Patent Publication Number: US-2021162872-A1

Title: Battery system and electric vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims to the priority of Chinese Patent No “201711330171.0” filed by the BYD Co., Ltd. on Dec. 13, 2017 and entitled “BATTERY SYSTEM AND ELECTRIC VEHICLE”, which is incorporated herein by reference in its entirety. 
     FIELD 
     The present disclosure relates to the field of batteries, and relates to a battery system and an electric vehicle. 
     BACKGROUND 
     In recent years, in the context of global environmental pollution and the shortage of petroleum energy, an electric vehicle has emerged. As a main power source battery for the electric vehicle, a pouch battery has been widely applied to the electric vehicle due to advantages such as a small size, a light weight, high energy density, and high safety. 
     However, in a charging process, the pouch battery is prone to abnormal phenomena such as overcharging, thereby resulting in a problem such as explosion of the pouch battery. 
     SUMMARY 
     The present disclosure provides a battery system and an electric vehicle, to resolve a technical problem of overcharging of a pouch battery. 
     In order to achieve the above object, the present disclosure provides a battery system, including at least one series circuit, a pouch battery and at least one first cell connected to the pouch battery in series being disposed in the series circuit, and a current interrupt device being disposed on the first cell; and the current interrupt device of the first cell being configured to interrupt an internal current of the first cell when at least one of the pouch battery and the first cell is abnormal. 
     In some embodiments, the series circuit includes a plurality of first cells connected to the pouch battery in series, the plurality of first cells being sequentially connected in series or being alternately connected in series. 
     In some embodiments, the series circuit includes a plurality of first cells connected to the pouch battery in series, the plurality of first cells being connected in parallel to form a battery pack to be connected to the pouch battery in series. 
     In some embodiments, the first cell includes a housing, a core accommodated in the housing, a cover plate encapsulating the housing, an inner electrode terminal located at an inner side of the cover plate, and an outer electrode terminal located at an outer side of the cover plate, the inner electrode terminal being electrically connected to the core, and the current interrupt device being disposed on the cover plate and electrically connected to the outer electrode terminal and the inner electrode terminal respectively. 
     In some embodiments, the housing is one of an aluminium housing, a steel housing, and a plastic housing, and a thickness of the housing is 0.4 mm to 1.5 mm. 
     In some embodiments, the current interrupt device includes a score member and a flipping member, the score member being electrically connected to the inner electrode terminal, and the flipping member being electrically connected to the score member and the outer electrode terminal respectively and being in gas communication with an inside of the first cell. 
     In some embodiments, the score member includes a score region in which a score is formed, a first welding region to be electrically connected to the flipping member, and a second welding region to be electrically connected to the inner electrode terminal, and the flipping member can act under an effect of air pressure to break the score, the score being disposed around the first welding region, and at least one of the first welding region and the second welding region being disposed in a plane different from a plane in which the score is disposed. 
     In some embodiments, the score is disposed in a plane different from planes in which the first welding region and the second welding region are disposed. 
     In some embodiments, a boss protruding from the score region is formed on the score member, the first welding region being formed on an upper surface of the boss and parallel to the score region, and an annular welding joint being disposed at an outer periphery of the upper surface. 
     In some embodiments, a ring wall protruding in a direction same as a direction in which the boss protrudes is formed at an outer periphery of the score region, an upper edge of the ring wall being flush with an upper edge of the boss in a height direction, and an outer wall of the ring wall being to be electrically connected to the inner electrode terminal. 
     In some embodiments, the second welding region, the score region, and the first welding region are sequentially arranged from outside to inside in a radial direction, and form a step structure gradually approaching the flipping member from outside to inside, and the score is disposed around the first welding region. 
     In some embodiments, a ring wall protruding in a direction opposite to a direction in which the boss protrudes is formed at the outer periphery of the score region, the second welding region being formed at an outer periphery of the ring wall and parallel to the score region, and an annular welding joint being formed at an outer periphery of the second welding region. 
     In some embodiments, a sidewall of the boss and the ring wall are perpendicular to the score region respectively. 
     In some embodiments, the first welding region, the score region, and the second welding region respectively form a ring structure. 
     In some embodiments, a first connection region to be electrically connected to the score member and a second connection region to be electrically connected to the outer electrode terminal are formed on the flipping member, and a deformation cushion region is further formed on the flipping member, the deformation cushion region being disposed in the first connection region. 
     In some embodiments, the flipping member is a sheet structure in the shape of a cone, a small end of the cone forming the first connection region, and a large end of the cone away from the score member forming the second connection region. 
     In some embodiments, the deformation cushion region forms an annular groove structure surrounding the first connection region. 
     In some embodiments, a radial cross-section of the annular groove structure is arc-shaped or angular. 
     In some embodiments, a support ring is connected between a lower side of an outer periphery of the flipping member and the cover plate in a sealing manner, and an outer periphery of the outer electrode terminal is electrically connected to an upper side of the outer periphery of the flipping member. 
     In some embodiments, a support flange is formed on an inner wall of the support ring, the outer peripheries of the flipping member and the outer electrode terminal being supported on an upper surface of the support flange. 
     The present disclosure further provides an electric vehicle, including the battery system provided in the present disclosure. 
     According to the foregoing technical solutions, the at least one first cell connected to the pouch battery in series is disposed in the series circuit and the current interrupt device is disposed on the first cell, so that explosion of the pouch battery due to an abnormality in a charging process can be avoided, and safety of the pouch battery can be improved during working. 
     Other features and advantages of the present disclosure will be described in detail in the following specific implementations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification, which are used to explain the present disclosure in combination with the following specific implementations, and do not constitute a limitation to the present disclosure. In the accompanying drawings: 
         FIG. 1  is a schematic structural diagram of a battery system according to an implementation of the present disclosure, where a current interrupt device on a first cell is not started, and a series circuit is in a normal working state. 
         FIG. 2  is a schematic structural diagram of a battery system according to an implementation of the present disclosure, where a current interrupt device on a first cell is started normally, and a series circuit is in an open state. 
         FIG. 3  is a schematic structural diagram of a battery system according to another implementation of the present disclosure, where a current interrupt device on a first cell is not started, and a series circuit is in a normal working state. 
         FIG. 4  is a schematic structural diagram of a battery system according to another implementation of the present disclosure, where a current interrupt device on a first cell is started normally, and a series circuit is in an open state. 
         FIG. 5  is a schematic structural diagram of a battery system according to another implementation of the present disclosure, where a current interrupt device on one of first cells in a battery pack is started by mistake, and a series circuit is still in a normal working state. 
         FIG. 6  is a partial three-dimensional schematic exploded view of a battery system according to an implementation of the present disclosure. 
         FIG. 7  is a partial three-dimensional schematic exploded view of a battery system according to an implementation of the present disclosure. 
         FIG. 8  is a partial three-dimensional schematic exploded view of a battery system according to another implementation of the present disclosure. 
         FIG. 9  is a partial three-dimensional schematic exploded view of a battery system according to another implementation of the present disclosure. 
         FIG. 10  is a cross-sectional view of a current interrupt device according to a first implementation of the present disclosure. 
         FIG. 11  is a cross-sectional view of a current interrupt device according to a second implementation of the present disclosure. 
         FIG. 12  is a three-dimensional schematic diagram of a score member according to the second implementation of the present disclosure. 
         FIG. 13  is a three-dimensional schematic diagram of a flipping member according to the first implementation of the present disclosure. 
     
    
    
     DESCRIPTION OF REFERENCE NUMERALS 
       10 . Pouch battery;  11 . Pouch cell;  20 . First cell;  21 . Housing;  22 . Cover plate;  23 . Outer electrode terminal;  231 . Through hole;  24 . Inner electrode terminal;  26 . Support ring;  261 . Support flange;  30 . Current interrupt device;  31 . Score member;  311 . Score;  312 . Score region;  313 . First welding region;  314 . Second welding region;  315 . Boss;  316 . Ring wall;  32 . Flipping member;  321 . First connection region;  322 . Second connection region;  323 . Deformation cushion region;  40 . Power connection sheet;  50 . Conductive connection member;  60 . Battery pack. 
     DETAILED DESCRIPTION 
     The following describes the specific implementations of the present disclosure in detail with reference to the accompanying drawings. It should be understood that the specific implementations described herein are merely used to describe and explain the present disclosure, but are not intended to limit the present disclosure. 
     In the present disclosure, without the contrary explanation, the directional terms such as “upper, lower, left, and right” are usually defined based on the drawing direction of the corresponding accompanying drawings, and “inside and outside” refers to the inside and outside of the contour of the corresponding component. 
       FIG. 1  to  FIG. 9  are schematic structural diagrams of a battery system according to the present disclosure.  FIG. 10  and  FIG. 11  are schematic structural diagrams of a current interrupt device according to the present disclosure.  FIG. 12  shows a score member according to the present disclosure.  FIG. 13  shows a flipping member according to the present disclosure. As shown in  FIG. 1  to  FIG. 5 , the battery system includes at least one series circuit, a pouch battery  10  and at least one first cell  20  connected to the pouch battery  10  in series being disposed in the series circuit, and a current interrupt device  30  being disposed on the first cell  20 . The current interrupt device  30  on the first cell  20  is configured to interrupt an internal current of the first cell  20  to disconnect the entire series circuit when one or more cells in the series circuit are abnormal. The one or more cells are at least one of the pouch battery  10  and the first cell  20 . 
     In an implementation of the present disclosure, the pouch battery  10  may include one pouch cell  11  or may include a plurality of pouch cells  11 . The plurality of pouch cells  11  may be a plurality of pouch cells  11  connected in series, or a plurality of pouch cells  11  connected in parallel, or a plurality of pouch cells  11  connected in series and in parallel. The pouch cell  11  includes a pouch core and an electrode connected to the pouch core in series. An outer housing of the pouch cell  11  is an aluminum plastic film. 
     In the present disclosure, the series circuit may include one first cell  20  connected to the pouch battery  10  in series, or may include a plurality of first cells connected to the pouch battery  10  in series. The plurality of first cells  20  may be connected in parallel to form a battery pack (such as a battery pack  60  shown in  FIG. 3  to  FIG. 5 ) to be connected to the pouch battery  10  in series, or the plurality of first cells  20  may be connected to each other in series and then connected to the pouch battery  10  in series. In this solution, the plurality of first cells  20  and the plurality of pouch cells  11  may be alternately connected in series in the series circuit. 
     In the present disclosure, the first cell  20  includes a housing  21 , a core accommodated in the housing, a cover plate  22  encapsulating the housing  21 , an inner electrode terminal  24  located at an inner side of the cover plate  22 , and an outer electrode terminal  23  located at an outer side of the cover plate  22 . The inner electrode terminal  24  is electrically connected to the core, and the outer electrode terminal  23  may complete current input and output through various electrode lead-out members  40 . The current interrupt device  30  may be disposed on the cover plate and is electrically connected to the outer electrode terminal  23  and the inner electrode terminal  24  respectively to control current input and output of the electrode terminals. In some embodiments, the housing is one of an aluminum housing, a steel housing, and a plastic housing, and a thickness of the housing is 0.4 mm to 1.5 mm. 
     In some embodiments, as shown in  FIG. 1 , that the current interrupt device  30  is not started means that the core and the electrode terminal are conducted, that is, the electrical connection between the outer electrode terminal  23  and the inner electrode terminal  24  is normal, and the current input and output may be performed normally to complete charging and discharging of the battery system. 
     As shown in  FIG. 2 , when one or more cells in the series circuit are abnormal, a heating temperature of the first cell  20  increases, and air pressure inside the cell increases, so that the current interrupt device  30  disposed on the first cell  20  is started to cut off the electrical connection between the outer electrode terminal  23  and the inner electrode terminal  24 . In this way, the current input and output of the electrode terminal are interrupted, so that the series circuit is in an open state, thereby preventing thermal runaway of the battery system. 
     It should be noted that in  FIG. 1  and  FIG. 2 , the battery system includes one series circuit, and only one first cell is disposed in the series circuit. In other implementations of the present disclosure, the battery system may also have a plurality of series circuits, and a plurality of first cells may also be disposed in each series circuit. The plurality of first cells may be connected in series at any position in the series circuit, or the plurality of first cells may be connected in parallel to form a battery pack to be connected to a pouch battery in series. 
     For example, in  FIG. 3  to  FIG. 5 , two first cells are connected in parallel to form a battery pack  60  to be connected to the pouch battery  10  in series. As shown in  FIG. 3 , when the series circuit is in a normal state, a current interrupt device  30  in each first cell  20  of the battery pack  60  does not work. In this case, an inner electrode terminal  24  and an outer electrode terminal  23  of each first cell  20  are electrically connected normally, that is, an internal current of each first cell  20  is conducted, and the entire series circuit is normal in this case. 
     As shown in  FIG. 4 , when one or more cells in the series circuit are abnormal, the current interrupt device  30  in the first cell  20  of the battery pack  60  is triggered to be enabled, so that internal currents of first cells  20  (first cells Cn(a) and Cn(b)) are all in a disconnected state, thereby causing the entire series circuit to be disconnected. In this way, overcharging of the pouch battery  10  is avoided and protection of the pouch battery  10  is implemented. 
     As shown in  FIG. 5 , when a current interrupt device  30  on a first cell  20  in the battery pack  60  (such as a current interrupt device on the first cell Cn(b)) is started abnormally, an internal current of the first cell Cn(b) is interrupted, but an internal current of the other first cell Cn(a) connected to the first cell Cn(b) in parallel is still in a conducting state. Thus, the series circuit maintains a normal working state, and only a capacity is reduced. Therefore, a risk that the current interrupt device is abnormally enabled and the series circuit is powered off can be reduced, so that an external control system based on the battery system has sufficient emergency time for related processing. 
     In the present disclosure, as shown in  FIG. 6  to  FIG. 9 , the pouch battery  10  may include one or more pouch cells  11 . When the pouch battery  10  includes a plurality of pouch cells  11 , the plurality of pouch cells  11  are connected in series through a conductive connection member  50 , or the plurality of pouch cells  11  are connected in parallel through a conductive connection member  50 , or the plurality of pouch cells  11  are connected in series and in parallel through a conductive connection member  50 . Each pouch cell  11  includes a pouch core and an electrode electrically connected to the pouch core. Electrodes between two adjacent pouch cells are connected in series or in parallel through the conductive connection member  50 . 
     In the present disclosure, one pouch cell  11  in the pouch battery  10  is connected to the first cell  20  or the battery pack  60  in series, or a plurality of pouch cells  11  in the pouch battery  10  are respectively connected to a plurality of first cells  20  or a plurality of battery packs  60  in series. In some embodiments, a positive electrode (negative electrode) of one pouch cell  11  in the pouch battery  10  and a negative electrode (positive electrode) of the first cell  20  may be welded in series through a power connection sheet  40  or a positive electrode (negative electrode) of one pouch cell  11  in the pouch battery  10  and a negative lead (positive lead) of the battery pack may be welded in series. The pouch cell  11  connected to the first cell  20  or the battery pack in series may be located at an end of the pouch battery  10  or in the middle of the pouch battery  10 . According to the present disclosure, a positive electrode (negative electrode) of a pouch cell  11  at an end of one side or ends of two sides of the pouch battery  10  and the negative electrode (positive electrode) of the first cell  20  are welded through the power connection sheet  40 , or a positive electrode (negative electrode) of a pouch cell  11  at an end of one side or ends of two sides of the pouch battery  10  and the negative lead (positive lead) of the battery pack are welded through the power connection sheet  40 . 
     In an implementation, as shown in  FIG. 6  and  FIG. 7 , the positive electrode (negative electrode) of the first cell  20  is electrically connected to the negative electrode (positive electrode) of the pouch cell  11  at the end of one side of the pouch battery  10  through the power connection sheet  40 , so that the first cell  20  and the pouch battery  10  are connected in series, and pouch cells  11  are connected in series or in parallel through the conductive connection member  50  to form the pouch battery  10 . 
     In another implementation, as shown in  FIG. 8  and  FIG. 9 , the electrodes of the pouch cell  11  at the ends of the two sides of the pouch battery  10  are electrically connected to the first cell  20  through the power connection sheet  40 , so that the pouch battery  10  is connected to two first cells in series in the series circuit. 
     According to the battery system provided in the present disclosure, a pouch cell  11  at the end of the pouch battery  10  may also be electrically connected to the positive lead of the battery pack or the negative lead of the battery pack through the power connection sheet  40 , so that a series connection between the pouch battery  10  and the battery pack  60  is completed. The battery pack  60  includes the plurality of first cells  20  connected in parallel. According to the battery system provided in the present disclosure, when the pouch battery  10  includes a plurality of pouch cells connected in series or in parallel, the first cell  20  may be connected in series in the middle of the pouch battery  10 , or the battery pack  60  may be connected in series in the middle of the pouch battery  10 . 
     In the present disclosure, the current interrupt device  30  may be disposed at any appropriate position on the cover plate  22 . In some embodiments, in an implementation, as shown in  FIG. 6  to  FIG. 9 , the current interrupt device  30  may be mounted on one of outer electrode terminals  23  of the first cell  20 , and a part of the power connection sheet  40  covers the current interrupt device  30 , and the other part extends. 
     Reliability of the current interrupt device as an important safety measure is crucial, that is, the current interrupt device needs to make a response quickly. 
     In the present disclosure, all current interrupt devices in the various implementations are mechanical structures for sensing air pressure. In some embodiments, the current interrupt device is in gas communication with an inside of a cell and can interrupt an internal current of the cell under an effect of the air pressure. In some embodiments, current transfer can be interrupted by disconnecting internal components, thereby cutting off charging and discharging of the cell in time. A source of the used air pressure is as follows: For example, when the cell is in an abnormal state such as overcharging, gas is generated inside the cell, resulting in an increase of the air pressure inside the housing, or when a temperature rises due to an abnormality during use of the cell, the air pressure inside the cell increases, resulting in pneumatic power that drives the current interrupt device. 
     For example, in the implementations of  FIG. 10  and  FIG. 11 , the current interrupt device  30  has a score member  31  and a flipping member  32  electrically connected to the score member  31 , and the electrical connection between the flipping member  32  and the score member  31  can be cut off under the effect of the air pressure. In the implementations of the present disclosure, a weak score may be made on a corresponding component to break the structure, thereby cutting off the electrical connection. In some embodiments, a score  311  is formed on the score member  31 . In other words, under the effect of the internal air pressure, the score  311  may be broken through a flipping action of the flipping member  32 , so as to cut off the electrical connection between the flipping member and the score member, thereby interrupting the current transfer. 
     A reason for adopting this method is that, for example, in the field of power batteries, a relatively large flowing current is required. Therefore, a welding structure between the score member  31  and the flipping member  32  needs to be stable to prevent the large current from fusing the welding structure. Therefore, by disposing the score  311  on the score member  31 , that is, making a weak portion with strength less than that of other regions in the corresponding part, the score member  31  and the flipping member  32  can be completely disconnected. The score is usually disposed around the welding region between the score member and the flipping member, to ensure complete disconnection between the score member and the flipping member. 
     The score member  31  and the flipping member  32  in the two implementations of the present disclosure are described below with reference to  FIG. 10  and  FIG. 11 . 
     As shown in  FIG. 10  and  FIG. 11 , the present disclosure provides a score member in a current interrupt device. The score member  31  includes a score region  312  in which a score  311  is formed, a first welding region  313  to be electrically connected to the flipping member  32 , and a second welding region  314  to be electrically connected to the inner electrode terminal. The flipping member  32  can act under an effect of air pressure to break the score  311  so as to cut off an electrical connection to the score member  31 . After the flipping member  32  breaks the score  311 , an electrical connection between the flipping member  32  and the second welding region  314  is cut off, thereby cutting off an electrical connection to the inner electrode terminal  24 . In the present disclosure, the score  311  is disposed around the first welding region  313 , and the score  311  may be a ring surrounding the first welding region  313 . In addition, at least one of the first welding region  313  and the second welding region  314  is disposed in a plane different from a plane in which the score  311  is disposed. In other words, the plane on which the score  311  is located is different from the planes/plane on which the first welding region  313  and/or the second welding region  314  are/is located, so that not only mechanical impact on the score  311  on the score member  31  caused by an external force transmitted from the flipping member  32  can be effectively eliminated, but also thermal influence of welding stresses in the first welding region  313  and the second welding region  314  on a region in which the score  311  is located can be eliminated. In this way, reliability of the current interrupt device provided in the present disclosure is improved. The score  311  surrounding the first welding region  313  can be broken under the effect of the air pressure inside the cell. In this case, the electrical connection between the flipping member  32  and the score member  31  is completely cut off to interrupt the current. 
     As shown in  FIG. 10  and  FIG. 11 , the score  311  is disposed in a plane different from planes in which the first welding region  313  and the second welding region  314  are disposed, that is, a plane in which the score  311  is located is different from a plane in which the first welding region  313  is located and the plane in which the score  311  is located is also different from a plane in which the second welding region  314  is located. More preferably, the score member  31  includes a score region  312  and a boss  106  protruding from the score region  312 , the first welding region  313  is formed on the boss  315 , and the score  311  is formed on the score region  312  and disposed around the boss  315 , so that the plane in which the score is located is different from the plane in which the first welding region is located and the plane in which the second welding region is located. In some embodiments, the first welding region  313  is formed by an upper surface of the boss  315  and is parallel to the score region  312 , and an annular welding joint is disposed on an outer periphery of the upper surface. 
     As shown in  FIG. 11  and  FIG. 12 , in a second implementation, the second welding region  314 , the score region  312 , and the first welding region  313  are sequentially arranged from outside to inside in a radial direction, and form a step structure gradually approaching the flipping member  32  from outside to inside. The second welding region  314  and the score region  312  are also located on different planes. The formed step structure has a cushion effect, so that the thermal influence of the welding stresses of the two welding regions on the score  311  can be avoided, and an external force transmitted from the inner electrode terminal can also be cushioned, making the current interrupt device more reliable. 
     In the two implementations of the present disclosure, as shown in  FIG. 10  or  FIG. 11 , the score member  31  includes a score region  312  and a boss  315  protruding from the score region  312 . The first welding region  313  is formed on the boss  315 , and the score  311  is formed on the score region  312  and disposed around the boss  315 . In this way, the score and the first welding region are disposed on different planes. In some embodiments, the first welding region  313  is formed on an upper surface of the boss  315  and is parallel to the score region  312 , and an annular welding joint is disposed at an outer periphery of the upper surface. Correspondingly, a first connection region  321  on the flipping member  32  may form a connecting hole for accommodating the boss  315 . In this way, the outer periphery of the boss  315  and an inner wall of the connecting hole are firmly welded by using the annular welding joint. The boss  315  may be a cylindrical structure or a through hole may be disposed in an axial direction of the cylindrical structure, as shown in  FIG. 4 . In other implementations, the score and the first welding region may be disposed on different planes by using various convex or concave structures. 
     As shown in  FIG. 10 , in a first implementation, in order to establish an electrical connection to the inner electrode terminal  24  of the battery, an accommodating groove is usually disposed on the top end of the inner electrode terminal  24 . Accordingly, a ring wall  316  protruding in a direction the same as a direction in which the boss  315  protrudes is formed at an outer periphery of the score region  312 , an upper edge of the ring wall  316  being flush with an upper edge of the boss  315  in a height direction. In addition, an outer wall of the ring wall is to be electrically connected to the inner electrode terminal  24  of the battery to form the first welding region  313 . The outer wall fits a shape of a groove wall of the accommodating groove of the inner electrode terminal  24  and is welded through the annular welding joint. In this implementation, the score member  31  can be completely accommodated in the accommodating groove of the inner electrode terminal  24 . The structure is stable. 
     As shown in  FIG. 11 , in the second implementation, an accommodating groove is still disposed on the inner electrode terminal  24 , the boss  315  of the score member  31  extending out of the accommodating groove. In some embodiments, a ring wall  316  protruding in a direction opposite to the direction in which the boss  315  protrudes is formed at the outer periphery of the score region  312 , and the second welding region  314  is formed at an outer periphery of the ring wall  316  and is parallel to the score region  312 , so that the score member  31  forms the step structure. An annular welding joint to be electrically connected to the inner electrode terminal  24  of the battery is formed at an outer periphery of the second welding region  314 . In some embodiments, a lower surface of the second welding region  314  may be placed on the bottom wall of the accommodating groove, and the outer periphery and a sidewall of the accommodating groove are welded through the annular welding joint. Likewise, the structure is also stable. 
     In the second implementation, as shown in  FIG. 11 , a sidewall of the boss  315  and the ring wall  316  are perpendicular to the score region  312  respectively. In other embodiments, there may be a specific angle, for example, a Z-shaped step is formed. In addition, the first welding region  313 , the score region  312 , and the second welding region  314  may each be a ring structure, that is, the first welding region  313  has a central hole. In other embodiments, the first welding region  313  may have no central hole. 
     The score member  31  in the two implementations is described above, and the flipping member  32  in the two implementations is described below. 
     A first connection region  321  to be electrically connected to the score member  31  and a second connection region  322  to be electrically connected to an outer electrode terminal  23  of a battery are formed on the flipping member  32 . In addition, a deformation cushion region  323  is further formed on the flipping member  32 , the deformation cushion region  323  being disposed between the first connection region  321  and the second connection region  322  and around the first connection region  321 . The deformation cushion region means that the region may be deformed prior to the flipping member  32 , the first connection region  321 , the second connection region  322 , and the score member  31  under an effect of an external force, so as to cushion the external force. Accordingly, impact of the external force on the first connection region  321  and the score  311  on the score member  31  is reduced, improving the reliability of the current interrupt device. 
     In the two implementations of the present disclosure, the flipping member  32  is a sheet structure in the shape of a cone, a small end of the cone forming the first connection region  321 , and a large end of the cone away from the score member  31  forming the second connection region  322 . The cone structure may be used to dispose the two connection regions on different planes and provide a space for the flipping member  32  to flip upward under a force to break the score  311 . In other possible implementations, the flipping member may also be an elastic flat member or the like. 
     As shown in  FIG. 10  and  FIG. 11 , the deformation cushion region  323  in the present disclosure forms an annular groove structure surrounding the first connection region  321 . In this way, a deformation cushion effect can be achieved through relative movement between groove walls of the annular groove under an effect of an external force. In other possible implementations, the deformation cushion region  323  may also be implemented by a structure such as a deformation chamber or elastic materials. 
     As shown in  FIG. 10  and  FIG. 13 , in the first implementation, a radial cross-section of the annular groove structure is arc-shaped, for example, is a semi-circle protruding toward the outer electrode terminal  23 . In this way, an external force transmitted from the second connection region  322  can be absorbed through the deformation of the arc-shaped groove wall, thereby reducing impact on the first connection region  321  and the score member  31 . 
     As shown in  FIG. 11 , in the second implementation, the radial cross-section of the annular groove structure may further be angular, so that both sides of the angular shape are two groove walls and can also be deformed under the effect of external force. In some embodiments, in the second implementation, the boss  315  of the score member  31  protrudes from the accommodating groove of the inner electrode terminal. In this case, in order to save space, the angular ring-shaped groove may be designed to protrude facing the score member  31 , and the bottom of the groove is formed on one side of the boss, so that the entire flipping member  32  can be formed into a Z-shaped structure to achieve cushioning of the external force. 
     As shown in  FIG. 10  and  FIG. 11 , in the two implementations of the present disclosure, in order to ensure that the flipping member can be acted by gas inside the battery, a support ring  26  is connected between a lower side of an outer periphery of the flipping member  32  and the cover plate  22  in a sealing manner, and an outer periphery of the outer electrode terminal  23  is electrically connected to an upper side of the outer periphery of the flipping member  32 . In this way, the gas generated inside the battery can act on the flipping member  32  without leakage. In order to enable the flipping member  32  to act normally, the outer electrode terminal  23  forms a cap structure and may have a through hole  231  for discharging gas during acting of the flipping member  32 , thereby preventing the acting of the flipping member from being restored under the action of the air pressure. In addition, in two implementations in which the cover plate  22  is conductive and insulative, an insulating material or a conductive material may be selected for the support ring  26  for supporting. Generally, the support ring  26  may be a ceramic ring so that the cover plate  22  is insulative. In some embodiments, a support flange  261  is formed on an inner wall of the support ring  26 , the outer peripheries of the flipping member  32  and the outer electrode terminal  23  being supported on an upper surface of the support flange  261 , so as to ensure stable working of the current interrupt device. 
     The first cell provided in the present disclosure further includes a housing, the core being accommodated in the housing. The first cell further includes a cover plate assembly that encapsulates the housing, where the inner electrode terminal is electrically connected to the core, and the flipping member is in gas communication with an interior of the housing. The cover plate assembly includes a cover plate, an inner electrode terminal  213  located at an inner side of the cover plate, and an outer electrode terminal  214  located at an outer side of the cover plate. The inner electrode terminal  213  and the outer electrode terminal  214  are electrically connected by using the foregoing current interrupt device. The outer electrode terminal  214  is electrically connected to the flipping member  222 , and the score member  221  is electrically connected to the inner electrode terminal  213 . 
     The inner electrode terminal  213  is welded to an inner lead-out member electrically connected to a core. In some embodiments, a welding hole may be formed on the inner lead-out member. The inner electrode terminal  213  forms a columnar structure and is embedded in the welding hole to be welded to the inner lead-out member. In order to prevent the cover plate from being energized, a cover plate insulating member is disposed between the cover plate and the inner lead-out member, and the inner electrode terminal may pass through the cover plate insulating member with a gap to be welded to the score member. In order to ensure sealing performance, a support ring is further included. A lower end of the support ring is welded to the cover plate. A ceramic material may be used to ensure the insulation of the current interrupt device and the cover plate. A duct is formed on the cover plate to facilitate mounting of the current interrupt device. In addition, in order to ensure that the gas inside the battery can act on the flipping member  222 , an air hole is formed on the inner lead-out member, so that the gas can act on the flipping member  222  through the air hole. 
     A battery system is disclosed, including at least one series circuit, a pouch battery and at least one first cell connected to the pouch battery in series being disposed in the series circuit, and a current interrupt device being disposed on the first cell; and the current interrupt device of the first cell being configured to interrupt an internal current of the first cell when at least one of the pouch battery and the first cell is abnormal. 
     In some embodiments, the series circuit includes a plurality of first cells connected to the pouch battery in series, the plurality of first cells being sequentially connected in series or being alternately connected in series. 
     In some embodiments, the series circuit includes a plurality of first cells connected to the pouch battery in series, the plurality of first cells being connected in parallel to form a battery pack to be connected to the pouch battery in series. 
     In some embodiments, the first cell includes a housing, a core accommodated in the housing, a cover plate encapsulating the housing, an inner electrode terminal located at an inner side of the cover plate, and an outer electrode terminal located at an outer side of the cover plate, the inner electrode terminal being electrically connected to the core, and the current interrupt device being disposed on the cover plate and electrically connected to the outer electrode terminal and the inner electrode terminal respectively. 
     In some embodiments, the housing is one of an aluminum housing, a steel housing, and a plastic housing, and a thickness of the housing is  0 . 4  mm to  1 . 5  mm. 
     In some embodiments, the current interrupt device includes a score member and a flipping member, the score member being electrically connected to the inner electrode terminal, and the flipping member being electrically connected to the score member and the outer electrode terminal respectively and being in gas communication with an inside of the first cell. 
     In some embodiments, the score member includes a score region in which a score is formed, a first welding region to be electrically connected to the flipping member, and a second welding region to be electrically connected to the inner electrode terminal, the flipping member can act under an effect of air pressure to break the score, and the flipping member may be disconnected from the inner electrode terminal after breaking the score, the score being disposed around the first welding region, and at least one of the first welding region and the second welding region being disposed in a plane different from a plane in which the score is disposed. 
     In some embodiments, the score is disposed in a plane different from planes in which the first welding region and the second welding region are disposed. 
     In some embodiments, a boss protruding from the score region is formed on the score member, the first welding region being formed on an upper surface of the boss and parallel to the score region, and an annular welding joint being disposed at an outer periphery of the upper surface. 
     In some embodiments, a ring wall protruding in a direction same as a direction in which the boss protrudes is formed at an outer periphery of the score region, an upper edge of the ring wall being flush with an upper edge of the boss in a height direction, and an outer wall of the ring wall being to be electrically connected to the inner electrode terminal. 
     In some embodiments, the second welding region, the score region, and the first welding region are sequentially arranged from outside to inside in a radial direction, and form a step structure gradually approaching the flipping member from outside to inside, and the score is disposed around the first welding region. 
     In some embodiments, a ring wall protruding in a direction opposite to a direction in which the boss protrudes is formed at the outer periphery of the score region, the second welding region being formed at an outer periphery of the ring wall and parallel to the score region, and an annular welding joint being formed at an outer periphery of the second welding region. 
     In some embodiments, a sidewall of the boss and the ring wall are perpendicular to the score region respectively. 
     In some embodiments, the first welding region, the score region, and the second welding region respectively form a ring structure. 
     In some embodiments, a first connection region to be electrically connected to the score member and a second connection region to be electrically connected to the outer electrode terminal are formed on the flipping member, and a deformation cushion region is further formed on the flipping member, the deformation cushion region being disposed in the first connection region. 
     In some embodiments, the flipping member is a sheet structure in the shape of a cone, a small end of the cone forming the first connection region, and a large end of the cone away from the score member forming the second connection region. 
     In some embodiments, the deformation cushion region forms an annular groove structure surrounding the first connection region. 
     In some embodiments, a radial cross-section of the annular groove structure is arc-shaped or angular. 
     In some embodiments, a support ring is connected between a lower side of an outer periphery of the flipping member and the cover plate in a sealing manner, and an outer periphery of the outer electrode terminal is electrically connected to an upper side of the outer periphery of the flipping member. 
     In some embodiments, a support flange is formed on an inner wall of the support ring, the outer peripheries of the flipping member and the outer electrode terminal being supported on an upper surface of the support flange. 
     Correspondingly, the present disclosure further provides an electric vehicle, including the foregoing battery system. 
     The implementations of the present disclosure are described above in detail with reference to the accompanying drawings, but the present disclosure is not limited to the specific details in the above implementations. Various simple variations may be made to the technical solutions of the present disclosure within the scope of the technical idea of the present disclosure, and such simple variations shall all fall within the protection scope of the present disclosure. 
     It should be further noted that the specific technical features described in the above specific embodiments may be combined in any suitable manner without contradiction. To avoid unnecessary repetition, various possible combinations are not further described in the present disclosure. 
     In addition, the various embodiments of the present disclosure may be combined without departing from the idea of the present disclosure, and such combinations shall also fall within the scope of the present disclosure.