JP2013020731A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery for improving a reaction characteristic of a battery by solving nonuniformity of current distribution of a collector plate.SOLUTION: The secondary battery has: a battery can 110 having a bottom and an opening; an electrode group 800 which is wound in a flat shape, is formed by overlaying a negative electrode plate 810 over a positive electrode plate 820 via a separator 830, and is housed in the battery can 110 with an end of the negative electrode plate 810 projecting from the separator 830 to form a projection edge 815; a hole sealing plate 120 blocking the opening of the battery can 110 and having a negative electrode terminal 130 on one end side; and a collector 210 interposed between the projection edge 815 and the hole sealing plate 120 and electrically connecting the negative electrode plate 810 and the negative electrode terminal 130. The collector plate 210 becomes thicker or wider from one end side on which the negative electrode terminal 130 of the hole sealing plate 120 is provided toward the other end side.

Description

  The present invention relates to a secondary battery in which an electrode group is housed in a battery can and takes out electric power from the electrode group via a current collector plate, and specifically relates to a secondary battery having an improved structure of the current collector plate. .

  In recent years, secondary batteries such as nickel hydride secondary batteries have been used for power supply applications such as hybrid electric vehicles (HEVs) and electric vehicles (PEVs). In these applications, higher output of the secondary battery is required, and improvement of the reaction characteristics of the battery is required.

  For example, Patent Document 1 describes a secondary battery that includes a wound electrode group wound in a flat shape so that a cross-sectional shape is substantially rectangular, and a battery can that houses the wound electrode group. Yes. The opening of the battery can is closed by a substantially long plate-like sealing plate, and a current collector plate is disposed between the sealing plate and the end face of the wound electrode group to electrically connect them. Yes.

  An electrode terminal is provided on the substantially long sealing plate. The sealing plate may be provided with an injection hole for injecting an electrolytic solution, or an explosion-proof valve that opens when the internal pressure of the secondary battery rises and lowers the internal pressure. When these are provided on the sealing plate In this case, the electrode terminal may be provided on one end side of the sealing plate. Further, when a module body is formed by combining a plurality of secondary batteries, this electrode terminal may be provided on one end side of the sealing plate in order to realize a space-saving connection between the electrode terminals. .

JP 2011-76829 A

  However, when the electrode terminal is provided on one end side of the sealing plate, the other end side of the current collector plate is far from the electrode terminal, so that one end side and the other side of the current collector plate The current distribution becomes non-uniform on the end side of the. For this reason, the reaction characteristics of the battery are lowered at locations far from the electrode terminals of the current collector plate.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a secondary battery that eliminates the non-uniformity of the current distribution of the current collector plate and improves the reaction characteristics of the battery.

  The secondary battery according to the present invention is laminated with a separator between a bottomed battery can having an opening and a belt-like first electrode plate and a second electrode plate, and wound in a flat shape. A cross-sectional shape in a plane perpendicular to the winding axis is substantially rectangular, and an end of the first electrode plate projects from the separator to form a projecting edge having a substantially rectangular cross-sectional shape. The electrode group housed in the battery can with the opening facing the battery can, the opening of the battery can closed, and the electrode terminal of the first pole provided on one end side in the longitudinal direction A plate-shaped sealing plate, a protruding end edge of the first electrode plate of the electrode group, and the sealing plate, and joined to the protruding edge of the first electrode plate, the first electrode plate And a substantially long plate-shaped current collector plate that electrically connects the electrode terminal of the first electrode, and the current collector plate includes: As from the side where the electrode terminals are provided is one end side of the mouth plate toward the other end, the cross-sectional area perpendicular to the longitudinal direction of the collector plate is equal to or larger.

  According to the present invention, the current collector plate has a cross-sectional area that is perpendicular to the longitudinal direction of the current collector plate as it goes farther from the side where the electrode terminals are located. Therefore, there is little decrease in electrical resistance even at a location far from the side where the electrode terminal is located.

  Further, the current collector plate is thickened so that the thickness gradually increases from one end side to the other end side, which is the side where the electrode terminal of the sealing plate is provided. It is preferable that at least one of the widening setting in which the width gradually increases from the one end side toward the other end side is set. In such a case, the thickness of the current collector plate gradually increases as it goes farther from the side where the electrode terminals are located. Further, the width gradually increases from the side where the electrode terminal is located toward the far side. Therefore, there is little decrease in electrical resistance even at a location far from the side where the electrode terminal is located.

  Further, it is preferable that an uncovered portion that is not covered with the current collector plate that is set to be widened is provided on one end side of the protruding end edge of the first electrode plate. In the case where the non-covering part is provided, the generated gas inside the secondary battery can be discharged from the non-covering part, so that the pressure increase inside the secondary battery can be suppressed.

  Moreover, it is preferable that the thickness of the current collector plate with the thickening setting increases continuously. When the thickness of the current collector plate is continuously increased, non-uniformity of the current flowing through the current collector plate is unlikely to occur.

  Moreover, it is preferable that the width | variety of the current collecting plate by which the said wide setting was made increases continuously. When the width of the current collector plate is continuously increased, non-uniformity of the current flowing through the current collector plate is unlikely to occur.

  The sealing plate is provided with an explosion-proof valve that opens to lower the internal pressure when the internal pressure of the secondary battery rises. An explosion-proof opening for allowing escape to the explosion-proof valve is provided, and the width of the explosion-proof opening is gradually increased from the one end side toward the other end side. It is preferable. If the explosion-proof opening of the current collector plate is widened, there will be a large difference in the current flow area near one end of the explosion-proof opening and the other end. There is little possibility that the current distribution becomes non-uniform.

  Moreover, it is preferable that the current collector plate is integrally provided with a raised portion that protrudes toward the sealing plate and is electrically connected to the electrode terminal of the first pole. In such a case, it is advantageous in terms of the number of parts compared to the case where the raised portion is provided separately and joined to the current collector plate, and the physical strength near the current collector plate where the raised portion is provided. Can be improved.

  Moreover, it is preferable that the current collector plate is provided with a protruding portion that protrudes toward the electrode group, and the current collector plate is joined to the protruding edge of the first electrode plate at the protruding portion. In such a case, the current collector plate and the protruding end edge of the electrode group can be more reliably joined.

  According to the present invention, since the electrical resistance is less lowered even at a location far from the side where the electrode terminal is located, the non-uniformity of the current distribution of the current collector plate is eliminated, and the reaction characteristics of the battery are improved.

It is a perspective view explaining the external appearance of a secondary battery. It is a perspective view explaining the external appearance of the electrode group accommodated in a battery can. It is a perspective view explaining the external appearance of a sealing plate and the current collecting plate with which thickening setting was made. It is a perspective view explaining the external appearance of the current collecting plate by which thickening setting was made. It is sectional drawing of the current collecting plate by which thickening setting was made. It is a perspective view explaining the external appearance of a sealing plate and the current collecting plate with which widening setting was made. It is a perspective view explaining the external appearance of the current collector plate with which widening setting was made. It is a top view of the current collecting plate with which wide setting was made. It is sectional drawing of the current collecting plate by which thickening setting was made in another embodiment.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. However, the embodiments are for facilitating understanding of the principle of the present invention, and the scope of the present invention is as follows. The present invention is not limited to the embodiments, and other embodiments in which those skilled in the art appropriately replace the configurations of the following embodiments are also included in the scope of the present invention.

(Embodiment 1)
FIG. 1 is a perspective view for explaining the external appearance of the secondary battery according to the present embodiment. As shown in FIG. 1, the secondary battery 900 is a square battery that is substantially rectangular in shape with both ends being substantially semicircular in cross section, and has a bottomed battery can 110 having an opening. ing. A substantially long sealing plate 120 is joined to the opening of the battery can 110 by, for example, welding.

  FIG. 2 is a perspective view for explaining the external appearance of the electrode group 800 housed in the battery can 110. As shown in FIG. 2, the electrode group 800 is wound in a flat shape, and the cross-sectional shape in a plane perpendicular to the winding axis is substantially semicircular at both ends and is generally rectangular as a whole. The electrode group 800 is formed by laminating a negative electrode plate (first electrode plate) 810 and a positive electrode plate (second electrode plate) 820 with a separator 830 formed of, for example, polyethylene or polypropylene interposed therebetween. In the laminated state, it is flattened into a spiral shape.

The negative electrode plate 810 is provided with a negative electrode active material layer 812 having, for example, natural graphite on the surface of a negative electrode current collector 811 made of, for example, a rectangular copper foil. Is exposed and a current collector exposed portion 813 is provided. The positive electrode plate 820 is provided with a positive electrode active material layer 822 having, for example, LiCoO ₂ on the surface of a positive electrode current collector 821 made of, for example, a rectangular aluminum foil. Is exposed and a current collector exposed portion 823 is provided.

  The end portion of the negative electrode plate 810 protrudes from the separator 830 and has a substantially semi-circular protruding end 815 on the upper side, with both end portions being substantially semicircular in cross-sectional shape. Similarly, the end of the positive electrode plate 820 also protrudes from the separator 830 and forms a protruding edge 825 on the lower side.

  The electrode group 800 is housed in the battery can 110 with the protruding edge 825 of the positive electrode plate 820 placed on the bottom of the battery can 110. In the battery can 110, the electrode group 800 is accommodated together with an electrolytic solution or an electrolyte (hereinafter referred to as “electrolyte”). In the present embodiment, the positive electrode current collecting structure is such that the end of the positive electrode plate 820 protrudes from the separator 830 to form a protruding edge 825 on the lower side, and the protruding edge 825 contacts the bottom of the battery can 110. However, the present invention is not limited to such an embodiment. For example, the end of the positive electrode plate 820 is not protruded from the separator 830 and a lead is connected to the positive electrode plate 820 to collect the lead. It is also possible to use electricity.

  FIG. 3 is a perspective view for explaining the appearance of the sealing plate and the current collector plate. As shown in FIG. 3, the current collector plate 210 is interposed between the protruding edge 815 of the negative electrode plate 810 of the electrode group 800 and the sealing plate 120. The sealing plate 120 is provided with a negative electrode terminal 130 on one end side. The battery can 110 and the sealing plate 120 have the same polarity, and the sealing plate 120 plays a role as a positive electrode. Since the sealing plate 120 is a positive electrode like the battery can 110, the negative electrode terminal 130 is provided through the sealing plate 120 via an insulating member 131 such as a gasket. In this embodiment, the sealing plate 120 plays a role as a positive electrode. However, the sealing plate 120 is not limited to such an embodiment, and for example, a positive electrode terminal can be provided separately.

  The explosion-proof valve 150 is provided, for example, at the center of the sealing plate 120 and opens when the internal pressure of the secondary battery rises to lower the internal pressure. The electrolyte injected into the battery can 110 is injected into the battery can 110 from a liquid injection hole (not shown) formed in the sealing plate 120, and the liquid injection hole is covered with a sealing plug 170 when the electrolyte is injected. The The sealing plug 170 is provided on the other end side of the sealing plate 120.

  The current collector plate 210 is provided with a raised portion 290 that protrudes toward the sealing plate 120 and is electrically connected to the negative electrode terminal 130. The raised portion 290 is provided integrally with the current collector plate 210, but the raised portion 290 as a separate body may be joined to the current collector plate 210 by welding or the like. The current collector plate 210 is joined to the protruding edge 815 of the negative electrode plate 810 on the back surface side, and is electrically connected to the negative electrode terminal 130 via the raised portion 290 on the front surface side. As a result, the current collector plate 210 electrically connects the negative electrode plate 810 and the negative electrode terminal 130.

  FIG. 4 is a perspective view for explaining the appearance of the current collector plate 210 according to the first embodiment. FIG. 5 is a cross-sectional view of the current collector plate 210 according to the first embodiment. As shown in FIGS. 4 and 5, the current collector plate 210 is a side where the electrode terminal 130 of the sealing plate 120 is provided from one end side (the left side in FIG. 5) to the other end side. The thickening setting is made such that the thickness gradually increases as it goes to the right side of the drawing in FIG.

  The current collector plate 210 has a flat part 213 and a protruding part 215. The protruding portion 215 protrudes toward the electrode group 800 from the flat portion 213 and has a substantially rectangular cross section. The connecting portion 215A is located at the protruding end of the protruding portion 215, is in contact with the protruding end edge 815, and is welded by laser welding or the like.

  The thickness of the current collector plate 210 increases continuously. Since the thickness of the current collector plate 210 continuously increases, non-uniformity of the current flowing through the current collector plate 210 hardly occurs. In the present embodiment, as shown in FIGS. 4 and 5, the flat portion 213, the protruding portion 215, and the raised portion 290 are continuously thick. The thickening setting of the current collector plate 210 can be appropriately set in consideration of the material of the current collector plate and the structure and type of the secondary battery, and is not particularly limited. The plate thickness is formed so as to continuously increase in the longitudinal direction from the thickness ds of the thinnest part to the thickness dl of the thickest part. For example, dl = ds × (1.2 to 2.6) And preferably dl = ds × (1.4 to 2.2).

  According to the present embodiment, the current collector plate 210 gradually increases in thickness from the side where the negative electrode terminal 130 is located to the far side. Therefore, there is little decrease in electrical resistance even at a location far from the side where the negative electrode terminal 130 is located. Therefore, the non-uniformity of the current distribution of the current collector plate 210 is eliminated, and the reaction characteristics of the battery are improved. Further, if the thickness ds of the thinnest portion of the current collector plate 210 is set to 0.4 mm, for example, as in the conventional example, and the thickness is continuously increased from here, the strength of the current collector plate 210 as a whole is increased. Therefore, the current collector plate 210 is less likely to be deformed by the gas pressure inside the battery.

(Embodiment 2)
In the above-described embodiment, the current collector plate is set to be thick. However, the scope of the present invention is not limited to such an embodiment. In the second embodiment, the current collector plate is set to be widened so that the width gradually increases.

  FIG. 6 is a perspective view illustrating the appearance of the sealing plate 220 and the current collector plate 220 that has been set to be wider. FIG. 7 is a perspective view for explaining the external appearance of the current collector plate 220 according to the second embodiment. FIG. 8 is a plan view of the current collector plate 220 according to the second embodiment. As shown in FIGS. 6 to 8, the current collector plate 220 has a flat portion 223 and a protruding portion 225 as in the first embodiment, and a connecting portion is provided at the protruding end of the protruding portion 225 in the protruding direction. 225A is located. The current collector plate 220 is interposed between the protruding edge 815 of the negative electrode plate 810 of the electrode group 800 and the sealing plate 120, and the negative electrode terminal 130 is provided on one end side of the sealing plate 120. It has been. The current collector plate 220 is joined to the protruding end edge 815 of the negative electrode plate 810 on the back surface side, and is electrically connected to the negative electrode terminal 130 via the raised portion 290 on the front surface side.

  The current collecting plate 220 moves from one end side (the left side in the drawing in FIG. 8), which is the side where the negative electrode terminal 130 of the sealing plate 120 is provided, to the other end side (the right side in the drawing in FIG. 8). A widening setting is made such that the width is continuously widened. Since the width of the current collector plate 220 is continuously increased, non-uniformity of the current flowing through the current collector plate 220 is unlikely to occur. In the present embodiment, as shown in FIGS. 7 and 8, the flat portion 213, the protruding portion 215, and the raised portion 290 are continuously wide. The widening setting of the current collector plate 220 can be appropriately set in consideration of the material of the current collector plate and the structure and type of the secondary battery, and is not particularly limited. From the width ws of the narrowest portion to the width wl of the widest portion, the plate width is formed so as to continuously increase in the longitudinal direction, for example, wl = ws × (1.6 to 3.2), Preferably, wl = ws × (2.0 to 2.6) can be set.

  As shown in FIGS. 6 and 8, an uncovered portion 816 that is not covered with the current collector plate 220 is provided on one end side of the protruding edge 815 of the positive electrode plate 820. In the present embodiment, the generated gas inside the secondary battery 900 is discharged from the non-covering portion 816, and an increase in internal pressure due to the accumulated generated gas inside the secondary battery can be suppressed. Further, if the width ws of the widest portion of the current collector plate 220 is set to, for example, 16 mm as in the conventional example, and the thickness is continuously reduced from here, the width of one end portion of the current collector plate 220 is the width. Since the weight of the current collector plate 220 is reduced as a whole, the weight of the secondary battery 900 can be reduced.

  An explosion-proof valve 150 is provided at the center of the sealing plate 120, and an explosion-proof opening 222 for allowing the gas inside the secondary battery 900 to escape to the explosion-proof valve 150 is also provided at the center of the current collector plate 220. . As shown in FIGS. 6 to 8, the explosion-proof opening 222 has a width as it goes from one end side where the electrode terminal 130 of the sealing plate 120 is provided to the other end side. Widening setting is made so that gradually becomes wider. The shape of the explosion-proof opening 222 is not particularly limited, and is, for example, a trapezoid or a triangle.

  In the case where the current collector plate 220 that has been set to be wide is provided with an opening having a uniform shape such as a rectangle, the other end side is near one end side of the opening. Since the current flowing area is smaller than the vicinity, the current distribution may be non-uniform. However, in the present embodiment, the explosion-proof opening 222 of the current collector plate 220 is set to be wider, so that the current flows in the vicinity of one end side of the explosion-proof opening 222 and the other end side. There is no great difference and there is little risk of non-uniform current distribution.

  According to the present embodiment, the width of the current collector plate 220 gradually increases from the side where the negative electrode terminal 130 is located to the far side. Therefore, there is little decrease in electrical resistance even at a location far from the side where the negative electrode terminal 130 is located. Therefore, the non-uniformity of the current distribution of the current collector plate 220 is eliminated, and the reaction characteristics of the battery are improved.

(Other embodiments)
In the above-described embodiment, the current collector plate is set to be thickened or widened, but the scope of the present invention is not limited to such an embodiment, and the current collector plate is Both thickening setting and widening setting may be made.

  In the first embodiment, the current collector plate 210 has a continuously increasing thickness. In the second embodiment, the current collector plate 220 has a continuously increasing plate width. Is not limited to such an embodiment. As a modification of the first embodiment, the current collector plate 210 may have a plate thickness that increases stepwise, and as a modification of the second embodiment, the current collector plate 220 may have a plate width that increases stepwise. good.

  For example, as shown in FIG. 9, the thickness of the flat portion 213 is gradually increased, but the thickness of the protruding portion 215 and the thickness of the raised portion 290 can be set not to increase. In such a setting, the non-uniformity of the current distribution of the current collector plate is slightly reduced, but the thickness of the connection portion 215A is constant, so that the contact between the connection portion 215A and the protruding edge 815 is abutted. It is easy to make the contact stress generated in the part uniform. Furthermore, since the thickness of the raised portion 290 does not change, the contact stress generated at the contact portion between the raised portion 290 and the negative electrode terminal 130 can be easily made uniform. In addition, for example, the thickness of the flat portion 213 and the raised portion 290 is gradually increased, but the thickness of the protruding portion 215 can be set not to increase.

  Further, for example, the width of the flat portion 213 is gradually increased, but the width of the protruding portion 215 and the width of the raised portion 290 can be set not to be wide. Also, for example, the width of the flat portion 213 and the raised portion 290 is gradually increased, but the width of the protruding portion 215 can be set not to be wide.

  The present invention is useful as a power source for driving portable electronic devices, mobile communication devices, vehicles, and the like.

110: Battery can 120: Sealing plate 130: Negative electrode terminal 150: Explosion-proof valve 210: Current collecting plate 220: Current collecting plate 222: Explosion-proof opening 290: Raised portion 800: Electrode group 810: Negative electrode plate 820: Positive electrode plate 815: Protruding edge 816: Uncovered portion 830: Separator 900: Secondary battery

Claims (8)

A bottomed battery can having an opening;
The first pole electrode is formed by laminating a separator between a strip-shaped first electrode plate and a second electrode plate, wound in a flat shape, and having a substantially rectangular cross-sectional shape in a plane perpendicular to the winding axis. An end portion of the plate protrudes from the separator to form a protruding edge having a substantially rectangular cross-sectional shape, and the electrode group is housed in the battery can with the protruding edge facing the opening side of the battery can. When,
A substantially plate-shaped sealing plate that closes the opening of the battery can and includes an electrode terminal of a first pole on one end side in the longitudinal direction;
The first electrode plate and the electrode of the first electrode are inserted between the protruding edge of the first electrode plate of the electrode group and the sealing plate, and joined to the protruding edge of the first electrode plate. In a secondary battery having a substantially long current collector plate that electrically connects the terminal,
The current collector plate has a cross-sectional area perpendicular to the longitudinal direction of the current collector plate as it goes from one end side, which is the side where the electrode terminal of the sealing plate is provided, to the other end side. A secondary battery characterized by comprising:   The current collector plate is a thickening setting in which the thickness gradually increases from one end side to the other end side, which is the side where the electrode terminal of the sealing plate is provided, and 2. The secondary according to claim 1, wherein at least one of a widening setting in which the width gradually increases from the one end side toward the other end side is made. battery.   3. The non-covering portion that is not covered with the current collector plate that is set to be widened is provided on one end side of the protruding end edge of the first electrode plate. The secondary battery as described.   4. The secondary battery according to claim 2, wherein a thickness of the current collector plate set to be thickened continuously increases. 5.   5. The secondary battery according to claim 2, wherein the width of the current collector plate that is set to be widened increases continuously. 6. The sealing plate is provided with an explosion-proof valve that opens to lower the internal pressure when the internal pressure of the secondary battery increases,
The current collector plate set to be widened is provided with an explosion-proof opening for allowing the gas inside the secondary battery to escape to the explosion-proof valve,
6. The explosion-proof opening according to claim 1, wherein the width of the explosion-proof opening is gradually increased from the one end to the other end. A secondary battery according to item.   7. A raised portion that is raised on the side of the sealing plate and is electrically connected to the electrode terminal of the first pole is integrally provided on the current collector plate. The secondary battery according to claim 1.   The current collector plate is provided with a projecting portion projecting toward the electrode group, and the current collector plate is joined to the projecting edge of the first electrode plate at the projecting portion. Item 8. The secondary battery according to any one of Items 1 to 7.

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