Positive electrode sheet, method for manufacturing the same, battery, and electric device

Abstract

The application discloses a positive electrode sheet, a preparation method thereof, a battery and an electric device. The positive electrode sheet comprises a positive active material layer, wherein the positive active material layer comprises a positive active material; and a capacity compensation layer, wherein the capacity compensation layer is arranged on at least one side of the positive active material layer, and the capacity compensation layer comprises a capacity compensation agent and an additive. In this way, the probability of the reaction between the additive and residual alkali is improved, the content of residual alkali on the surface of the capacity compensation agent is reduced, the capacity compensation effect is improved, and the cycle capacity retention rate of the battery is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to positive electrode sheets and their preparation methods, batteries, and electrical devices. Background Technology

[0002] Batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. During the battery formation process, a solid electrolyte interphase (SEI) film forms on the surface of the negative electrode. This SEI film formation consumes active ions. To compensate for the irreversible capacity loss caused by SEI film formation, a capacity compensator can be placed on the positive electrode. During the first charge cycle, the capacity compensator can release sufficient active ions, improving the battery's cycle capacity retention. However, residual alkali on the surface of the capacity compensator can affect the release of active ions, reducing the capacity compensation effect and lowering the battery's cycle capacity retention. Summary of the Invention

[0003] In view of the technical problems existing in the background art, this application provides a positive electrode sheet that can increase the probability of contact between the capacity compensator and the additive, improve the capacity compensation effect, and improve the cycle capacity retention rate of the battery.

[0004] The first aspect of this application provides a positive electrode sheet, comprising: a positive electrode active material layer, the positive electrode active material layer comprising a positive electrode active material; and a capacity compensation layer disposed on at least one side of the positive electrode active material layer, the capacity compensation layer comprising a capacity compensator and an additive, the additive comprising at least one of elemental sulfur, sulfides, elemental selenium, selenides, elemental phosphorus, phosphides, elemental tellurium, elemental iodine, or elemental boron.

[0005] The positive electrode proposed in this application has both the capacity compensator and additives located in the capacity compensation layer. This increases the probability of contact between the capacity compensator and additives, the probability of reaction between the additives and residual alkali, and reduces the residual alkali content on the surface of the capacity compensator, thereby improving the capacity compensation effect and ultimately increasing the battery's cycle capacity retention. The aforementioned additives dissolve in the electrolyte to form ions, which can diffuse to the negative electrode and participate in the formation of the SEI film, thus improving the structural stability of the SEI film. This, in turn, reduces the battery's DC internal resistance (DCR) while increasing its cycle life.

[0006] According to some embodiments of this application, the additive is coated on at least a portion of the surface of the capacity compensator. Thereby, the additive can react with residual alkali on the surface of the capacity compensator to form a fast ion conductor layer on the surface of the capacity compensator, thereby improving the ionic conductivity of the capacity compensator.

[0007] According to some embodiments of this application, based on the total mass of the capacity compensation layer and the positive electrode active material layer, the mass ratio of the capacity compensator is a1, and the mass ratio of the additive is a2, satisfying 0.01≤a2 / a1≤0.45. Therefore, while reducing the residual alkali content on the surface of the capacity compensator, the probability of reaction between the additive and the capacity compensator is reduced, thus minimizing the impact of the additive on the capacity of the capacity compensator.

[0008] According to some embodiments of this application, 0.5% ≤ a1 ≤ 12%.

[0009] According to some embodiments of this application, 1% ≤ a1 ≤ 10%.

[0010] Therefore, by keeping a1 within the above range, the capacity compensation effect is improved, and the cycle capacity retention rate of the battery is increased.

[0011] According to some embodiments of this application, 0.05% ≤ a2 ≤ 2%.

[0012] According to some embodiments of this application, 0.1% ≤ a2 ≤ 0.5%.

[0013] Therefore, by keeping a2 within the above range, the probability of contact between the additive and the capacity compensator is increased, the reduction effect of the additive on the capacity compensator is improved, the capacity compensator is decomposed into active ions, and the cycle capacity retention rate of the battery is improved.

[0014] According to some embodiments of this application, the mass percentage of the positive electrode active material is 80%-96% based on the total mass of the positive electrode active material layer and the capacity compensation layer. This improves the energy density of the battery.

[0015] According to some embodiments of this application, the sulfide includes at least one of lithium sulfide, sodium sulfide, selenium sulfide, cobalt sulfide, or nickel sulfide.

[0016] According to some embodiments of this application, the phosphide includes at least one of lithium phosphide or sodium phosphide.

[0017] According to some embodiments of this application, the selenide includes at least one of lithium selenide or sodium selenide.

[0018] Therefore, when the additive is the aforementioned material, it can react with the residual alkali on the surface of the capacity compensator to form a fast ion conductor layer, improving the ionic conductivity of the capacity compensator and enhancing the compensation effect of active ions. Simultaneously, these additives can also diffuse to the negative electrode, combining with active ions to form a dense SEI film, improving the toughness of the SEI film, reducing the battery's DC internal resistance (DCR), and increasing the battery's cycle life.

[0019] According to some embodiments of this application, at least a portion of the surface of the capacity compensator is covered with a carbon coating layer. This improves the electronic conductivity of the capacity compensator, reduces its decomposition potential, enhances the compensation effect of active ions, and improves the cycle capacity retention rate of the battery.

[0020] According to some embodiments of this application, the carbon coating layer accounts for 0.5%-10% of the total mass of the capacity compensator. This improves the electronic conductivity of the capacity compensator, reduces its decomposition potential, enhances the compensation effect of active ions, and improves the cycle capacity retention rate of the battery.

[0021] According to some embodiments of this application, the capacity compensation layer further includes the positive electrode active material. This reduces the difficulty of forming the capacity compensation layer and increases the energy density of the battery.

[0022] According to some embodiments of this application, the capacity compensator includes a lithium supplement and / or a sodium supplement, wherein the lithium supplement includes Li₂C₂O₄, Li₂M₁O₂, Li₂M₂O₃, and Li₅Fe. x M 3(1-x) O4, Li6Mn y M 4(1-y) O4 or Li6Co y M 4(1-y) At least one of O4; wherein 0.5≤x≤1, 0.5≤y≤1, M1 includes at least one of Ni, Mn, Cu, Fe, Cr or Mo, M2 includes at least one of Ni, Mn, Fe, Mo, Zr, Si, Cu, Cr or Ru, M3 includes at least one of Al, Nb, Co, Mn, Ni, Mo, Ru or Cr, and M4 includes at least one of Ni, Fe, Cu or Ru. The sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2, NaCrO2, Na3P, Na3N, Na2NiO2, Na2CuO2, Na2FeO2 or NaF. Therefore, when the battery is a lithium-ion battery or a sodium-ion battery, the cycle capacity retention rate of the battery can be improved.

[0023] According to some embodiments of this application, the capacity compensation layer further includes at least one of an adhesive and a conductive agent. This improves the adhesion between the capacity compensation layer and the positive electrode active material layer, reducing the risk of film detachment.

[0024] A second aspect of this application provides a method for preparing a positive electrode sheet, comprising: forming a capacity compensation layer on at least one side of a positive electrode active material layer, the capacity compensation layer comprising a capacity compensator and an additive, the additive comprising at least one selected from elemental sulfur, sulfides, elemental selenium, selenides, elemental phosphorus, phosphides, elemental tellurium, elemental iodine, or elemental boron. This increases the probability of contact between the capacity compensator and the additive, increases the probability of reaction between the additive and residual alkali, reduces the residual alkali content on the surface of the capacity compensator, improves the capacity compensation effect, and improves the cycle capacity retention rate of the battery.

[0025] A third aspect of this application provides a battery comprising a positive electrode sheet provided in the first aspect of this application or a positive electrode sheet prepared by the method provided in the second aspect of this application. This improves the cycle capacity retention rate of the battery and reduces the battery's damping rate (DCR).

[0026] The fourth aspect of this application provides an electrical device that includes the battery provided in the third aspect of this application. This improves the service life of the electrical device.

[0027] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0028] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0029] Figure 1 This is a schematic diagram of the structure of the positive electrode sheet according to one embodiment of this application.

[0030] Figure 2 This is a schematic diagram of the capacity compensator according to one embodiment of this application.

[0031] Figure 3 This is a schematic diagram of the structure of a capacity compensator according to another embodiment of this application.

[0032] Figure 4 This is a schematic diagram of the structure of a capacity compensator according to another embodiment of this application.

[0033] Figure 5 This is a schematic diagram of the structure of a capacity compensator according to another embodiment of this application.

[0034] Figure 6 This is a schematic diagram of the structure of the positive electrode sheet according to another embodiment of this application.

[0035] Figure 7This is a schematic diagram of the structure of the positive electrode sheet according to another embodiment of this application.

[0036] Figure 8 This is a schematic diagram of a battery according to one embodiment of this application.

[0037] Figure 9 yes Figure 8 An exploded view of a battery according to one embodiment of this application is shown.

[0038] Figure 10 This is a schematic diagram of a battery module according to one embodiment of this application.

[0039] Figure 11 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0040] Figure 12 yes Figure 11 An exploded view of a battery pack according to one embodiment of this application is shown.

[0041] Figure 13 This is a schematic diagram of an electrical device in which a battery is used as a power source according to one embodiment of this application.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1 Battery; 11 Casing; 12 Electrode Assembly; 13 Cover Plate; 2 Battery Module; 3 Battery Pack; 31 Upper Housing; 32 Lower Housing; 110 Conductive Agent; 120 Additive; 130 Capacity Compensator; 1000 Positive Electrode Sheet; 1100 Positive Current Collector; 1200 Positive Active Material Layer; 1210 First Positive Active Material Layer; 1220 Second Positive Active Material Layer; 1300 Capacity Compensation Layer. Detailed Implementation

[0044] The embodiments of the technical solution of this application are described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0045] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0046] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0047] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0048] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0049] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0050] Currently, judging from market trends, battery applications are becoming increasingly widespread. Batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of battery applications, market demand is also constantly increasing.

[0051] During battery formation, an SEI film forms on the surface of the negative electrode. This SEI film formation consumes a large number of active ions, reducing the battery's cycle capacity retention. To improve cycle capacity retention, the positive electrode can be pre-compensated for capacity. Capacity compensation for the positive electrode typically involves using additives rich in active ions, which release these ions to compensate for their consumption. During the sintering process of the capacity compensator, residual alkali forms on its surface. This residual alkali affects the release of active ions, reducing the capacity compensation effect. Residual alkali in the positive electrode slurry can cause gel formation, leading to side reactions with the electrolyte and resulting in battery gas production. Adding additives can react with the residual alkali on the capacity compensator surface, consuming it and improving the capacity compensation effect, thus extending battery life. However, because the content of positive electrode active material on the positive electrode sheet is high, while the content of additives and capacity compensators is low, the probability of contact between them is low, reducing the likelihood of reaction between the additives and residual alkali.

[0052] The positive electrode proposed in this application has the additive and capacity compensator located in the same layer, which increases the probability of contact between the additive and the capacity compensator and increases the probability of reaction between the additive and the residual alkali on the surface of the capacity compensator. After the additive reacts with the residual alkali, a fast ion conductor layer can be generated on the surface of the capacity compensator, which improves the ionic conductivity of the capacity compensator, improves the capacity compensation effect, and improves the cycle capacity retention rate of the battery.

[0053] The positive electrode sheet disclosed in this application is applicable to lithium-ion batteries and sodium-ion batteries, and the battery disclosed in this application can be used in electrical devices that use batteries as a power source or in various energy storage systems that use batteries as energy storage elements. Electrical devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys may include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0054] The first aspect of this application provides a positive electrode plate 1000, with reference to... Figure 1 The positive electrode 1000 includes a positive electrode active material layer 1200, which includes a positive electrode active material; and a capacity compensation layer 1300, which is disposed on at least one side of the positive electrode active material layer 1200. The capacity compensation layer 1300 includes a capacity compensator (not shown in the figure) and an additive (not shown in the figure). The additive includes at least one of elemental sulfur, sulfide, elemental selenium, selenide, elemental phosphorus, phosphide, elemental tellurium, elemental iodine, or elemental boron.

[0055] The positive electrode 1000 proposed in this application, with the capacity compensator and additives simultaneously located in the capacity compensation layer 1300, can increase the probability of contact between the capacity compensator and the additives, increase the probability of reaction between the additives and residual alkali on the surface of the capacity compensator, reduce the residual alkali content on the surface of the capacity compensator, improve the capacity compensation effect, and thus improve the cycle capacity retention rate of the battery. By reducing the residual alkali content on the surface of the capacity compensator through additives, the risk of positive electrode slurry gelation is reduced, the probability of residual alkali reacting with the electrolyte leading to battery gas generation is reduced, and the cycle life of the battery is improved. The aforementioned additives 120 dissolve in the electrolyte to form ions, participate in the formation of the SEI film, and thus improve the structural stability of the SEI film, thereby reducing the battery DCR while improving the battery's cycle life.

[0056] According to some embodiments of this application, reference is made to Figure 2 The additive 120 can coat at least a portion of the surface of the capacity compensator 130. This further increases the probability of contact between the additive 120 and the capacity compensator 130, increases the probability of the additive 120 reacting with residual alkali, reduces the residual alkali content on the surface of the capacity compensator 130, improves the capacity compensation effect, and increases the battery's cycle capacity retention rate.

[0057] According to some embodiments of this application, based on the total mass of the capacity compensation layer and the positive electrode active material layer, the mass ratio of the capacity compensator is a1, and the mass ratio of the additive is a2, where 0.01 ≤ a2 / a1 ≤ 0.45. For example, it can be 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or 0.45, or any range of the above values. Therefore, while reducing the residual alkali content on the surface of the capacity compensator 130, the probability of reaction between the additive 120 and the capacity compensator 130 is reduced, thus minimizing the influence of the additive 120 on the capacity of the capacity compensator 130.

[0058] According to some embodiments of this application, 1% ≤ a1 + a2 ≤ 12%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, or 12%, or a range of the above values. This improves the capacity compensation effect, increases the battery's cycle capacity retention rate, reduces the residual alkali content on the surface of the capacity compensation agent 130, reduces the risk of positive electrode slurry gelation, reduces the probability of residual alkali reacting with the electrolyte leading to battery gas production, and improves battery life. According to some specific embodiments of this application, based on the total mass of the capacity compensation layer 1300, the total mass ratio of the capacity compensation agent 130 and the additive 120 is 1.1%-5.5%.

[0059] According to some embodiments of this application, 0.5% ≤ a1 ≤ 12%, for example, it can be 0.5%, 0.7%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or 12%, or any range of the above values. This improves the capacity compensation effect and increases the battery's cycle capacity retention rate. According to some specific embodiments of this application, 1% ≤ a1 ≤ 10%.

[0060] According to some embodiments of this application, 0.05% ≤ a2 ≤ 2%, for example, can be 0.05%, 0.07%, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, 1.9%, or 2%, or can be any range of the above values. Therefore, while reducing the residual alkali content on the surface of the capacity compensator 130, the probability of reaction between the additive 120 and the capacity compensator 130 is reduced, thus minimizing the influence of the additive 120 on the capacity of the capacity compensator 130. According to some specific embodiments of this application, 0.1% ≤ a2 ≤ 0.5%.

[0061] According to some embodiments of this application, based on the total mass of the positive electrode active material layer 1200 and the capacity compensation layer 1300, the mass percentage of the positive electrode active material is b, where a² / b ≤ 0.5%. For example, it can be 0.005%, 0.01%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, or any range of the above values. This reduces the probability of the additive 120 reacting with the positive electrode active material, thereby increasing the energy density of the battery. According to some specific embodiments of this application, 0.01% ≤ a² / b ≤ 0.3%.

[0062] According to some embodiments of this application, 80% ≤ b ≤ 96%, for example, it can be 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, or 96%, or it can be a range of any of the above values.

[0063] According to some embodiments of this application, the sulfide may include at least one of lithium sulfide, sodium sulfide, selenium sulfide, cobalt sulfide, or nickel sulfide.

[0064] According to some embodiments of this application, the phosphide may include at least one of lithium phosphide or sodium phosphide.

[0065] According to some embodiments of this application, the selenide may include at least one of lithium selenide or sodium selenide.

[0066] Therefore, when additive 120 is the aforementioned material, additive 120 can react with the residual alkali on the surface of capacity compensator 130 to form a fast ion conductor layer, thereby improving the ionic conductivity of capacity compensator 130 and enhancing the compensation effect of active ions. Simultaneously, the aforementioned additive 120 dissolves in the electrolyte to form ions, which diffuse to the negative electrode and combine with active ions to form a dense SEI film, improving the toughness of the SEI film, reducing the battery's DCR, and increasing the battery's cycle life.

[0067] According to some embodiments of this application, at least a portion of the surface of the capacity compensator 130 is formed with a carbon coating layer 110. This improves the electronic conductivity of the capacity compensator 130, reduces its decomposition potential, enhances the compensation effect of active ions, and improves the cycle capacity retention rate of the battery.

[0068] In this application, the active ions may include Li + Or Na + .

[0069] According to some embodiments of this application, reference is made to Figure 3 The carbon coating layer 110 covers at least a portion of the surface of the capacity compensator 130, and the additive 120 covers at least a portion of the surface of the carbon coating layer 110.

[0070] According to some embodiments of this application, reference is made to Figure 4 The additive 120 is coated on at least a portion of the surface of the capacity compensator 130, and the carbon coating layer 110 is coated on at least a portion of the surface of the additive 120.

[0071] According to some embodiments of this application, reference is made to Figure 5 The carbon coating layer 110 covers a portion of the surface of the capacity compensator 130, and the additive 120 covers the portion of the capacity compensator 130 that is not coated by the conductive agent.

[0072] This improves the electronic and ionic conductivity of the capacity compensator 130, thereby enhancing the compensation effect of active ions.

[0073] According to some embodiments of this application, when the carbon coating layer 110 and the additive 120 are simultaneously coated on the surface of the capacity compensator 130, the capacity compensator 130 can be prepared by the following method: the capacity compensator coated with the carbon coating layer 110 and the additive are ball-milled, then placed in a reaction vessel and heated at a temperature of 140℃-200℃ for 6h-15h to obtain the capacity compensator 130 with the carbon coating layer 110 and the additive 120 coated on its surface. According to some specific embodiments of this application, the heating temperature can be 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃, or any range of the above values. According to some specific embodiments of this application, the heating time can be 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, or 16h, or any range of the above values.

[0074] According to some embodiments of this application, based on the total mass of the capacity compensator 130, the mass percentage of the carbon coating layer 110 can be 0.5%-10%, for example, it can be 0.5%, 0.7%, 1%, 1.3%, 1.6%, 1.8%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, or any range of the above values. This improves the electronic conductivity of the capacity compensator 130, reduces its decomposition potential, enhances the compensation effect of active ions, and improves the cycle capacity retention rate of the battery.

[0075] According to some embodiments of this application, the capacity compensation layer 1300 may further include the positive electrode active material. Therefore, adding a small amount of positive electrode active material to the capacity compensation layer 1300 increases the thickness of the capacity compensation layer 1300, reduces the difficulty of forming the capacity compensation layer 1300, and improves the energy density of the battery.

[0076] According to some embodiments of this application, reference is made to Figure 1 The positive electrode 1000 further includes a positive current collector 1100, the positive active material layer 1200 is located on at least one side of the positive current collector 1100, and the capacity compensation layer 1300 is located on the side of the positive active material layer 1200 away from the positive current collector 1100.

[0077] According to some embodiments of this application, reference is made to Figure 6 The positive electrode 1000 further includes a positive current collector 1100, the positive active material layer 1200 is located on at least one side of the positive current collector 1100, and the capacity compensation layer 1300 is located between the positive active material layer 1200 and the positive current collector 1100.

[0078] According to some embodiments of this application, reference is made to Figure 7 The positive electrode 1000 further includes a positive current collector 1100, and the positive active material layer 1200 includes a first positive active material layer 1210 and a second positive active material layer 1220. The first positive active material layer 1210 is located on at least one side of the positive current collector 1100, and the second positive active material layer 1220 is located on the side of the first positive active material layer 1210 away from the positive current collector 1100. The capacity compensation layer 1300 is located between the first positive active material layer 1210 and the second positive active material layer 1220.

[0079] Therefore, the battery containing the above-described positive electrode 1000 has excellent cycle capacity retention and capacity.

[0080] According to some embodiments of this application, the positive electrode sheet can be prepared by gravure coating. Specifically, a capacity compensation layer and a positive electrode active material layer are formed on the positive electrode current collector by gravure coating.

[0081] According to some other embodiments of this application, a capacity compensation layer and a positive electrode active material layer can be formed simultaneously through a double-layer coating die.

[0082] According to some other embodiments of this application, the positive electrode active material layer and the capacity compensation layer can be formed by multiple coatings.

[0083] As an example, the positive electrode current collector 1100 may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0084] According to some embodiments of this application, the capacity compensator 130 includes a lithium supplement and / or a sodium supplement, wherein the lithium supplement includes Li₂C₂O₄, Li₂M₁O₂, Li₂M₂O₃, and Li₅Fe. x M 3(1-x) O4, Li6Mn y M 4(1-y) O4 or Li6Co y M 4(1-y)At least one of O4; wherein 0.5≤x≤1, 0.5≤y≤1, M1 includes at least one of Ni, Mn, Cu, Fe, Cr or Mo, M2 includes at least one of Ni, Mn, Fe, Mo, Zr, Si, Cu, Cr or Ru, M3 includes at least one of Al, Nb, Co, Mn, Ni, Mo, Ru or Cr, M4 includes at least one of Ni, Fe, Cu or Ru, and the sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2, NaCrO2, Na3P, Na3N, Na2NiO2, Na2CuO2, Na2FeO2 or NaF. Therefore, when the battery is a lithium-ion battery, the capacity compensator 130 can be a lithium replenishing agent, and the additive 120 can react with the residual alkali on the surface of the lithium replenishing agent to reduce the content of residual alkali on the surface of the lithium replenishing agent, improve the capacity compensation effect of the lithium replenishing agent, and improve the cycle capacity retention rate of the battery; when the battery is a sodium-ion battery, the capacity compensator 130 can be a sodium replenishing agent, and the additive 120 can react with the residual alkali on the surface of the sodium replenishing agent to reduce the content of residual alkali on the surface of the sodium replenishing agent, improve the capacity compensation effect of the sodium replenishing agent, and improve the cycle capacity retention rate of the battery.

[0085] According to some embodiments of this application, the capacity compensation layer 1300 may further include at least one of an adhesive and a conductive agent.

[0086] According to some embodiments of this application, based on the total mass of the capacity compensation layer 1300 and the positive electrode active material layer 1200, the mass percentage of the binder can be 0.8%-5%, for example, it can be 0.8%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, or any range of the above values. This improves the adhesion between the capacity compensation layer 1300 and the positive electrode active material layer 1200, reducing the risk of film detachment. According to some specific embodiments of this application, based on the total mass of the capacity compensation layer 1300, the mass percentage of the binder can be 0.8%-2.2%.

[0087] According to some embodiments of this application, the adhesive may include at least one of polypropylene, polyethylene, polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, or polyhexafluoropropylene. This improves the adhesion between the capacity compensation layer 1300 and the positive electrode active material layer 1200, reducing the risk of film detachment.

[0088] According to some embodiments of this application, based on the total mass of the capacity compensation layer 1300 and the positive electrode active material layer 1200, the mass percentage of the conductive agent can be 0.3%-10%.

[0089] According to some embodiments of this application, the conductive agent may include at least one of superconducting carbon, carbon nanotubes, graphite, nanofibers, or graphene. Therefore, the conductive agents of the above types can improve the electronic conductivity of the capacity compensator 130, reduce the decomposition potential of the capacity compensator 130, improve the compensation effect of active ions, and improve the cycle capacity retention rate of the battery.

[0090] When the battery is a lithium-ion battery, as an example, the positive electrode active material can be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries 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, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0091] When the battery is a sodium-ion battery, as an example, the positive electrode active material may include, but is not limited to, at least one of layered transition metal oxides, polyanionic compounds, and Prussian blue analogues.

[0092] Examples of the aforementioned layered transition metal oxides include:

[0093] Na 1-x Cu h Fe k Mn l M 1 m O 2-y M 1 It is one or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0094] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 It is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, 0 <z≤0.1;

[0095] Na a Li b Ni c Mn d Fe e O2, of which 0.67 <a≤1,0<b<0.2,0<c<0.3,0.67<d+e<0.8,b+c+d+e=1。

[0096] Examples of the aforementioned polyanionic compounds include:

[0097] A 1 f M 3 g (PO4) i O j X 1 3-j A 1 It is one or more of H, Li, Na, K and NH4, M 3 It is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu and Zn, X 1is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0098] Na n M 4 PO4X 2 , where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, and X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0099] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0100] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0101] As an example of the above Prussian blue analogs, for example, the following can be listed:

[0102] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + 、NH4 + 、an alkali metal cation, and an alkaline earth metal cation, M 6 and M 7 are each independently one or more of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A is H + 、Li + 、Na + 、K + 、NH4 + 、Rb + 、Cs + 、Fr + 、Be 2+ 、Mg 2+ 、Ca 2+ 、Sr 2+ 、Ba 2+ and Ra 2+ among one or more of them, M 6 and M 7Each is an independent cation of one or more transition metal elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W.

[0103] The modified compounds for the above materials can be used to modify the materials by doping and / or by surface coating.

[0104] In some embodiments, the positive electrode 1000 can be prepared by dispersing the components used to prepare the positive electrode 1000, such as the positive active material, capacity compensator 130, additive 120, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive current collector 1100, and after drying, cold pressing and other processes, the positive electrode 1000 can be obtained.

[0105] A second aspect of this application also provides a method for preparing a positive electrode sheet, comprising forming a capacity compensation layer on at least one side of a positive electrode active material layer, the capacity compensation layer comprising a capacity compensator and an additive.

[0106] According to some embodiments of this application, reference is made to Figure 3 When the carbon coating layer 110 coats at least a portion of the surface of the capacity compensator 130, and the additive 120 coats at least a portion of the surface of the carbon coating layer 110, the capacity compensator 130 can be prepared by mixing the capacity compensator 130 and the carbon coating layer 110 evenly in water, spray drying, and then calcining under an inert atmosphere to obtain the capacity compensator 130 coated by the carbon coating layer 110. Then, the capacity compensator 130 coated by the carbon coating layer 110 and the additive 120 are ground and mixed evenly and placed in a reaction vessel. The heating temperature can be 140℃-160℃, and the heating time can be 20h-30h, so that the capacity compensator 130 with the additive 120 coated on at least a portion of the surface of the carbon coating layer 110 and the carbon coating layer 110 coated on at least a portion of the surface of the capacity compensator 130 can be obtained. According to some specific embodiments of this application, the heating temperature can be 140℃, 145℃, 150℃, 155℃, or 160℃, or a range of any of the above values. According to some specific embodiments of this application, the heating time can be 20h, 22h, 24h, 26h, 28h, or 30h, or a range of any of the above values.

[0107] According to some embodiments of this application, reference is made to Figure 4When the additive 120 coats at least a portion of the surface of the capacity compensator 130, and the carbon coating layer 110 coats at least a portion of the surface of the additive 120, the capacity compensator 130 can be prepared by grinding and mixing the capacity compensator 130 and the additive 120 evenly, placing them in a reaction vessel, heating at a temperature of 140℃-160℃ for 20-30 hours, and then ball milling with the carbon coating layer 110 to obtain the capacity compensator 130 in which the additive 120 coats at least a portion of the surface of the capacity compensator 130, and the carbon coating layer 110 coats at least a portion of the surface of the additive 120. According to some specific embodiments of this application, the heating temperature can be 140℃, 145℃, 150℃, 155℃, or 160℃, or any range of the above values. According to some specific embodiments of this application, the heating time can be 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, or 30 hours, or any range of the above values.

[0108] According to some embodiments of this application, reference is made to Figure 5 When the carbon coating layer 110 covers a portion of the surface of the capacity compensator 130, and the additive 120 covers the portion of the capacity compensator 130 not covered by the carbon coating layer 110, the capacity compensator 130 can be prepared by ball milling the capacity compensator 130 coated with the carbon coating layer 110 and the additive 120, then placing them in a reaction vessel and heating them at a temperature of 140℃-200℃ for 6h-15h to obtain a capacity compensator 130 with a surface coated with the carbon coating layer 110 and the additive 120. According to some specific embodiments of this application, the heating temperature can be 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃, or any range of the above values. According to some specific embodiments of this application, the heating time can be 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or 16h, or a range of any of the above values.

[0109] A third aspect of this application provides a battery comprising the positive electrode 1000 provided in the first aspect of this application or a positive electrode prepared by the method provided in the second aspect of this application. This improves the cycle capacity rate of the battery and reduces the drain-rate-discharge (DCR) of the battery.

[0110] [Negative electrode plate]

[0111] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0112] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0113] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate 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 (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0114] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0115] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0116] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon (SuperP), acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0117] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0118] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0119] [Electrolytes]

[0120] The electrolyte acts as a conductor of ions between the positive electrode 1000 and the negative electrode. This application does not specify any particular type of electrolyte; it can be selected according to requirements.

[0121] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0122] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0123] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0124] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0125] [Isolation membrane]

[0126] In some embodiments, the battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0127] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0128] In some implementations, the positive electrode 1000, the negative electrode, and the separator can be fabricated into an electrode assembly using a winding process or a stacking process.

[0129] In some embodiments, the battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0130] In some implementations, the battery's outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The battery's outer packaging can also be a soft pack, such as a pouch. The soft pack can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0131] This application does not impose any particular limitation on the shape of the battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 8 This is a square-structured battery 1 used as an example.

[0132] In some embodiments, battery 1 may include an outer packaging. The outer packaging is used to encapsulate the positive electrode, the negative electrode, and the electrolyte.

[0133] In some implementations, reference Figure 9 The positive electrode, negative electrode, and separator can be manufactured into electrode assembly 12 by winding or stacking processes.

[0134] In some implementations, reference Figure 9 The outer packaging may include a shell 11 and a cover plate 13. The shell 11 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The shell 11 has an opening communicating with the receiving cavity, and the cover plate 13 can be placed on the opening to close the receiving cavity.

[0135] In some embodiments, the outer packaging of battery 1 can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0136] The outer packaging of battery 1 can also be a soft package, such as a pouch. The material of the soft package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0137] In some implementations, the battery 1 can be assembled into a battery module 2, and the battery module 2 can contain multiple batteries 1, the specific number of which can be adjusted according to the application and capacity of the battery module 2.

[0138] In some embodiments, the outer packaging of battery 1 may include a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0139] Figure 10 This is battery module 2 as an example. (See reference...) Figure 10 In battery module 2, multiple batteries 1 can be arranged sequentially along the length of battery module 2. Of course, they can also be arranged in any other way. Furthermore, these multiple batteries 1 can be fixed in place using fasteners.

[0140] The battery module 2 may also include a housing with a receiving space in which multiple batteries 1 are housed. In some embodiments, the battery modules may also be assembled into a battery pack, the number of battery modules contained in the battery pack being adjustable according to the application and capacity of the battery pack.

[0141] Figure 11 and Figure 12 This is battery pack 3 as an example. (See reference...) Figure 11 and 12 The battery pack 3 may include a battery box and multiple battery modules 2 disposed within the battery box. The battery box includes an upper box 31 and a lower box 32, with the upper box 31 covering the lower box 32 to form a closed space for accommodating the battery modules 2. The multiple battery modules 2 can be arranged in any manner within the battery box.

[0142] The fourth aspect of this application provides an electrical device that includes the battery provided in the third aspect of this application. This improves the energy density and cycle life of the electrical device.

[0143] As an example, a battery can be used as a power source for an electrical device or as an energy storage unit for that device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0144] As for the electrical equipment, the battery can be selected according to its usage requirements.

[0145] Figure 13 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density batteries, a battery pack or battery module can be used.

[0146] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a battery as their power source.

[0147] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0148] Example 1

[0149] 1. Preparation of positive electrode sheet

[0150] LiFePO4 (LFP), conductive agent Super P, and binder polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone (NMP) solvent at a weight ratio of 96:2:2 to obtain the first slurry.

[0151] The capacity compensator Li5FeO4 / C and sulfur were ball-milled at a mass ratio of 1:0.4. After ball milling, the mixture was placed in a reactor and reacted at 155°C for 12 hours. Li5FeO4, PVDF, Super P, and LFP, coated with carbon and sulfur, were then thoroughly mixed in NMP at a weight ratio of 35:2:2:61 to obtain a second slurry. The carbon content was 4% based on the total mass of the capacity compensator Li5FeO4 / C. The first and second slurries were coated onto a positive electrode current collector and cold-pressed to obtain the positive electrode sheet. The positive electrode active material layer was located on the surface of the positive electrode current collector, and its mass was 20.384 g / cm³. 2 The capacity compensation layer is located on the surface of the positive electrode active material layer away from the positive electrode current collector, and the mass of the capacity compensation layer is 0.416 g / cm³. 2 .

[0152] 2. Preparation of negative electrode sheet

[0153] The active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC-Na) are mixed thoroughly in deionized water at a weight ratio of 96.5:0.7:1.8:1. The mixture is then coated onto copper foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0154] 3. Preparation of electrolyte

[0155] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), ethylene carbonate and methyl ethyl carbonate were mixed at a mass ratio of 30:70 to obtain an organic solvent. The fully dried electrolyte salt LiPF6 was dissolved in the above solvent and mixed evenly to obtain an electrolyte with a concentration of 1 mol / L.

[0156] 4. Separating membrane

[0157] Polypropylene film is used as the separator.

[0158] 5. Battery manufacturing

[0159] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. The electrode assembly is then wound up. The electrode assembly is placed in an outer package, and the prepared electrolyte is injected into the dried lithium-ion battery. After vacuum sealing, settling, formation, and shaping, the lithium-ion battery is obtained.

[0160] The preparation methods of the batteries in Examples 2-17 and Comparative Example 1 are the same as those in Example 1, with the differences detailed in Table 1.

[0161] The difference between Examples 2-11 and Example 1 is that the mass ratio of capacity compensator Li5FeO4 / C to additive sulfur, as well as the mass of the positive electrode active material layer and the mass of the capacity compensation layer, are adjusted accordingly. The rest are the same as in Example 1.

[0162] The difference between Examples 12-15 and Example 3 is that the weight ratio of each substance in the first slurry and the second slurry is adjusted accordingly, while the rest is the same as in Example 3. In Example 12, the weight ratio of LFP, Super P, and PVDF in the first slurry was 97.9:0.1:2, and the weight ratio of carbon- and sulfur-coated Li5FeO4, PVDF, Super P, and LFP in the second slurry was 35:0.1:2:62.9; in Example 13, the weight ratio of LFP, Super P, and PVDF in the first slurry was 97.7:0.3:2, and the weight ratio of carbon- and sulfur-coated Li5FeO4, PVDF, Super P, and LFP in the second slurry was 35:0.3:2:62.7; in Example 14, the weight ratio of LFP, Super P, and PVDF in the first slurry was 97.3:0.7:2, and the weight ratio of carbon- and sulfur-coated Li5FeO4, PVDF, Super P, and LFP in the second slurry was 35:0.7:2:62.3; in Example 15, the weight ratio of LFP, Super P ... Super P, and LFP in the first slurry was 97.9:0.1:2, and the weight ratio of carbon- and sulfur-coated Li5FeO4, PVDF, Super P, and LFP in the second slurry was 35:0.7:2:62.3; in Example 15, the weight ratio of LFP, Super P, Super P, Super P, Super P, Super P, and LFP in the first slurry was 97.9:0.1 The weight ratio of P to PVDF is 88:10:2. The second slurry contains Li5FeO4 coated with carbon and sulfur, PVDF, Super P and LFP in a weight ratio of 35:10:2:53.

[0163] The preparation method of the battery in Comparative Example 1 is the same as that in Example 1, except that: LFP, Super P, PVDF, Li5FeO4 / C and additive sulfur are thoroughly mixed in NMP solvent at a weight ratio of 90.8:2:2:5:0.2, coated on aluminum foil, and cold-pressed to obtain a positive electrode active material layer containing positive electrode active material, additive and capacity compensator.

[0164]

[0165]

[0166] Performance testing

[0167] 1. DCR test

[0168] Maintain an ambient temperature of 25℃, charge and discharge at a rate of 0.33C for 3 cycles, with a cutoff voltage of 2.5V to 3.65V. Take the discharge capacity of the 3rd cycle as the standard capacity C0. Then charge at 0.33C0 to 50% C0 (50% SOC), let stand for 30 minutes, and then discharge at a current of I = 4C0 for 30 seconds. Record the voltage difference ΔU before and after the 4C0 discharge. DCR = ΔU / I.

[0169] 2. Cyclic capacity retention test method

[0170] (1) At 45℃, the lithium-ion battery was charged at a constant current of 1 / 3C to 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C, left to stand for 5 minutes, and then discharged at 1 / 3C to 2.5V. The discharge capacity C0 was recorded. (2) The lithium-ion battery was then charged at a constant current of 1.0C to 3.65V, left to stand for 5 minutes, and then discharged at 1 / 3C to 2.5V. The discharge capacity C1 was recorded. Step (2) was repeated 200 times. The discharge capacity C of the lithium-ion battery after the 200th cycle was recorded. 200 Capacity retention rate P 200 =C 200 / C0×100%.

[0171] The test results of the batteries in Examples 1-17 and Comparative Example 1 are shown in Table 2.

[0172] Table 2

[0173]

[0174] Conclusion: The cycle capacity retention rates of the batteries in Examples 1-17 were all higher than those in Comparative Example 1, indicating that the battery proposed in this application can improve the capacity compensation effect of the capacity compensator by placing the capacity compensator and the additive in the same layer, thereby improving the cycle capacity retention rate of the battery.

[0175] As can be seen from Examples 1-5, by adjusting the content of capacity compensator, the battery cycle capacity retention rate can be improved and the battery DCR can be reduced, thereby improving the overall performance of the battery.

[0176] As can be seen from Examples 6-11, by adjusting the content of additives, the battery cycle capacity retention rate can be improved and the battery DCR can be reduced, thereby improving the overall performance of the battery.

[0177] As can be seen from Examples 1-11, by adjusting the ratio of the additive content to the positive electrode active material content, the cycle capacity retention rate of the battery can be improved, the DCR of the battery can be reduced, and the overall performance of the battery can be improved.

[0178] As can be seen from Examples 12-15, by adjusting the content of conductive agent in the capacity compensation layer, the cycle capacity retention rate of the battery can be improved, the DCR of the battery can be reduced, and the overall performance of the battery can be improved.

[0179] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A positive electrode plate, characterized in that, include: A positive electrode active material layer, wherein the positive electrode active material layer comprises a positive electrode active material; A capacity compensation layer is disposed on at least one side of the positive electrode active material layer. The capacity compensation layer includes a capacity compensator and an additive. The additive includes at least one of elemental selenium, selenide, phosphide, elemental tellurium, and elemental iodine. The phosphide includes at least one of lithium phosphide or sodium phosphide; The selenide includes at least one of lithium selenide or sodium selenide; The additive is coated on at least a portion of the surface of the capacity compensator.

2. The positive electrode sheet according to claim 1, characterized in that, Based on the total mass of the capacity compensation layer and the positive electrode active material layer, the mass ratio of the capacity compensator is a1, the mass ratio of the additive is a2, and the condition 0.01≤a2 / a1≤0.45 is met.

3. The positive electrode sheet according to claim 2, characterized in that, 0.5%≤a1≤12%。 4. The positive electrode sheet according to claim 3, characterized in that, 1%≤a1≤10%。 5. The positive electrode sheet according to claim 2, characterized in that, 0.05%≤a2≤2%。 6. The positive electrode sheet according to claim 5, characterized in that, 0.1%≤a2≤0.5%。 7. The positive electrode sheet according to any one of claims 2-6, characterized in that, Based on the total mass of the positive electrode active material layer and the capacity compensation layer, the mass ratio of the positive electrode active material is 80%-96%.

8. The positive electrode sheet according to any one of claims 1-6, characterized in that, At least a portion of the surface of the capacity compensator is covered with a carbon coating.

9. The positive electrode sheet according to claim 8, characterized in that, Based on the total mass of the capacity compensator, the mass percentage of the carbon coating layer is 0.5%-10%.

10. The positive electrode sheet according to any one of claims 1-6, characterized in that, The capacity compensation layer also includes the positive electrode active material.

11. The positive electrode sheet according to any one of claims 1-6, characterized in that, The capacity compensator includes a lithium supplement and / or a sodium supplement, wherein the lithium supplement includes Li₂C₂O₄, Li₂M₁O₂, Li₂M₂O₃, and Li₅Fe. x M 3(1-x) O4, Li6Mn y M 4（1-y） O4 or Li6Co y M 4(1-y) At least one of O4; wherein 0.5≤x≤1, 0.5≤y≤1, M1 includes at least one of Ni, Mn, Cu, Fe, Cr or Mo, M2 includes at least one of Ni, Mn, Fe, Mo, Zr, Si, Cu, Cr or Ru, M3 includes at least one of Al, Nb, Co, Mn, Ni, Mo, Ru or Cr, M4 includes at least one of Ni, Fe, Cu or Ru, and the sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2, NaCrO2, Na3P, Na3N, Na2NiO2, Na2CuO2, Na2FeO2 or NaF.

12. A method for preparing a positive electrode sheet, characterized in that, include: A capacity compensation layer is formed on at least one side of the positive electrode active material layer. The capacity compensation layer includes a capacity compensator and an additive. The additive includes at least one of elemental selenium, selenide, phosphide, elemental tellurium, and elemental iodine. The phosphide includes at least one of lithium phosphide or sodium phosphide; The selenide includes at least one of lithium selenide or sodium selenide; The additive is coated on at least a portion of the surface of the capacity compensator.

13. A battery, characterized in that, The positive electrode sheet includes any one of claims 1-11 or the positive electrode sheet prepared by the method of claim 12.

14. An electrical appliance, characterized in that, Includes the battery as described in claim 13.

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