JP2006164713A - Secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery in which a current collector jointed to an electrode body being a power generation element can be welded to the bottom of a battery can with a large jointing area, capable of reducing the internal resistance of the battery. <P>SOLUTION: The secondary battery is constructed by housing a wound-up electrode body 4 inside a battery can 1, in which a sealing plate 2 is fixed at the opening part of a bottomed cylinder 11. A positive electrode current collector 51 is connected to the end fringe of the core 45 on the positive electrode side of the wound-up electrode body 4, and a negative electrode current collector 5 is connected to the end fringe of the core 47 on negative electrode side. The surface of the negative electrode current collector 5 is welded to the bottom of the bottomed cylindrical body. A projection 14 protruding toward the inside of the battery can 1 is formed at the bottom of the bottomed cylinder 11 and a recessed face 56 which is engaged with the projection 14 is formed on the surface of the negative electrode current collector 5, and a resistance welding is applied to the engaging portion of the recessed face 56 and the projection 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a secondary battery, and in particular, one of a positive current collector plate and a negative current collector plate joined to an electrode body serving as a power generation element is welded to the bottom surface of a battery can. The present invention relates to a secondary battery.

As shown in FIG. 5, the cylindrical lithium ion secondary battery is configured by accommodating a winding electrode body (4) inside a cylindrical battery can (7). The battery can (7) is formed by caulking and fixing the sealing plate (2) to the opening of the bottomed cylindrical body (71) via the insulating member (13), and the take-up electrode body (4) has a belt-like shape. The separator (42) is interposed between the positive electrode (41) and the negative electrode (43), and these are wound in a spiral shape, and have a through hole (49) in the winding axis.
The positive electrode current collector plate (51) is welded to the edge of the positive electrode (41) of the winding electrode body (4), and the tip of the lead portion (53) protruding from the positive electrode current collector plate (51) Is welded to the back surface of the sealing plate (2).

The sealing plate (2) has a two-layer structure in which an iron-nickel plating plate (21) and an aluminum plate (22), which are plated with nickel on the surface of a steel plate-like base material, are joined together. With the plate (2) being caulked and fixed to the opening of the bottomed cylinder (71), the iron-nickel plating plate (21) faces the outside of the battery can (7), and the aluminum plate (22) is the battery. Facing the inside of the can (7).
The iron-nickel plating plate (21) has a central hole (26), and the aluminum plate (22) has a predetermined internal pressure in a region facing the central hole (26) of the iron-nickel plating plate (21). A valve membrane (23) to be opened when the value is exceeded is formed. A positive electrode terminal (24) is attached to the surface of the iron-nickel plating plate (21). On the other hand, the negative electrode current collector plate (72) is welded to the edge of the negative electrode (43) of the take-up electrode body (4), and the surface of the negative electrode current collector plate (72) has a bottomed cylindrical body (71). ) (See Patent Document 1).

  As shown in FIG. 7, on the surface of the negative electrode current collector plate (72), facing the through hole (49) of the winding electrode body (4), facing the bottom surface of the bottomed cylindrical body (71). A plurality of projecting projections (73) are formed on the same circumference.

Conventionally, when the negative electrode current collector plate (72) is welded to the bottom surface of the bottomed cylindrical body (71), as shown in FIG. 6, the take-up electrode body (4) to which the negative electrode current collector plate (72) is welded is shown. Is inserted into the through hole (49) of the wound electrode body (4), and the tip of the electrode bar (61) is inserted into the through hole (49) of the wound electrode body (4). While making it contact with the back surface of a negative electrode current collecting plate (72), an electrode piece (62) is made to contact the back surface of a bottomed cylinder (71) facing this electrode rod (61). Then, by passing a current between the electrode rod (61) and the electrode piece (62), the negative electrode current collector plate (72) and the bottomed cylindrical body (71) are resistance-welded to each other.
Thus, the negative electrode current collector plate (72) and the bottomed cylindrical body (71) are joined at the top of each projection (73) of the negative electrode current collector plate (72) and the bottom surface of the bottomed cylindrical body (71). Are electrically connected to each other.
JP-A-6-275653 [H01M 2/22]

However, in the conventional cylindrical lithium ion secondary battery, the negative electrode current collector (72) and the bottomed cylindrical body (71) are merely welded to each other at the apex of the projection (73). The junction area between the two becomes small. For this reason, the connection resistance between the negative electrode current collector plate (72) and the bottomed cylindrical body (71) becomes large, which increases the internal resistance of the battery, and there is a problem that high charge / discharge performance cannot be obtained. there were.
The negative current collector (72) and the bottomed cylinder (71) are resistant to each other while a part of the plurality of projections (73) is separated from the bottom surface of the bottomed cylinder (71). As a result, the connection resistance between the negative electrode current collector plate (72) and the bottomed cylindrical body (71) may be further increased.
Therefore, an object of the present invention is to be able to weld the current collector plate and the bottomed cylindrical body to each other with a large joint area, thereby reducing the connection resistance between the current collector plate and the bottomed cylindrical body. It is to provide a secondary battery.

In the secondary battery according to the present invention, a sealing plate (2) is fixed to an opening of a bottomed cylindrical body (11) through an insulating member (13) to form a battery can (1). The electrode body (4) is accommodated inside 1). A pair of electrodes (41) and (43) protrude from both ends of the electrode body (4), and one of the pair of electrodes (41) and (43) is electrically connected to the sealing plate (2). Connected. A current collector plate (5) is joined to the edge of the other electrode, and the surface of the current collector plate (5) and the bottom surface of the bottomed cylindrical body (11) are welded together. Thereby, the electric power generated by the electrode body (4) can be taken out from the sealing plate (2) and the bottomed cylindrical body (11).
A convex surface (14) protruding toward the inside of the battery can (1) is formed on the bottom surface of the bottomed cylindrical body (11), while the bottom surface of the current collector plate (5) A concave surface (56) that fits with the convex surface (14) of the cylindrical body (11) is formed, and the fitting portion between the convex surface (14) and the concave surface (56) is welded.

  In the secondary battery of the present invention, when welding the surface of the current collector plate (5) and the bottom surface of the bottomed cylindrical body (11), the concave surface (56) formed on the surface of the current collector plate (5) is provided. The bottom surface of the bottomed cylindrical body (11) is fitted to a convex surface (14) projecting from the bottom surface. Thereby, the concave surface (56) of the current collector plate (5) and the convex surface (14) of the bottomed cylindrical body (11) are in close contact with each other. The current collector plate (5) and the bottomed cylindrical body (11) are welded to each other at the fitting portion between the convex surface (14) and the concave surface (56). In this way, the current collector plate (5) and the bottomed cylinder (11) are welded in a state where they are in surface contact with each other at the fitting portion, so that the current collector plate and the bottomed cylinder are in point contact with each other. Compared to the conventional case where the current collector plate (5) and the bottomed cylindrical body (11) are joined together, the joining area is large. Thereby, the connection resistance between the current collector plate (5) and the bottomed cylindrical body (11) becomes small. As a result, the internal resistance of the secondary battery can be reduced, and high charge / discharge performance can be obtained.

  In a specific configuration, in a state where the concave surface (56) of the current collector plate (5) is fitted to the convex surface (14) of the bottomed cylindrical body (11), The region excluding the concave surface (56) is separated from the bottom surface of the bottomed cylindrical body (11).

  According to the specific configuration, the current collector plate (5) and the bottomed surface are provided in a region other than the fitting portion between the concave surface (56) of the current collector plate (5) and the convex surface (14) of the bottomed cylindrical body (11). Since the cylindrical body (11) does not contact each other, the concave surface (56) of the current collector plate (5) can be securely fitted to the convex surface (14) of the bottomed cylindrical body (11). Thus, the contact state between the concave surface (56) of the current collector plate (5) and the convex surface (14) of the bottomed cylindrical body (11) can be made more reliable.

  Specifically, resistance welding is applied to a fitting portion between the convex surface (14) of the bottomed cylindrical body (11) and the concave surface (56) of the current collector plate (5).

  In the specific configuration, the concave surface (56) and the convex surface (14) of the current collector plate (5) and the convex surface (14) of the bottomed cylindrical body (11) are in close contact with each other. When energized between them, heat is generated in the fitting portion between the convex surface (14) and the concave surface (56), thereby melting the fitting portion, and the current collector plate (5) and the bottomed cylindrical body (11) Will be resistance welded together.

  Alternatively, laser welding is applied to a fitting portion between the convex surface (14) of the bottomed cylindrical body (11) and the concave surface (56) of the current collector plate (5).

  According to the specific configuration, the concave surface (56) and the convex surface (56) are in close contact with the concave surface (56) of the current collector plate (5) and the convex surface (14) of the bottomed cylindrical body (11). By irradiating the fitting portion of 14) with laser light, substantially the entire fitting portion can be melted to weld the current collector plate (5) and the bottomed cylindrical body (11) to each other. As a result, the joint area between the current collector plate (5) and the bottomed cylinder (11) becomes larger than when the current collector plate (5) and the bottomed cylinder (11) are resistance-welded. As a result, the connection resistance between the current collector plate (5) and the bottomed cylindrical body (11) is smaller than that when the current collector plate (5) and the bottomed cylindrical body (11) are resistance-welded. Become.

  In a specific configuration, each of the electrode bodies (4) is configured by winding a separator (42) between a strip-like positive electrode (41) and a negative electrode (43) in a spiral shape. A through hole (49) is provided in the shaft center part, and the current collector plate (5) has a concave part (54) having the concave surface (56) at a position facing the through hole (49) of the electrode body (4). ) And a convex portion (12) having the convex surface (14) at a position facing the concave portion (54) is formed on the bottom surface of the bottomed cylindrical body (11).

  In the specific configuration, when the current collector plate (5) is resistance-welded to the bottom surface of the bottomed cylindrical body (11), the electrode body (4) is accommodated in the bottomed cylindrical body (11), An electrode rod is inserted into the through hole (49) of the electrode body (4), and a current collector plate (5) formed at a position where the tip of the electrode rod faces the through hole (49) of the electrode body (4) ) Is brought into contact with the recess (54). Accordingly, the concave surface (56) formed in the concave portion (54) of the current collector plate (5) is opposed to the convex surface (12) of the convex portion (12) formed on the bottom surface of the bottomed cylindrical body (11). Fit to 14). Then, by contacting an electrode piece to the back surface of the convex portion (12) of the bottomed cylindrical body (11) and energizing between the electrode piece and the electrode rod, the convex surface (14) and the concave surface (56) A current flows through the fitting portion, the fitting portion melts, and the current collector plate (5) and the bottomed cylindrical body (11) are resistance-welded to each other.

  According to the secondary battery of the present invention, the current collector plate and the bottomed cylinder can be welded to each other with a large joint area, thereby reducing the connection resistance between the current collector and the bottomed cylinder. I can do it.

Hereinafter, embodiments of the present invention applied to a cylindrical lithium ion secondary battery will be described in detail with reference to the drawings.
As shown in FIG. 1, a cylindrical lithium ion secondary battery according to the present invention has a winding electrode body (4) housed inside a cylindrical battery can (1). The sealing plate (2) is caulked and fixed to the opening of the bottomed cylindrical body (11) made of an iron-nickel plating plate via a ring-shaped insulating member (13).

The sealing plate (2) has a two-layer structure in which an iron-nickel plating plate (21) and an aluminum plate (22), which are plated with nickel on the surface of a steel plate-like base material, are joined together. With the plate (2) caulked and fixed to the opening of the bottomed cylinder (11), the iron-nickel plating plate (21) faces the outside of the battery can (1), and the aluminum plate (22) is the battery. Facing the inside of the can (1).
The iron-nickel plating plate (21) has a circular central hole (26), and the aluminum plate (22) has an internal pressure in a region facing the central hole (26) of the iron-nickel plating plate (21). A valve membrane (23) to be opened is formed when the pressure exceeds a predetermined value (0.98 to 1.18 MPa).

  As shown in FIG. 2, the wound electrode body (4) has a positive electrode (41) formed by applying a positive electrode active material (44) made of lithium cobalt oxide on the surface of a core body (45) made of an aluminum foil having a thickness of 15 μm. ), A negative electrode (43) obtained by applying a negative electrode active material (46) containing a carbon material to the surface of a core (47) made of a copper foil having a thickness of 10 μm, and an ion permeation impregnated with a nonaqueous electrolytic solution The separator (42) is made of a porous polypropylene microporous membrane, and the positive electrode (41) and the negative electrode (43) are superimposed on the separator (42) while being shifted in the width direction and wound in a spiral shape. Yes. As a result, the end of the core body (45) of the positive electrode (41) is more outward than the edge of the separator (42) at one end of both ends in the winding axis direction of the winding electrode body (4). The edge (48) protrudes, and at the other end, the end edge (48) of the core (47) of the negative electrode (43) protrudes outward from the end edge of the separator (42). Furthermore, the winding electrode body (4) has a through hole (49) in the winding shaft center portion.

  A positive electrode current collector plate (51) having a lead portion (53) is laser-welded to the edge (48) on the positive electrode (41) side of the winding electrode body (4), and the winding electrode body ( The negative electrode current collector plate (5) made of nickel is laser-welded to the edge (48) on the negative electrode (43) side of 4).

As shown in FIG. 1, the tip of the lead portion (53) of the positive electrode current collector plate (51) is welded to the surface of the aluminum plate (22) constituting the sealing plate (2). The negative electrode current collector plate (5) is welded to the bottom surface of the bottomed cylindrical body (11).
Thereby, the electric power generated by the winding electrode body (4) can be taken out from the back surface of the positive electrode terminal (24) and the bottomed cylindrical body (11).

As shown in FIGS. 1 and 3, the bottom surface of the bottomed cylindrical body (11) is formed with a convex portion (12) having a hemispherical convex surface (14) projecting toward the inside of the battery can (1). On the other hand, on the surface of the negative electrode current collector plate (5), a concave portion (56) having a hemispherical concave surface (56) tightly fitted to the convex surface (14) of the convex portion (12) of the bottomed cylindrical body (11) ( 54) is formed. As shown in FIG. 3, the back surface (55) of the concave portion (54) enters the through hole (49) of the winding electrode body (4).
The bottomed cylinder (11) has an outer diameter of 35 mm, the negative electrode current collector (5) has a diameter of 33 mm, and the bottomed cylinder (11) and the negative electrode current collector (5) have a thickness of 0.5 mm. The inner diameter of the through hole (49) of the winding electrode body (4) is 10 mm, and the outer diameter of the convex part (12) of the bottomed cylindrical body (11) and the concave part (54) of the negative electrode current collector plate (5) is 8 mm. is there.

In the conventional configuration, a large gap corresponding to the projection amount of the projection formed on the surface of the negative electrode current collector plate is formed between the surface of the negative electrode current collector plate and the bottom surface of the bottomed cylindrical body. However, according to the configuration of the present invention, the negative electrode current collector plate (5) in the state in which the concave portion (54) of the negative electrode current collector plate (5) is fitted to the convex portion (12) of the bottomed cylindrical body (11). Of the surface of 5), it is sufficient if there is a minimum gap necessary for separating the region excluding the concave surface (56) from the bottom surface of the bottomed cylindrical body (11).
Therefore, a useless space between the bottom surface of the bottomed cylindrical body (11) and the surface of the negative electrode current collector plate (5) is reduced as compared with the conventional case. This makes it possible to collect electricity efficiently with a small volume.

  When welding the negative electrode current collector plate (5) to the bottomed cylindrical body (11), as shown in FIG. 3, the winding electrode body (4) to which the negative electrode current collector plate (5) is joined is used. A cylindrical electrode rod (61) is inserted into the through hole (49) of the winding electrode body (4) while being accommodated in the body (11), and the negative electrode current collector plate (5 ) Against the bottom of the bottomed cylinder (11). On the other hand, the electrode piece (62) is brought into contact with the back surface of the bottomed cylindrical body (11) so as to face the electrode rod (61).

  Here, as shown in FIG. 4, the height L1 from the bottom surface of the bottomed cylinder (11) to the top of the convex surface (14) of the bottomed cylinder (11) is from the surface of the negative electrode current collector (5). Since it is formed slightly larger than the depth L2 to the bottom of the concave surface (56) of the negative electrode current collector plate (5), the bottomed cylindrical body (11) and the negative electrode current collector plate (5) have a concave surface (56 ) And the convex surface (14) are not in contact with each other in the region other than the fitting portion. This ensures that the concave surface (56) of the negative electrode current collector plate (5) is in close contact with the convex surface (14) of the bottomed cylindrical body (11).

  In this state, when a current is applied between the electrode rod (61) and the electrode piece (62), the fitting portion between the concave surface (56) of the negative electrode current collector plate (5) and the convex surface (14) of the bottomed cylindrical body (11). When the current flows concentratedly, heat is generated, the fitting portion is melted, and the negative electrode current collector plate (5) and the bottomed cylindrical body (11) are resistance-welded to each other. As a result, the joining area of the negative electrode current collector plate (5) and the bottomed cylindrical body (11) is larger than the conventional case where the current collector plate and the bottomed cylindrical body are welded in a point contact state. The connection resistance between the negative electrode current collector plate (5) and the bottomed cylindrical body (11) is smaller than that in the prior art.

  As another configuration, the negative electrode current collector plate (5) and the bottomed cylindrical body (11) can be laser-welded to each other. In this case, the concave surface (56) and the convex surface (14) are fitted in a state where the concave surface (56) of the negative electrode current collector plate (5) is fitted to the convex surface (14) of the bottomed cylindrical body (11). The laser beam is irradiated to the part from the back side of the bottomed cylindrical body (11). Thereby, the negative electrode current collector plate (5) and the bottomed cylindrical body (11) can be welded to each other by melting the substantially entire fitting portion.

  As a result, the joining area between the negative electrode current collector plate (5) and the bottomed cylinder (11) becomes larger than when the negative electrode current collector plate (5) and the bottomed cylinder (11) are resistance welded. . As a result, the connection resistance between the negative electrode current collector plate (5) and the bottomed cylindrical body (11) is higher than that in the case where the negative electrode current collector plate (5) and the bottomed cylindrical body (11) are resistance-welded. It becomes even smaller.

As described above, the secondary battery according to the present invention has the concave portion (54) of the negative electrode current collector plate (5) when welding the negative electrode current collector plate (5) and the bottom surface of the bottomed cylindrical body (11). By fitting into the convex portion (12) of the bottom cylindrical body (11), the concave surface (56) of the negative electrode current collector plate (5) and the convex surface (14) of the bottomed cylindrical body (11) are securely adhered. I can do it.
Therefore, the negative electrode current collector plate (5) and the bottomed cylinder (11) are fitted to the fitting portion between the concave surface (56) of the negative electrode current collector plate (5) and the convex surface (14) of the bottomed cylinder (11). As a result of being welded to each other, the joining area between the negative electrode current collector plate (5) and the bottomed cylindrical body (11) becomes larger than in the prior art. Thereby, the connection resistance between the negative electrode current collector plate (5) and the bottomed cylindrical body (11) can be reduced. As a result, the internal resistance of the battery is reduced, and high charge / discharge performance is obtained.

In order to confirm the effect of the present invention, two types of cylindrical lithium ion secondary batteries (Example and Comparative Example) were prepared by the method described later, and the resistance values of both batteries were compared.
EXAMPLE As shown in FIG. 2, a positive electrode (41) and a negative electrode (43) prepared by applying a positive electrode and a negative electrode active material (44) (46) to two cores (45) and (47), respectively, were separated into separators. (42) was sandwiched between them, and these were spirally wound to produce a wound electrode body (4).
As shown in FIG. 1, a convex portion (12) having a convex surface (14) having an outer diameter of 8 mm protruding toward the inside of the battery can (1) is formed on the bottom surface of the bottomed cylindrical body (11) serving as a negative electrode. On the other hand, on the surface of the negative electrode current collector plate (5) made of nickel to be welded to the bottom surface of the bottomed cylindrical body (11), a concave surface (56) closely contacting the convex surface (14) of the bottomed cylindrical body (11). A recess (54) having

Next, as shown in FIG. 2, a positive electrode current collector plate (51) made of aluminum is laser-welded to the edge (48) on the positive electrode side of the winding electrode body (4), and the winding electrode body (4) The negative electrode current collector plate (5) was laser welded to the negative electrode side edge (48).
Then, as shown in FIG. 3, the winding electrode body (4) welded to the positive electrode current collector plate (51) and the negative electrode current collector plate (5) is accommodated in the bottomed cylindrical body (11), and the negative electrode current collector plate is collected. The concave surface (56) of the electric plate (5) was fitted to the convex surface (14) of the bottomed cylindrical body (11), and resistance welding was applied to the fitting portion between the concave surface (56) and the convex surface (14).
Further, as shown in FIG. 1, the lead portion (53) of the positive electrode current collector plate (51) is resistance-welded to the back surface of the sealing plate (2), and the bottomed tube body (11) is opened from the opening of the bottomed tube body (11). 11) After injecting the electrolyte into the bottomed cylinder (11), the sealing plate (2) is caulked and fixed to the opening of the bottomed cylinder (11) via the insulating member (13), and the cylindrical lithium ion secondary of the embodiment A battery was produced.

Comparative Example As shown in FIG. 5, three projections (73) having an outer diameter of 2 mm projecting toward the outside of the battery can are formed on the same circumference on the surface of the negative electrode current collector plate (72) made of nickel. The comparative example was the same as the above example except that resistance welding was performed on the contact portion between the flat bottom surface of the bottomed cylindrical body (71) and each projection (73) of the negative electrode current collector plate (72). A cylindrical lithium ion secondary battery was produced.

Battery Resistance Measurement The battery resistance value at a frequency of 1 kHz in Examples and Comparative Examples was measured.
The results of resistance measurement are shown in Table 1 below.

As is clear from the measurement results, it can be seen that the lithium ion secondary battery of the example has a smaller resistance value and improved charge / discharge performance compared to the lithium ion secondary battery of the comparative example.
This is because the lithium ion secondary battery of the example in which the concave portion of the negative electrode current collector plate and the convex portion of the bottomed cylindrical body are welded is different in each projection of the negative electrode current collector plate and the bottomed cylindrical body. Compared with the lithium ion secondary battery of the comparative example which welded to the contact part with a bottom face, the junction area of a bottomed cylinder and a negative electrode current collector plate was large, and became low resistance by this.
Therefore, according to the secondary battery of the present invention, the resistance of the battery can be reduced, and high charge / discharge performance can be obtained.

In addition, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim. For example, a plurality of convex surfaces are formed on the bottom surface of the bottomed cylindrical body (11), and a plurality of concave surfaces closely contacting each convex surface of the bottomed cylindrical body (11) are formed on the surface of the negative electrode current collector plate (5). A structure in which the negative electrode current collector plate (5) and the bottomed cylindrical body (11) are welded to each other in a state where the concave surfaces of the negative electrode current collector plate (5) are in close contact with the convex surfaces of the bottomed cylindrical body (11). It is also possible to adopt.
Moreover, the shape of the convex surface (14) of the bottomed cylindrical body (11) and the concave surface (56) of the negative electrode current collector plate (5) is not limited to a hemispherical shape, and the convex surface (14) of the bottomed cylindrical body (11) and the negative electrode It is possible to adopt various shapes that allow the concave surface (56) of the current collector plate (5) to be in close contact with each other.

It is sectional drawing of the cylindrical lithium ion secondary battery of this invention. It is a partial expansion perspective view of a winding electrode body. It is sectional drawing explaining the welding process of a negative electrode current collecting plate and a bottomed cylindrical body. It is an expanded sectional view which shows the principal part of FIG. It is sectional drawing of the conventional cylindrical lithium ion secondary battery. It is sectional drawing explaining the welding process of the conventional negative electrode current collecting plate and a bottomed cylinder. It is a top view of the conventional negative electrode current collecting plate.

Explanation of symbols

(1) Battery can
(11) Bottomed cylinder
(12) Convex
(14) Convex surface
(2) Sealing plate
(4) Winding electrode body
(41) Positive electrode
(43) Negative electrode
(49) Through hole
(5) Negative current collector
(51) Positive current collector
(54) Concave
(56) Concave

Claims (5)

  A sealing plate (2) is fixed to the opening of the bottomed cylindrical body (11) via an insulating member (13) to form a battery can (1), and an electrode body (4) is formed inside the battery can (1). ) And a pair of electrodes (41) and (43) project from both ends of the electrode body (4), and one of the pair of electrodes (41) and (43) is connected to the sealing plate (2 The current collector plate (5) is joined to the edge of the other electrode, and the surface of the current collector plate (5) and the bottom surface of the bottomed cylindrical body (11) are connected to each other. In the secondary battery that is welded to each other and can take out the generated power of the electrode body (4) from the sealing plate (2) and the bottomed cylinder (11), the bottom of the bottomed cylinder (11) has a battery A convex surface (14) protruding toward the inside of the can (1) is formed, and the surface of the current collector plate (5) is fitted with the convex surface (14) of the bottomed cylindrical body (11). A secondary battery, wherein a concave surface (56) is formed, and a fitting portion between the convex surface (14) and the concave surface (56) is welded.   The concave surface (56) among the surfaces of the current collector plate (5) in a state where the concave surface (56) of the current collector plate (5) is fitted to the convex surface (14) of the bottomed cylindrical body (11). The secondary battery according to claim 1, wherein the region excluding is separated from the bottom surface of the bottomed cylindrical body (11).   The secondary according to claim 1 or 2, wherein resistance welding is applied to a fitting portion between the convex surface (14) of the bottomed cylindrical body (11) and the concave surface (56) of the current collector plate (5). battery.   The secondary according to claim 1 or 2, wherein a laser welding is applied to a fitting portion between the convex surface (14) of the bottomed cylindrical body (11) and the concave surface (56) of the current collector plate (5). battery.   Each of the electrode bodies (4) is formed by winding a separator (42) between a strip-like positive electrode (41) and a negative electrode (43) in a spiral shape, and penetrating through the winding axis. A recess (54) having the concave surface (56) is formed in the current collector plate (5) at a position facing the through hole (49) of the electrode body (4); 5. The convex portion (12) having the convex surface (14) is formed on the bottom surface of the bottomed cylindrical body (11) at a position facing the concave portion (54). Secondary battery described in 1.

Images