Negative electrode current collector, battery cell, battery, and electrical apparatus

Abstract

A negative electrode current collector, a battery cell, a battery, and an electrical apparatus. The negative electrode current collector comprises a negative electrode substrate and a modification layer located on at least one side of the negative electrode substrate, the modification layer comprising an active reaction layer, and a layered material layer located between the active reaction layer and the negative electrode substrate. The battery has good cycle performance.

Description

Negative electrode current collector, battery cell, battery and electrical device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202410167441.4 filed on February 5, 2024, entitled “Negative electrode current collector, battery cell, battery and electrical device,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a negative electrode current collector, a battery cell, a battery, and an electrical device. Background Art

[0004] Compared to ionic battery cells, metal battery cells can have higher energy density. However, unlike the negative electrodes of ionic battery cells, the surface of the negative electrode current collector commonly used in metal battery cells is mostly characterized by localized nucleation. Localized nuclei easily grow into loose, porous moss or dendritic structures, which leads to a sharp increase in the specific surface area of ​​the negative electrode and produces severe side reactions, seriously impairing the cycling performance of the metal battery cells. The above statements are intended only to provide background information related to this application and do not necessarily constitute prior art.

[0005] Summary of the Invention

[0006] The present application provides a negative electrode current collector, a battery cell, a battery and an electrical device, which can enable the battery to have good cycle performance.

[0007] In a first aspect, the present application provides a negative electrode current collector comprising a negative electrode substrate and a modified layer located on at least one side of the negative electrode substrate, wherein the modified layer comprises an active reaction layer and a layered material layer located between the active reaction layer and the negative electrode substrate.

[0008] By locating the layered material layer between the active reaction layer and the negative electrode matrix, the layered material layer can act as a buffer layer, reducing the volume expansion of the negative electrode caused by the deposition of metals such as lithium and sodium, thereby maintaining good electronic contact between the modified layer and the negative electrode matrix during the battery cell cycle, thereby improving the cycle performance of the battery cell.

[0009] In some embodiments, the thickness of the active reaction layer is 1 to 25 times, and optionally 2 to 20 times, the thickness of the layered material layer. This not only increases the active sites on the surface of the negative electrode current collector and reduces the nucleation overpotential of the negative electrode current collector, but also reduces the volume expansion of the negative electrode caused by the metal deposition process, improving the problem of unlimited volume expansion of the negative electrode, thereby further improving the cycling performance of the battery cell.

[0010] In some embodiments, the active reaction layer has a thickness of 50 nm to 1000 nm; and / or the layered material layer has a thickness of 5 nm to 500 nm.

[0011] The thickness of the active reaction layer being within the above range is beneficial to reducing the nucleation overpotential of the negative electrode current collector and reducing the formation of loose and porous moss structures or dendrite structures, thereby improving the cycle performance of the battery cell.

[0012] The thickness of the layered material layer is within the above range, which can reduce the risk of rupture and pulverization of the active reaction layer, thereby enabling the battery cell to have good cycle performance.

[0013] In addition, the layered material layer can react with the deposited metal, so as the thickness of the layered material layer increases, the first coulombic efficiency of the battery decreases. Therefore, when the thickness of the layered material layer is within the above range, the battery cell can also have a higher first coulombic efficiency.

[0014] Optionally, the thickness of the active reaction layer is 300 nm-1000 nm; and / or the thickness of the layered material layer is 20 nm-500 nm.

[0015] Optionally, the thickness of the active reaction layer is 300 nm-750 nm; and / or the thickness of the layered material layer is 25 nm-250 nm.

[0016] This can make the battery cell have good cycle performance and high first coulombic efficiency.

[0017] In some embodiments, the surface density of the active reaction layer is greater than or equal to 0.5 g / m 2 ; and / or, the surface density of the layered material layer is greater than or equal to 0.5g / m 2 .

[0018] In some embodiments, the layered material layer includes a layered material having an electronic conductivity greater than or equal to 5 S / m. The layered material has good electronic conductivity, which facilitates the intercalation of metals such as lithium and sodium into the interlayers of the layered material during battery cell charging. This facilitates the layered material layer to better serve as a buffer layer, thereby better reducing the volume expansion of the negative electrode caused by the deposition of metals such as lithium and sodium, thereby enabling the battery cell to have better cycling performance.

[0019] In some embodiments, the layered material layer comprises a layered material comprising As, Sb, Bi, black phosphorus, graphite, hard carbon, MXene, MoS2, MoO2, TiO2, RuO2, Li4Ti5O 12One or more of these. These layered materials have a good layered structure and good electronic conductivity, which is conducive to the insertion of metals such as lithium and sodium. In addition, the volume change before and after the insertion of lithium, sodium and other metals is relatively small, which helps to better reduce the volume expansion of the negative electrode caused by the metal deposition process, thereby making the battery cell have better cycle performance. At the same time, the intercalation reaction of these layered materials also has high reversibility, which can also make the battery cell have a higher first coulombic efficiency. In addition, these layered materials can also make the battery cell have a lower production cost.

[0020] Optionally, the layered material comprises Bi.

[0021] In some embodiments, the nucleation overpotential of the active reaction layer is less than or equal to 80 mV. A low nucleation overpotential of the active reaction layer is beneficial for reducing the formation of loose and porous moss structures or dendrite structures, thereby facilitating better cycle performance of the battery cell.

[0022] In some embodiments, the active reaction layer includes an alkali metal affinity material, wherein the alkali metal affinity material includes one or more of a graphitized carbon material, a non-metallic material, and a metallic material. The graphitized carbon material includes one or more of graphene oxide and graphene oxide. The non-metallic material includes one or more of boron and phosphorus. The metallic material includes one or more of single elements of Sn, Zn, Mg, Al, Ag, Au, Ga, In, Ge, Pb, As, Sb, and Bi, and alloys thereof.

[0023] The deposited metals, such as lithium and sodium, can react with the alkali metal affinity material in the active reaction layer, thereby reducing the nucleation overpotential of the negative electrode current collector and increasing its active area. Furthermore, the diffusion of metal atoms, such as lithium and sodium, in the alkali metal affinity material is faster than in the metal itself, thereby reducing localized metal deposition. Furthermore, the alloys formed by metals such as lithium and sodium and the alkali metal affinity material have a higher electrode potential than the metal itself, thereby increasing the negative electrode potential. This also helps improve the quality of the solid electrolyte interface film on the negative electrode surface, further contributing to the improved cycling performance of the battery cells.

[0024] Optionally, the alkali metal affinity material includes one or more of single substances of Sn, Zn, Mg, Al and alloys thereof.

[0025] In some embodiments, the negative electrode substrate is a two-dimensional structure or a three-dimensional porous structure.

[0026] In some embodiments, the negative electrode substrate includes a metal material, and the metal material includes one or more of copper, nickel, titanium, magnesium, aluminum, copper alloy, nickel alloy, titanium alloy, magnesium alloy, and aluminum alloy.

[0027] In a second aspect, the present application provides a battery cell comprising the negative electrode current collector according to the first aspect of the present application.

[0028] In some embodiments, the battery cell includes at least one of a lithium metal battery cell, a sodium metal battery cell, a negative electrode-free lithium metal battery cell, and a negative electrode-free sodium metal battery cell.

[0029] In a third aspect, the present application provides a battery comprising the battery cell according to the second aspect of the present application.

[0030] In a fourth aspect, the present application provides an electrical device comprising the battery according to the third aspect of the present application, wherein the battery is used to provide electrical energy.

[0031] The electric device of the present application includes the battery provided by the present application, and thus has at least the same advantages as the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on the drawings without inventive effort.

[0033] FIG1 is a schematic diagram of a battery cell provided by some embodiments of the present application.

[0034] FIG2 shows a schematic diagram of a battery module provided in some embodiments of the present application.

[0035] FIG3 shows a schematic diagram of a battery pack provided in some embodiments of the present application.

[0036] FIG4 is an exploded schematic diagram of the battery pack shown in FIG3 .

[0037] FIG5 shows an exploded schematic diagram of a battery cell provided in some embodiments of the present application.

[0038] FIG6 shows a schematic structural diagram of a negative electrode current collector provided in some embodiments of the present application.

[0039] FIG7 is a schematic structural diagram of an electrode assembly of a battery cell provided in some embodiments of the present application.

[0040] FIG8 shows a schematic diagram of an electrical device provided in some embodiments of the present application.

[0041] In the accompanying drawings, the drawings are not necessarily drawn to scale.

[0042] The accompanying drawings are marked as follows: 1. Battery pack; 2. Upper case; 3. Lower case; 4. Battery module; 5. Battery cell; 51. Shell; 52. Electrode assembly; 53. Cover plate; 100. Positive electrode sheet; 200. Negative electrode current collector; 300. Isolation membrane; 201. Negative electrode substrate; 202. Active reaction layer; 203. Layered material layer. DETAILED DESCRIPTION

[0043] Below, with appropriate reference to the accompanying drawings, the embodiments of the negative electrode current collector, battery cell, battery, and electrical device of the present application are described in detail. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0044] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0046] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0047] Unless otherwise specified, all steps of the present 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 may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0048] In this application, the terms "plurality" and "multiple" refer to two or more.

[0049] In the description of the embodiments of the present application, unless otherwise specified, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0050] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0051] Unless otherwise stated, the numerical values ​​of the various parameters mentioned in this application can be measured using various test methods commonly used in the art, for example, they can be measured according to the test methods given in the examples of this application. Unless otherwise stated, the test temperature of each parameter is 25°C.

[0052] The battery mentioned in the embodiments of the present application may be a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery cell, a battery module, or a battery pack.

[0053] A battery cell is the smallest unit of a battery, independently capable of charging and discharging. A battery cell can be cylindrical, rectangular, or have other shapes, though this is not a limitation in the present invention. Figure 1 shows a battery cell 5 with a rectangular structure as an example.

[0054] When there are multiple battery cells, the multiple battery cells are connected in series, in parallel, or in mixed series via a busbar. In some embodiments, the battery may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. In some embodiments, the battery may be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed in the housing. In some embodiments, the housing may serve as part of the vehicle's chassis structure. For example, a portion of the housing may form at least a portion of the vehicle's floor, or a portion of the housing may form at least a portion of the vehicle's crossbeam or longitudinal beam.

[0055] In some embodiments, battery cells can be assembled into a battery module. The number of battery cells contained 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 in sequence along the length of the battery module 4. Of course, they can also be arranged in any other manner. The multiple battery cells 5 can further be fixed by fasteners.

[0056] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0057] In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0058] Figures 3 and 4 are schematic diagrams of an exemplary battery pack 1. 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 comprises an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3 and forms an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 may be arranged in any manner within the housing.

[0059] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0060] The battery cells provided in the embodiments of the present application are metal battery cells and negative electrode-free battery cells, and may include, for example, at least one of lithium metal battery cells, sodium metal battery cells, negative electrode-free lithium metal battery cells, and negative electrode-free sodium metal battery cells.

[0061] A negative electrode-free battery cell generally refers to a battery cell constructed without the active negative electrode layer being applied during the manufacturing process. For example, a negative electrode active material layer is not applied to the negative electrode through coating or deposition, or a carbonaceous active material layer is used to form the negative electrode active material layer. During initial charging, ions on the negative electrode side gain electrons and deposit on the surface of the negative electrode current collector to form metal. During discharge, the metal can be converted back to ions and returned to the positive electrode, enabling cyclic charge and discharge. Compared to other battery cells, negative electrode-free battery cells can achieve higher energy density due to the lack of a negative electrode active material layer. In some embodiments, to improve battery cell performance, the negative electrode side of the negative electrode-free battery cell may also be provided with some conventional negative electrode active materials, such as carbon materials. Although these materials have a certain capacity, their content is relatively low and they are not used as the primary negative electrode active material in the battery cell. Therefore, the battery cell constructed in this manner can still be considered a negative electrode-free battery cell. The CB (Cell Balance) value of a battery cell without a negative electrode is typically very small. For example, in some embodiments, the CB value of a battery cell without a negative electrode can be less than or equal to 0.1. The CB value is the unit area capacity of the negative electrode in the battery cell divided by the unit area capacity of the positive electrode. Because a battery cell without a negative electrode contains no or only a small amount of negative electrode active material, the unit area capacity of the negative electrode is relatively small, and thus the CB value is very small, for example, typically less than or equal to 0.1.

[0062] The battery cell includes an electrode assembly, which may be a wound structure or a laminated structure, and the present invention is not limited thereto.

[0063] The battery cell may also include an outer packaging that can be used to encapsulate the electrode assembly. The outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, steel shell, etc. The outer packaging can also be a soft shell, such as a bag-type soft shell. The soft shell can be made of plastic, such as one or more of polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0064] In some embodiments, as shown in Figure 5, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, which together form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening, thereby sealing the receiving cavity. The electrode assembly 52 is enclosed in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and can be adjusted according to needs.

[0065] Affinity treatment of the negative electrode current collector surface can reduce the formation of loose, porous moss or dendrite structures. However, common affinity materials experience significant volume expansion after reacting with metals such as lithium. During cycling, the negative electrode of a metal battery cell repeatedly expands and contracts, causing the affinity material layer to rupture and pulverize, thus affecting the cycling performance of the metal battery cell.

[0066] In view of this, an embodiment of the present application provides a negative electrode current collector, which effectively improves the cycle performance of the battery cell by adding a layered material layer between the active reaction layer and the negative electrode substrate.

[0067] FIG6 shows a schematic structural diagram of a negative electrode current collector provided in some embodiments of the present application.

[0068] As shown in FIG6 , the negative electrode current collector 200 includes a negative electrode substrate 201 and a modified layer located on at least one side of the negative electrode substrate 201 . The modified layer includes an active reaction layer 202 and a layered material layer 203 located between the active reaction layer 202 and the negative electrode substrate 201 .

[0069] The active reaction layer is far away from the negative electrode matrix and close to the isolation membrane of the battery cell. During the deposition process of metals such as lithium and sodium, the active reaction layer first contacts and reacts with metals such as lithium and sodium, thereby increasing the active sites on the surface of the negative electrode current collector, reducing the nucleation overpotential of the negative electrode current collector, and reducing the formation of loose and porous moss structures or dendrite structures.

[0070] The layered material layer includes layered materials, and metals such as lithium and sodium can be embedded between the layers of the layered materials. Therefore, the thickness of the layered material layer changes little before and after the battery cell is charged, that is, before and after the metals such as lithium and sodium are embedded.

[0071] By locating the layered material layer between the active reaction layer and the negative electrode matrix, the layered material layer can act as a buffer layer, reducing the volume expansion of the negative electrode caused by the deposition of metals such as lithium and sodium, thereby maintaining good electronic contact between the modified layer and the negative electrode matrix during the battery cell cycle, thereby improving the cycle performance of the battery cell.

[0072] In some embodiments, the negative electrode substrate 201 may be a two-dimensional structure or a three-dimensional porous structure.

[0073] The negative electrode substrate includes a metal material, and the metal material may include one or more of copper, nickel, titanium, magnesium, aluminum, copper alloy, nickel alloy, titanium alloy, magnesium alloy, and aluminum alloy.

[0074] For example, in some embodiments, the negative electrode substrate 201 may be a copper foil.

[0075] In some embodiments, the active reaction layer 202 may be formed by electro-deposition, evaporation, magnetron sputtering, ion beam sputtering, or atomic layer deposition, and may be formed by magnetron sputtering.

[0076] In some embodiments, the layered material layer 203 may be formed by electro-deposition, evaporation, magnetron sputtering, ion beam sputtering, or atomic layer deposition, and may be formed by magnetron sputtering.

[0077] In some embodiments, the layered material layer 203 includes a layered material having an electronic conductivity greater than or equal to 5 S / m. The layered material has good electronic conductivity, which facilitates the intercalation of metals such as lithium and sodium into the interlayers of the layered material during battery cell charging. This facilitates the layered material layer to better serve as a buffer layer, thereby better reducing the negative electrode volume expansion caused by the deposition of metals such as lithium and sodium, thereby enabling the battery cell to have better cycling performance.

[0078] In some embodiments, the layered material may include As, Sb, Bi, black phosphorus, graphite, hard carbon, MXene, MoS2, MoO2, TiO2, RuO2, Li4Ti5O 12 One or more of .

[0079] These layered materials have a good layered structure and good electronic conductivity, which is conducive to the insertion of metals such as lithium and sodium. The volume change before and after the insertion of lithium, sodium and other metals is also small, which helps to better reduce the volume expansion of the negative electrode caused by the metal deposition process, thereby making the battery cell have better cycle performance. At the same time, the intercalation reaction of these layered materials is also highly reversible, which can also make the battery cell have a higher first coulombic efficiency. In addition, these layered materials can also make the battery cell have a lower production cost.

[0080] Optionally, the layered material may include one or more of As, Sb, Bi, black phosphorus, graphite, and hard carbon.

[0081] More optionally, the layered material may include Bi. Bi is inexpensive, non-toxic, and has better interlayer bonding with the active reaction layer and the negative electrode matrix, thereby facilitating better cycle performance of the battery cell.

[0082] In some embodiments, the nucleation overpotential of the active reaction layer 202 may be less than or equal to 80 mV, and may optionally be less than or equal to 50 mV.

[0083] The nucleation overpotential of the active reaction layer has a well-known meaning in the art. For example, the nucleation overpotential of the active reaction layer can be obtained by the following method: under the same process conditions, the active reaction layer is directly disposed on the negative electrode substrate to obtain a negative electrode current collector; in an argon-protected glove box, a metal lithium sheet is used as a counter electrode and assembled with the prepared negative electrode current collector into a button cell; after the assembled button cell is left to stand for 12 hours at 25°C, the cell is charged at 1 mA / cm 2 The current density is constant current discharge to 1 mAh / cm 2 At the beginning of the lithium metal deposition process, there will be a significant voltage drop, followed by a flat voltage platform. The difference (absolute value) between the voltage at the lowest point of the discharge curve and the flat part of the voltage platform is used as the nucleation overpotential of the active reaction layer. The electrolyte salt of the electrolyte is LiFSI with a concentration of 1 mol / L, and the solvent of the electrolyte is ethylene glycol dimethyl ether (DME). The isolation membrane is a PE film with a thickness of 12μm.

[0084] The nucleation overpotential of the active reaction layer is small, which is beneficial to reducing the formation of loose and porous moss structures or dendrite structures, and thus is beneficial to better cycle performance of the battery cell.

[0085] In some embodiments, the active reaction layer 202 includes an alkali metal affinity material, which may be a lithium affinity material or a sodium affinity material.

[0086] Unlike layered materials, the reactions of lithiophilic materials with deposited lithium metal, and of sodiumophilic materials with deposited sodium metal, are both non-intercalation reactions, such as alloying reactions. Consequently, the active reaction layer experiences significant volume expansion before and after charging the battery cell. During cycling of the metal battery cell, the negative electrode repeatedly expands and contracts, causing the active reaction layer to rupture and pulverize. By providing a layered material layer between the active reaction layer and the negative electrode substrate, the layered material layer can function as a buffer layer, thereby reducing the negative electrode volume expansion caused by the deposition of metals such as lithium and sodium, and minimizing the rupture and pulverization of the active reaction layer. This allows for good electronic contact between the modified layer and the negative electrode substrate during battery cell cycling, thereby improving the battery cell's cycling performance.

[0087] The alkali metal affinity material may include one or more of a graphitized carbon material, a non-metallic material, and a metallic material.

[0088] Optionally, the graphitized carbon material may include one or more of graphene oxide and graphyne oxide.

[0089] Optionally, the non-metallic material may include one or more of B and P.

[0090] Optionally, the metal material may include one or more single-element materials of Sn, Zn, Mg, Al, Ag, Au, Ga, In, Ge, Pb, As, Sb, Bi, and alloy materials thereof.

[0091] Alternatively, the alkali metal affinity material may include one or more of single substance materials of Sn, Zn, Mg, Al, Ag, Au, and alloy materials thereof.

[0092] More optionally, the alkali metal affinity material may include one or more of single-element materials of Sn, Zn, Mg, Al, and alloy materials thereof. These materials are inexpensive and non-toxic, and thus can be better applied to battery cells.

[0093] The deposited metals, such as lithium and sodium, can react with the alkali metal affinity material in the active reaction layer, thereby reducing the nucleation overpotential of the negative electrode current collector and increasing its active area. Furthermore, the diffusion of metal atoms, such as lithium and sodium, in the alkali metal affinity material is faster than in the metal itself, thereby reducing localized metal deposition. Furthermore, the alloys formed by metals such as lithium and sodium and the alkali metal affinity material have a higher electrode potential than the metal itself, thereby increasing the negative electrode potential. This also helps improve the quality of the solid electrolyte interface film on the negative electrode surface, further contributing to the improved cycling performance of the battery cells.

[0094] In some embodiments, the thickness of the active reaction layer 202 can be 1 times to 25 times the thickness of the layered material layer 203. For example, it can be 1 times, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, 14 times, 15 times, 16 times, 17 times, 18 times, 19 times, 20 times, 25 times, or a range consisting of any of the above values.

[0095] The ratio of the thickness of the active reaction layer to the layered material layer is between 1 and 25, which can not only increase the active sites on the surface of the negative electrode current collector and reduce the nucleation overpotential of the negative electrode current collector, but also reduce the volume expansion of the negative electrode caused by the metal deposition process, improve the problem of infinite volume expansion of the negative electrode, and thus further improve the cycle performance of the battery cell.

[0096] Optionally, the thickness of the active reaction layer 202 may be 2 to 25 times, 2 to 20 times, 5 to 20 times, 8 to 20 times, 8 to 15 times, or 8 to 12 times the thickness of the layered material layer 203. This can further improve the cycle performance of the battery cell.

[0097] In some embodiments, the thickness of the active reaction layer 202 can be 50 nm-1000 nm, for example, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 900 nm, 1000 nm, or a range consisting of any of the above values.

[0098] The thickness of the active reaction layer being within the above range is beneficial to reducing the nucleation overpotential of the negative electrode current collector and reducing the formation of loose and porous moss structures or dendrite structures, thereby improving the cycle performance of the battery cell.

[0099] When the thickness of the active reaction layer is within the above range, the battery cell can also have a higher energy density.

[0100] Optionally, the thickness of the active reaction layer 202 may be 100nm-1000nm, 150nm-1000nm, 200nm-1000nm, 300nm-1000nm, 100nm-750nm, 150nm-750nm, 200nm-750nm, or 300nm-750nm, thereby further improving the cycle performance of the battery cell.

[0101] In some embodiments, the thickness of the layered material layer 203 can be 5nm-500nm, for example, it can be 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 65nm, 75nm, 85nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, or a range consisting of any of the above values.

[0102] The thickness of the layered material layer is within the above range, which can reduce the risk of rupture and pulverization of the active reaction layer, thereby enabling the battery cell to have good cycle performance.

[0103] In addition, the layered material layer can react with the deposited metal, so as the thickness of the layered material layer increases, the first coulombic efficiency of the battery decreases. Therefore, when the thickness of the layered material layer is within the above range, the battery cell can also have a higher first coulombic efficiency.

[0104] Optionally, the thickness of the layered material layer 203 may be 10 nm-500 nm, 20 nm-500 nm, 25 nm-500 nm, 30 nm-500 nm, 10 nm-250 nm, 20 nm-250 nm, 25 nm-250 nm, 30 nm-250 nm, 10 nm-100 nm, 20 nm-100 nm, 25 nm-100 nm, 30 nm-100 nm, 10 nm-75 nm, 20 nm-75 nm, 25 nm-75 nm, 30 nm-75 nm. This can provide the battery cell with good cycle performance and high first coulombic efficiency.

[0105] In some embodiments, the total thickness of the modified layer can be 55 nm-1500 nm, for example, 55 nm, 110 nm, 200 nm, 250 nm, 275 nm, 300 nm, 325 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 825 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, 1500 nm, or a range consisting of any of the above values.

[0106] Optionally, the total thickness of the modified layer may be 110 nm-1500 nm, 250 nm-1500 nm, 300 nm-1500 nm, 250 nm-1100 nm, 300 nm-1100 nm, 250 nm-1000 nm, 300 nm-1000 nm, 250 nm-825 nm, 300 nm-825 nm.

[0107] When the total thickness of the modified layer is within the above range, the battery cell can have good cycle performance and higher energy density.

[0108] In some embodiments, the surface density of the active reaction layer 202 may be greater than or equal to 0.5 g / m 2 This can make the battery cell have good cycle performance.

[0109] In some embodiments, the surface density of the layered material layer 203 may be greater than or equal to 0.5 g / m 2 This can make the battery cell have good cycle performance.

[0110] The present invention also provides a battery cell, comprising the negative electrode current collector provided in the present invention. The battery cell may be a metal battery cell or a negative electrode-free battery cell, for example, at least one of a lithium metal battery cell, a sodium metal battery cell, a negative electrode-free lithium metal battery cell, and a negative electrode-free sodium metal battery cell.

[0111] A battery cell includes an electrode assembly and an electrolyte. A battery assembly includes a positive electrode sheet, a negative electrode sheet, and a separator.

[0112] In some embodiments, the negative electrode current collector provided in the embodiments of the present application can be used as a negative electrode plate, thereby obtaining a negative electrode-free battery cell, such as a negative electrode-free lithium metal battery cell or a negative electrode-free sodium metal battery cell.

[0113] Figure 7 shows a schematic diagram of the structure of an electrode assembly of a negative electrode-free battery cell provided in some embodiments of the present application. As shown in Figure 7, the electrode assembly includes a positive electrode sheet 100, a negative electrode current collector 200, and a separator 300 located between the positive electrode sheet 100 and the negative electrode current collector 200.

[0114] In some embodiments, the surface of the negative electrode current collector may further include a lithium metal layer or a sodium metal layer, thereby obtaining a lithium metal battery cell or a sodium metal battery cell.

[0115] [Positive electrode]

[0116] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector and comprising a positive electrode active material. For example, the positive electrode current collector has two opposing surfaces in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposing surfaces of the positive electrode current collector.

[0117] In some embodiments, the positive electrode active material includes a material capable of extracting and inserting lithium.

[0118] As an example, the positive electrode active material may include, but is 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 oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium titanium oxide, 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, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon, and their respective modified compounds.

[0119] In some embodiments, in order to further improve the energy density of the battery cell, the positive electrode active material may include a general formula of Li a Ni b Co c M d O e Df One or more lithium transition metal oxides and modified compounds thereof. 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.

[0120] In some embodiments, the positive electrode active material may include both a lithium transition metal oxide and a lithium-containing phosphate, thereby facilitating the production of a battery cell having both high capacity and high reliability.

[0121] As an example, the positive electrode active material may include but is not limited to LiCoO2, LiNiO2, LiMnO2, 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.

[0122] In some embodiments, the positive electrode active material includes a material capable of extracting and inserting sodium. 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.

[0123] In some embodiments, as examples, the positive electrode active material may include but is not limited to NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, Na 0.67 MO2 (M includes at least two of Fe, Co, Cr, Mn, Ni, V, Ti, Mo), NaMO2 (M includes at least two of Fe, Co, Ni, V, Ti, 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.

[0124] The modified compounds of the above-mentioned positive electrode active materials may be used to perform doping modification and / or surface coating modification on the positive electrode active materials.

[0125] The charge and discharge process of a battery cell is accompanied by the intercalation and deintercalation of Li / Na, and the molar content of Li / Na varies when the battery cell is discharged to different states. The molar content of Li / Na in the examples of this application regarding the positive electrode active materials is based on the initial state of the material. The molar content of Li / Na may change after the positive electrode active material is applied to the battery cell and undergoes charge and discharge cycles.

[0126] In the examples of the present application regarding the positive electrode active materials, the molar content of O is only a theoretical value. Lattice oxygen release will cause the molar content of O to change, and the actual molar content of O will fluctuate.

[0127] In some embodiments, the positive electrode film layer may further 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.

[0128] In some embodiments, the positive electrode film layer may further optionally include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene oxide, fluorinated acrylic resin, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and one or more of carboxymethyl chitosan (CMCS).

[0129] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0130] The positive electrode film layer is typically formed by coating a positive electrode slurry onto a positive electrode current collector, drying, and cold pressing. The positive electrode slurry is typically formed by dispersing the positive electrode active material, optional positive electrode conductive agent, optional positive electrode binder, and any other components in a solvent and stirring them uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP).

[0131] [Isolation film]

[0132] The isolation film is located between the positive electrode and the negative electrode, and its main function is to prevent internal short circuit.

[0133] This application does not specifically limit the type of separator; any known porous separator with good chemical and mechanical stability may be used. In some embodiments, the separator may be made of, but not limited to, one or more of fiberglass, non-woven 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.

[0134] [Electrolytes]

[0135] In some embodiments, the electrolyte is an electrolyte solution including an electrolyte salt and an organic solvent.

[0136] In some embodiments, the electrolyte includes anions, which may include bis(fluorosulfonyl)imide anions (FSI - ), bis(trifluoromethanesulfonyl)imide anion (TFSI - ), dioxalatoborate anion (BOB - ), difluorooxalatoborate anion (DFOB - ), difluorobis(oxaloyl)phosphate anion (DFOP - ), tetrafluorooxalophosphate anion (TFOP - ), difluorophosphate anion (PO2F2 - ), hexafluorophosphate anion (PF6 -), tetrafluoroborate anion (BF4 - ), hexafluoroarsenate anion (AsF6 - ), trifluoromethanesulfonate anion (CF3SO3 - )

[0137] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0138] In some embodiments, the concentration of the electrolyte salt may be greater than 0.3 mol / L, and may be greater than 0.7 mol / L. The concentration of the electrolyte salt may further be less than 4 mol / L, and may be less than 2.5 mol / L or less than 1.7 mol / L. When the concentration of the electrolyte salt is within the above range, the electrolyte solution can have suitable ionic conductivity.

[0139] Organic solvent can include but not limited to one or more in esters, ethers, sulfones, nitrile etc.Ester can include but not limited to one or more in carbonate, phosphate, carboxylate, sulfate, sulfonate etc.Carbonate can comprise cyclic carbonate and / or chain carbonate, alternatively, carbonate can comprise cyclic carbonate and chain carbonate simultaneously.Chain carbonate can comprise low-viscosity polar chain carbonate, aliphatic branched-chain carbonate etc.

[0140] As an example, the organic solvent may include, but is not limited to, ethylene carbonate (EC), propylene carbonate (PC), butylene 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), tetraethylene glycol dimethyl ether (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 trifluoromethyl decafluoropentyl methyl ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether, 5-trifluoromethyl dodecafluorohexyl methyl ether, 5-trifluoromethyl dodecafluorohexyl ethyl ether, 5-trifluoromethyl dodecafluorohexyl propyl ether, 6-trifluoromethyl tetradecafluoroheptyl methyl ether, 6-trifluoromethyl tetradecafluoroheptyl ethyl ether, 6-trifluoromethyl tetradecafluoroheptyl propyl ether, 7-trifluoromethyl hexafluorooctyl methyl ether, 7-trifluoromethyl hexafluorooctyl ethyl ether, and 7-trifluoromethyl hexafluorooctyl propyl ether.

[0141] 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, or additives that can improve certain properties of the battery cell, such as additives that improve overcharge performance, additives that improve high-temperature performance, and additives that improve low-temperature power performance.

[0142] The preparation method of battery cells is well known. As an example, the positive electrode sheet, separator, and negative electrode sheet can be formed into an electrode assembly through a winding process and / or a lamination process. The electrode assembly is placed in an outer package, dried, and then injected with the above-mentioned electrolyte. After vacuum packaging, standing, and chemical formation, a battery cell is obtained. Multiple battery cells can also be further connected in series, parallel, or mixed to form a battery module. Multiple battery modules can also be connected in series, parallel, or mixed to form a battery pack. In some embodiments, multiple battery cells can also directly form a battery pack.

[0143] The present application also provides an electrical device, which includes a battery provided in the present application. The battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device can be, but is not limited to, a mobile device (such as a mobile phone, a tablet computer, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0144] The electric device can select the type of battery according to its usage requirements, such as a battery cell, a battery module or a battery pack.

[0145] Figure 8 is a schematic diagram of an exemplary electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of this device, a battery pack or battery module may be used.

[0146] As another example, an electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such an electric device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0147] Example

[0148] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further processing, and all instruments used in the examples are commercially available.

[0149] Example 1

[0150] Commercially available double-sided polished copper foil with a thickness of 8 μm was first wiped with 1 mol / L acetic acid solution and allowed to stand for 20 min. The surface of the copper foil was then wiped with anhydrous ethanol. The copper foil was then ultrasonically cleaned in deionized water for 5 min and then vacuum dried at 80°C for 30 min.

[0151] After installing the Bi target, place the copper foil sample in the magnetron sputtering instrument and evacuate to vacuum (<1Pa). After injecting argon into the chamber to 1 bar, evacuate again (<1Pa), set the magnetron sputtering current to 30mA, and the magnetron sputtering time to 75s; replace the target with a Sn target, evacuate to vacuum (<1Pa), inject argon into the chamber to 1 bar, evacuate again (<1Pa), set the magnetron sputtering current to 30mA, and the magnetron sputtering time to 600s to obtain a copper foil with a modified layer, i.e., the negative electrode current collector. The modified layer includes an active reaction layer Sn metal layer and a layered material layer Bi metal layer. The layered material layer is located between the copper foil and the active reaction layer. The thickness of the active reaction layer is 300nm and the surface density is about 21.93g / m 2 The thickness of the layered material is 30nm and the surface density is about 24.9g / m 2 .

[0152] Examples 2 to 6

[0153] The preparation method for the modified copper foil was similar to that of Example 1, except that the thickness of the active reaction layer and the layered material layer were different. Specific parameters are shown in Table 1. The magnetron sputtering current was 30 mA for both layers. The thickness of the active reaction layer and the layered material layer could be adjusted by adjusting the magnetron sputtering time. Changing the thickness of the active reaction layer and the layered material layer also changes their areal density.

[0154] Comparative Example 1

[0155] Commercially available double-sided polished copper foil with a thickness of 8 μm was first wiped with 1 mol / L acetic acid solution and allowed to stand for 20 min. The surface of the copper foil was then wiped with anhydrous ethanol. The copper foil was then ultrasonically cleaned in deionized water for 5 min and then vacuum dried at 80°C for 30 min.

[0156] Comparative Example 2

[0157] Commercially available double-sided polished copper foil with a thickness of 8 μm was first wiped with 1 mol / L acetic acid solution and allowed to stand for 20 min. The surface of the copper foil was then wiped with anhydrous ethanol. The copper foil was then ultrasonically cleaned in deionized water for 5 min and then vacuum dried at 80°C for 30 min.

[0158] After installing the Sn target, the copper foil sample was placed in a magnetron sputtering instrument and evacuated to a vacuum (<1 Pa). Argon was then injected into the chamber to 1 bar, and the pressure was evacuated again (<1 Pa). The magnetron sputtering current was set to 30 mA, and the magnetron sputtering time was set to 100 seconds to obtain a copper foil with a modified layer. The modified layer is the active reaction layer Sn metal layer.

[0159] Performance Testing

[0160] Lithium iron phosphate, conductive agent 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 on the positive electrode current collector aluminum foil and dried to obtain a positive electrode sheet.

[0161] In an argon-protected glove box, a button-type battery was assembled with the positive electrode, the modified copper foil prepared above (pure copper foil in Comparative Example 1), and a separator. The electrolyte salt was LiFSI at a concentration of 1 mol / L, and the solvent was ethylene glycol dimethyl ether (DME). The separator was a 12 μm thick PE film.

[0162] (1) First Coulomb efficiency test

[0163] After the assembled button cell was allowed to rest for 12 hours at 25°C, it was charged at a constant current of 0.1C to 3.65V. Then, it was charged at a constant voltage of 3.65V to 0.05C to obtain the initial charge capacity. After the button cell was allowed to rest for 10 minutes, it was discharged at a constant current of 0.2C to 2V to obtain the initial discharge capacity. The initial coulombic efficiency of the button cell = initial discharge capacity / initial charge capacity × 100%. The number of button cell samples can be more than 6, and the test results are averaged.

[0164] (2) Negative electrode thickness change test

[0165] At 25°C, the assembled button battery was left to stand for 12 hours, then charged to 3.65V at a constant current of 0.1C, and then charged to 0.05C at a constant voltage of 3.65V. At this time, the button battery was fully charged.

[0166] Disassemble a fully charged button cell and measure the total thickness of the active reaction layer and the layered material layer after full charge, recording this as h1. Before charging, measure the total thickness of the active reaction layer and the layered material layer as h0. Denote the change in negative electrode thickness as h1 / h0. For Comparative Example 2, where no layered material layer is provided, h1 represents the thickness of the active reaction layer after full charge, while h0 represents the thickness of the active reaction layer before charging. Testing can be performed on six or more button cell samples, and the test results are averaged.

[0167] (3) Cyclic performance test

[0168] After the assembled button cell was allowed to rest for 12 hours at 25°C, it was charged at a constant current of 0.2C to 3.65V. Then, it was charged at a constant voltage of 3.65V to 0.05C. After the button cell was allowed to rest for 10 minutes, it was discharged at a constant current of 0.5C to 2V. The button cell was cycled according to the above method until the discharge capacity decayed to 50% of the initial discharge capacity. The number of cycles was recorded. The number of button cell samples can be more than 6 during testing, and the test results are averaged.

[0169] Table 1

[0170] It can be seen from the test results in Table 1 that by providing a layered material layer between the active reaction layer and the copper foil, the expansion problem of the negative electrode can be alleviated, the thickness variation of the active reaction layer can be reduced, and the cycle performance of the battery can be improved.

[0171] It can also be seen from the test results in Table 1 that when the thickness of the active reaction layer increases, by increasing the thickness of the layered material layer and making the ratio of the thickness of the active reaction layer to the layered material layer within an appropriate range, the expansion problem of the negative electrode can be alleviated and the battery can also have good cycle performance.

[0172] Table 2

[0173] It can also be seen from the test results in Table 2 that when the thickness ratio of the active reaction layer to the layered material layer is constant, the thickness of the active reaction layer increases and the first coulombic efficiency of the battery decreases.

[0174] Examples 2-1 to 2-4

[0175] The preparation method of the copper foil with the modified layer is similar to that of Example 2, except that the thickness of the layered material layer is different. The specific parameters are shown in Table 3. The magnetron sputtering current is 30 mA, and the thickness of the layered material layer can be adjusted by adjusting the magnetron sputtering time.

[0176] Table 3

[0177] The test results in Table 3 show that, while the thickness of the active reaction layer remains constant, increasing the thickness of the layered material layer can better alleviate the negative electrode expansion problem. Since Bi can also react with the deposited lithium metal, the initial coulombic efficiency of the battery will decrease to varying degrees as the thickness of the layered material layer increases. However, the coulombic efficiency will rapidly increase in the later stages of the battery cycle. Therefore, increasing the thickness of the layered material layer can still improve the battery's cycling performance.

[0178] Example 3-1

[0179] The preparation method of the copper foil with the modified layer is similar to that of Example 4, except that the thickness of the layered material layer is different. Specific parameters are shown in Table 4. The magnetron sputtering current is 30 mA, and the thickness of the layered material layer can be adjusted by adjusting the magnetron sputtering time.

[0180] Table 4

[0181] The test results in Table 4 show that, while the thickness of the active reaction layer remains constant, increasing the thickness of the layered material layer can better alleviate the negative electrode expansion problem. Since Bi can also react with the deposited lithium metal, the initial coulombic efficiency of the battery will decrease to a certain extent when the thickness of the layered material layer increases; however, the coulombic efficiency will rapidly increase in the later stages of the battery cycle. Therefore, increasing the thickness of the layered material layer can still improve the battery's cycling performance.

[0182] Examples 4-1 to 4-5

[0183] The preparation method for the modified copper foil was similar to that of Example 1, except that the type of active reaction layer or layered material layer was different. Specific parameters are detailed in Table 5. The type of active reaction layer or layered material layer can be adjusted by changing the magnetron sputtering target. The magnetron sputtering current was always 30 mA, and the thickness of the active reaction layer or layered material layer could be adjusted by adjusting the magnetron sputtering time.

[0184] The active reaction layer of Example 1 is a Sn metal layer, and the test result of the overpotential for lithium nucleation is 9.1 mV.

[0185] The active reaction layer of Example 4-1 is a Zn metal layer, and the test result of its nucleation overpotential for lithium is 26.1 mV.

[0186] The active reaction layer of Example 4-2 is an Al metal layer, and the test result of its nucleation overpotential for lithium is 131.5 mV.

[0187] The active reaction layer of Example 4-3 is a Mg metal layer, and the test result of its nucleation overpotential for lithium is 158.4 mV.

[0188] The nucleation overpotential of the active reaction layer was obtained by the following method: according to the same process conditions as in each embodiment, the active reaction layer was directly sputtered on a copper foil to obtain a negative electrode current collector; in an argon-protected glove box, a metal lithium sheet was used as a counter electrode and assembled with the prepared negative electrode current collector into a button cell; after the assembled button cell was allowed to stand for 12 hours at 25°C, a voltage of 1 mA / cm 2 The current density is constant current discharge to 1 mAh / cm 2At the beginning of the lithium metal deposition process, there will be a significant voltage drop, followed by a flat voltage platform. The difference (absolute value) between the voltage at the lowest point of the discharge curve and the flat part of the voltage platform is used as the nucleation overpotential of the active reaction layer. The electrolyte salt of the electrolyte is LiFSI with a concentration of 1 mol / L, and the solvent of the electrolyte is ethylene glycol dimethyl ether (DME). The isolation membrane is a PE film with a thickness of 12μm.

[0189] The test results of Example 4-2 and Example 4-3 are too large. This is because Al metal and Mg metal are relatively active. During the process of transferring to the glove box after sputtering, the metal on the surface of the Al metal layer and the Mg metal layer may be oxidized by air to form metal oxides, thereby causing the test results of the nucleation overpotential of the Al metal layer and the Mg metal layer for lithium to deviate from their actual nucleation overpotential.

[0190] Table 5

[0191] From the test results in Table 5, it can be seen that by further selecting a suitable material for the active reaction layer, the expansion problem of the negative electrode can be better alleviated, and the battery can also have good cycle performance and high first coulombic efficiency.

[0192] It can be seen from the test results in Table 5 that by further selecting a suitable material for the layered material layer, the expansion problem of the negative electrode can be better alleviated, and the battery can also have good cycle performance and high first coulombic efficiency.

[0193] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A negative electrode current collector comprising a negative electrode substrate and a modified layer located on at least one side of the negative electrode substrate, wherein the modified layer comprises an active reaction layer and a layered material layer located between the active reaction layer and the negative electrode substrate.

2. The negative electrode current collector according to claim 1, wherein The thickness of the active reaction layer is 1 to 25 times the thickness of the layered material layer.

3. The negative electrode current collector according to claim 2, wherein: The thickness of the active reaction layer is 2 to 20 times the thickness of the layered material layer.

4. The negative electrode current collector according to any one of claims 1 to 3, wherein: The thickness of the active reaction layer is 50 nm to 1000 nm; and / or the thickness of the layered material layer is 5 nm to 500 nm.

5. The negative electrode current collector according to claim 4, wherein The thickness of the active reaction layer is 300 nm to 1000 nm; and / or the thickness of the layered material layer is 20 nm to 500 nm.

6. The negative electrode current collector according to claim 5, wherein: The thickness of the active reaction layer is 300 nm to 750 nm; and / or the thickness of the layered material layer is 25 nm to 250 nm.

7. The negative electrode current collector according to any one of claims 1 to 6, wherein: The surface density of the active reaction layer is greater than or equal to 0.5 g / m 2 ; and / or, the surface density of the layered material layer is greater than or equal to 0.5g / m 2 .

8. The negative electrode current collector according to any one of claims 1 to 7, wherein: The layered material layer includes a layered material, and the electronic conductivity of the layered material is greater than or equal to 5 S / m.

9. The negative electrode current collector according to any one of claims 1 to 8, wherein: The layered material layer includes layered materials, and the layered materials include As, Sb, Bi, black phosphorus, graphite, hard carbon, MXene, MoS2, MoO2, TiO2, RuO2, Li4Ti5O 12 One or more of .

10. The negative electrode current collector according to claim 9, wherein: The layered material includes Bi.

11. The negative electrode current collector according to any one of claims 1 to 10, wherein: The nucleation overpotential of the active reaction layer is less than or equal to 80 mV.

12. The negative electrode current collector according to any one of claims 1 to 11, wherein: The active reaction layer includes an alkali metal affinity material, and the alkali metal affinity material includes one or more of a graphitized carbon material, a non-metallic material, and a metal material. The graphitized carbon material includes one or more of graphene oxide and graphene oxide. The non-metallic material includes one or more of B and P. The metal material includes one or more of a single substance material of Sn, Zn, Mg, Al, Ag, Au, Ga, In, Ge, Pb, As, Sb, Bi and an alloy material thereof.

13. The negative electrode current collector according to claim 12, wherein: The alkali metal affinity material includes one or more of single substance materials of Sn, Zn, Mg, Al and alloy materials thereof.

14. The negative electrode current collector according to any one of claims 1 to 13, wherein: The negative electrode substrate is a two-dimensional structure or a three-dimensional porous structure; and / or, The negative electrode substrate includes a metal material, and the metal material includes one or more of copper, nickel, titanium, magnesium, aluminum, copper alloy, nickel alloy, titanium alloy, magnesium alloy, and aluminum alloy. 15 . A battery cell comprising the negative electrode current collector according to claim 1 .

16. The battery cell according to claim 15, wherein: The battery cell includes at least one of a lithium metal battery cell, a sodium metal battery cell, a negative electrode-free lithium metal battery cell, and a negative electrode-free sodium metal battery cell.

17. A battery comprising the battery cell according to any one of claims 15 to 16.

18. An electrical device comprising the battery according to claim 17, wherein the battery is used to provide electrical energy.

Images