Battery cell, battery, and electric device

Abstract

The present application discloses a battery cell, a battery, and an electric device. The battery cell comprises: a casing, the casing comprising a first wall portion; a pressure relief mechanism, the pressure relief mechanism being arranged on the first wall portion; and an electrode assembly, being accommodated in the casing, the electrode assembly comprising at least one negative electrode sheet, the first wall portion facing the edge of the negative electrode sheet, an active material layer being formed on at least one side of the negative electrode sheet, the active material layer comprising a first region and a second region which are arranged in a first direction, the second region being closer to the first wall portion than the first region, the first direction being parallel to the thickness direction of the first wall portion, and in a full-charge state, the thickness of the second region being a μm, and the thickness of the first region being b μm, wherein b-a≥5 μm.

Description

Battery cells, batteries, and electrical equipment Technical Field

[0001] The present application relates to the field of battery technology, 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 increase the service life 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 negative electrode plates will expand, causing the outer shell to expand and deform. After the outer shell is deformed, it is easy to pull the pressure relief mechanism, causing the pressure relief mechanism to crack and break, 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 area of ​​the shell close to the first wall on the pressure relief mechanism and reduce the probability of cracking of the pressure relief mechanism.

[0006] The first aspect of the present application provides a battery cell, including a shell, the shell including a first wall portion; a pressure relief mechanism, the pressure relief mechanism being arranged on the first wall portion; an electrode assembly, accommodated in the shell, the electrode assembly including at least one negative electrode sheet, the first wall portion being arranged facing the edge of the negative electrode sheet, an active material layer being formed on at least one side of the negative electrode sheet, the active material layer including a first region and a second region arranged along a first direction, the second region being closer to the first wall portion than the first region, the first direction being parallel to the thickness direction of the first wall portion, the thickness of the second region being aμm in a fully charged state, the thickness of the first region being bμm, and satisfying ba≥5μm.

[0007] The battery cell proposed in the present application can reduce the expansion force of the part of the shell close to the pressure relief mechanism by ensuring that the thickness difference between the first area and the second area after full charge is within the above-mentioned range, reduce the pulling of the shell on the pressure relief mechanism, reduce the probability of the pressure relief mechanism being pulled and damaged, reduce the probability of leakage at the pressure relief mechanism, and improve the reliability of the battery cell.

[0008] According to some embodiments of the present application, 10μm ≤ ba ≤ 33μm. This allows the expansion force of the housing to be primarily concentrated in the area away from the pressure relief mechanism, reducing the expansion force in the area near the pressure relief mechanism. This reduces the pull of the housing on the pressure relief mechanism, lowering the probability of damage to the pressure relief mechanism due to the pull, and improving the reliability of the battery cell. This also reduces the excessive stress generated at the junction of the first and second regions, reducing the risk of active ion precipitation.

[0009] According to some embodiments of the present application, 210 μm ≤ a ≤ 275 μm, and 195 μm ≤ b ≤ 245 μm. This reduces the expansion force on the portion of the housing near the pressure relief mechanism, reduces the pulling of the housing on the pressure relief mechanism, reduces the probability of damage to the pressure relief mechanism, reduces the probability of leakage from the pressure relief mechanism, and improves the reliability of the battery cell.

[0010] According to some embodiments of the present application, the first region includes a first active material, the second region includes a second active material, and the mass per unit area of ​​the first active material in the first region is w1 g / m 2 The volume expansion rate of the first active material is v1, and the mass per unit area of ​​the second active material in the second region is w2g / m 2 The volume expansion rate of the second active material is v2. Under the condition w1=w2, v1>v2. This reduces the expansion of the second region, reduces deformation of the housing caused by expansion of the active material layer near the first wall, reduces the pull of the housing on the pressure relief mechanism near the pressure relief mechanism, and reduces the probability of cracking the pressure relief mechanism.

[0011] According to some embodiments of the present application, both the first active material and the second active material include silicon-based materials, and the mass proportion of the silicon-based material in the first active material is greater than the mass proportion of the silicon-based material in the second active material.

[0012] According to some embodiments of the present application, the mass proportion of the silicon-based material in the first active material is less than or equal to 30%, and the mass proportion of the silicon-based material in the second active material is less than or equal to 15%.

[0013] According to some embodiments of the present application, both the first active material and the second active material include graphite, and a volume expansion rate of the graphite in the first active material is greater than a volume expansion rate of the graphite in the second active material.

[0014] Therefore, through the above method, the thickness of the first area after full filling is greater than the thickness of the second area after full filling, reducing the expansion force of the part of the shell close to the pressure relief mechanism, reducing the pulling of the shell on the pressure relief mechanism, and reducing the probability of the pressure relief mechanism being pulled and damaged.

[0015] According to some embodiments of the present application, the active materials of the first region and the second region are of the same type, and the mass per unit area of ​​the first active material in the first region is w1g / m 2 , the mass per unit area of ​​the second active material in the second region is w2g / m 2 , w1>w2. Thus, the thickness of the first region after full filling is greater than the thickness of the second region after full filling, reducing the expansion force on the portion of the shell near the pressure relief mechanism, reducing the pulling of the shell on the pressure relief mechanism, and reducing the probability of the pressure relief mechanism being damaged by the pulling, and reducing the probability of the pressure relief mechanism cracking.

[0016] According to some embodiments of the present application, the values ​​of w1 and w2 satisfy at least one of the following conditions: 140 g / m 2 ≤w1≤200g / m 2 ;112g / m 2 ≤w2≤180g / m 2 Therefore, by setting the values ​​of w1 and w2 within the above range, the thickness of the first region after full filling is made greater than the thickness of the second region after full filling, thereby reducing the pulling of the shell close to the pressure relief mechanism on the pressure relief mechanism and reducing the probability of cracking of the pressure relief mechanism.

[0017] According to some embodiments of the present application, along the first direction, the height of the first region is h1, the height of the second region is h2, and 5≤h1 / h2≤30. This reduces the probability of cracking of the pressure relief mechanism and improves the energy density of the battery.

[0018] According to some embodiments of the present application, 60mm≤h1≤120mm, optionally 80mm≤h1≤100mm.

[0019] According to some embodiments of the present application, 2mm≤h2≤15mm, optionally 5mm≤h2≤10mm.

[0020] Therefore, by making h1 and h2 within the above range, the degree of deformation of the shell caused by the expansion of the active material layer near the first wall is reduced, the pulling of the shell on the pressure relief mechanism by the pressure relief mechanism is reduced, the probability of cracking of the pressure relief mechanism is reduced, and at the same time, the energy density of the battery is improved.

[0021] According to some embodiments of the present application, the battery cell further includes: a positive electrode sheet, the polarity of the positive electrode sheet is opposite to that of the negative electrode sheet, the positive electrode sheet and the negative electrode sheet are stacked in a second direction, and the second direction intersects with the first direction.

[0022] According to some embodiments of the present application, the battery cell further includes: a positive electrode sheet, the polarity of the positive electrode sheet is opposite to the polarity of the negative electrode sheet, and the positive electrode sheet and the negative electrode sheet are wound together.

[0023] According to some embodiments of the present application, the pressure relief mechanism is integrally formed with the first wall portion, thereby increasing the reliability of the pressure relief mechanism, eliminating the need for a connection process between the pressure relief mechanism and the first wall portion, and reducing the production cost of the battery cell.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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, and the distance between the pressure relief mechanism and the electrode assembly can be shortened. This can further shorten the path of the discharge medium flowing to the pressure relief mechanism during pressure relief, shorten the time it takes for the discharge medium to reach the pressure relief mechanism, improve the timeliness of pressure relief of the battery cell, and thus effectively improve the reliability of the battery cell.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] According to some embodiments of the present application, the housing further comprises: a second wall portion, a third wall portion, and a fourth wall portion, wherein the fourth wall portion and the first wall portion are arranged opposite each other in the first direction, the second wall portion and the third wall portion are arranged opposite each other in the second direction, and the first wall portion, the second wall portion, the fourth wall portion, and the third wall portion are connected end to end in sequence. 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, has a simple structure, and is easy to form.

[0033] According to some embodiments of the present application, along the first direction, the minimum distance between the first wall portion and the fourth wall portion is L1, and the minimum distance between the second wall portion and the third wall portion 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 portion, the risk of the pressure relief mechanism being blocked or damaged by the electrode assembly expansion is reduced.

[0034] 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.

[0035] 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.

[0036] A second aspect of the present application provides a battery, comprising the battery cell provided in the first aspect of the present application.

[0037] A third aspect of the present application provides an electrical device, comprising the battery provided in the second aspect of the present application.

[0038] 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

[0039] 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:

[0040] FIG1 is a schematic diagram of a battery cell provided in some embodiments of the present application;

[0041] FIG2 is an exploded view of a battery cell provided in some embodiments of the present application;

[0042] FIG3 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0043] FIG4 is a schematic diagram of an electrode assembly provided in some embodiments of the present application;

[0044] FIG5 is a schematic diagram of electrode assemblies provided in some other embodiments of the present application;

[0045] FIG6 is a schematic diagram of a first wall portion provided in some embodiments of the present application;

[0046] FIG7 is a cross-sectional view along line AA in FIG6 provided in some embodiments;

[0047] FIG8 is a schematic diagram of a pressure relief mechanism provided in some embodiments of the present application;

[0048] FIG9 is a schematic diagram of a pressure relief mechanism provided in some other embodiments of the present application;

[0049] FIG10 is a schematic diagram of a pressure relief mechanism provided in some other embodiments of the present application;

[0050] FIG11 is a schematic diagram of a battery cell provided in some other embodiments of the present application;

[0051] FIG12 is a schematic diagram of a fifth wall portion of a battery cell provided by some embodiments of the present application;

[0052] FIG13 is a schematic diagram of a battery in the related art;

[0053] FIG14 is a schematic diagram of an electrical device in the related art.

[0054] Description 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 Cap 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, First Region 221, Second Region 222, 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

[0055] 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.

[0056] 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.

[0057] " 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.

[0058] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] During the charging and discharging process of the battery cell, the electrode assembly will expand, causing the shell to swell and deform, and the pressure relief mechanism is arranged on the shell, especially some pressure relief mechanisms are arranged on the wall on the side closer to the electrode assembly. The expansion of the electrode assembly will cause the wall where the pressure relief mechanism is located to deform, thereby pulling the notch of the pressure relief mechanism, causing the pressure relief mechanism to be damaged at the notch and then leaking, etc. As a result, the pressure relief mechanism will be destroyed 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 is low.

[0063] The present application proposes a battery cell, in which the negative electrode plate includes a first region and a second region, and the second region is closer to the first wall portion where the pressure relief mechanism is located than the first region. By ensuring that the thickness difference between the first region and the second region after full charge is within the above-mentioned range, the degree of deformation of the shell near the first wall portion is reduced, thereby reducing the pulling of the shell on the pressure relief mechanism, reducing the cracking rate of the pressure relief mechanism, reducing the probability of leakage at the pressure relief mechanism, and improving the reliability of the battery cell.

[0064] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0065] 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.

[0066] In a first aspect, the present application provides a battery cell 100. Referring to Figure 1, the battery cell 100 includes a shell 10, which includes a first wall portion 11; a pressure relief mechanism 40, which is arranged on the first wall portion 11; an electrode assembly 20, which is accommodated in the shell 10, and the electrode assembly 20 includes at least one negative electrode sheet 22, the first wall portion 11 is arranged facing the edge of the negative electrode sheet 22, and an active material layer is formed on at least one side of the negative electrode sheet 22, and the active material layer includes a first region 221 and a second region 222 arranged along a first direction F1, the second region 222 is closer to the first wall portion 11 than the first region 221, the first direction F1 is parallel to the thickness direction of the first wall portion 11, and when fully charged, the thickness of the second region 222 is aμm, the thickness of the first region 221 is bμm, and ba≥5μm is satisfied.

[0067] The battery cell 100 proposed in the present application can reduce the expansion force of the portion of the outer shell 10 close to the pressure relief mechanism 40 by ensuring that the difference in thickness between the first region 221 and the second region 222 after full charge is within the above-mentioned range, thereby reducing the pulling of the outer shell 10 on the pressure relief mechanism 40, 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, a ten-thousand-meter or a micrometer may be used to measure the thickness of the first region 221 and the second region 222 .

[0069] According to some embodiments of the present application, 10μm≤ba≤33μm, for example, it can be 10μm, 15μm, 20μm, 25μm, 30μm or 33μm, or it can be a range composed of any of the above values. Therefore, by making the thickness difference between the first region 221 and the second region 222 after full charge within the above range, the expansion force of the shell 10 can be mainly concentrated in the area away from the first wall portion 11, thereby reducing the expansion force of the shell 10 close to the first wall portion 11, reducing the pulling of the shell 10 close to the first wall portion 11 on the pressure relief mechanism 40, reducing the probability of cracking of the pressure relief mechanism 40, and improving the reliability of the battery cell 100. By making ba≤33μm, the stress at the junction of the first region 221 and the second region 222 is reduced, and the probability of active ion precipitation is reduced.

[0070] According to some embodiments of the present application, 210 μm ≤ a ≤ 275 μm, and 195 μm ≤ b ≤ 245 μm. For example, a can be 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm, or 275 μm, or any range thereof; b can be 195 μm, 205 μm, 215 μm, 225 μm, 235 μm, or 245 μm, or any range thereof. This reduces the expansion force on the portion of the housing 10 near the pressure relief mechanism 40, reduces the pulling force of the housing 10 on the pressure relief mechanism 40, and reduces the probability of the pressure relief mechanism 40 being damaged by the pulling.

[0071] According to some embodiments of the present application, the first region 221 includes a first active material, the second region 222 includes a second active material, and the mass per unit area of ​​the first active material in the first region 221 is w1 g / m 2 The volume expansion rate of the first active material is v1, and the mass per unit area of ​​the second active material in the second region 222 is w2 g / m 2 The volume expansion rate of the second active material is v2. Under the condition w1=w2, v1>v2. This reduces the thickness change rate of the second region 222 compared to the thickness change rate of the first region 221, reducing deformation of the housing caused by expansion of the active material layer near the first wall. This also reduces the pull of the housing on the pressure relief mechanism near the pressure relief mechanism, thereby reducing the probability of cracking the pressure relief mechanism.

[0072] Specifically, under the condition of w1=w2, v1>v2 can be achieved in the following way:

[0073] According to some embodiments of the present application, both the first active material and the second active material include silicon-based materials, and the mass proportion of the silicon-based material in the first active material is greater than the mass proportion of the silicon-based material in the second active material.

[0074] As an example, the first active material and the second active material both include graphite, and the mass proportion of the silicon-based material in the first active material is greater than the mass proportion of the silicon-based material in the second active material.

[0075] As an example, both the first active material and the second active material include graphite, and only the first active material includes a silicon-based material.

[0076] Therefore, after charging, the expansion degree of the first area 221 is greater than the expansion degree of the second area 222, which reduces the deformation degree of the shell 10 caused by the expansion of the active material layer near the first wall portion 11, reduces the pulling of the shell 10 on the pressure relief mechanism 40 near the pressure relief mechanism, reduces the probability of cracking of the pressure relief mechanism 40, and improves the reliability of the battery cell 100.

[0077] In the present application, after the active material layer on the negative electrode sheet is scraped off, the mass ratio of the active material in the active material layer can be tested by inductively coupled plasma (ICP).

[0078] As an example, the silicon-based material may include at least one of silicon oxide or silicon carbide.

[0079] According to some embodiments of the present application, the mass proportion of the silicon-based material in the first active material is less than or equal to 30%, and the mass proportion of the silicon-based material in the second active material is less than or equal to 15%. For example, the mass proportion of the silicon-based material in the first active material can be 5%, 10%, 15%, 20%, 25% or 30%, or can be a range consisting of any of the above values; the mass proportion of the silicon-based material in the second active material can be 3%, 6%, 9%, 12% or 15%, or can be a range consisting of any of the above values. Thus, by making the content of silicon-based materials in the first region 221 and the second region 222 different, the thickness of the first region 221 and the second region 222 after full filling is different, thereby reducing the expansion force of the part of the shell near the pressure relief mechanism, reducing the pulling of the shell on the pressure relief mechanism, 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.

[0080] According to some embodiments of the present application, both the first active material and the second active material include graphite, and the volume expansion rate of the graphite in the first active material is greater than the volume expansion rate of the graphite in the second active material. As an example, the first active material includes natural graphite, and the second active material may be coated with carbon nanotubes on the surface of the natural graphite to reduce the volume expansion rate of the graphite in the second active material. Thus, by making the content of silicon-based materials in the first region 221 and the second region 222 different, the thickness of the first region 221 and the second region 222 after full filling is made different, thereby reducing the expansion force of the part of the shell close to the pressure relief mechanism, reducing the pulling of the shell on the pressure relief mechanism, 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.

[0081] In the present application, the volume expansion rate of the active material can be tested by confocal microscopy.

[0082] According to some embodiments of the present application, the active materials of the first region 221 and the second region 222 are of the same type, and the mass per unit area of ​​the first active material in the first region 221 is w1 g / m 2 The mass per unit area of ​​the second active material in the second region 222 is w2 g / m 2, w1>w2. Thus, the thickness of the first region 221 after full filling is greater than the thickness of the second region after full filling, reducing the expansion force on the portion of the shell near the pressure relief mechanism, reducing the pulling of the shell on the pressure relief mechanism, and reducing the probability of the pressure relief mechanism being damaged by the pulling, and reducing the probability of the pressure relief mechanism cracking.

[0083] According to some embodiments of the present application, 140g / m 2 ≤w1≤200g / m 2 , for example, it can be 140g / m 2 , 150g / m 2 , 160g / m 2 , 180g / m 2 , 190g / m 2 or 200g / m 2 etc., or can be within the range of any of the above numerical values.

[0084] According to some embodiments of the present application, 112 g / m 2 ≤w2≤180g / m 2 , for example, it can be 112g / m 2 , 120g / m 2 , 140g / m 2 , 160g / m 2 or 180g / m 2 etc., or can be within the range of any of the above numerical values.

[0085] Therefore, by making the values ​​of w1 and w2 within the above range, the thickness of the first area 221 after full filling is made greater than the thickness of the second area 222 after full filling, thereby reducing the pulling of the shell close to the pressure relief mechanism on the pressure relief mechanism and reducing the probability of cracking of the pressure relief mechanism.

[0086] According to some embodiments of the present application, the height of the first region 221 is h1, and the height of the second region 222 is h2, and 5≤h1 / h2≤30. For example, it can be 5, 10, 15, 20, 25, or 30, or it can be a range consisting of any of the above values. Thus, while improving the energy density of the battery, the expansion force of the shell 10 is mainly concentrated in the area away from the first wall portion 11, thereby reducing the expansion force of the shell 10 near the first wall portion 11, reducing the pulling of the shell 10 near the first wall portion 11 on the pressure relief mechanism 40, reducing the probability of cracking of the pressure relief mechanism 40, and improving the reliability of the battery cell 100.

[0087] According to some embodiments of the present application, 60 mm ≤ h1 ≤ 120 mm, for example, it can be 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, or 120 mm, or it can be a range consisting of any of the above values. According to some specific embodiments of the present application, 80 mm ≤ h1 ≤ 100 mm.

[0088] According to some embodiments of the present application, 2 mm ≤ h2 ≤ 15 mm, for example, 2 mm, 5 mm, 7 mm, 9 mm, 11 mm, 13 mm, or 15 mm, or a range consisting of any of the above values. According to some specific embodiments of the present application, 5 mm ≤ h2 ≤ 10 mm.

[0089] Therefore, by making the values ​​of h1 and h2 within the above range, while improving the battery energy density, the expansion force of the shell 10 is mainly concentrated in the area away from the first wall portion 11, thereby reducing the expansion force of the shell 10 close to the first wall portion 11, reducing the pulling of the shell 10 close to the first wall portion 11 on the pressure relief mechanism 40, reducing the probability of cracking of the pressure relief mechanism 40, and improving the reliability of the battery cell 100.

[0090] According to some embodiments of the present application, referring to FIG. 4 , 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.

[0091] According to some embodiments of the present application, referring to FIG5 , 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.

[0092] According to some embodiments of the present application, referring to FIG6 , 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.

[0093] In some embodiments, referring to FIG6 , 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 battery cell 100 releases pressure. 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 that 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.

[0094] According to some embodiments of the present application, referring to Figure 7, the first wall portion 11 is provided with a notched groove 41, and the first wall portion 11 forms the weak area 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 area 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 Figure 5, the notched groove 41 is provided on the outer surface of the first wall portion 11.

[0095] The bottom wall of the notched groove 41 is a weak area 111 , and the thickness of the weak area 111 is smaller than the thickness of the non-weak area 1112 .

[0096] According to some embodiments of the present application, referring to FIG. 7 , 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.

[0097] According to some embodiments of the present application, the scoring groove 41 is a groove extending along a closed track.

[0098] 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 .

[0099] 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.

[0100] 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.

[0101] 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 .

[0102] In some embodiments, referring to Figure 8, 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.

[0103] In some embodiments, referring to Figure 9, 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.

[0104] In some embodiments, referring to Figure 10, 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.

[0105] 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 .

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] According to some embodiments of the present application, referring to Figures 1 and 2, the shell 10 also includes: a second wall portion 12, a third wall portion 13 and a fourth wall portion 14, the fourth wall portion 14 and the first wall portion 11 are arranged opposite to each other in the first direction F1, the second wall portion 12 and the third wall portion 13 are arranged opposite to each other in the second direction F2, and 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.

[0119] In some embodiments, referring to FIG11 , the housing 101 further includes a fifth wall 15 and a sixth wall 16 . The first wall 11 and the fourth wall 14 are arranged relative to each other along the first direction ( F1 ), the second wall 12 and the third wall 13 are arranged relative to each other along the second direction ( F2 ), and the fifth wall 15 and the sixth wall 16 are arranged relative to 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.

[0120] According to some embodiments of the present application, referring to FIG. 12 , along the first direction F1, the distance between the first wall portion 11 and the fourth wall portion 14 is L1; along the second direction F2, 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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%.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] [Positive electrode]

[0130] 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.

[0131] 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.

[0132] 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.).

[0133] 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 0.8 Co 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.

[0134] 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.

[0135] Examples of the layered transition metal oxides include:

[0136] 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;

[0137] 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;

[0138] 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。

[0139] Examples of the polyanionic compound include:

[0140] A 1 f M 3 g (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;

[0141] Na n M 4 PO4X 2 , where M 4is 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;

[0142] 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;

[0143] 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.

[0144] As an example of the above Prussian blue analogues, for example, the following can be listed:

[0145] 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<00001​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​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.

[0148] 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.

[0149] 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.

[0150] [Negative electrode]

[0151] 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.

[0152] 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.

[0153] 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.).

[0154] 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.

[0155] 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).

[0156] 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.

[0157] 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)).

[0158] 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.

[0159] [Electrolytes]

[0160] 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.

[0161] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] [Isolation film]

[0166] 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.

[0167] 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.

[0168] A second aspect of the present application provides a battery, comprising the battery cell 100 provided in the first aspect of the present application.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] Example 1

[0179] 1) Preparation of positive electrode sheet

[0180] 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 75wt%, 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.

[0181] 2) Preparation of negative electrode sheet

[0182] The negative electrode active material (graphite and silicon oxide) is mixed evenly with the conductive agent Super P, the thickener carboxymethyl cellulose (CMC), and the adhesive styrene-butadiene rubber (SBR) in deionized water to form a negative electrode slurry, wherein the solid content in the negative electrode slurry is 50wt%, and the mass ratio of the negative electrode active material, Super P, CMC and SBR in the solid component is 88:7:3:2. Based on the total mass of the negative electrode active material, the mass proportion of graphite is 95%, and the mass proportion of silicon oxide is 5%. 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 striped, and then dried under vacuum conditions at 120°C for 12h to form a negative electrode sheet. The height h1 of the first region of the negative electrode sheet is 100mm, and the height h2 of the second region is 7mm.

[0183] 3) Preparation of electrolyte

[0184] 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.

[0185] 4) Isolation parts

[0186] A 16 μm polyethylene film was used as a separator.

[0187] 5) Lithium-ion battery preparation

[0188] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed in the middle of the positive and negative electrode sheets to isolate the positive and negative electrodes. The bare battery cell is wound and the tabs are welded. The bare battery cell is placed in an aluminum casing, and the prepared electrolyte is injected into the dried casing. The battery is packaged, allowed to stand, formed, shaped, and capacity tested to complete the preparation of the lithium-ion battery (the thickness of the lithium-ion battery is 31 mm, the width is 237.5 mm, and the length is 117.4 mm).

[0189] The preparation methods of the batteries in Examples 2 to 17 and Comparative Examples 1 to 2 are the same as those in Example 1. The differences are detailed in Table 1.

[0190] Performance Testing

[0191] 1. Test method for whether explosion-proof valve is cracked

[0192] 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.

[0193] 2. Energy density test method

[0194] 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.

[0195] The test results of the batteries in Examples 1 to 17 and Comparative Examples 1 and 2 are shown in Table 2.

[0196] Table 2

[0197] Conclusion: It can be seen from Table 2 that the present application can reduce the probability of cracking of the pressure relief mechanism by making ba ≥ 5 μm.

[0198] It can be seen from Examples 1 to 7 that when the first active material and the second active material are of the same type, the content of the first active material or the second active material can be adjusted to make the thickness of the first region and the second region different after full filling, thereby reducing the pulling of the area of ​​the shell close to the first wall on the pressure relief mechanism and reducing the probability of cracking of the pressure relief mechanism.

[0199] It can be seen from Examples 8 to 16 that by adjusting the relative content of the silicon-based material in the first active material and the second active material, the thickness of the first region and the second region after full filling can be made different, thereby reducing the pulling of the area of ​​the shell close to the first wall on the pressure relief mechanism and reducing the probability of cracking of the pressure relief mechanism.

[0200] It can be seen from Example 17 that when the first active material and the second active material only include graphite, graphite with a high volume expansion rate can be used in the first region, and graphite with a low volume expansion rate can be used in the second region, so that the thickness of the first region and the second region after full filling are different, thereby reducing the pulling of the area of ​​the shell close to the first wall on the pressure relief mechanism and reducing the probability of cracking of the pressure relief mechanism.

[0201] 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, the housing including a first wall portion; A pressure relief mechanism, the pressure relief mechanism being provided on the first wall portion; An electrode assembly, accommodated within the housing, the electrode assembly including at least one negative electrode tab, the first wall portion being disposed along an edge facing the negative electrode tab, at least one side of the negative electrode tab being formed with an active material layer, the active material layer including a first region and a second region disposed along a first direction, the second region being closer to the first wall portion than the first region, the first direction being parallel to the thickness direction of the first wall portion, when in a fully charged state, the thickness of the second region is a μm, the thickness of the first region is b μm, and b - a ≥ 5 μm is satisfied.

2. The battery cell according to claim 1, wherein, 10 μm ≤ b - a ≤ 33 μm.

3. The battery cell according to claim 1 or 2, wherein, 210 μm ≤ a ≤ 275 μm, 195 μm ≤ b ≤ 245 μm.

4. The battery cell according to any one of claims 1-3, wherein, The first region includes a first active material, the second region includes a second active material, the mass per unit area of the first active material in the first region is w1 g / m 2 , the volume expansion rate of the first active material is v1, the mass per unit area of the second active material in the second region is w2 g / m 2 , the volume expansion rate of the second active material is v2, and under the condition that w1 = w2, v1 > v2.

5. The battery cell according to claim 4, wherein, Both the first active material and the second active material include a silicon-based material, and the mass ratio of the silicon-based material in the first active material is greater than the mass ratio of the silicon-based material in the second active material.

6. The battery cell according to claim 4, wherein, The mass ratio of the silicon-based material in the first active material is less than or equal to 30%, and the mass ratio of the silicon-based material in the second active material is less than or equal to 15%.

7. The battery cell according to claim 4 or 5, wherein, Both the first active material and the second active material include graphite, and the volume expansion rate of the graphite in the first active material is greater than the volume expansion rate of the graphite in the second active material.

8. The battery cell according to any one of claims 1-3, wherein, The types of active materials in the first region and the second region are the same. The mass per unit area of the first active material in the first region is w1 g / m 2 , and the mass per unit area of the second active material in the second region is w2 g / m 2 , where w1 > w2.

9. The battery cell according to any one of claims 4-8, wherein, The values of w1 and w2 satisfy at least one of the following conditions: 140 g / m 2 ≤ w1 ≤ 200 g / m 2 ; 112 g / m 2 ≤ w2 ≤ 180 g / m 2 .

10. The battery cell according to any one of claims 1-9, wherein, Along the first direction, the height of the first region is h1, the height of the second region is h2, and 5 ≤ h1 / h2 ≤ 30.

11. The battery cell according to any one of claims 1-10, wherein, The values of h1 and h2 satisfy at least one of the following conditions: 60 mm ≤ h1 ≤ 120 mm, optionally 80 mm ≤ h1 ≤ 100 mm; 2 mm ≤ h2 ≤ 15 mm, optionally 5 mm ≤ h2 ≤ 10 mm.

12. The battery cell according to any one of claims 1-11, wherein, The electrode assembly further includes at least one positive electrode tab, the polarity of the positive electrode tab being opposite to the polarity of the negative electrode tab, the positive electrode tab and the negative electrode tab being stacked in a second direction, the second direction intersecting the first direction.

13. The battery cell according to any one of claims 1-11, wherein, The electrode assembly further includes at least one positive electrode tab, the polarity of the positive electrode tab being opposite to the polarity of the negative electrode tab, the positive electrode tab and the negative electrode tab being wound.

14. The battery cell according to any one of claims 1-13, wherein, The pressure relief mechanism is integrally formed with the first wall portion.

15. The battery cell according to claim 14, wherein, The first wall portion includes a weak area and a non-weak area, the weak area being disposed along the edge of the pressure relief mechanism and connecting the pressure relief mechanism and the non-weak area, the weak area being configured to crack when the battery cell relieves pressure.

16. The battery cell according to claim 15, wherein, The first wall portion is provided with a scoring groove, and the first wall portion forms the weak area in the region where the scoring groove is provided.

17. The battery cell according to claim 16, wherein, The scoring groove is a groove extending along a closed trajectory.

18. The battery cell according to any one of claims 1-13, 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.

19. The battery cell according to any one of claims 1-18, 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 used for closing the opening, the first wall portion being formed on the housing body.

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

21. The battery cell according to any one of claims 12 - 20, wherein, The end cap is provided with an electrical connection part, and the electrical connection part is electrically connected to the positive electrode plate, or the electrical connection part is electrically connected to the negative electrode plate.

22. The battery cell according to any one of claims 1 - 21, wherein, The first wall portion is used to support the electrode assembly and is located below the electrode assembly.

23. The battery cell according to any one of claims 1 - 22, wherein, The outer shell further includes: a second wall portion, a third wall portion, and a fourth wall portion. The fourth wall portion and the first wall portion are oppositely arranged in the first direction, the second wall portion and the third wall portion are oppositely arranged in the second direction, and the first wall portion, the second wall portion, the fourth wall portion, and the third wall portion are connected in sequence end to end.

24. The battery cell according to claim 23, wherein, Along the first direction, the minimum distance between the first wall portion and the fourth wall portion is L1, the minimum distance between the second wall portion and the third wall portion is L2, and L1 > L2 is satisfied.

25. The battery cell according to any one of claims 1 - 24, wherein, The material of the outer shell includes at least one of aluminum, nickel-plated carbon steel, stainless steel, magnesium alloy, nickel alloy, copper alloy, and zirconium alloy.

26. The battery cell according to any one of claims 12 - 25, wherein, The positive electrode plate includes a positive current collector and a positive active material region provided on the surface of the positive current collector. The constituent material of the positive current collector includes aluminum element with a mass percentage greater than or equal to 50%.

27. A battery, wherein, It includes a battery cell according to any one of claims 1-26.

28. An electrical device, wherein, It includes a battery according to claim 27.

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