Battery cell, battery device, and electrical device

Abstract

The present disclosure provides a battery cell, a battery device, and an electrical device. The battery cell includes: an electrode assembly, the electrode assembly includes a positive electrode tab and a negative electrode tab, the positive electrode active material includes lithium-containing phosphate, and the film resistance of the positive electrode tab is 0.02 Ω - 5 Ω; the housing includes a first wall, at least one electrode terminal is provided on the first wall, the electrode terminal includes a first limiting portion, the first limiting portion is located on the side of the first wall facing the electrode assembly, along the length direction of the first wall, the length of the first wall is L1, the length of the first limiting portion is L2, and L2 ≥ 20%L1; along the width direction of the first wall, the width of the first wall is W1, the width of the first limiting portion is W2, and W2 ≥ 20%W1.

Description

[0001] Cross-reference to related applications

[0002] This application claims the priority of PCT patent application PCT / CN2025 / 071088 titled "Battery Cell, Battery Device, and Electrical Device" filed on January 7, 2025, the entire content of which is incorporated herein by reference. Technical field

[0003] The present disclosure relates to the field of batteries, and specifically, to battery cells, battery devices, and electrical devices. Background art

[0004] Lithium-ion batteries are not only applied to energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, but also widely used in electric transportation such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as military equipment and aerospace. However, there are still many problems with current battery cells in actual applications and further improvements are needed.

[0005] It should be noted that the above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art. Summary of the invention

[0006] In the first aspect of the present application, a battery cell is proposed, including: an electrode assembly, the electrode assembly includes a positive electrode tab, the positive electrode tab includes a positive electrode current collector and a positive electrode active material layer located on at least one side of the positive electrode current collector, the positive electrode active material layer includes positive electrode active material, the positive electrode active material includes lithium-containing phosphate, wherein, the film resistance of the positive electrode tab is 0.02 Ω - 5 Ω; a housing, the housing forms an accommodation space, the electrode assembly is located in the accommodation space of the housing, the housing includes a first wall, at least one electrode terminal is provided on the first wall, the electrode terminal includes a first limiting portion, the first limiting portion is located on the side of the first wall facing the electrode assembly, the first limiting portion is electrically connected to the electrode assembly, wherein, along the length direction of the first wall, the length of the first wall is L1, the length of the first limiting portion is L2, L2 ≥ 20%L1; along the width direction of the first wall, the width of the first wall is W1, the width of the first limiting portion is W2, W2 ≥ 20%W1. Thus, the heat generation of the battery cell during high-rate charge and discharge can be effectively reduced, and the rapid diffusion of the heat accumulated inside the battery cell can be accelerated, so that the battery cell can maintain a relatively stable temperature during high-rate charge and discharge, and the battery cell has excellent high-rate charge and discharge performance.

[0007] In some embodiments, 86% L1≥L2, and / or 66% W2≥W1. Thus, there is ample space on the first wall for arranging other structural components.

[0008] In some embodiments, L1-L2≥3 mm; and / or W1-W2≥3 mm. This facilitates the connection and fixation of the electrode terminal to the first wall.

[0009] In some embodiments, 120 mm ≥ L1 - L2; and / or 15 mm ≥ W1 - W2. Thus, the electrode terminal can provide better current flow capacity and a larger heat dissipation area.

[0010] In some embodiments, L1 is 100 mm to 140 mm, and L2 is 30 mm to 120 mm, thereby facilitating assembly of the electrode terminal and the first wall.

[0011] In some embodiments, W1 is 13 mm to 23 mm, and W2 is 5 mm to 15 mm, thereby facilitating assembly of the electrode terminal and the first wall.

[0012] In some embodiments, the first wall is provided with a through-hole, and the electrode terminal further includes a terminal body and a second retaining portion, wherein the terminal body connects the second retaining portion and the first retaining portion, the terminal body extends through the through-hole, and the second retaining portion is located on a side of the first wall facing away from the electrode assembly. Thus, the electrode terminal can be more securely fixed to the first wall.

[0013] In some embodiments, the sheet resistance of the positive electrode plate is 0.05Ω-1Ω, thereby further reducing the heat generated by the positive electrode plate.

[0014] In some embodiments, the positive electrode active material layer includes a conductive agent, and the mass fraction of the conductive agent in the positive electrode active material layer is 1%-5%. Thus, the heat generation of the positive electrode sheet can be further reduced by constructing a conductive network.

[0015] In some embodiments, the conductive agent includes carbon nanotubes, and the mass fraction of carbon nanotubes in the positive electrode active material layer is 0.1%-1.1%. Therefore, adding a small amount of carbon nanotubes can effectively reduce the impedance of the positive electrode sheet and reduce heat generation.

[0016] In some embodiments, the carbon nanotubes have a diameter of 1 nm to 16 nm, or alternatively, 1 nm to 8 nm. Therefore, the carbon nanotubes have excellent electronic conductivity.

[0017] In some embodiments, the conductive agent further includes carbon black. By mixing conductive agents with different morphologies and sizes, a more uniform and dense conductive network can be formed between the cathode active materials, which is beneficial to reducing the internal resistance of the cathode electrode sheet, improving the charge-discharge efficiency, and reducing heat generation.

[0018] In some embodiments, the lithium-containing phosphate satisfies the general formula: Li x1 A y1 Me a M b P 1-c X c Y z , where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, and 0.9 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5, and 0.9 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5, A includes at least one of Na, K, and Mg, Me includes at least one of Mn, Fe, Co, and Ni, M includes at least one of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce, X includes at least one of Cl, C, and N, and Y includes one or both of O and F. Thus, the lithium-containing phosphate has relatively high ionic conductivity and electronic conductivity, and the structural stability of the lithium-containing phosphate particles is relatively high, and the cycle stability during charge and discharge is relatively excellent, which is beneficial to improving the cycle performance of the battery cell.

[0019] In some embodiments, the lithium-containing phosphate includes a lithium iron phosphate material. Thus, the lithium iron phosphate material has good thermal stability and chemical stability under overcharge, short-circuit, and high-temperature conditions, and can improve the cycle performance of the battery cell.

[0020] In some embodiments, at least part of the surface of the lithium-containing phosphate has a carbon coating layer. Based on the total mass of the lithium-containing phosphate and the carbon coating layer, the mass fraction of carbon element in the cathode active material is 0.7% - 1.5%. Thus, the conductivity of the cathode active material can be improved.

[0021] In some embodiments, the powder resistivity of the cathode active material is 2 S / cm - 60 S / cm, optionally 2 S / cm - 30 S / cm. Thus, it helps to reduce the internal resistance of the cathode electrode sheet and reduce heat generation.

[0022] In some embodiments, the positive electrode active material layer further includes a lithium-rich material, and the mass fraction of the lithium-rich material in the positive electrode active material layer is 0.1% - 5%. Thus, the addition of an appropriate amount of lithium-rich material can not only compensate for the irreversible lithium ion loss in the battery cell, but also has a relatively small impact on the internal resistance of the positive electrode sheet, which is beneficial to reducing heat generation.

[0023] In some embodiments, the lithium-rich material includes at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganite, lithium tartrate, lithium citrate, lithium nickelate, and lithium ferrate. Thus, the lithium-rich material can supplement the consumption of active lithium during the first charge and store some lithium ions additionally in the negative electrode active material, improving the capacity of the battery cell.

[0024] In some embodiments, the single-sided coating weight of the positive electrode active material layer is 200 mg / 1540.25 mm 2 - 370 mg / 1540.25 mm 2 。Thus, by controlling the number of active lithium ions per unit area of the positive electrode sheet, the polarization during high-rate charge and discharge can be effectively reduced, and the polarization internal resistance can be reduced.

[0025] In some embodiments, the compaction density of the positive electrode active material layer corresponding to 100% SOC of the battery cell is 2.50 g / cm 3 - 2.80 g / cm 3 。Thus, the particles in the positive electrode active material layer are relatively closely packed, and the contact resistance between particles is small, which is beneficial to reducing the resistance of the positive electrode sheet and improving the energy density of the battery cell.

[0026] In some embodiments, in the length direction of the positive electrode current collector, the coating length of the positive electrode active material layer is 200 mm - 700 mm. Thus, the length of the positive electrode active material layer is appropriate, the electron migration path is appropriate, the polarization is weak, and the heat generation is small.

[0027] In some embodiments, along the thickness direction of the first wall, the ratio of the orthographic projection area of the first limiting portion on the first wall to the area of the first wall is 15% - 65%, optionally 20% - 60%. Thus, the area of the first limiting portion is large, which is beneficial to improving the over-current capacity and heat dissipation area of the electrode terminal and reducing heat generation.

[0028] In some embodiments, the ratio of the orthographic projection area of each first limiting portion on the first wall to the area of the first wall is 6% - 30%, optionally 8% - 28%. Thus, it helps to improve the over-current capacity of the electrode terminal.

[0029] In some embodiments, two electrode terminals are included on each of the first walls, and the two electrode terminals have the same polarity or opposite polarities. Thereby, the current density inside the battery cell can be effectively dispersed, reducing the current load on a single electrode terminal and helping to reduce the risk of local overheating.

[0030] In some embodiments, two electrode terminals with opposite polarities are included on each of the first walls. Among them, in the length direction of the battery cell, the electrode terminals with the same polarity on different first walls are arranged in a staggered manner. Optionally, the electrode terminals with the same polarity are arranged diagonally in the length direction of the battery cell. Thereby, it is convenient to electrically connect multiple battery cells.

[0031] In some embodiments, the electrode assembly has a laminated structure. Thereby, the positive electrode plate, the separator, and the negative electrode plate can make more full use of the internal space of the battery cell, reducing waste of the internal space, and helping heat to be evenly distributed inside the battery cell, which is beneficial to improving the heat dissipation efficiency and reducing the risk of local overheating.

[0032] In some embodiments, the positive current collector includes a positive electrode main body portion and at least one positive electrode tab portion, the positive electrode main body portion is connected to the positive electrode tab portion, the negative electrode plate includes a negative current collector and a negative active material layer located on at least one side of the negative current collector, the negative current collector includes a negative electrode main body portion and at least one negative electrode tab portion, and the negative electrode main body portion is connected to the negative electrode tab portion. Thereby, the positive electrode plate and the negative electrode plate can be electrically connected to the electrode terminals through the corresponding tab portions.

[0033] In some embodiments, the ratio of the number of the positive electrode tab portions to the number of the positive current collectors is 1 - 2; and / or, the ratio of the number of the negative electrode tab portions to the number of the negative current collectors is 1 - 2. Thereby, the current density on the current collector can be dispersed, helping to reduce the risk of local overheating.

[0034] In some embodiments, the positive current collector includes a positive electrode main body portion and one positive electrode tab portion. Along the width direction of the positive electrode main body portion, the total width of the positive electrode tab portion accounts for 40% - 100% of the total width of the positive electrode main body portion; and / or, the negative current collector includes a negative electrode main body portion and one negative electrode tab portion. Along the width direction of the negative electrode main body portion, the total width of the negative electrode tab portion accounts for 40% - 100% of the total width of the negative electrode main body portion. Thereby, by adopting a tab structure with a larger area, the current-carrying capacity of the tab portion can be effectively improved, alleviating the temperature rise of the battery cell during fast charging.

[0035] In some embodiments, the positive current collector includes a positive electrode main body portion and two positive electrode tab portions. Along the width direction of the positive electrode main body portion, the width of each positive electrode tab portion accounts for 15% - 45% of the total width of the positive electrode main body portion; and / or, the negative current collector includes a negative electrode main body portion and two negative electrode tab portions. Along the width direction of the negative electrode main body portion, the width of the negative electrode tab portion accounts for 15% - 45% of the total width of the negative electrode main body portion. Thus, the current-carrying capacity of the tab portions can be further improved, and the temperature rise of the battery cell during fast charging can be alleviated.

[0036] In some embodiments, it further includes: an electrolyte, and the conductivity of the electrolyte at room temperature is 10 mS / cm - 18 mS / cm. Thus, the migration rate of lithium ions in the electrolyte is relatively high, and the internal resistance of the battery cell can be further reduced.

[0037] In some embodiments, the viscosity of the electrolyte at room temperature is 1.5 mPa·s - 5.5 mPa·s. Thus, the migration rate of lithium ions in the electrolyte is relatively high.

[0038] In some embodiments, the electrolyte includes a chain carboxylic ester solvent. Thus, the chain carboxylic ester solvent can improve the solubility of the electrolyte lithium salt, thereby increasing the migration rate of lithium ions in the electrolyte.

[0039] In some embodiments, the chain carboxylic ester solvent satisfies Formula I:

[0040] Formula I, where R1 includes at least one of a hydrogen atom, a C1 - C5 alkyl group, and a C1 - C5 haloalkyl group, and R2 includes at least one of a C1 - C5 alkyl group and a C1 - C5 haloalkyl group. Thus, by using the aforementioned chain carboxylic ester solvent, the viscosity and conductivity of the electrolyte can be controlled within the aforementioned ranges.

[0041] In some embodiments, the chain carboxylic ester solvent includes Formula I-1, Formula I-2, Formula I-3, Formula I-4, Formula I-5, Formula I-6, Formula I-7, at least one of Formula I-8.

[0042] In some embodiments, the time for the battery cell to be charged from 10% SOC to 80% SOC is 5 min - 10.5 min. Thus, the battery cell has excellent fast charging performance.

[0043] In a second aspect of the present application, a battery device is proposed, including the aforementioned battery cell, and the battery device includes at least one of a battery module, a battery pack, and an energy storage device. Thus, this battery device has all the features and advantages of the aforementioned battery cell, which will not be elaborated herein.

[0044] In a third aspect of the present application, an electrical device is proposed, including the aforementioned battery cell. Thus, this electrical device has all the features and advantages of the aforementioned battery cell, which will not be elaborated herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0046] Figure 1 is a partial structural schematic diagram of the first wall according to an embodiment of the present application.

[0047] Figure 2 is a structural schematic diagram of the first wall according to an embodiment of the present application.

[0048] Figure 3 is Figure 2 an exploded view of the first wall in

[0049] Figure 4 is a top view of the first wall according to an embodiment of the present application.

[0050] Figure 5 is Figure 4 a sectional view of the first wall in along the AA' direction.

[0051] Figure 6 is a structural schematic diagram of the electrode terminal according to an embodiment of the present application.

[0052] Figure 7 is a structural schematic diagram of the first wall according to another embodiment of the present application.

[0053] Figure 8 is Figure 7 an exploded view of the first wall in

[0054] Figure 9 is a top view of the first wall according to another embodiment of the present application.

[0055] Figure 10 is Figure 9 a sectional view of the first wall in along the BB' direction.

[0056] Figure 11 is a structural schematic diagram of the electrode terminal according to another embodiment of the present application.

[0057] Figure 12Schematic diagram of the structure of the housing according to an embodiment of the present application.

[0058] Figure 13 Schematic diagram of the structure of a battery cell according to an embodiment of the present application.

[0059] Figure 14 Schematic diagram of the structure of the first wall according to another embodiment of the present application.

[0060] Figure 15 is Figure 14 Exploded view of the first wall in

[0061] Figure 16 Top view of the first wall according to another embodiment of the present application.

[0062] Figure 17 is Figure 16 Cross-sectional view of the first wall in along the CC’ direction.

[0063] Figure 18 Schematic diagram of the structure of the first wall according to another embodiment of the present application.

[0064] Figure 19 is Figure 18 Exploded view of the first wall in

[0065] Figure 20 Top view of the first wall according to another embodiment of the present application.

[0066] Figure 21 is Figure 20 Cross-sectional view of the first wall in along the DD’ direction.

[0067] Figure 22 Positive electrode tab according to an embodiment of the present application.

[0068] Figure 23 Schematic diagram of the structure of an electrode assembly according to an embodiment of the present application.

[0069] Figure 24 Schematic diagram of the structure of a positive current collector according to an embodiment of the present application.

[0070] Figure 25 Schematic diagram of the structure of a positive current collector according to another embodiment of the present application.

[0071] Figure 26 Schematic diagram of the structure of an electrode assembly prepared by a stacking process according to an embodiment of the present application.

[0072] Figure 27 Schematic diagram of the structure of an electrical device according to an embodiment of the present application.

[0073] Explanation of reference numerals:

[0074] 1 Battery cell; 2 Positive electrode plate; 3 Negative electrode plate; 4 Separator film;

[0075] 21 Positive current collector; 22 Positive active material layer; 211 Positive main body; 212 Positive electrode tab; 311 Negative main body; 312 Negative electrode tab;

[0076] 11 Housing; 111 First opening; 112 Second opening;

[0077] 12 First end cap; 121 First end plate; 122 Positive electrode terminal; 123 First insulator; 124 First seal; 125 First positioning member; 126 Second insulator; 127 Riveting block; 1211 First through hole; 1212 Liquid injection hole; 1221 First limit portion of positive electrode terminal; 1222 Terminal main body portion of positive electrode terminal; 1223 Second limit portion of positive electrode terminal; 1231 Second through hole;

[0078] 13 Second end cap; 131 Second end plate; 132 Negative electrode terminal; 133 Third insulator; 134 Second seal; 135 Second positioning member; 136 Fourth insulator; 137 Pressure relief portion; 1311 Third through hole; 1321 First limit portion of negative electrode terminal; 1322 Terminal main body portion of negative electrode terminal; 1323 Second limit portion of negative electrode terminal; 1331 Fourth through hole. Detailed implementation manners

[0079] [[ID=

[17] ]]The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the drawings, but there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where the detailed descriptions of well-known matters are omitted and the repeated descriptions of actually identical structures are omitted. This is to avoid the following descriptions from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0080] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; unless otherwise stated, the numerical values of the various parameters mentioned in the present application can be measured by various commonly used measurement methods in the art (for example, they can be tested according to the methods given in the embodiments of the present application).

[0081] The terms "comprising" and "having" and any variations thereof in the description and claims of the present application are open expressions, that is, they include the content specified in the present application, but do not exclude other aspects.

[0082] In the description of this application, all the numbers disclosed herein are approximate values, whether or not the words "about" or "approximate" are used. The numerical value of each number may have a difference of less than 10% or a reasonable difference considered by those skilled in the art, such as a difference of 1%, 2%, 3%, 4% or 5%.

[0083] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a specific range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4 and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4 and 2 - 5. In this application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" represents all the real numbers between "0 - 5" that have been fully listed herein, and "0 - 5" is just an abbreviated representation of these numerical combinations. Additionally, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0084] In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application.

[0085] In the description of this application, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. The "first feature" and "second feature" may include one or more of such features.

[0086] In the description of this application, the meaning of "plurality" is two or more.

[0087] In the description of this application, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween.

[0088] In the description of the present application, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature.

[0089] In the description of the present application, "A and / or B" may include the case of only A, the case of only B, or any one of the cases of A and B. Here, A and B are only for illustration purposes and may be any technical features connected by "and / or" in the present application.

[0090] If there is no special indication, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0091] If there is no special indication, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0092] The fast charging performance of the battery enables users to replenish a large amount of power for the device in a relatively short time, reducing the charging waiting time and improving the user experience. During the fast charging process, the chemical reaction rate inside the battery cell accelerates, and the current output by the battery cell is relatively large. Further, when the internal resistance of the battery cell is large, according to Joule's law, as the battery cell continues to work at a large current, a large amount of heat will be generated inside the battery cell, resulting in an obvious temperature increase. High temperature will accelerate the aging process of the chemical substances inside the battery cell, especially the evaporation of the electrolyte and the degradation of the positive electrode active material, leading to a rapid decline in the battery capacity and a poor cycle performance of the battery. In extreme cases, overheating may cause the battery to experience a thermal runaway phenomenon, even leading to combustion or explosion, posing a serious threat to users and the surrounding environment.

[0093] Lithium-containing phosphates have both low cost and high theoretical specific capacity, which helps to improve the energy density of individual battery cells. However, the powder resistivity of lithium-containing phosphates themselves is relatively high. Under fast charging conditions, the heat generation of the positive electrode sheet caused by the relatively high powder resistivity of the positive electrode active material powder, and the heat generation of mechanical parts caused by the existence of welds at the welding points between the electrode assembly and the electrode terminals are the main reasons for the temperature rise of the individual battery cell. In this application, by improving the main heat sources of heat generation under high-current conditions inside the individual battery cell, the internal heat generation of the individual battery cell under fast charging conditions is effectively reduced. Specifically, when the film resistance of the positive electrode sheet 2 is 0.02 Ω - 5 Ω, the conduction path of electrons in the positive electrode active material layer is shorter, and the heat generation of the positive electrode sheet under fast charging conditions is less; at the same time, when the first limiting part 1221 / 1321 of the electrode terminal is directly welded to the tab of the electrode assembly or connected through a connecting piece, when along the length direction of the first wall, the length L2 of the first limiting part 1221 / 1321 is not less than 20% of the length L1 of the first wall, and when along the width direction of the first wall, the width of the first limiting part 1221 / 1321 is not less than 20% of the width W1 of the first wall, the welding area at the welding point between the electrode assembly and the electrode terminal is relatively large, the welding quality is controllable and relatively high, so that a large amount of heat generated due to relatively large internal resistance at the weld during fast charging can be effectively reduced, and it helps to quickly dissipate the heat inside the individual battery cell. Thus, the heat generation of the individual battery cell 1 during rate charge and discharge can be effectively reduced, and the rapid diffusion of the heat accumulated inside the individual battery cell 1 is accelerated, so that the individual battery cell 1 can maintain a relatively stable temperature during rate charge and discharge, and the individual battery cell 1 has better rate charge and discharge performance. This application controls the heat generation of the chemical system of the lithium-containing phosphate battery cell and the heat generation of mechanical parts together to reduce the internal temperature rise of the battery cell and improve the cycle performance of the battery cell under fast charging.

[0094] The battery cell proposed in this application can be used in electrical equipment that uses the battery cell as a power source or various energy storage systems that use the battery cell as an energy storage element. The electrical equipment can include, but is not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0095] In the first aspect of this application, this application proposes a battery cell 1, refer to Figure 1 and Figure 23, including: an electrode assembly, the electrode assembly includes a positive electrode tab 2, the positive electrode tab 2 includes a positive current collector 21 and a positive active material layer 22 located on at least one side of the positive current collector 21, the positive active material layer 22 includes a positive active material, the positive active material includes a lithium-containing phosphate. Wherein, the sheet resistance of the positive electrode tab 2 is 0.02Ω - 5Ω; reference Figure 12 and Figure 13 , a housing 11, the housing 11 forms a receiving space, the electrode assembly is located in the receiving space of the housing 11, the housing 11 includes a first wall, at least one electrode terminal is provided on the first wall, the electrode terminal includes a first limiting portion 1221 / 1321, the first limiting portion 1221 / 1321 is located on the side of the first wall facing the electrode assembly, and the first limiting portion 1221 / 1321 is electrically connected to the electrode assembly. Wherein, along the length direction of the first wall, the length of the first wall is L1, the length of the first limiting portion 1221 / 1321 is L2, L2≥20%L1; along the width direction of the first wall, the width of the first wall is W1, the width of the first limiting portion 1221 / 1321 is W2, W2≥20%W1. Thus, the heat generation of the battery cell 1 during the rate charge and discharge process can be effectively reduced, and the rapid diffusion of the heat accumulated inside the battery cell 1 can be accelerated, so that the battery cell 1 can maintain a relatively stable temperature during the rate charge and discharge process, and the battery cell 1 has better rate charge and discharge performance.

[0096] In some embodiments, the first limiting portion 1221 / 1321 of the electrode terminal and the tab of the electrode assembly are electrically connected through a connecting piece. Thus, the welding quality and connection reliability between the electrode terminal and the electrode assembly can be significantly improved.

[0097] When the first limiting portion of the electrode terminal and the tab of the electrode assembly are electrically connected through a connecting piece, the shape and size of the connecting piece can be adjusted as needed to adapt to different distances and positions, and there are fewer welding process defects in the connecting piece, which can help to distribute the current more evenly, reduce local overheating and potential difference, and extend the service life of the battery cell.

[0098] In some embodiments, the first limiting portion 1221 / 1321 of the electrode terminal and the tab of the electrode assembly are directly electrically connected. Thus, it helps to reduce the internal structural complexity of the battery cell, helps to reduce the volume of the battery cell, and improves the energy density.

[0099] When the first limiting portion of the electrode terminal and the tab of the electrode assembly are directly electrically connected, the connecting piece is omitted, the internal structure of the battery cell is simplified, the assembly steps are reduced, and the overall manufacturing cost is reduced.

[0100] As an example, along the length direction of the first wall, the length of the first wall is L1, and the length of the first limiting portion 1221 / 1321 is L2. L2 can be 20%L1, 30%L1, 40%L1, 50%L1, 60%L1, 70%L1, 80%L1, 90%L1 or 100%L1.

[0101] When the ratio relationship between L1 and L2 is within the aforementioned range, the size of the first limiting portion is larger, and the welding area at the welding joint between the electrode assembly and the electrode terminal is larger, which can effectively reduce the large amount of heat generated due to the large internal resistance at the weld during fast charging. At the same time, the processing difficulty of the electrode terminal gradually increases with the increase in size. Those skilled in the art can make adaptive adjustments according to the actual situation and select an appropriate length of the first limiting portion.

[0102] As an example, along the width direction of the first wall, the width of the first wall is W1, and the width of the first limiting portion 1221 / 1321 is W2. W2 can be 20%W1, 30%W1, 40%W1, 50%W1, 60%W1, 70%W1, 80%W1, 90%W1 or 100%W1.

[0103] When the ratio relationship between W1 and W2 is within the aforementioned range, the size of the first limiting portion is larger, and the welding area at the welding joint between the electrode assembly and the electrode terminal is larger, which can effectively reduce the large amount of heat generated due to the large internal resistance at the weld during fast charging. At the same time, the processing difficulty of the electrode terminal is also higher. Those skilled in the art can make adaptive adjustments according to the actual situation and select an appropriate length of the first limiting portion.

[0104] As an example, the sheet resistance of the positive electrode sheet 2 can be 0.02Ω, 0.05Ω, 0.1Ω, 0.5Ω, 1Ω, 1.5Ω, 2Ω, 2.5Ω, 3Ω, 3.5Ω, 4Ω, 4.5Ω or 5Ω.

[0105] As an example, the sheet resistance of the positive electrode sheet can be obtained by the following method: After discharging the battery to 0% SOC, disassemble the electrode sheet, and clean the electrode sheet more than three times with a solvent, such as dimethyl carbonate. 20 parallel samples can be taken along the central axis of the electrode sheet. Each sample is symmetric along the central axis, and the size of each sample is 4 cm × 25 cm. Among them, the central axis can be parallel to the length direction of the electrode sheet. Use a sheet resistance tester (Yuaneng Technology, model BER2500) to test the above 20 parallel samples, and calculate the average value as the sheet resistance of the electrode sheet.

[0106] In some embodiments, the first wall can be an end cap. As an example, the first wall can include two end caps oppositely arranged along the length direction of the battery cell 1, for example, the first end cap 12 and the second end cap 13.

[0107] It should be noted that when the first wall is an end cap, the end cap is usually formed by assembling multiple mechanical parts. For the end cap, the length of the aforementioned first wall refers to the length of the mechanical part with the maximum length value among its multiple mechanical parts along the length direction of the end cap; the width of the aforementioned first wall refers to the width of the mechanical part with the maximum width value among its multiple mechanical parts along the width direction of the end cap.

[0108] As an example, the end plate is the mechanical part with the maximum length value and the maximum width value in the end cap. Therefore, the length of the aforementioned first wall is the length of the end plate, and the width of the aforementioned first wall is the width of the end plate.

[0109] In some embodiments, the first limiting portion of the electrode terminal can be the lower seat of the pole of the electrode terminal, also known as the inner pole.

[0110] Under normal circumstances, by connecting the lower seat of the pole of the electrode terminal to the tab of the electrode assembly through a welding process, the current inside the battery can be smoothly conducted to the external circuit. When there are defects such as voids and cracks at the welding interface, it will cause the welding interface to be discontinuous and the welding quality to be poor, resulting in a relatively large internal resistance at the weld. Also, since the electrode terminal is usually made of a metal or alloy material with good electrical conductivity, for the electrode terminal, the internal resistance at the welding part between the electrode terminal and the mechanical part has a much greater impact on the resistance value of the electrode terminal than the material resistance of the electrode terminal itself. Therefore, when the size of the lower seat of the pole meets the aforementioned requirements, the quality of the welding part can be effectively improved, good electrical contact between the electrode terminal and the electrode assembly can be achieved, and the overcurrent heat generation at the electrode terminal can be significantly improved.

[0111] It should be noted that when the first limiting portion of the electrode terminal is an irregular shape with multiple length values and / or width values, along the length direction of the first wall, the length W2 of the first limiting portion 1221 / 1321 is the minimum value among the multiple length values; along the width direction of the first wall, the width W2 of the first limiting portion 1221 / 1321 is the minimum value among the multiple width values.

[0112] It can be understood that the size of the resistance is closely related to the geometric shape of the mechanical part. According to Ohm's law and the basic formula of resistance, the resistance R can be calculated by the following formula: R = ρ×L / A, where: R is the resistance (unit: ohm, Ω); ρ is the resistivity of the mechanical part material (unit: ohm·meter, Ω·m); L is the length of the mechanical part (unit: meter, m); A is the cross-sectional area of the mechanical part (unit: square meter, m²).

[0113] For the first limiting part, L in the foregoing resistance R calculation formula is the thickness of the first limiting part, and A is the cross-sectional area of the first limiting part. It can be seen from the foregoing formula that the smaller the cross-sectional area of the first limiting part, the greater the resistance of the first limiting part. Also, since the cross-sectional area of the first limiting part is positively correlated with the length and width of the first limiting part. Therefore, by controlling the minimum values of the length and width of the first limiting part of the electrode terminal, the cross-sectional area of the electrode terminal can be adjusted, so that the electrode terminal has a lower resistance, which helps to improve the welding quality between the lower seat of the pole column of the electrode terminal and the ear of the electrode assembly, and significantly improves the heat generation due to overcurrent at the electrode terminal.

[0114] In some embodiments, 86%L1≥L2, and / or, 66%W2≥W1. Thus, there is relatively abundant space on the first wall for arranging other structural members.

[0115] In some embodiments, L1 - L2≥3mm; and / or, W1 - W2≥3mm. Thus, it is convenient to assemble the electrode terminal with the first wall to achieve a relatively firm connection and fixation.

[0116] In some embodiments, 120mm≥L1 - L2; and / or, 15mm≥W1 - W2. Thus, the electrode terminal can provide better overcurrent capacity and a larger heat dissipation area.

[0117] In some embodiments, L1 is 100mm - 140mm, and L2 is 30mm - 120mm. Thus, it is convenient to assemble the electrode terminal with the first wall.

[0118] As an example, L1 can be 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm or 140mm.

[0119] As an example, L2 can be 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm or 120mm.

[0120] In some embodiments, W1 is 13mm - 23mm, and W2 is 5mm - 15mm. Thus, it is convenient to assemble the electrode terminal with the first wall.

[0121] As an example, W1 can be 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm or 23mm.

[0122] As an example, W2 can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm or 15mm.

[0123] As an example, the electrode terminals include a positive electrode terminal 122 and a negative electrode terminal 132.

[0124] As an example, the first wall includes a first end cap 12 and a second end cap 13.

[0125] In some embodiments, referring to Figure 13 , the battery cell includes a housing 11, a first end cap 12 and a second end cap 13. The housing, the first end cap and the second end cap define a receiving cavity. The first end cap includes a first end plate 121 and at least one positive electrode terminal 122. The positive electrode main body is electrically connected to the positive electrode terminal 122 through the positive electrode tab; and / or, the second end cap includes a second end plate 131 and at least one negative electrode terminal 132. The negative electrode main body is electrically connected to the negative electrode terminal 132 through the negative electrode tab.

[0126] Specifically, referring to Figure 12 , the two ends of the housing 11 in its length direction have a first opening 111 and a second opening 112. The length direction of the housing 11 is the same as the length direction of the positive current collector. The first end cap 12 is adapted to cover the first opening 111, and the second end cap 13 is adapted to cover the second opening 112 to isolate the internal environment of the battery cell from the external environment. The housing, the first end cap and the second end cap define a receiving cavity, and the electrode assembly is disposed in the receiving cavity. The shapes of the first end cap and the second end cap can be adapted to the shape of the housing to cooperate with the housing. The first end cap and the second end cap can be respectively independently made of a material with a certain hardness and strength (such as aluminum alloy), so that the first end cap and the second end cap have higher strength. Thus, when the first end cap and the second end cap are squeezed, the deformation of the first end cap and the second end cap is reduced, and the safety performance of the battery cell is improved.

[0127] In some embodiments, the first end cap, the second end cap, and the housing can be independent components.

[0128] In some embodiments, the first end cap, the second end cap, and the housing are integrated. Specifically, the first end cap, the second end cap, and the housing can form a common connection surface before other components are put into the housing. When it is necessary to encapsulate the interior of the housing, the first end cap is then made to cover the first opening of the housing, and the second end cap is made to cover the second opening of the housing.

[0129] In some embodiments, referring to Figures 2 - 6, the first end cap 12 includes a first end plate 121 and a positive electrode terminal 122. The positive electrode terminal 122 is disposed on a side of the first end plate 121 close to the electrode assembly. A first through hole 1211 is provided on the first end plate 121. A first insulating member 123 is disposed between the first end plate 121 and the positive electrode terminal 122. The first insulating member 123 is adapted to isolate the electrical connection components in the housing from the first end plate 121 to reduce the risk of short circuit. A second through hole 1231 is provided on the first insulating member 123. The positive electrode terminal 122 sequentially passes through the second through hole 1231 and the first through hole 1211. On a side of the first end plate 121 away from the electrode assembly, a first sealing member 124, a first positioning member 125, a second insulating member 126 and a riveting block 127 are sequentially disposed. The riveting block is adapted to fix the positive electrode terminal 122 on the first end plate 121.

[0130] In some embodiments, refer to Figures 7 - 11 , the second end cap 13 includes a second end plate 131 and a negative electrode terminal 132. The negative electrode terminal 132 is disposed on a side of the second end plate 131 close to the electrode assembly. A third through hole 1311 is provided on the second end plate 131. A third insulating member 133 is disposed between the second end plate 131 and the negative electrode terminal 132. The third insulating member 133 is adapted to isolate the electrical connection components in the housing from the second end plate 131 to reduce the risk of short circuit. A fourth through hole 1331 is provided on the third insulating member 133. The negative electrode terminal 132 sequentially passes through the fourth through hole 1331 and the third through hole 1311. On a side of the second end plate 131 away from the electrode assembly, a second sealing member 134, a second positioning member 135, a fourth insulating member 136 and the riveting block 127 are sequentially disposed. The riveting block 127 is adapted to fix the negative electrode terminal 132 on the second end plate 131.

[0131] As an example, the first insulating member 123, the second insulating member 126, the third insulating member 133 and the fourth insulating member 136 may be independently plastics, rubbers, etc.

[0132] In some embodiments, refer to Figures 2 - 6 , a liquid injection hole 1212 is provided on the first end plate 121. The liquid injection hole 1212 can be used to inject electrolyte; refer to Figures 7 - 11 , a pressure relief portion 137 is provided on the second end plate 131. When the pressure inside the housing exceeds a threshold value, the pressure relief portion 137 can release the pressure inside the housing.

[0133] As an example, the pressure relief part 137 and the second end plate 131 are two separate components, which are separately formed and then installed together. The pressure relief part 137 can be components such as an explosion-proof film, an explosion-proof valve, a safety valve, etc. The pressure relief part 137 can be installed on the second end plate 131 by means of bonding, welding, etc. When the internal pressure of the battery cell reaches the threshold value, the pressure relief part 137 opens at least part of the pressure relief holes, and the discharge cut-off inside the battery cell is discharged through the pressure relief holes to relieve the internal pressure of the battery cell.

[0134] In some embodiments, the first end cap 12 is provided with through holes, such as Figure 3 the first through hole 1211 and the second through hole 1231 in Figure 5 and Figure 6 Further, referring to

[0135] the positive electrode terminal further includes a terminal main body portion 1222 and a second limiting portion 1223. The terminal main body portion 1222 connects the second limiting portion 1223 and the first limiting portion 1221. The terminal main body portion 1222 sequentially passes through the second through hole 1231 and the first through hole 1211. The second limiting portion 1223 is located on the side of the first end cap 12 away from the electrode assembly. Thus, the positive electrode terminal can be relatively firmly fixed on the first end cap.

[0135] In some embodiments, the second end cap 13 is provided with through holes, such as Figure 8 the third through hole 1311 and the fourth through hole 1331 in Figure 10 and Figure 11 Further, referring to

[0136] the negative electrode terminal further includes a terminal main body portion 1322 and a second limiting portion 1323. The terminal main body portion 1322 connects the second limiting portion 1323 and the first limiting portion 1321. The terminal main body portion 1322 sequentially passes through the fourth through hole 1331 and the third through hole 1311. The second limiting portion 1323 is located on the side of the second end cap 13 away from the electrode assembly. Thus, the negative electrode terminal can be relatively firmly fixed on the second end cap.

[0136] In some embodiments, referring to Figure 1 along the thickness direction of the first wall, the ratio of the orthographic projection area of the first limiting portion 1221 / 1321 on the first wall to the area of the first wall is 15%-65%, optionally 20%-60%. Thus, the area of the first limiting portion is relatively large, which is beneficial to improving the current-carrying capacity and heat dissipation area of the electrode terminal and reducing heat generation.

[0137] As an example, along the thickness direction of the first wall, the ratio of the orthographic projection area of the first limiting portion 1221 / 1321 on the first wall to the area of the first wall is 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or 65%.

[0138] It should be noted that referring to Figure 1 , the orthographic projection area of the first limiting portion on the first wall refers to the projection area of the region formed by the outer edge contours of the first limiting portion. When there are multiple first limiting portions on the first wall, the orthographic projection area of the first limiting portion on the first wall refers to the sum of the projection areas of the regions formed by the outer edge contours of the multiple first limiting portions.

[0139] In some embodiments, when there are multiple first limiting portions on the first wall, the ratio of the orthographic projection area of each first limiting portion 1221 / 1321 on the first wall to the area of the first wall is 6% - 30%, optionally 8% - 28%. Thereby, it helps to improve the overcurrent capacity of the electrode terminal.

[0140] As an example, the ratio of the orthographic projection area of each first limiting portion 1221 / 1321 on the first wall to the area of the first wall can be 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28% or 30%.

[0141] In some embodiments, each first wall includes two of the electrode terminals, and the polarities of the two electrode terminals are the same.

[0142] In some embodiments, referring to Figure 15 and Figure 19 , each first wall includes two of the electrode terminals, and the polarities of the two electrode terminals are opposite. Thereby, the current density inside the battery cell 1 can be effectively dispersed, so as to reduce the current load on a single electrode terminal, relieve the polarization unevenness inside the battery cell, and reduce the risk of local overheating.

[0143] It should be noted that when each first wall includes multiple electrode terminals with the same polarity, the length L2 of the aforementioned first limiting portion is the sum of the lengths of the first limiting portions of the multiple electrode terminals.

[0144] It should be noted that when each first wall includes at least two electrode terminals with opposite polarities, the length L2 of the aforementioned first limiting portion refers to the length or the sum of the lengths of the first limiting portions of the electrode terminals with the same polarity on this first wall.

[0145] In some embodiments, each first wall includes two electrode terminals with opposite polarities, wherein, along the length direction of the battery cell 1, the electrode terminals with the same polarity on different first walls are arranged in a staggered manner, optionally, the electrode terminals with the same polarity are arranged diagonally along the length direction of the battery cell 1. Thereby, it is convenient to electrically connect multiple battery cells 1, and it helps to relieve the polarization unevenness inside the battery cell.

[0146] In some embodiments, the first cover plate 12 includes one of the positive electrode terminals 122 and one of the negative electrode terminals 132; and / or, the second cover plate 13 includes one of the positive electrode terminals 122 and one of the negative electrode terminals 132.

[0147] Specifically, referring to Figures 14 - 17 , the first end cover 12 includes a first end plate 121. The first end plate 121 includes one of the positive electrode terminals 122 and one of the negative electrode terminals 132. Two first through holes are provided on the first end cover. A first insulating member 123 is provided between the first end cover and the positive electrode terminal 122 and the negative electrode terminal 132. Two second through holes 1231 are provided on the first insulating member 123. The positive electrode terminal 122 sequentially passes through the correspondingly provided second through hole 1231 and the first through hole 1211. The negative electrode terminal 132 sequentially passes through the correspondingly provided second through hole 1231 and the first through hole 1211. On the side of the first end plate 121 away from the electrode assembly, a first sealing member 124, a first positioning member 125, a second insulating member 126, and a riveting block 127 are sequentially provided.

[0148] Specifically, referring to Figures 18 - 21 , the second end cover 13 includes a second end plate 131. The second end plate 131 includes one of the positive electrode terminals 122 and one of the negative electrode terminals 132. Two third through holes 1311 are provided on the second end plate 131. A second insulating member 133 is provided between the second end plate 131 and the negative electrode terminal 132 and between the second end plate 131 and the positive electrode terminal 122. Two fourth through holes 1331 are provided on the third insulating member 133. The positive electrode terminal 122 sequentially passes through the correspondingly provided fourth through hole 1331 and the third through hole 1311. The negative electrode terminal 132 sequentially passes through the correspondingly provided fourth through hole 1331 and the third through hole 1311. On the side of the second end plate 131 away from the electrode assembly, a second sealing member 134, a second positioning member 135, a fourth insulating member 136, and the riveting block 127 are sequentially provided.

[0149] Further, when the first end cover 12 includes a first end plate 121, the first end plate 121 includes one of the positive electrode terminals 122 and one of the negative electrode terminals 132, and the second end cover 13 includes a second end plate 131, the second end plate 131 includes one of the positive electrode terminals 122 and one of the negative electrode terminals 132, the electrode assembly includes four tab ears. Specifically, referring to Figure 25, the positive current collector may have two positive electrode tabs 212 extending from the opposite side along the length direction of the current collector. Similarly, the negative current collector may have two negative electrode tabs 312 extending from the opposite side along the length direction of the current collector. After the positive electrode sheet and the negative electrode sheet are stacked to form an electrode assembly, each of the opposite sides along the length direction of the electrode assembly has an un-overlapped positive electrode tab and a negative electrode tab, so that the electrode tabs on the same side can be electrically connected to the corresponding positive electrode terminal 122 and negative electrode terminal 132 on the first wall respectively. Thus, the over-current capacity of the battery cell can be improved, the temperature rise inside the battery cell can be reduced, especially the temperature rise in the length direction of the battery cell can be reduced. At the same time, the wiring inside the battery cell can be reduced, and the assembly efficiency is relatively high.

[0150] In some embodiments, when multiple electrode terminals are provided on one end plate, the sizes of the multiple electrode terminals may be the same. For example, the sizes of the first limiting portions of the multiple electrode terminals may be the same. Thus, the over-current heat conduction capabilities of different electrode terminals are relatively close, and local overheating caused by excessive resistance of a certain electrode terminal can be effectively reduced.

[0151] In some embodiments, the sizes of the electrode terminals of the same polarity may be the same. For example, the sizes of the first limiting portions of the electrode terminals of the same polarity may be the same. Thus, the over-current heat conduction capabilities of the electrode terminals of the same polarity are relatively close, and local overheating caused by excessive resistance of a certain electrode terminal can be effectively reduced.

[0152] In some embodiments, referring to Figure 23 , the electrode assembly is of a stacked structure. Thus, the positive electrode sheet 2, the separator 4, and the negative electrode sheet 3 can make more full use of the internal space of the battery cell 1, reduce the waste of the internal space, and contribute to the uniform distribution of heat inside the battery cell 1, which is beneficial to improving the heat dissipation efficiency and reducing the risk of local overheating.

[0153] In some embodiments, the time for the battery cell 1 to be charged from 10% SOC to 80% SOC is 5 min - 10.5 min. Thus, the battery cell 1 has relatively good fast charging performance.

[0154] Taking the electrical device as an automobile as an example, in the actual use scenario, for an automobile, the state of charge (SOC) of its battery is usually between 10% and 80%. Thus, when the charging time of the battery within this SOC range is short, the waiting time of the user for charging can be reduced, greatly improving the user experience.

[0155] Under normal circumstances, a battery cell includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charging and discharging process of the battery, active ions are inserted into and extracted from between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. The separator is disposed between the positive electrode plate and the negative electrode plate, mainly to prevent short circuit between the positive and negative electrodes, and at the same time allows ions to pass through.

[0156] [Positive electrode plate]

[0157] In some embodiments, the positive electrode active material layer 22 includes a conductive agent, and the mass fraction of the conductive agent in the positive electrode active material layer 22 is 1% - 5%. Thus, by adding the conductive agent, a conductive network can be constructed, effectively connecting the positive electrode active material particles, shortening the electron conduction path, improving the overcurrent internal resistance of the electrode plate, and further reducing the heat generation of the positive electrode plate.

[0158] As an example, the mass fraction of the conductive agent in the positive electrode active material layer 22 can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

[0159] In some embodiments, the conductive agent includes carbon nanotubes, and the mass fraction of carbon nanotubes in the positive electrode active material layer is 0.1% - 1.1%. Thus, by adding a small amount of carbon nanotubes, the impedance of the positive electrode plate 2 can be effectively reduced, and the heat generation can be reduced.

[0160] As an example, the mass fraction of the carbon nanotubes in the positive electrode active material layer 22 can be 0.1%, 0.3%, 0.5%, 0.7% or 1.1%.

[0161] Carbon nanotubes have high electron conduction ability, can form a complex three-dimensional conductive network, improve the interfacial contact between the positive electrode active material particles and the current collector, significantly reduce the sheet resistance of the positive electrode plate, and contribute to improving the rate charge and discharge performance of the battery.

[0162] In some embodiments, the diameter of the carbon nanotubes is 1nm - 16nm; optionally, 1nm - 8nm. Thus, the carbon nanotubes have better electron conductivity.

[0163] As an example, the diameter of the carbon nanotubes is 1nm, 4nm, 6nm, 8nm, 10nm, 12nm, 14nm or 16nm.

[0164] It should be noted that the diameter of the aforementioned carbon nanotubes refers to the sum of the inner diameter and the wall thickness of the carbon nanotubes.

[0165] As an example, the diameter of the carbon nanotubes can be measured by the following method: Use a scanning electron microscope (SEM), a transmission electron microscope (TEM), or a spatially resolved fluorescence microscope (SRM) to observe the morphology of the carbon nanotubes and measure the diameter.

[0166] In some embodiments, the conductive agent further includes carbon black. By mixing conductive agents with different morphologies and sizes, a more uniform and dense conductive network can be formed between the positive electrode active materials, which is beneficial to reducing the sheet resistance of the positive electrode sheet 2, improving the charge-discharge efficiency, and reducing heat generation.

[0167] It should be noted that the foregoing addition of an appropriate amount of conductive agent to regulate the sheet resistance of the positive electrode sheet is only exemplary. In this application, there is no particular limitation on the method of regulating the sheet resistance of the positive electrode sheet, as long as the sheet resistance range can meet the foregoing requirements. For example, the conductivity of the positive electrode active material can be improved, such as carbon coating the positive electrode active material to reduce the sheet resistance; or, the particle size distribution of the positive electrode active material can be regulated, so that particles with smaller and uniform particle sizes form closer contacts to reduce the sheet resistance; or, the foregoing conductive agent can be used to establish a good conductive network between the positive electrode active materials to reduce the sheet resistance; or, the coating process can be improved to increase the coating thickness uniformity of the positive electrode active material layer and reduce the resistance change caused by local over-thickness or under-thickness to reduce the sheet resistance. For another example, the pressing process can be improved: appropriately increasing the pressing pressure can reduce the distance between the active material particles, improve the electron conduction path, and reduce the sheet resistance. For another example, the binder composition affects the combination of the active material and the current collector and ion conduction. Selecting a suitable binder can also adjust the resistance. When polyvinylidene fluoride (PVDF) is used as the binder, its dosage and molecular weight will affect the sheet resistance. In the actual process of preparing the electrode sheet, the sheet resistance can also be adjusted by introducing different dosages or using PVDF with different molecular weights.

[0168] In some embodiments, the lithium-containing phosphate satisfies the general formula: Li x1 A y1 Me a M b P 1-c X c Y z, where \(0.5\leq x1\leq1.3\), \(0\leq y1\leq1.3\), and \(0.9\leq x1 + y1\leq1.3\), \(0.9\leq a\leq1.5\), \(0\leq b\leq0.5\), and \(0.9\leq a + b\leq1.5\), \(0\leq c\leq0.5\), \(3\leq z\leq5\), \(A\) includes at least one of \(Na\), \(K\), and \(Mg\), \(Me\) includes at least one of \(Mn\), \(Fe\), \(Co\), and \(Ni\), \(M\) includes at least one of \(B\), \(Mg\), \(Al\), \(Si\), \(P\), \(S\), \(Ca\), \(Sc\), \(Ti\), \(V\), \(Cr\), \(Cu\), \(Zn\), \(Sr\), \(Y\), \(Zr\), \(Nb\), \(Mo\), \(Cd\), \(Sn\), \(Sb\), \(Te\), \(Ba\), \(Ta\), \(W\), \(Yb\), \(La\), and \(Ce\), \(X\) includes at least one of \(Cl\), \(C\), and \(N\), and \(Y\) includes one or both of \(O\) and \(F\). Thus, the ionic conductivity and electronic conductivity of the lithium-containing phosphate are relatively high, and the structural stability of the lithium-containing phosphate particles is relatively high, and the cycle stability during charge and discharge is excellent, which is beneficial to improving the cycle performance of the battery cell.

[0169] During the charge and discharge process of the battery, the insertion and extraction and consumption of Li will occur, and the molar content of Li is different when the battery is discharged to different states. In the list of the positive electrode active materials in the present application, the molar content of Li is the initial state of the material, that is, the state before feeding. When the positive electrode active material is applied to the battery system, after the charge and discharge cycle, the molar content of Li will change.

[0170] In the list of the positive electrode active materials for lithium-ion batteries in the present application, the molar content of O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will show fluctuations.

[0171] In some embodiments, the lithium-containing phosphate includes a lithium iron phosphate material. Thus, the lithium iron phosphate material has good thermal stability and chemical stability under overcharge, short circuit, and high temperature conditions, and can improve the cycle performance of the battery cell 1.

[0172] In some embodiments, at least a part of the surface of the lithium-containing phosphate has a carbon coating layer. Based on the total mass of the lithium-containing phosphate and the carbon coating layer, the mass fraction of carbon element in the positive electrode active material is 0.7% - 1.5%. Thus, the carbon coating layer can effectively alleviate the poor electronic conductivity of the lithium-containing phosphate, reduce the resistance of the positive electrode active material in the positive electrode active material layer, and improve the specific capacity utilization of the positive electrode active material.

[0173] As an example, based on the total mass of the lithium-containing phosphate and the carbon coating layer, the mass fraction of carbon element in the positive electrode active material can be 0.7%, 0.9%, 1.1%, 1.3%, or 1.5%.

[0174] As an example, based on the total mass of the lithium-containing phosphate and the carbon coating layer, the mass fraction of the carbon coating layer can be obtained by the following method: Turn on all power switches of the carbon and sulfur analyzer, press the "zeroing" button, open the oxygen valve of the carbon and sulfur analyzer, and adjust the oxygen pressure to 0.02 - 0.04 MPa. Open the "front oxygen" and "rear control", and adjust the flow meter to control at about 100 L / h. Add silicon molybdenum powder (about 0.3 g), weighed sample (250 mg), tin granules (0.3 g), and pure iron (1 g) into the crucible in sequence, and close the crucible. Click the "test" button to start the test. After the test is completed, the test result will be automatically displayed, and record this result as the C content.

[0175] In some embodiments, the powder resistivity of the positive electrode active material is 2 S / cm - 60 S / cm, optionally 2 S / cm - 30 S / cm. Thus, it helps to reduce the internal resistance of the positive electrode sheet 2 and reduce heat generation.

[0176] As an example, the powder resistivity of the positive electrode active material can be obtained by the following method: For example, according to the test standard GB / T30835 - 2014, use a PRCD1100 powder resistivity meter for testing.

[0177] In some embodiments, the positive electrode active material layer 22 further includes a lithium-rich material, and the mass fraction of the lithium-rich material in the positive electrode active material layer 22 is 0.1% - 5%. Thus, the addition of an appropriate amount of lithium-rich material can not only compensate for the irreversible loss of lithium ions in the battery cell 1, but also has a relatively small impact on the internal resistance of the positive electrode sheet 2, which is beneficial to reducing heat generation.

[0178] As an example, the mass fraction of the lithium-rich material in the positive electrode active material layer 22 can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

[0179] When the mass fraction of the lithium-rich material in the positive electrode active material layer 22 is within the aforementioned range, it can not only better supplement the loss of active lithium ions, but also help the positive electrode active material layer to carry more positive electrode active material, improving the energy density of the battery cell.

[0180] When the battery is charged for the first time, a SEI film will form on the surface of the negative electrode active material, and the rupture and recombination of the SEI during the charge-discharge cycle will both cause irreversible consumption of lithium ions, resulting in a reduction in the first-cycle efficiency and capacity loss of the battery cell. By adding a lithium-rich material, this part of the lost lithium can be pre-supplemented during the battery preparation process, reducing or eliminating the capacity attenuation caused by lithium loss and extending the cycle life of the battery.

[0181] In some embodiments, the lithium-rich material includes at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganite, lithium tartrate, trilithium citrate, lithium nickelate, and lithium ferrate. Thus, the lithium-rich material can supplement the consumption of active lithium during the first charge and store some lithium ions additionally in the negative electrode active material, improving the capacity performance of the battery cell 1.

[0182] In some embodiments, the single-sided coating weight of the positive electrode active material layer 22 is 200 mg / 1540.25 mm 2 -370 mg / 1540.25 mm 2 . Thus, by controlling the number of active lithium ions per unit area of the positive electrode plate 2, the polarization during high-rate charge and discharge can be effectively reduced, and the polarization internal resistance can be decreased.

[0183] As an example, the single-sided coating weight of the positive electrode active material layer can be 200 mg / 1540.25 mm 2 、210 mg / 1540.25 mm 2 、220 mg / 1540.25 mm 2 、230 mg / 1540.25 mm 2 、240 mg / 1540.25 mm 2 、250 mg / 1540.25 mm 2 、260 mg / 1540.25 mm 2 、270 mg / 1540.25 mm 2 、280 mg / 1540.25 mm 2 、290 mg / 1540.25 mm 2 、300 mg / 1540.25 mm 2 、310 mg / 1540.25 mm 2 、320 mg / 1540.25 mm 2 、330 mg / 1540.25 mm 2 、340 mg / 1540.25 mm 2 、350 mg / 1540.25 mm 2 、360 mg / 1540.25 mm 2 or 370 mg / 1540.25 mm 2 .

[0184] As an example, the single-sided coating weight of the positive electrode active material layer can be obtained by the following method: disassemble the positive electrode sheet from the battery cell, take the single-sided coated positive electrode sheet (if it is a double-sided coated positive electrode sheet, the positive electrode active material layer on one side can be wiped off first), punch it into small circular pieces with an area of S1, weigh it, and record it as M1. Then wipe off the positive electrode active material layer of the above-mentioned weighed positive electrode sheet, weigh the weight of the positive electrode current collector, and record it as M0. The single-sided coating weight of the positive electrode active material layer = (M1 - M0) / S1.

[0185] In some embodiments, the tap density of the positive electrode active material layer 22 corresponding to the battery cell 1 at 100% SOC is 2.50 g / cm 3 -2.80 g / cm 3 . Thus, the particles in the positive electrode active material layer 22 are stacked relatively tightly, and the contact resistance between particles is small, which is beneficial to reducing the resistance of the positive electrode sheet 2 and improving the energy density of the battery cell 1.

[0186] As an example, the tap density of the positive electrode active material layer corresponding to the battery cell 1 at 100% SOC can be 2.50 g / cm 3 , 2.55 g / cm 3 , 2.60 g / cm 3 , 2.65 g / cm 3 , 2.70 g / cm 3 , 2.75 g / cm 3 or 2.80 g / cm 3 .

[0187] When the tap density of the positive electrode active material layer is within the aforementioned range, the particles in the positive electrode active material layer are stacked relatively tightly, and the positive electrode sheet has both a high energy density and a low film resistance.

[0188] As an example, the tap density of the positive electrode active material layer corresponding to the battery cell at 100% SOC can be obtained by the following method: charge the battery cell at a constant current of 1 / 3C to 3.8V, charge it at a constant voltage of 3.8V to 0.05C, disassemble the positive electrode sheet from the battery cell, for example, take the single-sided coated positive electrode sheet (if it is a double-sided coated sheet, the positive electrode active material layer on one side can be wiped off first), punch it into small circular pieces with an area of S1, weigh it, and record it as M1, measure its thickness H1. Then wipe off the positive electrode active material layer of the above-mentioned weighed positive electrode sheet, weigh the weight of the positive electrode current collector, and record it as M0, measure its thickness H0. The single-sided coating weight of the positive electrode active material layer = (M1 - M0) / S1, the thickness of the positive electrode active material layer = H1 - H0, and the tap density of the positive electrode active material layer = the single-sided coating weight of the positive electrode active material layer / the thickness of the positive electrode active material layer.

[0189] In some embodiments, referring to Figure 22 , in the length direction of the positive electrode current collector 21, the coating length of the positive electrode active material layer 22 is 200 mm - 700 mm. Thus, the length of the positive electrode active material layer 22 is appropriate, the electron migration path is appropriate, the polarization is weak, and the heat generation is small.

[0190] As an example, in the length direction of the positive electrode current collector 21, the coating length of the positive electrode active material layer 22 can be 200 mm, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm or 700 mm.

[0191] When When the coating length of the positive electrode active material layer 22 is 300 mm - 600 mm, the battery cell 1 can be in a strip structure. Arranging and combining such strip-shaped battery cells directly forms a battery pack, eliminating the intermediate module structure. Thus, it is convenient to closely arrange multiple battery cells 1 in the battery device, reducing the redundant gaps and unnecessary structural parts, thereby improving the space utilization rate of the battery device and increasing the energy density of the battery device.

[0192] In some embodiments, referring to Figure 24 , the positive electrode current collector 21 includes a positive electrode main body portion 211 and at least one positive electrode tab 212, and the positive electrode main body portion 211 is connected to the positive electrode tab 212. Thus, the positive electrode plate 2 can be electrically connected to the electrode terminal through the corresponding tab.

[0193] In some embodiments, the electrode terminal and the positive electrode tab can be electrically connected through a connecting piece. Specifically, the first limiting portion 1221 of the electrode terminal can be electrically connected to the positive electrode tab through the connecting piece. Thus, the welding quality and connection reliability between the electrode terminal and the tab can be significantly improved.

[0194] When realizing the electrical connection between the electrode terminal and the positive electrode tab through the connecting piece, the shape and size of the connecting piece can be adjusted as needed to adapt to different distances and positions. Moreover, there are fewer welding process defects in the connecting piece, which can help distribute the current more evenly, reduce local overheating and potential difference, and improve the fast charging performance of the battery.

[0195] In some embodiments, the electrode terminal and the positive electrode tab can be directly electrically connected. Specifically, the first limiting portion 1221 of the electrode terminal can be directly electrically connected to the positive electrode tab. Thus, it helps to reduce the structural complexity inside the battery cell, reduce the volume of the battery cell, and increase the energy density.

[0196] When there is a direct electrical connection between the electrode terminal and the positive electrode tab, the connecting piece is omitted, simplifying the internal structure of the battery cell, reducing the assembly steps, and lowering the overall manufacturing cost.

[0197] In some embodiments, the ratio of the number of the positive electrode tabs 212 to the number of the positive current collectors 21 is 1 - 2. Thereby, the current density on the current collector can be dispersed, which helps to reduce the risk of local overheating.

[0198] The electrical connection is achieved through the tab and the pole column, so as to output the current inside the battery cell to the external circuit. The ratio of the number of the positive electrode tabs 212 to the number of the positive current collectors 21 corresponds to the number of positive electrode tabs on each positive current collector. The number of positive electrode tabs on a single positive current collector corresponds to the number of electrode terminals on the first wall. Thus, through the design of multiple tabs matching the design of multiple electrode terminals, multiple transfer paths of electrons in the electrode assembly can be realized, shortening the electron transfer path, reducing the internal resistance of the battery cell, and reducing heat generation.

[0199] As an example, refer to Figure 25 , the positive current collector includes the positive main body portion 211 and multiple positive electrode tabs 212. At least two positive electrode tabs 212 are located on opposite sides of the positive main body portion 211. Similarly, the negative current collector may include the negative main body portion and multiple negative electrode tabs, and at least two negative electrode tabs are located on opposite sides of the negative main body portion. Thereby, a more uniform heat distribution can be provided, reducing the deformation of the tabs caused by excessive force on one side.

[0200] In some embodiments, refer to Figure 24 , when the positive current collector includes the positive main body portion 211 and one positive electrode tab 212, along the width direction of the positive main body portion 211, the total width of the positive electrode tab 212 accounts for 40% - 100% of the total width of the positive main body portion 211. Thereby, by adopting a tab structure with a larger area, the current-carrying capacity of the tab can be effectively improved, alleviating the temperature rise of the battery cell 1 during fast charging.

[0201] In some embodiments, refer to Figure 25 , when the positive current collector includes the positive main body portion 211 and two positive electrode tabs 212, along the width direction of the positive main body portion 211, the width of each positive electrode tab 212 accounts for 15% - 45% of the total width of the positive main body portion 211, and the total width of the positive electrode tabs 212 accounts for 30% - 90% of the total width of the positive main body portion 211. Thereby, by adopting a tab structure with a larger area, the current-carrying capacity of the tab can be effectively improved, alleviating the temperature rise of the battery cell 1 during fast charging.

[0202] When a battery cell undergoes high-rate charge and discharge, both the current and voltage inside the battery cell will increase correspondingly, and the current passing through the tab increases. A larger positive tab area means lower resistance. On the one hand, according to Ohm's law, at the same voltage, a tab with a larger area can carry a higher current, that is, it has a stronger overcurrent capacity. On the other hand, when the resistance of the tab is small, the heat generated due to resistance loss after the current passes through the tab can be reduced, the heat generation of the battery under high current is reduced, and the heat dissipation efficiency of the battery is indirectly improved.

[0203] In some specific embodiments, referring to Figure 24 , the positive electrode plate used is rectangular. At this time, one of the short sides of the two short sides on both sides of the positive current collector has a positive tab portion 212 extending along the length direction of the positive current collector. The width of the positive tab portion is W3. At this time, the total width W4 of the positive tab portion is equal to the width W3 of the positive tab portion, and the total width V1 of the positive electrode main body portion is the width of the positive current collector. Similarly, its corresponding negative current collector can also have a similar structure, which will not be elaborated here.

[0204] In some specific embodiments, referring to Figure 25 , the positive electrode plate used is rectangular. At this time, each of the two short sides on both sides of the positive current collector has a positive tab portion 212 extending along the length direction of the positive current collector, and the extending directions of the two positive tab portions 212 are opposite. Among them, the widths W3 of the multiple positive tab portions 212 can be the same or different. At this time, the total width W4 of the positive tab portion is the sum of the widths W3 of the multiple positive tab portions, and the total width V1 of the positive electrode main body portion is the width of the positive current collector. Similarly, its corresponding negative current collector can also have a similar structure, which will not be elaborated here.

[0205] It should be noted that when the electrode assembly is prepared by the stacking process, the electrode assembly may include a structure of multiple layers of continuously arranged positive electrode plates / separator films / negative electrode plates / separator films. At this time, the ratio of the total width of the aforementioned positive tab portion to the total width of the positive electrode main body portion corresponds to the ratio of the width of the positive tab portion to the width of the positive electrode main body portion in any positive electrode plate. Similarly, the ratio of the total width of the aforementioned negative tab portion to the total width of the negative electrode main body portion corresponds to the ratio of the width of the negative tab portion to the width of the negative electrode main body portion in any negative electrode plate.

[0206] It should be noted that referring to Figure 26, in the electrode assembly prepared by the lamination process, multiple positive electrode tab portions 212 may be misaligned (at least partially overlapped between adjacent positive electrode tab portions). At this time, the total width W4 of the positive electrode tab portions 212 can be regarded as the total width after stacking of multiple positive electrode tab portions 212 after the corresponding positive electrode sheet, negative electrode sheet, and separator are laminated. The total width V1 of the positive electrode main body portion is the width of the positive electrode current collector. Similarly, multiple negative electrode tab portions 312 may also be misaligned (at least partially overlapped between adjacent negative electrode tab portions). At this time, the total width W5 of the negative electrode tab portions 312 can be regarded as the total width after stacking of multiple negative electrode tab portions 22 after the corresponding positive electrode sheet, negative electrode sheet, and separator are laminated. The total width V2 of the negative electrode main body portion is the width of the negative electrode current collector.

[0207] In some embodiments, the widths and total widths of the positive electrode tab portions and the negative electrode tab portions can be the same. When the widths of the positive electrode current collector and the negative electrode current collector are also the same, along the width direction of the positive electrode main body portion, the ratio of the total width of the positive electrode tab portions to the total width of the positive electrode main body portion is the same as the ratio of the total width of the negative electrode tab portions to the total width of the negative electrode main body portion along the width direction of the negative electrode main body portion.

[0208] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material layer is provided on either one or both of the two opposite surfaces of the positive electrode current collector.

[0209] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (such as 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.).

[0210] In some embodiments, the positive electrode active material layer may further optionally include a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0211] In some embodiments, the positive electrode active material layer may further optionally include a conductive agent. As an example, the conductive agent can include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0212] In some embodiments, the positive electrode sheet can be prepared by the following method: dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode sheet can be obtained.

[0213] In some embodiments, the positive electrode sheet can be prepared by the following method: dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the lithium-rich material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode sheet can be obtained.

[0214] In some embodiments, the positive electrode sheet can be prepared by the following method: dispersing the positive electrode active material, the conductive agent, the binder and any other components in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, a positive electrode active material layer is formed, and then on the surface of the positive electrode active material layer, the lithium-rich material is compounded with the positive electrode active material layer by means such as spraying and secondary coating.

[0215] [Negative electrode sheet]

[0216] In some embodiments, the negative electrode sheet 3 includes a negative electrode current collector and a negative electrode active material layer located on at least one side of the negative electrode current collector. The negative electrode current collector includes a negative electrode main body portion 311 and at least one negative electrode ear portion 312, and the negative electrode main body portion 311 is connected to the negative electrode ear portion 312. Thus, the negative electrode sheet 3 can be electrically connected to the electrode terminal through the corresponding ear portion.

[0217] In some embodiments, the electrode terminal and the negative electrode ear portion can be electrically connected through a connecting piece. Specifically, the first limiting portion 1321 of the electrode terminal can be electrically connected to the negative electrode ear portion through the connecting piece. Thus, the welding quality and connection reliability between the electrode terminal and the ear portion can be significantly improved.

[0218] When the electrode terminal and the negative electrode ear portion are electrically connected through the connecting piece, the shape and size of the connecting piece can be adjusted as needed to adapt to different distances and positions, and the connecting piece has fewer welding process defects, which can help to more evenly distribute the current, reduce local overheating and potential difference, and improve the fast charging performance of the battery.

[0219] In some embodiments, the electrode terminal can be directly electrically connected to the negative electrode tab. Specifically, the first limiting portion 1321 of the electrode terminal can be directly electrically connected to the negative electrode tab. Thereby, it helps to reduce the structural complexity inside the battery cell, reduce the volume of the battery cell, and improve the energy density.

[0220] When the electrode terminal is directly electrically connected to the negative electrode tab, the connecting piece is omitted, the internal structure of the battery cell is simplified, the assembly steps are reduced, and the overall manufacturing cost is reduced.

[0221] In some embodiments, the ratio of the number of the negative electrode tabs to the number of the negative current collectors is 1-2. Thereby, the current density on the current collector can be dispersed, which helps to reduce the risk of local overheating.

[0222] In some embodiments, when the negative current collector includes a negative electrode main body portion 311 and a negative electrode tab 312, along the width direction of the negative electrode main body portion 311, the total width of the negative electrode tab 312 accounts for 40%-100% of the total width of the negative electrode main body portion 311. Thereby, by adopting a larger-area tab structure, the current-carrying capacity of the tab can be effectively improved, and the temperature rise of the battery cell 1 during fast charging can be alleviated.

[0223] In some embodiments, when the negative current collector includes a negative electrode main body portion 311 and two negative electrode tabs 312, along the width direction of the negative electrode main body portion 311, the width of each negative electrode tab 312 accounts for 15%-45% of the total width of the negative electrode main body portion 311, and the total width of the negative electrode tabs 312 accounts for 30%-90% of the total width of the negative electrode main body portion 311. Thereby, by adopting a larger-area tab structure, the current-carrying capacity of the tab can be effectively improved, and the temperature rise of the battery cell 1 during fast charging can be alleviated.

[0224] When the battery cell performs high-rate charge and discharge, the current and voltage inside the battery cell will increase correspondingly, and the current passing through the tab increases. A larger area of the negative electrode tab means lower resistance. On the one hand, according to Ohm's law, under the same voltage, a tab with a larger area can carry a higher current, that is, it has a stronger current-carrying capacity. On the other hand, when the resistance of the tab is small, the heat generated by the resistance loss after the current passes through the tab can be reduced, the heat generation of the battery under high current is reduced, and the heat dissipation efficiency of the battery is indirectly improved.

[0225] As an example, the negative current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer is provided on any one or both of the two opposite surfaces of the negative current collector.

[0226] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper 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.).

[0227] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery 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, and lithium titanate, etc. The silicon-based materials include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials include at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0228] In some embodiments, the negative electrode active material layer may also optionally include a binder. The binder includes 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).

[0229] In some embodiments, the negative electrode active material layer may also optionally include a conductive agent. The conductive agent includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0230] In some embodiments, the negative electrode active material layer may also optionally include other additives, such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0231] In some embodiments, the negative electrode plate may be prepared by the following method: dispersing the components for preparing the negative electrode plate, such as the negative electrode active material, conductive agent, binder, and any other components, in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode plate can be obtained.

[0232] [Electrolyte solution]

[0233] The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. There are no specific restrictions on the type of electrolyte in this application, and it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like or all-solid state.

[0234] In some embodiments, the electrolyte uses an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0235] In some embodiments, it further includes: an electrolytic solution, and the conductivity of the electrolytic solution at room temperature is 10 mS / cm - 18 mS / cm. Thus, the migration rate of lithium ions in the electrolytic solution is relatively high, which can further reduce the internal resistance of the battery cell 1.

[0236] As an example, the test method for the conductivity of the electrolytic solution can refer to HG-T 4067-2015.

[0237] In some embodiments, the viscosity of the electrolytic solution at room temperature is 1.5 mPa·s - 5.5 mPa·s. Thus, the migration rate of lithium ions in the electrolytic solution is relatively high.

[0238] As an example, the viscosity of the electrolytic solution at room temperature can be 1.5 mPa·s, 2 mPa·s, 2.5 mPa·s, 3 mPa·s, 3.5 mPa·s, 4 mPa·s, 4.5 mPa·s, 5 mPa·s or 5.5 mPa·s.

[0239] As an example, the viscosity of the electrolytic solution can be tested by the following method: The viscosity is tested by a viscometer. Referring to the national standard GB / T10247-2008, at a certain temperature, the shear force received by the rotor rotating continuously at a constant speed in the sample causes a torque on the spring, and the torque is proportional to the viscosity, obtaining the viscosity value.

[0240] In some embodiments, the electrolytic solution includes a chain carboxylic ester solvent. Thus, the chain carboxylic ester solvent can increase the solubility of the electrolyte lithium salt, thereby increasing the migration rate of lithium ions in the electrolytic solution.

[0241] The viscosity of the chain carboxylic ester solvent is relatively low, and further, the overall viscosity of the electrolytic solution with an organic solvent as the main body is relatively low. In the low-viscosity electrolytic solution, the intermolecular interaction force is weak, and the movement between molecules is more free, making the diffusion and migration speed of lithium ions in the electrolytic solution faster. Further, when the battery cell is charged and discharged rapidly, concentration polarization will occur inside the battery. When the ion migration rate of the electrolytic solution is relatively high, it can alleviate the concentration polarization inside the battery. The aforementioned low-viscosity electrolytic solution can effectively reduce the concentration polarization by increasing the ion migration rate and improve the fast-charging performance of the battery.

[0242] As an example, the qualitative analysis method of chain carboxylic ester solvents can adopt gas chromatography-ion chromatography coupling.

[0243] In some embodiments, the chain carboxylic ester solvents satisfy Formula I:

[0244] Formula I, where R1 includes at least one of a hydrogen atom, an alkyl group with 1 to 5 carbon atoms, and a halogenated alkyl group with 1 to 5 carbon atoms, and R2 includes at least one of an alkyl group with 1 to 5 carbon atoms and a halogenated alkyl group with 1 to 5 carbon atoms. Thus, by using the aforementioned chain carboxylic ester solvents, the viscosity and conductivity of the electrolyte can be controlled within the aforementioned ranges.

[0245] As an example, R1 can include at least one of a hydrogen atom, a methyl group, an ethyl group, a propyl group, a fluoromethyl group, a fluoroethyl group, and a fluoropropyl group.

[0246] As an example, R2 can be one or more of a methyl group, an ethyl group, a propyl group, a fluoromethyl group, a fluoroethyl group, and a fluoropropyl group.

[0247] In some embodiments, the chain carboxylic ester solvents include Formula I-1, Formula I-2, Formula I-3, Formula I-4, Formula I-5, Formula I-6, Formula I-7, at least one of Formula I-8.

[0248] Chain carboxylic esters have good lithium salt solubility, can improve the conductivity of the electrolyte, accelerate the migration rate of lithium ions inside the battery, and enhance the charge and discharge efficiency of the battery. And chain carboxylic esters show good thermal stability and oxidation stability at high temperatures, which helps to improve the stability of the battery under fast charging conditions and reduce the risk of thermal runaway.

[0249] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bis(oxalato)borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0250] In some embodiments, the electrolyte may further optionally include additives. For example, the additives can include negative electrode film-forming additives, positive electrode film-forming additives, and can also include additives that can improve certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature or low-temperature performance of the battery, etc.

[0251] [Separator membrane]

[0252] There is no particular limitation on the type of the separator membrane in this application, and any well-known porous structure separator membrane with good chemical stability and mechanical stability can be selected.

[0253] In some embodiments, the material of the separator membrane includes at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0254] In the second aspect of this application, a battery device is proposed, which includes the aforementioned battery cell 1. The battery device includes at least one of a battery module, a battery pack, and an energy storage device. Thus, this battery device has all the features and advantages of the aforementioned battery cell 1, which will not be elaborated here.

[0255] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, and the multiple battery cells are connected in series, parallel, or in a mixed connection through a busbar component.

[0256] In some embodiments, a battery cell assembly is usually formed by arranging multiple battery cells.

[0257] As an example, the battery cell assembly can be a battery module, and the battery module is formed by arranging and fixing multiple battery cells into an independent module. As an example, the battery module can be formed by bundling multiple battery cells with a tie strap.

[0258] In some embodiments, the battery device can be a battery pack, and the battery pack includes a box body and one or more battery cell assemblies, and the battery cell assemblies are accommodated in the box body.

[0259] As an example, the battery cell assembly can also be accommodated in the box body by directly fixing multiple battery cells to the box body.

[0260] As an example, the box body may include a first box body and a second box body. The first box body and the second box body are buckled so that a closed space is formed inside the box body to accommodate the battery cell assembly. The "closed" here means covering or closing, which can be sealed or non-sealed. The first box body can be a top cover or a bottom plate.

[0261] As an example, the box body may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame so that a closed space is formed inside the box body to accommodate the battery cell assembly.

[0262] In some embodiments, the box body can be part of the chassis structure of a vehicle. For example, part of the box body can form at least part of the floor of the vehicle, or part of the box body can form at least part of the cross beams and longitudinal beams of the vehicle.

[0263] In the third aspect of the present application, an electrical device is proposed, including the aforementioned battery cell 1. Thus, this electrical device has all the features and advantages of the aforementioned battery cell 1, which will not be elaborated here.

[0264] The aforementioned battery cell or battery pack can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device can include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but not limited thereto.

[0265] As the electrical device, the battery cell or battery pack can be selected according to its usage requirements.

[0266] Figure 27 is an electrical device as an example. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the electrical device for the battery, a battery pack or battery module can be used.

[0267] Another example of an electrical device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires being thin and light, and a battery cell can be used as the power source.

[0268] The solution of the present application will be described below through specific embodiments. It should be noted that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For those reagents or instruments not specified with the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0269] Example 1

[0270] 1. Positive electrode plate

[0271] The positive electrode plate includes a positive current collector aluminum foil, and positive active material layers are provided on both surfaces of the aluminum foil. In the state of 100% SOC, the tap density of the positive active material layer is 2.65 g / cm 3 ; the coating weight of the single-sided positive active material layer is 260 mg / cm 2; Based on the total mass of the single-sided positive electrode active material layer, the positive electrode active material layer includes lithium iron phosphate material with a mass fraction of 95.4%, carbon nanotubes with a mass fraction of 0.3%, lithium ferrite as a lithium supplement agent with a mass fraction of 1.7%, carbon black as a conductive agent with a mass fraction of 0.4%, and polyvinylidene fluoride (PVDF) as a binder with a mass fraction of 2.2%. The surface of the lithium iron phosphate has a carbon coating layer, and based on the total mass of the lithium iron phosphate, the mass fraction of the carbon coating layer is 1.18%. The film resistance of the positive electrode sheet is 0.1 Ω.

[0272] 2. Negative electrode sheet

[0273] The negative electrode sheet includes a negative electrode current collector copper foil, and the coating weight of the single-sided negative electrode active material layer is 123 mg / cm 2 , Based on the total mass of the single-sided negative electrode active material layer, the negative electrode active material layer includes artificial graphite with a mass fraction of 96%, carbon black as a conductive agent with a mass fraction of 1.1%, styrene-butadiene rubber (SBR) as a binder with a mass fraction of 1.4%, and sodium carboxymethyl cellulose (CMC-Na) as a thickener with a mass fraction of 1.5%.

[0274] 3. Electrolyte

[0275] The electrolyte includes a solvent and an electrolyte salt. The solvent includes methyl acetate or ethyl acetate, and the electrolyte salt is lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide salt. The concentration of the electrolyte salt in the electrolyte is 1.0 mol / L.

[0276] 4. Separator

[0277] The separator is a porous polypropylene film.

[0278] 5. Preparation of battery cell

[0279] The battery cell includes a housing (the length of the housing of the battery cell is 630 mm, the width is 99.6 mm, and the thickness is 15.7 mm), an electrode assembly and an electrolyte. The electrode assembly and the electrolyte are arranged in the housing. The electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator. The electrode assembly is a stacked structure, and the separator is arranged between the positive electrode sheet and the negative electrode sheet. The housing includes two end caps oppositely arranged along the length direction of the battery cell. The first end cap adopts the structure as shown in Figure 2 , The second end cap adopts the structure as shown in 7, where L1 is 100 mm, L2 is 50 mm, W1 is 15.4 mm, and W2 is 8 mm.

[0280] For the differences between the remaining examples, comparative examples and Example 1, see Table 1. Among them, in Example 20, the first end cap adopts the structure as shown in Figure 14 , The second end cap adopts the structure as shown in Figure 18 , L1 and W1 are the length and width of the first limiting part of the same electrode terminal.

[0281] The fast charging performance of the battery cells in the foregoing examples and comparative examples was tested, and the temperature change of the top cover during the fast charging performance test was monitored. The test method is as follows, and the test results are shown in Table 1.

[0282] Cycling performance under fast charging conditions (45°C @ 80% SOH): At an ambient temperature of 45°C, the battery cell was charged to 3.65V by Stepcharge, charged at a constant voltage to 0.05C, rested for 30 minutes, discharged at a constant current of 0.5C to 2.5V, and rested for 30 minutes. This is one charge-discharge cycle. Repeat the above charge-discharge cycle until the capacity of the battery cell is 80% of the initial capacity, and the number of charge-discharge cycles obtained is the fast charging cycle performance of the battery cell. Among them,

[0283] The Step charge charging steps are as follows: Constant current charge from 0% SOC to 10% SOC at 1C; Constant current charge from 10% SOC to 15% SOC at 7.0C; Constant current charge from 15% SOC to 20% SOC at 7.0C; Constant current charge from 20% SOC to 25% SOC at 7.0C; Constant current charge from 25% SOC to 30% SOC at 7.0C; Constant current charge from 30% SOC to 35% SOC at 6.2C; Constant current charge from 35% SOC to 40% SOC at 5.7C; Constant current charge from 40% SOC to 45% SOC at 5.2C; Constant current charge from 45% SOC to 50% SOC at 4.8C; Constant current charge from 50% SOC to 55% SOC at 4.6C; Constant current charge from 55% SOC to 60% SOC at 4.2C; Constant current charge from 60% SOC to 65% SOC at 3.9C; Constant current charge from 65% SOC to 70% SOC at 3.5C; Constant current charge from 70% SOC to 75% SOC at 3.0C; Constant current charge from 75% SOC to 80% SOC at 0.33C; Constant current charge from 80% SOC to 100% SOC.

[0284] Table 1

[0285]

[0286] The test results show that the battery cells in this application can effectively reduce the heat generation of the battery cells during high-rate charge and discharge, and accelerate the rapid diffusion of the heat accumulated inside the battery cells, so that the battery cells can maintain a relatively stable temperature during high-rate charge and discharge, and the battery cells have excellent high-rate charge and discharge performance.

[0287] Specifically, in Examples 1-3, the length L1 of the end plate is different, and the cycle performance of the battery cell under fast charging conditions is positively correlated with the ratio of L2 / L1; in Examples 4-8, the length L2 of the first limiting portion is different, and the cycle performance of the battery cell under fast charging conditions is positively correlated with the ratio of L2 / L1. Examples 1-8 show that when the ratio relationship between L1 and L2 is within the aforementioned range, the size of the first limiting portion is larger, the welding area at the welding joint between the electrode assembly and the electrode terminal is larger, and a large amount of heat generated due to the large internal resistance at the weld during fast charging can be effectively reduced, so that the battery cell can maintain a relatively stable temperature during the rate charge and discharge process, and the battery cell has a better cycle performance under fast charging conditions.

[0288] In Examples 9-11, the width W1 of the end plate is different, and the cycle performance of the battery cell under fast charging conditions is positively correlated with the ratio of W2 / W1; in Examples 12-14, the width W2 of the first limiting portion is different, and the cycle performance of the battery cell under fast charging conditions is positively correlated with the ratio of W2 / W1. Examples 9-14 show that when the ratio relationship between W1 and W2 is within the aforementioned range, the size of the first limiting portion is larger, the welding area at the welding joint between the electrode assembly and the electrode terminal is larger, and a large amount of heat generated due to the large internal resistance at the weld during fast charging can be effectively reduced, so that the battery cell can maintain a relatively stable temperature during the rate charge and discharge process, and the battery cell has a better cycle performance under fast charging conditions.

[0289] In Example 17, the content of the conductive agent in the positive electrode active material layer is different, resulting in a lower film resistance of the positive electrode plate, a shorter electron conduction path in the positive electrode active material layer, less heat generation of the positive electrode plate under fast charging conditions, and better cycle performance of the battery cell under fast charging conditions.

[0290] In Example 18, each first wall includes two electrode terminals with different polarities, which can effectively disperse the current density inside the battery cell, thereby reducing the current load on a single electrode terminal, alleviating the polarization unevenness inside the battery cell, reducing the risk of local overheating, and improving the cycle performance under fast charging conditions.

[0291] Comparative Examples 1-4 show that when the film resistance of the positive electrode plate and / or the size of the first limiting portion do not meet the requirements, the cycle performance of the battery cell under fast charging conditions is poor and the temperature rises significantly.

[0292] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered within the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: An electrode assembly, the electrode assembly comprising a positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer located on at least one side of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode active material, the positive electrode active material comprising a lithium-containing phosphate, wherein the sheet resistance of the positive electrode sheet is 0.02Ω-5Ω; a shell, the shell forming a accommodating space, the electrode assembly being located within the accommodating space of the shell, the shell comprising a first wall, at least one electrode terminal being provided on the first wall, the electrode terminal comprising a first limiting portion, the first limiting portion being located on a side of the first wall facing the electrode assembly, the first limiting portion being electrically connected to the electrode assembly, wherein, Along the length direction of the first wall, the length of the first wall is L1, the length of the first limiting portion is L2, and L2≥20%L1; along the width direction of the first wall, the width of the first wall is W1, the width of the first limiting portion is W2, and W2≥20%W1.

2. The battery cell according to claim 1, wherein: 86%L1≥L2, and / or, 66%W2≥W1.

3. The battery cell according to claim 1, wherein: L1-L2 ≥ 3 mm; and / or, W1-W2 ≥ 3 mm.

4. The battery cell according to claim 1, wherein: 120mm≥L1-L2; and / or, 15mm≥W1-W2.

5. The battery cell according to claim 1, characterized in that L1 is 100mm-140mm, L2 is 30mm-120mm.

6. The battery cell according to claim 1, characterized in that W1 is 13mm-23mm, and W2 is 5mm-15mm.

7. The battery cell according to claim 1, characterized in that The first wall is provided with a through hole, and the electrode terminal further includes a terminal main body and a second limiting part. The terminal main body connects the second limiting part and the first limiting part, the terminal main body passes through the through hole, and the second limiting part is located on the side of the first wall away from the electrode assembly.

8. The battery cell according to claim 1, wherein: The membrane resistance of the positive electrode plate is 0.05Ω-1Ω.

9. The battery cell according to claim 1, characterized in that The positive electrode active material layer includes a conductive agent, and the mass fraction of the conductive agent in the positive electrode active material layer is 1%-5%.

10. The battery cell according to claim 9, characterized in that The conductive agent includes carbon nanotubes, and the mass fraction of the carbon nanotubes in the positive electrode active material layer is 0.1%-1.1%.

11. The battery cell according to claim 10, characterized in that The diameter of the carbon nanotubes is 1 nm to 16 nm.

12. The battery cell according to claim 10, characterized in that The diameter of the carbon nanotubes is 1 nm to 8 nm.

13. The battery cell according to claim 10, characterized in that The conductive agent also includes carbon black.

14. The battery cell according to claim 1, characterized in that The lithium-containing phosphate satisfies the general formula: Li x1 A y1 Me a M b P 1-c X c Y z , wherein, 0.5≤x1≤1.3, 0≤y1≤1.3, and 0.9≤x1+y1≤1.3, 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5, 0≤c≤0.5, 3≤z≤5, A includes at least one of Na, K, and Mg, Me includes at least one of Mn, Fe, Co, and Ni, M includes at least one of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce, X includes at least one of Cl, C, and N, and Y includes one or two of O and F.

15. The battery cell according to claim 1, characterized in that The lithium-containing phosphate includes lithium iron phosphate material.

16. The battery cell according to claim 1, characterized in that At least a portion of the surface of the lithium-containing phosphate has a carbon coating layer. Based on the total mass of the lithium-containing phosphate and the carbon coating layer, the mass fraction of carbon in the positive electrode active material is 0.7%-1.5%.

17. The battery cell according to claim 1, characterized in that The powder resistivity of the positive electrode active material is 2S / cm-60S / cm.

18. The battery cell according to claim 1, characterized in that The powder resistivity of the positive electrode active material is 2S / cm-30S / cm.

19. The battery cell according to claim 1, characterized in that The positive electrode active material layer further includes a lithium-rich material, and the mass fraction of the lithium-rich material in the positive electrode active material layer is 0.1%-5%.

20. The battery cell according to claim 19, characterized in that The lithium-rich material includes at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganese oxide, lithium tartrate, trilithium citrate, lithium nickelate and lithium ferrite.

21. The battery cell according to claim 1, characterized in that The single-side coating weight of the positive electrode active material layer is 200 mg / 1540.25 mm 2 -370mg / 1540.25mm 2 .

22. The battery cell according to claim 1, characterized in that The compaction density of the positive electrode active material layer of the battery cell at 100% SOC is 2.50 g / cm 3 -2.80g / cm 3 .

23. The battery cell according to claim 1, characterized in that In the longitudinal direction of the positive electrode current collector, the coating length of the positive electrode active material layer is 200 mm to 700 mm.

24. The battery cell according to claim 1, characterized in that Along the thickness direction of the first wall, a ratio of an orthographic projection area of the first limiting portion on the first wall to an area of the first wall is 15%-65%.

25. The battery cell according to claim 1, characterized in that Along the thickness direction of the first wall, a ratio of an orthographic projection area of the first limiting portion on the first wall to an area of the first wall is 20%-60%.

26. The battery cell according to claim 24, characterized in that The ratio of the orthographic projection area of each first limiting portion on the first wall to the area of the first wall is 6%-30%.

27. The battery cell according to claim 24, characterized in that A ratio of an orthographic projection area of each first limiting portion on the first wall to an area of the first wall is 8%-28%.

28. The battery cell according to claim 1, characterized in that Each of the first walls includes two electrode terminals, and the two electrode terminals have the same polarity, or the two electrode terminals have opposite polarities.

29. The battery cell according to claim 28, characterized in that Each of the first walls includes two electrode terminals with opposite polarities, wherein the electrode terminals with the same polarity on different first walls are staggered along the length direction of the battery cell.

30. The battery cell according to claim 29, characterized in that The electrode terminals of the same polarity are arranged diagonally along the length direction of the battery cell.

31. The battery cell according to claim 1, characterized in that The electrode assembly is a laminated structure.

32. The battery cell according to claim 31, characterized in that The positive electrode current collector includes a positive electrode main body and at least one positive electrode ear, and the positive electrode main body is connected to the positive electrode ear. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer located on at least one side of the negative electrode current collector. The negative electrode current collector includes a negative electrode main body and at least one negative electrode ear, and the negative electrode main body is connected to the negative electrode ear.

33. The battery cell according to claim 32, characterized in that The ratio of the number of the positive electrode tabs to the number of the positive electrode current collectors is 1-2; and / or the ratio of the number of the negative electrode tabs to the number of the negative electrode current collectors is 1-2.

34. The battery cell according to claim 33, characterized in that The positive electrode current collector includes a positive electrode main body and a positive electrode ear, and along the width direction of the positive electrode main body, the total width of the positive electrode ear accounts for 40%-100% of the total width of the positive electrode main body; and / or, the negative electrode current collector includes a negative electrode main body and a negative electrode ear, and along the width direction of the negative electrode main body, the total width of the negative electrode ear accounts for 40%-100% of the total width of the negative electrode main body.

35. The battery cell according to claim 33, characterized in that The positive electrode current collector includes a positive electrode main body and two positive electrode ear portions, and along the width direction of the positive electrode main body, the width of each positive electrode ear portion accounts for 15%-45% of the total width of the positive electrode main body; and / or, the negative electrode current collector includes a negative electrode main body and two negative electrode ear portions, and along the width direction of the negative electrode main body, the total width of the negative electrode ear portions accounts for 15%-45% of the total width of the negative electrode main body.

36. The battery cell according to any one of claims 1 to 34, characterized in that: include: The electrolyte has an electrical conductivity of 10 mS / cm-18 mS / cm at room temperature.

37. The battery cell according to claim 36, characterized in that The viscosity of the electrolyte at room temperature is 1.5 mPa·s-5.5 mPa·s.

38. The battery cell according to claim 36, characterized in that The electrolyte includes a chain carboxylate solvent.

39. The battery cell according to claim 38, characterized in that The chain carboxylate solvent satisfies Formula I: Formula I, Wherein, R1 includes at least one of a hydrogen atom, a C1-C5 alkyl group, and a C1-C5 halogenated alkyl group, R2 includes at least one of a C1-C5 alkyl group and a C1-C5 halogenated alkyl group.

40. The battery cell according to claim 39, characterized in that The chain carboxylate solvent includes Formula I-1, Formula I-2, Formula I-3, Formula I-4, Formula I-5, Formula I-6, Formula I-7, At least one of formula I-8.

41. The battery cell according to claim 1, characterized in that The battery cells are configured to be charged from 10% SOC to 80% SOC in a time range of 5 min to 10.5 min.

42. A battery device, characterized in that: The battery device comprises a battery cell according to any one of claims 1 to 41, wherein the battery device comprises at least one of a battery module, a battery pack, and an energy storage device.

43. An electrical device, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 41.

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