Patent Publication Number: US-2023163419-A1

Title: Battery cell, battery, power consuming apparatus, and method and apparatus for manufacturing battery cell

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of International Application No. PCT/CN2021/109908, filed Jul. 30, 2021, the entire content of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present application relates to the technical field of batteries, and in particular, relates to a battery cell, a battery, a power consuming apparatus, and a method and apparatus for manufacturing a battery cell. 
     BACKGROUND ART 
     At present, lithium ion batteries have become predominant products of secondary batteries because of their outstanding advantages such as high energy density and good cycling performance, and are widely used in fields such as portable electrical appliances, power vehicles, mobile phones, and spacecrafts. 
     People require lithium batteries to have better electrical performance while paying attention to the safety performance of the batteries in use. Lithium precipitation is one of the main factors affecting the electrical performance and the safety performance of the batteries. Once lithium precipitation occurs in a cell core, not only will the electrical performance of the battery be reduced, but also it is likely to form dendrites with the accumulation of lithium precipitation. The dendrites may puncture a separator and cause a short circuit in the battery, causing a safety hazard. 
     Therefore, how to effectively reduce the risk of lithium precipitation in batteries has become a technical problem to be solved urgently at present. 
     SUMMARY OF THE DISCLOSURE 
     Embodiments of the present application provide a battery cell, a battery, a power consuming apparatus, and a method and apparatus for manufacturing a battery cell, which can effectively improve the safety performance of the battery cell. 
     In a first aspect, an embodiment of the present application provides a battery cell, comprising a housing, an electrode assembly and a first support member. The housing is provided with an accommodating cavity. The electrode assembly is accommodated in the accommodating cavity, and comprises a main body portion and a thinned portion, wherein at least one end of the main body portion in a first direction is connected to the thinned portion, and a part of an electrode plate of the electrode assembly at the main body portion has a thickness greater than that of a part of the electrode plate of the electrode assembly at the thinned portion. The first support member is arranged corresponding to the thinned portion, and is configured to support the thinned portion when the electrode assembly is expanded. 
     In the technical solution described above, the first support member is arranged in the housing and corresponding to the thinned portion such that when the electrode assembly is expanded, the first support member supports the thinned portion, so that the thinned portion can be in a stressed state with the support of the first support member, alleviating the problems of rapid capacity decay and even thermal runaway caused by uneven stresses on the main body portion and the thinned portion of the electrode assembly and uneven polarization and therefore by the deposition of lithium ions and the formation of lithium dendrites during charging and discharging due to the fact that under conventional circumstances, the electrode plate has a smaller thickness at the thinned portion so that the thinned portion is not in contact with an inner wall of the housing or adjacent thinned portions are not in contact with each other and thus the thinned portion(s) cannot be stressed. In addition, the uneven stresses on the main body portion and the thinned portion of the electrode assembly will also generate side reaction products such as metal lithium, lithium oxide, lithium fluoride and lithium carbonate. The side reaction products will consume lithium ions and the electrolytic solution, and affect the electrical conductivity, so that the capacity and the safety performance of the battery should be improved. Therefore, the provision of the first support member in the housing improves the capacity retention rate and the safety performance of the battery. 
     In some embodiments of the first aspect, the battery cell comprises a plurality of electrode assemblies, wherein the plurality of electrode assemblies are arranged side-by-side in a thickness direction of the battery cell; and the first support member comprises at least one first abutting portion, and at least one first abutting portion is arranged between the thinned portions of two adjacent electrode assemblies. 
     In the technical solution described above, in the case where the battery cell comprises a plurality of electrode assemblies arranged side-by-side in the thickness direction thereof and the first abutting portion of the first support member is arranged between the thinned portions of two adjacent electrode assemblies, when the electrode assemblies are expanded, adjacent parts of the thinned portions of the two adjacent electrode assemblies approach each other and press the first abutting portion, and the thinned portions are supported by the reaction force of the first abutting portion, so that the thinned portions of the two adjacent electrode assemblies can be in a stressed state with the support of the first abutting portion, reducing the risk of deposition of lithium ions and therefore lithium precipitation during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the electrode plates have a smaller thickness at the parts of the thinned portions between the two adjacent electrode assemblies so that the thinned portions are not in contact with each other and thus cannot be stressed. 
     In some embodiments of the first aspect of the present application, two first abutting portions are arranged between the thinned portions of two adjacent electrode assemblies, and the two first abutting portions are configured to abut against each other in the thickness direction of the battery cell when the electrode assemblies are expanded, so as to support the thinned portions. 
     In the technical solution described above, two first abutting portions are arranged between the thinned portions of two adjacent electrode assemblies, and each first abutting portion may be arranged corresponding to a thinned portion, so that as the electrode assemblies are expanded, the two first abutting portions are abutting against each other in the direction of approaching each other, and when the two first abutting portions abut against each other, they provide a reverse support force for the corresponding thinned portions, reducing the deposition of lithium ions and the generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the thinned portions of the two adjacent electrode assemblies have a smaller thickness so that the thinned portions are not in contact with each other and thus cannot be stressed. 
     In some embodiments of the first aspect of the present application, the first support member comprises a second abutting portion arranged between the thinned portion and an inner wall of the housing, the second abutting portion being configured to abut against the inner wall of the housing when the electrode assembly is expanded, so as to support the thinned portion. 
     In the technical solution described above, the second abutting portion is arranged between the thinned portion and the inner wall of the housing such that when the electrode assembly is expanded, the second abutting portion is supported between the thinned portion and the inner wall of the housing, so that the thinned portion can be in a stressed state with the support of the second abutting portion, reducing the risk of deposition of lithium ions and therefore lithium precipitation during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the electrode plate has a smaller thickness at the thinned portion so that the thinned portion is not in contact with the inner wall of the housing and thus the thinned portion cannot be stressed. 
     In some embodiments of the first aspect of the present application, the part of the electrode plate at the thinned portion has a thickness gradually decreasing in a direction in which the thinned portion faces away from the main body portion. 
     In the technical solution described above, the part of the electrode plate at the thinned portion has a thickness gradually decreasing in the direction in which the thinned portion faces away from the main body portion, so that in a rolling process of the electrode plate, the pressure received by the part of the electrode plate at the thinned portion is smaller, thereby reducing the risk of peeling or falling off of the active material from the thinned portion of the electrode plate, and reducing the possibility of cracking at the interface between the part of the electrode plate at the thinned portion and the part of the electrode plate at the main body portion. 
     In some embodiments of the first aspect of the present application, a part of the first support member corresponding to the thinned portion has a thickness gradually increasing in the direction in which the thinned portion faces away from the main body portion. 
     In the technical solution described above, since the part of the electrode plate at the thinned portion has a thickness gradually decreasing in the direction in which the thinned portion faces away from the main body portion, that is, the part of the electrode plate at the thinned portion has a gradually increasing distance from the opposite inner wall of the housing or the thinned portion of the adjacent electrode assembly in the direction in which the thinned portion faces away from the main body portion, the part of the first support member corresponding to the thinned portion having a thickness gradually increasing in the direction in which the thinned portion faces away from the main body portion can complement the thickness change of the part of the electrode plate at the thinned portion, so that when the electrode assembly is expanded, the thinned portion can be supported by the first support member to make the thinned portion be stressed as uniformly as possible. 
     In some embodiments of the first aspect of the present application, the battery cell further comprises a second support member or structure arranged corresponding to the main body portion, the second support member being configured to support the main body portion when the electrode assembly is expanded. 
     In the technical solution described above, the battery cell further comprises a second support member arranged corresponding to the main body portion such that when the battery cell is expanded, the second support member supports the main body portion, so that the main body portion is stressed as uniformly as possible, improving the polarization uniformity, and reducing the risk of deposition of lithium ions and generation of side reaction products during charging and discharging. The provision of the first support member and the second support member can alleviate the problems of lithium precipitation of the thinned portion and uneven expansion force of the main body portion. 
     In some embodiments of the first aspect of the present application, the second support member is connected to one end of the first support member in the first direction. 
     In the technical solution described above, the first support member is connected to the second support member such that the first support member and the second support member can be mutually restrained, relative displacement will not occur, and the mounting stability of the first support member and the second support member are improved, so that when the electrode assembly is expanded, the first support member can stably support the thinned portion, and the second support member can stably support the main body portion. 
     In some embodiments of the first aspect of the present application, the second support member and the first support member are of an integrally formed structure. 
     In the technical solution described above, the first support member and the second support member being of an integrally formed structure facilitates manufacturing, and can also reduce the number of steps for assembling the battery cell, and the integrally formed structure of the first support member and the second support member also has a good structural strength. 
     In some embodiments of the first aspect of the present application, a surface of the first support member facing away from the thinned portion is flush with a surface of the second support member facing away from the main body portion. 
     In the technical solution described above, the surface of the first support member facing away from the thinned portion is flush with the surface of the second support member facing away from the main body portion, such that when the surface of the second support member facing away from the main body portion is subjected to an abutting force in a direction facing the main body portion, the surface of the first support member facing away from the thinned portion is also subjected to an abutting force in a direction facing the thinned portion, so that the thinned portion and the main body portion are uniformly stressed. 
     In some embodiments of the first aspect of the present application, in a direction in which the first support member faces away from the thinned portion, a surface of the first support member facing away from the thinned portion protrudes from a surface of the main body portion or the surface of the first support member facing away from the thinned portion is flush with the surface of the main body portion. 
     In the technical solution described above, when the electrode assembly is expanded, the expansion amount of the main body portion is generally greater than the expansion amount of the thinned portion, so when the surface of the first support member facing away from the thinned portion protrudes from the surface of the main body portion in the direction in which the first support member faces away from the thinned portion, the protruding size can compensate for the difference in the expansion amount of the thinned portion relative to the main body portion during expansion, such that when the surface of the main body portion is subjected to an abutting force, the surface of the first support member facing away from the thinned portion is subjected to an abutting force in the direction facing the thinned portion, so that the thinned portion and the main body portion are uniformly stressed. When the surface of the first support member facing away from the thinned portion is flush with the surface of the main body portion, it is convenient to complete assembly of the battery cell. 
     In some embodiments of the first aspect of the present application, the electrode assembly has a central hole; and the battery cell further comprises a third support member which is inserted into the central hole and arranged corresponding to the thinned portion. 
     In the technical solution described above, when the electrode assembly is expanded, a part of the thinned portion will have a tendency to expand toward the center of the central hole, the third support member is inserted into the central hole and is arranged corresponding to the thinned portion, such that when the electrode assembly is expanded, the part of the thinned portion expanding toward the center of the central hole presses the third support member, and the thinned portion is supported with the reaction force of the third support member, so that the thinned portion expanding toward the center of the central hole can be in a stressed state, reducing the risk of deposition of lithium ions and generation of side reaction products during charging and discharging caused by uneven polarization due to the smaller thickness of the electrode plate at the thinned portion on the outer periphery of the central hole and the presence of the central hole so that the thinned portion is not in contact with the central hole and thus cannot be stressed. 
     In some embodiments of the first aspect of the present application, the first support member is arranged around an outer periphery of the thinned portion. 
     In the technical solution described above, the first support member is arranged around the outer periphery of the thinned portion, such that when the electrode assembly is expanded, the first support member can support the thinned portion at any position in the circumferential direction of the thinned portion, so that all the positions of the thinned portion in the circumferential direction can be stressed, and the thinned portion is uniformly polarized, reducing the risk of deposition of lithium ions and generation of side reaction products during charging and discharging. 
     In some embodiments of the first aspect of the present application, the first support member is fixed to the thinned portion. 
     In the technical solution described above, the first support member being fixed to the thinned portion enables the first support member to be closely attached to the thinned portion, so that during assembling of the battery cell and during charging and discharging of the battery cell, the first support member is not displaced relative to the electrode assembly. 
     In some embodiments of the first aspect of the present application, the electrode plate comprises a current collector and an active material layer arranged on a surface of the current collector, and the active material layer of the electrode plate has a greater thickness at the main body portion than at the thinned portion. 
     In the technical solution described above, in the rolling process of the electrode plate, the active material layer of the electrode plate may spread from the middle to two ends in the width direction and be accumulated, so the active material layer of the electrode plate having a greater thickness at the main body portion than at the thinned portion provides an accumulation compensation position for the active material layer accumulated from the middle to two ends, so that the thickness of the active material layer of the rolled electrode plate at the two ends in the width direction will not exceed the thickness thereof in the middle, reducing the accumulation amount of the active material layer at the two ends in the width direction. Moreover, the active material layer of the electrode plate having a greater thickness at the main body portion than at the thinned portion enables that in the rolling process of the electrode plate, the pressure received by the part of the electrode plate at the thinned portion is smaller, thereby reducing the risk of peeling or falling off of the active material from the thinned portion, and reducing the possibility of cracking at the interface between the part of the electrode plate at the thinned portion and the part of the electrode plate at the main body portion. 
     In a second aspect, an embodiment of the present application provides a battery, comprising a case and a battery cell provided in any embodiment of the first aspect, wherein the battery cell is accommodated in the case. 
     In the technical solution described above, since the battery cell of the battery is provided with a first support member in the housing, when the electrode assembly is expanded, the first support member supports the thinned portion, so that the thinned portion can be stressed, reducing the risk of rapid capacity decay and even thermal runaway and generation of side reaction products caused by uneven stresses on the electrode assembly, uneven polarization, the deposition of lithium ions and the formation of lithium dendrites during charging and discharging, and improving the safety performance and the electrical performance of the battery. 
     In a third aspect, an embodiment of the present application provides a power consuming apparatus, comprising any battery cell described in the first aspect. 
     In the technical solution described above, since the battery cell of the power consuming apparatus is provided with a first support member in the housing, when the electrode assembly is expanded, the first support member supports the thinned portion, so that the thinned portion can be stressed, reducing the risk of rapid capacity decay and even thermal runaway and generation of side reaction products caused by uneven polarization, the deposition of lithium ions and the formation of lithium dendrites during charging and discharging, and improving the safety performance and the electrical performance of the battery, thereby improving the safety of electricity consumption. 
     According to a fourth aspect, an embodiment of the present application provides a method for manufacturing a battery cell, the method comprising: 
     providing a housing, an electrode assembly and a first support member, wherein the housing is provided with an accommodating cavity, and the electrode assembly comprises a main body portion and a thinned portion, wherein at least one end of the main body portion in a first direction is connected to the thinned portion, and a part of an electrode plate of the electrode assembly at the main body portion has a thickness greater than that of a part of the electrode plate of the electrode assembly at the thinned portion; and 
     causing the electrode assembly and the first support member to be accommodated in the accommodating cavity, and arranging the first support member corresponding to the thinned portion, such that the first support member supports the thinned portion when the electrode assembly is expanded. 
     In the technical solution described above, the first support member is arranged in the housing and corresponding to the thinned portion such that when the electrode assembly is expanded, the first support member supports the thinned portion, so that the thinned portion can be in a stressed state with the support of the first abutting portion, reducing the risk of deposition of lithium ions and therefore lithium precipitation and generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the electrode plate has a smaller thickness at the thinned portion so that the thinned portion is not in contact with an inner wall of the housing or adjacent thinned portions are not in contact with each other and thus the thinned portion(s) cannot be stressed. 
     In a fifth aspect, an embodiment of the present application provides an apparatus for manufacturing a battery cell, the apparatus comprising: 
     a provision device configured to provide a housing, an electrode assembly and a first support member, wherein the housing is provided with an accommodating cavity, and the electrode assembly comprises a main body portion and a thinned portion, wherein at least one end of the main body portion in a first direction is connected to the thinned portion, and a part of an electrode plate of the electrode assembly at the main body portion has a thickness greater than that of a part of the electrode plate of the electrode assembly at the thinned portion; and 
     an assembly device configured to cause the electrode assembly and the first support member to be accommodated in the accommodating cavity, and to arrange the first support member corresponding to the thinned portion, such that the first support member supports the thinned portion when the electrode assembly is expanded. 
     In the technical solution described above, the assembly device can arrange the first support member in the housing and corresponding to the thinned portion such that when the electrode assembly is expanded, the first support member supports the thinned portion, so that the thinned portion can be in a stressed state with the support of the first abutting portion, reducing the risk of deposition of lithium ions and therefore lithium precipitation and generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the electrode plate has a smaller thickness at the thinned portion so that the thinned portion is not in contact with an inner wall of the housing or adjacent thinned portions are not in contact with each other and thus the thinned portion(s) cannot be stressed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to more clearly explain the technical solutions of the embodiments of the present application, the drawings being used in the embodiments will be described briefly below. It should be understood that the following drawings illustrate only some embodiments of the present application and are therefore not to be considered as a limitation on the scope thereof. For those of ordinary skill in the art, other relevant drawings can also be obtained from these drawings without any creative effort. 
         FIG.  1    is a schematic structural diagram of an electrode assembly in the related art; 
         FIG.  2    is a schematic structural diagram of a vehicle provided in some embodiments of the present application; 
         FIG.  3    is a schematic structural diagram of a battery provided in some embodiments of the present application; 
         FIG.  4    is a structural schematic diagram of the connection of a plurality of battery cells provided in some embodiments of the present application; 
         FIG.  5    is an exploded view of a battery cell provided in some embodiments of the present application; 
         FIG.  6    is a cross-sectional view of a battery cell provided in some embodiments of the present application after a first support member, an electrode assembly and a housing are assembled; 
         FIG.  7    is an enlarged view of part I in  FIG.  6   ; 
         FIG.  8    is a cross-sectional view of a battery cell provided in some other embodiments of the present application after a first support member, an electrode assembly and a housing are assembled; 
         FIG.  9    is an enlarged view of part II in  FIG.  8   ; 
         FIG.  10    is a cross-sectional view of a side-by-side arrangement of more than three electrode assemblies provided in some embodiments of the present application; 
         FIG.  11    is an enlarged view of part III in  FIG.  10   ; 
         FIG.  12    is a cross-sectional view of a side-by-side arrangement of more than three electrode assemblies provided in some other embodiments of the present application; 
         FIG.  13    is an enlarged view of part IV in  FIG.  12   ; 
         FIG.  14    is a schematic diagram of a side-by-side arrangement of two electrode assemblies; 
         FIG.  15    is a schematic diagram of a side-by-side arrangement of more than two electrode assemblies; 
         FIG.  16    is a schematic diagram of a battery cell with only one electrode assembly; 
         FIG.  17    is a cross-sectional view of a battery cell with only one electrode assembly; 
         FIG.  18    is a schematic structural diagram of a battery cell provided in some other embodiments of the present application; 
         FIG.  19    is a flow block diagram of a method for manufacturing a battery cell provided in some embodiments of the present application; and 
         FIG.  20    is a schematic structural diagram of an apparatus for manufacturing a battery cell provided in some embodiments of the present application. 
     
    
    
     List of reference signs:  1 —Electrode plate;  1   a —Current collector;  11   a —Coated portion;  12   a —Tab;  1   b —Active material layer;  1000 —Vehicle;  100 —Battery;  10 —Case;  11  —Accommodating space;  12 —First portion;  13 —Second portion;  20 —Battery cell;  21 —Housing;  211 —Opening;  212 —Accommodating cavity;  22 —Electrode assembly;  221 —Thinned portion;  222 —Main body portion;  223 —Straight portion;  224 —Bent portion;  225 —Central hole;  22   a —First edge electrode assembly;  22   b —Second edge electrode assembly;  22   c —Intermediate electrode assembly;  23 —End cap assembly;  231 —End cap;  232 —First electrode terminal;  233 —Second electrode terminal;  234 —Pressure relief mechanism;  24 —First support member or structure;  241 —First abutting portion;  2411 —First supporting face;  2412 —First abutting face;  242 —Second abutting portion;  2421 —Second supporting face;  2422 —Second abutting face;  25 —Second support member or structure;  26 —Third support member or structure;  30 —Bus component;  200 —Controller;  300 —Motor;  2000 —Apparatus for manufacturing a battery cell;  2100 —Provision device;  2200 —Assembly device; A—First direction; B—Thickness direction of a battery cell; and C—Length direction of an electrode assembly. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     In order to make the objectives, technical solutions and advantages of embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the embodiments described are some of, rather than all of, the embodiments of the present application. Generally, the assemblies of the embodiments of the present application described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. 
     Thus, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application as claimed, but is merely representative of the selected embodiments of the present application. All the other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application. 
     It should be noted that the embodiments in the present application and features in the embodiments may be combined with each other without conflicts. 
     It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures. 
     In the description of the embodiments of the present application, it should be noted that the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings or are orientations or positional relationships in which a product of the present application is conventionally placed when in use, or the orientations or positional relationships commonly understood by those skilled in the art, and are intended to facilitate the description of the present application and simplify the description only, rather than indicating or implying that the device or element referred to must have a particular orientation or be constructed and operated in a particular orientation, and will not to be interpreted as limiting the present application. In addition, the terms “first”, “second”, “third”, etc. are used for discriminative description purposes only, and shall not be construed as indicating or implying relative importance. 
     “A plurality of” appearing in the present application means two or more (including two). 
     In the present application, a battery cell may include a lithium ion secondary battery, a lithium ion primary battery, a lithium-sulfur battery, a sodium/lithium ion battery, a sodium ion battery or a magnesium ion battery, and the like, which is not limited in the embodiments of the present application. The battery cell may be cylindrical, flat, cuboid or in another shape, which is not limited in the embodiments of the present application. The battery cells are generally classified into three types depending on the way of packaging: cylindrical battery cells, prismatic battery cells and pouch battery cells, which also will not be limited in the embodiments of the present application. 
     A battery mentioned in the embodiments of the present application refers to a single physical module comprising one or more battery cells to provide a higher voltage and capacity. For example, the battery mentioned in the present application may comprise a battery module, a battery pack, or the like. The battery generally comprises a case for packaging one or more battery cells. The case can reduce the influence of liquid or other foreign matters on the charging or discharging of the battery cell. 
     The electrode assembly of the battery cell is the core component that realizes the charging and discharging functions. The battery cell comprises an electrode assembly and an electrolytic solution. The electrode assembly is composed of a positive electrode plate, a negative electrode plate and a separator. The battery cells operate mainly by means of metal ions moving between the positive electrode plate and the negative electrode plate. The positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer. A surface of the positive electrode current collector is coated with the positive electrode active material layer, the positive electrode current collector that is not coated with the positive electrode active material layer protrudes from the positive electrode current collector coated with the positive electrode active material layer, and the positive electrode current collector that is not coated with the positive electrode active material layer is used as a positive electrode tab. A lithium ion battery is taken as an example, the positive electrode current collector may be made of aluminum, and a positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganate, or the like. The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer. A surface of the negative electrode current collector is coated with the negative electrode active material layer, the negative electrode current collector that is not coated with the negative electrode active material layer protrudes from the negative electrode current collector coated with the negative electrode active material layer, and the negative electrode current collector that is not coated with the negative electrode active material layer is used as a negative electrode tab. The negative electrode current collector may be made of copper, and a negative electrode active material may be carbon, silicon, or the like. In order to ensure that no fusing occurs when a large current passes, a plurality of positive electrode tabs are provided and are stacked together, and a plurality of negative electrode tabs are provided and are stacked together. The separator may be made from PP (polypropylene), PE (polyethylene), or the like. In addition, the electrode assembly may be of a winding structure or a laminated structure, which is not limited in the embodiments of the present application. 
     In order to meet production demands, in a width direction of an electrode plate  1  (a positive electrode plate and/or a negative electrode plate), two ends of the electrode plate  1  need to be thinned, to prevent edge over-pressure and breakage of the electrode plate  1 . As shown in  FIG.  1   , the electrode plate  1  comprises a current collector  1   a  and an active material layer  1   b  coated on a surface of the current collector  1   a . The current collector  1   a  comprises a coated portion  11   a  coated with the active material layer  1   b  and a tab  12   a  that is not coated with the active material layer  1   b . The positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector comprises a first coated portion coated with the positive electrode active material layer and a positive electrode tab that is not coated with the positive electrode active material layer. The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer. The negative electrode current collector comprises a second coated portion coated with the negative electrode active material layer and a negative electrode tab that is not coated with the negative electrode active material layer. In a process of forming the electrode plate  1  or in a process of rolling the electrode assembly, it is generally necessary to roll the active material layer  1   b  of the electrode plate  1  to increase the density of the active material layer  1   b.    
     However, due to the existence of the active material layer  1   b , a thickness difference exists at the interface between the coated portion  11   a  and the tab  12   a  of the electrode plate  1 . Therefore, during rolling, stress may be concentrated on the interface between the active material layer  1   b  and the tab  12   a , resulting in that the active material layer  1   b  is peeled off, and cracks are generated in the current collector  1   a . In order to relieve stress, the thickness of the active material layer  1   b  at the end near the tab  12   a  is generally reduced, to form a region with a smaller thickness. In the electrode assembly, the region with a smaller thickness may increase the distance between the end of the active material layer  1   b  and other structures (such as an inner wall of a housing, and an adjacent electrode assembly), so that when the electrode assembly is expanded, all the region with a smaller thickness cannot be in contact with other structures (such as the inner wall of the housing, and the adjacent electrode assembly), and thus the region with a smaller thickness cannot be stressed like the region with a greater thickness, resulting in uneven polarization, causing deposition of lithium ions and generation of side reaction products and generation of side reaction products during charging and discharging and therefore lithium precipitation, which affects the performance of the secondary battery. The side reaction products comprise metal lithium, lithium oxide, lithium fluoride, lithium carbonate, etc., and the side reaction products will consume lithium ions and the electrolytic solution, and affect the electrical conductivity, so that the capacity and the safety performance of the battery should be improved. 
     In view of this, an embodiment of the present application provides a technical solution in which a first support member is provided in the housing. The first support member is arranged in the housing and corresponding to the thinned portion such that when the electrode assembly is expanded, the thinned portion can be in a stressed state with the support of the first support member, reducing the possibility of deposition of lithium ions and therefore lithium precipitation and generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the electrode plate has a smaller thickness at the thinned portion so that the thinned portion is not in contact with an inner wall of the housing or adjacent thinned portions are not in contact with each other and thus the thinned portion(s) cannot be stressed, thereby reducing the risk of lithium precipitation. 
     The technical solutions described in the embodiments of the present application are applicable to batteries and power consuming apparatuses using the batteries. 
     The power consuming apparatus may be a vehicle, a mobile phone, a portable apparatus, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle may be a fuel vehicle, a gas vehicle or a new-energy vehicle. The new-energy vehicle may be a battery electric vehicle, a hybrid vehicle, an extended-range vehicle, or the like. The spacecraft includes an airplane, a rocket, an aerospace plane, a spaceship, etc. The electric toy includes a stationary or mobile electric toy, such as a game machine, an electric toy car, an electric toy ship, and an electric toy airplane. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an electric impact drill, a concrete vibrator, and an electric planer. The power consuming apparatuses mentioned above are not specially limited in the embodiments of the present application. 
     For ease of description, an example in which the power consuming apparatus refers to a vehicle  1000  is used for description in the following embodiments. 
     Referring to  FIG.  2   , a battery  100  is provided inside the vehicle  1000 , and the battery  100  may be provided at the bottom, the front or the back of the vehicle  1000 . The battery  100  may be configured to supply power to the vehicle  1000 . For example, the battery  100  may be used as an operating power supply of the vehicle  1000 . 
     The vehicle  1000  may further comprise a controller  200  and a motor  300 . The controller  200  is configured to control the battery  100  to supply power to the motor  300 , for example, to satisfy the working power requirements during the starting, navigation and traveling of the vehicle  1000 . 
     In some embodiments of the present application, the battery  100  can not only serve as an operating power supply for the vehicle  1000 , but also serve as a driving power supply for the vehicle  1000 , in place of or partially in place of fuel or natural gas, to provide driving power for the vehicle  1000 . 
     Referring to  FIG.  3   , the battery  100  comprises a case  10  and a battery cell  20 . The battery cell  20  is received in the case  10 . The case  10  is configured to provide an accommodating space  11  for the battery cell  20 . In some embodiments, the case  10  may comprise a first portion  12  and a second portion  13 . The first portion  12  and the second portion  13  covers each other to define the accommodating space  11  for accommodating the battery cell  20 . Of course, a connection between the first portion  12  and the second portion  13  may be sealed by a sealing member. The sealing member may be a sealing ring, a sealant or the like. 
     The first portion  12  and the second portion  13  may be of various shapes such as a cuboid and a cylinder. The first portion  12  may be of a hollow structure with one side open, the second portion  13  may also be of a hollow structure with one side open, and the open side of the second portion  13  covers the open side of the first portion  12 , such that the case  10  having the accommodating space  11  is formed. Of course, it is also possible that the first portion  12  is of a hollow structure with one side open, the second portion  13  is of a plate-like structure, and the second portion  13  covers the open side of the first portion  12 , such that the case  10  having the accommodating space  11  is formed. 
     In the battery  100 , there may be one or more battery cells  20 . If a plurality of battery cells  20  are provided, the plurality of battery cells  20  may be connected to each other in series, in parallel, or in series-parallel. The series-parallel connection refers that some of the plurality of battery cells  20  are connected in series and the rest are connected in parallel. The plurality of battery cells  20  may be directly connected to each other in series or in parallel or in series-parallel, and then a whole body composed of the plurality of battery cells  20  is accommodated in the case  10 . Of course, it is also possible that a plurality of battery cells  20  are first connected in series or in parallel or in series-parallel to form a battery module, and a plurality of battery modules are then connected in series or in parallel or in series-parallel connection to form a whole and are accommodated in the case  10 . The battery cell  20  may be in the shape of a cylinder, a flat body, a cuboid or others.  FIG.  3    exemplarily shows a battery cell  20  in the form of a cube. 
     Referring to  FIG.  4   , in some embodiments, the battery  100  may further comprise a bus component  30 , and the plurality of battery cells  20  may be electrically connected to each other via the bus component  30 , so as to implement series connection, parallel connection, or series-parallel connection of the plurality of battery cells  20 . 
     Referring to  FIG.  5   , the battery cell  20  may comprise a housing  21 , an electrode assembly  22  and an end cap assembly  23 . The housing  21  is provided with an opening  211  and an accommodating cavity  212 , the electrode assembly  22  can enter the accommodating cavity  212  from the opening  211  such that the electrode assembly  22  is accommodated in the accommodating cavity  212 , and the end cap assembly  23  is configured to cover the opening  211 . 
     The housing  21  may have various shapes such as a cylinder and a cuboid. The housing  21  may be shaped depending on the specific shape of the electrode assembly  22 . For example, if the electrode assembly  22  is of a cylindrical structure, a housing  21  of a cylindrical structure may be used; and if the electrode assembly  22  is of a cuboid structure, a housing  21  of a cuboid structure may be used.  FIG.  5    exemplarily shows the housing  21  and the electrode assembly  22  in the form of cubes. 
     The housing  21  may also be made of various materials, such as copper, iron, aluminum, stainless steel, an aluminum alloy and plastic, which will not be particularly limited in the embodiments of the present application. 
     The electrode assembly  22  may comprise a positive electrode plate, a negative electrode plate and a separator. The electrode assembly  22  may be of a winding structure formed by winding the positive electrode plate, the separator and the negative electrode plate, or a laminated structure formed by laminating the positive electrode plate, the separator and the negative electrode plate. The electrode assembly  22  further comprises a positive electrode tab and a negative electrode tab. A positive electrode current collector in the positive electrode plate that is not coated with a positive electrode active material layer may be used as the positive electrode tab, and a negative electrode current collector in the negative electrode plate that is not coated with a negative electrode active material layer may be used as the negative electrode tab. 
     The end cap assembly  23  is configured to cover the opening  211  of the housing  21 , so as to cover the electrode assembly  22  in the accommodating cavity  212 . The accommodating cavity  212  is configured to accommodate the electrode assembly  22 . The accommodating cavity  212  is also configured to accommodate an electrolyte, such as an electrolytic solution. The end cap assembly  23  is used as a component for outputting the electrical energy from the electrode assembly  22 . An electrode terminal in the end cap assembly  23  is configured to be electrically connected to the electrode assembly  22 , that is, the electrode terminal is electrically connected to the tab of the electrode assembly  22 . For example, the electrode terminal is connected to the tab via the current collector  1   a  to realize the electrical connection between the electrode terminal and the tab. 
     It should be noted that, as shown in  FIG.  5   , there may be one or two openings  211  of the housing  21 . If there is one opening  211  of the housing  21 , there also may be one end cap assembly  23 . Two electrode terminals may be provided in the end cap assembly  23 , and are configured to be respectively electrically connected to the positive electrode tab and the negative electrode tab of the electrode assembly  22 . The two electrode terminals in the end cap assembly  23  are respectively a positive electrode terminal and a negative electrode terminal. If there are two openings  211  of the housing  21 , for example, the two openings  211  are arranged on opposite sides of the housing  21 , there also may be two end cap assemblies  23 . The two end cap assemblies  23  respectively cover the two openings  211  of the housing  21 . In this case, the electrode terminal in one of the end cap assemblies  23  may be a positive electrode terminal for electrical connection with the positive electrode tab of the electrode assembly  22 ; and the electrode terminal in the other end cap assembly  23  may be a negative electrode terminal for electrical connection with the negative electrode plate of the electrode assembly  22 . 
     The end cap assembly  23  may comprise an end cap  231 , a first electrode terminal  232 , a second electrode terminal  233  and a pressure relief mechanism  234 . 
     The first electrode terminal  232  and the second electrode terminal  233  are both mounted on the end cap  231 . The pressure relief mechanism  234  is located between the first electrode terminal  232  and the second electrode terminal  233 , and the pressure relief mechanism  234  is configured to be actuated when an internal pressure or temperature of the battery cell  20  reaches a threshold to relieve the internal pressure of the battery cell  20 . 
     The end cap  231  of the end cap assembly  23  is configured to cover the opening  211  of the housing  21  (see  FIG.  5   ). The end cap  231  may have various shapes such as a circle and a rectangle. The shape of the end cap  231  depends on the shape of the housing  21 . If the housing  21  is of a cylindrical structure, a circular end cap  231  may be used; and if the housing  21  is of a cuboid structure, a cuboid end cap  231  may be used. As shown in  FIG.  5   , the end cap  231  is of a rectangular structure. 
     It should be noted that the polarities of the first electrode terminal  232  and the second electrode terminal  233  of the end cap assembly  23  may be the same or different. 
     In some embodiments, the polarities of the first electrode terminal  232  and the second electrode terminal  233  are the same, and the first electrode terminal  232  and the second electrode terminal  233  may be both positive electrode terminals for electrical connection with the positive electrode tab of the electrode assembly  22 . The first electrode terminal  232  and the second electrode terminal  233  may also be both negative electrode terminals for electrical connection with the negative electrode tab of the electrode assembly  22 . 
     In some embodiments, the polarities of the first electrode terminal  232  and the second electrode terminal  233  are opposite, one of the first electrode terminal  232  and the second electrode terminal  233  is a positive electrode terminal for electrical connection with the positive electrode tab of the electrode assembly  22 , and the other is a negative electrode terminal for electrical connection with the negative electrode tab of the electrode assembly  22 . 
     In the battery cell  20 , there may be one or two end cap assemblies  23 . 
     Referring to  FIGS.  6  and  7   , in some embodiments, the battery cell  20  comprises a housing  21 , an electrode assembly  22  and a first support member or structure  24 . The housing  21  is provided with an accommodating cavity  212 . The electrode assembly  22  is accommodated in the accommodating cavity  212 . The electrode assembly  22  comprises a main body portion  222  and a thinned portion  221 . At least one end of the main body portion  222  in a first direction A is connected to the thinned portion  221 , and a part of an electrode plate of the electrode assembly  22  at the main body portion  222  has a thickness greater than that of a part of the electrode plate of the electrode assembly  22  at the thinned portion  221 . The first support member  24  is arranged corresponding to the thinned portion  221 , and the first support member  24  is configured to support the thinned portion  221  when the electrode assembly  22  is expanded. 
     The first support member  24  is arranged in the housing  21  and corresponding to the thinned portion  221  such that when the electrode assembly  22  is expanded, the first support member  24  supports the thinned portion  221 , so that the thinned portion  221  can be in a stressed state with the support of the first support member  24 , reducing the risk of rapid capacity decay and even thermal runaway caused by uneven stresses on the main body portion and the thinned portion of the electrode assembly and uneven polarization and therefore by the deposition of lithium ions and the formation of lithium dendrites during charging and discharging due to the fact that under conventional circumstances, the thinned portion  221  has a smaller thickness so that the thinned portion  221  is not in contact with an inner wall of the housing  21  or adjacent thinned portions  221  are not in contact with each other and thus the thinned portion(s)  221  cannot be stressed. In addition, the uneven stresses on the main body portion and the thinned portion of the electrode assembly will also generate side reaction products such as metal lithium, lithium oxide, lithium fluoride and lithium carbonate. The side reaction products will consume lithium ions and the electrolytic solution, and affect the electrical conductivity, so that the capacity and the safety performance of the battery should be improved. Therefore, the provision of the first support member in the housing improves the capacity retention rate and the safety performance of the battery. 
     It should be noted that the first direction A is consistent with the width direction of the electrode plate of the electrode assembly  22 . For a wound electrode assembly  22 , the first direction A is also consistent with the direction of a winding axis of the wound electrode assembly  22 . 
     The electrode plate  1  (referring to  FIG.  1   ) comprises a current collector  1   a  and an active material layer  1   b  arranged on a surface of the current collector  1   a , and the active material layer  1   b  of the electrode plate  1  at the main body portion  222  has a greater thickness than that of the active material layer  1   b  of the electrode plate  1  at the thinned portion  221 . The electrode plate  1  may be a positive electrode plate and/or a negative electrode plate. In the rolling process of the electrode plate  1 , the active material layer  1   b  of the electrode plate  1  may spread from the middle to two ends in the width direction and be accumulated at the two ends in the width direction of the electrode plate  1 , so the active material layer  1   b  of the electrode plate  1  at the main body portion  222  having a greater thickness than that of the active material layer  1   b  of the electrode plate  1  at the thinned portion  221  provides an accumulation compensation position for the active material layer  1   b  accumulated from the middle to two ends, so that the thickness of the active material layer  1   b  of the rolled electrode plate  1  at the two ends in the width direction will not exceed the thickness thereof in the middle, reducing the accumulation amount of the active material layer  1   b  at the two ends in the width direction. Moreover, the active material layer  1   b  of the electrode plate at the main body portion  222  having a greater thickness than that of the active material layer  1   b  of the electrode plate  1  at the thinned portion  221  enables that in the rolling process of the electrode plate, the pressure received by the part of the electrode plate at the thinned portion  221  is smaller, thereby reducing the risk of peeling or falling off of the active material from the electrode plate at the thinned portion  221 , and reducing the possibility of cracking at the interface between the part of the electrode plate at the thinned portion  221  and the part of the electrode plate at the main body portion  222 . 
     In some embodiments, it is possible for the electrode assembly  22  that only the thickness of the positive electrode active material layer of the positive electrode plate at the main body portion  222  is greater than the thickness of the positive electrode active material layer of the positive electrode plate at the thinned portion  221 , and the thickness of the negative electrode active material layer of the negative electrode plate at the main body portion  222  is equal to the thickness of the negative electrode active material layer of the negative electrode plate at the thinned portion  221 . 
     In some other embodiments, it is possible for the electrode assembly  22  that only the thickness of the negative electrode active material layer of the negative electrode plate at the main body portion  222  is greater than the thickness of the negative electrode active material layer of the negative electrode plate at the thinned portion  221 , and the thickness of the positive electrode active material layer of the positive electrode plate at the main body portion  222  is equal to the thickness of the positive electrode active material layer of the positive electrode plate at the thinned portion  221 . 
     In some embodiments, the thickness of the positive electrode active material layer of the positive electrode plate of the electrode assembly  22  at the main body portion  222  is greater than the thickness of the positive electrode active material layer of the positive electrode plate at the thinned portion  221 , and the thickness of the negative electrode active material layer of the negative electrode plate at the main body portion  222  is greater than the thickness of the negative electrode active material layer of the negative electrode plate of the electrode assembly  22  at the thinned portion  221 . 
     In some embodiments, in the first direction A, one end of the main body portion  222  of the electrode assembly  22  is connected to the thinned portion  221 . In some other embodiments, in the first direction A, two ends of the main body portion  222  of the electrode assembly  22  are connected to thinned portions  221 . 
     In the case where in the first direction A, two ends of the main body portion  222  of the electrode assembly  22  are connected to the thinned portions  221 , for the convenience of description, the two thinned portions  221  are respectively defined as a first thinned portion  221  and a second thinned portion  221 . In some embodiments, it is possible that the thickness of the positive electrode active material layer of the positive electrode plate at the first thinned portion  221  is smaller than the thickness of the positive electrode active material layer of the positive electrode plate at the main body portion  222 , the thickness of the positive electrode active material layer of the positive electrode plate at the second thinned portion  221  is equal to the thickness of the positive electrode active material layer of the positive electrode plate at the main body portion  222 , the thickness of the negative electrode active material layer of the negative electrode plate at the first thinned portion  221  is equal to the thickness of the negative electrode active material layer of the negative electrode plate at the main body portion  222 , and the thickness of the negative electrode active material layer of the negative electrode plate at the second thinned portion  221  is smaller than the thickness of the negative electrode active material layer of the negative electrode plate at the main body portion  222 . In some other embodiments, it is possible that the thickness of the positive electrode active material layer of the positive electrode plate at each of the first thinned portion  221  and the second thinned portion  221  is smaller than the thickness of the positive electrode active material layer of the positive electrode plate at the main body portion  222 , and the thickness of the negative electrode active material layer of the negative electrode plate at each of the first thinned portion  221  and the second thinned portion  221  is smaller than the thickness of the negative electrode active material layer of the negative electrode plate at the main body portion  222 . 
     There are various forms for making the thickness of the part of the electrode plate  1  at the thinned portion  221  smaller than the thickness of the part of the electrode plate  1  at the main body portion  222 . In some embodiments, the part of the electrode plate  1  at the thinned portion  221  has a thickness gradually decreasing in the direction in which the thinned portion  221  faces away from the main body portion  222 , so that in a rolling process of the electrode plate  1 , the pressure received by the part of the electrode plate  1  at the thinned portion  221  is smaller, thereby reducing the risk of peeling or falling off of the active material from the thinned portion  221 , and reducing the possibility of cracking at the interface between the part of the electrode plate  1  at the thinned portion  221  and the part of the electrode plate  1  at the main body portion  222 . The part of the electrode plate  1  at the thinned portion  221  has a thickness gradually decreasing in the direction in which the thinned portion  221  faces away from the main body portion  222 , so that the part of the active material layer  1   b  of the electrode plate  1  at the thinned portion  221  forms an inclined surface on the side facing away from the current collector  1   a . The surface of the active material layer  1   b  of the electrode plate  1  refers to a face of the active material layer  1   b  on the side facing away from the current collector  1   a.    
     Since the part of the electrode plate  1  at the thinned portion  221  has a thickness gradually decreasing in the direction in which the thinned portion  221  faces away from the main body portion  222 , that is, the part of the electrode plate  1  at the thinned portion  221  has a gradually increasing distance from the opposite inner wall of the housing  21  or the thinned portion  221  of the adjacent electrode assembly  22  in the direction in which the thinned portion  221  faces away from the main body portion  222 , the part of the first support member  24  corresponding to the thinned portion  221  has a thickness gradually increasing in the direction in which the thinned portion  221  faces away from the main body portion  222  in some embodiments. The part of the first support member  24  corresponding to the thinned portion  221  having a thickness gradually increasing in the direction in which the thinned portion  221  faces away from the main body portion  222  can complement the thickness change of the part of the electrode plate  1  at the thinned portion  221 , so that when the electrode assembly  22  is expanded, the thinned portion  221  can be supported by the first support member  24  to make the thinned portion  221  be stressed as uniformly as possible. 
     In some other embodiments, the part of the electrode plate  1  at the thinned portion  221  has a constant thickness in the direction in which the thinned portion  221  faces away from the main body portion  222 . The thickness of the part of the electrode plate  1  at the thinned portion  221  is smaller than the thickness of the part of the electrode plate  1  at the main body portion  222 , so that a step is formed at the interface between the part of the electrode plate  1  at the thinned portion  221  and the part of the electrode plate at the main body portion  222 . 
     In some embodiments, the first support member  24  is fixed to the thinned portion  221 . The first support member  24  being fixed to the thinned portion  221  enables the first support member  24  to be closely attached to the thinned portion  221 , so that during assembling of the battery cell  20  and during charging and discharging of the battery cell  20 , the first support member  24  is not displaced relative to the electrode assembly  22 . The first support member  24  may be fixed to the thinned portion  221  by means of glue bonding, adhesive tape binding, or the like. 
     In some embodiments, it is also possible that the first support member  24  is fixed to the inner wall of the housing  21 . 
     In the embodiment of the present application, a battery cell  20  comprising a cuboid wound electrode assembly is taken as an example to introduce the related structure of the battery cell  20 . In the thickness direction of the electrode assembly  22 , the electrode assembly  22  has a straight portion  223 . In the length direction C of the electrode assembly, the electrode assembly  22  has two opposite bent portions  224 , and two ends of the straight portion  223  are respectively connected to the two bent portions  224 . Each thinned portion  221  comprises a part at the straight portion  223  and parts at the two bent portions  224 . The first direction A, the thickness direction B of the battery cell and the length direction C of the electrode assembly are perpendicular to one another. 
     Referring to  FIG.  7   , which is an enlarged view of part I in  FIG.  6   , in some embodiments, the battery cell  20  comprises a plurality of electrode assemblies  22 . The plurality of electrode assemblies  22  are arranged side-by-side in the thickness direction B of the battery cell. The first support member  24  comprises at least one first abutting portion  241 , and at least one first abutting portion  241  is arranged between the thinned portions  221  of two adjacent electrode assemblies  22 . 
     In the case where the battery cell  20  comprises a plurality of electrode assemblies  22  arranged side-by-side in the thickness direction thereof and the first abutting portion  241  of the first support member  24  is arranged between the thinned portions  221  of two adjacent electrode assemblies  22 , when the electrode assemblies  22  are expanded, adjacent parts of the thinned portions  221  of the two adjacent electrode assemblies  22  approach each other and press the first abutting portion  241 , and the thinned portions  221  are supported by the reaction force of the first abutting portion  241 , so that the thinned portions  221  of the two adjacent electrode assemblies  22  can be in a stressed state with the support of the first abutting portion  241 , reducing the risk of deposition of lithium ions and generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the parts of the thinned portions  221  between the two adjacent electrode assemblies  22  have a smaller thickness so that the thinned portions are not in contact with each other and thus cannot be stressed. 
     The first abutting portion  241  is at least partially arranged between the parts of the thinned portions  221  of the two adjacent electrode assemblies  22  at the straight portions  223 . 
     In some embodiments, one first abutting portion  241  is arranged between the thinned portions  221  of two adjacent electrode assemblies  22 . The first abutting portion  241  may be of a triangular prism structure. As shown in  FIG.  7   , in the side-by-side direction of the two electrode assemblies  22 , the first abutting portion  241  has two first supporting faces  2411 . One first supporting face  2411  of the two first supporting faces  2411  is configured to be attached to the thinned portion  221  of one electrode assembly  22  of the two electrode assemblies  22 , and the other first supporting face  2411  of the two first supporting faces  2411  is configured to be attached to the thinned portion  221  of the other electrode assembly  22  of the two electrode assemblies  22 . The two first supporting faces  2411  are inclined faces, and the inclination direction of each inclined face is consistent with that of the surface of the part of the electrode plate  1  of the corresponding electrode assembly  22  at the thinned portion  221 , so that the first supporting face  2411  can be better attached to the thinned portion  221 , and the first support member  24  can thus make the thinned portion  221  stressed as uniformly as possible. When the electrode assemblies  22  are expanded, the opposite parts of the thinned portions  221  of the two electrode assemblies  22  are expanded in the direction of approaching each other, and cooperate with the corresponding first supporting faces  2411  respectively, to press the first abutting portion  241 . The first abutting portion  241  reacts to the thinned portions  221 , so that the thinned portions  221  are subjected to the reaction forces of the first abutting portion  241 , alleviating the deposition of lithium ions and therefore lithium precipitation and the generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that the electrode plate  1  has a smaller thickness at the thinned portion  221  so that the thinned portion  221  is not in contact with an adjacent thinned portion  221  and thus the thinned portions cannot be stressed. 
     In the embodiment of the present application, the side-by-side direction of the electrode assemblies  22  is consistent with the thickness direction B of the battery cell. 
     The two first supporting faces  2411  of one first abutting portion  241  between two electrode assemblies  22  may respectively form a fixed connection relationship with the thinned portions  221  of the two electrode assemblies  22  by means of adhesive bonding or the like. It is also possible that the first abutting portion  241  is pressed between two adjacent electrode assemblies  22  by pressing the two electrode assemblies  22  against each other. 
     Referring to  FIGS.  8  and  9   , in some embodiments, two first abutting portions  241  are provided between the thinned portions  221  of two adjacent electrode assemblies  22 , and the two first abutting portions  241  are configured to abut against each other in the thickness direction B of the battery cell when the electrode assemblies  22  are expanded, so as to support the thinned portions  221 . Each first abutting portion  241  may be arranged corresponding to one thinned portion  221 . As the electrode assemblies  22  are expanded, the two first abutting portions  241  are abutting against each other in the direction of approaching each other. When the two first abutting portions  241  abut against each other, they provide a reverse support force for the corresponding thinned portions  221 , so that the parts of the thinned portions  221  between the two adjacent electrode assemblies  22  are stressed, reducing the risk of deposition of lithium ions and generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the parts of the thinned portions  221  between the two adjacent electrode assemblies  22  have a smaller thickness so that the thinned portions are not in contact with each other and thus cannot be stressed. 
     As shown in  FIG.  9   , the battery cell  20  comprises two electrode assemblies  22  arranged side-by-side, and the two first abutting portions  241  are provided between the opposite parts of the thinned portions  221  of the two electrode assemblies  22 . 
     The first abutting portion  241  has a first supporting face  2411  and a first abutting face  2412 . The first supporting face  2411  is configured to be attached to the thinned portion  221 , and the first supporting face  2411  is an inclined face. The inclination direction of the first supporting face  2411  of each first abutting portion  241  is consistent with that of the surface of the part of the active material layer  1   b  of the electrode plate of the corresponding electrode assembly  22  at the thinned portion  221 , so that the first supporting face  2411  can be better attached to the thinned portion  221 , and the first support member  24  can thus make the thinned portion  221  stressed as uniformly as possible. The first supporting face  2411  may be in the side-by-side direction of the two electrode assemblies  22 , the first abutting face  2412  is located on the side of the first support member  24  away from the thinned portion  221 , and the two first abutting faces  2412  are configured to abut against each other under the action of the expansion forces of the electrode assemblies  22 . When the electrode assemblies  22  are expanded, the opposite parts of the thinned portions  221  of the two electrode assemblies  22  are expanded in the direction of approaching each other, and cooperate with the corresponding first supporting faces  2411  respectively, to press the first abutting portion  241 , so as to abut the first abutting faces  2412  of the two first abutting portions  241  against each other, and apply reaction forces to the thinned portions  221 , so that the thinned portions  221  are subjected to the reaction forces of the first abutting portion  241 , alleviating the deposition of lithium ions and therefore lithium precipitation and the generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that the electrode plate  1  has a smaller thickness at the thinned portion  221  so that the thinned portion  221  is not in contact with an adjacent thinned portion  221  and thus the thinned portions cannot be stressed. 
     In some embodiments, the inclination angle of the first supporting face  2411  relative to the first abutting face  2412  is between 0.1° and 50°, and may be specifically selected from 1° to 45° or 5° to 30°. 
     The length of the first supporting face  2411  in the extending direction thereof may be set to be 0.1 mm to 25 mm, and the length of the first abutting face  2412  in the first direction A may be set to be 0.1 mm to 10 mm. 
     In the case where two first abutting portions  241  are provided between two adjacent electrode assemblies  22 , the first supporting face  2411  of one first abutting portion  241  of the two first abutting portions  241  is connected to the thinned portion  221  of one of the electrode assemblies  22 , and the first supporting face  2411  of the other first abutting portion  241  is connected to the thinned portion  221  of the other electrode assembly  22 , so that the two first abutting portions  241  are respectively integrally connected to the two electrode assemblies  22  for ease of mounting. With this structure, when the electrode assemblies  22  are not expanded, the first abutting faces  2412  of the two first abutting portions  241  may abut against each other, or may be arranged apart from each other. 
     In some embodiments, the battery cell  20  may also comprise more than two electrode assemblies  22 . Referring to  FIGS.  10  and  11   ,  FIG.  10    shows a schematic structural diagram in which more than three electrode assemblies  22  are comprised and one first abutting portion  241  is arranged between two adjacent electrode assemblies  22 , and  FIG.  11    shows an enlarged view of part III in  FIG.  10   . In the battery cell  20  shown in  FIGS.  10    and  11 , in the side-by-side direction of the electrode assemblies  22 , two adjacent first abutting portions  241  may also be formed by connecting them each other, or two adjacent first abutting portions  241  may form an integrally formed structure by means of integral forming, and the side-by-side direction of the electrode assemblies  22  is consistent with the thickness direction B of the battery cell. 
     As shown in  FIGS.  12  and  13   ,  FIG.  12    shows a schematic structural diagram in which more than three electrode assemblies  22  are comprised and two first abutting portions  241  are arranged between two adjacent electrode assemblies  22 , and  FIG.  13    shows an enlarged view of part IV in  FIG.  12   . In the battery cell  20  shown in  FIGS.  12  and  13   , in the thickness direction B of the battery cell, the first abutting portions  241  on two sides of each electrode assembly  22  may be two separate structures. The two first abutting portions  241  may also be formed by connecting them each other, or may form an integrally formed structure by means of integral forming. In some embodiments, two adjacent first abutting portions  241  may be two separate structures, and each first abutting portion  241  is provided with a straight portion  223  of the electrode assembly  22 , so as to support the part of the thinned portion  221  at the straight portion  223  when the electrode assembly  22  is expanded. 
     The first abutting portion  241  may be entirely located at the straight portion  223 , or may have one part located at the straight portion  223  and the other part extending to the bent portion  224  in the circumferential direction of the electrode assembly  22 . 
     Still referring to  FIG.  13   , in some embodiments, the first support member  24  comprises a second abutting portion  242 . The second abutting portion  242  is arranged between the thinned portion  221  and the inner wall of the housing  21 . The second abutting portion  242  is configured to abut against the inner wall of the housing  21  when the electrode assembly  22  is expanded, so as to support the thinned portion  221 . 
     It should be noted that, the second abutting portion  242  abutting against the inner wall of the housing  21  may refer to that the second abutting portion  242  directly abuts against the inner wall of the housing  21 , or may indirectly abut against the inner wall of the housing via an intermediate member. 
     The second abutting portion  242  is arranged between the thinned portion  221  and the inner wall of the housing  21  such that when the electrode assembly  22  is expanded, the second abutting portion  242  is supported between the thinned portion  221  and the inner wall of the housing  21 , so that the thinned portion  221  can be in a stressed state with the support of the second abutting portion  242 , reducing the risk of deposition of lithium ions and generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the thinned portion  221  has a smaller thickness so that the thinned portion  221  is not in contact with the inner wall of the housing  21  and thus the thinned portion  221  cannot be stressed. 
     The second abutting portion  242  may be of a right-angled triangular prism structure. In the thickness direction B of the battery cell, the second abutting portion  242  has a second supporting face  2421  and a second abutting face  2422 . The second abutting portion  242  is configured to cooperate with the thinned portion  221 , and the second abutting face  2422  is configured to abut against the inner wall of the housing  21  in the direction in which the first support member  24  faces away from the thinned portion  221 . The second supporting face  2421  is an inclined face. The inclination direction of the inclined face is consistent with that of the surface of the part of the electrode plate  1  of the corresponding electrode assembly  22  at the thinned portion  221 , so that the second supporting face  2421  can be better attached to the thinned portion  221 . 
     In the case where the battery cell  20  comprises a plurality of electrode assemblies  22 , the plurality of electrode assemblies  22  comprise a first edge electrode assembly  22   a  and a second edge electrode assembly  22   b  located at two ends in the side-by-side direction of the electrode assemblies  22 . A second abutting portion  242  is provided on the side where the part of the thinned portion  221  of the first edge electrode assembly  22   a  facing the inner wall of the housing  21  is located. The second abutting portion  242  is arranged corresponding to the part of the thinned portion  221  of the first edge electrode assembly  22   a  facing the inner wall of the housing  21 , and the second abutting portion  242  supports the part of the thinned portion  221  of the first edge electrode assembly  22   a  facing the inner wall of the housing  21  when the electrode assembly  22  is expanded. A second abutting portion  242  is provided on the side where the part of the thinned portion  221  of the second edge electrode assembly  22   b  facing the inner wall of the housing  21  is located. The second abutting portion  242  is arranged corresponding to the part of the thinned portion  221  of the second edge electrode assembly  22   b  facing the inner wall of the housing  21 , and the second abutting portion  242  supports the part of the thinned portion  221  of the second edge electrode assembly  22   b  facing the inner wall of the housing  21  when the electrode assembly  22  is expanded. 
     In some embodiments, one part of the second abutting portion  242  is located at the straight portion  223 , and other part of the second abutting portion  242  extends at least to an outer periphery of one bent portion  224 , so that the second abutting portion can support the straight portion  223  and at least one bent portion  224  of the first edge electrode assembly  22   a  when the electrode assembly  22  is expanded, and the second abutting portion  242  can support the straight portion  223  and the bent portion  224  of the second edge electrode assembly  22   b  when the electrode assembly  22  is expanded. 
     In some embodiments, the second abutting portion  242  may also be entirely arranged at the straight portion  223 . 
     In some embodiments, the first support member  24  is arranged around the outer periphery of the thinned portion  221 , such that when the electrode assembly  22  is expanded, the first support member  24  can support the thinned portion  221  at any position in the circumferential direction of the thinned portion  221 , so that all the positions of the thinned portion  221  in the circumferential direction can be stressed, and the thinned portion  221  is uniformly polarized, reducing the risk of deposition of lithium ions and generation of side reaction products during charging and discharging. 
     Referring to  FIG.  14   , in some embodiments, the battery cell  20  comprises two electrode assemblies  22 . In the side-by-side direction of the electrode assemblies  22  (the thickness direction B of the battery cell), the two electrode assemblies  22  are respectively a first edge electrode assembly  22   a  and a second edge electrode assembly  22   b , and one first support member  24  is arranged around the outer periphery of the thinned portion  221  of each of the two electrode assemblies  22 . The first support member  24  comprises a first abutting portion  241  and a second abutting portion  242 . In the circumferential direction of the electrode assembly  22 , the first abutting portion  241  and the second abutting portion  242  are connected to each other form a closed-loop first support member  24 . 
     Referring to  FIG.  15   , in some embodiments, the battery cell  20  comprises three or more electrode assemblies  22 , and each thinned portion  221  of each electrode assembly  22  is correspondingly provided with one first support member  24 . In the side-by-side direction of the electrode assemblies  22  (the thickness direction B of the battery cell), the electrode assemblies  22  at two ends are respectively a first edge electrode assembly  22   a  and a second edge electrode assembly  22   b , and the remaining electrode assemblies  22  are intermediate electrode assemblies  22   c . Each thinned portion  221  of the first edge electrode assembly  22   a , each thinned portion  221  of the second edge electrode assembly  22   b , and each thinned portion  221  of the intermediate electrode assembly  22   c  are respectively provided with one first support member  24  around the outer circumference thereof. The first support member  24  arranged at each of the first edge electrode assembly  22   a  and the second edge electrode assembly  22   b  comprises a first abutting portion  241  and a second abutting portion  242 . In the circumferential direction of the electrode assembly  22 , the first abutting portion  241  and the second abutting portion  242  are connected to each other form a closed-loop first support member  24 . The first support member  24  corresponding to the thinned portion  221  of the intermediate electrode assembly  22   c  comprises only the first abutting portion  241 , and the first abutting portion  241  is arranged around the thinned portion  221  of the intermediate electrode assembly  22   c.    
     In some embodiments, the battery cell  20  comprises a plurality of electrode assemblies  22 , the first support member  24  may only comprise a first abutting portion  241 , and the first abutting portion  241  is supported between the thinned portions  221  of two adjacent electrode assemblies  22 . 
     Referring to  FIGS.  16  and  17   , in some embodiments, the battery cell  20  has only one electrode assembly  22 . In the thickness direction B of the battery cell, second abutting portions  242  are provided on two sides of the electrode assembly  22 , that is, one electrode assembly  22  is correspondingly provided with two second abutting portions  242 , and the two second abutting portions  242  can respectively abut against the inner wall of the housing  21  on two sides of the thickness direction B of the battery cell, so as to support the thinned portion  221  when the electrode assembly  22  is expanded. The two second abutting portions  242  may be separate structures, or may be connected to each other or form an integrally formed structure by means of integral forming. In the case where the two second abutting portions  242  are connected to each other or are of an integrally formed structure, the two second abutting portions  242  extend in the circumferential direction of the electrode assembly  22 , so that one part of the structure formed by the two second abutting portions  242  is arranged at the straight portion  223 , and the other part is arranged around at least one bent portion  224 . When one part of the structure formed by the two second abutting portions  242  is arranged at the straight portion  223 , and the other part is arranged around two bent portions  224 , the first support member  24  is arranged around the outer periphery of the thinned portion  221 .  FIGS.  16  and  17    show that the first support member  24  comprising only the second abutting portion  242  is arranged around the thinned portion  221 . 
     In some embodiments, regardless of whether there is one or more electrode assemblies  22  in the battery cell  20 , the first support member  24  may only comprise a second abutting portion  242 . In other words, when there is one electrode assembly  22 , the first support member  24  only comprises a second abutting portion  242  arranged between the thinned portion  221  and the inner wall of the housing  21 , and when there are a plurality of electrode assemblies  22 , the first support member  24  only comprises a second abutting portion  242  arranged between the thinned portion  221  and the inner wall of the housing  21 , and no first abutting portion  241  may be provided between two adjacent electrode assemblies  22 . 
     Referring to  FIG.  18   , in some embodiments, the battery cell  20  further comprises a second support member  25 . The second support member  25  is arranged corresponding to the main body portion  222 , and the second support member  25  is configured to support the main body portion  222  when the electrode assembly  22  is expanded. When the battery cell  20  is expanded, the second support member  25  supports the main body portion  222 , so that the main body portion  222  is stressed as uniformly as possible, improving the polarization uniformity, and reducing the risk of deposition of lithium ions and generation of side reaction products during charging and discharging. The provision of the first support member  24  and the second support member  25  can alleviate the problems of lithium precipitation of the thinned portion  221  and uneven expansion force of the main body portion  222 . 
     In the case where the second support member  25  is located between the main body portion  222  and the inner wall of the housing  21 , when the electrode assembly  22  is expanded, the main body portion  222  and the inner wall of the housing  21  jointly press the second support member  25 , and the second support member  25  supports the main body portion  222  so that the main body portion  222  is in a stressed state. In the case where the second support member  25  is located between the main body portions  222  of two adjacent electrode assemblies  22 , when the electrode assemblies  22  are expanded, the main body portions  222  of the two adjacent electrode assemblies  22  jointly press the second support member  25 , and the second support member  25  exerts reaction forces on the main body portions  222  to support the main body portions  222 , so that the main body portions  222  are in a stressed state. 
     In some embodiments, in the first direction A, the first support member  24  and the second support member  25  are arranged apart from each other, or one end of the first support member  24  abuts against one end of the second support member  25 . 
     In some embodiments, the second support member  25  is connected to one end of the first support member  24  in the first direction A. The first support member  24  is connected to the second support member  25  such that the first support member  24  and the second support member  25  can be mutually restrained, relative displacement will not occur, and the mounting stability of the first support member  24  and the second support member  25  are improved, so that when the electrode assembly  22  is expanded, the first support member  24  can stably support the thinned portion  221 , and the second support member  25  can stably support the main body portion  222 . 
     In the case where the battery cell  20  comprises only one electrode assembly  22 , the first support member  24  arranged in the battery cell  20  only comprises a second abutting portion  242 , and the second support member  25  is connected to one end of the second abutting portion  242 . 
     In the case where the battery cell  20  comprises two electrode assemblies  22 , the first support member  24  comprises a first abutting portion  241  and a second abutting portion  242 , the second support member  25  may be connected to both the first abutting portion  241  and the second abutting portion  242 , and one part of the second support member  25  is located between the main body portion  222  and the inner wall of the housing, and the other part is located between two adjacent electrode assemblies  22 . 
     In the case where the battery cell  20  comprises three or more electrode assemblies  22 , some of the first support members  24  may only comprise a second abutting portion  242 , and some of the second support members  25  may comprise a first abutting portion  241  and a second abutting portion  242 . Then, some of the second support members  25  may be connected to one end of a second abutting portion  242 , and some of the second support members  25  may be connected to both a first abutting portion  241  and a second abutting portion  242 . 
     In some embodiments, the surface of the first support member  24  facing away from the thinned portion  221  is flush with the surface of the second support member  25  facing away from the main body portion  222 , such that when the surface of the second support member  25  facing away from the main body portion  222  is subjected to a pressing force in a direction facing the main body portion  222 , the surface of the first support member  24  facing away from the thinned portion  221  is also subjected to a pressing force in a direction facing the thinned portion  221 , so that the thinned portion  221  and the main body portion  222  are uniformly stressed. 
     In some embodiments, the second support member  25  and the first support member  24  being of an integrally formed structure facilitates manufacturing, and can also reduce the number of steps for assembling the battery cell  20 , and the integrally formed structure of the first support member  24  and the second support member  25  also has a good structural strength. The integrally formed structure of the second support member  25  and the first support member  24  refers to a structure formed by the second support member  25  and the first support member  24  by means of integral forming such as casting or injection molding. 
     As shown in  FIG.  18   , in some embodiments, the two ends of the main body portion  222  in the first direction A are connected to thinned portions  221 , and the two ends of the second support member  25  in the first direction A are connected to first support members  24 . 
     In some embodiments, the battery cell  20  may only comprise a first support member  24 , and no second support member  25  is provided. When only the first support member  24  is provided in the battery cell  20 , the surface of the first support member  24  facing away from the thinned portion  221  protrudes from the surface of the main body portion  222  in the direction in which the first support member  24  faces away from the thinned portion  221 . When the electrode assembly  22  is expanded, the expansion amount of the main body portion  222  is generally greater than the expansion amount of the thinned portion  221 , so when the surface of the first support member  24  facing away from the thinned portion  221  protrudes from the surface of the main body portion  222  in the direction in which the first support member  24  faces away from the thinned portion  221 , the protruding size can compensate for the difference in the expansion amount of the thinned portion  221  relative to the main body portion  222  during expansion, such that when the surface of the main body portion  222  is subjected to an abutting force, the surface of the first support member  24  facing away from the thinned portion  221  is subjected to an abutting force in the direction facing the thinned portion  221 , so that the thinned portion  221  and the main body portion  222  are uniformly stressed. 
     Of course, when only the first support member  24  is provided in the battery cell  20 , the surface of the first support member  24  facing away from the thinned portion  221  may be flush with the surface of the main body portion  222  in the direction in which the first support member  24  faces away from the thinned portion  221 . When the surface of the first support member  24  facing away from the thinned portion  221  is flush with the surface of the main body portion  222 , it is convenient to complete assembly of the battery cell  20 . 
     Still referring to  FIG.  18   , in some embodiments, the electrode assembly  22  has a central hole  225 ; and the battery cell  20  further comprises a third support member  26 . The third support member  26  is inserted into the central hole  225  and arranged corresponding to the thinned portion  221 . 
     The materials of the first support member  24 , the second support member  25  and the third support member  26  may be the same or different. For example, the first support member  24 , the second support member  25  and the third support member  26  may be selected from rubber, foam, aerogel and other flexible materials. 
     The combination of the first support member  24  and the second support member  25  can realize the function of enhancing the safety performance of the battery  100 . For example, the first support member  24  is made of foam, and the second support member  25  is made of heat-insulating aerogel, so that the second support member  25  blocks the heat transfer between the plurality of electrode assemblies  22  at the main body portion  222 , so as to delay the spread time of thermal runaway and reduce the severity of the runaway. 
     For a cylindrical electrode assembly  22 , the positive electrode plate, the negative electrode plate and the separator that need to be stacked are wound around a winding needle, so the formed electrode assembly  22  has a central hole  225 . When the electrode assembly  22  is expanded, a part of the thinned portion  221  will have a tendency to expand toward the center of the central hole  225 , the third support member  26  is inserted into the central hole  225  and is arranged corresponding to the thinned portion  221 , such that when the electrode assembly  22  is expanded, the part of the thinned portion  221  expanding toward the center of the central hole  225  presses the third support member  26 , and the thinned portion  221  is supported with the reaction force of the third support member  26 , so that the thinned portion  221  expanding toward the center of the central hole  225  can be in a stressed state, reducing the risk of deposition of lithium ions and generation of side reaction products during charging and discharging caused by uneven polarization due to the smaller thickness of the electrode plate  1  at the thinned portion  221  on the outer periphery of the central hole  225  and the presence of the central hole  225  so that the thinned portion is not in contact with the central hole and thus cannot be stressed. The structure of the third support member  26  may refer to the structure of the first support member  24  or the combined structure of the first support member  24  and the second support member  25 . 
     In some embodiments, the electrode assembly  22  may be a laminated electrode assembly. At least one end of the laminated electrode assembly in the height direction is provided with a thinned portion, and a first support member  24  is arranged corresponding to the thinned portion of the laminated electrode assembly. 
     As shown in  FIG.  19   , an embodiment of the present application also provides a method for manufacturing a battery cell  20 , the manufacturing method comprises the following steps. 
     In step S 100 , a housing  21 , an electrode assembly  22  and a first support member  24  are provided. The housing  21  is provided with an accommodating cavity  212 . The electrode assembly  22  comprises a main body portion  222  and a thinned portion  221 . At least one end of the main body portion  222  in a first direction A is connected to the thinned portion  221 , and a part of an electrode plate  1  of the electrode assembly  22  at the main body portion  222  has a thickness greater than that of a part of the electrode plate  1  of the electrode assembly  22  at the thinned portion  221 . 
     In step S 200 , the electrode assembly  22  and the first support member  24  are caused to be accommodated in the accommodating cavity  212 , and the first support member  24  is arranged corresponding to the thinned portion  221 , such that the first support member  24  supports the thinned portion  221  when the electrode assembly  22  is expanded. 
     The first support member  24  is arranged in the housing  21  and corresponding to the thinned portion  221  such that when the electrode assembly  22  is expanded, the first support member  24  supports the thinned portion  221 , so that the thinned portion  221  can be in a stressed state with the support of the first abutting portion  241 , alleviating the deposition of lithium ions and therefore lithium precipitation and the generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the electrode plate has a smaller thickness at the thinned portion  221  so that the thinned portion  221  is not in contact with the inner wall of the housing  21  or adjacent thinned portions  221  are not in contact with each other and thus the thinned portion(s)  221  cannot be stressed. 
     Referring to  FIG.  20   , an embodiment of the present application also provides an apparatus  2000  for manufacturing a battery cell. The apparatus  2000  for manufacturing a battery cell comprises a provision device  2100  and an assembly device  2200 . The provision device  2100  is configured to provide a housing  21 , an electrode assembly  22  and a first support member  24 . The housing  21  is provided with an accommodating cavity  212 . The electrode assembly  22  comprises a main body portion  222  and a thinned portion  221 . At least one end of the main body portion  222  in a first direction A is connected to the thinned portion  221 , and a part of an electrode plate  1  of the electrode assembly  22  at the main body portion  222  has a thickness greater than that of a part of the electrode plate  1  of the electrode assembly  22  at the thinned portion  221 . The assembly device  2200  is configured to cause the electrode assembly  22  and the first support member  24  to be accommodated in the accommodating cavity  212 , and to arrange the first support member  24  corresponding to the thinned portion  221 , such that the first support member  24  supports the thinned portion  221  when the electrode assembly  22  is expanded. 
     The assembly device  2200  can arrange the first support member  24  in the housing  21  and corresponding to the thinned portion  221  such that when the electrode assembly  22  is expanded, the first support member  24  supports the thinned portion  221 , so that the thinned portion  221  can be in a stressed state with the support of the first abutting portion  241 , alleviating the deposition of lithium ions and therefore lithium precipitation and the generation of side reaction products during charging and discharging caused by uneven polarization due to the fact that under conventional circumstances, the electrode plate has a smaller thickness at the thinned portion  221  so that the thinned portion  221  is not in contact with the inner wall of the housing  21  or adjacent thinned portions  221  are not in contact with each other and thus the thinned portion(s)  221  cannot be stressed. 
     The foregoing descriptions are merely preferred embodiments of the present application, but are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, and the like made within the spirit and principle of the present application should be included within the protection scope of the present application.