JP2011181321A - Lead-acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the disconnection of a joint part between a positive electrode current collecting lug and a positive electrode strap due to vibration in particular. <P>SOLUTION: In the crystalline structure of a joint between the positive electrode current collecting lug and the positive electrode strap, a first region is formed which has a crystalline structure oriented in the longitudinal direction of the positive electrode current collecting ear. At the front end of the positive electrode current collecting lug, where the sizes of crystal grains in the thickness direction of the positive electrode current collecting lug are crystal grain sizes, a second region is formed which is a region ranging from the first region, which has an average crystal grain size larger than the average crystal grain size of the first region, and which has a crystalline structure aligned in the longitudinal direction of the positive electrode current collecting lug. Ranging from the second region, a third region is arranged which has a crystalline structure not oriented in a specific direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lead-acid battery.

  In lead-acid batteries for automobiles, a plurality of positive and negative electrode plates are combined via a separator, and current collecting ears provided on each of the positive and negative electrode plates melt around current collecting ears of the same polarity. A strap is formed by supplying lead and cooling and solidifying the molten lead. The strap includes the tip of the current collecting ear to electrically connect the current collecting ears.

  In Patent Document 1, when the current collector ear obtained by processing the rolled sheet is integrated by welding, the crystal state of the current collector ear changes, particularly in the positive electrode, due to the elongation of the electrode plate, It is shown that bending occurs at the site where the recrystallization of the current collecting ear is formed. For the purpose of suppressing such bending of the current collecting ear of the positive electrode, from the root where the surface of the current collecting ear and the surface of the strap are in contact to the boundary between the recrystallized structure and the rolled structure on the surface of the current collecting ear It is shown that the length X is equal to or less than the thickness Y of the ear portion.

JP 2009-064720 A

  On the other hand, lead-acid batteries for automobiles are required to be smaller and lighter and have higher output, and due to these demands, the grid has been made thinner, and current collecting ears provided integrally with the grid There is a tendency that the thickness is further reduced and the strength is lowered.

  Furthermore, in a lead-acid battery for automobiles, vibration is applied along with the bending of the positive electrode current collector ear due to the elongation of the lattice as shown in Patent Document 1, and therefore, the recrystallized structure formed by welding, and the rolled structure There was a problem that the current collecting ear was disconnected at the boundary. Such disconnection of the positive electrode current collecting ear causes a rapid decrease in battery capacity.

  The present invention provides a lead-acid battery that suppresses disconnection of the positive electrode current collector ear at the junction between the positive electrode strap and the positive electrode current collector ear and is more reliable.

  In order to solve the above-described problem, an invention according to claim 1 of the present invention is a positive electrode comprising a positive electrode grid made of a lead alloy and provided with a positive electrode current collecting ear, and a positive electrode active material filled in the positive electrode grid. A lead storage battery comprising a plurality of plates, wherein a plurality of the positive electrode current collector ears are connected by a positive electrode strap, wherein the positive electrode current collector ear is a cross section parallel to the thickness direction and the longitudinal direction of the positive electrode current collector ear, A first region composed of a crystal structure oriented in the longitudinal direction of the positive electrode current collector ear and a dimension of the crystal grain in the thickness direction of the positive electrode current collector ear are taken as the crystal grain size. A second region having an average crystal grain size larger than the average crystal grain size of the first region and having a crystal structure arranged in the longitudinal direction, and the second region A third structure composed of a crystal structure that is continuous with a region and is not oriented in a specific direction It shows a lead-acid battery and having a region.

  Further, the invention according to claim 2 of the present invention is the lead storage battery having the configuration of claim 1, wherein one of the positive electrode current collector ears is arranged in the thickness direction of the base portion exposed from the positive electrode strap of the positive electrode current collector ear. The third region does not exist in the thickness direction of the base, or the third region is discontinuous by the second region. It has the site | part which becomes.

  According to the configuration of the first aspect of the present invention, the first region between the third region having no crystal directionality and the first region oriented with priority in the longitudinal direction over the thickness direction of the current collecting ears. By disposing a second region having a grain size larger than that of the crystal in the region and having a crystal structure oriented in the longitudinal direction in preference to the thickness direction of the current collecting ear, And the disconnection of the positive electrode current collection ear which occurred in the part which the 3rd field contacted directly can be controlled.

  Further, according to the configuration of claim 2, since the third region is not continuous in the thickness direction at the portion exposed from the positive electrode strap of the current collecting ear, the crystal grain boundary of the third region is in the current collecting ear thickness direction. As a result, even if corrosion occurs at the crystal grain boundary in the third region, disconnection of the positive electrode current collector ear can be suppressed, which is more preferable.

The figure which shows the positive electrode strap and positive electrode current collection ear | edge of the lead acid battery of the 1st Embodiment of this invention. The schematic diagram which shows the crystal state of the positive electrode current collection ear | edge of the lead acid battery of the 1st Embodiment of this invention. (A) Schematic diagram showing the crystal form of the second region (b) Schematic diagram showing the crystal state of the first region The schematic diagram which shows the crystal state of the positive electrode current collection ear | edge of the lead acid battery of the 2nd Embodiment of this invention. Schematic diagram showing the crystal state of the positive electrode current collector ear of the lead storage battery of the comparative example

(First embodiment)
As shown in FIG. 1, the lead storage battery according to the first embodiment of the present invention has a plurality of positive electrode plates 1 each having a positive electrode current collector ear 1 a, and the positive electrode current collector ear 1 a is connected by a positive electrode strap 2. ing. In addition, although not specifically illustrated, the positive electrode plate 1 is a plate in which a positive electrode active material is filled in a positive electrode lattice body including a positive electrode current collecting ear 1a as is well known.

  The positive electrode grid body and the positive electrode current collecting ear 1a are made of a lead alloy, and include, for example, about 0.03% by mass to about 0.09% by mass of calcium, and further include 0.5% by mass to 1.80% by mass of tin. A well-known lead alloy for positive electrodes can be used.

  In the present invention, the positive electrode grid body and the positive electrode current collector ear 1a provided integrally therewith can be obtained by subjecting a rolled sheet to mechanical processing such as punching perforation processing or expansion processing. Moreover, the positive electrode grid body by continuous casting obtained by supplying a molten lead alloy to a continuous casting mold, such as a drum type, may be rolled.

  The positive electrode grid body and the positive electrode current collector ear 1a obtained as described above exhibit a layered crystal form along the plane perpendicular to the thickness direction of the positive electrode grid body, by rolling the lead alloy crystal by rolling. .

  In the present invention, the crystal state after the collective welding of the positive electrode current collecting ear 1a with the positive electrode strap 2 is the state shown in FIGS. FIG. 2 shows a positive electrode strap 2 of the lead-acid battery of the present invention in a plane parallel to the thickness direction (direction X in FIG. 2) and the longitudinal direction (direction Y in FIG. 2) of the positive electrode current collecting ear 1a, that is, the direction X It is a figure which shows the cross section at the time of cut | disconnecting by the surface formed by two vectors of and Y direction.

  The portion of the positive electrode current collecting ear 1a that is separated from the positive electrode strap 2 is oriented in the longitudinal direction of the positive electrode current collection ear 1a by being pressed down in the thickness direction that existed from the stage before the formation of the positive electrode strap 2. There is a first region C having a crystal structure consisting of crystal grains 4c. The crystal grains 4c constituting the first region C have a form as shown in FIG.

  On the other hand, the portion of the positive electrode current collecting ear 1 a included in the positive electrode strap 2 is changed to a crystal structure having no specific orientation due to recrystallization due to heat at the time of forming the positive electrode strap 2. There is a crystal structure composed of block-like crystal grains 4a having no specific orientation. This region is referred to as a third region A.

  In the present invention, the second region B is further provided between the first region C and the third region A described above. As shown in FIG. 3A, the crystal grain 4b constituting the second region B has a direction (Y) in a cross section when cut along a plane defined by the direction (X) and the direction (Y). ) In the longitudinal direction of the crystal grains 4b.

  However, when the crystal grains 4b and the crystal grains 4c in the first region C are taken as the crystal grain size in the thickness direction of the positive electrode current collector ear 1a, the average crystal grain size of the crystal grains 4b is It is larger than the average crystal grain size of 4c.

  In the present invention, an intermediate crystal is formed between the third region A recrystallized in an indefinite direction by heat during welding and the first region C having the initial crystal structure of the positive electrode current collector ear 1a. A second region B having a tissue is arranged. According to such a configuration, it is possible to suppress disconnection of the positive electrode current collecting ear 1a that has occurred at the boundary between the first region C and the third region A.

  In order to form the second region B, the relationship between the temperature (or heat amount) of the molten lead alloy that is cooled and solidified to become the positive electrode strap 2 and the temperature (or heat capacity) of the positive electrode current collecting ear 1a immediately before welding, and the positive electrode The cooling conditions of the mold for forming the strap 2 are adjusted. When the heat capacity of the positive electrode current collector ear 1a is small with respect to the amount of heat of the molten metal and the cooling rate of the positive electrode current collector ear 1a is large, a boundary between the first region C and the third region A occurs. It is not preferable. The temperature of the molten metal is limited to such an extent that the formation of the third region A does not proceed excessively, and the positive electrode current collecting ear 1a is gradually cooled so that the space between the first region C and the third region A is reduced. The second region B can be formed.

  The conditions for forming the second region B differ depending on the size and shape of the positive electrode current collecting ear 1a, the size and shape of the positive electrode strap 2, or the method of forming the positive electrode strap 2, and accordingly, depending on the size and shape and method of construction. Set.

(Second Embodiment)
The second embodiment of the present invention has the following configuration in addition to the configuration of the first embodiment described above. That is, as shown in FIG. 4, in the thickness direction (X) of the base 1b exposed from the positive strap 2 of the positive current collecting ear 1a, the positive current collecting ear 1a continues from one surface to the other surface. It does not have the 3rd field A to do. That is, in the thickness direction of the base 1b, the third region A does not exist (the state shown in FIG. 4), or the third region A has a portion discontinuous by the second region B. According to the present embodiment, disconnection of the positive electrode current collecting ear 1a can be further suppressed, which is more preferable.

  Light load as defined in JIS D5301 by manufacturing the lead storage battery of the present invention and the lead storage battery of the comparative example (both are 80D26 type lead storage batteries in JIS D5301, hereinafter referred to as batteries) according to the first and second embodiments described above. A life test was conducted. In the light load life test, in addition to a test in which a normal battery was left stationary, a test was also performed while applying vibration to the battery.

(Battery A1 of the present invention example)
Battery A1 of the example of the present invention has a positive electrode lattice body obtained by expanding a 0.80 mm thick rolled sheet made of lead-0.07 mass% calcium-1.60 mass% tin alloy. This positive electrode lattice body was filled with an active material paste made of lead powder, water and sulfuric acid in the positive electrode lattice, and aged and dried by a conventional method to obtain a positive electrode plate 1. The thickness of the positive electrode current collector ear 1a is 0.80 mm.

  The negative electrode grid is obtained by expanding a rolled sheet made of a lead-calcium 0.07 wt% -tin 0.25 wt% alloy, and the negative electrode grid is formed of lead powder, water, sulfuric acid, and a predetermined amount of lignin. , Filled with an active material paste composed of carbon and barium sulfate, and aged and dried by a conventional method to obtain a negative electrode plate.

  In the battery A1, the negative electrode plate is housed in a bag-shaped separator made of a microporous film in which silica and mineral oil are added to polyethylene resin, and after combining with the positive electrode plate 1, the positive electrode strap 2 and the negative electrode strap are Formed.

  In the present embodiment, a method was adopted in which both the positive strap 2 and the negative strap were loaded with a cuboidal lead alloy on a cast-on mold, and the lead alloy was heated by high frequency induction heating and melted. In the positive electrode strap 2, the temperature-controlled positive electrode current collecting ear 1a was inserted into the molten metal, and then the melting was cooled and solidified. However, the amount of heat supplied to the molten metal was controlled by the electric power supplied to the induction coil. The surface temperature of the positive electrode current collector ear 1a immediately before insertion into the molten metal was set to 70 ° C. The additional lead is melted by high-frequency induction heating, and the positive electrode current collecting ear 1a is inserted into the molten metal while maintaining the surface temperature of the molten metal at 460 ° C. In addition, in order to control the temperature of the molten metal, the surface temperature of the molten metal is measured, and when this measured value falls below the control range, the electric power supplied to the induction coil is increased. Control is performed to increase the energization power to the coil. In the battery A1 of the present invention, the temperature of the molten metal was controlled at 460 ° C. for 1 second from the time when the positive electrode current collecting ear 1a was inserted into the molten metal, and then the energization to the induction coil was stopped to cool and solidify the molten metal. I let you.

  The cross section of the positive electrode strap 2 and the positive electrode current collector ear 1a of the battery A1 of the present invention example has the crystal structure of the first embodiment shown in FIG.

(Battery A2 of the present invention example)
The battery A2 of the present invention is the same as the battery A1 of the present invention described above, by reducing the power supplied to the induction coil by reducing the power supplied to the induction coil, thereby reducing the amount of heat applied to the lead, as shown in FIG. It has a crystal structure of Both the battery A1 and the battery A2 of the example of the present invention have a configuration in which the tip of the positive current collector ear 1a is also heated by the magnetic field generated from the induction coil before the tip of the positive current collector ear 1a is inserted into the mold. It was. In the battery A2 of the present invention example, the temperature of the positive electrode current collecting ear 1a was kept at 70 ° C. Also, the temperature of the molten metal was set to 450 ° C., and after inserting the positive electrode current collecting ear 1a into the molten metal, the molten metal temperature was maintained at 450 ° C. for 0.5 seconds, and then the current supply to the induction coil was stopped. Cool and solidify.

(Batteries B1 and B2 of comparative examples)
The battery B1 of the comparative example is based on the same positive electrode plate 1, negative electrode plate, and bag-like separator as the above-described batteries A1 and A2, and the same strap formation method. However, the standby position of the positive electrode current collector ear 3a is further away from the mold so that the amount of heat supplied to the lead added in the strap formation at the positive electrode is further increased and the positive electrode current collector ear 3a before the strap formation is not induction heated. It is what was made the position. As a result, as shown in FIG. 5, the third region A and the first region C are directly joined in the cross section of the positive strap 2 and the positive current collecting ear 3a. In particular, in the battery B1 of the comparative example, the boundary between the third region A and the first region C is arranged at a position outside the strap 2 with respect to the base 3b. The strap B of the battery B1 of the comparative example was formed by inserting the positive electrode current collector ear 3a into the molten metal having a surface temperature of 480 ° C. after maintaining the surface temperature of the positive electrode current collector ear 3a at 20 ° C. The temperature was held at 480 ° C. for 2.5 seconds and then cooled.

  Further, the battery B2 of the comparative example has a configuration in which the boundary between the first region C and the third region A is 0.2 mm from the base 3b and is located inside the positive strap 2 in the battery B1 of the comparative example. Have. The conditions for forming the strap of the battery B2 of Comparative Example were that the surface temperature of the positive electrode current collecting ear 3a was kept at 20 ° C., then held in a molten metal at 480 ° C. for 1.5 seconds, and then cooled.

  For each of these batteries, the positive electrode strap 2 and the positive electrode current collector ears 1a and 3a were sampled, and the crystal grain size in the thickness direction of each region in the positive electrode current collector ears 1a and 3a direction was measured. The range of the crystal grain size of each region is 5 μm to 40 μm in the first region C, 15 μm to 200 μm in the second region B, and 10 to 250 μm in the third region A for each battery, The average crystal grain size was 8 to 15 μm in the first region C, 20 to 40 μm in the second region B, and 50 to 150 μm in the third region A.

  About these batteries A1, A2, B1, and B2, the light load life test was done in 75 degreeC gaseous-phase atmosphere. As described above, this life test was performed in a state in which a vertical vibration of 30 Hz was applied to the battery at an acceleration of 1 G in addition to the test in which a normal battery was left stationary. This vibration direction coincides with the longitudinal direction of the positive electrode current collecting ears 1a, 3a (direction (Y) shown in FIGS. 2 to 5).

  In the light load life test, the battery was discharged at a current of 25 A for 4 minutes and then charged for 10 minutes at a charging voltage of 14.8 V (maximum current: 25 A). It is left in a gas phase atmosphere at 25 ° C. for 56 hours, and after that, it is discharged at 582A for 30 seconds. The cycle number is calculated as the life when the voltage at 30 seconds falls below 7.2V.

  Table 1 shows the results of the life test conducted under the above test conditions. In Table 1, the percentage with respect to the number of life cycles when the vibration of the battery A1 of the present invention was applied is shown as a life index.

  From the results shown in Table 2, the battery A1 and battery A2 of the example of the present invention are less affected by the vibration life than the batteries B1 and B2 of the comparative example, and an improvement in the life when applying vibration is recognized. It was. When these batteries were disassembled and investigated after the end of the life test, the positive current collecting ear 3a was disconnected at the time of application of vibration, and the batteries B1 and B2 of the comparative examples reached the end of their lives early. When the crystal structures of the disconnected positive electrode current collecting ear 3a on the side remaining on the positive electrode strap 2 and on the side remaining on the positive electrode plate were observed, the positive electrode current collecting ear 3a remaining on the side remaining on the positive electrode strap 2 was aligned. The crystal structure on the positive electrode plate side had a crystal structure oriented in the longitudinal direction of the positive electrode current collecting ear 3a.

  From this result, it is considered that in the batteries B1 and B2 of the comparative example, disconnection occurred at discontinuous portions of the crystal structure of the positive electrode current collecting ear 3a. The battery B2 had better life characteristics than the battery B1. This is because the portion of the positive electrode current collecting ear 3a where the crystal structure changes is located inside the positive electrode strap 2 rather than the base portion 3b of the positive electrode current collecting ear 3a. This is probably because extreme concentration was avoided.

  On the other hand, the battery A1 and the battery A2 of the example of the present invention did not break the positive electrode current collecting ear 1a even when vibration was applied, and had a longer life than the batteries B1 and B2 of the comparative example. However, the battery A1 of the invention example tended to have a slightly shorter life than the battery A2 of the invention example. When the crystal structure of the positive electrode current collector ear 1a of the battery A1 was observed, the boundary between the third region A that was not oriented in a specific direction and the second region B that was oriented in the longitudinal direction of the positive electrode current collector ear 1a Corrosion slightly progressed, and the positive electrode current collecting ear 1a was deformed at that site. Regarding the battery A2 of the present invention example, the corrosion and the deformation slightly progressed in the second region B and the third region A of the positive electrode current collecting ear 1a, but the lifetime was longer than that of the battery A1. Met.

  According to the present invention, even when vibration is applied to the lead storage battery, disconnection of the positive electrode current collecting ear in the positive strap is suppressed, and a long-life lead storage battery can be obtained. In addition, the present invention is suitable for lead storage batteries for various uses including liquid type start-up storage batteries.

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 1a Positive electrode collector ear 1b Base 2 Positive electrode strap 3a Positive electrode collector ear 3b Base 4a, 4b, 4c Crystal grain A 3rd area | region B 2nd area | region C 1st area | region

Claims (2)

A positive electrode grid made of a lead alloy and provided with a positive electrode current collecting ear;
A plurality of positive electrode plates comprising a positive electrode active material filled in the positive electrode grid;
A lead storage battery in which a plurality of the positive electrode current collecting ears are connected by a positive electrode strap,
In a cross section parallel to the thickness direction and the longitudinal direction of the positive electrode current collector ear,
The positive electrode current collector ear is:
A first region comprising a crystal structure oriented in the longitudinal direction of the positive electrode current collector ear;
At the tip of the positive electrode current collector ear,
When the size of the positive electrode current collecting ear in the thickness direction of the crystal grain is the crystal grain size,
A second region consisting of a crystal structure that is continuous with the first region, has an average crystal grain size larger than the average crystal grain size of the first region, and is arranged in the longitudinal direction as described above. Area of
A lead-acid battery comprising: a third region having a crystal structure that is continuous with the second region and is not oriented in a specific direction. In the thickness direction at the base exposed from the positive electrode strap of the positive electrode current collecting ear, the positive electrode current collecting ear does not include the third region continuous from one surface of the positive electrode current collecting ear to the other surface,
2. The lead according to claim 1, wherein in the thickness direction of the base portion, the third region does not exist, or the third region has a portion discontinuous by the second region. Storage battery.

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