Capacity compensation additive and preparation method therefor, positive electrode sheet, battery, and electric device

Abstract

A capacity compensation additive and a preparation method therefor, a positive electrode sheet, a battery, and an electric device. The capacity compensation additive comprises a capacity compensation agent and a carbon material containing a catalyst, and the carbon material containing a catalyst coats at least part of the surface of the capacity compensation agent.

Description

Capacity compensation additive and preparation method thereof, positive electrode sheet, battery and electrical device

[0001] Priority information

[0002] This application requests priority to the Chinese patent application with patent application number 202311608084.2, entitled “Capacity Compensating Additive and Preparation Method thereof, Positive Electrode Sheet, Battery and Electrical Device”, filed with the State Intellectual Property Office of China on November 27, 2023, and all the contents of which are incorporated by reference into this application. Technical Field

[0003] The present application belongs to the field of batteries, and specifically relates to a capacity compensation additive and a preparation method thereof, a positive electrode sheet, a battery and an electrical device. Background Art

[0004] In recent years, as battery applications have become increasingly widespread, they are widely used in energy storage systems such as hydropower, thermal, wind, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. During the battery formation process, the formation of the SEI film (solid electrolyte interface) on the negative electrode surface consumes a large amount of active ions, resulting in reduced initial charge and discharge efficiency and severe irreversible capacity loss.

[0005] To address the problems of low initial charge and discharge efficiency and severe irreversible capacity loss during battery development, positive electrode capacity compensation is an effective solution. However, existing capacity compensators have poor conductivity and require a high decomposition voltage to release active ions. At high voltages, electrolyte side reactions are prone to occur, and the structure of the positive electrode active material undergoes irreversible changes, affecting battery capacity and cycle performance.

[0006] Summary of the Invention

[0007] In view of the technical problems existing in the background technology, the present application provides a capacity compensation additive, aiming to improve the capacity and cycle performance of the battery containing the same.

[0008] In order to achieve the above objectives, the first aspect of the present application proposes a capacity compensating additive, comprising a capacity compensating agent and a catalyst-containing carbon material, wherein the catalyst-containing carbon material is coated on at least a portion of the surface of the capacity compensating agent.

[0009] The present application includes at least the following beneficial effects: the capacity compensation additive of the present application adopts a catalyst-containing carbon material, and the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensator, that is, the catalyst and the capacity compensator are not easy to fall off, which is beneficial to the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, increase the capacity of the battery, and avoid the side reaction of the electrolyte at high voltage and the irreversible change of the structure of the positive electrode active material, thereby improving the battery cycle performance.

[0010] In some embodiments, the catalyst-containing carbon material comprises a carbon support and a catalyst, wherein the catalyst is supported on at least a portion of the carbon support, and the catalyst comprises M x Q y , 1≤x≤6, 1≤y≤3, M includes at least one of Ni, Co, Mn, Fe, Cu, Ti, Nb, Mg or Cr, and Q includes at least one of O, N, S or P. Thus, the capacity and cycle performance of the battery containing the same can be improved.

[0011] In some embodiments, M includes at least one of Ni, Co, or Fe, and Q includes O and / or N. Thus, the capacity and cycle performance of a battery containing the same can be improved.

[0012] In some embodiments, the catalyst accounts for 5% to 20% by mass based on the total mass of the catalyst-containing carbon material, thereby improving the capacity and cycle performance of the battery containing the catalyst.

[0013] In some embodiments, the mass proportion of the catalyst is 5%-15% based on the total mass of the catalyst-containing carbon material, thereby improving the capacity and cycle performance of the battery containing the catalyst.

[0014] In some embodiments, the particle size of the catalyst is 300 nm to 1 μm, thereby improving the catalytic effect on the decomposition of the capacity compensating agent.

[0015] In some embodiments, the particle size of the catalyst is 500 nm to 800 nm, thereby improving the catalytic effect on the decomposition of the capacity compensating agent.

[0016] In some embodiments, the mass of the catalyst-containing carbon material accounts for 1% to 20% of the total mass of the capacity compensation additive, thereby improving the cycle performance of the battery containing the catalyst.

[0017] In some embodiments, the mass of the catalyst-containing carbon material accounts for 5% to 10% of the total mass of the capacity compensation additive, thereby improving the cycle performance of the battery containing the catalyst.

[0018] In some embodiments, the capacity compensator comprises A a C b O c , the A includes Na and / or Li, 2≤a≤4, 1≤b≤6, and 3≤c≤6. This is beneficial for improving the energy density of the battery without deteriorating the power performance of the battery.

[0019] In some embodiments, the capacity compensator includes a lithium supplement, and the lithium supplement includes at least one of Li2CO3, Li2C2O4, Li2C4O4, Li2C4O6, or Li2C3O5. This is beneficial for improving the energy density of the battery without deteriorating the power performance of the battery.

[0020] In some embodiments, the lithium supplement includes at least one of Li2CO3, Li2C2O4, or Li2C4O4, thereby improving the energy density of the battery without deteriorating the power performance of the battery.

[0021] In some embodiments, the capacity compensator includes a sodium supplement, and the sodium supplement includes at least one of Na2CO3, Na2C2O4, Na2C4O4, Na2C6O6, or Na4C6O6. This is beneficial for improving the energy density of the battery without deteriorating the power performance of the battery.

[0022] In some embodiments, the sodium supplement includes at least one of Na2C2O4 or Na2C4O4, thereby improving the energy density of the battery without deteriorating the power performance of the battery.

[0023] In some embodiments, the volume average particle size Dv50 of the capacity compensation additive is 1 μm to 20 μm, thereby improving the capacity and cycle performance of the battery containing the capacity compensation additive.

[0024] In some embodiments, the volume average particle size Dv50 of the capacity compensation additive is 1 μm to 10 μm, thereby improving the capacity and cycle performance of the battery containing the capacity compensation additive.

[0025] In some embodiments, the powder resistivity of the capacity compensating additive is less than or equal to 5Ω·cm at 20 MPa, thereby improving the capacity and cycle performance of a battery containing the additive.

[0026] In some embodiments, the powder resistivity of the capacity compensating additive is less than or equal to 1 Ω·cm at 20 MPa, thereby improving the capacity and cycle performance of a battery containing the capacity compensating additive.

[0027] In some embodiments, the decomposition voltage of the capacity compensation additive is lower than or equal to 4.5 V. Thus, the capacity and cycle performance of the battery containing the capacity compensation additive can be improved.

[0028] In some embodiments, the decomposition voltage of the capacity compensation additive is lower than or equal to 4.3 V. Thus, the capacity and cycle performance of the battery containing the capacity compensation additive can be improved.

[0029] In a second aspect of the present application, a method for preparing a capacity compensation additive is proposed, comprising: coating a catalyst-containing carbon material on at least a portion of the surface of the capacity compensation agent to obtain the capacity compensation additive.

[0030] Therefore, the capacity compensation additive prepared in the present application includes a carbon material containing a catalyst, and the carbon material containing the catalyst is coated on at least part of the surface of the capacity compensator, that is, the catalyst and the capacity compensator are not easy to fall off, which is beneficial to the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, increase the capacity of the battery, and avoid the side reactions of the electrolyte at high voltage and irreversible changes and side reactions in the structure of the positive electrode active material, thereby improving the battery cycle performance.

[0031] In some embodiments, coating the catalyst-containing carbon material on at least a portion of the surface of the capacity compensating agent is performed by spray-drying a slurry comprising the catalyst-containing carbon material and the capacity compensating agent, thereby coating at least a portion of the surface of the capacity compensating agent with the catalyst-containing carbon material. This can improve the capacity and cycle performance of batteries containing the catalyst-containing carbon material.

[0032] In some embodiments, the spray drying process includes at least one of the following conditions: a concentration of the slurry comprising the capacity compensating agent and the catalyst-containing carbon material of 20 g / L-50 g / L, optionally 20 g / L-30 g / L; an air inlet temperature of 120°C-150°C; and an air outlet temperature of 80°C-100°C. This can improve the capacity and cycle performance of batteries containing the spray drying process.

[0033] In some embodiments, coating the catalyst-containing carbon material on at least a portion of the surface of the capacity compensating agent is performed by electrospinning a slurry comprising the catalyst-containing carbon material and the capacity compensating agent, thereby coating the catalyst-containing carbon material on at least a portion of the surface of the capacity compensating agent. This can improve the capacity and cycle performance of batteries containing the catalyst-containing carbon material.

[0034] In some embodiments, the electrospinning process includes at least one of the following conditions: a concentration of the slurry comprising a capacity compensating agent and a catalyst-containing carbon material of 5 g / L to 20 g / L; a spinneret speed of 0.3 mL / h to 1 mL / h; a voltage between the spinneret and the receiver of 15 kV to 18 kV; and a distance between the spinneret and the receiver of 12 cm to 20 cm. This can improve the capacity and cycle performance of batteries containing the same.

[0035] In a third aspect of the present application, a positive electrode plate is provided, comprising the capacity compensation additive described in the first aspect or the capacity compensation additive obtained by the method described in the second aspect, thereby improving the capacity and cycle performance of a battery containing the positive electrode plate.

[0036] In some embodiments, the positive electrode sheet includes a positive electrode active material layer, and the positive electrode active material layer includes the capacity compensation additive, thereby improving the capacity and cycle performance of a battery containing the positive electrode sheet.

[0037] In some embodiments, the capacity compensation additive accounts for 1% to 20% of the total mass of the positive electrode active material layer, thereby improving the capacity and cycle performance of the battery containing the capacity compensation additive.

[0038] In some embodiments, the capacity compensation additive accounts for 1% to 5% of the total mass of the positive electrode active material layer, thereby improving the capacity and cycle performance of the battery containing the capacity compensation additive.

[0039] In a fourth aspect of the present application, the present application provides a battery comprising the positive electrode sheet described in the third aspect, thereby having a higher capacity and cycle performance.

[0040] In a fifth aspect of the present application, the present application provides an electrical device comprising the battery according to the fourth aspect, so that the electrical device has an excellent service life.

[0041] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0043] FIG1 is a schematic diagram of a battery according to one embodiment of the present application.

[0044] FIG. 2 is an exploded view of the battery according to one embodiment of the present application shown in FIG. 1 .

[0045] FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0046] FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0047] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.

[0048] FIG6 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0049] FIG7 is a comparison diagram of the cycle curves of Example 1, Comparative Example 1 and Comparative Example 6.

[0050] FIG8 is a SEM image of the capacity compensation additive obtained in Example 1.

[0051] FIG9 is a distribution diagram of the Ni element in the EDS spectrum of the capacity compensation additive obtained in Example 1.

[0052] Explanation of reference numerals: 1 battery cell; 11 housing; 12 electrode assembly; 13 cover plate; 2 battery module; 3 battery pack; 31 upper case; 32 lower case. DETAILED DESCRIPTION

[0053] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0054] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0055] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0056] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0057] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0058] Unless otherwise specified, all steps of the present 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 may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0059] Currently, market developments indicate that secondary batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As the application of secondary batteries continues to expand, market demand is also growing.

[0060] During the formation process of secondary batteries, the formation of the SEI film (solid electrolyte interface) on the negative electrode surface consumes a large amount of active ions, resulting in reduced charge and discharge efficiency of the battery in the first cycle and serious irreversible capacity loss.

[0061] In order to solve the problems of low initial charge and discharge efficiency and serious irreversible capacity loss of the battery, capacity compensation of the positive electrode sheet is an effective solution. Lithium sheet is usually used to replenish the negative electrode sheet. Lithium sheet itself is very active in the electrolyte and easily reacts with the electrolyte, resulting in low lithium replenishment efficiency. In addition, when lithium dendrites are generated on the surface of the negative electrode, the SEI film will continue to rupture and reconstruct, continuously consuming lithium, thereby reducing the cycle life of the battery. Lithium-rich additives or lithiated active materials are usually added to the positive electrode sheet as lithium replenishers. This type of lithium replenisher has a high decomposition potential and requires high voltage to decompose. However, high voltage will destroy the structure of the positive electrode active material. At the same time, high voltage will cause the electrolyte to oxidize and decompose, and the side reactions will increase, thereby reducing the cycle performance of the battery and not being conducive to the battery capacity.

[0062] The capacity compensation additive of the present application has a lower decomposition voltage, so that the capacity compensator can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, thereby increasing the capacity of the battery and avoiding side reactions of the electrolyte at high voltage and irreversible changes and side reactions in the structure of the positive electrode active material, thereby improving the battery cycle performance.

[0063] The capacity compensation additive disclosed in the embodiments of the present application is applicable to lithium-ion batteries and sodium-ion batteries, and the battery disclosed in the embodiments of the present application can be used in electrical equipment that uses batteries as power sources or various energy storage systems that use batteries as energy storage elements. Electrical equipment may include, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, battery cars, electric cars, ships, spacecraft, and the like. Among them, electric toys may include fixed or mobile electric toys, for example, game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0064] In a first aspect, the present application proposes a capacity compensating additive, which includes a capacity compensating agent and a catalyst-containing carbon material, wherein the catalyst-containing carbon material is coated on at least a portion of the surface of the capacity compensating agent.

[0065] The capacity compensation additive of the present application uses a catalyst-containing carbon material, and the catalyst-containing carbon material is coated on at least part of the surface of the capacity compensation agent, that is, the catalyst and the capacity compensation agent are not easy to fall off, which is conducive to the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensation agent, thereby reducing the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, increase the capacity of the battery, and avoid the side reaction of the electrolyte at high voltage and the irreversible change of the structure of the positive electrode active material, thereby improving the battery cycle performance. In addition, when the capacity compensation agent in the capacity compensation additive is consumed, the catalyst-containing carbon material can still play a supporting role and will not cause changes in the electrode structure.

[0066] In some embodiments of the present application, the catalyst-containing carbon material comprises a carbon support and a catalyst, wherein the catalyst is supported on at least a portion of the carbon support, and the catalyst comprises M x Q y , 1≤x≤6, 1≤y≤3, M may include at least one of Ni, Co, Mn, Fe, Cu, Ti, Nb, Mg or Cr, and Q may include at least one of O, N, S or P. Thus, by loading the metal compound on the carbon material, not only can the agglomeration of the catalyst be reduced, which is beneficial to the catalytic performance of the catalyst, but also the conductivity of the catalyst can be significantly improved, thereby reducing the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, thereby increasing the capacity of the battery, and avoiding the side reactions of the electrolyte at high voltage and the irreversible changes and side reactions in the structure of the positive electrode active material, thereby improving the battery cycle performance. In other embodiments of the present application, the M x Q y Wherein, M may include at least one of Ni, Co or Fe, and Q may include O and / or N.

[0067] As an example, the M x Q y The MnO may include at least one of NiO, Ni3N2, NiS, Ni2P, CoO, CoN, CoS, CoP, MnO2, MnN, MnS, Mn3P2, Fe2O3, Fe6N2, Fe2S3, Fe3P, CuO, Cu3N, CuS, Cu3P2, TiO2, TiN, TiS3, TiP, Nb2O5, NbN, NbS2, NbP, MgO, Mg3N2, MgS, Mg3P2, Cr2O3, CrN, Cr2S3 or Cr3P2. In other embodiments, the Mn x Q yIt may include at least one of NiO, Ni3N2, CoO, CoN, MnO2, MnN, Fe2O3 or Fe6N2.

[0068] As an example, the carbon support may include but is not limited to carbon nanotubes, graphene, carbon nanofibers, and the like.

[0069] In some embodiments of the present application, based on the total mass of the catalyst-containing carbon material, the mass proportion of the catalyst is 5%-20%, for example, 7%-18%, 10%-15%, 10%-12%, etc. Thus, by adopting the catalyst-containing carbon material of the above composition, the catalytic properties and electrical conductivity of the catalyst-containing carbon material can be improved, thereby reducing the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, thereby increasing the capacity of the battery, and avoiding the side reactions of the electrolyte at high voltage and the irreversible changes and side reactions of the positive electrode active material structure, thereby improving the battery cycle performance. In other embodiments of the present application, based on the total mass of the catalyst-containing carbon material, the mass proportion of the catalyst is 5%-15%.

[0070] In some embodiments of the present application, the particle size of the catalyst may be 300nm-1μm, such as 350nm-950nm, 400nm-900nm, 450nm-850nm, 500nm-800nm, 550nm-750nm, 600nm-700nm, 650nm-700nm, etc. Thus, the present application adopts a catalyst of this particle size, which is not only evenly distributed on the carbon support, but also has an excellent catalytic effect on the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, thereby increasing the capacity of the battery, and avoiding the side reactions of the electrolyte at high voltage and the irreversible changes and side reactions of the positive electrode active material structure, thereby improving the battery cycle performance. In other embodiments of the present application, the particle size of the catalyst may be 500nm-800nm.

[0071] In some embodiments of the present application, based on the total mass of the capacity compensation additive, the mass proportion of the catalyst-containing carbon material is 1%-20%, for example, 1%-18%, 3%-15%, 5%-12%, 7%-10%, etc. Thus, by adding the above-mentioned content of the catalyst-containing carbon material to the capacity compensation additive, the decomposition voltage of the capacity compensation additive can be reduced, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, thereby increasing the capacity of the battery and avoiding the side reactions of the electrolyte at high voltage and the irreversible changes and side reactions of the positive electrode active material structure, thereby improving the battery cycle performance. In other embodiments of the present application, based on the total mass of the capacity compensation additive, the mass proportion of the catalyst-containing carbon material is 5%-10%.

[0072] In some embodiments of the present application, the capacity compensator includes A a C b O c , the A includes Na and / or Li, 2≤a≤4, 1≤b≤6, 3≤c≤6. Therefore, the capacity compensator with this composition decomposes to release active ions and carbon oxide gas. The released active ions can compensate for the loss of active ions during the formation of the SEI film, and the carbon oxide gas can be discharged in the exhaust process. Therefore, the capacity compensator has no residue after decomposition, which is beneficial to improving the energy density of the battery, and does not increase the cell impedance, thereby not deteriorating the power performance of the battery.

[0073] In some embodiments of the present application, the capacity compensator includes a lithium supplement agent, and the lithium supplement agent includes at least one of Li2CO3, Li2C2O4, Li2C4O4, Li2C4O6 or Li2C3O5. Thus, the lithium supplement agent of this composition decomposes to release lithium ions and carbon oxide gas. The released lithium ions can compensate for the loss of lithium ions during the formation of the SEI film, and the carbon oxide gas can be discharged in the exhaust process. Therefore, the capacity compensator has no residue after decomposition, which is beneficial to improve the energy density of the battery and does not increase the impedance of the battery cell, thereby not deteriorating the power performance of the battery. In another embodiment of the present application, the lithium supplement agent includes at least one of Li2CO3, Li2C2O4 or Li2C4O4.

[0074] In some embodiments of the present application, the capacity compensator includes a sodium supplement, and the sodium supplement includes at least one of Na2CO3, Na2C2O4, Na2C4O4, Na2C6O6 or Na4C6O6. Thus, using a sodium supplement of this composition, it decomposes to release sodium ions and carbon oxide gas. The released sodium ions can compensate for the loss of sodium ions during the formation of the SEI film, and the carbon oxide gas can be discharged in the exhaust process. Therefore, the capacity compensator has no residue after decomposition, which is beneficial to improving the energy density of the battery and will not increase the impedance of the battery cell, thereby not deteriorating the power performance of the battery. In other embodiments of the present application, the sodium supplement includes at least one of Na2C2O4 or Na2C4O4.

[0075] In the present application, when the battery is a lithium ion battery, the capacity compensator is a lithium supplement; when the battery is a sodium ion battery, the capacity compensator is a sodium supplement.

[0076] In some embodiments of the present application, the volume average particle size Dv50 of the capacity compensation additive is 1 μm-20 μm, for example, 2 μm-18 μm, 5 μm-15 μm, 7 μm-12 μm, 8 μm-10 μm, etc. As a result, the diffusion path of the active ions in the capacity compensation additive of this particle size is suitable and easy to escape, thereby increasing the gram capacity of the capacity compensation additive and reducing the risk of agglomeration between particles, thereby improving the capacity and cycle performance of the battery. In other embodiments of the present application, the volume average particle size Dv50 of the capacity compensation additive is 1 μm-10 μm.

[0077] In this application, Dv50 refers to the particle size at which the cumulative volume distribution percentage reaches 50%, as measured, for example, using a laser particle size analyzer (Malvern Master Size 2000) in accordance with the standard GB / T 19077-2016 / ISO 13320:2009. The specific testing process is as follows: take an appropriate amount of the sample to be tested (the sample concentration is sufficient to ensure an 8%-12% light shielding), add 20ml of deionized water, and ultrasonicate for 5 minutes (53KHz / 120W) to ensure that the sample is completely dispersed. The sample is then measured according to the GB / T19077-2016 / ISO 13320:2009 standard.

[0078] In some embodiments of the present application, at 20 MPa, the powder resistivity of the capacity compensation additive is less than or equal to 5Ω·cm, for example, 0.1Ω·cm-5Ω·cm, 0.3Ω·cm-5Ω·cm, 0.5Ω·cm-5Ω·cm, 0.8Ω·cm-5Ω·cm, 1Ω·cm-5Ω·cm, 1.5Ω·cm-4.5Ω·cm, 2Ω·cm-4Ω·cm, 2.5Ω·cm-3.5Ω·cm, 3Ω·cm-3.5Ω·cm, etc. As a result, the capacity compensation additive of the present application has high conductivity, which can reduce the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, thereby increasing the capacity of the battery, and avoiding the side reactions of the electrolyte at high voltage and the irreversible changes and side reactions of the positive electrode active material structure, thereby improving the battery cycle performance. In other embodiments of the present application, the powder resistivity of the capacity compensating additive is less than or equal to 1 Ω·cm at 20 MPa, thereby improving the capacity and cycle performance of the battery containing the additive.

[0079] In this application, the powder resistivity test method can use the four-probe method or the two-probe method. The four-probe method includes: using four probes to measure the current and voltage on the powder sample, and calculating the resistivity based on the current and voltage. The two-probe method: using two probes to measure the current and voltage on the powder sample, and calculating the resistivity based on the current and voltage.

[0080] In some embodiments of the present application, the decomposition voltage of the capacity compensation additive is lower than or equal to 4.5V, for example, 3V-4.5V, 3.2V-4.2V, 3.5V-4V, 3.5V-3.8V, etc. As a result, the capacity compensation additive has a lower decomposition voltage, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, thereby increasing the capacity of the battery and avoiding the side reactions of the electrolyte at high voltage and the irreversible changes in the structure of the positive electrode active material, thereby improving the battery cycle performance. In other embodiments of the present application, the decomposition voltage of the capacity compensation additive is lower than or equal to 4.3V.

[0081] In this application, the decomposition voltage of the capacity-compensating additive refers to the voltage at which decomposition occurs during a voltammetry test or during charge-discharge cycling. The voltammetry method used for testing the decomposition voltage of the capacity-compensating additive in this application includes cyclic voltammetry or linear sweep voltammetry.

[0082] In a second aspect, the present application proposes a method for preparing a capacity compensation additive, comprising: coating a catalyst-containing carbon material on at least a portion of the surface of the capacity compensation agent to obtain the capacity compensation additive.

[0083] Thus, the capacity compensation additive prepared in the present application includes a carbon material containing a catalyst, and the carbon material containing the catalyst is coated on at least part of the surface of the capacity compensation agent, that is, the catalyst and the capacity compensation agent are not easy to fall off, which is beneficial to the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensation agent, thereby reducing the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, increase the capacity of the battery, and avoid the side reactions of the electrolyte at high voltage and the irreversible changes and side reactions of the positive electrode active material structure, thereby improving the battery cycle performance. In addition, when the capacity compensation agent in the capacity compensation additive is consumed, the carbon material containing the catalyst can still play a supporting role and will not cause changes in the electrode structure.

[0084] In some embodiments of the present application, the carbon material containing the catalyst is coated on at least a portion of the surface of the capacity compensator by the following method: a slurry comprising the carbon material containing the catalyst and the capacity compensator is spray-dried so that the carbon material containing the catalyst is coated on at least a portion of the surface of the capacity compensator. Thus, by adopting the spray drying process, the carbon material containing the catalyst can be tightly coated on the surface of the capacity compensator and is not easy to fall off, which is conducive to the catalytic performance of the catalyst, and the conductivity of the capacity compensator can be improved, thereby reducing the decomposition voltage of the capacity compensating additive, so that the capacity compensating additive can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions during the formation of the SEI film, thereby increasing the capacity of the battery, and avoiding the side reactions of the electrolyte at high voltage and the irreversible changes and side reactions of the positive electrode active material structure, thereby improving the battery cycle performance. In addition, after the capacity compensating additive in the capacity compensating additive is consumed, the carbon material containing the catalyst can still play a supporting role and will not cause changes in the electrode structure.

[0085] As an example, a catalyst-containing carbon material, a capacity compensator and a solvent are mixed and stirred evenly to obtain a slurry, and the slurry is spray-dried so that the catalyst-containing carbon material is coated on at least a portion of the surface of the capacity compensator to obtain a capacity compensating additive.

[0086] As an example, the solvent may include but is not limited to at least one of ethanol, deionized water, ethylene glycol, and the like.

[0087] In some embodiments of the present application, the concentration of the slurry comprising the capacity compensating agent and the catalyst-containing carbon material in the spray drying is 20 g / L-50 g / L, for example, 25 g / L-45 g / L, 30 g / L-40 g / L, 35 g / L-40 g / L, etc. In some embodiments of the present application, the concentration of the slurry comprising the capacity compensating agent and the catalyst-containing carbon material is 20 g / L-30 g / L.

[0088] In some embodiments of the present application, the air inlet temperature in the spray drying is 120°C-150°C, for example, 125°C-145°C, 130°C-140°C, 135°C-140°C, etc.; the air outlet temperature is 80°C-100°C, for example, 85°C-95°C, 85°C-90°C, etc.

[0089] In other embodiments of the present application, the carbon material containing the catalyst is coated on at least part of the surface of the capacity compensator by the following method: a slurry comprising the carbon material containing the catalyst and the capacity compensator is electrostatically spun so that the carbon material containing the catalyst is coated on at least part of the surface of the capacity compensator. Thus, by adopting the electrostatic spinning process, the carbon material containing the catalyst can be tightly coated on the surface of the capacity compensator, not easily falling off, which is conducive to the catalytic performance of the catalyst, and can improve the conductivity of the capacity compensator, thereby reducing the decomposition voltage of the capacity compensation additive, so that the capacity compensation additive can release active ions at a lower voltage, and the released active ions can compensate for the loss of active ions in the process of forming the SEI film, thereby improving the capacity of the battery, and avoiding the side reaction of the electrolyte at high voltage and the irreversible change and side reaction of the positive electrode active material structure, thereby improving the battery cycle performance. In addition, when the capacity compensation agent in the capacity compensation additive is consumed, the carbon material containing the catalyst can still play a supporting role and will not cause changes in the electrode structure.

[0090] As an example, a catalyst-containing carbon material, a capacity compensator and a solvent are mixed and stirred evenly to obtain a slurry, and the slurry is electrospun so that the catalyst-containing carbon material is coated on at least a portion of the surface of the capacity compensator to obtain a capacity compensating additive.

[0091] As an example, the solvent may include, but is not limited to, at least one of N,N-dimethylformamide (DMF), tetrahydrofuran, dichloromethane, and dimethyl sulfoxide (DMSO).

[0092] In some embodiments of the present application, the concentration of the slurry including the capacity compensator and the catalyst-containing carbon material in the electrospinning process is 5g / L-20g / L, for example, 7.5g / L-17.5g / L, 10g / L-15g / L, 10g / L-12.5g / L, etc.

[0093] In some embodiments of the present application, the pushing speed of the spinneret is 0.3 mL / h-1 mL / h, for example, 0.5 mL / h-0.8 mL / h, 0.6 mL / h-0.7 mL / h, etc.; the voltage between the spinneret and the receiver is 15 kV-18 kV, for example, 15 kV-17 kV, 15 kV-16 kV, etc.; the distance between the spinneret and the receiver is 12 cm-20 cm, for example, 12 cm-18 cm, 15 cm-17 cm, etc.

[0094] In the third aspect of the present application, the present application proposes a positive electrode plate, which includes the capacity compensation additive described in the first aspect or the capacity compensation additive obtained by the method described in the second aspect. Thus, by adding the capacity compensation additive to the positive electrode plate, the capacity compensation additive has a lower decomposition voltage and can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, thereby increasing the capacity of the battery and avoiding the side reactions of the electrolyte at high voltage and the irreversible changes in the structure of the positive electrode active material, thereby improving the battery cycle performance and power performance. In addition, after the capacity compensation agent in the capacity compensation additive is consumed, the catalyst-containing carbon material can still play a supporting role and will not cause changes in the structure of the positive electrode plate.

[0095] In some embodiments of the present application, the positive electrode plate includes a positive electrode active material layer, and the positive electrode active material layer includes the capacity compensation additive. Thus, by adding the above-mentioned capacity compensation additive to the positive electrode active material layer, the capacity compensation additive has a lower decomposition voltage and can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, thereby increasing the capacity of the battery and avoiding the side reactions of the electrolyte at high voltage and irreversible changes in the structure of the positive electrode active material, thereby improving the battery cycle performance and power performance. In addition, after the capacity compensator in the capacity compensation additive is consumed, the catalyst-containing carbon material can still play a supporting role and will not cause changes in the structure of the positive electrode plate.

[0096] In some embodiments of the present application, based on the total mass of the positive electrode active material layer, the mass proportion of the capacity compensation additive is 1%-20%, such as 3%-18%, 5%-15%, 7%-13%, 7%-10%, etc. Thus, by adding the above-mentioned content of the capacity compensation additive to the positive electrode active material layer, the capacity compensation additive has a lower decomposition voltage and can release active ions at a lower voltage. The released active ions can compensate for the loss of active ions in the process of forming the SEI film, thereby increasing the capacity of the battery and avoiding the side reactions of the electrolyte at high voltage and irreversible changes in the structure of the positive electrode active material, thereby improving the battery cycle performance and power performance. In other embodiments of the present application, based on the total mass of the positive electrode active material layer, the mass proportion of the capacity compensation additive is 1%-5%.

[0097] The positive electrode sheet includes a positive electrode current collector, and the positive electrode active material layer is provided on at least one side of the positive electrode current collector.

[0098] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0099] In some embodiments of the present application, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. 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.).

[0100] In some embodiments of the present application, the positive electrode active material layer may further include a positive electrode active material. The positive electrode active material may be a positive electrode active material for batteries known in the art.

[0101] As an example, when the positive electrode plate is used in a lithium-ion battery, the positive electrode active material may adopt a positive electrode active material for lithium-ion batteries that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials 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 may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) or at least one of its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, or a composite material of lithium iron manganese phosphate and carbon.

[0102] For example, when the positive electrode plate is used in a sodium ion battery, the positive electrode active material may be a positive electrode active material known in the art for use in sodium ion batteries. For example, the positive electrode active material may include, but is not limited to, at least one of a layered transition metal oxide, a polyanion compound, and a Prussian blue analog.

[0103] Examples of the layered transition metal oxides include:

[0104] Na 1-x Cu h Fe k Mn l M 1 m O 2-y , where M 1 Including at least one of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn or 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;

[0105] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 including at least one of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn or Ba, 0 <z≤0.1;

[0106] 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。

[0107] Examples of the polyanionic compound include:

[0108] A 1 f M 3 g (PO4) i O j X 1 3-j , where A 1 including at least one of H, Li, Na, K or NH4, M 3 Contains at least one of Ti, Cr, Mn, Fe, Co, Ni, V, Cu or Zn, X 1 is at least one of F, Cl or Br, 0 <f≤4,0<g≤2,1≤i≤3,0≤j≤2;

[0109] Na n M 4 PO4X2 , where M 4 includes at least one of Mn, Fe, Co, Ni, Cu or Zn, and X 2 is at least one of F, Cl or Br; 0 < n ≤ 2;

[0110] Na p M 5 q (SO4)3, where M 5 includes at least one of Mn, Fe, Co, Ni, Cu or Zn; 0 < p ≤ 2, 0 < q ≤ 2;

[0111] 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.

[0112] As an example of the above-mentioned Prussian blue analogues, for example, the following can be cited:

[0113] A u M 6 v [M 7 (CN)6] w ·xH2O, where A includes H + , NH4 + , at least one of alkali metal cations or alkaline earth metal cations, M 6 and M 7 each independently include at least one of transition metal cations; 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A includes H + , Li + , Na + , K + , NH4 + , Rb + , Cs + , Fr + , Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ or Ra 2+ , at least one of them, M 6 and M 7 each independently include at least cations among Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn or W.

[0114] The battery's charge and discharge processes are accompanied by the intercalation and deintercalation of Li or Na, and the molar content of Li or Na varies when the battery is discharged to different states. The molar content of Li or Na in the positive electrode materials listed in this application refers to the material's initial state, i.e., the state before the materials are added. When the positive electrode material is used in a battery system, the molar content of Li or Na will change after charge and discharge cycles.

[0115] In the list of positive electrode materials in this application, the molar content of oxygen is only a theoretical value. Lattice oxygen release will cause the molar content of oxygen to change, and the actual molar content of oxygen will fluctuate.

[0116] In some embodiments of the present application, the positive electrode active material layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, or a fluorine-containing acrylate resin.

[0117] In some embodiments of the present application, the positive electrode active material layer may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0118] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0119] The third aspect of the present application provides a battery, which includes the positive electrode sheet described in the second aspect of the present application. As a result, the battery of the present application has higher capacity and cycle performance.

[0120] In some embodiments of the present application, the battery further comprises a negative electrode plate, the negative electrode plate comprising a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material.

[0121] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0122] In some embodiments of the present application, 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 base layer and a metal layer formed on at least one surface of the polymer base material. 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 base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0123] In some embodiments of the present application, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. 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 include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites or silicon alloys. The tin-based material may include at least one of elemental tin, tin oxide compounds or tin alloys. However, the present application is not limited to these materials, and other traditional 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.

[0124] In some embodiments of the present application, the negative electrode active material layer may further optionally include a binder. The binder may include 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), or carboxymethyl chitosan (CMCS).

[0125] In some embodiments of the present application, the negative electrode active material layer may further include a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0126] In some embodiments of the present application, the negative electrode active material layer may optionally further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0127] In some embodiments of the present application, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0128] Typically, a battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0129] The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or solid.

[0130] In some embodiments of the present application, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0131] In some embodiments of the present application, when the battery is a lithium ion battery, the electrolyte salt may include 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 difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate or lithium tetrafluorooxalatophosphate.

[0132] In some embodiments of the present application, when the battery is a sodium ion battery, the electrolyte salt may include at least one of sodium hexafluorophosphate, sodium difluorooxalatoborate, sodium tetrafluoroborate, sodium bisoxalatoborate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethylsulfonate or sodium bis(trifluoromethylsulfonyl)imide.

[0133] In some embodiments of the present application, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl 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, cyclopentane, dimethyl sulfone, ethylene glycol dimethyl ether, methyl ethyl sulfone or diethyl sulfone.

[0134] In some embodiments of the present application, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0135] The present application has no particular limitation on the type of isolation membrane, and any known isolation membrane with a porous structure having good chemical stability and mechanical stability can be selected.

[0136] In some embodiments, the material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The separator may 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 may be the same or different, without particular limitation.

[0137] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0138] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0139] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the secondary battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0140] The present application has no particular limitation on the shape of the battery, which can be cylindrical, square, or any other shape. For example, FIG1 shows a battery cell 1 with a square structure as an example.

[0141] In some embodiments, referring to Figure 2, the outer packaging may include a shell 11 and a cover plate 13. The shell 11 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 11 has an opening connected to the receiving cavity, and the cover plate 13 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 12 through a winding process or a lamination process. The electrode assembly 12 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 12. The number of electrode assemblies 12 contained in the battery cell 1 can be one or more, and those skilled in the art can select according to specific actual needs.

[0142] In some embodiments, batteries may be assembled into a battery module. The number of batteries contained in the battery module may be one or more. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0143] Figure 3 shows an example battery module 2. Referring to Figure 3 , within the battery module 2, multiple battery cells 1 may be arranged sequentially along the length of the battery module 2. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 1 may be secured together using fasteners.

[0144] Optionally, the battery module 2 may further include a housing having an accommodation space, and the plurality of battery cells 1 are accommodated in the accommodation space.

[0145] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0146] Figures 4 and 5 illustrate an example battery pack 3. Referring to Figures 6 and 7 , the battery pack 3 may include a battery box and multiple battery modules 2 disposed within the box. The battery box comprises an upper case 31 and a lower case 32. The upper case 31 can be placed over the lower case 32 to form an enclosed space for accommodating the battery modules 2. The multiple battery modules 2 can be arranged in any manner within the battery box.

[0147] In addition, the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may 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 and satellites, energy storage systems, etc., but is not limited thereto.

[0148] As the electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0149] Figure 6 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery, a battery pack or battery module can be used.

[0150] Another example device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be light and thin, and may use a battery as a power source.

[0151] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0152] Example 1

[0153] 1. Preparation of positive electrode sheet

[0154] a. Preparation of capacity compensation additives

[0155] 1 g of nickel oxide (particle size 500 nm-800 μm) was weighed as a catalyst and placed in a quartz boat. The quartz boat was then placed in a chemical vapor deposition reactor. Nitrogen was introduced at a controlled flow rate of 500 sccm. The temperature was raised to 800° C., acetylene was introduced as a carbon source, and the reaction was allowed to proceed for 1 h. The reaction was then cooled to obtain carbon nanotubes containing the catalyst. Composition analysis by ICP (inductively coupled plasma mass spectrometry) revealed a nickel oxide content of 15 wt % in the carbon nanotubes containing the catalyst.

[0156] Lithium oxalate and carbon nanotubes containing a catalyst were weighed in a mass ratio of 9:1, mixed in water to a concentration of 20 g / L, stirred for 2 hours, and the feed rate of the spray dryer was controlled at 200 ml / h, the air inlet temperature was 120° C., and the air outlet temperature was 90° C. to obtain a capacity compensation additive.

[0157] b. Preparation of positive electrode sheet

[0158] The positive electrode active materials lithium iron phosphate, acetylene black, polyvinylidene fluoride and the above-mentioned capacity compensation additives are mixed evenly in an appropriate amount of solvent N-methylpyrrolidone (NMP) at a mass ratio of 90.25:3:2:4.75 to obtain a positive electrode slurry. The positive electrode slurry is coated on both sides of the positive electrode current collector aluminum foil. The negative electrode active material layer is formed on both sides of the positive electrode current collector through drying and cold pressing. The striping and cutting process are performed to obtain a positive electrode sheet.

[0159] 2. Preparation of negative electrode sheet

[0160] The negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) are mixed evenly in a proper amount of solvent deionized water at a mass ratio of 96:1:1.5:1.5 to obtain a negative electrode slurry. The negative electrode slurry is coated on both sides of the negative electrode current collector copper foil. A negative electrode active material layer is formed on both sides of the negative electrode current collector through drying and cold pressing. Finally, the negative electrode sheet is obtained through striping and cutting processes.

[0161] 3. Preparation of electrolyte

[0162] In an argon atmosphere glove box (H2O <0.1ppm, O2 <0.1ppm), ethylene carbonate and ethyl methyl carbonate were mixed in a mass ratio of 30:70 to obtain a solvent, and fully dried electrolyte salt LiPF6 was dissolved in the above solvent. After mixing evenly, an electrolyte solution with a concentration of 1 mol / L was obtained.

[0163] 4. Isolation film

[0164] Polypropylene film is used as the isolation film.

[0165] 5. Preparation of secondary batteries

[0166] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive and negative electrode sheets to serve as an isolation, and then wound to obtain an electrode assembly; the electrode assembly is placed in an outer package, and the prepared electrolyte is injected into the dried lithium-ion battery. After vacuum packaging, standing, formation, and shaping processes, a lithium-ion battery is obtained.

[0167] The preparation methods of the lithium-ion batteries of Examples 2-11, 14-22 and Comparative Examples 1-2 and 4 are the same as those of Example 1, except that the processes for preparing the positive electrode sheets are different, as shown in Table 1.

[0168] The preparation method of the lithium-ion battery in Example 12 is the same as that in Example 1, except that the method for preparing the carbon material containing the catalyst is different, specifically comprising: adding 0.75 g of NiO and 4.25 g of graphene to 200 ml of deionized water and stirring for 1 hour to mix them evenly, then transferring the mixture to a reactor and placing it in a homogeneous reactor, maintaining it at 180°C for 15 hours, and then centrifuging and drying to obtain a sample of nickel oxide loaded on graphene.

[0169] The preparation method of the lithium-ion battery in Example 13 is the same as that in Example 1, except that the method of preparing the carbon material containing the catalyst is different, specifically comprising: adding 0.75 g of NiO and 4.25 g of carbon nanofibers to 200 ml of deionized water and stirring for 1 hour to mix them evenly, then transferring the mixture to a reactor and placing it in a homogeneous reactor, maintaining it at 180°C for 15 hours, and then centrifuging and drying to obtain a sample of nickel oxide loaded on carbon nanofibers.

[0170] The preparation method of the lithium-ion battery of Example 23 is the same as that of Example 1, except that the preparation method of the capacity compensation additive in the process of preparing the positive electrode plate is different, specifically comprising: weighing 1g of nickel oxide as a catalyst and placing it in a quartz boat, then placing the quartz boat in a chemical vapor deposition reactor, introducing nitrogen, controlling the flow rate to 500sccm, heating to 800°C, introducing acetylene as a carbon source, reacting for 1h, cooling, and obtaining carbon nanotubes containing the catalyst. After ICP component analysis, the nickel oxide content in the carbon nanotubes containing the catalyst was measured to be 15wt%; lithium oxalate and carbon nanotubes containing the catalyst were weighed according to a mass ratio of 9:1, mixed in ethanol to a concentration of 10g / L, stirred for 2h to obtain a spinning solution, adjusted the push speed of the spinneret to 0.5mL / h, the voltage between the spinneret and the receiver to 18kV, and the distance between the spinneret and the receiver to 15cm, and spun into a capacity compensation additive.

[0171] Comparative Example 3

[0172] The preparation method of the lithium-ion battery is the same as that of Example 1, except that the process of preparing the capacity compensation additive in preparing the positive electrode plate is different, as shown in Table 1.

[0173] The method for preparing the capacity compensation additive comprises:

[0174] 1 g of nickel oxide was weighed as a catalyst and placed in a quartz boat. The quartz boat was then placed in a chemical vapor deposition reactor. Nitrogen was introduced at a controlled flow rate of 500 sccm. The temperature was raised to 800°C, and acetylene was introduced as a carbon source. The reaction was allowed to proceed for 1 hour, and the reaction was cooled to obtain catalyst-containing carbon nanotubes. Composition analysis by ICP (inductively coupled plasma mass spectrometry) revealed that the nickel oxide content in the catalyst-containing carbon nanotubes was 15 wt%.

[0175] Lithium oxalate and carbon nanotubes containing a catalyst were weighed in a mass ratio of 9:1, mixed in water to a concentration of 100 g / L, and then ground by a sand mill for 2 hours at a controlled speed of 1000 rpm. After drying, a capacity compensation additive was obtained.

[0176] Comparative Example 5

[0177] The preparation method of the lithium-ion battery is the same as that of Example 1, except that the process of preparing the capacity compensation additive in preparing the positive electrode plate is different, as shown in Table 1.

[0178] The method for preparing the capacity compensation additive comprises:

[0179] 1 g of nickel oxide was weighed as a catalyst and placed in a quartz boat. The quartz boat was then placed in a chemical vapor deposition reactor. Nitrogen was introduced at a controlled flow rate of 500 sccm. The temperature was raised to 800°C, and acetylene was introduced as a carbon source. The reaction was allowed to proceed for 1 hour, and the reaction was cooled to obtain catalyst-containing carbon nanotubes. Composition analysis by ICP (inductively coupled plasma mass spectrometry) revealed that the nickel oxide content in the catalyst-containing carbon nanotubes was 15 wt%.

[0180] Lithium oxalate and carbon nanotubes containing a catalyst were weighed in a mass ratio of 9:1 and mixed in water to a concentration of 5 g / L. The solution was then added dropwise to ethanol. The capacity compensation additive was recrystallized in ethanol and filtered and dried to obtain the capacity compensation additive.

[0181] Comparative Example 6

[0182] The preparation method of the lithium-ion battery is the same as that of Example 1, except that no capacity compensation additive is added in the preparation of the positive electrode plate, as shown in Table 1.

[0183] The powder resistivity and decomposition voltage of the capacity compensation additives obtained in Examples 1-23 and Comparative Examples 1-6, as well as the first charge capacity and cycle performance of the batteries were characterized. The characterization results are shown in Table 2.

[0184] (1) Decomposition voltage test of capacity compensation additives

[0185] Prepare button cells:

[0186] a. Preparation of positive electrode sheet:

[0187] Lithium iron phosphate, capacity compensation additive, acetylene black, and binder polyvinylidene fluoride were dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 90.25:3:2:4.75, and the mixture was stirred thoroughly to prepare a positive electrode slurry. The positive electrode slurry was coated on one side of the aluminum foil (coating surface density was 0.8 mm). 2 ), then drying and cold pressing to form a positive electrode active material layer (with a thickness of 0.05 mm) on one side of an aluminum foil (with a thickness of 15 μm), and finally punching to obtain a positive electrode sheet;

[0188] b. Preparation of negative electrode sheet:

[0189] A metal lithium sheet with a thickness of 0.5 mm was used as the negative electrode.

[0190] c. Preparation of isolation membrane:

[0191] Polyethylene was used as the separator (thickness 20 μm);

[0192] d. Preparation of electrolyte

[0193] Ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) are mixed in a mass ratio of 1:1:1 to obtain a solvent, and fully dried electrolyte salt LiPF6 is dissolved in the above solvent. After mixing evenly, an electrolyte solution with a concentration of 1 mol / L is obtained.

[0194] Assembly: Stack a single positive electrode sheet, a single separator, and a single negative electrode sheet in order (the side of the positive electrode sheet where the positive active material layer is formed contacts the separator), place the separator between the positive and negative electrodes to isolate them, add electrolyte, and pressure package (500 MPa) to obtain a CR2032 button battery A (capacity ≤ 2 mAh).

[0195] The above-mentioned button-type full cell A was used as an experimental example to perform charge and discharge cycles at a rate of 0.1C at 25°C, and the capacity (Q)-voltage (V) curve of the first cycle was recorded. The dQ / dV-V curve was obtained by differentiating it. At the same time, the button-type battery of the control group (no capacity compensation additive was added to the positive electrode plate, that is, lithium iron phosphate, acetylene black, and binder polyvinylidene fluoride were mixed in a mass ratio of 95:3:2 in the preparation of the positive electrode plate, and the rest was the same as the above-mentioned button-type battery) was obtained under the same conditions. By comparing the two curves, an additional peak can be seen from the dQ / dV-V curve of the experimental example button battery. This peak is the characteristic peak of the capacity compensation additive, and the ordinate corresponding to the peak is the decomposition potential of the capacity compensation additive.

[0196] (2) Powder resistivity test

[0197] Four probes are used to measure the current and voltage on the powder sample, from which the resistivity is calculated.

[0198] (3) First charge capacity test of the battery:

[0199] Button cell B was prepared. The difference between it and button cell A is that no capacity compensation additive was added when preparing the positive electrode plate. Lithium iron phosphate, acetylene black, and binder polyvinylidene fluoride were dissolved in solvent N-methylpyrrolidone (NMP) in a mass ratio of 95:3:2. The mixture was thoroughly stirred and mixed to prepare a positive electrode slurry.

[0200] At 25°C, charge the button cell A to 4.5V at a current density of 0.1C, and record the initial charge capacity Q. A Then charge button battery B to 4.5V at a current density of 0.1C and record the battery's first charge capacity Q. B , first charge capacity = (Q A -W1Q B ) / W2, where in the positive electrode sheet in button battery A, based on the total mass of lithium iron phosphate and capacity compensation additive, the mass proportion of capacity compensation additive is W2, and the mass proportion of lithium iron phosphate is W1.

[0201] (4) Cycle performance test of lithium-ion batteries:

[0202] Keep the ambient temperature at 60°C, let the battery rest for 2 hours, discharge at 1C to 2.5V, let it rest for 5 minutes, charge at 1C to 3.65V, let it rest for 5 minutes, and discharge at 1C to 2.5V. Record the discharge capacity as C0. Perform 1000 cycles of charging at 1C to 3.65V, letting it rest for 5 minutes, discharging at 1C to 2.5V, and letting it rest for 5 minutes. The discharge capacity at the 1000th cycle is C1. The cycle capacity retention rate of the battery cell = C1 / C0*100%.

[0203] FIG7 is a comparison chart of the cycle curves of the batteries of Example 1, Comparative Examples 1 and 6. As can be seen from FIG7, the capacity retention rate of the lithium-ion battery of Example 1 is significantly higher than that of Comparative Examples 1 and 6 after 1000 cycles, indicating that the addition of a capacity compensation additive including a catalyst-containing carbon material to the positive electrode plate of Example 1 can improve the cycle performance of the battery.

[0204] Figure 8 is an SEM image of the capacity compensation additive obtained in Example 1, and Figure 9 is a distribution diagram of the Ni element in the EDS spectrum of the capacity compensation additive obtained in Example 1 (refer to the test method of GB / T 17359-2012). It can be seen from the figure that the Ni element is evenly distributed on the surface of the capacity compensation additive, which indicates that the carbon nanotubes containing nickel oxide are evenly distributed on the surface of the capacity compensation agent and the nickel oxide is evenly distributed on the carbon nanotubes.

[0205] Table 2

[0206] Conclusion: It can be seen from the data in Table 2 that the decomposition voltage of the capacity compensating agent of Example 1-23 is significantly lower than that of Comparative Example 1-6, and the first charge capacity and capacity retention rate of the battery of Example 1-23 are significantly higher than those of Comparative Example 1-6, which shows that the capacity compensating additive of the present application has a lower decomposition voltage, thereby improving the capacity and cycle performance of the battery.

[0207] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solution of the present application, embodiments having substantially the same structure as the technical concept and exerting the same effects are all included in the technical scope of the present application. In addition, within the scope of the subject matter of the present application, various modifications that can be conceived by those skilled in the art to the embodiments, and other methods constructed by combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A capacity compensation additive, characterized in that: The invention comprises a capacity compensating agent and a carbon material containing a catalyst, wherein the carbon material containing the catalyst is coated on at least a part of the surface of the capacity compensating agent.

2. The capacity compensation additive according to claim 1, characterized in that: The catalyst-containing carbon material comprises a carbon support and a catalyst, wherein the catalyst is supported on at least a portion of the carbon support, and the catalyst comprises M x Q y , 1≤x≤6, 1≤y≤3, M includes at least one of Ni, Co, Mn, Fe, Cu, Ti, Nb, Mg or Cr, and Q includes at least one of O, N, S or P.

3. The capacity compensation additive according to claim 2, characterized in that: M includes at least one of Ni, Co or Fe, and Q includes O and / or N.

4. The capacity compensation additive according to claim 2 or 3, characterized in that: Based on the total mass of the catalyst-containing carbon material, the mass proportion of the catalyst is 5%-20%.

5. The capacity compensation additive according to any one of claims 2 to 4, characterized in that: Based on the total mass of the catalyst-containing carbon material, the mass proportion of the catalyst is 5%-15%.

6. The capacity compensation additive according to any one of claims 2 to 5, characterized in that: The particle size of the catalyst is 300nm-1μm.

7. The capacity compensation additive according to any one of claims 2 to 6, characterized in that: The particle size of the catalyst is 500nm-800nm.

8. The capacity compensation additive according to any one of claims 1 to 7, characterized in that: Based on the total mass of the capacity compensation additive, the mass proportion of the catalyst-containing carbon material is 1%-20%.

9. The capacity compensation additive according to any one of claims 1 to 8, characterized in that: Based on the total mass of the capacity compensation additive, the mass proportion of the catalyst-containing carbon material is 5%-10%.

10. The capacity compensation additive according to any one of claims 1 to 9, characterized in that: The capacity compensating agent includes A a C b O c , wherein A includes Na and / or Li, 2≤a≤4, 1≤b≤6, 3≤c≤6.

11. The capacity compensation additive according to any one of claims 1 to 10, characterized in that: The capacity compensating agent includes a lithium supplementing agent, and the lithium supplementing agent includes at least one of Li2CO3, Li2C2O4, Li2C4O4, Li2C4O6 or Li2C3O5.

12. The capacity compensation additive according to claim 11, characterized in that: The lithium supplement includes at least one of Li2CO3, Li2C2O4 or Li2C4O4.

13. The capacity compensation additive according to any one of claims 1 to 12, characterized in that: The capacity compensating agent includes a sodium supplement, and the sodium supplement includes at least one of Na2CO3, Na2C2O4, Na2C4O4, Na2C6O6 or Na4C6O6.

14. The capacity compensation additive according to claim 13, characterized in that: The sodium supplement includes at least one of Na2C2O4 or Na2C4O4.

15. The capacity compensation additive according to any one of claims 1 to 14, characterized in that: The volume average particle size Dv50 of the capacity compensation additive is 1 μm-20 μm.

16. The capacity compensation additive according to any one of claims 1 to 15, characterized in that: The volume average particle size Dv50 of the capacity compensation additive is 1 μm-10 μm.

17. The capacity compensation additive according to any one of claims 1 to 16, characterized in that: At 20 MPa, the powder resistivity of the capacity compensation additive is less than or equal to 5Ω·cm.

18. The capacity compensation additive according to any one of claims 1 to 17, characterized in that: At 20 MPa, the powder resistivity of the capacity compensation additive is less than or equal to 1 Ω·cm.

19. The capacity compensation additive according to any one of claims 1 to 18, characterized in that: The decomposition voltage of the capacity compensation additive is lower than or equal to 4.5V.

20. The capacity compensation additive according to any one of claims 1 to 19, characterized in that: The decomposition voltage of the capacity compensation additive is lower than or equal to 4.3V.

21. A method for preparing a capacity compensation additive, characterized in that: include: The catalyst-containing carbon material is coated on at least a portion of the surface of the capacity compensating agent to obtain the capacity compensating additive.

22. The method according to claim 21, characterized in that The catalyst-containing carbon material is coated on at least a portion of the surface of the capacity compensating agent in the following manner: The slurry including the catalyst-containing carbon material and the capacity compensating agent is spray-dried to coat at least a portion of the surface of the capacity compensating agent with the catalyst-containing carbon material.

23. The method according to claim 22, characterized in that The spray drying comprises at least one of the following conditions: The concentration of the slurry including the capacity compensating agent and the carbon material containing the catalyst is 20 g / L-50 g / L; The air inlet temperature is 120℃-150℃; The air outlet temperature is 80℃-100℃.

24. The method according to claim 22 or 23, characterized in that The catalyst-containing carbon material is coated on at least a portion of the surface of the capacity compensating agent in the following manner: The slurry including the catalyst-containing carbon material and the capacity compensating agent is subjected to electrostatic spinning, so that the catalyst-containing carbon material is coated on at least a portion of the surface of the capacity compensating agent.

25. The method according to claim 24, characterized in that The electrospinning comprises at least one of the following conditions: The concentration of the slurry including the capacity compensating agent and the carbon material containing the catalyst is 5 g / L-20 g / L; The push speed of the spinneret is 0.3mL / h-1mL / h; The voltage between the spinneret and the receiver is 15kV-18kV; The distance between the spinneret and the receiver is 12cm-20cm.

26. A positive electrode plate, characterized in that: The invention comprises the capacity compensating additive described in any one of claims 1 to 20 or the capacity compensating additive obtained by the method described in any one of claims 21 to 25.

27. The positive electrode sheet according to claim 26, characterized in that: The positive electrode plate includes a positive electrode active material layer, and the positive electrode active material layer includes the capacity compensation additive.

28. The positive electrode sheet according to claim 27, characterized in that: Based on the total mass of the positive electrode active material layer, the mass proportion of the capacity compensation additive is 1%-20%.

29. The positive electrode sheet according to claim 27 or 28, characterized in that: Based on the total mass of the positive electrode active material layer, the mass proportion of the capacity compensation additive is 1%-5%.

30. A battery, characterized in that: A positive electrode sheet comprising any one of claims 26-29.

31. An electrical device, characterized in that: The electrical device comprises the battery according to claim 30.

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