collector and a positive electrode mixture containing a positive active material, which contains lead dioxide. The positive current collector has a rectangular grid-like substrate and tabs 11 continuous with the grid-like substrate, and the positive electrode mixture is held in the grid-like substrate. The negative electrode plate 20 has a negative current collector and a negative electrode mixture containing a negative active material, which contains metallic lead. The negative current collector has a rectangular grid-like substrate and tabs 21 continuous with the grid-like substrate, and the negative electrode mixture is held in the grid-like substrate.

[0088] The positive electrode and negative electrode fill the openings of each grid-shaped substrate and exist as an agent layer on both sides of the grid-shaped substrate.

[0089] The positive current collector is described in detail below. The negative current collector constituting the negative electrode plate 20 is formed by a punching method using a lead alloy rolled sheet. Other manufacturing methods for the positive and negative current collectors besides the punching method include casting of lead alloys and wire drawing using a lead alloy rolled sheet. The separator 30 is, for example, a porous film-like body made of resin, glass, etc., and has a flat base surface and pleated ribs that protrude in a direction orthogonal to the surface direction of the base surface as needed.

[0090] The tabs 11 of multiple positive plates 10 are connected by positive connecting pieces 13, and the tabs 21 of multiple negative plates 20 are connected by negative connecting pieces 23. Furthermore, the positive connecting piece 13 is connected to one end of the positive terminal 15, the negative connecting piece 23 is connected to one end of the negative terminal 25, and the other ends of the positive terminal 15 and the other ends of the negative terminal 25 pass through the cover 43 that blocks the opening of the battery cell 41, and are exposed on the outside of the casing of the liquid lead-acid battery formed by the battery cell 41 and the cover 43.

[0091] [Regarding the positive current collector of the first embodiment]

[0092] like Figure 2 As shown, the positive current collector 5 constituting the positive electrode plate 10 of the first embodiment is formed by punching a rolled sheet made of lead alloy, and has a horizontally elongated rectangular grid-like substrate 51 and tabs 11 continuous with the grid-like substrate, on which the positive electrode alloy is held. Furthermore, regarding the positive current collector 5, a striped rolled structure is observed in a cross-section perpendicular to the plate surface. This rolled structure is formed by stretching the metal crystals in the lead alloy into thin layers through rolling. Thus, the positive current collector 5 is formed from a lead alloy having a rolled structure.

[0093] The grid-shaped substrate 51 has: a frame skeleton that is rectangular with four sides; and a plurality of intermediate skeletons connected to the frame skeleton and existing on the inner side of the frame skeleton.

[0094] The frame skeleton is composed of an upper frame skeleton 511 located on the upper side of the grid-shaped substrate and extending laterally, a lower frame skeleton 512 located on the lower side of the grid-shaped substrate and extending laterally, a left frame skeleton 513 located on the left side of the grid-shaped substrate and extending longitudinally, and a right frame skeleton 514 located on the right side of the grid-shaped substrate and extending longitudinally.

[0095] The tab 11 protrudes upward from a position offset from the center of the long side of the upper frame 511 toward the right frame 514. The multiple middle frames consist of multiple longitudinal middle frames 516 extending from various positions of the upper frame 511 toward the lower frame 512 and multiple transverse middle frames 517 connecting the left frame 513 and the right frame 514.

[0096] In the grid-shaped substrate 51, all the longitudinal central frames 516 are arranged along a diagonal line that starts at a point on a reference line extending upwards from a line perpendicular to the lower frame frame 512 to the right of the electrode tab and ends at either the lower frame frame 512 or the transverse central frame 517. Furthermore, the starting point of the diagonal line is upwards as the connection points of the longitudinal central frames located to the upper frame of the longitudinal central frame, respectively, to the right and left of the aforementioned reference line, move away from the electrode tab. As a result, compared to a simple grid-shaped positive electrode grid, the current path from the diagonal region to the electrode tab is shortened.

[0097] Moreover, two of the multiple transverse central frames 517 are coarse transverse central frames 517a and 517b with a cross-sectional area B that is larger than the average cross-sectional area A of the multiple transverse central frames 517, and the ratio of their cross-sectional areas B / A is 1.15 or more.

[0098] When the distance between the longitudinal center positions of the upper frame skeleton and the lower frame skeleton is set to L0, and the distance between the longitudinal center position of the upper frame skeleton and the longitudinal center position of the thick horizontal frame 517a is set to L1, the ratio L1 / L0 is 0.66. When the distance between the longitudinal center position of the upper frame skeleton and the longitudinal center position of the thick horizontal frame 517b is set to L2 (<L1), the ratio L2 / L0 is 0.47.

[0099] In other words, in the liquid lead-acid battery of the first embodiment, the grid-shaped substrate 51 constituting the positive current collector 5 of the positive electrode plate 10 has two coarse horizontal central skeletons 517a and 517b. The coarse horizontal central skeleton 517a exists in the lower half region, and the coarse horizontal central skeleton 517b exists near the longitudinal central part of the grid-shaped substrate 51.

[0100] [Regarding the positive current collector in the second embodiment]

[0101] like Figure 3As shown, the positive current collector 5 constituting the positive electrode plate 10A of the second embodiment is formed by punching a rolled sheet made of lead alloy, and has a horizontally elongated rectangular grid-like substrate 51 and tabs 11 continuous with the grid-like substrate, on which the positive electrode alloy is held. Furthermore, regarding the positive current collector 5, a striped rolled structure is observed in a cross-section perpendicular to the plate surface. This rolled structure is formed by stretching the metal crystals in the lead alloy into thin layers through rolling. Thus, the positive current collector 5 is formed from a lead alloy having a rolled structure.

[0102] The grid-shaped substrate 51 has: a frame skeleton that is rectangular with four sides; and a plurality of intermediate skeletons connected to the frame skeleton and existing on the inner side of the frame skeleton.

[0103] The frame skeleton is composed of an upper frame skeleton 511 located on the upper side of the grid-shaped substrate and extending laterally, a lower frame skeleton 512 located on the lower side of the grid-shaped substrate and extending laterally, a left frame skeleton 513 located on the left side of the grid-shaped substrate and extending longitudinally, and a right frame skeleton 514 located on the right side of the grid-shaped substrate and extending longitudinally.

[0104] The tab 11 protrudes upward from a position offset from the center of the long side of the upper frame 511 toward the right frame 514. The multiple middle frames consist of multiple first longitudinal middle frames 516a extending from each position of the upper frame 511 toward the lower frame 512 at an angle directly below the tab 11 of the lower frame 512, a second longitudinal middle frame 518 positioned closest to the left frame 513 and reaching the lower frame, and multiple transverse middle frames 517 connecting the left frame 513 and the right frame 514.

[0105] In the grid-shaped substrate 51, a plurality of first longitudinal central frames 516a are arranged along a diagonal line extending upwards from a point on a reference line that extends slightly to the right of the center of the electrode tab in the width direction and perpendicular to the lower frame frame 512, and terminates at either the lower frame frame 512 or the horizontal central frame 517. Furthermore, as the connection points of the longitudinal central frames located to the right and left of the aforementioned reference line and their connections to the upper frame of the longitudinal central frame move away from the electrode tab, the starting point of the aforementioned diagonal line points upwards. As a result, compared to a simple grid-shaped positive electrode grid, the current path from the diagonal region to the electrode tab is shortened.

[0106] The angle θ between the line K518, which indicates the direction of extension of the second vertical frame 518, and the line K513, which indicates the direction of extension of the left frame frame (first vertical frame frame) 513, is... L The angle is between -10° and 10°. The minimum separation distance d between the left frame skeleton (first vertical frame skeleton) 513 and the second vertical frame 518. LThe distance is 7.0 mm. Additionally, the average separation distance between adjacent transverse mid-frames 517 is 5.5 mm. Furthermore, the average opening area of ​​the multiple left-end openings 519 when viewed from above is 30 mm². 2 Above and 104mm 2 the following.

[0107] Furthermore, two of the multiple transverse central frames 517 are coarse transverse central frames 517a and 517b with a cross-sectional area B that is larger than the average cross-sectional area A of the multiple transverse central frames 517, and the ratio of their cross-sectional areas B / A is 1.15 or more.

[0108] When the distance between the longitudinal center positions of the upper frame skeleton and the lower frame skeleton is set to L0, and the distance between the longitudinal center position of the upper frame skeleton and the longitudinal center position of the thick horizontal frame 517a is set to L1, the ratio L1 / L0 is 0.66. When the distance between the longitudinal center position of the upper frame skeleton and the longitudinal center position of the thick horizontal frame 517b is set to L2 (<L1), the ratio L2 / L0 is 0.47.

[0109] In other words, in the liquid lead-acid battery of this embodiment, the grid-shaped substrate 51 of the positive current collector 5 constituting the positive electrode plate 10A has two coarse horizontal central skeletons 517a and 517b. The coarse horizontal central skeleton 517a exists in the lower half region, and the coarse horizontal central skeleton 517b exists near the longitudinal central part of the grid-shaped substrate 51.

[0110] [Regarding the positive current collector in the third embodiment]

[0111] like Figure 4 As shown, the positive current collector 5B constituting the positive electrode plate 10 of the third embodiment is the same as the positive current collector 5A constituting the positive electrode plate 10 of the second embodiment, except that all the horizontal frame 517 have the same thickness.

[0112] [The functions and effects of the liquid lead-acid batteries in the first to third embodiments]

[0113] The liquid lead-acid batteries described in the first and second embodiments have a thicker transverse core frame 517a and 517b on the grid-shaped substrate 51 constituting the positive current collector 5 and 5A of the positive electrode plate 10, with a B / A ratio of 1.15 or higher. Compared to the case where all transverse core frames have the same thickness as the transverse core frame 517, the mechanical strength of the positive electrode plate is improved, making it less prone to transverse elongation and suppressing barrel-shaped and mountain-shaped deformation of the grid-shaped substrate 51 of the positive current collector 5 and 5A, which is made of rolled plate. Therefore, the growth associated with corrosion of the grid-shaped substrate 51 is suppressed, and short circuits caused by contact between the positive and negative electrode plates are prevented, thereby extending the battery's lifespan.

[0114] The liquid lead-acid battery involved in the second and third embodiments serves as the longitudinal central frame of the grid-shaped substrate 51 constituting the positive current collectors 5A and 5B of the positive electrode plate 10, and has a first longitudinal central frame 516a and a second longitudinal central frame 518, with an angle θ between them. L The temperature is between -10° and 10°. Therefore, compared to the case with only the first longitudinal frame 516a, during long-term use in a partially charged state, the peeling and shedding of the positive electrode compound disposed at the left-end opening 519 is significantly suppressed. Furthermore, the distance d... L With a diameter of 5.0 mm or more and 10.0 mm or less, the left-end opening 519 becomes an opening area suitable for filling the paste when it is the positive electrode paste for ISS automotive liquid lead-acid batteries, thus reducing manufacturing costs.

[0115] Furthermore, in the first to third embodiments of the liquid lead-acid battery, the longitudinal central frame 516 and the first longitudinal central frame 516a of the grid-shaped substrate 51 constituting the positive electrode current collectors 5, 5A, and 5B of the positive electrode plate 10 are arranged such that they extend from each position of the upper frame frame towards the lower frame frame side, directly below the electrode tabs of the lower frame frame. Therefore, compared to liquid lead-acid batteries with a simple grid-shaped positive electrode current collector, during constant voltage charging, the charge-discharge reaction associated with the electrolysis of the electrolyte in the lower part of the positive electrode plate 10 is easily aggravated. Consequently, the amount of gas generated from the lower part of the positive electrode plate 10 increases, and by stirring the electrolyte, electrolyte stratification is less likely to occur, and softening and shedding of the lower part of the positive electrode plate and sulfation of the lower part of the negative electrode plate are also suppressed. Furthermore, the liquid lead-acid batteries of the first to third embodiments, through the configuration of the aforementioned longitudinal central frame 516 and the first longitudinal central frame 516a, improve the utilization rate of the positive electrode active material in the positive electrode mixture held at the bottom of the positive electrode plate, and therefore have excellent discharge capacity.

[0116] Therefore, the liquid lead-acid batteries of the first to third embodiments are suitable for use in vehicles that perform charging control, such as charging control vehicles and idle-off vehicles, and are mainly used in a partially charged state. Furthermore, a partially charged state is, for example, a state where the charge is more than 70% but less than 100%.

[0117] Furthermore, the liquid lead-acid batteries of the first to third embodiments can be used not only as power sources for starting the internal combustion engines of vehicles, but also as backup power sources for power and auxiliary equipment in electric vehicles, electric forklifts, electric buses, electric motorcycles, electric skid boats, small electric-assisted bicycles, golf carts, electric locomotives, etc. Moreover, the liquid lead-acid batteries involved in this embodiment can also be used as lighting power sources or backup power sources. Alternatively, they can also be used as energy storage devices for electrical energy generated by solar power generation, wind power generation, etc.

[0118] Example

[0119] The following examples and comparative examples illustrate the invention in more detail.

[0120] [First Comparative Experiment]

[0121] Liquid lead-acid batteries with a size of Q-85 (samples No. 1 to No. 39) were manufactured using the following method. As shown in Tables 1 to 3, the transverse frame structure of the positive electrode current collector differs for each sample, but all other aspects are the same.

[0122] First, current collectors (grid-shaped substrate + tabs) for positive and negative electrodes were fabricated from rolled sheets made of Pb-Ca-Sn alloy using a punching method. The microstructure of the rolled material with an average interlayer distance of 20 μm was observed by cutting a cross-section of the current collector in the thickness direction.

[0123] Sample No. 1 is an existing example of a liquid lead-acid battery, and the positive electrode current collector is... Figure 2 In the positive current collector 5, there are no thick horizontal frame skeletons 517a and 517b, and all horizontal frame skeletons 517 have the same thickness. The width (lateral dimension) of the grid-like substrate 51 of the positive current collector 5 is 137 mm, and the height (vertical dimension) is 116.5 mm. Their dimensions are not the center lines of the frame skeleton, but the spacing between the outermost edges. In the positive current collector of Sample No.1, the cross-sectional area of ​​all horizontal frame skeletons 517 is 1.00 mm². 2 .

[0124] For the positive electrode current collector 5 of the liquid lead-acid batteries in samples No.2 to No.31, one of the multiple horizontal central frames 517 constituting the grid-shaped substrate 51 is called the coarse horizontal central frame. The ratio L1 / L0 of the distance between the coarse horizontal central frame and the upper frame frame 511 (the distance between their longitudinal center positions) L1 and the distance between the upper frame frame 511 and the lower frame frame 512 (the distance between their longitudinal center positions) L0 is any one of 0.40, 0.50, 0.60, 0.70, 0.80, and 0.90.

[0125] Furthermore, in the positive current collectors of all samples, except for the thick horizontal central frame, the cross-sectional area of ​​the horizontal central frame is all the same, which is 1.00 mm². 2 Furthermore, by making the cross-sectional area B of the coarse horizontal frame 1.11 mm² 2 1.17mm 2 1.22mm 2 1.29mm 2 1.34mm 2This makes the average cross-sectional area A of all transverse central skeletons, including the thick transverse central skeleton, become 1.01 mm. 2 1.02mm 2 1.02mm 2 1.03mm 2 1.03mm 2 This makes the ratios B / A 1.10, 1.15, 1.20, 1.25, and 1.30, respectively.

[0126] In the positive current collector 5 of the liquid lead-acid batteries No. 32 to No. 35, two of the multiple transverse center frames 517 are called thick transverse center frames. One of the two thick transverse center frames is positioned such that the ratio L1 / L0 of the distance between it and the upper frame frame 511 (the distance between their longitudinal center positions) L1 and the distance between the upper frame frame 511 and the lower frame frame 512 (the distance between their longitudinal center positions) L0 is 0.80. The other is positioned such that the ratio L2 / L0 of the distance between it and the upper frame frame 511 (the distance between their longitudinal center positions) L2 (< L1) and the distance L0 is any one of 0.40, 0.50, 0.60, and 0.70.

[0127] In the positive current collectors No.32 to No.35, all the cross-sectional areas of the horizontal central frames, except for the thick central frame, are the same, which is 1.00 mm². 2 The cross-sectional area B of both thick horizontal central frames is 1.26 mm². 2 Furthermore, the average cross-sectional area A of all transverse central skeletons, including the thick transverse central skeleton, is 1.05 mm. 2 Therefore, the ratio of B / A becomes 1.20.

[0128] In the positive electrode current collector 5 of the liquid lead-acid batteries No. 36 to No. 39, three of the multiple transverse core frames 517 are coarse transverse core frames. Two of the three coarse transverse core frames are located in the lower half of the region from the longitudinal center of the grid-like substrate 51, and the remaining one is located at various positions in the upper half of the region. The two coarse transverse core frames located in the lower half of the region are positioned at positions where the ratio of L1 / L0 is 0.80 and the ratio of L2 / L0 is 0.60. The coarse transverse core frame located in the upper half of the region is positioned at any one of the ratios of L3 / L0, which is 0.10, 0.20, 0.30, or 0.40.

[0129] In the positive current collectors No. 36 to No. 39, the cross-sectional area B of the three thick horizontal core frames is all 1.30 mm². 2 All horizontal central skeletons, except for the thick horizontal central skeleton, have the same cross-sectional area of ​​1.00 mm². 2Furthermore, the average cross-sectional area A of all transverse central skeletons, including the thick transverse central skeleton, is 1.08 mm. 2 Therefore, the ratio of B / A becomes 1.20.

[0130] In addition, in the positive current collector, if the cross-sectional areas of multiple thick horizontal cores are different from each other, let their average cross-sectional area be B, and calculate the ratio B / A.

[0131] As the negative current collector, in order to... Figure 2 The positive current collector 5 shown has the same shape, but uses the same structure with the same thickness for all horizontal cores.

[0132] Next, lead powder, primarily composed of lead monoxide, is mixed with water and dilute sulfuric acid. Additives are then further mixed and fused as needed to produce a paste for the positive electrode. The ratio of the mass of α-lead dioxide (α) to the mass of β-lead dioxide (β) in the positive electrode active material, α / (α+β), is 20%. Separately, lead powder, primarily composed of lead monoxide, is mixed with water and dilute sulfuric acid. Additives are then further mixed and fused as needed to produce a paste for the negative electrode.

[0133] Furthermore, after filling the grid-shaped substrate of the positive electrode current collector with the positive electrode mixture as a paste, it is cured and dried to produce the positive electrode plate before formation. Similarly, after filling the grid-shaped substrate of the negative electrode current collector with the negative electrode mixture as a paste, it is cured and dried to produce the negative electrode plate before formation.

[0134] The positive electrode plate has a positive electrode active material density of 4.2 g / cm³. 3 The density of the negative electrode active material in the negative electrode plate is 4.0 g / cm³. 3 .

[0135] In addition, as a separator, a ribbed separator is prepared, which is made of porous synthetic resin and has a flat base and pleated ribs protruding in a direction orthogonal to the surface direction of the base. The total thickness of the ribbed separator is 0.90 mm, the rib height is 0.65 mm, and the thickness of the base is 0.25 mm.

[0136] Multiple positive and negative electrode plates, sandwiched between ribbed separators, are stacked alternately to create an electrode assembly. There are 7 positive electrode plates and 8 negative electrode plates.

[0137] The electrode assembly is housed within a battery cell. The tabs of the positive current collectors on each positive electrode are connected via positive electrode connecting tabs, and the tabs of the negative current collectors on each negative electrode are connected via negative electrode connecting tabs. Furthermore, the positive electrode connecting tab is connected to one end of the positive terminal, and the negative electrode connecting tab is connected to one end of the negative terminal. Additionally, the battery cell has multiple unit cell chambers for housing the electrode assembly, but the volume of each unit cell below the high liquid level (maximum liquid level line) is 570 cm³. 3 In addition, the plate assembly has a predetermined pressure.

[0138] Furthermore, a cover is used to seal the opening of the battery cell. The positive and negative terminals are respectively inserted into the terminal sleeve formed in the cover, so that the other end of the positive terminal and the other end of the negative terminal are welded together while exposed on the outside of the lead-acid battery, forming the positive and negative terminals. An electrolyte solution consisting of dilute sulfuric acid with a specific gravity of 1.23 and containing aluminum sulfate at a concentration of 0.1 mol / L is injected into the high liquid level of the battery cell through the injection port formed in the cover. The injection port is then sealed with a plug, and the battery cell is formed to obtain the lead-acid battery.

[0139] The soaking time (from electrolyte injection to the start of energization for formation) is 30 minutes, the charge used for formation is 230%, and the electrolyte temperature during formation is 45°C. At this time, the volume of each cell chamber is 375 cm³, based on the amount of electrolyte injected. 3 In addition, the specific gravity of the electrolyte after formation is 1.28.

[0140] In addition, for the purpose of subsequent dismantling investigation, multiple batches of lead-acid batteries were produced. As long as the lead-acid batteries were from the same batch, they were considered to have the same structure and battery characteristics.

[0141] For each liquid lead-acid battery obtained in this way (samples No.1 to No.39), a composite life test was conducted at 75°C to investigate the number of cycles to the end of the life.

[0142] The life test conditions are as follows. First, at 75°C, multiple cycles are performed sequentially, including 2 seconds of 300A discharge, 60 minutes of CCCV charging (14.5V, maximum charging current 50A), 5 minutes of 25A discharge, and 30 minutes of CCCV charging (14.5V, maximum charging current 50A). The life test is considered complete when the voltage drops to 7.2V during each discharge. The number of cycles performed up to this point is taken as the life test duration.

[0143] The results of the life test were evaluated according to the following criteria: "×" for less than 360 cycles, "△" for 360 or more but less than 380 cycles, "○" for 380 or more but less than 400 cycles, and "◎" for 400 or more cycles.

[0144] After the life test, the battery was disassembled and investigated to confirm the condition (degree of damage) of the separator associated with the growth of the positive electrode. Table 1 shows one of the following four states as "Separator State" in relation to the condition of the separator damage.

[0145] ×: When visually inspecting the base surface of the partition, damage or penetration of the base surface is observed.

[0146] △: When visually inspecting the base surface of the partition, traces of stress application, such as deformation and discoloration, can be observed on both sides of the base surface.

[0147] ○: When visually inspecting the base surface of the partition, traces of stress such as deformation and discoloration are only observed on one side of the base surface.

[0148] ◎: When visually inspecting the base surface of the partition, no traces of stress application, such as deformation or discoloration, were observed.

[0149] In addition, liquid lead-acid batteries are being made lighter, with a target weight reduction of a few grams. Therefore, the suppression of battery weight increase was evaluated based on the following criteria.

[0150] The mass of the positive current collector in the existing example is 48.0g. If the increase in its mass is less than 0.5g, it is marked with "◎"; if it is more than 0.5g but less than 1.0g, it is marked with "○"; if it is more than 1.0g but less than 1.5g, it is marked with "△"; and if it is more than 1.5g, it is marked with "×".

[0151] Furthermore, a comprehensive judgment was made as follows. In the evaluation of "life test judgment", "partition condition" and "weight increase suppression", "◎" was set to 3 points, "○" to 2 points, "△" to 1 point, and "×" to 0 points. The total number of points was calculated. If the total number of points was 7 or more, it was "◎"; if it was 5 or 6, it was "○"; if it was 4 or 3, it was "△"; and if it was 2 or less, it was "×".

[0152] These results are shown in Tables 1, 2, and 3. Table 2, as a comparative example, also records the structure and results of No. 24, and Table 3, as a comparative example, also records the structure and results of No. 34.

[0153] [Table 1]

[0154]

[0155] [Table 2]

[0156]

[0157] [Table 3]

[0158]

[0159] Based on the experimental results in Table 1, it can be seen that regardless of the difference in the distance ratio L1 / L0, when the cross-sectional area ratio (B / A) of the transverse central skeleton is 1.10, only the performance equivalent to that of the existing example with a ratio of 1.00 can be obtained. Furthermore, in the comparison of structures with the same distance ratio L1 / L0, it can be seen that when the cross-sectional area ratio (B / A) of the transverse central skeleton is 1.15 or higher, and the larger this ratio (the larger the cross-sectional area of ​​the thicker transverse central skeleton), the greater the effect of suppressing transverse growth, the less damage to the diaphragm, and the tendency to improve the lifespan.

[0160] Specifically, when the separator is in an "×" state, a short circuit occurs between the positive and negative plates, indicating a shortened lifespan. When the separator is in a "△" state, it is not visually apparent, but the deformation associated with the expansion of the positive plate is increased, suggesting that the softening and peeling of the positive active material is aggravated. When the separator is in an "○" state, the deformation associated with the expansion of the positive plate is suppressed, indicating good lifespan characteristics. When the separator is in a "◎" state, the suppression effect on the deformation associated with the expansion of the positive plate is high, indicating excellent lifespan characteristics.

[0161] Furthermore, the larger the cross-sectional area of ​​the cross frame, the greater the weight (mass) of the grid-shaped substrate of the positive electrode current collector. Therefore, from the viewpoint of making the liquid lead-acid battery lighter, it is preferable to make the cross-sectional area ratio (B / A) of the cross frame 1.25 or less.

[0162] Furthermore, in the comparison of structures with the same cross-sectional area ratio (B / A) of the transverse frame, it can be seen that when L1 / L0 is above 0.50 and below 0.80, compared with L1 / L0 being 0.40 and 0.90, damage to the partition is reduced and the service life is improved.

[0163] According to the test results in Table 2, it can be seen that by increasing the number of coarse cross-bracing frames from one to two, damage to the partition is reduced and the service life is improved.

[0164] According to the test results in Table 3, it can be seen that by increasing the number of coarse cross-bracing members from two to three, the lifespan is further improved.

[0165] [Second Comparative Experiment]

[0166] Liquid lead-acid batteries No. 40 to No. 53 were manufactured using the same method as described in the first comparative test, except that the positive current collectors of samples No. 40 to No. 53 were used.

[0167] The liquid lead-acid batteries in samples No. 40 to No. 53 have positive electrode current collectors in... Figure 3In the positive current collector 5A, one of the multiple horizontal central skeletons 517 constituting the grid-shaped substrate 51 is called the coarse horizontal central skeleton. The ratio L1 / L0 of the distance between the coarse horizontal central skeleton and the upper frame skeleton 511 (the distance between their longitudinal center positions) and the distance between the upper frame skeleton 511 and the lower frame skeleton 512 (the distance between their longitudinal center positions) is 0.70.

[0168] Furthermore, in the positive current collectors of samples No. 40 to No. 53, the cross-sectional area of ​​all the horizontal central frames except for the thick horizontal central frame is the same, which is 1.00 mm². 2 Furthermore, by setting the cross-sectional area B of the coarse horizontal frame to 1.29 mm². 2 This makes the average cross-sectional area A of all transverse central skeletons, including the thick transverse central skeleton, 1.03 mm. 2 This results in a B / A ratio of 1.25.

[0169] The liquid lead-acid batteries of samples No.40 to No.53 are shown in Table 4. The structure of the left longitudinal frame 518 is different, but other aspects are the same.

[0170] The distance d between the positive current collectors of samples No.40 to No.48 L They are the same and both are 7.0mm, but the angle θ is different. L The values ​​are -15°, -10°, -5°, -2°, 0°, 3°, 5°, 10°, and 15°, respectively.

[0171] The angle θ of the positive current collector in samples No.49 to No.53 L They are the same and at 0°, but the distance d L The thicknesses are 3.0mm, 5.0mm, 8.0mm, 10.0mm, and 12.0mm respectively.

[0172] For the liquid lead-acid batteries No. 40 to No. 53 produced, tests were conducted using the same method as described in the first comparative test. The number of cycles to the end of their lifespan was investigated, and the condition of the separator was also determined using the same method. The results are shown in Table 4.

[0173] [Table 4]

[0174]

[0175] The following can be observed based on the results in Table 4.

[0176] For the liquid lead-acid batteries in samples No. 40 to No. 48, the distance d of the positive electrode current collector is... L It is 7.0mm and only the angle θ L Different, but makes the angle θ LBy achieving a range of -10° to 10°, it can achieve excellent lifespan performance of over 400 cycles, and the separator remains in good condition. Furthermore, by adjusting the angle θ... L Achieving a lifespan of over 410 cycles with an angle between -5° and 5° is possible. Furthermore, by adjusting the angle θ... L It achieves superior lifespan performance of over 420 cycles, reaching temperatures between -2°C and 3°C.

[0177] For the liquid lead-acid batteries in samples No. 49 to No. 53, the angle θ of the positive electrode current collector is... L It is 0° and only at a distance of d L Different, but make the distance d L By reducing the thickness to below 10.0 mm, it achieves excellent lifespan performance exceeding 419 cycles, and the separator is in good condition. However, the distance to d... L The 3.0mm positive current collector of No. 49 requires increased pressure when filling the positive electrode paste at the left end opening. Therefore, considering manufacturing costs, a distance d is preferred. L It is between 5.0mm and 10.0mm.

[0178] [Third Comparative Test]

[0179] Liquid lead-acid batteries No. 54 to No. 67 were manufactured using the same method as described in the first comparative test, except that the positive current collectors of samples No. 54 to No. 67 were used.

[0180] Samples No. 54 to No. 67 contain liquid lead-acid batteries. Figure 4 The positive current collector 5B is shown. Otherwise, it is the same as the liquid lead-acid battery in the first comparative test.

[0181] The cross-sectional area of ​​all the transverse frames 517 constituting the positive current collector 5B is the same, which is 1.00 mm² in this case. 2 .

[0182] As shown in Table 5, the liquid lead-acid batteries of samples No. 54 to No. 67 differ in the structure of the left longitudinal frame 518, but are otherwise identical. Furthermore, samples No. 54 to No. 67 are identical to samples No. 40 to No. 53, except for the ratio B / A = 1.00.

[0183] The distance d between the positive current collectors of samples No.54 to No.62 L They are the same and both are 7.0mm, but the angle θ is different. L The values ​​are -15°, -10°, -5°, -2°, 0°, 3°, 5°, 10°, and 15°, respectively.

[0184] The angle θ of the positive current collector in samples No. 63 to No. 67 L They are the same and at 0°, but the distance d L The thicknesses are 3.0mm, 5.0mm, 8.0mm, 10.0mm, and 12.0mm respectively.

[0185] For the manufactured liquid lead-acid batteries No. 54 to No. 67, tests were conducted using the same method as described in the first comparative test. The number of cycles to the end of their lifespan was investigated, and the condition of the separators was also determined using the same method. The results are shown in Table 5.

[0186] [Table 5]

[0187]

[0188] The following can be observed based on the results in Table 5.

[0189] For the liquid lead-acid batteries in samples No. 54 to No. 62, the distance d of the positive electrode current collector is... L It is 7.0mm and only the angle θ L Different, but makes the angle θ L By achieving a range of -10° to 10°, it can achieve excellent lifespan performance of over 400 cycles, and the separator remains in good condition. Furthermore, by adjusting the angle θ... L Achieving a lifespan of over 405 cycles with an angle between -5° and 5° is possible. Furthermore, by adjusting the angle θ... L It achieves an even better lifespan performance of over 408 cycles, with a temperature range of -2°C to 3°C.

[0190] For the liquid lead-acid batteries in samples No. 63 to No. 67, the angle θ of the positive electrode current collector is... L It is 0° and only at a distance of d L Different, but make the distance d L By reducing the thickness to below 10.0 mm, it achieves excellent lifespan performance exceeding 406 cycles, and the separator is in good condition. However, the distance to d... L The 3.0mm No. 63 positive current collector requires increased pressure when filling the positive electrode paste at the left end opening. Therefore, considering manufacturing costs, a distance d is preferred. L It is between 5.0mm and 10.0mm.

[0191] Furthermore, compared to samples No. 40 to No. 53, which are identical except for the ratio B / A = 1.00, the liquid lead-acid batteries No. 54 to No. 67 have slightly worse lifespan performance, but are more advantageous in suppressing weight gain.

[0192] Explanation of reference numerals in the attached figures

[0193] 1...plate assembly; 10...positive plate; 20...negative plate; 30...separator; 41...cell; 5...positive current collector; 51...grid-shaped substrate; 11...tab continuous with grid-shaped substrate; 511...upper frame frame; 512...lower frame frame; 513...left frame frame; 514...right frame frame; 516...central longitudinal frame; 516a...first central longitudinal frame; 517...central transverse frame; 517a...thick central transverse frame; 517b...thick central transverse frame; 518...left end central longitudinal frame (second central longitudinal frame); 519...left end opening.

Claims

1. A liquid lead-acid battery, comprising a unit battery compartment containing electrolyte and electrode plates. The electrode assembly has a laminate, which is composed of a plurality of alternating positive electrode plates and a negative electrode plate and a separator disposed between the positive electrode plates and the negative electrode plates. The positive electrode plate has a positive current collector and a positive electrode mixture containing a positive active material, the positive active material containing lead dioxide. The positive current collector has a rectangular grid-like substrate and tabs continuous with the grid-like substrate, and the positive electrode mixture is held in the grid-like substrate. The positive current collector is formed of a lead alloy with a rolled structure. The grid-shaped substrate has: a frame skeleton forming the four sides of the rectangle; and a plurality of intermediate skeletons connected to the frame skeleton and existing on the inner side of the frame skeleton. The frame skeleton includes: an upper frame skeleton located on the upper side of the grid-shaped substrate and extending laterally; a lower frame skeleton located on the lower side of the grid-shaped substrate and extending laterally; and a pair of longitudinal frame skeletons extending longitudinally. The tab protrudes upward from a position offset from the center of the long side of the upper frame towards one side of either of the pair of longitudinal frames. The plurality of central frames include: a plurality of vertical central frames extending from various positions of the upper frame towards one side of the lower frame; and a plurality of horizontal central frames connecting the pair of vertical frame frames. At least one of the plurality of transverse central frames is a coarse transverse central frame with a cross-sectional area B that is larger than the average cross-sectional area A of the plurality of transverse central frames, and the ratio of the cross-sectional areas B / A is 1.15 or greater. The liquid lead-acid battery includes: a plurality of first longitudinal frames serving as the longitudinal central frame, extending obliquely from each position of the upper frame towards the lower frame, and exiting from a position directly below the tabs of the lower frame; and a second longitudinal frame serving as the longitudinal central frame, positioned closest to the first longitudinal frames serving as the longitudinal frame and reaching the lower frame, the longitudinal frames being located away from the tabs. The angle θ between the straight line representing the direction of extension of the second longitudinal frame and the straight line representing the direction of extension of the first longitudinal frame is... L The temperature is above -5°C and below 5°C.

2. The liquid lead-acid battery according to claim 1, wherein, The thick horizontal skeleton exists in the region extending from the longitudinal center of the grid-shaped substrate to the lower half.

3. The liquid lead-acid battery according to claim 1, wherein, When the distance between the longitudinal center position of the upper frame skeleton and the longitudinal center position of the lower frame skeleton is set as L0, and the distance between the longitudinal center position of the upper frame skeleton and the longitudinal center position of the thick horizontal middle skeleton is set as L1, the ratio of L1 / L0 is greater than 0.50 and less than 0.

80.

4. The liquid lead-acid battery according to any one of claims 1 to 3, wherein, There are two of the aforementioned coarse transverse skeletons.

5. The liquid lead-acid battery according to any one of claims 1 to 3, wherein, There are three of the aforementioned coarse horizontal skeletons.

6. The liquid lead-acid battery according to any one of claims 1 to 3, wherein, The minimum separation distance d between the first longitudinal frame and the second longitudinal frame L It is between 5.0mm and 10.0mm.

7. A liquid lead-acid battery, comprising a unit battery compartment containing electrolyte and electrode plates. The electrode assembly has a laminate, which is composed of a plurality of alternating positive electrode plates and a negative electrode plate and a separator disposed between the positive electrode plates and the negative electrode plates. The positive electrode plate has a positive current collector and a positive electrode mixture containing a positive active material, the positive active material containing lead dioxide. The positive current collector has a rectangular grid-like substrate and tabs continuous with the grid-like substrate, and the positive electrode mixture is held in the grid-like substrate. The positive current collector is formed of a lead alloy with a rolled structure. The grid-shaped substrate has: a frame skeleton forming the four sides of the rectangle; and a plurality of intermediate skeletons connected to the frame skeleton and existing on the inner side of the frame skeleton. The frame skeleton includes: an upper frame skeleton located on the upper side of the grid-shaped substrate and extending laterally; a lower frame skeleton located on the lower side of the grid-shaped substrate and extending laterally; and a pair of longitudinal frame skeletons extending longitudinally. The tab protrudes upward from a position offset from the center of the long side of the upper frame towards one side of either of the pair of longitudinal frames. The plurality of central frames include: a plurality of vertical central frames extending from various positions of the upper frame towards one side of the lower frame; and a plurality of horizontal central frames connecting the pair of vertical frame frames. The liquid lead-acid battery includes: a plurality of first longitudinal frames serving as the longitudinal central frame, extending obliquely from each position of the upper frame towards the lower frame, and exiting from a position directly below the tabs of the lower frame; and a second longitudinal frame serving as the longitudinal central frame, positioned closest to the first longitudinal frames serving as the longitudinal frame and reaching the lower frame, the longitudinal frames being located away from the tabs. The angle θ between the straight line representing the direction of extension of the second longitudinal frame and the straight line representing the direction of extension of the first longitudinal frame is... L The temperature is above -5°C and below 5°C.

8. The liquid lead-acid battery according to claim 7, wherein, The minimum separation distance d between the first longitudinal frame and the second longitudinal frame L It is between 5.0mm and 10.0mm.

Images