Abstract:
A battery module including a plurality of battery cells each having a vent; an insulating member on the battery cells, the insulating member having a plurality of openings and a protrusion seal extending around a periphery of each of the openings; a pressurizing member on the insulating member, the pressurizing member having a plurality of openings; and a cover covering the insulating member and the pressurizing member.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of U.S. Provisional Application No. 61/607,907, filed on Mar. 7, 2012, the United States Patent and Trademark Office, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present invention relates to a battery module. 
     2. Description of the Related Art 
     Recently, a high output battery module has been developed by using a non-aqueous electrolyte of high energy density, the high output battery module including a plurality of battery cells connected in series to drive a motor such as an electric vehicle and the like in which high power is necessary. 
     A typical battery cell includes an electrode assembly composed of a positive plate, a negative plate and electrolyte, which generates energy by a electro-chemical reaction with the pole plates and the electrolyte. In this case, gas may be generated within the battery cell by side-reaction of the electro-chemical reaction. 
     SUMMARY 
     A battery module is provided that is capable of preventing a gas leak generated from the battery cell under degassing by forming a pressurizing member between a cover covering a vent and a gasket. In one embodiment, the battery module is capable of independently sealing each vent by forming a protrusion along a circumference of a first opening member facing the vent. 
     In one embodiment, a battery module is provided including a plurality of battery cells each having a vent; an insulating member on the battery cells, the insulating member having a plurality of openings and a protrusion seal extending around a periphery of each of the openings; a pressurizing member on the insulating member, the pressurizing member having a plurality of openings; and a cover covering the insulating member and the pressurizing member. 
     In one embodiment, the protrusion seal is a double protrusion seal. The double protrusion seal of the insulating member may include a first protrusion and a second protrusion configured to be movable with respect to the first protrusion. Further, the protrusion seal may extend around a periphery of the vent of at least one of the battery cells. 
     In one embodiment, the pressurizing member comprises a first pressurizing member and a second pressurizing member stepped from the first pressurizing member. Additionally, the cover may have a rib structure, configured to contact the pressurizing member, wherein the rib structure includes a pair of first ribs having a first length and a pair of second ribs having a second length different from the first length. In one embodiment, the pair of first ribs contacts the first pressurizing member and wherein the pair of second ribs contacts the second pressurizing member. Further, the pressurizing member further may include a fixing protrusion ext ending therefrom and the cover may have a fixing groove accommodating the fixing protrusion of the pressurizing member. 
     In one embodiment, the pressurizing member includes a pressurizing protrusion protruding towards the battery cells, wherein the pressurizing protrusion is generally aligned with the protrusion seal on the insulating member. In embodiments, the protrusion seal is made from a flexible material and the protrusion seal is integral as a single body with the insulating member. 
     In another embodiment, a battery module is provided including a plurality of battery cells each having a vent; a pressurizing member having a plurality of openings and a protrusion seal extending around a periphery of each of the openings; and a cover covering the insulating member and the pressurizing member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a battery module according to a first embodiment of the present invention. 
         FIG. 2  is an exploded perspective view showing the battery module of  FIG. 1 . 
         FIG. 3  is a rear perspective view of a cover, a pressurizing member and a gasket of the battery module of  FIG. 1 . 
         FIG. 4  is a cross-sectional view taken along line A-A′ of  FIG. 1 . 
         FIG. 5  is a cross-sectional view taken along line B-B′ of  FIG. 3 . 
         FIG. 6  is an exploded perspective view showing a battery module according to a second embodiment of the present invention. 
         FIG. 7  is a vertical perspective view showing a top of the battery module of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. 
     An embodiment of the present disclosure will be described with reference to accompanying drawings in detail. 
       FIG. 1  is a perspective view showing a battery module according to a first embodiment of the present invention and  FIG. 2  is an exploded perspective view showing a battery module according to a first embodiment of the present invention. 
     Referring to  FIGS. 1 and 2 , a battery module according to the present invention includes a plurality of battery cells  10  forming a vent  13  for discharging gas, an insulating member  130  formed at a position generally corresponding to a vent  13  of the battery cell  10  and a cover  120  covering the vent  13  and the insulating member  130  at top thereof. In addition, a pressurizing member  140  includes between the cover  120  and the insulating member  130 . 
     In this case, the cover  120  is a hexahedral shape, wherein one side thereof is opened, wherein the inside thereof has a space, and wherein the opened surface of the cover  120  faces the vents  13  on the top of the battery cell  10 . Therefore, the space within the cover  120  may form a path capable of moving gas discharged from the vent  13  during degassing. 
     In addition, the insulating member  130  may be made of an elastic or flexible material such as silicon and includes a first opening  131  at a position generally corresponding to the vent  13 . Such an insulating member  130  may be integrally formed to cover all of the vents  13  and a double protrusion may be formed along a circumference of the first opening  131  of a surface facing the vent  13  (see  132  in  FIG. 3 ). 
     Such an insulating member  130  may be made of a heat-resistant material because the battery cell  10  generates heat in process of battery charging. 
     Sometimes the plurality of battery cells  10  can emit heat that melts the insulating member  130  attached to the battery cell  10 . As described above, when the insulating member is melted, gas leaks due to a reduction of a sealing capacity between the insulating member  130  and the cover  120 . Therefore, the insulating member  130  can be made of a heat-resistant material to prevent a gas leak. 
     In addition, the pressurizing member  140  placed on the top of the insulating member  130  includes a second opening  141  at an area generally corresponding to the first opening  131 . Such a pressurizing member  140  includes a first pressurizing member  145  along a center portion of a longitudinal direction thereof, a second pressurizing member  146  formed to step from the first pressurizing member  145  along both ends of the first pressurizing member  145  and a connector  143  connecting the first pressurizing member  145  and second pressurizing member  146 . 
     In one embodiment, the first pressurizing member  145  is placed above the insulating member  130  and the top of the battery cell  10  and the second pressurizing member  146  is placed above the top of the battery cell in which the insulating member is not formed. Therefore, a space surrounded by the first pressurizing member  145 , the connecting element  143 , and the vent  13  is formed by the step between the first pressurizing member  145  and the second pressurizing member  146 , and wherein the insulating member  130  may be located in the space. 
     In addition, both ends of the second pressurizing member have at least one fixing protrusion  142  bent vertically toward the cover  120 . Further, the fixing groove  126  is formed in the cover  120  generally corresponding to the fixing protrusion  142 . The pressurizing member  146  is firmly fixed and the insulating member  130  placed below the pressurizing member  146  can be further pressurized by inserting the fixing protrusion  142  into the fixing groove  126 . This improves a sealing of the gas flowing path formed within the cover  120 . 
     In addition, the cover  120  is seated on the top of the battery cell  10  so that an opened surface thereof is in communication with the vent  13 , and at least one rib  121  and  122  is formed in the inner space of the cover  120  along a longitudinal direction. Such a rib  121  and  122  includes a pair of first ribs  121  formed at position generally corresponding to the first pressurizing member  145  of the pressurizing member  140  and a pair of second ribs  122  formed at a position generally corresponding to the second pressurizing member  146  of the pressurizing member  140 . In this case, since the first pressurizing member  145  and second pressurizing member  146  are stepped, a length of the first rib  121  is shorter than a length of the second rib  122 . 
     One end of the cover is formed with a gas discharging port  125  connected with the outside. On degassing in a battery cell  10 , gas discharged through the vent  13  moves through the cover  120  and is discharged out of the gas discharging port  125 . In this case, the gas discharging port  125  is formed in a T-shape. Since a left side and a right side is opened, the gas does not have an effect on an adjacent battery module  100 . However, a type of the gas discharge port is not limited to the ones described herein. 
     Next, a battery cell and a housing will briefly described. 
     The battery cell  10  includes an electrode case and a cap plate  14  sealing an open area. The electrode case houses an electrode assembly having positive plate and a negative plate, and a separator located between these pole plates, and an electrolyte. A positive terminal  11  connected with the positive plate and a negative terminal  12  connected with the negative plate, which are formed at both ends of the cap plate  14 , protrude from the electrode assembly. The positive plate and the negative plate of the electrode assembly react with the electrolyte to generate energy. The energy is transferred through the positive terminal  11  and the negative terminal  12  into the outside. 
     In addition, if a gas pressure generated from the inside of the battery cell  10  is above a predetermined value, the vent  13  provided between the positive terminal  11  and the negative terminal  12  of the cap plate  14  serves as a discharge path of gas from the battery cell  10 . Therefore, the vent  13  can prevent the battery cell  10  from being damaged by the internal pressure thereof. The gas can be generated as a byproduct of the pole plate and electrolyte as the battery cell  10  is charged and such a gas is discharged through the vent  13 . 
     An external case of the battery cell  10  is made of metal and the cover  120  is made of plastic resin. In this case, since the battery cell  10  and the cover  120  are made of heterogeneous or different materials, when the cell  10  and the cover  120  contact each other, they may not form a secure connection and a gas leak may occur in a vulnerable area. In order to prevent or minimize this, the insulating member  130  is provided between a battery pack  10  and the cover  120  to keep an area between the battery cell  10  and the cover  120  airtight. 
     In addition, the housing  110  includes a pair of end plates  111  provided in both ends of a plurality of battery cells  10 , a side bracket  112  connecting the side of the end plates  111  and a bottom bracket connecting the bottom of the end plates  111 . 
     Here, the pair of end plates  111  are formed to surface-contact the uppermost battery  10  to compress the plurality of battery cells  10 . 
     In addition, the side bracket  112  is connected to each of the end plates  111  to support both sides of the plurality of battery cells. Further, the bottom of the battery cell  10  is supported by the bottom bracket. As described above, the plurality of battery cells  10  are housed by a housing  110  composed of the pair end plates  111 , the side bracket  112 , and the bottom bracket. 
       FIG. 3  is a rear perspective view of a cover, a pressurizing member and a gasket according to a first embodiment of the present invention. 
     Referring to  FIG. 3 , an insulating member  130  is formed to generally correspond to a vent (see  13  in  FIG. 2 ) of the top of a battery cell (see  10  in  FIG. 2 ) according to the first embodiment of the present invention. 
     A pressurizing member  140  is formed below the insulating member  130  and a cover  120  is formed below the insulating member  130  and the pressurizing member  140 . The cover  120  is formed in a hexahedral shape providing a space between the cover and the battery cells, which one side thereof is opened. The opened surface of such a cover  120  is placed over the vent  13 . 
     In one embodiment, the insulating member  130  includes a first opening  131  at an area generally corresponding to the vent  13  and a double protrusion  132  formed along a circumference of the first opening  131  of the insulating member  140  facing the vent  13 . The double protrusion  132  includes a first protrusion  132   a  formed along the circumference of the first opening  131  and a second protrusion  132   b  formed along the circumference of the first protrusion  132   a . The first protrusion  132   a  and the second protrusion  132   b  closely contact each other in a non-pressurized state and a gap therebetween widens due to pressurization. The first protrusion  132   a  and the second protrusion  132   b  are integral with the insulating member  130  and may be made of a material of the same silicon as the insulating member  130 . Although a double protrusion has been described herein, a single protrusion may also be used within the spirit and scope of the present invention. 
     In addition, the pressurizing member  140  includes a second opening  141  at an area generally corresponding to the first opening  131 . 
     Such a pressurizing member  140  includes a first pressurizing member  145  extending along a center portion of a longitudinal direction and a second pressurizing member  146  stepped with the first pressurizing member  145  extending along both ends of the pressurizing member  145 . The first pressurizing member  145  and the second pressurizing member  146  are connected by a connector  143 . In one embodiment, a space surrounded by the first pressurizing member  145  and the connecting element  143  is formed by stepping the first pressurizing member  145  and the second pressurizing member  146 . The insulating member  130  can be accommodated in the space. 
     In addition, the cover  120  accommodated the insulating member  130  and the pressurizing member  140  and the space within the cover  120  can be used as a flow path though which gas is discharged from the vent  13  move during a degassing. 
     In addition, a least one rib  121  and  122  is formed within the space of the cover  120  along the longitudinal direction of the cover  120 . The ribs  121  and  122  include a pair of first ribs formed at position generally corresponding to the first pressurizing member  145  of the pressurizing member  140  and a pair of a ribs  122  formed at a position generally corresponding to the second pressurizing member  146  of the pressurizing member  140 . 
     In one embodiment, since the first pressurizing member  145  and the second pressurizing member  146  of the pressurizing member  140  are stepped, a length of the first rib  121  pressurizing the first pressurizing member  145  is shorter than a length of the second rib  122  pressurizing the second pressurizing member  146 . In one embodiment, a pair of first ribs at position generally corresponding to the first pressurizing member  145  is formed to generally correspond to a double protrusion  132  of the insulating member  130 . 
     Furthermore, both ends of the second pressurizing member  146  of the pressurizing member  140  have at least one fixing protrusion  142  vertically bent toward the cover  120  and the cover  120  corresponding to the fixing protrusion  142  is formed with a fixing groove  126 . This enables the fixing protrusion  142  of the pressurizing member  140  to be inserted into the fixing groove  126  of the cover  120 . 
       FIG. 4  is a cross-sectional view taken along line A-A′ of  FIG. 1  and  FIG. 3  is a cross-sectional view taken along line B-B′ of  FIG. 3 . 
     Referring to  4  and  5 , the insulating member  130  is formed at a position generally corresponding to a vent  13  of a battery cell  10 . 
     As shown in the figures, one surface of the insulating member  130  in contact with the batter cell  10  is formed with a double protrusion  132  along a circumference of the first opening  131 . In addition, the pressurizing member  140  is formed on top of the insulating member  130 . The pressurizing member  140  includes a first pressurizing member  145  close to the top of a insulating member  130 , a second pressurizing member  146  placed in both end portions of the first pressurizing member  145  and formed to step with the first pressurizing member  145  to be closed to the top of the battery cell  10  and a connector  143  connecting the first pressurizing member  145  and a second pressurizing member  146 . 
     In addition, the insulating member  130  and the pressurizing member  140  is covered by a cover  120  having an interior space. In this case, both ends of the second pressurizing member  146  of the pressurizing member  140  formed with at least one fixing protrusion  142  vertically bent toward the cover  120 . The fixing protrusion  142  is inserted into the fixing groove  126  on the cover  120  and the pressurizing member  140  pressurizes the insulating member  130  by pressurizing the pressurizing member  140  of the cover  120 . Therefore, the double protrusion of the insulating member  130  becomes wider to more easily seal the vent. 
     Additionally, the top of the inside of the cover  120  facing the pressurizing member  140  is formed with at least one rib  121  and  122  along a longitudinal direction of the cover  120 . Herein, a pair of first ribs  121  located to generally correspond to the first pressurizing member  145  can pressurize the pressurizing member  140  and the insulating member  130 , and the battery cell  10 . Herein, a pair of second ribs located to generally correspond to the second pressurizing member  146  can pressurize the pressurizing member  140  and the battery cell  10 . In this case, the first rib  121  is formed to generally correspond to the double protrusion  132  of the insulating member  130  to apply a greater pressure to the double protrusion  132 . 
     The pressure is applied to the pressurizing member  140  by the first rib  121  and the second rib  122  formed on an inner side of the cover and such a pressure is applied to the insulating member  130  through the pressurizing member  140 . Therefore, a portion of the insulating member  130  not corresponding to the first rib  121  and the second rib  122  also can be pressurized against the top of the battery cell  10 . 
     The first protrusion  132   a  and the second protrusion  132   b  are close to each other when the pressure is not applied, whereas they separate in generally opposite directions when the pressure is applied to the first protrusion  132   a  and the second protrusion  132   b . This enables the top of the battery cell  10  and the insulating member  130  to be closed. Therefore, gas discharged from the vent under a degassing may be discharged through the first opening  131 . In addition, a gap does not occur between the insulating member  130  and the pressurizing member  140  because the pressurizing member  140  is pressurized by the cover  120 . Therefore, gas discharged through the first opening  131  can be discharged through the second opening  141  into the inner space of the cover  120 , that is, through the gas flow path into the outside. 
       FIG. 6  is exploded perspective view of a battery module according to a second embodiment of the present invention and  FIG. 7  is a vertical cross-sectional view of the top of the battery module according to a second embodiment of the present invention. 
     The battery module according to the second embodiment of the present invention is substantially similar to that of the first embodiment expect for the pressurizing protrusion formed in the pressurized element. Therefore, a duplicate detailed description will be omitted. 
     Referring to  FIGS. 6 and 7 , the battery module  200  according to a second embodiment of the present invention is arranged in one direction and includes a plurality of battery cells  10  having a vent  13  which discharges gas to the top thereof, an insulating member  130  formed at position generally corresponding to the vent  13  of a battery cell  10  and a cover  120  covering the vent  13  and the insulating member  130 . A pressurizing member  140  is further between the cover  120  and the insulating member  130 . 
     Herein, the insulating member  130  is formed with a double protrusion  132  along a circumference of the first opening  131  facing the vent  13 . 
     In addition, one surface of the pressurizing member  140  facing the insulating member  130  is formed with the pressurizing protrusion  144  along a circumference of the second opening  141 . In one embodiment, the pressurizing protrusion  144  is formed at a position generally corresponding to an area in which the double protrusion  132  is formed. 
     The pressure which the cover  10  applies to the battery cell  10  is transferred to the insulating member  130  through the pressurizing member  140 , but the area in which the pressurizing protrusion  144  is formed is subjected to a greater pressure. That is, the area having the double protrusion  132  is exposed to an intense pressure compared with other areas by the pressurizing protrusion  144  formed to correspond to the double protrusion  132  of the insulating member  130 . This enables the sealing capacity between the battery cell  10  and the insulating member  130  to prevent or reduce the likelihood of gas leaks between the battery cell  10  and the insulating member  130 . 
     Embodiments of the present invention prevent a gas leak generated from the battery cell to the outside by forming the pressurizing member between a cover covering a vent and the gasket which improves sealing of the gas discharge path. 
     In addition, each vent is independently sealed by a double protrusion along a circumference of a first opening of a gasket facing the vent to prevent a gas from leaking to the outside. 
     As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.