Positive pole piece and preparation method thereof, battery and electric equipment

Abstract

The invention relates to the technical field of batteries, in particular to a positive pole piece and a preparation method thereof, a battery and electric equipment, the positive pole piece comprises a lithium supplement agent and an organic solvent, at least a part of the organic solvent is attached to the lithium supplement agent, the lithium supplement agent comprises one or more of Li3N, Li3P and Li2O2, the organic solvent comprises an organic solvent with weak proton hydrogen removed, and the lithium supplement agent comprises one or more of Li3N, Li3P and Li2O2. The weak proton hydrogen removal organic solvent comprises one or more of triethyl phosphate, sulfolane and propylene carbonate. In the embodiment of the invention, the amount of proton hydrogen removed from the organic solvent is small, side reactions of the lithium supplement agent are reduced, and the lithium supplement effect of the lithium supplement agent can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a positive electrode plate and a preparation method thereof, a battery, and an electrical device. Background Art

[0002] The information provided in this section is only background information related to the present application, and it is not necessarily prior art.

[0003] As a new generation of green energy storage and conversion devices, lithium-ion batteries have been widely used in fields such as portable electronic devices and electric vehicles. During the first charge and discharge process of a lithium-ion battery, some lithium ions will react with the components of the electrolyte to form a SEI film on the surface of the negative electrode material, resulting in a loss of some lithium ions and a decrease in the energy density of the battery. To compensate for this loss, a lithium supplement agent is usually added, but the lithium supplement effect is relatively low. Summary of the Invention

[0004] The main technical problem to be solved by the present application is the problem that the lithium supplement effect needs to be improved. To solve the above technical problem, the present application provides a positive electrode plate and a preparation method thereof, a battery, and an electrical device, which can improve the lithium supplement effect of the lithium supplement agent.

[0005] The technical solution provided in the first aspect of the present application: A positive electrode plate, the positive electrode plate includes a lithium supplement agent and an organic solvent, at least part of the organic solvent adheres to the lithium supplement agent, and the lithium supplement agent includes Li 3 N, Li 3 P, Li 2 O 2 and Li 2 S, and the organic solvent includes an organic solvent capable of removing weakly acidic hydrogen, and the organic solvent capable of removing weakly acidic hydrogen includes one or more of triethyl phosphate, sulfolane, and propylene carbonate.

[0006] In the technical solution of the embodiment of the present application, a positive electrode plate is provided, the positive electrode plate includes a lithium supplement agent, and the lithium supplement agent includes Li 3 N, Li 3 P, Li 2 O 2 and Li 2 S, and the lithium supplement agent can be decomposed to form lithium ions, and the lithium supplement effect is achieved by adding the lithium supplement agent. Among them, Li 3 N releases nitrogen as the lithium supplement agent, and Li 2 O 2 releases oxygen or generates lithium peroxide as the lithium supplement agent, and the air bag can be removed after the battery formation process to achieve no residue of by-products on the positive electrode; Li 3 P and Li 2 S form Li x P and Li yIntermediate phase residue of S; meanwhile, by using an organic solvent with weak proton hydrogen extraction to disperse the lithium supplement agent, when forming the positive electrode sheet, at least part of the organic solvent adheres to the surface of the lithium supplement agent. The amount of proton hydrogen extracted by the organic solvent is very weak and can be ignored, reducing the probability of the deprotonation-self-condensation reaction between the lithium supplement agent and the organic solvent, reducing the occurrence of side reactions of the lithium supplement agent, and improving the lithium supplement effect of the lithium supplement agent.

[0007] In the embodiment of the present application, by adding a lithium supplement agent to the positive electrode sheet, after the positive electrode sheet is assembled into a battery, during the battery charging process, an external voltage is applied, causing the lithium supplement agent in the positive electrode sheet to release electrons, and the lithium supplement agent decomposes into lithium ions, so that the lithium supplement agent can decompose into lithium ions to achieve the lithium supplement effect.

[0008] In the embodiment of the present application, the proton hydrogen extraction effect in the molecular structures of triethyl phosphate, sulfolane, and propylene carbonate is weak, and the amount of proton hydrogen extracted can be ignored. It can be considered that almost no proton hydrogen is extracted, and no self-condensation reaction will occur with the lithium supplement agent, reducing the occurrence of side reactions of the lithium supplement agent. At the same time, in the embodiment of the present application, triethyl phosphate and propylene carbonate are non-toxic or have low toxicity, reducing the environmental impact during the production process of the positive electrode sheet. In the embodiment of the present application, after the positive electrode sheet is manufactured, there is still some organic solvent with weak proton hydrogen extraction remaining in the positive electrode sheet. The remaining organic solvent can adhere to the surface of the lithium supplement agent or be located between adjacent lithium supplement agents.

[0009] In any embodiment, the particle size D50 of the lithium supplement agent is 1 μm - 10 μm. In the embodiment of the present application, when the particle size D50 of the lithium supplement agent is within the above range, on the one hand, the dispersibility of the lithium supplement agent is better, and the lithium supplement agent can be better dispersed in the organic solvent, making the surface of the film layer formed by coating the slurry containing the lithium supplement agent relatively flat during the production process of the positive electrode sheet; on the other hand, the lithium supplement agent with a particle size D50 of 1 μm - 10 μm has an extremely small particle size and a large specific surface area, which can accelerate the solvation process of the lithium supplement agent, better improve the dispersibility of the lithium supplement agent, and reduce or avoid the occurrence of agglomeration of the lithium supplement agent; on the third hand, when the particle size D50 of the lithium supplement agent is 1 μm - 10 μm, the decomposition rate of the lithium supplement agent is relatively high, which is beneficial to improving the lithium supplement efficiency.

[0010] Among them, the particle size D50 represents the particle size corresponding to when the cumulative particle size distribution percentage of the tested powder reaches 50%.

[0011] In any embodiment, the D50 particle size of the lithium supplement agent is 3 μm - 8 μm. In the embodiments of the present application, the D50 particle size of the lithium supplement agent is within the above range, so that the dispersibility of the lithium supplement agent is better, and the lithium supplement agent can be better dispersed in the organic solvent. In any embodiment, the positive electrode plate includes a positive electrode plate layer and a current collector. The positive electrode plate layer is disposed on one or both sides of the current collector. The positive electrode plate layer includes a first positive electrode active material layer, and the lithium supplement agent and the organic solvent are dispersed in the first positive electrode active material layer. In the embodiments of the present application, the positive electrode plate layer includes a first positive electrode active material layer, and the lithium supplement agent is dispersed in the first positive electrode active material layer, so that in the embodiments of the present application, the manufacturing process of the positive electrode plate is relatively simple, and at the same time, the lithium supplement agent can achieve the effect of supplementing lithium.

[0012] In any embodiment, the positive electrode plate includes a positive electrode plate layer and a current collector. The positive electrode plate layer is disposed on one or both sides of the current collector; the positive electrode plate layer includes a second positive electrode active material layer and a lithium supplement film layer. The lithium supplement film layer is disposed on the side of the second positive electrode active material layer facing away from the current collector. The lithium supplement film layer includes a lithium supplement agent and an organic solvent. In the embodiments of the present application, the positive electrode plate layer includes a second positive electrode active material layer and a lithium supplement film layer. In the embodiments of the present application, by disposing the lithium supplement agent as a film layer on the surface of the second positive electrode active material layer, after the positive electrode plate is assembled into a battery, after the lithium supplement agent plays a role in supplementing lithium, the lithium supplement agent reacts and does not form vacancies in the second positive electrode active material layer. Therefore, it does not affect the charge transfer path of the battery cell and does not increase the impedance of the positive electrode plate, so it does not affect the long-term cycle stability of the battery cell.

[0013] In any embodiment, both the first positive electrode active material layer and the second positive electrode active material layer include a positive electrode active material. The positive electrode active material includes one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide. In the embodiments of the present application, the lithium supplement agent is combined with the organic solvent from which weak proton hydrogen is removed as an additive, and can be applied to the positive electrode plate of the above positive electrode active material, which is beneficial to lithium supplementation.

[0014] In any embodiment, the mass ratio of the lithium supplement agent to the positive electrode active material is (1 - 3):100. By controlling the mass ratio of the lithium supplement agent to the positive electrode active material within the above range, the lithium supplement agent can achieve a better lithium supplementation effect, so that when the positive electrode plate is used in a battery, the amount of the lithium supplement agent can meet the lithium supplementation requirement while avoiding the formation of lithium dendrites on the negative electrode due to excessive lithium supplementation.

[0015] In any embodiment, based on the mass of the positive electrode plate layer, the mass percentage of the organic solvent is 1×10 3 ppm - 9.9×10 3 ppm. In the embodiments of the present application, the organic solvent accounts for 1×10 3 ppm - 9.9×103 ppm. Using an organic solvent that can release weakly acidic protons can also reduce the side reactions of the lithium supplement during the production of the electrode sheet.

[0016] In the embodiments of the present application, the organic solvent that can release weakly acidic protons has a dehydrogenation energy barrier greater than 375 kcal / mol. Among them, the dehydrogenation energy barrier can be obtained through theoretical calculations.

[0017] The second aspect of the present application also provides a method for preparing a positive electrode sheet, including:

[0018] Disperse the lithium supplement in an organic solvent to form a lithium supplement dispersion liquid, where the lithium supplement includes one or more of Li 3 N, Li 3 P, Li 2 O 2 and Li 2 S, and the organic solvent includes an organic solvent that can release weakly acidic protons, and the organic solvent that can release weakly acidic protons includes one or more of triethyl phosphate, sulfolane, and propylene carbonate;

[0019] Place the lithium supplement dispersion liquid in a dispersion liquid containing the positive electrode active material, mix and stir to disperse, obtain a slurry, and coat the slurry on a current collector to form a positive electrode sheet.

[0020] In the embodiments of the present application, first grind the lithium supplement in an organic solvent, so that the dispersion effect of the lithium supplement is better, which can improve the dispersibility of the lithium supplement, and the production steps of the embodiments of the present application are fewer and the production is relatively simple.

[0021] In any embodiment, the mass ratio of the lithium supplement to the positive electrode active material is (1-3):100. By controlling the mass ratio of the lithium supplement to the positive electrode active material within the above range, the lithium supplement can achieve a better lithium supplement effect, so that when the positive electrode sheet is used in a battery, the amount of the lithium supplement can meet the lithium supplement demand while avoiding the formation of lithium dendrites on the negative electrode due to excessive lithium supplementation.

[0022] In any embodiment, dispersing the lithium supplement in an organic solvent includes: dispersing the lithium supplement in an organic solvent under an inert atmosphere. In the embodiments of the present application, dispersing the lithium supplement in an inert atmosphere can reduce the reaction of the lithium supplement with moisture in the external air, thereby reducing the decomposition of the lithium supplement. Improve the lithium supplement effect of the lithium supplement. In the embodiments of the present application, when dispersing the lithium supplement in a dispersion liquid containing the positive electrode active material, it can also be dispersed under an inert atmosphere to reduce the occurrence of the decomposition of the lithium supplement.

[0023] The third aspect of the present application also provides a method for preparing a positive electrode sheet, including:

[0024] Disperse the lithium supplement agent in an organic solvent to form a lithium supplement agent dispersion liquid, where the lithium supplement agent includes Li 3 N, Li 3 P, Li 2 O 2 and Li 2 S, and one or more of them. The organic solvent includes an organic solvent from which weakly acidic protons can be removed, and the organic solvent from which weakly acidic protons can be removed includes one or more of triethyl phosphate, sulfolane, and propylene carbonate;

[0025] Coat the lithium supplement agent dispersion liquid on the side of the second positive electrode active material layer facing away from the current collector to form a positive electrode plate.

[0026] In the embodiments of the present application, by coating the dispersion liquid of the lithium supplement agent on the side of the second positive electrode active material facing away from the current collector, a lithium supplement film layer is formed on the surface of the second positive electrode active material layer. After the positive electrode plate is assembled into a battery, after the lithium supplement agent plays a lithium supplement role, the lithium supplement agent in the lithium supplement film layer reacts and does not form vacancies in the second positive electrode active material layer. Therefore, it does not affect the charge transfer path of the lithium-ion battery and does not increase the impedance of the battery cell, so it does not affect the long-term cycle stability of the battery cell.

[0027] In any embodiment, dispersing the lithium supplement agent in the organic solvent to form a lithium supplement agent dispersion liquid includes: dispersing the lithium supplement agent, a conductive agent, and an adhesive in the organic solvent to form a lithium supplement agent dispersion liquid. In the embodiments of the present application, by adding a conductive agent, the formed lithium supplement film layer has conductivity, facilitating the transmission of lithium ions; by adding an adhesive, it is easy to form a film, so that the lithium supplement agent is more evenly distributed on the second positive electrode active material layer.

[0028] The fourth aspect of the present application further provides a battery, including the positive electrode plate of the first aspect, or the positive electrode plate prepared by the preparation method of the positive electrode plate of the second aspect, or the positive electrode plate prepared by the preparation method of the positive electrode plate of the third aspect. The battery of the embodiments of the present application has at least the same advantages as the positive electrode plate of the first aspect, or has the same advantages as the positive electrode plate prepared by the preparation method of the positive electrode plate of the second aspect, or has the same advantages as the positive electrode plate prepared by the preparation method of the positive electrode plate of the third aspect, which will not be specifically elaborated here.

[0029] The fifth aspect of the present application further provides an electrical device, including the battery of the fourth aspect. The battery of the electrical device of the embodiments of the present application uses the battery of the fourth aspect, so it has at least the same advantages as the battery of the fourth aspect, which will not be specifically elaborated here.

[0030] The above description is only an overview of the technical solution of the present application. In order to better understand the technical means of the present application, it can be implemented according to the content of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the following specific embodiments of the present application are given. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to the drawings.

[0032] Figure 1 It is a schematic structural diagram of an embodiment of the positive electrode sheet layer provided by the present application;

[0033] Figure 2 It is an exploded structural diagram of an embodiment of the battery cell provided by the present application;

[0034] Figure 3 It is an exploded structural diagram of an embodiment of the battery provided by the present application;

[0035] Figure 4 It is a schematic structural diagram of an embodiment of the electrical device provided by the present application;

[0036] Figure 5 It is a scanning electron microscope image of an embodiment of the lithium supplement agent dispersion provided by the present application;

[0037] Figure 6 It is a scanning electron microscope image of an embodiment of the positive electrode sheet layer provided by the present application.

[0038] Explanation of the reference numerals in the drawings:

[0039] 1000, electrical device; 100, battery; 200, controller; 300, motor; 400, battery module; 10, battery cell; 20, box body; 21, first part; 22, second part; 11, battery cell assembly; 12, end cover; 13, housing; 12a, electrode terminal; 11a, tab; 1110, positive electrode sheet layer; 1111, second positive active material layer; 1112, lithium supplement film layer; 1120, current collector. Detailed Embodiments

[0040] To make the purpose, technical solution and effect of the present application clearer and more definite, the embodiments of the technical solution of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, so they are only examples and cannot be used to limit the protection scope of the present application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above description of the drawings are intended to cover non-exclusive inclusion.

[0042] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, the term "plurality" means two or more (including two). Similarly, "multiple groups" means two or more groups (including two groups), and "multiple pieces" means two or more pieces (including two pieces), unless otherwise specifically defined.

[0043] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0044] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0045] Quantities, ratios, and other numerical values are presented herein in a range format. It should be understood that such range formats are for convenience and brevity and should be understood flexibly, including not only the explicitly specified numerical values as range limits, but also all individual numerical values or sub-ranges subsumed within the said range, as if each numerical value and sub-range were explicitly specified.

[0046] During the first charge and discharge process of current lithium-ion batteries, some lithium ions and electrolyte components form a SEI film on the surface of the negative electrode material, resulting in the loss of a part of lithium ions and a decrease in the energy density of the battery. To make up for this loss, a lithium supplement is usually added to the positive electrode sheet. During the production process of the positive electrode sheet, N-methylpyrrolidone (NMP) is generally used as a solvent to disperse the positive electrode active material, conductive agent, and binder to prepare the positive electrode slurry; when the lithium supplement is added to the N-methylpyrrolidone solvent, the N-methylpyrrolidone solvent will remove a proton hydrogen, and the lithium supplement attacks the N-methylpyrrolidone, causing the N-methylpyrrolidone to undergo a self-condensation reaction, resulting in a significant decomposition of the lithium supplement and a greatly reduced lithium supplement effect.

[0047] The technical solution provided by the first aspect of the present application: A positive electrode sheet, the positive electrode sheet includes a lithium supplement and an organic solvent, at least part of the organic solvent adheres to the lithium supplement, and the lithium supplement includes Li 3 N, Li 3 P, Li 2 O 2 and Li 2 S, one or more of them, and the organic solvent includes an organic solvent with weak proton hydrogen removal, and the organic solvent with weak proton hydrogen removal includes one or more of triethyl phosphate, sulfolane, and propylene carbonate.

[0048] In the technical solution of the embodiment of the present application, a positive electrode sheet is provided, and a lithium supplement is included in the positive electrode sheet. In the technical solution of the embodiment of the present application, the lithium supplement includes Li 3 N, Li 3 P, Li 2 O 2 one or more of them, among which, the theoretical capacity of Li 3 N reaches 2300 mAh / g, the theoretical capacity of Li 3 P reaches 1616 mAh / g, the theoretical capacity of Li 2 O 2 reaches 1168 mAh / g, and the theoretical capacity of Li 2 S reaches 1166 mAh / g, so that in the embodiment of the present application, the lithium supplement effect can be achieved by adding a small amount of lithium supplement. In the embodiment of the present application, Li 3 N releases nitrogen gas as a lithium supplement, and Li 2 O 2 releases oxygen or generates lithium superoxide as a lithium supplement, and the air bag can be removed after the battery formation process to achieve no by-product residue on the positive electrode; Li 3 P and Li 2 S form Li x P and Li yIntermediate phase residue of S; In the embodiments of the present application, by using an organic solvent with weak proton hydrogen removal to disperse the lithium supplement agent, when forming the positive electrode sheet, at least part of the organic solvent adheres to the surface of the lithium supplement agent. The amount of proton hydrogen removed by the organic solvent is very weak, and the amount of proton hydrogen removed can be ignored, reducing the probability of the deprotonation-self-condensation reaction between the lithium supplement agent and the organic solvent, reducing the occurrence of side reactions of the lithium supplement agent, and improving the lithium supplement effect of the lithium supplement agent.

[0049] In the embodiments of the present application, by adding a lithium supplement agent to the positive electrode sheet, after the positive electrode sheet is assembled into a battery, during the battery charging process, an external voltage is applied, so that the lithium supplement agent in the positive electrode sheet removes electrons, and the lithium supplement agent decomposes into lithium ions, so that the lithium supplement agent can decompose into lithium ions to achieve the lithium supplement effect.

[0050] It should be noted that for the positive electrode sheet in the embodiments of the present application, after being assembled into a battery in the later stage, after formation or cycling, the atomic number ratio of the constituent elements of Li 3 In the atomic number ratio of the constituent elements of N, the atomic number ratio of the Li element can be greater than 3, or less than 3 and greater than 0, and the atomic number ratio of the N element can be greater than 1, or less than 1 and greater than 0. Li 3 In the atomic number ratio of the constituent elements of P, the atomic number ratio of the Li element can be greater than 3, or less than 3 and greater than 0, and the atomic number ratio of the P element can be greater than 1, or less than 1 and greater than 0. Li 2 O 2 In the atomic number ratio of the constituent elements of, the atomic number ratio of the Li element can be greater than 2, or less than 2 and greater than 0, and the atomic number ratio of the O element can be greater than 2, or less than 2 and greater than 0. Li 2 In the atomic number ratio of the constituent elements of S, the atomic number ratio of the Li element can be greater than 2, or less than 2 and greater than 0, and the atomic number ratio of the S element can be greater than 1, or less than 1 and greater than 0.

[0051] In the embodiments of the present application, the proton hydrogen in the molecular structures of triethyl phosphate, sulfolane, and propylene carbonate is weakly removed, and it is difficult to undergo a self-condensation reaction with the lithium supplement agent, which can reduce the occurrence of side reactions of the lithium supplement agent. At the same time, in the embodiments of the present application, triethyl phosphate and propylene carbonate are non-toxic or have low toxicity, reducing the impact on the environment during the production of the positive electrode sheet. In the embodiments of the present application, triethyl phosphate or propylene carbonate can be used as an organic solvent to better disperse the lithium supplement agent. The above three organic solvents have good boiling points, heat of vaporization, viscosity, and surface tension, such that the surface tension of the organic solvent in the embodiments of the present application preferably reaches 30 dyne / cm - 30.6 dyne / cm, and can coat the surface of the lithium supplement agent; the viscosity of the organic solvent is preferably 1.38 mPa·s - 1.76 mPa·s, making the organic solvent easy to stir and better dispersing the lithium supplement agent; the heat of vaporization is 55.3 KJ / mol - 57.4 KJ / mol, such that during the production of the positive electrode sheet in the embodiments of the present application, the organic solvent is easy to volatilize. In the embodiments of the present application, during the production of the positive electrode sheet, there is still some organic solvent with weakly removed proton hydrogen remaining in the positive electrode sheet. The remaining organic solvent can adhere to the surface of the lithium supplement agent or be located between adjacent lithium supplement agents.

[0052] In some embodiments, the D50 particle size of the lithium supplement agent is 1 μm - 10 μm. In the embodiments of the present application, when the D50 particle size of the lithium supplement agent is within the above range, on the one hand, the dispersibility of the lithium supplement agent is better, and the lithium supplement agent can be better dispersed in the organic solvent, making the surface of the film layer formed by coating the slurry containing the lithium supplement agent relatively flat during the production of the positive electrode sheet; on the other hand, the lithium supplement agent with a D50 particle size of 1 μm - 10 μm has an extremely small particle size and a large specific surface area, which can accelerate the solvation process of the lithium supplement agent, better improve the dispersibility of the lithium supplement agent, and reduce or avoid the occurrence of agglomeration of the lithium supplement agent; on the further hand, the D50 particle size of the lithium supplement agent is 1 μm - 10 μm, and the decomposition rate of the lithium supplement agent is relatively high, which is beneficial to improving the lithium supplement efficiency. Among them, the D50 particle size of the lithium supplement agent is 1 μm, 2 μm, 3 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc., or a range composed of any two of the above values, for example, 1 μm - 3 μm, 3 μm - 6 μm, 6 μm - 10 μm, etc.

[0053] In some embodiments, the D50 particle size of the lithium supplement agent is 3 μm - 8 μm. In the embodiments of the present application, the D50 particle size of the lithium supplement agent is within the above range, so that the dispersibility of the lithium supplement agent is better, and the lithium supplement agent can be better dispersed in the organic solvent. Among them, the D50 particle size of the lithium supplement agent is 3 μm, 4 μm, 4.8 μm, 5 μm, 5.6 μm, 6 μm, 7 μm, 7.4 μm, 8 μm, etc., or a range composed of any two of the above values. For example, 3 μm - 4.8 μm, 4.8 μm - 5.6 μm, 5.6 μm - 8 μm, etc.

[0054] In some embodiments, as Figure 1 shown, the positive electrode plate includes a positive electrode plate layer 1110 and a current collector 1120. The positive electrode plate layer 1110 is provided on one or both sides of the current collector 1120. The positive electrode plate layer 1110 includes a first positive electrode active material layer, and a lithium supplement agent and an organic solvent are dispersed in the first positive electrode active material layer. In the embodiments of the present application, the positive electrode plate layer 1110 includes a first positive electrode active material layer, and the lithium supplement agent is dispersed in the first positive electrode active material layer, so that in the embodiments of the present application, the manufacturing process of the positive electrode plate is relatively simple, and at the same time, the lithium supplement agent can play a lithium supplement effect. In the embodiments of the present application, the first positive electrode active material layer includes a positive electrode active material, a conductive agent, a binder, etc.

[0055] In some embodiments, the positive electrode plate includes a positive electrode plate layer 1110 and a current collector 1120. The positive electrode plate layer 1110 is provided on one or both sides of the current collector 1120; the positive electrode plate layer 1110 includes a second positive electrode active material layer 1111 and a lithium supplement film layer 1112. The lithium supplement film layer 1112 is provided on the side of the second positive electrode active material layer 1111 facing away from the current collector 1120. The lithium supplement film layer 1112 includes a lithium supplement agent and an organic solvent. In the embodiments of the present application, the positive electrode plate layer includes a second positive electrode active material layer 1111 and a lithium supplement film layer 1112. In the embodiments of the present application, by setting the lithium supplement agent as a film layer on the surface of the second positive electrode active material layer 1111, after the positive electrode plate is assembled into a battery, after the lithium supplement agent plays a lithium supplement role, the lithium supplement agent reacts and does not form vacancies in the second positive electrode active material layer 1111. Therefore, it does not affect the charge transfer of the lithium ion battery, does not increase the impedance of the positive electrode plate, and does not affect the electrochemical stability of the lithium ion battery. In the embodiments of the present application, the first positive electrode active material layer and the second positive electrode active material layer 1111 are only used to distinguish the positive electrode active material layer, and both belong to the positive electrode active material layer. The second positive electrode active material layer 1111 may also include a positive electrode active material, a conductive agent, a binder, etc.

[0056] In some embodiments, the lithium supplement film layer 1112 further includes a conductive agent and a binder. In the embodiments of the present application, the inclusion of a conductive agent in the lithium supplement film layer 1112 can improve the conductivity of the lithium supplement film layer 1112, which is beneficial to the transport of active ions. In the embodiments of the present application, the inclusion of a binder in the lithium supplement film layer 1112 is beneficial to the interaction with the lithium supplement agent and is easy to improve the film-forming performance of the lithium supplement film layer 1112.

[0057] In some embodiments, the thickness range of the lithium supplement film layer 1112 is 5 μm - 20 μm. By controlling the thickness of the lithium supplement film layer 1112 within the above range, the release effect of the lithium supplement agent in the lithium supplement film layer in the embodiments of the present application is better, which is beneficial to lithium supplementation. Among them, the thickness of the lithium supplement film layer 1112 is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, etc., or a range composed of any two of the above values. For example, 5 μm - 9 μm, 9 μm - 13 μm, 13 μm - 20 μm, etc.

[0058] In some embodiments, in the lithium supplement film layer 1112, the mass ratio of the lithium supplement agent, the conductive agent, and the binder is (60 - 90):(5 - 30):(5 - 10). By controlling the mass ratio range of the lithium supplement agent, the conductive agent, and the binder in the lithium supplement film layer 1112, the lithium supplement film layer 1112 has a better lithium supplement effect, a better conductive layer, and film-forming properties. Among them, the mass ratio of the lithium supplement agent, the conductive agent, and the binder is 60:5:5, 60:30:5, 60:30:10, 70:5:5, 80:5:5, 90:5:5, 60:10:5, 60:20:5, 60:5:8, 60:20:9, etc., or a range composed of any two of the above values. For example, (60 - 70):(5 - 10):(5 - 8), (70 - 80):(10 - 20):(8 - 9), (80 - 90):(20 - 30):(9 - 10), etc.

[0059] In some embodiments, both the first positive electrode active material layer and the second positive electrode active material layer 1111 include a positive electrode active material, and the positive electrode active material includes one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide. In the embodiments of the present application, the positive electrode active material can be one or more of the above materials. In the embodiments of the present application, the lithium supplement agent, as an additive, is combined with an organic solvent from which weak proton hydrogen is removed, and can be applied to the positive electrode plate of the above positive electrode active material, which is beneficial to lithium supplementation. The embodiments of the present application are not limited to the above positive electrode active materials and may also be applicable to other positive electrode active materials.

[0060] In any embodiment, the mass ratio of the lithium supplement agent to the positive electrode active material is (1-3):100. By controlling the mass ratio of the lithium supplement agent to the positive electrode active material within the above range, the lithium supplement agent can achieve a better lithium supplement effect, so that when the positive electrode sheet is used in a battery, the amount of the lithium supplement agent can meet the lithium supplement requirement while avoiding the formation of lithium dendrites on the negative electrode. Among them, the mass ratio of the lithium supplement agent to the positive electrode active material is 1:100, 1.5:100, 1.8:100, 2:100, 2.4:100, 2.6:100, 3:100, etc., or a range composed of any two of the above values. For example, (1-1.8):100, (1.8-2.4):100, (2.4-3):100, etc.

[0061] In the embodiments of the present application, the organic solvent for weak proton hydrogen extraction has a dehydrogenation energy barrier greater than 375 kcal / mol for the organic solvent. Among them, the dehydrogenation energy barrier can be obtained through theoretical calculation. In the embodiments of the present application, the dehydrogenation energy barrier of triethyl phosphate is 396 kcal / mol, the dehydrogenation energy barrier of sulfolane is 380 kcal / mol, and the dehydrogenation energy barrier of propylene carbonate is 384 kcal / mol.

[0062] In some embodiments, based on the mass of the positive electrode sheet layer 1110, the mass percentage of the organic solvent is 1×10 3 ppm - 9.9×10 3 ppm. In the embodiments of the present application, the organic solvent accounts for 1×10 3 ppm - 9.9×10 3 ppm of the mass of the positive electrode sheet layer 1110. The content of the organic solvent can be measured by gas chromatography. In the embodiments of the present application, during the production process of the positive electrode sheet, the organic solvent is used as a reagent for dispersing the lithium supplement agent. After the positive electrode sheet is coated and then through the baking step, part of the organic solvent still remains in the positive electrode sheet. During the production process of the positive electrode sheet, the lithium supplement agent is dispersed in the organic solvent. In the embodiments of the present application, using an organic solvent for weak proton hydrogen extraction can also reduce the occurrence of side reactions between the lithium supplement agent and water vapor in the air during the production process of the electrode sheet. Among them, the organic solvent accounts for 1×10 3 ppm, 2×10 3 ppm, 3×10 3 ppm, 5×10 3 ppm, 6×10 3 ppm, 6.052×10 3 ppm, 7×10 3 ppm, 8×10 3 ppm, 9×10 3 ppm, 9.5×10 3 ppm, 9.9×10 3ppm or the like, or a range composed of any two of the above values. For example, 1×10 3 ppm - 5×10 3 ppm, 5×10 3 ppm - 8×10 3 ppm, 8×10 3 ppm - 9.9×10 3 ppm or the like.

[0063] The second aspect of the present application further provides a method for preparing a positive electrode plate, including:

[0064] S110, dispersing the lithium supplement agent in an organic solvent to form a lithium supplement agent dispersion liquid, wherein the lithium supplement agent includes Li 3 N, Li 3 P, Li 2 O 2 one or more of them, and the organic solvent includes an organic solvent for weak proton hydrogen removal, and the organic solvent for weak proton hydrogen removal includes one or more of triethyl phosphate, sulfolane, and propylene carbonate.

[0065] In an embodiment of the present application, grinding and dispersing the lithium supplement agent in an organic solvent for weak proton hydrogen removal can improve the dispersion effect of the lithium supplement agent and reduce the occurrence of agglomeration of the lithium supplement agent.

[0066] S120, placing the lithium supplement agent dispersion liquid in a dispersion liquid containing a positive electrode active material, dispersing to obtain a slurry, and coating the slurry on the current collector 1120 to form a positive electrode plate.

[0067] In an embodiment of the present application, the preparation method of the dispersion liquid containing a positive electrode active material includes dispersing the positive electrode active material, a conductive agent, a binder, and any other components in an organic solvent for weak proton hydrogen removal to form a dispersion liquid of the positive electrode active material.

[0068] In the related art, directly dispersing the lithium supplement agent in the dispersion liquid of the positive electrode active material will result in the occurrence of agglomeration of the lithium supplement agent. To solve the above technical problems, in the implementation manner of the present application, the lithium supplement agent is first dispersed in an organic solvent for grinding, so that the dispersion effect of the lithium supplement agent is better, and the dispersibility of the lithium supplement agent can be improved; then the lithium supplement agent dispersion liquid is mixed and dispersed with the dispersion liquid containing the positive active material, which can reduce the occurrence of agglomeration of the lithium supplement agent, and the manufacturing steps of the implementation manner of the present application are less and the manufacturing is relatively simple.

[0069] In some embodiments, the mass ratio of the lithium supplement agent to the positive electrode active material is (1-3):100. In the embodiments of the present application, by controlling the mass ratio of the lithium supplement agent to the positive electrode active material within the above range, in the embodiments of the present application, the lithium supplement agent can achieve a better lithium supplement effect, so that when the positive electrode sheet is used in a battery, the amount of the lithium supplement agent can meet the lithium supplement requirement, and at the same time, it will not precipitate too much on the negative electrode sheet, reducing the formation of lithium dendrites. Among them, the mass ratio of the lithium supplement agent to the positive electrode active material is 1:100, 1.5:100, 1.8:100, 2:100, 2.4:100, 2.6:100, 3:100, etc., or a range composed of any two of the above values. For example, (1-1.8):100, (1.8-2.4):100, (2.4-3):100, etc.

[0070] In some embodiments, the lithium supplement agent is dispersed in an organic solvent, including: dispersing the lithium supplement agent in an organic solvent under an inert atmosphere. In the embodiments of the present application, dispersing the lithium supplement agent in an inert atmosphere can reduce the reaction of the lithium supplement agent with moisture in the external air, thereby reducing the decomposition of the lithium supplement agent and improving the lithium supplement effect of the lithium supplement agent. In the embodiments of the present application, dispersing the lithium supplement agent in a dispersion liquid containing the positive electrode active material can also be carried out under an inert atmosphere to reduce the occurrence of the decomposition of the lithium supplement agent.

[0071] The third aspect of the present application also provides a method for preparing a positive electrode sheet, including:

[0072] S210, dispersing the lithium supplement agent in an organic solvent to form a lithium supplement agent dispersion liquid, wherein the lithium supplement agent includes one or more of Li 3 N, Li 3 P, Li 2 O 2 , and the organic solvent includes an organic solvent for weak proton hydrogen removal, and the organic solvent for weak proton hydrogen removal includes one or more of triethyl phosphate, sulfolane, and propylene carbonate.

[0073] S220, coating the lithium supplement agent dispersion liquid on the side of the second positive electrode active material layer 1111 away from the current collector 1120 to form a positive electrode sheet.

[0074] In an embodiment of the present application, the method for preparing the second positive electrode active material layer 1111 includes dispersing a positive electrode active material, a conductive agent, a binder, and any other components in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector 1120, and after processes such as drying, the second positive electrode active material layer 1111 is formed on the current collector 1120. In the implementation of the present application, a lithium supplement agent dispersion liquid is coated on the side of the second positive electrode active material layer 1111 facing away from the current collector 1120 to form a lithium supplement film layer 1112, thereby forming a positive electrode plate. In an embodiment of the present application, the solvent for dispersing the positive electrode active material, the conductive agent, the binder, and any other components during the preparation process of the second positive electrode active material layer 1111 is different from the solvent for dispersing the lithium supplement agent. In other embodiments, the two may also be the same, for example, both belong to organic solvents with weak proton hydrogen removal.

[0075] In the implementation manner of the present application, by coating the dispersion liquid of the lithium supplement agent on the side of the second positive electrode active material facing away from the current collector 1120, a lithium supplement film layer 1112 is formed on the surface of the second positive electrode active material layer 1111. After the positive electrode plate is assembled into a battery, after the lithium supplement agent plays a lithium supplement role, the lithium supplement agent in the lithium supplement film layer 1112 reacts and does not form vacancies in the second positive electrode active material layer 1111. Therefore, it does not affect the charge transfer of the lithium-ion battery and does not affect the electrochemical stability of the lithium-ion battery. In the implementation manner of the present application, the lithium supplement agent is dispersed in an organic solvent with weak proton hydrogen removal. The lithium supplement agent does not attack the organic solvent, and the organic solvent does not undergo a self-condensation reaction or the amount of self-condensation reaction is very weak, reducing the occurrence of side reactions of the lithium supplement agent and improving the lithium supplement effect of the lithium supplement agent.

[0076] In some implementation manners, dispersing the lithium supplement agent in an organic solvent to form a lithium supplement agent dispersion liquid includes: dispersing the lithium supplement agent, a conductive agent, and an adhesive in the organic solvent to form a lithium supplement agent dispersion liquid. In the implementation manner of the present application, by adding a conductive agent, the formed lithium supplement film layer 1112 in the implementation manner of the present application has conductivity, facilitating the transmission of lithium ions. In the implementation manner of the present application, by adding an adhesive, it is convenient for the lithium supplement film layer 1112 to form a film and uniformly cover the surface of the second positive electrode active material layer 1111.

[0077] The fourth aspect of the present application further provides a battery, including the positive electrode plate of the first aspect, or the positive electrode plate prepared by the preparation method of the positive electrode plate of the second aspect, or the positive electrode plate prepared by the preparation method of the positive electrode plate of the third aspect. The battery in the implementation manner of the present application has at least the same advantages as the positive electrode plate of the first aspect, or has the same advantages as the positive electrode plate prepared by the preparation method of the positive electrode plate of the second aspect, or has the same advantages as the positive electrode plate prepared by the preparation method of the positive electrode plate of the third aspect, which will not be specifically elaborated herein.

[0078] The fifth aspect of the present application further provides an electrical device, including the battery of the fourth aspect. The battery of the electrical device in the embodiments of the present application adopts the battery of the fourth aspect, and thus has at least the same advantages as the battery of the fourth aspect, which will not be elaborated herein specifically.

[0079] In addition, the positive electrode plate, battery cell, battery and electrical device of the present application will be described below with reference to the accompanying drawings as appropriate.

[0080] In the embodiments of the present application, a battery cell refers to the smallest unit that makes up a battery. The battery cell further includes an electrolyte and a separator. The separator is disposed between the positive electrode plate and the negative electrode plate, mainly serving to prevent short circuit between the positive and negative electrodes, and at the same time allowing ions to pass through. During the charging and discharging process of the battery, active ions Li + intercalate and deintercalate between the positive electrode plate and the negative electrode plate, and the electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate.

[0081] In some embodiments, the current collector included in the positive electrode plate is a positive current collector, and the positive current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0082] In some embodiments, the first positive electrode active material layer and the second positive electrode active material layer optionally include a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0083] In some embodiments, the first positive electrode active material layer and the second positive electrode active material layer optionally include a conductive agent. As an example, the conductive agent can include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0084] The negative electrode plate includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector. The negative electrode film layer includes the negative electrode active material of the above embodiments.

[0085] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0086] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, copper foil can be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0087] In some embodiments, the negative electrode film layer may further optionally include a binder. The binder can be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0088] In some embodiments, the negative electrode film layer may further optionally include a conductive agent. The conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0089] In some embodiments, the negative electrode film layer may further optionally include other additives, such as thickeners, such as sodium carboxymethyl cellulose (CMC-Na), etc.

[0090] In some embodiments, the negative electrode plate can be prepared in the following manner: dispersing the components for preparing the negative electrode plate, such as the negative electrode active material, conductive agent, binder, and any other components, in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode plate can be obtained.

[0091] The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. The present application has no specific limitation on the type of the electrolyte, and it can be selected according to requirements.

[0092] In some embodiments, the electrolyte includes an electrolyte salt and a solvent.

[0093] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0094] 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, methyl ethyl sulfone, and diethyl sulfone.

[0095] In some embodiments, the electrolyte may further optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature or low-temperature performance of the battery, etc.

[0096] In some embodiments, the battery cell further includes a separator. The present application does not have any particular limitation on the type of the separator, and any well-known porous structure separator with good chemical stability and mechanical stability can be selected.

[0097] In some embodiments, the material of the separator may be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without any particular limitation.

[0098] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be made into a battery cell assembly by a winding process or a stacking process.

[0099] In some embodiments, as Figure 2 shown, the battery cell 10 may include an outer package. The outer package may be used to encapsulate the above-mentioned battery cell assembly 11 and the electrolyte. The outer package includes an end cap 12, a housing 13, and other functional components.

[0100] The end cap 12 refers to a component that covers the opening of the housing 13 to isolate the internal environment of the battery cell 10 from the external environment. Without limitation, the shape of the end cap 12 can be adapted to the shape of the housing 13 to fit the housing 13. Optionally, the end cap 12 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 12 is not easily deformed when subjected to extrusion and collision, enabling the battery cell 10 to have higher structural strength and improved safety performance. Functional components such as electrode terminals 12a can be provided on the end cap 12. The electrode terminal 12a can be used for electrically connecting with the battery core assembly 11 to output or input the electrical energy of the battery cell 10. In some embodiments, a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 10 reaches a threshold can also be provided on the end cap 12. The material of the end cap 12 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special restrictions on this. In some embodiments, an insulating member (not shown in the figure) can also be provided on the inner side of the end cap 12, and the insulating member can be used to isolate the electrical connection components in the housing 13 from the end cap 12 to reduce the risk of short circuit. Exemplarily, the insulating member can be plastic, rubber, etc.

[0101] The housing 13 is a component used to cooperate with the end cap 12 to form the internal environment of the battery cell 10, wherein the formed internal environment can be used to accommodate the battery core assembly 11, the electrolyte, and other components. The housing 13 and the end cap 12 can be independent components. An opening can be provided on the housing 13, and the end cap 12 is covered at the opening to form the internal environment of the battery cell 10. Without limitation, the end cap 12 and the housing 13 can also be integrated. Specifically, the end cap 12 and the housing 13 can first form a common connection surface before other components are put into the housing, and when it is necessary to encapsulate the inside of the housing 13, the end cap 12 is then covered on the housing 13. The housing 13 can be of various shapes and various sizes, such as rectangular parallelepiped shape, cylindrical shape, hexagonal prism shape, etc. Specifically, the shape of the housing 13 can be determined according to the specific shape and size of the battery core assembly 11. The material of the housing 13 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special restrictions on this.

[0102] One or more battery core assemblies 11 can be included in the housing 13. The parts of the positive electrode plate and the negative electrode plate without active substances respectively constitute the electrode tabs 11a. The positive electrode tab and the negative electrode tab can be located at one end of the main body part together or at both ends of the main body part respectively. During the charging and discharging process of the battery, the positive active substance and the negative active substance react with the electrolyte, and the electrode tab 11a is connected to the electrode terminal to form a current loop.

[0103] Please refer to Figure 3 , Figure 3Schematic diagram of an exploded structure of an embodiment of the battery 100 provided by the present application. The battery 100 includes a box body 20 and battery cells 10, and the battery cells 10 are accommodated in the box body 20. Among them, the box body 20 is used to provide an accommodation space for the battery cells 10, and the box body 20 can adopt various structures. In some embodiments, the box body 20 may include a first part 21 and a second part 22, the first part 21 and the second part 22 cover each other, and the first part 21 and the second part 22 jointly define an accommodation space for accommodating the battery cells 10. The second part 22 may be a hollow structure with one end open, and the first part 21 may be a plate-like structure. The first part 21 covers the open side of the second part 22 so that the first part 21 and the second part 22 jointly define an accommodation space; the first part 21 and the second part 22 may also both be hollow structures with one side open, and the open side of the first part 21 covers the open side of the second part 22. Of course, the box body 20 formed by the first part 21 and the second part 22 can be of various shapes, such as a cylinder, a cuboid, etc.

[0104] In the battery 100, there may be multiple battery cells 10, and the multiple battery cells 10 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection means that there are both series and parallel connections among the multiple battery cells 10. The multiple battery cells 10 can be directly connected in series, in parallel, or in a hybrid connection together, and then the whole formed by the multiple battery cells 10 is accommodated in the box body 20; of course, the battery 100 can also be that multiple battery cells 10 are first connected in series, in parallel, or in a hybrid connection to form a battery module form, and then multiple battery modules are connected in series, in parallel, or in a hybrid connection to form a whole and are accommodated in the box body 20. The battery 100 may further include other structures. For example, the battery 100 may further include a busbar component for realizing electrical connection among the multiple battery cells 10.

[0105] The battery 100 in the embodiment of the present application includes a lithium-ion battery as the battery cell 10. In other embodiments, the battery 100 may further include any one or several of lithium-sulfur batteries, sodium-ion batteries, and magnesium-ion batteries, but is not limited thereto. The battery cell 10 can be in the shape of a cylinder, a flat body, a cuboid, or other shapes, etc.

[0106] In some embodiments, the battery 100 can be assembled into a battery module. The number of batteries 100 included in the battery module can be one or more, and those skilled in the art can select the specific number according to the application and capacity of the battery module.

[0107] In addition, the present application also provides an electrical device, which includes at least one of the battery cells and / or battery 100 provided by the present application. The battery cell or battery 100 can be used as the power supply of the electrical device or as the energy storage unit of the electrical device. The electrical device can include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0108] As the electrical device, the battery cell and / or battery 100 can be selected according to its usage requirements.

[0109] Figure 4 As shown, it is an electrical device as an example. The electrical device is a vehicle such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. Specifically, a structural schematic diagram of the electrical device 1000 is provided. A battery 100 is provided inside the electrical device 1000, and the battery 100 can be arranged at the bottom, head, or tail of the electrical device 1000. The battery 100 can be used for power supply of the electrical device 1000. For example, the battery 100 can be used as the operating power supply of the electrical device 1000. The electrical device 1000 can also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300. For example, it is used for the working power requirements during the start, navigation, and driving of the electrical device 1000.

[0110] In some embodiments of the present application, the battery 100 can not only be used as the operating power supply of the electrical device 1000, but also as the driving power supply of the electrical device 1000, replacing or partially replacing fuel or natural gas to provide driving power for the electrical device 1000.

[0111] The beneficial effects of the present application will be further described below in conjunction with embodiments.

[0112] In order to make the technical problems, technical solutions, and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail in conjunction with embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation to the present application and its application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0113] Embodiment 1

[0114] 1.1) Preparation of the positive electrode plate:

[0115] S111. Mix 4.85 g of the cathode active material lithium iron phosphate, 0.115 g of conductive carbon black, and 0.0375 g of polyvinylidene fluoride, add N-methylpyrrolidone and stir to form a dispersion of the cathode active material.

[0116] S112. Disperse 0.0485 g of the lithium supplement agent Li 3 N in 2 g of the organic solvent triethyl phosphate (TEP) to form a dispersion of the lithium supplement agent. Among them, the processing environment is an argon glove box with a humidity of 0.02 ppm - 0.06 ppm, specifically 0.04 ppm; the oxygen content is 0.05 ppm - 4.5 ppm, specifically 0.1 ppm; the mass of TEP is 41.24 times the mass of lithium nitride. In other embodiments, the mass of TEP is 41 - 76 times the mass of lithium nitride; the grinding time is 3 min - 7 min, and the specific grinding time in the embodiment of the present application is 5 min. The particle size D50 of Li 3 N is 3.75 μm. As Figure 5 shown, after the mixed wet grinding, the Li 3 N particles have no obvious agglomeration, and the particle size is 2 μm - 4 μm.

[0117] S122. Add the dispersion of the lithium supplement agent to the dispersion of the cathode active material, stir for 10 minutes at a stirring speed of 2000 r / min to form a cathode slurry. Among them, the mass ratio of the lithium supplement agent in the dispersion of the lithium supplement agent to the cathode active material in the dispersion of the cathode active material is 1:100. Coat the cathode slurry on the surface of the current collector aluminum foil, dry, cold press, and slit to obtain a cathode electrode sheet.

[0118] Among them, in other embodiments, the order of steps S111 and S112 can also be exchanged or occur simultaneously.

[0119] In the embodiment of the present application, the cathode electrode sheet includes a current collector and a cathode electrode sheet layer provided on one or both sides of the current collector. The cathode electrode sheet layer includes a first cathode active material layer. The first cathode active material layer includes lithium iron phosphate, conductive carbon black, and polyvinylidene fluoride. Li 3 N is dispersed in the first cathode active material layer, and the organic solvent triethyl phosphate (TEP) is partially attached to Li 3 N.

[0120] 1.2) Preparation of the anode electrode sheet.

[0121] Use styrene-butadiene rubber as the binder and conductive carbon as the conductive agent; mix the anode active material, styrene-butadiene rubber, and conductive carbon in a mass ratio of 96:2:2 to prepare an anode slurry. Coat the anode slurry on the surface of the anode current collector copper foil, and after drying and cold pressing, obtain an anode electrode sheet.

[0122] 1.3) Separator

[0123] Use a polyethylene separator film.

[0124] 1.4) Electrolyte.

[0125] Mix ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 3:7, then uniformly dissolve LiPF6 in the above solution, and add fluoroethylene carbonate (FEC) to obtain the electrolyte. In this electrolyte, the concentration of LiPF6 is 1 mol / L, and the mass percentage of fluoroethylene carbonate is 2%.

[0126] 1.5) Assembly of the battery.

[0127] Stack and wind the above positive electrode sheet, separator film, and negative electrode sheet in sequence to obtain an electrode assembly; place the electrode assembly in a housing, add the above electrolyte, and after processes such as encapsulation, standing, formation, and aging, obtain a battery cell.

[0128] 2. The specific test methods for relevant parameters are as follows:

[0129] 2.1) D50 particle size test.

[0130] Weigh 5 - 10 g of the lithium supplement agent and pour it into the dry injection sampler of the MS300 laser particle size analyzer. Then, turn on the air flow to blow the sample into the test optical path system. When the particles are irradiated by the laser beam, the particle size distribution characteristics can be obtained by receiving and measuring the energy distribution of the scattered light. The obscuration is 8 - 12%. After the software deducts the blank background, calculate and analyze to obtain the D50 particle size of the lithium supplement agent.

[0131] 2.2) Battery cycle performance test.

[0132] Charge the fabricated battery at a constant current of 0.01C for formation, aiming to complete the decomposition and lithium release of the lithium supplement agent while realizing the first-cycle SEI of a conventional battery cell.

[0133] Charge the battery at a constant current of 0.33C to a voltage of 3.65V in a constant-temperature environment, and then discharge it at a constant current of 0.33C to a voltage of 2.0V. This is a cycle of charge and discharge. The discharge capacity at this time is recorded as the discharge capacity of the battery in the 1st cycle. Perform n (n≥2) cycles of charge and discharge tests on the battery according to the above method, and record the discharge capacity in the nth cycle.

[0134] The capacity retention rate CR (%) after n cycles of the battery = the discharge capacity in the nth cycle / the discharge capacity in the 1st cycle × 100%. In the embodiment of the present application, specifically record the battery cycle capacity retention rate after 200 cycles.

[0135] 2.3) Determination of the content of organic solvents.

[0136] Create a standard sample using AR99.99% triethyl phosphate (TEP) reagent by gas chromatography. After drying, cut the electrode sheet into a vial, add a quantitative amount of N,N-dimethylformamide (DMF), and ultrasonically dissolve the active material on the surface of the positive electrode sheet for 12 h. Take 0.4 - 1 μL of the liquid for injection testing to detect the residual organic solvent amount on the positive electrode sheet.

[0137] Example 2

[0138] The difference from Example 1 is that 1.1) the preparation of the positive electrode sheet is the same as that in Example 1 for others. Specifically, 1.1) the preparation of the positive electrode sheet includes the following steps:

[0139] S211, Mix 4.85 g of the positive active material lithium iron phosphate, 0.115 g of conductive carbon black, and 0.0375 g of polyvinylidene fluoride, add N-methylpyrrolidone (NMP) and stir to form a positive electrode slurry. Coat the positive electrode slurry on the surface of the current collector aluminum foil and dry it to form a second positive active material layer on the current collector aluminum foil.

[0140] S212, Disperse 0.0485 g of the lithium supplement agent Li 3 N, 0.0027 g of conductive carbon black, and 0.0027 g of polyvinylidene fluoride in 2 g of the organic solvent triethyl phosphate (TEP) to form a lithium supplement agent dispersion liquid. The mass ratio of the lithium supplement agent Li 3 N, conductive carbon black, and polyvinylidene fluoride is 90:5:5. Among them, the processing environment is an argon glove box with a humidity of 0.02 ppm - 0.06 ppm, specifically 0.04 ppm; the oxygen content is 0.05 ppm - 4.5 ppm, specifically 0.1 ppm; the mass of TEP is 41.24 times the mass of lithium nitride. In other embodiments, the mass of TEP is 41 - 76 times the mass of lithium nitride; the grinding time is 3 min - 7 min, and the specific grinding time in the embodiment of the present application is 5 min. The particle size D50 of Li 3 N is 3.75 μm. As Figure 5 shown, there is no obvious agglomeration of the Li 3 N particles after wet mixing and grinding, and the particle size is 2 μm - 4 μm.

[0141] S122, Under an argon atmosphere, coat the lithium supplement agent dispersion liquid on the side of the second positive active material layer facing away from the current collector aluminum foil. After drying, cold pressing, and slitting, a positive electrode sheet is obtained. Among them, the mass ratio of the lithium supplement agent in the lithium supplement agent dispersion liquid to the positive active material in the positive active material dispersion liquid is 1:100. As Figure 6 shown, it includes a second positive active material layer and a lithium supplement film layer.

[0142] In the embodiment of the present application, as Figure 1As shown, the positive electrode plate includes a current collector 1120 and a positive electrode plate layer 1110 disposed on one or both sides of the current collector 1120. The positive electrode plate layer 1110 includes a second positive active material layer 1111 and a lithium supplement film layer 1112. The second positive active material layer 1111 includes lithium iron phosphate, conductive carbon black, and polyvinylidene fluoride. The lithium supplement film layer includes Li 3 N, triethyl phosphate (TEP), conductive carbon black, and polyvinylidene fluoride. The organic solvent triethyl phosphate (TEP) is partially attached to Li 3 N.

[0143] For the specific target components of each example and comparative example, please refer to Table 1 in detail.

[0144] The above is only the implementation mode of this application, and does not limit the patent scope of this application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of this application, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of this application by the same token.

[0145] Table 1 Sample parameters and performance test results of each example and comparative example.

[0146]

[0147] Note: D50 represents the particle size D50 of the lithium supplement agent; the mass ratio represents the mass ratio of the lithium supplement agent to the positive active material; the mass percentage represents the mass percentage of the organic solvent in the positive electrode plate layer; the dehydrogenation energy barrier represents the dehydrogenation energy barrier of the organic solvent; the setting method represents the setting method of the lithium supplement agent in the positive electrode plate. Method 1 means that the lithium supplement agent is dispersed in the first positive active material layer, and method 2 means that the lithium supplement film layer formed by the lithium supplement agent is located on the second positive active material layer; the cycle performance represents the cycle capacity retention rate.

[0148] The results show that in Comparative Example 1 and Comparative Example 2, the organic solvent is NMP, and its dehydrogenation ability is less than 375 kcal / mol, which does not belong to the organic solvent for weak proton hydrogen extraction. Based on Comparative Example 1 and Comparative Example 2, in Examples 1 - 15 of this application, organic solvents such as triethyl phosphate, sulfolane, and propylene carbonate for weak proton hydrogen extraction are used as the organic solvents for the solvent lithium supplement agent. The batteries formed by them have a cycle capacity retention rate of 90.6% - 96.4% after 1000 cycles, which is significantly improved compared with the cycle capacity retention rates of 89.1% and 89.3% in Comparative Example 1 and the comparative example. Compared with Comparative Example 4 and Comparative Example 5, the cycle capacity retention rates of Examples 1 - 15 are also significantly improved. It shows that the implementation mode of this application using an organic solvent for weak proton hydrogen extraction to disperse the lithium supplement agent can improve the lithium supplement effect and the cycle stability of the battery.

[0149] It can be seen from Embodiment 1 to Embodiment 4 that in the implementation mode of the present application, the cycle capacity retention rates of Embodiment 2 and Embodiment 4 are higher than those of Embodiment 1 and Embodiment 3. This shows that when the lithium supplement agent is made into a lithium supplement film layer and disposed on the side of the second positive electrode active material layer away from the current collector, after the lithium supplement agent plays the role of lithium supplement, the lithium supplement agent reacts and will not form a vacancy battery in the second positive electrode active material layer, will not affect the charge transmission path of the battery cell, and will not increase the impedance of the positive electrode sheet, resulting in a relatively high cycle capacity retention rate.

[0150] The above is only the implementation mode of the present application, and does not limit the patent scope of the present application accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A positive electrode sheet, It is characterized in that The positive electrode plate includes a lithium supplement agent and an organic solvent, at least part of the organic solvent is attached to the lithium supplement agent, and the lithium supplement agent includes Li 3 N.Li 3 P.Li 2 O 2 and Li 2 S, wherein the organic solvent comprises an organic solvent that undergoes weak proton hydrogenation, and the organic solvent that undergoes weak proton hydrogenation comprises one or more of triethyl phosphate, cyclopentane sulfone and propylene carbonate.

2. The positive electrode sheet according to claim 1, It is characterized in that The particle size D50 of the lithium supplement agent is 1 μm-10 μm, and optionally 3 μm-8 μm.

3. The positive electrode sheet according to claim 1 or 2, It is characterized in that The positive electrode sheet comprises a positive electrode sheet layer and a current collector, wherein the positive electrode sheet layer is arranged on one side or both sides of the current collector; The positive electrode sheet layer includes a first positive electrode active material layer, in which the lithium supplement agent and the organic solvent are dispersed.

4. The positive electrode sheet according to claim 1 or 2, It is characterized in that The positive electrode sheet comprises a positive electrode sheet layer and a current collector, wherein the positive electrode sheet layer is arranged on one side or both sides of the current collector; The positive electrode layer includes a second positive electrode active material layer and a lithium replenishing film layer, wherein the lithium replenishing film layer is arranged on the side of the second positive electrode active material layer away from the current collector, and the lithium replenishing film layer includes the lithium replenishing agent and the organic solvent. Optionally, the lithium replenishing film layer also includes a conductive agent and a binder.

5. The positive electrode sheet according to claim 3 or 4, It is characterized in that The first positive electrode active material layer and the second positive electrode active material layer both include positive electrode active materials, and the positive electrode active materials include one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide.

6. The positive electrode sheet according to claim 5, It is characterized in that The mass ratio of the lithium supplement agent to the positive electrode active material is (1-3):

100.

7. The positive electrode sheet according to any one of claims 3 to 6, It is characterized in that Based on the mass of the positive electrode layer, the mass proportion of the organic solvent is 1×10 3 ppm-9.9×10 3 ppm.

8. The positive electrode sheet according to any one of claims 1 to 7, It is characterized in that The dehydrogenation energy barrier of the organic solvent for weak proton hydrogenation is greater than 375 kcal / mol.

9. A method for preparing a positive electrode sheet as claimed in any one of claims 1 to 3 and 5 to 8, It is characterized in that include: Dispersing a lithium supplement agent in an organic solvent to form a lithium supplement agent dispersion, wherein the lithium supplement agent includes Li 3 N.Li 3 P.Li 2 O 2 and Li 2 One or more of S, the organic solvent includes an organic solvent that refers to weak proton hydrogen removal, and the weak proton hydrogen removal organic solvent includes one or more of triethyl phosphate, cyclopentane sulfone and propylene carbonate; The lithium supplement agent dispersion is placed in a dispersion containing a positive electrode active material, mixed, stirred and dispersed to obtain a slurry, and the slurry is coated on a current collector to form the positive electrode sheet.

10. A method for preparing a positive electrode sheet according to any one of claims 1-2 and 4-8, It is characterized in that include: Dispersing a lithium supplement agent in an organic solvent to form a lithium supplement agent dispersion, wherein the lithium supplement agent includes Li 3 N.Li 3 P.Li 2 O 2 and Li 2 One or more of S, the organic solvent includes an organic solvent for weak proton hydrogen removal, and the organic solvent for weak proton hydrogen removal includes one or more of triethyl phosphate, cyclopentane sulfone and propylene carbonate; The lithium supplement agent dispersion is coated on the side of the second positive electrode active material layer away from the current collector to form the positive electrode sheet.

11. The method for preparing a positive electrode sheet according to claim 10, It is characterized in that The step of dispersing the lithium supplement agent in the organic solvent to form a lithium supplement agent dispersion comprises: The lithium supplement agent, the conductive agent and the adhesive are dispersed in the organic solvent to form a lithium supplement agent dispersion.

12. A battery, It is characterized in that It comprises the positive electrode sheet as described in any one of claims 1 to 8, or the positive electrode sheet prepared by the method for preparing the positive electrode sheet as described in any one of claims 9 to 11.

13. An electrical device, It is characterized in that Comprising the battery of claim 12.

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