Battery cell, battery and electric device

Abstract

Disclosed in the present application are a battery cell, a battery and an electric device. The battery cell comprises: a case, the case comprising a first wall portion, a second wall portion and a third wall portion; a pressure relief mechanism, the pressure relief mechanism being arranged at the first wall portion; and an electrode assembly, which is accommodated in the case, wherein the electrode assembly comprises at least one negative electrode sheet, an active material layer is formed on at least one side of the negative electrode sheet, and in a second direction, the first wall portion is arranged facing an edge of the negative electrode sheet; in the second direction, the minimum distance between the pressure relief mechanism and an edge of the active material layer is D, and 3 mm≤D≤15 mm; on the basis of the total mass of the active material layer, the mass proportion of an active material is S, and 0.5%≤S≤25%; and in a first direction, the minimum distance between an edge of the pressure relief mechanism and an outer surface of the second wall portion or an outer surface of the third wall portion is d, and 3 mm≤d≤20 mm.

Description

Battery cells, batteries, and electrical equipment Technical Field

[0001] The present application relates to the field of batteries, and in particular to battery cells, batteries, and electrical equipment. Background Art

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry. Electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of the sustainable development of the automotive industry. For electric vehicles, battery technology is a key factor in their development.

[0003] In order to ensure the safety performance of battery cells, a pressure relief mechanism is usually provided on the battery cells. The pressure relief mechanism is used to release the pressure inside the battery cells when the battery cells reach predetermined conditions. During the charging and discharging process of the battery cells, the electrode assembly will expand and deform, causing the outer shell containing the electrode assembly to swell and deform. The outer shell pulls on the pressure relief mechanism, causing the pressure relief mechanism to be easily damaged, thereby reducing the reliability of the battery cells.

[0004] Summary of the Invention

[0005] In view of the technical problems existing in the background technology, the present application provides a battery cell, which can reduce the pulling of the battery cell shell on the pressure relief mechanism and reduce the probability of cracking of the pressure relief mechanism.

[0006] A first aspect of the present application provides a battery cell, comprising a shell, comprising a first wall portion, a second wall portion, and a third wall portion, wherein the second wall portion and the third wall portion are arranged opposite to each other along a first direction, and the first wall portion is connected to the second wall portion and the third wall portion at both ends along the first direction; a pressure relief mechanism, wherein the pressure relief mechanism is arranged on the first wall portion, and the pressure relief mechanism is configured to release the pressure inside the battery cell; an electrode assembly, housed in the shell, wherein the electrode assembly includes at least one negative electrode sheet, and an active material layer is formed on at least one side of the negative electrode sheet, and the active material layer includes active material, along the second direction, the first wall portion is arranged facing the edge of the negative electrode sheet, and the second direction is the thickness direction of the first wall portion and is perpendicular to the first direction; wherein, along the second direction, the minimum distance between the pressure relief mechanism and the edge of the active material layer is D, 3mm≤D≤15mm; based on the total mass of the active material layer, the mass proportion of the active material is S, 0.5%≤S≤25%; along the first direction, the minimum distance between the edge of the pressure relief mechanism and the outer surface of the second wall portion or the outer surface of the third wall portion is d, 3mm≤d≤20mm.

[0007] In the battery cell proposed in this application, the values ​​of D, S, and d can be adjusted relative to each other. Specifically, the minimum distance D between the pressure relief mechanism and the edge of the active material layer, and the minimum distance d between the edge of the pressure relief mechanism and the outer surface of the second wall or the outer surface of the third wall, can be adjusted based on the mass fraction S of the active material on the negative electrode active material layer. Alternatively, the minimum distance S between the edge of the pressure relief mechanism and the outer surface of the second wall or the outer surface of the third wall can be adjusted based on the minimum distance D between the pressure relief mechanism and the edge of the active material layer. Alternatively, the minimum distance d between the edge of the pressure relief mechanism and the outer surface of the second wall or the outer surface of the third wall can be adjusted based on the minimum distance d between the pressure relief mechanism and the edge of the active material layer. This improves battery energy density while reducing the pull on the first wall due to deformation of the electrode assembly and the pull and deformation of the second wall or the third wall due to expansion of the electrode assembly. This reduces the probability of damage to the pressure relief mechanism due to pull, reduces the probability of leakage from the pressure relief mechanism, and improves the reliability of the battery cell.

[0008] According to some embodiments of the present application, 3mm≤D≤10mm, and 5%≤S≤15%. This improves the battery's energy density while reducing expansion and deformation of the electrode assembly, reducing the pull on the first wall caused by deformation of the electrode assembly, and reducing the probability of damage to the pressure relief mechanism due to pulling, thereby reducing the probability of leakage from the pressure relief mechanism and improving the reliability of the battery cell.

[0009] According to some embodiments of the present application, D / S is greater than 20 mm. Thus, S can be adjusted according to D, or vice versa, thereby increasing the battery energy density while reducing expansion and deformation of the electrode assembly, reducing the pulling on the first wall due to deformation of the electrode assembly, reducing the probability of damage to the pressure relief mechanism due to pulling, and reducing the probability of leakage from the pressure relief mechanism, thereby improving the reliability of the battery cell.

[0010] According to some embodiments of the present application, 2mm≤D≤10mm, and 5mm≤d≤15mm. This reduces the pulling of the first wall due to expansion and deformation of the electrode assembly, reduces the pulling of the second or third wall on the first wall, reduces the probability of damage to the pressure relief mechanism due to pulling, reduces the probability of leakage at the pressure relief mechanism, and improves the reliability of the battery cell.

[0011] According to some embodiments of the present application, 10 mm 2 ≤D×d≤150mm 2 Thus, d can be adjusted according to D, or D can be adjusted according to d, thereby reducing the pulling of the first wall due to the expansion and deformation of the electrode assembly, reducing the pulling of the second wall or the third wall on the first wall, reducing the probability of the pressure relief mechanism being pulled and damaged, reducing the probability of leakage at the pressure relief mechanism, and improving the reliability of the battery cell.

[0012] According to some embodiments of the present application, the active material includes an expandable element, and the expandable element includes at least one of silicon or graphite, thereby improving the energy density of the battery.

[0013] According to some embodiments of the present application, the pressure relief mechanism is integrally formed with the first wall portion. Thus, by integrally forming the pressure relief mechanism with the first wall portion, the reliability of the pressure relief mechanism can be improved, the connection process between the pressure relief mechanism and the first wall portion can be eliminated, and the production cost of the battery cell can be reduced.

[0014] According to some embodiments of the present application, the first wall portion includes a weak area and a non-weak area. The weak area is arranged along the edge of the pressure relief mechanism and connects the pressure relief mechanism and the non-weak area. The weak area is configured to rupture when the battery cell releases pressure. Thus, when the battery cell releases pressure, the first wall portion can rupture in the weak area, and the pressure relief mechanism can open with the weak area as the boundary, with a larger pressure relief area, so that the discharge medium inside the housing can be quickly discharged.

[0015] According to some embodiments of the present application, the first wall portion is provided with a notch, and the first wall portion forms the weakened area in the region where the notch is provided. Thus, by providing the notch on the first wall portion to form the weakened area, an integrated pressure relief mechanism is formed, which has a simple molding method and low production cost.

[0016] According to some embodiments of the present application, the scored groove is a groove extending along a closed trajectory. Thus, during the pressure relief process, after the first wall portion ruptures along the scored groove, the pressure relief mechanism can open in a manner that separates from the non-weakened area, thereby increasing the pressure relief area and improving the pressure relief rate of the battery cell.

[0017] According to some embodiments of the present application, the pressure relief mechanism is separately provided from the first wall portion, and the first wall portion is provided with a through hole, and the pressure relief mechanism is mounted in the through hole. Thus, the pressure relief mechanism is a component independent of the housing, and the pressure relief mechanism and the housing can be manufactured separately and then assembled, which reduces production difficulty and improves efficiency.

[0018] According to some embodiments of the present application, along the first direction, the thickness of the battery cell is W1, the width of the pressure relief mechanism is W2, and the following relationship is satisfied: 0.2≤W2 / W1≤0.5. This reduces the pulling of the housing on the pressure relief mechanism and improves the energy density of the battery.

[0019] According to some embodiments of the present application, the width of the pressure relief mechanism along the first direction is W2; along the third direction, the length of the pressure relief mechanism is W3, and the following conditions are satisfied: 0.5≤W2 / W3≤0.8; the third direction is perpendicular to the second direction. This increases the pressure relief area and improves the pressure relief rate of the battery cell.

[0020] According to some embodiments of the present application, the housing further includes a fourth wall portion, wherein the first wall portion, the second wall portion, the fourth wall portion, and the third wall portion are sequentially connected end to end, and the fourth wall portion and the first wall portion are arranged opposite each other along the second direction. Thus, the housing including the first wall portion, the second wall portion, the third wall portion, and the fourth wall portion is generally in the shape of a quadrangular prism, which has a simple structure and is easy to form.

[0021] According to some embodiments of the present application, along the second direction, the distance between the first wall and the fourth wall is L1; along the first direction, the distance between the second wall and the third wall is L2, and L1>L2. Thus, when the electrode assembly expands, the first and fourth walls are less affected by the electrode assembly than the second and third walls. Because the pressure relief mechanism is located on the first wall, the risk of the pressure relief mechanism being blocked or damaged by the electrode assembly expansion is reduced.

[0022] According to some embodiments of the present application, the electrode assembly further includes at least one positive electrode sheet, the polarity of the positive electrode sheet is opposite to that of the negative electrode sheet, and the positive electrode sheet and the negative electrode sheet are stacked.

[0023] According to some embodiments of the present application, the electrode assembly further includes at least one positive electrode sheet, the polarity of the positive electrode sheet is opposite to that of the negative electrode sheet, and the positive electrode sheet and the negative electrode sheet are wound together.

[0024] According to some embodiments of the present application, the housing includes a shell and an end cap, wherein at least one side of the shell has an opening, the end cap is connected to the shell and is used to close the opening, and the first wall portion is formed on the shell. Thus, by arranging the pressure relief mechanism on the shell, the structure of the end cap can be simplified, while also facilitating a reduction in the distance between the pressure relief mechanism and the electrode assembly. This, in turn, shortens the path for the discharge medium to flow to the pressure relief mechanism during pressure relief, shortening the time it takes for the discharge medium to reach the pressure relief mechanism, thereby improving the timeliness of pressure relief in the battery cell and effectively enhancing the reliability of the battery cell.

[0025] According to some embodiments of the present application, the housing has openings on opposite sides, and the two end caps are used to close the openings on the corresponding sides. Thus, by providing two openings on the housing, the manufacturing and forming of the housing can be facilitated, while also facilitating the extraction of the tabs from both ends of the electrode assembly, thereby facilitating the separation of the two electrical connections and reducing the risk of short circuits in the battery cells.

[0026] According to some embodiments of the present application, the end cap is provided with an electrical connection portion, and the electrical connection portion is electrically connected to the positive electrode plate, or the electrical connection portion is electrically connected to the negative electrode plate, thereby inputting or outputting electrical energy of the battery cell.

[0027] According to some embodiments of the present application, the first wall portion is used to support the electrode assembly and is located below the electrode assembly. Thus, a pressure relief mechanism can be provided at the bottom of the battery cell, and an exhaust channel can be provided at the bottom of the battery cell. The exhaust channel can be connected to the pressure relief mechanism to discharge high-temperature and high-pressure flue gas through the pressure relief mechanism at the bottom into the exhaust channel and then to the outside world when thermal runaway of the battery cell occurs.

[0028] According to some embodiments of the present application, the housing is made of at least one of aluminum, nickel-plated carbon steel, stainless steel, magnesium alloy, nickel alloy, copper alloy, and zirconium alloy. The use of these materials can improve the housing's tensile strength, thereby reducing deformation of the housing during electrode assembly expansion, lowering the probability of the housing or pressure relief mechanism being torn and broken, reducing the risk of leakage, and improving the reliability of the battery cells.

[0029] According to some embodiments of the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material region disposed on the surface of the positive electrode current collector. The positive electrode current collector is composed of a material comprising aluminum at a mass percentage of greater than or equal to 50%. Thus, by using this positive electrode current collector, the manufacturing difficulty and cost of the positive electrode sheet can be reduced compared to composite current collectors in related technologies.

[0030] A second aspect of the present application provides a battery, comprising the battery cell provided in the first aspect of the present application.

[0031] A third aspect of the present application provides an electrical device, comprising the battery provided in the second aspect of the present application.

[0032] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0034] FIG1 is a schematic diagram of a battery cell provided in some embodiments of the present application;

[0035] FIG2 is an exploded view of a battery cell provided in some embodiments of the present application;

[0036] FIG3 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0037] FIG4 is a schematic diagram of a first wall portion provided in some embodiments of the present application;

[0038] FIG5 is a cross-sectional view along line AA in FIG4 provided in some embodiments;

[0039] FIG6 is a schematic diagram of a pressure relief mechanism provided in some embodiments of the present application;

[0040] FIG7 is a schematic diagram of a pressure relief mechanism provided in some other embodiments of the present application;

[0041] FIG8 is a schematic diagram of a pressure relief mechanism provided in some other embodiments of the present application;

[0042] FIG9 is a schematic diagram of an electrode assembly provided in some embodiments of the present application;

[0043] FIG10 is a schematic diagram of electrode assemblies provided in some other embodiments of the present application;

[0044] FIG11 is a schematic diagram of a battery cell provided in some other embodiments of the present application;

[0045] FIG12 is a schematic diagram of a fifth wall portion of a battery cell provided by some embodiments of the present application;

[0046] FIG13 is a schematic diagram of a battery in the related art;

[0047] FIG14 is a schematic diagram of an electrical device in the related art.

[0048] Explanation of the accompanying drawings: Battery 1000, Vehicle 2000, Box 200, First Part 210, Second Part 220, Battery Cell 100, Outer Shell 10, Shell 101, End Cover 102, First Wall 11, Weakened Area 111, Non-Weakened Area 112, Second Wall 12, Third Wall 13, Fourth Wall 14, Fifth Wall 15, Sixth Wall 16, Electrode Assembly 20, Positive Pole Sheet 21, Negative Pole Sheet 22, Electrical Connection 30, Pressure Relief Mechanism 40, Predetermined Pressure Relief Area 401, Notched Groove 41, First Arc Segment 411, First Straight Line Segment 412, Second Straight Line Segment 413, Third Straight Line Segment 414, Arc Segment 415, Fourth Straight Line Segment 416, Fifth Straight Line Segment 417, Sixth Straight Line Segment 418, Seventh Straight Line Segment 419 (Flip Notch 419), Patch 60, A first direction F1, a second direction F2, and a third direction F3. DETAILED DESCRIPTION

[0049] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0050] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0051] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0052] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0053] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0054] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0055] The development of battery technology requires simultaneous consideration of multiple design factors, including performance parameters such as energy density, cycle life, discharge capacity, and charge / discharge rate. To ensure the lifespan of a battery cell, a pressure relief mechanism can be installed on the outer shell of the cell. In the event of thermal runaway, this mechanism releases internal pressure, improving the reliability of the cell.

[0056] During the charge and discharge process of a battery cell, the electrode assembly will expand, causing the outer shell to bulge and deform. The pressure relief mechanism is located on the outer shell, especially some pressure relief mechanisms are located on the wall closer to the electrode assembly. The expansion of the electrode assembly will deform the wall where the pressure relief mechanism is located, thereby pulling on the notch of the pressure relief mechanism, causing the pressure relief mechanism to break at the notch and then leak. As a result, the pressure relief mechanism will be damaged when the pressure inside the battery cell does not reach the detonation pressure of the pressure relief mechanism, causing the pressure relief mechanism to fail and the reliability of the pressure relief mechanism to be low. The expansion of the electrode assembly is mainly related to the expansion of the negative electrode plate, and the expansion of the negative electrode plate is mainly related to the content of active material on the negative electrode plate. The higher the active material content, the greater the expansion force of the negative electrode plate during charge and discharge, the greater the deformation of the outer shell, and the greater the tendency to pull on the pressure relief mechanism, causing the pressure relief mechanism to crack. The pull on the pressure relief mechanism caused by casing deformation is also related to the distance between the negative electrode and the wall where the pressure relief mechanism is located. The smaller the distance, the greater the pull on the pressure relief mechanism when the casing deforms, and the more likely it is to crack. The force exerted by the electrode assembly after expansion is primarily concentrated on the large surface of the casing. The smaller the distance between the edge of the pressure relief mechanism and the large surface of the casing in the thickness direction of the battery cell, the more likely the casing deformation will pull on the pressure relief mechanism, causing it to crack.

[0057] In view of this, the present application proposes a battery cell, comprising a shell and an electrode assembly, the electrode assembly comprising at least one negative electrode sheet, an active material layer being provided on the negative electrode sheet, the shell comprising a first wall portion, a second wall portion and a third wall portion, and a pressure relief mechanism being provided on the first wall portion, wherein, along the second direction, the minimum distance between the pressure relief mechanism and the edge of the active material layer is D, 3mm≤D≤15mm, thereby reducing the pulling force on the first wall portion when the electrode assembly expands, and reducing the probability of the pressure relief mechanism being pulled and damaged; based on the total mass of the active material layer, the mass proportion of the active material is S, 0.5%≤S≤25%, thereby reducing the expansion deformation of the electrode assembly; along the first direction, the minimum distance between the edge of the pressure relief mechanism and the outer surface of the second wall portion or the outer surface of the third wall portion is d, 3mm≤d≤20mm, thereby reducing the pulling force of the second wall portion or the third wall portion on the first wall portion, reducing the probability of the pressure relief mechanism being pulled and damaged, reducing the probability of leakage at the pressure relief mechanism, and improving the reliability of the battery cell.

[0058] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0059] Electrical equipment can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and electric tools, etc. Vehicles can be fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical equipment.

[0060] 1 to 3 , a first aspect of the present application provides a battery cell 100, comprising: a housing 10, wherein the housing 10 comprises a first wall portion 11, a second wall portion 12, and a third wall portion 13, wherein the second wall portion 12 and the third wall portion 13 are arranged opposite to each other along a first direction F1, and the first wall portion 11 is connected to the second wall portion 12 and the third wall portion 13 at both ends along the first direction F1; a pressure relief mechanism 40, wherein the pressure relief mechanism 40 is provided on the first wall portion 11, and the pressure relief mechanism 40 is configured to release the pressure inside the battery cell 100; an electrode assembly 20, housed in the housing 10, wherein the electrode assembly 20 comprises at least one negative electrode sheet 22, wherein the negative electrode sheet 22 is provided on the first wall portion 11; and 2, an active material layer is formed on at least one side of the negative electrode 2, and the active material layer includes an active material. Along the second direction F2, the first wall portion 11 is arranged to face the edge of the negative electrode sheet 22, and the second direction F2 is the thickness direction of the first wall portion 11 and is perpendicular to the first direction F1; wherein, along the second direction F2, the minimum distance between the pressure relief mechanism 40 and the edge of the active material layer is D, 3mm≤D≤15mm; based on the total mass of the active material layer, the mass proportion of the active material is S, 0.5%≤S≤25%; along the first direction F1, the minimum distance between the edge of the pressure relief mechanism 40 and the outer surface of the second wall portion 12 or the outer surface of the third wall portion 13 is d, 3mm≤d≤20mm.

[0061] In the battery cell 100 proposed in this application, the values ​​of D, S, and d can be adjusted according to each other.

[0062] As an example, S and d can be adjusted according to the minimum distance D between the pressure relief mechanism 40 and the edge of the active material layer: when the pressure relief mechanism 40 is far away from the edge of the active material layer, the mass proportion S of the active material in the active material layer can be increased, and then the minimum distance d between the edge of the pressure relief mechanism 40 and the outer surface of the second wall portion 12 or the outer surface of the third wall portion 13 can be adjusted according to S.

[0063] As an example, D and d can be adjusted according to the mass proportion S of the active material in the active material layer. When the mass proportion of the active material in the active material layer is large, the minimum distance D between the edge of the pressure relief mechanism and the edge of the active material layer can be increased, and then the minimum distance d between the edge of the pressure relief mechanism 40 and the outer surface of the second wall portion 12 or the outer surface of the third wall portion 13 can be adjusted according to D.

[0064] As an example, D and S can be adjusted according to the minimum distance d between the edge of the pressure relief mechanism 40 and the outer surface of the second wall portion 12 or the outer surface of the third wall portion 13: when the minimum distance d between the edge of the pressure relief mechanism 40 and the outer surface of the second wall portion 12 or the outer surface of the third wall portion 13 is large, the minimum distance D between the pressure relief mechanism 40 and the edge of the active material layer can be reduced, and then the mass proportion S of the active material in the active material layer can be adjusted according to D.

[0065] Thus, while improving the battery energy density, the pulling force on the first wall portion 11 due to the deformation of the electrode assembly 20 is reduced, and the pulling force and deformation of the second wall portion 12 or the third wall portion 13 due to the expansion of the electrode assembly 20 are reduced, thereby reducing the probability of the pressure relief mechanism 40 being pulled and damaged, reducing the probability of leakage at the pressure relief mechanism 40, and improving the reliability of the battery cell 100.

[0066] In the present application, the minimum distance d means: the distances between different positions of the edge of the pressure relief mechanism 40 and different positions of the outer surface of the second wall portion 12 are different, and the minimum distance among all distances is d1; the distances between different positions of the edge of the pressure relief mechanism 40 and different positions of the outer surface of the third wall portion 13 are different, and the minimum distance among all distances is d2. The minimum value of d1 and d2 is d in this application.

[0067] According to some embodiments of the present application, 3mm≤D≤15mm. For example, it can be 3mm, 5mm, 7mm, 9mm, 11mm, 13mm or 15mm, or it can be a range consisting of any of the above values. According to some specific embodiments of the present application, 3mm≤D≤10mm. As a result, the pulling of the first wall portion 11 by the electrode assembly 20 during expansion and deformation is reduced, thereby reducing the probability of the pressure relief mechanism 40 being pulled and damaged, reducing the probability of leakage at the pressure relief mechanism 40, and improving the reliability of the battery cell 100.

[0068] In the present application, when an active material layer is provided on each negative electrode sheet, the minimum distance D between the pressure relief mechanism 40 and the edge of the active material layer is the minimum distance between the edge of the pressure relief mechanism 40 and the edge of the negative electrode sheet 22 .

[0069] In the present application, the minimum distance D between the pressure relief mechanism 40 and the edge of the active material layer can be measured by X-ray.

[0070] According to some embodiments of the present application, 0.5% ≤ S ≤ 25%, for example, it can be 0.5%, 5%, 10%, 15%, 20% or 25%, or it can be a range consisting of any of the above values. Thus, by setting the value of S within the above range, while improving the battery energy density, the expansion degree of the negative electrode plate 22 is reduced, the expansion deformation of the electrode assembly 20 is reduced, and the pulling force and deformation of the second wall 12 or the third wall 13 due to the expansion of the electrode assembly 20 are reduced, thereby reducing the probability of the pressure relief mechanism 20 being pulled and damaged, reducing the probability of leakage at the pressure relief mechanism 40, and improving the reliability of the battery cell 100. According to some specific embodiments of the present application, 5% ≤ S ≤ 15%.

[0071] In the present application, the mass ratio of the active material in the active material layer may be tested by inductively coupled plasma (ICP).

[0072] According to some embodiments of the present application, D / S>20mm. For example, it can be 20mm, 50mm, 100mm, or 200mm, or it can be a range consisting of any of the above values. Thus, S can be adjusted according to D, or D can be adjusted according to S. While improving the battery energy density, it can also reduce the expansion deformation of the electrode assembly 20, reduce the pulling of the first wall portion 11 due to the deformation of the electrode assembly 20, reduce the probability of the pressure relief mechanism 20 being pulled and damaged, reduce the probability of leakage at the pressure relief mechanism 40, and improve the reliability of the battery cell 100.

[0073] According to some embodiments of the present application, 3mm≤d≤20mm. For example, d can be 3mm, 5mm, 7mm, 9mm, 11mm, 13mm, 15mm, 17mm, 19mm, or 20mm, or can be a range of any of the above values. Thus, by setting the value of d within the above range, the pressure relief effect of the pressure relief mechanism 40 is improved while reducing the pulling of the pressure relief mechanism 40 by deformation of the housing 10, thereby reducing the probability of the pressure relief mechanism 40 being damaged by the pulling. According to some specific embodiments of the present application, 5mm≤d≤15mm.

[0074] In the present application, the minimum distance d between the edge of the pressure relief mechanism 40 and the outer surface of the second wall portion 12 or the outer surface of the third wall portion 13 can be measured by a steel ruler or a soft ruler.

[0075] According to some embodiments of the present application, the active material includes an expandable element, and the volume expansion rate of the expandable element is greater than or equal to 15%. For example, it can be 15%, 20%, 25%, 30%, 35% or 40%, etc., or it can be a range composed of any of the above values. As a result, the outer shell 10 will deform due to the expansion of the active material when the battery is charged and discharged. By making the values ​​of D, d and S within the above range, the pulling of the outer shell 10 on the pressure relief mechanism 40 after deformation can be reduced, and the probability of the pressure relief mechanism 40 being pulled and damaged can be reduced. According to some embodiments of the present application, the volume expansion rate of the expandable element is greater than or equal to 25%.

[0076] In the present application, the volume expansion rate of the active material can be tested by confocal microscopy.

[0077] According to some embodiments of the present application, the active material includes an expandable element, which includes at least one of silicon and graphite. This improves the battery's energy density. Simultaneously, by keeping the values ​​of D and S within the aforementioned ranges, the strain on the pressure relief mechanism 40 caused by deformation of the housing 10 is reduced, thereby reducing the probability of cracking the pressure relief mechanism 40. According to some specific embodiments of the present application, the active material includes silicon.

[0078] According to some embodiments of the present application, referring to FIG4 , the pressure relief mechanism 40 is integrally formed with the first wall portion 11. By integrally forming the pressure relief mechanism 40 with the first wall portion 11, the reliability of the pressure relief mechanism 40 can be improved, the connection process between the pressure relief mechanism 40 and the first wall portion 11 can be eliminated, and the manufacturing cost of the battery cell 100 can be reduced.

[0079] In some embodiments, referring to FIG. 4 , the first wall portion 11 includes a weak region 111 and a non-weak region 112. The weak region 111 is disposed along the edge of the pressure relief mechanism 40 and connects the pressure relief mechanism 40 and the non-weak region 112. The weak region 111 is configured to rupture when the pressure of the battery cell 100 is released. Specifically, the weak region 111, the non-weak region 112, and the pressure relief mechanism 40 are integrally formed. The non-weak region 112 constitutes the main body of the first wall portion 11, and the weak region 111 is a region of the first wall portion 11 that is weaker than the non-weak region 112, and the strength of the non-weak region 112 is greater than that of the weak region 111. The weak region 111 can be a weakened portion of the first wall portion 11, for example, by partially annealing the first wall portion 11 to reduce the strength of the region, thereby forming the weak region 111. Alternatively, a groove can be provided in the first wall portion 11 to form the weak region 111 in the region of the groove. When the battery cell 100 is depressurized, the first wall 11 may be cracked at the weak area 111 , and the pressure relief mechanism 40 may be opened with the weak area 111 as the boundary, with a larger pressure relief area, so that the discharge medium inside the housing 10 can be discharged quickly.

[0080] According to some embodiments of the present application, referring to FIG5 , the first wall portion 11 is provided with a notched groove 41, and the first wall portion 11 forms the weak zone 111 in the area where the notched groove 41 is provided. The notched groove 41 can be formed in a variety of ways, such as stamping, milling, laser etching, etc. The extension direction of the notched groove 41 is the same as the extension direction of the weak zone 111. The notched groove 41 can extend along a closed trajectory; the notched groove 41 can also extend along a non-closed trajectory, for example, the notched groove 41 is a groove extending along an arc-shaped, U-shaped, or other trajectory. The notched groove 41 can be provided on the inner surface and / or outer surface of the first wall portion 11. As an example, in the embodiment shown in FIG5 , the notched groove 41 is provided on the outer surface of the first wall portion 11. The bottom wall of the notched groove 41 is the weak zone 111, and the thickness of the weak zone 111 is less than the thickness of the non-weak zone 1112.

[0081] According to some embodiments of the present application, referring to FIG. 5 , a weak area 111 is formed by providing a notched groove 41 on the first wall portion 11 , thereby forming an integrated pressure relief mechanism 40 . The pressure relief mechanism 40 is simple to form and has low production costs.

[0082] According to some embodiments of the present application, the scoring groove 41 is a groove extending along a closed track.

[0083] It can be understood that the weakened area 111 extends along a closed trajectory, and the weakened area 111 defines the pressure relief mechanism 40 .

[0084] According to some embodiments of the present application, the notched groove 41 may be an annular groove, which may be a rectangular annular groove or a circular annular groove. A rectangular annular groove is a groove extending along a rectangular track, while a circular annular groove is a groove extending along a circular track.

[0085] In other embodiments, the notched groove 41 can also be of other shapes. The notched groove 41 is a groove extending along a trajectory such as a "double Y" shape, an "I" shape, and a "W" shape. At this time, a pressure relief mechanism 40 is formed at the bottom of the notched groove 41, so that the pressure relief mechanism 40 forms the above-mentioned corresponding shape. The pressure relief mechanism 40 forms a weak area relative to the first wall portion 11. The notched groove 41 here can also be understood as the notched groove 41. At this time, when the battery cell 100 is depressurized, the bottom of the notched groove 41 cracks, the pressure relief mechanism 40 is destroyed, and the first wall portion 11 can form an opening at the bottom of the notched groove 41 to achieve pressure relief.

[0086] During the pressure relief process, after the first wall portion 11 is cracked along the notched groove 41 , the pressure relief mechanism 40 can be opened by separating from the non-weakened area 1112 , thereby increasing the pressure relief area and improving the pressure relief rate of the battery cell 10 .

[0087] In some embodiments, referring to Figure 6, the scoring groove 41 includes two first arc segments 411 arranged opposite to each other and two first straight segments 412 arranged in parallel, and the two ends of each first straight segment 412 are respectively connected to the two first arc segments 411, and the two first straight segments 412 and the two first arc segments 411 form a closed annular structure; in the second direction F2, the outer edge of the positive projection of the annular structure constitutes the predetermined opening boundary of the predetermined pressure relief area 401, that is, the predetermined opening boundary is surrounded by the outer edge of the positive projection of the scoring groove 40 in the second direction F2.

[0088] In some embodiments, referring to Figure 7, the scoring groove 41 includes a second straight line segment 413 and four third straight line segments 414, and the two ends of the second straight line segment 413 are respectively connected to two third straight line segments 414 set at a preset angle; in the second direction F2, an arc segment 415 with the vertex of the preset angle as the center is defined between the free ends of the positive projections of the two third straight line segments 414 located at the same end of the second straight line segment 413, and a fourth straight line segment 416 is defined between the free ends of the positive projections of the two third straight line segments 414 located on the same side of the second straight line segment 413. The two arc segments 415 and the two fourth straight line segments 416 together constitute a predetermined opening boundary of the predetermined pressure relief area 401, that is, the predetermined opening boundary is surrounded by the connecting lines between the multiple ends of the scoring groove 40.

[0089] In some embodiments, referring to Figure 8, the scoring groove 41 includes a fifth straight line segment 417 and two sixth straight line segments 418, the fifth straight line segment 417 is located between the two sixth straight line segments 418, and the ends of the fifth straight line segment 417 are respectively connected to the middle parts of the corresponding sixth straight line segments 418, and a seventh straight line segment 419 is defined between the ends of the two sixth straight line segments 418 located on the same side of the fifth straight line segment 417. The outer edges of the positive projections of the seventh straight line segment 419 and the sixth straight line segment 418 in the second direction F2 constitute a predetermined opening boundary of the predetermined pressure relief area 401, that is, the predetermined opening boundary is jointly surrounded by the connecting lines between the multiple ends of the scoring groove 40 and the outer edges of the positive projections of a part of the scoring groove 40 in the second direction.

[0090] In some embodiments, referring to FIG. 2 , a patch 60 may be further provided on the outside of the pressure relief mechanism 40 . The patch 60 cooperates with the housing 10 to protect the pressure relief mechanism 40 .

[0091] According to some embodiments of the present application, referring to FIG. 1 and FIG. 2 , the pressure relief mechanism is separately provided from the first wall portion 11 , the first wall portion 11 is provided with a through hole, and the pressure relief mechanism 40 is installed in the through hole.

[0092] As shown in Figures 1 and 2, the pressure relief mechanism 40 and the shell 10 are two separate components, which are separately molded and then installed together. Specifically, the pressure relief mechanism 40 can be a component such as an explosion-proof disk, an explosion-proof valve, or a safety valve. The pressure relief mechanism 40 can be installed on the first wall portion 11 by bonding, welding, etc. The first wall portion 11 is provided with a through hole, and the pressure relief mechanism 40 is installed in the through hole. When the internal pressure of the battery cell 100 reaches a threshold value, the pressure relief mechanism 40 opens at least part of the through hole, and the discharge medium inside the battery cell 100 is discharged through the through hole to release the pressure inside the battery cell 100.

[0093] According to some embodiments of the present application, referring to FIG4 , along the first direction F1, the thickness of the battery cell 10 is W1, and the width of the pressure relief mechanism 40 is W2, and the following conditions are satisfied: 0.2 ≤ W2 / W1 ≤ 0.5. For example, the values ​​may be 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, or 0.5, or any range thereof. This reduces the pulling force of the housing 10 on the pressure relief mechanism 40 while increasing the energy density of the battery.

[0094] According to some embodiments of the present application, referring to FIG4 , the width of the pressure relief mechanism 40 along the first direction F1 is W2; along the third direction F3, the length of the pressure relief mechanism 40 is W3, and the following conditions are satisfied: 0.5 ≤ W2 / W3 ≤ 0.8. The third direction F3 intersects the second direction F2. For example, the width can be 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, or 0.8, or can be any range of the above values. This increases the pressure relief area and improves the pressure relief rate of the battery cell 100.

[0095] According to some embodiments of the present application, referring to FIG9 , the battery cell 100 further includes a positive electrode sheet 21 , the polarity of the positive electrode sheet 21 is opposite to that of the negative electrode sheet 22 , and the positive electrode sheet 21 and the negative electrode sheet 22 are stacked.

[0096] According to some embodiments of the present application, referring to FIG10 , the battery cell 100 further includes a positive electrode sheet 21 , the polarity of the positive electrode sheet 21 is opposite to that of the negative electrode sheet 22 , and the positive electrode sheet 21 and the negative electrode sheet 22 are wound together.

[0097] According to some embodiments of the present application, referring to Figures 1 and 2 , the housing 10 includes a shell 101 and an end cap 102 . The shell 101 has an opening on at least one side. The end cap 102 is connected to the shell 101 and is used to close the opening. The first wall portion 11 is formed on the shell 101 . As shown in Figures 1 and 2 , the shell 101 can be a hollow structure with an opening formed at one end, or a hollow structure with openings formed at two opposite ends. The shell 101 can have various shapes, such as a prismatic shape.

[0098] The end cap 102 is a component that closes the opening of the shell 101 to isolate the internal environment of the battery cell 100 from the external environment. The end cap 102 and the shell 101 together define a storage space for accommodating the electrode assembly 20, the electrolyte and other components. The shape of the end cap 102 can be adapted to the shape of the shell 10. For example, the shell 101 is a rectangular parallelepiped structure, and the end cap 102 is a rectangular plate structure adapted to the shell 10. For another example, the shell 101 is a cylindrical structure, and the end cap 102 is a circular plate structure adapted to the shell 101. The material of the end cap 102 can also be a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the end cap 102 and the shell 101 can be the same or different.

[0099] In an embodiment where the housing 101 is open at one end, one end cap 102 may be provided. In an embodiment where the housing 101 is open at two opposite ends, two end caps 102 may be provided, each of which closes the two openings of the housing 101, and the two end caps 102 and the housing 101 together define a receiving space.

[0100] The shell 101 has a first wall portion 11 and a second wall portion 12, and the pressure relief mechanism 40 is arranged on the shell 101. The pressure relief mechanism 40 can be integrally formed with the shell 101, or can be separately arranged from the shell 101. By arranging the pressure relief mechanism 40 on the shell 101, the structure of the end cover 102 can be simplified, and at the same time, it is convenient to shorten the distance between the pressure relief mechanism 40 and the main body of the electrode assembly 20, thereby shortening the path of the discharge medium flowing to the pressure relief mechanism 40 during pressure relief, shortening the time for the discharge medium to reach the pressure relief mechanism 40, and improving the timeliness of the pressure relief of the battery cell 100, thereby effectively improving the reliability of the battery cell 100.

[0101] As shown in FIG. 11 , in some embodiments, two opposite sides of the housing 101 have openings, and two end covers 102 are used to close the openings on the corresponding sides.

[0102] As shown in Figure 11, in an embodiment where the housing 101 has openings at opposite ends, two end caps 102 may be provided. The two end caps 102 respectively seal the two openings of the housing 101, and the two end caps 102 and the housing 101 together define a receiving space. The first wall 11 is located on the housing 101, the pressure relief mechanism 40 is located between the two openings, and each end cap 102 may be provided with an electrical connection portion 30.

[0103] By providing two openings on the shell 101, the shell 101 can be manufactured and formed more easily, and the electrode assembly 20 can be easily led out from both ends, thereby facilitating the separation of the two electrical connection parts 30 and reducing the risk of short circuit of the battery cell 100.

[0104] As shown in FIG1 and FIG2 , in some examples, the end cap 102 is provided with an electrical connection portion 30 , which is electrically connected to the positive electrode sheet 21 , or the negative electrode sheet 22 , thereby inputting or outputting electrical energy of the battery cell.

[0105] The electrical connection part 30 is arranged on the end cover 102. The electrical connection part 30 can be a part of the end cover 102, and the electrical connection part 30 can also be a pole installed on the end cover 102; usually there are two electrical connection parts 30, one electrical connection part 30 is electrically connected to the pole tab of the positive electrode plate 21, and the other electrical connection part 30 is electrically connected to the pole tab of the negative electrode plate 22 to input or output the electrical energy of the battery cell 100. The electrical connection part 30 and the pole tab can be directly connected, for example, the electrical connection part 30 and the pole tab are directly welded, and the electrical connection part 30 and the pole tab can also be indirectly connected, for example, the electrical connection part 30 and the pole tab are indirectly connected through a current collecting component, and the current collecting component can be a metal conductor, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0106] The electrical connection portion 30 and the pressure relief mechanism 40 are located on different sides of the housing 10, that is, the electrical connection portion 30 is located on one wall of the housing 10, and the pressure relief mechanism 40 is located on another wall of the housing 10. Because the electrical connection portion 30 is connected to the tab of the electrode assembly 20, there is a certain gap between the wall where the electrical connection portion 30 is located and the electrode assembly 20. By arranging the electrical connection portion 30 and the pressure relief mechanism 40 on different walls of the housing 10, the distance between the pressure relief mechanism 40 and the electrode assembly 20 can be shortened. Therefore, when the battery cell 100 thermally runs away, most of the exhaust medium in the housing 10 can flow directly from the edge of the electrode assembly 20 to the pressure relief mechanism 40, thereby shortening the path for the exhaust medium to flow to the pressure relief mechanism 40, allowing the exhaust medium to flow quickly to the pressure relief mechanism 40, shortening the time it takes for the exhaust medium to reach the pressure relief mechanism 40, and improving the timeliness of the pressure relief of the battery cell 100, thereby effectively improving the reliability of the battery cell 100.

[0107] According to some embodiments of the present application, referring to Figure 11, the shell 11 also includes a fourth wall portion 14, the first wall portion 11, the second wall portion 12, the fourth wall portion 14 and the third wall portion 13 are connected end to end in sequence, and the fourth wall portion 14 and the first wall portion 11 are arranged opposite to each other along the second direction.

[0108] In some embodiments, referring to FIG11 , the housing 101 further includes a fifth wall portion 15 and a sixth wall portion 16 . The first wall portion 11 and the fourth wall portion 14 are arranged opposite each other along the second direction ( F2 ), the second wall portion 12 and the third wall portion 13 are arranged opposite each other along the first direction ( F1 ), and the fifth wall portion 15 and the sixth wall portion 16 are arranged opposite each other along the third direction F3 . Thus, the housing 101 can be substantially in the shape of a quadrangular prism, having a simple structure and being easy to form.

[0109] According to some embodiments of the present application, referring to FIG. 12 , along the second direction F2, the distance between the first wall portion 11 and the fourth wall portion 14 is L1; along the first direction F1, the distance between the second wall portion 12 and the third wall portion 13 is L2, and L1>L2 is satisfied. Thus, when the electrode sheet expands, the first wall portion 11 and the fourth wall portion 14 are less affected by the negative electrode sheet 22 than the second wall portion 12 and the third wall portion 13. Because the pressure relief mechanism 40 is located on the first wall portion 11, the probability of the negative electrode sheet 22 expanding and obstructing or damaging the pressure relief mechanism 40 is reduced.

[0110] As shown in Figures 1 and 2, the first wall portion 11 is used to support the electrode assembly 20 and is located below the electrode assembly 20. Therefore, the pressure relief mechanism 40 can be provided at the bottom of the battery cell 100. An exhaust passage can be provided at the bottom of the battery cell 100. The exhaust passage can communicate with the pressure relief mechanism 40 to discharge high-temperature, high-pressure flue gas through the pressure relief mechanism 40 at the bottom into the exhaust passage and then to the outside world when thermal runaway occurs in the battery cell 100.

[0111] According to some embodiments of the present application, the material of the housing 10 includes at least one of aluminum, nickel-plated carbon steel, stainless steel, magnesium alloy, nickel alloy, copper alloy and zirconium alloy.

[0112] The shell 101 of the outer shell 10 can be made of nickel-plated carbon steel, such as SPCC. The shell 101 can also be made of stainless steel, such as SUS304, SUS316, etc. The shell 101 can also be made of a magnesium alloy, such as AZ31B. The shell 101 can also be made of a nickel alloy, such as Inconcel 625. The shell 101 can also be made of a copper alloy, such as brass. The shell 101 can also be made of a zirconium alloy, such as Zr702. Of course, the shell 101 can also be made of a composite material. By using the above materials, the tensile strength of the wall of the shell 101 can be increased, thereby reducing the deformation of the shell 101 when the electrode assembly 20 expands, reducing the probability of the shell 101 or the pressure relief mechanism 40 being pulled and broken, reducing the risk of leakage, and improving the reliability of the battery cell 100. The end cap 102 and the shell 101 can be made of the same material or different materials.

[0113] According to some embodiments of the present application, the positive electrode plate 21 includes a positive electrode current collector and a positive electrode active material region disposed on the surface of the positive electrode current collector, and the constituent material of the positive electrode current collector includes aluminum element with a mass percentage greater than or equal to 50%.

[0114] That is, the constituent material of the positive electrode current collector may include aluminum, and the mass percentage of aluminum in the positive electrode current collector is greater than or equal to 50%. By adopting the above-mentioned positive electrode current collector, compared with the composite current collector in the prior art, the manufacturing difficulty of the positive electrode plate 21 can be reduced, and the manufacturing cost can be reduced at the same time.

[0115] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0116] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0117] The electrode assembly 20 includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell 100, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0118] [Positive electrode]

[0119] In some embodiments, the positive electrode may be a positive electrode sheet, which includes a positive electrode collector and a positive electrode active material layer disposed on at least one surface of the positive electrode collector, wherein the positive electrode active material layer includes the positive electrode active material of the first aspect of the present application.

[0120] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0121] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0122] In some embodiments, when the battery is a lithium-ion battery, the positive electrode active material may adopt the positive electrode active material for lithium-ion batteries known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0123] For example, when the battery is a sodium ion battery, as an example, the positive electrode active material may include, but is not limited to, at least one of a layered transition metal oxide, a polyanion compound, and a Prussian blue analog.

[0124] Examples of the layered transition metal oxides include:

[0125] Na 1-x Cu h Fe k Mn l M 1 m O 2-y , where M 1 One or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0126] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, 0 <z≤0.1;

[0127] Na a Li b Ni c Mn d Fe e O2, of which 0.67 <a≤1,0<b<0.2,0<c<0.3,0.67<d+e<0.8,b+c+d+e=1。

[0128] Examples of the polyanionic compound include:

[0129] A 1 f M 3g (PO4) i O j X 1 3-j , where A 1 is one or more of H, Li, Na, K, and NH4, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, X 1 is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0130] Na n M 4 PO4X 2 , where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0131] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0132] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0133] As an example of the above Prussian blue analogs, for example, the following can be listed:

[0134] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + , NH4 + , an alkali metal cation, and an alkaline earth metal cation, M 6 and M 7 are each independently one or more of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A is H + , Li + , Na + , K + , NH4 + , Rb + , Cs+ 、Fr + 、Be 2+ Mg 2+ , Ca 2+ 、Sr 2+ 、Ba 2+ and Ra 2+ One or more of M 6 and M 7 Each is independently a cation of one or more transition metal elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn and W.

[0135] The modified compounds of the above materials may be doping-modified and / or surface-coated modified materials.

[0136] In some embodiments, the positive electrode active material layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0137] In some embodiments, the positive electrode active material layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0138] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0139] [Negative electrode]

[0140] In some embodiments, the negative electrode may be a negative electrode sheet including a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0141] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0142] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0143] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0144] In some embodiments, the negative electrode active material layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0145] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0146] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0147] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0148] [Electrolytes]

[0149] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. This application has no specific restrictions on the type of electrolyte, and it can be selected according to needs.

[0150] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0151] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0152] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0153] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0154] [Isolation film]

[0155] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0156] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0157] A second aspect of the present application provides a battery, comprising the battery cell 100 provided in the first aspect of the present application.

[0158] The battery mentioned in the embodiments of the present application may include one or more battery cells to provide a single physical module with higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel or in hybrid through a busbar.

[0159] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0160] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0161] 13 is an exploded view of a battery 1000 in the related art. The battery 1000 includes a battery cell 100 and a housing 200 for accommodating the battery cell 100.

[0162] The housing 200 is a component that houses the battery cells 100 and provides storage space for the battery cells 100. The housing 200 can have various structures. In some embodiments, the housing 200 can include a first portion 210 and a second portion 220, which overlap to define a storage space for the battery cells 100. The first portion 210 and the second portion 220 can have various shapes, such as a rectangular parallelepiped or a cylinder. The first portion 210 can be a hollow structure with one side open, and the second portion 220 can be a hollow structure with one side open. The open side of the second portion 220 overlaps the open side of the first portion 210, forming the housing 200 with storage space. Alternatively, the first portion 210 can be a hollow structure with one side open, and the second portion 220 can be a plate-like structure. The second portion 220 overlaps the open side of the first portion 210, forming the housing 200 with storage space. As an example, the battery cell 100 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell 100 of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a polygonal battery, and a polygonal battery such as a hexagonal battery, etc. There is no special limitation in this application.

[0163] In the battery 1000, there can be one or more battery cells 100. If there are multiple battery cells 100, the multiple battery cells 100 can be connected in series, parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 100. Multiple battery cells 100 can be connected in series, parallel, or in a hybrid connection to form a battery module, which is then connected in series, parallel, or in a hybrid connection to form a whole and housed within the housing 200. Alternatively, all battery cells 100 can be directly connected in series, parallel, or in a hybrid connection, and then the whole battery module 100 can be housed within the housing 200.

[0164] A third aspect of the present application provides an electrical device comprising the battery provided in the second aspect of the present application. Battery 1000 is used to provide electrical energy to the electrical device. Thus, the use of battery 1000 can improve the safety and reliability of the electrical device.

[0165] Optionally, as shown in FIG14 , when battery 1000 is used in vehicle 2000, battery 1000 may be installed at the bottom, front, or rear of vehicle 2000. Battery 1000 may be used to power vehicle 2000. For example, battery 1000 may serve as an operating power source for vehicle 2000. Vehicle 2000 may also include a controller and a motor. The controller is used to control battery 1000 to power the motor, for example, to meet the power requirements of vehicle 2000 during startup, navigation, and driving.

[0166] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0167] Example 1

[0168] 1) Preparation of positive electrode sheet

[0169] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are prepared into positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 80wt%, and the solid content of LiNi 0.8 Co 0.1 Mn 0.1 The mass ratio of O2, Super P and PVDF is 8:1:1. The positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil and dried at 85°C and then cold pressed. Then, it is trimmed, cut and striped, and dried under vacuum conditions at 85°C for 4 hours to make the positive electrode sheet.

[0170] 2) Preparation of negative electrode sheet

[0171] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry is 50wt%, the mass ratio of graphite, silicon oxide, Super P, CMC and adhesive styrene butadiene rubber (SBR) in the solid components is 88:7:3:2, and the mass proportion S of graphite and silicon oxide in the negative electrode active material layer is 10%. The negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C, and then cold pressed, trimmed, cut, and slit, and then dried under vacuum conditions at 120°C for 12 hours to prepare a negative electrode sheet.

[0172] 3) Preparation of electrolyte

[0173] In an argon atmosphere glove box (H2O <0.1ppm, O2 <0.1ppm), the fully dried electrolyte salt LiPF6 was dissolved in a mixed solvent (the mixed solvent included ethylene carbonate (EC) and diethyl carbonate (DEC), and ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a mass ratio of 50:50), and after mixing evenly, a liquid electrolyte with a concentration of 1 mol / L was obtained.

[0174] 4) Isolation parts

[0175] A 16 μm polyethylene film was used as a separator.

[0176] 5) Lithium-ion battery preparation

[0177] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive and negative electrode sheets to separate the positive and negative electrodes. The bare cell is wound and the tabs are welded. The bare cell is placed in an aluminum casing, and the prepared electrolyte is injected into the dried casing. The battery is packaged, left to stand, formed, shaped, and capacity tested to complete the preparation of the lithium-ion battery (the lithium-ion battery has a thickness of 31 mm, a width of 237.5 mm, and a length of 117.4 mm). After preparation, the minimum distance D between the pressure relief mechanism and the edge of the negative electrode active material layer along the second direction is 1 mm. Along the first direction, the distances d between the edge of the pressure relief mechanism and the outer surface of the second wall portion and the outer surface of the third wall portion are both 10 mm.

[0178] The preparation methods of the batteries in Examples 2 to 14 and Comparative Examples 1 to 5 are the same as in Example 1, with the differences detailed in Table 1.

[0179] Table 1

[0180] Performance Testing

[0181] 1. Test method for whether explosion-proof valve is cracked

[0182] At 45°C, charge and discharge the battery at a constant current of 0.33C. Check the explosion-proof valve every 50 cycles to see if it is cracked or leaking.

[0183] 2. Energy density test method

[0184] At 25°C, the battery is charged and discharged at a constant current of 0.33C. The charge and discharge test is performed within the range of 2.8V-4.25V to obtain the battery capacity. The capacity is divided by the battery size (length, width and height) to obtain the energy density, which is expressed in Wh / L.

[0185] The test results of the batteries in Examples 1 to 14 and Comparative Examples 1 to 5 are shown in Table 2.

[0186] Table 2

[0187] As can be seen from Table 2, the present application can improve the energy density of the battery while reducing the probability of the pressure relief mechanism being pulled and damaged, reducing the probability of leakage at the pressure relief mechanism, and improving the reliability of the battery cell by making the values ​​of D, S and d simultaneously satisfy: 3mm≤D≤15mm, 0.5%≤S≤30%, 3mm≤d≤20mm.

[0188] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, wherein, Comprising: A housing including a first wall portion, a second wall portion, and a third wall portion. The second wall portion and the third wall portion are disposed opposite to each other along a first direction, and two ends of the first wall portion along the first direction are respectively connected to the second wall portion and the third wall portion; A pressure relief mechanism provided on the first wall portion and configured to be able to relieve the pressure inside the battery cell; An electrode assembly accommodated in the housing. The electrode assembly includes at least one negative electrode tab, and an active material layer is formed on at least one side of the negative electrode tab. The active material layer includes an active material. Along a second direction, the first wall portion is disposed facing the edge of the negative electrode tab. The second direction is the thickness direction of the first wall portion and is perpendicular to the first direction; wherein, Along the second direction, the minimum distance between the pressure relief mechanism and the edge of the active material layer is D, and 3mm ≤ D ≤ 15mm; Based on the total mass of the active material layer, the mass ratio of the active material is S, and 0.5% ≤ S ≤ 25%; Along the first direction, the minimum distance between the edge of the pressure relief mechanism and the outer surface of the second wall portion or the outer surface of the third wall portion is d, and 3mm ≤ d ≤ 20mm.

2. The battery cell according to claim 1, wherein, 3mm ≤ D ≤ 10mm, 5% ≤ S ≤ 15%.

3. The battery cell according to claim 2, wherein, D / S > 20mm.

4. The battery cell according to claim 1, wherein, 2mm ≤ D ≤ 10mm, 5mm ≤ d ≤ 15mm.

5. The battery cell according to claim 4, wherein, 10mm 2 ≤D×d≤150mm 2 。 6. The battery cell according to any one of claims 1-5, wherein, The active material includes an expandable element, and the expandable element includes at least one of silicon or graphite.

7. The battery cell according to any one of claims 1-6, wherein, The pressure relief mechanism is integrally formed with the first wall portion.

8. The battery cell according to claim 7, wherein, The first wall portion includes a weak area and a non-weak area. The weak area is disposed along the edge of the pressure relief mechanism and connects the pressure relief mechanism and the non-weak area. The weak area is configured to crack when the battery cell relieves pressure.

9. The battery cell according to claim 8, wherein, The first wall portion is provided with a scoring groove, and the first wall portion forms the weak area in the area where the scoring groove is provided.

10. The battery cell according to claim 9, wherein, The scoring groove is a groove extending along a closed trajectory.

11. The battery cell according to any one of claims 1-6, wherein, The pressure relief mechanism is separately provided from the first wall portion. The first wall portion is provided with a through hole, and the pressure relief mechanism is installed in the through hole.

12. The battery cell according to any one of claims 1-11, wherein, Along the first direction, the thickness of the battery cell is W1, and the width of the pressure relief mechanism is W2, and it satisfies: 0.2 ≤ W2 / W1 ≤ 0.

5.

13. The battery cell according to any one of claims 1-12, wherein, Along the first direction, the width of the pressure relief mechanism is W2; along a third direction, the length of the pressure relief mechanism is W3, and it satisfies: 0.5 ≤ W2 / W3 ≤ 0.

8. The third direction is perpendicular to the second direction.

14. The battery cell according to any one of claims 1-13, wherein, The housing further includes a fourth wall portion. The first wall portion, the second wall portion, the fourth wall portion, and the third wall portion are sequentially connected end to end. The fourth wall portion and the first wall portion are disposed opposite to each other along the second direction.

15. The battery cell according to claim 14, wherein, Along the second direction, the distance between the first wall portion and the fourth wall portion is L1; along the first direction, the distance between the second wall portion and the third wall portion is L2, and it satisfies, L1 > L2.

16. The battery cell according to any one of claims 1-15, wherein, The electrode assembly further includes at least one positive electrode tab. The polarity of the positive electrode tab is opposite to that of the negative electrode tab, and the positive electrode tab and the negative electrode tab are stacked.

17. The battery cell according to any one of claims 1-15, wherein, The electrode assembly further includes at least one positive electrode tab, the polarity of the positive electrode tab being opposite to that of the negative electrode tab, and the positive electrode tab and the negative electrode tab are wound together.

18. The battery cell according to any one of claims 1-17, wherein, The housing includes: a housing body and an end cap, at least one side of the housing body having an opening, the end cap being connected to the housing body and configured to close the opening, and the first wall portion being formed on the housing body.

19. The battery cell according to claim 18, wherein, Both opposite sides of the housing body have openings, and the two end caps are configured to close the openings on the corresponding sides.

20. The battery cell according to claim 18 or 19, wherein, The end cap is provided with an electrical connection portion, and the electrical connection portion is electrically connected to the positive electrode tab, or the electrical connection portion is electrically connected to the negative electrode tab.

21. The battery cell according to claims 1-20, wherein, The first wall portion is configured to support the electrode assembly and is located below the electrode assembly.

22. The battery cell according to any one of claims 1-21, wherein, The material of the housing includes at least one of aluminum, nickel-plated carbon steel, stainless steel, magnesium alloy, nickel alloy, copper alloy, and zirconium alloy.

23. The battery cell according to any one of claims 16-22, wherein, The positive electrode tab includes a positive current collector and a positive active material region provided on the surface of the positive current collector, and the constituent material of the positive current collector includes aluminum element with a mass percentage of greater than or equal to 50%.

24. A battery, wherein, Including the battery cell according to any one of claims 1-23.

25. An electrical device, wherein, Including the battery according to claim 24.

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