Patent Description:
In order to supply electric energy to an application such as an electric vehicle using a battery module or a battery pack in which a plurality of battery modules are connected, a terminal or a connecting bar of a power cable must be fastened to a module terminal of the battery module.

When an external terminal such as a terminal or a connecting bar of a power cable is fastened to the module terminal of the battery module as described above, a bolt/nut fixing structure may be applied. In the bolt/nut fixing structure, a terminal nut is located at a lower part of the module terminal of the battery module, and an external terminal is located at an upper part of the module terminal. Then, if the external nut is inserted into a bolt and then rotated in a clockwise direction, the terminal nut is closely adhered to a lower surface of the module terminal, and also the external terminal is adhered and fixed on the module terminal.

For example, in the battery module applied to an electric vehicle, if the coupling force between the external terminal and the module terminal is weakened to cause a contact failure between the external terminal and the module terminal, components of the electric vehicle cannot be normally performed partly or entirely. Thus, the bolt must be tightened with very strong force.

In this case, the structure surrounding the periphery of the nut is usually made of a resin injection material for insulation so that the nut does not turn together when the bolt is rotated for fastening.

In addition, in the bolt/nut fixing structure, in order to obtain a high fastening force, the bolt must be sufficiently rotated in a state of being fastened to the nut. However, if a nut having a blocked lower surface is applied or the injection material accommodating the nut has a blocked structure at the surface supporting the nut, the bolt may not be sufficiently rotated, and accordingly the coupling force between the module terminal and the external terminal may not be sufficiently secured.

<CIT> discloses a battery module structured by including a battery module formed by allowing a plurality of battery cells to be stacked therein, a fixing piece fixed to a cover and a terminal piece which is connected to a busbar and extends above the fixing piece. A nut is positioned below the terminal piece. A coupling member includes a cylindrical unit for accommodating the nut and a key unit which is formed below the cylindrical unit so as to form the space capable of accommodating a bolt penetrating the nut. The terminal piece is exposed to the outside.

<CIT> describes a module terminal including a terminal main body which is made of a metal plate and an insulating interference preventing member which is mounted on the terminal main body. In the terminal main body one end portion is connected electrically to an electrode of a battery rack, and a female screw portion is formed integrally on a terminal portion to penetrate therethrough. While a distal end of a male screw faces an end face of the battery pack when the mal screw is screwed into the female screw portion, the interference prevention member is disposed therebetween.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing a battery module, which has a structure in which a nut is stably fixed even though a bolt is strongly fastened, by reinforcing rigidity of a portion where the nut is fixed.

In addition, the present disclosure is also directed to providing a battery module, which has an additional space for accommodating the bolt so that the bolt may be sufficiently rotated, and also has a structure capable of preventing foreign matter, which may be generated by friction between the bolt and the nut as the bolt is rotated with strong force, from entering the inner space of the battery module.

In one aspect of the present disclosure, there is provided a battery module, comprising: a cell stack formed by stacking a plurality of battery cells; a bus bar frame assembly having a bus bar frame configured to cover one longitudinal side and the other longitudinal side of the cell stack and a plurality of bus bars fixed on the bus bar frame and electrically connected to the battery cells; a module terminal having a lead connection portion fixed on the bus bar frame and electrically connected to the battery cells and a head portion connected to the lead connection portion to extend above the lead connection portion; a terminal nut located below the head portion; and a frame cover having a nut accommodation portion configured to accommodate the terminal nut and a bolt accommodation portion formed below the nut accommodation portion to accommodate a bolt passing through the head portion and the terminal nut, the frame cover being configured to cover the bus bar frame assembly so that the head portion is exposed to the outside.

The terminal nut may be a hexagonal nut.

The nut accommodation portion may have a size corresponding to the terminal nut, and an inner wall of the nut accommodation portion may be in contact with a side surface of the bolt to fix the terminal nut so that the terminal nut does not rotate together when the bolt rotates.

The bolt accommodation portion may have a groove shape formed at a bottom surface of the nut accommodation portion.

The frame cover may include a barrier formed between the bolt accommodation portion and the bus bar frame assembly to prevent foreign matter generated when the bolt and the terminal nut are fastened from entering the bus bar frame assembly.

The battery module may further comprise an end plate configured to cover the frame cover.

The battery module may further comprise a reinforcing frame interposed between the end plate and the frame cover at a location corresponding to the nut accommodation portion.

The battery cell may include an electrode assembly; a pair of electrode leads connected to the electrode assembly to extend in opposite directions along a longitudinal direction of the battery cell; and a cell case configured to accommodate the electrode assembly and sealed so that the electrode lead is exposed to the outside.

The pair of electrode leads may be formed at locations biased downward from a center of the cell stack in a height direction thereof.

The module terminal may be disposed in a space formed above the electrode lead due to the biasing of the electrode leads.

In another aspect of the present disclosure, there are also provided a battery pack and a vehicle, which comprises the battery module according to an embodiment of the present disclosure.

According to an embodiment of the present disclosure, even if the bolt is tightened with a strong force to fasten an external terminal to the module terminal, the nut may be stably fixed.

In addition, according to another embodiment of the present disclosure, since an additional space for accommodating the bolt protruding below the nut is provided, the bolt may be sufficiently rotated. Also, it is possible to prevent foreign matter, which may be generated by friction between the bolt and the nut as the bolt is rotated with a strong force, from entering the inner space of the battery module.

Referring to <FIG>, a battery module according to an embodiment of the present disclosure may include a cell stack <NUM>, a FPCB assembly <NUM>, a bus bar frame assembly <NUM>, a module terminal <NUM>, an upper cover <NUM>, a mono frame <NUM>, a frame cover <NUM> and an end plate <NUM>.

As shown in <FIG>, the cell stack <NUM> includes a plurality of battery cells <NUM> stacked to face each other at wide surfaces thereof. The cell stack <NUM> may include at least one buffer pad P interposed at an outermost battery cell <NUM> and/or between adjacent battery cells <NUM>.

That is, the cell stack <NUM> may be inserted into the mono frame <NUM> in a state of being coupled with the bus bar frame assembly <NUM>, the module terminal <NUM> and the upper cover <NUM>. At this time, in order to insert the cell stack <NUM> easily while securing a maximum volume of the cell stack <NUM>, the buffer pad P made of an elastic material such as a sponge may be additionally applied.

Referring to <FIG>, a specific structure of the battery cell <NUM> is illustrated. A pouch-type battery cell may be applied as the battery cell <NUM>. The pouch-type battery cell <NUM> includes an electrode assembly (not shown), a pair of electrode leads <NUM> and a cell case <NUM>.

Although not shown in the drawings, the electrode assembly has a form in which separators are interposed between positive electrode plates and negative electrode plates that are repeatedly stacked alternately, and separators are preferably positioned at both outermost sides for insulation.

The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer coated on one side of the positive electrode current collector, and a positive electrode uncoated region not coated with a positive electrode active material is formed at one side end of the positive electrode plate. The positive electrode uncoated region functions as a positive electrode tab.

The negative electrode plate may include a negative electrode current collector and a negative electrode active material layer coated on one surface or both sides of the negative electrode current collector, and a negative electrode uncoated region not coated with a negative electrode active material is formed at one side end of the negative electrode plate. The negative electrode uncoated region functions as a negative electrode tab.

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

The pair of electrode leads <NUM> are connected to the positive electrode tab (not shown) and the negative electrode tab (not shown), respectively, and are drawn out of the cell case <NUM>. The pair of electrode leads <NUM> are drawn out at one longitudinal side and the other longitudinal side of the battery cell <NUM>, respectively. That is, the battery cell <NUM> applied to the present disclosure corresponds to a bidirectional draw-out battery cell in which the positive electrode lead and the negative electrode lead are drawn in opposite directions.

In addition, the pair of electrode leads <NUM> are positioned to be biased to one side from a center of the battery cell <NUM> in a width direction (the Z-axis direction of <FIG>). Specifically, the pair of electrode leads <NUM> are positioned to be biased to one side from the center of the battery cell <NUM> in the width direction, preferably to be biased downward along the height direction (the Z-axis direction of <FIG>) of the cell stack <NUM>.

If the pair of electrode leads <NUM> are positioned to be biased to one side from the center of the battery cell <NUM> in the width direction as described above, it is possible to give a space for installation of the module terminal <NUM>, explained later, so that the energy density of the battery module is improved. The increase in energy density due to the structure in which the electrode lead <NUM> is installed to be biased will be described in detail later.

The cell case <NUM> includes two regions, namely an accommodation portion accommodating the electrode assembly and a sealing portion extending in a circumferential direction of the accommodation portion and thermally fused in a state where the electrode lead <NUM> is drawn out to seal the cell case <NUM>.

Although not shown in the figures, the cell case <NUM> is sealed by affixing and thermally fusing edge portions of an upper case and a lower case made of a multi-layered pouch film in which a resin layer, a metal layer and a resin layer are stacked in order.

In the sealing portion, a terrace portion 112a corresponding to a region located in the direction in which the electrode lead <NUM> is drawn out has a tapered shape such that both sides of the terrace portion 112a are cut so that the width thereof is gradually reduced along the drawing direction of the electrode lead <NUM>. As described above, if the width of the terrace portion 112a is gradually reduced toward the outer direction of the battery cell <NUM>, the electrode lead <NUM> may be disposed to be biased, and the energy density of the battery module may be improved.

Meanwhile, the battery cell <NUM> applied to the present disclosure is a long cell where a ratio of width (W) to length (L) is about <NUM> or more and <NUM> or less. In the battery module according to the present disclosure, if the long cell type battery cell <NUM> is employed, it is possible to improve the capacity of the battery while minimizing the increase in the height of the battery module, which makes it easy to install the battery module at a lower part of a seat or a trunk of a vehicle.

Referring to <FIG>, the FPCB assembly <NUM> may be implemented to include a flexible printed circuit board (FPCB) <NUM> and a connector <NUM>.

The FPCB <NUM> extends along the longitudinal direction of the battery module (the Y-axis direction of <FIG>) to cover at least a portion of the top surface of the cell stack <NUM>, and both ends of the FPCB <NUM> are bent and placed on the bus bar frame assembly <NUM>. Connection terminals <NUM> are provided at both ends of the bent FPCB <NUM>, and the connection terminals <NUM> are connected to the bus bar <NUM> and the module terminal <NUM> to electrically connect the FPCB <NUM> to the battery cell <NUM>.

The connector <NUM> is exposed out of the upper cover <NUM> and the mono frame <NUM> and mounted on the FPCB <NUM> that is bent toward the bus bar frame assembly <NUM>. The connector <NUM> is disposed in a space formed above the electrode lead <NUM> due to the biasing of the electrode lead <NUM>, similar to the installation position of the module terminal <NUM> described above. The arrangement position of the connector <NUM> minimizes the increase in the volume of the battery module due to the installation of the connector <NUM>, thereby increasing the energy density of the battery module.

The connector <NUM> is electrically connected to the battery cells <NUM> through the FPCB <NUM>. In addition, a control device (not shown) such as a BMS is connected to the connector <NUM>, and the control device receives information about the voltage of the battery cell <NUM> and controls charging and discharging of the battery module with reference to the information.

Referring to <FIG>, the bus bar frame assembly <NUM> may be implemented to include a bus bar frame <NUM> configured to cover one longitudinal side and the other longitudinal side of the cell stack <NUM> and a plurality of bus bars <NUM> fixed on the bus bar frame <NUM> and electrically connected to the battery cell <NUM>.

The bus bar frame <NUM>, for example, may be made of an insulating material such as resin, and includes a bus bar placing portion <NUM> formed to protrude at a position corresponding to electrode leads <NUM> of the battery cell <NUM>. The bus bar placing portion <NUM> is formed at a position biased downward from the center of the cell stack <NUM> in the height direction (the Z-axis direction of <FIG> and <FIG>), like the electrode lead <NUM>. The biasing of the bus bar placing portion <NUM> is to secure a space for installing components such as the connector <NUM> or the module terminal <NUM>, similar to the biasing of the electrode lead <NUM>.

The bus bar placing portion <NUM> has a plurality of lead slits S formed at positions corresponding to the electrode leads <NUM>. Through the lead slits S, the electrode leads <NUM> are drawn out of the bus bar frame assembly <NUM>, and the drawn electrode leads <NUM> are bent and fixed by welding or the like on the bus bar <NUM>.

Referring to <FIG>, the module terminal <NUM> is provided in a pair, and each module terminal <NUM> includes a lead connection portion <NUM> and a head portion <NUM>.

The lead connection portion <NUM> is fixed on the bus bar placing portion <NUM> of the bus bar frame <NUM> and is connected to the electrode lead <NUM> located at both outermost sides along the width direction of the cell stack <NUM> (the X-axis direction of <FIG> and <FIG>). The head portion <NUM> is connected to the lead connection portion <NUM> and extends above the lead connection portion <NUM>. The head portion <NUM> has a terminal hole <NUM> into which a bolt B applied for fastening an external terminal (not shown) to the module terminal <NUM> is inserted.

Referring to <FIG> along with <FIG>, the head portion <NUM> of the module terminal <NUM> is located in the space formed above the electrode lead <NUM> and the bus bar placing portion <NUM> due to the biasing of the electrode lead <NUM> (upward along the Z axis based on <FIG> and <FIG>). The formation position of the head portion <NUM> is to minimize the volume of the battery module increased due to the installation of the module terminal <NUM> by utilizing the space formed by the biased installation of the electrode lead <NUM>.

Referring to <FIG> and <FIG> together, the upper cover <NUM> corresponds to a part that covers the top surface of the cell stack <NUM> (a surface parallel to the X-Y plane of <FIG>). The upper cover <NUM> is hinged with a pair of bus bar frames <NUM>, respectively. Thus, the pair of the bus bar frames <NUM> may be rotated relative to the upper cover <NUM>, based on the hinged portion.

Referring to <FIG> along with <FIG>, the frame cover <NUM> covers the bus bar frame assembly <NUM> so that the head portion <NUM> of the module terminal <NUM> is exposed to the outside. The frame cover <NUM> includes a nut accommodation portion <NUM>, a bolt accommodation portion <NUM>, and a barrier <NUM>.

The nut accommodation portion <NUM> accommodates a terminal nut N located below the head portion <NUM> of the module terminal <NUM>. In order to supply electric energy to an application such as an electric vehicle by using the battery module or a battery pack in which a plurality of battery modules are connected, an external terminal T such as a terminal or a connecting bar of a power cable provided in the vehicle must be fastened to the module terminal <NUM> of the battery module (see <FIG>). As described above, in order to fasten the external terminal T to the module terminal <NUM> of the battery module, the battery module according to an embodiment of the present disclosure uses a bolt/nut fixing structure.

That is, the terminal nut N is located under the head portion <NUM> of the module terminal <NUM>, the external terminal T is located above the head portion <NUM>, and then a bolt B (see <FIG>) is inserted to pass through the external terminal T and the head portion <NUM> in order and is rotated clockwise. In this case, the bolt B moves downward along a thread formed on the terminal nut N, and the terminal nut N moves upward (an arrow direction in <FIG>) on the contrary. Accordingly, the external terminal T is fixed between the bolt B and the head portion <NUM>. As the bolt B is rotated clockwise more, the fixing force becomes stronger.

In this way, in order for the terminal nut N to move upward with the rotation of the bolt B, the terminal nut N must be fixed without rotating together according to the rotation of the bolt B. That is, an inner wall of the nut accommodation portion <NUM> is in contact with a side surface of the terminal nut N to fix the terminal nut N so that the terminal nut N does not rotate according to the rotation of the bolt B.

To this end, the nut accommodation portion <NUM> has a size corresponding to the terminal nut N. Specifically, the nut accommodation portion <NUM> and the terminal nut N may be formed to have the same width (D1) and the same vertical width (D2), and the terminal nut N may be a hexagonal nut whose cross section is approximately hexagonal.

When the bolt B passes through the terminal nut N to protrude downward below the terminal nut N according to the clockwise rotation of the bolt B, the bolt accommodation portion <NUM> accommodates the protruding portion of the bolt B. The bolt accommodation portion <NUM> has a groove shape formed at the bottom surface of the nut accommodation portion <NUM>.

The barrier <NUM> is formed between the bolt accommodation portion <NUM> and the bus bar frame assembly <NUM> to form an inner wall of the bolt accommodation portion <NUM>. The barrier <NUM> prevents the bolt accommodation portion <NUM> and the bus bar frame assembly <NUM> from communicating with each other, thereby preventing foreign matter, such as metal powder generated when the bolt B and the terminal nut N are fastened, from entering the bus bar frame assembly <NUM>.

By preventing foreign matter such as metal powder from entering the bus bar frame assembly <NUM> as above, it is possible prevent that an unnecessary electrical connection occurs between the electrode leads <NUM> due to foreign matter to cause a problem such as a short.

Referring to <FIG> and <FIG> together, the end plate <NUM> covers the frame cover <NUM> such that the head portion <NUM> of the module terminal <NUM> is exposed to the outside. Meanwhile, as shown in <FIG>, the battery module according to an embodiment of the present disclosure may further include a reinforcing frame F interposed between the frame cover <NUM> and the end plate <NUM>.

Referring to <FIG> along with <FIG>, the reinforcing frame F is interposed at a position corresponding to the nut accommodation portion <NUM> of the frame cover <NUM> to enhance the fixing force of the nut N. That is, the frame cover <NUM> may be made of a resin material for insulation. In this case, if the bolt B is strongly rotated and tightened, the inner wall of the nut accommodation portion <NUM> may be bent or damaged not to fix the terminal nut N.

In order to prevent this situation from occurring, the reinforcing frame F may be made of a metal material with a higher rigidity than resin, and the bolt B may be strongly tightened by applying the reinforcing frame F to strengthen the fastening force between the external terminal T and the head portion <NUM>.

As described above, since the head portion <NUM> of the module terminal <NUM> is disposed using the space formed by the biasing of the electrode lead <NUM>, the battery module according to an embodiment of the present disclosure may minimize the increase in the volume of the battery module due to the installation of the module terminal <NUM>, thereby improving the energy density.

In addition, the battery module according to an embodiment of the present disclosure includes the bolt accommodation portion <NUM> accommodating the bolt B protruding below the terminal nut N, thereby increasing the degree of freedom in selecting the length of the bolt B. Accordingly, by using the bolt B having a sufficiently long length to pass through the terminal nut N, the fastening force between the external terminal T and the head portion <NUM> of the module terminal <NUM> may be further strengthened.

Claim 1:
A battery module, comprising:
a cell stack (<NUM>) formed by stacking a plurality of battery cells (<NUM>);
a bus bar frame assembly (<NUM>) having a bus bar frame (<NUM>) configured to cover one longitudinal side and the other longitudinal side of the cell stack (<NUM>) and a plurality of bus bars (<NUM>) fixed on the bus bar frame (<NUM>) and electrically connected to the battery cells (<NUM>);
a module terminal (<NUM>) having a lead connection portion (<NUM>) fixed on the bus bar frame (<NUM>) and electrically connected to the battery cells (<NUM>) and a head portion (<NUM>) connected to the lead connection portion (<NUM>) to extend above the lead connection portion (<NUM>);
a terminal nut (N) located below the head portion (<NUM>); and
a frame cover (<NUM>) having a nut accommodation portion (<NUM>) configured to accommodate the terminal nut (N) and a bolt accommodation portion (<NUM>) formed below the nut accommodation portion (<NUM>) to accommodate a bolt (B) passing through the head portion (<NUM>) and the terminal nut (N), the frame cover (<NUM>) being configured to cover the bus bar frame assembly (<NUM>) so that the head portion (<NUM>) is exposed to the outside.