Patent Publication Number: US-2023148174-A1

Title: Battery, electrical device, and method and device for manufacturing battery

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2021/076288, filed Feb. 9, 2021, and entitled “BATTERY, ELECTRICAL DEVICE, AND METHOD AND DEVICE FOR MANUFACTURING BATTERY”, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This application relates to the field of batteries, and in particular, to a battery, an electrical device, and a method and device for manufacturing a battery. 
     BACKGROUND 
     A chemical cell, electrochemical cell, or electrochemical battery is a type of device that converts chemical energy of positive and negative active materials into electrical energy through a redox reaction. Different from an ordinary redox reaction, the oxidation and reduction reactions in the electrochemical cell occur separately. To be specific, the oxidation occurs at a negative electrode, the reduction occurs at the positive electrode, and electrons are gained and lost through an external circuit, thereby forming a current. That is an essential feature of all batteries. After being researched and developed in a long term, the chemical batteries have been shaping up into many different varieties applied widely. The batteries are applicable to huge equipment that occupies a building and small devices that are several millimeters in size. The development of modern electronic technology has imposed high requirements on the chemical batteries. Every breakthrough in the technology of chemical batteries has brought about a revolutionary development of electronic devices. Many electrochemical scientists in the world have concentrated their research and development interests in the field of chemical batteries that provide power for electric vehicles. 
     Due to advantages such as a small size, a high energy density, a high power density, reusability for many cycles, and a long shelf life, lithium-ion batteries as a type of chemical battery are widely used in electronic devices, electrical means of transport, electrical toys, and electrical devices. For example, currently, the lithium-ion batteries are widely used in products such as a mobile phone, a notebook computer, an electric power cart, an electric vehicle, an electric airplane, an electric ship, an electric toy car, an electric toy ship, an electric toy airplane, and a power tool. 
     With the ongoing development of lithium-ion battery technology, higher requirements have been imposed on the performance of lithium-ion batteries. The lithium-ion batteries are expected to meet a plurality of design requirements concurrently. Normally, battery cells in a lithium-ion battery are connected by an electrical connection structure by welding, and the electrical connection structure is a busbar component of relatively high rigidity. The busbar component is an independently manufactured structural part, and is electrically connected to electrode terminals of a battery cell by welding for at least two times. Such an electrical connection structure is complicated, and the busbar component disposed brings a variety of risks and affects conductivity between the battery cells. 
     SUMMARY 
     This application discloses a battery, an electrical device, and a method and device for manufacturing a battery to simplify an electrical connection structure between the battery cells. 
     According to a first aspect in accordance with the present disclosure, a battery is provided, including:
         a plurality of battery cells arranged along a first direction, where a plate-like electrode terminal is disposed on each end face of each of the battery cells along a first direction, so that two electrode terminals of two battery cells are disposed between two end faces opposite to each other along the first direction; and   the two electrode terminals are configured to be at least partly stacked and fixedly connected between the two end faces along a thickness direction of the electrode terminal to enable electrical connection between the two battery cells.       

     With the end faces of the two battery cells being disposed opposite to each other along the first direction, the battery cells can be electrically connected to each other in a horizontal way. A plurality of battery cells can be accommodated in the height direction according to an internal mounting space of a vehicle, thereby taking full advantage of the internal mounting space of the vehicle. The two electrode terminals are fixedly connected by being stacked partly without a need to use a busbar component, thereby simplifying the electrical connection structure between the battery cells, reducing a variety of risks brought by the busbar component disposed, ensuring reliable conductivity between the battery cells, reducing the manufacturing cost of the battery, and improving the production efficiency of the battery. 
     In some embodiments, the electrode terminal includes:
         a stack portion, configured to enable stacking of the two electrode terminals; and   an extension portion, configured to be connected to the stack portion, where the extension portion protrudes from the end face by a preset length.       

     With the electrode terminal including two portions that serve different functions, the stack portion is configured to enable fixed connection, and the extension portion is configured to electrically connect the stack portion to an internal component of the battery cell, thereby facilitating the design and manufacture of the electrode terminal and facilitating the electrical connection between the electrode terminals. 
     In some embodiments, a ratio of the preset length to a length of the stack portion along the first direction is 0.25 to 1. 
     If the length of the extension portion is deficient, the stack portion will be very close to the end face of the battery cell, thereby bringing inconvenience to the fixed connection between the stack portions. If the length of the extension portion is excessive, the electrode terminal is prone to occupy excessive space between the end faces of the battery cell. By limiting the ratio of the length of the extension portion to the length of the stack portion, it is convenient to implement the fixed connection between the stack portions, and the electrode terminal is prevented from occupying excessive space between the end faces of the battery cells, and the electrical connection structure of the battery cells is further optimized. 
     In some embodiments, the electrode terminal further includes a connecting portion, configured to connect the stack portion and the extension portion, so that the stack portion is staggered from the extension portion along the thickness direction. 
     Normally, the positions of the electrode terminals on the end faces of battery cells are identical. In a case that an end face of one battery cell is disposed opposite to an end face of another battery cell, the electrode terminals of adjacent battery cells will inevitably interfere with each other when the electrode terminals are stacked. To avoid the interference, the stack portion is staggered from the extension portion along the thickness direction, and the two portions are disposed at different heights. In this way, the stacking of the electrode terminals is facilitated, and the adjacent electrode terminals dodge each other, so as to form a stacking structure. Normally, the electrode terminal is formed by stamping. The stack portion, the connecting portion, and the extension portion may be made in one piece, thereby facilitating manufacturing. 
     In some embodiments, a distance by which the stack portion is staggered from the extension portion is not greater than ½ of a thickness of the electrode terminal. 
     If the distance by which the stack portion is staggered from the extension portion is greater than ½ of the thickness of the electrode terminal, the stack portions of the two electrode terminals will be separated from each other in a natural state, thereby being adverse to the fixed connection. In some embodiments, the distance by which the stack portion is staggered from the extension portion is less than or equal to ½ of the thickness of the electrode terminal, so that all the stack portions can contact each other. 
     In some embodiments, a cross section of the connecting portion is linear or arcuate in shape. 
     The cross section of the connecting portion may be in various shapes, as long as the stack portion is staggered from the extension portion along the thickness direction. Applicable shapes include linear and arcuate shapes, and the connection strength such shapes can meet design requirements. 
     In some embodiments, the electrode terminal is in a flat plate shape. The two electrode terminals of the two battery cells, which are disposed opposite to each other along the first direction, are staggered from each other along the thickness direction. 
     By disposing the two electrode terminals of adjacent battery cells at different positions on the end faces, the adjacent electrode terminals dodge each other, so as to form a stacking structure. The electrode terminals do not need to be punched into special shapes, thereby simplifying the structure of the electrode terminals. 
     In some embodiments, the stack portion includes a first stack portion and a second stack portion that are separated from each other along a second direction. The second direction is perpendicular to the thickness direction. 
     With the first stack portion and the second stack portion disposed, the stack portions are diversified, and the types of the fixed connection structures between the stack portions are increased. 
     In some embodiments, along the second direction, a ratio of a width of a gap between the first stack portion and the second stack portion to a width of the stack portion is 0 to ⅓. 
     The first stack portion may be adjacent to the second stack portion or not. When the first stack portion is not adjacent to the second stack portion, a gap exists between the first stack portion and the second stack portion. If the width of the gap is greater than ⅓ of the width of the stack portion, the stacks portions are prone to be separated under an external force after being fixedly connected. By limiting the width of the gap, the stability of the connection structure between the stack portions is ensured. 
     In some embodiments, the first stack portion is staggered from the second stack portion along the thickness direction. 
     With the first stack portion staggered from the second stack portion, the two fixedly connected stack portions can not only limit each other in the thickness direction, but also limit each other in the width direction, thereby improving the stability of the connection structure between the stack portions. 
     In some embodiments, a distance by which the first stack portion is staggered from the second stack portion is not less than a thickness of the electrode terminal. 
     If the distance by which the first stack portion is staggered from the second stack portion is less than the thickness of the electrode terminal, the two stack portions will interfere with each other instead of being stacked in staggered way. When the distance by which the first stack portion is staggered from the second stack portion is greater than or equal to the thickness of the electrode terminal, the two stack portions can be stacked together in a staggered way. 
     In some embodiments, two adjacent stack portions are configured to enable stacking of the two electrode terminals by snap-fitting into each other. 
     With the stack portions that can snap-fit into each other, the connection strength is increased between the stack portions. Especially, when the battery cells are vibrating, the stack portions are not prone to separate, thereby ensuring the reliability of the electrical connection between the battery cells. 
     In some embodiments, one of the two adjacent stack portions includes a plug portion, and the other of the two adjacent stack portions includes a receptacle portion. The receptacle portion is configured to hold the plug portion so that the two adjacent stack portions snap-fit into each other. 
     Snap-fitting structures come in many types. The structures of the plug portion and the receptacle portion are highly manufacturable and formable, and facilitate snap-fitting. 
     In some embodiments, the stack portion is configured to be bent toward the end face along the first direction to form the plug portion and the receptacle portion. 
     With the stack portion bent toward the end face of the battery cell, the stack portion can form a hook shape, so that the stack portion can not only be stacked but also be hooked, thereby further improving the connection strength between the stack portions. 
     In some embodiments, the stack portion further includes a body portion configured to connect the extension portion and the plug portion. The body portion is disposed opposite to, and spaced apart from, the plug portion along the thickness direction to form the receptacle portion. 
     The snap-fitting structure formed in this way is highly manufacturable and formable, and achieves a relatively large space of the receptacle portion, thereby increasing the strength of the snap-fitting structure. 
     According to a second aspect in accordance with the present disclosure, an electrical device is provided. The electrical device includes the battery described in the first aspect above. The battery is configured to provide electrical energy for the electrical device. 
     According to a third aspect in accordance with the present disclosure, a method for manufacturing a battery is further provided, including:
         providing a plurality of battery cells arranged along a first direction, where a plate-like electrode terminal is disposed on each end face of each of the battery cells along a first direction, so that two electrode terminals of two battery cells are disposed between two end faces opposite to each other along the first direction; and   stacking at least partly and connecting fixedly the two electrode terminals between the two end faces along a thickness direction of the electrode terminal to enable electrical connection between the two battery cells.       

     According to a fourth aspect in accordance with the present disclosure, a device for manufacturing a battery is further provided, including:
         a battery cell manufacturing module, configured to manufacture a plurality of battery cells, where a plate-like electrode terminal is disposed on each end face of each of the battery cells along a first direction, so that two electrode terminals of two battery cells are disposed between two end faces opposite to each other along the first direction; and   an assembling module, configured to electrically connect the plurality of battery cells, where the two electrode terminals are configured to be at least partly stacked and fixedly connected between the two end faces along a thickness direction of the electrode terminal to enable electrical connection between the two battery cells.       

    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The drawings described herein are intended to enable a further understanding in accordance with the present disclosure, and constitute a part in accordance with the present disclosure. The exemplary embodiments in accordance with the present disclosure and the description thereof are intended to explain this application but not to constitute any undue limitation on this application. In the drawings: 
         FIG.  1    is a three-dimensional schematic diagram of a battery cell according to some embodiments in accordance with the present disclosure; 
         FIG.  2    is a three-dimensional schematic diagram of a plurality of battery cells connected in series according to some embodiments in accordance with the present disclosure; 
         FIG.  3    is a schematic front view of a plurality of battery cells connected in series according to some embodiments in accordance with the present disclosure; 
         FIG.  4    is an enlarged view of position A shown in  FIG.  3   ; 
         FIG.  5    is a three-dimensional schematic diagram of an electrode terminal of a battery cell according to some embodiments in accordance with the present disclosure; 
         FIG.  6    is a three-dimensional schematic diagram of a connection state of electrode terminals of battery cells according to some embodiments in accordance with the present disclosure; 
         FIG.  7    is a schematic front view of a connection state of electrode terminals of battery cells according to some embodiments in accordance with the present disclosure; 
         FIG.  8    is a three-dimensional schematic diagram of an electrode terminal of a battery cell according to some embodiments in accordance with the present disclosure; 
         FIG.  9    is a three-dimensional schematic diagram of a connection state of electrode terminals of battery cells according to some embodiments in accordance with the present disclosure; 
         FIG.  10    is a three-dimensional schematic diagram of an electrode terminal of a battery cell according to some embodiments in accordance with the present disclosure; 
         FIG.  11    is a three-dimensional schematic diagram of an electrode terminal of a battery cell according to some embodiments in accordance with the present disclosure; 
         FIG.  12    is a three-dimensional schematic diagram of a connection state of electrode terminals of battery cells according to some embodiments in accordance with the present disclosure; 
         FIG.  13    is a schematic exploded view of a battery cell according to some embodiments in accordance with the present disclosure; 
         FIG.  14    is a schematic sectional view of a battery cell according to some embodiments in accordance with the present disclosure; 
         FIG.  15    is a partial enlarged view of the battery cell shown in  FIG.  14    and rotated by 90 degrees; 
         FIG.  16    is a schematic structural diagram of a vehicle powered by a battery disclosed herein according to some embodiments in accordance with the present disclosure; 
         FIG.  17    is a schematic flowchart of a method for manufacturing a battery according to some embodiments in accordance with the present disclosure; and 
         FIG.  18    is a schematic structural diagram of a device for manufacturing a battery according to some embodiments in accordance with the present disclosure. 
     
    
    
     Reference numerals:  1 . vehicle;  10 . battery;  30 . controller;  40 . motor;  2 . battery cell;  201 . housing;  202 . electrode assembly;  203 . connecting member;  204 . adhesive;  205 . top cover assembly;  2051 . end cap;  2052 . sealing element;  2053 . electrode terminal.  20531 . first electrode terminal;  20532 . second electrode terminal;  2054 . mounting hole;  2055 . extension portion;  2056 . stack portion;  20561 . plug portion;  20562 . receptacle portion;  20563 . body portion;  2057 . first stack portion;  2058 . second stack portion;  2059 . gap;  2060 . tail;  2061 . connecting portion;  3 . device for manufacturing a battery;  301 . battery cell manufacturing module;  302 . assembling module. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     To make the objectives, technical solutions, and advantages in accordance with the present disclosure clearer, the following gives an explicit and thorough description of the technical solutions in various embodiments in accordance with the present disclosure with reference to the drawings in various embodiments in accordance with the present disclosure. Understandably, the described embodiments are merely a part of but not all of various embodiments in accordance with the present disclosure. All other embodiments derived by a person of ordinary skill in the art based on various embodiments described herein without making any creative effort fall within the protection scope in accordance with the present disclosure. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meanings as usually understood by a person skilled in the technical field in accordance with the present disclosure. The terms used in the specification in accordance with the present disclosure are merely intended for describing specific embodiments but are not intended to limit this application. The terms “include”, “comprise”, “possess”, “contain”, and any variations thereof used in the specification, claims, and brief description of drawings hereof are used in a non-restrictive way. Therefore, a method or device that “includes”, “comprises”, or “contains” one or more steps or elements, includes but is not limited to, the one or more steps or elements enumerated. The terms such as “first” and “second” used in the specification, claims, and brief description of drawings herein are intended to distinguish between different items, but are not intended to describe a specific sequence or order of precedence. In addition, the terms “first” and “second” are used merely for descriptive purposes but are not to be construed as indicating or implying relative importance or implicitly specifying the quantity of technical features indicated. Therefore, a feature qualified by “first”, “second” and the like may explicitly or implicitly include one or more such features. In the description in accordance with the present disclosure, unless otherwise specified, “a plurality of” means two or more. 
     Understandably, in the description in accordance with the present disclosure, a direction or a positional relationship indicated by the terms such as “center”, “transverse”, “length”, “width”, “up”, “down”, “before”, “after”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “in”, “out”, “axial”, “radial”, and “circumferential” is a direction or positional relationship based on the illustration in the drawings, and is merely intended for ease or brevity of description in accordance with the present disclosure, but not intended to indicate or imply that the indicated device or element must be located in the specified direction or constructed or operated in the specified direction. Therefore, such terms are not to be understood as a limitation on this application. 
     In the description in accordance with the present disclosure, unless otherwise expressly specified and defined, the terms “mount”, “concatenate”, “connect”, and “attach” are understood in a broad sense. For example, a “connection” may be a fixed connection, a detachable connection, or an integrated connection; or may be a direct connection or an indirect connection implemented through an intermediary; or may be internal communication between two components. A person of ordinary skill in the art understands the specific meanings of the terms in this application according to the context. 
     Reference to “embodiment” in this application means that a specific feature, structure or characteristic described with reference to the embodiment may be included in at least one embodiment in accordance with the present disclosure. Reference to this term in different places in the specification does not necessarily represent the same embodiment, nor does it represent an independent or alternative embodiment in a mutually exclusive relationship with other embodiments. A person skilled in the art explicitly and implicitly understands that various embodiments described in this application may be combined with other embodiments. 
     As mentioned above, it needs to be emphasized that the term “include/comprise” used in this specification is intended to explicitly indicate the existence of the mentioned feature, integer, step or component, but does not exclude the existence or addition of one or more other features, integers, steps, or components, or a group of features, integers, steps, or components. Unless otherwise expressly specified herein, a noun in the singular form preceded by “a”, “an”, or “the” herein includes the plural form thereof. 
     The terms “a” and “an” in this specification may mean one, but may also have the same meaning as “at least one” or “one or more”. The term “approximately” qualifying a numerical value generally means the numerical value plus or minus 10% thereof, or more specifically, plus or minus 5% thereof. Unless expressly indicating only an alternative solution, the term “or” used in the claims means “and/or”. 
     The term “and/or” in this application indicates merely a relation for describing the related items, and represents three possible relationships. For example, “A and/or B” may represent the following three circumstances: A alone, both A and B, and B alone. In addition, the character “/” herein generally indicates an “or” relationship between the item preceding the character and the item following the character. 
     Batteries mentioned in this field may be classed into a primary battery and a rechargeable battery depending on rechargeability. The primary battery is informally known as a “disposable” battery or a galvanic battery because the battery is not rechargeable and has to be discarded after exhaustion of electrical power. A rechargeable battery is also called a secondary battery, a secondary cell, or a storage battery. A material for and a process of manufacturing a rechargeable battery are different from those of a primary battery. An advantage of the rechargeable battery is that the battery can be used for a plurality of cycles after being charged. An output current load capacity of the rechargeable battery is higher than that of most primary batteries. Currently, common types of rechargeable batteries include: lead-acid battery, nickel-metal hydride battery, and lithium-ion battery. The lithium-ion battery exhibits advantages such as a light weight, a high capacity (the capacity is 1.5 to 2 times that of a nickel-metal hydride battery of the same weight), and no memory effect, and exhibits a very low self-discharge rate. Therefore, despite relative expensiveness, the lithium-ion battery is widely applied. The lithium-ion battery is also applied to battery electric vehicles and hybrid vehicles. The lithium-ion battery for use in such vehicles possesses a relatively low capacity, but a relatively high output current, a relatively high charge current, and a relatively long life in spite of a relatively high cost. 
     The battery described in various embodiments in accordance with the present disclosure means a rechargeable battery. The following describes the conception in accordance with the present disclosure using a lithium-ion battery as an example. Understandably, this application is applicable to any other suitable types of rechargeable batteries. The battery mentioned in various embodiments in accordance with the present disclosure means a stand-alone physical module that includes one or more battery cells to provide a higher voltage and a higher capacity. For example, the battery mentioned in this application may include a battery module, a battery pack, or the like. A battery cell includes a positive electrode plate, a negative electrode plate, an electrolytic solution, and a separator, and is a basic structural unit of a battery module and a battery pack. Depending on the form of packaging, battery cells are generally classed into three types: cylindrical battery cell, prismatic battery cell, and pouch-type battery cell. 
     A lithium-ion battery cell works primarily by relying on movement of lithium ions between the positive electrode plate and the negative electrode plate. The lithium-ion battery cell uses an intercalated lithium compound as an electrode material. Currently, positive electrode materials typically used for lithium-ion batteries include: lithium cobalt oxide (LiCoO 2 ), lithium manganese oxide (LiMn 2 O 4 ), lithium nickel oxide (LiNiO 2 ), and lithium iron phosphate (LiFePO 4 ). A separator is disposed between the positive electrode plate and the negative electrode plate to form a thin film structure compounded of three layers of materials. The thin film structure is generally wound or stacked to form an electrode assembly of a desired shape. For example, the thin film structure compounded of three layers of materials in a cylindrical battery cell is wound into a cylinder-shaped electrode assembly. The thin film structure in a prismatic battery cell is wound or stacked to form an electrode assembly in the shape of approximately a cuboid. 
     A plurality of battery cells may be connected together in series and/or parallel through electrode terminals, so as to be applied in various scenarios. In high-power application scenarios such as electric vehicles, a battery is applied in different hierarchical forms such as a battery cell, a battery module, and a battery pack. The battery module is formed by electrically connecting a specific quantity of battery cells together and putting the battery cells into a frame, so as to protect the battery cells from external impact, heat, vibration, and the like. The battery pack is a final state of a battery system mounted in an electric vehicle. Currently, most of battery packs are made by assembling various control and protection systems such as a battery management system (BMS) and a thermal management part on one or more battery modules. With advancement of technologies, the battery module is omissible. That is, a battery pack is directly formed from battery cells. This improvement significantly decreases the quantity of parts while enhancing a gravimetric energy density and a volumetric energy density of the battery system. A battery referred to herein includes a battery module or a battery pack. 
     Considering that existing battery cells are generally connected by a busbar component of relatively high rigidity by welding, and that the electrical connection structure is relatively complicated and at many risks, this application fixedly connects electrode terminals of the battery cells directly to enable electrical connection between two battery cells, thereby simplifying the electrical connection structure between the battery cells, and reducing a variety of risks brought by the busbar component disposed. 
     For clearer understanding in accordance with the present disclosure, the following describes various embodiments in accordance with the present disclosure in detail with reference to  FIG.  1    to  FIG.  18   . 
     As shown in  FIG.  1   ,  FIG.  2   ,  FIG.  3   , and  FIG.  4   , a battery  10  according to an embodiment in accordance with the present disclosure includes: 
     a plurality of battery cells  2  arranged along a first direction X, where a plate-like electrode terminal  2053  is disposed on each end face of each of the battery cells  2  along a first direction X, so that two electrode terminals  2053  of two battery cells  2  are disposed between two end faces opposite to each other along the first direction X. 
     The two electrode terminals are configured to be at least partly stacked and fixedly connected between the two end faces along a thickness direction Z of the electrode terminal  2053  to enable electrical connection between the two battery cells  2 . 
     In this embodiment, the first direction X is an axial direction of the battery cell  2  after the battery cell is fixed in the battery  10 , or a length direction of the battery cell  2  after the battery cell is fixed in the battery  10 . 
     The battery cell  2  may be in a prismatic shape, a cylindrical shape, or the like. The electrode terminals  2053  in this embodiment are applicable to the battery cells  2  of different shapes. A cross section of the electrode terminal  2053  is rectangular. The length-width ratio of the cross section is relatively high, so that the electrode terminal  2053  is in the shape of a plate. 
       FIG.  1   ,  FIG.  2   , and  FIG.  3    use one row of battery cells  2  as an example. Two electrode terminals  2053  of two battery cells  2 , that is, a first electrode terminal  20531  and a second electrode terminal  20532 , are disposed between two end faces opposite to each other along the first direction X. The first electrode terminal  20531  and the second electrode terminal  20532  are partly stacked and fixedly connected along the thickness direction Z, as shown in  FIG.  4   . The fixed connection may be implemented by welding, such as laser welding, ultrasonic welding, or other appropriate types of welding. The two battery cells  2  are electrically connected without a busbar component disposed in between. 
     With the end faces of the two battery cells  2  being disposed opposite to each other along the first direction X, the battery cells  2  can be electrically connected to each other in a horizontal way. A plurality of battery cells  2  can be accommodated in the height direction according to an internal mounting space of a vehicle, thereby taking full advantage of the internal mounting space of the vehicle. The two electrode terminals  2053  are fixedly connected by being stacked partly without a need to use a busbar component, thereby simplifying the electrical connection structure between the battery cells  2 , reducing a variety of risks brought by the busbar component disposed, ensuring reliable conductivity between the battery cells  2 , reducing the manufacturing cost of the battery  10 , and improving the production efficiency of the battery  10 . 
     In some embodiments, the electrode terminal  2053  includes:
         a stack portion  2056 , configured to enable stacking of the two electrode terminals  2053 ; and   an extension portion  2055 , configured to be connected to the stack portion  2056 , where the extension portion  2055  protrudes from the end face by a preset length.       

     As shown in  FIG.  5    and  FIG.  6   , the two electrode terminals  2053  are partly stacked and fixedly connected along the thickness direction Z by using a stack portion  2056 . The extension portion  2055  is connected to the stack portion  2056 . Referring to  FIG.  4    additionally, it can be seen that the extension portion  2055  protrudes from the end face of the battery cell  2  by a preset length. 
     With the electrode terminal  2053  including two portions that serve different functions, the stack portion  2056  is configured to enable fixed connection, and the extension portion  2055  is configured to electrically connect the stack portion  2056  to an internal component of the battery cell  2 , thereby facilitating the design and manufacture of the electrode terminal  2053  and facilitating the electrical connection between the electrode terminals  2053 . 
     In some embodiments, a ratio of the preset length to a length of the stack portion  2056  along the first direction X is 0.25 to 1. 
     As shown in  FIG.  4   , the extension portion  2055  protrudes from the end face by a preset length B. B is a distance from the end face of the battery cell  2  to a boundary line between the extension portion  2055  and the connecting portion  2061  (to be described later) along the first direction X. The length of the stack portion  2056  is C. C is a distance from the boundary line between the connecting portion  2061  and the stack portion  2056  to the end face of the stack portion  2056  along the first direction X. In this embodiment, a ratio of B to C is 0.25 to 1, so as to facilitate the fixed connection between the stack portions  2056  and prevent the electrode terminals  2053  from occupying excessive space between the end faces of the battery cells  2 . 
     If the length of the extension portion  2055  is deficient, the stack portion  2056  will be very close to the end face of the battery cell  2 , thereby bringing inconvenience to the fixed connection between the stack portions  2056 . If the length of the extension portion  2055  is excessive, the electrode terminal  2053  is prone to occupy excessive space between the end faces of the battery cell  2 . By limiting the ratio of the length of the extension portion  2055  to the length of the stack portion  2056 , it is convenient to implement the fixed connection between the stack portions  2056 , and the electrode terminal  2053  is prevented from occupying excessive space between the end faces of the battery cells  2 , and the electrical connection structure of the battery cells  2  is further optimized. 
     In some embodiments, the electrode terminal  2053  further includes a connecting portion  2061 , configured to connect the stack portion  2056  and the extension portion  2055 , so that the stack portion  2056  is staggered from the extension portion  2055  along the thickness direction Z. Normally, the thicknesses of the stack portion  2056  is equal to the thickness of the extension portion  2055 , and is equal to the thickness of the electrode terminal  2053 . 
     As shown in  FIG.  4   ,  FIG.  5   , and  FIG.  6   , a connecting portion  2061  is disposed between the stack portion  2056  and the extension portion  2055 . The stack portion  2056  may be regarded as being parallel to the extension portion  2055 . One end that is of the connecting portion  2061  and that is connected to the stack portion  2056  is at a different height than the other end connected to the extension portion  2055 , so that the stack portion  2056  is staggered from the extension portion  2055  along the thickness direction Z. 
     Normally, the positions of the electrode terminals  2053  on the end faces of the battery cells  2  are identical. In a case that an end face of one battery cell  2  is disposed opposite to an end face of another battery cell, the electrode terminals  2053  of adjacent battery cells will inevitably interfere with each other when the electrode terminals are stacked. To avoid the interference, the stack portion  2056  is staggered from the extension portion  2055  along the thickness direction Z, that is, the two portions are disposed at different heights. In this way, the stacking of the electrode terminals  2053  is facilitated, and the adjacent electrode terminals  2053  dodge each other, so as to form a stacking structure. Normally, the electrode terminal  2053  is formed by stamping. The stack portion  2056 , the connecting portion  2061 , and the extension portion  2055  may be made in one piece, thereby facilitating manufacturing. 
     In some embodiments, a distance by which the stack portion  2056  is staggered from the extension portion  2055  is not greater than ½ of a thickness of the electrode terminal  2053 . 
     As shown in  FIG.  4   , the distance by which the stack portion  2056  is staggered from the extension portion  2055  is D. D is a distance from a lower surface of the extension portion  2055  to a lower surface of the stack portion  2056  along the thickness direction Z, or a distance from an upper surface of the extension portion  2055  to an upper surface of the stack portion  2056  along the thickness direction Z. The thickness of the electrode terminal  2053  is E. E is a distance from an upper surface to a lower surface of the electrode terminal  2053  along the thickness direction Z. In this embodiment, the ratio of D to E is 0 to ½, thereby ensuring that the stack portions  2056  can be in contact with and fixedly connected to each other. 
     If the distance by which the stack portion  2056  is staggered from the extension portion  2055  is greater than ½ of the thickness of the electrode terminal  2053 , the stack portions  2056  of the two electrode terminals  2053  will be separated from each other in a natural state, thereby being adverse to the fixed connection. In some embodiments, the distance by which the stack portion  2056  is staggered from the extension portion  2055  is less than or equal to ½ of the thickness of the electrode terminal  2053 , so that all the stack portions  2056  can contact each other. 
     In some embodiments, a cross section of the connecting portion  2061  is linear or arcuate in shape. 
     As shown in  FIG.  4   , the cross section of the connecting portion  2061  is an arc shape. As shown in  FIG.  5    and  FIG.  6   , the cross section of the connecting portion  2061  is a linear shape. The thicknesses of the connecting portion  2061  is equal to the thickness of the electrode terminal  2053 . 
     The cross section of the connecting portion  2061  may be in various shapes, as long as the stack portion  2056  is staggered from the extension portion  2055  along the thickness direction Z. Applicable shapes include linear and arcuate shapes, and the connection strength such shapes can meet design requirements. 
     In some embodiments, the electrode terminal  2053  is in a flat plate shape. The two electrode terminals  2053  of two battery cells  2 , which are disposed opposite to each other along the first direction X, are staggered from each other along the thickness direction Z. 
     As shown in  FIG.  7   , the first electrode terminal  20531  partly overlaps the second electrode terminal  20532 . Each electrode terminal  2053  may be regarded as still including the stack portion  2056  and the extension portion  2055 . However, the stack portion  2056  is not staggered from the extension portion  2055  any longer. Instead, the two electrode terminals  2053  are disposed at different positions on the end faces of the battery cells  2 , so that the two electrode terminals  2053  are stacked partly. 
     By disposing the two electrode terminals  2053  of adjacent battery cells  2  at different positions on the end faces, the adjacent electrode terminals  2053  dodge each other, so as to form a stacking structure. The electrode terminals  2053  do not need to be punched into special shapes, thereby simplifying the structure of the electrode terminals  2053 . It needs to be noted that a flat electrode terminal  2053  still includes a tail  2060  (to be detailed later). 
     In some embodiments, the stack portion  2056  includes a first stack portion  2057  and a second stack portion  2058  that are separated from each other along a second direction Y. The second direction Y is perpendicular to the thickness direction Z. 
     As shown in  FIG.  8   ,  FIG.  9   , and  FIG.  10   , the first stack portion  2057  and the second stack portion  2058  are two independent parts. The first stack portion  2057  is contiguous to the second stack portion  2058  in  FIG.  8    and  FIG.  9   . That is, there is no gap or a very small gap between the two stack portions along the second direction Y. In  FIG.  10   , the first stack portion  2057  is not contiguous to the second stack portion  2058 , That is, there is a relatively large gap between the two stack portions. 
     With the first stack portion  2057  and the second stack portion  2058  disposed, the stack portions  2056  are diversified, and the types of the fixed connection structures between the stack portions  2056  are increased. 
     In some embodiments, along the second direction Y, a ratio of a width of a gap  2059  between the first stack portion  2057  and the second stack portion  2058  to a width of the stack portion  2056  is 0 to ⅓. 
     As shown in  FIG.  10   , there is a gap  2059  between the first stack portion  2057  and the second stack portion  2058 . The width of the gap  2059  is F. F is a distance between two adjacent lateral faces of the first stack portion  2057  and the second stack portion  2058  along the second direction Y. The width of the stack portion  2056  is G. G is a distance between two lateral faces of the stack portion  2056  along the second direction Y. In this embodiment, a ratio of F to G is 0 to ⅓, thereby ensuring stability of the connection structure between the stack portions  2056 . 
     If the gap  2059  is larger than ⅓ of the width of the stack portion  2056 , a stacking area between the stack portions  2056  is relatively small. After being connected fixedly, the stack portions are prone to be separated under an external force. By limiting the width of the gap  2059 , the stability of the connection structure is ensured between the stack portions  2056 . 
     In some embodiments, the first stack portion  2057  is staggered from the second stack portion  2058  along the thickness direction Z. 
     As shown in  FIG.  8   ,  FIG.  9   , and  FIG.  10   , the first stack portion  2057  and the second stack portion  2058  may be regarded as being parallel to each other and located at different heights. 
     With the first stack portion  2057  staggered from the second stack portion  2058 , the two fixedly connected stack portions  2056  can not only limit each other in the thickness direction Z, but also limit each other in the width direction (that is, the second direction Y), thereby improving the stability of the connection structure between the stack portions  2056 . 
     In some embodiments, the distance by which the first stack portion  2057  is staggered from the second stack portion  2058  is not less than the thickness of the electrode terminal  2053 . 
     As shown in  FIG.  8   ,  FIG.  9   , and  FIG.  10   , the distance by which the first stack portion  2057  is staggered from the second stack portion  2058  is H. H is a distance from an upper surface of the first stack portion  2057  to an upper surface of the second stack portion  2058  along the thickness direction Z. The thickness of the electrode terminal  2053  is E. E is a distance from an upper surface to a lower surface of the electrode terminal  2053  along the thickness direction Z. In this embodiment, H is greater than or equal to E, thereby ensuring that the two stack portions  2056  can be stacked in a staggered way. 
     If the distance by which the first stack portion  2057  is staggered from the second stack portion  2058  is less than the thickness of the electrode terminal  2053 , the two stack portions  2056  will interfere with each other instead of being stacked in staggered way. When the distance by which the first stack portion  2057  is staggered from the second stack portion  2058  is greater than or equal to the thickness of the electrode terminal  2053 , the two stack portions  2056  can be stacked together in a staggered way. 
     In some embodiments, two adjacent stack portions  2056  are configured to enable stacking of the two electrode terminals  2053  by snap-fitting into each other. 
     As shown in  FIG.  11    and  FIG.  12   , the two stack portions  2056  are both stacked and snap-fitted to each other, and are connected variously. 
     With the stack portions  2056  that can snap-fit into each other, the connection strength is increased between the stack portions  2056 . Especially, when the battery cells  2  are vibrating, the stack portions  2056  are not prone to separate, thereby ensuring the reliability of the electrical connection between the battery cells  2 . 
     In some embodiments, one of the two adjacent stack portions  2056  includes a plug portion  20561 , and the other of the two adjacent stack portions includes a receptacle portion  20562 . The receptacle portion  20562  is configured to hold the plug portion  20561  so that the two adjacent stack portions  2056  snap-fit into each other. 
     As shown in  FIG.  11    and  FIG.  12   , the two stack portions  2056  each include a plug portion  20561  and a receptacle portion  20562 . The plug portion  20561  of one stack portion  2056  is inserted into the receptacle portion  20562  of the other stack portion  2056  to form a snap-fitting relationship. 
     The snap-fitting structures is diversified. For example, a bulge and a groove may be provided on the stack portion  2056  along the thickness direction Z. The bulge and the groove snap-fit into each other. The structures of the plug portion  20561  and the receptacle portion  20562  are highly manufacturable and formable, and facilitate snap-fitting. 
     In some embodiments, the stack portion  2056  is configured to be bent toward the end face along the first direction X to form the plug portion  20561  and the receptacle portion  20562 . 
     As shown in  FIG.  11    and  FIG.  12   , each stack portion  2056  is bent toward the end face of the battery cell  2  on which the stack portion is located, so as to form the plug portion  20561  and the receptacle portion  20562 . 
     With the stack portion  2056  bent toward the end face of the battery cell  2 , the stack portion  2056  can form a hook shape, so that the stack portion can not only be stacked but also be hooked, thereby further improving the connection strength between the stack portions  2056 . 
     In some embodiments, the stack portion  2056  further includes a body portion  20563  configured to connect the extension portion  2055  and the plug portion  20561 . The body portion  20563  is disposed opposite to, and spaced apart from, the plug portion  20561  along the thickness direction Z to form the receptacle portion  20562 . 
     As shown in  FIG.  11    and  FIG.  12   , the body portion  20563  and the plug portion  20561  may be regarded as being parallel to each other and located at different heights. 
     The snap-fitting structure formed in this way is highly manufacturable and formable, and achieves a relatively large space of the receptacle portion  20562 , thereby increasing the strength of the snap-fitting structure. 
     The arrangement of the electrode terminals  2053  in the battery cells  2  is shown in  FIG.  13   ,  FIG.  14   , and  FIG.  15   . The battery cell  2  includes:
         a housing  201 , where openings are made at two ends of the housing  201  along the first direction X;   an electrode assembly  202 , where the electrode assembly  202  is disposed inside the housing  201 .   two electrode terminals  2053 , where the two electrode terminals  2053  are disposed at two ends of the battery cell  2  along the first direction X respectively;   two connecting members  203 , where the two connecting members  203  are disposed inside the housing  201  and disposed at two ends of the electrode assembly  202  respectively, and are configured to electrically connect the electrode assembly  202  and the electrode terminal  2053 ; and   two end caps  2051 , where the two end caps  2051  are disposed at openings of the housing  201  and configured to seal the housing  201 .       

     In an embodiment in accordance with the present disclosure, the end face of the battery cell  2  is an outer end face of the end cap  2051 . 
     As shown in  FIG.  14   , the structures of the two electrode terminals  2053  are identical. The two ends of the battery cell  2  are oriented differently. The two electrode terminals  2053  each include a stack portion  2056 , an extension portion  2055 , and a tail  2060 . The stack portion  2056  is located outside the housing  201 . The extension portion  2055  passes through the end cap  2051 . The tail  2060  is located inside the housing  201  and configured for electrical connection to the connecting member  203 . 
     As shown in  FIG.  15   , a mounting hole  2054  is made at the center of the end cap  2051 . The extension portion  2055  passes through the mounting hole  2054 . A sealing element  2052  is disposed at a position corresponding to the mounting hole  2054 , and is configured to seal a gap between the extension portion  2055  and the mounting hole  2054 . The sealing element  2052  may be made by a nano-injection molding process. 
     According to a second aspect of embodiments in accordance with the present disclosure, an electrical device is provided. The electrical device includes the battery  10  described in the first aspect above. The battery  10  is configured to provide electrical energy for the electrical device. 
     Understandably, the battery  10  described in this embodiment in accordance with the present disclosure is applicable to various devices that use a battery  10 , for example, a mobile phone, a portable device, a notebook computer, an electric power cart, an electric vehicle, a ship, a spacecraft, an electric toy, an electric tool. For example, the spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, and the like. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, an electric airplane toy, and the like. The electric tool includes an electric tool for metal cutting, an electric grinding tool, an electric assembly tool, an electric tool for railways, 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 battery  10  described in this embodiment in accordance with the present disclosure is not only applicable to the devices described above, but also applicable to all devices that use the battery  10 . However, for brevity, the following embodiment is described by using an electric vehicle as an example. 
     For example, refer to  FIG.  16   , which is a brief schematic view of a vehicle  1  according to an embodiment in accordance with the present disclosure. The vehicle  1  may be an oil-fueled vehicle, a natural gas vehicle, or a new energy vehicle. The new energy vehicle may be a battery electric vehicle, a hybrid electric vehicle, a range-extended electric vehicle, or the like. As shown in  FIG.  16   , the battery  10  may be disposed inside the vehicle  1 . For example, the battery  10  may be disposed at the bottom, front, or rear of the vehicle  1 . The battery  10  may be configured to supply power to the vehicle  1 . For example, the battery  10  may serve as an operating power supply of the vehicle  1 . In addition, the vehicle  1  may further include a controller  30  and a motor  40 . The controller  30  is configured to control the battery  10  to supply power to the motor  40 , for example, to start or navigate the vehicle  1 , or meet the operating power requirements of the vehicle in operation. In another embodiment in accordance with the present disclosure, the battery  10  serves not only as an operating power supply of the vehicle  1 , but may also serve as a drive power supply of the vehicle  1  to provide driving motive power for the vehicle  1  in place of or partially in place of oil or natural gas. 
     As shown in  FIG.  16   , the battery cells  2  can be electrically connected to each other in a horizontal way. A plurality of battery cells  2  can be accommodated in the height direction according to an internal mounting space of the vehicle  1 , thereby taking full advantage of the internal mounting space of the vehicle  1 , facilitating assembling of the vehicle  1 , and increasing the capacity of the battery  10  mounted in the vehicle  1 . 
     According to a third aspect of embodiments in accordance with the present disclosure, a method for manufacturing a battery is provided. As shown in  FIG.  17   , the method includes the following steps: 
     Step S 1 : Provide a plurality of battery cells  2  arranged along a first direction X, where a plate-like electrode terminal  2053  is disposed on each end face of each of the battery cells  2  along a first direction X, so that two electrode terminals  2053  of two battery cells  2  are disposed between two end faces opposite to each other along the first direction X; and 
     Step S 2 : Stack at least partly and connect fixedly the two electrode terminals  2053  between the two end faces along a thickness direction Z of the electrode terminal  2053  to enable electrical connection between the two battery cells  2 . 
     For information not detailed in this embodiment, refer to the preceding embodiments. 
     According to a fourth aspect of embodiments in accordance with the present disclosure, a device  3  for manufacturing a battery is further provided. As shown in  FIG.  18   , the device includes:
         a battery cell manufacturing module  301 , configured to manufacture a plurality of battery cells  2 , where a plate-like electrode terminal  2053  is disposed on each end face of each of the battery cells  2  along a first direction X, so that two electrode terminals  2053  of two battery cells  2  are disposed between two end faces opposite to each other along the first direction X; and   an assembling module  302 , configured to electrically connect the plurality of battery cells  2 , where the two electrode terminals  2053  are configured to be at least partly stacked and fixedly connected between the two end faces along a thickness direction Z of the electrode terminal  2053  to enable electrical connection between the two battery cells  2 .       

     For information not detailed in this embodiment, refer to the preceding embodiments. 
     Finally, it needs to be noted that the foregoing embodiments are merely intended to describe the technical solutions in accordance with the present disclosure, but not to limit this application. Although this application is described in detail with reference to the foregoing embodiments, a person of ordinary skill in the art understands that modifications may still be made to the technical solutions described in the foregoing embodiments or equivalent replacements may still be made to some technical features thereof, without making the essence of the corresponding technical solutions depart from the spirit and scope of the technical solutions of various embodiments in accordance with the present disclosure.