Patent Description:
Batteries are widely applied in electronic devices, such as, mobile phones, laptops, battery cars, electric cars, electric planes, electric boats, electric toy cars, electric toy boats, electric toy planes and power tools, etc..

In battery technology, both safety and service life of the battery cells need to be considered. Therefore, how to improve the service life of battery cells is an urgent problem to be solved in battery technology.

<CIT> discloses a cover for an electrochemical cell with enhanced heat conduction. The cover comprises flat inner surfaces which are oriented inside of the cell housing and at least one flat outer surface which are oriented outside the housing. The inner surfaces are welded to a current collector. A similar construction is taught by <CIT>.

Embodiments of the present application provide a battery cell, a battery, an electrical device, and a method and a device for manufacturing the battery cell, which can effectively improve the service life of the battery cell.

In the first aspect, an embodiment of the present application provides a battery cell comprising the features of claim <NUM>. The battery cell comprising: an electrode assembly, having a first tab; a housing, having an opening, with the housing configured for receiving the electrode assembly; and an end cap, configured for connecting with the housing and covering the opening, wherein the end cap has an abutting surface and a welding groove, the abutting surface is configured for abutting against the first tab, the welding groove is recessed from one side of the end cap away from the electrode assembly towards the abutting surface, the end cap forms a connection part between the abutting surface and a bottom surface of the welding groove, and the connection part is configured for being welded with the first tab, wherein the end cap is provided with a reinforcing part, the reinforcing part is protruded from the bottom surface, and the reinforcing part is configured for enhancing a strength of the connection part.

In the above technical solution, the end cap is provided with a reinforcing part which is protruded from the bottom surface of the welding groove, and the reinforcing part can strengthen the connection part configured for being welded with the first tab, improving the strength of the connection part, reducing the risk of failure of the battery cell due to the damage of the connection part under pressure, and effectively improving the service life of the battery cell.

According to the first aspect, the connection part is welded with the first tab to form a weld mark, the weld mark comprises a first part and a second part that are continuously arranged, and the first part is formed at the reinforcing part, and the second part is formed on the connection part.

In the above technical solution, one part of the weld mark is formed on the reinforcing part, and the second part of the weld mark is formed on the connection part, which can reduce the risk that the connection part is punched through by the welding, due to the high initial welding temperature.

In some embodiments, in a thickness direction of the end cap, the reinforcing part has a first end and a second end oppositely arranged, and the first end is connected to the bottom surface; and a dimension of the reinforcing part in an extending direction of the welding groove gradually decreases from the first end to the second end, so that at least one side of the reinforcing part in the extending direction is provided with a sloping surface, the sloping surface is connected to the bottom surface, and the first part is formed on the sloping surface.

In the above technical solution, the dimension of the reinforcing part in the extending direction of the welding groove gradually decreases from the first end of the reinforcing part, which is connected to the bottom surface, to the second end of the reinforcing part, which is away from the bottom surface, so that the reinforcing part is of a structure with gradient thickness, which ensures the reinforcement part has better strengthening ability and at the same time saves material. In addition, since the reinforcing part is of the structure with gradient thickness, at least one side of the reinforcing part in the extending direction of the welding groove forms a sloping surface connected to the bottom surface of the welding groove. During the process of welding the connection part and the first tab, the slopping surface of the reinforcing rib can be used as a starting welding position to form the first part of the weld mark on the sloping surface, reducing the risk that the connection part is punched through by the welding, due to the high initial welding temperature.

In some embodiments, the reinforcing part is completely accommodated in the welding groove.

In the above technical solution, the reinforcing part is completely accommodated in the welding groove, so that the reinforcing part does not protrude out of the welding groove, and the reinforcing part does not occupy the space outside the battery cell.

In some embodiments, the end cap is provided with a plurality of the reinforcing parts arranged at intervals along an extending direction of the welding groove.

In the above technical solution, each of the plurality of reinforcing parts can reinforce the connection part, so that the connection parts are reinforced at plural positions in the extending direction of the welding groove, which further improves the strength of the connection part.

In some embodiments, the welding groove is an annular groove extending along a circumferential direction of the end cap; and the annular groove has an inner groove surface and an outer groove surface arranged coaxially, and the reinforcing part is connected to the inner groove surface and the outer groove surface.

In the above technical solution, the welding groove is an annular groove extending along the circumferential direction of the end cap, and plural positions of the connection part can be welded in the circumferential direction of the annular groove, which is beneficial to improve the firmness of the connection part and the first tab after welding. In addition, since the reinforcing part is connected to the inner groove surface and the outer groove surface of the welding groove, the firmness of the reinforcing part is improved, and the effect of the reinforcing part reinforcing the connection part is enhanced.

In some embodiments, the end cap comprises: a cap body, configured for connecting with the housing and covering the opening, wherein in a thickness direction of the end cap, the cap body has an outer surface and an inner surface arranged oppositely, and the welding groove is recessed from the outer surface towards the abutting surface; and a convex part, wherein in a thickness direction of the end cap, the convex part protrudes from the inner surface to the electrode assembly, and one end of the convex part away from the inner surface forms the abutting surface.

In the above technical solution, the convex part protrudes from the inner surface of the cap body towards the electrode assembly in the thickness direction of the end cap, and the end of the convex part away from the inner surface of the end cap forms an abutting surface. Such structure is easy to assure the flatness of the abutting surface, such that the abutting surface is in good contact with the first tab, thereby increasing the flow area.

In some embodiments, in a thickness direction of the end cap, a distance between the bottom surface and the abutting surface is less than or equal to a distance between the outer surface and the inner surface.

In the above technical solution, the distance between the bottom surface of the welding groove and the abutting surface of the convex part is less than or equal to the distance between the outer surface of the cap body and the inner surface of the cap body, that is, the thickness of the connection part is less than or equal to the thickness of the cap body, reducing the risk that the welding between the connection part and the first tab is weak due to the connection part being too thick.

In some embodiments, the end cap is provided with a liquid injection hole and a flow guiding channel; the liquid injection hole is configured for allowing electrolyte to enter an interior of the battery cell from outside of the battery cell, and an outer peripheral surface of the convex part is located on an outer periphery of the liquid injection hole; and the flow guiding channel communicates with the liquid injection hole and penetrates an outer peripheral surface of the convex part, and the flow guiding channel is configured for allowing at least part of the electrolyte to flow to outside of the outer peripheral surface.

In the above technical solution, the end cap is provided with a liquid injection hole and a flow guiding channel, the flow guiding channel is communicated with the liquid injection hole and passes through the outer peripheral surface of the convex part. During the process of injecting electrolyte into the interior of the battery cell through the liquid injection hole, the electrolyte can flow laterally to outside of the outer peripheral surface of the convex part through the flow guiding channel, which can effectively improve the liquid injection efficiency and make the electrolyte fully and quickly infiltrate the electrode sheets in the electrode assembly.

In some embodiments, the flow guiding channel is disposed at a position on the end cap corresponding to the reinforcing part.

In the above technical solution, the flow guiding channel is arranged on the end cap at a position corresponding to the reinforcing part, and the reinforcing part can strengthen the position of the end cap where the flow guiding channel is arranged, and improve the strength of the end cap at the position which the flow guiding channel is provided at.

In some embodiments, the flow guiding channel is a flow guiding groove arranged on the abutting surface.

In the above technical solution, the flow guiding channel is a flow guiding groove disposed on the abutting surface, which is convenient for forming of the flow guiding channel. Since the abutting surface faces the electrode assembly, the flow guiding groove is arranged on the abutting surface, so that the side of the flow guiding groove facing the electrode assembly is open, and during the process that the electrolyte laterally flows through the flow guiding channel, a part of the electrolyte can flows toward the interior of the electrode assembly along the direction towards the electrode assembly, which is beneficial for the electrolyte to infiltrate the electrode sheets.

In some embodiments, the flow guiding groove has a first groove wall and a second groove wall opposite to each other; and the reinforcing part comprises a first sloping surface and a second sloping surface opposing to each other, the first sloping surface and the second sloping surface are configured in such a way that a dimension of the reinforcing part in an extending direction of the welding groove gradually decreases from one end of the reinforcing part facing the bottom surface to one end of the reinforcing part away from the bottom surface, the first sloping surface is parallel to the first groove wall, and the second sloping surface is parallel to the second groove wall.

In the above technical solution, the first sloping surface of the reinforcing part is parallel to the first groove wall of the flow guiding groove, and the second sloping surface of the reinforcing part is parallel to the second groove wall of the flow guiding groove, so that the wall thicknesses of individual portions of the reinforcing part are uniform, without mutation generated, so as to enhance the ability of the reinforcing part strengthening the connection part.

In some embodiments, the end cap is provided with a concave part, the welding groove is located on an outer periphery of the concave part, the concave part is recessed from the abutting surface in a direction away from the electrode assembly, and the flow guiding channel communicates with the liquid injection hole through the concave part.

In the above technical solution, the welding groove is located on the outer periphery of the concave part, so that the welding groove and the concave part do not affect each other. The concave part plays the role of making the flow guiding channel and the liquid injection hole communicated with each other. Since the concave part is recessed from the abutment face in the direction away from the electrode assembly, after the electrolyte enters the concave part through the liquid injection hole, a part of the electrolyte can directly enter the interior of the electrode assembly through the concave part to infiltrate the electrode sheet, and a part of the electrolyte can enter the flow guiding channel through the concave part, and flow laterally inside the flow guiding channel and flow to outside of the outer peripheral surface of the convex part, improving the effect of the electrolyte infiltrating the electrode assembly, and simultaneously increasing the injection efficiency.

In some embodiments, the end cap has a liquid outlet surface located in the concave part, and one end of the liquid injection hole penetrates the liquid outlet surface; and in a thickness direction of the end cap, the liquid outlet surface is farther from the electrode assembly than the abutting surface.

In the above technical solution, the liquid outlet surface is farther away from the electrode assembly than the abutting surface in the thickness direction of the end cap, so that there is a distance between the liquid outlet surface and the electrode assembly, which is convenient for the electrolyte to enter the concave part through the liquid injection hole, which is beneficial to the electrolyte to enter the flow guiding channel through the concave part.

In some embodiments, one end of the flow guiding channel penetrates the outer peripheral surface, and the other end of the flow guiding channel penetrates an inner peripheral surface of the concave part.

In the above technical solution, the two ends of the flow guiding channel penetrate through the outer peripheral surface of the convex part and the inner peripheral surface of the concave part respectively, so that the electrolyte can enter the flow guiding channel from the concave part and flow laterally inside the flow guiding channel.

In some embodiments, the end cap is provided with a plurality of the flow guiding channels, and the plurality of the flow guiding channels are circumferentially distributed at intervals with the liquid injection hole as a center, such that the electrolyte can flow to many different directions through the plurality of flow guiding channels, thereby improving the injection efficiency.

In a second aspect, an embodiment of the present application provides a battery, comprising: the battery cell according to the first aspect; and a box, configured for accommodating the battery cell.

In a third aspect, an embodiment of the present application provides an electrical device, comprising the battery provided by any one of the embodiments of the second aspect.

In a fourth aspect, an embodiment of the present application provides a method of manufacturing a battery cell, the method comprising: providing an electrode assembly having a first tab; providing a housing having an opening; providing an end cap; making the electrode assembly accommodated in the housing; and connecting the end cap to the housing, so that the end cap covers the opening, wherein the end cap has an abutting surface and a welding groove, the abutting surface is configured for abutting against the first tab, the welding groove is recessed from one side of the end cap away from the electrode assembly towards the abutting surface, the end cap forms a connection part between the abutting surface and a bottom surface of the welding groove, and the connection part is configured for being welded with the first tab, the end cap is provided with a reinforcing part, the reinforcing part is protruded from the bottom surface, and the reinforcing part is configured for enhancing a strength of the connection part. According to the method, the connection part is welded with the first tab to form a weld mark, the weld mark comprises a first part and a second part that are continuously arranged, and the first part is formed at the reinforcing part, and the second part is formed on the connection part.

In a fifth aspect, an embodiment of the present application further provides a manufacturing device for a battery cell, the manufacturing device comprising: a first providing device, configured for providing an electrode assembly having a first tab; a second providing device, configured for providing a housing having an opening; a third providing device, configured for providing an end cap; an assembling device, configured for making the electrode assembly accommodated in the housing; and also for connecting the end cap to the housing, so that the end cap covers the opening, wherein the end cap has an abutting surface and a welding groove, the abutting surface is configured for abutting against the first tab, the welding groove is recessed from one side of the end cap away from the electrode assembly towards the abutting surface, the end cap forms a connection part between the abutting surface and a bottom surface of the welding groove, and the connection part is configured for being welded with the first tab, the end cap is provided with a reinforcing part, the reinforcing part is protruded from the bottom surface, and the reinforcing part is configured for enhancing a strength of the connection part. The assembling device is further configured to weld the connection part with the first tab to form a weld mark, the weld mark comprises a first part and a second part that are continuously arranged, and the first part is formed at the reinforcing part, and the second part is formed on the connection part.

In order to illustrate the technical solutions of the embodiments of the present application more clearly, the drawings needed to be used in the embodiments will be briefly introduced s below. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained according to these drawings without any creative efforts.

Reference Numbers: <NUM>-box; <NUM>-accommodating part; <NUM>-covering part; <NUM>-accommodating space; <NUM>-battery cell; <NUM>-housing; <NUM>-opening; <NUM>-first limit part; <NUM>-second limit part; <NUM>-roller groove; <NUM>-electrode assembly; <NUM>-first tab; <NUM>-main body part; <NUM>-second tab; <NUM>-center hole; <NUM>-end cap; <NUM>-abutting surface; <NUM>-welding groove; <NUM>-bottom surface; <NUM>-inner groove surface; <NUM>-outer groove surface; <NUM>-connection part; <NUM>-reinforcing part; <NUM>-first end; <NUM>-second end; <NUM>-sloping surface; 2343a-first sloping surface; 2343b-second sloping surface; <NUM>-cap body; <NUM>-outer surface; <NUM>-inner surface; <NUM>-convex part; <NUM> -outer peripheral surface; <NUM>-liquid injection hole; <NUM>-flow guiding channel; <NUM>-first groove wall; <NUM>-second groove wall; <NUM>-concave part; <NUM>-inner peripheral surface; <NUM>-liquid outlet surface; <NUM>-sealing member; <NUM>-weld mark; <NUM>-first part; <NUM>-second part; <NUM>-blocking member; <NUM>-battery; <NUM>-controller; <NUM>-motor; <NUM>-vehicle; <NUM>-manufacturing device; <NUM>-first supply device; <NUM>-second providing device; <NUM>-third providing device; <NUM>-assembling device; X-extension direction; Z-thickness direction.

In order to make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obvious, some, but not all of the embodiments of the present application are described. Based on the embodiments in the present application, all other embodiments, which are obtained by those skilled in the art without creative work, fall within the protection scope of the present application.

Unless defined otherwise, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the technical field of the present application. In the present application, the terms used in the specification of the present application are only for describing embodiments, not intended to limit the present application. The terms "comprising" and "having" and any variations thereof in the description and claims of the present application and the above description of the drawings are intended to cover non-exclusive inclusion. The terms "first", "second" and the like in the description and claims of the present application or the above drawings are used to distinguish different objects, rather than to describe a specific order or the primary and secondary relationship.

The "embodiment" mentioned in the present application means that a particular feature, structure, or characteristic, which is described in connection with the embodiment, can be included in at least one embodiment of the present application. The appearances of the term in various places in the specification do not necessarily refer to a same embodiment, or a separate or alternative embodiment that is mutually exclusive of other embodiments.

In the description of the present application, it should be noted that, unless expressly specified and limited otherwise, the terms, "installed", "connected with", "connected to" and "attached" should be understood in a broad sense. For example, it may be a fixed connection, or a detachable connection, or an integral connection. It can be directly connected, or indirectly connected through an intermediate medium, and it can be internally communicated between two components. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

In the embodiments of the present application, the same reference numeral denote the same component. For the sake of brevity, detailed description of the same component is omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components of the embodiments of the present application shown in the drawings, as well as the overall thickness, length and width, etc. of the integrated device are only exemplarily described, and should not constitute any limitation to the present application.

The appearance of "plurality" in the present application refers to two or more (including two).

In the present application, the battery cells may comprise lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., which are not limited in the embodiments of the present application. The battery cell may be in the form of a cylinder, a flat body, a cuboid, or other shapes, which are not limited in the embodiments of the present application. The battery cells are generally divided into three types according to the packaging method: a cylindrical battery cell, a square battery cell, and a soft-pack battery cell, which are not limited in the embodiments of the present application.

The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may comprise battery modules or battery packs, and the like. The battery typically comprises a box for enclosing one or more battery cells. The box can prevent liquids or other foreign objects from affecting the charging or discharging of the battery cells.

The battery cell comprises an electrode assembly and electrolyte, and the electrode assembly is composed of a positive electrode sheet, a negative electrode sheet and a separator. The battery cell works mainly relying on the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector, and the positive electrode current collector without being coated with the positive electrode active material layer protrudes from the positive electrode current collector coated with the positive electrode active material layer. With a lithium-ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganite, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode current collector not coated with the negative electrode active material layer protrudes from the negative electrode current collector coated with the negative electrode active material layer. The negative electrode current collector not coated with the negative electrode active material layer is used as the negative electrode tab. The material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon or silicon, etc. In order to ensure that a large current is passed without fusing, the number of positive tabs is plural and stacked together, and the number of negative electrode tabs is plural and stacked together. The material of the separator can be PP (polypropylene) or PE (polyethylene), and the like. In addition, the electrode assembly may be of a wound structure or a laminated structure, and the embodiment of the present application is not limited thereto.

For a common battery cell, the end cap needs to be welded with the tab of the electrode assembly to realize the electrical connection between the end cap and the tab, so that the end cap acts as the output pole (positive output pole or negative output pole) of the battery cell. The inventor found that, in order to ensure the firmness of the end cap and the tab after welding, the part of the end cap, which is welded with the tab, was relatively weak. When the external pressure is too large or the internal pressure of the battery cell is too large, the part of the end cap, which is welded with the tab, is easy to be damaged, affecting the service life of the battery cell.

In view of this, an embodiment of the present application provides a technical solution, wherein the end cap has an abutting surface and a welding groove, the abutting surface is configured for abutting against the first tab, and the welding groove is recessed from the side of the end cap away from the electrode assembly to the abutting surface. The end cap forms a connection part between the abutting surface and the bottom surface of the welding groove, the connection part is configured for being welded with the first tab, the end cap is provided with a reinforcing part protruding from the bottom surface of the welding groove, and the reinforcing part plays a role of strengthening the connection part configured for being welded with the first tab, so as to improve the strength of the connection part, reduce the risk that the battery cell is failure due to the damage of the connection part under pressure, and effectively improve the service life of the battery cell.

The technical solutions described in the embodiments of the present application are applicable to battery cells, batteries, and electrical device using batteries.

The electrical devices can be vehicles, mobile phones, portable devices, notebook computers, ships, spacecraft, electric toys and power tools, and so on. The vehicles can be fuel vehicles, gas vehicles or new energy vehicles, and the new energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles, etc.; the spacecraft comprise airplanes, rockets, space shuttles, spacecraft, etc.; the electric toys comprise electric toys of fixed type or mobile type, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.; the electric tools comprise metal cutting electric tools, grinding electric tools, assembling electric tools and railway electric tools, such as, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, electric impact drills, concrete vibrators and electric planers, etc. The embodiments of the present application do not impose special limitations on the above-mentioned electrical device.

In the following embodiments, for the convenience of description, the electric device is a vehicle, as an example for description.

Referring to <FIG>, it is a schematic structural diagram of a vehicle <NUM> provided by some embodiments of the present application. A battery <NUM> is disposed inside the vehicle <NUM>, and the battery <NUM> may be disposed at the bottom, head or tail of the vehicle <NUM>. The battery <NUM> may be configured for supplying power to the vehicle <NUM>, for example, the battery <NUM> may be used as an operating power source for the vehicle <NUM>.

The vehicle <NUM> may also comprise a controller <NUM> and a motor <NUM>, and the controller <NUM> is used for controlling the battery <NUM> to supply power to the motor <NUM>, e.g., for the work power requirements during starting, navigating, and driving the vehicle <NUM>.

In some embodiments of the present application, the battery <NUM> can be used as not only the operating power source of the vehicle <NUM>, but also the driving power source of the vehicle <NUM> to provide driving power for the vehicle <NUM>, replacing or partially replacing fuel or natural gas.

In some embodiments, referring to <FIG>, it is a schematic structural diagram of a battery <NUM> provided by some embodiments of the present application. The battery <NUM> comprises a box <NUM> and a battery cell <NUM>, and the box <NUM> is configured to accommodate the battery cell <NUM>.

The box <NUM> may comprise an accommodating part <NUM> and a covering part <NUM>, and the covering part <NUM> covers the accommodating part <NUM> to define a accommodating space <NUM> for receiving the battery cell <NUM>. The accommodating part <NUM> and the covering part <NUM> may be in various shapes, such as a cuboid, a cylinder, and the like. The accommodating part <NUM> can be of a hollow structure with one side open, and the covering part <NUM> can also be of a hollow structure with one side open. The open side of the covering part <NUM> covers the open side of the accommodating part <NUM> to form the box <NUM> with the accommodating cavity. As shown in <FIG>, it is also possible that the accommodating part <NUM> can be of a hollow structure with one side open, the covering part <NUM> is of a plate-like structure, and the covering part <NUM> covers the open side of the accommodating part <NUM> to form a box with an accommodating cavity <NUM>.

Herein, the accommodating part <NUM> and the covering part <NUM> can be sealed by a sealing element, and the sealing element can be a sealing ring, a sealant or the like.

In the battery <NUM>, there may be one battery cell <NUM> or a plurality of battery cells <NUM>. If a plurality of battery cells <NUM> are provided, the plurality of battery cells <NUM> may be connected in series or in parallel or in a mixed connection. A mixed connection means that some of the plurality of battery cells <NUM> are connected in series and the remaining are in parallel. A plurality of battery cells <NUM> may firstly be connected in series or in parallel or in mixed connection to form a battery module, and then a plurality of battery modules may be connected in series or in parallel or in mixed connection to form a whole, which is accommodated in the box <NUM>. It is also possible that all the battery cells <NUM> are directly connected in series, in parallel or in a mixed connection, and then the whole formed by all the battery cells <NUM> is accommodated in the box <NUM>.

In some embodiments, the battery <NUM> may further comprise a bus component, and the plurality of battery cells <NUM> may be electrically connected through the bus component, so as to realize the series, parallel or mixed connection of the plurality of battery cells <NUM>.

The bus component may be a metal conductor, such as, copper, iron, aluminum, stainless steel, aluminum alloys, and the like.

Referring to <FIG>, it is an exploded view of a battery cell <NUM> provided by some embodiments of the present application. The battery cell <NUM> comprises a housing <NUM>, an electrode assembly <NUM> and an end cap <NUM>. The housing <NUM> has an opening <NUM> and the housing <NUM> is configured to accommodate the electrode assembly <NUM>, the electrode assembly <NUM> has a first tab <NUM>, the end cap <NUM> is configured to connect with the housing <NUM> and cover the opening <NUM>, and the end cap <NUM> is configured to be welded with the first tab <NUM> to realize that the end cap <NUM> is electrically connected to the first tab <NUM>.

The end cap <NUM> is electrically connected to the first tab <NUM>, the end cap <NUM> can be used as an output pole (positive output pole or negative output pole) of the battery cell <NUM>, and the output pole is the portion of the battery cell <NUM>, which is connected with other components and outputs electrical energy of the battery cell <NUM>. In the case where the battery <NUM> comprises a plurality of battery cells <NUM> and the plurality of battery cells <NUM> can be electrically connected through a bus component, the end cap <NUM> of the battery cell <NUM> can be connected to the bus component to output electrical energy of the battery cell <NUM>.

In some embodiments, continuously referring to <FIG>, the battery cell <NUM> may further comprise a sealing member <NUM>, and the end cap <NUM> and the housing <NUM> are sealingly connected by the sealing member <NUM>, so that the end cap <NUM> and the housing <NUM> together form a sealing space for accommodating the electrode assembly <NUM> and the electrolyte.

The sealing member <NUM> may be of material, such as plastic, rubber, or the like.

In the embodiment of the present application, the housing <NUM> is configured to accommodate the electrode assembly <NUM>, and the housing <NUM> may be in various shapes, for example, a cylinder, a cuboid, and the like. The shape of the housing <NUM> may be determined according to the specific shape of the electrode assembly <NUM>. For example, if the electrode assembly <NUM> is of a cylindrical structure, the housing <NUM> can selectively is of a cylindrical structure; and if the electrode assembly <NUM> is of a cuboid structure, the housing <NUM> can selectively is of a cuboid structure. Exemplarily, in <FIG>, the housing <NUM> is a hollow cylindrical structure with one end open, and an opening <NUM> is formed at the open end of the housing <NUM>.

The housing <NUM> may be made of metal material, such as copper, iron, aluminum, steel, aluminum alloy, and the like.

In some embodiments, referring to <FIG>, it is a sectional view of the battery cell <NUM> shown in <FIG>. The housing <NUM> is form with a first limit part <NUM> and a second limit part <NUM>. The first limit part <NUM> is configured to limit the movement of the end cap <NUM> in the direction facing the electrode assembly <NUM> to reduce the risk that the end cap <NUM> moves towards the interior of the housing <NUM> to squeeze the electrode assembly <NUM>. The second limit part <NUM> is configured to limit the movement of the end cap <NUM> in a direction away from the electrode assembly <NUM>, so as to limit the end cap <NUM> from being separated from the housing <NUM>. Under the combined limitations of the first limit part <NUM> and the second limit part <NUM>, the end cap <NUM> cannot move relative to the housing <NUM> in the thickness direction Z of the end cap <NUM>.

Both the first limit part <NUM> and the second limit part <NUM> may be of an annular structure extending along the circumferential direction of the opening <NUM> of the housing <NUM>.

In the case where the end cap <NUM> and the housing <NUM> are sealingly connected by the sealing member <NUM>, the second limit part <NUM> can press a part of the sealing member <NUM> against the end cap <NUM>, and the end cap <NUM> can press a part of the sealing member <NUM> against the first limit part <NUM>, to realize the sealing connection between the end cap <NUM> and the housing <NUM>.

Exemplarily, a roller groove <NUM> is provided on the outer side surface of the housing <NUM>, and a first limit part <NUM> is formed on the inner side surface of the housing <NUM> at a position corresponding to the roller groove <NUM>, so that the housing <NUM> forms a necking structure at the position at which the first limit part <NUM> is formed.

In the actual production process, the roller groove <NUM> can be formed on the outer side surface of the housing <NUM> by means of rolling, and the first limit part <NUM> is naturally formed on the inner side surface of the housing <NUM>.

Exemplarily, the second limit part <NUM> may be a flanging structure formed at the position of the opening <NUM>, which is formed by partially folding the housing <NUM> inward.

In the process of assembling the battery cell <NUM>, the electrode assembly <NUM> can be accommodated in the housing <NUM> first, and then the end cap <NUM> is made to cover one end of the housing <NUM>, and the end cap <NUM>, under a restricting effect on the first limit part <NUM>, cannot move to the interior of the housing <NUM>, and finally the housing <NUM> is partially folded inward to form the second limit part <NUM>, so as to fix the end cap <NUM> to the housing <NUM>.

In some embodiments, the electrode assembly <NUM> may further comprise a main body part <NUM> and a second tab <NUM>. The polarities of the first tab <NUM> and the second tab <NUM> are opposite to each other, and both the first tab <NUM> and the second tab <NUM> are protruded from the main body part <NUM>, and the second tab <NUM> is configured for being electrically connected with the housing <NUM>.

Exemplarily, the first tab <NUM> and the second tab <NUM> protrude from opposite two ends of the main body part <NUM> in the thickness direction Z of the end cap <NUM>, respectively, and the second tab <NUM> is welded to the housing <NUM>, so as to realize that the second tab <NUM> is electrically connected with the housing <NUM>.

The polarities of the first tab <NUM> and the second tab <NUM> are opposite to each other. It is understandable that if the first tab <NUM> is a positive electrode tab, the second tab <NUM> is a negative electrode tab, and if the first tab <NUM> is a negative electrode tab, the second tab <NUM> is the positive electrode tab.

Since the first tab <NUM> is electrically connected to the end cap <NUM> and the second tab <NUM> is electrically connected to the housing <NUM>, in order to reduce the risk of the short circuit between the positive and negative electrodes caused by the contact between the end cap <NUM> and the housing <NUM>, the end cap <NUM> can be connected to the end cap <NUM> in insulation manner. In the case where the end cap <NUM> and the housing <NUM> are sealed by the sealing member <NUM>, the end cap <NUM> and the housing <NUM> can also be insulated by the sealing member <NUM>, that is, the sealing member <NUM>, located between the end cap <NUM> and the housing <NUM>, plays both a sealing role and an insulating role.

The main body part <NUM> may comprise a positive electrode sheet, a negative electrode sheet and a separator. The main body part <NUM> may be a rolled-type structure which is formed by winding a positive electrode sheet, a separator and a negative electrode sheet. The main body part <NUM> may also be a stacked-type structure which is formed by stacking the positive electrode sheet, the separator and the negative electrode sheet.

The positive electrode sheet comprises a positive electrode current collector and positive electrode active material layers coated on opposite sides of the positive electrode current collector. The negative electrode sheet comprises a negative electrode current collector and negative electrode active material layers coated on opposite sides of the negative electrode current collector. The main body part <NUM> may be the portion of the electrode assembly <NUM> corresponding to the area of the electrode sheet that is coated with the active material layer. The tab may be the portion of the electrode assembly <NUM> corresponding to the area of the electrode sheet that is not coated with the active material layer. It is understandable that the positive electrode tab may be the area on the positive electrode sheet that is not coated with the positive active material layer, and the negative electrode tab may be the area on the negative electrode sheet that is not coated with the negative electrode active material layer.

In some embodiments, the end cap <NUM> and the second limit part <NUM> of the housing <NUM> are respectively used as two output poles of the battery cell <NUM>. It is possible that the end cap <NUM> is used as the positive output pole of the battery cell <NUM>, and the second limit part <NUM> can be used as the negative output pole of the battery cell <NUM>; or it is possible that the end cap <NUM> is used as the negative output pole of the battery cell <NUM>, and the second limit part <NUM> is used as the positive output electrode of the battery cell <NUM>.

As an example in which the two battery cells <NUM> are electrically connected through the bus component to realize the series connection of the two battery cells <NUM>, the second limit part <NUM> of one battery cell <NUM> and the end cap <NUM> of the other battery cell <NUM> are both connected to the same bus component, e.g., by welding.

In the embodiment of the present application, referring to <FIG> is a front axonometric view of the end cap <NUM> shown in <FIG>. The end cap <NUM> has an abutting surface <NUM> and a welding groove <NUM>, and the abutting surface <NUM> is used for abutting against the first tab <NUM>. The welding groove <NUM> is recessed from the side of the end cap <NUM> away from the electrode assembly <NUM> toward the abutting surface <NUM>. The end cap <NUM> forms a connecting part <NUM> between the abutting surface <NUM> and the bottom surface <NUM> of the welding groove <NUM>. The connection part <NUM> is used for being welded with the first tab <NUM>, wherein the end cap <NUM> is provided with a reinforcing part <NUM>, the reinforcing part <NUM> is protruded from the bottom surface <NUM> of the welding groove <NUM>, and the reinforcing part <NUM> is used to enhance the strength of the connecting portion <NUM>.

The end cap <NUM> is provided with a reinforcing part <NUM> protruding from the bottom surface <NUM> of the welding groove <NUM>. The reinforcing part <NUM> can strengthen the connection part <NUM> for being welded with the first tab <NUM>, thereby increasing the strength of the connection part <NUM>, reducing the risk of failure of the battery cell <NUM> due to the damage of the connection part <NUM>, and effectively enhancing the service life of the battery cell <NUM>.

It should be noted that a connection part <NUM> is formed between the abutting surface <NUM> of the end cap <NUM> and the bottom surface <NUM> of the welding groove <NUM>. It is understood that the part of the end cap <NUM>, which has a thickness, between the abutting surface <NUM> and the bottom surface <NUM> of the welding groove <NUM>, is the connection part <NUM>, and the thickness of the connection part <NUM> is the distance between the abutting surface <NUM> and the bottom surface <NUM> of the welding groove <NUM>.

The reinforcing part <NUM> acts to reinforce the connection part <NUM>, and the reinforcing part <NUM> is connected to the groove side surface of the welding groove <NUM>. The reinforcing part <NUM> and the connection part <NUM> may be of an integrally formed structure or a separate structure. For example, the reinforcing part <NUM> and the connection part <NUM> are of a separate structure, and the reinforcing part <NUM> is connected to the bottom surface <NUM> of the welding groove <NUM> and the groove side surface of the welding groove <NUM> by bonding or welding.

The reinforcing part <NUM> is protruded from the bottom surface <NUM> of the welding groove <NUM>, that is, the reinforcing part <NUM> is at least partially located in the welding groove <NUM>. Of course, the reinforcing part <NUM> may be partially located in the welding groove <NUM>, or it may be completely located in the welding groove <NUM>.

Exemplarily, in <FIG>, the reinforcing part <NUM> is completely located in the welding groove <NUM>, so that the reinforcing part <NUM> does not protrude out of the welding groove <NUM>, and the reinforcing part <NUM> does not occupy the space outside the battery cell <NUM>.

In some embodiments, the welding groove <NUM> is an annular groove extending along the circumferential direction of the end cap <NUM>. The annular groove has an inner groove surface <NUM> and an outer groove surface <NUM> arranged coaxially, and the reinforcing part <NUM> is connected to the inner groove surface <NUM> and the outer groove surface <NUM>.

Since the welding groove <NUM> is an annular groove extending along the circumferential direction of the end cap <NUM>, the connection part <NUM> can be welded at plural positions, in the circumferential direction of the annular groove, which is beneficial to improve the firmness between the connection part <NUM> and the first tab <NUM> after welding. In addition, since the reinforcing part <NUM> is connected to the inner groove surface <NUM> and the outer groove surface <NUM> of the welding groove <NUM>, the firmness of the reinforcing part <NUM> is improved, and the reinforcing effect of the reinforcing part <NUM> on the connection part <NUM> is enhanced.

In other embodiments, the welding groove <NUM> may also of other shapes, for example, the welding groove <NUM> is a strip-shaped groove extending perpendicularly to the thickness direction Z of the end cap <NUM>.

In the embodiment of the present application, the reinforcing part <NUM> on the end cap <NUM> that plays a role of reinforcing the connection part <NUM> may be one or plural.

In some embodiments, the end cap <NUM> is provided with a plurality of reinforcing parts <NUM> at intervals along the extending direction X of the welding groove <NUM>, and the plurality of reinforcing parts <NUM> can each strengthen the connection part <NUM>, so that the connection parts <NUM> are reinforced at plural positions in the extending direction X of the welding groove <NUM>, which further improves the strength of the connection part <NUM>.

In the case that the welding groove <NUM> is an annular groove extending along the circumferential direction of the end cap <NUM>, the extending direction X of the welding groove <NUM> is the circumferential direction of the welding groove <NUM>, and the plurality of reinforcing parts <NUM> are circumferentially distributed in the welding groove <NUM>.

Optionally, the plurality of reinforcing parts <NUM> are circumferentially and evenly distributed in the welding groove <NUM>.

Exemplarily, in <FIG>, the end cap <NUM> is provided with four reinforcing parts <NUM>, and the four reinforcing parts <NUM> are circumferentially and evenly distributed in the welding groove <NUM>.

Referring to <FIG> is a top view of the end cap <NUM> shown in <FIG>. The connection part <NUM> and the first tab <NUM> (not shown in <FIG>) are welded to form a weld mark <NUM>. The weld mark <NUM> comprises a first part <NUM> and the second part <NUM> continuously arranged. According to the invention, the first part <NUM> is formed on the reinforcing part <NUM>, and the second part <NUM> is formed on the connection part <NUM>, which can reduce the risk that the connection part <NUM> is punched through by welding due to the high initial welding temperature.

In the actual welding process, the welding can be started from the reinforcing part <NUM>, so that the first part <NUM> is formed on the reinforcing part <NUM>, and then the connection part <NUM> and the tab are welded to form the second part <NUM> on the reinforcing part. Since the welding is started at the reinforcing part, the overall thickness of the end cap <NUM> at the position of the reinforcing part <NUM> is relatively large, which can withstand higher welding temperatures. Even if the initial welding temperature is relatively high, the end cap <NUM> is not easily punched through by welding.

The second part <NUM> of the weld mark <NUM> is formed on the connection part <NUM> to realize the welding of the connection part <NUM> and the first tab <NUM>. The first part <NUM> of the weld mark <NUM> is formed on the reinforcing part <NUM>. If the welding depth corresponding to the first part <NUM> is small, the reinforcing part <NUM> and the first tab <NUM> are not welded together. If the welding depth corresponding to the first part <NUM> is relatively large, the reinforcing part <NUM> and the first tab <NUM> are welded together.

In some embodiments, referring to <FIG> and <FIG>, in the thickness direction Z of the end cap <NUM>, the reinforcing part <NUM> has a first end <NUM> and a second end <NUM> arranged oppositely, and the first end <NUM> is connected to the bottom surface of <NUM> of the welding groove <NUM>. The dimension of the reinforcing part <NUM> in the extending direction X of the welding groove <NUM> (the width of the reinforcing part <NUM>) gradually decreases from the first end <NUM> to the second end <NUM>, so that at least one side of the reinforcing part <NUM> in the extending direction X of the welding groove <NUM> is provided with a sloping surface <NUM>, the sloping surface <NUM> is connected to the bottom surface <NUM> of the welding groove <NUM>, and the first part <NUM> is formed on the sloping surface <NUM>.

Since the dimension of the reinforcing part <NUM> in the extending direction X of the welding groove <NUM> gradually decreases from the first end <NUM> of the reinforcing part <NUM>, that is connected to the bottom surface <NUM>, to the second end <NUM> of the reinforcing part <NUM>, which faces away from the bottom surface <NUM>, so that the reinforcing part <NUM> is of a structure with the thickness gradient, which saves materials while ensuring that the reinforcing part <NUM> has better reinforcing ability. In addition, since the reinforcing part <NUM> is of a structure with gradient thickness, at least one side of the reinforcing part <NUM> in the extending direction X of the welding groove <NUM> forms a sloping surface <NUM> connected to the bottom surface <NUM> of the welding groove <NUM>. During welding the connection part <NUM> with the first tab <NUM>, the sloping surface <NUM> of the reinforcing rib can be used as the initial welding position to form the first part <NUM> of the weld mark <NUM> on the sloping surface <NUM>. After the welding temperature is decreased, the welding is performed on the connection part <NUM> and the first tab <NUM>, so as to reduce the risk that the connection part <NUM> is punched through by welding, due to the high initial welding temperature.

Exemplarily, in <FIG> and <FIG>, sloping surfaces <NUM> are formed on both sides of the reinforcing part <NUM> in the extending direction X of the welding groove <NUM>, that is, the reinforcing part <NUM> has two sloping surfaces <NUM>. It is possible to use one sloping surface <NUM> of the reinforcing part <NUM> as the starting position for welding, or both sloping surfaces <NUM> of the reinforcing part <NUM> as the starting positions for welding.

Referring to <FIG>, it is a partial view of the battery cell <NUM> shown in <FIG>. The end cap <NUM> may comprise a cap body <NUM> and a convex part <NUM>. The cap body <NUM> is configured to connect with the housing <NUM> and cover the opening <NUM>. In the thickness direction Z of the end cap <NUM>, the cap body <NUM> has an outer surface <NUM> and an inner surface <NUM> arranged oppositely. The welding groove <NUM> (not shown in <FIG>) is recessed from the outer surface <NUM> towards the abutting surface <NUM>. The convex part <NUM> is in the thickness direction Z of the end cap <NUM>. The convex part <NUM> protrudes from the inner surface <NUM> towards the electrode assembly <NUM>. One end of the convex part <NUM> away from the inner surface <NUM> forms the abutting surface <NUM>. This structure can easily ensure the flatness of the abutting surface <NUM>, so that the abutting surface <NUM> and the first tab <NUM> are kept in good contact, thereby increasing the flow area.

Exemplarily, the cap body <NUM> is sealingly connected to the housing <NUM> through the sealing member <NUM>. In the thickness direction Z of the end cap <NUM>, the first limit part <NUM> is located on the side of the cap body <NUM> facing the electrode assembly <NUM>, and the second limit part <NUM> is located on the side of the cap body <NUM> away from the electrode assembly <NUM>. The first limit part <NUM> and the second limit part <NUM> cooperate with each other to limit the movement of the cap body <NUM> relative to the housing <NUM> along the thickness direction Z of the end cap <NUM>.

In some embodiments, the end cap <NUM> is provided with a liquid injection hole <NUM> and a flow guiding channel <NUM>. The liquid injection hole <NUM> is configured for allowing the electrolyte to enter the interior of the battery cell <NUM> from the outside of the battery cell <NUM>, and the outer peripheral surface <NUM> of the convex part <NUM> is located on the outer periphery of the liquid injection hole <NUM>. The flow guiding channel <NUM> communicates with the liquid injection hole <NUM> and penetrates the outer peripheral surface <NUM> of the convex part <NUM>. The flow guiding channel <NUM> is used for allowing at least part of the electrolyte to flow to outside of the outer peripheral surface <NUM>.

During the process of injecting the electrolyte into the battery cell <NUM> through the injection hole <NUM>, the electrolyte can flow laterally through the flow guiding channel <NUM> and flow to outside of the outer peripheral surface <NUM> of the convex part <NUM>, which can effectively improve the injection efficiency and make the electrolysis sufficiently and rapidly infiltrate the electrode sheets in the electrode assembly <NUM>.

As an example in which the welding groove <NUM> is an annular groove, the liquid injection hole <NUM> may be disposed coaxially with the welding groove <NUM>. The liquid injection hole <NUM> may also be arranged coaxially with the central hole <NUM> of the electrode assembly <NUM>.

The number of flow guiding channels <NUM> on the end cap <NUM> may be one or plural. In some embodiments, the end cap <NUM> is provided with a plurality of flow guiding channels <NUM>, and the flow guiding channels <NUM> are circumferentially distributed at intervals with the liquid injection hole <NUM> as the center, so that the electrolyte can flow, through the plurality of flow guiding channels <NUM>, towards a plurality of different directions, thereby improving the injection efficiency.

In some embodiments, the battery cell <NUM> may further comprise a blocking member <NUM>, and the blocking member <NUM> is configured to block the liquid injection hole <NUM>. After the electrolyte is injected into the battery <NUM>, the liquid injection hole <NUM> can be blocked by the blocking member <NUM> to prevent the electrolyte from leaking from the liquid injection hole <NUM>.

In the embodiment of the present application, the flow guiding channel <NUM> communicates with the liquid injection hole <NUM>, which may be the direct communication between the flow guiding channel <NUM> and the liquid injection hole <NUM>, or the indirect communication between the flow guiding channel <NUM> and the liquid injection hole <NUM>.

In some embodiments, the flow guiding channel <NUM> is indirectly connected with the liquid injection hole <NUM>. Specifically, the end cap <NUM> is provided with a concave part <NUM>, the welding groove <NUM> is located on the outer periphery of the concave part <NUM>, the concave part <NUM> is recessed from the abutting surface <NUM> towards the direction away from the electrode assembly <NUM>, and the flow guiding channel <NUM> communicates with the liquid injection hole <NUM> through the concave part <NUM>.

Since the welding groove <NUM> is located on the outer periphery of the concave part <NUM>, the welding groove <NUM> and the concave part <NUM> do not affect each other. The concave part <NUM> plays the role of making the flow guiding channel <NUM> and the liquid injection hole <NUM> communicated with each other. Since the concave part <NUM> is recessed from the abutting surface <NUM> towards the direction away from the electrode assembly <NUM>, after the electrolyte enters the concave part <NUM> through the liquid injection hole <NUM>, a part of the electrolyte can directly enter the interior of the electrode assembly <NUM> through the concave part <NUM> to infiltrate the electrode sheet, and a part of the electrolyte can enter the flow guiding channel <NUM> through the concave part <NUM> and flow laterally inside the flow guiding channel <NUM> to outside of the outer peripheral surface <NUM> of the convex part <NUM>, improving the liquid injection efficiency, at the same increasing the infiltration effect of the electrolyte on the electrode assembly <NUM>.

Exemplarily, the concave part <NUM> is disposed coaxially with the liquid injection hole <NUM>.

Optionally, one end of the flow guiding channel <NUM> penetrates the outer peripheral surface <NUM> of the convex part <NUM>, and the other end of the flow guiding channel <NUM> penetrates the inner peripheral surface <NUM> of the concave part <NUM>, so that the electrolyte can enter the flow guiding channel <NUM> from the concave part <NUM>, and flows laterally in the flow guiding channel <NUM>.

Exemplarily, the flow guiding channel <NUM> may extend along the radial direction of the liquid injection hole <NUM>.

In some embodiments, the end cap <NUM> has a liquid outlet surface <NUM> located in the concave part <NUM>, and one end of the liquid injection hole <NUM> penetrates the liquid outlet surface <NUM>. In the thickness direction Z of the end cap <NUM>, the liquid outlet surface <NUM> is farther away from the electrode assembly <NUM> than the abutting surface <NUM>. This structure enables a distance exists between the liquid outlet surface <NUM> and the electrode assembly <NUM>, which facilitates that the electrolyte enters the concave part <NUM> from the liquid injection hole <NUM>, and facilitates that the electrolyte enters the flow guiding channel <NUM> through the concave part <NUM>.

In some embodiments, the flow guiding channel <NUM> is disposed on the end cap <NUM> at a position corresponding to the reinforcing part <NUM>. The reinforcing part <NUM> can strengthen the end cap <NUM> at the position where the flow guiding channel <NUM> is arranged, and improve the strength of the position where the flow guiding channel <NUM> is arranged on the end cap <NUM>.

The flow guiding channels <NUM> correspond to the reinforcing parts <NUM> one-to-one. If there is one flow guiding channel <NUM>, there will be one reinforcing part <NUM>, and if there are plural flow guiding channels <NUM>, there will be plural reinforcing parts <NUM>.

In some embodiments, referring to <FIG> is a reverse axonometric view of the end cap <NUM> shown in <FIG>. The flow guiding channel <NUM> is a flow guiding groove disposed on the abutting surface <NUM>.

In the production process, the guiding grooves can be directly formed, by processing, on the abutting surface <NUM>, to form the guiding channels <NUM>. Under the condition that the flow guiding channel <NUM> is disposed on the end cap <NUM> at a position corresponding to the reinforcing part <NUM>, the arrangement of the reinforcing part <NUM> enables that the flow guiding groove is recessed more deeply, from the abutting surface <NUM>, along the direction away from the electrode assembly <NUM> (not shown in <FIG>), which is conducive to the flow of the electrolyte in the flow guiding groove, effectively improving the injection efficiency.

In addition, since the abutting surface <NUM> faces the electrode assembly <NUM>, the flow guiding groove is provided on the abutting surface <NUM>, so that the side of the flow guiding groove facing the electrode assembly <NUM> is open, and the electrolyte, during flowing laterally through the flow guiding channel <NUM>, has a part capable of flowing toward the interior of the electrode assembly <NUM> along the direction facing the electrode assembly <NUM> (towards the electrode assembly), which is beneficial for the electrolyte to infiltrate the electrode sheet.

In some embodiments, referring to <FIG> is a sectional view along A-A of the end cap <NUM> shown in <FIG>. The flow guiding groove has the first groove wall <NUM> and the second groove wall <NUM> opposite to each other. The reinforcing part <NUM> comprises the first and second sloping surfaces 2343a and 2343b opposing to each other. The first and second sloping surfaces 2343a and 2343b are configured in such a way that the dimension of the reinforcing part <NUM> in the extending direction X of the welding groove <NUM> gradually decreases from the end of the reinforcing part <NUM> facing the bottom surface <NUM> to the end of the reinforcing part <NUM> away from the bottom surface <NUM>. The first sloping surface 2343a is parallel to the first groove wall <NUM>, and the second sloping surface 2343b is parallel to the second groove wall <NUM>. This structure makes the wall thicknesses of individual portions of the reinforcing part <NUM> uniform without sudden change, and enhances the ability of the reinforcing part <NUM> reinforcing the connection part <NUM>.

It should be noted that the first sloping surface 2343a and the second sloping surface 2343b are the two sloping surfaces <NUM> (shown in <FIG>) of the reinforcing part <NUM> in the extending direction X of the welding groove <NUM>. The end of the reinforcing part <NUM> facing the bottom surface <NUM> is the first end <NUM> of the reinforcing part <NUM> (shown in <FIG>), and the end of the reinforcing part <NUM> away from the bottom surface <NUM> is the second end <NUM> of the reinforcing part <NUM> (shown in <FIG>). That is to say, the first sloping surface 2343a and the second sloping surface 2343b are arranged such that the dimension of the reinforcing part <NUM> in the extending direction X of the welding groove <NUM> gradually decrease from the first end <NUM> to the second end <NUM>, which can also be understood in the way that the distance between the first sloping surface 2343a and the second sloping surface 2343b in the extending direction X of the welding groove <NUM> gradually decreases from the first end <NUM> to the second end <NUM>.

In some embodiments, referring to <FIG>, it is a sectional view along B-B of the end cap <NUM> shown in <FIG>. In the thickness direction Z of the end cap <NUM>, the distance between the abutting surface <NUM> and the bottom surface <NUM> of the welding groove <NUM> is less than or equal to the distance between the outer surface <NUM> of the cap body <NUM> and the inner surface <NUM> of the cap body <NUM>, that is, the thickness of the connection part <NUM> is less than or equal to the thickness of the cap body <NUM>, which reduces the risk that the welding between the connection part <NUM> and the first tab <NUM> is weak due to the connection part being too thick.

Exemplarily, in <FIG>, the distance between the abutting surface <NUM> and the bottom surface <NUM> of the welding groove <NUM> is smaller than the distance between the outer surface <NUM> of the cap body <NUM> and the inner surface <NUM> of the cap body.

Optionally, the bottom surface <NUM> of the welding groove <NUM> is closer to the abutting surface <NUM> than the inner surface <NUM> of the cap body <NUM>, so that the welding groove <NUM> is recessed into the convex part <NUM>.

Embodiments of the present application provide a method for manufacturing a battery cell <NUM>. Referring to <FIG> is a flowchart of a method for manufacturing the battery cell <NUM> provided by some embodiments of the present application. The manufacturing method comprises:.

Here, the end cap <NUM> has an abutting surface <NUM> and a welding groove <NUM>, the abutting surface <NUM> is configured to abut against the first tab <NUM>, and the welding groove <NUM> is recessed from the side of the end cap <NUM> away from the electrode assembly <NUM>, towards the abutting surface <NUM>. The end cap <NUM> forms a connection part <NUM> between the abutting surface <NUM> and the bottom surface <NUM> of the welding groove <NUM>, and the connection part <NUM> is configured for being welded with the first tab <NUM>. The end cap <NUM> is provided with a reinforcing part <NUM>, the reinforcing part <NUM> is protruded from the bottom surface <NUM>, and the reinforcing part <NUM> is configured to enhance the strength of the connection part <NUM>.

In the above method, the sequence of step S100, step S200 and step S300 is not limited. For example, step S300 may be performed first, then step S200 may be performed, and then step S100 may be performed.

It should be noted that, the battery cells <NUM> provided in the foregoing embodiments may be referred to, for obtaining the related structures of the battery cells <NUM> manufactured by the manufacturing method provided in the foregoing embodiments, which is not described herein again.

In addition, an embodiment of the present application further provides a device <NUM> for manufacturing a battery cell <NUM>. Referring to <FIG> is a schematic block diagram of a device <NUM> for manufacturing a battery cell <NUM> provided by some embodiments of the present application. The manufacturing device <NUM> comprises a first providing device <NUM>, a second providing device <NUM> and a third providing device <NUM>.

The first providing device <NUM> is configured to provide the electrode assembly <NUM>, and the electrode assembly <NUM> has a first tab <NUM>. The second providing device <NUM> is configured for providing the housing <NUM> and the housing has an opening <NUM>. The third providing device <NUM> is configured to provide the end cap <NUM>. The assembling device <NUM> is configured for making the electrode assembly <NUM> accommodated in the housing <NUM>, and the assembling device <NUM> is also configured for connecting the end cap <NUM> to the housing <NUM>, so that the end cap <NUM> covers the opening <NUM> of the housing <NUM>.

It should be noted that, the battery cells <NUM> provided in the foregoing embodiments may be referred to, for obtaining the related structure of the battery cell <NUM> manufactured by the manufacturing device <NUM> provided in the foregoing embodiment, which not described herein again.

Claim 1:
A battery cell (<NUM>), comprising:
an electrode assembly (<NUM>), having a first tab (<NUM>);
a housing (<NUM>), having an opening (<NUM>), with the housing (<NUM>) configured to receive the electrode assembly (<NUM>); and
an end cap (<NUM>), configured to connect with the housing (<NUM>) and covering the opening (<NUM>), wherein the end cap (<NUM>) has an abutting surface (<NUM>) and a welding groove (<NUM>), the abutting surface (<NUM>) is configured to abut against the first tab (<NUM>), the welding groove (<NUM>) is recessed from one side of the end cap (<NUM>) away from the electrode assembly (<NUM>) towards the abutting surface (<NUM>), the end cap (<NUM>) forms a connection part (<NUM>) between the abutting surface (<NUM>) and a bottom surface (<NUM>) of the welding groove (<NUM>), and the connection part (<NUM>) is configured to be welded with the first tab (<NUM>),
wherein the end cap (<NUM>) is provided with a reinforcing part (<NUM>), the reinforcing part (<NUM>) is protruded from the bottom surface (<NUM>), and the reinforcing part (<NUM>) is configured to enhance strength of the connection part (<NUM>),
characterized in that the connection part (<NUM>) is welded with the first tab (<NUM>) to form a weld mark (<NUM>), the weld mark (<NUM>) comprises a first part (<NUM>) and a second part (<NUM>) that are continuously arranged, and the first part (<NUM>) is formed at the reinforcing part (<NUM>), and the second part (<NUM>) is formed on the connection part (<NUM>).