Method for manufacturing a heterostructure material, secondary battery, and electric device

Abstract

This application discloses a method for preparing a heterostructure material, a secondary battery, and an electrical device, relating to the field of battery technology. The secondary battery includes a positive electrode, a negative electrode, and an electrolyte; wherein the negative electrode includes a carbon-based material and a heterostructure material, and the heterostructure material contains at least two semiconductor materials, with the difference in valence band top energies between the two semiconductor materials being greater than 2 eV. The secondary battery of this application can broaden the full-temperature-range fast-charging window while also maintaining long-cycle performance.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a method for preparing a heterogeneous structure material, a secondary battery, and an electrical device. Background Technology

[0002] In recent years, with the increasing demand for clean energy, rechargeable batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields. To improve user experience and shorten charging time, higher requirements have been placed on the fast-charging performance of rechargeable batteries. Summary of the Invention

[0003] This application is made in view of the above-mentioned issues, and its purpose is to provide a method for preparing heterostructure materials, a secondary battery and an electrical device that can broaden the full-temperature-range fast charging window of the secondary battery while taking into account long-cycle performance.

[0004] To achieve the above objectives, embodiments of this application provide a method for preparing a heterogeneous structural material, a secondary battery, and an electrical device.

[0005] In a first aspect, embodiments of this application propose a secondary battery, including a positive electrode, a negative electrode, and an electrolyte; wherein the negative electrode includes a carbon-based material and a heterostructure material, the heterostructure material contains at least two semiconductor materials, and the difference in valence band top energies between the two semiconductor materials is greater than 2 eV.

[0006] Therefore, in the technical solution of this application embodiment, the negative electrode includes a carbon-based material and a heterostructure material. On the one hand, the difference in valence band top energy of at least two semiconductor materials in the heterostructure material is greater than 2 eV. When the heterostructure material comes into contact with the carbon-based material, the energy bands spontaneously rearrange at the interface, causing charge redistribution and bringing the Fermi level to equilibrium. In this process, the electrons and holes move in opposite directions, thereby forming a built-in electric field. There is a new channel for electrons to migrate from semiconductor materials with high valence band top energy to semiconductor materials with low valence band top energy. This channel has a low barrier height, which is beneficial for the transport of lithium ions in the carbon-based material and improves the fast-charging performance of the secondary battery. On the other hand, the multiple semiconductor materials in the heterostructure material can participate in the electrode reaction, compensate for the loss of carbon-based material, reduce the impact of the addition of heterostructure material on the capacity of the secondary battery, improve the energy density, and improve the cycle performance of the secondary battery. This can broaden the full-temperature-range fast-charging window of the secondary battery while taking into account long-cycle performance.

[0007] In any embodiment, the semiconductor material is selected from any one of SnO2, ZnS, SnS, Sb2S3, ZnO, and CuS. Using the above-mentioned semiconductor materials to form a heterostructure material can broaden the fast-charging window of the secondary battery.

[0008] In any embodiment, the heterostructure material includes at least one of SnO2-ZnS heterostructure material and SnO2-Sb2S3 heterostructure material. Using the above-mentioned heterostructure material can broaden the fast-charging window of the secondary battery.

[0009] In any embodiment, the heterostructure material is a SnO2-ZnS heterostructure material, and the mass ratio of SnO2 to ZnS is 1:(1-5). Within this range, the mass ratio of SnO2 to ZnS can improve the fast-charging performance of the lithium-ion battery.

[0010] In any embodiment, the carbon-based material includes at least one of artificial graphite, natural graphite, and hard carbon. Using the above-mentioned carbon-based material can broaden the fast-charging window of the secondary battery and improve its cycle performance; and / or,

[0011] The Dv50 of the carbon-based material is 5μm to 50μm. With a Dv50 within this range, the fast-charging window of the secondary battery can be widened, improving its cycle performance; and / or,

[0012] The Dv50 of the heterostructure material is 1 μm to 10 μm. The particle size of the heterostructure material within this range can widen the fast-charging window of the secondary battery and improve its cycle performance. Optionally, the Dv50 of the heterostructure material is 1 μm to 5 μm.

[0013] In any embodiment, the negative electrode includes a current collector and a first active material layer disposed on the current collector. The first active material layer includes a carbon-based material and a heterostructure material, and the carbon-based material and the heterostructure material in the first active material layer correspond to a first carbon-based material and a first heterostructure material. Mixing the first carbon-based material and the first heterostructure material to form a single-layer active material layer on the current collector can broaden the full-temperature-range fast-charging window while also ensuring long-cycle performance. The structure and fabrication of the negative electrode are also relatively simple.

[0014] In any embodiment, in the first active material layer, with the total mass of the first carbon-based material and the first heterostructure material being 100%, the mass percentage of the first heterostructure material is less than or equal to 5%. When the mass percentage of the first heterostructure material is within this range, the fast-charging window of the secondary battery can be widened, further improving the cycle performance of the secondary battery.

[0015] In any embodiment, the negative electrode includes a current collector and a second active material layer and an additive layer sequentially stacked on the current collector in a direction away from the current collector; wherein, the second active material layer includes a carbon-based material, and the carbon-based material in the second active material layer is a second carbon-based material; the additive layer includes a heterostructure material, and the heterostructure material in the additive layer is a second heterostructure material. By providing an additive layer containing a second heterostructure material on the surface of the second active material layer, the generated electric field can accelerate the ion transport rate at the solid-liquid interface, thus widening the fast-charging window of the secondary battery.

[0016] In any embodiment, a third active material layer is disposed on the side of the additive layer away from the second active material layer. The third active material layer comprises a carbon-based material, and the carbon-based material in the third active material layer is a third carbon-based material; wherein, the Dv50 of the second carbon-based material is greater than the Dv50 of the third carbon-based material. The second active material layer containing the second carbon-based material, the additive layer containing the second heterostructure material, and the third active material layer containing the third carbon-based material are sequentially stacked on the current collector. Utilizing the electric field effect, the solid-phase kinetics of the second and third active material layers are directionally increased, enhancing the ion transport capability at the solid-phase interface. Simultaneously, the particle size matching of the second and third carbon-based materials can widen the fast-charging window of the secondary battery and improve its cycle performance. Optionally, the initial lithium intercalation capacity of the second carbon-based material is greater than that of the third carbon-based material. The matching of the specific capacities of the second and third carbon-based materials can widen the fast-charging window of the secondary battery and improve its cycle performance.

[0017] In any embodiment, the thickness ratio of the additive layer to the second active material layer is (0.01 to 0.1):1. This thickness ratio can widen the fast-charging window of the secondary battery and improve its cycle performance.

[0018] In any embodiment, the negative electrode includes a current collector and a fourth active material layer and a fifth active material layer sequentially stacked on the current collector in a direction away from the current collector; wherein, the fourth active material layer includes a carbon-based material and a heterostructure material, and the carbon-based material and the heterostructure material in the fourth active material layer correspond to a fourth carbon-based material and a third heterostructure material, and the fifth active material layer includes a carbon-based material, and the carbon-based material in the fifth active material layer is a fifth carbon-based material; wherein, the Dv50 of the fourth carbon-based material is greater than the Dv50 of the fifth carbon-based material. A fourth active material layer containing a fourth carbon-based material and a heterostructure material, and a fifth active material layer containing a fifth carbon-based material are sequentially stacked on a current collector. Utilizing the electric field effect, the solid-state kinetics of the fourth active material layer are directionally increased. Simultaneously, the particle size matching of the fourth and fifth carbon-based materials can widen the fast-charging window of the secondary battery and improve its cycle performance. Optionally, the initial lithium intercalation capacity of the fourth carbon-based material is greater than that of the fifth carbon-based material. This matching of the specific capacities of the fourth and fifth carbon-based materials can widen the fast-charging window of the secondary battery and improve its cycle performance.

[0019] In any embodiment, in the fourth active material layer, with the total mass of the fourth carbon-based material and the third heterostructure material being 100%, the mass percentage of the third heterostructure material is 0.1% to 5%. Within this range, the mass percentage of the third heterostructure material can broaden the fast-charging window of the secondary battery and improve its cycle performance.

[0020] In any embodiment, the second carbon-based material satisfies at least one of the following conditions:

[0021] The specific surface area of ​​the second carbon-based material is 1.5 m². 2 / g~3m 2 / g;

[0022] The initial lithium intercalation capacity of the second carbon-based material is 380 mAh / g to 384 mAh / g;

[0023] The Dv50 of the second carbon-based material is 13μm to 30μm.

[0024] The second carbon-based material satisfies at least one of the above conditions and can have a long lifespan.

[0025] In any embodiment, the third carbon-based material satisfies at least one of the following conditions:

[0026] The specific surface area of ​​the third carbon-based material is 0.5 m². 2 / g~1.2m2 / g;

[0027] The initial lithium intercalation capacity of the third carbon-based material is 360mAh / g to 378mAh / g;

[0028] The Dv50 of the third carbon-based material is 5μm to 13μm.

[0029] The third carbon-based material satisfies at least one of the above conditions and can have fast charging performance.

[0030] In any embodiment, the fourth carbon-based material satisfies at least one of the following conditions:

[0031] The specific surface area of ​​the fourth carbon-based material is 1.5 m². 2 / g~3m 2 / g;

[0032] The initial lithium intercalation capacity of the fourth carbon-based material is 380 mAh / g to 384 mAh / g;

[0033] The Dv50 of the fourth carbon-based material is 13μm to 30μm.

[0034] The fourth carbon-based material satisfies at least one of the above conditions and can have a long lifespan.

[0035] In any embodiment, the fifth carbon-based material satisfies at least one of the following conditions:

[0036] The specific surface area of ​​the fifth carbon-based material is 0.5 m². 2 / g~1.2m 2 / g;

[0037] The initial lithium intercalation capacity of the fifth carbon-based material is 360 mAh / g to 378 mAh / g;

[0038] The Dv50 of the fifth carbon-based material is 5μm to 13μm.

[0039] The fifth carbon-based material satisfies at least one of the above conditions and can have fast charging performance.

[0040] Secondly, embodiments of this application provide an electrical device including a secondary battery according to the first aspect of this application.

[0041] Thirdly, embodiments of this application propose a method for preparing heterostructured materials, comprising the following steps:

[0042] A mixture is obtained by mixing multiple semiconductor materials; wherein, among the multiple semiconductor materials, the difference in valence band top energy between at least two semiconductor materials is greater than 2 eV;

[0043] The mixture is then combined with an ionic liquid and a dispersant to obtain a dispersion.

[0044] The dispersion was dried to obtain a heterostructured material.

[0045] By mixing multiple semiconductor materials and then mixing them with ionic liquids and dispersants, the negative electrode groups of the ionic liquids can be used to uniformly disperse the multiple semiconductor materials in the dispersant. After drying, a heterostructure material is obtained. The preparation method is simple. The obtained heterostructure material can be used as a negative electrode sheet to broaden the full-temperature-range fast charging window of secondary batteries, while also taking into account long cycle performance.

[0046] In any embodiment, in the step of mixing multiple semiconductor materials to obtain a mixture: among the multiple semiconductor materials, the Dv50 of the semiconductor material with a high valence band top energy is less than the Dv50 of the semiconductor material with a low valence band top energy. Using the semiconductor material with the aforementioned Dv50 allows the semiconductor material with a high valence band top energy to adhere to the semiconductor material with a low valence band top energy, improving the performance of the resulting heterostructure material; and / or,

[0047] The various semiconductor materials include at least two of SnO2, ZnS, Sb2S3, ZnO, and CuS. Using these semiconductor materials to prepare heterostructure materials for use as negative electrode plates can broaden the fast-charging window of secondary batteries.

[0048] In any embodiment, in the step of mixing multiple semiconductor materials to obtain a mixture, the multiple semiconductor materials include SnO2 and ZnS. Using SnO2 and ZnS to prepare a SnO2-ZnS heterostructure material for use as a negative electrode can broaden the fast-charging window of a secondary battery.

[0049] In any embodiment, the Dv50 of SnO2 is 1 μm to 20 μm. A Dv50 of SnO2 within this range can improve the performance of the resulting heterostructure material; and / or,

[0050] The Dv50 of ZnS ranges from 0.1 μm to 5 μm. Within this range, the Dv50 of ZnS can improve the properties of the resulting heterostructured materials; and / or,

[0051] The ratio of Dv50 of SnO2 to Dv50 of ZnS is greater than or equal to 4:1. Within this range, the ratio of Dv50 of SnO2 to Dv50 of ZnS allows ZnS to adhere more fully to SnO2, thereby improving the performance of the resulting heterostructure material.

[0052] In any embodiment, in the step of mixing the mixture with an ionic liquid and a dispersant to obtain a dispersion: the ionic liquid includes an imidazole-based ionic liquid with 3 to 8 carbon atoms. Using the above-mentioned ionic liquid can make the dispersion of various semiconductor materials in the dispersion more uniform, improving the performance of the obtained heterostructure material; and / or,

[0053] In the step of mixing the mixture with an ionic liquid and a dispersant to obtain a dispersion, the dispersant includes at least one of water and ethanol. Using the above-mentioned dispersant can make the dispersion of various semiconductor materials in the dispersion more uniform, improving the performance of the obtained heterostructure material; and / or,

[0054] The mixing temperature is less than or equal to 80°C. 。 Mixing temperatures within this range can improve the performance of the resulting heterostructured material. Optionally, the mixing temperature is 40°C to 60°C, which can improve mixing efficiency while simultaneously enhancing the performance of the resulting heterostructured material. Attached Figure Description

[0055] Figure 1 This is a schematic diagram illustrating the principle of accelerated ion transport according to one embodiment of this application.

[0056] Figure 2 This is a schematic diagram of the SnO2-ZnS heterostructure material according to one embodiment of this application.

[0057] Figure 3 This is a structural simulation diagram of the SnO2-ZnS heterostructure material according to one embodiment of this application.

[0058] Figure 4 This is a scanning electron microscope (SEM) image of the SnO2-ZnS heterostructure material prepared in Example 1 of this application.

[0059] Figure 5 These are capacity graphs of the secondary batteries of Embodiment 1, Embodiment 2 and Comparative Example 1 of this application at different temperatures.

[0060] Figure 6 This is a cycle performance graph of the secondary batteries of Embodiment 1, Embodiment 2 and Comparative Example 1 of this application at 25°C.

[0061] Figure 7 This is a cycle performance diagram of the secondary batteries of Embodiment 1, Embodiment 2 and Comparative Example 1 of this application at 45°C.

[0062] Figure 8 This is a schematic diagram of a secondary battery according to one embodiment of this application.

[0063] Figure 9 yes Figure 8An exploded view of a secondary battery according to one embodiment of this application is shown.

[0064] Figure 10 This is a schematic diagram of a battery module according to one embodiment of this application.

[0065] Figure 11 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0066] Figure 12 yes Figure 11 An exploded view of a battery pack according to one embodiment of this application is shown.

[0067] Figure 13 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0068] Explanation of reference numerals in the attached figures:

[0069] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Secondary battery; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0070] The following detailed description, with appropriate reference to the accompanying drawings, discloses the methods for preparing heterogeneous structural materials, embodiments of secondary batteries, and electrical devices of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually 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.

[0071] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0072] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0073] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0074] 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.

[0075] 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.

[0076] In recent years, with the increasing demand for clean energy, rechargeable batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields. To improve user experience and shorten charging time, higher requirements have been placed on the fast-charging performance of rechargeable batteries.

[0077] Based on this, this application proposes a method for preparing heterogeneous structural materials, a secondary battery, and an electrical device.

[0078] In a first aspect, embodiments of this application propose a secondary battery, including a positive electrode, a negative electrode, and an electrolyte; wherein the negative electrode includes a carbon-based material and a heterostructure material, the heterostructure material contains at least two semiconductor materials, and the difference in valence band top energies between the two semiconductor materials is greater than 2 eV.

[0079] Therefore, in the technical solution of this application embodiment, the negative electrode includes a carbon-based material and a heterostructure material. On the one hand, the difference in valence band top energy between at least two semiconductor materials in the heterostructure material is greater than 2 eV. When the heterostructure material comes into contact with the carbon-based material, the energy bands spontaneously rearrange at the interface, causing a redistribution of charge, so that its Fermi level reaches equilibrium. In this case, the movement directions of electrons and holes are opposite, thereby forming a built-in electric field. There is a new channel for electrons to migrate from the semiconductor material with high valence band top energy to the semiconductor material with low valence band top energy (see [link]). Figure 1 This channel has a low barrier height, which is beneficial for the transport of lithium ions in carbon-based materials and improves the fast-charging performance of secondary batteries. On the other hand, various semiconductor materials in the heterostructure material can participate in the electrode reaction, compensate for the loss of carbon-based materials, reduce the impact of the addition of heterostructure materials on the capacity of secondary batteries, improve energy density, and improve the cycle performance of secondary batteries. Thus, it can broaden the full-temperature-range fast-charging window of secondary batteries while taking into account long-cycle performance.

[0080] It is understood that the heterostructure material contains at least two semiconductor materials, and the difference in valence band top energy between the two semiconductor materials is greater than 2eV. This means that when the heterostructure material is composed of two semiconductor materials, the difference in valence band top energy between the two semiconductor materials is greater than 2eV; when the heterostructure material is composed of more than two semiconductor materials, as long as one of the differences in valence band top energy between any two semiconductor materials is greater than 2eV, the other differences can be greater than 2eV, equal to 2eV, or less than 2eV.

[0081] In any embodiment, the semiconductor material is selected from any one of SnO2, ZnS, SnS, Sb2S3, ZnO, and CuS. Using the above-mentioned semiconductor materials to form a heterostructure material can broaden the fast-charging window of the secondary battery. The heterostructure material can be composed of any combination of semiconductor materials selected from SnO2, ZnS, SnS, Sb2S3, ZnO, and CuS.

[0082] In any embodiment, the heterostructure material includes at least one selected from SnO2-ZnS heterostructure material and SnO2-Sb2S3 heterostructure material. Using the above-mentioned heterostructure material can broaden the fast-charging window of the secondary battery. The heterostructure material can be SnO2-ZnS heterostructure material, SnO2-Sb2S3 heterostructure material, or a combination of SnO2-ZnS heterostructure material and SnO2-Sb2S3 heterostructure material.

[0083] In any embodiment, the heterostructure material is a SnO2-ZnS heterostructure material, and the mass ratio of SnO2 to ZnS is 1:(1-5). Within this range, the fast-charging window of the secondary battery can be widened. The mass ratio of SnO2 to ZnS can be 1:1, 1:2, 1:3, 1:4, or 1:5.

[0084] In any embodiment, the carbon-based material includes at least one of artificial graphite, natural graphite, and hard carbon. Using the aforementioned carbon-based material can broaden the fast-charging window of the secondary battery and improve its cycle performance. The carbon-based material can be any one or any combination of artificial graphite, natural graphite, and hard carbon.

[0085] In any embodiment, the Dv50 of the carbon-based material is 5μm to 50μm. The Dv50 of the carbon-based material within this range can widen the fast-charging window of the secondary battery and improve its cycle performance. The Dv50 of the carbon-based material can be 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, or 50μm.

[0086] In any embodiment, the Dv50 of the heterostructure material is 1 μm to 10 μm. A Dv50 within this range can widen the fast-charging window of the secondary battery and improve its cycle performance. The Dv50 of the heterostructure material can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. Optionally, a Dv50 of 1 μm to 5 μm can further widen the fast-charging window of the secondary battery and improve its cycle performance.

[0087] In any embodiment, the negative electrode includes a current collector and a first active material layer disposed on the current collector. The first active material layer includes the carbon-based material and the heterostructure material, and the carbon-based material and the heterostructure material in the first active material layer correspond to the first carbon-based material and the first heterostructure material, respectively. Mixing the first carbon-based material and the first heterostructure material to form a single-layer active material layer on the current collector can broaden the full-temperature-range fast-charging window while maintaining long-cycle performance. The structure and fabrication of the negative electrode are also relatively simple.

[0088] In any embodiment, in the first active material layer, with the total mass of the first carbon-based material and the first heterostructure material being 100%, the mass percentage of the first heterostructure material is less than or equal to 5%. Having the mass percentage of the first heterostructure material within this range can broaden the fast-charging window of the secondary battery and further improve its cycle performance. In the first active material layer, with the total mass of the first carbon-based material and the first heterostructure material being 100%, the mass percentage of the first heterostructure material can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%.

[0089] In any embodiment, the negative electrode includes a current collector and a second active material layer and an additive layer sequentially stacked on the current collector in a direction away from the current collector; wherein, the second active material layer includes a carbon-based material, and the carbon-based material in the second active material layer is a second carbon-based material; the additive layer includes a heterostructure material, and the heterostructure material in the additive layer is a second heterostructure material. By providing an additive layer containing a second heterostructure material on the surface of the second active material layer, the generated electric field can accelerate the ion transport rate at the solid-liquid interface, thus widening the fast-charging window of the secondary battery.

[0090] In any embodiment, a third active material layer is disposed on the side of the additive layer away from the second active material layer. The third active material layer comprises a carbon-based material, and the carbon-based material in the third active material layer is a third carbon-based material; wherein, the Dv50 of the second carbon-based material is greater than the Dv50 of the third carbon-based material. The second active material layer containing the second carbon-based material, the additive layer containing the second heterostructure material, and the third active material layer containing the third carbon-based material are sequentially stacked on the current collector. Utilizing the electric field effect, the solid-phase kinetics of the second and third active material layers are directionally increased, enhancing the ion transport capability at the solid-phase interface. Simultaneously, the particle size matching of the second and third carbon-based materials can broaden the fast-charging window of the secondary battery and improve its cycle performance. Optionally, the initial lithium intercalation capacity of the second carbon-based material is greater than that of the third carbon-based material. The matching of the specific capacities of the second and third carbon-based materials can broaden the fast-charging window of the secondary battery and improve its cycle performance.

[0091] In any embodiment, the thickness ratio of the additive layer to the second active material layer is (0.01 to 0.1):1. This thickness ratio can widen the fast-charging window of the secondary battery and improve its cycle performance. The thickness ratio of the additive layer to the first active material layer can be 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, or 0.1:1.

[0092] In any embodiment, the negative electrode includes a current collector and a fourth active material layer and a fifth active material layer sequentially stacked on the current collector in a direction away from the current collector; wherein, the fourth active material layer includes a carbon-based material and a heterostructure material, and the carbon-based material and the heterostructure material in the fourth active material layer correspond to a fourth carbon-based material and a third heterostructure material, and the fifth active material layer includes a carbon-based material, and the carbon-based material in the fifth active material layer is a fifth carbon-based material; wherein, the Dv50 of the fourth carbon-based material is greater than the Dv50 of the fifth carbon-based material. A fourth active material layer containing a fourth carbon-based material and a third heterostructure material, and a fifth active material layer containing a fifth carbon-based material are sequentially stacked on a current collector. Utilizing the electric field effect, the solid-state kinetics of the fourth active material layer are directionally increased. Simultaneously, the particle size matching of the fourth and fifth carbon-based materials can widen the fast-charging window of the secondary battery and improve its cycle performance. Optionally, the initial lithium intercalation capacity of the fourth carbon-based material is greater than that of the fifth carbon-based material. This matching of the specific capacities of the fourth and fifth carbon-based materials can widen the fast-charging window of the secondary battery and improve its cycle performance.

[0093] In any embodiment, in the fourth active material layer, with the total mass of the fourth carbon-based material and the third heterostructure material being 100%, the mass percentage of the third heterostructure material is 0.1% to 5%. This mass percentage range can broaden the fast-charging window of the secondary battery and improve its cycle performance. In the fourth active material layer, with the total mass of the fourth carbon-based material and the third heterostructure material being 100%, the mass percentage of the third heterostructure material can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%.

[0094] In any embodiment, the second carbon-based material satisfies at least one of the following conditions:

[0095] The specific surface area of ​​the second carbon-based material is 1.5 m². 2 / g~3m 2 / g;

[0096] The initial lithium intercalation capacity of the second carbon-based material is 380 mAh / g to 384 mAh / g;

[0097] The Dv50 of the second carbon-based material is 13μm to 30μm.

[0098] The second carbon-based material satisfies at least one of the above conditions and can exhibit a long lifespan. The second carbon-based material may satisfy one, two, or all three of the above conditions; the specific surface area of ​​the second carbon-based material may be 1.5 m². 2 / g, 1.8m 2 / g、2m 2 / g, 2.2m 2 / g, 2.5m 2 / g, 2.8m 2 / g or 3m 2 / g; the initial lithium insertion capacity of the second carbon-based material can be 380mAh / g, 381mAh / g, 382mAh / g, 383mAh / g or 384mAh / g; the Dv50 of the second carbon-based material can be 13μm, 15μm, 18μm, 20μm, 23μm, 25μm, 28μm or 30μm.

[0099] In any embodiment, the third carbon-based material satisfies at least one of the following conditions:

[0100] The specific surface area of ​​the third carbon-based material is 0.5 m². 2 / g~1.2m 2 / g;

[0101] The initial lithium intercalation capacity of the third carbon-based material is 360mAh / g to 378mAh / g;

[0102] The Dv50 of the third carbon-based material is 5μm to 13μm.

[0103] The third carbon-based material satisfies at least one of the above conditions and can exhibit fast-charging performance. The third carbon-based material may satisfy one, two, or all three of the above conditions; the specific surface area of ​​the third carbon-based material may be 0.5 m². 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g, 1m 2 / g, 1.1m 2 / g or 1.2m 2 / g; the initial lithium insertion capacity of the third carbon-based material can be 360mAh / g, 362mAh / g, 364mAh / g, 366mAh / g, 368mAh / g, 370mAh / g, 372mAh / g, 374mAh / g, 376mAh / g or 378mAh / g; the Dv50 of the third carbon-based material can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm or 13μm.

[0104] In any embodiment, the fourth carbon-based material satisfies at least one of the following conditions:

[0105] The specific surface area of ​​the fourth carbon-based material is 1.5 m². 2 / g~3m 2 / g;

[0106] The initial lithium intercalation capacity of the fourth carbon-based material is 380 mAh / g to 384 mAh / g;

[0107] The Dv50 of the fourth carbon-based material is 13μm to 30μm.

[0108] The fourth carbon-based material satisfies at least one of the above conditions and can exhibit a long lifespan. The fourth carbon-based material may satisfy one, two, or all three of the above conditions; the specific surface area of ​​the fourth carbon-based material can be 1.5 m². 2 / g, 1.8m 2 / g、2m 2 / g, 2.2m 2 / g, 2.5m 2 / g, 2.8m 2 / g or 3m 2 / g; the initial lithium insertion capacity of the fourth carbon-based material can be 380mAh / g, 381mAh / g, 382mAh / g, 383mAh / g or 384mAh / g; the Dv50 of the fourth carbon-based material can be 13μm, 15μm, 18μm, 20μm, 23μm, 25μm, 28μm or 30μm.

[0109] In any embodiment, the fifth carbon-based material satisfies at least one of the following conditions:

[0110] The specific surface area of ​​the fifth carbon-based material is 0.5 m². 2 / g~1.2m 2 / g;

[0111] The initial lithium intercalation capacity of the fifth carbon-based material is 360 mAh / g to 378 mAh / g;

[0112] The Dv50 of the fifth carbon-based material is 5μm to 13μm.

[0113] The fifth carbon-based material satisfies at least one of the above conditions and can exhibit fast-charging performance. The fifth carbon-based material may satisfy one, two, or all three of the above conditions; the specific surface area of ​​the fifth carbon-based material may be 0.5 m². 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g, 1m 2 / g, 1.1m 2 / g or 1.2m 2 / g; the initial lithium insertion capacity of the fifth carbon-based material can be 360mAh / g, 362mAh / g, 364mAh / g, 366mAh / g, 368mAh / g, 370mAh / g, 372mAh / g, 374mAh / g, 376mAh / g or 378mAh / g; the Dv50 of the fifth carbon-based material can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm or 13μm.

[0114] Secondly, embodiments of this application provide an electrical device including a secondary battery according to the first aspect of this application.

[0115] Thirdly, embodiments of this application propose a method for preparing heterostructured materials, comprising the following steps:

[0116] A mixture is obtained by mixing multiple semiconductor materials; wherein, among the multiple semiconductor materials, the difference in valence band top energy between at least two semiconductor materials is greater than 2 eV;

[0117] The mixture is then combined with an ionic liquid and a dispersant to obtain a dispersion.

[0118] The dispersion was dried to obtain a heterostructured material.

[0119] By mixing multiple semiconductor materials and then mixing them with ionic liquids and dispersants, the negative electrode groups of the ionic liquids can be used to uniformly disperse the multiple semiconductor materials in the dispersant. After drying, a heterostructure material is obtained. The preparation method is simple. The obtained heterostructure material can be used as a negative electrode sheet to broaden the full-temperature-range fast charging window of secondary batteries, while also taking into account long cycle performance.

[0120] It should be noted that in the step of mixing the mixture with the ionic liquid and the dispersant to obtain a dispersion, the amount of the ionic liquid and the dispersant is sufficient to disperse the mixture in the liquid to form a dispersion; in the step of drying the dispersion to obtain a heterostructure material, the drying can be vacuum drying to further improve the performance of the heterostructure material; for the use of the heterostructure material, a grinding process can be performed on the heterostructure material.

[0121] In any embodiment, in the step of mixing multiple semiconductor materials to obtain a mixture, the Dv50 of the semiconductor material with a high valence band top energy is less than the Dv50 of the semiconductor material with a low valence band top energy. Using the semiconductor material with the aforementioned Dv50 allows the semiconductor material with a high valence band top energy to adhere to the semiconductor material with a low valence band top energy, thereby improving the performance of the resulting heterostructure material.

[0122] In any embodiment, in the step of mixing multiple semiconductor materials to obtain a mixture, the multiple semiconductor materials include at least two selected from SnO2, ZnS, SnS, Sb2S3, ZnO, and CuS. Using the above-mentioned semiconductor materials to prepare a heterostructure material for use as a negative electrode can broaden the fast-charging window of the secondary battery. The multiple semiconductor materials can be any combination of SnO2, ZnS, SnS, Sb2S3, ZnO, and CuS.

[0123] In any embodiment, the step of mixing multiple semiconductor materials to obtain a mixture includes SnO2 and ZnS. SnO2-ZnS heterostructure materials are prepared using SnO2 and ZnS (see [link to documentation]). Figures 2 to 4 ), used for the negative electrode, can widen the fast charging window of the secondary battery.

[0124] In any embodiment, the Dv50 of SnO2 is 1 μm to 20 μm. Having a Dv50 of SnO2 within this range can improve the performance of the resulting heterostructure material. The Dv50 of SnO2 can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm.

[0125] In any embodiment, the Dv50 of ZnS is 0.1 μm to 5 μm. A Dv50 of ZnS within this range can improve the performance of the resulting heterostructure material. The Dv50 of ZnS can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm.

[0126] In any embodiment, the ratio of Dv50 of SnO2 to Dv50 of ZnS is greater than or equal to 4:1. Within this range, the ratio of Dv50 of SnO2 to Dv50 of ZnS allows ZnS to adhere more fully to SnO2, improving the performance of the resulting heterostructure material. The ratio of Dv50 of SnO2 to Dv50 of ZnS can be 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1.

[0127] In any embodiment, the mass ratio of SnO2 to ZnS is 1:(1 to 5). Within this range, the mass ratio of SnO2 to ZnS allows ZnS to adhere sufficiently to SnO2, thereby improving the performance of the resulting heterostructure material.

[0128] In any embodiment, in the step of mixing the mixture with an ionic liquid and a dispersant to obtain a dispersion, the ionic liquid includes an imidazole-based ionic liquid with 3 to 8 carbon atoms. Using the above-mentioned ionic liquid allows for more uniform dispersion of various semiconductor materials in the dispersion, improving the performance of the resulting heterostructure material. The ionic liquid can be any one or any combination of 1-pentyl-2,3-dimethylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, and 1-hexyl-2,3-dimethylimidazolium chloride.

[0129] In any embodiment, in the step of mixing the mixture with an ionic liquid and a dispersant to obtain a dispersion, the dispersant includes at least one of water and ethanol. Using the above-mentioned dispersant can make the dispersion of various semiconductor materials in the dispersion more uniform, thereby improving the performance of the obtained heterostructure material. The dispersant can be water, ethanol, or an aqueous solution of ethanol.

[0130] In any embodiment, the mixing temperature is less than or equal to 80°C. 。 Mixing temperatures within this range can improve the performance of the resulting heterostructured material. The mixing temperature can be 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, or 80℃. Optionally, a mixing temperature of 40℃ to 60℃ can improve both mixing efficiency and the performance of the resulting heterostructured material.

[0131] 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.

[0132] In one embodiment of this application, a secondary battery is provided.

[0133] 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.

[0134] [Positive electrode plate]

[0135] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including the positive electrode active material of the first aspect of this application.

[0136] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0137] 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 a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0138] In some embodiments, when the secondary battery is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as 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 include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi).1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0139] In some embodiments, the positive electrode film layer may optionally include 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.

[0140] In some embodiments, the positive electrode film may optionally include 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.

[0141] 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 active 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.

[0142] [Negative electrode plate]

[0143] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0144] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0145] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0146] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0147] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0148] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0149] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0150] [Electrolytes]

[0151] 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.

[0152] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0153] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0154] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0155] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0156] [Isolation membrane]

[0157] 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.

[0158] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0159] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0160] 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.

[0161] 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.

[0162] 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 8 This is an example of a square-structured secondary battery 5.

[0163] In some implementations, refer to Figure 9 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.

[0164] 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.

[0165] Figure 10 This is battery module 4, used as an example. (See reference...) Figure 10 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.

[0166] Optionally, the battery module 4 may also include a housing with a receiving space in which a plurality of secondary batteries 5 are received.

[0167] 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.

[0168] Figure 11 and Figure 12 This is battery pack 1 as an example. (See reference...) Figure 11 and Figure 12The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 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.

[0169] 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.

[0170] As the electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0171] Figure 13 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0172] 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.

[0173] Example

[0174] 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.

[0175] Preparation Example 1

[0176] A method for preparing a heterostructured material includes the following steps:

[0177] SnO2 with a Dv50 of 10 μm and ZnS with a Dv50 of 2 μm were mixed and ground at a mass ratio of 1:1 to obtain a mixture;

[0178] Add the ionic liquid 1-pentyl-2,3-dimethylimidazolium chloride and the dispersant water to the mixture and stir at 60°C to obtain a dispersion;

[0179] The dispersion was vacuum dried and ground to obtain SnO2-ZnS heterostructure material.

[0180] Preparation Example 2

[0181] A method for preparing a heterostructured material includes the following steps:

[0182] SnO2 with a Dv50 of 10 μm and Sb2S3 with a Dv50 of 2 μm were mixed and ground at a mass ratio of 1:1 to obtain a mixture;

[0183] Add the ionic liquid 1-pentyl-2,3-dimethylimidazolium chloride and the dispersant water to the mixture and stir at 60°C to obtain a dispersion;

[0184] The dispersion was vacuum dried and ground to obtain SnO2-Sb2S3 heterostructure material.

[0185] Preparation of secondary batteries

[0186] LiNi, the positive electrode active material 0.6 Co 0.2 Mn 0.2 O2, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97:0.7:2.3. N-methylpyrrolidone (NMP) solvent is added and the mixture is stirred thoroughly to obtain a positive electrode slurry. The positive electrode slurry is coated onto aluminum foil, dried, and cold-pressed to obtain a positive electrode sheet.

[0187] The negative electrode active material, conductive agent carbon black, and binder carboxymethyl cellulose (CMC) are mixed in a weight ratio of 96:2:1. Water is added as a solvent and the mixture is stirred thoroughly to obtain a negative electrode slurry. The negative electrode slurry is coated onto copper foil, dried, and cold-pressed to obtain a negative electrode sheet.

[0188] Ethylene carbonate, diethyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 1:1:1. Lithium hexafluorophosphate (LiPF6) was dissolved in the above solution to obtain an electrolyte. The concentration of LiPF6 in the electrolyte was 1 mol / L.

[0189] A polyethylene film with a thickness of 13 μm was used as the separator.

[0190] The positive electrode, separator, and negative electrode are stacked and wound in sequence to obtain an electrode assembly. The electrode assembly is placed in an outer package, electrolyte is added, and after processes such as encapsulation, settling, formation, and aging, a secondary battery is obtained.

[0191] The parameters of the negative electrode sheets in Examples 1 to 5 and Comparative Examples 1 to 2 of this application are as shown in Table 1, and secondary batteries are prepared accordingly. In Examples 1 to 5 and Comparative Example 2, the negative electrode active material is a carbon-based material and a heterostructure material, and a layer of negative electrode slurry is coated on a copper foil to form a first active material layer. The negative electrode active material in Comparative Example 1 is a carbon-based material. In Comparative Example 2, the difference in valence band top energy between the two semiconductor materials in the NiO-ZnO heterostructure material is less than 2 eV.

[0192] The parameters of the negative electrode sheets in Examples 6 to 11 of this application are as shown in Table 2, and secondary batteries are prepared accordingly. In Examples 6 to 8, a layer of negative electrode slurry with carbon-based negative electrode active material is first coated on the copper foil, and then a layer of negative electrode slurry with heterogeneous structure material is coated on the copper foil, forming a second active material layer and an additive layer that are sequentially stacked on the copper foil in the direction away from the copper foil. In Examples 9 to 11, a layer of negative electrode slurry with carbon-based negative electrode active material is first coated on the copper foil, then a layer of negative electrode slurry with heterogeneous structure material is coated on the copper foil, and then a layer of negative electrode slurry with carbon-based negative electrode active material is coated on the additive layer, forming a third active material layer.

[0193] The parameters of the negative electrode sheets in Examples 12 to 14 of this application are as shown in Table 3 to prepare a secondary battery. A layer of negative electrode slurry with carbon-based material and heterostructure material as negative electrode active material is first coated on the copper foil, and then another layer of negative electrode slurry with carbon-based material as negative electrode active material is coated, forming a fourth active material layer and a fifth active material layer that are sequentially stacked on the copper foil in the direction away from the copper foil.

[0194] Performance testing:

[0195] (1) Fast charging performance test of secondary batteries

[0196] The test was conducted using a blue electric shock tester at a constant temperature.

[0197] Tests at different temperature magnification rates:

[0198] 1) Let stand at 25℃ for 30 minutes;

[0199] 2) 1 / 3C DC (constant current discharge) to 2.5V;

[0200] 3) Change the temperature (-20℃, -15℃, -10℃, -5℃, 0℃, 5℃, 10℃, 15℃), and let it stand for 30 minutes;

[0201] 4) n*C CC (constant current charging) to 4.4V (n=1, 2, 3, 4, 5, 6, 7, 8), with the negative electrode potential less than 0 as the cutoff potential;

[0202] 5) Repeat steps 1 to 4 until all charging rates have been tested;

[0203] 6) Let stand for 30 minutes;

[0204] Full temperature test:

[0205] 1) Let stand at 25℃ for 30 minutes;

[0206] 2) 1 / 3C CC to 4.4V;

[0207] 3) Change the temperature (-20℃~15℃) and let it stand for 30 minutes;

[0208] 4) 1 / 3C DC to 4.4V;

[0209] 5) Repeat steps 1 to 4 until all temperatures have been tested;

[0210] 6) Let stand for 30 minutes.

[0211] (2) Secondary battery capacity test

[0212] Adjust to the specified temperature (25℃, -20℃).

[0213] 1) 1 / 3C CC to 4.4V,

[0214] 2) Adjust the voltage from 1 / 3 DC to 0.5C to 2.5V and record the discharge capacity.

[0215] (3) Cyclic performance test of secondary batteries

[0216] The test subject was subjected to constant current charge and discharge test, with the current being the current step-by-step charging within the charging window (cycle charging SOC: 3-97%, test voltage range: 2.5V~4.4V). The capacity retention rate was recorded for each cycle. The test was stopped when the capacity retention rate was lower than 80%. According to GB / T 31484-2015, the standard cycle life of power batteries for electric vehicles is specified using 0.33C charge and discharge.

[0217] The performance tests of the secondary batteries in Examples 1 to 14 and Comparative Examples 1 to 2 are shown in Table 4; the capacity graphs of the secondary batteries in Examples 1, 2, and Comparative Example 1 at different temperatures, and the cycle performance graphs at 25°C and 45°C are shown in Table 4. Figures 5 to 7 .

[0218]

[0219]

[0220]

[0221]

[0222] As shown in Table 4, compared to Comparative Examples 1 and 2, the maximum charging rates of the secondary batteries in Examples 1 to 14 are improved at -20°C, 5% SOC, -20°C, 95% SOC, 15°C, 5% SOC, and 15°C, 95% SOC, indicating that the full-temperature-range fast-charging window of the secondary battery in this application has been broadened. Meanwhile, as shown in Table 4, the capacity retention rates of the secondary batteries in Examples 1 to 14 are all at a high level after 120 cycles. Figures 5 to 7 It can be seen that the capacity of Examples 1 and 2 at different temperatures is very similar to that of Comparative Example 1, indicating that the cycle performance of the secondary battery of this application is good and basically unaffected. In summary, the negative electrode of the secondary battery of this application includes carbon-based materials and heterostructure materials. The difference in valence band top energy of at least two semiconductor materials in the heterostructure material is greater than 2eV, which can broaden the full-temperature-range fast charging window of the secondary battery while taking into account long cycle performance.

[0223] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A secondary battery, characterized in that, It includes a positive electrode, a negative electrode, and an electrolyte; wherein the negative electrode includes a carbon-based material and a heterostructure material, and the heterostructure material contains at least two semiconductor materials, wherein the difference in valence band top energy between the two semiconductor materials is greater than 2 eV.

2. The secondary battery as described in claim 1, characterized in that, The semiconductor material is selected from any one of SnO2, ZnS, SnS, Sb2S3, ZnO, and CuS.

3. The secondary battery as described in claim 1 or 2, characterized in that, The heterostructure material includes at least one of SnO2-ZnS heterostructure material and SnO2-Sb2S3 heterostructure material.

4. The secondary battery according to any one of claims 1 to 3, characterized in that, The heterostructure material is a SnO2-ZnS heterostructure material, and the mass ratio of SnO2 to ZnS is 1:(1-5).

5. The secondary battery according to any one of claims 1 to 4, characterized in that, The carbon-based material includes at least one of artificial graphite, natural graphite, and hard carbon; and / or, The carbon-based material has a Dv50 of 5 μm to 50 μm; and / or, The Dv50 of the heterostructure material is 1μm to 10μm.

6. The secondary battery according to any one of claims 1 to 5, characterized in that, The negative electrode sheet includes a current collector and a first active material layer disposed on the current collector. The first active material layer includes a carbon-based material and a heterostructure material, and the carbon-based material and the heterostructure material in the first active material layer correspond to the first carbon-based material and the first heterostructure material.

7. The secondary battery as described in claim 6, characterized in that, In the first active material layer, with the total mass of the first carbon-based material and the first heterostructure material being 100%, the mass percentage of the first heterostructure material is less than or equal to 5%.

8. The secondary battery according to any one of claims 1 to 5, characterized in that, The negative electrode includes a current collector and a second active material layer and an additive layer sequentially stacked on the current collector in a direction away from the current collector; wherein, the second active material layer includes a carbon-based material, and the carbon-based material in the second active material layer is a second carbon-based material, and the additive layer includes a heterostructure material, and the heterostructure material in the additive layer is a second heterostructure material.

9. The secondary battery as described in claim 8, characterized in that, A third active material layer is disposed on the side of the additive layer away from the second active material layer. The third active material layer includes a carbon-based material, and the carbon-based material in the third active material layer is a third carbon-based material. The Dv50 of the second carbon-based material is greater than that of the third carbon-based material. Optionally, the initial lithium intercalation capacity of the second carbon-based material is greater than that of the third carbon-based material.

10. The secondary battery as described in claim 8 or 9, characterized in that, The thickness ratio of the additive layer to the second active material layer is (0.01~0.1):

1.

11. The secondary battery according to any one of claims 1 to 5, characterized in that, The negative electrode includes a current collector and a fourth active material layer and a fifth active material layer sequentially stacked on the current collector in a direction away from the current collector; wherein, the fourth active material layer includes a carbon-based material and a heterostructure material, and the carbon-based material and the heterostructure material in the fourth active material layer correspond to a fourth carbon-based material and a third heterostructure material, and the fifth active material layer includes a carbon-based material, and the carbon-based material in the fifth active material layer is a fifth carbon-based material; wherein, the Dv50 of the fourth carbon-based material is greater than the Dv50 of the fifth carbon-based material; optionally, the initial lithium intercalation capacity of the fourth carbon-based material is greater than the initial lithium intercalation capacity of the fifth carbon-based material.

12. The secondary battery as described in claim 11, characterized in that, In the fourth active material layer, with the total mass of the fourth carbon-based material and the third heterostructure material being 100%, the mass percentage of the third heterostructure material is 0.1% to 5%.

13. The secondary battery as described in claim 9 or 10, characterized in that, The second carbon-based material must satisfy at least one of the following conditions: The specific surface area of ​​the second carbon-based material is 1.5 m². 2 / g~3m 2 / g; The initial lithium intercalation capacity of the second carbon-based material is 380 mAh / g to 384 mAh / g; The Dv50 of the second carbon-based material is 13μm to 30μm.

14. The secondary battery as described in claim 9 or 10, characterized in that, The third carbon-based material must satisfy at least one of the following conditions: The specific surface area of ​​the third carbon-based material is 0.5 m². 2 / g~1.2m 2 / g; The initial lithium intercalation capacity of the third carbon-based material is 360mAh / g to 378mAh / g; The Dv50 of the third carbon-based material is 5μm to 13μm.

15. The secondary battery as described in claim 11 or 12, characterized in that, The fourth carbon-based material must satisfy at least one of the following conditions: The specific surface area of ​​the fourth carbon-based material is 1.5 m². 2 / g~3m 2 / g; The initial lithium intercalation capacity of the fourth carbon-based material is 380 mAh / g to 384 mAh / g; The Dv50 of the fourth carbon-based material is 13μm to 30μm.

16. The secondary battery as described in claim 11 or 12, characterized in that, The fifth carbon-based material must satisfy at least one of the following conditions: The specific surface area of ​​the fifth carbon-based material is 0.5 m². 2 / g~1.2m 2 / g; The initial lithium intercalation capacity of the fifth carbon-based material is 360 mAh / g to 378 mAh / g; The Dv50 of the fifth carbon-based material is 5μm to 13μm.

17. An electrical appliance, characterized in that, Includes the secondary battery as described in any one of claims 1 to 16.

18. A method for preparing a heterogeneous structural material, characterized in that, Includes the following steps: A mixture is obtained by mixing multiple semiconductor materials; wherein, among the multiple semiconductor materials, the difference in valence band top energy between at least two semiconductor materials is greater than 2 eV; The mixture is then combined with an ionic liquid and a dispersant to obtain a dispersion. The dispersion was dried to obtain a heterostructured material.

19. The method for preparing heterogeneous structural materials as described in claim 18, characterized in that, In the step of mixing multiple semiconductor materials to obtain a mixture: Among the various semiconductor materials, the Dv50 of the semiconductor material with a high valence band top energy is smaller than that of the semiconductor material with a low valence band top energy; and / or, The various semiconductor materials include at least two of SnO2, ZnS, SnS, Sb2S3, ZnO, and CuS.

20. The method for preparing heterogeneous structural materials as described in claim 18 or 19, characterized in that, In the step of mixing multiple semiconductor materials to obtain a mixture, the multiple semiconductor materials include SnO2 and ZnS.

21. The method for preparing heterogeneous structural materials as described in claim 20, characterized in that, The Dv50 of SnO2 is 1 μm to 20 μm; and / or, ZnS has a Dv50 of 0.1 μm to 5 μm; and / or, The ratio of Dv50 of SnO2 to Dv50 of ZnS is greater than or equal to 4:

1.

22. The method for preparing heterogeneous structural materials according to any one of claims 18 to 21, characterized in that, In the step of mixing the mixture with the ionic liquid and the dispersant to obtain the dispersion: The ionic liquid includes imidazole ionic liquids with 3 to 8 carbon atoms; and / or, The dispersant comprises at least one of water and ethanol; and / or, The mixing temperature is less than or equal to 80°C.

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