Patent Description:
Conventionally, there has been a battery pack (one form of which is a battery module) that is, for example, mounted in a vehicle such as an electric vehicle and used as a power source for driving a vehicle motor. The battery pack is configured by stacking unit cells (batteries) using spacers (battery holder). Electrode tabs of the different unit cells are electrically interconnected by means of a bus bar (refer to Patent Document <NUM>.

<CIT> aims to provide an electric power storage device including positive electrodes 41A, 41B and negative electrodes 42A, 42B with separators disposed there-between and a plurality of capacitor cells 4A, 4B arranged alternately.

<CIT> aims to provide a battery module <NUM> made up of a plurality of cartridges <NUM> that support a plurality of battery cells <NUM>.

<CIT> aims to provide a battery module <NUM> including a plurality of thin batteries <NUM> and a plate assembly <NUM> made up of terminal-equipped plates <NUM> and guide plates <NUM>.

When the bus bar and the electrode tabs of the unit cell are laser-welded in a state in which the unit cell is attached to the spacer, a portion of the spacer that is heated by laser light may evaporate and generate gas. If gas mixes into a welded portion between the bus bar and the electrode tabs of the unit cell, there is the risk of decreasing the mechanical strength of the welded portion and increasing the electrical resistance.

An object of the present invention is to provide a spacer, a battery pack, and a method for manufacturing a battery pack with which it is possible to prevent the increase in electrical resistance and the reduction in the mechanical strength at the welded portion between the bus bar and the electrode tabs of the unit cell.

An insulating spacer which achieves the object described above is used in a battery pack, obtained by electrically interconnecting unit cells, which are stacked one atop another, by means of a bus bar along the stacking direction of the unit cells, each of which has a cell body including a power-generating element formed in a flat shape and an electrode tab extending out from the cell body with a distal end portion bent along the thickness direction of the cell body; and is provided between each of the unit cells. The spacer has an abutting portion, a recessed portion, and a communicating portion. The abutting portion abuts the distal end portion of the electrode tab along the stacking direction of the unit cells. The recessed portion is recessed in a direction intersecting with the stacking direction of the unit cells so as to be separated from the distal end portion of the electrode tab. The communicating portion communicates an inner side of the recessed portion with an outside of the recessed portion.

The battery pack which achieves the object described above comprises a plurality of unit cells that are stacked one atop another, a plurality of spacers, and a bus bar. The unit cell comprises a cell body including a power-generating element formed in a flat shape and an electrode tab extending out from the cell body with a distal end portion bent along a thickness direction of the cell body. The spacer has an insulating property and comprises an abutting portion that abuts the distal end portion of the electrode tab along the stacking direction of the unit cells, a recessed portion that is recessed in a direction intersecting with the stacking direction of the unit cells so as to be separated from the distal end portion of the electrode tab, and a communicating portion that communicates an inner side of the recessed portion with outside of the recessed portion. The bus bar electrically interconnects the distal end portions of the electrode tabs of the different unit cells.

A method for manufacturing the battery pack which achieves the object described above comprises arranging the spacer described above between a plurality of unit cells each including a cell body having a power-generating element formed in a flat shape, and an electrode tab extending out from the cell body with a distal end portion bent along a thickness direction of the cell body. Furthermore, the bus bar that electrically interconnects the distal end portions of the electrode tabs of the different unit cells is brought into contact with the distal end portion of each of the electrode tabs. Furthermore, laser light for welding is irradiated on the bus bar correspond to positions of recessed portions of the spacer in order to weld the bus bar and the distal end portions of the unit cell.

The first to third embodiments of the present invention will be described below with reference to the appended drawings. In the drawings, the same members have been assigned the same reference symbols and redundant explanations have been omitted. In the drawings, the sizes and proportions of the members have been exaggerated for ease of understanding the first to third embodiments and may differ from the actual sizes and proportions.

The orientation of a battery pack <NUM> is shown using arrows indicated by X, Y, and Z in each of the drawings. The direction of the arrow indicated by X is the longitudinal direction of the battery pack <NUM>. The direction of the arrow indicated by Y is the transverse direction of the battery pack <NUM>. The direction of the arrow indicated by Z is the stacking direction of the battery pack <NUM>.

<FIG> is a perspective view illustrating the battery pack <NUM> according to an embodiment. <FIG> is a perspective view illustrating a state in which a portion of a bus bar unit <NUM> (a protective cover <NUM>, an anode side terminal <NUM>, and a cathode side terminal <NUM>) as well as a pressurizing unit <NUM> (an upper pressure plate <NUM>, a lower pressure plate <NUM>, and left and right side plates <NUM>) are removed from the battery pack <NUM> shown in <FIG>. <FIG> is a perspective view illustrating a cross section of a main part of a state in which a bus bar <NUM> is joined to electrode tabs <NUM> of stacked unit cells <NUM>. <FIG> is an end surface view illustrating <FIG> from the side. <FIG> is a perspective view illustrating a state in which a bus bar holder <NUM> and the bus bars <NUM> are removed from a stacked body <NUM> illustrated in <FIG>. <FIG> is a perspective view illustrating a state in which a first cell sub-assembly <NUM> and a second cell sub-assembly 110N shown in <FIG> are electrically connected by means of the bus bars <NUM>. <FIG> is a perspective view illustrating a state in which the first cell sub-assembly <NUM> (three sets of unit cells <NUM> that are connected in parallel) shown in <FIG> is disassembled for each unit cell <NUM>, and a first spacer <NUM> and a second spacer <NUM> are removed from one (the uppermost) unit cell <NUM> thereof. <FIG> is a perspective view illustrating a portion of the unit cell <NUM> and a portion of the first spacer <NUM>. <FIG> is a perspective view illustrating a portion of the first spacer <NUM>. <FIG> is a schematic view illustrating one state in which the bus bar <NUM> abuts a distal end portion 112d of the unit cell <NUM> disposed in the first spacer <NUM>, and the distal end portion 112d of the unit cell <NUM> and the bus bar <NUM> are laser-welded. <FIG> is a schematic view illustrating another state in which the bus bar <NUM> abuts the distal end portion 112d of the unit cell <NUM> disposed in the first spacer <NUM>, and the distal end portion 112d of the unit cell <NUM> and the bus bar <NUM> are laser-welded.

With reference to <FIG> and <FIG>, in general, the spacer (first spacer <NUM>) according to an embodiment is used in the battery pack <NUM> including unit cells <NUM> stacked on each other and electrically connected by a bus bar <NUM> along a stacking direction (Z direction) of the unit cells <NUM>, with each of the unit cells <NUM> having a cell body <NUM>, including a power-generating element <NUM> that is formed in a flat shape, and an electrode tab <NUM> that extends out from the cell body <NUM> with a distal end portion 112d bent along the thickness direction of the cell body <NUM>; and is provided between each of the unit cells <NUM>. The first spacer <NUM> has an abutting portion <NUM>, a recessed portion 114i, and a communicating portion 114j. The abutting portion <NUM> abuts the distal end portion 112d of the electrode tab <NUM> along the stacking direction of the unit cells <NUM>. The recessed portion 114i is recessed in a direction intersecting the stacking direction of the unit cells <NUM> so as to be separated from the distal end portion 112d of the electrode tab <NUM>. The communicating portion 114j allows an inner side of the recessed portion 114i to communicate with the outside of the recessed portion 114i.

With reference to <FIG> and <FIG>, in general, the battery pack <NUM> according to the embodiment comprises the plurality of unit cells <NUM> stacked one atop another, the plurality of spacers (first spacers <NUM>), and the bus bar <NUM>. The unit cell <NUM> comprises the cell body <NUM>, which includes the power-generating element <NUM> formed in a flat shape, and the electrode tab <NUM> that extends out from the cell body <NUM> with distal end portions 112d bent along the thickness direction of the cell body <NUM>. The first spacer <NUM> comprises the abutting portion <NUM> that abuts against the distal end portion 112d of the electrode tab <NUM> along the stacking direction (Z direction) of the unit cells <NUM>, the recessed portion 114i that is recessed in a direction intersecting the stacking direction of the unit cells <NUM> so as to be separated from the distal end portion 112d of the electrode tab <NUM>, and the communicating portion 114j that allows the inner side of the recessed portion 114i to communicate with the outside of the recessed portion 114i. The bus bar <NUM> electrically interconnects the distal end portions 112d of the electrode tabs <NUM> of the various unit cells <NUM>.

With reference to <FIG>, <FIG>, in general, a method for manufacturing the battery pack <NUM> according to the embodiment comprises arranging the spacer (first spacer <NUM>) described above between each of the unit cells <NUM>, each of which has the cell body <NUM>, which includes the power-generating element <NUM> and is formed in a flat shape, and the electrode tab <NUM>, which extends out from the cell body <NUM> and whose distal end portion 112d is bent along the thickness direction of the cell body <NUM>. Furthermore, the bus bar <NUM> that electrically interconnects the distal end portions 112d of the electrode tabs <NUM> of the various unit cells <NUM> is brought into contact with the distal end portion 112d of each of the electrode tabs <NUM>. Furthermore, laser light L for welding is irradiated on the bus bar <NUM> so as to correspond to the position of the recessed portion 114i of the first spacer <NUM> in order to weld the bus bar <NUM> and the distal end portion 112d of the unit cell <NUM>.

A plurality of the battery packs <NUM> are mounted in a vehicle such as an electric vehicle and can be charged with electric power from an outdoor charging station or the like, and are used as a power source for driving a vehicle motor. The battery pack <NUM> is configured by electrically connecting a stacked body <NUM>, obtained by stacking a plurality of the unit cells <NUM> by means of a bus bar unit <NUM>, in a state of pressurization by means of a pressurizing unit <NUM>. Each configuration of the battery pack <NUM>, including the spacer (first spacer <NUM>), will be described below.

The configuration of the stacked body <NUM> will be described in detail.

As shown in <FIG>, the stacked body <NUM> is configured by alternately connecting in series a first cell sub-assembly <NUM> composed of three of the unit cells <NUM> that are electrically connected in parallel, and a second cell sub-assembly 110N composed of three of the unit cells <NUM> that are electrically connected in parallel.

As shown in <FIG>, the first cell sub-assembly <NUM> corresponds to the three unit cells <NUM> that are positioned in the first row (lowermost row), the third row, the fifth row, and the seventh row (uppermost row) of the battery pack <NUM>. As shown in <FIG>, the second cell sub-assembly 110N corresponds to the three unit cells <NUM> that are positioned in the second row, the fourth row, and the sixth row of the battery pack <NUM>.

The first cell sub-assembly <NUM> and the second cell sub-assembly 110N are similarly configured. However, the first cell sub-assembly <NUM> and the second cell sub-assembly 110N are arranged such that three anode side electrode tabs 112A and three cathode side electrode tabs <NUM> are alternately positioned along the Z direction by interchanging the tops and bottoms of the three unit cells <NUM>, as shown in <FIG> and <FIG>.

As shown in <FIG> and <FIG>, in the first cell sub-assembly <NUM>, all of the anode side electrode tabs 112A are positioned on the right side of the drawing, and all of the cathode side electrode tabs <NUM> are positioned on the left side of the drawing.

As shown in <FIG> and <FIG>, in the second cell sub-assembly 110N, all of the anode-side electrode tabs 112A are positioned on the left side of the drawing, and all of the cathode-side electrode tabs <NUM> are positioned on the right side of the drawing. If the tops and bottoms are simply interchanged every three of the unit cells <NUM>, the orientations of the distal end portions 112d of the electrode tabs <NUM> will vary vertically in the Z direction. Therefore, each of the distal end portions 112d is bent downwards, so that the orientations of all of the distal end portions 112d of the electrode tabs <NUM> of the unit cells <NUM> are aligned.

The unit cell <NUM> corresponds to a lithium-ion secondary battery, for example. A plurality of the unit cells <NUM> are connected in series in order to satisfy the drive voltage specification of the vehicle motor. A plurality of the unit cells <NUM> are connected in parallel in order to ensure the battery capacity and to extend the travel distance of the vehicle.

As shown in <FIG>, the unit cell <NUM> includes the cell body <NUM>, which includes the power-generating element <NUM> that carries out charging and discharging and is formed into a flat shape, the electrode tab <NUM> that extends out from the cell body <NUM> and whose distal end portion 112d is bent along the thickness direction of the cell body <NUM>, and a laminate film <NUM> for sealing the power-generating element <NUM>.

The power-generating element <NUM> is formed by stacking a plurality of sets of anodes and cathodes that are separated by separators, and functions as a chargeable and dischargeable electrical storage body via the electrode tab <NUM>.

As shown in <FIG>, and <FIG>, the electrode tab <NUM> is for exposing the power-generating element <NUM> to the outside. The electrode tab <NUM> is composed of the anode side electrode tab 112A and the cathode side electrode tab <NUM>. The proximal end side of the anode side electrode tab 112A is joined to all of the anodes included in one of the power-generating element <NUM>. The anode side electrode tab 112A has the form of a thin plate and is made of aluminum in accordance with the characteristics of the anode. The proximal end side of the cathode side electrode tab <NUM> is joined to all of the cathodes included in one of the power-generating elements <NUM>. The cathode side electrode tab <NUM> has the form of a thin plate and is made of copper in accordance with the characteristics of the cathode.

As shown in <FIG> and <FIG>, the electrode tab <NUM> has the form of an L. A proximal end portion 112c of the electrode tab <NUM> is supported from below by a support portion <NUM> of the first spacer <NUM>. The distal end portion 112d of the electrode tab <NUM> is bent downward in the Z direction and faces the abutting portion <NUM> of the first spacer <NUM>.

As shown in <FIG>, the electrode tab <NUM> has a hole 112e in a central portion 112f along the width direction (Y direction). The hole 112e is formed in an elongated shape from the proximal end portion 112c to the distal end portion 112d of the electrode tab <NUM>. The boss 114r of the first spacer <NUM> is inserted into the hole 112e of the electrode tab <NUM>.

As shown in <FIG>, the laminate film <NUM> is configured in pairs and is for sandwiching and sealing the cell body <NUM> from above and below along the Z direction. In the pair of laminate films <NUM>, the anode side electrode tab 112A and the cathode side electrode tab <NUM> extend out to the outside from gaps between one end portions 113a thereof along the Y direction. The laminate film <NUM> includes a sheet-like metal layer and a sheet-like insulating layer that covers and insulates the metal layer from both sides.

The unit cells <NUM> are stacked, as shown in <FIG>, and <FIG>, in a state of support by means of a pair of spacers (first spacer <NUM> and second spacer <NUM>), as shown in <FIG>.

The pair of spacers (first spacer <NUM> and second spacer <NUM>) are used to arrange the unit cells <NUM> at constant intervals along the Z direction, as shown in <FIG>, <FIG>. The first spacer <NUM> supports the side of the unit cell <NUM> provided with the electrode tab <NUM>. The second spacer <NUM> supports the unit cell <NUM> on the side not provided with the electrode tab <NUM>, so as to oppose the first spacer <NUM> in the X direction of the unit cell <NUM>.

As shown in <FIG>, the first spacer <NUM> is made from reinforced plastic having an insulating property. The first spacer <NUM> comprises the abutting portion <NUM> that abuts the distal end portion 112d of the electrode tab <NUM> along the stacking direction of the unit cells <NUM>, the recessed portion 114i that is recessed in a direction intersecting the stacking direction of the unit cells <NUM> so as to be separated from the distal end portion 112d of the electrode tab <NUM>, and the communicating portion 114j that allows the inner side of the recessed portion 114i to communicate with the outside of the recessed portion 114i. Furthermore, as shown in <FIG>, the first spacer <NUM> has the support portion <NUM> that is adjacent to the recessed portion 114i and that supports the electrode tab <NUM> from below in the Z direction along the directions (X direction and Y direction) intersecting the stacking direction (Z direction) of the unit cells <NUM>.

As shown in <FIG>, the abutting portion <NUM> of the first spacer <NUM> abut both end portions (one end portion <NUM> and other end portion <NUM>) of the distal end portion 112d of the electrode tab <NUM> along the width direction (Y direction). The abutting portion <NUM> has a side surface <NUM> along the Y direction and the Z direction of the first spacer <NUM>. The abutting portion <NUM> supports (from the back) the one end portion <NUM> and the other end portion <NUM> of the electrode tab <NUM> along the X direction. That is, as shown in <FIG>, the abutting portion <NUM> abuts the distal end portion 112d of the electrode tab <NUM> and positions the distal end portion 112d of the electrode tab <NUM> along the X direction.

As shown in <FIG>, the abutting portion <NUM> of the first spacer <NUM> abuts the distal end portion 112d of the electrode tab <NUM> of the unit cell <NUM>. On the other hand, as shown in <FIG>, there is a gap corresponding to the communicating portion 114j between the side surface <NUM> of the first spacer <NUM> and the electrode tab <NUM> of the unit cell <NUM> in a region without the abutting portion <NUM>.

As shown in <FIG>, the recessed portion 114i of the first spacer <NUM> is provided in a region extending from a position of the abutting portion <NUM> to a position corresponding to the welded portion between the distal end portion 112d of the electrode tab <NUM> and the bus bar <NUM> along the width direction (Y direction) of the electrode tab <NUM>. The recessed portion 114i is provided on the side surface <NUM> of the first spacer <NUM> so as to vertically divide the two abutting portions <NUM> along the horizontal direction (Y direction).

As shown in <FIG>, the communicating portion 114j of the first spacer <NUM> is formed by notching a portion adjacent to the abutting portion <NUM> so as to be separated from the distal end portion 112d of the electrode tab <NUM>. The communicating portion 114j corresponds to an elongated gap positioned between each of the abutting portions <NUM>.

As shown in <FIG>, the support portion <NUM> of the first spacer <NUM> is provided in an elongated shape along the width direction (Y direction) of the electrode tab <NUM>. The support portion <NUM> is provided on a flat supporting surface 114b that is provided on the upper surface of the first spacer <NUM> along the Y direction. That is, the support portion <NUM> is formed on the supporting surface 114b along a linear outer edge facing the abutting portion <NUM>, projecting upward from the supporting surface 114b in a rectangular shape.

Here, the first spacer <NUM> largely suppresses the contact area with the electrode tab <NUM> at the side surface <NUM> formed by the Z direction and the Y direction by means of the recessed portion 114i and the communicating portion 114j.

As shown in <FIG>, the first spacer <NUM> has a convex boss 114r projecting from the support portion <NUM>. The boss 114r also projects into the recessed portion 114i positioned below the support portion <NUM> in the Z direction. The boss 114r is inserted into the hole 112e that is opened in the central portion 112f of the electrode tab <NUM> in order to regulate the position of the electrode tab <NUM>. The boss 114r is swaged and fixed to a peripheral portion of the hole 112e of the electrode tab <NUM>. The swaging of the boss 114r is carried out by heating and pressing the boss 114r to deform the boss into a hemispherical shape.

As shown in <FIG> and <FIG>, the first spacer <NUM> has a pair of connecting pins 114c that respectively project upward at both ends of the supporting surface 114b along the Y direction. The pair of connecting pins 114c are cylindrical in form and are inserted into connecting holes 113c formed at both ends of the one end portion 113a of the laminate film <NUM> along the Y direction, thereby positioning the unit cell <NUM>.

In a plurality of the first spacers <NUM>, an upper surface 114a of one first spacer <NUM> and a lower surface 114d of another first spacer <NUM> are in contact, as shown in <FIG>. The plurality of first spacers <NUM> are positioned relative to each other by fitting a cylindrical positioning pin 114e that projects from the upper surface 114a of one first spacer <NUM> into a positioning hole 114f that opens onto the lower surface 114d of another first spacer <NUM>, as also shown in <FIG>.

As shown in <FIG>, the first spacer <NUM> is provided with locating holes <NUM> at both ends along the Y direction. Bolts for connecting and positioning a plurality of the battery packs <NUM> with respect to each other along the Z direction are inserted in the locating holes <NUM>.

Since it is not necessary for the second spacer to support the electrode tab <NUM>, the second spacer <NUM> is configured by simplifying the first spacer <NUM>. As shown in <FIG>, similarly to the first spacer <NUM>, the second spacer <NUM> includes positioning pins 115e for positioning the second spacers relative to each other, connecting pins 115c for positioning the unit cell <NUM>, and locating holes <NUM>, into which bolts for interconnecting and positioning a plurality of the battery packs <NUM> relative to each other are inserted.

The configuration of the pressurizing unit <NUM> will be described in detail.

The pressurizing unit <NUM> includes the upper pressure plate <NUM> and the lower pressure plate <NUM>, which pressurize the power-generating element <NUM> of each of the unit cells <NUM> of the unit cells <NUM> of the stacked body <NUM> from above and below, and a pair of side plates <NUM> that fix the upper pressure plate <NUM> and the lower pressure plate <NUM> in a state of pressurization of the stacked body <NUM>.

As shown in <FIG> and <FIG>, the upper pressure plate <NUM>, together with the lower pressure plate <NUM>, hold and sandwich the plurality of the unit cells <NUM> that constitute the stacked body <NUM> from above and below and pressurize the power-generating element <NUM> of each of the unit cells <NUM>. The upper pressure plate <NUM> has the form of a plate with recesses and protrusions and is made from a metal possessing sufficient rigidity. The upper pressure plate <NUM> is provided on a horizontal plane. The upper pressure plate <NUM> has a pressurizing surface 121a that pressurizes the power-generating element <NUM> downwards, as illustrated in <FIG>. The pressurizing surface 121a is formed flat, protruding downward from a central portion of the upper pressure plate <NUM>. The upper pressure plate <NUM> has locating holes 121b into which bolts for interconnecting the battery packs <NUM> are inserted. The locating holes 121b are through-holes and formed at the four corners of the upper pressure plate <NUM>.

As shown in <FIG>, the lower pressure plate <NUM> has the same shape as the upper pressure plate <NUM> and is provided so that the top and bottom of the upper pressure plate <NUM> is reversed. Like the upper pressure plate <NUM>, the lower pressure plate <NUM> includes a pressurizing surface 122a that pressurizes the power-generating element <NUM> upwards, and locating holes 122b, into which bolts for connecting and positioning the battery packs <NUM> relative to each other along the Z direction are inserted.

As shown in <FIG> and <FIG>, the pair of side plates <NUM> are for fixing the upper pressure plate <NUM> and the lower pressure plate <NUM> in a state of pressurization of the stacked body <NUM>. That is, the pair of side plates <NUM> hold the interval between the upper pressure plate <NUM> and the lower pressure plate <NUM> constant. In addition, the pair of side plates <NUM> cover and protect the side surfaces of the stacked unit cells <NUM> along the X direction. The side plate <NUM> has the form of a flat plate and is made of metal. The pair of side plates <NUM> stand upright so as to face both side surfaces of the stacked unit cells <NUM> along the X direction. The pair of side plates <NUM> are welded to the upper pressure plate <NUM> and the lower pressure plate <NUM>.

The configuration of the bus bar unit <NUM> will be described in detail.

The bus bar unit <NUM> includes the bus bar holder <NUM> that integrally holds a plurality of the bus bars <NUM>, the bus bars <NUM> that electrically interconnect the distal end portions 112d of the electrode tabs <NUM> of the different unit cells <NUM> (vertically adjacent unit cells <NUM>), an anode side terminal <NUM> that causes the anode side terminal ends of the plurality of the electrically connected unit cells <NUM> to oppose an external input/output terminal, a cathode side terminal <NUM> that causes the cathode side terminal ends of the plurality of the electrically connected unit cells <NUM> to oppose an external input/output terminal, and a protective cover <NUM> for protecting the bus bars <NUM>, and the like.

As shown in <FIG> and <FIG>, the bus bar holder <NUM> is for integrally holding a plurality of the bus bars <NUM>. The bus bar holder <NUM> integrally holds the plurality of the bus bars <NUM> in a matrix so as to oppose the electrode tab <NUM> of each of the unit cells <NUM> of the stacked body <NUM>. The bus bar holder <NUM> is made of resin having insulating properties and has the form of a frame.

As shown in <FIG>, the bus bar holder <NUM> is respectively provided with a pair of columnar support portions 131a that stand upright along the Z direction, so as to be positioned on both sides of the longitudinal direction of the first spacers <NUM> that support the electrode tabs <NUM> of the unit cells <NUM>. The pair of columnar support portions 131a are fitted to the side surfaces of the first spacers <NUM>. The pair of columnar support portions 131a have the form of an L when viewed along the Z direction and have the form of a plate that extends in the Z direction. The bus bar holder <NUM> is provided with an auxiliary columnar support portion 131b to stand upright along the Z direction so as to be positioned in the vicinity of the center of the first spacer <NUM> in the longitudinal direction. The auxiliary columnar support portion 131b has the form of a U in a cross section along the XY plane extending in the Z direction.

As shown in <FIG>, the bus bar holder <NUM> includes insulating portions 131c that respectively protrude between adjacent bus bars <NUM> in the Z direction. The insulating portions 131c have the form of a plate that extends in the Y direction. Each of the insulating portions 131c is provided horizontally between the columnar support portion 131a and the auxiliary columnar support portion 131b. The insulating portion 131c prevents discharge by insulating the space between bus bars <NUM> that are adjacent to each other along the Z direction.

The bus bar holder <NUM> may be configured by joining together the columnar support portions 131a, the auxiliary columnar support portions 131b, and the insulating portions 131c, which are independently formed, or may be configured by integrally molding the columnar support portions 131a, the auxiliary columnar support portions 131b, and the insulating portions 131c.

As shown in <FIG>, <FIG> and <FIG>, the bus bars <NUM> are for electrically interconnecting the electrode tabs <NUM> of the vertically adjacent unit cells <NUM>. The bus bars <NUM> electrically connect the anode side electrode tab 112A of one unit cell <NUM> and the cathode side electrode tab <NUM> of another unit cell <NUM>. For example, the bus bars <NUM> connect three vertically arranged anode side electrode tabs 112A of the first cell sub-assembly <NUM> and three vertically arranged cathode side electrode tabs <NUM> of the second cell sub-assembly 110N, as illustrated in <FIG>.

That is, for example, the bus bars <NUM> connect the three anode side electrode tabs 112A of the first cell sub-assembly <NUM> in parallel and connect the three cathode side electrode tabs <NUM> of the second cell sub-assembly 110N in parallel, as shown in <FIG>. Moreover, the bus bars <NUM> connect the three anode side electrode tabs 112A of the first cell sub-assembly <NUM> and the three cathode side electrode tabs <NUM> of the second cell sub-assembly 110N in series. The bus bars <NUM> are laser-welded to the anode side electrode tab 112A of one unit cell <NUM> and the cathode side electrode tab <NUM> of another unit cell <NUM>.

As shown in <FIG> and <FIG>, the bus bar <NUM> is formed by joining the anode side bus bar 132A and the cathode side bus bar <NUM>. The anode side bus bar 132A and the cathode side bus bar <NUM> have the same shape, each having the form of an L. The bus bar <NUM> is integrally formed by a joint portion 132c, which is formed by joining one bent end of the anode side bus bar 132A to one bent end of the cathode side bus bar <NUM>, as illustrated in <FIG> and <FIG>. The anode side bus bar 132A and the cathode side bus bar <NUM>, which constitute the bus bar <NUM>, are provided with side portions 132d that are joined to the bus bar holder <NUM> at both ends in the Y direction, as illustrated in <FIG>.

The anode side bus bar 132A is made of aluminum in the same manner as the anode side electrode tab 112A of the unit cell <NUM>. The cathode side bus bar <NUM> is made of copper, in the same manner as the cathode side electrode tab <NUM> of the unit cell <NUM>. The anode side bus bar 132A and the cathode side bus bar <NUM>, which are made from different metals, are joined to each other by means of ultrasonic bonding to form the joint portion 132c.

Of the bus bars <NUM> arranged in the form of a matrix, the bus bar <NUM> positioned on the upper right in the drawing in <FIG> corresponds to the anode side terminal ends of <NUM> unit cells <NUM> (<NUM> parallel <NUM> series) and is composed of only the anode side bus bar 132A. This anode side bus bar 132A is laser-welded to the anode side electrode tabs 112A of the three uppermost unit cells <NUM> of the stacked unit cells <NUM>.

Of the bus bars <NUM> arranged in the form of a matrix, the bus bar <NUM> positioned on the lower left in the drawing in <FIG> corresponds to the cathode side terminal ends of <NUM> unit cells <NUM> (<NUM> parallel <NUM> series) and is composed of only the cathode side bus bar <NUM>. The cathode side bus bar <NUM> is laser-welded to the cathode side electrode tabs <NUM> of the three lowermost unit cells <NUM> of the stacked unit cells <NUM>.

As shown in <FIG> and <FIG>, the anode side terminal <NUM> causes the anode side terminal ends of the plurality of the electrically connected unit cells <NUM> to oppose an external input/output terminal. The anode side terminal <NUM> is joined to the anode side bus bar 132A positioned on the upper right in the drawing, from among the bus bars <NUM> arranged in a matrix, as illustrated in <FIG>. The anode side terminal <NUM> has the form of a plate, both ends of which are bent, and is made from a conductive metal.

As shown in <FIG> and <FIG>, the cathode side terminal <NUM> causes the cathode side terminal ends of the plurality of the electrically connected unit cells <NUM> to oppose an external input/output terminal. The cathode side terminal <NUM> is joined to the cathode side bus bar <NUM> positioned on the lower left in the drawing, from among the bus bars <NUM> arranged in a matrix, as illustrated in <FIG>. The cathode side terminal <NUM> has the shape of the anode side terminal <NUM>, with the top and bottom inverted.

As shown in <FIG> and <FIG>, the protective cover <NUM> is for protecting the bus bars <NUM> and the like. That is, the protective cover <NUM> integrally covers the plurality of the bus bars <NUM> to thereby prevent each of the bus bars <NUM> from coming into contact with other members, etc., to cause electrical short-circuiting. The protective cover <NUM> is made from a plastic having an insulating property, where one end 135b and the other end 135c of a side surface 135a standing upright along the Z direction are bent claw-like in the X direction, as illustrated in <FIG>.

The protective cover <NUM> covers each of the bus bars <NUM> with the side surface 135a, while sandwiching and fixing the bus bar holder <NUM> from above and below with the one end 135b and the other end 135c. The protective cover <NUM> has a first opening 135d, which is a rectangular hole for exposing the anode side terminal <NUM> to the outside, and a second opening 135e, which is a rectangular hole for exposing the cathode side terminal <NUM> to the outside on the side surface 135a.

In regard to the method of manufacturing the battery pack <NUM>, a method for welding the bus bar <NUM> and the electrode tab <NUM> of the unit cell <NUM> will now be described with reference to <FIG>.

The first spacer <NUM> is disposed between each of the unit cells <NUM>. Next, the bus bar <NUM> is brought into contact with the distal end portion 112d of each of the electrode tabs <NUM>. As shown in <FIG>, the abutting portion <NUM> of the first spacer <NUM> supports (from the back) the bus bar <NUM> and the distal end portion 112d of the electrode tab <NUM>. Next, as shown in <FIG>, in order to weld the bus bar <NUM> and the distal end portion 112d of the unit cell <NUM>, laser light L for welding is irradiated on the bus bar <NUM> so as to correspond to the position of the recessed portion 114i of the first spacer <NUM>. Here, as shown in <FIG>, gas, generated from the interior of the recessed portion 114i of the first spacer <NUM> due to heat from the bus bar <NUM> irradiated with the laser light L, is discharged to the outside of the recessed portion 114i via the communicating portion 114j (gap between the electrode tab <NUM> of the unit cell <NUM> and the side surface <NUM> of the first spacer <NUM>).

The action and effects of the above-described first embodiment will be described.

The first spacer <NUM> has an insulating property, is used in the battery pack <NUM>, obtained by electrically interconnecting the unit cells <NUM>, which are stacked one atop another, by means of the bus bar <NUM> along the stacking direction of the unit cells <NUM>, each of which has the cell body <NUM>, which includes the power-generating element <NUM> and is formed in a flat shape, and the electrode tab <NUM>, which extends out from the cell body <NUM> and whose distal end portion 112d is bent along the thickness direction of the cell body <NUM>; and is provided between each of the unit cells <NUM>. The first spacer <NUM> has the abutting portion <NUM>, the recessed portion 114i, and the communicating portion 114j. The abutting portion <NUM> abuts the distal end portion 112d of the electrode tab <NUM> along the stacking direction of the unit cells <NUM>. The recessed portion 114i is recessed in a direction intersecting the stacking direction of the unit cells <NUM> so as to be separated from the distal end portion 112d of the electrode tab <NUM>. The communicating portion 114j allows an inner side of the recessed portion 114i to communicate with the outside of the recessed portion 114i.

The battery pack <NUM> comprises a plurality of the unit cell <NUM> stacked one atop another, a plurality of the first spacers <NUM>, and the bus bar <NUM>. The unit cell <NUM> comprises the cell body <NUM>, which includes the power-generating element <NUM> formed in a flat shape, and the electrode tab <NUM> that extends out from the cell body <NUM> with a distal end portion 112d bent along the thickness direction of the cell body <NUM>. The first spacer <NUM> comprises the abutting portion <NUM> that abuts the distal end portion 112d of the electrode tab <NUM> along the stacking direction of the unit cells <NUM>, the recessed portion 114i that is recessed in a direction intersecting the stacking direction of the unit cells <NUM> so as to be separated from the distal end portion 112d of the electrode tab <NUM>, and the communicating portion 114j that allows the inner side of the recessed portion 114i to communicate with the outside of the recessed portion 114i. The bus bar <NUM> electrically interconnects the distal end portions 112d of the electrode tabs <NUM> of the different unit cells <NUM>.

The method for manufacturing the battery pack <NUM> comprises arranging the first spacer <NUM> described above between each of the unit cells <NUM>, each of which has the cell body <NUM>, which includes the power-generating element <NUM> formed in a flat shape, and the electrode tab <NUM> that extends out from the cell body <NUM> with a distal end portion 112d bent along the thickness direction of the cell body <NUM>. Furthermore, the bus bar <NUM> that electrically interconnects the distal end portions 112d of the electrode tabs <NUM> of the different unit cells <NUM> is brought into contact with the distal end portion 112d of each of the electrode tabs <NUM>. Furthermore, in order to weld the bus bar <NUM> and the distal end portion 112d of the unit cell <NUM>, laser light L for welding is irradiated on the bus bar <NUM> so as to correspond to the position of the recessed portion 114i of the first spacer <NUM>.

By means of the first spacer <NUM>, the battery pack <NUM>, and the method of manufacturing the battery pack <NUM>, when the laser light L for welding is irradiated on the bus bar <NUM> so as to correspond to the position of the recessed portion 114i of the first spacer <NUM>, the abutting portion <NUM> of the first spacer <NUM> is heated via the electrode tab <NUM> of the unit cell <NUM> and the bus bar <NUM>. By coming into contact with the distal end portion 112d of the electrode tab <NUM> from the opposite side of the irradiation direction of the laser light L, the abutting portion <NUM> of the first spacer <NUM> supports (from the back) the bus bar <NUM> and the distal end portion 112d of the electrode tab <NUM> such that the bus bar <NUM> and the distal end portion 112d of the electrode tab <NUM> come into close contact with each other, facilitating welding. Here, the gas, generated from the interior of the recessed portion 114i due to the heating of the first spacer <NUM>, is discharged to the outside of the recessed portion 114i via the communicating portion 114j. The gas is formed due to the vaporization from heating of the first spacer <NUM>, and if the gas were to enter the welded portion between the bus bar <NUM> and the electrode tabs <NUM> of the unit cell <NUM>, the mechanical strength of the welded portion would be reduced and the electrical resistance would increase. Thus, by means of the first spacer <NUM>, the battery pack <NUM>, and the method of manufacturing the battery pack <NUM>, it is possible to prevent a reduction of the mechanical strength at the welded portion between the bus bar <NUM> and the electrode tab <NUM> of the unit cell <NUM> as well as to prevent an increase in the electrical resistance.

The abutting portion <NUM> of the first spacer <NUM> preferably abuts both end portions (one end portion <NUM> and other end portion <NUM>) of the distal end portion 112d of the electrode tab <NUM> along the width direction (Y direction).

By means of the first spacer <NUM>, it is possible to support (from the back) both end portions (one end portion <NUM> and the other end portion <NUM>) of the distal end portion 112d of the electrode tab <NUM> with the abutting portion <NUM> of the first spacer <NUM>. Thus, by means of the first spacer <NUM>, it is possible to prevent a reduction of the mechanical strength at the welded portion as well as to prevent an increase in the electrical resistance, while providing sufficient weld strength between of the bus bar <NUM> and the electrode tab <NUM> of the unit cell <NUM>.

In addition, by means of the first spacer <NUM>, by bringing the two end portions (left and right) of the electrode tab <NUM> into contact with the first spacer along the width direction (Y direction), compared to a case of bringing the two end portions (above and below) into contact with the first spacer along the direction (Z direction) intersecting the width direction (Y direction) of the electrode tab <NUM>, it is possible to suppress the thickness along the Z direction. Accordingly, by means of the first spacer <NUM>, when the battery pack <NUM> is configured by stacking a plurality of the first spacers <NUM> along the Z direction, it is possible to maintain the stacking efficiency thereof.

In addition, by means of the first spacer <NUM>, if the two end portions (one end portion <NUM> and the other end portion <NUM>) of the electrode tab <NUM> adjacent to the bus bar <NUM> are supported (from the back) by means of the abutting portion <NUM> of the first spacer <NUM> while pressing the bus bar <NUM> toward the side of the first spacer <NUM>, it is possible to cause the peripheral portion separated from the two end portions (one end portion <NUM> and the other end portion <NUM>) of the electrode tab <NUM> to also come into contact with the bus bar <NUM>. In particular, in a case in which the distal end portion 112d of the electrode tab <NUM> is distorted, it is possible to pressurize the two end portions (one end portion <NUM> and the other end portion <NUM>) of the distal end portion 112d of the electrode tab <NUM> by means of the abutting portion <NUM> of the first spacer <NUM> to correct the distortion. Accordingly, by means of the first spacer <NUM>, it is possible to prevent a reduction of the mechanical strength at the welded portion as well as to prevent an increase in the electrical resistance, while providing sufficient weld strength between the bus bar <NUM> and the electrode tab <NUM> of the unit cell <NUM>.

The recessed portion 114i of the first spacer <NUM> is preferably provided in a region extending from the position of the abutting portion <NUM> to the position corresponding to the welded portion between the distal end portion 112d of the electrode tab <NUM> and the bus bar <NUM> along the width direction (Y direction) of the electrode tab <NUM>.

By means of the first spacer <NUM>, since the recessed portion 114i is provided in the region of the abutting portion <NUM> while the distal end portion 112d of the electrode tab <NUM> is supported (from the back) by the abutting portion <NUM>, it is possible to minimize contact with the distal end portion 112d of the electrode tab <NUM>. That is, by means of the recessed portion 114i, it is possible to sufficiently suppress the gas that is generated due to the heating of the abutting portion <NUM> of the first spacer <NUM> via the distal end portion 112d of the electrode tab <NUM>. Accordingly, by means of the first spacer <NUM>, it is possible to prevent a reduction of the mechanical strength at the welded portion as well as to prevent an increase in the electrical resistance, while providing sufficient weld strength between the bus bar <NUM> and the electrode tab <NUM> of the unit cell <NUM>.

The communicating portion 114j of the first spacer <NUM> is preferably formed by notching a portion adjacent to the abutting portion <NUM> so as to be separated from the distal end portion 112d of the electrode tab <NUM>.

By means of the first spacer <NUM>, it is possible to provide the communicating portion 114j with an extremely simple structure. By providing the communicating portion 114j, the first spacer <NUM> would not increase in size, become troublesome to manufacture, or be subject to increased manufacturing costs.

<FIG> is a perspective view illustrating a portion of a first spacer <NUM> of a modified example of the first embodiment.

The first spacer <NUM> according to the modified example of the first embodiment is different from the first spacer <NUM> of the first embodiment described above in that the abutting portion <NUM> thereof also abuts, in addition to the two ends (one end portion <NUM> and the other end portion <NUM>) of the electrode tab <NUM>, a central portion 112f separated from the two ends. The abutting portion <NUM> of the first spacer <NUM> of the first embodiment described above abuts only the two ends (one end portion <NUM> and the other end portion <NUM>) of the electrode tab <NUM>.

As shown in <FIG>, there are a total of five abutting portions <NUM> of the first spacer <NUM> aligned along the Y direction of a side surface <NUM> at a set interval, one each at positions opposing the one end portion <NUM> and the other end portion <NUM> of the electrode tab <NUM>, one at a position opposing the central portion 112f of the electrode tab <NUM>, and one each at an intermediate position between the one end portion <NUM> and the central portion 112f of the electrode tab and an intermediate position between the other end portion <NUM> and the central portion 112f of the electrode tab. The plurality of the abutting portions <NUM> may all be formed in the same shape, or those positioned in the middle or both ends of the side surface <NUM> may be formed elongated in the Y direction.

The action and effects of the above-described modified example of the first embodiment will be described.

The first spacer <NUM> abuts, at the abutting portions <NUM> thereof, portions (such as the central portion 112f) separated from the two ends (one end portion <NUM> and the other end portion <NUM>) along the width direction (Y direction) of the distal end portion 112d of the electrode tab <NUM>.

By means of the first spacer <NUM>, it is possible to support (from the back) the portions (such as the central portion 112f) separated from the two ends of the distal end portion 112d of the electrode tab <NUM> with the abutting portions <NUM>. Accordingly, by means of the first spacer <NUM>, it is possible to prevent a reduction of the mechanical strength at the welded portion as well as to prevent an increase in the electrical resistance, while providing sufficient weld strength between the bus bar <NUM> and the electrode tab <NUM> of the unit cell <NUM>.

Additionally, by means of the first spacer <NUM>, if the portions (for example, the central portion 112f) separated from the two ends of the electrode tab <NUM> adjacent to the bus bar <NUM> are supported (from the back) by means of the abutting portion <NUM> of the first spacer <NUM> while pressing the bus bar <NUM> toward the side of the first spacer <NUM>, it is possible to cause the peripheral portion of, for example, the central portion 112f of the electrode tab <NUM> to also come in contact with the bus bar <NUM>. Such a configuration is effective if the overall length of the first spacer <NUM> in the width direction (Y direction) of the electrode tab <NUM> is sufficiently long relative to the overall length in the Z direction. In particular, in a case in which the distal end portion 112d of the electrode tab <NUM> is distorted, it is possible to pressurize the central portion 112f of the distal end portion 112d of the electrode tab <NUM> by means of the abutting portion <NUM> of the first spacer <NUM> to correct the distortion. Accordingly, by means of the first spacer <NUM>, it is possible to prevent a reduction of the mechanical strength at the welded portion as well as to prevent an increase in the electrical resistance, while providing sufficient weld strength between the bus bar <NUM> and the electrode tab <NUM> of the unit cell <NUM>.

<FIG> is a perspective view illustrating a portion (one side along the Y direction) of the first spacer <NUM> of a second embodiment. <FIG> is a side view illustrating a portion of the unit cell <NUM> and the first spacer <NUM> in a cross section of the first spacer <NUM> of <FIG> along 12A-12A. <FIG> is a side view illustrating a portion of the unit cell <NUM> and the first spacer <NUM> in a cross section of the first spacer <NUM> of <FIG> indicated by 12B-12B.

The first spacer <NUM> of the second embodiment differs from the first spacer <NUM> of the first embodiment described above in that the first spacer is intermittently provided with support portions <NUM> which support the electrode tab <NUM> from below along the width direction (Y direction) of the electrode tab <NUM>. The first spacer <NUM> of the first embodiment described above is provided with the support portion <NUM> that supports the electrode tab <NUM> from below with an elongated shape along the width direction (Y direction) of the electrode tab <NUM>.

As shown in <FIG>, the first spacer <NUM> is provided with supporting portions <NUM>, which project in a rectangular shape from a flat supporting surface 314b upward along the Z direction. One of the supporting portions <NUM> is provided at the center of the supporting surface 314b, and each of the supporting portions is provided at the two ends of the supporting surface 314b along the Y direction. The supporting portion <NUM> at the center of the supporting surface 314b has a protruding boss 314r. The supporting portions <NUM> support the central portion 112f of the electrode tab <NUM>, the one end portion <NUM> thereof, and the other end portion <NUM> thereof along the width direction (Y direction). As shown in <FIG>, the first spacer <NUM> supports the proximal end portion 112c of the electrode tab <NUM> of the unit cell <NUM> from below by means of the supporting portions <NUM>. On the other hand, as shown in <FIG>, there are gaps between the supporting surface 314b and the electrode tab <NUM> of the unit cell <NUM> in regions where there are no supporting portions <NUM>.

Here, the first spacer <NUM> greatly suppresses the contact area with the electrode tab <NUM> at the side surface <NUM> formed by the Z direction and the Y direction by means of a recessed portion 314i and a communicating portion 314j. Furthermore, the first spacer <NUM> greatly suppresses the contact area with the electrode tab <NUM> at the upper surface formed by the X direction and the Y direction by means of the intermittently provided supporting portions <NUM>.

The action and effects of the above-described second embodiment will be described.

The first spacer <NUM> has the support portions <NUM> that are adjacent to the recessed portion 314i and that partially support the electrode tab <NUM> along the direction (X direction and Y direction) intersecting the stacking direction (Z direction) of the unit cells <NUM>.

By means of the first spacer <NUM>, it is possible to directly discharge the gas, which is generated in the interior of the recessed portion 314i due to the presence of heat, to outside of the recessed portion 314i via the communicating portion 314j, and to discharge the gas from the communicating portion 314j to outside of the recessed portion 314i via the air around the supporting portion <NUM> (for example, the gap between the supporting portion <NUM> and the supporting portion <NUM>, which are adjacent to each other and separated along the Y direction). Accordingly, by means of the first spacer <NUM>, the battery pack provided with the first spacer <NUM>, and the method of manufacturing the battery pack provided with the first spacer <NUM>, it is possible to prevent a reduction of the mechanical strength at the welded portion between the bus bar <NUM> and the electrode tab <NUM> of the unit cell <NUM> as well as to sufficiently prevent an increase in the electrical resistance.

<FIG> is a perspective view illustrating a portion (one side along the Y direction) of the first spacer <NUM> of a third embodiment.

A first spacer <NUM> of the third embodiment differs from the first spacer <NUM> of the first embodiment described above in that communicating portions 414j that allow the inner side of a recessed portion 414i to communicate with the outside of the recessed portion 414i are configured by piercing portions so as to be separated from the abutting portion <NUM> along the stacking direction (Z direction) of the unit cells <NUM> to the recessed portion 414i. In the first spacer <NUM> of the first embodiment described above, the communicating portion 114j is formed by notching a portion adjacent to the abutting portion <NUM> so as to be separated from the distal end portion 112d of the electrode tab <NUM>.

The communicating portions 414j are constituted by cylindrical through-holes that penetrate the supporting portion <NUM> in the Z direction. The communicating portions 414j penetrate the recessed portion 414i positioned below the supporting portion <NUM> in the Z direction. The communicating portions 414j are separated from the abutting portion <NUM> that forms a side surface of the first spacer <NUM>. A plurality of the communicating portions 414j are provided in the supporting portion <NUM> at prescribed intervals along the Y direction.

The action and effects of the above-described third embodiment will be described.

In the first spacer <NUM>, the communicating portions 414j are configured by piercing portions so as to be separated from the abutting portion <NUM> along the stacking direction (Z direction) of the unit cells <NUM> to the recessed portion 414i.

Claim 1:
An insulating spacer (<NUM>) configured to be used in a battery pack (<NUM>) including unit cells (<NUM>) stacked on each other and electrically connected by a bus bar (<NUM>) along a stacking direction of the unit cells, and each of the unit cells having a cell body (<NUM>) including a power-generating element (<NUM>) formed in a flat shape and an electrode tab (<NUM>) extending out from the cell body with a distal end portion (112d) of the electrode tab being bent along a thickness direction of the cell body, the insulating spacer being configured to be provided between each of the unit cells, and the insulating spacer comprising:
an abutting portion (<NUM>) arranged and configured to abut the distal end portion of the electrode tab from a direction intersecting the stacking direction of the unit cells;
a side surface (<NUM>) arranged to face the distal end portion of the electrode tab in the direction intersecting the stacking direction of the unit cells; and
a recessed portion (114i) formed in the side surface, the recessed portion arranged to be recessed in the direction intersecting the stacking direction of the unit cells so as to be separated from the distal end portion of the electrode tab;
characterized in that the insulating spacer further comprises a communicating portion (114j) that includes a gap between the side surface and the electrode tab and communicates an inside of the recessed portion with an outside of the recessed portion when the abutting portion is abutted against the distal end portion of the electrode tab.