Battery cell, battery device, electric device

Abstract

The present disclosure provides a battery cell, a battery device, and a power consumption device. The battery cell comprises: 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 sheet, 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 0.02 Ω-5 Ω; and a shell, the electrode assembly being located in an accommodation space of the shell, the shell comprising an end plate, at least one electrode terminal being provided on the end plate, and the ratio of the area of the orthographic projection of the terminal main body part of the electrode terminal of a single polarity on the end plate to the area of the side surface of the end plate away from the electrode assembly being 5%-70%.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to PCT patent application PCT / CN2025 / 071090, filed on January 7, 2025, entitled “Battery Cell, Battery Device, Electrical Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of batteries, specifically to battery cells, battery devices, and electrical devices. Background Technology

[0004] Lithium-ion batteries are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. However, current batteries still have many problems in practical applications and require further improvement.

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

[0006] In a first aspect, this application proposes a battery cell comprising: an electrode assembly including a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer located on at least one side of the positive electrode sheet, the positive active material layer including a positive active material containing lithium phosphate, wherein the film resistivity of the positive electrode sheet is 0.02Ω-5Ω; and a housing including a receiving space, the electrode assembly being located within the receiving space of the housing, the housing including an end plate, the end plate having at least one electrode terminal, the electrode terminal including a terminal body portion, the ratio of the projected area of ​​the terminal body portion of the single-polarity electrode terminal on the end plate to the area enclosed by the outer contour of the end plate being 5%-70%. This effectively reduces heat generation in the battery cell during high-rate charging and discharging, thereby allowing the battery cell to maintain a relatively stable temperature during high-rate charging and discharging, resulting in superior high-rate charging and discharging performance.

[0007] In some embodiments, the ratio of the projected area of ​​the terminal body portion of the single-polarity electrode terminal on the end plate to the area enclosed by the outer contour of the end plate is 15%-65%, optionally 20%-60%. Thus, the electrode terminal can provide superior current carrying capacity and a larger heat dissipation area, while the end plate has ample space for mounting other structural components.

[0008] In some embodiments, the membrane resistance of the positive electrode tab is 0.05 Ω-1 Ω. In this way, the heat generation of the positive electrode tab during charging and discharging can be reduced.

[0009] In some embodiments, the positive electrode active material layer comprises a conductive agent, and the mass fraction of the conductive agent in the positive electrode active material layer is 0.5%-5%. In this way, the heat generation of the positive electrode tab can be further reduced by the construction of the conductive network.

[0010] In some embodiments, the positive electrode active material layer comprises a conductive agent, and the conductive agent comprises carbon nanotubes, and the mass fraction of the carbon nanotubes in the positive electrode active material layer is 0.1%-1.1%. In this way, the impedance of the positive electrode tab can be effectively reduced by adding a small amount of carbon nanotubes, thereby reducing heat generation.

[0011] In some embodiments, the carbon nanotubes have a tube diameter of 1 nm-16 nm; optionally, 1 nm-8 nm. In this way, the carbon nanotubes have better electronic conductivity.

[0012] In some embodiments, the conductive agent further comprises carbon black. In this way, by mixing and using multiple conductive agents, a more uniform and dense conductive network can be formed, which is beneficial to reducing the internal resistance of the positive electrode tab and reducing heat generation.

[0013] 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 , 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 comprises at least one of Na, K, Mg, Me comprises at least one of Mn, Fe, Co, Ni, M comprises at least one of 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, Ce, X comprises at least one of S, Si, Cl, B, C, N, and Y comprises one or both of O, F. In this way, the lithium-containing phosphate particles have high structural stability and excellent cycle stability during charging and discharging, which is beneficial to improving the cycle performance of the battery cell.

[0014] In some embodiments, at least part of the surface of the lithium-containing phosphate has a carbon coating layer, and the mass fraction of carbon elements in the positive electrode active material is 0.7%-1.5% based on the total mass of the lithium-containing phosphate and the carbon coating layer. In this way, the conductivity of the positive electrode active material can be improved.

[0015] In some embodiments, the powder resistivity of the positive electrode active material is 2 S / cm-60 S / cm, or 2 S / cm-30 S / cm. In this way, the internal resistance of the positive electrode plate can be reduced, and the heat generation can be reduced.

[0016] In some embodiments, the positive electrode active material layer further comprises a lithium-rich material, and the mass fraction of the lithium-rich material in the positive electrode active material layer is 0.1%-5%. In this way, the appropriate addition of the lithium-rich material can not only compensate for the irreversible loss of lithium ions in the battery cell, but also have little effect on the internal resistance of the positive electrode plate, which is conducive to reducing the heat generation.

[0017] In some embodiments, the lithium-rich material comprises at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, 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 ferrite. In this way, the lithium-rich material can compensate for the consumption of active lithium during the first charge and store part of the lithium ions in the negative electrode active material, thereby improving the capacity of the battery cell.

[0018] 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 In this way, by controlling the number of active lithium ions per unit area of the positive electrode plate, the polarization during high-rate charging and discharging can be effectively reduced, and the polarization resistance can be reduced.

[0019] 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 In this way, the particles in the positive electrode active material layer are closely packed, and the contact resistance between the particles is small, which is conducive to reducing the resistance of the positive electrode plate and improving the energy density of the battery cell.

[0020] 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. In this way, the length of the positive electrode active material layer is moderate, the electron migration path is moderate, the polarization is weak, and the heat generation is small.

[0021] In some embodiments, the end plate is provided with a lead-out hole, the electrode terminal further comprises a first limiting part and a second limiting part, the terminal body part connects the first limiting part and the second limiting part, the terminal body part is arranged in the lead-out hole, the first limiting part is located on the side of the end plate facing the electrode assembly, and the second limiting part is located on the side of the end plate away from the electrode assembly. Thus, the electrode terminal can be firmly fixed on the end plate and electrically connected with the electrode assembly and the external circuit.

[0022] In some embodiments, the ratio of the area of the orthographic projection of the terminal body part on the end plate to the area of the orthographic projection of the first limiting part on the end plate is 30%-90%. Thus, the internal resistance of the electrode terminal can be reduced, and the heat generation can be reduced.

[0023] In some embodiments, the cross section of the terminal body part in the direction parallel to the end plate is a rounded rectangle. Thus, the assembly of the electrode terminal is facilitated.

[0024] In some embodiments, each end plate comprises two electrode terminals, the polarities of the two electrode terminals are the same, or the polarities of the two electrode terminals are opposite. Thus, the current density inside the battery monomer can be effectively dispersed, thereby reducing the current load on a single electrode terminal and helping to reduce the risk of local overheating.

[0025] In some embodiments, each end plate comprises two electrode terminals with opposite polarities, and the electrode terminals with a single polarity on different end plates are arranged staggered along the length direction of the battery monomer, or the electrode terminals with a single polarity on different end plates are arranged diagonally along the length direction of the battery monomer. Thus, the electrical connection of multiple battery monomers is facilitated.

[0026] In some embodiments, the electrode assembly is a laminated structure, the laminated structure comprises a plurality of positive electrode laminates and a plurality of negative electrode laminates arranged in layers, each positive electrode laminate comprises a positive current collector, the positive current collector comprises a positive body part and a positive tab part, each negative electrode laminate comprises a negative current collector and a negative tab part, the negative current collector comprises a negative body part and a negative tab part, the positive body part is electrically connected with the positive tab part, the positive tab part is electrically connected with a positive terminal, the negative body part is electrically connected with the negative tab part, and the negative tab part is electrically connected with a negative terminal. Thus, the electrode assembly can make more full use of the internal space of the battery monomer, reduce the waste of internal space, and help to evenly distribute the heat inside the battery monomer, which is conducive to improving the heat dissipation efficiency and reducing the risk of local overheating.

[0027] In some embodiments, a ratio of the number of the positive electrode tab portions to the number of the positive electrode current collectors is 1-2; and / or, a ratio of the number of the negative electrode tab portions to the number of the negative electrode current collectors is 1-2. Thereby, it is helpful to disperse the current density on the current collectors, and to reduce the risk of local overheating.

[0028] In some embodiments, along the width direction of the positive electrode body portion, the total width of the positive electrode tab portions accounts for 80%-100% of the total width of the positive electrode body portion; and / or, along the width direction of the negative electrode body portion, the total width of the negative electrode tab portions accounts for 80%-100% of the total width of the negative electrode body portion. Thereby, by adopting the tab structure with larger area, the overcurrent capacity of the tab portion can be effectively improved, and the temperature rise of the battery cell in the fast charging process can be alleviated.

[0029] In some embodiments, further comprising: an electrolyte, an electrical conductivity of the electrolyte at normal temperature is 10 mS / cm-18 mS / cm. Thereby, the migration rate of lithium ions in the electrolyte is higher, which can further reduce the internal resistance of the battery cell and reduce heat generation.

[0030] In some embodiments, a viscosity of the electrolyte at normal temperature is 1.5 mPa·s-5.5 mPa·s. Thereby, the migration rate of lithium ions in the electrolyte is higher, which is conducive to improving the rate charge and discharge performance.

[0031] In some embodiments, the electrolyte comprises a chain carboxylate solvent. Thereby, the chain carboxylate solvent can improve the solubility of the electrolyte lithium salt, thereby improving the migration rate of lithium ions in the electrolyte.

[0032] In some embodiments, the chain carboxylate solvent satisfies formula I:

[0033] Formula I, wherein R1 comprises at least one of a hydrogen atom, a C1-C5 alkyl group, and a C1-C5 halogenated alkyl group, and R2 comprises at least one of a C1-C5 alkyl group and a C1-C5 halogenated alkyl group. Thereby, by adopting the aforementioned chain carboxylate solvent, the viscosity and electrical conductivity of the electrolyte can be controlled within an appropriate range.

[0034] In some embodiments, the chain carboxylate solvent comprises Formula I-1, Formula I-2, Formula I-3, Formula I-4, Formula I-5, Formula I-6, Formula I-7, Formula I-8.

[0035] In some embodiments, the battery cell is configured to have a time of 5 min-10.5 min to charge from 10% SOC to 80% SOC. Thereby, the battery cell has a better performance of rate charge and discharge.

[0036] In a second aspect of the present application, a battery device is provided, comprising the battery cell as described above. The battery device comprises at least one of a battery module, a battery pack, and an energy storage device. Thereby, the battery device has all the features and advantages of the battery cell as described above, which will not be repeated here.

[0037] In a third aspect of the present application, a consumer device is provided, comprising the battery cell as described above. Thereby, the consumer device has all the features and advantages of the battery cell as described above, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0038] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the following drawings, in which:

[0039] Figure 1 is a partial structural diagram of an end plate of one embodiment of the present application.

[0040] Figure 2 is a structural diagram of a cover plate assembly of one embodiment of the present application.

[0041] Figure 3 is Figure 2 an exploded view of the cover plate assembly.

[0042] Figure 4 is a top view of the cover plate assembly of one embodiment of the present application.

[0043] Figure 5 is Figure 4 a sectional view of the cover plate assembly along AA' direction.

[0044] Figure 6 is a structural diagram of a cover plate assembly of another embodiment of the present application.

[0045] Figure 7 is Figure 6 an exploded view of the cover plate assembly.

[0046] Figure 8 is a top view of the cover plate assembly of another embodiment of the present application.

[0047] Figure 9 is Figure 8 a sectional view of the cover plate assembly along BB' direction.

[0048] Figure 10 is a structural diagram of a housing of one embodiment of the present application.

[0049] Figure 11 This is a schematic diagram of the structure of a battery cell according to an embodiment of this application.

[0050] Figure 12 This is a schematic diagram of the structure of a cover plate assembly according to another embodiment of this application.

[0051] Figure 13 yes Figure 12 Exploded view of the middle cover plate assembly.

[0052] Figure 14 This is a top view of a cover plate assembly according to yet another embodiment of this application.

[0053] Figure 15 yes Figure 14 Cross-sectional view of the middle cover plate assembly along the CC' direction.

[0054] Figure 16 This is a schematic diagram of the structure of a cover plate assembly according to another embodiment of this application.

[0055] Figure 17 yes Figure 16 Exploded view of the middle cover plate assembly.

[0056] Figure 18 This is a top view of a cover plate assembly according to yet another embodiment of this application.

[0057] Figure 19 yes Figure 18 Cross-sectional view of the middle cover plate assembly along the DD' direction.

[0058] Figure 20 This is a positive electrode sheet of one embodiment of this application.

[0059] Figure 21 This is a schematic diagram of the structure of an electrode assembly according to an embodiment of this application.

[0060] Figure 22 This is a schematic diagram of the structure of a positive current collector according to an embodiment of this application.

[0061] Figure 23 This is a schematic diagram of the structure of the positive current collector according to another embodiment of this application.

[0062] Figure 24 This is a schematic diagram of the structure of the positive current collector according to another embodiment of this application.

[0063] Figure 25 This is a schematic diagram of the structure of an electrode assembly fabricated using a lamination process according to an embodiment of this application.

[0064] Figure 26 This is a schematic diagram of the structure of an electrical device according to an embodiment of this application.

[0065] BRIEF DESCRIPTION OF DRAWINGS

[0066] 1 battery cell; 2 positive electrode sheet; 3 negative electrode sheet; 4 separator;

[0067] 21 positive current collector; 22 positive active material layer; 211 positive main portion; 212 positive tab portion; 311 negative main portion; 312 negative tab portion;

[0068] 11 housing; 111 first opening; 112 second opening;

[0069] 12 first cover plate assembly; 121 first end plate; 122 positive electrode terminal; 123 first insulating member; 124 first sealing member; 125 first positioning member; 126 second insulating member; 127 riveting block; 1211 first through hole; 1212 liquid injection hole; 1221 first limiting portion of positive electrode terminal; 1222 terminal main portion of positive electrode terminal; 1223 second limiting portion of positive electrode terminal; 1231 second through hole;

[0070] 13 second cover plate assembly; 131 second end plate; 132 negative electrode terminal; 133 third insulating member; 134 second sealing member; 135 second positioning member; 136 fourth insulating member; 137 pressure relief portion; 1311 third through hole; 1321 first limiting portion of negative electrode terminal; 1322 terminal main portion of negative electrode terminal; 1323 second limiting portion of negative electrode terminal; 1231 second through hole; 1331 fourth through hole. DETAILED DESCRIPTION

[0071] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, but there will be cases where unnecessary detailed description is omitted. For example, there are cases where detailed description of matters known well, repeated description of substantially the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy, facilitating understanding by those skilled in the art. In addition, the drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0072] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; unless otherwise specified, the numerical values of various parameters mentioned in the present application can be measured by various measurement methods commonly used in the art (for example, tests can be performed according to the methods given in the embodiments of the present application).

[0073] The terms "comprise" and "have" and any variations thereof in the specification and claims of this application are open-ended transitional phrases, i.e., including, but not limited to, whatever falling within the scope of the terms.

[0074] In the description of the application, whether using "about" or "approximately" or not, all the numbers disclosed herein are approximate values. The value of each number can have a difference of 10% or less, or a reasonable difference in the opinion of those skilled in the art, such as 1%, 2%, 3%, 4% or 5%.

[0075] The "range" disclosed in the present application is defined in the form of lower limit and 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 boundary of a particular range. The range defined in this way can be inclusive or exclusive of the end value, and can be arbitrarily combined, i.e. any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 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, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise stated, the numerical range "a-b" represents a shorthand notation for any real combination between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein, and "0-5" is only a shorthand notation for these numerical combinations. In addition, when a parameter is stated to be ≥2 integers, it is equivalent to disclose that the parameter is, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0076] In the description of the application, it is understood that the terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0077] In the description of the application, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. "First feature", "second feature" can include one or more of the features.

[0078] In the description of the application, "multiple" means two or more.

[0079] In the description of the present application, the first feature is "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them.

[0080] In the description of the present application, the first feature is "on", "above" and "over" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher than the second feature in height.

[0081] In the description of the present application, "A and / or B" can include any one of the case of A alone, the case of B alone, and the case of A and B, where A and B are only used as examples, which can be any technical feature connected by "and / or" in the present application.

[0082] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0083] If not specifically stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0084] The fast charging performance of the battery enables the user to supplement a large amount of power to the device in a short time, reduces the charging waiting time, and improves the user experience. During the fast charging process, the chemical reaction rate inside the battery cell is accelerated, and the current output by the battery cell is larger. Further, when the internal resistance of the battery cell is larger, according to Joule's law, as the battery cell continues to work under a larger current, a large amount of heat will be generated inside the battery cell, and then a significant temperature rise will occur. 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 active material, resulting in rapid decline of the battery capacity and poor cycle performance of the battery. In extreme cases, overheating can cause the battery to have a thermal runaway phenomenon, and even cause combustion or explosion, posing a serious threat to the user and the surrounding environment.

[0085] The lithium-containing phosphate has low cost and high theoretical specific capacity, which helps to improve the energy density of the battery cell. However, the lithium-containing phosphate has high powder resistivity. In the fast charging condition, the heat generated by the positive electrode active material powder due to the high powder resistivity of the positive electrode active material, and the heat generated by the mechanical part due to the large current passing through the electrode terminal are the main reasons for the temperature rise of the battery cell. In the present application, the main heat source generated under the condition of large current in the battery cell is improved, and the internal heat generation of the battery cell under the fast charging condition is effectively reduced. Specifically, when the sheet resistance of the positive electrode sheet 2 is 0.02 Ω-5 Ω, the internal resistance of the positive electrode sheet is small, the conduction path of the electrons in the positive electrode active material layer is short, and the heat generated by the positive electrode sheet under the fast charging condition is small. At the same time, when the ratio of the positive projection area of the terminal main body part 1222 of the positive electrode terminal and the terminal main body part 1322 of the negative electrode terminal on the end plate to the area surrounded by the outer contour of the end plate is 5%-70%, the overcurrent area of the electrode terminal is large, which helps to reduce the internal resistance of the electrode terminal, thereby reducing the heat generated at the electrode terminal and improving the heat dissipation at the electrode terminal. Therefore, the heat generated by the battery cell 1 during the rate charging and discharging process can be effectively reduced, and the rapid diffusion of the heat accumulated in the battery cell 1 can be accelerated, so that the battery cell 1 can maintain a relatively stable temperature during the rate charging and discharging process, and the battery cell 1 has a relatively good rate charging and discharging performance. The present application controls the heat generation of the chemical system and the mechanical part of the lithium-containing phosphate battery cell to reduce the internal temperature rise of the battery cell and improve the cycle performance of the battery cell under fast charging.

[0086] The battery cell provided in the present application can be used in a power consumption device using the battery cell as a power source or a variety of energy storage systems using the battery cell as an energy storage element. The power consumption device can include but is not limited to mobile phones, tablets, notebook computers, electric toys, electric tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, the electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric plane toys, etc., and the spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0087] In the first aspect of the present application, a battery cell is provided, comprising: 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 sheet, 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 0.02 Ω-5 Ω; a shell comprising a containing space, the electrode assembly being located in the containing space of the shell, the shell comprising an end plate, the end plate being provided with at least one electrode terminal, with reference Figure 1For example, the ratio of the area of the positive electrode terminal 122 on the end plate 121 to the area enclosed by the outer contour of the end plate 121 can be 5%-70%. For example, the ratio of the area of the negative electrode terminal 132 on the end plate 131 to the area enclosed by the outer contour of the end plate 131 can be 5%-70%. In this way, the heat generated by the battery cell during the rate charge and discharge process 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 relatively good rate charge and discharge performance.

[0088] In some embodiments, the shell includes two end plates arranged opposite along the length direction of the battery cell, for example, the first end plate 121 and the second end plate 131.

[0089] For 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.

[0090] For example, the sheet resistance of the positive electrode sheet can be tested by the following method: after disassembling the sheet after discharging the battery to 0% SOC, using a solvent such as dimethyl carbonate to clean the sheet more than three times, 20 parallel samples can be taken along the central axis of the sheet, each sample is symmetrical along the central axis, and each sample size is 4cm x 25cm, wherein the central axis can be parallel to the length direction of the sheet. The 20 parallel samples are tested by using a sheet resistance tester (Yuan Neng Technology, BER2500 model), and the average value is calculated as the sheet resistance of the sheet.

[0091] For example, the ratio of the area of the terminal body of the electrode terminal of a single polarity on the end plate to the area enclosed by the outer contour of the end plate can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%.

[0092] It can be understood that the greater the ratio of the orthographic projection area of the terminal body part of the electrode terminal on the end plate to the area of the surface of the end plate away from the electrode assembly, for example, 80%, 90% or 100%, the greater the overcurrent area of the electrode terminal, and the lower the internal resistance of the electrode terminal. However, since the size of the first limiting part needs to be greater than the size of the terminal body part, so as to play a role in limiting the movement of the electrode terminal, when the ratio of the orthographic projection area of the terminal body part of the electrode terminal of a single polarity on the end plate to the area of the surface of the end plate away from the electrode assembly is too large, for example, greater than 70%, the processing difficulty of the first limiting part is greater, and the fixing effect of the first limiting part on the electrode terminal is poor, and the effect of limiting the position movement of the electrode terminal cannot be well achieved.

[0093] It should be noted that the orthographic projection area of the electrode terminal on the end plate refers to the projection area of the region composed of the outer edge profile of the terminal body part of the electrode terminal. When the end plate includes a plurality of electrode terminals, the orthographic projection area of the terminal body part of the electrode terminal of a single polarity on the end plate refers to the sum of the projection areas of the regions composed of the outer edge profiles of the terminal body parts of the plurality of electrode terminals. The area surrounded by the outer contour of the end plate refers to the projection area of the region composed of the outer edge profile of the end plate.

[0094] In some embodiments, the end plate is provided with a lead-out hole, the electrode terminal includes a terminal body part, a first limiting part and a second limiting part, the terminal body part connects the first limiting part and the second limiting part, the terminal body part is arranged in the lead-out hole, the first limiting part is located on the side of the end plate facing the electrode assembly, and the second limiting part is located on the side of the end plate away from the electrode assembly. Thus, the electrode terminal can be firmly fixed on the end plate and electrically connected with the electrode assembly and the external circuit. In some embodiments, the first limiting part of the electrode terminal can be the inner pole column of the electrode terminal, also known as the inner pole column.

[0095] As an example, the electrode terminal includes a positive electrode terminal 122 and a negative electrode terminal 132.

[0096] In some embodiments, the first end plate 121 is provided with through holes, such as the first through hole 1211 and the second through hole 1231 in Figure 3 The positive electrode terminal 122 includes a terminal body part 1222 and a second limiting part 1223, the terminal body part 1222 connects the second limiting part 1223 and the first limiting part 1221, the terminal body part 1222 sequentially penetrates the second through hole 1231 and the first through hole 1211, and the second limiting part 1223 is located on the side of the first end plate 121 away from the electrode assembly. Thus, the positive electrode terminal can be more firmly fixed on the first end plate.

[0097] In some embodiments, the second end plate 131 is provided with a through hole, such as a third through hole 1311 and a fourth through hole 1331 in Figure 7 Further, the negative electrode terminal 132 includes a terminal body part 1322, a second limiting part 1323, the terminal body part 1322 connecting the second limiting part 1323 and the first limiting part 1321, the terminal body part 1322 sequentially penetrating the fourth through hole 1331 and the third through hole 1311, and the second limiting part 1323 being located on the side of the second end plate 131 facing away from the electrode assembly. In this way, the negative electrode terminal can be more firmly fixed on the second end plate.

[0098] In some embodiments, the ratio of the area of the orthographic projection of the terminal body part of the electrode terminal of a single polarity on the end plate to the area enclosed by the outer contour of the end plate is 15%-65%, or 20%-60%. In this way, the electrode terminal can provide better current-carrying capacity and larger heat dissipation area, and there is sufficient space on the end plate for setting other structural members.

[0099] In some embodiments, the ratio of the area of the orthographic projection of the terminal body part on the end plate to the area of the orthographic projection of the first limiting part on the end plate is 30%-90%. In this way, the internal resistance of the electrode terminal can be reduced, and heat generation can be reduced.

[0100] As an example, the ratio of the area of the orthographic projection of the terminal body part on the end plate to the area of the orthographic projection of the first limiting part on the end plate can be 30%, 40%, 50%, 60%, 70%, 80%, or 90%. The terminal body part is the smallest part of the cross-sectional area of the electrode terminal, and has a greater impact on the resistance of the electrode terminal. By controlling the size of the area of the terminal body part, the internal resistance of the electrode terminal can be effectively reduced, and the current-carrying capacity of the electrode terminal can be improved.

[0101] In some embodiments, the battery cell includes a housing 11, a first cover plate assembly 12, and a second cover plate assembly 13, the housing, the first cover plate assembly, and the second cover plate assembly defining a receiving cavity, the first cover plate assembly including a first end plate 121 and at least one positive electrode terminal 122, the positive terminal body part being electrically connected to the positive electrode terminal 122 through the positive electrode tab part; and / or, the second cover plate assembly including a second end plate 131 and at least one negative electrode terminal 132, the negative terminal body part being electrically connected to the negative electrode terminal 132 through the negative electrode tab part.

[0102] In particular, reference is made to Figure 10The shell 11 has a first opening 111 and a second opening 112 at two ends along a length direction of the shell 11, the length direction of the shell 11 is the same as the length direction of the positive current collector, the first cover plate assembly 12 is adapted to cover the first opening 111, and the second cover plate assembly 13 is adapted to cover the second opening 112, so as to isolate the internal environment of the battery cell from the external environment. The shell, the first cover plate assembly and the second cover plate assembly define a containing cavity, and the electrode assembly is arranged in the containing cavity. The shapes of the first cover plate assembly and the second cover plate assembly can be adapted to the shape of the shell to fit the shell. The first cover plate assembly and the second cover plate assembly can be respectively independently made of a material (such as an aluminum alloy) with certain hardness and strength, so that the first cover plate assembly and the second cover plate assembly have higher strength, thereby reducing the deformation of the first cover plate assembly and the second cover plate assembly when the first cover plate assembly and the second cover plate assembly are pressed, and improving the safety performance of the battery cell.

[0103] In some embodiments, the first cover plate assembly, the second cover plate assembly and the shell can be independent components.

[0104] In some embodiments, the first cover plate assembly, the second cover plate assembly and the shell are integrated. Specifically, the first cover plate assembly, the second cover plate assembly and the shell can form a common connecting surface before other components enter the shell. When it is necessary to encapsulate the interior of the shell, the first cover plate assembly covers the first opening of the shell, and the second cover plate assembly covers the second opening of the shell.

[0105] In some embodiments, with reference to Figures 2-5 The first cover plate assembly 12 includes a first end plate 121 and a positive electrode terminal 122, the positive electrode terminal 122 is arranged on the side of the first end plate 121 close to the electrode assembly, and the first end plate 121 is provided with a first through hole 1211; a first insulating piece 123 is arranged between the first end plate 121 and the positive electrode terminal 122, the first insulating piece 123 is adapted to isolate the electrical connection components in the shell from the first end plate 121, so as to reduce the risk of short circuit, the first insulating piece 123 is provided with a second through hole 1231, and the positive electrode terminal 122 is sequentially arranged in the second through hole 1231 and the first through hole 1211; a first sealing piece 124, a first positioning piece 125, a second insulating piece 126 and a riveting block 127 are sequentially arranged on the side of the first end plate 121 away from the electrode assembly, and the riveting block is adapted to fix the positive electrode terminal 122 on the first end plate 121.

[0106] In some embodiments, with reference to Figures 6-9The second cover plate assembly 13 comprises a second end plate 131 and a negative electrode terminal 132 arranged on a side of the second end plate 131 close to the electrode assembly, and the second end plate 131 is provided with a third through hole 1311; a third insulating piece 133 is arranged between the second end plate 131 and the negative electrode terminal 132, the third insulating piece 133 is adapted to isolate the electrical connection components in the shell from the second end plate 131 to reduce the risk of short circuit, the third insulating piece 133 is provided with a fourth through hole 1331, and the negative electrode terminal 132 is sequentially arranged in the fourth through hole 1331 and the third through hole 1311; a second sealing piece 134, a second positioning piece 135, a fourth insulating piece 136 and the riveting block 127 are sequentially arranged on a side of the second end plate 131 away from the electrode assembly, and the riveting block 127 is adapted to fix the negative electrode terminal 132 on the second end plate 131.

[0107] For example, the first insulating piece 123, the second insulating piece 126, the third insulating piece 133 and the fourth insulating piece 136 can be plastic, rubber or the like independently.

[0108] In some embodiments, referring to Figures 1-5 The first end plate 121 is provided with a liquid injection hole 1212, which can be used for injecting electrolyte; referring to Figures 6-9 The second end plate 131 is provided with a pressure relief portion 137, which can release the pressure inside the shell when the pressure inside the shell exceeds a threshold value.

[0109] For example, the pressure relief portion 137 and the second end plate 131 are two separate components, which are separately formed and then installed together. The pressure relief portion 137 can be a bursting disc, a bursting valve, a safety valve or the like, and the pressure relief portion 137 can be installed on the second end plate 131 by bonding, welding or the like. When the internal pressure of the battery monomer reaches a threshold value, the pressure relief portion 137 opens at least part of the pressure relief hole, and the discharge cutoff inside the battery monomer is discharged through the pressure relief hole to release the pressure inside the battery monomer.

[0110] In some embodiments, referring to Figure 3 and Figure 7 In the direction parallel to the end plate, the cross section of the terminal body portion 1222 / 1322 is a rounded rectangle. In this way, the assembly of the electrode terminal is facilitated.

[0111] In some embodiments, each of the end plates comprises two electrode terminals, and the polarities of the two electrode terminals are the same or opposite. In this way, the current density inside the battery monomer can be effectively dispersed, thereby reducing the current load on a single electrode terminal and helping to reduce the risk of local overheating.

[0112] In some embodiments, when each of the end plates comprises a plurality of electrode terminals, for example, two electrode terminals, the ratio of the area of the orthogonal projection of the terminal body of each of the electrode terminals on the end plate to the area enclosed by the outer contour of the end plate is the same.

[0113] In some embodiments, referring to Figure 13 and Figure 17 each of the end plates comprises two electrode terminals, and the polarities of the two electrode terminals are opposite. In this way, the current density inside the battery monomer 1 can be effectively dispersed, thereby reducing the current load on a single electrode terminal, alleviating the polarization unevenness inside the battery monomer, and reducing the risk of local overheating.

[0114] In some embodiments, each of the end plates comprises two electrode terminals with opposite polarities, and the electrode terminals of a single polarity on different end plates are arranged staggered along the length direction of the battery monomer, or optionally, the electrode terminals of a single polarity on different end plates are arranged diagonally along the length direction of the battery monomer. In this way, it is convenient to electrically connect a plurality of battery monomers. In this way, it is convenient to electrically connect a plurality of battery monomers 1, and it is helpful to alleviate the polarization unevenness inside the battery monomer.

[0115] In some embodiments, the first cover plate assembly 12 comprises one positive electrode terminal 122 and one negative electrode terminal 132; and / or, the second cover plate assembly 13 comprises one positive electrode terminal 122 and one negative electrode terminal 132.

[0116] Specifically, referring to Figures 12-15 , the first cover plate assembly 12 comprises a first end plate 121, the first end plate 121 comprises one positive electrode terminal 122 and one negative electrode terminal 132, two first through holes are arranged on the first cover plate assembly, a first insulating piece 123 is arranged between the first end plate 121 and the positive electrode terminal 122 and the negative electrode terminal 132, two second through holes 1231 are arranged on the first insulating piece 123, the positive electrode terminal 122 is sequentially arranged through the corresponding second through hole 1231 and the first through hole 1211, the negative electrode terminal 132 is sequentially arranged through the corresponding second through hole 1231 and the first through hole 1211, and a first sealing piece 124, a first positioning piece 125, a second insulating piece 126 and a riveting block 127 are sequentially arranged on the side of the first end plate 121 away from the electrode assembly.

[0117] Specifically, referring to Figures 16-19The second cover plate assembly 13 comprises a second end plate 131, the second end plate 131 comprises one positive electrode terminal 122 and one negative electrode terminal 132, the second end plate 131 is provided with two third through holes 1311, the second end plate 131 and the negative electrode terminal 132 and the positive electrode terminal 122 are provided with a second insulating piece 133, the third insulating piece 133 is provided with two fourth through holes 1331, the positive electrode terminal 122 is sequentially arranged in the corresponding fourth through hole 1331 and the third through hole 1311, the negative electrode terminal 132 is sequentially arranged in the corresponding fourth through hole 1331 and the third through hole 1311, and the second end plate 131 is provided with a second sealing piece 134, a second positioning piece 135, a fourth insulating piece 136 and the riveting block 127 in sequence away from the electrode assembly.

[0118] In some embodiments, referring to Figure 21 The electrode assembly is a laminated structure, and the laminated structure comprises a plurality of positive electrode laminas and a plurality of negative electrode laminas arranged in layers, each of the positive electrode laminas comprises the positive current collector, the positive current collector comprises a positive main body part and a positive lug part, each of the negative electrode laminas comprises a negative current collector and a negative lug part, the negative current collector comprises a negative main body part and a negative lug part, the positive main body part is electrically connected with the positive lug part, the positive lug part is electrically connected with the positive terminal, the negative main body part is electrically connected with the negative lug part, and the negative lug part is electrically connected with the negative terminal. Thus, the positive electrode laminas 2, the separator film 4 and the negative electrode laminas 3 can be more fully utilized in the internal space of the battery monomer 1, the internal space waste is reduced, the heat is evenly distributed in the internal space of the battery monomer 1, the heat dissipation efficiency is improved, and the risk of local overheating is reduced.

[0119] In some embodiments, the battery monomer is configured to take 5 min-10.5 min to charge from 10% SOC to 80% SOC. Thus, the battery monomer has better performance in the rate charging and discharging.

[0120] Taking a car as an example, in an actual use scenario, the state of charge (SOC) of the battery of the car is usually between 10%-80%, thus, when the charging time of the battery in the SOC range is short, the user's waiting time for charging can be reduced, and the user's use experience is greatly improved.

[0121] Generally, the battery cell includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the charging and discharging of the battery, active ions are embedded and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuiting of the positive and negative electrodes, while allowing ions to pass through.

[0122] [positive electrode sheet]

[0123] In some embodiments, the sheet resistance of the positive electrode sheet is 0.05 Ω-1 Ω. In this way, the heat generation of the positive electrode sheet during charging and discharging can be reduced.

[0124] In some embodiments, the positive active material layer includes a conductive agent, and the mass fraction of the conductive agent in the positive active material layer is 0.5%-5%. In this way, by adding the conductive agent, a conductive network can be constructed, effectively connecting the positive active material particles, shortening the electron conduction path, improving the overcurrent resistance of the sheet, and further reducing the heat generation of the positive electrode sheet.

[0125] For example, the mass fraction of the conductive agent in the positive active material layer 22 can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%.

[0126] In some embodiments, the positive active material layer includes a conductive agent, and the conductive agent includes carbon nanotubes, and the mass fraction of the carbon nanotubes in the positive active material layer is 0.1%-1.1%. In this way, by adding a small amount of carbon nanotubes, the impedance of the positive electrode sheet can be effectively reduced, and the heat generation can be reduced.

[0127] In this way, by adding a small amount of carbon nanotubes, the impedance of the positive electrode sheet 2 can be effectively reduced, and the heat generation can be reduced.

[0128] For example, the mass fraction of the carbon nanotubes in the positive active material layer 22 can be 0.1%, 0.5%, 1%, or 1.1%.

[0129] Carbon nanotubes have high electron conduction capacity and can form a complex three-dimensional conductive network, improving the interface contact between the positive active material particles and the current collector, significantly reducing the sheet resistance of the positive electrode sheet, and helping to improve the rate charging and discharging performance of the battery.

[0130] In some embodiments, the carbon nanotubes have a tube diameter of 1 nm-16 nm; optionally, 1 nm-8 nm. In this way, the carbon nanotubes have relatively optimal electron conductivity.

[0131] For example, the tube diameter of the carbon nanotubes is 1 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, or 16 nm.

[0132] It should be noted that the tube diameter of the aforementioned carbon nanotube refers to the sum of the inner diameter and the wall thickness of the carbon nanotube.

[0133] As an example, the tube diameter of the carbon nanotube can be tested by the following method: using a scanning electron microscope (SEM), spraying gold on the surface of the sample of the carbon nanotube, directly observing the morphology of the sample and measuring the tube diameter.

[0134] In some embodiments, the conductive agent further includes carbon black. In this way, by mixing the use of conductive agents of different forms and sizes, a more uniform and dense conductive network can be formed between the positive active materials, which is beneficial to reduce the internal resistance of the positive electrode plate 2, improve the charge and discharge efficiency, and reduce the heat generation.

[0135] 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 , 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, Mg, Me includes at least one of Mn, Fe, Co, Ni, M includes at least one of 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, Ce, X includes at least one of S, Si, Cl, B, C, N, and Y includes one or both of O, F. In this way, the lithium-containing phosphate has relatively high ionic conductivity and electronic conductivity, and the structure stability of the lithium-containing phosphate particles is relatively high, and the cycle stability during the charging and discharging process is relatively excellent, which is beneficial to improve the cycle performance of the battery cell.

[0136] The battery will be accompanied by Li deintercalation and consumption during the charging and discharging process, and the molar content of Li is different when the battery is discharged to different states. In the enumeration of the positive active material in the present application, the molar content of Li is the initial state of the material, i.e. the state before feeding. After the positive active material is applied to the battery system and undergoes charging and discharging cycles, the molar content of Li will change.

[0137] In the enumeration of the positive active material for lithium ion batteries in the present application, the molar content of O is only the theoretical state value, and the lattice oxygen release will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0138] In some embodiments, at least part of the surface of the lithium-containing phosphate has a carbon coating layer, and the mass fraction of carbon in the positive electrode active material is 0.7%-1.5% based on the total mass of the lithium-containing phosphate and the carbon coating layer. In this way, 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 of the positive electrode active material.

[0139] For example, the mass fraction of carbon in the positive electrode active material can be 0.7%, 0.9%, 1.1%, 1.3%, or 1.5% based on the total mass of the lithium-containing phosphate and the carbon coating layer.

[0140] For example, the mass fraction of carbon in the positive electrode active material can be tested by the following method: turn on all power switches of the carbon-sulfur analyzer, press the "zero" button, open the oxygen valve of the carbon-sulfur analyzer, adjust the oxygen pressure to 0.02-0.04 MPa. Open the "front oxygen" and "rear control", adjust the flowmeter to about 100 L / h. Add silicon molybdenum powder (about 0.3 g), weighed sample (250 mg), tin particles (0.3 g), and pure iron (1 g) in the crucible in turn, close the crucible. Click the "test" button to start the test, and the test result will be automatically displayed after the test is completed. Record the C content.

[0141] In some embodiments, the powder resistivity of the positive electrode active material is 2 S / cm-60 S / cm, or 2 S / cm-30 S / cm. In this way, it is helpful to reduce the internal resistance of the positive electrode plate and reduce heat generation.

[0142] For example, the powder resistivity of the positive electrode active material can be tested by the following method: according to the test standard GB / T30835-2014, using PRCD1100 powder resistivity meter for testing.

[0143] In some embodiments, the positive electrode active material layer 22 further comprises 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%. In this way, the addition of an appropriate amount of lithium-rich material can not only compensate for the loss of irreversible lithium ions in the battery monomer 1, but also have little effect on the internal resistance of the positive electrode plate 2, which is conducive to reducing heat generation.

[0144] For 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%.

[0145] When the mass fraction of the lithium-rich material in the positive electrode active material layer 22 is within the aforementioned range, both the loss of active lithium ions can be better supplemented, and more positive electrode active material layers can be loaded in the positive electrode active material layer, thereby improving the energy density of the battery cell.

[0146] The formation of the SEI film on the surface of the negative electrode active material during the first charging of the battery, and the rupture and recombination of the SEI during the charging and discharging cycles, all cause irreversible consumption of lithium ions, resulting in a decrease in the first-cycle efficiency and a loss of capacity of the battery cell. By adding the lithium-rich material, the loss of lithium during the preparation of the battery can be pre-supplemented, the capacity decay caused by the loss of lithium can be alleviated or eliminated, and the cycle life of the battery can be prolonged.

[0147] 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 ferrite. In this way, the lithium-rich material can supplement the active lithium consumption during the first charging, and store part of the lithium ions in the negative electrode active material, thereby improving the capacity of the battery cell 1.

[0148] 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 In this way, by controlling the number of active lithium ions per unit area of the positive electrode sheet, the polarization during the rate charging and discharging can be effectively reduced, and the polarization resistance can be reduced.

[0149] 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 mm2 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 .

[0150] As an example, the single-side coating weight of the positive electrode active material layer can be tested by the following method: disassemble the positive electrode tab from the battery cell, take the single-side coated positive electrode tab (if it is a double-side coated positive electrode tab, wipe off the positive electrode active material layer on one side first), punch into a small disc with an area of S1, weigh it, and record it as M1. Then wipe off the positive electrode active material layer of the above weighed positive electrode tab, weigh the weight of the positive electrode current collector, and record it as M0. The single-side coating weight of the positive electrode active material layer = (M1- M0) / S1.

[0151] 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 . In this way, the particles in the positive electrode active material layer 22 are packed more closely, the contact resistance between particles is smaller, which is conducive to reducing the resistance of the positive electrode tab 2 and improving the energy density of the battery cell 1.

[0152] As an example, the compaction density of the positive electrode active material layer corresponding to 100% SOC of the battery cell 1 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 .

[0153] When the compaction density of the positive electrode active material layer is within the above range, the particles in the positive electrode active material layer are packed more closely, and the positive electrode tab has both high energy density and low membrane resistance.

[0154] As an example, the compaction density of the positive electrode active material layer corresponding to 100% SOC of the battery cell can be tested by the following method: the battery cell is charged at 1 / 3C constant current to 3.8V, and charged at 3.8V constant voltage to 0.05C, the positive electrode plate is disassembled from the battery cell, for example, the single-sided coated positive electrode plate (if it is a double-sided coated plate, the positive electrode active material layer of one side can be wiped off first), punched into a small disc with an area of S1, weighed and recorded as M1, and its thickness H1 is measured. Then wipe off the positive electrode active material layer of the above weighed positive electrode plate, weigh the weight of the positive electrode current collector and record it as M0, and 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 compaction 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.

[0155] In some embodiments, the positive electrode active material layer 22 has a coating length of 200mm-700mm in the length direction of the positive electrode current collector 21. Figure 20 In some embodiments, the positive electrode active material layer 22 has a coating length of 200mm-700mm in the length direction of the positive electrode current collector 21.

[0156] As an example, the positive electrode active material layer 22 has a coating length of 200mm, 300mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm, 650mm or 700mm in the length direction of the positive electrode current collector 21.

[0157] When the coating length of the positive electrode active material layer 22 is 200mm-700mm, the battery cell 1 can have a long strip structure, and the long strip battery cell can be directly arranged and combined to form a battery pack, eliminating the intermediate module structure, thereby facilitating the close arrangement of multiple battery cells 1 in the battery device, reducing the excess gap and unnecessary structural members, thereby improving the space utilization of the battery device and increasing the energy density of the battery device.

[0158] In some embodiments, the positive electrode current collector 21 includes a positive electrode main body part 211 and at least one positive electrode tab part 212, and the positive electrode main body part 211 is connected to the positive electrode tab part 212. Thus, the positive electrode plate 2 can be electrically connected to the electrode terminal through the corresponding tab part.

[0159] In some embodiments, the electrode terminal and the positive electrode tab part can be electrically connected through a conversion sheet. Specifically, the first limiting part 1221 of the electrode terminal can be electrically connected to the positive electrode tab part through the conversion sheet. Thus, the welding quality and connection reliability between the electrode terminal and the tab part can be significantly improved.

[0160] When using an adapter plate to achieve electrical connection between the electrode terminals and the positive electrode tab, the shape and size of the adapter plate can be adjusted as needed to adapt to different distances and positions. Furthermore, the welding process of the adapter plate has fewer defects, which can help to distribute the current more evenly, reduce local overheating and potential difference, and improve the fast charging performance of the battery.

[0161] In some embodiments, the electrode terminals can be directly electrically connected to the positive electrode tab. Specifically, the first limiting portion 1221 of the electrode terminal can be directly electrically connected to the positive electrode tab. This helps to reduce the structural complexity inside the battery cell, shrink the battery cell size, and increase the energy density.

[0162] When the electrode terminals are directly electrically connected to the positive electrode tab, the connectors are eliminated, simplifying the internal structure of the battery cell, reducing assembly steps, and lowering the overall manufacturing cost.

[0163] In some embodiments, the ratio of the number of positive electrode tabs to the number of positive electrode current collectors is 1-2. This helps to disperse the current density on the current collectors and helps to reduce the risk of localized overheating.

[0164] Electrical connections are achieved between the tabs and terminals, thereby outputting the current inside the battery cell to the external circuit. The ratio of the number of positive electrode tabs 212 to the number of positive electrode current collectors 21 corresponds to the number of positive electrode tabs on each positive electrode current collector. The number of positive electrode tabs on a single positive electrode current collector corresponds to the number of electrode terminals on the end plate. Thus, by matching the design of multiple tabs with the design of multiple electrode terminals, multiple transfer paths for electrons can be realized within the electrode assembly, shortening the electron transfer path, reducing the internal resistance of the battery cell, and reducing heat generation.

[0165] As an example, refer to Figures 22-24 The ratio of the number of positive electrode tabs 212 to the number of positive electrode current collectors 21 can be 1, 2, 3 or 4.

[0166] As an example, refer to Figure 23 The positive current collector includes the positive electrode body portion 211 and a plurality of positive electrode tabs 212, with at least two positive electrode tabs 212 located on opposite sides of the positive electrode body portion 211. Similarly, the negative current collector may include the negative electrode body portion and a plurality of negative electrode tabs, with at least two negative electrode tabs located on opposite sides of the negative electrode body portion. This provides a more uniform heat distribution and reduces tab deformation caused by excessive force on one side.

[0167] As an example, refer to Figure 24The positive electrode current collector includes a positive electrode main body portion 211 and a plurality of positive electrode tab portions 212 arranged at intervals in the length direction of the positive electrode current collector. Similarly, the negative electrode current collector can also include a negative electrode main body portion 311 and a plurality of negative electrode tab portions 312 arranged at intervals in the length direction of the negative electrode current collector.

[0168] When the positive electrode current collector includes a plurality of positive electrode tab portions 212 and the negative electrode current collector includes a plurality of negative electrode tab portions 312, the transmission path of electrons between the positive electrode tab portions and the negative electrode tab portions is short, which can reduce the heat generation of the battery and improve the fast charging performance.

[0169] In some embodiments, the total width of the positive electrode tab portions in the width direction of the positive electrode main body portion accounts for 80%-100% of the total width of the positive electrode main body portion. In this way, by using a tab structure with a larger area, the overcurrent capacity of the tab portion can be effectively improved, and the temperature rise of the battery cell during fast charging can be alleviated.

[0170] As an example, the total width of the positive electrode tab portions 212 accounts for 80%, 85%, 90%, 95%, or 100% of the total width of the positive electrode main body portion 211.

[0171] When the battery cell is subjected to high-rate charging and discharging, the current and voltage inside the battery cell will increase accordingly, and the current passing through the tab will also increase. A larger positive electrode tab area means a 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, i.e., it has a stronger overcurrent capacity. On the other hand, when the resistance of the tab is low, the heat generated by the resistance loss after the current flows through the tab can be reduced, which reduces the heat generation of the battery under a large current and indirectly improves the heat dissipation efficiency of the battery.

[0172] In some specific embodiments, with reference to Figure 22 For example, taking the preparation of an electrode assembly using a lamination process, the positive electrode tab used is a rectangle. At this time, one of the short sides of the positive electrode current collector has a positive electrode tab portion 212 extending in the length direction of the positive electrode current collector, and the width of the positive electrode tab portion is W1. At this time, the total width of the positive electrode tab portion is equal to the width W1 of the positive electrode tab portion, and the total width V1 of the positive electrode main body portion is the width of the positive electrode current collector. Similarly, the corresponding negative electrode current collector can also have a similar structure, which will not be described here.

[0173] In some specific embodiments, with reference to Figure 23For example, when the electrode assembly is prepared by the stacking process, the positive electrode tab used is rectangular, and at this time, the two short sides of the positive current collector each have a positive tab 212 extending in the length direction of the positive current collector, and the two positive tabs 212 extend in opposite directions. The widths W1 of the plurality of positive tabs 212 can be the same or different, and at this time, the total width of the positive tabs is the sum of the widths W1 of the plurality of positive tabs, and the total width V1 of the positive main body is the width of the positive current collector. Similarly, the corresponding negative current collector can also have a similar structure, which will not be described here.

[0174] In some embodiments, with reference to Figure 24 For example, when the electrode assembly is prepared by the stacking process, the positive electrode tab used is rectangular, and at this time, one of the two long sides of the positive current collector has a plurality of positive tabs 212 extending in the width direction of the positive current collector, and the plurality of positive tabs 212 are arranged at intervals in the length direction of the positive current collector. The width of each positive tab can be the same or different. For example, when there are three positive tabs, the widths of the three positive tabs 212 are L1, L2, and L3, respectively, and L1, L2, and L3 can all be the same, all be different, or any two be the same. At this time, the total width of the positive tabs is the sum of the widths of the plurality of positive tabs, i.e., W1=L1+L2+L3, and the total width V1 of the positive main body is the length of the positive current collector. Similarly, the corresponding negative current collector can also have a similar structure, and at this time, the total width of the negative tabs is the sum of the widths of the plurality of negative tabs, and the width of the negative main body is the length of the negative current collector.

[0175] It should be noted that when the electrode assembly is prepared by the stacking process, the electrode assembly can include a plurality of layers of positive electrode tabs / isolation films / negative electrode tabs / isolation film structures arranged continuously. At this time, the ratio of the total width of the positive tabs to the total width V1 of the positive main body corresponds to the ratio of the width of the positive tabs to the width of the positive main body in any positive electrode tab, and similarly, the ratio of the total width of the negative tabs to the total width V2 of the negative main body corresponds to the ratio of the width of the negative tabs to the width of the negative main body in any negative electrode tab.

[0176] In some embodiments, with reference to Figure 25In the electrode assembly manufactured by the lamination process, the plurality of positive tab portions 212 can be misaligned (at least partially overlap between adjacent positive tab portions), in which case the total width W3 of the positive tab portions 212 can be considered as the total width of the plurality of positive tab portions 212 after being stacked after the lamination of the positive electrode sheet, the negative electrode sheet, and the separator. The total width V1 of the positive main portion is the width of the positive current collector. Similarly, the plurality of negative tab portions 312 can also be misaligned (at least partially overlap between adjacent negative tab portions), in which case the total width W4 of the negative tab portions 312 can be considered as the total width of the plurality of negative tab portions 22 after being stacked after the lamination of the positive electrode sheet, the negative electrode sheet, and the separator. The total width V2 of the negative main portion is the width of the negative current collector.

[0177] In some embodiments, the width and the total width of the positive tab portion and the negative tab portion can be the same. When the width of the positive current collector and the negative current collector is also the same, the ratio of the total width of the positive tab portion to the total width of the positive main portion in the width direction of the positive main portion is the same as the ratio of the total width of the negative tab portion to the total width of the negative main portion in the width direction of the negative main portion.

[0178] As an example, the positive current collector has two surfaces opposite in the thickness direction thereof, and the positive active material layer is provided on either one or both of the two opposite surfaces of the positive current collector.

[0179] In some embodiments, the positive current collector can be a metal foil or a composite current collector. For example, as the metal foil, an 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 (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0180] In some embodiments, the positive active material layer can also optionally include a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic resin.

[0181] In some embodiments, the positive active material layer can also optionally include a conductive agent. As an example, the conductive agent can include at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0182] In some embodiments, the positive electrode sheet can be prepared by dispersing the 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 (e.g., N-methyl pyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying, cold pressing, etc., the positive electrode sheet can be obtained.

[0183] In some embodiments, the positive electrode sheet can be prepared by dispersing the 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 (e.g., N-methyl pyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying, cold pressing, etc., the positive electrode sheet can be obtained.

[0184] In some embodiments, the positive electrode sheet can be prepared by dispersing the positive electrode active material, the conductive agent, the binder, and any other components in a solvent (e.g., N-methyl pyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying, cold pressing, etc., to form a positive electrode active material layer, and then using a spraying, secondary coating, or other method to composite the lithium-rich material with the positive electrode active material layer on the surface of the positive electrode active material layer.

[0185] [Negative electrode sheet]

[0186] 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, and the negative electrode current collector includes a negative electrode main body portion 311 and at least one negative electrode tab portion 312, and the negative electrode main body portion 311 is connected to the negative electrode tab portion 312. In this way, the negative electrode sheet 3 can be electrically connected to the electrode terminal through the corresponding tab portion.

[0187] In some embodiments, the electrode terminal can be electrically connected to the negative electrode tab portion through a transfer piece. Specifically, the first limiting portion 1321 of the electrode terminal can be electrically connected to the negative electrode tab portion through the transfer piece. In this way, the welding quality and connection reliability between the electrode terminal and the tab portion can be significantly improved.

[0188] When the electrode terminal is electrically connected to the negative electrode tab portion through the transfer piece, the shape and size of the transfer piece can be adjusted as needed to adapt to different distances and positions, and the transfer 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.

[0189] In some embodiments, the electrode terminal can be directly electrically connected with the negative tab. Specifically, the first limiting portion 1321 of the electrode terminal can be directly electrically connected with the negative tab. In this way, the structural complexity inside the battery cell is reduced, the volume of the battery cell is reduced, and the energy density is improved.

[0190] When the electrode terminal is directly electrically connected with the negative tab, the connecting member is omitted, the internal structure of the battery cell is simplified, the assembly steps are reduced, and the overall manufacturing cost is reduced.

[0191] In some embodiments, the ratio of the number of negative tabs to the number of negative current collectors is 1-2. In this way, the current density on the current collector is dispersed, and the risk of local overheating is reduced.

[0192] In some embodiments, the ratio of the number of negative tabs 312 to the number of negative current collectors can be 1, 2, 3, or 4.

[0193] In some embodiments, along the width direction of the negative main body portion, the total width of the negative tab 312 accounts for 80%-100% of the total width of the main body portion 311. In this way, by adopting a tab structure with a larger area, the overcurrent capacity of the tab portion can be effectively improved, and the temperature rise of the battery cell 1 during fast charging can be alleviated.

[0194] As an example, the total width of the negative tab 312 accounts for 80%, 85%, 90%, 95%, or 100% of the total width of the negative main body portion 311.

[0195] When the battery cell is subjected to high-rate charging and discharging, the current and voltage inside the battery cell will increase accordingly, and the current through the tab will increase. A larger negative tab area means a 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, i.e., it has a stronger overcurrent capacity. On the other hand, when the resistance of the tab is low, the heat generated by the resistance loss after the current flows 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.

[0196] As an example, the negative current collector has two opposite surfaces in the thickness direction thereof, and the negative active material layer is disposed on any one or both of the two opposite surfaces of the negative current collector.

[0197] In some embodiments, the negative current collector can employ a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be employed. 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 (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer (e.g., a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0198] In some embodiments, the negative active material can employ a negative active material for a battery known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate, etc. The silicon-based material includes at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material includes at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material for a battery can also be used. These negative active materials can be used alone or in combination of two or more.

[0199] In some embodiments, the negative active material layer can further 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).

[0200] In some embodiments, the negative active material layer can further optionally include a conductive agent. The conductive agent includes at least one of super P, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0201] In some embodiments, the negative active material layer can further optionally include other additives, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) etc.

[0202] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-described components for preparing the negative electrode sheet, such as the negative active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry, coating the negative electrode slurry on the negative current collector, and performing drying, cold pressing, etc.

[0203] [Electrolyte]

[0204] The electrolyte plays a role of conducting ions between the positive electrode sheet and the negative electrode sheet. The type of the electrolyte is not specifically limited in the present application, and can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0205] In some embodiments, the electrolyte employs an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0206] In some embodiments, the electrolyte solution has an electrical conductivity of 10 mS / cm-18 mS / cm at room temperature. In this way, the migration rate of lithium ions in the electrolyte solution is high, and the internal resistance of the battery cell 1 can be further reduced.

[0207] For example, the test method for the electrical conductivity of the electrolyte solution can refer to HG-T 4067-2015.

[0208] In some embodiments, the electrolyte solution has a viscosity of 1.5 mPa·s-5.5 mPa·s at room temperature. In this way, the migration rate of lithium ions in the electrolyte solution is high.

[0209] For example, the viscosity of the electrolyte 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.

[0210] For example, the viscosity of the electrolyte solution can be tested by the following method: the viscosity is tested by a viscometer. According to the national standard GB / T10247-2008, when the rotor rotates in the sample at a constant speed, the shear force received by the spring produces a torque, and the torque is proportional to the viscosity, so that the viscosity value is obtained.

[0211] In some embodiments, the electrolyte solution includes a chain carboxylate solvent. In this way, the chain carboxylate solvent can improve the solubility of the electrolyte lithium salt, thereby improving the migration rate of lithium ions in the electrolyte solution.

[0212] The chain carboxylate solvent has low viscosity, and thus the overall viscosity of the electrolyte solution mainly composed of organic solvents is low. The intermolecular interaction force in the low-viscosity electrolyte solution is weak, and the intermolecular motion is more free, so that the diffusion and migration speed of lithium ions in the electrolyte solution is accelerated. Further, when the battery cell is subjected to rapid charging and discharging, concentration polarization occurs inside the battery. When the ion migration rate of the electrolyte solution is high, the concentration polarization inside the battery can be alleviated. The aforementioned low-viscosity electrolyte solution can effectively reduce the concentration polarization by improving the ion migration rate, and improve the rapid charging performance of the battery.

[0213] As an example, the qualitative analysis method of the chain carboxylate solvent can employ gas chromatography-ion chromatography.

[0214] In some embodiments, the chain carboxylate solvent satisfies Formula I:

[0215] Formula I, wherein R1 includes at least one of a hydrogen atom, a C1-C5 alkyl group, a C1-C5 halogenated alkyl group, and R2 includes at least one of a C1-C5 alkyl group, a C1-C5 halogenated alkyl group. Thus, by employing the aforementioned chain carboxylate solvent, the viscosity and conductivity of the electrolyte can be controlled within an appropriate range.

[0216] 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.

[0217] 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.

[0218] In some embodiments, 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, Formula I-8.

[0219] The chain carboxylate has good lithium salt solubility, which can increase the conductivity of the electrolyte, accelerate the migration rate of lithium ions inside the battery, and improve the charge and discharge efficiency of the battery. Moreover, the chain carboxylate exhibits 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.

[0220] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobisoxalate borate, lithium bisoxalate borate, lithium difluorobisoxalate phosphate, and lithium tetrafluorobisoxalate phosphate.

[0221] In some embodiments, the electrolyte can optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive capable of improving certain properties of the battery, such as an additive for improving the overcharge performance of the battery, an additive for improving the high-temperature or low-temperature performance of the battery, etc.

[0222] [Separator film]

[0223] The type of the separation film is not particularly limited, and any known porous structure separation film having good chemical stability and mechanical stability can be used.

[0224] In some embodiments, the material of the separation film includes at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separation film can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separation film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0225] In a second aspect of the present application, a battery device is provided, which includes at least one of a battery module, a battery pack, and an energy storage device, and includes the aforementioned battery cell. The battery device has all the features and advantages of the aforementioned battery cell, and will not be described here.

[0226] The battery device mentioned in the embodiments of the present application can include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can include a plurality of battery cells connected in series, in parallel, or in a mixed connection through a busbar component.

[0227] In some embodiments, the battery cell assembly is generally formed by arranging a plurality of battery cells.

[0228] As an example, the battery cell assembly can be a battery module formed by arranging and fixing a plurality of battery cells into an independent module. As an example, the battery module can be formed by bundling a plurality of battery cells with a cable tie.

[0229] In some embodiments, the battery device can be a battery pack including a box and one or more battery cell assemblies accommodated in the box.

[0230] As an example, the battery cell assembly can also be accommodated in the box by directly fixing a plurality of battery cells to the box.

[0231] As an example, the box can include a first box and a second box. The first box and the second box are fastened so that an enclosed space is formed inside the box to accommodate the battery cell assembly. Here, enclosed means covered or closed, which can be sealed or unsealed. The first box can be a top cover or a bottom plate.

[0232] As an example, the box can 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 an enclosed space is formed inside the box to accommodate the battery cell assembly.

[0233] In some embodiments, the case can be part of a chassis structure of the vehicle. For example, portions of the case can become at least part of a floor of the vehicle, or portions of the case can become at least part of cross members and longitudinal members of the vehicle.

[0234] In a third aspect of the present application, a power consuming device is provided, which comprises the aforementioned battery cell. Thus, the power consuming device has all the features and advantages of the aforementioned battery cell, which will not be repeated here.

[0235] The aforementioned battery cell or battery pack can be used as a power source of the power consuming device, or as an energy storage unit of the power consuming device. The power consuming device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0236] As the power consuming device, the battery cell or battery pack can be selected according to the use requirements thereof.

[0237] Figure 26 is a power consuming device as an example. The power consuming 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 power consuming device for the battery, a battery pack or a battery module can be used.

[0238] The power consuming device as another example can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and a battery cell can be used as a power source.

[0239] The scheme 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. If the specific technology or condition is not specified in the embodiments, it is performed according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained from the market.

[0240] Example 1

[0241] 1. Positive electrode tab

[0242] The positive electrode tab comprises a positive electrode current collector aluminum foil, and the aluminum foil has a positive electrode active material layer on both surfaces. The compaction density of the positive electrode active material layer is 2.65 g / cm 3 at 100% SOC. The single-sided positive electrode active material layer coating weight is 260 mg / 1540.25 mm 2The coating length of the positive active material layer in the length direction of the positive current collector is 585 mm, and the total width of the positive tab portion accounts for 80% of the total width of the positive main body portion in the width direction of the positive main body portion.

[0243] The positive active material layer includes, based on the total mass of the single-sided positive active material layer, 95.4% of a lithium iron phosphate material (the mass fraction of carbon elements in the positive active material is 1.1% based on the total mass of the lithium-containing phosphate and the carbon coating layer, and the powder resistivity of the positive active material is 10 S / m), 0.3% of carbon nanotubes (the tube diameter of the carbon nanotubes is 8 nm), 1.7% of a lithium supplement lithium ferrite, 0.4% of a conductive agent carbon black, and 2.2% of a binder polyvinylidene fluoride (PVDF), and the lithium iron phosphate has a carbon coating layer on the surface, and the mass fraction of the carbon coating layer based on the total mass of the lithium iron phosphate is 1.18%. The membrane resistance of the positive electrode sheet is 0.1 Ω.

[0244] 2. Negative electrode sheet

[0245] The negative electrode sheet includes a negative current collector copper foil, and the coating weight of the single-sided negative active material layer is 123 mg / cm 2 The total width of the negative tab portion accounts for 80% of the total width of the negative main body portion in the width direction of the negative main body portion. Based on the total mass of the single-sided negative active material layer, the negative active material layer includes, by mass fraction, 96% of artificial graphite, 1.1% of a conductive agent carbon black, 1.4% of a binder styrene-butadiene rubber (SBR), and 1.5% of a thickening agent sodium carboxymethyl cellulose (CMC-Na).

[0246] 3. Electrolyte

[0247] The electrolyte includes a solvent and an electrolyte salt, the solvent includes methyl acetate or ethyl acetate, the electrolyte salt is lithium hexafluorophosphate and lithium bisfluorosulfonylimide salt, and the concentration of the electrolyte salt in the electrolyte is 1.0 mol / L. 1. The conductivity of the electrolyte at room temperature is 11 S / m, and the viscosity of the electrolyte at room temperature is 3.5 mPa·s.

[0248] 4. Separation film

[0249] The separation film is a porous polypropylene film.

[0250] 5. Preparation of battery monomer

[0251] The battery cell comprises a shell (the shell length 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, and the electrode assembly and the electrolyte are arranged in the shell. The electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator, the electrode assembly is a laminated structure, and the separator is arranged between the positive electrode sheet and the negative electrode sheet. The shell comprises two end plates arranged opposite along the length direction of the battery cell, the first cover plate assembly adopts the structure as shown in Figure 2 , and the second cover plate assembly adopts the structure as shown in Figure 6 , wherein the ratio of the area of the positive projection of the terminal main body part of the electrode terminal on the end plate to the area of the side surface of the end plate away from the electrode assembly is 5%.

[0252] The differences between the remaining examples, the comparative examples and example 1 are shown in Table 1. In example 7, the first cover plate assembly adopts the structure as shown in Figure 12 , and the second cover plate assembly adopts the structure as shown in Figure 16 .

[0253] The battery cell in the foregoing examples and comparative examples is subjected to fast charging performance test, and the maximum temperature of the top cover in the fast charging performance test process is monitored. The test method is as follows, and the test results are shown in Table 1.

[0254] The cycle performance under fast charging condition (45℃@80%SOH): under the environment temperature of 45℃, the battery cell is charged to 3.65V by Stepcharge, charged to 0.05C by constant voltage, rested for 30min, discharged to 2.5V by 0.5C constant current, rested for 30min, which is one charge-discharge cycle, and the above charge-discharge cycle is repeated until the capacity of the battery cell is 80% of the initial capacity, the number of charge-discharge cycles is obtained, that is, the fast charging cycle performance of the battery cell, wherein,

[0255] Step charge is charging from 0% SOC to 10% SOC at 1C constant current, from 10% SOC to 15% SOC at 7.0C constant current, from 15% SOC to 20% SOC at 7.0C constant current, from 20% SOC to 25% SOC at 7.0C constant current, from 25% SOC to 30% SOC at 7.0C constant current, from 30% SOC to 35% SOC at 6.2C constant current, from 35% SOC to 40% SOC at 5.7C constant current, from 40% SOC to 45% SOC at 5.2C constant current, from 45% SOC to 50% SOC at 4.8C constant current, from 50% SOC to 55% SOC at 4.6C constant current, from 55% SOC to 60% SOC at 4.4C constant current, from 60% SOC to 65% SOC at 4.2C constant current, from 65% SOC to 70% SOC at 3.9C constant current, from 70% SOC to 75% SOC at 3.5C constant current, from 75% SOC to 80% SOC at 3.0C constant current, and from 80% SOC to 100% SOC at 0.33C constant current.

[0256] Table 1

[0257]

[0258] The test results show that the battery cell in the application can effectively reduce the heat generation in the process of rate charge and discharge, so that the battery cell can maintain a relatively stable temperature in the process of rate charge and discharge, and the battery cell has a relatively optimal rate charge and discharge performance.

[0259] Specifically, the ratio of the area of the orthographic projection of the terminal body part of the single-polarity electrode terminal on the end plate to the area of the surface of the side of the end plate away from the electrode assembly is different in Examples 1-2, the electrode terminal has a larger overcurrent area and a smaller internal resistance, and the battery cell has a relatively optimal cycle performance under fast charging conditions.

[0260] The ratio of the area of the orthographic projection of the terminal body part on the end plate to the area of the orthographic projection of the first limiting part on the end plate is different in Examples 3-5, the electrode terminal can provide a relatively optimal overcurrent capacity and a larger heat dissipation area, and the battery cell has a relatively optimal cycle performance under fast charging conditions.

[0261] The membrane resistance of the positive electrode tab is lower in Example 6, the internal resistance of the positive electrode tab is smaller, the conduction path of electrons in the positive active material layer is shorter, and the positive electrode tab generates less heat under fast charging conditions.

[0262] The two electrode terminals of different polarities included in each end plate assembly in Example 7 can effectively disperse the current density inside the battery monomer, thereby reducing the current load on a single electrode terminal, relieving the polarization unevenness inside the battery monomer, reducing the risk of local overheating, and improving the cycle performance under fast charging conditions.

[0263] Comparative Examples 1-3 show that when the film resistance of the positive electrode tab and / or the size of the terminal body part does not meet the requirements, the cycle performance of the battery monomer under fast charging conditions is poor, and the temperature rise is more obvious.

[0264] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same technical idea and playing the same role and effect within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art are applied to the embodiments, and other ways constructed by combining part of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A battery cell, characterized in that, include: An electrode assembly, the electrode assembly including a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer located on at least one side of the positive electrode sheet, the positive active material layer including a positive active material, the positive active material including a lithium phosphate, wherein the film resistance of the positive electrode sheet is 0.02Ω-5Ω; The housing includes a receiving space, the electrode assembly is located within the receiving space of the housing, the housing includes an end plate, the end plate is provided with at least one electrode terminal, the electrode terminal includes a terminal body portion, and the ratio of the orthographic projection area of ​​the terminal body portion of the single polarity electrode terminal on the end plate to the area enclosed by the outer contour of the end plate is 8%-70%; The end plate is provided with a lead-out hole. The electrode terminal includes a first limiting part and a second limiting part. The terminal body part is connected to the first limiting part and the second limiting part. The terminal body part passes through the lead-out hole. The first limiting part is located on the side of the end plate facing the electrode assembly, and the second limiting part is located on the side of the end plate away from the electrode assembly. The ratio of the orthographic projection area of ​​the terminal body part on the end plate to the orthographic projection area of ​​the first limiting part on the end plate is 30%-90%.

2. The battery cell according to claim 1, characterized in that, The film resistance of the positive electrode is 0.05Ω-1Ω.

3. The battery cell according to claim 1, characterized in that, The ratio of the projected area of ​​the main body of the electrode terminal of the single polarity on the end plate to the area enclosed by the outer contour of the end plate is 15%-65%.

4. The battery cell according to claim 1, characterized in that, The ratio of the projected area of ​​the main body of the electrode terminal of the single polarity on the end plate to the area enclosed by the outer contour of the end plate is 20%-60%.

5. 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 0.5%-5%.

6. The battery cell according to claim 1, characterized in that, The positive electrode active material layer includes a conductive agent, which includes carbon nanotubes, and the mass fraction of carbon nanotubes in the positive electrode active material layer is 0.1%-1.1%.

7. The battery cell according to claim 6, characterized in that, The diameter of the carbon nanotubes is 1nm-16nm.

8. The battery cell according to claim 6, characterized in that, The diameter of the carbon nanotubes is 1nm-8nm.

9. The battery cell according to claim 5, characterized in that, The conductive agent also includes carbon black.

10. 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 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 S, Si, Cl, B, C, and N, and Y includes one or two of O and F.

11. The battery cell according to claim 1, characterized in that, The lithium phosphate has at least a portion of its surface covered with a carbon coating layer, and the mass fraction of carbon in the positive electrode active material is 0.7%-1.5% based on the total mass of the lithium phosphate and the carbon coating layer.

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

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

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

15. The battery cell according to claim 14, characterized in that, The lithium-rich material includes at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, lithium tartrate, trilithium citrate, lithium nickel oxide, and lithium ferrite.

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

17. The battery cell according to claim 1, characterized in that, When the battery cell is configured at 100% SOC, the compaction density of the positive electrode active material layer is 2.50 g / cm³. 3 -2.80g / cm 3 .

18. 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 200mm-700mm.

19. The battery cell according to claim 1, characterized in that, Along the direction parallel to the end plate, the cross-section of the terminal body is a rounded rectangle.

20. The battery cell according to claim 1, characterized in that, Each of the end plates includes two electrode terminals, the two electrode terminals having the same polarity or the two electrode terminals having opposite polarities.

21. The battery cell according to claim 20, characterized in that, Each of the end plates includes two electrode terminals with opposite polarities, and the electrode terminals of single polarity on different end plates are staggered along the length of the battery cell.

22. The battery cell according to claim 21, characterized in that, The electrode terminals of different polarities on the end plates are arranged diagonally along the length of the battery cell.

23. The battery cell according to claim 1, characterized in that, The electrode assembly is a stacked structure, which includes multiple positive electrode plates and multiple negative electrode plates stacked together. Each positive electrode plate includes a positive current collector, which includes a positive electrode body and a positive electrode tab. Each negative electrode plate includes a negative current collector and a negative electrode tab, which includes a negative electrode body and a negative electrode tab. The positive electrode body is electrically connected to the positive electrode tab, the positive electrode tab is electrically connected to the positive terminal, the negative electrode body is electrically connected to the negative electrode tab, and the negative electrode tab is electrically connected to the negative terminal.

24. The battery cell according to claim 23, characterized in that, The ratio of the number of positive electrode tabs to the number of positive electrode current collectors is 1-2; and / or, the ratio of the number of negative electrode tabs to the number of negative electrode current collectors is 1-2.

25. The battery cell according to claim 24, characterized in that, Along the width direction of the positive electrode body portion, the total width of the positive electrode tab portion accounts for 80%-100% of the total width of the positive electrode body portion; and / or, along the width direction of the negative electrode body portion, the total width of the negative electrode tab portion accounts for 80%-100% of the total width of the negative electrode body portion.

26. The battery cell according to claim 1, characterized in that, include: The electrolyte has a conductivity of 10 mS / cm to 18 mS / cm at room temperature.

27. The battery cell according to claim 26, characterized in that, The viscosity of the electrolyte at room temperature is 1.5 mPa·s-5.5 mPa·s.

28. The battery cell according to claim 26, characterized in that, The electrolyte includes chain-like carboxylic acid ester solvents.

29. The battery cell according to claim 28, characterized in that, The chain-like carboxylic acid ester solvent satisfies Formula I: Formula I, Wherein, R1 includes at least one of hydrogen atom, C1-C5 alkyl group, and C1-C5 haloalkyl group. R2 includes at least one of C1-C5 alkyl groups and C1-C5 haloalkyl groups.

30. The battery cell according to claim 29, characterized in that, The chain-like carboxylic acid 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.

31. The battery cell according to any one of claims 1-30, characterized in that, The battery cell is configured to charge from 10% SOC to 80% SOC in 5 min to 10.5 min.

32. A battery device, characterized in that, The battery device includes the battery cell of any one of claims 1-31, and the battery device includes at least one of battery module, battery pack, and energy storage device.

33. An electrical appliance, characterized in that, Includes the battery cell described in any one of claims 1-31.

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