Battery cell, battery device, and electric device

Abstract

The present application provides a battery cell, a battery device, and an electric device. The battery cell comprises a casing and an electrode assembly inside the casing, wherein the electrode assembly comprises a positive electrode sheet, a negative electrode sheet, and a separator between the two electrode sheets. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer provided on at least one side of the positive electrode current collector; the positive electrode active layer comprises a positive electrode active material; and the positive electrode active material comprises a nickel-containing lithium transition metal oxide and a lithium-containing phosphate, wherein the molar amount of Ni in the nickel-containing lithium transition metal oxide accounts for 70% to 95% of the total molar amount of the transition metal. The positive electrode active material comprises Ni, Co, Mn, Fe and Li, and the ratio of the mass of Ni in the positive electrode active material to the total mass of Fe and Mn is between 0.15-2.

Description

Battery cell, battery device and electric device Cross-reference to related applications

[0001] This application claims priority to Chinese Patent Application No. 202411087369.0, filed on August 8, 2024, entitled “Battery cell, battery device and electric device”, and to Chinese Patent Application No. 202411270897.X, filed on September 11, 2024, entitled “Battery cell, battery device and electric device”, the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a battery cell, a battery device and an electric device. BACKGROUND

[0003] With the popularity and development of electric vehicles, the performance requirements of battery devices are gradually increasing. Currently, not only is it necessary to have high energy density and fast charging rate to reduce the range anxiety of users, but it is also necessary to have high cycle stability to improve the service life and safety performance of the battery.

[0004] However, when the energy density of the battery device is high, the electrodes are in a high lithium intercalation or delithiation state, which often leads to a decrease in battery stability, causing positive electrode structure degradation, side reactions at the interface, and dramatic changes in negative electrode volume, etc. Therefore, how to improve the cycle performance while increasing the energy density of the battery device is one of the key targets of current battery research. SUMMARY

[0005] The present application provides a battery cell, a battery device and an electric device, which can improve the cycle performance while achieving high electrode energy density.

[0006] A first aspect of the present application provides a battery cell, comprising a shell and an electrode assembly located inside the shell, the electrode assembly comprising a positive electrode sheet, a negative electrode sheet, and a separator film located between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on at least one side of the negative electrode current collector, the negative electrode active layer comprising a negative electrode active material, the negative electrode active material comprising graphite, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active layer arranged on at least one side of the positive electrode current collector, the positive electrode active layer comprising a positive electrode active material, the positive electrode active material comprising a lithium transition metal oxide containing nickel and a lithium-containing phosphate, the molar amount of Ni element in the lithium transition metal oxide containing nickel accounting for 70% to 95% of the total molar amount of transition metals; the lithium-containing phosphate comprising Mn and Fe elements, and the ratio of the mass of Ni element in the positive electrode active material to the sum of the mass of Fe element and Mn element in the positive electrode active material being between 0.15 and 2.

[0007] In any embodiment of the first aspect, the ratio of the mass of Ni element in the positive electrode active material to the sum of the mass of Fe element and Mn element in the positive electrode active material is between 0.55 and 1.42.

[0008] In any embodiment of the first aspect, the mass content of the lithium-containing phosphate in the positive electrode active material is 50%-90%, optionally 50%-70%.

[0009] In any embodiment of the first aspect, the molar amount of Ni element in the lithium-containing transition metal oxide containing Ni accounts for 80%-95% of the total molar amount of Ni, Co and Mn elements.

[0010] In any embodiment of the first aspect, the lithium-containing transition metal oxide containing Ni comprises lithium-containing nickel-cobalt-manganese oxide, and the lithium-containing nickel-cobalt-manganese oxide contains one or more of Zr, Al, B, Fe, Ca, Sr, Ti, V or Y elements.

[0011] In any embodiment of the first aspect, the lithium-containing nickel-cobalt-manganese oxide contains one or more of Zr, Al, B or Fe elements; optionally, in the lithium-containing nickel-cobalt-manganese oxide, the mass content of the elements satisfies at least one of the following: the content of Zr is 1000-3000 ppm, the content of Al is 100-1000 ppm, and the content of B is 50-300 ppm.

[0012] In any embodiment of the first aspect, the lithium-containing phosphate comprises lithium manganese iron phosphate, and the molar amount of Mn element in the lithium manganese iron phosphate accounts for 20%-80%, optionally 30%-70%, and further optionally 30%-50% of the total molar amount of transition metal elements.

[0013] In any embodiment of the first aspect, the lithium manganese iron phosphate contains one or more of Al, B, Ca, Cr, Cu, K, Mg, Na, P, Si, Ti, V or Zn elements, and optionally the lithium manganese iron phosphate contains one or more of Al, Ca, Na, Ti or V elements; further optionally, in the lithium manganese iron phosphate, the mass content of the elements satisfies at least one of the following: the content of Al is 100-1000 ppm, the content of Ca is 50-300 ppm, the content of Na is 50-300 ppm, the content of Ti is 100-1000 ppm, and the content of V is 1000-3000 ppm.

[0014] In any embodiment of the first aspect, the positive electrode active layer contains lithium iron manganese phosphate and lithium-containing nickel cobalt manganese oxide, the positive electrode active material contains one or more of Al, B, Ca, Na, Sr, Ti, V, Y or Zr elements, and the mass content of each element satisfies: Al: 0.005%-0.1%; Ca: 0.0001%-0.02%; Na: 0.005%-0.06%; Ti: 0.005%-0.15%; V: 0.0001%-0.3%; Zr: 0.005%-0.2%; B: 0.01%-0.1%, based on the total mass of the positive electrode active material.

[0015] In any embodiment of the first aspect, the positive electrode active layer includes a first active layer and a second active layer, the first active layer is arranged close to the positive electrode current collector, and the second active layer is arranged on the side of the first active layer away from the positive electrode current collector, the mass content of Ni element in the first active layer is less than that in the second active layer, and the mass content of Fe element in the first active layer is greater than that in the second active layer, based on the total mass of the positive electrode active layer.

[0016] In any embodiment of the first aspect, the battery cell further includes a non-aqueous electrolyte, the non-aqueous electrolyte includes a solvent and a lithium salt, the solvent includes a cyclic carbonate and a linear carbonate; optionally, the cyclic carbonate includes ethylene carbonate (EC); optionally, the linear carbonate includes one or more of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC); optionally, the mass ratio of the cyclic carbonate to the linear carbonate is 2:8-5:5.

[0017] In any embodiment of the first aspect, the electrolyte injection coefficient of the battery cell is 1.8 g / Ah-3.5 g / Ah, which can be 1.9 g / Ah-3.1 g / Ah.

[0018] The second aspect of the present application provides a battery device including any one of the battery cells of the first aspect, the battery device including a battery module, a battery pack or an energy storage device.

[0019] The third aspect of the present application provides a power utilization device including any one of the battery cells of the first aspect or the battery device of the second aspect.

[0020] The present application can realize the synchronous regulation of energy density and cycle life through the design of the positive electrode active material, so that the energy density of the battery cell is fully utilized, and the battery cell has good cycle performance. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below only constitute some embodiments of the present application, and for those skilled in the art, other drawings can be obtained on the basis of the drawings without creative labor.

[0022] FIG. 1 is a schematic view of a battery assembly according to an embodiment of the present application.

[0023] FIG. 2 is an exploded view of a battery cell according to an embodiment of the present application.

[0024] FIG. 3 is a schematic view of a battery pack according to an embodiment of the present application.

[0025] FIG. 4 is an exploded view of a battery pack according to an embodiment of the present application.

[0026] FIG. 5 is a schematic view of an electric device using a battery cell according to an embodiment of the present application as a power source.

[0027] In the drawings, the drawings are not drawn according to the actual scale.

[0028] Explanation of reference numerals:

[0029] 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 battery cell; 51 case; 52 electrode assembly; 53 top cap assembly. DETAILED DESCRIPTION

[0030] The embodiments of the present application will be described in further detail below with reference to the drawings and examples. The detailed description of the following examples and the drawings are used to exemplarily illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described examples.

[0031] Hereinafter, the embodiments of the secondary battery and the electric device according to the present application will be described in detail with appropriate reference to the drawings. However, there will be cases where unnecessary detailed description is omitted. For example, there will be 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 and to facilitate 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.

[0032] The ranges disclosed herein are intended to be "open" ranges, i.e., the upper and lower limits of the range are not included. The ranges can be "closed" ranges, i.e., the upper and lower limits of the range are included. The ranges can be arbitrarily combined, i.e., any upper limit can be combined with any lower limit to form a range. For example, if a range of 60-120 and a range of 80-110 are listed, it is understood that a range of 60-110 and a range of 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and 2 are listed, and if a maximum range value of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise indicated, a numerical range "a-b" means a range of any combination of the numbers a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between 0 and 5 have been listed herein, and "0-5" is merely a shorthand for listing all of those numbers. Also, when a parameter is stated to be an integer > 2, it is equivalent to state that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, if not specifically stated otherwise.

[0034] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, if not specifically stated otherwise.

[0035] All steps of the present application can be performed in sequence or randomly, preferably in sequence, if not specifically stated otherwise. For example, the method comprises steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c) means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0036] The terms "comprise" and "include" mentioned in the present application are open-ended, if not specifically stated otherwise. For example, the terms "comprise" and "include" can mean that other components not listed can also be included.

[0037] If not specifically stated, the term "or" in this application is inclusive. For example, any of the following satisfy the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0038] [Battery cell]

[0039] As described above, improving the cycle performance while increasing the energy density of the battery is one of the focuses in the current battery research field. The present application provides a battery cell, which comprises a shell and an electrode assembly located inside the shell, the electrode assembly comprising a positive electrode sheet, a negative electrode sheet, and a separator film located between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on at least one side of the negative electrode current collector, the negative electrode active layer comprising a negative electrode active material, the negative electrode active material comprising graphite, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active layer arranged on at least one side of the positive electrode current collector, the positive electrode active layer comprising a positive electrode active material, the positive electrode active material comprising a lithium transition metal oxide containing nickel and a lithium-containing phosphate, the molar amount of Ni element in the lithium transition metal oxide containing nickel accounting for 70% to 95% of the total molar amount of transition metals; the lithium-containing phosphate comprising Mn and Fe elements, the ratio of the mass of Ni element in the positive electrode active material to the sum of the mass of Fe element and Mn element in the positive electrode active material being between 0.15 and 2.

[0040] The present application aims to develop a low-cost lithium ion battery cell with high energy density and good cycle performance. Compared with pure lithium transition metal oxide containing nickel, lithium-containing phosphate material has a significant low-cost advantage, and the mixture of the two can fully exert the high specific capacity advantage of lithium nickel cobalt manganese oxide material under the low-cost advantage, thereby improving the energy density of the battery cell. However, the present application unexpectedly found that the content of Ni element, the content of Mn element, and the content of Fe element in the mixture of lithium transition metal oxide containing nickel and lithium-containing phosphate positive electrode active material not only have an impact on the energy density of the battery cell, but also have a significant impact on the cycle performance of the battery cell. The present application expects to obtain a battery cell with high energy density and long cycle life under the system of mixing lithium transition metal oxide containing nickel and lithium-containing phosphate.

[0041] The battery cell includes a nickel-containing lithium transition metal oxide and a lithium-containing phosphate positive electrode active material, the molar amount of Ni element in the nickel-containing lithium transition metal oxide is high (the molar amount of Ni element accounts for 70% to 95% of the total molar amount of transition metal), which belongs to high-nickel lithium transition metal oxide and helps to improve the energy density of the battery cell. However, if too much high-nickel lithium transition metal oxide is added to improve the energy density of the battery cell, the proportion of the lithium-containing phosphate material will be too small, resulting in an imbalance in the content of Ni element, the content of Mn element and the proportion of Fe element in the positive electrode active material, affecting the cycle performance of the battery cell. Therefore, by further controlling the relative proportion of the content of Ni element, the content of Mn element and the content of Fe element, that is, by limiting the ratio of the mass of Ni element in the positive electrode active material to the sum of the mass of Fe element and Mn element in the positive electrode active material to be between 0.15 and 2, the relative content of high-nickel lithium transition metal oxide and lithium-containing phosphate in the positive electrode active material is kept within a reasonable range, so that the battery cell has both high energy density and cycle performance.

[0042] Specifically, when the molar amount of Ni element in the nickel-containing lithium transition metal oxide is within the range of 70% to 95%, and the ratio of the mass of Ni element in the positive electrode active material to the sum of the mass of Fe element and Mn element in the positive electrode active material is less than 0.15, it indicates that the content of lithium-containing phosphate in the positive electrode active material is too high, which corresponds to the content of Mn element and Fe element in the positive electrode active material being too high. This makes the Mn element and Fe element easy to be released from the lithium-containing phosphate skeleton and transition metal elution, thereby reducing the cycle performance of the battery cell. Correspondingly, when the molar amount of Ni element in the nickel-containing lithium transition metal oxide is within the range of 70% to 95%, and the ratio of the mass of Ni element in the positive electrode active material to the sum of the mass of Fe element and Mn element in the positive electrode active material is greater than 2, it indicates that the content of high-nickel lithium transition metal oxide in the positive electrode active material is too high, which corresponds to the content of Ni element in the positive electrode active material being too high. At this time, although the energy density of the battery cell is high, the structural stability of the high-nickel lithium transition metal oxide is poor, the Ni element is easy to be released from the skeleton structure of the high-nickel lithium transition metal oxide, in addition, the surface residual alkali amount of the high-nickel lithium transition metal oxide is also high and is easy to have side reactions with the electrolyte, thereby reducing the cycle performance of the battery cell.

[0043] By reasonably controlling the molar amount of Ni element in the nickel-containing lithium transition metal oxide and the ratio of the mass of Ni element in the positive electrode active material to the sum of the mass of Fe element and Mn element in the positive electrode active material within a reasonable range, the battery cell has low cost, high energy density and good cycle performance.

[0044] In some embodiments, the ratio of the mass of Ni element in the positive electrode active material to the sum of the mass of Fe element and Mn element in the positive electrode active material is between 0.55 and 1.42, such as 0.55, 0.60, 0.62, 0.64, 0.66, 0.7, 0.8, 0.9, 0.97, 1.0, 1.1, 1.2, 1.3, 1.4, or 1.42.

[0045] When the content of Ni element in the nickel-containing lithium transition metal oxide is high, the ratio of the mass of Ni element in the positive electrode active material to the sum of the mass of Fe and Mn elements allows the content of nickel-containing lithium transition metal oxide in the positive electrode active material to be high, and improves the cycle performance of the battery cell when increasing the energy density of the battery cell.

[0046] In some embodiments, the mass content of lithium-containing phosphate in the positive electrode active material is 50%-90%, such as 50%, 55%, 60%, 65%, 70%, 75%, 80%, or 90%, and optionally 50%-70%. When the mass content of lithium-containing phosphate in the positive electrode active material is within the above range, the battery cell has a high energy density.

[0047] In the nickel-containing lithium transition metal oxide, increasing the content of Ni element can effectively increase the specific capacity of the material system, thereby further increasing the energy density of the battery cell. In addition, the capacity retention rate of the nickel-containing lithium transition metal oxide is high in a low-temperature environment, and has good low-temperature stability. In some embodiments, the molar content of Ni element in the nickel-containing lithium transition metal oxide is 80%-95% of the total molar content of Ni, Co, and Mn elements. Increasing the molar percentage of Ni element is beneficial to increasing the energy density of the entire multi-system mixed positive electrode sheet, and controlling the molar percentage of Ni element to be no higher than 95% improves the structural stability of the nickel-containing lithium transition metal oxide, and also reduces the side reactions with the battery cell, to optimize the cycle performance and safety performance of the battery cell.

[0048] In some embodiments, the nickel-containing lithium transition metal oxide includes lithium-containing nickel-cobalt-manganese oxide, and the lithium-containing nickel-cobalt-manganese oxide contains one or more of Zr, Al, B, Fe, Ca, Sr, Ti, V, or Y elements. The above elements can exist in the form of doping or coating in the nickel-containing lithium transition metal oxide.

[0049] The energy density of lithium transition metal oxides containing nickel (especially high-nickel ternary material system) is high, but there are defects such as element mixing, phase change, poor thermal stability, micro-cracks, and the cycle stability and service life need to be improved. To improve the comprehensive performance of lithium-containing nickel-cobalt-manganese oxides, modification methods such as doping, modification, compounding, and morphology control can be used. For example, cation doping, anion doping, and multi-ion co-doping, and for example, Zr, Al, Fe, Ca, Sr, Ti, V, and Y can be used as cation doping elements, and B can be used as anion doping element. In some embodiments, Zr can simultaneously occupy Ni sites and Li sites, reducing the mixing of Ni and Li, improving ion conductivity, and Zr has a strong chemical bond with O, which is conducive to stabilizing the crystal structure of the layered material and plays a supporting role in the process of lithium extraction / insertion. Al is dissolved in the transition metal layer of lithium-containing nickel-cobalt-manganese oxide in the form of a solid solution, which can effectively improve the capacity retention during the cycle process. B as anion doping can relieve the strain of lithium-containing nickel-cobalt-manganese oxide during lithiation / delithiation, improve the cycle stability and service life.

[0050] In some embodiments, the lithium-containing nickel-cobalt-manganese oxide contains one or more of Zr, Al, B, or Fe elements; optionally, in the lithium-containing nickel-cobalt-manganese oxide, the mass content of the elements satisfies at least one of the following: the content of Zr is 1000-3000 ppm, the content of Al is 100-1000 ppm, and the content of B is 50-300 ppm. This is conducive to better balancing the cycle stability and specific capacity.

[0051] In some embodiments, the lithium-containing phosphate includes lithium manganese iron phosphate, and the molar amount of Mn element in the lithium manganese iron phosphate is 20%-80% of the total molar amount of non-lithium metal elements, such as 20%, 30%, 40%, 50%, 60%, 70%, or 80%, optionally 30%-70%, and further optionally 30%-50%. When the molar percentage content of Mn element in the non-lithium metal elements of the lithium-containing phosphate is within the above range, the specific capacity of the lithium-containing phosphate can be maintained as high as possible, and the voltage platform of the battery cell can be improved, thereby improving the energy density of the battery cell.

[0052] In some embodiments, the lithium manganese iron phosphate contains one or more of Al, B, Ca, Cr, Cu, K, Mg, Na, P, Si, Ti, V, or Zn elements, and the lithium manganese iron phosphate contains one or more of Al, Ca, Na, Ti, or V elements; further optionally, in the lithium manganese iron phosphate, the mass content of the elements satisfies at least one of the following: the content of Al is 100-1000 ppm, the content of Ca is 50-300 ppm, the content of Na is 50-300 ppm, the content of Ti is 100-1000 ppm, and the content of V is 1000-3000 ppm.

[0053] Doping one or more of the above elements into the lithium-containing phosphate can improve the conductivity of the material by introducing lattice vacancies or changing atomic bond lengths, which can facilitate Li + migration. For example, Mg doping can improve the conductivity while improving the structural stability; Al doping can improve the material conductivity and help to inhibit phase transition under high voltage or deep discharge; Ca doping can improve the cycle stability; Na doping can promote the ion diffusion rate and improve the specific capacity; Ti doping can provide additional Li + sites, improve the specific capacity, and help to reduce Mn dissolution during cycling; V doping can improve the conductivity and electrochemical activity, and improve the charge and discharge performance.

[0054] In some embodiments, the positive electrode active layer contains lithium iron manganese phosphate and lithium-containing nickel-cobalt-manganese oxide, the positive electrode active material contains one or more of Al, B, Ca, Na, Sr, Ti, V, Y, or Zr, and the mass content of each element satisfies: Al: 0.005%-0.1%; Ca: 0.0001%-0.02%; Na: 0.005%-0.06%; Ti: 0.005%-0.15%; V: 0.0001%-0.3%; Zr: 0.005%-0.2%; B: 0.01%-0.1%, based on the total mass of the positive electrode active material. The energy density of the battery cell with the above characteristics can be maintained at a high level, and the cycle life is longer and more secure.

[0055] The elements in each of the above materials can be determined by the following method:

[0056] For the positive electrode tab of the battery cell, the positive electrode tab is washed with dimethyl carbonate (DMC), and the positive electrode tab is dried and calcined to collect the positive electrode material in the positive electrode active layer. The positive electrode material is tested by inductively coupled plasma atomic emission spectrometry (ICP-OES).

[0057] In some embodiments, the positive electrode active layer includes a first active layer and a second active layer, the first active layer is arranged close to the positive electrode current collector, and the second active layer is arranged on the side of the first active layer away from the positive electrode current collector. The mass content of Ni in the first active layer is less than the mass content of Ni in the second active layer, and the mass content of Fe in the first active layer is greater than the mass content of Fe in the second active layer, based on the total mass of the positive electrode active layer. The first active layer is arranged close to the current collector, and the positive electrode active material is mainly lithium-containing phosphate; the second active layer is arranged away from the positive electrode current collector, i.e. in contact with the electrolyte, and the positive electrode active material is mainly lithium transition metal oxide containing nickel. The lithium transition metal oxide containing nickel can block the side reaction of lattice water in the lithium-containing phosphate with the electrolyte, and improve the cycle life of the battery cell.

[0058] In some embodiments, the positive current collector can employ a metal foil or a composite current collector. For example, as a metal foil, an aluminum 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 (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0059] In some embodiments, the positive electrode film layer can further optionally include a conductive agent. As an example, the conductive agent can include at least one of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0060] In some embodiments, the positive electrode tab can be prepared by dispersing the above-described components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector; and subjecting the same to a drying, cold-pressing, or the like process to obtain the positive electrode tab.

[0061] [Electrolyte]

[0062] In some embodiments, the battery cell further includes an electrolyte. The electrolyte serves to conduct ions between the positive electrode tab and the negative electrode tab. The type of the electrolyte is not particularly limited in the present application and can be selected as needed. For example, the electrolyte can be in a liquid state, a gel state, or a full solid state.

[0063] In some embodiments, the battery cell includes a non-aqueous electrolyte, the non-aqueous electrolyte includes a solvent, the solvent includes a cyclic carbonate and a linear carbonate; optionally, the cyclic carbonate includes ethylene carbonate (EC); optionally, the linear carbonate includes one or more of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC); optionally, the mass ratio of the cyclic carbonate and the linear carbonate is 2:8 to 5:5. The cyclic carbonate has a large dielectric constant, which is advantageous for promoting the dissociation of lithium salt, and the linear carbonate has a low viscosity, which is advantageous for Li + ion migration. When the mass ratio of the cyclic carbonate and the linear carbonate is in the range of 2:8 to 5:5, the oxidation resistance of the electrolyte can be significantly improved, which is advantageous for prolonging the cycle life of the battery cell.

[0064] In some embodiments, the electrolyte salt can be selected from 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.

[0065] In some embodiments, the electrolyte solution can further optionally include an additive. As an example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can further include an additive capable of improving certain performance of the battery, such as an additive for improving overcharge performance of the battery, an additive for improving high-temperature or low-temperature performance of the battery, etc.

[0066] In some embodiments, the electrolyte solution of the battery cell can have an electrolyte injection coefficient of 1.8-3.5 g / Ah, and can optionally have an electrolyte injection coefficient of 1.9-3.1 g / Ah. In the case of normal operation of the battery cell, a small electrolyte injection coefficient is advantageous in reducing the degree of deterioration of side reactions caused by the electrolyte solution, and improving the cycle life of the battery cell.

[0067] [Negative electrode sheet]

[0068] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode active layer is provided on either one or both of the two surfaces of the negative electrode current collector.

[0069] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. As a metal foil, for example, a copper 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 (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.).

[0070] In some embodiments, the graphite of the negative electrode active material can include artificial graphite and natural graphite. In addition, in some embodiments, the negative electrode active material can further include soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative electrode active material can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0071] In some embodiments, the negative electrode film layer can further optionally comprise a binder. As an example, the binder can be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0072] In some embodiments, the negative electrode film layer can further optionally comprise a conductive agent. As an example, the conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0073] In some embodiments, the negative electrode film layer can further optionally comprise other auxiliary agents, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), etc.

[0074] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as the negative electrode 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 a negative electrode current collector, and after processes such as drying, cold pressing, etc., the negative electrode sheet can be obtained.

[0075] [Separator]

[0076] In some embodiments, the battery cell further comprises a separator. The type of the separator is not particularly limited in the present application, and any known porous structure separator with good chemical stability and mechanical stability can be used.

[0077] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0078] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly through a winding process or a stacking process.

[0079] The second embodiment of the present application further provides a battery device comprising any one of the battery cells provided by the above-mentioned first embodiment, and the battery device comprises a battery module, a battery pack, or an energy storage device.

[0080] In some embodiments, the battery device can comprise an outer package. The outer package can be used to package the above-mentioned electrode assembly and the electrolyte.

[0081] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, etc. can be listed.

[0082] The shape of the battery cell is not particularly limited in the present application, and can be cylindrical, square, or any other shape. For example, FIG. 1 is an electrode assembly 52 of a square structure as an example.

[0083] In some embodiments, referring to FIG. 2, the outer package can include a shell 51 and a top cover assembly 53. The shell 51 can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can be provided on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the secondary battery cell 5 can be one or more, and a person skilled in the art can select according to the specific actual needs.

[0084] In some embodiments, the secondary battery cell can be assembled into a battery module, and the number of secondary battery cells contained in the battery module can be one or more, and the specific number can be selected by a person skilled in the art according to the application and capacity of the battery module.

[0085] In the battery module 4, a plurality of battery cells can be arranged in sequence along the thickness direction of the battery cell. Of course, other arbitrary arrangements can also be used. Further, the plurality of battery cells can be fixed by fasteners.

[0086] Optionally, the battery module can also include a housing having a receiving space, and the plurality of battery cells are received in the receiving space.

[0087] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by a person skilled in the art according to the application and capacity of the battery pack.

[0088] FIGS. 3 and 4 are a battery pack 1 as an example. Referring to FIGS. 3 and 4, the battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be provided on the lower box body 3 to form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0089] In addition, the application also provides a power utilization device comprising the battery cell or the battery device provided by the application. The battery cell or the battery device can be used as a power supply of the power utilization device, and can also be used as an energy storage unit of the power utilization device. The power utilization 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.

[0090] As the power utilization device, the battery cell, the battery module or the battery pack can be selected according to the use requirement thereof.

[0091] FIG. 5 is a power utilization device as an example. The power utilization device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirement of high power and high energy density of the battery cell of the power utilization device, the battery pack or the battery module can be used.

[0092] [Embodiment]

[0093] Hereinafter, the embodiments of the application are described. The embodiments described below are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application. If the specific technology or condition is not indicated in the embodiments, the technology or condition described in the literature in the art or according to the product instruction is used. If the reagent or instrument used is not indicated by the manufacturer, it is a conventional product that can be obtained by market purchase.

[0094] Embodiment 1

[0095] Positive electrode tab:

[0096] The positive electrode active layer comprises a positive electrode active material, a binder polyvinylidene fluoride, and a conductive agent acetylene black (mass ratio is 96.7:2.3:1). In the positive electrode active material, the mass ratio of lithium transition metal oxide containing nickel and lithium-containing phosphate is 3:7. The chemical formula of the lithium transition metal oxide containing nickel is Li(Ni 0.90 Co 0.05 Mn 0.05 )O2, and the chemical formula of the lithium-containing phosphate is Li(Fe 0.5 Mn 0.5 )PO4. The ratio of the mass of the element Ni to the sum of the mass of the elements Fe and Mn is 0.64.

[0097] The other elements in the positive active material are from the lithium transition metal oxide containing nickel, the subscripts of Ni, Co and Mn in the chemical formula are the data after rounding, the content of element M is trace or even lower, so these elements and their mole number are not reflected in the chemical formula, and element M does not affect the performance of the battery cell, and the chemical formula is Li(Ni 0.90 Co 0.05 Mn 0.05 In the lithium transition metal oxide containing nickel with the chemical formula of Li(Ni

[0098] The thickness of the positive current collector aluminum foil is 13 μm, the positive film layer is located on both sides of the aluminum foil, and there is a conductive primer layer between the positive film layer and the aluminum foil, the conductive primer layer is a film layer formed by uniformly mixing the positive conductive agent super conductive carbon, the positive binder polyacrylate and the solvent on the surface of the positive current collector and drying, the thickness is 1 μm, the mass content of the positive conductive agent in the negative conductive layer is 50%, and the mass content of the positive binder in the negative conductive layer is 50%. The length of the positive electrode sheet is 592 mm.

[0099] The coating density of the positive electrode sheet is 315 mg / 1540.25 mm 2 .

[0100] The negative electrode sheet:

[0101] The negative active layer includes the negative active material graphite, the conductive agent acetylene black, the binder styrene butadiene rubber and the thickening agent sodium carboxymethyl cellulose with a mass ratio of 96:1:2:1.

[0102] The negative current collector is a copper foil with a thickness of 5 μm, and there is a negative conductive layer between the copper foil and the lower film layer, the conductive primer layer is a film layer formed by uniformly mixing the negative conductive agent super conductive carbon, the negative binder styrene butadiene rubber SBR, the thickening agent sodium carboxymethyl cellulose (CMC-Na) and the solvent water on the surface of the negative current collector and drying, the thickness is 1 μm, the mass content of the negative conductive agent in the negative conductive layer is 35%, the mass content of the negative binder in the negative conductive layer is 60%, and the mass content of the thickening agent in the negative conductive layer is 5%.

[0103] The coating density of the negative electrode sheet is 160 mg / 1540.25 mm 2 .

[0104] The electrolyte includes an organic solvent, a lithium salt and an additive, wherein:

[0105] The organic solvent is a mixture of a cyclic carbonate and a linear carbonate, the cyclic carbonate is ethylene carbonate (EC), and the linear carbonate is dimethyl carbonate (DMC), methyl ethyl carbonate (EMC), or diethyl carbonate (DEC), which are mixed in a mass ratio of 30%:20%:20%:30% to obtain a mixture, and the mass ratio of the cyclic carbonate to the linear carbonate is 3:7;

[0106] The lithium salt is lithium hexafluorophosphate (LiPF6) with a concentration of 1.2 mol / L.

[0107] The electrolyte additive is composed of 2.5 wt% of vinylene carbonate (VC), 1 wt% of fluoroethylene carbonate (FEC), 0.5 wt% of 1,3-propylene sulfite (PS), 0.5 wt% of vinyl sulfite (DTD), and 0.5 wt% of lithium difluorophosphate (LiPO2F2).

[0108] Preparation of the separator film:

[0109] A polyethylene (PE) film coated with an alumina inorganic coating and a PVDF organic coating is used as the separator film, the thickness of the polyethylene film is 7 μm, and the separator is purchased from Zhgaokong Technology Co., Ltd.

[0110] Preparation of the battery cell:

[0111] The positive electrode sheet, the separator film, and the negative electrode sheet are arranged in a stack to obtain an electrode assembly. The electrode assembly is added to an outer packaging square aluminum shell (600 mm in length, 19 mm in thickness, 105 mm in height, and 1 mm in shell wall thickness), and after drying, an electrolyte is injected, and the injection coefficient is 2.75 g / Ah. After the packaging, high-temperature standing, formation, secondary injection, aging, and capacity processes, the battery cell is obtained.

[0112] The lithium transition metal oxide containing nickel and the lithium-containing phosphate used in the examples and comparative examples are both conventional materials in the art or are prepared by conventional methods.

[0113] The lithium transition metal oxide containing nickel has a chemical formula of Li(Ni 0.93 Co 0.06 Mn 0.01 )O2, Li(Ni 0.95 Co 0.03 Mn 0.02 )O2, and the mass content of each element in the element M is: Al: 0.081%, B: 0.091%, Na: 0.0093%, S: 0.082%, Sb: 0.014%, Sr: 0.025%, W: 0.035%, and Zr: 0.143%.

[0114] The lithium transition metal oxide containing nickel has a chemical formula of Li(Ni 0.70Co 0.10 Mn 0.20 )O2, the mass content of each element in element M is: Al: 0.0054%; B: 0.0024%; Ca: 0.0032%; Cr: 0.0001%; Cu: 0.0003%; Mg: 0.0037%; Na: 0.010%; S: 0.063%; Sr: 0.085%; Ti: 0.175%; W: 0.059%; Y: 0.0001%; Zn: 0.0002%; Zr: 0.125%.

[0115] Li(Ni 0.45 Co 0.18 Mn 0.37 )O2, Li(Ni 0.45 Co 0.25 Mn 0.30 )O2, Li(Ni 0.50 Co 0.20 Mn 0.30 )O2, Li(Ni 0.55 Co 0.05 Mn 0.40 )O2, the mass content of each element in element M is: Al: 0.0054%; B: 0.0024%; Ca: 0.0032%; Cr: 0.0001%; Cu: 0.0003%; Mg: 0.0037%; Na: 0.010%; S: 0.063%; Sr: 0.085%; Ti: 0.175%; W: 0.059%; Y: 0.0001%; Zn: 0.0002%; Zr: 0.125%.

[0116] [Battery cell performance test]

[0117] Test method of volume energy density:

[0118] The battery cell is placed at 25°C, and charged at a rate of 0.33C to 4.3V, and then charged at a constant voltage to 0.05C, and the discharge capacity A0 (unit: Ah) of the battery cell is recorded when discharged at a rate of 0.33C from 4.3V to 2.5V, and C is the nominal capacity of the battery cell; the length, width and height of the battery cell are measured using a caliper (generally calculated based on the size of the battery shell, excluding the height of the electrode terminal, and excluding the insulating film outside the shell), and the volume V0 of the battery cell is calculated, unit L; the volume energy density VED of the battery cell is (A0 x discharge platform voltage) / V0, unit Wh / L.

[0119] Test method of cycle performance:

[0120] The battery cells were subjected to charge-discharge cycles at a constant temperature of 25°C, between 2.5V and 4.3V. The specific procedure was as follows: charge at 0.33C to 4.3V, then charge at 4.3V with a constant voltage until the current does not exceed 0.05C, let stand for 5 minutes, and then discharge at 1C to 2.5V. The capacity is recorded as C. m (m = 1, 2, 3, ...), repeat the above operation, and use C as the capacity retention rate. m The ratio / C3 indicates that when C m When / C3×100%=80%, record the corresponding number of cycles as an indicator of cycle capability. The more cycles, the better the cycle performance of the battery cell.

[0121] Based on Example 1, the following examples adjust the composition of the nickel-containing lithium transition metal oxide and the mass ratio of nickel-containing lithium transition metal oxide to lithium phosphate in the positive electrode active material. The negative electrode sheet, electrolyte, and separator are the same as in Example 1.

[0122] The specific adjustments are shown in Table 1, and the battery cell performance test results for each embodiment are recorded in Table 1.

[0123] Table 1

[0124] In Table 1, data T represents the mass content of lithium phosphate in the positive electrode active material.

[0125] Table 1 illustrates that controlling the ratio of the mass of Ni to the sum of the masses of Fe and Mn (hereinafter referred to as the "Ni:(Fe+Mn) mass ratio") is beneficial for improving energy density and cycle life. If the Ni:(Fe+Mn) mass ratio is too low, as in Comparative Examples 1 and 2, it leads to a deterioration in both the energy density and cycle performance of the battery cells. If the Ni:(Fe+Mn) mass ratio is too high, as in Comparative Examples 3 and 4, although it increases the energy density of the battery cells, it significantly reduces the number of cycle times and drastically decreases the cycle life. When the Ni:(Fe+Mn) mass ratio is between 0.15 and 2, the energy density and cycle performance of the battery cells are at a relatively high level in a balanced manner.

[0126] The following investigation examines the effect of changes in the molar ratio of Mn to transition metals in lithium phosphate on the energy density and cycle performance of individual battery cells.

[0127] The nickel-containing lithium transition metal oxides used in Examples 5 to 8 are the same as those in Example 1, and all satisfy the mass ratio of nickel-containing lithium transition metal oxide to lithium phosphate is 3:7. The negative electrode sheet, electrolyte and separator are the same as those in Example 1. The variable settings and battery cell performance test results of each example are shown in Table 2.

[0128] Table 2

[0129] Comparative analysis of the data of each example in Table 2 can find that:

[0130] The molar percentage of Mn element in lithium-containing phosphate to transition metal elements has a nonlinear relationship with the performance of the battery cell. When the molar percentage is 30%-50%, the energy density and cycle life of the battery cell have relatively more excellent performance.

[0131] Next, by adjusting the mass content of lithium-containing phosphate in the positive electrode active material, the influence of the mass ratio of nickel-containing lithium transition metal oxide to lithium-containing phosphate in the positive electrode active material on the energy density and cycle performance of the battery cell is investigated.

[0132] In the positive electrode active materials of Examples 9 to 12, the compositions of nickel-containing lithium transition metal oxide and lithium-containing phosphate are all the same as those of Example 1, the nickel-containing lithium transition metal oxide is Li(Ni 0.9 Co 0.05 Mn 0.05 )O2, and the lithium-containing phosphate is Li(Fe 0.5 Mn 0.5 )PO4, only the mass ratio of nickel-containing lithium transition metal oxide to lithium-containing phosphate is changed; in addition, the rest of the positive electrode sheet and the settings of the negative electrode sheet, electrolyte, and separator are all the same as those of Example 1.

[0133] The variable settings of each example and the test results of the battery cell performance are shown in Table 3.

[0134] Table 3

[0135] In Table 3, data T represents the mass content of lithium-containing phosphate in the positive electrode active material.

[0136] Comparative analysis of the data of each example in Table 3 can find that:

[0137] When the mass content of lithium-containing phosphate is 50%-90%, the battery cell all shows good cycle performance; further, when the mass content of lithium-containing phosphate is 50%-70%, the energy density improvement is greater with the high-nickel lithium transition metal oxide system.

[0138] On the basis of Example 1, the following examples only adjust the molar content of Ni element in Ni, Co, and Mn elements in the nickel-containing lithium transition metal oxide, and the other initial conditions remain unchanged. That is, the mass ratio of nickel-containing lithium transition metal oxide to lithium-containing phosphate in the positive electrode active material of each example is 3:7, and the lithium-containing phosphate is all Li(Fe 0.5 Mn 0.5)PO4, i.e. the molar amount of Mn element in lithium-containing phosphate accounts for 50% of the total molar amount of non-lithium transition metal elements. The negative electrode sheet, electrolyte and separator film are the same as those in Example 1.

[0139] The variable settings and battery cell performance test results of each example are shown in Table 4.

[0140] Table 4

[0141] Comparative analysis of the data of each example in Table 4 can find that:

[0142] The composition and mass content of lithium-containing phosphate in the positive active material are unchanged, and in the lithium transition metal oxide containing nickel, as the molar content of Ni element in Ni, Co and Mn elements increases, the mass ratio of Ni:(Fe+Mn) also increases accordingly, making the value of the energy density of the battery cell show an increasing trend, and the cycle number shows less and less.

[0143] The amount and composition of electrolyte are closely related to its ion transport ability, chemical stability and other properties, which will further affect the cycle life of the battery cell. Therefore, next, by adjusting the electrolyte injection coefficient and different solvent ratios, the role of electrolyte on the cycle life of the battery cell is investigated.

[0144] On the one hand, for the electrolyte of Examples 18 to 23, only the injection coefficient of each is set to different values, and the composition of the electrolyte and the rest of the conditions remain unchanged with Example 1. The settings of the positive electrode sheet, negative electrode sheet and separator film of each example are also the same as those of Example 1.

[0145] The variable settings and battery cell performance test results of each example are shown in Table 5.

[0146] Table 5

[0147] From the data presented in Table 5, it can be seen that: the injection coefficient of the battery cell is too high or too low, which will affect the cycle life. Too high injection coefficient may easily cause electrolyte side reactions, which reduces the cycle performance; too low injection coefficient easily leads to insufficient soaking of the electrode sheet, which also reduces the cycle performance. When the electrolyte injection coefficient is in the range of 1.8g / Ah-3.5g / Ah, especially in the range of 1.9g / Ah-3.1g / Ah, the cycle performance can be kept at a high level.

[0148] On the other hand, for Examples 24 to 27, only the mass ratio of cyclic carbonate to linear carbonate in each electrolyte is adjusted, and the injection coefficient and the rest of the conditions remain unchanged with Example 1. The settings of the positive electrode sheet, negative electrode sheet and separator film of each example are also the same as those of Example 1.

[0149] The variable settings and battery cell performance test cases of each embodiment are shown in Table 6.

[0150] Table 6

[0151] From the data presented in Table 6, it can be seen that in the above embodiments, the mass ratio of different cyclic carbonates to linear carbonates mainly affects the cycle performance of the battery cell. Based on Embodiment 1, whether the mass content of cyclic carbonate is reduced or increased, the cycle number shows a downward trend, which may be due to the fact that cyclic carbonate is beneficial to the dissociation of lithium ions, and its mass content reduction will affect the dissociation degree and conductivity of lithium ions. The viscosity of cyclic carbonate itself is large and its oxidation resistance is weak, and its mass content increase may cause polarization loss of the battery cell, thereby affecting the cycle performance.

[0152] In summary, by matching the lithium transition metal oxide containing nickel and the lithium-containing phosphate, and through the design of the positive electrode active material, the synchronous regulation of energy density and cycle life can be realized, so that the battery cell obtains a relatively balanced energy density and cycle life, the energy density of the battery cell is fully utilized, and compared with the case of using high-nickel lithium transition metal oxide as the positive electrode active material alone, the safety risk is significantly reduced.

[0153] Although the present application has been described with reference to the preferred embodiments, various modifications can be made to it without departing from the scope of the application, and equivalent components therein can be substituted. In particular, the technical features mentioned in each embodiment can be combined in any way as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, comprising a casing and an electrode assembly located inside the casing, the electrode assembly comprising a positive electrode tab, a negative electrode tab, and a separator film located between the positive electrode tab and the negative electrode tab, wherein, the negative electrode tab comprises a negative electrode current collector and a negative electrode active layer provided on at least one side of the negative electrode current collector, the negative electrode active layer comprising a negative electrode active material, the negative electrode active material comprising graphite, the positive electrode tab comprises a positive electrode current collector and a positive electrode active layer provided on at least one side of the positive electrode current collector, the positive electrode active layer comprising a positive electrode active material, the positive electrode active material comprising a nickel-containing lithium transition metal oxide and a lithium-containing phosphate, a molar amount of Ni element in the nickel-containing lithium transition metal oxide accounts for 70% to 95% of a total molar amount of transition metals in the nickel-containing lithium transition metal oxide, a ratio of a mass of Ni element in the positive electrode active material to a sum of masses of Fe element and Mn element in the positive electrode active material is between 0.15 and 2. A ratio of a mass of Ni element in the positive electrode active material to a sum of masses of Fe element and Mn element in the positive electrode active material is between 0.55 and 1.

42. A mass content of the lithium-containing phosphate in the positive electrode active material is 50% to 90%, optionally 50% to 70%. The nickel-containing lithium transition metal oxide comprises a lithium-containing nickel cobalt manganese oxide, a molar amount of the Ni element in the lithium-containing nickel cobalt manganese oxide accounts for 80% to 95% of a total molar amount of nickel cobalt manganese elements.

2. The battery cell of claim 1, wherein, The nickel-containing lithium transition metal oxide comprises a lithium-containing nickel cobalt manganese oxide, the lithium-containing nickel cobalt manganese oxide containing one or more of Zr, Al, B, Fe, Ca, Sr, Ti, V or Y elements.

3. The battery cell of claim 1 or 2, wherein, The lithium-containing nickel cobalt manganese oxide contains one or more of Zr, Al, B or Fe elements; optionally, in the lithium-containing nickel cobalt manganese oxide, the element mass content satisfies at least one of: a content of Zr is 1000 to 3000 ppm, a content of Al is 100 to 1000 ppm, a content of B is 50 to 300 ppm.

4. The battery cell of any one of claims 1 to 3, wherein, The lithium-containing phosphate comprises a lithium manganese iron phosphate, a molar amount of the Mn element in the lithium manganese iron phosphate accounts for 20% to 80%, optionally 30% to 70%, further optionally 30% to 50% of a total molar amount of transition metal elements.

5. The battery cell of any one of claims 1 to 4, wherein, The lithium manganese iron phosphate contains one or more of Al, B, Ca, Cr, Cu, K, Mg, Na, P, Si, Ti, V or Zn elements, optionally the lithium manganese iron phosphate comprises one or more of Al, Ca, Na, Ti or V elements; further optionally, in the lithium manganese iron phosphate, the element mass content satisfies at least one of: a content of Al is 100 to 1000 ppm, a content of Ca is 50 to 300 ppm, a content of Na is 50 to 300 ppm, a content of Ti is 100 to 1000 ppm, a content of V is 1000 to 3000 ppm.

6. The battery cell of claim 5, wherein, ​ 7. The battery cell of any one of claims 1 to 6, wherein, ​ 8. The battery cell of any one of claims 1 to 7, wherein, ​ 9. The battery cell of any one of claims 1 to 8, wherein, The positive electrode active layer contains lithium manganese iron phosphate and lithium-containing nickel cobalt manganese oxide, the positive electrode active material contains one or more of Al, B, Ca, Na, Sr, Ti, V, Y or Zr elements, and the mass content of each element satisfies: Al:0.005％-0.1％； Ca: 0.0001% to 0.02%; Na: 0.005% to 0.06%; Ti: 0.005% to 0.15%; V:0.0001％-0.3％； Zr:0.005％-0.2％； B:0.01％-0.1％。 10. The battery cell of any one of claims 1 to 9, wherein, The positive electrode active layer includes a first active layer and a second active layer, the first active layer is arranged close to the positive electrode current collector, the second active layer is arranged on the side of the first active layer away from the positive electrode current collector, the mass content of Ni element in the first active layer is less than that in the second active layer, and the mass content of Fe element in the first active layer is greater than that in the second active layer, based on the total mass of the positive electrode active layer.

11. The battery cell of any one of claims 1 to 10, wherein, The battery cell further includes a non-aqueous electrolyte, the non-aqueous electrolyte includes a solvent and a lithium salt, the solvent includes a cyclic carbonate and a linear carbonate; optionally, the cyclic carbonate includes ethylene carbonate; optionally, the linear carbonate includes one or more of dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; optionally, the mass ratio of the cyclic carbonate to the linear carbonate is 2:8 to 5:

5.

12. The battery cell of any one of claims 1-11, wherein, The electrolyte injection coefficient of the battery cell is 1.8 g / Ah to 3.5 g / Ah, and optionally 1.9 g / Ah to 3.1 g / Ah.

13. A battery device comprising the battery cell of any one of claims 1 to 12, the battery device comprising a battery module, a battery pack, or an energy storage device.

14. A power utilization device comprising the battery cell of any one of claims 1 to 12, or the battery device of claim 13.

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