Patent Description:
In a battery module in which a plurality of battery cells are connected, electrical connection between the battery cells is generally performed by welding electrode leads of the battery cells, which are to be electrically connected with each other, to one bus bar.

The laser welding, which is one of the methods of connecting the electrode lead and the bus bar, is performed in a state where the electrode lead is pressed toward the bus bar by using a welding jig capable of closely adhering the electrode lead and the bus bar of the battery cell, in order to improve the welding quality.

<FIG> shows a conventional battery module. In the conventional battery module as shown in <FIG>, after the electrode lead and the bus bar are pressed using a pressing jig, namely after the electrode lead <NUM> is pressed using the pressing jig to be closely adhered to the bus bar <NUM> disposed below the electrode lead, welding is performed. In such a model, a pressing jig having a size and shape suitable for the corresponding model is required.

This means that the pressing jig for closely adhering the electrode lead and the bus bar should be prepared to have a different design suitable for battery modules having different sizes and shapes.

In addition, the model in which the electrode lead and the bus bar should be welded using the pressing jig has limitations in terms of space and structure since a minimum space for placing the jig should be secured around a welding portion in order to apply the pressing jig for welding.

Accordingly, there is a demand for development of a battery module structure that allows easy welding without preparing different welding jigs for different battery module models regardless of the above limitations in terms of space and structure.

<CIT> relates to a secondary battery and battery module having the same. The secondary battery is formed in the shape of a plate and has an electrode assembly mounted in a battery case made of a laminated sheet including a metal layer and a resin layer, wherein the secondary battery is constructed in a structure in which independent coupling type frame members are mounted to the outside part of a sheathing member serving as the battery case, and a medium- or large-sized battery module including the same as a unit cell.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to securing easy welding without preparing a dedicated welding jig for different battery modules since the bus bar frame may serve as the welding jig.

In one aspect of the present invention, there is provided a unit module as defined in claim <NUM>, comprising: a pouch-type battery cell having an electrode assembly, a cell case for accommodating the electrode assembly, and an electrode lead connected to the electrode assembly and drawn out of the cell case; a bus bar attached to the electrode lead; and a bus bar frame attached to a terrace portion of the battery cell to accommodate at least a portion of the electrode lead and the bus bar therein, the bus bar frame pressing the electrode lead and the bus bar so that the electrode lead and the bus bar are closely adhered to each other, the bus bar frame having a welding slit formed at a location corresponding to the bus bar and the electrode lead so that a contact portion of the bus bar and the electrode lead is exposed out.

The bus bar includes: a bonding portion extending in a direction parallel to the electrode lead to contact the electrode lead and located at an inner side of the bus bar frame; an exposed portion bent from the bonding portion to extend in a direction perpendicular to the bonding portion and drawn out of the bus bar frame; and a hook portion extending from an end of the bonding portion in a direction parallel to the exposed portion.

The bus bar frame may include: a hook accommodation groove extending from the welding slit; and a hook fixing portion formed on an inner wall of the hook accommodation groove.

The bus bar frame may include a bus bar placing portion having a size and shape corresponding to the exposed portion of the bus bar and formed concavely on an outer surface of the bus bar frame so that the exposed portion is placed thereon.

The bus bar frame may have a damage-preventing groove formed on the placing portion to a predetermined depth so that the bus bar and the bus bar frame are partially not in contact to prevent the bus bar frame from being damaged due to heat caused by welding.

In another aspect of the present invention, there is provided a unit module as defined in claim <NUM>, comprising: a pouch-type battery cell having an electrode assembly, a cell case for accommodating the electrode assembly, and an electrode lead connected to the electrode assembly and drawn out of the cell case; a bus bar attached to the electrode lead; and a bus bar frame attached to a terrace portion of the battery cell to accommodate at least a portion of the electrode lead and the bus bar therein, the bus bar frame pressing the electrode lead and the bus bar so that the electrode lead and the bus bar are closely adhered to each other, the bus bar frame having a welding slit formed at a location corresponding to the bus bar and the electrode lead so that a contact portion of the bus bar and the electrode lead is exposed out.

The bus bar frame includes: a first unit frame configured to cover at least a portion of an upper surface of the terrace portion; and a second unit frame configured to cover at least a portion of a lower surface of the terrace portion and coupled to the first unit frame.

In the bus bar frame, the first unit frame and the second unit frame are shaped to be point-symmetric to each other.

In another aspect of the present invention, there is also provided a battery module as defined in claim <NUM>, comprising: a unit module stack formed by connecting a plurality of unit modules according to an embodiment of the present disclosure as described above; and a connector configured to connect bus bars of neighboring unit modules.

Meanwhile, in another aspect of the present invention, there is also provided a battery pack as defined in claim <NUM>, which is implemented by connecting a plurality of battery modules according to an embodiment of the present invention as described above, and in another aspect of the present invention, there is also provided a vehicle as defined in claim <NUM>, comprising the battery pack according to an embodiment of the present invention.

According to an embodiment of the present disclosure, since the bus bar frame may serve as a welding jig, welding may be easily performed without preparing a dedicated welding jig for different battery modules.

Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the disclosure, so it should be understood that other equivalents and modifications could be made thereto within the scope of the appended claims.

First, an overall configuration of a battery module according to an embodiment of the present disclosure will be described with reference to <FIG>.

<FIG> is a perspective view showing a portion of a battery module according to an embodiment of the present disclosure, and <FIG> is a front showing a portion of the battery module according to an embodiment of the present disclosure. Also, <FIG> is a diagram showing a unit module stack applied to the battery module according to an embodiment of the present disclosure, and <FIG> is an exploded perspective view showing a unit module applied to the battery module according to an embodiment of the present disclosure.

Referring to <FIG> and <FIG>, a battery module according to an embodiment of the present disclosure includes a unit module stack <NUM>, a connector <NUM>, and an external terminal <NUM>.

Referring to <FIG> and <FIG>, the unit module stack <NUM> is a stack implemented by stacking a plurality of unit modules <NUM>. Each unit module <NUM> includes a battery cell <NUM>, a bus bar <NUM> connected to an electrode lead <NUM> of the battery cell <NUM>, and a bus bar frame <NUM> attached to a terrace portion T of the battery cell <NUM>. The unit module stacks <NUM> are stacked such that broad surfaces of neighboring battery cells <NUM> face each other, thereby forming one unit module stack <NUM>.

The connector <NUM> is a component adapted to electrically connect neighboring unit module stacks <NUM>, and the connector <NUM> connects bus bars <NUM> provided in the neighboring unit module stacks <NUM> to each other.

The external terminal <NUM> contacts the bus bar <NUM> provided to the unit module <NUM> disposed at the outermost side among the plurality of unit modules <NUM> of the unit module stack <NUM> and functions as a terminal for electrical connection with an external electronic device.

Next, the battery cell <NUM> of the unit module <NUM> according to an embodiment of the present disclosure will be described in detail with reference to <FIG> and <FIG>.

<FIG> is an exploded perspective view showing a unit module applied to the battery module according to an embodiment of the present disclosure, and <FIG> is a perspective view showing a battery cell applied to the battery module according to an embodiment of the present disclosure.

Referring to <FIG> and <FIG>, a pouch-type battery cell is used as the battery cell <NUM>. The battery cell <NUM> may include an electrode assembly (not shown), a cell case <NUM>, and an electrode lead <NUM>.

Although not shown in the figures, the electrode assembly is configured so that separators are interposed between positive electrode plates and negative electrode plates alternately stacked repeatedly, and separators are preferably disposed at both outermost sides thereof for insulation.

The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer coated on one or both surfaces of the positive electrode current collector. A positive electrode uncoated region where the positive electrode active material is not coated is formed at one end of the positive electrode plate. The positive electrode uncoated region functions as a positive electrode tab connected to the electrode lead <NUM>.

Similarly, the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer coated on one or both surfaces of the negative electrode current collector. A negative electrode uncoated region where the negative electrode active material is not coated is formed at one side of the negative electrode plate. The negative electrode uncoated region functions as a negative electrode tab connected to the electrode lead <NUM>.

In addition, the separator is interposed between the positive electrode plate and the negative electrode plate to prevent the electrode plates having different polarities from contacting each other directly. The separator may be made of a porous material to allow ions to move between the positive electrode plate and the negative electrode plate by using an electrolyte as a medium.

The cell case <NUM> includes an accommodation portion <NUM> for accommodating the electrode assembly (not shown) and a sealing portion <NUM> extending in a circumferential direction of the accommodation portion so that the electrode lead <NUM> is thermally fused thereto in an outwardly drawn state to seal the cell case <NUM>.

The electrode lead <NUM> is classified into a positive electrode lead connected to the positive electrode tab and a negative electrode lead connected to the negative electrode tab, and the positive electrode lead and the negative electrode lead are drawn out of the cell case <NUM> in opposite directions.

Meanwhile, in the present disclosure, in the sealing portion <NUM> formed around the accommodation portion <NUM>, a region positioned in the direction to which the electrode lead <NUM> is drawn out is particularly defined as a terrace portion T.

Next, the bus bar <NUM> of the unit module <NUM> according to an embodiment of the present disclosure will be described in detail with reference to <FIG> again.

Referring to <FIG>, the bus bar <NUM> is bonded to the electrode lead <NUM> by welding in a state of being fixed to the bus bar frame <NUM>, so that a portion of the bus bar <NUM> is located inside the bus bar frame <NUM> and the remaining portion is exposed out of the bus bar frame <NUM>. The portion of the bus bar <NUM> exposed out of the bus bar frame <NUM> is connected to the connector <NUM> (see <FIG> and <FIG>) explained above, thereby electrically connecting neighboring battery unit modules <NUM>.

More specifically, the bus bar <NUM> includes a bonding portion <NUM>, an exposed portion <NUM>, and a hook portion <NUM>.

The bonding portion <NUM> extends in a direction parallel to the electrode lead <NUM>, namely in the horizontal direction, to contact the electrode lead <NUM> and is located inside the bus bar frame <NUM>. The exposed portion <NUM> is bent from the bonding portion <NUM> and extends in a direction perpendicular to the bonding portion <NUM>, and also the exposed portion <NUM> is drawn out of the bus bar frame <NUM> and placed on a bus bar placing portion <NUM>, explained later.

The hook portion <NUM> extends from an end of the bonding portion <NUM> in a direction parallel to the exposed portion <NUM>, and one or more hook portions <NUM> are provided. The hook portion <NUM> allows the bus bar <NUM> to be fixed to the inside of the bus bar frame <NUM> and is coupled or fixed to a hook fixing portion <NUM> provided at an inner surface of the bus bar frame <NUM>.

As described above, the bus bar <NUM> is fixed and mounted inside the bus bar frame <NUM> so that a portion of the bus bar <NUM> is exposed out of the bus bar frame <NUM>. Also, the bonding portion <NUM> located inside the bus bar frame <NUM> is bonded to the lower surface of the electrode lead <NUM>, and the exposed portion <NUM> located at the outer side of the bus bar frame <NUM> is connected to the connector <NUM> to electrically connect neighboring unit modules <NUM> to each other.

Next, the bus bar frame <NUM> of the unit module <NUM> according to an embodiment of the present disclosure will be described in detail with reference to <FIG> along with <FIG>.

<FIG> is a front showing that the unit module applied to the battery module according to an embodiment of the present disclosure is coupled to a bus bar, <FIG> and <FIG> are perspective views showing a unit frame of a bus bar frame applied to the battery module according to an embodiment of the present disclosure at different angles, and <FIG> is a side view showing the unit frame of the bus bar frame applied to the battery module according to an embodiment of the present disclosure.

First, referring to <FIG> and <FIG>, the bus bar frame <NUM> is attached to the terrace portion T of the battery cell <NUM> and functions as a support for the bus bar <NUM> as described above.

The bus bar frame <NUM> is implemented by combining a first unit frame 130A and a second unit frame 130B having the same shape. That is, the first unit frame 130A and the second unit frame 130B are components having the same shape, where the first unit frame 130A covers at least a portion of the upper surface of the terrace portion T and the second unit frame 130B covers at least a portion of the lower portion of the terrace portion T. The first unit frame 130A and the second unit frame 130B are coupled to each other.

Meanwhile, when the first unit frame 130A and the second unit frame 130B are coupled to each other to form one bus bar frame <NUM>, the first unit frame 130A and the second unit frame 130B are point-symmetric to each other.

That is, in the completed one bus bar frame <NUM>, if the first unit frame 130A is rotated by <NUM> degrees with respect to the center point in the longitudinal direction, the first unit frame 130A has the same shape as the second unit frame 130B.

When the pair of unit frames 130A, 130B point-symmetric to each other are coupled to each other as above, the bus bar <NUM> is drawn through a gap of the coupling surfaces thereof. That is, the exposed portion <NUM> of the bus bar <NUM> is drawn through the gap between the coupling surfaces of the first unit frame 130A and the second unit frame 130B.

The drawn bus bar <NUM> is bent toward the first unit frame 130A or the second unit frame 130B and is placed on the bus bar placing portion <NUM> formed at the first unit frame 130A or the second unit frame 130B. Here, the bending direction of the bus bar <NUM> is determined according to whether the bus bar <NUM> is electrically connected to the unit module <NUM> in contact with the first unit frame 130A or the unit module in contact with the second unit frame 130B.

As described above, since the pair of unit frames 130A, 130B are components having the same shape, the detailed structure of the bus bar frame <NUM> will be described based on one unit frame (130A or 130B) with reference to <FIG>.

Referring to <FIG>, the unit frames 130A, 130B may include a fixing protrusion <NUM>, a protrusion accommodation groove <NUM>, a welding slit <NUM>, a hook accommodation groove <NUM>, a hook fixing portion <NUM>, a bus bar placing portion <NUM>, and a connector holder <NUM>.

At least one fixing protrusion <NUM> and at least one protrusion accommodation groove <NUM> are formed at the coupling surfaces of the unit frames 130A, 130B, and the fixing protrusion <NUM> and the protrusion accommodation groove <NUM> are formed in pairs at corresponding locations at the facing surfaces of the unit frames 130A, 130B. That is, the fixing protrusion <NUM> formed at the coupling surface of the first unit frame 130A has a size and shape corresponding to the protrusion accommodation groove <NUM> formed at the coupling surface of the second unit frame 130B at a position corresponding thereto, and similarly the protrusion accommodation groove <NUM> formed at the coupling portion of the first unit frame 130A has a size and shape corresponding to the fixing protrusion <NUM> formed at the coupling surface of the second unit frame 130B at a location corresponding thereto.

As the fixing protrusion <NUM> and the protrusion accommodation groove <NUM> are formed in pair, the first unit frame 130A and the second unit frame 130B may be coupled and fixed to each other.

Referring to <FIG> and <FIG>, the welding slit <NUM> is formed at a surface perpendicular to the bonding surface of the unit frames 130A, 130B and allows welding to be performed on the bonding portion of the electrode lead <NUM> (see <FIG>) and the bus bar <NUM> located inside the bus bar frame <NUM>. The welding slit <NUM> may be formed to have a length corresponding to the width of the bonding portion of the electrode lead <NUM> and the bus bar <NUM> so that welding is performed over the entire width on the bonding portion of the electrode lead <NUM> and the bus bar <NUM>.

The bus bar frame <NUM> is a component attached to the battery cell <NUM> to configure the unit module <NUM>. The bus bar frame <NUM> may also function as a pressing jig for pressing the bus bar <NUM> fixed and coupled therein to be closely adhered to the electrode lead <NUM>. Also, since the welding slit <NUM> is provided, welding may be performed easily without any additional work for securing a space for welding.

The hook accommodation groove <NUM> extends from the welding slit <NUM> and gives a space in which the hook portion <NUM> of the bus bar <NUM> may be accommodated. In view of this function, the hook accommodation groove <NUM> may be formed in the same number as the hook portion <NUM>.

The hook fixing portion <NUM> is formed on an inner wall of the hook accommodation groove <NUM> and has a shape corresponding to the hook portion <NUM> so as to be fastened with the hook portion <NUM>. That is, the hook fixing portion <NUM> may be formed in various shapes such as a groove or a protrusion formed on the hook accommodation groove <NUM>.

The bus bar placing portion <NUM> is formed concavely on the side surface of the bus bar frame <NUM> to have a size and shape corresponding to the exposed portion <NUM> so that the exposed portion <NUM> of the bus bar <NUM> exposed out of the bus bar frame <NUM> may be placed thereon without shaking.

The bus bar placing portion <NUM> may have a damage-preventing groove 136a formed at the surface thereof as a concave groove along in the length direction thereof. The damage-preventing groove 136a prevents the bus bar placing portion <NUM> from being damaged during the welding process for coupling the bus bar <NUM> and the connector <NUM> (see <FIG> and <FIG>).

That is, the bus bar frame <NUM> may be made of an injection-molded resin. In this case, during the welding process for coupling the exposed portion <NUM> of the bus bar <NUM> placed on the placing portion <NUM> to the connector <NUM>, the placing portion <NUM> is highly likely to be damaged by heat.

Thus, the groove is formed at a position corresponding to the welding line where the welding is performed, so that the bus bar <NUM> and the bus bar placing portion <NUM> do not contact each other partially, thereby preventing the injection-molded resin from melting due to heat conduction caused by welding.

Next, the connector holder <NUM> will be described in detail with reference to <FIG> along with <FIG> and <FIG>.

The connector holder <NUM> is formed to protrude on the same plane as the bus bar placing portion <NUM> of the unit frames 130A, 130B, and at least one connector holder <NUM> is formed at one longitudinal side and/or the other longitudinal side of the unit frames 130A, 130B.

The connector holder <NUM> is a component applied to fix the connector <NUM> when welding is performed to bond the connector <NUM> and the bus bar <NUM>.

Referring to <FIG> and <FIG>, the connector holders <NUM> respectively provided to a pair of neighboring unit modules 100A, 100B are simultaneously fastened together with one connector <NUM>. By doing so, the bus bar <NUM> of the first unit module 100A and the bus bar <NUM> of the second unit module 100B, which are bent toward each other, are in common contact with one connector <NUM> to electrically connect the pair of unit modules 100A, 100B.

Claim 1:
A unit module (<NUM>), comprising:
a pouch-type battery cell (<NUM>) having an electrode assembly, a cell case (<NUM>) for accommodating the electrode assembly, and an electrode lead (<NUM>) connected to the electrode assembly and drawn out of the cell case (<NUM>);
a bus bar (<NUM>) attached to the electrode lead (<NUM>); and
a bus bar frame (<NUM>) attached to a terrace portion (T) of the battery cell (<NUM>) to accommodate at least a portion of the electrode lead (<NUM>) and the bus bar (<NUM>) therein, the bus bar frame (<NUM>) pressing the electrode lead (<NUM>) and the bus bar (<NUM>) so that the electrode lead (<NUM>) and the bus bar (<NUM>) are closely adhered to each other,
characterized by the bus bar frame (<NUM>) having a welding slit (<NUM>) formed at a location corresponding to the bus bar (<NUM>) and the electrode lead (<NUM>) so that a contact portion of the bus bar (<NUM>) and the electrode lead (<NUM>) is exposed out,
wherein the bus bar (<NUM>) includes:
a bonding portion (<NUM>) extending in a direction parallel to the electrode lead (<NUM>) to contact the electrode lead (<NUM>) and located at an inner side of the bus bar frame (<NUM>);
an exposed portion (<NUM>) bent from the bonding portion (<NUM>) to extend in a direction perpendicular to the bonding portion (<NUM>) and drawn out of the bus bar frame (<NUM>); and
a hook portion (<NUM>) extending from an end of the bonding portion (<NUM>) in a direction parallel to the exposed portion (<NUM>).