Patent Description:
Battery cells are widely used in electronic devices, such as mobile phones, laptop computers, battery cars, electric vehicles, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes, and electric tools. The battery cells may include nickel-cadmium battery cells, nickel-hydrogen battery cells, lithium-ion battery cells, secondary alkaline zinc-manganese battery cells, and the like.

In the development of battery technologies, in addition to improving the performance of the battery cells, safety is also an issue that cannot be ignored. If the safety of a battery cell cannot be guaranteed, the battery cell cannot be used. Therefore, how to enhance the safety of the battery cells is an urgent technical problem to be solved in battery technology. <CIT>, <CIT>, <CIT>, <CIT> and <CIT> also disclose pressure relief mechanism for batteries.

The present application provides a battery cell, a manufacturing method and a manufacturing system thereof, a battery, and a powered device, which can enhance the safety of the battery cell.

The invention is defined by independent claims <NUM>, <NUM> and <NUM>, preferred embodiments are as set out in the dependent claims. In a first aspect the invention is a battery cell according to claim <NUM>, including: a shell, where the shell has a wall portion; an electrode assembly, where the electrode assembly is accommodated in the shell; a pressure relief mechanism, where the pressure relief mechanism is provided on the wall portion, the pressure relief mechanism includes a weak portion, a body portion, and a connecting portion, the weak portion is configured to be damaged when pressure inside the shell reaches a threshold so as to relieve the pressure, the body portion is located in a region defined by the weak portion, and the connecting portion is located on an outer side of the weak portion and configured to connect the wall portion; the body portion protrudes relative to the connecting portion in a direction away from the electrode assembly, and a first concave portion is formed in the pressure relief mechanism at a position corresponding to the body portion on a side facing the electrode assembly.

In the battery cell according to the present invention, the body portion protrudes relative to the connecting portion in a direction away from the electrode assembly, a sudden change in a cross section occurs at the weak portion, stress concentration occurs in the weak portion, and the first concave portion is formed in the pressure relief mechanism at a position corresponding to the body portion on a side facing the electrode assembly, which further aggravates the stress concentration of the weak portion, making the weak portion easy to break and capable of releasing pressure when the pressure in the shell reaches a threshold, and ensures the safety of the battery cell in the case of thermal runaway thereby improving stability and safety of use of the battery cell.

In some examples, the weak portion is formed by providing a groove on the pressure relief mechanism.

In the above solution, a groove is provided to reduce a local thickness of the pressure relief mechanism, so as to form the weak portion.

In some examples, a thickness of the body portion and a thickness of the connecting portion are both greater than a thickness of the weak portion.

According to the present invention, the weak portion has lower strength than the body portion and the connecting portion, and can be more easily damaged so as to relieve the pressure of the battery cell in time.

In some examples, the thickness of the connecting portion is B1 and the thickness of the weak portion is W1, where <NUM>≤W1/B1≤<NUM>.

In the above scheme, when the thicknesses of the weak portion and the connecting portion are within the above numerical range, machining accuracy of the weak portion can be improved, thereby improving uniformity of the thickness of the weak portion. When the weak portion is subjected to alternating stress, degrees of damages to the weak portion is relatively uniform so that blasting consistency of the battery can be improved.

When W1/B1<<NUM>, the thickness of the weak portion is relatively thin, the strength of the weak portion is low, and the weak portion is easily damaged when the battery cell does not undergo thermal runaway. Moreover, when the weak portion with the thickness is formed, a dimension of the weak portion fluctuates greatly, and the thickness thereof has poor uniformity. When weak portions of different battery cells are subjected to alternating stress, regions or degrees of fatigue aging may be different, resulting in poor consistency of blasting pressure relief of different battery cells.

When W1/B1><NUM>, the thickness of the weak portion is relatively thick, and the strength of the weak portion is high. When a preset pressure value of the battery cell is small, the weak portion is not easy to be damaged. When the battery cell is subjected to thermal runaway, gas inside the battery cell cannot be discharged in time, and the battery cell is prone to expansion or even explosion.

In some examples, projections of the groove and the first concave portion in a first direction at least partially overlap, and the first direction is perpendicular to a thickness direction of the pressure relief mechanism.

In the above solution, the groove and the weak portion are arranged correspondingly in the thickness direction, and the projections of the groove and the first concave portion in the first direction at least partially overlap, which may aggravate the stress concentration of the weak portion, the weak portion can be more easily damaged so that the pressure of the battery cell can be relieved in time.

In some examples, the connecting portion has a first outer surface and a first inner surface along the thickness direction of the pressure relief mechanism, and the first inner surface faces the electrode assembly; and the groove is recessed relative to the first inner surface in a direction away from the electrode assembly; and/or the groove is recessed relative to the first outer surface in a direction toward the electrode assembly.

In some examples, the connecting portion has a first outer surface and a first inner surface along the thickness direction of the pressure relief mechanism, and the first inner surface faces the electrode assembly; and the first concave portion is recessed relative to the first inner surface in a direction away from the electrode assembly, and at least a part of the body portion protrudes from the first outer surface.

In some examples, in the thickness direction of the pressure relief mechanism, the thickness of the connecting portion is B <NUM>, and a height of the body portion is H, where H/B1≤ <NUM>.

In the above solution, when the thicknesses of the connecting portion and the body portion are within the above numerical range, the body portion has a moderate height and is easily machined, which can prevent interference between the body portion and a foreign matter outside the battery cell in a case where the stress concentration at the weak portion is aggravated.

When H/B1><NUM>, the body portion is excessively high and is not easily machined. Moreover, the excessively high body portion may protrude from a surface of the battery cell to interfere with a foreign matter outside the battery cell.

In some examples, the first concave portion has a bottom wall, the first concave portion is recessed from the first inner surface to the bottom wall in a direction away from the electrode assembly, and the bottom wall does not extend beyond the first outer surface in a direction away from the electrode assembly.

In the above solution, along the thickness direction, as a distance between the bottom wall and the first outer surface decreases, the first concave portion is recessed deeper in the thickness direction, stress concentration is more easily formed at a junction between the body portion corresponding to the position of the first concave portion and the weak portion, and the weak portion can be more easily damaged.

In some examples, the pressure relief mechanism further includes a transition portion, the transition portion is provided around the connecting portion and configured to connect the wall portion and the connecting portion, and a thickness of the transition portion is greater than that of the connecting portion.

In the above solution, the thickness of the transition portion is relatively thicker, which can improve welding strength of the transition portion and prevent distortion or burn-through during welding caused by a small thickness of the transition portion. In addition, the thickness of the connecting portion is relatively thinner so that the pressure relief mechanism is easily broken when subjected to alternating stress, and the pressure can be relieved in time.

In some examples, the thickness of the connecting portion is B1, and the thickness of the transition portion is B2, where B1/B2≤<NUM>/<NUM>.

In the above solution, when the thicknesses of the connecting portion and the transition portion are within this numerical range, the thicknesses of the connecting portion and the transition portion are moderate, which can satisfy both welding strength of the transition portion and a strength requirement of the connecting portion.

In some examples, the connecting portion has a first outer surface and a first inner surface along the thickness direction of the pressure relief mechanism, and the first inner surface faces the electrode assembly; the transition portion has a second outer surface and a second inner surface along the thickness direction of the pressure relief mechanism, and the second inner surface faces the electrode assembly; and the second outer surface protrudes from the first outer surface in a direction away from the electrode assembly; and/or the second inner surface protrudes from the first inner surface in a direction close to the electrode assembly.

In some examples, the body portion protrudes relative to the transition portion in a direction away from the electrode assembly.

In the above solution, a stepped structure is formed among the body portion, the weak portion, the connecting portion, and the transition portion, and the weak portion and the connecting portion are prone to stress concentration. In particular, the stress concentration of the weak portion may be aggravated, the weak portion is easily damaged, and the pressure of the battery cell can be relieved in time.

In some examples, a minimum dimension of the connecting portion along a first direction is greater than <NUM>, and the first direction is perpendicular to the thickness direction of the pressure relief mechanism.

In the above solution, the weak portion is closer to a central position of the pressure relief mechanism, the weak portion is subjected to more uniform alternating stress, and the consistency of the fracture of the weak portion is higher.

In some examples, the battery cell further includes a protective sheet, and the protective sheet is attached to an outer surface of the wall portion and covers the pressure relief mechanism.

In the above solution, the protective sheet can protect the pressure relief mechanism, and reduce distortion or dent formation of the pressure relief mechanism caused by an accidental impact or scratch of an external object on the pressure relief mechanism.

In some examples, the shell includes an end cap and a case, the case is provided with an opening, and the end cap is configured to cover the opening, where the wall portion is the end cap.

In the above solution, when the pressure relief mechanism is actuated to discharge high temperature and high pressure substances, the structure of the end cap may not be substantially affected.

In a second aspect, the present invention provides a battery according to claim <NUM> comprising the battery cell according to claims <NUM> to <NUM>.

In a third aspect, the present invention provides a power device according to claim <NUM>, comprising the battery according to claim <NUM>. The battery cell is configured to provide electrical energy.

In a fourth aspect, the present invention is a manufacturing method according to claim <NUM>, including: providing an end cap, where the end cap is provided with a pressure relief mechanism and an electrode terminal, the pressure relief mechanism includes a weak portion, a body portion, and a connecting portion, the body portion is located in a region defined by the weak portion, the connecting portion is located on an outer side of the weak portion and configured to connect the end cap, the body portion protrudes relative to the connecting portion, and a first concave portion is formed in the pressure relief mechanism at a position corresponding to the body portion; providing an electrode assembly; providing a case, where the case has an opening; connecting the electrode assembly to the electrode terminal; and placing the electrode assembly into the case, and then connecting the end cap to the case to close the opening of the case, where the weak portion is configured to be damaged when pressure inside the case reaches a threshold so as to relieve the pressure; the body portion protrudes relative to the connecting portion in a direction away from the electrode assembly, and the first concave portion is formed in the pressure relief mechanism at a position corresponding to the body portion on a side facing the electrode assembly.

In a fifth aspect, the invention is a manufacturing system for a battery cell according to independent claim <NUM>, including: a first providing device configured to provide an end cap, where the end cap is provided with a pressure relief mechanism and an electrode terminal, the pressure relief mechanism includes a weak portion, a body portion, and a connecting portion, the body portion is located in a region defined by the weak portion, the connecting portion is located on an outer side of the weak portion and configured to connect the end cap, the body portion protrudes relative to the connecting portion, and a first concave portion is formed in the pressure relief mechanism at a position corresponding to the body portion; a second providing device configured to provide an electrode assembly; a third providing device configured to provide a case, where the case has an opening; a first assembling device configured to connect the electrode assembly to the electrode terminal; and a second assembling device configured to place the electrode assembly into the case, and then connect the end cap to the case to close the opening of the case, where the weak portion is configured to be damaged when pressure inside the case reaches a threshold so as to relieve the pressure; the body portion protrudes relative to the connecting portion in a direction away from the electrode assembly, and the first concave portion is formed in the pressure relief mechanism at a position corresponding to the body portion on a side facing the electrode assembly.

In order to illustrate the technical solutions of the examples of the present invention more clearly, the drawings required in the examples of the present invention will be briefly introduced below. Obviously, the drawings described below are only some examples of the invention.

In the drawings, the drawings may not be drawn to actual scale.

thickness direction; Y. first direction; <NUM>. vehicle; 1a. controller; <NUM>. battery; <NUM>. bottom case; <NUM>. top case; <NUM>. battery; <NUM>. battery cell; <NUM>. shell; <NUM>. end cap; <NUM>. case; <NUM>. opening; <NUM>. through hole; <NUM>. electrode assembly; <NUM>. tab; <NUM>. electrode terminal; <NUM>. adapter member; <NUM>. pressure relief mechanism; <NUM>. body portion; <NUM>. connecting portion; 82a. first outer surface; 82b. first inner surface; <NUM>. weak portion; 83c. groove; <NUM>. first concave portion; <NUM>. bottom wall; <NUM>. transition portion; 85a. second outer surface; 85b. second inner surface.

In the examples of the present application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different examples. It should be understood that the thickness, length, width and other dimensions of various components in the examples of the present application shown in the accompanying drawings, as well as the overall thickness, length and width, etc. of the integrated device are only exemplary descriptions, and should not constitute any limitation to the present application.

In the present application, battery cells may include a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, etc., which is not limited in the examples of the present application. The battery cells may be cylindrical, flat, rectangular, or in other shapes, which is not limited in the examples of the present application. The battery cells are generally divided into three types according to packaging manners: cylindrical battery cells, rectangular battery cells, and pouch cells, which are not limited in the examples of the present application.

The battery mentioned in the examples of the present application refers to a single physical module including one or more battery cells to provide a higher voltage and capacity. For example, the battery mentioned in the present application may include a battery module, a battery pack, or the like. The battery typically includes a box body for encapsulating one or more battery cells. The box body can prevent the influence of liquids or other foreign matters on charging or discharging of the battery cell.

The battery cell includes an electrode assembly and an electrolyte solution. The electrode assembly is composed of a positive electrode sheet, a negative electrode sheet and an isolator. The battery cell operates mainly relying on movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. A surface of the positive electrode current collector is coated with the positive electrode active material layer. Current collectors not coated with the positive electrode active material layer protrude from the current collector coated with the positive electrode active material layer. The current collectors not coated with the positive electrode active material layer are stacked and serve as positive electrode tabs. Taking a lithium-ion battery as an example, the material of the positive electrode current collector may be aluminum, and a positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. A surface of the negative electrode current collector is coated with the negative electrode active material layer. Current collectors not coated with the negative electrode active material layer protrude from the current collector coated with the negative electrode active material layer. The current collectors not coated with the negative electrode active material layer are stacked and serve as negative electrode tabs. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon, silicon, or the like. A diaphragm may be made from polypropylene (PP), polyethylene (PE), or the like. In addition, the electrode assembly may be a wound structure or a laminated structure, which is not limited in the examples of the present application.

Many design factors, such as energy density, cycle life, discharge capacity, charge-discharge rate and other performance parameters, should be considered in the development of the battery technology. In addition, the safety of the battery also needs to be taken into account.

A pressure relief mechanism on the battery cell has an important impact on the safety of the battery. For example, when a short circuit, overcharge, or the like occurs, it may cause thermal runaway inside the battery cell, resulting in a sudden rise in pressure or temperature. In this case, internal pressure and temperature can be relieved outward through the actuation of the pressure relief mechanism to prevent explosion and fire of the battery cell.

The pressure relief mechanism refers to an element or component that is actuated to relieve the internal pressure or temperature when the internal pressure or temperature of the battery cell reaches a predetermined threshold. The design of the threshold varies according to different design requirements. The threshold may depend on the materials of one or more of the positive electrode sheet, the negative electrode sheet, the electrolyte solution, and the isolator in the battery cell. The pressure relief mechanism may take the form of an explosion-proof valve, a gas valve, a pressure relief valve or a safety valve, etc., and may specifically adopt a pressure-sensitive or temperature-sensitive element or structure. That is, when the internal pressure or temperature of the battery cell reaches a predetermined threshold, the pressure relief mechanism performs an action or a weak structure provided in the pressure relief mechanism is damaged, so as to form an opening or channel for releasing the internal pressure or temperature.

The word "actuate" as mentioned in the present application means that the pressure relief mechanism is actuated or activated to a certain state, so that the internal pressure and temperature of the battery cell can be relieved. Actions produced by the pressure relief mechanism may include, but are not limited to, at least a part of the pressure relief mechanism being broken, crushed, torn or opened, and the like. When the pressure relief mechanism is actuated, high temperature and high pressure substances inside the battery cell may be discharged outward from the actuated part as emissions. In this way, the pressure and temperature of the battery cell can be relieved under controllable pressure or temperature, so as to prevent potential more serious accidents.

The emissions from the battery cell mentioned in the present application include, but are not limited to, the electrolyte solution, dissolved or split positive and negative electrode sheets, fragments of the isolator, high temperature and high pressure gas generated by reaction, flames, and the like.

The applicant has found that, during the cycle of the battery cell, the battery cell does not blast and relieves pressure even when reaching a predetermined condition of thermal runaway, and thus the structure and use environment of the battery cell have been analyzed and studied. In the process of transportation, temperature change or charging and discharging of the battery cell, the internal pressure of the battery cell changes alternately between high and low, which causes the pressure relief mechanism to flip back and forth. That is, the pressure relief mechanism is subjected to the alternating stress generated by the gas inside the battery cell. The applicant has found that when the preset pressure value of the battery cell is small, the requirement on the strength of the pressure relief mechanism is correspondingly low. However, in order to ensure the dimensional accuracy of the pressure relief mechanism, there is a need to maintain the pressure relief mechanism with a certain strength. In this way, the battery cell is not prone to fatigue deformation or fracture even if subjected to the alternating stress generated by the gas inside the battery cell, and even when the internal pressure of the battery cell exceeds the preset pressure value, the pressure relief mechanism may not break, and the battery cell cannot exhaust in time, causing safety hazards.

Based on the above problems found by the applicant, the applicant has improved the structure of the battery cell. The technical solutions described in the examples of the present application are applicable to a battery cell, a battery including the battery cell, and a powered device using the battery.

The powered device may be, but not limited to, a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle may be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle may be an all-electric vehicle, a hybrid electric vehicle, an extended-range electric vehicles, or the like. The aircraft includes airplanes, rockets, space shuttles, spacecraft, and the like. The electric toy includes fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. The electric tool includes 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. The examples of the present application do not impose special limitations on the above powered apparatus.

In the following examples, for the convenience of description, the powered device is a vehicle.

As shown in <FIG>, a battery <NUM> is provided inside a vehicle <NUM>. The battery <NUM> may be provided at the bottom or head or rear of the vehicle <NUM>. The battery <NUM> may be configured to power the vehicle <NUM>. For example, the battery <NUM> may be used as an operating power source of the vehicle <NUM>.

The vehicle <NUM> may also include a controller 1b and a motor 1a. The controller 1b is configured to control the battery <NUM> to supply power to the motor 1a, for example, configured for operation power requirements of the vehicle <NUM> for starting, navigating and driving.

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

As shown in <FIG> and <FIG>, the battery <NUM> includes a battery cell <NUM> (not shown in <FIG>). The battery <NUM> may also include a box body for accommodating the battery cell <NUM>.

The box body is used for accommodating the battery cell <NUM>, and the box may be in various structural forms.

In some examples, the box body may include a bottom case <NUM> and a top case <NUM>. The bottom case <NUM> and the top case <NUM> are covered with each other. The bottom case <NUM> and the top case <NUM> together define an accommodating space for accommodating the battery cell <NUM>. The bottom case <NUM> and the top case <NUM> may both have a hollow structure with one side open. An open side of the bottom case <NUM> covers the open side of the top case <NUM> to form a box body with an accommodating space. A sealing member may also be provided between the bottom case <NUM> and the top case <NUM> to achieve a sealed connection between the bottom case <NUM> and the top case <NUM>.

In practice, the bottom case <NUM> may cover the top of the top case <NUM>. The bottom case <NUM> may also be referred to as an upper box, and the top case <NUM> may also be referred to as a lower box.

The bottom case <NUM> and the top case <NUM> may have various shapes, for example, a cylinder, a cuboid, and the like. In <FIG>, by way of example, the bottom case <NUM> and the top case <NUM> are both of a cuboid structure.

In the battery <NUM>, one or more battery cells <NUM> may be provided. If there are a plurality of battery cells <NUM>, the plurality of battery cells <NUM> may be connected in series or in parallel or in a combination thereof. The "in a combination thereof" means that the plurality of battery cells <NUM> are connected in series and in parallel. The plurality of battery cells <NUM> may be directly connected in series or in parallel or in a combination thereof, and then an entirety composed of the plurality of battery cells <NUM> may be accommodated in the box body, or the plurality of battery cells <NUM> may be connected in series or in parallel or in a combination thereof to form battery modules <NUM>. A plurality of battery modules <NUM> are connected in series or in parallel or in a combination thereof to form an entirety, and are accommodated in the box body.

In some examples, as shown in <FIG>, in the battery, a plurality of battery cells <NUM> are provided. The plurality of battery cells <NUM> are first connected in series or in parallel or in a combination thereof to form battery modules <NUM>. A plurality of battery modules <NUM> are connected in series or in parallel or in a combination thereof to form an entirety, and are accommodated in the box body.

In some examples, the plurality of battery cells <NUM> in the battery module <NUM> may be electrically connected through a bus component, so as to realize parallel connection, series connection or hybrid connection of the plurality of battery cells <NUM> in the battery module <NUM>.

As shown in <FIG>, in some examples, the battery cell <NUM> includes a shell <NUM>, an electrode assembly <NUM>, an electrode terminal <NUM>, an insulating member, and an adapter member <NUM>. The shell <NUM> includes a case <NUM> and an end cap <NUM>. The case <NUM> has an opening <NUM>. The electrode assembly <NUM> is accommodated in the case <NUM>, and the electrode assembly <NUM> includes tabs <NUM>. The end cap <NUM> is configured to cover the opening <NUM>. The electrode terminal <NUM> is mounted to the end cap <NUM>. The insulating member is located on the side of the end cap <NUM> facing the electrode assembly <NUM>. The adapter member <NUM> is configured to connect the electrode terminal <NUM> and the tabs <NUM>, so that the tabs <NUM> and the electrode terminal <NUM> are electrically connected.

The case <NUM> may be in various shapes, such as a cylinder, a cuboid, or the like. The shape of the case <NUM> may be determined according to the specific shape of the electrode assembly <NUM>. For example, if the electrode assembly <NUM> has a cylinder structure, the case <NUM> may be selected as a cylinder structure. If the electrode assembly <NUM> has a cuboid structure, the case <NUM> may be selected as a cuboid structure. In <FIG>, by way of example, the case <NUM> and the electrode assembly <NUM> are both of a cuboid structure.

The case <NUM> may be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic, which is not particularly limited in the examples of the present application.

One or more electrode assemblies <NUM> may be accommodated in the case <NUM>. In <FIG>, two electrode assemblies <NUM> are accommodated in the case <NUM>.

In some examples, the electrode assembly <NUM> further includes a positive electrode sheet, a negative electrode sheet, and an isolator. The electrode assembly <NUM> may be a wound structure formed by winding the positive electrode sheet, the isolator, and the negative electrode sheet. The electrode assembly <NUM> may also be a laminated structure formed by stacking the positive electrode sheet, the isolator, and the negative electrode sheet.

The positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer. A surface of the positive electrode current collector is coated with the positive electrode active material layer. The negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer. A surface of the negative electrode current collector is coated with the negative electrode active material layer. The isolator is between the positive electrode sheet and the negative electrode sheet, and is configured to isolate the positive electrode sheet and the negative electrode sheet, so as to reduce a risk of short circuit between the positive electrode sheet and the negative electrode sheet.

The isolator may be made from PP, PE, or the like.

The tabs <NUM> in the electrode assembly <NUM> are divided into positive tabs and negative tabs. The positive tabs may be parts of the positive electrode current collector that are not coated with the positive electrode active material layer. The negative tabs may be parts of the negative electrode current collector that are not coated with the negative electrode active material layer.

In the examples of the present application, referring to <FIG> and <FIG>, the end cap <NUM> is configured to cover the opening <NUM> of the case <NUM> to form a closed space for accommodating the electrode assembly <NUM>. The closed space may also be used to accommodate electrolytes, such as an electrolyte solution. The electrode terminal <NUM> is an output member for outputting electrical energy of the battery cell <NUM>, and two electrode terminals may be provided.

The case <NUM> may include one or two openings <NUM>. If the case <NUM> includes one opening <NUM>, one end cap <NUM> may be provided. If the case <NUM> includes two openings <NUM>, two end caps <NUM> may be provided. The two end caps <NUM> cover the two openings <NUM> respectively, and the electrode terminal <NUM> may be provided on each end cap <NUM>.

In some examples, as shown in <FIG>, the case <NUM> includes one opening <NUM>, and one end cap <NUM> is provided. Two electrode terminals <NUM> may be provided in the end cap <NUM>. One electrode terminal <NUM> is electrically connected to the positive tab of the electrode assembly <NUM> through one adapter member <NUM>. The other electrode terminal <NUM> is electrically connected to the negative tab of the electrode assembly <NUM> through the other adapter member <NUM>.

In other examples, the case <NUM> is provided with two openings <NUM>. The two openings <NUM> are provided on two opposite sides of the case <NUM>, and two end caps <NUM> are provided. The two end caps <NUM> cover the two openings <NUM> of the case <NUM> respectively. In this case, each end cap <NUM> may be provided with one electrode terminal <NUM>. The electrode terminal <NUM> on one end cap <NUM> is electrically connected to one tab (positive tab) of the electrode assembly <NUM> through one adapter member <NUM>. The electrode terminal <NUM> on the other end cap <NUM> is electrically connected to the other tab (negative tab) of the electrode assembly <NUM> through the other adapter member <NUM>.

In some examples, as shown in <FIG>, the battery cell <NUM> may further include a pressure relief mechanism <NUM>. The pressure relief mechanism <NUM> is mounted on the shell <NUM>. The pressure relief mechanism <NUM> is configured to relieve pressure inside the battery cell <NUM> when internal pressure or temperature of the battery cell <NUM> reaches a threshold.

For example, the pressure relief mechanism <NUM> may be an explosion-proof valve, a rupture disc, an air valve, a pressure relief valve, a safety valve, or the like.

Referring to <FIG>, in some examples, the shell <NUM> of the example of the present application has a wall portion, the wall portion has a through hole <NUM>, and the pressure relief mechanism <NUM> covers the through hole <NUM>.

In the examples of the present application, referring to <FIG>, in order to enable the pressure relief mechanism <NUM> to blast and relieve pressure in time, according to an example of the present application, a battery cell <NUM> is provided, including: a shell <NUM>, where the shell <NUM> has a wall portion; an electrode assembly <NUM>, where the electrode assembly <NUM> is accommodated in the shell <NUM>; a pressure relief mechanism <NUM>, where the pressure relief mechanism <NUM> is provided on the wall portion, the pressure relief mechanism <NUM> includes a weak portion <NUM>, a body portion <NUM>, and a connecting portion <NUM>, the weak portion <NUM> is configured to be damaged when pressure inside the shell <NUM> reaches a threshold so as to relieve the pressure, the body portion <NUM> is located in a region defined by the weak portion <NUM>, and the connecting portion <NUM> is located on an outer side of the weak portion <NUM> and configured to connect the wall portion; the body portion <NUM> protrudes relative to the connecting portion <NUM> in a direction away from the electrode assembly <NUM>, and a first concave portion <NUM> is formed in the pressure relief mechanism <NUM> at a position corresponding to the body portion <NUM> on a side facing the electrode assembly <NUM>.

It should be noted that the electrode assembly <NUM> in the example of the present application may be a wound electrode assembly, a laminated electrode assembly, or an electrode assembly in other forms.

In some examples, the electrode assembly <NUM> is a wound electrode assembly. The positive electrode sheet, the negative electrode sheet, and the isolator all have strip-shaped structures. In an example of the present application, the positive electrode sheet, the isolator, and the negative electrode sheet may be stacked in sequence and wound for more than two turns to form the electrode assembly <NUM>.

In some examples, the electrode assembly <NUM> is a laminated electrode assembly. Specifically, the electrode assembly <NUM> includes a plurality of positive electrode sheets and a plurality of negative electrode sheets. The positive electrode sheets and the negative electrode sheets are alternately stacked, and a stacking direction is parallel to a thickness direction of the positive electrode sheets and a thickness direction of the negative electrode sheets.

In the examples of the present application, the end cap <NUM> may include a wall portion. That is, the pressure relief mechanism <NUM> may be provided on the end cap <NUM>. Alternatively, the shell <NUM> may include a wall portion. That is, the pressure relief mechanism <NUM> may be provided on the shell <NUM>. The pressure relief mechanism <NUM> in the example of the present application is provided on the wall portion. It may be understood that the shell <NUM> and the pressure relief mechanism <NUM> may have separate structures. That is, the two are manufactured separately and then assembled by mechanical connection. The shell <NUM> and the pressure relief mechanism <NUM> may also be formed into an integral structure. For example, in the present application, a predetermined region of the wall portion may be thinned to form the pressure relief mechanism <NUM>. For the sake of simplicity, the following examples are described with the end cap <NUM> as a wall portion.

The end cap <NUM> is thicker than the case <NUM>, so that the rigidity of the end cap <NUM> is greater than that of the case <NUM>. Under the same pressure, the end cap <NUM> is not prone to deformation. In the process of transportation, temperature change or charging and discharging of the battery cell <NUM>, the internal pressure of the battery cell <NUM> changes alternately between high and low. Therefore, when the pressure relief mechanism <NUM> is provided on the end cap <NUM>, the alternating stress acts on the pressure relief mechanism <NUM>, the pressure relief mechanism <NUM> is actuated to discharge high temperature and high pressure substances, and the structure of the end cap <NUM> is not easily damaged.

In the battery cell <NUM> according to the example of the present application, the weak portion <NUM> refers to a part of the pressure relief mechanism <NUM> which is weak in strength relative to the body portion <NUM> and the connecting portion <NUM> and is easy to be broken, crushed, torn or opened. The pressure relief mechanism <NUM> includes a weak portion <NUM>, a body portion <NUM> and a connecting portion <NUM>, and the weak portion <NUM> is located at a junction between the body portion <NUM> and the connecting portion <NUM>. It may be understood that a predetermined region of the pressure relief mechanism <NUM> is thinned, the thinned portion forms the weak portion <NUM>, and the two parts separated by the weak portion <NUM> and connected by the weak portion <NUM> form the main body portion <NUM> and the connecting portion <NUM>. Alternatively, material treatment is performed on the predetermined region of the pressure relief mechanism <NUM>, so that the strength of the region is weaker than that of other regions, the region with low strength forms the weak portion <NUM>, two parts that are high in strength and separated by the weak portion <NUM> and connected by the weak portion <NUM> to form the body portion <NUM> and the connecting portion <NUM>.

The connecting portion may be directly connected to the wall portion, or may be indirectly connected to the wall portion through other parts.

In some examples, the weak portion may encircle the body portion. In other examples, the weak portion may also surround the body portion at a certain angle. For example, the weak portion may surround the body portion at <NUM>° to <NUM>°.

When the preset pressure value of the battery cell <NUM> is small, the requirement on the strength of the weak portion <NUM> is correspondingly low. However, in order to ensure the dimensional accuracy of the weak portion <NUM>, there is a need to maintain the weak portion <NUM> with a certain strength. In the process of transportation, temperature change or charging and discharging of the battery cell <NUM>, the internal pressure of the battery cell <NUM> changes alternately between high and low, which may cause the pressure relief mechanism <NUM> to deform by bulging away from the electrode assembly <NUM> or recessing close to the electrode assembly <NUM>. When the pressure relief mechanism <NUM> deforms alternately between bulging and recessing, the weak portion <NUM> connected to the body portion <NUM> and the connecting portion <NUM> may bear the alternating stress. In order to prevent the breakage of the weak portion <NUM> under the action of the alternating stress, there is a need to maintain the weak portion <NUM> with a certain strength. However, since the weak portion <NUM> has a certain strength, when the internal pressure of the battery cell <NUM> exceeds the preset pressure value, the weak portion <NUM> may not break in time. If the internal pressure of the battery cell <NUM> is excessively high, the gas inside the battery cell <NUM> cannot be discharged in time, which may cause the battery cell <NUM> to expand or even explode.

In the battery cell <NUM> according to the example of the present application, the body portion <NUM> protrudes relative to the connecting portion <NUM> in a direction away from the electrode assembly <NUM>, a sudden change in a cross section occurs at the weak portion <NUM>, stress concentration occurs in the weak portion <NUM>, and the first concave portion <NUM> is formed in the pressure relief mechanism <NUM> at a position corresponding to the body portion <NUM> on a side facing the electrode assembly <NUM>, which further aggravates the stress concentration of the weak portion <NUM>, making the weak portion <NUM> easy to break and capable of releasing pressure when the pressure in the shell <NUM> reaches a threshold, and ensures the safety of the battery cell <NUM> in the case of thermal runaway thereby improving stability and safety of use of the battery cell <NUM>.

In some examples, the battery cell <NUM> also includes a protective sheet <NUM>. The protective sheet <NUM> is attached to an outer surface of the wall portion of the shell <NUM> and covers the pressure relief mechanism <NUM>.

The protective sheet <NUM> can protect the pressure relief mechanism <NUM>, and reduce distortion or dent formation of the pressure relief mechanism <NUM> caused by an accidental impact or scratch of an external object on the pressure relief mechanism <NUM>, thereby affecting the possibility of normal fracture and blasting of the weak portion <NUM> of the pressure relief mechanism <NUM>.

In some examples, the protective sheet <NUM> is located on an upper side of the end cap and covers the through hole <NUM>. The material of the protective sheet <NUM> may be plastics such as PE or PP.

In the battery cell <NUM> according to the example of the present application, the weak portion <NUM> may be in a shape such as a curved structure or a ring structure. When the weak portion <NUM> is of the curved structure or the ring structure, the body portion <NUM> is located in a region defined by the weak portion <NUM>, and the connecting portion <NUM> is located on an outer side of the weak portion <NUM>. The connecting portion <NUM> is configured to connect the wall portion of the shell <NUM>.

In some examples, the weak portion <NUM> may reduce the local strength of the pressure relief mechanism <NUM> by forming a notch, groove or other structures on the pressure relief mechanism <NUM>.

In some examples, referring to <FIG>, the weak portion <NUM> is formed by providing a groove 83c on the pressure relief mechanism <NUM>. The connecting portion <NUM> has a first outer surface 82a and a first inner surface 82b along a thickness direction X of the pressure relief mechanism <NUM>. The first inner surface 82b faces the electrode assembly <NUM>.

For example, the material may be removed from the pressure relief mechanism <NUM> by machining to form the groove 83c, which is beneficial to reduce the machining cost and the machining difficulty. Along the thickness direction X, the weak portion <NUM> and the groove 83c are arranged correspondingly.

In some examples, referring to <FIG>, the groove 83c on the pressure relief mechanism <NUM> is curved, and the weak portion <NUM> corresponding to the groove 83c is of a curved structure. The groove 83c on the pressure relief mechanism <NUM> is strip-shaped, and the weak portion <NUM> corresponding to the groove 83c is of a strip-shaped structure.

When the internal pressure of the battery cell <NUM> changes alternately between high and low, the weak portion <NUM> is prone to fatigue aging or fracture. The body portion <NUM> flips after the fracture of the weak portion <NUM>, thereby relieving the pressure of the battery cell <NUM>.

In some examples, referring to <FIG>, the groove 83c on the pressure relief mechanism <NUM> is ring-shaped. The weak portion <NUM> corresponding to the groove 83c is also ring-shaped. The body portion <NUM> is located in the region defined by the weak portion <NUM>. The connecting portion <NUM> is configured to connect the wall portion.

In some examples, a region defined by the groove 83c may be in a shape of a racetrack, a circle, a rectangle, or an oval. When the internal pressure of the battery cell <NUM> changes alternately between high and low, the weak portion <NUM> is prone to fatigue aging or fracture. After the fracture of the weak portion <NUM>, the through hole <NUM> in the wall portion is exposed, the battery cell <NUM> communicates with the external environment, and the battery cell <NUM> can quickly relieve the pressure.

In some examples, the groove 83c is recessed along the thickness direction X.

In some examples, referring to <FIG> and <FIG>, the groove 83c is recessed relative to the first outer surface 82a in a direction toward the electrode assembly <NUM>.

In some other examples, referring to <FIG>, the groove 83c is recessed relative to the first inner surface 82b in a direction away from the electrode assembly <NUM>.

In some other examples, referring to <FIG>, two grooves 83c are provided, one groove 83c is recessed relative to the first inner surface 82b in a direction away from the electrode assembly <NUM>, and the other groove 83c is recessed relative to the first outer surface 82a in a direction toward the electrode assembly <NUM>.

In some examples, referring to <FIG>, a thickness of the body portion <NUM> and a thickness of the connecting portion <NUM> are both greater than a thickness of the weak portion <NUM>. The strength of the weak portion <NUM> is smaller than that of the body portion <NUM> and the connecting portion <NUM>, and can be more easily damaged so that the pressure of the battery cell <NUM> can be relieved in time when the battery cell is subjected to thermal runaway.

In some examples, the thickness of the connecting portion <NUM> is B1, and the thickness of the weak portion <NUM> is W1, where <NUM>≤W1B1≤<NUM>. When the thicknesses of the weak portion <NUM> and the connecting portion <NUM> are within the above numerical range, machining accuracy of the weak portion <NUM> can be improved, thereby improving uniformity of the thickness of the weak portion <NUM>. When the weak portion <NUM> is subjected to alternating stress, degrees of damages to the weak portion <NUM> is relatively uniform, so that blasting consistency of the battery can be improved.

When W1/B1 < <NUM>, the thickness of the weak portion <NUM> is relatively thin, and the strength of the weak portion <NUM> is low. When the battery cell <NUM> does not undergo thermal runaway, the weak portion <NUM> is easily damaged. Moreover, when the weak portion <NUM> with the thickness is formed, a dimension of the weak portion <NUM> fluctuates greatly, and the thickness thereof has poor uniformity. When weak portions <NUM> of different battery cells <NUM> are subjected to alternating stress, regions or degrees of fatigue aging may be different, resulting in poor consistency of blasting pressure relief of different battery cells <NUM>.

When W1/B <NUM>><NUM>, the thickness of the weak portion <NUM> is relatively thick, and the strength of the weak portion <NUM> is high. When a preset pressure value of the battery cell <NUM> is small, the weak portion <NUM> is not easily damaged. When the battery cell <NUM> is subjected to thermal runaway, gas inside the battery cell <NUM> cannot be discharged in time, and the battery cell <NUM> is prone to expansion or even explosion.

In the battery cell <NUM> according to the example of the present application, referring to <FIG>, the first concave portion <NUM> is recessed relative to the first inner surface 82b in a direction away from the electrode assembly <NUM>. Stress concentration is formed at the weak portion <NUM>, and the weak portion <NUM> is easily damaged, so that the pressure of the battery cell <NUM> can be relieved in time.

In some examples, projections of the groove 83c and the first concave portion <NUM> in a first direction Y at least partially overlap, and the first direction Y is perpendicular to a thickness direction X of the pressure relief mechanism <NUM>. The groove 83c and the weak portion <NUM> are arranged correspondingly in the thickness direction X, and the projections of the groove 83c and the first concave portion <NUM> in the first direction Y at least partially overlap, which may aggravate the stress concentration of the weak portion <NUM>, the weak portion <NUM> can be more easily damaged so that the pressure of the battery cell <NUM> can be relieved in time.

In some examples, referring to <FIG>, the first concave portion <NUM> is recessed relative to the first inner surface 82b in a direction away from the electrode assembly <NUM>, and at least a part of the body portion <NUM> protrudes from the first outer surface 82a. At least a part of the body portion <NUM> protrudes from the first outer surface 82a, a stepped structure is formed between the body portion <NUM> and the connecting portion <NUM>, and the stress at a junction between the body portion <NUM> and the connecting portion <NUM> may be significantly increased. However, the weak portion <NUM> is located at a junction between the body portion <NUM> and the connecting portion <NUM>, so the stress concentration at the weak portion <NUM> may be aggravated.

In some examples, referring to <FIG>, in the thickness direction X of the pressure relief mechanism <NUM>, the thickness of the connecting portion <NUM> is B1, and a height of the body portion <NUM> is H, where H/B1≤ <NUM>. When the thicknesses of the connecting portion <NUM> and the body portion <NUM> are within the above numerical range, the body portion <NUM> has a moderate height and is easily machined, which can prevent interference between the body portion <NUM> and a foreign matter outside the battery cell <NUM> in a case where the stress concentration in the weak portion <NUM> is aggravated.

When H/B1><NUM>, the body portion <NUM> is excessively high and is not easily machined. Moreover, the excessively high body portion <NUM> may protrude from a surface of the battery cell <NUM> to interfere with a foreign matter outside the battery cell <NUM>.

In some examples, referring to <FIG>, the first concave portion <NUM> has a bottom wall <NUM>, the first concave portion <NUM> is recessed from the first inner surface 82b to the bottom wall <NUM> in a direction away from the electrode assembly <NUM>, and the bottom wall <NUM> does not extend beyond the first outer surface 82a in a direction away from the electrode assembly <NUM>. Along the thickness direction X, as a distance between the bottom wall <NUM> and the first outer surface 82a decreases, the first concave portion <NUM> is recessed deeper in the thickness direction X, stress concentration is more easily formed at a junction between the body portion <NUM> corresponding to the position of the first concave portion <NUM> and the weak portion <NUM>, and the weak portion <NUM> can be more easily damaged.

In some examples, the pressure relief mechanism <NUM> according to the example of the present application further includes a transition portion <NUM>. As shown in <FIG>, the transition portion <NUM> is provided around the connecting portion <NUM> and configured to connect the wall portion and the connecting portion <NUM>, and a thickness of the transition portion <NUM> is greater than that of the connecting portion <NUM>. The thickness of the transition portion <NUM> is relatively thicker, which can improve welding strength of the transition portion <NUM>, and prevent distortion or burn-through during welding caused by a small thickness of the transition portion <NUM>. In addition, the thickness of the connecting portion <NUM> is relatively thinner, so that the pressure relief mechanism <NUM> is easily broken when subjected to alternating stress, and the pressure can be relieved in time.

In some examples, the thickness of the connecting portion <NUM> is B1, and the thickness of the transition portion <NUM> is B2, where B1/B2≤<NUM>/<NUM>. When the thicknesses of the connecting portion <NUM> and the transition portion <NUM> are within this numerical range, the thicknesses of the connecting portion <NUM> and the transition portion <NUM> are moderate, which can satisfy both welding strength of the transition portion <NUM> and a strength requirement of the connecting portion <NUM>.

It should be noted that the transition portion <NUM> has a second outer surface 85a and a second inner surface 85b along the thickness direction X of the pressure relief mechanism <NUM>, and the second inner surface 85b faces the electrode assembly <NUM>.

In some examples, the second outer surface 85a protrudes beyond the first outer surface 82a in a direction away from the electrode assembly <NUM>.

In some examples, the second inner surface 85b protrudes beyond the first inner surface 82b in a direction close to the electrode assembly <NUM>.

In some examples, the second outer surface 85a protrudes from the first outer surface 82a in a direction away from the electrode assembly <NUM>; and the second inner surface 85b protrudes from the first inner surface 82b in a direction close to the electrode assembly <NUM>.

As an example, the thickness of the connecting portion <NUM> is B1, and the thickness of the transition portion <NUM> is B2, where B1/B2≤<NUM>/<NUM>. When the thicknesses of the connecting portion <NUM> and the transition portion <NUM> are within this numerical range, the thicknesses of the connecting portion <NUM> and the transition portion <NUM> are moderate, which can satisfy both welding strength of the transition portion <NUM> and the tearing strength of the connecting portion <NUM>.

In some examples, the transition portion <NUM> and the connecting portion <NUM> are smoothly connected in a transitional manner, which prevents fracture at a junction between the transition portion <NUM> and the connecting portion <NUM> during the mounting.

In some examples, referring to <FIG>, along the thickness direction X, the body portion <NUM> protrudes relative to the transition portion <NUM> in a direction away from the electrode assembly <NUM>. Moreover, the thickness of the transition portion <NUM> is greater than that of the connecting portion <NUM>. A stepped structure is formed among the body portion <NUM>, the weak portion <NUM>, the connecting portion <NUM>, and the transition portion <NUM>, and the weak portion <NUM> and the connecting portion <NUM> are prone to stress concentration. In particular, the stress concentration of the weak portion <NUM> may be aggravated, the weak portion <NUM> is easily damaged, and the pressure of the battery cell <NUM> can be relieved in time.

A minimum dimension of the connecting portion <NUM> in the example of the present application along the first direction Y is greater than <NUM>. The weak portion <NUM> is closer to a central position of the pressure relief mechanism <NUM>, the weak portion <NUM> is subjected to more uniform alternating stress, and the consistency of the fracture of the weak portion <NUM> is higher.

Referring to <FIG>, according to an example of the present application, a manufacturing method for a battery cell <NUM> is further provided, which includes:.

In the battery cell <NUM> manufactured with the manufacturing method for the battery cell <NUM> according to the example of the present application, the body portion <NUM> of the pressure relief mechanism <NUM> protrudes relative to the connecting portion <NUM> in a direction away from the electrode assembly <NUM>, stress concentration occurs in the weak portion <NUM>, and the first concave portion <NUM> is formed in the pressure relief mechanism <NUM> at a position corresponding to the body portion <NUM> on a side facing the electrode assembly <NUM>, so as to aggravate the stress concentration of the weak portion <NUM> and reduce the strength of the weak portion <NUM>, making the weak portion <NUM> easy to break and capable of releasing pressure when the pressure in the shell <NUM> reaches a threshold, which ensures the safety of the battery cell <NUM> in the case of thermal runaway and thereby improves stability and safety of use of the battery.

The battery cell <NUM> in the above example can be manufactured with the manufacturing method for the battery cell <NUM> according to the example of the present application.

Referring to <FIG>, according to an example of the present application, a manufacturing system <NUM> for a battery cell <NUM> is further provided, including:.

The manufacturing system for the battery cell <NUM> according to the example of the present application can perform the manufacturing method for the battery cell <NUM> in the above example.

Claim 1:
A battery cell (<NUM>), comprising:
a shell (<NUM>), wherein the shell (<NUM>) has a wall portion;
an electrode assembly (<NUM>), wherein the electrode assembly (<NUM>) is accommodated in the shell (<NUM>); and
a pressure relief mechanism (<NUM>), wherein the pressure relief mechanism (<NUM>) is provided on the wall portion, the pressure relief mechanism (<NUM>) comprises a weak portion (<NUM>), a body portion (<NUM>), and a connecting portion (<NUM>), the weak portion (<NUM>) is configured to be damaged when pressure inside the shell (<NUM>) reaches a threshold so as to relieve the pressure, the body portion (<NUM>) is located in a region defined by the weak portion (<NUM>), and the connecting portion (<NUM>) is located on an outer side of the weak portion (<NUM>) and configured to connect the wall portion;
wherein the body portion (<NUM>) protrudes relative to the connecting portion (<NUM>) in a direction away from the electrode assembly (<NUM>), and a first concave portion (<NUM>) is formed in the pressure relief mechanism (<NUM>) at a position corresponding to the body portion (<NUM>) on a side facing the electrode assembly (<NUM>).