JP6891594B2 - Lead-acid battery - Google Patents

Description

The present invention relates to a lead storage battery.

Lead-acid batteries are used for various purposes such as in-vehicle use and industrial use. The lead-acid battery includes a electrode plate group including a negative electrode plate, a positive electrode plate, and a separator interposed therein, and an electrolytic solution. The electrode plate group is housed in the electric tank together with the electrolytic solution.

When charging and discharging are repeated in a liquid lead-acid battery, the concentration of the electrolytic solution becomes thin in the upper part of the battery case and becomes thicker in the lower part.

In Patent Document 1, from the viewpoint of generating convection of the electrolytic solution and suppressing stratification, a communication flow path for communicating the recess (upper part) and the lower part of the storage space for accommodating the electrode plate group is provided in the battery case. Has been proposed. Patent Document 2 proposes that the electrolytic solution is allowed to flow and be agitated by providing a communication path for communicating the partition wall that divides the inside of the electric tank and the divided space with each other.

Japanese Unexamined Patent Publication No. 2015-176659 JP-A-2007-242333

As stratification progresses, the charge / discharge reaction varies and the battery life is shortened. Further, in order to convect the electrolytic solution to suppress stratification, the structure of the battery case tends to be complicated as in Patent Document 1 and Patent Document 2.

One aspect of the present invention is a group of electrode plates including a positive electrode and a negative electrode, and
With electrolyte
An electric tank having an opening and accommodating the electrode plate group and the electrolytic solution,
A lid for sealing the opening of the battery case is provided.
The battery case includes a bottom and a side wall rising from the bottom.
When the height of the side wall from the bottom is H, the average heat insulating property at the upper part where the height of the side wall from the bottom is higher than 0.5H is the height of the side wall from the bottom. With respect to lead-acid batteries, which is higher than the average thermal insulation at the bottom up to 0.5H.

The electrolytic solution can be convected in the battery case of the lead storage battery by a simple method.

It is sectional drawing of the electric tank of the lead storage battery which concerns on one Embodiment of this invention. It is sectional drawing which shows the state of the side wall of the electric tank of the lead storage battery which concerns on other embodiment of this invention. It is sectional drawing which shows the state of the side wall of the electric tank of the lead storage battery which concerns on still another Embodiment of this invention. It is sectional drawing which shows the state of the side wall of the electric tank of the lead storage battery which concerns on another embodiment of this invention. It is a perspective view which shows typically the state which removed the lid of the lead storage battery which concerns on one aspect of this invention. It is a front view of the lead storage battery of FIG. FIG. 6 is a cross-sectional view taken along the line VIB-VIB of the lead storage battery of FIG. 6A.

The lead-acid battery according to one aspect of the present invention has a electrode plate group including a positive electrode and a negative electrode, an electrolytic solution, and an opening, and has an electric tank for accommodating the electrode plate group and the electrolytic solution, and an opening of the electric tank. It is provided with a lid for sealing. The battery case includes a bottom and a side wall rising from the bottom. When the height from the bottom of the side wall is H, the average heat insulating property of the upper part where the height from the bottom of the side wall is above 0.5H is up to 0.5H from the bottom of the side wall. Higher than the average insulation at the bottom.

By making the heat insulating property at the upper part of the side wall of the electric tank higher than the heat insulating property at the lower part of the side wall, when heat is applied to the electric tank, the temperature of the electrolytic solution lower than the temperature of the electrolytic solution at the upper part of the electric tank is increased. The temperature can be raised. The lower electrolyte, whose temperature has risen, rises in the battery case, and the upper electrolyte, which remains cold, falls. Thereby, the electrolytic solution can be convected in the electric tank by a simple method of changing the heat insulating property in the electric tank between the upper part and the lower part. Since stratification is suppressed by the convection of the electrolytic solution, the battery life can be improved.

The average heat insulating property of the upper part of the battery case means the average of the index values of the heat insulating property obtained at a plurality of places (for example, 3 to 10 places) along the vertical direction in the upper part of the side wall of the battery case. .. The average heat insulating property of the lower part of the electric tank is the same as that of the upper part except that the index value of the heat insulating property is obtained for the lower part of the side wall of the electric tank. The index value of heat insulating property is not particularly limited as long as it is an index of heat insulating property (or thermal conductivity). For example, the temperature or temperature change on the other main surface when the side wall (or the plate cut out from the side wall) is heated from one main surface side may be used as an index value of heat insulating property. When the side wall is covered with a cover as described later, the temperature or temperature change on the inner surface of the battery case when heated from the outside of the cover can be used as an index value of heat insulating property.

Examples of the mode in which the heat insulating property is different between the upper part and the lower part of the electric tank includes a mode in which the heat insulating property of the side wall of the electric tank itself is different between the upper part and the lower part. The average thickness of the upper part of the side wall may be larger than the average thickness of the lower part of the side wall. Further, the side wall contains a first material having a first thermal conductivity and a second material having a second thermal conductivity higher than the first thermal conductivity, and the first material is placed on the upper part of the side wall. The second material may be distributed more than the two materials, and the second material may be distributed more than the first material in the lower part of the side wall. In a side wall having a hollow portion, more hollow portions may be distributed in the upper part of the side wall than in the lower part of the side wall. In either case, the temperature difference between the upper part and the lower part of the electric tank is likely to occur, and the electrolytic solution can be convected in the electric tank.

The mode in which the heat insulating property is different between the upper part and the lower part of the electric tank includes a mode in which the upper part of the side wall of the electric tank is covered with a cover or the like from the outside of the electric tank. In this case, the temperature of the electrolytic solution in the lower part can be selectively increased as compared with the upper part of the electric tank, and convection is likely to occur.

When the lead-acid battery is installed in a vehicle such as an automobile, it may be installed in the engine room. Lead-acid batteries placed in the engine room are exposed to high temperatures due to the heat generated by the engine. By selectively heating the electrolytic solution at the lower part of the electric tank with such heat, the convection of the electrolytic solution as described above can be performed more easily. Therefore, the lead-acid battery according to the present invention is particularly suitable for being placed in the engine room of a vehicle. However, not limited to such a case, heat may be applied to the battery case of the lead storage battery by using a heater or the like.

The side wall may have a laminate of a plurality of films intersecting the height direction. An electric tank having such a side wall can be formed by a 3D printer, multiple inkjet, or the like. In a 3D printer, multiple inkjet, or the like, it is easy to manufacture an electric tank having different average heat insulating properties between the upper part and the lower part of the side wall.

Hereinafter, the lead-acid battery according to the embodiment of the present invention will be described for each of the main constituent requirements, but the present invention is not limited to the following embodiments.
(Electric tank)
In the present invention, it is sufficient that the average heat insulating property of the upper part of the side wall of the battery case can be made higher than the average heat insulating property of the lower part, and the specific means thereof is not particularly limited. For example, the average thickness of the upper part of the side wall may be larger than the average thickness of the lower part, the lower part of the side wall may contain a large amount of material having high thermal conductivity, or the hollow part may be distributed in the upper part of the side wall. Alternatively, by covering the upper part of the side wall from the outside with a cover, the average heat insulation of the upper part can be improved as compared with the lower part.

In the side wall of the electric tank, a region having high heat insulation may be formed over the entire upper part of the side wall of the electric tank, and is formed from the upper part of the electric tank to the lower part of the electric tank (for example, the upper end of the lower part of the electric tank). It may have been. The region having high heat insulation may be formed in a part of the region above the side wall of the battery case. At least in the upper part of the side wall of the battery case, it is preferable to form a region having high heat insulating properties on the side wall in a region facing the electrolytic solution.

Examples of the material of the battery case include polypropylene (PP), acrylonitrile butadiene styrene copolymer (ABS), polyvinyl chloride (PVC), acrylonitrile styrene copolymer (AS), ethylene propylene copolymer (EPP), and the like. Can be mentioned.

The battery case may be formed by a known molding method using a mold such as injection molding, or may be formed by a 3D printer, multiple inkjet, or the like. In a 3D printer, multiple inkjet, or the like, a plurality of films formed of the material of the battery case are usually laminated in the height direction to form the battery case. The side wall of such an electric tank has a laminated body of a plurality of films intersecting with each other in the height direction. In 3D printers, multiple inkjets, and the like, it is easy to manufacture an electric tank having different thicknesses in the upper part and the lower part of the side wall, an electric tank having a hollow portion in the side wall, and an electric tank having different materials in the upper part and the lower part.

Specific embodiments will be described in more detail below.
(First embodiment: When the thickness of the side wall is different between the upper part and the lower part)
Increase the average thickness of the sidewalls at the top rather than at the bottom. In the region where the average thickness of the side wall is large, the cross section of the side wall (cross section parallel to the height direction of the battery case) is not particularly limited, and may be tapered or rectangular. FIG. 1 shows a schematic cross-sectional view of an electric tank of a lead storage battery according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a state of a side wall of an electric tank according to another embodiment. In these figures, the electrode plate group and the lid are omitted.

As shown in FIG. 1, when the height of the electric tank 110 is H, the height of the electric tank 110 from the bottom 110B of the side wall of the electric tank 110 is higher than 0.5H at the upper 110U and the bottom 110B. It has a lower part 110D up to a height of 0.5H. In the illustrated example, in the cross section of the upper portion 110U of the side wall of the electric tank 110 in the height direction, the outer wall of the electric tank 110 is parallel to the vertical direction, and the inner wall expands upward and inward to form the upper 110U. The cross section has a tapered shape. The average thickness of the upper part 110U is larger than the average thickness of the lower part 110D, which makes the upper part 110U more average heat insulating than the lower part 110D.

FIG. 2 shows an example in which the average thickness of the upper part of the cross section in the height direction of the side wall of the battery case becomes larger than the average thickness of the lower part. In FIG. 2A, in the cross section of the side wall of the electric tank 210 in the height direction, the inner wall of the upper 210U of the side wall is parallel to the vertical direction, and the outer wall expands outward toward the upper side, so that the upper 210U The cross section of is tapered. In these embodiments, the average thickness of the upper part may be larger than the average thickness of the lower part, and the position of the starting point where the taper shape starts to spread is not particularly limited. From the viewpoint that the heat insulating property is likely to be different between the upper part and the lower part, the starting point of the tapered shape is preferably a height position of 0.5H from the bottom of the battery case or its vicinity.

2 (b) and 2 (c) show an example in which the thickness of the upper portion of the side wall of the battery case is larger than the thickness of the lower portion, and a step is formed between the thick portion and the small portion. In FIG. 2B, the thickness of the side wall of the upper 310U is increased so that the outer wall of the upper 310U projects to the outside of the battery case 310. In FIG. 2C, the thickness of the side wall of the upper 410U is increased so that the inner wall of the upper 410U projects inside the electric tank 410. In these embodiments, the position of the step is not particularly limited, but from the viewpoint that the difference in heat insulating property is likely to occur between the upper part and the lower part, the position may be 0.5H from the bottom of the battery case or its vicinity. preferable. 2 (b) and 2 (c) show a case where the thickness of the side wall is the same on the upper side and the lower side of the step (when the cross-sectional shape is rectangular on the upper side and the lower side of the step). However, not limited to such a case, the upper side and / or the lower side of the step may be tapered.

(Second embodiment: When the upper part of the side wall is covered with a cover)
In the present embodiment, the upper part of the side wall of the battery case is covered with a cover from the outside. As a result, in the upper part of the electric tank, heat from the outside is less likely to be transferred to the electrolytic solution in the electric tank than in the lower part, and the temperature of the electrolytic solution in the lower part is selectively increased to facilitate convection.

FIG. 3 is a schematic cross-sectional view of the battery case of a lead storage battery when a cover is used. The upper side wall above the height of 0.5H from the bottom 10B of the battery case 10 is covered with the cover 13. The thickness of the side wall of the battery case 10 is substantially the same in the upper part and the lower part above the height of 0.5H from the bottom portion 10B.

The cover may be attached to the battery case so as to cover a part of the upper part of the side wall. It is preferable to cover most of the upper part of the side wall (for example, an area of 80% or more of the area of the outer wall above the side wall) with a cover so that heat from the outside is not transferred to the electrolyte solution in the upper part of the battery case as much as possible. It is more preferred to cover the entire top with a cover.

Since the cover does not come into contact with the electrolytic solution, there are more choices of materials that can be used compared to the battery case, and if the cover is used, the shape of the battery case itself can be the same as the conventional one, so it is highly versatile. ..

The material of the cover is not particularly limited, but for example, resin is used. The cover may be made of a resin porous body such as foamed resin. The material of the cover may be the same as that of the electric tank, but if it is formed of a material having a lower thermal conductivity than that of the electric tank, a high heat insulating effect can be easily obtained.

(Third embodiment: When a hollow portion is distributed in the upper part of the side wall)
In this embodiment, the side wall of the battery case has a hollow portion. By distributing more hollow portions in the upper part than in the lower part of the side wall, it is possible to slow down the heat transfer in the upper part as compared with the lower part and promote the convection of the electrolytic solution.

The total volume of the hollow portion in the upper part of the side wall of the battery case may be larger than the total volume of the hollow portion in the lower part of the side wall, but it is preferable that the hollow portion is not formed in the lower part of the side wall as much as possible. When the side wall includes a plurality of hollow portions, the average volume of the hollow portions distributed in the upper part of the side wall may be larger than the average volume of the hollow portions distributed in the lower part. From the viewpoint of increasing the difference in heat insulating properties between the upper portion and the lower portion of the side wall, it is preferable to form a hollow portion having a large volume in the upper portion and not to form a hollow portion in the lower portion. The position and volume of the hollow portion may be adjusted from the viewpoint of efficiently convection of the electrolytic solution.

FIG. 4 shows a schematic cross-sectional view when a hollow portion is formed on the upper portion of the side wall of the battery case. On the side wall of the electric tank 510, a hollow portion 514 is formed in the upper portion 510U above the height 0.5H from the bottom portion 510B. A hollow portion is not formed in the lower portion 510D of the side wall. Since the hollow portion 514 is present in the upper 510U, the heat insulating property of the side wall in the upper 510U is higher than that in the lower 510D, and heat is easily applied to the electrolytic solution in the lower part of the electric tank 510, so that the convection of the electrolytic solution is performed. Can be promoted. The hollow portion is particularly preferably arranged at a portion facing the electrolytic solution at the upper part of the side wall.

(Fourth embodiment: When changing the thermal conductivity of the material)
From the viewpoint of lowering the thermal conductivity of the upper part of the side wall of the electric tank, a material having low thermal conductivity (first material) may be contained in the upper part of the side wall. The lower part of the side wall preferably does not contain, or if it does, contain less of the first material than the upper part.

From the viewpoint of increasing the thermal conductivity of the lower part of the side wall, a material having high thermal conductivity (second material) may be contained in the lower part of the side wall. The upper part of the side wall preferably does not contain, or if it does, contain less of the second material than the lower part.

When the side wall contains a first material and a second material having a thermal conductivity (second thermal conductivity) lower than the thermal conductivity (first thermal conductivity) of the first material, the upper part of the side wall It is preferable that the first material is distributed more than the second material and the second material is distributed more than the first material at the bottom.

The first material and the second material may be used as a base material (base material) for forming an electric tank, one may be used as a base material, and the other may be used as an additive. Examples of the first material include polyphenylene sulfide, high-density PP, polyamide (polyamide 6, polyamide 46, polyamide MDX6, etc.), polyacetal, polyester (polyethylene terephthalate, polybutylene terephthalate, etc.) and other resins, glass powder, alumina and the like. Examples thereof include metal oxide powder, metal powder (powder such as gold and copper), glass fiber, and metal fiber. Examples of the second material include resins such as PP, ABS, PVC, AS, and polyphenylene ether resin (PPE), and materials having holes inside such as glass balloons and glass beads. One type of the first material or the second material may be used alone, or two or more types may be used in combination. Powders and fibers other than resin are usually used in combination with resin.

The respective contents of the first material and the second material in the upper part or the lower part of the side wall are determined according to the type of each material and the like so as to promote the convection of the electrolytic solution.

Some embodiments of the first to fourth embodiments may be combined. For example, the average thickness of the upper side wall may be made larger than that of the lower part, and then a hollow portion may be formed in the upper part of the side wall, or the upper part may be covered with a cover. Further, the upper part may be covered with a cover in a state where a large amount of the second material is distributed on the upper part.

Known components other than the battery case can be used. The components other than the battery case will be described in more detail below.
(Positive plate)
There are two types of positive electrode plates for lead-acid batteries: paste type and clad type.
The paste-type positive electrode plate includes a positive electrode current collector and a positive electrode material. The positive electrode material is held in the positive electrode current collector. The positive electrode electrode material is a positive electrode plate obtained by removing a positive electrode current collector. The positive electrode current collector can be formed by casting lead or a lead alloy or processing a lead or lead alloy sheet. Examples of the processing method include expanding processing and punching processing.

The clad type positive electrode plate includes a plurality of porous tubes, a core metal inserted in each tube, a positive electrode material filled in the tube into which the core metal is inserted, and a collective punishment for connecting the plurality of tubes. Equipped with.

As the lead alloy used for the positive electrode current collector, Pb-Sb-based alloys, Pb-Ca-based alloys, Pb-Ca-Sn-based alloys and the like are preferable in terms of corrosion resistance and mechanical strength. The lead or lead alloy used in the positive electrode current collector may further contain at least one selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu and the like as additive elements. It is preferable to use a Pb-Sb-based alloy for the core metal.
The positive electrode material contains a positive electrode active material (lead dioxide or lead sulfate) whose capacity is developed by a redox reaction. The positive electrode material may contain other additives, if necessary.

The unchemical paste type positive electrode plate is obtained by filling a positive electrode current collector with a positive electrode paste, aging and drying. After that, an unchemical positive electrode plate is formed. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid.
The clad type positive electrode plate is formed by filling a tube into which a core metal is inserted with lead powder or slurry-like lead powder, and connecting a plurality of tubes in a collective punishment.

(Negative electrode plate)
The negative electrode plate of a lead storage battery is composed of a negative electrode current collector and a negative electrode material. The negative electrode electrode material is a negative electrode plate obtained by removing the negative electrode current collector. The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead or lead alloy sheet. Examples of the processing method include expanding processing and punching processing.

As the lead alloy used for the current collector, Pb-Sb-based alloys, Pb-Ca-based alloys, Pb-Ca-Sn-based alloys and the like are preferable. These leads or lead alloys may further contain, as an additive element, at least one selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu and the like.

The negative electrode material contains a negative electrode active material (lead or lead sulfate) whose capacity is developed by a redox reaction, and may contain a depolarizer, a carbonaceous material such as carbon black, barium sulfate, etc., if necessary. Other additives may be included.

The negative electrode active material in the charged state is spongy lead, but the unchemicald negative electrode plate is usually produced using lead powder.

The negative electrode plate can be formed by filling a negative electrode current collector with a negative electrode paste, aging and drying to produce an unchemicald negative electrode plate, and then forming an unchemicald negative electrode plate. The negative electrode paste is prepared by adding water and sulfuric acid to lead powder, an organic shrink-proofing agent, and various additives as necessary, and kneading them. In the aging step, it is preferable to ripen the unchemicald negative electrode plate at a temperature higher than room temperature and high humidity.

The chemical conversion can be carried out by charging the electrode plate group in a state where the electrode plate group including the unchemical negative electrode plate is immersed in the electrolytic solution containing sulfuric acid in the electric tank of the lead storage battery. However, chemical conversion may be performed before assembling the lead-acid battery or the electrode plate group. The chemical formation produces spongy lead.

(Separator)
A separator is usually arranged between the negative electrode plate and the positive electrode plate. A non-woven fabric, a microporous membrane, or the like is used as the separator. The non-woven fabric is a mat that is entwined without weaving fibers, and is mainly composed of fibers (for example, 60% by mass or more is formed of fibers). As the fiber, glass fiber, polymer fiber (polyester fiber such as polyolefin fiber, acrylic fiber, polyethylene terephthalate fiber, etc.), pulp fiber and the like can be used. Of these, glass fiber is preferable. The non-woven fabric may contain components other than fibers, for example, an acid-resistant inorganic powder, a polymer as a binder, and the like.

On the other hand, the microporous film is a porous sheet mainly composed of components other than fiber components. For example, a composition containing a pore-forming agent (polymer powder and / or oil, etc.) is extruded into a sheet and then pore-formed. It is obtained by removing the agent to form pores. The material constituting the separator is preferably one having acid resistance, and the polymer component is preferably polyolefin such as polyethylene or polypropylene.

The separator may be composed of, for example, only a non-woven fabric or only a microporous membrane. Further, the separator may be, if necessary, a laminate of a non-woven fabric and a microporous film, a material obtained by laminating different or similar materials, or a material in which irregularities are engaged with different or similar materials.

(Electrolytic solution)
The electrolytic solution is an aqueous solution containing sulfuric acid, and may be gelled if necessary. A specific gravity at 20 ° C. of the electrolytic solution in lead-acid battery in a fully charged state after the conversion is, for example, 1.10~1.35g / cm ^3, it is preferable that 1.20~1.35g / cm ^3.

FIG. 5 is a perspective view schematically showing an example in which the lid of the lead storage battery according to the embodiment of the present invention is removed. 6A is a front view of the lead-acid battery of FIG. 5, and FIG. 6B is a cross-sectional view taken along the line VIB-VIB of FIG. 6A. In these figures, as shown in FIG. 3, an example in which the upper part of the side wall of the battery case is covered with a cover is shown.

The lead-acid battery 1 includes an electric tank 10 that houses the electrode plate group 11 and the electrolytic solution 12. When the height of the electric tank 10 is H, the upper side wall above 0.5H from the bottom of the electric tank 10 is covered with the cover 13. The electrode plate group 11 is formed by laminating a plurality of negative electrode plates 2 and positive electrode plates 3 via a separator 4, respectively. Here, the negative electrode plate 2 is wrapped in the bag-shaped separator 4, but the form of the separator is not particularly limited.

An ear portion (not shown) for collecting electricity is provided above each of the plurality of negative electrode plates 2 so as to project upward. Ears (not shown) for collecting electricity are also provided on the upper portions of the plurality of positive electrode plates 3 so as to project upward. The ears of the negative electrode plate 2 are connected and integrated by the negative electrode strap 5a. Similarly, the ears of the positive electrode plates 3 are also connected and integrated by the positive electrode strap 5b. The lower end of the negative electrode column 6a is fixed to the upper part of the negative electrode strap 5a, and the lower end of the positive electrode column 6b is fixed to the upper part of the positive electrode strap 5b.

[Test example]
Hereinafter, the present invention will be specifically described based on Test Examples, but the present invention is not limited to the following Test Examples.

Test Example 1
Resin plates with different thicknesses imitating the side walls of the battery case were prepared, and the temperature change on one surface side was measured when the other surface side was heated.
Specifically, a plate having the thickness shown in Table 1 and formed of the resin shown in Table 1 is placed on a hot plate, and the surface on the hot plate side (one surface) is heated by the hot plate. Then, the change over time in the temperature on the other surface side was investigated. The temperature was measured at three points on an arbitrary straight line parallel to one side of the plate on the other surface of the plate, and an average value was calculated. The air temperature at this time was 22 ° C., and the temperature of one surface during heating was 72 ° C. The thermal conductivity of the resin used was 0.15 to 0.21 W / m · K for PVC and 0.17 to 0.21 W / m · K for ABS. The results are shown in Table 1.

Test Example 2
Next, it was investigated whether convection occurred when the temperature of the liquid was different between the upper part and the lower part.
Specifically, about 300 mL of water or sulfuric acid (specific gravity 1.30 at 20 ° C.) was placed in the beaker as a liquid, and the temperature at the lower part and the upper part of the liquid was monitored while heating the lower part of the beaker with a heater. The distance between the upper and lower positions where the temperature was measured was 10 cm. The presence or absence of convection was visually observed. The temperature at the time of measurement was 22 ° C. The results are shown in Table 2.

As shown in Table 1, when PVC is used, the average temperature of the other surface 1 minute after heating is about 5 mm when the plate thickness is 5 mm, as compared with the case where the plate thickness is 2 mm. The temperature was lowered by 20 ° C., and when the thickness was 10 mm, the temperature was lowered by about 30 ° C. Even after 15 minutes, the average temperature of the other surface is about 8 ° C lower when the plate thickness is 5 mm and about 8 ° C lower when the plate thickness is 10 mm than when the plate thickness is 2 mm. It dropped by about 18 ° C. A similar tendency can be seen when ABS is used.
As shown in Table 2, convection was confirmed within the temperature range shown in Table 2 even when the difference between the temperature of the lower liquid and the temperature of the upper liquid was about 3 ° C. The degree of convection becomes more remarkable as the temperature difference between the upper part and the lower part of the liquid increases, which is advantageous for suppressing stratification.

Generally, when the engine of an automobile is started, the temperature of the engine room becomes about 10 ° C higher than the outside air temperature, and after traveling at a speed of 60 to 70 km / h for about 30 minutes, the equilibrium point is reached and the temperature reaches about 70 ° C. (Approximately 45 ° C higher than the outside temperature). Therefore, if the lead-acid battery according to the present invention is installed in the engine room of the vehicle, the heat trapped in the engine room can be used for convection of the electrolytic solution, which is advantageous in suppressing stratification.

The lead-acid battery according to one aspect of the present invention can be applied to a liquid-type lead-acid battery, and can also be used as a power storage device for vehicles such as automobiles or motorcycles, and as a power source for starting and auxiliary equipment. Further, the lead storage battery may be used as a power source for an industrial power storage device for stationary use or the like.

1: Lead-acid battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5a: Negative electrode strap 5b: Positive electrode strap 6a: Negative electrode pillar 6b: Positive electrode pillar 10: Battery 10B: Bottom of battery plate 11: Electrode plate group 12: Electrolyte 13: Cover 110, 210, 310, 410, 510: Battery 110B, 510B: Bottom 110U, 210U, 310U, 410U, 510U: Upper side wall 110D, 210D, 310D, 410D, 510D: Lower side wall 514: Hollow part

Claims (7)

A group of electrodes including a positive electrode and a negative electrode,
With electrolyte
An electric tank having an opening and accommodating the electrode plate group and the electrolytic solution,
A lid for sealing the opening of the battery case is provided.
The battery case includes a bottom and a side wall rising from the bottom.
When the height of the side wall from the bottom is H, the average heat insulating property in the upper part where the height of the side wall from the bottom is higher than 0.5H is the height of the side wall from the bottom. There rather higher than the average thermal insulation in the lower to 0.5H,
A lead-acid battery in which at least a part of the side wall having a high heat insulating property is formed in a region facing the electrolytic solution. The lead-acid battery according to claim 1, wherein the average thickness of the upper part of the side wall is larger than the average thickness of the lower part of the side wall. The side wall contains a first material having a first thermal conductivity and a second material having a second thermal conductivity higher than the first thermal conductivity.
The first material is distributed more than the second material on the upper part of the side wall.
The lead-acid battery according to claim 1 or 2, wherein the second material is distributed in a lower portion of the side wall in a larger amount than the first material. The side wall has a hollow portion
The lead-acid battery according to any one of claims 1 to 3, wherein the hollow portion is distributed more in the upper part of the side wall than in the lower part of the side wall. The lead-acid battery according to any one of claims 1 to 4, further comprising a cover that covers the upper portion of the side wall from the outside of the battery case. The lead-acid battery according to any one of claims 1 to 5, which is arranged in the engine room of a vehicle. The lead-acid battery according to any one of claims 1 to 6, wherein the side wall has a laminated body of a plurality of films intersecting with each other in the height direction.

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