Battery cell and preparation method therefor, and battery device and electric device

Abstract

Provided in the present application are a battery cell and a preparation method therefor, and a battery device and an electric device. The battery cell comprises a negative electrode sheet, the negative electrode sheet comprising a first layer and a non-metallic layer located on the surface on at least one side of the first layer, wherein the nucleation overpotential of Li on the non-metallic layer is V1, and the nucleation overpotential of Li on the first layer is V2, and V1>V2. The negative electrode sheet in the present application can induce the deposition of lithium metal on the surface of a first layer, mitigate dendrite growth and improve the uniformity of lithium metal deposition, thereby improving the cycling performance of battery cells.

Description

Battery cells and their preparation methods, battery devices and electrical devices

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411044915.2, filed on July 31, 2024, entitled “Battery cell and method of preparation thereof, battery device and power consumption device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, specifically to a battery cell and its preparation method, a battery device, and an electrical device. Background Technology

[0004] Compared to ion-ion battery cells, metal battery cells have a higher energy density. However, unlike the negative electrode of ion-ion battery cells, in metal batteries, metal is deposited on the surface of the negative electrode current collector during operation. The commonly used negative electrode current collector surface typically exhibits a localized nucleation pattern, where localized nuclei easily grow into a loose and porous structure. This leads to rapid volume expansion of the negative electrode current collector and generates severe side reactions. These side reactions continuously consume active materials and electrolytes, affecting the cycle performance of the battery cell. Summary of the Invention

[0005] This application provides a battery cell and its preparation method, a battery device, and an electrical device, which can reduce side reactions during metal deposition on the surface of the negative electrode current collector, reduce the consumption of active materials and electrolyte, thereby improving the cycle performance of the battery cell.

[0006] In a first aspect, embodiments of this application provide a battery cell including a negative electrode sheet. The negative electrode sheet includes a first layer and a non-metallic layer located on at least one side of the first layer. The nucleation overpotential of the non-metallic layer for Li is V1, and the nucleation overpotential of the first layer for Li is V2, where V1 > V2.

[0007] In this embodiment, by setting a non-metallic layer on the surface of the first layer and making the nucleation overpotential of the non-metallic layer for Li greater than that of the first layer for Li, during the charge-discharge cycle of the metal battery cell, lithium / sodium and other metals will be induced to deposit on the first layer and located between the first layer and the non-metallic layer. The presence of the non-metallic layer will inhibit dendrite growth and make the metal uniformly deposited on the surface of the first layer. This can reduce the risk of dendrite growth piercing the SEI film, thereby reducing the side reactions caused by SEI film rupture, reducing the consumption of active materials and electrolyte in the battery cell, and thus improving the cycle performance of the battery cell.

[0008] In some embodiments, V1-V2 ≥ 20mV. Limiting the difference between the nucleation overpotential V1 of the non-metallic layer and the nucleation overpotential V2 of the first layer on Li to the above range can make it easier for lithium metal to deposit on the surface of the first layer, reduce the deposition of lithium metal on the non-metallic surface, improve the uniformity of lithium metal deposition, further reduce the risk of dendrite growth piercing the SEI film during lithium metal deposition, and further improve the cycle performance of the battery cell.

[0009] In some embodiments, 20mV ≤ V1 - V2 ≤ 60mV. The difference between the nucleation overpotential V1 of the non-metallic layer on Li and the nucleation overpotential V2 of the first layer on Li is further limited to the above range, which can further induce lithium metal deposition on the surface of the first layer, slow down dendrite growth, improve the uniformity of lithium metal deposition, and thereby improve the cycle performance of the battery cell.

[0010] In some embodiments, the material of the first layer includes one or more of Cu, Ni, Ti, Mg, Al, copper alloys, nickel alloys, titanium alloys, magnesium alloys, and aluminum alloys. When the material of the first layer includes the above types, the first layer can be a negative electrode current collector, in which case the negative electrode sheet includes a negative electrode current collector and a non-metallic layer located on at least one side surface of the current collector.

[0011] In some embodiments, the material of the first layer includes one or more of Sn, Zn, Bi, Pb, Au, Ag, In, and Ga. When the material of the first layer includes the above types, the first layer can be other coating layers that can be coated onto the surface of the current collector. By providing a coating layer on the surface of the negative electrode current collector and controlling the nucleation overpotential of the coating layer for Li to be the minimum among the three layers, lithium metal deposition on the surface of the coating layer can be induced.

[0012] In some embodiments, the negative electrode further includes a second layer, wherein the first layer is located on at least one side surface of the second layer, and the non-metallic layer is located on the side surface of the first layer away from the second layer; the material of the first layer and the material of the second layer are different, and the material of the second layer includes one or more of Cu, Ni, Ti, Mg, Al, copper alloy, nickel alloy, titanium alloy, magnesium alloy, and aluminum alloy. The second layer can be a negative electrode current collector layer, thereby inducing the deposition of metals such as lithium / sodium on the surface of the coating layer by forming a coating layer on the negative electrode current collector layer.

[0013] In some embodiments, the material of the non-metallic layer includes one or more of C, Si, P, and compounds composed of the above materials.

[0014] In some embodiments, the compound includes one or both of silicon carbide and phosphorus carbide.

[0015] In some embodiments, the thickness of the non-metallic layer is greater than or equal to 20 μm.

[0016] In some embodiments, the thickness of the non-metallic layer is 30 μm to 60 μm.

[0017] By limiting the thickness of the non-metallic layer to the above range, the nucleation overpotential of the non-metallic layer on Li can be made greater than the nucleation overpotential of the negative electrode current collector on Li. As a result, lithium metal can be deposited on the surface of the negative electrode current collector during the charging cycle of the battery cell. The non-metallic layer slows down the dendrite growth during the lithium metal deposition process, reduces the risk of dendrite growth piercing the SEI film, reduces the consumption of active materials and electrolyte in the battery cell, and thus improves the cycle performance of the battery cell.

[0018] In some embodiments, the battery cell includes at least one of a negative electrode-free lithium metal battery cell and a negative electrode-free sodium metal battery cell.

[0019] Secondly, embodiments of this application provide a method for preparing a battery cell, including the preparation of a negative electrode sheet. The method for preparing the negative electrode sheet includes the following steps:

[0020] Substrate and non-metallic materials are provided separately;

[0021] The non-metallic material is used to form a non-metallic layer on at least one surface of the substrate; wherein,

[0022] The nucleation overpotential of the non-metallic layer to Li is V1, and the nucleation overpotential of the substrate to Li is V2, where V1 > V2.

[0023] In some embodiments, the non-metallic material includes one or more of C material, Si material, P material, and compounds composed of the above materials.

[0024] In some embodiments, the non-metallic material includes one or more of porous carbon, hard carbon, graphene, carbon nanotubes, carbon fibers, polycrystalline silicon, monocrystalline silicon, amorphous silicon, red phosphorus, black phosphorus, silicon carbide, and phosphorus carbide.

[0025] In some embodiments, the provided substrate includes:

[0026] Provide current collectors and metallic materials;

[0027] The metal material is used to form a coating on at least one side surface of the current collector; wherein the metal material is different from the material of the current collector.

[0028] In some embodiments, the material of the current collector includes one or more of Cu, Ni, Ti, Mg, Al, copper alloys, nickel alloys, titanium alloys, magnesium alloys, and aluminum alloys.

[0029] In some embodiments, the material of the coating includes one or more of Cu, Ni, Ti, Mg, Al, copper alloys, nickel alloys, titanium alloys, magnesium alloys, and aluminum alloys.

[0030] In some embodiments, the method for forming a non-metallic layer of the non-metallic material on at least one side of the substrate includes one or more of magnetron sputtering, ion beam sputtering, hydrothermal method, electrospinning, chemical vapor deposition, and 3D printing.

[0031] Thirdly, embodiments of this application provide a battery device, including a battery cell from the first aspect of this application or a battery cell obtained according to the preparation method of the second aspect of this application.

[0032] Fourthly, embodiments of this application provide an electrical device, including a battery device according to embodiments of the second aspect of this application. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 is a schematic diagram of a battery cell provided in some embodiments of this application.

[0035] Figure 2 is an exploded view of a battery cell provided in some embodiments of this application.

[0036] Figure 3 is a schematic diagram of a battery module provided in some embodiments of this application.

[0037] Figure 4 is a schematic diagram of a battery pack provided in some embodiments of this application.

[0038] Figure 5 is an exploded view of the battery pack shown in Figure 4.

[0039] Figure 6 is a schematic diagram of an electrical device provided in some embodiments of this application.

[0040] The accompanying drawings are not necessarily drawn to scale.

[0041] The reference numerals in the attached diagram are explained as follows: 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery module; 5. Battery cell; 51. Housing; 52. Electrode assembly; 53. Cover plate. Detailed Implementation

[0042] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the electrode assembly, battery cell, battery, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0043] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0044] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0045] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0046] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0047] Unless otherwise specified, the terms "connected" and "linked" in this application should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0048] In this application, "multiple" refers to two or more, including two. "Multiple types" refers to two or more, including two.

[0049] The battery device mentioned in the embodiments of this application can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery device mentioned in this application can include battery cells, battery modules, or battery packs.

[0050] A battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. A battery cell can be cylindrical, cuboid, or other shapes, and the embodiments of this application are not limited to this. Figure 1 shows a cuboid battery cell 5 as an example.

[0051] When there are multiple battery cells, they are connected in series, parallel, or mixed via a busbar. In some embodiments, the battery device can be a battery module; when there are multiple battery cells, they are arranged and fixed to form a battery module. In some embodiments, the battery device can be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed within the housing. In some embodiments, the housing can be part of the vehicle's chassis structure. For example, a portion of the housing can be at least part of the vehicle's floor, or a portion of the housing can be at least part of the vehicle's crossbeams and longitudinal beams.

[0052] In some embodiments, individual battery cells can be assembled into a battery module. The number of battery cells in a battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module. Figure 2 is a schematic diagram of a battery module 4 as an example. As shown in Figure 2, in the battery module 4, multiple battery cells 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other arbitrary manner. Furthermore, the multiple battery cells 5 can be fixed in place using fasteners.

[0053] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0054] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0055] Figures 3 and 4 are schematic diagrams of a battery pack 1 as an example. As shown in Figures 3 and 4, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The housing includes an upper housing 2 and a lower housing 3, with the upper housing 2 covering the lower housing 3 and forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the housing.

[0056] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0057] The battery cells provided in the embodiments of this application are negative electrode-free battery cells, and may include at least one of negative electrode-free lithium metal battery cells and negative electrode-free sodium metal battery cells.

[0058] A negative electrode-free battery cell typically refers to a battery cell in which no negative electrode active material layer is actively formed on the negative electrode side during the battery cell manufacturing process. For example, the negative electrode active material layer is not formed at the negative electrode through coating or deposition processes, or it is formed from a carbonaceous active material layer. During the first charge, ions gain electrons on the negative electrode side and deposit metal on the surface of the negative electrode current collector. During discharge, the metal can be converted back into ions and return to the positive electrode, achieving cyclic charging and discharging. Compared to other battery cells, a negative electrode-free battery cell can achieve a higher energy density due to the absence of a negative electrode active material layer. In some embodiments, to improve battery cell performance, some conventional materials that can be used as negative electrode active materials, such as carbon materials, can also be placed on the negative electrode side of the negative electrode-free battery cell. Although these materials have a certain capacity, because their content is small and they are not used as the main negative electrode active material in the battery cell, such a battery cell can still be considered a negative electrode-free battery cell. The Cell Balance (CB) value of a negative electrode-free battery cell is typically very small; for example, in some embodiments, the CB value of a negative electrode-free battery cell can be less than or equal to 0.1. The CB value is the capacity per unit area of ​​the negative electrode divided by the capacity per unit area of ​​the positive electrode in the battery cell. Because a negative electrode-free battery cell contains little or no negative electrode active material, the capacity per unit area of ​​the negative electrode is small, and therefore the CB value is very small, typically less than or equal to 0.1.

[0059] The battery cell includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to this.

[0060] Electrode assemblies generally include a positive electrode, a negative electrode, and a separator.

[0061] The battery cell may also include an outer packaging, which can be used to encapsulate the electrode assembly. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0062] In some embodiments, as shown in FIG5, the outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates enclosing a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 is used to cover the opening to close the receiving cavity. Electrode assemblies 52 are encapsulated in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, and can be adjusted as needed.

[0063] [Negative electrode plate]

[0064] The negative electrode includes a first layer and a non-metallic layer located on at least one side of the first layer. The nucleation overpotential of the non-metallic layer to Li is V1, and the nucleation overpotential of the first layer to Li is V2, where V1 > V2.

[0065] Metal-based battery cells do not incorporate conventional carbon or other negative electrode active materials on the negative electrode side. During charge-discharge cycles, lithium / sodium and other metals deposit on the surface of the first layer. Since the first layer typically uses a localized nucleation pattern, lithium / sodium deposits can exhibit needle-like, moss-like, or dendritic morphologies, eventually forming dendrites. When these dendrites grow to a certain extent, they may pierce the solid electrolyte interphase (SEI) membrane, leading to an internal short circuit within the battery cell. This can ultimately result in thermal runaway or even an explosion. Furthermore, during charge-discharge cycles, the continuous deposition and peeling of lithium / sodium on the first layer exposes fresh lithium / sodium, which reacts with the electrolyte, consuming electrolyte and active materials, thus limiting the battery cell's cycle performance.

[0066] In this embodiment, the first layer can be a negative electrode current collector or a coating layer that can be coated onto the surface of the negative electrode current collector. By setting a non-metallic layer on the surface of the first layer and making the nucleation overpotential of the non-metallic layer for Li greater than that of the first layer for Li, lithium / sodium and other metals will be induced to deposit on the surface of the first layer during the charge-discharge cycle of the metal battery cell. Since the lithium / sodium metal is deposited between the first layer and the non-metallic layer, the presence of the non-metallic layer will hinder the growth of dendrites, so that the metal is uniformly deposited on the surface of the first layer. This can reduce the risk of dendrite growth piercing the SEI film, reduce the side reactions caused by the rupture of the SEI film, reduce the consumption of active materials and electrolyte in the battery cell, and thus improve the cycle performance of the battery cell.

[0067] In this embodiment, the nucleation overpotential of the first layer and the non-metallic layer for Li can be measured as follows: In an argon-protected glove box, a coin cell is assembled with a lithium metal sheet as the counter electrode and a sheet of material corresponding to the first layer or the non-metallic layer. The electrolyte salt is LiFSI with a concentration of 1 mol / L, and the solvent is dimethyl ethylene glycol ether (DME). The separator is a PE membrane with a thickness of 12 μm.

[0068] After the assembled button cell was left to stand for 12 hours at 25°C, it was tested at 1 mA / cm². 2 Constant current discharge to 1 mAh / cm 2At the start of the lithium metal deposition process, there is a significant voltage drop followed by a flat voltage plateau. The difference between the voltage at the lowest point of the discharge curve and the flat portion of the voltage plateau (in absolute terms) is used as the overpotential for lithium metal nucleation in the first or non-metallic layer.

[0069] It should be noted that the specific values ​​of the lithium metal nucleation overpotential of the above-mentioned negative electrode current collector and non-metallic layer are used to represent the physicochemical properties of the first layer or non-metallic layer, as well as the affinity between the first layer material or non-metallic layer material and the deposited metal. They do not mean that the negative electrode current collector provided in this application embodiment can only be used in negative electrode-free lithium metal battery cells. The negative electrode current collector provided in this application embodiment can also be used in negative electrode-free sodium metal battery cells.

[0070] In some embodiments, V1 can be 60mV to 120mV.

[0071] In some embodiments, V2 can be 40mV to 65mV.

[0072] In some embodiments, V1-V2 ≥ 20mV. When the nucleation overpotential of the non-metallic layer on Li is greater than the nucleation overpotential of the negative first layer on Li, lithium metal is more easily deposited on the surface of the first layer, thereby slowing down dendrite growth during lithium metal deposition and reducing the risk of dendrites piercing the SEI film. Further limiting the difference between the nucleation overpotential V1 of the non-metallic layer on Li and the nucleation overpotential V2 of the first layer on Li within the above range makes it easier for lithium metal to deposit on the surface of the first layer, reducing lithium metal deposition on the non-metallic surface, improving the uniformity of lithium metal deposition, further reducing the risk of dendrite growth piercing the SEI film during lithium metal deposition, and further improving the cycle performance of the battery cell.

[0073] In some embodiments, 20mV ≤ V1-V2 ≤ 60mV. Exemplarily, the values ​​of V1-V2 can be 20mV, 21mV, 22mV, 23mV, 24mV, 25mV, 26mV, 27mV, 28mV, 29mV, 30mV, 31mV, 32mV, 33mV, 34mV, 35mV, 36mV, 37mV, 38mV, 39mV, 40mV, 41mV, 42mV, 43mV, 44mV, 45mV, 46mV, 47mV, 48mV, 49mV, 50mV, 51mV, 52mV, 53mV, 54mV, 55mV, 56mV, 57mV, 58mV, 59mV, or 60mV.

[0074] The difference between the nucleation overpotential V1 of the non-metallic layer and the nucleation overpotential V2 of the first layer for Li is further limited to the above range, which can further induce lithium metal deposition on the surface of the first layer, further slow down dendrite growth, improve the uniformity of lithium metal deposition, and thus improve the cycle performance of the battery cell.

[0075] In some embodiments, the material of the first layer may include one or more of Cu, Ni, Ti, Mg, Al, copper alloys, nickel alloys, titanium alloys, magnesium alloys, and aluminum alloys.

[0076] When the material of the first layer includes the types described above, the first layer can be a negative electrode current collector. In this case, the negative electrode sheet includes a negative electrode current collector and a non-metallic layer located on at least one side of the surface of the negative electrode current collector. The nucleation overpotential of the first layer on Li is the same as the nucleation overpotential of the negative electrode current collector on Li. By limiting the nucleation overpotential of the non-metallic layer on Li to be greater than the nucleation overpotential of the negative electrode current collector on Li, lithium metal can be deposited on the surface of the negative electrode current collector through the non-metallic layer. The growth of lithium dendrites is suppressed by the non-metallic layer, resulting in uniform deposition of lithium metal, thereby reducing the risk of dendrite growth piercing the separator.

[0077] In some embodiments, the material of the first layer may include one or more of Sn, Zn, Bi, Pb, Au, Ag, In, and Ga.

[0078] When the material of the first layer includes the above-mentioned types, the first layer can be a coating layer that can be coated on the surface of the negative electrode current collector. In this case, the nucleation overpotential of the first layer to Li is the same as the nucleation overpotential of the coating layer to Li. By controlling the nucleation overpotential of the coating layer to Li to be less than the nucleation overpotential of the non-metallic layer to Li, lithium metal can be induced to deposit through the non-metallic layer onto the surface of the coating layer.

[0079] In some embodiments, the negative electrode further includes a second layer, wherein the first layer is located on at least one side surface of the second layer, and a non-metallic layer is located on the side surface of the first layer away from the second layer; the material of the second layer is different from the material of the first layer, and the material of the second layer may include one or more of Cu, Ni, Ti, Mg, Al, copper alloy, nickel alloy, titanium alloy, magnesium alloy, and aluminum alloy.

[0080] The second layer can be a negative electrode current collector. In this case, the first layer can be a coating layer applied to the surface of the negative electrode current collector. The material of the coating layer is a lithium-loving metal, whose nucleation overpotential for Li is less than that of the negative electrode current collector for Li. This can induce lithium metal to pass through the non-metallic layer and deposit on the surface of the coating layer.

[0081] In some embodiments, the non-metallic layer comprises a non-metallic material, which may include one or more of C material, Si material, P material, and compounds composed of the above materials.

[0082] In the embodiments of this application, C material, Si material and P material refer to materials containing elemental C, elemental Si or elemental P, respectively.

[0083] Optionally, the compound composed of the above materials may include one or both of silicon carbide and phosphorus carbide.

[0084] In some embodiments, the thickness of the non-metallic layer can be greater than or equal to 20 μm. The thickness affects the nucleation overpotential of the non-metallic layer for Li. By limiting the thickness of the non-metallic layer to the above range, the nucleation overpotential of the non-metallic layer for Li can be made greater than that of the first layer for Li. This allows lithium metal to be deposited on the surface of the first layer during the charging cycle of the battery cell. The non-metallic layer slows down dendrite growth during the lithium metal deposition process, reducing the risk of dendrite growth piercing the SEI film, reducing the consumption of active materials and electrolyte in the battery cell, and thus improving the cycle performance of the battery cell.

[0085] In some embodiments, the thickness of the non-metallic layer can be from 30 μm to 60 μm. Exemplarily, the thickness of the non-metallic layer can be 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm, 51 μm, 52 μm, 53 μm, 54 μm, 55 μm, 56 μm, 57 μm, 58 μm, 59 μm, or 60 μm.

[0086] Limiting the thickness of the non-metallic layer within the aforementioned range facilitates lithium metal deposition between the non-metallic layer and the first layer, reducing dendrite growth during lithium metal deposition, improving the uniformity of lithium metal deposition, and thus enhancing the cycle performance of the battery cell. When the non-metallic layer is thinner, the nucleation overpotential for Li is lower, making it more difficult to induce lithium metal deposition between the first and non-metallic layers, leading to dendrite growth and even penetration of the SEI film, affecting the cycle performance of the battery cell. When the non-metallic layer is thicker, its conductivity is lower, hindering lithium ion penetration and limiting the lithium deposition / stripping process, resulting in poorer cycle performance.

[0087] In some embodiments, the non-metallic layer can be deposited on the surface of the negative electrode current collector by means of magnetron sputtering (PVD), ion beam sputtering, hydrothermal method, electrospinning, chemical vapor deposition (CVD), or 3D printing.

[0088] Optionally, the non-metallic layer can be deposited on the surface of the negative electrode current collector by magnetron sputtering.

[0089] Compared to other methods, magnetron sputtering is simpler, faster, and more convenient to operate. At the same time, the non-metallic layer formed by magnetron sputtering has a higher bonding force with the negative electrode current collector, and the stability of the non-metallic layer is also better.

[0090] In some embodiments, the preparation of a single battery cell may include the preparation of a negative electrode sheet, and the method for preparing the negative electrode sheet may include the following steps:

[0091] S10 provides base material and non-metallic material respectively;

[0092] S20, a non-metallic layer is formed on at least one side surface of the substrate by a non-metallic material; wherein the nucleation overpotential of the non-metallic layer to Li is V1, and the nucleation overpotential of the substrate to Li is V2, where V1 > V2.

[0093] In some embodiments, the method of forming a non-metallic layer may include one or more of magnetron sputtering (PVD), ion beam sputtering, hydrothermal method, electrospinning, chemical vapor deposition (CVD), and 3D printing.

[0094] In some embodiments, the non-metallic material may include one or more of C material, Si material, P material, and compounds composed of the above materials.

[0095] Optionally, material C may include one or more of porous carbon, hard carbon, graphene, carbon nanotubes, and carbon fibers.

[0096] Si materials can include one or more of polycrystalline silicon, monocrystalline silicon, and amorphous silicon.

[0097] P-materials can include one or both of red phosphorus and black phosphorus.

[0098] The compound may include one or both of silicon carbide and phosphorus carbide.

[0099] In this embodiment, the substrate can be a negative electrode current collector or a substrate formed by applying a coating to the surface of the negative electrode current collector.

[0100] In some embodiments, the substrate may include a negative electrode current collector and a coating disposed on at least one side of the negative electrode current collector. In this case, the substrate may be prepared by the following method:

[0101] (1) Provide current collector and metal materials respectively;

[0102] (2) Form a coating of metal material on at least one side surface of the current collector; wherein the metal material is different from the material of the current collector.

[0103] In some embodiments, the material of the current collector may include one or more of Cu, Ni, Ti, Mg, Al, copper alloys, nickel alloys, titanium alloys, magnesium alloys, and aluminum alloys.

[0104] In some embodiments, the metallic material may include one or more of Cu, Ni, Ti, Mg, Al, copper alloys, nickel alloys, titanium alloys, magnesium alloys, and aluminum alloys; wherein the metallic material is different from the material of the current collector.

[0105] [Positive electrode plate]

[0106] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and comprising a positive electrode active material. For example, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0107] In some embodiments, the positive electrode active material includes a material capable of extracting and inserting lithium, thereby obtaining a negative electrode-free lithium metal battery cell.

[0108] As examples, positive electrode active materials may include, but are not limited to, one or more of lithium transition metal oxides, metal chalcogenides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, lithium titanium oxides, and their respective modified compounds. Lithium transition metal oxides may include, but are not limited to, layered structures and spinel structures. Examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, lithium iron manganese phosphate and carbon composites, and their respective modified compounds.

[0109] In some embodiments, to further improve the energy density of a single battery cell, the positive electrode active material may include materials of the general formula Li. a Ni b Co c M d O e D f One or more of lithium transition metal oxides and their modified compounds. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M may include, but is not limited to, one or more of Ge, Mo, Sn, Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and D may include, but is not limited to, one or more of N, F, S and Cl.

[0110] In some embodiments, the positive electrode active material may simultaneously comprise lithium transition metal oxide and lithium phosphate. This is advantageous for obtaining battery cells that balance high capacity and high reliability.

[0111] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, and LiNi 1 / 2 Mn 1 / 2 O2, LiMn2O4, Li 4 / 3 Ti 5 / 3 O4, LiNi 1 / 2 Mn 1 / 2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.80 Co 0.15 Al 0.05 O2, LiFePO4, LiMnPO4, Li 1.13 Ti 0.57 Fe 0.3 One or more of S2.

[0112] In some embodiments, the positive electrode active material includes a material capable of both sodium extraction and insertion. This results in a sodium-free negative electrode battery cell. For example, the positive electrode active material may include, but is not limited to, one or more of layered transition metal oxides (including, but not limited to, P2-type, O3-type, etc.), polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian materials.

[0113] In some embodiments, as an example, the positive electrode active material may include, but is not limited to, NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, Na 0.67MO2 (M includes at least two of Fe, Co, Cr, Mn, Ni, V, Ti, and Mo), NaMO2 (M includes at least two of Fe, Co, Ni, V, Ti, and Mo), NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, Prussian white, and one or more of their respective modified compounds.

[0114] The modified compounds for the above-mentioned positive electrode active materials can be obtained by doping and / or surface coating of the positive electrode active materials.

[0115] In some embodiments, the positive electrode film may optionally include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0116] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene oxide, fluorinated acrylate resins, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0117] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a first layer of polymeric material and a layer of metallic material formed on at least one surface of the first layer of polymeric material. As an example, the metallic material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the first layer of polymeric material may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0118] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, positive electrode conductive agents, positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to this.

[0119] [Isolation membrane]

[0120] The separator is located between the positive and negative electrodes and mainly serves to prevent internal short circuits.

[0121] This application does not impose any particular restrictions on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0122] In some embodiments, the material of the separator may include, but is not limited to, one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.

[0123] [Electrolytes]

[0124] A single battery cell includes an electrolyte.

[0125] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0126] In some embodiments, the electrolyte includes anion, which may include bis(fluorosulfonyl)imide anion (FSI). - ), bis(trifluoromethanesulfonyl)imide anion (TFSI) - ), dioxaborate anion (BOB) - ), difluorooxalate borate anion (DFOB) - ), difluorodioxanol phosphate anion (DFOP) - ), tetrafluorooxalate phosphate anion (TFOP) - ), difluorophosphate anion (PO2F2) - ), hexafluorophosphate anion (PF6) - ), tetrafluoroborate anion (BF4) - ), hexafluoroarsenate anion (AsF6) - ), trifluoromethanesulfonate anion (CF3SO3) - One or more of the following.

[0127] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0128] In some embodiments, the concentration of the electrolyte salt may be 0.3 mol / L or higher, optionally 0.7 mol / L or higher, and further optionally 4 mol / L or lower, optionally 2.5 mol / L or lower, or 1.7 mol / L or lower. When the concentration of the electrolyte salt is within the above range, the electrolyte can have a suitable ionic conductivity.

[0129] Organic solvents may include, but are not limited to, one or more of esters, ethers, sulfones, and nitriles. Esters may include, but are not limited to, one or more of carbonates, phosphate esters, carboxylic esters, sulfate esters, and sulfonates. Carbonates may include cyclic carbonates and / or chain carbonates; optionally, carbonates may include both cyclic and chain carbonates. Chain carbonates may include low-viscosity polar chain carbonates, aliphatic branched carbonates, etc.

[0130] As an example, organic solvents may include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), butene carbonate, ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), dimethyl ether tetraethylene glycol (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL), trimethyl phosphate, 3-methoxypropionitrile, H(CF2)2OCH3, C4F9O CH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, H(CF2)2CH2O(CF2)2H, CF3CHFCF2OCH3, CF3CHFCF2OCH2CH3, 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyloctafluorobutyl methyl ether, 3-trifluoromethyloctafluorobutyl ethyl ether, 3-trifluoromethyloctafluorobutyl propyl ether, 4-trifluoromethyl One or more of the following: decafluoropentyl methyl ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether, 5-trifluoromethyl dodecylfluorohexyl methyl ether, 5-trifluoromethyl dodecylfluorohexyl ethyl ether, 5-trifluoromethyl dodecylfluorohexyl propyl ether, 6-trifluoromethyl tetradecafluoroheptyl methyl ether, 6-trifluoromethyl tetradecafluoroheptyl ethyl ether, 6-trifluoromethyl tetradecafluoroheptyl propyl ether, 7-trifluoromethyl hexadecylfluorooctyl methyl ether, 7-trifluoromethyl hexadecylfluorooctyl ethyl ether, and 7-trifluoromethyl hexadecylfluorooctyl propyl ether.

[0131] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, additives that improve battery low-temperature power performance, etc.

[0132] Methods for preparing battery cells are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer package, dried, and then injected with the electrolyte. After vacuum sealing, settling, and formation processes, a battery cell is obtained. Multiple battery cells can be further connected in series, parallel, or a combination thereof to form a battery module. Multiple battery modules can also be connected in series, parallel, or a combination thereof to form a battery pack. In some embodiments, multiple battery cells can also be directly assembled into a battery pack.

[0133] This application also provides an electrical device, which includes the battery device provided in this application. The battery device can be used as the power source for the electrical device or as the energy storage unit of the electrical device. The electrical device can be, but is not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0134] Electrical devices can choose the type of battery according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0135] Figure 6 is a schematic diagram of an example electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0136] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0137] Example

[0138] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0139] Example 1

[0140] Negative electrode sheet

[0141] Commercially available double-sided glossy two-dimensional copper foil, 8μm thick.

[0142] S10, wipe the copper foil surface with 1 mol / L acetic acid solution, let stand for 20 min, continue to wipe the copper foil surface with anhydrous ethanol, then ultrasonically clean with deionized water for 5 min, and vacuum dry at 80℃ for 30 min.

[0143] S20, cut the dried copper foil sample into 4cm×4cm size, place it on the sample stage of the ion sputtering instrument, install the C target material, which is graphene, and evacuate to a vacuum degree of 3.0Pa.

[0144] S30, after injecting argon gas into the magnetron sputtering instrument chamber to 1 bar, evacuate again to a vacuum level of 3.0 Pa;

[0145] S40, with a magnetron sputtering current of 60mA and a magnetron sputtering time of 24min, a non-metallic layer was fabricated on copper foil. The thickness of the non-metallic layer was 60μm.

[0146] battery cell

[0147] Lithium iron phosphate, conductive carbon black (Super P), and binder polyvinylidene fluoride (PVDF) are mixed evenly in an appropriate amount of solvent N-methylpyrrolidone (NMP) at a weight ratio of 8:1:1 to obtain a positive electrode slurry. The positive electrode slurry is coated onto a positive electrode current collector aluminum foil and dried to obtain a positive electrode sheet.

[0148] In an argon-protected glove box, the positive electrode, the prepared negative electrode, and the separator were assembled into a coin cell. The electrolyte salt was LiFSI with a concentration of 1 mol / L, and the solvent was dimethyl ethylene glycol ether (DME). The separator was a 12 μm thick PE membrane.

[0149] Examples 2 to 10

[0150] The preparation of the negative electrode sheet is the same as in Example 1, with the differences detailed in Table 1.

[0151] Example 11

[0152] The non-metallic layer is prepared using a hydrothermal method, the specific method of which is as follows:

[0153] S10, commercially available double-sided glossy two-dimensional copper foil, 8μm thick, cut to 4cm×4cm specifications;

[0154] S20, commercially available graphene oxide dispersion with a concentration of 5 mg / mL, take 60 mL of graphene oxide dispersion and mix with 1.5 g of ascorbic acid, and sonicate for 15 min;

[0155] S30: A mixture of graphene oxide and copper foil is placed in a high-pressure reactor and reacted at 180°C for 12 hours to obtain a non-metallic layer on the copper foil. The non-metallic layer is graphene. The average thickness of the non-metallic layer is 60 μm.

[0156] Everything else is the same as in implementation 1.

[0157] Example 12

[0158] Negative electrode sheet

[0159] Commercially available double-sided glossy two-dimensional copper foil, 8μm thick.

[0160] S10, wipe the copper foil surface with 1 mol / L acetic acid solution, let stand for 20 min, continue to wipe the copper foil surface with anhydrous ethanol, then ultrasonically clean with deionized water for 5 min, and vacuum dry at 80℃ for 30 min.

[0161] S20, cut the dried copper foil sample into 4cm×4cm dimensions, place it on the sample stage of the ion sputtering instrument, install the Bi target, and evacuate to a vacuum degree of 3.0Pa;

[0162] S30, after injecting argon gas into the magnetron sputtering instrument chamber to 1 bar, evacuate again to a vacuum level of 3.0 Pa;

[0163] S40, set the magnetron sputtering current to 30mA and the magnetron sputtering time to 8min, and a Bi coating layer with a thickness of 200nm is prepared on the copper foil.

[0164] S50, replace the C target material and evacuate to a vacuum level of 3.0 Pa;

[0165] S60, after injecting argon gas into the magnetron sputtering instrument chamber to 1 bar, evacuate again to a vacuum level of 3.0 Pa;

[0166] S70, with a magnetron sputtering current of 60mA and a magnetron sputtering time of 24min, a non-metallic layer with a thickness of 60μm was formed on the Bi coating.

[0167] The preparation method of the battery cell is the same as that in Example 1.

[0168] Comparative Example 1

[0169] Commercially available double-sided glossy two-dimensional copper foil, 8μm thick, was used as the negative electrode.

[0170] Comparative Example 2

[0171] The preparation of the negative electrode sheet is the same as in Example 1, with the differences detailed in Table 1.

[0172] Test section

[0173] (1) Nucleation overpotential

[0174] In an argon-protected glove box, a coin cell was assembled with a lithium metal sheet as the counter electrode and sheets of corresponding materials. The electrolyte salt was LiFSI with a concentration of 1 mol / L, and the solvent was dimethyl ethylene glycol ether (DME). The separator was a 12 μm thick PE membrane.

[0175] After the assembled button cell was left to stand for 12 hours at 25°C, it was tested at 1 mA / cm². 2 Constant current discharge to 1 mAh / cm 2 At the beginning of the lithium metal deposition process, there is a significant voltage drop, followed by a flat voltage plateau. The difference between the voltage at the lowest point of the discharge curve and the flat part of the voltage plateau (in absolute terms) is taken as the metal nucleation overpotential of the corresponding material.

[0176] (2) Short circuit time

[0177] In an argon-protected glove box, a coin cell was assembled using the prepared negative electrode sheet as the positive electrode and a lithium sheet as the negative electrode. The electrolyte salt was LiFSI at a concentration of 1 mol / L, and the solvent was dimethyl glycol ether (DME). A 12 μm thick PE membrane was used as the separator. The coin cell was subjected to an 1 mA / cm² pressure at 25°C. 2 Constant current discharge is performed at a constant current density until a short circuit signal appears (the battery voltage jumps to 0), and the time from the start of discharge to the short circuit is recorded.

[0178] (3) Cyclic stability

[0179] At 25℃, after the assembled coin cells were left to stand for 12 hours, they were charged at a constant current of 0.2C to 3.65V, and then charged at a constant voltage of 3.65V to 0.05C. After the coin cells were left to stand for 10 minutes, they were discharged at a constant current of 0.5C to 2V. The coin cells were cycled through the above charging and discharging process until the discharge capacity decreased to 50% of the capacity of the first discharge cycle, and the number of cycles was recorded. More than six coin cell samples could be used for testing, and the average value of the test results was taken.

[0180] The test results are detailed in Table 1.

[0181] Based on the data in Table 1, it can be seen that by setting a non-metallic layer on the surface of the first layer and controlling the overpotential of the non-metallic layer for Li to be greater than the overpotential of the first layer for Li to be greater, the dendritic growth of lithium metal deposition in the battery cell during charge-discharge cycles can be reduced, the short-circuit time of the battery cell is significantly extended, and the cycle performance is significantly improved.

[0182] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. 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 by, The negative electrode sheet comprises a first layer and a non-metallic layer on at least one side surface of the first layer, the nucleation overpotential of the non-metallic layer to Li is V1, the nucleation overpotential of the first layer to Li is V2, and V1>V2.

2. The battery cell of claim 1, wherein, The nucleation overpotential of the non-metallic layer to Li V1 and the nucleation overpotential of the first layer to Li V2 satisfy: V1-V2≥20mV.

3. The battery cell of claim 2, wherein, The nucleation overpotential of the non-metallic layer to Li V1 and the nucleation overpotential of the first layer to Li V2 satisfy: 20mV≤V1-V2≤60mV.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The material of the first layer comprises one or more of Cu, Ni, Ti, Mg, Al, copper alloy, nickel alloy, titanium alloy, magnesium alloy and aluminum alloy.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The material of the first layer comprises one or more of Sn, Zn, Bi, Pb, Au, Ag, In and Ga.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The negative electrode sheet further comprises a second layer, the first layer is located on at least one side surface of the second layer, and the non-metallic layer is located on the side surface of the first layer away from the second layer; the material of the second layer is different from that of the first layer, and the material of the second layer comprises one or more of Cu, Ni, Ti, Mg, Al, copper alloy, nickel alloy, titanium alloy, magnesium alloy and aluminum alloy.

7. The battery cell of any one of claims 1 to 6, wherein, The material of the non-metallic layer comprises one or more of C material, Si material, P material and compound composed of the above materials.

8. The battery cell of claim 7, wherein, The compound comprises one or both of silicon carbide and phosphorus carbide.

9. The battery cell of any one of claims 1 to 8, wherein, The thickness of the non-metallic layer is greater than or equal to 20μm.

10. The battery cell of claim 9, wherein, The thickness of the non-metallic layer is 30μm to 60μm.

11. The battery cell of any one of claims 1 to 10, wherein, The battery cell comprises one or both of a negative electrode-free lithium metal battery cell and a negative electrode-free sodium metal battery cell.

12. A method of producing a battery cell, characterized by, The method for preparing a negative electrode sheet comprises the following steps: The substrate and the non-metallic material are provided respectively; The non-metallic material is formed into a non-metallic layer on at least one side surface of the substrate; wherein, The nucleation overpotential of the non-metallic layer to Li is V1, and the nucleation overpotential of the substrate to Li is V2, and V1>V2.

13. The method of claim 12, wherein, The non-metallic material comprises one or more of C material, Si material, P material and compound composed of the above materials.

14. The production method according to claim 12 or 13, characterized by, The non-metallic material comprises one or more of porous carbon, hard carbon, graphene, carbon nanotube, carbon fiber, polycrystalline silicon, single crystal silicon, amorphous silicon, red phosphorus, black phosphorus, silicon carbide and phosphorus carbide.

15. The method of making according to any one of claims 12 to 14, wherein, The substrate is provided by: The current collector and the metal material are provided respectively; The metal material is formed into a coating layer on at least one side surface of the current collector; wherein the metal material is different from the material of the current collector.

16. The method of claim 15, wherein, The material of the current collector comprises one or more of Cu, Ni, Ti, Mg, Al, copper alloy, nickel alloy, titanium alloy, magnesium alloy and aluminum alloy; and / or The material of the coating layer comprises one or more of Cu, Ni, Ti, Mg, Al, copper alloy, nickel alloy, titanium alloy, magnesium alloy and aluminum alloy.

17. The method of making according to any one of claims 12 to 16, wherein, The method of forming the non-metallic layer on at least one side surface of the substrate includes one or more of magnetron sputtering, ion beam sputtering, hydrothermal method, electrospinning, chemical vapor deposition, 3D printing.

18. A battery device characterized by comprising: A battery cell comprising the battery cell of any one of claims 1 to 11 or a battery cell obtained by the method of any one of claims 12 to 17.

19. An electrical device, comprising: A battery device comprising the battery cell of claim 12.

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