Positive electrode plate and its manufacturing method, electrode assembly, battery cell, battery and power consumption device

Abstract

This application relates to the field of battery technology, particularly to a positive electrode plate and a manufacturing method thereof, an electrode assembly, a battery cell, a battery, and a power consumption device. The positive electrode plate includes a current collector and a coating formed on at least one side of the current collector, and a protective film is formed on the surface of the coating, the protective film being made of a fluoride material. Considering that performance degradation occurs when the positive electrode material in the coating comes into contact with air and that interfacial side reactions occur when the positive electrode material comes into contact with an electrolyte, a protective film is formed on the surface of the coating to improve the performance of the positive electrode material, thereby reducing the chance of contact between the positive electrode material and air and reducing the probability of interfacial reactions occurring between the positive electrode material and the electrolyte, improving the stability of the positive electrode material and thereby improving battery performance.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from a Chinese patent application filed on March 28, 2023, bearing application number 202310312883.9, the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] The present application relates to the field of battery technology, and in particular to a positive electrode plate and its manufacturing method, an electrode assembly, a battery cell, a battery and a power consuming device. [Background technology]

[0003] Lithium-ion batteries have become the most popular energy storage system due to their high working potential, long service life, and environmental friendliness, and are now widely applied in fields such as pure electric vehicles, hybrid electric vehicles, and smart grids.

[0004] A problem with lithium-ion batteries is that their performance deteriorates during cycling. Summary of the Invention [Problem to be solved by the invention]

[0005] The main objective of this application is to provide a positive electrode plate aimed at improving the performance of a battery. [Means for solving the problem]

[0006] To achieve the above object, the present application provides a positive electrode plate including a current collector and a coating provided on at least one side of the current collector, wherein a protective film is provided on a surface of the coating, and the material of the protective film includes a fluoride.

[0007] The positive electrode plate of the present application includes a current collector and a coating formed on at least one side of the current collector, with a protective film formed on the surface of the coating, the protective film being made of a material containing fluoride. Considering that performance degradation occurs when the positive electrode material in the coating comes into contact with air, and that interfacial side reactions occur when the positive electrode material comes into contact with the electrolyte, a protective film is formed on the surface of the coating to improve the performance of the positive electrode material. This reduces the chance of contact between the positive electrode material and air and the probability of interfacial reactions occurring between the positive electrode material and the electrolyte, improving the stability of the positive electrode material and thereby improving battery performance.

[0008] Optionally, the thickness of the protective film ranges from 1 nm to 50 nm, preferably from 5 nm to 20 nm.

[0009] In order to ensure that the protective film effectively reduces the chance of contact between the electrolyte and the coating and ensures good lithium ion migration speed, the thickness of the protective film ranges from 1 nm to 50 nm, preferably from 5 nm to 20 nm.

[0010] Optionally, the fluoride includes at least one of lithium fluoride and aluminum fluoride.

[0011] The fluoride includes at least one of lithium fluoride and aluminum fluoride. That is, the protective film may contain lithium fluoride and aluminum fluoride simultaneously, or may be composed of lithium fluoride or aluminum fluoride independently. Of course, in some cases, other types of materials may be added to the protective film as needed. The present application is not limited and may be designed according to usage needs.

[0012] Optionally, the protective film includes a lithium fluoride protective film and an aluminum fluoride protective film, and the lithium fluoride protective film and the aluminum fluoride protective film are laminated on a surface of the coating; And / or, the protective film includes a lithium fluoride protective film and an aluminum fluoride protective film, and the lithium fluoride protective film is provided on at least a portion of the surface of the coating, and the aluminum fluoride protective film is provided on at least another portion of the surface of the coating.

[0013] The lithium fluoride protective film and the aluminum fluoride protective film are laminated on the surface of the coating. The lithium fluoride protective film 30a and the aluminum fluoride protective film 30b are alternately formed on the surface of the coating 20. For example, the lithium fluoride protective film 30a is formed on the surface of the coating 20, and the aluminum fluoride protective film 30b is formed on one side of the lithium fluoride protective film 30a away from the coating 20. Of course, the aluminum fluoride protective film 30b may be formed on the surface of the coating 20, or the lithium fluoride protective film 30a may be formed on one side of the aluminum fluoride protective film 30b away from the coating 20. The number of layers of the lithium fluoride protective film 30a and the aluminum fluoride protective film 30b is not specifically limited. For example, the lithium fluoride protective film 30a may be two layers and the aluminum fluoride protective film 30b may be one layer. The aluminum fluoride protective film 30b may be provided between the two lithium fluoride protective films 30a as needed.

[0014] A lithium fluoride protective film is provided on at least a portion of the surface of the coating, and an aluminum fluoride protective film is provided on at least another portion of the surface of the coating. The lithium fluoride protective film 30a is provided on at least a portion of the surface of the coating 20, and the aluminum fluoride protective film 30b is provided on at least another portion of the surface of the coating 20. For example, the lithium fluoride protective film 30a and the aluminum fluoride protective film 30b may be provided side by side on one surface of the coating 20. This embodiment is not particularly limited and can be considered as needed.

[0015] Optionally, the coating includes a positive electrode material, and a coating layer is formed on the surface of the positive electrode material, and the coating layer includes at least one of a sulfur-containing compound, a boron-containing compound, and a fluoride.

[0016] Positive electrode materials, such as ternary positive electrode materials, especially those with a high nickel content, tend to have a high level of residual lithium compounds present on their surfaces during synthesis. This residual lithium is highly susceptible to absorbing carbon dioxide and water from the air, forming Li2CO3 and LiOH layers on the particle surface, which have the following effects: It consumes the lithium in the material and is electrochemically inactive, resulting in capacity fade. LiOH reacts with polyvinylidene fluoride (PVDF), causing the slurry to gel. Finally, the residual LiOH on the electrode plate may further react with the LiPF6 electrolyte, consuming Li ions in the electrolyte and generating HF. HF further corrodes the positive electrode material itself, dissociating its surface. The dense Li2CO3 layer on the positive electrode particle surface subsequently inhibits lithium diffusion, affecting the battery's electrical performance.

[0017] To solve the above problem, residual lithium compounds are reduced or removed by chemical reaction, and an ionically conductive coating layer is formed on the surface of the positive electrode material to reduce the polarization of the battery, and the coating layer contains at least one of a sulfur-containing compound, a boron-containing compound, and a fluoride.

[0018] Optionally, the coating layer is lithium fluoride.

[0019] The lithium fluoride coating layer is obtained by reacting with ammonium fluoride. By controlling the amount of ammonium fluoride added to the reaction, the residual lithium can be completely removed. Furthermore, the controlled operation step can effectively remove the reaction by-products, thus avoiding the introduction of new impurities.

[0020] In addition, the step of adding ammonium fluoride can be performed during the preparation of the coating slurry, eliminating the need for an additional step, thereby improving the manufacturing efficiency of the positive electrode plate.

[0021] Optionally, the mass percentage of the lithium fluoride relative to the total mass of the positive electrode material is 0.01% to 5%, preferably 0.5% to 1.2%.

[0022] In the process of reacting the residual lithium with ammonium fluoride to obtain a lithium fluoride coating layer, the amount of ammonium fluoride that needs to be added can be calculated based on the amount of residual lithium in the positive electrode material in order to completely react the residual lithium, and in the obtained positive electrode material, the mass percentage of the mass of lithium fluoride relative to the total mass of the positive electrode material is 0.01% to 5%, preferably 0.5% to 1.2%.

[0023] Optionally, the general formula of the positive electrode material in the coating is Li x Ni y M 1-y O2, 0.9≦x≦1.15, 0.6≦y≦1, and M is selected from one or more of Co, Mn, and Al; and / or the general formula of the positive electrode material in said coating is xLi2MnO3·(1−x)LiMO2, where 0.1≦x≦0.9, and M is selected from one or more of Co, Mn, and Al.

[0024] The cathode material in the coating is a layered Li x Ni y M 1-y O2, where 0.9≦x≦1.15 and 0.6≦y≦1, and M is selected from one or more of Co, Mn, and Al; and / or a lithium-rich manganese-based positive electrode material xLi2MnO3·(1-x)LiMO2, where 0.1≦x≦0.9, and M is selected from one or more of Co, Mn, and Al.

[0025] The present application further provides a method for manufacturing a positive electrode plate, the method comprising: providing a positive electrode plate; providing a fluoride precursor; and forming a protective film on the surface of the coating of the positive electrode plate by a thin film deposition technique.

[0026] To form a protective film on the surface of the coating of the positive electrode plate, the steps include preparing a positive electrode plate, preparing a fluoride precursor, and forming a protective film on the surface of the coating of the positive electrode plate by a thin film deposition technique.

[0027] The thin film deposition technique includes chemical vapor deposition and physical vapor deposition. The present application does not limit the deposition technique used to form the protective film on the surface of the coating, and it may be selected according to the experimental environment and practical needs.

[0028] Optionally, the thin film deposition technique comprises an atomic layer deposition process.

[0029] Thin film deposition techniques include chemical vapor deposition and physical vapor deposition, and the specific process to be selected is not limited. In order to improve the effect of the protective film obtained, an atomic layer deposition process is preferably selected. The atomic layer deposition process has a better chemical composition, a high stress control ability, a smooth film formation surface, a relatively wide process window, and a wider selection range of precursors.

[0030] Optionally, the fluoride comprises lithium fluoride and / or aluminum fluoride.

[0031] Fluoride can effectively reduce the oxidation activity of the surface of the positive electrode material, inhibit the oxidative decomposition of the electrolyte at the positive electrode, and promote lithium ion transport in the solid phase. A fluoride protective film is formed on the surface of the coating of the positive electrode plate by thin film deposition technology through the preparation of a fluoride precursor, and the fluoride precursor includes a lithium fluoride precursor and / or an aluminum fluoride precursor.

[0032] Optionally, the step of forming a coating layer on the surface of the coating of the positive electrode plate by an atomic layer deposition process includes: The positive electrode plate is placed in an atomic layer deposition reaction chamber, evacuated, and the deposition temperature is set to 200°C-250°C; introducing a suitable fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness.

[0033] The material of the protective film includes a fluoride, and the type of the fluoride is not specifically limited, and a precursor may be selected based on the selected type of fluoride. The step of forming a coating layer on the surface of the coating of the positive electrode plate by atomic layer deposition includes placing the positive electrode plate in an atomic layer deposition reaction chamber, drawing a vacuum, setting a deposition temperature of 200°C-250°C, introducing a suitable fluoride precursor into the reaction chamber to form a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness.

[0034] Optionally, the steps of introducing a suitable fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness include: introducing an aluminum fluoride precursor into the reaction chamber to form a protective film on the surface of the coating, and opening a vacuum to remove unreacted precursor; introducing a lithium fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, and opening a vacuum to remove unreacted precursor; Repeating the above steps to obtain a predetermined thickness of the protective film.

[0035] The fluoride includes at least one of lithium fluoride and aluminum fluoride. To obtain a protective film of lithium fluoride and aluminum fluoride, the steps of introducing a suitable fluoride precursor into a reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness include introducing an aluminum fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and introducing a lithium fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness.

[0036] Optionally, the step of introducing an aluminum fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, and opening a vacuum to remove unreacted precursor may include: evacuating the reaction chamber to reduce the pressure to 10 Pa or less; Inject AlCl gas into the reaction chamber and maintain it for 10s-20s; introducing a sweep gas into the reaction chamber, breaking the vacuum, and removing unreacted AlCl gas; The pressure in the reaction chamber is reduced to 10 Pa or less, TiF gas is introduced into the reaction chamber, and the pressure is maintained for 10 s to 20 s. introducing a sweep gas into the reaction chamber and breaking the vacuum to remove unreacted TiF gas; Repeating the above steps to obtain a predetermined thickness of the aluminum fluoride protective film.

[0037] The aluminum fluoride precursors include AlCl3 and TiF4. The steps for producing the aluminum fluoride protective film are to evacuate the reaction chamber, reduce the pressure to below 10 Pa, introduce AlCl3 gas into the reaction chamber and maintain the pressure for 10-20 seconds, introduce a sweep gas into the reaction chamber, release the vacuum, remove unreacted AlCl3 gas, reduce the pressure in the reaction chamber to below 10 Pa, introduce TiF4 gas into the reaction chamber and maintain the pressure for 10-20 seconds, introduce a sweep gas into the reaction chamber, release the vacuum, remove unreacted TiF4 gas, and repeat the above steps to obtain an aluminum fluoride protective film with a predetermined thickness.

[0038] AlCl3 and TiF4 are in a solid state at room temperature, and in order to obtain a gaseous precursor, a temperature is set at which the precursor can be vaporized, and the solid is vaporized to obtain a gaseous precursor.

[0039] The step of introducing AlCl3 gas into the reaction chamber and maintaining it for 10s-20s is an example of introducing an appropriate amount of AlCl3 gas into the reaction chamber. The gas introduction time may be selected according to actual needs, and the present application does not specifically limit it.

[0040] Optionally, the step of introducing a lithium fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, and opening the vacuum to remove unreacted precursor may include: evacuating the reaction chamber to reduce the pressure to 10 Pa or less; Introduce alkyllithium vapor into the reaction chamber and maintain for 10 seconds to 20 seconds; introducing a sweep gas into the reaction chamber and breaking the vacuum to remove unreacted alkyllithium vapor; reducing the pressure in the reaction chamber to 10 Pa or less, introducing TiF vapor into the reaction chamber, and maintaining the pressure for 10 s to 20 s; introducing a sweep gas into the reaction chamber and breaking the vacuum to remove unreacted TiF vapor; Repeating the above steps to obtain a lithium fluoride protective film of a predetermined thickness.

[0041] The lithium fluoride precursor includes alkyllithium and TiF4. The steps of producing the lithium fluoride protective film include evacuating the reaction chamber, reducing the pressure to below 10 Pa, introducing alkyllithium vapor into the reaction chamber, maintaining the pressure for 10-20 seconds, introducing a sweep gas into the reaction chamber, releasing the vacuum, removing the unreacted alkyllithium vapor, reducing the pressure to below 10 Pa, introducing TiF4 vapor into the reaction chamber, maintaining the pressure for 10-20 seconds, introducing a sweep gas into the reaction chamber, releasing the vacuum, removing the unreacted TiF4 vapor, and repeating the above steps to obtain a lithium fluoride protective film with a predetermined thickness.

[0042] Optionally, the step of providing a positive electrode plate includes: mixing a positive electrode material with a reactive substance to cause a reaction and form a coating layer on the surface of the positive electrode material; mixing the positive electrode material having the coating layer, the adhesive, and the conductive agent, adding a solvent and stirring the mixture to obtain a positive electrode slurry; and applying the positive electrode slurry to a current collector and drying the applied positive electrode slurry to obtain a positive electrode plate. Here, the reactive substance includes at least one of a sulfur compound and a boron compound.

[0043] Residual lithium on the surface of the positive electrode material can affect battery performance, so to remove the residual lithium, a reactive substance is used to react with the residual lithium. For example, a sulfur compound or boron compound is mixed with the positive electrode material and reacted under certain conditions to form a coating layer on the surface of the positive electrode material. The coated positive electrode material, adhesive, and conductive agent are mixed, and a solvent is added and stirred to obtain a positive electrode slurry. The positive electrode slurry is then applied to a current collector and dried to obtain a positive electrode plate.

[0044] Optionally, the step of providing a positive electrode plate includes: mixing a positive electrode material, an adhesive, a conductive agent, and ammonium fluoride, adding a solvent and stirring the mixture to obtain a positive electrode slurry; and applying the positive electrode slurry to a current collector and drying the applied positive electrode slurry to obtain a positive electrode plate.

[0045] Ammonium fluoride is introduced during the slurry production process and reacts with the remaining lithium on the surface of the positive electrode material to form a lithium fluoride coating layer, which can reduce the amount of alkali remaining on the surface of the positive electrode material as needed and reduce battery polarization. Compared to using a sulfur compound or boron compound to mix with the positive electrode material and react under certain conditions to form a coating layer on the surface of the positive electrode material, this method does not require the addition of an extra step using ammonium fluoride, and instead directly adds ammonium fluoride during the slurry production process, reducing process steps and improving the production efficiency of positive electrode plates.

[0046] By converting the residual lithium into an effective lithium fluoride protective layer as a reactant, the slurry gel state can be effectively improved, the residual lithium can be removed, a fast ion conductor coating layer can be established, the conductive ability of the positive electrode plate can be improved, the polarization of the lithium ion battery can be reduced, and the power performance of the lithium ion battery can be improved.

[0047] Optionally, the amount of ammonium fluoride added ranges from 0.009% to 4.5%, preferably from 0.45% to 1.1%, based on the mass of the positive electrode material.

[0048] In the process of removing the residual lithium, the amount of ammonium fluoride that needs to be added can be calculated based on the amount of residual lithium, and the range of the amount of ammonium fluoride added based on the mass of the positive electrode material is 0.009% to 4.5%, preferably 0.45% to 1.1%.

[0049] Optionally, the step of mixing the positive electrode material, the adhesive, the conductive agent, and ammonium fluoride, adding a solvent, and stirring to obtain a positive electrode slurry may include: The process involves mixing the positive electrode material, adhesive, conductive agent, and ammonium fluoride for 5-60 minutes, adding a solvent, stirring at a rotation speed of 300-2000 r / min for 30-3 hours, removing bubbles, and evacuating to obtain a positive electrode slurry with a solid content of 60-85%.

[0050] To ensure that the ammonium fluoride and positive electrode material are thoroughly mixed and reacted effectively during the slurry preparation process, the positive electrode material, adhesive, conductive agent, and ammonium fluoride are mixed for 5-60 minutes, a solvent is added, and the mixture is stirred at a rotation speed of 300-2000 r / min for 30-3 hours to remove bubbles and evacuate, resulting in a positive electrode slurry with a solids content of 60-85%.

[0051] Ammonium fluoride reacts with the residual lithium, and the chemical reaction is as follows: 2NH4F+LiCO3→2LiF↓+(NH4)2CO3, NH4F+LiOH→LiF↓+NH3↑+H2O↑

[0052] The by-products of the reaction are all substances that are easily volatile or that volatilize upon decomposition, and in order to facilitate removal of the by-products, bubbles are removed and air is bled during the operation.

[0053] In other words, a corresponding amount of ammonium fluoride is calculated and used as a source of residual lithium, and the ammonium fluoride and the positive electrode material are thoroughly brought into contact with each other under stirring conditions of the slurry to mix uniformly and react with each other. After stirring is completed, a portion of the gas product is removed by bleed-off during the bubble removal step.

[0054] Optionally, the step of applying the positive electrode slurry to a current collector and drying it to obtain a positive electrode plate may include: The positive electrode slurry is applied to a current collector and dried at a temperature of 100°C to 170°C to obtain a positive electrode plate.

[0055] In order to ensure the decomposition and removal of the reaction by-product (NH4)2CO3 effectively, the ammonium carbonate is decomposed and removed by adjusting the drying temperature during the drying process. The drying temperature is 100-170°C. Under these drying conditions, the product (NH4)2CO3 is decomposed and discharged along the gas path, which is favorable for the rapid decomposition and removal of (NH4)2CO3 and improves production efficiency.

[0056] Optionally, the mass of the residual lithium in the positive electrode material satisfies Li2CO3≧0.02% and LiOH≧0.2%.

[0057] To produce a coating layer with appropriate coating quality and to make the beneficial effects of the coating layer significant, the mass ratio of the residual lithium in the positive electrode material to the mass of the positive electrode material should satisfy Li2CO3 ≥ 0.02% and LiOH ≥ 0.2%.

[0058] The present application further provides an electrode assembly, which includes the positive electrode plate or includes a positive electrode plate manufactured by the method for manufacturing a positive electrode plate.

[0059] The present application further provides a battery cell including the aforementioned electrode assembly.

[0060] The present application further provides a battery including the aforementioned battery cell.

[0061] The present application further provides a power consuming device including a battery cell as described above or a battery as described above.

[0062] The positive electrode plate of the present application includes a current collector and a coating formed on at least one side of the current collector, with a protective film formed on the surface of the coating, the protective film being made of a material containing fluoride. Considering that performance degradation occurs when the positive electrode material in the coating comes into contact with air, and that interfacial side reactions occur when the positive electrode material comes into contact with the electrolyte, a protective film is formed on the surface of the coating to improve the performance of the positive electrode material. This reduces the chance of contact between the positive electrode material and air and the probability of interfacial reactions occurring between the positive electrode material and the electrolyte, improving the stability of the positive electrode material and thereby improving battery performance. [Brief explanation of the drawings]

[0063] In order to more clearly explain the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings that need to be used in the embodiments or the prior art description. It is obvious that the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the structures shown in these drawings without any creative efforts. [Figure 1] FIG. 2 is a structural schematic diagram of a positive electrode plate according to an embodiment of the present application. [Figure 2] FIG. 2 is a structural schematic diagram of a positive electrode plate according to an embodiment of the present application. [Figure 3] FIG. 2 is a structural schematic diagram of a positive electrode plate according to an embodiment of the present application. [Figure 4] 1 is a flowchart of a method for manufacturing a positive electrode plate according to an embodiment of the present application. [Figure 5] 1 is a schematic diagram of a battery cell according to one embodiment of the present application; [Figure 6] FIG. 6 is an exploded view of the battery cell shown in FIG. 5 according to the embodiment of the present application. [Figure 7] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 8] 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 9] FIG. 9 is an exploded view of the battery pack shown in FIG. 8 according to an embodiment of the present application. [Figure 10] 1 is a schematic diagram of a power consumption device powered by a secondary battery according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0064] The following clearly and completely describes the technical solutions in the embodiments of the present application, in conjunction with the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without any creative efforts fall within the scope of protection of the present application.

[0065] Hereinafter, with appropriate reference to the drawings, specifically disclosed embodiments of the cathode plate, electrode assembly, battery core, battery cell, battery, and power consumption device of the present application will be described in detail. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of structures that are actually the same may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0066] The "ranges" disclosed in this application are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive, and may be arbitrarily combined; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the following ranges are also contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. Unless otherwise specified, the numerical range "ab" in this application is a shorthand notation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" represents a list of all real numbers between "0-5" already listed in this specification, and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0067] Unless otherwise stated, all embodiments and optional embodiments in the present application can be combined with each other to form a new technical solution.

[0068] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0069] Unless otherwise specified, all steps in this application may be performed in order or randomly, and are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, and for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0070] The presence of impurities on the surface of the positive electrode material reduces the performance of the positive electrode material.

[0071] For example, when producing high-nickel ternary materials, structural stability issues during the synthesis process mean that excess Li / Me (alloying elements) is typically used to synthesize a structurally stable cathode active material in the form of a stable oxide. In other words, when producing high-nickel ternary materials, the excess lithium salt in the mixed ternary precursor and lithium salt results in the excess lithium salt not participating in the reaction. This excess lithium salt reacts with moisture and CO2 in the air to form residual lithium (LiOH and Li2CO3). The presence of residual lithium can cause numerous problems during battery core fabrication. For example, the residual lithium formed on the surface of the ternary material has low ionic conductivity, inhibiting the transport of lithium ions in the ternary material. Furthermore, Li2CO3 reacts with the electrolyte, generating gas and heat, thereby affecting battery safety.

[0072] The application of a positive electrode material with residual lithium to the coating may result in a decrease in battery performance, for example, due to the deterioration of performance when the positive electrode material in the coating comes into contact with air, and due to the occurrence of interfacial side reactions when the positive electrode material comes into contact with the electrolyte.

[0073] To solve the above problems, the present application provides a positive electrode plate including a current collector and a coating provided on at least one side of the current collector, wherein a protective film is provided on a surface of the coating, and the material of the protective film includes a fluoride.

[0074] A current collector is a structure or component that collects current. In lithium-ion batteries, it is typically a metal foil such as copper or aluminum foil. The current collector serves as a substrate for attaching the positive or negative electrode active material, collecting the current generated by the active material and providing a large current output to the outside. Generally, aluminum foil is used as the positive electrode current collector, and copper foil is used as the negative electrode current collector.

[0075] The coating includes a positive electrode material, an adhesive, and a conductive agent. In the process of preparing the coating, the positive electrode material, the adhesive, the conductive agent, and a solvent are mixed to prepare a slurry, and the prepared slurry is applied to a current collector to obtain the coating.

[0076] The positive electrode material can provide a lithium source and is used in batteries. During charging, lithium ions are released from the crystal lattice of the positive electrode active material and inserted into the crystal lattice of the negative electrode material after passing through the electrolyte. During discharging, lithium ions are released from the crystal lattice of the negative electrode material and inserted into the crystal lattice of the positive electrode material after passing through the electrolyte.

[0077] An adhesive is a material that has adhesive properties for bonding different substances together.

[0078] In order to ensure that the electrode has good charge and discharge performance, a certain amount of conductive material is generally added when manufacturing the electrode plate. The conductive agent plays the role of collecting minute currents between the active material and between the active material and the current collector, reducing the contact resistance of the electrode and accelerating the electron transfer rate, while effectively improving the lithium ion transfer rate in the electrode material, thereby improving the charge and discharge efficiency of the electrode.

[0079] The protective film has a film layer structure formed on the surface of the coating. As shown in FIG. 1, a positive electrode plate 100 includes a current collector 10, a coating 20 formed on the current collector 10, and a protective film 30 formed on the surface of the coating 20. The surface of the coating 20 refers to the surface of the coating that is exposed to the outside, and may be, for example, the surface of the coating 20 away from the current collector or the surface located on the side of the coating 20. The protective film 30 may be formed on either surface of the coating 20, as needed. For example, a protective film 30 may be formed on each exposed surface of the coating to reduce contact between the coating and the electrolyte.

[0080] Fluorides refer to compounds that contain fluorine with a negative valence.

[0081] Fluoride can effectively reduce the oxidation activity of the surface of the positive electrode material, inhibit the oxidative decomposition of the electrolyte at the positive electrode, and promote the lithium ion transport in the solid phase of the lithium ion. For example, the fluoride can be lithium fluoride or aluminum fluoride, and lithium fluoride is more beneficial for improving its air stability.

[0082] That is, in order to improve the performance of the coating, a protective film is provided on the surface of the coating, and the material of the protective film contains fluoride, which reduces the chance of contact between the positive electrode material in the coating and air, and reduces the probability of an interfacial reaction occurring between the positive electrode material and the electrolyte, improving the stability of the positive electrode material and thereby improving the performance of the battery.

[0083] In addition, lithium fluoride and aluminum fluoride are both ion conductors, and do not inhibit lithium ion transport or affect infiltration.

[0084] In one embodiment, the thickness of the protective film ranges from 1 nm to 50 nm, preferably from 5 nm to 20 nm.

[0085] In order to ensure that the protective film effectively reduces the chance of contact between the electrolyte and the coating and ensures good lithium ion migration speed, the thickness of the protective film ranges from 1 nm to 50 nm, preferably from 5 nm to 20 nm.

[0086] In the above range of 1 nm to 50 nm, the values ​​include the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 1 nm, 3 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, etc.

[0087] In the above range of 5 nm to 20 nm, the values ​​include the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, etc.

[0088] In one embodiment, the fluoride includes at least one of lithium fluoride and aluminum fluoride.

[0089] The fluoride includes at least one of lithium fluoride and aluminum fluoride. That is, the protective film may contain lithium fluoride and aluminum fluoride simultaneously, or may be composed of lithium fluoride or aluminum fluoride independently. Of course, in some cases, other types of materials may be added to the protective film as needed, and the protective film in this application is not limited and may be designed according to usage needs.

[0090] Lithium fluoride is an inorganic substance with the chemical formula LiF, an alkali metal halide, a white crystal at room temperature, and poorly soluble in water.

[0091] Aluminum fluoride is an inorganic substance with the chemical formula AlF3, which is insoluble in water, acid and base, and has very stable properties.

[0092] Lithium fluoride and aluminum fluoride are ion-conducting materials, which are advantageous for the transport of lithium ions. For example, lithium fluoride is an electronic insulator, and its ionic conductivity is about 10 -13 Scm -1 -10 -14 Scm -1 is. The specific type of fluoride in the present application is not limited, and it is sufficient if it is provided on the surface of the coating, reduces the chance of contact between the positive electrode material in the coating and air, and reduces the probability of an interfacial reaction occurring between the positive electrode material and the electrolyte.

[0093] In one embodiment, the protective film comprises a lithium fluoride protective film and an aluminum fluoride protective film, and the lithium fluoride protective film and the aluminum fluoride protective film are laminated on the surface of the coating, and / or the protective film comprises a lithium fluoride protective film and an aluminum fluoride protective film, and the lithium fluoride protective film is provided on at least a portion of the surface of the coating and the aluminum fluoride protective film is provided on at least another portion of the surface of the coating.

[0094] The lithium fluoride protective film and the aluminum fluoride protective film are laminated on the surface of the coating. As shown in FIG. 3, the lithium fluoride protective film 30a and the aluminum fluoride protective film 30b are alternately formed on the surface of the coating 20. For example, the lithium fluoride protective film 30a is formed on the surface of the coating 20, and the aluminum fluoride protective film 30b is formed on one side of the lithium fluoride protective film 30a away from the coating 20. Of course, the aluminum fluoride protective film 30b may be formed on the surface of the coating 20, or the lithium fluoride protective film 30a may be formed on one side of the aluminum fluoride protective film 30b away from the coating 20. The number of layers of the lithium fluoride protective film 30a and the aluminum fluoride protective film 30b is not specifically limited. For example, the lithium fluoride protective film 30a may be two layers and the aluminum fluoride protective film 30b may be one layer. The aluminum fluoride protective film 30b may be provided between the two lithium fluoride protective films 30a as needed.

[0095] A lithium fluoride protective film is provided on at least a portion of the surface of the coating, and an aluminum fluoride protective film is provided on at least another portion of the surface of the coating. As shown in FIG. 2, a lithium fluoride protective film 30a is provided on at least a portion of the surface of the coating 20, and an aluminum fluoride protective film 30b is provided on at least another portion of the surface of the coating 20. For example, the lithium fluoride protective film 30a and the aluminum fluoride protective film 30b may be provided side by side on one surface of the coating 20. However, these embodiments are not particularly limited and can be considered as needed.

[0096] The protective film includes a lithium fluoride protective film and an aluminum fluoride protective film. That is, the protective film simultaneously includes a lithium fluoride protective film and an aluminum fluoride protective film. The thickness ratio of the lithium fluoride protective film to the aluminum fluoride protective film is not limited and can be set as needed. For example, the lithium fluoride and aluminum fluoride film thickness can be 1:1. Both lithium fluoride and aluminum fluoride can effectively reduce the oxidative activity on the surface of the positive electrode material, inhibit the oxidative decomposition of the electrolyte at the positive electrode, and promote lithium ion transport in the solid phase. Lithium fluoride is more beneficial for improving its air stability. If the coating is air-sensitive, the thickness of the lithium fluoride can be increased.

[0097] In one embodiment, the coating includes a cathode material and a coating layer formed on the cathode material, the coating layer including at least one of a sulfur-containing compound, a boron-containing compound, and a fluoride.

[0098] The sulfur-containing compound can react with the residual lithium and can be, for example, K2S2O3 or Na2S2O3.

[0099] The boron-containing compound can react with the residual lithium and can be, for example, B2O3.

[0100] Positive electrode materials, such as ternary positive electrode materials, especially those with a higher nickel content, tend to have higher levels of residual lithium compounds present on their surfaces during synthesis. This residual lithium is highly susceptible to absorbing carbon dioxide and water from the air, forming Li2CO3 and LiOH layers on the particle surfaces, which have the following effects: it consumes the lithium in the material and is electrochemically inactive, causing capacity loss; the LiOH reacts with polyvinylidene fluoride (PVDF), causing the slurry to gel; and finally, the residual LiOH on the electrode plate may further react with the LiPF6 electrolyte, consuming Li ions in the electrolyte and generating HF. The HF further corrodes the positive electrode material itself, dissociating its surface; and the dense Li2CO3 layer on the positive electrode particle surface subsequently inhibits lithium diffusion, affecting the battery's electrical performance.

[0101] To solve the above problem, residual lithium compounds are reduced or removed by chemical reaction, and an ionically conductive coating layer is formed on the surface of the positive electrode material, thereby reducing the polarization of the battery. The coating layer includes at least one of a sulfur-containing compound, a boron-containing compound, and a fluoride.

[0102] Residual lithium compounds in the positive electrode material can be reacted with substances such as sulfur-containing compounds, boron-containing compounds, and ammonium fluoride. For example, sulfur-containing compounds are used to react with residual lithium (LiOH and Li2CO3), reduce the content of residual lithium, and increase the ionic conductivity of the material. Sulfur compounds include K2S x O y or Na2S x O y (x=1 to 8, y=1 to 8), for example, K2S2O3, Na2S2O3, and the reaction formula is nLiOH+nK2S x O y ->nLi2S+nLi2SO x +nH2O(n=integer), nLi2CO3+nK2S x O y ->nK2CO3+nLi2S x O y (n=integer), nLiOH+nNa2Sx O y ->nLi2S+nLi2SO x +nH2O(n=integer), nLi2CO3+nNa2S x O y ->nNa2CO3+nLi2S x O y (n=integer).

[0103] Boron-containing compounds are used to react with residual lithium (LiOH and Li2CO3), reducing the residual lithium content and increasing the ionic conductivity of the material. Boron compounds include H3BO3 or B2O3, and the reaction formulas are nLiOH + nB2O3 → nLi3BO3 + nH2O (n = integer) and nLi2CO3 + nB2O3 → nLi3BO3 + nCO2 (n = integer).

[0104] Ammonium fluoride is used to react with residual lithium (LiOH and Li2CO3), reducing or eliminating the residual lithium and increasing the ionic conductivity of the material: 2NH4F + Li2CO3 → 2LiF↓ + (NH4)2CO3, NHF + LiOH → LiF↓ + NH3↑ + H2O↑.

[0105] Although the ternary material undergoes a modified coating during the material production process, the basic characterization of the residual lithium at the material level shows that a certain amount of residual lithium remains. Considering that this residual lithium is still exposed to air during the subsequent battery manufacturing process, such reactions still exist and continue to affect performance, the present application introduces two protective steps during the manufacturing process of the positive electrode plate, ultimately achieving all-round protection for the positive electrode plate.

[0106] The first step is to form a coating layer on the surface of the positive electrode material, and the second step is to build a protective film on the surface of the positive electrode plate using the process of atomic layer deposition.

[0107] The coating layer depends on the distribution of residual lithium on the surface of the original ternary material. If there is no residual lithium in this area, this protective layer cannot be formed by chemical reaction. Therefore, a double protective process is adopted. The second protective layer can effectively protect the positive electrode material that is not covered by the coating layer, effectively suppressing performance degradation caused by contact with air in subsequent processes of the positive electrode plate surface, and can also reduce the probability of side reactions occurring at the interface between the positive electrode and the electrolyte. The composite protective layer constructed through the two processes can further protect the structural stability of the positive electrode material when it deeply releases lithium.

[0108] The second step is to use the atomic layer deposition process to build a nanoscale protective film on the surface of the positive electrode plate, which not only achieves a dense and uniform film layer, but also prevents the thickness from affecting energy density as with conventional intaglio coating.

[0109] In one embodiment, the coating layer is lithium fluoride.

[0110] The lithium fluoride coating layer is obtained by reacting with ammonium fluoride. By controlling the amount of ammonium fluoride added to the reaction, the residual lithium can be completely removed. Furthermore, the controlled operation step can effectively remove the reaction by-products, thus avoiding the introduction of new impurities.

[0111] In addition, the step of adding ammonium fluoride can be performed during the preparation of the coating slurry, eliminating the need for an additional step, thereby improving the manufacturing efficiency of the positive electrode plate.

[0112] In one embodiment, the mass percentage of lithium fluoride relative to the total mass of the positive electrode material is 0.01% to 5%, preferably 0.5% to 1.2%.

[0113] The total mass of the positive electrode material is the sum of the mass of the positive electrode material and the mass of lithium fluoride. For example, if the mass of lithium fluoride is m1 and the mass of the positive electrode material is m2, the mass percentage of the lithium fluoride in the total mass of the positive electrode material is calculated as m1 / (m1+m2)×100%.

[0114] In the process of reacting the residual lithium with ammonium fluoride to obtain a lithium fluoride coating layer, the amount of ammonium fluoride that needs to be added can be calculated based on the amount of residual lithium in the positive electrode material in order to completely react the residual lithium, and in the obtained positive electrode material, the mass percentage of the mass of lithium fluoride relative to the total mass of the positive electrode material is 0.01% to 5%, preferably 0.5% to 1.2%.

[0115] The above mass percentage values ​​are from 0.01% to 5%, including the minimum and maximum values ​​within this range and each value between such minimum and maximum values, and specific examples include, but are not limited to, the point values ​​in the examples and 0.01%, 0.05%, 0.1%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0116] The above mass percentage values ​​are from 0.5% to 1.2%, including the minimum and maximum values ​​of this range and each value between such minimum and maximum values, and specific examples include, but are not limited to, the point values ​​in the examples and 0.5%, 0.7%, 0.9%, 1%, 1.2%, etc.

[0117] In one embodiment, the general formula of the cathode material in the coating is Li x Ni y M 1-y O2, where 0.9≦x≦1.15, 0.6≦y≦1, and M is selected from one or more of Co, Mn, and Al; and / or the general formula of the cathode material in the coating is xLi2MnO3·(1−x)LiMO2, where 0.1≦x≦0.9, and M is selected from one or more of Co, Mn, and Al.

[0118] The cathode material in the coating is a layered Li x Ni y M 1-y O2, where 0.9≦x≦1.15 and 0.6≦y≦1, and M is selected from one or more of Co, Mn, and Al; and / or a lithium-rich manganese-based positive electrode material xLi2MnO3·(1-x)LiMO2, where 0.1≦x≦0.9, and M is selected from one or more of Co, Mn, and Al.

[0119] In one embodiment, the present application further provides a method for manufacturing a positive electrode plate, including: preparing a positive electrode plate; preparing a fluoride precursor; and forming a protective film on a surface of the coating of the positive electrode plate by a thin film deposition technique.

[0120] Thin film deposition techniques include chemical vapor deposition and physical vapor deposition.

[0121] Chemical vapor deposition is a chemical technology that utilizes one or more vapor-phase compounds or elements, primarily containing the film elements, to produce thin films by chemical reactions on a substrate surface, including, for example, atomic layer deposition processes.

[0122] Physical vapor deposition technology refers to a technology that uses physical methods under vacuum conditions to vaporize the surface of a material source (solid or liquid) into gaseous atoms or molecules, or ionize a portion of it, and then deposit a thin film with a specific function on the surface of a substrate through a low-pressure gas (or plasma) process. Examples include vacuum evaporation, sputter plating, arc plasma plating, ion plating, and molecular beam epitaxy.

[0123] To form a protective film on the surface of the coating of the positive electrode plate, the steps include preparing a positive electrode plate, preparing a fluoride precursor, and forming a protective film on the surface of the coating of the positive electrode plate by a thin film deposition technique.

[0124] In one embodiment, the thin film deposition technique includes an atomic layer deposition process.

[0125] Atomic layer deposition is a method (technology) for forming deposited films by introducing alternating pulses of vapor-phase precursors into a reactor, where they chemisorb and react on the deposition substrate. When the precursors reach the surface of the deposition substrate, they chemisorb to the surface and undergo a surface reaction. It is necessary to flush the atomic layer deposition reactor with an inert gas between precursor pulses.

[0126] To obtain a better protective film, the atomic layer deposition process is preferably selected, which has better chemical composition, high stress control, smooth film surface, a wider process window, and a wider selection of precursors.

[0127] For example, in one embodiment, to form a protective film on a positive electrode plate, a positive electrode plate is prepared, and an atomic layer deposition process is used to form a protective film on the surface of the coating, and the atomic layer deposition process is used to build a single layer of nanoscale protective film on the surface of the coating, which not only achieves a dense and uniform film layer, but also prevents the thickness from affecting energy density as in conventional intaglio coating.

[0128] In one embodiment, the fluoride includes lithium fluoride and / or aluminum fluoride.

[0129] Fluoride can effectively reduce the oxidation activity of the surface of the positive electrode material, inhibit the oxidative decomposition of the electrolyte at the positive electrode, and promote lithium ion transport in the solid phase. A fluoride protective film is formed on the surface of the positive electrode plate coating using a thin film deposition technique by preparing a fluoride precursor, and the fluoride precursor includes a lithium fluoride precursor and / or an aluminum fluoride precursor.

[0130] In one embodiment, the step of forming a coating layer on the surface of the coating of the positive electrode plate by an atomic layer deposition process includes placing the positive electrode plate in an atomic layer deposition reaction chamber, drawing a vacuum, setting the deposition temperature to 200°C-250°C, introducing a suitable fluoride precursor into the reaction chamber to form a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness.

[0131] The protective film material includes a fluoride. The type of fluoride is not specifically limited, and a precursor may be selected based on the selected fluoride type. The step of forming a coating layer on the surface of the coating of the positive electrode plate by atomic layer deposition includes placing the positive electrode plate in an atomic layer deposition reaction chamber, drawing a vacuum, setting the deposition temperature to 200°C-250°C, introducing an appropriate fluoride precursor into the reaction chamber to form a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness.

[0132] In the process of manufacturing the protective film, it is necessary to maintain a vacuum environment to prevent active substances in the air from participating in the reaction during the film formation process and affecting the quality of the film layer. Therefore, in order to manufacture the protective film in a vacuum environment, the positive electrode plate must be placed in a reaction chamber and evacuated.

[0133] The above deposition temperature values ​​are in the range of 200°C-250°C, including the minimum and maximum values ​​of this range and each value between such minimum and maximum values, and specific examples include, but are not limited to, the point values ​​in the examples and 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, etc.

[0134] In one embodiment, the steps of introducing a suitable fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove any unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness include introducing an aluminum fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove any unreacted precursor, and introducing a lithium fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove any unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness.

[0135] The fluoride includes at least one of lithium fluoride and aluminum fluoride. To obtain a protective film of lithium fluoride and aluminum fluoride, the steps of introducing a suitable fluoride precursor into a reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness include introducing an aluminum fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and introducing a lithium fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness.

[0136] In one embodiment, the steps of introducing an aluminum fluoride precursor into the reaction chamber to form a protective film on the surface of the coating and releasing the vacuum to remove the unreacted precursor include: evacuating the reaction chamber to reduce the pressure to 10 Pa or less; introducing AlCl gas into the reaction chamber and maintaining the pressure for 10 s-20 s; introducing a sweep gas into the reaction chamber and releasing the vacuum to remove the unreacted AlCl gas; reducing the pressure in the reaction chamber to 10 Pa or less; introducing TiF gas into the reaction chamber and maintaining the pressure for 10 s-20 s; introducing a sweep gas into the reaction chamber and releasing the vacuum to remove the unreacted TiF gas; and repeating the above steps to obtain an aluminum fluoride protective film with a predetermined thickness.

[0137] The aluminum fluoride precursors include AlCl3 and TiF4. The steps for producing the aluminum fluoride protective film include evacuating the reaction chamber to a pressure of less than 10 Pa, introducing AlCl3 gas into the reaction chamber and maintaining this pressure for 10-20 seconds, introducing a sweep gas into the reaction chamber, releasing the vacuum, removing any unreacted AlCl3 gas, reducing the pressure in the reaction chamber to less than 10 Pa, introducing TiF4 gas into the reaction chamber and maintaining this pressure for 10-20 seconds, introducing a sweep gas into the reaction chamber, releasing the vacuum, removing any unreacted TiF4 gas, and repeating the above steps to obtain an aluminum fluoride protective film of a predetermined thickness.

[0138] AlCl3 and TiF4 are in a solid state at room temperature, and in order to obtain a gaseous precursor, a temperature is set at which the precursor can be vaporized, and the solid is vaporized to obtain a gaseous precursor.

[0139] The step of introducing AlCl3 gas into the reaction chamber and maintaining it for 10s-20s is to introduce an appropriate amount of AlCl3 gas into the reaction chamber. The gas introduction time can be selected according to actual needs, and the present application does not specifically limit it.

[0140] The sweep gas is introduced into the reaction chamber in order to remove other unreacted gases and impurities. The sweep gas is an inert gas, and may be, for example, argon gas.

[0141] In one embodiment, the steps of introducing a lithium fluoride precursor into the reaction chamber to form a protective film on the surface of the coating and releasing the vacuum to remove the unreacted precursor include: evacuating the reaction chamber to reduce the pressure to 10 Pa or less; introducing alkyllithium vapor into the reaction chamber and maintaining the pressure for 10 s-20 s; introducing a sweep gas into the reaction chamber and releasing the vacuum to remove the unreacted alkyllithium vapor; reducing the pressure in the reaction chamber to 10 Pa or less; introducing TiF vapor into the reaction chamber and maintaining the pressure for 10 s-20 s; introducing a sweep gas into the reaction chamber and releasing the vacuum to remove the unreacted TiF vapor; and repeating the above steps to obtain a lithium fluoride protective film with a predetermined thickness.

[0142] The lithium fluoride precursor includes alkyllithium and TiF4. The steps for producing the lithium fluoride protective film include evacuating the reaction chamber to a vacuum of 10 Pa or less, introducing alkyllithium vapor into the reaction chamber and maintaining the pressure for 10-20 seconds, introducing a sweep gas into the reaction chamber, releasing the vacuum, removing the unreacted alkyllithium vapor, reducing the pressure in the reaction chamber to 10 Pa or less, introducing TiF4 vapor into the reaction chamber and maintaining the pressure for 10-20 seconds, introducing a sweep gas into the reaction chamber, releasing the vacuum, removing the unreacted TiF4 vapor, and repeating the above steps to obtain a lithium fluoride protective film with a predetermined thickness.

[0143] The alkyllithium may be lithium tert-butoxide, butyllithium, phenyllithium, etc. For example, lithium tert-butoxide and TiF4 are in a solid state at room temperature, and in order to obtain a gaseous precursor, a temperature is set at which the precursor can be vaporized, and the solid is vaporized to obtain the gaseous precursor.

[0144] In one embodiment, the step of preparing a positive electrode plate includes: mixing a positive electrode material and a reactive substance to react with each other and form a coating layer on the surface of the positive electrode material; mixing the positive electrode material with the coating layer, an adhesive, and a conductive agent, adding a solvent and stirring to obtain a positive electrode slurry; and applying the positive electrode slurry to a current collector and drying to obtain a positive electrode plate, wherein the reactive substance includes at least one of a sulfur compound and a boron compound.

[0145] For example, a sulfur compound and a boron compound are mixed with a positive electrode material and reacted under certain conditions to form a coating layer on the surface of the positive electrode material, the positive electrode material with the coating layer, an adhesive, and a conductive agent are mixed, a solvent is added and the mixture is stirred to obtain a positive electrode slurry, and the positive electrode slurry is applied to a current collector and dried to obtain a positive electrode plate.

[0146] In one embodiment, the step of preparing the positive electrode plate includes mixing a positive electrode material, an adhesive, a conductive agent, and ammonium fluoride, adding a solvent and stirring to obtain a positive electrode slurry, and applying the positive electrode slurry to a current collector and drying to obtain a positive electrode plate.

[0147] Ammonium fluoride is introduced during the slurry production process and reacts with the remaining lithium on the surface of the positive electrode material to form a lithium fluoride coating layer, which can reduce the amount of alkali remaining on the surface of the positive electrode material as needed and reduce battery polarization. Compared to using a sulfur compound or boron compound to mix with the positive electrode material and react under certain conditions to form a coating layer on the surface of the positive electrode material, this method does not require the addition of an extra step using ammonium fluoride, and instead directly adds ammonium fluoride during the slurry production process, reducing process steps and improving the production efficiency of positive electrode plates.

[0148] By converting the residual lithium into an effective lithium fluoride protective layer as a reactant, the slurry gel state can be effectively improved, the residual lithium can be removed, a fast ion conductor coating layer can be established, the conductive ability of the positive electrode plate can be improved, the polarization of the lithium ion battery can be reduced, and the power performance of the lithium ion battery can be improved.

[0149] In one embodiment, the amount of ammonium fluoride added ranges from 0.009% to 4.5% by mass of the positive electrode material, and preferably ranges from 0.45% to 1.1%.

[0150] For example, if the mass of ammonium fluoride added is M1 and the mass of the positive electrode material is M2, the calculation formula for the amount of ammonium fluoride added relative to the mass of the positive electrode material is M1 / M2×100%.

[0151] The amount of residual lithium in the positive electrode material can be measured by hydrochloric acid titration, and the mass of ammonium fluoride added can be calculated based on the measured amount of residual lithium. The range of the amount of ammonium fluoride added relative to the mass of the positive electrode material is 0.009% to 4.5%, preferably 0.45% to 1.1%.

[0152] The range of values ​​for the amount of ammonium fluoride added relative to the mass of the positive electrode material is 0.009% to 4.5%, including the minimum and maximum values ​​within this range and all values ​​between these minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 0.009%, 0.01%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4.5%, etc.

[0153] The range of values ​​of the amount of ammonium fluoride added relative to the mass of the positive electrode material is 0.45% to 1.1%, including the minimum and maximum values ​​within this range and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1.0%, 1.1%, etc.

[0154] In one embodiment, the step of mixing the positive electrode material, adhesive, conductive agent, and ammonium fluoride, adding a solvent, and stirring to obtain a positive electrode slurry includes mixing the positive electrode material, adhesive, conductive agent, and ammonium fluoride for 5-60 minutes, adding a solvent, stirring at a rotation speed of 300-2000 r / min, removing bubbles, and venting to obtain a positive electrode slurry with a solid content of 60%-85%.

[0155] To ensure that the ammonium fluoride and positive electrode material are thoroughly mixed and reacted effectively during the slurry preparation process, the positive electrode material, adhesive, conductive agent, and ammonium fluoride are mixed for 5-60 minutes, a solvent is added, and the mixture is stirred at a rotation speed of 300-2000 r / min for 30-3 hours to remove bubbles and evacuate, resulting in a positive electrode slurry with a solids content of 60-85%.

[0156] Ammonium fluoride reacts with the residual lithium, and the chemical reaction is as follows: 2NH4F+LiCO3→2LiF↓+(NH4)2CO3, NH4F+LiOH→LiF↓+NH3↑+H2O↑

[0157] The by-products of the reaction are all substances that are easily volatile or that volatilize upon decomposition, and in order to facilitate removal of the by-products, bubbles are removed and air is bled during the operation.

[0158] In other words, a corresponding amount of ammonium fluoride is calculated and used as a source of residual lithium, and the ammonium fluoride and the positive electrode material are thoroughly brought into contact with each other under stirring conditions of the slurry to mix uniformly and react with each other. After stirring is completed, a portion of the gas product is removed by bleed-off during the bubble removal step.

[0159] In one embodiment, the step of applying the positive electrode slurry to a current collector and drying to obtain a positive electrode plate includes applying the positive electrode slurry to a current collector and drying at a temperature of 100°C-170°C to obtain a positive electrode plate.

[0160] In order to ensure the decomposition and removal of the reaction by-product (NH4)2CO3 effectively, the ammonium carbonate is decomposed and removed by adjusting the drying temperature during the drying process. The drying temperature is 100-170°C. Under these drying conditions, the product (NH4)2CO3 is decomposed and discharged along the gas path, which is favorable for the rapid decomposition and removal of (NH4)2CO3 and improves production efficiency.

[0161] In one embodiment, the mass of the residual lithium in the positive electrode material satisfies Li2CO3≧0.02% and LiOH≧0.2%.

[0162] To produce a coating layer with appropriate coating quality and to make the beneficial effects of the coating layer significant, the mass ratio of the residual lithium in the positive electrode material to the mass of the positive electrode material should satisfy Li2CO3 ≥ 0.02% and LiOH ≥ 0.2%.

[0163] The surface of the positive electrode material and the surface and depth of the positive electrode plate achieve an all-round protective film, and the technical effects of this protective film are as follows: This application converts residual lithium into an effective coating layer as a reactant, effectively improving the slurry gel state, removing residual lithium, and establishing a fast-ion conductor coating layer, thereby improving the conductive ability of the positive electrode plate, reducing polarization of the lithium-ion battery, and improving the power performance of the lithium-ion battery. Furthermore, a protective film of lithium fluoride and / or aluminum is added based on the coating layer to protect the positive electrode from interfacial side reactions with the electrolyte. The composite protective layer constructed through the two processes can further protect the structural and surface stability of the positive electrode material when it deeply releases lithium, which is beneficial to improving the service life of the battery.

[0164] In one embodiment, the present application further provides an electrode assembly, the electrode assembly including a positive electrode plate as described above, or including a positive electrode plate manufactured by the method for manufacturing a positive electrode plate as described above.

[0165] Since the positive electrode plate adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects of the technical solutions of the above embodiments, and no further description will be given here.

[0166] In one embodiment, there is further provided a battery cell including an electrode assembly as described above.

[0167] Since the electrode assembly adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects of the technical solutions of the above embodiments, and will not be further described here.

[0168] In one embodiment, there is further provided a battery comprising a battery cell as described above.

[0169] Since the battery cell adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects of the technical solutions of the above embodiments, and no further description will be given here.

[0170] An embodiment of the present application further provides a power consuming device including the battery cell or battery described above.

[0171] Since the battery cell or battery adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects of the technical solutions of the above embodiments, and no further description will be given here.

[0172] The batteries (battery cells, battery modules, battery packs) and power consuming devices of the present application will be described below with appropriate reference to the drawings.

[0173] In one embodiment of the present application, a secondary battery is provided.

[0174] A typical secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charge and discharge process of the battery, active ions are absorbed and desorbed by moving back and forth between the positive electrode plate and the negative electrode plate. The electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate. The separator, located between the positive electrode plate and the negative electrode plate, primarily serves to prevent short-circuiting between the positive and negative electrodes and allows ions to pass through. The separator is the improved separator described above in this application.

[0175] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.

[0176] For example, the positive electrode current collector has two surfaces that face each other in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two facing surfaces of the positive electrode current collector.

[0177] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0178] In some embodiments, when the secondary battery is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art and used in lithium-ion batteries. For example, the positive electrode active material may include at least one of a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and a modified compound thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO), lithium nickel oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (may be abbreviated as "LiNi") 0.5 Co 0.2 Mn 0.3O2(NCM 523 (may be abbreviated as "LiNi") 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as "LiNi") 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (may be abbreviated as "LiNi") 0.8 Co 0.1 Mn 0.1 O2(NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 Examples of the lithium-containing phosphate having an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0179] Batteries undergo Li desorption and depletion during charge and discharge, and the molar content of Li varies when the battery is discharged to different states. In the listing of positive electrode materials in the embodiments of the present disclosure, the molar content of Li is the initial state of the material, i.e., the state before insertion. When the positive electrode material is applied to a battery system and undergoes charge and discharge cycles, the molar content of Li may change.

[0180] In the listing of positive electrode materials in the examples of the present disclosure, the molar content of O is only a theoretical value; crystal lattice oxygen release causes a change in the molar content of O, and in practice, the molar content of O fluctuates.

[0181] In some embodiments, the positive electrode membrane layer optionally further includes an adhesive. For example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0182] In some embodiments, the positive electrode film layer optionally further includes a conductive agent, for example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0183] In some embodiments, the positive electrode plate may be manufactured in the following manner: Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then applied onto a positive electrode current collector, and the positive electrode plate is obtained after processes such as drying and cold pressing.

[0184] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0185] As an example, the negative electrode current collector has two surfaces facing each other in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two facing surfaces of the negative electrode current collector.

[0186] In some embodiments, the negative electrode current collector may employ a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0187] In some embodiments, the negative electrode active material may be any negative electrode active material known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of silicon elemental, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of tin elemental, stannate compounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials in batteries may also be used. These negative electrode active materials may be used alone or in combination.

[0188] In some embodiments, the negative electrode membrane layer optionally further comprises an adhesive, which 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).

[0189] In some embodiments, the negative electrode film layer optionally further comprises a conductive agent, which may be at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0190] In some embodiments, the negative electrode membrane layer further optionally includes other auxiliary agents, such as a thickener (e.g., carboxymethylcellulose sodium (CMC-Na)).

[0191] In some embodiments, the negative electrode plate may be manufactured in the following manner: The components for manufacturing the negative electrode plate, such as the negative electrode active material, conductive agent, adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then applied onto a negative electrode current collector, and the negative electrode plate is obtained after processes such as drying and cold pressing.

[0192] The electrolyte serves to conduct ions between the positive and negative electrodes, and the present application does not specifically limit the type of electrolyte, which may be selected as needed.

[0193] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0194] In some embodiments, the electrolyte salt may be chosen from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethylsulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0195] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0196] In some embodiments, the electrolyte solution may further optionally contain additives. For example, the additives may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some battery performance, such as an additive that improves battery overcharge performance, or an additive that improves battery high-temperature or low-temperature performance.

[0197] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous separator with good chemical stability and mechanical stability may be selected.

[0198] In some embodiments, the separator may be made of at least one material selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may 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 each layer may be the same or different, and are not particularly limited.

[0199] In some embodiments, the positive and negative electrodes and the separator can be fabricated into an electrode assembly by a winding or lamination process.

[0200] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0201] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0202] The present application does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. For example, Fig. 5 shows a battery cell 5 having a rectangular structure as an example.

[0203] In some embodiments, referring to FIG. 6 , the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can be installed to cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the battery cell 5 may be one or more, and can be selected by those skilled in the art according to specific actual needs.

[0204] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0205] FIG. 7 shows an example of a battery module 4. Referring to FIG. 7, in the battery module 4, a plurality of battery cells 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of battery cells 5 may be fixed by fasteners.

[0206] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of battery cells 5 are accommodated in this accommodating space.

[0207] In some embodiments, the battery modules may be assembled into a battery pack, and the battery pack may include one or more battery modules, the specific number of which may be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0208] 8 and 9 show an example of a battery pack 1. Referring to FIGS. 8 and 9, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be provided with a lid on the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0209] The present application also provides a power consuming device, the power consuming device including at least one of the secondary battery, battery module, or battery pack according to the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming 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, satellites, energy storage systems, etc.

[0210] The power consumption device can be selected from a secondary battery, a battery module, or a battery pack depending on its usage needs.

[0211] 10 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. A battery pack or a battery module can be employed to meet the demand for high power output and high energy density of the secondary battery of the power consuming device.

[0212] Other examples of the device may include a mobile phone, a tablet computer, a laptop computer, etc. These devices are generally required to be thin and lightweight, and may use a secondary battery as a power source.

[0213] Examples will be described below. Example 1 [Production of positive electrode slurry] Cathode material LiNi 0.8 Co 0.1 Mn 0.1 O2, PVDF adhesive, and carbon black conductive agent were mixed in a 90:5:5 ratio, and the corresponding amount of ammonium fluoride calculated based on the residual lithium content was added (the percentage of residual alkali in the positive electrode material was 0.2%, and the mass of the added ammonium fluoride accounted for 0.18% of the mass of the positive electrode material). After dry mixing for 15 minutes, NMP was added and the mixture was stirred at a high speed of 1000 rpm for 120 minutes. After removing bubbles and venting, a uniform positive electrode slurry with a solids content of 70% was obtained.

[0214] [Production of positive electrode plates] The positive electrode slurry was uniformly applied to an aluminum foil positive electrode current collector, and the plate was dried in an oven at 130°C. An aluminum fluoride thin film layer was then deposited on the positive electrode plate using an atomic layer deposition (ALD) reactor. Precursor A was polished TiF4, precursor B was AlCl3, and the deposition temperature was 250°C. The positive electrode plate was placed in an ALD reactor, and the deposition parameters and process were as follows: 1) Vacuum the reaction chamber and wait until the pressure drops to 10 Pa or less. 2) Open the valve of precursor A to let AlCl3 vapor into the reaction chamber and maintain for 15 seconds, the temperature at which vapor is generated is 120°C. 3) Argon gas is introduced into the reaction chamber for 120 seconds, and then the vacuum is opened to remove unreacted precursor A. 4) When the pressure in the reaction chamber is reduced to 10 Pa, open the valve of precursor B to introduce TiF4 vapor into the reaction chamber and maintain this for 15 seconds, and the temperature at which the vapor is generated is 120°C. 5) Argon gas is introduced into the reaction chamber for 100 seconds, and then the vacuum is opened to remove unreacted precursor B. 1)-5) constitute one complete cycle process, and the above cycle is repeated to obtain a protective film with a thickness of approximately 10 nm. The protective film-treated electrode plate is then subjected to processes such as cold pressing and slitting to obtain an assembly-ready positive electrode plate.

[0215] [Manufacturing of battery components and finished products] The negative electrode material, graphite, conductive agent, acetylene black, adhesive, styrene butadiene rubber (SBR), and thickener, sodium carboxymethylcellulose (CMC), were mixed in a 90:5:2:2:1 mass ratio in deionized water solvent system by thorough stirring until homogeneous. The mixture was then coated onto a copper foil negative electrode current collector, dried, and then cold-pressed and slit to obtain a negative electrode plate. A PE porous polymer membrane, which had been treated with aluminum oxide ceramic, was used as the separator. The electrolyte was a 1 mol / L LiPF6 solution. The organic solvent was a mixture of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) in a volume ratio of 5:2:3, with appropriate addition of film-forming additives to create the required electrolyte. The positive electrode plate, separator, and negative electrode plate were assembled in a dry room with a humidity of less than 2%, baked, and dried. The corresponding electrolyte was then injected and packaged. A chemical formation test was conducted to fabricate a pouch battery with a capacity of 2.8 Ah. Electrical performance tests were then conducted.

[0216] <Example 2> [Production of positive electrode slurry] Cathode material LiNi0.8 Co 0.1 Mn 0.1 O2, adhesive PVDF, and conductive carbon black were mixed in a 90:5:5 ratio, and the corresponding amount of ammonium fluoride calculated based on the amount of residual lithium was added. After dry mixing for 15 minutes, NMP was added and the mixture was stirred at a high speed of 1000 rpm for 120 minutes. After removing bubbles and venting, a uniform cathode slurry with a solids content of 70% was obtained.

[0217] [Production of positive electrode plates] The positive electrode slurry was uniformly coated on an aluminum foil positive electrode current collector, and the plate was dried in an oven at 130°C. An atomic layer deposition (ALD) machine was then used to deposit an aluminum fluoride protective film and a lithium fluoride protective film on the positive electrode plate. The aluminum fluoride thin film precursor A was polished TiF4, precursor B was AlCl3, and lithium fluoride thin film precursor A was lithium tert-butoxide, precursor B was TiF4. The deposition temperature was 250°C. The positive electrode plate was placed in an ALD reactor, and the deposition parameters and process for the aluminum fluoride composite thin film were as follows: 1) Vacuum the reaction chamber and wait until the pressure drops to 10 Pa or less. 2) Open the valve of precursor A to let AlCl3 vapor into the reaction chamber and maintain for 15 seconds, the temperature at which vapor is generated is 120°C. 3) Argon gas is introduced into the reaction chamber for 120 seconds, and then the vacuum is opened to remove unreacted precursor A. 4) When the pressure in the reaction chamber is reduced to 10 Pa, open the valve of precursor B, introduce TiF4 into the reaction chamber, and maintain this for 15 seconds. The temperature at which the vapor is generated is 120°C. 5) Argon gas is introduced into the reaction chamber for 120 seconds, and then the vacuum is opened to remove unreacted precursor B. 1)-5) is the complete aluminum fluoride deposition cycle process.

[0218] The deposition parameters and deposition process of the lithium fluoride composite thin film are as follows: 1) Vacuum the reaction chamber and wait until the pressure drops to 10 Pa or less. 2) Open the valve of precursor A, introduce lithium tert-butoxide vapor into the reaction chamber, and maintain for 15 seconds, the temperature at which vapor is generated is 165°C. 3) Argon gas is introduced into the reaction chamber for 120 seconds, and then the vacuum is opened to remove unreacted precursor A. 4) When the pressure in the reaction chamber is reduced to 10 Pa, open the valve of precursor B, introduce TiF4 vapor into the reaction chamber, and maintain this for 15 seconds, and the temperature at which the vapor is generated is 120°C. 5) Argon gas is introduced into the reaction chamber for 120 seconds, and then the vacuum is opened to remove unreacted precursor B. 1)-5) are the complete lithium fluoride deposition cycle process. LiF and AlF3 cycles are alternately deposited in a 1:1 ratio to obtain a protective film with a thickness of approximately 10 nm. The protective film-treated electrode plate is then subjected to processes such as cold pressing and slitting to obtain an assembly-ready positive electrode plate.

[0219] The manufacturing of the battery components and the finished product was the same as in Example 1.

[0220] Example 3 Based on Example 2, the number of deposition cycles was adjusted to obtain a protective film with a thickness of 20 nm.

[0221] Example 4 [Production of positive electrode slurry] Cathode material LiNi 0.8 Co 0.1 Mn 0.1 O2, adhesive PVDF, and conductive carbon black were dry mixed in a ratio of 90:5:5 for 15 minutes, and then NMP was added and stirred at a high speed of 1000 rpm for 120 minutes, after which bubbles were removed to obtain a uniform cathode slurry with a solid content of 70%.

[0222] The positive electrode plate was manufactured in the same manner as in Example 2. The manufacturing of the battery components and the finished product was the same as in Example 1.

[0223] <Examples 5 to 9> Based on Example 1, the number of deposition cycles was adjusted to obtain protective films with different thicknesses.

[0224] <Comparative Example 1> [Production of positive electrode slurry] Cathode material LiNi 0.8 Co 0.1 Mn 0.1 O2, adhesive PVDF, and conductive carbon black were dry mixed in a ratio of 90:5:5 for 15 minutes, and then NMP was added and stirred at a high speed of 1000 rpm for 120 minutes, after which bubbles were removed to obtain a uniform cathode slurry with a solid content of 70%.

[0225] [Production of positive electrode plates] This positive electrode slurry was uniformly applied to an aluminum foil positive electrode current collector and dried.

[0226] The manufacturing of the battery components and the finished product was the same as in Example 1.

[0227] <Comparative Example 2> [Production of positive electrode slurry] The method for producing the positive electrode slurry is the same as that in Example 1.

[0228] [Production of positive electrode plates] This positive electrode slurry was uniformly applied to an aluminum foil positive electrode current collector and dried.

[0229] The manufacturing of the battery components and the finished product was the same as in Example 1. The manufactured batteries are tested using the following method. 1. Slurry static test The produced positive electrode slurry was left to stand for 24 hours in an environment of a temperature of 25°C and a humidity of 40%, and the surface state of the positive electrode slurry was observed.

[0230] 2. Gas generation test A fully charged lithium ion battery was placed in a thermostatic box at 70°C, and after 30 days, its volume was measured by the discharge method and converted into mL / Ah.

[0231] 3. Cycle test A charge-discharge test was carried out for 300 cycles at a voltage range of 1C / 1C 2.8-4.25V at a temperature of 45°C, and the capacity retention rate was recorded.

[0232] [Table 1]

[0233] As can be seen from the above table, the present application adds an additive that removes residual lithium when stirring the positive electrode material, thereby effectively improving the slurry gel state, and the protective film effectively improves the specific capacity of the battery, reduces the high-temperature gas generation level, and improves the high-temperature cycle life of the battery. This is because the composite protective film not only purifies the residual lithium, but also the product and the composite protective film both have ion transport properties, thereby improving the ion transport performance of the surface of the positive electrode material. At the same time, the protective film effectively protects the surface of the positive electrode material under high-temperature degradation conditions, inhibits the oxidation and side reaction processes of the active material with the electrolyte, maintains the structural stability and surface stability of the positive electrode material, and significantly improves the cycle life and gas generation level of the battery.

[0234] The above is merely a preferred embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structural transformations made using the contents of the specification and drawings of the present application in accordance with the application concept of the present application, or direct or indirect applications in other related technical fields, are all included in the patent protection scope of the present application. [Explanation of symbols]

[0235] 1 battery pack 2 Upper housing 3 Lower housing 4 Battery Module 5 battery cells 10 Current collector 20 Coating 30 Protective film 30a Lithium fluoride protective film 30b Aluminum fluoride protective film 51 cases 52 Electrode Assembly 53 Cover plate 100 Positive electrode plate

[0236] The realization of the objects, functional features and advantages of the present application will be further explained with reference to the drawings in conjunction with the embodiments.

Claims

1. A positive electrode plate, wherein the positive electrode plate includes a current collector and a coating provided on at least one side of the current collector, and a protective film is provided on a surface of the coating, and the material of the protective film includes a fluoride.

2. 2. The positive electrode plate according to claim 1, wherein the thickness of the protective film ranges from 1 nm to 50 nm, preferably from 5 nm to 20 nm.

3. The positive electrode plate according to claim 1 or 2, wherein the fluoride includes at least one of lithium fluoride and aluminum fluoride.

4. the protective film includes a lithium fluoride protective film and an aluminum fluoride protective film, the lithium fluoride protective film and the aluminum fluoride protective film being laminated on a surface of the coating; and / or the protective film includes a lithium fluoride protective film and an aluminum fluoride protective film, the lithium fluoride protective film being provided on at least a portion of a surface of the coating, and the aluminum fluoride protective film being provided on at least another portion of a surface of the coating.

5. 5. The positive electrode plate according to claim 1, wherein the coating includes a positive electrode material, a coating layer is formed on a surface of the positive electrode material, and the coating layer includes at least one of a sulfur-containing compound, a boron-containing compound, and a fluoride.

6. The positive electrode plate according to claim 5 , wherein the coating layer is lithium fluoride.

7. 7. The positive electrode plate according to claim 6, wherein the mass percentage of the lithium fluoride relative to the total mass of the positive electrode material is 0.01% to 5%, preferably 0.5% to 1.2%.

8. The general formula of the positive electrode material in the coating is Li ｘ Ni ｙ M １－ｙ O ２ wherein 0.9≦x≦1.15, 0.6≦y≦1, and M is selected from one or more of Co, Mn, and Al; and / or the positive electrode material in the coating has the general formula xLi ２ MnO ３ ・(1-x)LiMO ２ 8. The positive electrode plate of claim 1, wherein 0.1≦x≦0.9, and M is selected from one or more of Co, Mn, and Al.

9. providing a positive electrode plate; providing a fluoride precursor; and forming a protective film on the surface of the coating of the positive electrode plate by a thin film deposition technique.

10. The method for manufacturing a positive electrode plate according to claim 9 , wherein the thin film deposition technique comprises an atomic layer deposition process.

11. The method for producing a positive electrode plate according to claim 9 or 10, wherein the fluoride includes lithium fluoride and / or aluminum fluoride.

12. The step of forming a coating layer on the surface of the coating of the positive electrode plate by an atomic layer deposition process includes: The positive electrode plate is placed in an atomic layer deposition reaction chamber, evacuated, and the deposition temperature is set to 200°C-250°C; 12. The method for manufacturing a positive electrode plate according to claim 10 or 11, comprising: introducing a suitable fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness.

13. introducing a suitable fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, opening the vacuum to remove unreacted precursor, and repeating the above steps to obtain a protective film of a predetermined thickness; introducing an aluminum fluoride precursor into the reaction chamber to form a protective film on the surface of the coating, and opening a vacuum to remove unreacted precursor; introducing a lithium fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, and opening a vacuum to remove unreacted precursor; 13. The method for manufacturing a positive electrode plate according to claim 12, further comprising: repeating the steps to obtain a protective film of a predetermined thickness.

14. The steps of introducing an aluminum fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, and opening a vacuum to remove unreacted precursor include: evacuating the reaction chamber to reduce the pressure to 10 Pa or less; In the reaction chamber, AlCl ３ Turn on the gas and maintain it for 10s-20s. A sweep gas is introduced into the reaction chamber, the vacuum is broken, and unreacted AlCl ３ Removing the gas; The pressure in the reaction chamber is reduced to 10 Pa or less, and TiF ４ Turn on the gas and maintain it for 10s-20s. A sweep gas is introduced into the reaction chamber, and the vacuum is released to remove unreacted TiF ４ Removing the gas; 14. The method for manufacturing a positive electrode plate according to claim 13, further comprising: repeating the steps to obtain a predetermined thickness of the aluminum fluoride protective film.

15. The steps of introducing a lithium fluoride precursor into the reaction chamber, forming a protective film on the surface of the coating, and opening a vacuum to remove unreacted precursor include: evacuating the reaction chamber to reduce the pressure to 10 Pa or less; Introduce alkyllithium vapor into the reaction chamber and maintain for 10 s to 20 s; introducing a sweep gas into the reaction chamber and breaking the vacuum to remove unreacted alkyllithium vapor; The pressure in the reaction chamber is reduced to 10 Pa or less, and TiF ４ Injecting steam and maintaining for 10s-20s; A sweep gas is introduced into the reaction chamber, and the vacuum is released to remove unreacted TiF ４ removing the vapor; 15. The method for manufacturing a positive electrode plate according to claim 13 or 14, further comprising repeating the steps to obtain a lithium fluoride protective film of a predetermined thickness.

16. The step of preparing a positive electrode plate includes: mixing a positive electrode material with a reactive substance to cause a reaction and form a coating layer on the surface of the positive electrode material; mixing the positive electrode material having the coating layer, the adhesive, and the conductive agent, adding a solvent and stirring the mixture to obtain a positive electrode slurry; and applying the positive electrode slurry to a current collector and drying the applied positive electrode slurry to obtain a positive electrode plate. The method for producing a positive electrode plate according to claim 9 , wherein the reactive substance includes at least one of a sulfur compound and a boron compound.

17. The step of preparing a positive electrode plate includes: mixing a positive electrode material, an adhesive, a conductive agent, and ammonium fluoride, adding a solvent and stirring the mixture to obtain a positive electrode slurry; The method for producing a positive electrode plate according to claim 9 , comprising: applying the positive electrode slurry to a current collector and drying the applied positive electrode slurry to obtain a positive electrode plate.

18. 18. The method for manufacturing a positive electrode plate according to claim 17, wherein the amount of ammonium fluoride added ranges from 0.009% to 4.5%, preferably from 0.45% to 1.1%, of the mass of the positive electrode material.

19. The step of mixing a positive electrode material, an adhesive, a conductive agent, and ammonium fluoride, adding a solvent, and stirring the mixture to obtain a positive electrode slurry includes:

19. The method for producing a positive electrode plate according to claim 17, comprising mixing a positive electrode material, an adhesive, a conductive agent, and ammonium fluoride for 5 to 60 minutes, adding a solvent, stirring at a rotation speed of 300 r / min to 2000 r / min for 30 minutes to 3 hours, removing bubbles, and venting to obtain a positive electrode slurry having a solids content of 60% to 85%.

20. The step of applying the positive electrode slurry to a current collector and drying it to obtain a positive electrode plate includes: The method for producing a positive electrode plate according to any one of claims 17 to 19, comprising applying the positive electrode slurry to a current collector and drying the slurry at a temperature of 100°C to 170°C to obtain a positive electrode plate.

21. The occupancy rate of the mass of the residual lithium in the positive electrode material to the mass of the positive electrode material is Li ２ CO ３ 21. The method for producing a positive electrode plate according to claim 16, wherein the method satisfies the following conditions: 0.02%, LiOH 0.2%.

22. 22. An electrode assembly, the electrode assembly comprising the positive electrode plate according to any one of claims 1 to 8, or a positive electrode plate manufactured by the method for manufacturing a positive electrode plate according to any one of claims 9 to 21.

23. A battery cell comprising the electrode assembly of claim 22.

24. A battery comprising the battery cell of claim 23.

25. 25. A power consuming device comprising a battery cell according to claim 23 or a battery according to claim 24.

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