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

Abstract

The invention relates to the field of batteries, provides a battery monomer and a preparation method thereof, a battery device, a power utilization device and an energy storage device, and aims to improve the safety and stability of the battery monomer. The battery single body comprises a battery shell, a battery cover and a battery cover, the battery shell is internally provided with a cavity, and the cavity is internally provided with electrolyte; the battery cell assembly is positioned in the cavity, and the battery cell assembly is positioned in the electrolyte; the battery cell assembly comprises a positive plate, a diaphragm and a negative plate, and the negative plate comprises a negative current collector and a carbon-silicon active layer; the elastic layer is located on the carbon silicon active layer, the elastic layer comprises a conductive framework and a carbon layer, the conductive framework is located in the carbon layer, and the conductive framework is constructed by a plurality of hexagonal copper metal units in a honeycomb structure.

Description

TECHNICAL FIELD

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

[0002] With the rapid development of the energy storage market, energy storage battery cells are accelerating the update iteration. At present, battery cell products are developing towards large capacity and high energy density. The performance of battery cell products mainly depends on the performance of the positive electrode material for constituting the positive electrode sheet and the negative electrode material for constituting the negative electrode sheet. Among them, the traditional negative electrode material is graphite, and the traditional graphite negative electrode material has low diffusion rate and poor rate performance in lithium ion batteries. Volume expansion leads to the rupture of the SEI film (solid electrolyte interface / film), and the cycle life is limited.

[0003] On this basis, in addition to developing positive and negative electrode materials with higher specific capacity, in the design of battery cells, the purpose of improving the energy density of the battery cell is often achieved by increasing the surface density of the electrode sheet and increasing the compaction density, but this will greatly increase the electrochemical impedance of the electrode sheet, especially for the negative electrode sheet. The increase of the electrochemical impedance of the electrode sheet will increase the risk of lithium precipitation in the charging process of the battery cell, resulting in capacity attenuation of the battery cell.

[0004] At present, how to reduce the electrochemical impedance of the electrode sheet and improve the safety under the premise of improving the capacity of the positive and negative electrode materials by changing the performance of the electrode sheet needs to be solved. SUMMARY

[0005] The embodiments of the present application provide a battery monomer, a preparation method thereof, a battery device, a power utilization device and an energy storage device, which at least help to improve the safety and stability of the battery monomer.

[0006] According to some embodiments of the present application, the embodiments of the present application provide a battery monomer, comprising: a battery shell, the battery shell having a cavity inside, the cavity having an electrolyte inside; a battery cell assembly, the battery cell assembly being located in the cavity, and the battery cell assembly being located in the electrolyte; the battery cell assembly comprising a positive electrode sheet, a separator and a negative electrode sheet, wherein the negative electrode sheet comprises: a negative electrode current collector and a carbon-silicon active layer; an elastic layer, the elastic layer being located on the carbon-silicon active layer, the elastic layer comprising a conductive framework and a carbon layer, the conductive framework being located in the carbon layer, and the conductive framework being constructed in a honeycomb structure by a plurality of copper metal units in the shape of hexagons.

[0007] In some embodiments, the elastic layer comprises 2-3 layers of the conductive framework; the thickness of the conductive framework ranges from 100 nm to 200 nm.

[0008] In some embodiments, the ratio of the developed area of the conductive framework to the carbon layer is 1: (5-8).

[0009] In some embodiments, the length of the side of the copper metal unit ranges from 50 pm to 80 pm.

[0010] In some embodiments, further comprising: a plasma active layer, the plasma active layer is located between the carbon-silicon active layer and the elastic layer.

[0011] In some embodiments, the thickness of the plasma active layer is 1 nm to 100 nm.

[0012] According to some embodiments of the present application, another aspect of the embodiments of the present application provides a preparation method of a battery cell, comprising: forming a negative electrode sheet, the negative electrode sheet comprising: a negative electrode current collector and a carbon-silicon active layer; an elastic layer, the elastic layer being located on the carbon-silicon active layer, the elastic layer comprising a conductive framework and a carbon layer, the conductive framework being located in the carbon layer, the conductive framework being constructed in a honeycomb structure by a plurality of hexagonal copper metal units; providing a positive electrode sheet and a separator; stacking the negative electrode sheet, the separator and the positive electrode sheet in sequence, obtaining an electric core assembly by winding or stacking, and placing the electric core assembly into a battery shell, injecting an electrolyte into the battery shell, and then packaging to obtain a battery cell.

[0013] In some embodiments, the process steps for forming the negative electrode sheet comprise: providing a negative electrode current collector; forming a carbon-silicon active layer on the surface of the negative electrode current collector; performing plasma activation treatment on the carbon-silicon active layer to form a concave-convex structure on the surface of the carbon-silicon active layer; forming an initial elastic film, the initial elastic film having an initial conductive framework composed of copper atoms and carbon atoms, the carbon atoms being located in the initial conductive framework, and the carbon atoms coating the silicon particles in the carbon-silicon active layer; performing a regulation treatment on the initial elastic film to enable the copper atoms in the initial conductive framework to self-assemble into hexagonal copper metal units and construct a honeycomb structure; and the carbon atoms constructing the carbon layer.

[0014] In some embodiments, the process steps for forming the initial elastic film comprise: using a copper target to perform sputtering on the carbon-silicon active layer to form copper atoms, the copper atoms forming an initial conductive framework; and using a carbon target to perform sputtering on the carbon-silicon active layer to form carbon atoms, the carbon atoms being located in the initial conductive framework, and the carbon atoms coating the silicon particles in the carbon-silicon active layer.

[0015] In some embodiments, the process step of performing a regulation treatment on the initial elastic film comprises rotating the initial elastic film at a uniform speed of 5 rpm to 20 rpm, periodically nucleating copper atoms by centrifugal force and plasma irradiation to enable the copper atoms to self-assemble into copper metal units in a hexagonal shape and to construct a honeycomb structure.

[0016] In some embodiments, the sputtering power of the carbon-silicon active layer using a copper target to form copper atoms is a first power; the sputtering power of the carbon-silicon active layer using a carbon target to form carbon atoms is a second power, and the ratio of the second power to the first power is 1.3 to 20.

[0017] In some embodiments, the first power is 100 W to 180 W; and the second power is 270 W to 350 W.

[0018] In some embodiments, the process step of performing a regulation treatment on the initial elastic film comprises rotating the initial elastic film at a uniform speed of 5 rpm to 20 rpm, periodically nucleating copper atoms by centrifugal force and plasma irradiation to enable the copper atoms to self-assemble into copper metal units in a hexagonal shape and to construct a honeycomb structure. -4 Pa; and introducing argon gas to 0.3 Pa to 0.8 Pa, and pre-sputtering for 2 min to 5 min by the copper target and the carbon target.

[0019] According to some embodiments of the present application, a further aspect of the embodiments of the present application provides a battery device, comprising the battery monomer according to any one of the above embodiments or the battery monomer prepared by the preparation method of the battery monomer according to any one of the above embodiments, and the battery device comprises one or more of a battery module, a battery pack, and an energy storage battery.

[0020] According to some embodiments of the present application, a further aspect of the embodiments of the present application provides a power utilization device, comprising the battery device according to the above embodiments, and the battery device is used to provide electric energy.

[0021] According to some embodiments of the present application, a further aspect of the embodiments of the present application provides an energy storage device, comprising the battery device according to the above embodiments, and the battery device is used to store electric energy.

[0022] The technical solutions provided by the embodiments of the present application have at least the following advantages: In the negative electrode sheet provided by the embodiments of the present application, the carbon-silicon active layer composed of a silicon-carbon composite material has the advantages of good stability, small volume change, and excellent conductivity as a silicon-carbon negative electrode, thereby improving the expansion and failure problems of the silicon-based negative electrode material.

[0023] The elastic layer is located on the carbon-silicon active layer and is composed of a conductive framework (copper metal units in a honeycomb structure) and a carbon layer. Its cushioning effect is mainly based on the following mechanisms: First, the conductive framework is constructed by multiple copper metal units in a honeycomb structure with a hexagonal shape. The honeycomb structure has high specific strength, high toughness, and good energy absorption characteristics. When the carbon-silicon active layer undergoes volume changes during the process of deintercalating lithium ions, the honeycomb structure can absorb and disperse stress through elastic deformation, just like a spring cushioning mechanical impact. Specifically, the isotropic characteristics of the honeycomb structure enable it to uniformly bear multidirectional stress, reducing stress concentration points and effectively inhibiting the rupture of silicon particles and the peeling of the electrode layer. Copper metal itself has good ductility and conductivity, ensuring that the elastic layer will not break during the cushioning process while maintaining the continuity of the electronic conduction path. Second, the carbon layer enhances interface stability and adaptability: The carbon layer is wrapped inside the conductive framework, and carbon materials generally have good flexibility and lubricity, which can further adapt to the volume changes of silicon. The carbon layer can fill the gaps of the honeycomb structure, forming a more continuous cushioning layer and reducing the direct contact pressure between the carbon-silicon active layer and the separator. The carbon layer also helps to stabilize the formation of the SEI film, as carbon materials have good compatibility with electrolyte, reducing side reactions and thus alleviating interface instability caused by volume changes.

[0024] The elastic layer combines with the carbon-silicon active layer to form a "stress buffer zone". During the deintercalation of lithium ions, the expansion of silicon is first absorbed by the elastic layer, avoiding the direct transmission of stress to the current collector and separator; when shrinking, the elastic recovery force of the elastic layer can maintain the tightness of the electrode structure, preventing the electrode from loosening. This design is similar to adding a flexible layer between hard materials (silicon) and rigid components (such as the negative electrode current collector), thereby improving the tolerance of the electrode. The elastic layer reduces the mechanical degradation of the carbon-silicon active layer by buffering stress and deformation, delaying capacity decay, allowing the battery cell to withstand more charging and discharging cycles. The elastic layer prevents the destruction of the electrode structure and reduces the risk of internal short circuits. The conductive framework ensures good electronic conduction, avoiding the increase in impedance caused by the cushioning layer, allowing the battery to maintain stable performance at high rates.

[0025] The elastic layer absorbs the expansion force of silicon during a long charging process, avoids excessive extrusion of the separator, and greatly reduces the risk of deformation or damage of the separator due to stress accumulation. Secondly, by stabilizing the SEI film, the interface side reaction and lithium consumption are reduced, ensuring long-term capacity retention and efficient operation. Further, the short life of the silicon negative electrode can be fundamentally solved, so that the battery can stably undergo complete and severe volume expansion and contraction during a long charging and discharging process, can withstand deep cycle for several years once a day, significantly improves the cycle life of the battery, and meets the harsh requirements of cycle times for long-term energy storage. For example, it can be applied to 5h, 6h, 8h, etc. Energy storage scenarios. Among them, long-term energy storage, i.e. can discharge for 4h or even longer at rated power, or realize large-scale low-cost energy storage for several days or months. This scheme is beneficial to improve the quality retention rate of battery products during storage and transportation, and the performance of terminal equipment after long-term idling. BRIEF DESCRIPTION OF DRAWINGS

[0026] One or more embodiments are illustrated by way of example in the drawings that are for illustrative purposes only, and not for the purpose of limiting the embodiments, unless otherwise specifically stated in the specification. The drawings in the accompanying drawings do not constitute a proportional limit; in order to more clearly illustrate the technical solutions in the embodiments or in the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings from these drawings without creating labor.

[0027] Figure 1 A cross-sectional view of a battery cell provided by an embodiment of the present application; Figure 2 A cross-sectional view of a negative electrode provided by an embodiment of the present application; Figure 3 Another cross-sectional view of a negative electrode provided by an embodiment of the present application.

[0028] Explanation of reference signs: 100, negative current collector; 101, carbon-silicon active layer; 102, plasmonic active layer; 11, elastic layer; 110, conductive framework; 111, copper metal unit; 120, carbon layer; 1, positive electrode; 2, negative electrode; 3, separator. DETAILED DESCRIPTION

[0029] As known from the background art, the current battery cell has problems of safety and stability.

[0030] The analysis found that one of the reasons for the current battery monomer safety problem is that silicon as a negative electrode active material has a high theoretical capacity (about 4200 mAh / g), but during the charging and discharging process, silicon will undergo a dramatic volume change (shrinkage when delithiation, expansion when lithium intercalation, and volume change of more than 300%). This repeated volume change will cause: mechanical stress concentration: high stress is generated inside and at the interface of silicon particles, which can easily cause particle breakage and pulverization, leading to loss of active material. Electrode structure damage: volume change can cause electrode coating to fall off and current collector to deform, destroying the integrity of the electrode. Interface instability: the solid-liquid interface between silicon and electrolyte changes repeatedly, which can easily form an unstable SEI film and exacerbate capacity decay. During long-term charging and discharging, silicon material will undergo complete and dramatic volume expansion and contraction. This "breathing effect" can cause cumulative and irreversible damage to the electrode structure after thousands of repetitions, which is the main cause of the early failure of traditional silicon-carbon negative electrode batteries in long-term energy storage applications.

[0031] The embodiment of the present application provides a battery monomer, which forms a "stress buffer zone" by arranging a carbon-silicon active layer and an elastic layer. When lithium ions are deintercalated, the expansion of silicon is first absorbed by the elastic layer, avoiding the direct transmission of stress to the current collector and the separator; when shrinking, the elastic recovery force of the elastic layer can keep the tightness of the electrode structure, preventing the electrode from loosening. This design is similar to adding a flexible layer between hard materials (silicon) and rigid components (such as negative electrode current collectors), thereby improving the tolerance of the electrode. The elastic layer reduces the mechanical degradation of the carbon-silicon active layer by buffering stress and deformation, delays capacity decay, and enables the battery monomer to withstand more charging and discharging cycles. The elastic layer prevents the destruction of the electrode structure and reduces the risk of internal short circuit. The conductive framework ensures good electron conduction and avoids the impedance increase caused by the buffer layer, so that the battery can still maintain stable performance at high rates.

[0032] 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 "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0033] In this document, the phrase "embodiment" means that the specific features, structures or properties described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor is it an independent or alternative embodiment to other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0034] 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 can represent: there is A, there is A and B, and there is B. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0035] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).

[0036] 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" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0037] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0038] In the corresponding drawings of the embodiments of the present application, in order to better understand and facilitate the description, the thickness and area of the layer are enlarged. When describing that a component (such as a layer, a film, a region or a substrate) is on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. On the contrary, when describing that a component is on the surface of another component or a component surface is formed or provided with another component, it means that there is no third component between the two components. In addition, when describing that a component is "formed" on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on the edge of the entire surface.

[0039] In the description of the embodiments of the present application, when a certain component "includes" another component, unless otherwise specified, other components are not excluded and can be further included. In addition, when a layer, film, region, plate, etc. component is referred to as "on / under" another component, it can be "directly on" the other component (i.e. between the other component surface and the layer, film, region, plate, etc. component, no other component is present), or another component can be present therebetween. In addition, when a layer, film, region, plate, etc. component is "directly on" another component, or when a layer, film, region, plate, etc. component is on the surface of another component, it means that no other component is present therebetween.

[0040] The terms used in the description of various described embodiments herein are only used to describe specific embodiments and are not intended to be limiting. As used in the description of various embodiments described and the appended claims, "the part" is also intended to include the plural, unless the context clearly indicates otherwise. Among them, the components include layers, films, regions, or plates, etc.

[0041] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present application, many technical details are presented in order to enable the reader to better understand the present application. However, the technical solutions claimed by the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0042] According to some embodiments of the present application, the embodiments of the present application provide a battery monomer for improving the safety problem of the battery monomer.

[0043] Figure 1 A cross-sectional view of a battery monomer provided by an embodiment of the present application; Figure 2 A cross-sectional view of a negative electrode sheet provided by an embodiment of the present application.

[0044] Reference Figure 1 And Figure 2 The battery monomer includes: a battery shell, the battery shell has a cavity inside, and the cavity has an electrolyte inside; a battery cell assembly, the battery cell assembly is located in the cavity, and the battery cell assembly is located in the electrolyte; the battery cell assembly includes a positive electrode sheet 1, a separator 3 and a negative electrode sheet 2, wherein the negative electrode sheet 2 includes: a negative electrode current collector 100 and a carbon-silicon active layer 101; an elastic layer 11, the elastic layer 11 is located on the carbon-silicon active layer 101, the elastic layer 11 includes a conductive framework 110 and a carbon layer 120, the conductive framework 110 is located in the carbon layer 120, and the conductive framework 110 is constructed in a honeycomb structure by a plurality of hexagonal copper metal units 111.

[0045] The negative electrode sheet provided by the embodiment of the present application comprises a carbon-silicon active layer 101 composed of a silicon-carbon composite material. The carbon-silicon active layer 101 as a silicon-carbon negative electrode has the advantages of good stability, small volume change and excellent electrical conductivity, thereby improving the expansion and failure problems of the silicon-based negative electrode material.

[0046] The elastic layer 11 is located on the carbon-silicon active layer 101 and is composed of a conductive framework 110 (copper metal unit 111 in a honeycomb structure) and a carbon layer 120. The buffering effect of the elastic layer 11 is mainly based on the following mechanisms: first, the conductive framework 110 is constructed by a plurality of hexagonal copper metal units 111 in a honeycomb structure, which has high specific strength, high toughness and good energy absorption characteristics. When the carbon-silicon active layer undergoes volume change during the process of deintercalating lithium ions, the honeycomb structure can absorb and disperse stress through elastic deformation, just like a spring buffering mechanical impact. Specifically, the isotropic characteristics of the honeycomb structure enable it to uniformly bear multidirectional stress, reducing stress concentration points, thereby effectively inhibiting the rupture of silicon particles and the peeling of the electrode layer. Copper metal itself has good ductility and electrical conductivity, ensuring that the elastic layer 11 will not break during the buffering process, while maintaining the continuity of the electron conduction path. Second, the carbon layer 120 enhances the interface stability and adaptability: the carbon layer 120 is wrapped in the conductive framework 110, and the carbon material generally has good flexibility and lubricity, which can further adapt to the volume change of silicon. The carbon layer 120 can fill the gaps of the honeycomb structure, forming a more continuous buffer layer, reducing the direct contact pressure between the carbon-silicon active layer and the separator. The carbon layer 120 also helps to stabilize the formation of the SEI film, because the carbon material has good compatibility with the electrolyte, which can reduce side reactions, thereby relieving the interface instability caused by volume change.

[0047] The elastic layer 11 combines with the carbon-silicon active layer 101 to form a "stress buffer zone". During the deintercalation of lithium ions, the expansion of silicon is first absorbed by the elastic layer 11, avoiding the direct transmission of stress to the current collector and the separator; when shrinking, the elastic recovery force of the elastic layer 11 can maintain the tightness of the electrode structure, preventing the electrode from loosening. This design is similar to adding a flexible layer between hard materials (silicon) and rigid components (such as the negative electrode current collector 100), thereby improving the tolerance of the electrode. The elastic layer 11 reduces the mechanical degradation of the carbon-silicon active layer 101 by buffering stress and deformation, delays capacity decay, and enables the battery cell to withstand more charge and discharge cycles. The elastic layer 11 prevents the destruction of the electrode structure and reduces the risk of internal short circuit. The conductive framework 110 ensures good electron conduction, avoiding the increase in impedance caused by the buffer layer, so that the battery can still maintain stable performance at high rates.

[0048] The elastic layer 11 absorbs the expansion force of silicon during a long charging process, avoids excessive extrusion of the separator, and greatly reduces the risk of deformation or damage of the separator due to stress accumulation. Secondly, by stabilizing the SEI film, the interface side reaction and lithium consumption are reduced, ensuring long-term capacity retention and efficient operation. Furthermore, the short life of the silicon negative electrode can be fundamentally solved, so that the battery can stably undergo complete and severe volume expansion and contraction during a long charging and discharging process, can withstand deep cycle for several years once a day, significantly improves the cycle life of the battery, and meets the harsh requirements of cycle times for long-term energy storage.

[0049] The above-mentioned battery cell will be described in detail below with reference to the accompanying drawings.

[0050] According to the shape classification, the prepared battery cell can be divided into square cells, round cells or soft package cells. According to the capacity classification, the battery cell can be divided into 50Ah, 100Ah, 150Ah, 200Ah, 280Ah, 306Ah, 314Ah, 500+Ah, 800+Ah and 1000+Ah and the like. According to the chemical composition and working principle of the cell assembly of the battery cell, the battery cell can be a lithium ion battery, a lead-acid battery, a sodium ion battery or a nickel-hydrogen battery. The lithium ion in the positive sheet 1, the negative sheet 2 and the electrolyte in the lithium ion battery preparation method of the present application is replaced by the corresponding metal ion. For example, the sodium ion battery, the lithium transition metal oxide of the positive active material in the subsequent is replaced by any one of the corresponding layered metal oxide (such as NaFeO2), polyanion compound (NaFePO4) and prussian blue compound system (such as NaMnFe(CN)6-zH2O), and the electrolyte is replaced by any one of organic liquid electrolyte, solid composite electrolyte or solid electrolyte.

[0051] Reference Figure 1 , the positive sheet 1 as the cathode in the redox reaction. When discharging, the positive material (lithium salt material) releases lithium ions (Li + ) and electrons (e - ) through chemical reaction; when charging, it receives lithium ions again.

[0052] The positive sheet 1 includes a positive current collector and a positive active layer, and the positive current collector can be an aluminum foil. The price of aluminum foil is lower than that of copper foil, a dense oxide film is formed on the surface of aluminum foil, and the oxide film is very thin, which can improve the corrosion resistance of aluminum foil, and electrons can pass through the tunnel effect to realize electrical conductivity.

[0053] In some embodiments, the current collector of the positive electrode sheet 1 can also be a composite current collector, which includes three layers stacked together, with an organic material in the middle layer and copper plating and aluminum plating in the upper and lower layers. The organic material can be PET (polyethylene terephthalate), PP (polypropylene), PI (polyimide), or the like.

[0054] The positive electrode active material in the positive electrode active layer is a kind of energy storage material, which is usually composed of metal oxides, metal sulfides or polymers, etc. Its main function is to chemically react with lithium ions of the negative electrode when the battery is charged, thereby storing lithium ions and increasing the concentration of lithium ions, so as to make the positive electrode of the battery release charge current. At the same time, when the battery is discharged, the lithium ions stored in the positive electrode active material move to the negative electrode and react with the negative electrode material, so as to form a potential difference between the positive and negative electrodes of the battery, thereby generating current output.

[0055] The negative electrode sheet 2 serves as the anode in the redox reaction. During discharging, the negative electrode material (such as graphite, silicon-based material) accepts lithium ions and stores them; during charging, the lithium ions are released.

[0056] The negative electrode sheet includes a negative electrode current collector 100, which can be a copper foil. The copper foil has low electrical conductivity, can have high electron transmission capacity, and has weak lithium intercalation capacity, capturing less lithium ions, thereby effectively reducing the loss of lithium ions. In other embodiments, the negative electrode current collector 100 can also be a foam copper current collector, a copper mesh current collector, and a three-dimensional nano-copper array current collector.

[0057] In some embodiments, the negative electrode current collector 100 can be a composite current collector, which includes a polymer material layer and a metal plating layer on the upper and lower sides of the polymer material layer. The polymer material layer can be PET (polyethylene terephthalate), PP (polypropylene), PI (polyimide), or the like, and the metal plating layer can be a copper layer.

[0058] In some embodiments, the negative electrode current collector 100 can also be a carbon-based current collector, i.e., a copper foil with a conductive carbon layer. The conductive carbon layer can serve as a protective layer to effectively protect the current collector from corrosion, thereby improving the service life of the current collector. In addition, the conductive carbon layer itself has a low resistivity, thereby not causing excessive electrical loss. The material of the conductive carbon layer can be flaky graphite, spherical graphite, carbon nanotubes, graphene, or the like.

[0059] The carbon-silicon active layer 101 is located on the negative electrode current collector 100, and the carbon-silicon active layer 101 is a negative electrode active material particle, which is a carrier for the oxidation reaction of the battery. The carbon-silicon active layer 101 is a silicon-carbon composite material formed by compounding carbon material on the basis of the existing silicon-based negative electrode material. The silicon-carbon composite material as a silicon-carbon negative electrode can have the advantages of good stability, small volume change, excellent electrical conductivity, etc., thereby improving the expansion and failure problems of the silicon-based negative electrode material.

[0060] The silicon-carbon negative electrode refers to the mixing of nano-silicon and carbon material. By reducing the particle size of the silicon-based material to the nanometer level, more voids can be obtained to buffer the stress and deformation of silicon during the process of deintercalating lithium ions. In the preparation process of the silicon-carbon negative electrode, nano-silicon particles need to be prepared first, and a carbon coating layer is formed on the outermost layer to form a core-shell structure.

[0061] In some embodiments, the negative electrode sheet includes an elastic layer 11 located on the surface of the carbon-silicon active layer 101, which is used to buffer the stress and deformation of silicon during the process of deintercalating lithium ions.

[0062] The specific mechanism can be: the conductive framework 110 is constructed by a plurality of hexagonal copper metal units 111 in a honeycomb structure. This structure is known in material science to have high specific strength, high toughness, and good energy absorption characteristics. When the carbon-silicon active layer undergoes volume change during the process of deintercalating lithium ions, the honeycomb structure can absorb and disperse stress through elastic deformation, just like a spring buffering mechanical impact.

[0063] First, the conductive framework 110 is constructed by a plurality of hexagonal copper metal units 111 in a honeycomb structure, which has high specific strength, high toughness, and good energy absorption characteristics. When the carbon-silicon active layer 101 undergoes volume change during the process of deintercalating lithium ions, the honeycomb structure can absorb and disperse stress through elastic deformation, just like a spring buffering mechanical impact. Specifically, the isotropic characteristics of the honeycomb structure enable it to uniformly bear multidirectional stress, reducing stress concentration points, thereby effectively inhibiting the rupture of silicon particles and the peeling of the electrode layer. Copper metal itself has good ductility and electrical conductivity, ensuring that the elastic layer 11 will not break during the buffering process, while maintaining the continuity of the electronic conduction path. Second, the carbon layer 120 enhances the interface stability and adaptability: the carbon layer 120 is wrapped inside the conductive framework 110. Carbon material generally has good flexibility and lubricity, which can further adapt to the volume change of silicon. The carbon layer 120 can fill the voids of the honeycomb structure, forming a more continuous buffer layer, reducing the direct contact pressure between the carbon-silicon active layer 101 and the separator. The carbon layer 120 also helps to stabilize the formation of the SEI film, as carbon material has good compatibility with electrolyte, which can reduce side reactions, thereby alleviating the interface instability caused by volume change.

[0064] In some embodiments, the elastic layer 11 includes 2-3 layers of conductive framework 110. The multi-layer conductive framework 110 can form a multi-layer buffer layer, and the multi-layer buffer layer formed by the honeycomb structure can absorb and disperse stress through elastic deformation in multiple angles and dimensions, thereby minimizing the direct contact pressure between the carbon-silicon active layer 101 and the separator, improving the stability and safety of the battery cell. Secondly, too thin a number of layers of the conductive framework 110 results in insufficient overall conductivity of the conductive framework 110, and too thick a number of layers reduces the porosity of the honeycomb structure of the hexagonal copper metal units 111.

[0065] In some embodiments, the elastic layer 11 can be 1 layer of conductive framework 110, 2 layers of conductive framework 110, or 3 layers of conductive framework 110.

[0066] In some embodiments, the thickness of the conductive framework 110 ranges from 100 nm to 200 nm. If the elastic layer 11 is too thick, its overall rigidity will increase. Although the support force can be stronger, the flexibility will decrease. It can not be able to well adapt to the frequent and severe volume changes of the silicon-carbon layer 120, and itself can be broken due to stress, or will transfer more stress to the underlying carbon-silicon active layer 101, and the buffering effect will be discounted. At the same time, a too thick non-active layer will reduce the energy density of the battery. If the elastic layer 11 is too thin, its mechanical strength can be insufficient. When the silicon material expands, the thin layer is easily over-stretched and broken, losing continuity, and thus cannot effectively constrain and buffer the volume change. The thickness range of 100 nm to 200 nm of the conductive framework 110 ensures that the elastic layer 11 has sufficient mechanical strength and toughness to withstand cyclic stress, while maintaining excellent flexibility, and can reversibly deform with the expansion and contraction of silicon like a layer of tough and elastic “nanoscale spring pad”, thereby providing sustained and effective buffering protection.

[0067] Specifically, the thickness of the conductive framework 110 can be 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm.

[0068] In some embodiments, the length of the side of the hexagonal copper metal unit 111 ranges from 50 μm to 80 μm. The length of the side of the hexagonal copper metal unit 111 ensures that the single hexagonal unit has appropriate rigidity and flexibility. At this size, when the internal pressure increases, the frame of the copper skeleton can slightly elastically bend and stretch, like a spring that lengthens a hexagon, and this deformation process itself can provide an effective energy (stress) absorption and release process. If the size is too small, the unit is too rigid and difficult to deform; if the size is too large, the unit is too soft and the constraint is insufficient. The length of the side of the hexagonal copper metal unit 111 is also greater than the expansion displacement of the silicon particles (about 2 μm to 3 μm of expansion of a single particle during charging and discharging), which can reserve stress release space. The length of the side of the hexagonal copper metal unit 111 can be 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, or 80 μm.

[0069] It should be noted that the thickness of the conductive skeleton 110 refers to the thickness of the copper metal unit 111 in a microscopic sense. The length of the side of the copper metal unit 111 refers to the length range of the side of the hexagon formed by the copper metal unit 111, which can be a standard regular hexagon or a near regular hexagon.

[0070] The carbon layer 120 enhances interface stability and adaptability: The carbon layer 120 is wrapped in the conductive skeleton 110, and carbon materials generally have good flexibility and lubricity, which can further adapt to the volume change of silicon. The carbon layer 120 can fill the voids of the honeycomb structure, form a more continuous buffer layer, and reduce the direct contact pressure between the carbon-silicon active layer and the separator. The carbon layer 120 also helps to stabilize the formation of the SEI film, because the carbon material has good compatibility with the electrolyte, can reduce side reactions, and thus alleviate the interface instability caused by volume change.

[0071] In some embodiments, the material of the carbon layer 120 can be graphite material (natural graphite, artificial graphite, and mesocarbon microbeads) and other carbon systems (hard carbon, soft carbon, and graphene). In other embodiments, the material of the carbon layer 120 can be a composite material, such as a material with amorphous carbon as the matrix, a small amount of graphene or carbon nanotubes, which can simultaneously have excellent coating, ultra-high conductivity, and excellent mechanical strength, and provide top-level protection for the long-term cycle stability of the battery.

[0072] In some embodiments, the ratio of the unfolded area of the conductive framework 110 to the carbon layer 120 is 1: (5-8). The honeycomb-like copper framework mainly provides macroscopic structural integrity and elastic restoring force. It acts like a “scaffold” to prevent the electrode from undergoing irreversible plastic deformation under repeated swelling / shrinking. The carbon layer 120 acts as a flexible buffer matrix. Carbon materials generally have good flexibility and deformability. The 5-8 times coverage of the framework is the key to its buffering effect. This means that microscopically, most of the area is dominated by soft, compressible / stretchable carbon layer 120. When silicon swells, the large area of the carbon layer 120 absorbs most of the initial strain energy through its own elastic deformation (compression, bending). The carbon layer 120 uniformly transmits the dispersed stress to the solid copper framework network. The framework disperses the concentrated stress to the entire network and stores and releases energy through the elastic deformation of its honeycomb structure.

[0073] It should be noted that the unfolded area of the conductive framework 110 and the carbon layer 120 respectively refers to the total area of the surface of the three-dimensional object of the conductive framework 110 unfolded into a two-dimensional plane and the total area of the surface of the three-dimensional object of the carbon layer 120 unfolded into a two-dimensional plane. The ratio of the unfolded area of the conductive framework 110 to the carbon layer 120 can be the ratio of the proportion of the copper metal unit 111 to the carbon layer 120.

[0074] Figure 3 Another cross-sectional view of a negative electrode sheet provided by an embodiment of the present application.

[0075] In some embodiments, referring to Figure 3 , the negative electrode sheet further comprises: a plasma active layer 102, the plasma active layer 102 is located between the carbon-silicon active layer 101 and the elastic layer 11, firmly “riveting” the three-layer structure of the carbon-silicon active layer 101, the plasma active layer 102 and the elastic layer 11 together to form a solid whole with gradient transition. Even if the silicon undergoes a huge volume change, the interface will not delaminate, ensuring the long-term effectiveness of the buffering effect of the elastic layer 11. The plasma active layer 102 can create favorable conditions for the rapid and uniform shuttling of lithium ions between the carbon-silicon active layer 101 and the elastic layer 11, help to reduce the internal resistance of the battery, improve the rate performance, and promote the uniform embedding / extraction of lithium in silicon, reduce local stress concentration.

[0076] In some embodiments, the thickness of the plasma active layer 102 is 1 nm-100 nm. The thickness range of the plasma active layer 102 can form a continuous and dense modified layer, effectively changing the surface chemical properties to provide an ideal substrate for building a stable SEI film, while not significantly increasing the impedance. The thickness of the plasma active layer 102 can be 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0077] The separator 3 is located between the positive electrode sheet 1 and the negative electrode sheet 2 to prevent short circuit problems caused by physical contact between the positive electrode sheet 1 and the negative electrode sheet 2, while allowing lithium ions to freely shuttle through micropores and impeding electron transmission, so that ions and electrons form a loop during charging and discharging of the battery; as a carrier of the electrolyte, adsorbing the electrolyte, ensuring ion transmission efficiency; closing the pores at high temperatures to block ion flow and prevent thermal runaway.

[0078] The separator 3 can be any one of a microporous membrane, a modified microporous membrane, a non-woven fabric separator 3, and a composite separator 3. The microporous membrane is a separator 3 with a pore size in the micron range, mainly including polyolefin microporous membranes and other polymer microporous membranes. The modified microporous membrane is a separator 3 obtained by modifying a microporous membrane, and common modification methods include surface treatment, chemical grafting, surface coating, etc. The non-woven fabric separator 3 has a small fiber diameter and generally exhibits higher porosity than other types of separators 3. The composite separator 3 is prepared by coating or filling inorganic materials in a microporous membrane or a non-woven fabric separator 3, and has higher thermal stability and electrolyte wettability than other types of separators 3.

[0079] In some embodiments, the separator 3 can be coated with a polyvinylidene fluoride (PVDF) material as an adhesive layer to make the separator 3 have excellent adhesion and flexibility. Because the separator 3 has excellent adhesion, it can make the separator 3 and the positive electrode sheet 1 or the separator 3 and the negative electrode sheet 2 have good contact performance, thereby reducing the assembly time of the energy storage cell and effectively reducing the overall production cost of the energy storage cell. Because the separator 3 has excellent flexibility, the strength of the separator 3 is improved, thereby facilitating the effective improvement of the impact resistance of the separator 3.

[0080] In some embodiments, the battery cell further includes a positive electrode tab and a negative electrode tab, and the positive electrode tab / negative electrode tab is a metal conductor that leads out the positive electrode sheet 1 / negative electrode sheet 2 of the energy storage cell from the cell. The positive electrode tab / negative electrode tab is the contact point of the positive electrode sheet 1 / negative electrode sheet 2 and the external contact component when the cell is charging and discharging. The external contact component can be a pole.

[0081] The electrolyte is a carrier for conducting electrons between the positive and negative electrodes in the battery. In some embodiments, the electrolyte can be an electrolyte solution, which is composed of three parts: a solvent, a lithium salt, and an additive. The solvent is used to dissolve the lithium salt, and the solvent can include cyclic carbonates (PC, EC); chain carbonates (DEC, DMC, EMC); carboxylic acid esters (MF, MA, EA, MA, MP, etc.). The lithium salt can be LiPF6, LiClO4, LiBF4, LiAsF6, etc. The additive can be one or more of a film-forming additive, a conductive additive, a flame-retardant additive, an overcharge protection additive, an additive for controlling the content of H2O and HF in the electrolyte, an additive for improving low-temperature performance, and a multifunctional additive.

[0082] In some embodiments, the battery cell can further include a top cover, a tab, and a pole. The top cover is engaged with the shell. The tab is located in the cavity and is electrically connected with the tab. The pole passes through the top cover, and one end of the pole is electrically connected with the tab.

[0083] In some embodiments, the tab includes at least a first tab and a second tab, and the pole includes a positive pole and a negative pole. The first tab is electrically connected with the positive tab of the positive electrode and the positive pole, respectively, and the second tab is electrically connected with the negative tab of the negative electrode and the negative pole, respectively.

[0084] The negative electrode provided by the embodiments of the present application contains a carbon-silicon active layer 101 composed of a silicon-carbon composite material. The carbon-silicon active layer 101 as a silicon-carbon negative electrode has the advantages of good stability, small volume change, and excellent electrical conductivity, thereby improving the expansion and failure problems of the silicon-based negative electrode material.

[0085] The elastic layer 11 is located on the carbon-silicon active layer 101 and is composed of a conductive framework 110 (copper metal units 111 in a honeycomb structure) and a carbon layer 120. Its buffering effect is mainly based on the following mechanisms: first, the conductive framework 110 is constructed by multiple copper metal units 111 in a honeycomb structure with high specific strength, high toughness, and good energy absorption characteristics. When the carbon-silicon active layer 101 undergoes volume changes during the process of deintercalating lithium ions, the honeycomb structure can absorb and disperse stress through elastic deformation, just like a spring buffering mechanical impact. Specifically, the isotropic characteristics of the honeycomb structure enable it to uniformly bear multidirectional stress, reducing stress concentration points and effectively inhibiting the rupture of silicon particles and the peeling of the electrode layer. Copper metal itself has good ductility and conductivity, ensuring that the elastic layer 11 will not break during the buffering process while maintaining the continuity of the electronic conduction path. Second, the carbon layer 120 enhances interface stability and adaptability: the carbon layer 120 is wrapped inside the conductive framework 110, and carbon materials generally have good flexibility and lubricity, which can further adapt to the volume changes of silicon. The carbon layer 120 can fill the gaps of the honeycomb structure, forming a more continuous buffer layer and reducing the direct contact pressure between the carbon-silicon active layer 101 and the separator. The carbon layer 120 also helps to stabilize the formation of the SEI film, as carbon materials have good compatibility with electrolyte, reducing side reactions and thus alleviating interface instability caused by volume changes.

[0086] The elastic layer 11, combined with the carbon-silicon active layer 101, forms a "stress buffer zone". During the deintercalation of lithium ions, the expansion of silicon is first absorbed by the elastic layer 11, avoiding the direct transmission of stress to the current collector and separator; when shrinking, the elastic recovery force of the elastic layer 11 can maintain the tightness of the electrode structure, preventing the electrode from loosening. This design is similar to adding a flexible layer between hard materials (silicon) and rigid components (such as the negative electrode current collector 100), thereby improving the tolerance of the electrode. The elastic layer 11 reduces the mechanical degradation of the carbon-silicon active layer 101 by buffering stress and deformation, delaying capacity decay and enabling the battery cell to withstand more charging and discharging cycles. The elastic layer 11 prevents the destruction of the electrode structure and reduces the risk of internal short circuits. The conductive framework 110 ensures good electronic conduction, avoiding the increase in impedance caused by the buffer layer, allowing the battery to maintain stable performance at high rates.

[0087] The elastic layer 11 absorbs the expansion force of silicon during a long charging process, avoiding excessive compression of the separator, and greatly reducing the risk of deformation or damage to the separator due to stress accumulation. Secondly, by stabilizing the SEI film, the interface side reaction and lithium consumption are reduced, ensuring long-term capacity retention and efficient operation. Furthermore, the short life of the silicon negative electrode can be fundamentally solved, allowing the battery to undergo complete and severe volume expansion and contraction during a long charging and discharging process, and to withstand deep cycles once a day for several years, significantly improving the cycle life of the battery and meeting the stringent requirements of cycle times for long-term energy storage.

[0088] According to some embodiments of the present application, another aspect of the embodiments of the present application provides a preparation method of a battery cell, for preparing the battery cell provided in the above embodiments, which has the same or corresponding technical features as the above embodiments, and will not be described in detail here.

[0089] Reference Figure 1 and Figure 2 The preparation method comprises: forming a negative electrode sheet, the negative electrode sheet comprising: a negative electrode current collector 100 and a carbon-silicon active layer 101; and an elastic layer 11, the elastic layer 11 being located on the carbon-silicon active layer 101, the elastic layer 11 comprising a conductive framework 110 and a carbon layer 120, the conductive framework 110 being located in the carbon layer 120, and the conductive framework 110 being constructed in a honeycomb structure by a plurality of copper metal units 111 in a hexagonal shape.

[0090] In some embodiments, the process step of forming the negative electrode sheet comprises: providing a negative electrode current collector 100.

[0091] A carbon-silicon active layer 101 is formed on the surface of the negative current collector 100. The carbon-silicon active layer 101 is formed by chemical vapor deposition (CVD). By precisely controlling the gas reaction, nanosilicon (or silicon oxide) is deposited in situ on the surface of the porous carbon substrate or graphite to form a silicon-carbon composite structure. The in-situ confined growth of silicon particles is achieved through the abundant microporous structure of the porous carbon substrate. The CVD silicon-carbon composite material exhibits excellent specific capacity and cycle stability as a negative electrode due to the excellent electrical conductivity and mechanical strength of carbon materials. The specific steps include: first, the negative current collector 100 is placed in the CVD reaction chamber, and a silicon source gas (such as silane, SiH4) is introduced. At a specific temperature (400°C-600°C) and pressure, silane decomposes and deposits nanoscale silicon particles or silicon film on the surface of the current collector. Subsequently, without breaking the vacuum, the gas source is switched to a carbon source gas (such as methane CH4, ethylene C2H4, or benzene C6H6, etc.). The carbon atoms generated by the decomposition of the carbon source gas will deposit on the surface of the previously formed silicon particles, forming a uniform carbon coating layer. Finally, the silicon source gas and the carbon source gas are introduced into the reaction chamber at a certain ratio. By controlling the temperature, pressure and gas ratio, silicon and carbon are deposited together to directly form a silicon-carbon composite, i.e. a carbon-silicon active layer 101.

[0092] In some embodiments, the preparation method includes: removing surface residual contaminants of the carbon-silicon active layer 101 by ultrasonic cleaning to ensure the cleanliness of the surface of the carbon-silicon active layer 101.

[0093] With reference to Figure 2 , an initial elastic film is formed, which has an initial conductive framework composed of copper atoms and carbon atoms in the initial conductive framework, and the carbon atoms coat the silicon particles in the carbon-silicon active layer 101; the initial conductive framework is subjected to a regulation treatment to self-assemble the copper atoms in the initial conductive framework into copper metal units 111 in a hexagonal shape and construct a honeycomb structure; and the carbon atoms are constructed into a carbon layer 120.

[0094] In some embodiments, the process step of forming an initial elastic film by dynamic co-sputtering deposition on the silicon-carbon negative electrode sheet includes: sputtering the carbon-silicon active layer 101 with a copper target to form copper atoms, which form an initial conductive framework; and sputtering the carbon-silicon active layer 101 with a carbon target to form carbon atoms, which are located in the initial conductive framework and coat the silicon particles in the carbon-silicon active layer 101.

[0095] In some embodiments, the process step of regulating the initial elastic film includes rotating the initial elastic film at a uniform speed of 5 rpm to 20 rpm, and periodically nucleating copper atoms by centrifugal force and plasma irradiation to self-assemble the copper atoms into hexagonal copper metal units 111 and build a honeycomb structure. During the process of periodically nucleating copper atoms by plasma irradiation, a periodic temperature gradient (center 80-100°C → edge 50-70°C) is formed by the centrifugal force and the non-uniformity of plasma irradiation, which drives the periodic nucleation of copper atoms and self-assembly into honeycomb pore walls.

[0096] In some embodiments, the sputtering power of the copper target for sputtering the carbon-silicon active layer 101 to form copper atoms is a first power, and the sputtering power of the carbon target for sputtering the carbon-silicon active layer 101 to form carbon atoms is a second power. The ratio of the second power to the first power is 1.3-20.

[0097] The ratio of the second power to the first power can be 1.3-5, 5-13, 13-15, 15-17, or 17-20. The ratio of the second power to the first power can be 1.3, 2.1, 3, 4.2, 5.6, 7.1, 8.6, 9.3, 10, 11, 13.2, 15, 16.8, 18, 19.1, or 20.

[0098] In some embodiments, the first power is 100-180 W, and the second power is 270-350 W. The first power can be 100, 110, 120, 130, 140, 150, 160, 170, or 180 W. The second power can be 270, 280, 290, 300, 310, 320, 330, 340, or 350 W.

[0099] The specific mechanism of the copper atoms forming the initial conductive framework is as follows. In the sputtering process, argon ions are accelerated by an electric field to bombard the copper target, and copper atoms are sputtered from the surface of the target. These copper atoms have high kinetic energy (usually a few to tens of electron volts) and fly to the substrate surface in gaseous form. After reaching the substrate surface, the copper atoms can quickly diffuse on the surface due to their high surface mobility. The copper atoms move from high-energy sites (such as defects or step edges) to low-energy sites to find stable adsorption sites. The tangential force (such as centrifugal force or surface stress gradient) generated by the rotation of the carbon-silicon active layer 101 guides the copper atoms to preferentially migrate along the tangential direction of rotation, which helps the atoms rearrange on the surface. Ultimately, the high-mobility copper atoms preferentially migrate along the tangential direction of the substrate rotation of the carbon-silicon active layer 101, forming a hexagonal framework prototype, i.e., the initial conductive framework.

[0100] The hexagonal skeleton is due to the fact that the hexagonal structure is one of the most stable arrangements of energy, similar to the closest packed hexagonal (HCP) or face-centered cubic (FCC) crystal. Copper is a FCC structure, and its (111) crystal plane naturally exhibits hexagonal symmetry. During deposition, high-mobility copper atoms self-organize into a hexagonal lattice through surface diffusion. Hexagonal units are connected to each other under the action of tangential force, forming a honeycomb-like skeleton prototype. This structure is similar to the Benard convection cell or the self-assembly phenomenon of nanoporous membranes.

[0101] In some embodiments, the carbon-silicon active layer 101 is sputtered with a copper target to form copper atoms, and the process parameters for forming the initial conductive skeleton include: under the action of a direct current power source (first power 100W~180W), at a temperature of 200°C~400°C and a pressure of 0.1Pa~1Pa, the copper atoms are sputtered onto the surface of the substrate under the bombardment of argon ions.

[0102] The carbon-silicon active layer 101 is sputtered with a carbon target to form carbon atoms, which are located in the initial conductive skeleton. The specific mechanism of the carbon atoms coating the silicon particles in the carbon-silicon active layer 101 is that the carbon atoms are deposited from the gas phase. Due to their weak migration ability, they will not jump over the pores or ravines, but will directly deposit on any surface they can contact, including the side and bottom of the copper skeleton, and the surface of the silicon particles.

[0103] This deposition mode is a "top-down" filling method. Carbon atoms will start to accumulate from the top, side wall and bottom of the pores at the same time, just like "sand filling", and eventually fill all the gaps uniformly to form a dense structure. This ensures that there is no void between the copper skeleton and the carbon-silicon active layer 101, achieving excellent mechanical coupling and electrical contact.

[0104] The specific mechanism of the regulation treatment of the initial elastic film is as follows: in the plasma (such as the plasma of magnetron sputtering), the energy distribution is usually uneven. The central region of the initial elastic film directly faces the region with the highest plasma density and is subjected to the strongest irradiation, and thus has the highest temperature (80-100°C). The edge region is subjected to weaker irradiation and has a lower temperature (50-70°C). When the substrate rotates at a uniform speed of 5-20 rpm, any point on the initial elastic film will periodically and alternately pass through the high-temperature zone (near the center) and the low-temperature zone (near the edge). For an initial elastic film rotating at 10 rpm, a point on the initial elastic film will experience a complete cold-hot cycle every 6 seconds. When the point rotates to the high-temperature zone in the center, the temperature of the point rises, and the copper atoms adsorbed on the point have a very high mobility and become very “active”. When the point rotates to the low-temperature zone at the edge, the temperature drops, the mobility of the copper atoms sharply decreases, and the copper atoms become “dull” or even “frozen”. In the high-temperature zone, the atoms quickly converge on potential nucleation points (such as defects and existing small islands), so that the nucleation points grow; when the growing nucleation point rotates to the low-temperature zone with the substrate, the mobility of the atoms sharply decreases. The diffusion movement of the atoms almost stops, and the current structure is “frozen” and fixed, preventing excessive disordered growth or being scattered. After multiple cold-hot cycles, this controlled and rhythmic growth pattern makes nucleation and growth preferentially occur on the path with the lowest energy defined by the temperature field and the centrifugal field. The hexagonal honeycomb structure is the arrangement with the lowest energy under this periodic boundary condition, because it can most effectively release stress and minimize surface energy.

[0105] By adjusting the ratio of the substrate rotation speed to the sputtering power, the difference between the high mobility of copper and the low diffusivity of carbon is utilized to induce spontaneous competitive growth of materials under a dynamic temperature gradient, and finally a biomimetic honeycomb structure is formed, that is, copper atoms preferentially assemble into a continuous hexagonal conductive framework 110 in the rotation direction, carbon atoms fill the pores between the honeycomb structures and can coat the silicon particles (since there are a small number of exposed areas of silicon particles on the surface of the electrode after rolling, these areas become preferential deposition sites for carbon atoms after plasma activation, and are further covered by the deposited carbon layer 120), and a conductive network and an elastic buffer layer are simultaneously constructed (carbon has the functions of mechanical buffering, conductive enhancement, and interface stabilization compared with silicon). After sputtering, low-temperature annealing is performed to eliminate internal stress and optimize the copper-carbon interface bonding strength, and if necessary, atomic layer deposition technology can be further used to uniformly cover an ultrathin oxide layer on the surface to seal the micropores and inhibit side reactions.

[0106] In some embodiments, with reference to Figure 3 Further comprising, after forming the carbon-silicon active layer 101 and before forming the initial elastic film, performing an ion activation treatment on the carbon-silicon active layer 101 to form a concave-convex structure on the surface of the carbon-silicon active layer 101.

[0107] Specifically, the carbon-silicon active layer 101 is subjected to plasma activation treatment, the surface is bombarded by high-energy particles in argon-oxygen mixed gas to form a nanoscale rough structure and introduce active groups such as hydroxyl and carboxyl groups, so as to enhance the adhesion of the subsequent coating.

[0108] In some embodiments, after the plasma activation treatment of the carbon-silicon active layer 101, the following steps are included: vacuumizing to an air pressure ≤ 5 × 10 -4 Pa; introducing argon to 0.3 Pa to 0.8 Pa, pre-sputtering for 2 min to 5 min by a copper target and a carbon target to remove the oxide on the surface of the target material. In this way, the activity of the active groups such as hydroxyl and carboxyl groups on the surface of the carbon-silicon active layer 101 can be improved, and some oxidation by-products can be removed.

[0109] The preparation method comprises the following steps: providing a positive electrode sheet and a separator; stacking the negative electrode sheet, the separator and the positive electrode sheet in sequence; obtaining an electric core assembly by winding or stacking; and placing the electric core assembly into a battery shell, injecting an electrolyte into the battery shell, and then packaging to obtain a battery monomer.

[0110] The innovation of the embodiments of the present application lies in the dynamic co-sputtering deposition technology adopted in the preparation method. This technology can realize complex microstructure regulation in a single process. Although traditional methods such as carbon coating or nanocrystallization can alleviate the volume expansion problem of silicon-based materials to some extent, they often require multiple complex processes and are difficult to meet the multiple requirements of mechanical support, ion transmission and electronic conduction. By adjusting the substrate rotation speed and sputtering power ratio, the embodiments of the present application utilize the difference between the high mobility of copper atoms and the low diffusion of carbon atoms to induce spontaneous competition growth under a dynamic temperature gradient, forming a biomimetic honeycomb structure with excellent mechanical and electrochemical properties. This cross-scale collaborative design is not available in the prior art.

[0111] The embodiments of the present application utilize the magnetron sputtering technology to construct a biomimetic honeycomb structure on the surface of the silicon-carbon negative electrode, simulating the mechanical and material transmission characteristics of the honeycomb in nature. Through the competitive growth mechanism of copper and carbon double targets, the integration of the hexagonal conductive framework 110 and the elastic buffer layer is realized in a single low-temperature process. This unique structure not only effectively disperses the volume expansion stress generated during the charging and discharging process of the silicon material, reducing the risk of electrode pulverization, but also optimizes the transmission path of ions and electrons, thereby significantly improving the energy density, cycle life and fast charging performance of the battery.

[0112] According to some embodiments of the present application, the embodiments of the present application further provide a battery device, comprising: a battery monomer prepared by the preparation method of the battery monomer in any one of the above embodiments or a battery monomer according to the above embodiments. The battery device comprises one or more of a battery module, a battery pack, and an energy storage battery.

[0113] According to some embodiments of the present application, the present application further provides a power consuming device comprising the battery device as described above.

[0114] The power consuming device includes, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft, etc. The electric toy can include a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy, an electric aircraft toy, etc. The spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0115] According to some embodiments of the present application, the present application further provides an energy storage device comprising the battery device as described above.

[0116] The energy storage device includes, but is not limited to, a household energy storage cabinet, a commercial energy storage cabinet, an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system, etc. The energy storage device can further include an energy management system (EMS), a battery management system (BMS), and an energy storage power conversion system (PCS), etc.

[0117] The beneficial effects of the embodiments of the present application will be further illustrated in the following embodiments.

[0118] Embodiment 1: (1) Preparation of the negative electrode sheet: First, the surface of the carbon-silicon active layer is cleaned by ultrasonic cleaning to remove residual contaminants and ensure the cleanliness of the surface of the carbon-silicon active layer; then, dynamic co-sputtering deposition is performed on the silicon-carbon negative electrode sheet: 1. Copper target activation: turn on the DC power supply (120 W), and copper atoms are sputtered onto the surface of the substrate under the bombardment of argon ions. Due to the high mobility, copper atoms preferentially migrate along the tangential direction of the substrate rotation, forming a hexagonal skeleton prototype; 2. Carbon target synchronous sputtering: start the RF power supply (300 W), and carbon atoms are deposited in the interstitial space of the copper skeleton with low mobility, filling the pores and coating the silicon particles; 3. Rotation control: the substrate rotates at a constant speed of 10 rpm, and the centrifugal force and the non-uniformity of plasma irradiation form a periodic temperature gradient, which drives the periodic nucleation of copper atoms and self-assembles into honeycomb pore walls.

[0119] (2) Assembly of the battery cell.

[0120] Example 2: The steps are basically the same as those of Example 1, except that after the step of removing the surface residual contaminants of the carbon-silicon active layer, before the step of performing dynamic co-sputtering deposition on the silicon-carbon negative electrode sheet, the step of performing plasma activation treatment is included, i.e., using high-energy particle bombardment on the surface in argon-oxygen mixed gas to form a nano-scale rough structure and introduce active groups such as hydroxyl and carboxyl groups, so as to enhance the adhesion of the subsequent coating.

[0121] Subsequently, the chamber is prepared for pre-sputtering cleaning: the silicon-carbon negative electrode sheet after plasma activation is loaded into the sputtering chamber, vacuumized to an internal air pressure < 5x10 -4 Pa, argon gas is introduced to 0.3 Pa~0.8 Pa, and the copper target and carbon target are pre-sputtered for 3 min to remove the surface oxides of the target materials.

[0122] Comparative Example 1: The steps are basically the same as those of Example 1, except that there is no step of performing dynamic co-sputtering deposition on the silicon-carbon negative electrode sheet, i.e., the negative electrode sheet is a silicon-carbon negative electrode sheet, and the surface of the silicon-carbon negative electrode sheet has no elastic layer.

[0123] The contact angle test and the electrochemical performance test are sequentially performed on the examples and the comparative example, and the test results are summarized and recorded in Table 1.

[0124] Table 1

[0125] The experimental results show that this bionic honeycomb structure not only effectively inhibits the electrode pulverization failure, but also enhances the electrolyte wettability, further improving the stability of the electrode / electrolyte interface.

[0126] It can be understood by those skilled in the art that the above-mentioned embodiments are specific examples for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, therefore the protection scope of the present application should be limited by the scope defined in the claims.

Claims

1. A battery cell, characterized in that, include: A battery casing having a cavity inside, and an electrolyte being contained within the cavity; A battery cell assembly, wherein the battery cell assembly is located within the cavity and the battery cell assembly is located within the electrolyte; The battery cell assembly includes a positive electrode, a separator, and a negative electrode, wherein the negative electrode includes: Negative electrode current collector and silicon carbide active layer; An elastic layer is located on the silicon carbide active layer. The elastic layer includes a conductive framework and a carbon layer. The conductive framework is located within the carbon layer and is constructed from multiple hexagonal copper metal units in a honeycomb structure.

2. The battery cell according to claim 1, characterized in that, The elastic layer includes 2 to 3 layers of the conductive framework; the thickness of the conductive framework ranges from 100 nm to 200 nm.

3. The battery cell according to claim 1 or 2, characterized in that, The ratio of the unfolded area of ​​the conductive framework to that of the carbon layer is 1:(5~8).

4. The battery cell according to claim 1, characterized in that, The side length of the copper metal unit ranges from 50μm to 80μm.

5. The battery cell according to claim 1, characterized in that, Also includes: A plasma active layer is located between the silicon carbide active layer and the elastic layer.

6. The battery cell according to claim 5, characterized in that, The thickness of the plasma active layer is 1 nm to 100 nm.

7. A method for preparing a single battery cell, characterized in that, include: A negative electrode sheet is formed, the negative electrode sheet comprising: a negative electrode current collector and a silicon carbide active layer; An elastic layer is located on the silicon carbide active layer. The elastic layer includes a conductive framework and a carbon layer. The conductive framework is located within the carbon layer and is constructed from multiple hexagonal copper metal units in a honeycomb structure. A positive electrode and a separator are provided; the negative electrode, separator and positive electrode are stacked in sequence, and the negative electrode, separator and positive electrode are stacked in sequence. The cell assembly is obtained by winding or stacking. The cell assembly is placed into a battery case, electrolyte is injected into the battery case and then it is packaged to obtain a single battery cell.

8. The method for preparing a battery cell according to claim 7, characterized in that, The process steps for forming the negative electrode sheet include: Provide negative electrode current collector; A silicon carbide active layer is formed, wherein the silicon carbide active layer is located on the surface of the negative electrode current collector; The silicon carbide active layer is subjected to plasma activation treatment to form an uneven structure on the surface of the silicon carbide active layer. An initial elastic membrane is formed, wherein the initial elastic membrane has an initial conductive framework composed of copper atoms and carbon atoms, wherein the carbon atoms are located within the initial conductive framework and the carbon atoms encapsulate the silicon particles within the carbon silicon active layer. The initial elastic membrane is subjected to a conditioning process to cause the copper atoms in the initial conductive framework to self-assemble into hexagonal copper metal units and construct a honeycomb structure; the carbon atoms are constructed into the carbon layer.

9. The method for preparing a battery cell according to claim 8, characterized in that, The process steps for forming the initial elastic film include: sputtering copper atoms onto the silicon-carbon active layer using a copper target to form copper atoms, which form an initial conductive framework; and sputtering carbon atoms onto the silicon-carbon active layer using a carbon target to form carbon atoms, which are located within the initial conductive framework and coat the silicon particles within the silicon-carbon active layer.

10. The method for preparing a battery cell according to claim 9, characterized in that, The process steps for regulating the initial elastic membrane include: rotating the initial elastic membrane at a constant speed of 5 rpm to 20 rpm, using centrifugal force and plasma irradiation to drive the periodic nucleation of copper atoms, so that the copper atoms self-assemble into hexagonal copper metal units and construct a honeycomb structure.

11. The method for preparing a battery cell according to claim 9, characterized in that, The sputtering power used to sputter the silicon-carbon active layer with a copper target to form copper atoms is the first power; the sputtering power used to sputter the silicon-carbon active layer with a carbon target to form carbon atoms is the second power, and the ratio of the second power to the first power is 1.3 to 20.

12. The method for preparing a battery cell according to claim 11, characterized in that, The first power is 100W~180W; the second power is 270W~350W.

13. The method for preparing a battery cell according to claim 8, characterized in that, After plasma activation treatment of the silicon carbide active layer, the process includes: evacuating to a pressure ≤ 5 × 10⁻⁶. -4 Pa; introduce argon gas to 0.3 Pa~0.8 Pa, and pre-sputter through copper and carbon targets for 2 min~5 min.

14. A battery device, characterized in that, The battery device includes a battery cell prepared by the method of preparing a battery cell as described in any one of claims 1 to 6 or as described in any one of claims 7 to 13, and the battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

15. An electrical appliance, characterized in that, The electrical device includes the battery device as described in claim 14, the battery device being used to provide electrical energy.

16. An energy storage device, characterized in that, The energy storage device includes the battery device as described in claim 14, the battery device being used to store electrical energy.

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