Patent Publication Number: US-2023134692-A1

Title: Battery pack and apparatus using battery pack as power supply

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2021/082424, filed on Mar. 23, 2021, which claims priority to Chinese Patent Application No. 202010580242.8, filed on Jun. 23, 2020, both of which are incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to the technical field of batteries, and more particularly, to a battery pack and an apparatus using the battery pack as a power supply. 
     BACKGROUND 
     As an important component of an electric automobile, a battery pack is used for providing power to the electric automobile. The battery pack includes at least one battery module; the battery module includes at least one battery cell; and the battery cell is provided with an anti-explosion assembly. When thermorunaway takes place on a single battery cell, the anti-explosion assembly will be started, and a short circuit is prone to occur on the whole battery module, which poses a safety risk. Therefore, a need exists to solve this problem. 
     SUMMARY OF THE INVENTION 
     The present disclosure provides a battery pack and an apparatus using the battery pack as a power supply to improve a structure of the battery pack. 
     Some embodiments of the present disclosure provide a battery pack, including: 
     a box body; 
     a battery module mounted in the box body, the battery module comprising an anti-explosion assembly; 
     a module electrical connection piece mounted on the battery module; and 
     a first protecting assembly mounted in the box body and configured to protect the module electrical connection piece when an ejecta discharged from the anti-explosion assembly impacts the module electrical connection piece. 
     In some embodiments, the first protecting assembly comprises protection sheet wrapped around the module electrical connection piece. 
     In some embodiments, the first protecting assembly comprises a shell, and the module electrical connection piece is positioned in the shell. 
     In some embodiments, the first protecting assembly comprises: 
     a first insulating member mounted on a side wall and/or a bottom wall of the box body corresponding to a position of the module electrical connection piece, wherein the first insulating member is configured to isolate the box body from the module electrical connection piece. 
     In some embodiments, the battery pack further includes: 
     a second protecting assembly mounted in the box body and facing toward the anti-explosion assembly, wherein the second protecting assembly is configured to protect the box body from an impact by the ejecta discharged from the anti-explosion assembly. 
     In some embodiments, the second protecting assembly bends toward the anti-explosion assembly along edges of two sides in a direction of a connecting line between the anti-explosion assembly and the module electrical connection piece, to enclose the anti-explosion assembly in a space formed by the second protecting assembly and the battery module. 
     In some embodiments, the battery pack further includes: 
     a beam provided with a notch, wherein the module electrical connection piece penetrates through the notch and is configured to electrically connect an external electric appliance; 
     The first protecting assembly further comprises a second insulating member mounted on the notch, and the second insulating member is configured to isolate the module electrical connection piece from the beam. 
     In some embodiments, the battery pack further includes: 
     a pressing plate fixedly connected with the beam and configured to fix the battery module. 
     In some embodiments, a material of the first protecting assembly is mica. 
     Some embodiments of the present disclosure provide an apparatus using a battery pack as a power supply, comprising the battery pack provided by any technical scheme of the present disclosure. 
     A module electrical connection piece in the battery pack provided in the technical scheme is provided with a first protecting assembly, and the first protecting assembly protects the module electrical connection piece when an ejecta discharged from the anti-explosion assembly impacts the module electrical connection piece. Further, the first protecting assembly effectively reduce protecting failure of the module electrical connection piece caused by the injection discharged from the anti-explosion assembly, such that probability of electric connection between the module electrical connection piece and a box body is further reduced. Finally, the probability of secondary short circuit of the battery pack is reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic structural diagram of an automobile using a battery pack as a power supply according to some embodiments of the present disclosure; 
         FIG.  2    is a schematic diagram of secondary short circuit of the battery pack; 
         FIG.  3    is an exploded view of a box body of the battery pack in an opened state according to some embodiments of the present disclosure; 
         FIG.  4   a    is a schematic three-dimensional structural diagram of a module electrical connection piece of the battery pack according to some embodiments of the present disclosure; 
         FIG.  4   b    is a schematic front view of  FIG.  4     a;    
         FIG.  4   c    is an A-A enlarged section view of  FIG.  4     b;    
         FIG.  5   a    is a schematic top view of the battery pack with its box cap removed according to some embodiments of the present disclosure; 
         FIG.  5   b    is a schematic B-B section view of  FIG.  5     a;    
         FIG.  5   c    is a partially enlarged schematic view of Area C in  FIG.  5     b;    
         FIG.  6   a    is another schematic three-dimensional diagram of the battery pack with its box cap removed according to some embodiments of the present disclosure; 
         FIG.  6   b    is a partially enlarged schematic view of Area D in  FIG.  6     a;    
         FIG.  7    is an exploded view of a battery pack according to some other embodiments of the present disclosure; 
         FIG.  8    is a schematic three-dimensional structural diagram of a second protecting assembly of a battery pack according to yet some other embodiments of the present disclosure; 
         FIG.  9   a    is a schematic diagram showing a breakdown structure of a battery pack according to yet some other embodiments of the present disclosure; 
         FIG.  9   b    is a schematic top view of a battery pack with its box cap removed according to some embodiments of the present disclosure; 
         FIG.  9   c    is a schematic E-E section view of  FIG.  9     b;    
         FIG.  10    is a schematic diagram showing a breakdown structure of a battery cell of the battery pack according to the embodiments of the present disclosure; 
         FIG.  11    is a schematic structural diagram of a stacked electrode assembly; and 
         FIG.  12    is a schematic structural diagram of a wound electrode assembly. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     The technical scheme provided by the present disclosure will be described in more detail below with reference to  FIGS.  1  to  12   . 
     To describe the technical scheme of each embodiment of the present disclosure more clearly, a coordinate system is established in  FIG.  3   , and subsequent description about directions of a battery pack is made based on the coordinate system. Referring to  FIG.  3   , a battery cell  21  forms two layers of 6*2 battery arrays, wherein an axis x is a length direction of a battery module  2 , i.e., an arrangement direction of six battery cells  21 . An axis Y is perpendicular to the axis X, and the axis Y represents a width direction of the single battery array, i.e., an arrangement direction of two battery cells  21  in the 6*2 battery arrays. An axis Z is perpendicular to a plane formed by the axis X and the axis Y, and the axis Z represents a height direction of the battery module  2 . In description of some embodiments of the present disclosure, terms “upper” and “lower” are relative to the direction of the axis Z. The length direction of the box body  1  is consistent with the length direction of the battery pack, the width direction of the box body  1  is consistent with the width direction of the battery pack, and the height direction of the box body  1  is consistent with the height direction of the battery pack. 
     In the description of some embodiments of the present disclosure, it is to be understood that the orientations or positions represented by the terms of “top”, “bottom”, “inside”, “outside”, and the like are based on the accompanying drawings, they are merely for ease of a description of the present disclosure and a simplified description instead of being intended to indicate or imply the apparatus or element to have a special orientation or to be configured and operated in a special orientation. Thus, they cannot be understood as limiting of the present disclosure. 
     Referring to  FIG.  2   , the battery module  2  includes one or more battery cell sequences. The battery cell sequence includes at least one battery cell  21 . Each of the battery cells  21  includes an outer shell  211  (a position of the outer shell  211  is seen in  FIG.  10   ) and an anti-explosion assembly  20  mounted on the outer shell  211  (a position of the anti-explosion assembly  20  is seen in  FIG.  3   ). It is found by inventors that when thermorunaway takes place on a certain single battery cell  21  in the battery module  2 , a high-temperature and high-pressure ejecta air flow ejected by the anti-explosion assembly  20  of the battery cell  21  will impact a module electrical connection piece  3 , such that an insulating sleeve  30  on a surface of the module electrical connection piece  3  (a position of the insulating sleeve  30  is seen in  FIG.  4   a   ) cracks and fails, and the module electrical connection piece  3  loses insulation and heat insulation protection. Under the high-temperature air flow, the module electrical connection piece  3  losing protection will be fused. In this case, if any position of the module electrical connection piece  3  is in conducting contact with a box body  1 , all battery cells  21  between this position and the runaway battery cell  21  is short-circuited, resulting in short-circuited failure of a plurality of battery cells  21 . The battery module  2  will emit a lot of heat, which causes a severe safety risk. Therefore, it is necessary to protect the module electrical connection piece  3  of the battery module  2  in a thermorunaway state. By adopting the technical scheme provided by the embodiments of the present disclosure, occurrence of a short circuit in a major loop is effectively reduced or even avoided when thermorunaway takes place on the single battery cell  21 . 
     Referring to  FIG.  1   , some embodiments of the present disclosure provide an apparatus  100  using a battery pack as a power supply. The apparatus includes the battery pack provided by any one technical scheme of the present disclosure. The apparatus is specifically a traffic apparatus, an energy storage electric cabinet and the like. The traffic apparatus is, for example, an electric automobile, a steamer, an unmanned aerial vehicle and the like. The battery pack is arranged at a bottom of a vehicle body, and adopts a rechargeable battery. 
     Referring to  FIGS.  3  to  4     c , some embodiments of the present disclosure provide a battery pack, which includes a box body  1 , a battery module  2 , a module electrical connection piece  3 , and a first protecting assembly  4 . 
     Referring to  FIG.  3   , in some embodiments, the box body  1  includes a box cap  12  and a lower box body  13 . The box body  1  is of a similarly rectangular structure, and there are four inner side walls of the box body  1 : two first side walls  141  arranged oppositely along a Y direction and two second side walls  142  arranged oppositely along an X direction. The first side walls  141  and the second side walls  142  are fixedly connected. 
     The lower box body  13  and the box cap  12  enclose an accommodation cavity  11 , and the battery module  2  is mounted in the accommodation cavity  11  of the box body  1 . The box body  1  and the battery module  2  are detachably connected or are fixed by glue. By adopting the above implementation mode, connection between the battery module  2  and the box body  1  is stable and reliable, which improves safety and reliability of the battery pack. 
     The battery module  2  includes one or more battery cell sequences. An electric connecting mode among the battery cell sequences is arranged as serial connection, parallel connection or parallel-series connection as needed, to implement electric performance needed by the battery pack. With continued reference to  FIG.  3   , two rows of battery cell sequences  21  are arranged in the box body along a width direction (i.e., the direction of the axis Y) of the battery pack. In an actual application, three or more rows of battery cells sequences are provided. As needed, in the actual use, one or more layers of battery cell sequences are further arranged in the height direction of the battery pack, i.e., the direction of the axis Z in  FIG.  3   . 
     The module electrical connection piece  3  is mounted in the box body  1 , and the module electrical connection piece  3  is configured to output electric energy of the battery module  2  outside the box body  1  of the battery pack. Specifically, one end of the module electrical connection piece  3  is electrically connected with the electrical connection piece  22  at an output end of the battery module  2 , and the other end of the module electrical connection piece  3  is electrically connected with an electric appliance positioned outside the box body  1  of the battery pack. The electric appliance positioned outside the box body  1  is also referred to as an external electric appliance. The external electric appliance is, for example, a controller, a motor, an electric control box and the like. 
     Referring to  FIG.  3    to  FIG.  4   b   , the module electrical connection piece  3  is bended and includes a first connection piece  31  and a second connection piece  32  connected integrally. End portions of the first connection piece  31  and the second connection piece  32  are both provided with connecting ends  33 . One of the connecting ends  33  is configured to electrically connect the electrical connection piece  22  at the output end of the battery module  2 , and the other connecting end  33  is configured to electrically connect the external electric appliance. 
     The first protecting assembly  4  is configured to protect the module electrical connection piece  3  when an ejecta discharged from the anti-explosion assembly  20  impacts the module electrical connection piece  3 . It is a phenomenon of reducing electric connection between the module electrical connection piece  3  under the circumstance of being melted and deformed due to impact of the high-temperature and high-pressure ejecta and the box body  1 . It means that the first protection assembly  4  is configured to insulate and isolate the box body  1  from the module electrical connection piece  3  under the high-temperature and high-pressure condition. The ejecta refers to the high-temperature and high-pressure air flow or even an air flow and an electrolyte with sparks and flames generated in the battery during thermal failure of the battery cell  21 , and is ejected when the anti-explosion valve is opened. 
     In some embodiments, a material of the first protecting assembly  4  is mica. The first protecting assembly  4  adopts mica powder, a relatively thin mica plate or other structures. The first protecting assembly  4  includes a plurality of scattered blocks, a plurality of spliced blocks or an integral block. Mica resists high temperature and protect thermal impact well. The material of the first protecting assembly  4  is suitable for various implementation modes of the first protecting assembly  4  introduced below. 
     Referring to  FIG.  4   a    to  FIG.  4   c   , in some embodiments, the first protecting assembly  4  includes a shell  41 , and the module electrical connection piece  3  is positioned in the shell  41 . Here, most region of the module electrical connection piece  3  is positioned in the shell  41  to play a protecting role. The shell  41  has various structural forms, for example, a single plate which is only arranged on a surface of the module electrical connection piece  3  subjected to the strongest impact, or is of an “L”-shaped or “U”-shaped protecting structure formed by combining a plurality blocks. The outer side of the surface of the module electrical connection piece  3  aligned with the ejecta is provided with the shell  41  to protect the module electrical connection piece  3 . 
     The shell  41  certainly as much as possible wraps the surface of the module electrical connection piece  3  to realize comprehensive protection. The material of the shell  41  is, for example, mica or other materials with similar performance. In different regions of the module electrical connection piece  3 , the shell  41  is different in thickness. For example, in the region with strong impact, the shell  41  is large in thickness. For example, in the region with not strong impact, the shell  41  is small in thickness. The structure realizes more targeted protection and reduce the material of the shell  41  needed, and thus manufacturing costs are lowered. It is to be noted that an insulating sleeve  30  made from a polyolefin material is originally arranged outside the module electrical connection piece  3 . When the shell  41  is arranged, the insulating sleeve  30  outside the module electrical connection piece  3  is either reserved or removed. In the case as shown in  FIG.  4   a    to  FIG.  4   c   , the insulating sleeve  30  outside the module electrical connection piece  3  is reserved, and the shell  41  directly wraps outside of the insulating sleeve  30 . 
     A protecting process of the battery pack provided by the embodiments of the present disclosure is introduced below: the anti-explosion assemblies  20  of the plurality of battery cells  21  and the module electrical connection piece  3  are positioned in the box body. Once thermorunaway takes place on a certain battery cell  21 , the ejecta air flow generated in the battery cell  21  is discharged via the anti-explosion assembly  20  in the battery cell  21 , and the high-temperature and high-pressure ejecta air flow will impact the module electrical connection piece  3 . According to the technical scheme, the first protecting assembly  4  is arranged, and the first protecting assembly  4  protects the module electrical connection piece  3  to reduce or even prevent melting and deforming failure of the module electrical connection piece  3  caused by the ejecta air flow. It is to be noted that the material of the module electrical connection piece  3  typically is aluminum, whose melting point is 660° C. When the ejecta air flow is strong, the temperature of the ejecta air flow far exceeds the melting point of aluminum, so that the module electrical connection piece  3  is melted to splash. 
     Referring to  FIG.  5   a    to  FIG.  5   c   , in some other embodiments, the first protecting assembly  4  includes protection sheet  40  wrapping the module electrical connection piece  3 . The protection sheet  40  wraps the module electrical connection piece  3  integrally, and a part of regions of the protection sheet  40  are overlapped with each other. The overlapping portion of the protection sheet  40  is pasted together by glue. It is to be noted that when the protection sheet  40  is provided, the insulating sleeve  30  outside the module electrical connection piece  3  is either reserved or removed. In the case as shown in  FIG.  5   a    to  FIG.  5   c   , the insulating sleeve  30  outside the module electrical connection piece  3  is reserved, and the protection sheet  40  directly wraps outside of the insulating sleeve  30 . The protection sheet  40  has a better protecting effect, when the high-temperature and high-pressure ejecta impacts the protection sheet, the ejecta impacts a surface of the protection sheet  40 . As long as the protection sheet  40  is free of a cracking phenomenon, the insulating sleeve  30  positioned in the protection sheet  40  is always prevented from cracking and falling due to impact by the high-temperature and high-pressure ejecta, such that the module electrical connection piece  3  is better protected, and a condition that the whole battery module is prone to short circuit due to thermorunaway of the battery cell  21  is prevented. 
     In other embodiments, the protection sheet  40  wraps an impacted key region of the module electrical connection piece  3 , and the key region is tested according to a test. Alternatively, the protection sheet  40  wraps, as much as possible, the surface of the module electrical connection piece  3 . The material of the protection sheet  40  is, for example, mica paper or other materials capable of resisting high-temperature impact. The number of the wrapping layers of the protection sheet  40  are one and more. Different wrapping thicknesses is provided in different regions. For example, in the regions with strong impact, the wrapping protection sheet  40  is more in number of layers and the finally formed wrap is large in thickness; or thicker protection sheet  40  is adopted directly. For example, in the regions with not strong impact, the wrapping protection sheet  40  is few in number of layers and the finally formed wrap is small in thickness; or thinner protection sheet  40  is adopted directly. 
     In some other embodiments, referring to  FIG.  6   a    and  FIG.  6   b   , the first protecting assembly  4  includes a first insulating member  42 , the first insulating member  42  is mounted in a side wall  14  or a bottom wall  15  of the box body  1  corresponding to the position of the module electrical connection piece  3 , and an annotating position of the bottom wall  15  is referred to  FIG.  3   . The first insulating member  42  is configured to block at least a part of the side walls  14  of the box body  1 , to isolate the box body  1  from the module electrical connection piece  3 . The first insulating member  42  blocks the box body  1  to play a protecting role. 
     Referring to  FIG.  6   a    and  FIG.  6   b   , the side walls  14  of the box body  1  corresponding to the position of the module electrical connection piece  3  refer to the first side wall  141  and the second side wall  142  corresponding to the module electrical connection piece in the box body  1 . The so called bottom wall  15  of the box body  1  corresponding to the position of the module electrical connection piece  3  refers to the bottom wall  15  under the position of the modular electric connections piece  3  of the box body  1 . The module electrical connection piece  3  is fused by the high-temperature and high-pressure ejecta air flow discharged from the anti-explosion assembly  20 , such that a short circuit is caused by an electrical connection between the module electrical connection piece  3  and the side wall  14  and the bottom wall  15  of the box body  1 . For this reason, the first insulating member  42  is arranged on the above position. According to the above technical scheme, at least one of the side wall  14  and the bottom wall  15  of the box body  1  corresponding to the position of the module electrical connection piece  3  is provided with the first insulating member  42 . The first insulating member  42  insulates and isolates the box body  1  from the module electrical connection piece  3 , to reduce or even prevent a short circuit of the whole battery module due to thermorunaway of the battery cell  21 . 
     The first insulating member  42  is, for example, a mica plate or a material with similar performance. A plurality of first insulating members  42  is arranged, and some of the first insulating members  42  are fixed to the side wall  14  of the box body  1 , and some other first insulating members  42  are fixed to the bottom wall  15  of the box body  1 . A connecting mode of the first insulating members  42  and the box body  1  is a pasting or similar mode. 
     It is to be noted that the first protecting assembly simultaneously employs two or three of the shell  41 , the protection sheet  40 , and the first insulating member  42  to realize multiple protection to prevent the short circuit which occurs when some protection fails. 
     Referring to  FIG.  7    to  FIG.  9   c   , in some other embodiments, the battery pack further includes a second protecting assembly  10 , the second protecting assembly  10  is mounted in the box body  1  and faces toward the anti-explosion assembly  20 , and the second protecting assembly  10  is configured to protect the box body  1  from an impact by the ejecta discharged from the anti-explosion assembly  20 . 
     Referring to  FIG.  7    or  FIG.  9   c   , after the second protecting assembly  10  is arranged, an exhaust channel S is formed among the second protecting assembly  10 , the battery module  2 , and the first side wall  141  of the box body  1 .  FIG.  9   c    shows the position of the exhaust channel S. A flowing direction of an air flow in the exhaust channel S is as shown in an arrowhead P 1 , referring to  FIG.  7    or  FIG.  9   a   . The second protecting assembly  10  is aligned with the anti-explosion assembly  20  of each of the battery cells  21 . The high-temperature and high-pressure ejecta ejected from the anti-explosion assembly  20  of the battery cell  21  directly impacts the second protecting assembly  10  after being ejected, such that the ejecta is prevented from directly impacting the box body  1 , and thus the box body  1  is prevented from being damaged. In addition, the second protecting assembly  10  guides the ejecta ejected from the anti-explosion assembly  20 , such that most ejecta air flows are discharged along the exhaust channel S formed by the second protecting assembly  10  and the battery module  2 . Therefore, exhaust efficiency is improved. On the other hand, due to the presence of the second protecting assembly  10 , the ejecta air flow ejected from the anti-explosion assembly  20  is gathered, and the gathered air flow has stronger impact on the module electrical connection pieces  3  positioned on two sides of the exhaust channel S. At this moment, it is more important to provide protection on the module electrical connection pieces  3 . When only the insulating sleeve  30  is provide in a scheme adopting the related art, annotation of the insulating sleeve  30  is referred to  FIG.  4   a   . The insulating sleeve  30  is prone to cracking and falling under impact, which easily short-circuits the entire battery module. Arrangement of the first protecting assembly  4  introduced above effectively reduces or even prevents a secondary short circuit of the battery module. To guarantee a good protecting effect, the first protecting assembly  4  needs to use a material that resists an instantaneous high temperature of over 1,000° C. and a continuous high temperature of 800° C., for example, mica or other materials with such performance. 
     The second protecting assembly  10  adopts various structural forms, for example, split or integral form. The two cases will be described in detail below. Referring to  FIG.  7   , in some embodiments, the second protecting assembly  10  bends toward the anti-explosion assembly  20  along edges of two sides in a direction of a connecting line between the anti-explosion assembly  20  and the module electrical connection piece  3 , to enclose the anti-explosion assembly  20  in a space formed by the second protecting assembly  10  and the battery module  2 . The space is the exhaust channel S, and an annotation of the exhaust channel S is referred to  FIG.  9   c   . In this way, probability that the ejecta from the anti-explosion assembly  20  burns batteries around the battery cell  21  subjected to thermal failure is reduced or even prevented. In addition, it is also reduced probability that a short circuit is caused by contact between a busbar  23  of the battery cell  21  melted and spurted under the action of the ejecta and the box body  1 . 
     Referring to  FIG.  7   ,  FIG.  8   ,  FIG.  9   a    or  FIG.  9   c   , upper and lower edges of the second protecting assembly  10  are bended after being mounted in position and are bended towards a side of the anti-explosion assembly  20 . The second protecting assembly  10  is substantially C-shaped, such that a section of the exhaust channel S corresponding to the second protecting assembly  10  is substantially closed at top and bottom ends. At the moment, the ejecta ejected from the anti-explosion assembly  20  of the thermorunaway battery cell  21  is only discharged from two ends of the exhaust channel S along the length direction. That is, the second protecting assembly  10  further limits the flowing direction of the air flow while playing a comprehensive protecting role, such that a strength of the air flow becomes stronger, and the ejecta has stronger impact on the module electrical connection pieces  3  positioned on two sides of the exhaust channel S. If the first protecting assembly  4  introduced above is not arranged, in this case, it is easier for the module electrical connection pieces  3  to fail and deform under the impact of the ejecta. After the first protecting assembly  4  introduced above is arranged, the probability that the module electrical connection pieces  3  fail and deform under impact of the ejecta is reduced or even prevented effectively under a premise that the second protecting assembly  10  is arranged, such that occurrence of the short circuit is further avoided. 
     To achieve a good protecting effect, a thickness of the second protecting assembly  10  is set within a range of 0.5-3 mm, and a lap width between the second protecting assembly  10  and a part connected with the second protecting assembly  10  is 3-10 mm. Based on such a design, a hot air flow/flame ejected by thermorunaway is prevented from roasting a side surface of the battery cell  21  with the largest area. Meanwhile, the second protecting assembly  10  and the part (for example, a beam  5  introduced below) connected with the second protecting assembly  10  are riveted by means of a plastic rivet. In this way, in one aspect, a short circuit between the battery cell  21  and the box body caused due to using a metal connecting piece is avoided. In another aspect, it is guaranteed a good connection between the second protecting assembly  10  and the box body, such that it is avoidable that position offset of the second protecting assembly  10  is caused by the ejecta discharged from an anti-explosion valve after thermorunaway of the battery, and thus a negative effect on the protecting role of the second protecting assembly  10  is avoided. 
     In some embodiments, to guarantee a good protecting effect of the second protecting assembly, the second protecting assembly  10  adopts a mica plate and materials with similar performance. Referring to  FIG.  6   a   ,  FIG.  6   b   ,  FIG.  7    and  FIG.  9   a    together, in these embodiments, the battery pack further includes a beam  5 . A surface of the battery cell  21  provided with the anti-explosion assembly  20  is parallel to the beam  5 , and the second protecting assembly  10  introduced above is arranged between the surface of the battery cell  21  provided with the anti-explosion assembly  20  and the beam  5 . After the beam  5  is arranged, the second insulating portion  102  of the second protecting assembly  10  is attached and fixed to the maximum side surface of the beam  5 , thereby simplifying the fixing difficulty of the second protecting assembly  10 . The beam  5  is provided with a notch  51 , and the module electrical connection piece  3  penetrates through the notch  51  and is configured to electrically connect an external electric appliance. The first protecting assembly  4  further includes a second insulating member  43  mounted on the notch  51 , and the second insulating member  43  is configured to isolate the module electrical connection piece  3  from the beam  5 . 
     Referring to  FIG.  6   b    and  FIG.  7   , the notch  51  of the beam  5  is further provided with the second insulating member  43 , and the second insulating member  43  insulates and isolates the beam  5  form the module electrical connection piece  3 . The second insulating member  43  includes, for example, a first mica plate  431  and a second mica plate  432 . The notch  51  is substantially L-shaped, and the notch  51  includes a side surface  52  and a bottom surface  53 . The module electrical connection piece  3  is placed on the bottom surface  53  of the notch  51  or has a certain gap with the bottom surface  53  of the notch  51 . The first mica plate  431  is fixed to the side surface  52  of the notch  51 , and the second mica plate  432  is fixed to the bottom surface  53  of the notch  51 . A fixing mode of the first mica plate  431  and the second mica plate  432  is pasting. 
     Referring to  FIG.  7   a    and  FIG.  9   a   , in these embodiments, the battery pack further includes a pressing plate  6  configured to fix the battery module  2 . The pressing plate  6  is mounted and fixed to the beam  5 . Besides a role of mounting the pressing plate  6 , the beam  5  further segments an inner space of the box body  1 , so that battery modules in other spaces are prevented from being affected after thermorunaway of the battery module in some space to cause severe accidents. 
     Referring to  FIG.  7   , in some embodiments, the second protecting assembly  10  is fixedly connected with at least one of the pressing plate  6 , the beam  5  and the box body  1 . The second protecting assembly  10  includes a first insulating portion  101 , a second insulating portion  102  and a third insulating portion  103 . In an embodiment, the three portions are independent and are not connected one another. Specifically, the first insulating portion  101  is fixedly connected with the pressing plate  6  and the second insulating portion  102  are fixedly connected with the beam  5 . The third insulating portion  103  is fixedly connected with the bottom wall of the box body  1 . The first insulating portion  101 , the second insulating portion  102  and the third insulating portion  103  is fixed to the box body  1  by other ways of gluing, bolt locking or slot designing and the like. The second protecting assembly  10  is in the split structural design and is connected with the box body  1 , so that it is easier to mount and position the second protecting assembly  10  while saving the mounting space. The first insulating portion  101 , the second insulating portion  102  and the third insulating portion  103  are of strip-type structures, so that the second protecting assembly  10  is matched with peripheral parts well. 
     Certainly, referring to  FIG.  8   , in some other embodiments, the second protecting assembly  10  is of an integral structure. The first insulating portion  101 , the second insulating portion  102  and the third insulating portion  103  are integral, and the second protecting assembly is further mounted by connecting any one of the three with the pressing plate  6 , the beam  5  or the box body  1 . 
     Referring to  FIG.  9   a    to  FIG.  9   c   , in some other embodiments, in order to facilitate connection between the battery module and the external circuit, the second side wall  142  of the box body  1  is provided with a high voltage connector  7 , and the position of the high voltage connector  7  is seen in  FIG.  9   a   . The module electrical connection piece  3  is electrically connected with the external electric appliance via the high voltage connector  7  mounted on the box wall. With continued reference to  FIG.  9   a   , in some other embodiments, the second side wall  142  of the box body  1  is provided with the anti-explosion valve  9  of the battery pack. 
     Referring to  FIG.  10    to  FIG.  12   , a structure that is adopted by the battery cell  21  is introduced in the embodiments below. 
     Referring to  FIG.  10   , the battery cell  21  includes an outer shell  211 , an electrode assembly  212  arranged in the outer shell  211 , a connecting piece  213  arranged on the end portion of the electrode assembly  212  and a cover plate  214  connected with the outer shell  211 . The cover plate  214  is provided with an electrode terminal  215  and an anti-explosion assembly  20 . 
     Manufacturing modes of the electrode assembly  212  include a stacked type and a wound type. As shown in  FIG.  11   , the stacked electrode assembly is the electrode assembly  212  formed by cutting an anode plate  212   a,  a cathode plate  212   b  and a diaphragm  212   c  into specified dimensions and then stacking the anode plate  212   a,  the diaphragm  212   c,  and the cathode plate  212   b.  As shown in  FIG.  12   , the wound electrode assembly is formed by winding the anode plate  212   a,  the cathode plate  212   b,  and the diaphragm  212   c.  Surfaces of the stacked electrode assembly and the wound electrode assembly with the largest areas are surfaces with maximum expansion deformation. 
     In the description of the present disclosure, it is to be understood that the orientations or positions represented by the terms of “center”, “longitudinal”, “transverse”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside” , “outside”, and the like are based on the accompanying figures, they are merely for ease of a description of the present disclosure and a simplified description instead of being intended to indicate or imply the apparatus or element to have a special orientation or to be configured and operated in a special orientation. Thus, they cannot be understood as limiting of the present disclosure. 
     Finally, it should be noted that the foregoing embodiments are merely intended for describing the technical scheme of the present disclosure, but not for limiting the present disclosure. Although the present disclosure is described in detail with reference to the preferred embodiments, persons of ordinary skill in the art should understand that they still make modifications to the specific embodiments of the present disclosure or make equivalent replacements to some technical features without departing from the spirit of the technical scheme of the present disclosure, which shall fall within the scope of the technical scheme claimed in the present disclosure.