Electric connection structure and electric connection method of batteries

Abstract: A connection structure of battery is presented for composing a storage battery module of specified output voltage by connecting plural cells having small electric power loss between connected cells and excellent mechanical strength. This is a connection structure of battery connecting a first cell (100A) and a second cell (100B) in series by using a connection member (1). Each one of the first cell and second cell has (a) a metal outer member in a container shape (11) as the negative electrode installing plural function element members inside, and (b) a metal electrode member (10) installed at one end, being electrically insulated from the outer member, including a first flat portion as the positive electrode. The connection member (1) has a side wall (4) capable of fitting the outer member inside, and a second flat portion (5) orthogonal to the side wall. A first projection (2) for welding to the electrode member is installed on the second flat portion. A second projection (3) for welding to the outer member is installed on an inside surface of the wall. The first projection of the electrode member abuts against the first surface of the first cell and is welded and joined. The side wall of the connection member is fitted to the outside of the outer member of the first cell, and the second projection of the connection member abuts against the surface of the outer member of the second cell, and is welded and joined.

Description: Technical Field The present invention relates to a battery, and more particularly to a connection structure of storage battery module for obtaining a specified output voltage by connecting plural cells in series. Background of the Invention A connector for connecting cells is used for forming a storage battery module for obtaining a specified output voltage by connecting cells in series. Fig. 4 is a sectional view showing a connection constitution of cells in a prior art. Fig. 5 (a) and Fig. 5 (b) are plan view and side view showing a constitution of a connector in a prior art. In Fig. 4, a first cell A and a second cell B respectively have a metal casing 111 formed cylindrically, and a metal electrode 110 installed at one end electrically insulated from the metal casing 111. The metal electrode 110 serves also as positive electrode, and the metal casing 111, as negative electrode. A bump 114 is set in the center of the metal electrode 110, and a rubber valve 116 is placed in the bump 114 for discharging the gas generated in the cell. By connecting the metal electrode 110 of the first cell A and the metal casing 111 of the second cell B, the first cell A and second cell B are connected in series. This series connection is achieved by welding a connector 115 to the metal electrode 110 and metal casing 111. As shown in Fig. 5, the connector 115 is formed in a circular disk in two-step depth, and an opening 17 is formed in the center of the connector 115 in order to evade the bump 114 of the metal electrode 110. The outer surface of a flat portion 118 of the connector 115 is welded to the metal electrode 110 of the first cell A, and the inner surface of a tubular portion 119 is welded to the metal casing 111 of the second cell B. In this way, plural cells are connected in series, and coupled mechanically, so that a battery module of specified output voltage is composed. In this conventional constitution, welding of the connector 115 and metal electrode 110 is done by spot welding by feeding welding current between the flat portion 118 of the connector 115 and the meal electrode 110. In this case, one welding electrode is fitted to the flat portion 118, and other is fitted to the bump 114 of the metal electrode 110. In ordinary spot welding, welding current is passed by pressing two weld zones between the welding electrodes, and pressed portions are fused and welded. In the connection battery of the prior art, however, since there is no pressing part, most current flows between the welding electrodes as the surface current of the connector 115 and metal electrode 110. Accordingly, when the connector 115 made of material having a thick material pressure or small specific resistance is used, welding is difficult. This state causes a similar problem when the tubular portion 119 is welded to the metal casing 111. That is, in the conventional constitution, when the connector 115 made of material having a thick material pressure or small specific resistance is used, the electric resistance of electric connection between cells becomes large, and hence the loss increases in the connection between cells where a large current flows. Moreover, the mechanical strength of the connector 115 is also weak and low in the welding strength, and therefore the strength of mechanical coupling between the cells is also low. Still worse, since a welding current flows in the recess 114, the rubber valve 116 placed inside of the bump 114 may deteriorate due to heat generation. Summary of the Invention A connection structure of battery of the invention has a constitution of connecting a first cell and a second cell in series by using a connection member. Each one of the first cell and the second cell has: (a) a metal outer member in a container shape installing plural function element members inside, serving as an electrode having one pole, and (b) a metal electrode member installed at one end, being electrically insulated from the outer member, including a first flat portion serving as an electrode having other pole. The connection member has a side wall capable of fitting the outer member inside, and a second flat portion orthogonal to the side wall. A first projection for welding to the electrode member is installed on the second flat portion, a second projection for welding to the outer member is installed on an inside surface of the wall. The second flat portion of the connection member is opposite to the first flat portion of the first cell, the first projection of the electrode member abuts against the first flat portion of the first cell and is welded and joined. The side wall of the connection member is fitted to the outside of the outer member of the first cell, and the second projection of the connection member abuts against the surface of the outer member of the second cell, and is welded and joined. Preferably, the outer member has a cylindrical shape, the connection member has a cylindrical portion that can be fitted to the outside of the outer member of the cylindrical shape, and the side surface is a side wall of the cylindrical portion. Preferably, the first projection installed on the connection member is composed of plural first projections, and each one of the plural first projections is installed on one circle of the second flat portion. Preferably, the second projection installed on the connection member is composed of plural second projections, and each one of the plural second projections is installed on one circle centered on the center of the connection member. The invention also relates to a connection method of battery by connecting plural cells in series by using plural connection members. Each one of the plural cells has: (a) a metal outer member in a container shape installing plural function element members inside, serving as an electrode having one pole, and (b) a metal electrode member installed at one end, being electrically insulated from the outer member, including a first flat portion serving as an electrode having other pole. Each one of the plural connection members has a side wall capable of fitting the outer member inside, and a second flat portion orthogonal to the side wall. A first projection for welding to the electrode member is installed on the second flat portion. A second projection for welding to the outer member is installed on an inside surface of the wall. This method comprises: (1) a step of installing the second flat portion of the each connection member opposite to the first flat portion of the each cell, so that the first projection of the electrode member abuts against the first flat portion of the each cell, (2) a step of welding a first contact portion of the first projection and the first flat portion, by applying a current between the connection member and the first flat portion of the each cell, (3) a step of fitting the inside of the side wall of the connection member to the outside of the outer member of the each cell, so that the second projection of the connection member abuts against the surface of the outer member of the each cell, and (4) a step of welding a second contact portion of the second projection and the outer member, by applying a current between the connection member and the outer member of the each cell. In this constitution, since the flat portion of the connector is welded to the metal electrode of the first cell, and the outer wall of the connector is welded to the casing of the second cell, any material can be used for the connector, regardless of the plate thickness or specific gravity, and the welding strength can be increased, too. Moreover, since the welding positions of the metal electrode and metal casing located on same plural radii, and the current route by connection is the shortest distance. Therefore, a connection structure of cells having an electric connection of small connection resistance and coupling of high mechanical strength is realized. Brief Description of the Drawings Fig. 1 is a sectional view showing a constitution of connection structure of battery according to an embodiment of the invention; Fig. 2 (a), Fig. 2 (b), and Fig. 2 (c) are plan view, side view, and perspective view showing the constitution of the connector used in the connection structure of battery according to an embodiment of the invention; Fig. 3 is a perspective view showing a state of composing a storage battery module by coupling and connecting a plurality of cells in a connection structure of battery according to an embodiment of the invention; Fig. 4 is a sectional view showing a constitution of connection structure of a conventional battery. Fig. 5 (a) and Fig. 5 (b) are plan view and side view showing a constitution of the connector used in the connection structure of a conventional battery. Reference Numerals 1 Connection member 2 Plural first projections 3 Plural second projections 4 Cylindrical portion (side wall) 5 Flat portion 6 Slit 7 Notch 8 Storage battery module 10 Metal electrode 11 Metal casing 14 Bump of metal electrode 16 Rubber valve 100A First cell 100B Second cell 100C Third cell 100D Fourth cell 100E Fifth cell 100F Sixth cell Description of the Preferred Embodiment Referring now to the drawings, a connection structure of battery in an embodiment of the invention is described below. The following embodiment is only an example of carrying out the invention, and is not intended to limit the technical scope of the invention. A sectional view showing a constitution of connection of battery in an embodiment of the invention is shown in Fig. 1. Plan view, side view, and perspective view of the connector used in the connection structure of the battery shown in Fig. 1 are given in Fig. 2 (a), Fig. 2 (b) and Fig. 2 (c). In Fig. 1, a first cell 100A and a second cell 100B are in a circular cylinder of the same type and same standard. Each one of the cells 100A and 100B has a cylindrical metal casing 11, and a metal electrode 10 installed at one end electrically insulated from the metal casing 11. The metal electrode 10 serves also as the positive electrode, and the metal casing 11, as the negative electrode. A bump 14 is formed in the center of the metal electrode 10, and a rubber valve 16 for discharging the gas generated in the cells is installed inside of the bump 14. The metal electrode 10 of the first cell 100A and the metal casing 11 of the second cell 100B are connected by using a connection member 1. Thus, the first cell 100A and second cell 100B are connected in series. In Fig. 2 (a), Fig. 2 (b) and Fig. 2 (c), the connection member 1 has a cylindrical portion 4, and a flat portion 5 installed at one end of the cylindrical portion 4. That is, the connection member 1 has a side wall 4, and a flat portion 5 orthogonal to the side wall. Plural second projections 3 are installed on the inner circumference of the cylindrical portion 4. Each one of the plural second projections 3 is installed on one circumference, and project toward the central direction of the cylindrical portion 4. Plural first projections 2 are installed on the outer surface of the flat portion 5. Each one of the plural first projections 2 is installed on one circumference. The conductor member is formed of conductive and weldable metal. At the inside of the cylindrical portion 4 of the connection member 1, the second cell 100B is installed, the plural second projections 3 formed on the cylindrical portion 4 abut against the outer surface of the metal casing 11 of the second cell 100B, and the second projections 3 and metal casing 11 compose a second contact portion. At the outer side of the flat portion 5 of the connection member 1, the first cell 100A is installed, the plural first projections 2 formed on the flat portion 5 abut against the outer surface of the metal electrode 10 of the first cell 100A, and the first projections 2 and metal electrode 10 compose a first contact portion. A slit 6 is formed in the cylindrical portion4. A notch 7 is formed in the flat portion 5. This notch 7 has a function of decreasing the reactive current when welding the connection member 1 and metal electrode 10. By this notch 7, the heat generation efficiency of the first contact portion is enhanced, so that welding may be done efficiently. The slit 6 formed in the connection member 1 functions to give an elastic force for pressing the cylindrical portion 4 of the connection member 1 in the direction of the metal casing 11 when the cylindrical portion 4 is fitted to the metal casing 11. By the elastic force of the connection member 1, the contact force between the plural second projections 3 formed in the connection member 1 and the metal casing 11 of the second cell 100B is increased. As a result, the heat generation efficiency of the second contact portion is enhanced, so that welding may be done efficiently. Thus, the connection structure of first cell 100A and second cell 100B is composed. A connection method of the first cell 100 A and second cell 100B is described below. First, the outer surface of the flat portion 5 of the connection member 1 is welded to the metal electrode 10 of the first cell 100A. That is, the flat portion 5 is put on the metal electrode 10, and while pressing the flat portion 5 to the metal electrode 10 side, a welding current is applied between the connection member 1 and metal electrode 10. At four positions of the plural firsts projections 2, the connection member 1 is welded to the metal electrode 10. That is, the plural first projections 2 formed on the flat portion 5 and the metal electrode 10 contact with each other. In this state of contact, when a current is applied between the connection member 1 and metal electrode 10, heat is generated in the contact portion of the plural first projections 2 and metal electrode 10, and by this heat generation, each one of the plural first projections 2 and metal electrode 10 are welded at the same time. In succession, the inside of the cylindrical portion 4 of the connection member 1 welded to the metal electrode 10 of the first cell 100A is fitted to the metal casing 11 of the second cell 100B. At this time, the metal casing 11 and plural second projections 3 contact with each other. In this state of contact, when a welding current is applied between the metal casing 11 and the connection member 1, the connection member 1 and metal casing 11 are welded at the same time at four positions of the plural second projections 3. In this way, the first cell 100 A and second cell 100B are connected in series by the connection member 1. By repeating such connection of cells, for example, a storage battery module 8 by series connection of third cell 100C, fourth cell 100D, fifth cell 100E, and sixth cell 100F as shown in Fig. 3 is obtained. Since the plural second projections 2 and plural second projections 3 formed on the connection member 1 are formed on the same radius, the current route is the shortest distance when the first cell 100A and second cell 100B are connected. Accordingly, the electric power loss due to specific resistance of the material for composing the connection member 1 may be suppressed to a minimum. This electric power loss can be lowered also by increasing the plate thickness of the connection member 1. For example, according to the measurement, the resistance in the contact portion of the first projections 2 and metal electrode 10, or the contact portion of the second projections 3 and metal casing 11 was R = 0.0681 mΩ at the plate thickness of t = 0.18 mm, R = 0.0409 mΩ at t = 0.30, and R = 0.0306 mΩ at t = 0.40mm. Thus, by increasing the plate thickness of the connection member 1, it is possible to lower the specific resistance R of the contact portion, and therefore the storage battery module 8 having a small electric power loss is obtained. Still more, since the connector having a sufficient thickness can be used, the mechanical strength of the weld zone and coupling strength of cells are enhanced. As described herein, the constitution of the invention brings about the following effects. (1) Since the connection member having a sufficient thickness can be used, a battery module of small electric power loss is obtained. (2) Since the current route by connection is short, the connection resistance is small, and hence a battery module of small electric power loss can be obtained. Besides, the effect of specific resistance of the connection member on the electric power loss is decreased. (3) Since the connection member having a sufficient thickness can be used, the mechanical strength between connected cells is enhanced, so that a battery module hardly destroyed by external force can be obtained.

Claims: A connection structure of battery connecting a first cell and a second cell in series by a connection member, each of said first cell and said second cell being comprised (a) a metal outer member in a container shape locating plural function element members inside, serving as an electrode having one pole, and (b) a metal electrode member located at one end, being electrically located from said outer member, including a first flat portion serving as an electrode having other pole, wherein said connection member has a side wall capable of fitting said outer member inside, and a second flat portion orthogonal to said side wall, a first projection for welding to said electrode member is located on said second flat portion, a second projection for welding to said outer member is located on an inside surface of said wall, said second flat portion of said connection member is opposite to said first flat portion of said first cell, and said first projection of said electrode member abuts against said first flat portion of said first cell and is welded and joined, and an inside of said side wall of said connection member is fitted to an outside of said outer member of said first cell, and said second projection of said connection member abuts against a surface of said outer member of said second cell, and is welded and joined. A connection structure of battery of claim 1, wherein said outer member has a cylindrical shape, said connection member has a cylindrical portion that can be fitted to the outside of said outer member of said cylindrical shape, and said wall is a side wall of said cylindrical portion. A connection structure of battery of claim 1, wherein said first projection located on said connection member is composed of plural first projections, and each one of said plural first projections is located on one circle of said second flat portion. A connection structure of battery of claim 1, wherein said second projection located on said connection member is composed of plural second projections, and each one of said plural second projections is located on one circle centered on a center of said connection member. A connection structure of battery of claim 1, wherein said connection member has a notch formed on said second flat portion. A connection structure of battery of claim 1, wherein said connection member has a slit formed on said side wall. A connection structure of battery of claim 1, further comprising plural cells connected to said second cell by plural connection members, wherein each one of said plural cells has a same constitution as said second cell, each on of said plural connection members has a same contitution as said connection member, said second flat portion of said each connection member is opposite to said first flat portion of said each cell, said first projection of said electrode member abuts against said first surface of said each cell, and is welded and joined, an inside of said side wall of said each connection member is fitted to an outside of said outer member of said each cell, and said second projection of said each connection member abuts against a surface of said outer member of said each cell, and is welded and joined, whereby said plural cells are connected in series by said plural connection members. A connection structure of battery of claim 7, wherein said outer member has a cylindrical shape, said each connection member has a cylindrical portion that can be fitted to the outside of said outer member of said cylindrical shape, and said wall is a side wall of said cylindrical portion. A connection structure of battery of claim 7, wherein said first projection located on said each connection member is composed of plural first projections, each one of said plural first projections is located on one circle of said second flat portion, said second projection located on said each connection member is composed of plural second projections, and each one of said plural second projections is located on one circle centered on a center of said connection member. A connection structure of battery of claim 7, wherein said connection member has a notch formed on said second flat portion, and a slit formed on said side wall. A connection method of battery connecting a first cell and a second cell in series by using a connection member, each of said first cell and said second cell being comprised : (a) a metal outer member in a container shape locating plural function element members inside, serving as an electrode having one pole, and (b) a metal electrode member located at one end, being electrically located from said outer member, including a first flat portion serving as an electrode having other pole, said connection member being had a side wall capable of fitting said outer member inside, and a second flat portion orthogonal to said side wall, a first projection for welding to said electrode member being located on said second flat portion, a second projection for welding to said outer member being located on an inside surface of said wall, said method comprising the steps of: (1) locating said second flat portion of said connection member opposite to said first flat portion of said first cell, so that said first projection of said electrode member abuts against said first flat portion of said first cell, (2) welding a first contact portion of said first projection and said first flat portion, by applying a current between said connection member and said first flat portion of said first cell, (3) fitting an inside of said side wall of said connection member to an outside of said outer member of said first cell, so that said second projection of said connection member abuts against a surface of said outer member of said second cell, and (4) welding a second contact portion of said second projection and said outer member, by applying a current between said connection member and said outer member of said first cell. A connection method of battery of claim 11, wherein said outer member has a cylindrical shape, said connection member has a cylindrical portion that can be fitted to the outside of said outer member of said cylindrical shape, and said wall is a side wall of said cylindrical portion. A connection method of battery of claim 11, wherein said first projection located on said connection member is composed of plural first projections, each one of said plural first projections is located on one circle of said second flat portion, and when a current is applied between said connection member and said first flat portion of said first cell, said first contact portion of each of said plural first projections and said first flat portion is generated heat and welded simultaneously. A connection method of battery of claim 11, wherein said second projection located on said connection member is composed of plural second projections, each one of said plural second projections is located on one circle centered on a center of said connection member, and when a current is applied between said connection member and said outer member of said first cell, each one of second contact portion of each one of said plural second projections and said outer member is generated heat and welded simultaneously. A connection method of battery of claim 11, wherein said connection member has a notch formed on said second flat portion, and when a current is applied between said connection member and said first flat portion of said first cell, unavailable current of said current flowing in said first contact portion decreases by said notch, a heat generation efficiency of said first contact portion is increased, and welding may be done efficiently. A connection method of battery of claim 11, wherein said connection member has a slit formed on said side wall, and by this slit, a contact force in said second contact portion between said side wall of said connection member and said outer member of said first cell is increased, and when a current is applied between said connection member and said outer member, unavailable current of said current flowing in said second contact portion decreases, and a heat generation efficiency of said second contact portion is increased, and welding may be done efficiently. A connection method of battery of claim 1, further comprising: (5) a step of connecting plural cells connected to said second cell by plural connection members, wherein each one of said plural cells has a same constitution as said second cell, each one of said plural connection member has a same constitution as said connection member, and the step (5) executes the step (1) through the step (4) repeatedly. A connection method of battery of claim 17, wherein said outer member has a cylindrical shape, said each connection member has a cylindrical portion that may be fitted to the outside of said outer member of said cylindrical shape, and said wall is a side wall of said cylindrical portion. A connection method of battery of claim 17, wherein said first projection located on said each connection member is composed of plural first projections, each one of said plural first projections is located on one circle of said second flat portion, and when a current is applied between said connection member and said first flat portion of said each cell, said first contact portion of each of said plural first projections and said first flat portion is generated heat and welded simultaneously, said second projection located on said each connection member is composed of plural second projections, each one of said plural second projections is located on one circle centered on a center of said each connection member, and when a current is applied between said each connection member and said outer member of said each cell, said second contact portion of each of said plural second projections and said outer member is generated heat and welded simultaneously.

Inventors: IKOMA MUNEHISA, MARUKAWA SHUHEI, YOSHII FUMIHIKO, IKOMA, MUNEHISA, MARUKAWA, SHUHEI, YOSHII, FUMIHIKO
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1997
Main classification: H01M2
IPC codes: H01M2