Battery monomer and preparation method thereof, battery device, power utilization device and energy storage device

Abstract

The invention provides a battery monomer and a preparation method thereof, a battery device, a power utilization device and an energy storage device, and belongs to the technical field of batteries. The battery monomer comprises a negative pole piece, the negative pole piece comprises a current collector, a first coating and a second coating, the first coating and the second coating are arranged on the same surface of the current collector, the first coating and the second coating are alternately arranged on the surface of the current collector, and the thickness of the first coating is larger than that of the second coating in the first direction; wherein the first direction is perpendicular to the surface of the current collector, the first coating comprises a graphite material, and the second coating comprises a silicon material. The first coatings and the second coatings are alternately arranged on the same surface of the current collector, and the thickness of the first coatings is larger than that of the second coatings in the first direction, so that stress generated by the second coatings in the cold pressing and charging and discharging processes can be effectively dispersed, the probability that silicon particles in the second coatings are broken is reduced, and the service life of the current collector is prolonged. And the structural stability and the cycle performance of the negative pole piece are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a battery monomer, a preparation method, a battery device, a power utilization device and an energy storage device. BACKGROUND

[0002] Energy saving and emission reduction is the key to the sustainable development of society. Rechargeable batteries have the characteristics of storing or releasing energy as needed, and are widely used in various power utilization devices or energy storage systems, and are an important part of promoting energy transformation and sustainable development. For the new energy industry, battery technology is an important factor for its development.

[0003] Due to the high specific capacity of silicon material, using silicon material as negative active material to improve the energy density of the battery has become an industry trend. However, the volume of silicon material is prone to expansion, which will affect the performance of the battery. SUMMARY

[0004] The present application aims to at least solve one of the technical problems in the background art. To this end, one object of the present application is to provide a battery monomer, a preparation method, a battery device, a power utilization device and an energy storage device to improve the structural stability and cycle performance of the negative electrode sheet.

[0005] An embodiment of the first aspect of the present application provides a battery monomer, the battery monomer comprising a negative electrode sheet, the negative electrode sheet comprising a current collector, a first coating layer and a second coating layer, the first coating layer and the second coating layer being arranged on the same surface of the current collector, the first coating layer and the second coating layer being arranged alternately, the thickness of the first coating layer being greater than the thickness of the second coating layer along a first direction; wherein the first direction is perpendicular to the surface of the current collector, the first coating layer comprises a graphite material, and the second coating layer comprises a silicon material.

[0006] In the technical solution of the embodiment of the present application, by arranging the first coating layer and the second coating layer alternately on the same surface of the current collector, and the thickness of the first coating layer being greater than the thickness of the second coating layer along the first direction, the stress generated by the second coating layer during cold pressing and charging and discharging can be effectively dispersed, the probability of the silicon particles in the second coating layer being broken is reduced, and the structural stability and cycle performance of the negative electrode sheet are improved, thereby improving the structural stability and cycle performance of the battery monomer.

[0007] In some embodiments, the ratio S1 of the thickness of the first coating layer to the thickness of the second coating layer satisfies 1

[0008] In some embodiments, the thickness of any two first coating layers is the same, and / or the thickness of any two second coating layers is the same. By setting the thickness of any two first coating layers to be the same, and / or the thickness of any two second coating layers to be the same, the probability of local damage to the negative electrode tab is reduced, and the mechanical strength of the negative electrode tab as a whole is improved.

[0009] In some embodiments, the thickness H1 of the first coating layer satisfies 20 micrometers (um)≤H1≤200 um, and the thickness H2 of the second coating layer satisfies 10 um≤H2≤100 um. By setting the thickness H1 of the first coating layer to satisfy 20 um≤H1≤200 um, and the thickness H2 of the second coating layer to satisfy 10 um≤H2≤100 um, the stress generated by the second coating layer during cold pressing and charging and discharging can be effectively dispersed, and the structural stability and cycle performance of the negative electrode tab are improved.

[0010] In some embodiments, the ratio S2 of the width of the first coating layer to the width of the second coating layer satisfies 1≤S2≤10. By setting the ratio S2 of the width of the first coating layer to the width of the second coating layer to satisfy 1≤S2≤10, the advantages of high specific capacity of the silicon-based material in the second coating layer are retained, the stress generated by the second coating layer during cold pressing and charging and discharging can be effectively dispersed, and the energy density and cycle performance of the negative electrode tab are taken into account.

[0011] In some embodiments, the width of any two first coating layers is the same, and / or the width of any two second coating layers is the same. By setting the width of any two first coating layers to be the same, and / or the width of any two second coating layers to be the same, the probability of local damage to the negative electrode tab is reduced, and the mechanical strength of the negative electrode tab as a whole is improved.

[0012] In some embodiments, the width L1 of the first coating layer satisfies 1 millimeter (mm)≤L1≤50 mm, and the width L2 of the second coating layer satisfies 0.5 mm≤L2≤5 mm. By setting the width L1 of the first coating layer to satisfy 1 mm≤L1≤50 mm, and the width L2 of the second coating layer to satisfy 0.5 mm≤L2≤5 mm, the stress generated by the second coating layer during cold pressing and charging and discharging can be effectively dispersed, and the structural stability and cycle performance of the negative electrode tab are improved.

[0013] In some embodiments, the first coating layer and the second coating layer extend in the width direction of the current collector and are arranged alternately in the length direction of the current collector. By setting the first coating layer and the second coating layer to extend in the width direction of the current collector and to be arranged alternately in the length direction of the current collector, the stress generated by the second coating layer during cold pressing and charging and discharging can be effectively dispersed, the structural stability and cycle performance of the negative electrode tab are improved, and mass production can be realized.

[0014] In some embodiments, the number of the first coating layers is greater than the number of the second coating layers. By setting the number of the first coating layers to be greater than the number of the second coating layers, the stress generated by the second coating layer during cold pressing and charging and discharging can be better dispersed, the probability of the silicon particles in the second coating layer being broken can be reduced, and the overall mechanical strength of the negative electrode sheet can be improved.

[0015] In some embodiments, the first coating layer and the second coating layer extend along the length direction of the current collector and are arranged alternately in the width direction of the current collector. By setting the first coating layer and the second coating layer to extend along the length direction of the current collector and to be arranged alternately in the width direction of the current collector, the application scenarios of the negative electrode sheet are expanded on the basis of dispersing the stress generated by the second coating layer during cold pressing and charging and discharging.

[0016] In some embodiments, the number of the first coating layers is greater than the number of the second coating layers. By setting the number of the first coating layers to be greater than the number of the second coating layers, the stress generated by the second coating layer during cold pressing and charging and discharging can be better dispersed, the probability of the silicon particles in the second coating layer being broken can be reduced, and the overall mechanical strength of the negative electrode sheet can be improved.

[0017] In some embodiments, the second coating layer is arranged in a grid shape to form a plurality of grids, and the first coating layer is located in the grid. By arranging the second coating layer in a grid shape to form a plurality of grids and locating the first coating layer in the grid, the stress generated by the second coating layer during cold pressing and charging and discharging can be further effectively dispersed, the probability of the silicon particles in the second coating layer being broken can be further reduced, and the structural stability and the cycle performance of the negative electrode sheet can be further improved.

[0018] In some embodiments, at least one second coating layer extends along the width direction of the negative electrode sheet, and at least one second coating layer extends along the length direction of the negative electrode sheet. By setting at least one second coating layer to extend along the width direction of the current collector and at least one second coating layer to extend along the length direction of the current collector, the difficulty of setting the first coating layer and the second coating layer is simplified, and the production efficiency of the negative electrode sheet is improved.

[0019] In some embodiments, the current collector includes a first region and a second region, the first coating layer and the second coating layer are located in the first region, and the first coating layer is arranged along the edge of the first region. By arranging the first coating layer along the edge of the first region, the edge of the second coating layer is protected, and the structural stability of the negative electrode sheet is further improved.

[0020] The embodiment of the second aspect of the present application provides a preparation method of the battery cell of the foregoing embodiment, and the method comprises the following steps: obtaining a current collector; coating a first coating layer and a second coating layer on the same surface of the current collector, the first coating layer and the second coating layer are arranged alternately on the surface of the current collector, and the thickness of the first coating layer is greater than the thickness of the second coating layer along a first direction; wherein the first direction is perpendicular to the surface of the current collector, the first coating layer comprises a graphite material, and the second coating layer comprises a silicon material; cold-pressing the coated current collector to obtain a negative electrode sheet; assembling the negative electrode sheet and a positive electrode sheet into an electrode assembly; and assembling the electrode assembly into a shell to obtain the battery cell. By alternately arranging the first coating layer and the second coating layer on the same surface of the current collector, and by the thickness of the first coating layer being greater than the thickness of the second coating layer along the first direction, the stress generated by the second coating layer during cold-pressing and charging and discharging can be effectively dispersed, the probability of the silicon particles in the second coating layer being broken is reduced, and the structural stability and the cycle performance of the negative electrode sheet are improved, so that the structural stability and the cycle performance of the battery cell are improved.

[0021] The embodiment of the third aspect of the present application provides a battery device, which comprises the battery cell in the foregoing embodiment.

[0022] The embodiment of the fourth aspect of the present application provides a power utilization device, which comprises the battery device in the foregoing embodiment, and the battery device is used for providing electric energy.

[0023] The embodiment of the fifth aspect of the present application provides an energy storage device, which comprises the battery device in the foregoing embodiment, and the battery device is used for storing electric energy.

[0024] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0025] In the drawings, identical or similar components or elements are denoted by identical reference numerals throughout the several views, unless otherwise specified. The drawings are not necessarily to scale. It is to be understood that these drawings only depict some embodiments in accordance with the disclosure and should not be considered as limiting the scope of the disclosure.

[0026] Figure 1 A structural schematic diagram of a vehicle of some embodiments of the present application; Figure 2 An exploded structural schematic diagram of a battery device of some embodiments of the present application; Figure 3 An exploded structural schematic diagram of a battery cell of some embodiments of the present application; Figure 4Structure diagram of negative electrode tab for some embodiments of the present application Figure 1 ; Figure 5 Structure diagram of negative electrode tab for some embodiments of the present application Figure 2 ; Figure 6 Structure diagram of negative electrode tab for some embodiments of the present application Figure 3 ; Figure 7 Structure diagram of negative electrode tab for some embodiments of the present application Figure 4 ; Figure 8 Structure diagram of negative electrode tab for some embodiments of the present application Figure 5 ; Figure 9 Structure diagram of negative electrode tab for some embodiments of the present application Figure 6 ; Figure 10 Structure diagram of negative electrode tab for some embodiments of the present application Figure 7 ; Figure 1 Flow diagram of preparation method of battery cell for some embodiments of the present application.

[0027] Explanation of reference signs: 1000, vehicle; 100, battery device; 200, controller; 300, motor; 10, box body; 11, first part; 12, second part; 20, battery cell; 21, end cover; 211, electrode terminal; 22, shell; 23, electrode assembly; 231, tab; 30, negative electrode tab; 31, current collector; 32, first coating layer; 33, second coating layer; 311, first area; 312, second area; Z, first direction; X, length direction; Y, width direction. DETAILED DESCRIPTION

[0028] The embodiments of the technical solutions of the present application will be described in detail below in combination with the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof. Unless otherwise required by context, singular terms shall include pluralities and vice versa. Unless otherwise required by context, the use herein of the singular is also to be construed as a reference to the plural and vice versa.

[0030] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly and specifically limited.

[0031] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification is not necessarily all referring to the same embodiment, or to a particular embodiment, or to a particular set of embodiments, and is not necessarily mutually exclusive of other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0032] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0033] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0034] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. The orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as limiting the embodiments of the present application. The device or element indicated must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0035] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0036] Currently, the application of rechargeable batteries is becoming increasingly widespread, judging from market trends. They are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but also extensively in various electronic devices, such as electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As the application areas of rechargeable batteries continue to expand, the market demand is also constantly increasing.

[0037] Taking lithium-ion batteries as an example, lithium-ion batteries are a typical type of rechargeable battery that relies on the chemical reaction of lithium ions being inserted and extracted between the positive and negative electrodes for charging and discharging. Due to the high specific capacity of silicon materials, they are typically chosen as the negative electrode active material for lithium-ion batteries. However, due to limitations in battery manufacturing processes and battery aging, stress concentration occurs in silicon-based materials during cold pressing and charge / discharge processes. This stress can lead to silicon particle breakage, active material shedding, and damage to the electrode structure, thereby affecting the structural stability and cycle performance of the electrode.

[0038] Based on this, this application provides a battery cell including a negative electrode sheet. By alternately arranging a first coating and a second coating on the same surface of the current collector, and along a first direction, the thickness of the first coating is greater than the thickness of the second coating, the stress generated by the second coating during cold pressing and charging / discharging can be effectively dispersed, reducing the probability of silicon particles in the second coating breaking, improving the structural stability and cycle performance of the negative electrode sheet, thereby improving the structural stability and cycle performance of the battery cell.

[0039] The negative electrode sheet disclosed in the embodiments of this application can be used, but is not limited to, in battery devices such as lithium batteries or electrical devices.

[0040] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0041] Please refer to Figure 1 , Figure 2This is a schematic diagram of the structure of a vehicle provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside the vehicle 1000, and the battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during starting, navigation, and driving.

[0042] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0043] Please refer to Figure 2 , Figure 3 This is an exploded structural diagram of a battery device provided in some embodiments of this application. The battery device 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, jointly defining a space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 jointly define the space. Alternatively, the first portion 11 and the second portion 12 may both be hollow structures with one open side, with the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a cuboid, etc.

[0044] In the battery device 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel connections. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed configuration, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple battery cells 20 first connected in series, parallel, or in a mixed configuration to form battery modules, and then these battery modules are connected in series, parallel, or in a mixed configuration to form a whole, which is also housed within the housing 10. The battery device 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0045] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0046] Please refer to Figure 3 , Figure 3 This is an exploded structural diagram of a battery cell provided in some embodiments of this application. The battery cell 20 refers to the smallest unit that makes up the battery. For example... Figure 4 The battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0047] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 21 is not easily deformed under pressure and impact, giving battery cell 20 higher structural strength and improved safety performance. Functional components such as electrode terminals 211 can be provided on end cap 21. Electrode terminals 211 can be used for electrical connection with electrode assembly 23 for outputting or inputting electrical energy to battery cell 20. In some embodiments, end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of battery cell 20 reaches a threshold. The material of end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0048] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 closes the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and the housing 22 can be integrated. Specifically, the end cap 21 and the housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the end cap 21 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The housing 22 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0049] Electrode assembly 23 is the component in the battery cell 20 where electrochemical reactions occur. The casing 22 may contain one or more electrode assemblies 23. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the electrode assembly, while the portions of the positive and negative electrode sheets without active material each constitute a tab 231. The positive and negative tabs may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs 231 connect to the electrode terminals to form a current loop.

[0050] This application provides a battery cell, which includes a negative electrode 30. Figure 1 This is a schematic diagram of the structure of the negative electrode sheet in some embodiments of this application. Figure 5 , Figure 2 This is a schematic diagram of the structure of the negative electrode sheet in some embodiments of this application. Figure 6 , Figure 3 This is a schematic diagram of the structure of the negative electrode sheet in some embodiments of this application. Figure 7 , Figure 4 This is a schematic diagram of the structure of the negative electrode sheet in some embodiments of this application. Figure 8 , Figure 5 This is a schematic diagram of the structure of the negative electrode sheet in some embodiments of this application. Figure 9 , Figure 6 This is a schematic diagram of the structure of the negative electrode sheet in some embodiments of this application. Figure 10 , Figure 7 This is a schematic diagram of the structure of the negative electrode sheet in some embodiments of this application. Figures 4 to 10 . refer to Figure 4The negative electrode 30 includes a current collector 31, a first coating 32, and a second coating 33. The first coating 32 and the second coating 33 are disposed on the same surface of the current collector 31. The first coating 32 and the second coating 33 are alternately arranged on the surface of the current collector 31. Along the first direction Z, the thickness H1 of the first coating 32 is greater than the thickness H2 of the second coating 33. The first direction Z is perpendicular to the surface of the current collector 31. The first coating 32 includes graphite material, and the second coating 33 includes silicon material.

[0051] In this embodiment, the current collector 31 may be a metal foil or a composite current collector. For example, the metal foil may be copper 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 can 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.).

[0052] The current collector 31 has two surfaces opposite each other in its own thickness direction, and a first coating 32 and a second coating 33 are disposed on either of the two opposing surfaces of the current collector 31.

[0053] The first coating 32 may include any one or more graphite materials selected from natural graphite (such as flake graphite), artificial graphite (such as MCMB mesophase carbon microspheres), or modified graphite (coated graphite). The second coating 33 includes a silicon-based material, where silicon has a high theoretical specific capacity, which can significantly improve the energy density of the battery.

[0054] The first coating 32 and the second coating 33 are alternately arranged on the surface of the current collector 31. That is, the first coating 32 and the second coating 33 do not overlap. A second coating 33 can be placed between any two adjacent first coatings 32, or a first coating 32 can be placed between any two adjacent second coatings 33. In one embodiment, the first coating 32 and the second coating 33 can extend along the width direction Y of the current collector 31 and alternately arrange themselves along the length direction X of the current collector 31. The number of first coatings 32 can be greater than the number of second coatings 33. In another embodiment, the first coating 32 and the second coating 33 can extend along the length direction X of the current collector 31 and alternately arrange themselves along the width direction Y of the current collector 31. The number of first coatings 32 can be greater than the number of second coatings 33. In yet another embodiment, the second coatings 33 can be arranged in a grid pattern to form multiple grids, with the first coatings 32 located within the grids.

[0055] Along the first direction Z, the thickness H1 of the first coating 32 is greater than the thickness H2 of the second coating 33. For example, the ratio S1 of the thickness H1 of the first coating 32 to the thickness H2 of the second coating 33 can satisfy 1 < S1 ≤ 2, and the thickness H1 of any two first coatings 32 is the same, and / or the thickness H2 of any two second coatings 33 is the same. The first coating 32 and the second coating 33 are arranged alternately, and the thickness H1 of the first coating 32 is greater than the thickness H2 of the second coating 33 along the first direction Z. During the production process of the negative electrode 30, for example during cold pressing, the first coating 32 can provide mechanical support for the second coating 33, effectively reducing or eliminating the normal stress experienced by the second coating 33 during cold pressing. During charging and discharging, the first coating 32 can also disperse the stress generated by the expansion of silicon particles in the second coating 33 during charging and discharging.

[0056] In this embodiment, the width, thickness, spacing, and ratio of the first coating 32 and the second coating 33 can be adjusted according to the silicon content in the second coating 33.

[0057] In this embodiment, by alternating the first coating 32 and the second coating 33 on the same surface of the current collector 31, and along the first direction Z, the thickness H1 of the first coating 32 is greater than the thickness H2 of the second coating 33. The first coating 32 can effectively disperse the stress generated by the second coating 33 during cold pressing and charging and discharging, reduce the probability of silicon particles in the second coating 33 breaking, improve the structural stability and cycle performance of the negative electrode sheet 30, and thus improve the structural stability and cycle performance of the battery cell.

[0058] According to some embodiments of this application, the ratio S1 of the thickness of the first coating 32 to the thickness of the second coating 33 satisfies 1 < S1 ≤ 2.

[0059] When the ratio S1 of the thickness H1 of the first coating 32 to the thickness H2 of the second coating 33 is less than 1, the first coating 32 provides insufficient support and buffering for the second coating 33. During the production of the negative electrode sheet 30, the first coating 32 is unable to provide mechanical support for the second coating 33 to reduce or eliminate the normal stress on the second coating 33 during cold pressing. During the charging and discharging process, the first coating 32 cannot disperse the stress generated by the expansion of silicon particles in the second coating 33 during the charging and discharging process.

[0060] When the ratio S1 of the thickness H1 of the first coating 32 to the thickness H2 of the second coating 33 is greater than 2, the proportion of the second coating 33 is too low, which may make it difficult to realize the high capacity advantage of the second coating 33.

[0061] By ensuring that the ratio S1 of the thickness H1 of the first coating 32 to the thickness H2 of the second coating 33 satisfies 1 < S1 ≤ 2, the high specific capacity advantage of the silicon material in the second coating 33 is preserved, and the stress generated in the second coating 33 during cold pressing and charging and discharging can be effectively dispersed, while taking into account the energy density and cycle performance of the negative electrode 30.

[0062] According to some embodiments of this application, any two first coatings 32 have the same thickness H1, and / or any two second coatings 33 have the same thickness H2.

[0063] The function of the first coating 32 is to reduce or eliminate the normal stress on the second coating 33 during cold pressing, and to disperse the stress generated by the expansion of silicon particles in the second coating 33 during charging and discharging. In other words, the first coating 32 provides support for the second coating 33. If the thickness H1 of the first coating 32 varies too much, "strong support areas" and "weak support areas" will form on the surface. During cold pressing or charging and discharging, the "weak support areas" are prone to cracking and delamination first, leading to overall electrode structure failure. However, if the thickness H1 of the first coating 32 is consistent, and / or the thickness H2 of the second coating 33 is consistent, the stress generated in the second coating 33 during cold pressing and charging and discharging can be evenly distributed, significantly reducing the risk of local structural damage.

[0064] In one embodiment, the thickness H1 of any two first coatings 32 is the same, and the thickness H2 of any two second coatings 33 is different. In another embodiment, the thickness H1 of any two first coatings 32 is different, and the thickness H2 of any two second coatings 33 is the same. In yet another embodiment, the thickness H1 of any two first coatings 32 is the same, and the thickness H2 of any two second coatings 33 is the same.

[0065] By setting the thickness H1 of any two first coatings 32 to be the same, and / or the thickness H2 of any two second coatings 33 to be the same, the probability of local damage to the negative electrode 30 is reduced, and the overall mechanical strength of the negative electrode 30 is improved.

[0066] According to some embodiments of this application, reference is made to Figure 5 The thickness H1 of the first coating 32 satisfies 20um≤H1≤200um, and the thickness H2 of the second coating 33 satisfies 10um≤H2≤100um.

[0067] If the thickness H1 of the first coating 32 is less than 20 μm, during cold pressing, the first coating 32 may not provide sufficient mechanical support for the second coating 33, meaning it cannot effectively reduce or eliminate the normal stress experienced by the second coating 33 during cold pressing. Simultaneously, during charging and discharging, the first coating 32 cannot effectively disperse the stress generated by the expansion of silicon particles in the second coating 33, which can easily lead to cracking of the negative electrode 30. If the thickness H1 of the first coating 32 is greater than 200 μm, it will increase the weight of the negative electrode 30, thereby reducing the energy density of the battery.

[0068] If the thickness H2 of the second coating 33 is less than 10 μm, the silicon content in the negative electrode 30 will be too low, making it impossible to realize the high capacity advantage of the negative electrode 30. If the thickness H2 of the second coating 33 is greater than 100 μm, the silicon in the second coating 33 will expand beyond the buffering capacity of the first coating 32, causing the silicon particles to pulverize and detach from the current collector 31, significantly shortening the cycle life.

[0069] By setting the thickness H1 of the first coating 32 to satisfy 20um≤H1≤200um and the thickness H2 of the second coating 33 to satisfy 10um≤H2≤100um, the stress generated by the second coating 33 during cold pressing and charge / discharge can be effectively dispersed, thereby improving the structural stability and cycle performance of the negative electrode 30.

[0070] According to some embodiments of this application, the ratio S2 of the width L1 of the first coating 32 to the width L2 of the second coating 33 satisfies 1≤S2≤10.

[0071] When the ratio S2 of the width L1 of the first coating 32 to the width L2 of the second coating 33 is less than 1, the first coating 32 provides insufficient support and buffering for the second coating 33. During the production of the negative electrode sheet 30, it is difficult to provide mechanical support for the second coating 33 to reduce or eliminate the normal stress on the second coating 33 during rolling. During the charging and discharging process, it is also impossible to disperse the stress generated by the expansion of silicon particles in the second coating 33 during the charging and discharging process.

[0072] When the ratio S2 of the width L1 of the first coating 32 to the width L2 of the second coating 33 is greater than 10, the proportion of the second coating 33 is too low, which may make it difficult to realize the high capacity advantage of the second coating 33.

[0073] By setting the ratio S2 of the width L1 of the first coating 32 to the width L2 of the second coating 33 to satisfy 1≤S2≤10, the high specific capacity advantage of the silicon-based material in the second coating 33 is retained, and the stress generated by the second coating 33 during cold pressing and charging and discharging can be effectively dispersed, while taking into account the energy density and cycle performance of the negative electrode 30.

[0074] According to some embodiments of this application, any two first coatings 32 have the same width L1, and / or any two second coatings 33 have the same width L2.

[0075] The function of the first coating 32 is to reduce or eliminate the normal stress on the second coating 33 during cold pressing. During charging and discharging, it disperses the stress generated by the expansion of silicon particles in the second coating 33. In other words, the first coating 32 provides support for the second coating 33. If a portion of the first coating 32 is too narrow, the supporting area of ​​the first coating 32 in the corresponding area will be insufficient, and local stress concentration will easily occur when the second coating 33 expands, which may cause cracking of the negative electrode 30. If a portion of the second coating 33 is too wide, it will form a local high-capacity region, causing excessive insertion or extraction of lithium ions in this region, forming a thick solid electrolyte interface (SEI) film, and exacerbating capacity decay.

[0076] In one embodiment, the width L1 of any two first coatings 32 is the same, and the width L2 of any two second coatings 33 is different. In another embodiment, the width L1 of any two first coatings 32 is different, and the width L2 of any two second coatings 33 is the same. In yet another embodiment, the width L1 of any two first coatings 32 is the same, and the width L2 of any two second coatings 33 is the same.

[0077] By setting any two first coatings 32 to have the same width L1 and / or any two second coatings 33 to have the same width L2, the probability of local damage to the negative electrode 30 is reduced, and the overall mechanical strength of the negative electrode 30 is improved.

[0078] According to some embodiments of this application, the width L1 of the first coating 32 satisfies 1mm≤L1≤50mm, and the width L2 of the second coating 33 satisfies 0.5mm≤L2≤5mm.

[0079] If the width L1 of the first coating 32 is less than 1 mm, during cold pressing, the first coating 32 may not provide sufficient mechanical support for the second coating 33, meaning it cannot effectively reduce or eliminate the normal stress experienced by the second coating 33 during cold pressing. Simultaneously, during charging and discharging, the first coating 32 cannot effectively disperse the stress generated by the expansion of silicon particles in the second coating 33, which can easily lead to cracking of the negative electrode 30. If the width L1 of the first coating 32 is greater than 50 mm, it will increase the weight of the negative electrode 30, thereby reducing the energy density of the battery.

[0080] If the width L2 of the second coating 33 is less than 0.5 mm, the silicon content in the negative electrode 30 will be too low, making it impossible to realize the high capacity advantage of the negative electrode 30. If the width L2 of the second coating 33 is greater than 5 mm, the silicon in the second coating 33 will expand beyond the buffering capacity of the first coating 32, causing the silicon particles to pulverize and detach from the current collector 31, significantly shortening the cycle life.

[0081] By setting the width L1 of the first coating 32 to satisfy 1mm≤L1≤50mm and the width L2 of the second coating 33 to satisfy 0.5mm≤L2≤5mm, the stress generated by the second coating 33 during cold pressing and charging / discharging can be effectively dispersed, thereby improving the structural stability and cycle performance of the negative electrode 30.

[0082] According to some embodiments of this application, reference is made to Figure 6 and Figure 5 The first coating 32 and the second coating 33 extend along the width direction Y of the current collector 31 and are arranged alternately along the length direction X of the current collector 31.

[0083] Along the length direction X of the current collector 31, a second coating 33 is set between two adjacent first coatings 32 to form an arrangement similar to "first coating 32 / second coating 33 / first coating 32 / second coating 33 / first coating 32", or a first coating 32 is set between two adjacent second coatings 33 to form an arrangement similar to "second coating 33 / first coating 32 / second coating 33 / first coating 32 / second coating 33".

[0084] In industrial production, the current collector 31 is continuously conveyed in roll form along the length direction X. The layout of extending along the width direction Y and alternating in the length direction X can be achieved by adding a slurry switching valve to a single die head. This process has a high degree of continuity and is suitable for large-scale mass production.

[0085] By setting the first coating 32 and the second coating 33 to extend along the width direction Y of the current collector 31 and to be arranged alternately along the length direction X of the current collector 31, the stress of the second coating 33 during cold pressing and charge-discharge processes can be effectively dispersed, thereby improving the structural stability and cycle performance of the negative electrode sheet 30 and enabling large-scale mass production.

[0086] According to some embodiments of this application, the number of first coatings 32 is greater than the number of second coatings 33.

[0087] refer to Figure 6 or Figure 7The first coating 32 and the second coating 33 can be of any shape, forming an arrangement similar to "first coating 32 / second coating 33 / first coating 32 / second coating 33 / first coating 32". Along the length direction X of the current collector 31, each second coating 33 is provided with a first coating 32 on both sides.

[0088] By setting the number of first coatings 32 to be greater than the number of second coatings 33, the stress generated by the second coatings 33 during cold pressing and charging / discharging can be better dispersed, reducing the probability of silicon particles in the second coatings 33 breaking and improving the overall mechanical strength of the negative electrode sheet 30.

[0089] According to some embodiments of this application, reference is made to Figure 7 The first coating 32 and the second coating 33 extend along the length direction X of the current collector 31 and are arranged alternately in the width direction Y of the current collector 31.

[0090] The first coating 32 and the second coating 33 are arranged alternately in the width direction Y of the current collector 31 and extend along the length direction X of the current collector 31, which can ensure that the first coating 32 supports the second coating 33 within any length range of the current collector 31. This arrangement is applicable to narrow electrode sheets.

[0091] By setting the first coating 32 and the second coating 33 to extend along the length direction X of the current collector 31 and to be alternately arranged in the width direction Y of the current collector 31, the application scenarios of the negative electrode sheet 30 are expanded based on dispersing the stress generated by the second coating 33 during cold pressing and charging and discharging.

[0092] According to some embodiments of this application, the number of first coatings 32 is greater than the number of second coatings 33.

[0093] refer to Figure 8 This forms an arrangement similar to "first coating 32 / second coating 33 / first coating 32 / second coating 33 / first coating 32", with a first coating 32 on both sides of each second coating 33 along the width direction Y of the current collector 31.

[0094] By setting the number of first coatings 32 to be greater than the number of second coatings 33, the stress generated by the second coatings 33 during cold pressing and charging / discharging can be better dispersed, reducing the probability of silicon particles in the second coatings 33 breaking and improving the overall mechanical strength of the negative electrode sheet 30.

[0095] According to some embodiments of this application, reference is made to Figure 9 or Figure 9 The second coating 33 is arranged in a grid pattern to form multiple grids, and the first coating 32 is located within the grid.

[0096] The second coating 33 is arranged in a grid pattern on the surface of the current collector 31, forming a continuous grid that divides the first coating 32 into independent units and completely encapsulates it. When the second coating 33 expands, the grid framework is subjected to a supporting reaction force from the internal first coating 32, limiting the disorderly expansion of the second coating 33. The grid structure of the second coating 33 disperses the expansion stress to the intersection nodes and grid edges of each grid, changing the stress distribution from linear concentration to planar dispersion, thereby reducing the stress per unit area.

[0097] The second coating 33 is arranged in a grid pattern to form multiple grids, with the first coating 32 located within the grids. This further effectively disperses the stress generated by the second coating 33 during cold pressing and charge / discharge processes, further reducing the probability of silicon particle breakage in the second coating 33, thereby further improving the structural stability and cycle performance of the negative electrode 30.

[0098] According to some embodiments of this application, at least one second coating 33 extends along the width direction Y of the current collector 31, and at least one second coating 33 extends along the length direction X of the current collector 31.

[0099] refer to Figure 8 Multiple second coatings 33 extend along the width direction Y of the current collector 31, and multiple second coatings 33 extend along the length direction X of the current collector 31.

[0100] By providing at least one second coating 33 extending along the width direction Y of the current collector 31 and at least one second coating 33 extending along the length direction X of the current collector 31, the difficulty of providing the first coating 32 and the second coating 33 is simplified, thereby improving the production efficiency of the negative electrode sheet 30.

[0101] According to some embodiments of this application, the current collector 31 includes a first region 311 and a second region 312, a first coating 32 and a second coating 33 are located in the first region 311, and the first coating 32 is disposed along the edge of the first region 311.

[0102] refer to Figure 9 or Figure 11 The first region 311 is the bearing area for the first coating 32 and the second coating 33. Due to the interface between the coating and the current collector 31 and the stress concentration during subsequent processing, the edge of the first region 311 is prone to coating peeling. Arranging the graphite coating along the edge of the first region 311 can form a high-adhesion buffer zone at the edge junction of the coating and the current collector 31, preventing the second coating 33 from directly contacting the edge.

[0103] By providing the first coating 32 along the edge of the first region 311, the edge of the second coating 33 is protected, further improving the structural stability of the negative electrode sheet 30.

[0104] This application provides a method for preparing a battery cell according to the aforementioned embodiments. Figure 11 This is a schematic flowchart illustrating the preparation method of a single battery cell according to some embodiments of this application. (Refer to...) Figure 11 The method for preparing a single battery cell includes steps 1110 to 1150.

[0105] Step 1110: Obtain the current collector.

[0106] Step 1120: Apply a first coating and a second coating to the same surface of the current collector. The first coating and the second coating are alternately arranged on the surface of the current collector. Along a first direction, the thickness of the first coating is greater than the thickness of the second coating. The first direction is perpendicular to the surface of the current collector. The first coating includes graphite material and the second coating includes silicon material.

[0107] Step 1130: Cold press the coated current collector to obtain the negative electrode sheet.

[0108] Step 1140: Assemble the negative electrode and the positive electrode into an electrode assembly; Step 1150: Assemble the electrode assembly into the housing to obtain a single battery cell.

[0109] In this embodiment, the current collector may be a metal foil or a composite current collector. For example, the metal foil may be copper 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 can 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.).

[0110] The current collector has two surfaces opposite each other in its own thickness direction, and a first coating and a second coating are disposed on either of the two opposing surfaces of the current collector.

[0111] The first coating may include any one or more graphite materials selected from natural graphite (such as flake graphite), artificial graphite (such as MCMB mesophase carbon microspheres), or modified graphite (coated graphite). The second coating includes silicon-based materials, as silicon has a high theoretical specific capacity, which can significantly improve the energy density of the battery.

[0112] The first and second coatings are arranged alternately on the surface of the current collector, meaning there is no overlap between the first and second coatings. A second coating can be placed between any two adjacent first coatings, or a first coating can be placed between any two adjacent second coatings. In one embodiment, the first and second coatings can extend along the width direction of the current collector and alternately in the length direction, with the number of first coatings being greater than the number of second coatings. In another embodiment, the first and second coatings can extend along the length direction of the current collector and alternately in the width direction, with the number of first coatings being greater than the number of second coatings. In yet another embodiment, the second coatings can be arranged in a grid pattern to form multiple grids, with the first coatings located within the grids.

[0113] Along the first direction, the thickness of the first coating is greater than the thickness of the second coating. For example, the ratio S1 of the thickness of the first coating to the thickness of the second coating can satisfy 1 < S1 ≤ 2, and any two first coatings have the same thickness, and / or any two second coatings have the same thickness.

[0114] In this embodiment, the width, thickness, spacing, and ratio of the first and second coatings can be adjusted according to the silicon content in the second coating.

[0115] The first and second coatings are arranged alternately, and the thickness of the first coating is greater than that of the second coating along the first direction. During the production of the negative electrode sheet, such as during cold pressing, the first coating can provide mechanical support for the second coating, effectively reducing or eliminating the normal stress on the second coating during cold pressing. During charging and discharging, the first coating can also disperse the stress generated by the expansion of silicon particles in the second coating during charging and discharging.

[0116] The negative electrode reference is obtained by cold pressing the coated current collector. Figures 4 to 10 .

[0117] In the embodiments of this application, the selection of materials for the positive electrode sheet and the casing, as well as the assembly process of the battery cell, can adopt the content described above, and will not be repeated here.

[0118] By alternating the first coating and the second coating on the same surface of the current collector, and with the thickness of the first coating being greater than that of the second coating along the first direction, the first coating can effectively disperse the stress generated by the second coating during cold pressing and charge / discharge, reduce the probability of silicon particles in the second coating breaking, improve the structural stability and cycle performance of the negative electrode sheet, and thus improve the structural stability and cycle performance of the battery cell.

[0119] This application provides a battery device, which includes the battery cells described in the foregoing embodiments.

[0120] This application provides an electrical device, which includes the battery device in the foregoing embodiments, and the battery device is used to provide electrical energy.

[0121] The electrical devices used in this application embodiment can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0122] This application provides an energy storage device, which includes the battery device described in the foregoing embodiments. The battery device is used to store electrical energy.

[0123] The energy storage device in this application embodiment can be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system.

[0124] The technical solution of this application is described below through a specific embodiment. (Refer to...) ​ .

[0125] The negative electrode 30 includes a current collector 31, a first coating 32 and a second coating 33. The first coating 32 and the second coating 33 are disposed on the same surface of the current collector 31. The first coating 32 and the second coating 33 are alternately arranged on the surface of the current collector 31. Along the first direction Z, the thickness of the first coating 32 is greater than the thickness of the second coating 33. The first direction Z is perpendicular to the surface of the current collector 31. The first coating 32 includes graphite material and the second coating 33 includes silicon material.

[0126] The ratio S1 of the thickness of the first coating 32 to the thickness of the second coating 33 satisfies 1 < S1 ≤ 2. Any two first coatings 32 have the same thickness, and / or any two second coatings 33 have the same thickness. The thickness H1 of the first coating 32 satisfies 20 μm ≤ H1 ≤ 200 μm, and the thickness H2 of the second coating 33 satisfies 10 μm ≤ H2 ≤ 100 μm.

[0127] The ratio S2 of the width of the first coating 32 to the width of the second coating 33 satisfies 1 ≤ S2 ≤ 10. Any two first coatings 32 have the same width, and / or any two second coatings 33 have the same width. The width L1 of the first coating 32 satisfies 1 mm ≤ L1 ≤ 50 mm, and the width L2 of the second coating 33 satisfies 0.5 mm ≤ L2 ≤ 5 mm.

[0128] In one embodiment, the first coating 32 and the second coating 33 extend along the width direction Y of the current collector 31 and are alternately arranged along the length direction X of the current collector 31. The number of first coatings 32 is greater than the number of second coatings 33.

[0129] In another embodiment, the first coating 32 and the second coating 33 extend along the length direction X of the current collector 31 and are arranged alternately in the width direction Y of the current collector 31. The number of first coatings 32 is greater than the number of second coatings 33.

[0130] In another embodiment, the second coating 33 is arranged in a grid pattern to form a plurality of grids, and the first coating 32 is located within the grids. At least one second coating 33 extends along the width direction Y of the current collector 31, and at least one second coating 33 extends along the length direction X of the current collector 31. The current collector 31 includes a first region 311 and a second region 312, the first coating 32 and the second coating 33 are located in the first region 311, and the first coating 32 is disposed along the edge of the first region 311.

[0131] The following provides some comparative examples and 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 in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0132] Comparative Example A battery cell includes a casing, end caps, electrode assemblies, and electrode terminals. The electrode assemblies include a positive electrode, a negative electrode, and a separator. The positive electrode includes lithium phosphate, and the negative electrode includes graphite and silicon materials. The separator is made of polyethylene, and the casing is made of rigid aluminum. The negative electrode is prepared by alternately coating graphite and silicon materials on the same surface of a current collector, with a width ratio of 1:1 and a thickness ratio of 1:1. The coated current collector is then cold-pressed.

[0133] Example 1 A battery cell includes a casing, end caps, electrode assemblies, and electrode terminals. The electrode assemblies include a positive electrode, a negative electrode, and a separator. The positive electrode includes lithium phosphate, and the negative electrode includes graphite and silicon materials. The separator is made of polyethylene, and the casing is made of rigid aluminum. The negative electrode is prepared by alternately coating graphite and silicon materials on the same surface of a current collector, with a width ratio of 3:1 and a thickness ratio of 2:1. The coated current collector is then cold-pressed.

[0134] Example 2 A battery cell includes a casing, end caps, electrode assemblies, and electrode terminals. The electrode assemblies include a positive electrode, a negative electrode, and a separator. The positive electrode comprises lithium phosphate, and the negative electrode comprises graphite and silicon materials. The separator is made of polyethylene, and the casing is made of rigid aluminum. The negative electrode is prepared by alternately coating graphite and silicon materials on the same surface of a current collector, with a width ratio of 5:1 and a thickness ratio of 2:1. The coated current collector is then cold-pressed.

[0135] Example 3 A battery cell includes a casing, end caps, electrode assemblies, and electrode terminals. The electrode assemblies include a positive electrode, a negative electrode, and a separator. The positive electrode includes lithium phosphate, and the negative electrode includes graphite and silicon materials. The separator is made of polyethylene, and the casing is made of rigid aluminum. The negative electrode is prepared by alternately coating graphite and silicon materials on the same surface of a current collector, with a width ratio of 7:1 and a thickness ratio of 2:1. The coated current collector is then cold-pressed.

[0136] Example 4 A battery cell includes a casing, end caps, electrode assemblies, and electrode terminals. The electrode assemblies include a positive electrode, a negative electrode, and a separator. The positive electrode comprises lithium phosphate, and the negative electrode comprises graphite and silicon materials. The separator is made of polyethylene, and the casing is made of rigid aluminum. The negative electrode is prepared by alternately coating graphite and silicon materials on the same surface of a current collector, with a width ratio of 3:1 and a thickness ratio of 3:2. The coated current collector is then cold-pressed.

[0137] Example 5 A battery cell includes a casing, end caps, electrode assemblies, and electrode terminals. The electrode assemblies include a positive electrode, a negative electrode, and a separator. The positive electrode comprises lithium phosphate, and the negative electrode comprises graphite and silicon materials. The separator is made of polyethylene, and the casing is made of rigid aluminum. The negative electrode is prepared by alternately coating graphite and silicon materials on the same surface of a current collector, with a width ratio of 5:1 and a thickness ratio of 3:2. The coated current collector is then cold-pressed.

[0138] Example 6 A battery cell includes a casing, end caps, electrode assemblies, and electrode terminals. The electrode assemblies include a positive electrode, a negative electrode, and a separator. The positive electrode comprises lithium phosphate, and the negative electrode comprises graphite and silicon materials. The separator is made of polyethylene, and the casing is made of rigid aluminum. The negative electrode is prepared by alternately coating graphite and silicon materials on the same surface of a current collector, with a width ratio of 7:1 and a thickness ratio of 3:2. The coated current collector is then cold-pressed.

[0139] The battery cells prepared in the comparative examples and Examples 1-6 were tested. The tests included the battery's first efficiency and the cycle expansion rate after 1000 charge-discharge cycles.

[0140] The test results are shown in the table below:

[0141] As shown in the table above, the width ratio and thickness ratio of graphite and silicon materials in Examples 1 to 6 are all greater than 1:1. Compared with the comparative examples, Examples 1 to 6 show increased initial battery efficiency and reduced 1000-cycle expansion rate.

[0142] The thickness ratio of graphite material to silicon material in Examples 1 to 3 is 2:1. The width ratio of graphite material to silicon material in Examples 2 and 3 is greater than that in Example 1. The first-cycle efficiency of the battery in Examples 2 and 3 is close to that in Example 1. The 1000-cycle expansion rates of Examples 2 and 3 are 6.5% and 6.3%, respectively, which are lower than that of Example 1.

[0143] The thickness ratio of graphite material to silicon material in Examples 4 to 6 is 3:2. The width ratio of graphite material to silicon material in Examples 5 and 6 is greater than that in Example 1. The first-cycle efficiency of the battery in Examples 5 and 6 is close to that in Example 4. The 1000-cycle expansion rate of Examples 5 and 6 is also close to that of Example 4.

[0144] In Example 4, the width ratio of graphite to silicon material is 3:1, the thickness ratio is 3:2, and in Example 1 it is 2:1. The battery in Example 1 has an initial efficiency of 88% and a 1000-cycle expansion rate of 6.8%. The battery in Example 4 has an initial efficiency of 87% and a 1000-cycle expansion rate of 7.2%. The initial efficiency of the batteries in Example 4 and Example 1 is similar, but the 1000-cycle expansion rate of Example 4 is greater than that of Example 1.

[0145] As can be seen from the above embodiments, compared with batteries using conventionally configured negative electrode sheets, batteries using the negative electrode sheets of this application show significant improvements in both initial battery efficiency and cycle expansion rate.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, The device includes a negative electrode sheet, which includes a current collector, a first coating, and a second coating. The first coating and the second coating are disposed on the same surface of the current collector, and the first coating and the second coating are alternately arranged on the surface of the current collector. Along a first direction, the thickness of the first coating is greater than the thickness of the second coating. The first direction is perpendicular to the surface of the current collector. The first coating includes a graphite material, and the second coating includes a silicon material.

2. The battery cell according to claim 1, characterized in that, The ratio S1 of the thickness of the first coating to the thickness of the second coating satisfies 1 < S1 ≤ 2.

3. The battery cell according to claim 1, characterized in that, Any two of the first coatings have the same thickness, and / or any two of the second coatings have the same thickness.

4. The battery cell according to claim 1, characterized in that, The thickness H1 of the first coating satisfies 20um≤H1≤200um, and the thickness H2 of the second coating satisfies 10um≤H2≤100um.

5. The battery cell according to claim 1, characterized in that, The ratio S2 of the width of the first coating to the width of the second coating satisfies 1 ≤ S2 ≤ 10.

6. The battery cell according to claim 1, characterized in that, Any two of the first coatings have the same width, and / or any two of the second coatings have the same width.

7. The battery cell according to claim 1, characterized in that, The width L1 of the first coating satisfies 1mm≤L1≤50mm, and the width L2 of the second coating satisfies 0.5mm≤L2≤5mm.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The first coating and the second coating extend along the width direction of the current collector and are arranged alternately along the length direction of the current collector.

9. The battery cell according to claim 8, characterized in that, The number of the first coatings is greater than the number of the second coatings.

10. The battery cell according to any one of claims 1 to 7, characterized in that, The first coating and the second coating extend along the length direction of the current collector and are arranged alternately in the width direction of the current collector.

11. The battery cell according to claim 10, characterized in that, The number of the first coatings is greater than the number of the second coatings.

12. The battery cell according to any one of claims 1 to 4, characterized in that, The second coating is arranged in a grid pattern to form multiple grids, and the first coating is located within the grids.

13. The battery cell according to claim 12, characterized in that, At least one of the second coatings extends along the width direction of the negative electrode sheet, and at least one of the second coatings extends along the length direction of the negative electrode sheet.

14. The battery cell according to claim 12, characterized in that, The current collector includes a first region and a second region, with the first coating and the second coating located in the first region, and the first coating disposed along the edge of the first region.

15. A method for preparing a battery cell according to any one of claims 1 to 14, characterized in that, The method includes: Obtain the current collector; A first coating and a second coating are applied to the same surface of the current collector, the first coating and the second coating being alternately arranged on the surface of the current collector, along a first direction, the thickness of the first coating being greater than the thickness of the second coating; wherein, the first direction is perpendicular to the surface of the current collector, the first coating comprising graphite material, and the second coating comprising silicon material; The coated current collector is cold-pressed to obtain a negative electrode sheet; The negative electrode and the positive electrode are assembled into an electrode assembly; The electrode assembly is assembled into the housing to obtain a single battery cell.

16. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1-14.

17. An electrical appliance, characterized in that, The electrical device includes the battery device as described in claim 16, the battery device being used to provide electrical energy.

18. An energy storage device, characterized in that, The energy storage device includes the electrical device as described in claim 17, and the energy storage device is used to store electrical energy.

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