A positive electrode material, a positive electrode sheet, a secondary battery, a battery module, a battery pack, and an electric device

Abstract

The application provides a positive electrode material, a positive electrode sheet, a secondary battery, a battery module, a battery pack and a power utilization device. The positive electrode material comprises a manganese-containing active material and a functionalized carbon nanotube. The surface of the functionalized carbon nanotube comprises a lone pair of electrons. The lone pair of electrons on the surface of the functionalized carbon nanotube has strong coordination ability. During the charging and discharging process of the secondary battery, the lone pair of electrons can coordinate with Mn 2+ dissolved from the manganese-containing active material to form a coordination structure, thereby reducing the amount of Mn 2+ dissolved, improving the manganese dissolution phenomenon of the secondary battery, and further improving the cycle performance of the secondary battery.

Description

Technical Field

[0001] This application relates to the field of electrochemical technology, and in particular to a positive electrode material, a positive electrode sheet, a secondary battery, a battery module, a battery pack, and an electrical device. Background Technology

[0002] Lithium-ion batteries possess advantages such as high energy density, high open-circuit voltage, low self-discharge rate, long cycle life, and good safety, and are widely used in various fields such as portable energy storage, electronic devices, and electric vehicles. However, this also places higher demands on the overall performance of lithium-ion batteries, such as simultaneously possessing good cycle performance.

[0003] The cathode material in lithium-ion batteries is one of the key factors affecting battery performance, and manganese-containing active materials are widely used. During the charge and discharge process of lithium-ion batteries, the manganese in the manganese-containing active material undergoes a disproportionation reaction, resulting in Mn2+. 2+ Dissolved in the electrolyte, Mn 2+ It will migrate to the negative electrode and be reduced to Mn, causing irreversible loss of the positive electrode material, which in turn affects the cycle performance of lithium-ion batteries. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to improve the manganese dissolution phenomenon of secondary batteries, thereby improving the cycle performance of secondary batteries.

[0005] To achieve the above objectives, this application provides a positive electrode material, a positive electrode sheet, a secondary battery, a battery module, a battery pack, and an electrical device.

[0006] The first aspect of this application provides a cathode material comprising a manganese-containing active material and functionalized carbon nanotubes, wherein the surface of the functionalized carbon nanotubes includes lone pairs of electrons. The lone pairs of electrons on the surface of the functionalized carbon nanotubes have strong coordination ability, and during the charging and discharging process of a secondary battery, these lone pairs of electrons can interact with Mn dissolved from the manganese-containing active material. 2+ To form a coordination structure to reduce Mn 2+ This reduces the amount of manganese leaching in the secondary battery, thereby improving the cycle performance of the secondary battery.

[0007] In any embodiment, the mass ratio of the functionalized carbon nanotubes to the manganese-containing active material is 0.0005:1-0.004:1, preferably 0.001:1-0.003:1. By adjusting the mass ratio of the functionalized carbon nanotubes to the manganese-containing active material within the above range, it is beneficial to simultaneously improve the cycle performance and energy density of the secondary battery.

[0008] In any embodiment, the functionalized carbon nanotubes include carboxylated carbon nanotubes and / or aminated carbon nanotubes. These functionalized carbon nanotubes have a large number of lone pairs of electrons on their surface, which can effectively capture dissolved Mn. 2+ It also forms a coordination structure with the secondary battery, improving the cycle performance of the secondary battery.

[0009] In any embodiment, the functionalization degree of the functionalized carbon nanotubes is 0.1%-6%, preferably 2%-5%. By controlling the functionalization degree of the functionalized carbon nanotubes within the above range, it is beneficial to improve the storage performance of the secondary battery and reduce the impedance of the secondary battery.

[0010] In any embodiment, the aspect ratio of the functionalized carbon nanotubes is 200-20000, preferably 1000-5000. By controlling the aspect ratio of the functionalized carbon nanotubes within the above range, it is beneficial to improve the cycle performance and storage performance of the secondary battery and reduce the impedance of the secondary battery.

[0011] In any embodiment, the diameter of the functionalized carbon nanotubes is 1 nm-100 nm, preferably 3 nm-80 nm. By controlling the diameter of the functionalized carbon nanotubes within the above range, it is beneficial to improve the cycle performance and storage performance of the secondary battery and reduce the impedance of the secondary battery.

[0012] In any embodiment, the length of the functionalized carbon nanotubes is 0.1 μm-50 μm, preferably 3 μm-30 μm. By controlling the length ratio of the functionalized carbon nanotubes within the above range, it is beneficial to improve the cycle performance and storage performance of the secondary battery and reduce the impedance of the secondary battery.

[0013] In any embodiment, the specific surface area of ​​the functionalized carbon nanotubes is 50 m². 2 / g-2000m 2 / g, preferably 300m 2 / g-1000m 2 / g. By controlling the specific surface area of ​​functionalized carbon nanotubes within the above range, it is beneficial to improve the cycle performance and storage performance of secondary batteries and reduce the impedance of secondary batteries.

[0014] In any embodiment, the manganese-containing active material comprises particles with a Dv50 of 50 nm to 99 nm, which are capable of embedding into the lumen of the functionalized carbon nanotubes. This facilitates the capture of dissolved Mn by the functionalized carbon nanotubes. 2+ It forms a coordination structure with the secondary battery, thereby improving the cycle performance of the secondary battery.

[0015] In any embodiment, the manganese-containing active material includes LiCo. x1 Mn y1 Ni1-x1-y1 O2, x2Li[Li 1 / 3 Mn 2 / 3 ]O2(1-x2)LiMO2, LiMn2O4, LiNi 0.5 Mn 1.5 At least one of O4, wherein 0 < x1 < 1, 0 < y1 < 1, 0 < x1 + y1 < 1, 0 ≤ x2 ≤ 1, and M is Ni, Co, or Mn. By selecting the above-mentioned manganese-containing active materials, it is beneficial to form a synergistic effect with functionalized carbon nanotubes to improve the manganese dissolution phenomenon in secondary batteries, thereby improving the cycle performance of secondary batteries.

[0016] A second aspect of this application provides a positive electrode sheet comprising a positive electrode material layer, wherein the positive electrode material layer comprises the positive electrode material of the first aspect of this application, wherein, based on the mass of the positive electrode material layer, the mass percentage content of the manganese-containing active material is 95.7%-96.05%, and the mass percentage content of the functionalized carbon nanotubes is 0.05%-0.4%. By controlling the mass percentage content of the manganese-containing active material and the functionalized carbon nanotubes within the above ranges, it is beneficial to improve the manganese dissolution phenomenon in the secondary battery, thereby improving the cycle performance of the secondary battery. Furthermore, the functionalized carbon nanotubes have good conductivity, thus acting as a conductive agent, which can reduce the amount of conductive agent used in the positive electrode material layer.

[0017] A third aspect of this application provides a secondary battery that includes the positive electrode of the second aspect of this application.

[0018] A fourth aspect of this application provides a battery module that includes the secondary battery of the third aspect of this application.

[0019] The fifth aspect of this application provides a battery pack that includes the battery module of the fourth aspect of this application.

[0020] The sixth aspect of this application provides an electrical device that includes a secondary battery according to the third aspect of this application, a battery module according to the fourth aspect of this application, or a battery pack according to the fifth aspect of this application.

[0021] The beneficial effects of this application are:

[0022] This application provides a cathode material, comprising a manganese-containing active material and functionalized carbon nanotubes, wherein the surface of the functionalized carbon nanotubes includes lone pairs of electrons. The applicant has discovered that the lone pairs of electrons on the surface of the functionalized carbon nanotubes possess strong coordination ability; during the charge and discharge process of a secondary battery, these lone pairs of electrons can interact with Mn dissolved from the manganese-containing active material. 2+ To form a coordination structure to reduce Mn 2+ This reduces the amount of manganese leaching, thereby improving the manganese leaching phenomenon in secondary batteries. Simultaneously, Mn... 2+The dihedral angle φ of the coordination bonds formed with the carboxyl and amino groups on the carbon nanotube surface is 180°, and the structure is conjugated. This coplanar conjugated structure promotes the Mn 2+ The strong electrical contact formed with carboxyl and amino groups reduces the energy level difference between the highest occupied orbital and the lowest vacant orbital of the coordination node. This strong electrical contact is equivalent to building an "electron transport bridge" between carbon nanotubes, increasing the electron transport path between them, accelerating electron transport, and ultimately improving the conductivity of the carbon nanotubes, reducing the resistance of the cathode material layer, and thus improving the cycle performance of the secondary battery. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of this application and the prior art, the accompanying drawings used in the embodiments and the prior art are briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application.

[0024] Figure 1 This is a schematic diagram of a secondary battery according to one embodiment of this application;

[0025] Figure 2 for Figure 1 An exploded view of a secondary battery according to an embodiment of this application is shown.

[0026] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application;

[0027] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application;

[0028] Figure 5 for Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown;

[0029] Figure 6 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to an embodiment of this application.

[0030] Figure 7 Infrared spectra of single-walled carbon nanotubes and carboxylated carbon nanotubes according to an embodiment of this application.

[0031] Figure 8 X-ray photoelectron spectrum of single-walled carbon nanotubes;

[0032] Figure 9 The X-ray photoelectron spectra of the carboxylated carbon nanotubes in Examples 2-3 are shown. Detailed Implementation

[0033] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the negative electrode, positive electrode, secondary battery, battery module, battery pack, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0034] 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 ​​1 and 2 are listed, and if maximum range values ​​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.

[0035] Unless otherwise specified, all embodiments and preferred embodiments of this application can be combined to form new technical solutions.

[0036] Unless otherwise specified, all technical features and preferred technical features of this application can be combined to form new technical solutions.

[0037] 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.

[0038] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0039] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0040] During the research process, the applicant discovered that during the charging and discharging of secondary batteries (such as lithium-ion batteries), manganese in manganese-containing active materials undergoes a disproportionation reaction, causing Mn to... 2+ Dissolved in the electrolyte, Mn 2+ The manganese will migrate to the negative electrode and be reduced to Mn, causing irreversible loss of the positive electrode material, which in turn affects the cycle performance of the secondary battery. In order to improve the manganese dissolution phenomenon in the secondary battery and enhance its cycle performance, so that the secondary battery can have better performance when used in electrical devices, such as longer driving range and longer service life, this application provides a positive electrode material, a positive electrode sheet, a secondary battery, a battery module, a battery pack, and an electrical device.

[0041] It should be noted that, in the specific embodiments of this application, lithium-ion batteries are used as an example of secondary batteries to explain this application, but the secondary batteries in this application are not limited to lithium-ion batteries.

[0042] In one embodiment of this application, a cathode material is proposed, comprising a manganese-containing active material and functionalized carbon nanotubes, wherein the surface of the functionalized carbon nanotubes comprises lone pairs of electrons.

[0043] Although the mechanism is not yet clear, the applicant unexpectedly discovered that the lone pairs of electrons on the surface of functionalized carbon nanotubes have a strong coordination ability. During the charging and discharging process of the secondary battery, the lone pairs of electrons can interact with Mn dissolved from the manganese-containing active material. 2+ To form a coordination structure to reduce Mn 2+ The amount of manganese leached and the content entering the electrolyte can inhibit manganese deposition at the negative electrode, thereby improving the manganese leaching phenomenon in secondary batteries. Meanwhile, Mn... 2+ The dihedral angle φ of the coordination bonds formed with the carboxyl and amino groups on the carbon nanotube surface is 180°, and the structure is conjugated. This coplanar conjugated structure promotes the Mn 2+ The strong electrical contact formed with carboxyl and amino groups reduces the energy level difference between the highest occupied orbital and the lowest vacant orbital of the coordination node. This strong electrical contact acts as a "bridge" for electron transport between carbon nanotubes, increasing the electron transport path and accelerating electron transport. Ultimately, this improves the conductivity of the carbon nanotubes, reduces the resistance of the positive electrode material layer, and thus improves the cycle performance of the secondary battery. Furthermore, the reduced amount of manganese metal deposited on the negative electrode mitigates the problem of continuous growth at the solid electrolyte interface, lowering the impedance of the secondary battery and improving its storage and rate performance.

[0044] In some embodiments, the mass ratio of functionalized carbon nanotubes to manganese-containing active materials is 0.0005:1-0.004:1, preferably 0.001:1-0.003:1. The applicant has found that when the mass ratio of functionalized carbon nanotubes to manganese-containing active materials is too small (e.g., less than 0.0005:1), the content of functionalized carbon nanotubes is too low, and the improvement on manganese dissolution in the secondary battery is not significant; when the mass ratio of functionalized carbon nanotubes to manganese-containing active materials is too large (e.g., greater than 0.004:1), the content of manganese-containing active materials decreases, which affects the energy density of the secondary battery. By controlling the mass ratio of functionalized carbon nanotubes to manganese-containing active materials within the above range, it is beneficial to simultaneously improve the cycle performance and energy density of the secondary battery.

[0045] In some embodiments, the functionalized carbon nanotubes include carboxylated carbon nanotubes and / or aminated carbon nanotubes. Mn 2+ Mn forms a conjugated structure with the carboxyl groups on the surface of carboxylated carbon nanotubes or the amino functional groups on the surface of aminolated carbon nanotubes, thus enabling Mn to form a conjugated structure. 2+ It forms a strong electrical contact with carboxyl or amino groups, which can effectively capture dissolved Mn. 2+This forms a coordination structure with the functionalized carbon nanotubes, improving the cycle performance of the secondary battery. Furthermore, this strong electrical contact increases and accelerates the electron transport path between the functionalized carbon nanotubes, enhancing their conductivity. This, in turn, helps reduce the internal resistance of the secondary battery, improves its rate performance, and maximizes the capacity of the manganese-containing active material. When the functionalized carbon nanotubes include both carboxylated and aminated carbon nanotubes, this application does not impose any particular limitation on the content relationship between the two, as long as the purpose of this application is achieved. For example, the mass ratio of carboxylated carbon nanotubes to aminated carbon nanotubes is 3:1.

[0046] In some embodiments, the functionalization degree of the functionalized carbon nanotubes is 0.1%-6%, preferably 2%-5%. The functionalization degree of the functionalized carbon nanotubes directly affects the number of lone pairs of electrons on the surface of the functionalized carbon nanotubes, and thus affects the degree of improvement in manganese dissolution. Therefore, when the functionalization degree of the functionalized carbon nanotubes is too low (e.g., below 0.1%), the number of lone pairs of electrons on the surface of the functionalized carbon nanotubes is small, and the improvement in manganese dissolution in the secondary battery is not significant. However, when the functionalization degree of the functionalized carbon nanotubes is too high (e.g., above 6%), it will damage the structure of the functionalized carbon nanotubes, affect their conductivity, and increase the internal resistance of the secondary battery. By controlling the functionalization degree of the functionalized carbon nanotubes within the above range, dissolved Mn can be captured to the maximum extent. 2+ This improves the resistance of the secondary battery by mitigating the damage to the solid electrolyte interface film caused by the deposition of metallic manganese at the negative electrode, thereby enhancing the battery's cycle performance. Simultaneously, it allows for the full utilization of Mn... 2+ The ability to form strong electrical contacts with carboxyl or amino groups is beneficial for improving the storage performance and reducing the impedance of secondary batteries. In this application, the degree of functionalization refers to the mass percentage of functional groups in the functionalized carbon nanotubes, based on their mass. For example, the degree of functionalization of carboxylated carbon nanotubes refers to the mass percentage of carboxyl groups based on the mass of the carboxylated carbon nanotubes; the specific testing process is described in the testing section.

[0047] In some embodiments, the aspect ratio of the functionalized carbon nanotubes is 200-20000, preferably 1000-5000. The applicant has found that when the aspect ratio of the functionalized carbon nanotubes is too small (e.g., less than 200), the functionalized carbon nanotubes tend to aggregate, making it difficult to effectively capture Mn. 2+Furthermore, the reduced contact sites between functionalized carbon nanotubes and manganese-containing active materials lead to increased internal resistance in secondary batteries. When the aspect ratio of functionalized carbon nanotubes is too large (e.g., greater than 20000), the nanotubes are prone to entanglement, affecting the internal resistance and cycle performance of the secondary battery. By controlling the aspect ratio of functionalized carbon nanotubes within the above range, the manganese dissolution phenomenon in secondary batteries can be effectively improved, as well as the problem of manganese deposition on the negative electrode damaging the solid electrolyte interface film. This is beneficial for improving the cycle performance and storage performance of secondary batteries and reducing their impedance.

[0048] In some embodiments, the diameter of the functionalized carbon nanotubes is 1 nm to 100 nm, preferably 3 nm to 80 nm. The applicant has found that when the diameter of the functionalized carbon nanotubes is too small (e.g., less than 1 nm), the functionalized carbon nanotubes tend to aggregate, making it difficult to effectively capture Mn. 2+ Furthermore, the reduced contact sites between functionalized carbon nanotubes and manganese-containing active materials lead to increased internal resistance in secondary batteries. When the diameter of functionalized carbon nanotubes is too large (e.g., greater than 100 nm), they are prone to entanglement, affecting the internal resistance and cycle performance of the secondary battery. By controlling the diameter of functionalized carbon nanotubes within the aforementioned range, the manganese dissolution phenomenon in secondary batteries can be effectively improved, as well as the problem of manganese deposition on the negative electrode damaging the solid electrolyte interface film. This is beneficial for improving the cycle performance and storage performance of secondary batteries and reducing their impedance.

[0049] In some embodiments, the length of the functionalized carbon nanotubes is 0.1 μm-50 μm, preferably 3 μm-30 μm. The applicant has found that when the length of the functionalized carbon nanotubes is too small (e.g., less than 0.1 μm), the functionalized carbon nanotubes tend to aggregate, making it difficult to effectively capture Mn. 2+ The functionalized carbon nanotubes (FCNs) have several drawbacks. Furthermore, the reduced contact sites between FCNs and manganese-containing active materials can lead to increased internal resistance in the secondary battery. When the length of the FCNs is too large (e.g., greater than 50 μm), they are prone to entanglement, affecting the internal resistance and cycle performance of the secondary battery. By controlling the length ratio of the FCNs within the aforementioned range, the manganese dissolution phenomenon in the secondary battery can be effectively improved, as well as the problem of manganese deposition on the negative electrode damaging the solid electrolyte interface film. This is beneficial for improving the cycle performance and storage performance of the secondary battery and reducing its impedance.

[0050] In some embodiments, the functionalized carbon nanotubes have a specific surface area of ​​50 m². 2 / g-2000m 2 / g, preferably 300m 2 / g-1000m 2 / g. The applicant discovered that when the specific surface area of ​​functionalized carbon nanotubes is too small (e.g., less than 50m²), 2 / g), the number of lone pairs of electrons on the surface of functionalized carbon nanotubes is reduced, resulting in little improvement in the manganese dissolution phenomenon of secondary batteries; moreover, functionalized carbon nanotubes are prone to aggregation, thus making it difficult to effectively capture Mn. 2+ The functionalized carbon nanotubes (FCNs) have several drawbacks. Firstly, the reduced contact sites between FCNs and manganese-containing active materials can lead to increased internal resistance in the secondary battery. Secondly, when the specific surface area of ​​FCNs is too large (e.g., greater than 100 nm), the FCNs are prone to entanglement, affecting the internal resistance and cycle performance of the secondary battery. By controlling the specific surface area of ​​FCNs within the aforementioned range and addressing the issue of manganese deposition at the negative electrode damaging the solid electrolyte interface film, the manganese dissolution phenomenon in the secondary battery can be effectively improved. This, in turn, enhances the cycle performance and storage capacity of the secondary battery and reduces its impedance.

[0051] In some embodiments, the manganese-containing active material comprises particles with a Dv50 of 50 nm to 99 nm, which can be embedded into the lumen of functionalized carbon nanotubes. It is understood that particles with a Dv50 of 50 nm to 99 nm can be embedded into the lumen of functionalized carbon nanotubes with a tube diameter larger than the Dv50 size, which is beneficial for the functionalized carbon nanotubes to capture dissolved Mn. 2+ It forms a coordination structure with the carbon nanotube, thereby improving the cycle performance of the secondary battery. In this application, the particles of manganese-containing active material are embedded in the lumen of the functionalized carbon nanotube. This can be done by partially or completely embedding the particles of manganese-containing active material into the lumen of the functionalized carbon nanotube. Preferably, it is done by partially embedding the particles of manganese-containing active material into the lumen of the functionalized carbon nanotube, which is beneficial for improving the cycle performance of the secondary battery while also enabling the secondary battery to have a higher energy density.

[0052] In some embodiments, the manganese-containing active material includes LiCo. x1 Mn y1 Ni 1-x1-y1 O2, x2Li[Li 1 / 3 Mn 2 / 3 ]O2(1-x2)LiMO2, LiMn2O4, LiNi 0.5 Mn 1.5 At least one of O4, wherein 0 < x1 < 1, 0 < y1 < 1, 0 < x1 + y1 < 1, 0 ≤ x2 ≤ 1, and M is Ni, Co, or Mn. By selecting the above-mentioned manganese-containing active materials, it is beneficial to form a synergistic effect with functionalized carbon nanotubes to improve the manganese dissolution phenomenon in secondary batteries, thereby improving the cycle performance of secondary batteries.

[0053] In this application, there are no particular restrictions on the preparation method of functionalized carbon nanotubes, as long as the purpose of this application can be achieved. For example, the preparation method of functionalized carbon nanotubes may include, but is not limited to, the following preparation steps: mixing carbon nanotubes with functional group precursors, ultrasonically dispersing them and reacting them in a water bath at 60℃-130℃, and then washing, filtering and drying to obtain functionalized carbon nanotubes.

[0054] The second aspect of this application provides a positive electrode sheet, comprising a positive electrode material layer, which includes the positive electrode material of the first aspect of this application. The positive electrode material layer contains, based on its mass, a manganese-containing active material with a mass percentage of 95.7%-96.05% and a functionalized carbon nanotube with a mass percentage of 0.05%-0.4%. By controlling the mass percentages of the manganese-containing active material and the functionalized carbon nanotube within the above ranges, it is beneficial to improve the manganese dissolution phenomenon in the secondary battery, thereby improving the cycle performance of the secondary battery. Furthermore, the functionalized carbon nanotube has good conductivity, thus acting as a conductive agent, which can reduce the amount of conductive agent used in the positive electrode material layer.

[0055] In addition, the secondary battery, battery module, battery pack and power device of this application will be described below with appropriate reference to the accompanying drawings.

[0056] In one embodiment of this application, a secondary battery is provided, which includes the positive electrode sheet described in any of the above embodiments. The secondary battery in this application may refer to the secondary battery described in any of the above embodiments.

[0057] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0058] [Positive electrode plate]

[0059] The positive electrode also includes a positive current collector, and a positive electrode material layer is disposed on at least one surface of the positive current collector. As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0060] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer 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 (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0061] In some embodiments, the positive electrode material layer preferably also includes a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0062] In some embodiments, the positive electrode material layer preferably also includes a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0063] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive electrode material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0064] [Negative electrode plate]

[0065] The negative electrode sheet includes a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector, the negative electrode material layer including a negative electrode material.

[0066] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0067] 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 polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0068] In some embodiments, the negative electrode material may be a negative electrode material known in the art for use in batteries. As an example, the negative electrode 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 is preferably at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material is preferably 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 battery negative electrode materials may also be used. These negative electrode materials may be used alone or in combination of two or more.

[0069] In some embodiments, the negative electrode material layer preferably also includes an adhesive. The adhesive is preferably at least one selected from 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).

[0070] In some embodiments, the negative electrode material layer preferably also includes a conductive agent. The conductive agent is preferably selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0071] In some embodiments, the negative electrode material layer preferably also includes other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0072] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as negative electrode 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 a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0073] [Electrolytes]

[0074] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0075] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0076] In some embodiments, the electrolyte salt is preferably 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.

[0077] In some embodiments, the solvent is preferably 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.

[0078] In some embodiments, the electrolyte preferably includes 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.

[0079] [Isolation membrane]

[0080] In some embodiments, the secondary 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.

[0081] In some embodiments, the material of the separator is preferably 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.

[0082] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0083] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0084] 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. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0085] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 This is an example of a square-structured secondary battery 5.

[0086] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 can be placed over the opening to close the receiving cavity. A positive electrode, a negative electrode, and a separator can be formed into an electrode assembly 52 using a winding or stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The secondary battery 5 may contain one or more electrode assemblies 52, which can be selected by those skilled in the art according to specific practical needs.

[0087] In some implementations, the secondary batteries can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0088] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple secondary batteries 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple secondary batteries 5 can be fixed in place using fasteners.

[0089] Preferably, the battery module 4 may further include a housing with a receiving space in which a plurality of secondary batteries 5 are received.

[0090] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0091] Figure 4 and Figure 5 This is a sample battery pack 10. (See reference...) Figure 4 and Figure 5The battery pack 10 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper box 11 and a lower box 12, with the upper box 11 covering the lower box 12 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0092] In addition, this application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0093] As the electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0094] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0095] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0096] Example

[0097] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0098] Example 1-1

[0099] <Preparation of Functionalized Carbon Nanotubes>

[0100] 5g of single-walled carbon nanotubes (SUVs) were added to 450mL of mixed acid, and the SUVs were dispersed uniformly by ultrasonic treatment. The mixture was then refluxed in a 70℃ water bath for 6 hours. After the reaction, the mixture was diluted with deionized water, filtered, washed until neutral, and then vacuum dried at 60℃ for 24 hours to obtain carboxylated carbon nanotubes. The mixed acid was a mixture of concentrated sulfuric acid and concentrated nitric acid in a 3:1 volume ratio. The functionalization degree of the carbon nanotubes was 4.5%, the aspect ratio was 1000-3000, the length was 5μm-15μm, the tube diameter was 2nm-4nm, and the specific surface area was 700m². 2 / g-900m 2 / g.

[0101] like Figure 7 The image shows the infrared spectra of single-walled carbon nanotubes and the carboxylated carbon nanotubes prepared above. The carboxylated carbon nanotubes show the infrared spectrum at 1725 cm⁻¹. -1 The characteristic peak is the stretching vibration peak of -C=O, while the characteristic peak of uncarboxylated single-walled carbon nanotubes is very weak at this point. (3433 cm⁻¹) -1 The characteristic peak at position -OH stretching vibration increases in intensity after carboxylation. These phenomena indicate that carboxylated carbon nanotubes were successfully prepared.

[0102] <Preparation of the positive electrode>

[0103] The functionalized carbon nanotubes prepared above were added to N-methylpyrrolidone (NMP) to obtain a functionalized carbon nanotube dispersion with a solid content of 5 wt%. Manganese-containing active material LiMn2O4, the functionalized carbon nanotube dispersion, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) were mixed to a mass ratio of 96:0.1:2.6:1.3. NMP was then added as a solvent, and the mixture was stirred under vacuum until homogeneous, yielding a positive electrode slurry with a solid content of 70 wt%. The positive electrode slurry was uniformly coated onto one surface of a 13 μm thick aluminum foil, dried at 90°C, and cold-pressed to obtain a double-sided positive electrode sheet with a positive electrode material layer thickness of 110 μm. The positive electrode sheet was then obtained through processes such as tab forming and slitting. The mass ratio of functionalized carbon nanotubes to manganese-containing active material was 0.001:1.

[0104] <Preparation of Negative Electrode Sheets>

[0105] Artificial graphite (anode material), conductive carbon black (conductive agent), styrene-butadiene rubber (SBR) (binder), and carboxymethyl cellulose (CMC) (thickener) were mixed in a mass ratio of 96:0.9:1.6:1.5. Deionized water was added as a solvent, and the mixture was stirred under vacuum until homogeneous, yielding a negative electrode slurry with a solid content of 54 wt%. The negative electrode slurry was uniformly coated onto one surface of an 8 μm thick copper foil, dried at 110°C, and cold-pressed to obtain a double-sided coated negative electrode sheet with a negative electrode material layer thickness of 110 μm. The negative electrode sheet was then obtained through processes such as tab forming and slitting.

[0106] <Preparation of Electrolyte>

[0107] In an environment with a water content of less than 10 ppm, ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate were mixed in a volume ratio of 1:1:1 to obtain an electrolyte solvent. Then, lithium salt LiPF6 was dissolved in the mixed solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0108] <Preparation of the separating membrane>

[0109] A polyethylene film with a thickness of 14μm was selected as the separator. Before use, it was cut to the appropriate size according to the size of the positive and negative electrode plates.

[0110] <Preparation of Lithium-ion Batteries>

[0111] 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 packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a lithium-ion battery is obtained.

[0112] Examples 1-2 to Examples 1-6

[0113] Except for adjusting the mass percentage of manganese-containing active materials and functionalized carbon nanotubes according to Table 1, the rest is the same as in Examples 1-1.

[0114] Examples 1-7

[0115] Except for the preparation of functionalized carbon nanotubes according to the following steps, the rest is the same as in Example 1-1:

[0116] (1) Take 5g of the carboxylated carbon nanotubes prepared in Example 1-1 and add them to 450mL of SOCl2. Disperse the carboxylated carbon nanotubes evenly by ultrasonic treatment. Then reflux at 70℃ for 6h. After the reaction is completed, dilute with ethanol, filter, wash repeatedly, and finally dry under vacuum at 60℃ for 24h to obtain acylated carbon nanotubes.

[0117] (2) Add 5g of acylated carbon nanotubes to 500mL of ethylenediamine, disperse the acylated carbon nanotubes evenly by ultrasonic treatment, and then reflux at 120℃ for 6h. After the reaction is completed, dilute with ethanol, filter, wash repeatedly, and finally dry under vacuum at 60℃ for 24h to obtain aminoated carbon nanotubes.

[0118] Examples 1-8

[0119] Except that the functionalized carbon nanotubes were obtained by mixing the carboxylated carbon nanotubes prepared in Example 1-1 and the aminated carbon nanotubes prepared in Example 1-7 at a mass ratio of 1:1, and the mass percentage of both carboxylated carbon nanotubes and aminated carbon nanotubes was 0.1%, the rest of the process was the same as in Example 1-1.

[0120] Examples 2-1 to 2-6

[0121] Except for adjusting the reflux reaction time in the <Preparation of Functionalized Carbon Nanotubes> to 0.5h, 3h, 7h, 9h, 0.2h, and 12h respectively, so that the degree of functionalization of carbon nanotubes is as shown in Table 2, the rest is the same as in Example 1-1.

[0122] Examples 3-1 to 3-5

[0123] Except for adjusting the type of carbon nanotubes in the "Preparation of Functionalized Carbon Nanotubes" so that the aspect ratio, length, tube diameter, and specific surface area of ​​the functionalized carbon nanotubes are as shown in Table 3, the rest are the same as in Example 1-1.

[0124] Examples 4-1 to 4-4

[0125] Except for adjusting the cathode material according to Table 4, everything else is the same as in Example 1-1.

[0126] Comparative Example 1

[0127] Except for replacing the functionalized carbon nanotubes with single-walled carbon nanotubes, the rest is the same as in Example 1-1.

[0128] The preparation parameters and performance tests of each embodiment and comparative example are shown in Tables 1 to 4.

[0129] Capacity retention test:

[0130] (1) The lithium-ion batteries of the examples and comparative examples were charged to 4.3V at a constant current of 1 / 3C, then charged to 0.05C at a constant voltage of 4.3V, left to stand for 5 minutes, and then discharged to 3.0V at 1 / 3C. The discharge capacity C0 was recorded.

[0131] (2) Charge the lithium-ion battery at a constant current of 1.0C to 4.3V, let it stand for 5 minutes, and then discharge it at 1 / 3C to 3.0V and record the discharge capacity C1.

[0132] Repeat step (2) and record the discharge capacity C of the lithium-ion battery after the 200th cycle. 200 Capacity retention rate P 200 =C 200 / C0×100%.

[0133] Impedance growth rate:

[0134] At 25℃, the battery was charged at a constant current of 1 / 3C to 4.3V, then charged at a constant voltage of 4.3V to a current of 0.05C. After resting for 5 minutes, the voltage V1 was recorded. Then, the battery was discharged at 1 / 3C for 30 seconds, and the voltage V2 was recorded. This yields the impedance DCR1 of the lithium-ion battery after the first cycle. The above steps were repeated 200 times to obtain the impedance DCR of the lithium-ion battery after the 200th cycle. 200 Impedance growth rate = (DCR) 200 -DCR1) / DCR1×100%.

[0135] Functionalization test:

[0136] The content of C, O, or N elements in carbon nanotubes, carboxylated carbon nanotubes, and aminated carbon nanotubes is obtained by X-ray photoelectron spectroscopy (XPS). The increased content of O or N elements is the O in the carboxyl group or the N in the amino group. The mass m1 of the carboxyl or amino group in the functionalized carbon nanotube is then calculated. The degree of functionalization = m1 / mass of functionalized carbon nanotube × 100%.

[0137] like Figure 8 and Figure 9 The figures show the XPS spectra of single-walled carbon nanotubes and carboxylated carbon nanotubes prepared in Examples 2-3, respectively. Based on the analysis software provided by XPS, the information shown in Table 5 is as follows. Assuming that the total mass of the single-walled carbon nanotubes is entirely contributed by carboxyl groups and C atoms, the degree of functionalization of the carboxylated carbon nanotubes (i.e., the mass percentage of carboxyl groups) is calculated as follows:

[0138] The degree of functionalization of carboxylated carbon nanotubes = (0.004×45) / [(0.004×45)+(1-0.004)×12] = 0.15%, where the molar mass of the carboxyl group is 45 and the relative atomic mass of the C atom is 12. The calculation method for other embodiments is similar to that described above.

[0139] It should be noted that existing methods for preparing single-walled carbon nanotubes leave a small amount of carboxyl groups during the preparation process, resulting in a small amount of carboxyl groups in single-walled carbon nanotubes. However, the carboxyl content in carboxylated carbon nanotubes increases significantly after carboxylation treatment.

[0140] Diameter and length tests of functionalized carbon nanotubes:

[0141] The test was conducted according to the national standard GB / T 26826-2011 (Method for measuring the diameter of carbon nanotubes).

[0142] Specific surface area test:

[0143] The test was conducted according to the national standard GB / T 19587-2017 (Determination of Specific Surface Area of ​​Solid Substances by Gas Adsorption BET Method).

[0144] Table 1

[0145]

[0146] Table 2

[0147]

[0148]

[0149] Table 3

[0150]

[0151] Table 4

[0152]

[0153] Table 5

[0154]

[0155] Referring to Table 1, examples 1-1 to 1-8 and Comparative Example 1 show that lithium-ion batteries incorporating functionalized carbon nanotubes exhibit higher cycle capacity retention and lower impedance growth rate, meaning they possess better cycle performance. Examples 1-1 to 1-6 show that when the mass percentages of manganese-containing active material and functionalized carbon nanotubes, as well as the mass ratio of functionalized carbon nanotubes to manganese-containing active material, are within the range specified in this application, the resulting lithium-ion batteries exhibit better cycle performance. Examples 1-1 to 1-8 show that selecting the functionalized carbon nanotubes provided in this application results in lithium-ion batteries with excellent cycle performance.

[0156] Referring to Table 2, it can be seen from Examples 1-1, 2-1 to 2-6 that when the functionalization degree of the functionalized carbon nanotubes is within the range of this application, the resulting lithium-ion battery has better cycle performance.

[0157] The aspect ratio, length, tube diameter, and specific surface area of ​​functionalized carbon nanotubes typically affect the performance of lithium-ion batteries. Referring to Table 3, it can be seen from Examples 1-1, 3-1 to 3-5 that when the aspect ratio, length, tube diameter, and specific surface area of ​​the functionalized carbon nanotubes are within the range of this application, the resulting lithium-ion batteries have good cycle performance.

[0158] The type of manganese-containing active material usually affects the performance of lithium-ion batteries. Referring to Table 4, it can be seen from Examples 1-1, 4-1 to 4-4 that when the manganese-containing active material provided in this application is selected, the resulting lithium-ion battery has good cycle performance.

[0159] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A cathode material, wherein, It includes a manganese-containing active material and functionalized carbon nanotubes, wherein the surface of the functionalized carbon nanotubes includes lone pairs of electrons, and the mass ratio of the functionalized carbon nanotubes to the manganese-containing active material is 0.0005:1-0.004:1; wherein the functionalized carbon nanotubes include aminated carbon nanotubes.

2. The cathode material according to claim 1, wherein, The functionalization degree of the functionalized carbon nanotubes is 0.1%-6%.

3. The cathode material according to claim 1, wherein, The aspect ratio of the functionalized carbon nanotubes is 200-20000.

4. The cathode material according to claim 1, wherein, The functionalized carbon nanotubes have a diameter of 1 nm to 100 nm.

5. The cathode material according to claim 1, wherein, The functionalized carbon nanotubes have a length of 0.1 μm-50 μm.

6. The cathode material according to claim 1, wherein, The functionalized carbon nanotubes have a specific surface area of ​​50 m². 2 / g-2000m 2 / g.

7. The cathode material according to claim 1, wherein, The manganese-containing active material includes particles with a Dv50 of 50nm-99nm, which can be embedded in the lumen of the functionalized carbon nanotubes.

8. The cathode material according to claim 1, wherein, The manganese-containing active material includes LiCo. x1 Mn y1 Ni 1-x1- y1 O2, x2 Li[Li 1 / 3 Mn 2 / 3 ]O 2(1-x2) LiMO2, LiMn2O4, LiNi 0.5 Mn 1.5 At least one of O4, wherein 0 < x1 < 1, 0 < y1 < 1, 0 < x1 + y1 < 1, 0 ≤ x2 ≤ 1, and M is Ni, Co, or Mn.

9. A positive electrode sheet comprising a positive electrode material layer, said positive electrode material layer comprising the positive electrode material according to any one of claims 1-8, wherein, Based on the mass of the cathode material layer, the mass percentage of the manganese-containing active material is 95.7%-96.05%, and the mass percentage of the functionalized carbon nanotubes is 0.05%-0.4%.

10. A secondary battery comprising the positive electrode sheet as described in claim 9.

11. A battery module comprising the secondary battery of claim 10.

12. A battery pack comprising the battery module of claim 11.

13. An electrical device comprising the secondary battery of claim 10, the battery module of claim 11, or the battery pack of claim 12.

Images