Battery monomer and preparation method thereof, battery device and power utilization device

Abstract

The invention provides a battery monomer and a preparation method thereof, a battery device and a power utilization device. The battery monomer comprises a positive pole piece, the positive pole piece comprises a positive current collector and a positive film layer arranged on at least one surface of the positive current collector, the positive film layer comprises a positive active material, and the positive active material comprises a substrate, a first coating layer located on the surface of the substrate and a second coating layer located on the surface of the first coating layer; the first coating layer comprises a fast ion conductor with the ionic conductivity range of 10 <-9 > S / cm to 10 <-4 > S / cm; the second coating layer comprises a material with the chemical formula of RaAcBd, R comprises at least one of Li, Na and K, A comprises any one of Ga, Gd, Hf, La, Pr, Y, Si, Ta and Th, and B comprises any one of O and F; wherein 0 < = a < = 4, 0 < c < = 5, and 1 < = d < = 12.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a battery monomer, a preparation method thereof, a battery device and a power utilization device. BACKGROUND

[0002] In recent years, with the application range of lithium ion batteries becoming more and more extensive, they are widely used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, aerospace, etc. With the great development of lithium ion batteries, higher requirements have been put forward for their performance, etc.

[0003] The positive active material, as an important component of the battery, has an important influence on its performance, but in the current battery, the performance of the positive active material cannot meet the needs of low direct current resistance, high output power and service life. SUMMARY

[0004] The present application is carried out in view of the above-mentioned problems, and aims to provide a battery monomer with relatively low direct current resistance, high output power and service life. In addition, the present application also provides a preparation method of the battery monomer, and a battery device and a power utilization device comprising the battery.

[0005] In order to achieve the above-mentioned purpose, the present application proposes the following technical solutions.

[0006] The first aspect of the present application provides a battery monomer, which comprises a positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material, wherein the positive electrode active material comprises: a matrix, a first coating layer located on the surface of the matrix, and a second coating layer located on the surface of the first coating layer.

[0007] The first coating layer comprises a fast ion conductor with an ionic conductivity ranging from 10 -9 S / cm to 10 -4 S / cm;

[0008] The second coating layer comprises a material with a chemical formula of R a A c B dmaterial, wherein R includes at least one of Li, Na, and K, A includes any one of Ga, Gd, Hf, La, Pr, Y, Si, Ta, and Th, and B includes any one of O and F; wherein 0≤a≤4, 0

[0009] In some embodiments, the first coating layer includes a material with a chemical formula of Li e M f (PO4)3, wherein 0

[0010] In some embodiments, A includes any one of Si and Y. Thus, the application further limits the material of the second coating layer, which is beneficial to the capture of HF by the second coating layer, reduces its corrosion damage to the positive electrode active material, thereby reducing the direct current resistance of the secondary battery to improve the output power and service life of the secondary battery.

[0011] In some embodiments, the content of the M element is 100 ppm to 2000 ppm based on the weight of the positive electrode active material. Thus, the application limits the content of the characteristic element M in the first coating layer, i.e., limits the coating amount of the first coating layer, so that the first coating layer can effectively coat the surface of the substrate, which is beneficial to its interception of HF function and conductivity.

[0012] In some embodiments, the content of the A element is 100 ppm to 5000 ppm based on the weight of the positive electrode active material. Thus, the application limits the content of the characteristic element A in the second coating layer, i.e., limits the coating amount of the second coating layer, so that the second coating layer can effectively coat the surface of the first coating layer, which directly contacts with the electrolyte, as the first barrier, captures HF in the electrolyte, and reduces the corrosion damage to the substrate.

[0013] In some embodiments, the substrate has a chemical formula of LiNi x Mn y Coz O2, wherein x, y, z are positive values, 0≤z≤0.4, x+y+z=1. For the ternary material with relatively low Co content, the structure will be damaged due to HF corrosion, resulting in the deterioration of DCR. Through the setting of the present application, HF can be effectively captured, thereby significantly reducing the DCR and the DCR growth rate, improving the power of the battery cell, and improving the cycle life.

[0014] In some embodiments, the positive electrode active material has a volume distribution particle size Dv50 of 2-5 μm. This is beneficial to improve the compaction density of the positive electrode active material.

[0015] In some embodiments, the substrate has a volume distribution particle size Dv50 of 2-5 μm. By limiting the volume distribution particle size of the substrate, the formation of the surface coating layer thereof can be facilitated.

[0016] In some embodiments, the average particle size of the first coating layer particles is greater than the average particle size of the second coating layer particles. Thus, the particle size of the first coating layer is greater than that of the second coating layer, and the compaction degree of the first coating layer is less than that of the second coating layer. Thus, the second coating layer, which is in direct contact with the electrolyte, can more effectively hinder the release of HF to the inside.

[0017] In some embodiments, the average particle size of the first coating layer particles is greater than 10 nm and less than or equal to 500 nm. Thus, the particles of the first coating layer can be uniformly distributed on the surface of the substrate without agglomeration.

[0018] In some embodiments, the average particle size of the second coating layer particles is greater than or equal to 10 nm and less than or equal to 100 nm. Thus, the particles of the second coating layer can be uniformly distributed on the surface of the first coating layer without agglomeration.

[0019] In some embodiments, in the positive electrode active material, the weight ratio of the A element in the second coating layer to the Co element in the substrate is 1:10-200.

[0020] Setting the content of the A element based on the content of the Co element can help to set the coating amount of the second coating layer within an appropriate range, thereby helping to improve the energy density of the positive electrode active material.

[0021] The second aspect of the present application provides a method for preparing a battery cell, the method comprising preparing a positive electrode active material; the preparation of the positive electrode active material comprises:

[0022] mixing the substrate and the first raw material uniformly to obtain a first mixture,

[0023] mixing the first mixture with a second raw material to obtain a second mixture; and

[0024] sintering the second mixture to obtain a positive electrode active material, the positive electrode active material comprising: a substrate, a first coating layer on the surface of the substrate, and a second coating layer on the surface of the first coating layer;

[0025] wherein the first coating layer comprises a fast ion conductor with an ionic conductivity of 10 -9 S / cm to 10 -4 S / cm;

[0026] the second coating layer comprises a material with a chemical formula of R a A c B d , wherein R comprises at least one of Li, Na, and K, A comprises any one of Ga, Gd, Hf, La, Pr, Y, Si, Ta, and Th, and B comprises any one of O and F; wherein 0≤a≤4, 0

[0027] In some embodiments, the second raw material comprises a first compound and a second compound, and the first compound and the second compound are sintered to obtain a material with a chemical formula of R a A c B d .

[0028] In the present application, in the preparation of the positive electrode active material, the first coating layer is coated on the surface of the substrate and the second coating layer is formed in situ by growth on the surface of the first coating layer through one-step sintering, so that the first coating layer and the second coating layer are formed simultaneously and are more stable, and the improvement effect on the DCR of the secondary battery is better.

[0029] In some embodiments, the sintering is performed at 400°C to 900°C for 4 hours to 12 hours.

[0030] By performing the coating layer sintering under the above conditions, on the one hand, the coating layer is firm, and on the other hand, the particles of the coating layer have appropriate particle size and distribution uniformity.

[0031] In some embodiments, the sintering is performed in an inert atmosphere or in an HF atmosphere.

[0032] By performing the sintering under the above conditions, the formation of the coating layer is facilitated, and the formed coating layer is further firm and has appropriate particle size and distribution uniformity.

[0033] A third aspect of the present application provides a battery device comprising the battery cell of the first aspect of the present application or the battery cell obtained by the preparation method according to the second aspect of the present application.

[0034] The battery device of this application includes the aforementioned battery cell and therefore has at least the same advantages as the aforementioned battery cell.

[0035] The fourth aspect of this application provides an electrical device, including a battery cell according to the first aspect of this application, a battery cell obtained according to the preparation method according to the second aspect of this application, or a battery device according to the second aspect of this application.

[0036] The electrical device of this application includes the aforementioned battery cell and therefore has at least the same advantages as the battery cell. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application.

[0038] Figure 2 yes Figure 1 An exploded view of a battery cell according to one embodiment of this application is shown.

[0039] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application.

[0040] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0041] Figure 5 yes Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown.

[0042] Figure 6 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0043] Figure 7 The graph shows a comparison of the DCR growth rate of the secondary batteries of Examples 1, 2 and Comparative Example 1 at 45°C with the number of cycles.

[0044] Figure 8 A graph comparing the DCR growth rate of the secondary batteries in Examples 1, 2 and Comparative Example 1 at 60°C with the number of storage days is shown.

[0045] Explanation of reference numerals in the attached figures:

[0046] 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery module; 5. Battery cell; 51. Housing; 52. Electrode assembly; 53. Top cover assembly. Detailed Implementation

[0047] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the battery cell, its preparation method, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0048] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0049] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0050] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0051] Unless otherwise specified, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0052] Unless otherwise specified, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in this application.

[0053] During the charge-discharge cycle of a secondary battery, HF in the electrolyte may corrode and damage the positive electrode material, leading to a deterioration in the DCR of the secondary battery, thereby reducing the output power and service life of the secondary battery.

[0054] Based on this, this application proposes a battery cell and its preparation method, a battery device and an electrical device. The following provides a detailed description of this application and its optional embodiments.

[0055] battery cell

[0056] The first aspect of this application provides a battery cell.

[0057] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0058] The battery cell can be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, or a sodium metal battery; however, this application does not limit the types of batteries used.

[0059] Typically, a battery cell includes a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0060] [Positive electrode plate]

[0061] The positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes a positive electrode active material, which includes: a substrate, a first coating layer located on the surface of the substrate, and a second coating layer located on the surface of the first coating layer.

[0062] The first coating layer has an ionic conductivity of 10. -9 S / cm to 10 -4 Fast ion conductors with a speed of S / cm;

[0063] The second coating layer includes a chemical formula R. a A c B d The material includes R, which includes at least one of Li, Na, and K; A includes any one of Ga, Gd, Hf, La, Pr, Y, Si, Ta, and Th; and B includes any one of O and F; wherein 0 ≤ a ≤ 4, 0 < c ≤ 5, and 1 ≤ d ≤ 12.

[0064] In this application, the positive electrode active material used in the battery cell includes a substrate, a first coating layer located on the surface of the substrate, and a second coating layer located on the surface of the first coating layer; wherein, the first coating layer at least covers a portion of the substrate surface and is in direct contact with the substrate, and the second coating layer at least covers a portion of the first coating layer surface and is in direct contact with the first coating layer. Here, the substrate is located at the core, the second coating layer is located on the outermost side and is in contact with the electrolyte, and the first coating layer is located between the substrate and the second coating layer.

[0065] Here, the second coating layer acts as the first barrier to intercept HF, directly contacting the electrolyte to capture HF in the electrolyte, thereby reducing the corrosive damage of HF to the active material (i.e., the matrix).

[0066] In this second coating layer, element A and F ions in HF exhibit strong binding ability and high stability after binding, thereby immobilizing F ions and reducing the corrosive damage of HF to the active material. In this application, the term "fast ionic conductor" has a meaning known in the art, and its most fundamental characteristic distinguishing it from general ionic conductors is that it possesses ionic conductivity comparable to that of liquid electrolytes and a low ionic conductivity activation energy within a certain temperature range.

[0067] Here, the first coating layer acts as a second barrier to intercept HF. The first coating layer is in direct contact with the substrate, further intercepting the HF that the second coating layer failed to intercept, thereby further reducing the corrosive damage of HF to the active material. In addition, the first coating layer can improve the conductivity to compensate for the deterioration of conductivity caused by the second coating layer, thereby improving the initial DCR and DCR growth rate of the battery cell.

[0068] Therefore, the first and second coating layers can reduce the corrosive damage of HF to the active material and inhibit the dissolution of transition metal ions, thereby reducing the DC internal resistance of the battery cell and improving the output power and service life of the battery cell.

[0069] It should be noted that the DC internal resistance of a single battery cell directly affects its output voltage and current. The lower the DC internal resistance of the battery, the more stable the output voltage and current. Conversely, the higher the DC internal resistance of the battery, the lower the output voltage and current will be, and the less power it can provide.

[0070] Furthermore, the DC internal resistance of individual battery cells can cause self-discharge. Even when the battery is not in operation, internal current still flows, leading to power loss within the cell. Secondly, the DC internal resistance of individual battery cells affects charging and discharging efficiency. The higher the DC internal resistance, the greater the energy loss during charging and discharging, and the longer the charging time. Finally, the DC internal resistance of individual battery cells also affects their temperature changes. It causes the battery to generate heat during high-current discharge, increasing the risk of overheating. Therefore, the higher the DC internal resistance of a battery, the shorter its lifespan.

[0071] In some embodiments, the first coating layer comprises a chemical formula of Li e M f (PO4)3 material, wherein 0 < e ≤ 3, 0 < f ≤ 3, and M includes at least one of Al, Ti, V and Zr.

[0072] Therefore, by further defining the material of the first coating layer, this application is beneficial for the first coating layer to intercept HF, and at the same time, it is beneficial to improve the conductivity of the positive electrode active material.

[0073] In some specific embodiments, the material of the first coating layer includes LiZr2(PO4)3, which has an ionic conductivity of 2.8 × 10⁻⁶. -6 S / cm; In some embodiments, the material of the first coating layer includes Li 1.3 Al 0.3 Ti 1.7 (PO4)3 has an ionic conductivity ranging from 1.792 × 10⁻⁶. -6 S / cm; In some embodiments, the material of the first coating layer includes Li3V2(PO4)3, whose ionic conductivity ranges from 10. -9 S / cm to 10 -7 S / cm.

[0074] In this application, ionic conductivity is determined by alternating current impedance spectroscopy. The specific steps include: 1. Preparing a blocking electrode: Using a analyte of a specific diameter and thickness as a blocking electrode, typically fabricated by magnetron sputtering; 2. Applying an alternating current voltage: Applying an alternating current voltage of a certain frequency and amplitude, such as 10mV, to the blocking electrode; 3. Measuring the alternating current impedance: Measuring the alternating current impedance using a frequency response analyzer and recording the changes in voltage and current; 4. Calculating the ionic conductivity: Using the measured impedance data, combined with the thickness and area of ​​the analyte, calculating the ionic conductivity using the formula σ = L / SR, where σ is the ionic conductivity, L is the thickness of the analyte, S is the area, and R is the volume resistivity.

[0075] In some embodiments, for the material R in the second coating layer aA c B d A includes either Y or Si.

[0076] Therefore, by further specifying the material of the second coating layer, this application facilitates the capture of HF by the second coating layer, which can further reduce the corrosive damage of HF to the positive electrode active material, thereby reducing the DC internal resistance of the secondary battery and improving the output power and service life of the secondary battery. Furthermore, the materials for the aforementioned second coating layer have a wide range of options and are readily available.

[0077] In some implementations, the coating density of the first coating layer is less than that of the second coating layer.

[0078] Since the second coating layer is located on the outermost side and is in direct contact with the electrolyte, a denser coating will be more effective in capturing HF in the electrolyte, thereby reducing corrosion damage to the positive electrode active material. By limiting the coating amounts of the first and second coating layers within a suitable range, the thicknesses of the first and second coating layers can also be kept within a suitable range, reducing the initial DCR of the secondary battery.

[0079] In some embodiments, the content of element M, based on the weight of the positive electrode active material, is between 100 ppm and 2000 ppm, for example, values ​​between 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1500 ppm, 2000 ppm, or any range of two such values. Element M is an element introduced solely by the first coating layer and is therefore referred to as the characteristic element of the first coating layer. The content of this characteristic element can be determined by performing inductively coupled plasma (ICP) testing, and the coating amount of the coating layer can then be calculated based on its molecular formula.

[0080] For example, disassemble the battery, scrape off the positive electrode film, and then dissolve the film with a suitable solvent; select an appropriate dilution factor based on the measurement range of the element to be measured to ensure that the measurement results are within the linear range of the instrument; turn on the ICP spectrometer and preheat it; select the corresponding calibration curve according to the requirements of the element to be measured, and calibrate the instrument by adding a standard solution of known concentration; inject the diluted sample into the ICP spectrometer through an automatic injection system or manual injection; set the required analytical parameters, such as ion energy and gas flow rate; start the ICP spectrometer to begin data acquisition and analysis; the instrument will generate a spectrum showing the emission or absorption peaks of different elements; calculate the concentration of the element in the sample based on the calibration curve and peak area.

[0081] Therefore, by limiting the content of element M, i.e. limiting the amount of coating of the first coating layer, the first coating layer forms an effective coating on the substrate surface, which is conducive to its function of intercepting HF and its conductivity, further reducing the corrosion damage of HF to the substrate and improving the conductivity.

[0082] In some embodiments, the content of element A is between 100 ppm and 5000 ppm based on the weight of the positive electrode active material, for example, values ​​between 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, or any range of two such values. Element A is introduced solely by the second coating layer and is therefore referred to as the characteristic element of the second coating layer. Similarly, the content of this characteristic element can be determined by performing inductively coupled plasma (ICP) testing, and the coating amount can then be calculated based on the molecular formula of the coating layer.

[0083] Therefore, by limiting the content of element A, this application limits the amount of coating of the second coating layer. The second coating layer can effectively coat the surface of the first coating layer and directly contact the electrolyte. As the first barrier, it effectively captures HF in the electrolyte, thereby reducing corrosion damage to the substrate.

[0084] In some embodiments, the chemical formula of the matrix is ​​LiNi. x Mn y Co z O2, where x, y, and z are all positive values, 0 ≤ z ≤ 0.4, and x + y + z = 1.

[0085] Therefore, during the charge-discharge cycle of a secondary battery, HF in the electrolyte may corrode and damage the positive electrode active material, leading to a deterioration in the discharge coefficient (DCR) and thus reducing the battery's output power and lifespan. This is especially true for positive electrode active materials with low cobalt content, where HF corrosion can further worsen the DCR. Therefore, for positive electrode active materials with low cobalt content, forming a first coating layer and a second coating layer on their surface can more effectively reduce the DCR, thereby improving the battery's output power and lifespan.

[0086] In some embodiments, the volume distribution particle size Dv50 of the positive electrode active material is 2 μm to 5 μm. This is beneficial to the compaction density of the positive electrode active material.

[0087] In some embodiments, the volumetric particle size distribution Dv50 of the matrix is ​​2 μm to 5 μm. By limiting the volumetric particle size distribution of the matrix, it is beneficial to form its surface coating layer.

[0088] In this application, the volumetric particle size Dv50 has a well-known meaning in the art, representing the particle size corresponding to a cumulative volumetric distribution percentage of 50%, which can be determined using instruments and methods known in the art. For example, it can be determined using a laser particle size analyzer, referring to GB / T 19077-2016. The testing instrument can be the Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK.

[0089] In some embodiments, the average particle size of the particles in the first coating layer is larger than the average particle size of the particles in the second coating layer. Therefore, the particle size of the resulting first coating layer is larger than that of the second coating layer, and consequently, the coating density of the first coating layer is less than that of the second coating layer. Consequently, the second coating layer, being the outermost layer and in direct contact with the electrolyte, can more effectively prevent HF from ionizing into the interior.

[0090] In this application, the average particle size has a meaning known in the art and can be measured using instruments and methods known in the art. For example, images can be obtained by measuring the material using a scanning electron microscope, a transmission electron microscope, or a particle size distribution instrument. Multiple (e.g., more than 100) coated particles can be randomly selected from the images to test the coating layer, and the average value of the shortest diagonal length of the particles can be used as the average particle size.

[0091] In some embodiments, the average particle size of the first coating layer particles is between 10 nm and 500 nm. This allows the particles of the first coating layer to be distributed relatively uniformly on the substrate surface, preventing agglomeration and accumulation.

[0092] In some embodiments, the average particle size of the second coating layer particles is 10 nm to 100 nm. Therefore, the particles of the second coating layer can be distributed relatively uniformly on the surface of the first coating layer, without agglomeration or accumulation.

[0093] In some embodiments, in the positive electrode active material, the weight ratio of element A in the second coating layer to element Co in the matrix is ​​1:10-200, optionally 1:20-130, for example 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, 1:80, etc. 1:85, 1:90, 1:95, 1:100, 1:105, 1:110, 1:115, 1:120, 1:125, 1:130, 1:135, 1:140, 1:145, 1:150, 1:155, 1:165, 1:170, 1:175, 1:180, 1:185, 1:190, 1:195, 1:200.

[0094] Setting the content of element A based on the content of element Co can help to set the coating amount of the second coating layer within a suitable range, thereby contributing to the energy density of the positive electrode active material.

[0095] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0096] During the charging and discharging process of a battery, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this application, the molar Li content refers to the initial state of the material, i.e., before feeding. When the positive electrode active material is applied to the battery system, the molar Li content changes after charge-discharge cycles.

[0097] In the examples of positive electrode active materials in this application, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate.

[0098] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0099] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0100] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0101] [Negative electrode plate]

[0102] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0103] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0104] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0105] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The aforementioned silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The aforementioned tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0106] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0107] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0108] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0109] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0110] [Electrolytes]

[0111] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0112] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0113] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0114] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0115] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0116] [Isolation membrane]

[0117] In some embodiments, the battery cell also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0118] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0119] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0120] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0121] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0122] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 The example shown is a square-structured battery cell 5.

[0123] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a top cover assembly 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can cover the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0124] Preparation method of battery cell

[0125] This application also provides a method for preparing a battery cell. The method includes preparing the aforementioned positive electrode active material. The preparation of the positive electrode active material includes:

[0126] The matrix and the first raw material are mixed evenly to obtain a first mixture;

[0127] The first mixture is mixed evenly with the second raw material to obtain a second mixture; and

[0128] The second mixture is sintered to obtain a positive electrode active material, which includes: a matrix, a first coating layer located on the surface of the matrix, and a second coating layer located on the surface of the first coating layer;

[0129] The first coating layer comprises layers with an ionic conductivity of 10. -9 S / cm to 10 -4 Fast ion conductors with a speed of S / cm;

[0130] The second coating layer includes a chemical formula R. a A c B d The material includes R, which includes at least one of Li, Na, and K; A includes any one of Ga, Gd, Hf, La, Pr, Y, Si, Ta, and Th; and B includes any one of O and F; wherein 0 ≤ a ≤ 4, 0 < c ≤ 5, and 1 ≤ d ≤ 12.

[0131] In this application, the first raw material includes materials with an ionic conductivity in the range of 10. -9 S / cm to 10 -4 Fast ion conductor with a speed of S / cm.

[0132] In this application, the second raw material comprises a first compound and a second compound, wherein the first compound and the second compound are sintered in one step to obtain a chemical formula R. a A c B d The material includes R, which includes at least one of Li, Na, and K; A includes any one of Ga, Gd, Hf, La, Pr, Y, Si, Ta, and Th; and B includes any one of O and F; wherein 0 ≤ a ≤ 4, 0 < c ≤ 5, and 1 ≤ d ≤ 12.

[0133] Therefore, this application obtains a positive electrode active material by blending a first raw material onto the surface of a substrate, then blending a second raw material onto the surface of the first coating layer, and finally sintering the mixture. In this application, during the preparation of the positive electrode active material, a first coating layer formed from the first raw material is formed on the surface of the substrate by a single sintering process, and a second coating layer is formed by in-situ growth of the second raw material on the surface of the first coating layer. Therefore, a more stable first and second coating layer can be formed simultaneously, and the first and second coating layers are less likely to detach, resulting in a better DCR improvement effect on the secondary battery.

[0134] In some embodiments, the first raw material comprises materials with an ionic conductivity in the range of 10. -9 S / cm to 10 -4 A fast ion conductor with a speed of S / cm. Optionally, the first raw material includes Li e M f (PO4)3 materials, M includes at least one of Al, Ti, V and Zr.

[0135] After sintering, the first raw material forms a first coating layer that covers the surface of the substrate. Therefore, by further specifying the material of the first coating layer, this application can further reduce the corrosive damage of HF to the positive electrode active material and improve its conductivity.

[0136] In some embodiments, the first and second compounds react after sintering to form a compound with the chemical formula R. a A c B d The material is used to cover the surface of the first coating layer.

[0137] In some embodiments, the first compound may be, for example, a base, such as LiOH, NaOH, or KOH; or, for example, a carbonate, such as Li₂CO₃, Na₂CO₃, or K₂CO₃; or, for example, a bicarbonate, such as LiHCO₃, NaHCO₃, or KHCO₃.

[0138] The first and second compounds can react under an inert atmosphere to form a salt, thereby forming a second coating layer; wherein the formed second coating layer includes the element O. Alternatively, the first and second compounds can react under an HF atmosphere to form a salt, thereby forming a second coating layer; wherein the formed second coating layer includes the element F.

[0139] In some implementations, element A includes either Y or Si.

[0140] In some embodiments, the volumetric particle size Dv50 of the first raw material ranges from 1 nm to 500 nm, and optionally from 10 nm to 100 nm.

[0141] In some embodiments, the amount of the first raw material added is calculated, for example, based on the content of element M in the designed positive electrode active material. For example, based on the fact that the content of element M in the designed positive electrode active material is 100 ppm to 2000 ppm, the amount of the first raw material added is calculated based on the molecular formula of the first raw material used.

[0142] The volume distribution particle size of the second raw material is expressed as the volume distribution particle size of the second compound. For example, its Dv50 ranges from 1 nm to 100 nm, and optionally from 10 nm to 50 nm.

[0143] In some embodiments, the amount of the second raw material added is calculated, for example, based on the content of element M in the designed positive electrode active material. For example, based on the content of element A in the designed positive electrode active material being 100 ppm to 5000 ppm, the amount of the second raw material added is calculated based on the molecular formula of the second raw material used.

[0144] Since the volumetric particle size of the substrate itself is at the micrometer level, and the volume distribution particle size Dv50 is 2μm to 5μm, effective coating can only be achieved when the volume distribution particle size of the first and second raw materials is at the nanometer level. By limiting the volume distribution particle size of the first and second coating layer raw materials within a suitable range, the raw materials of the first and second coating layers are less prone to particle aggregation. The first coating layer can be uniformly distributed on the substrate surface, and the second coating layer can be uniformly distributed on the surface of the first coating layer, better protecting the positive electrode active material. This is more conducive to reducing the DCR of the secondary battery, thereby improving the output power and service life of the secondary battery. Furthermore, by using raw materials with the above-mentioned volume distribution particle size and controlling the sintering temperature and time, the volume distribution particle size Dv50 of the particles in the formed first coating layer is 10nm to 500nm, and the volume distribution particle size Dv50 of the particles in the second coating layer is 10nm to 100nm.

[0145] In some embodiments, sintering is carried out at 400°C to 900°C, or optionally at 500°C to 800°C for 4 to 12 hours.

[0146] By sintering the coating layer under the above conditions, the coating layer can be made strong, and the particles of the coating layer have appropriate particle size and uniform distribution.

[0147] In some embodiments, sintering is carried out in an inert atmosphere or in an HF atmosphere.

[0148] Therefore, by further limiting the sintering temperature, sintering time, and sintering environment, this application makes the sintering process more complete, the first and second coating layers more robust, and the volume distribution and particle size of the first and second coating layers are appropriate. The first and second coating layers can be evenly distributed without causing particle aggregation, which is more conducive to reducing the DCR of the secondary battery, thereby improving the output power and service life of the secondary battery.

[0149] Battery device

[0150] This application also provides a battery device, including the aforementioned battery cell, or a battery cell obtained by the aforementioned preparation method. The battery device may be a battery module or a battery pack, etc.

[0151] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0152] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0153] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0154] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0155] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0156] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0157] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0158] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0159] In some embodiments, the housing can be part of the vehicle's chassis structure. For example, a portion of the housing can be at least a part of the vehicle's floor, or a portion of the housing can be at least a part of the vehicle's crossbeams and longitudinal beams. The technical solutions described in the embodiments of this application are applicable to various electrical devices using individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0160] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0161] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0162] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0163] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0164] Electrical appliances

[0165] This application also provides an electrical device, which will be described below with appropriate reference to the accompanying drawings.

[0166] The electrical device of this application includes the battery cell of this application, the battery cell obtained by the preparation method provided in this application, or the battery device of this application. The battery cell can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0167] As an electrical device, you can choose individual battery cells or battery packs, such as battery modules or battery packs, according to your usage requirements.

[0168] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0169] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0170] Example

[0171] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0172] Example 1

[0173] 1. Preparation of positive electrode sheet

[0174] Weigh 10 kg of LiNi substrate 0.55 Mn 0.39 Co 0.06 O2 (Dv50 is 3.8 μm) was added to 27.3 g of LiZr2(PO4)3 (slight excess, Dv50 is 50 nm), and then the mixture was thoroughly mixed at room temperature and sieved (1000 mesh sieve) to obtain the first mixture.

[0175] Then, 22.5g of SiO2 (slight excess, Dv50 of 20nm) and 18g of LiOH were added to the first mixture, and the mixture was sieved (1000 mesh) to obtain the second mixture.

[0176] The second mixture was transferred to a muffle furnace and sintered at 800°C for 6 hours under a nitrogen atmosphere to obtain the positive electrode active material.

[0177] The above-sintered positive electrode active material, conductive agent SP, and binder PVDF are dissolved in NMP solvent at a weight ratio of 8:1:1, and the mixture is stirred and mixed thoroughly to obtain the positive electrode slurry.

[0178] Then, the above positive electrode slurry is uniformly coated onto the positive electrode current collector aluminum foil, and after drying, cold pressing and slitting, the positive electrode sheet is obtained.

[0179] 2. Preparation of battery cells

[0180] Artificial graphite (Dv50 of 20μm), conductive agent SP, and binder CMC are mixed thoroughly in an appropriate amount of solvent at a weight ratio of 8:1:1 to form a negative electrode slurry with a solid content of 50%. The negative electrode slurry is coated on the surface of the negative electrode current collector copper foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0181] The above-mentioned positive electrode, negative electrode, and separator PP (12μm thick) are assembled and injected with electrolyte to obtain a secondary battery. The electrolyte is prepared by adding lithium hexafluorophosphate (LiPF6) to a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a mass ratio of 30:50:20 and mixing evenly. The molar concentration of LiPF6 in the electrolyte is 1 mol / L.

[0182] Example 2

[0183] Weigh 10 kg of the substrate LiNi 0.55 Mn 0.39 Co 0.06 O2 (Dv50 is 3.8 μm) was added to 27.3 g of LiZr2(PO4)3 (slight excess, Dv50 is 50 nm), and then the mixture was thoroughly mixed at room temperature and sieved (1000 mesh sieve) to obtain the first mixture.

[0184] The first mixture was then transferred to a muffle furnace and sintered at 800°C for 6 hours under a nitrogen atmosphere.

[0185] Add 22.5g of SiO2 (slight excess, Dv50 is 20nm) and 18g of LiOH to the first sintering product, mix them evenly and sieve (1000 mesh sieve) to obtain the second mixture.

[0186] The second mixture was transferred to a muffle furnace and sintered at 400°C for 3 hours under a nitrogen atmosphere to obtain the positive electrode active material.

[0187] In addition, secondary batteries were prepared in the same manner as in Example 1.

[0188] Comparative Example 1

[0189] Weigh 10 kg of the substrate LiNi 0.55 Mn 0.39 Co 0.06 O2 (Dv50 is 3.8μm), 22.5g of SiO2 (slight excess, Dv50 is 20nm) and 18g of LiOH were added, and then the mixture was thoroughly mixed at room temperature and sieved (1000 mesh sieve) to obtain the first mixture;

[0190] Then, 27.3g of LiZr2(PO4)3 (slight excess, Dv50 of 50nm) was added to the first mixture, and the mixture was then sieved (1000 mesh sieve) to obtain the second mixture.

[0191] The second mixture was transferred to a muffle furnace and sintered at 800°C for 6 hours under a nitrogen atmosphere to obtain the positive electrode active material.

[0192] The secondary battery was then prepared in the same manner as in Example 1.

[0193] Comparative Example 2

[0194] Weigh 10 kg of the substrate LiNi 0.55 Mn 0.39 Co 0.06 O2 (Dv50 is 3.8μm) was added to 27.3g LiZr2(PO4)3 (slight excess, Dv50 is 50nm), and the mixture was then sieved uniformly at room temperature (1000 mesh sieve). The mixture was then transferred to a muffle furnace and sintered at 800℃ for 6 hours under a nitrogen atmosphere to obtain the positive electrode active material.

[0195] In addition, secondary batteries were prepared in the same manner as in Example 1.

[0196] Comparative Example 3

[0197] Weigh 10 kg of the substrate LiNi 0.55 Mn 0.39 Co 0.06 O2 (Dv50 is 3.8μm) was added to 22.5g SiO2 (slight excess, Dv50 is 20nm) and 18g LiOH. The mixture was thoroughly mixed and sieved (1000 mesh sieve). Then it was transferred to a muffle furnace and sintered at 400℃ for 3 hours under a nitrogen atmosphere to obtain the positive electrode active material.

[0198] In addition, secondary batteries were prepared in the same manner as in Example 1.

[0199] Battery cell performance testing

[0200] 1. DC internal resistance test

[0201] The initial capacity C0 of a single battery cell is calibrated at room temperature, and the discharge current (DCR) is tested. The test method is as follows: the battery cell is discharged at 0.33C to 50% SOC, and then discharged at 4C for 30s. The voltage values ​​V0 and V1 before and after discharge are extracted. The DCR calculation formula corresponding to 50% SOC is R0 = (V0 - V1) / I0, where I0 is the corresponding discharge current.

[0202] 2.45℃ Cyclic DCR Growth Rate

[0203] The battery cells were placed in a 45°C chamber, with a test voltage range of 2.8V to 4.35V. They were charged at 1C to 4.35V, then charged with a small current (CV) of 0.05C to 4.35V. After resting for 30 minutes, they were discharged at 1C to 2.8V. After every 100 cycles, the capacity Cn (n = 1, 2, 3, 4, ...) was recalibrated at room temperature. The discharge DCR (Droutine Rate) Rn (n = 1, 2, 3, 4, ...) at 50% SOC was retested using the DC internal resistance test method. This cycle was repeated until Cn / C0 ≤ 80%.

[0204] The cyclic DCR growth rate F = Rn / R0-1 is used as the abscissa and F as the ordinate to obtain the cyclic DCR growth trend graph.

[0205] 3.60℃ storage DCR growth rate

[0206] The initial capacity C0 of a single battery cell was calibrated at room temperature, and the initial DCR was tested using the DC internal resistance test method, denoted as R0. Subsequently, the cell was charged to 97% SOC at a current of 0.33C and placed in a 60℃ incubator. During storage, the cell was removed, allowed to return to room temperature, and the DCR after storage was tested using the same method, denoted as Rn. Where M = (Rn - R0) / R0 represents the storage DCR growth rate. Plotting the storage days on the x-axis and M on the y-axis yields the storage DCR growth trend graph.

[0207] The performance of the battery cells prepared in Examples 1-2 and Comparative Example 1 was tested. The results are shown in Tables 1 and 2 below. Figure 7 and Figure 8 middle.

[0208] Table 1. Cyclic DCR Growth Rate at 45℃

[0209] Cycles Comparative Example 1 Example 2 Example 1 0 0 0 0 100 0.192279 0.130153 0.084054 200 0.298596 0.192308 0.131026 300 0.4239 0.265375 0.169345 400 0.487342 0.315136 0.207663 500 0.558228 0.362282 0.226205 600 0.644304 0.424318 0.257107 700 0.675949 0.442928 0.27194 800 0.750447 0.499841 0.299135 900 0.840507 0.542184 0.318912 1000 0.918988 0.599255 0.341161

[0210] Table 2. DCR Growth Rate at 60℃

[0211] Days of storage Comparative Example 1 Example 2 Example 1 0 0 0 0 15 0.419716 0.335853 0.279074 32 0.617729 0.431892 0.379509 62 0.901662 0.607158 0.51173 100 1.278979 0.874915 0.70802

[0212] The performance of the battery cells prepared in Comparative Examples 2 and 3 was further tested. The results, along with the data from Tables 1 and 2, are summarized in Table 3 below.

[0213] Table 3

[0214]

[0215] From Tables 1 to 3 above and Figure 7 and Figure 8 It is understood that the battery cell conforming to this application has a reduced initial DCR and a reduced DCR growth rate, thereby having improved output power and service life.

[0216] Example 3

[0217] Battery cells were prepared using the same method as in Example 1, except that 22.5 g of SiO2 (slight excess, Dv50 of 20 nm) and 30 g of NaOH were added to the first mixture.

[0218] Example 4

[0219] Battery cells were prepared using the same method as in Example 1, except that 22.5 g of SiO2 (slight excess, Dv50 of 20 nm) and 34.5 g of KOH were added to the first mixture.

[0220] Example 5

[0221] Battery cells were prepared using the same method as in Example 1, except that 23.2 g of Y2O3 (slight excess, Dv50 of 20 nm) and 2.0 g of LiOH were added to the first mixture.

[0222] Example 6

[0223] The battery cell was prepared using the same method as in Example 1, except that 10 kg of substrate LiNi was weighed. 0.55 Mn 0.39 Co 0.06 O2 (Dv50 is 3.8μm), 49.74g of Li was added. 1.3 Al 0.3 Ti 1.7 (PO4)3 (slight excess, Dv50 is 50nm).

[0224] Example 7

[0225] The battery cell was prepared using the same method as in Example 1, except that 10 kg of substrate LiNi was weighed. 0.55 Mn 0.39 Co 0.06O2 (Dv50 is 3.8 μm), 42.1 g of Li3V2(PO4)3 (slight excess, Dv50 is 50 nm) was added.

[0226] The battery cells prepared in Examples 3 to 7 above were subjected to performance tests. The results are shown in Table 4 below.

[0227] Table 4

[0228]

[0229]

[0230] As shown in Table 4, within the scope of the first and second coating materials defined in this application, the battery cell has a reduced initial DCR and a reduced DCR growth rate, thereby having improved output power and service life.

[0231] Example 8

[0232] Battery cells were prepared using the same method as in Example 1, except that 2.25 g of SiO2 (slight excess, Dv50 of 20 nm) and 1.8 g of LiOH were added to the first mixture.

[0233] Example 9

[0234] Battery cells were prepared using the same method as in Example 1, except that 11.23 g of SiO2 (slight excess, Dv50 of 20 nm) and 9.0 g of LiOH were added to the first mixture.

[0235] Example 10

[0236] Battery cells were prepared using the same method as in Example 1, except that 45g of SiO2 (slight excess, Dv50 of 20nm) and 35.8g of LiOH were added to the first mixture.

[0237] Example 11

[0238] Battery cells were prepared using the same method as in Example 1, except that 112.3 g of SiO2 (slight excess, Dv50 of 20 nm) and 89.5 g of LiOH were added to the first mixture.

[0239] Example 12

[0240] The battery cell was prepared using the same method as in Example 1, except that 10 kg of substrate LiNi was weighed. 0.55 Mn 0.39 Co 0.06O2 (Dv50 is 3.8 μm), 2.73 g of LiZr2(PO4)3 (slight excess, Dv50 is 50 nm) was added.

[0241] Example 13

[0242] The battery cell was prepared using the same method as in Example 1, except that 10 kg of substrate LiNi was weighed. 0.55 Mn 0.39 Co 0.06 O2 (Dv50 is 3.8 μm), 13.65 g of LiZr2(PO4)3 (slight excess, Dv50 is 50 nm) was added.

[0243] Example 14

[0244] The battery cell was prepared using the same method as in Example 1, except that 10 kg of substrate LiNi was weighed. 0.55 Mn 0.39 Co 0.06 O2 (Dv50 is 3.8μm), 54.6g of LiZr2(PO4)3 (slight excess, Dv50 is 50nm) was added.

[0245] The battery cells prepared in Examples 8 to 14 above were subjected to performance tests. The results are shown in Table 5 below.

[0246] Table 5

[0247]

[0248]

[0249] As shown in Table 5, within the M and A contents defined in this application, i.e. the coating amounts of the first and second coating layers, the battery cell has a reduced initial DCR and a reduced DCR growth rate, thus indicating that it has improved output power and service life.

[0250] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell comprising a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive film layer disposed on at least one surface of the positive current collector, the positive film layer comprising a positive active material, characterized in that, The positive electrode active material comprises: a substrate, a first coating layer on a surface of the substrate, and a second coating layer on a surface of the first coating layer. The first cladding layer comprises a fast ion conductor with an ionic conductivity of 10 -9 S / cm to 10 -4 S / cm. The second cladding layer includes a material with a chemical formula of R a A c B d wherein R includes at least one of Li, Na, and K, A includes any one of Ga, Gd, Hf, La, Pr, Y, Si, Ta, and Th, and B includes any one of O and F; wherein 0≤a≤4, 0 2. The battery cell of claim 1, wherein, The first cladding layer includes a material of the formula Li e M f (PO4)3, where 0 < e < 3, 0 < f < 3, and M includes at least one of Al, Ti, V, and Zr.

3. The battery cell according to any one of claims 1 to 2, characterized in that, A comprises any one of Si and Y.

4. The battery cell according to any one of claims 2 to 3, characterized in that, The content of the M element is 100 ppm to 2000 ppm based on the weight of the positive electrode active material.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The content of the A element is 100 ppm to 5000 ppm based on the weight of the positive electrode active material.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The chemical formula of the base body is LiNi x Mn y Co z O2, wherein x, y, z are positive values, 0≤z≤0.4, x+y+z=1.

7. The electrode monomer according to any one of claims 1 to 6, characterized in that, The volume distribution particle size Dv50 of the positive electrode active material is 2 μm to 5 μm.

8. The battery cell of any one of claims 1 to 7, wherein, The volume distribution particle size Dv50 of the substrate is 2 μm to 5 μm.

9. The battery cell of any one of claims 1 to 8, wherein, The average particle size of the first coating layer particles is greater than the average particle size of the second coating layer particles.

10. The battery cell of claim 9, wherein, The average particle size of the first coating layer particles is greater than 10 nm and less than or equal to 500 nm; and / or the average particle size of the second coating layer particles is greater than or equal to 10 nm and less than or equal to 100 nm.

11. The battery cell of any one of claims 1 to 10, wherein, In the positive electrode active material, the weight ratio of the A element in the second coating layer to the Co element in the substrate is 1:10-200.

12. A method of producing a battery cell, characterized by, The method comprises preparing a positive electrode active material; The preparation of the positive electrode active material comprises: mixing the substrate and the first raw material uniformly to obtain a first mixture; mixing the first mixture and the second raw material uniformly to obtain a second mixture; and sintering the second mixture to obtain a positive electrode active material, the positive electrode active material comprising: a substrate, a first coating layer on a surface of the substrate, and a second coating layer on a surface of the first coating layer; wherein the first cladding layer comprises a fast ion conductor having an ionic conductivity of 10 -9 S / cm to 10 -4 S / cm. The second cladding layer includes a material of a chemical formula of R a A c B d , wherein R includes at least one of Li, Na, and K, A includes any one of Ga, Gd, Hf, La, Pr, Y, Si, Ta, and Th, and B includes any one of O and F; wherein 0≤a≤4, 0 13. The method of claim 12, wherein, The second raw material includes a first compound and a second compound, and the first compound and the second compound are sintered in one step to obtain a material of the chemical formula R a A c B d .

14. The production method according to claim 12 or 13, characterized by, The sintering is performed at 400°C to 900°C for 4 hours to 12 hours.

15. The production method according to any one of claims 12 to 14, characterized in that, The sintering is performed in an inert atmosphere or in an HF atmosphere.

16. A battery device characterized by comprising: The battery cell of any one of claims 1 to 11 or obtained by the preparation method of any one of claims 12 to 15.

17. An electrical device, comprising: The battery cell of any one of claims 1 to 11, obtained by the preparation method of any one of claims 12 to 15, or the battery device of claim 16.

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