Negative current collector and preparation method therefor, and battery cell, battery and electric apparatus

Abstract

Disclosed in the present application are a negative current collector and a preparation method therefor, and a battery cell, a battery and an electric apparatus. The negative current collector comprises a metal substrate and metal nanoparticles located on at least part of a surface of the metal substrate, wherein the metal substrate comprises a first metal element, and the first metal element is made of the same material as the metal nanoparticles. By means of the negative current collector provided in the present application, a battery has good cycle performance and high reliability.

Description

Negative electrode current collector and preparation method thereof, battery cell, battery and electrical device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311427855.8, filed on October 31, 2023, entitled “Negative electrode current collector and preparation method thereof, battery cell, battery and electrical device,” and the entire contents of that application are incorporated herein by reference. Technical Field

[0003] The present application relates to a negative electrode current collector and a preparation method thereof, a battery cell, a battery and an electrical device. Background Art

[0004] Compared with ion-type batteries, metal batteries can have higher energy density. However, unlike the negative electrode of ion-type batteries, the negative electrode of metal batteries has a more serious dendrite problem, which affects its commercialization. The growth of dendrites will cause internal short circuits in the battery, affecting the reliability of the battery; at the same time, during the metal deposition and stripping process, the unstable solid electrolyte interface (SEI) film is repeatedly torn and reconstructed, which will continuously consume active ions and electrolytes, thereby affecting the cycle performance of the battery. The above statements are only used to provide background technical 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 and a preparation method thereof, a battery cell, a battery and an electrical device, which can enable the battery to have good cycle performance and high reliability.

[0007] In a first aspect, the present application provides a negative electrode current collector, which includes a metal matrix and nano-metal particles located on at least a portion of the surface of the metal matrix, wherein the metal matrix includes a first metal element, and the first metal element and the nano-metal particles are made of the same material.

[0008] Nanometal particles located on at least part of the surface of the metal matrix can serve as active sites for inducing nucleation, effectively reducing the nucleation overpotential of the negative electrode current collector and improving the battery's reliability and cycle performance. The nanometal particles are made of the same material as the first metal element in the metal matrix. This allows for a stronger binding force between metals like lithium and sodium and the nanometal particles during the battery's charge and discharge processes, further enhancing the battery's reliability and cycle performance.

[0009] In some embodiments, the nano-metal particles include nano-Cu particles or nano-Ni particles.

[0010] In some embodiments, the first metal element includes Cu or Ni.

[0011] In some embodiments, the diameter of the nano-metal particles is 10 nm-500 nm.

[0012] In some embodiments, the metal substrate includes a smooth metal substrate or a mesh metal substrate.

[0013] In some embodiments, the mesh number of the mesh metal substrate is greater than or equal to 100 meshes, and can be optionally 200 meshes-500 meshes.

[0014] In some embodiments, the rib diameter of the mesh metal matrix is ​​75 μm-150 μm, and optionally 80 μm-120 μm.

[0015] In some embodiments, the tensile strength of the negative electrode current collector is 8N-30N.

[0016] In some embodiments, the specific surface area of ​​the negative electrode current collector is 190 cm 2 / g-250cm 2 / g.

[0017] In some embodiments, the metal matrix further includes a second metal element, the standard electrode potential of the second metal element is less than the standard electrode potential of the first metal element, and optionally, the second metal element includes one or more of Zn, Ni, Sn, Pb, Be, and Al.

[0018] In second aspect, the present application provides a method for preparing a negative electrode current collector, comprising the following steps: providing a metal matrix, the metal matrix comprising a first metal element and a second metal element, the standard electrode potential of the second metal element being less than the standard electrode potential of the first metal element; providing a reaction solution, the reaction solution comprising a metal salt and an acid, the metal element in the metal salt being the same as the first metal element; immersing the metal matrix in the reaction solution, removing at least part of the second metal element in the metal matrix through a replacement reaction and forming nano-metal particles on at least part of the surface of the metal matrix to obtain a negative electrode current collector, and the material of the first metal element and the nano-metal particles is the same.

[0019] The metal matrix comprises a first metal element and a second metal element, with the second metal element having a lower standard electrode potential than the first metal element. Therefore, the principle of a displacement reaction can be used to dissolve the more active second metal element in the metal matrix, thereby forming pores on the surface of the metal matrix and increasing the electrochemically active specific surface area of ​​the metal matrix. Furthermore, the electroless plating process can displace the metal in the reaction solution and deposit nano-metal particles on the surface of the metal matrix.

[0020] The nano-metal particles formed on at least part of the surface of the metal matrix can serve as active sites for inducing nucleation, thereby effectively reducing the nucleation overpotential of the negative electrode current collector and improving the reliability and cycle performance of the battery.

[0021] The material of the nano-metal particles is the same as the first metal element in the metal matrix. Therefore, during the battery charging and discharging process, the binding force between metals such as lithium and sodium and the nano-metal particles is higher, thereby better improving the reliability and cycle performance of the battery.

[0022] In addition, since the replacement reaction has an indiscriminate effect on the metal matrix, nano-metal particles will not be selectively precipitated on the surface of the metal matrix, thereby avoiding the emergence of dominant growth points, reducing dendrite formation, and thus improving the reliability and cycle performance of the battery.

[0023] Therefore, the negative electrode current collector prepared by the preparation method provided in the embodiment of the present application is applied to 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, which can make the battery have good cycle performance and high reliability.

[0024] In some embodiments, the metal substrate and the reaction liquid undergo a replacement reaction under ultrasonic conditions. Ultrasonic treatment can enhance the wetting effect between the metal substrate and the reaction liquid, thereby facilitating a uniform reaction.

[0025] In some embodiments, the reaction time is 15 min-60 min.

[0026] In some embodiments, the nano-metal particles include nano-Cu particles or nano-Ni particles.

[0027] In some embodiments, the first metal element includes Cu or Ni.

[0028] In some embodiments, the second metal element includes one or more of Zn, Ni, Sn, Pb, Be, and Al.

[0029] In some embodiments, the mass content of the second metal element in the metal matrix is ​​less than or equal to 35%, and can be optionally 15%-30%. By adjusting the mass content of the second metal element within the above range, the negative electrode current collector can have both high tensile strength and high electrochemically active specific surface area, thereby enabling the battery to have good cycle performance, good processability, and high reliability.

[0030] In some embodiments, the metal substrate includes a smooth metal substrate or a mesh metal substrate.

[0031] In some embodiments, the mesh number of the mesh metal substrate is greater than or equal to 100 meshes, and can be optionally 200 meshes-500 meshes.

[0032] In some embodiments, the rib diameter of the mesh metal matrix is ​​75 μm-150 μm, and optionally 80 μm-120 μm.

[0033] The electrochemically active surface area of ​​the negative electrode current collector can be adjusted by adjusting the rib diameter and / or mesh size of the mesh metal matrix. The electrochemically active surface area of ​​the negative electrode current collector reflects the effective area of ​​the negative electrode current collector participating in the battery reaction. When the current is the same, the larger the electrochemically active surface area of ​​the negative electrode current collector, the lower the current density, and thus the probability of dendrite formation during battery charge and discharge.

[0034] By adjusting the rib diameter and / or mesh number of the mesh-like metal matrix, the tensile strength of the negative electrode current collector can also be adjusted, so that the battery has good processing performance.

[0035] In some embodiments, the metal salt in the reaction solution includes one or more of metal sulfates, nitrates, hydrochlorides, and acetates.

[0036] In some embodiments, the concentration of the metal ions in the reaction solution is 0.05 mol / L-10 mol / L, and can optionally be 0.5 mol / L-5 mol / L. By adjusting the concentration of the metal ions in the reaction solution within the above range, the rate of the replacement reaction can be increased, the rate of precipitation of the nano-metal particles can be increased, and the reaction can be prevented from becoming very slow and resulting in an excessive increase in reaction time, thereby reducing energy consumption. The degree of the replacement reaction can also be easily controlled, thereby facilitating the uniform precipitation of the nano-metal particles. The diameter of the nano-metal particles can also be adjusted.

[0037] In some embodiments, the acid in the reaction solution includes one or more of acetic acid and citric acid. The acid in the reaction solution can enhance the wetting effect between the metal substrate and the reaction solution, thereby facilitating a uniform reaction.

[0038] In some embodiments, the solvent in the reaction solution includes water.

[0039] In some embodiments, the pH of the reaction solution is 3-6.5, optionally 6-6.5. By adjusting the pH of the reaction solution within the aforementioned range, the reaction solution can be made weakly acidic, enhancing the wetting effect between the metal matrix and the reaction solution, thereby facilitating the uniform precipitation of nano-metal particles on the surface of the metal matrix. This can also prevent the second metal element in the metal matrix from excessively reacting with the acid, thereby affecting the effect of the replacement reaction and the precipitation of nano-metal particles. Furthermore, the prepared negative electrode current collector can have high tensile strength.

[0040] In a third aspect, the present application provides a battery cell, which includes the negative electrode current collector of the first aspect of the present application or the negative electrode current collector prepared by the preparation method of the second aspect of the present application.

[0041] Optionally, 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.

[0042] In a fourth aspect, the present application provides a battery comprising the battery cell according to the third aspect of the present application.

[0043] In a fifth aspect, the present application provides an electrical device comprising the battery according to the fourth aspect of the present application, wherein the battery is used to provide electrical energy.

[0044] 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

[0045] 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.

[0046] FIG1 is a schematic diagram of a battery cell provided by some embodiments of the present application.

[0047] FIG2 shows an exploded schematic diagram of a battery cell provided in some embodiments of the present application.

[0048] FIG3 shows a schematic diagram of a battery module provided in some embodiments of the present application.

[0049] FIG4 shows a schematic diagram of a battery pack provided in some embodiments of the present application.

[0050] FIG5 is an exploded schematic diagram of the battery pack shown in FIG4 .

[0051] FIG6 shows a schematic diagram of an electrical device provided in some embodiments of the present application.

[0052] FIG7 shows a scanning electron microscope (SEM) image of the negative electrode current collector prepared in Comparative Example 1.

[0053] FIG8 shows a scanning electron microscope (SEM) image of the negative electrode current collector prepared in Example 1.

[0054] In the accompanying drawings, which are not necessarily drawn to scale, reference numerals are as follows: 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 battery, 51 housing, 52 electrode assembly, 53 cover plate. DETAILED DESCRIPTION

[0055] Below, with appropriate reference to the accompanying drawings, the embodiments of the negative electrode current collector and its preparation method, 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 are 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.

[0056] " 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] In this application, the terms "plurality" and "multiple" refer to two or more.

[0061] 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.

[0062] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0068] 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.

[0069] 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 material can be a plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0070] In some embodiments, as shown in Figure 2, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and side plates connected to the bottom 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.

[0071] 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 3 is a schematic diagram of a battery module 4 as an example. As shown in Figure 3, 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.

[0072] 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.

[0073] 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.

[0074] Figures 4 and 5 are schematic diagrams of an exemplary battery pack 1. As shown in Figures 4 and 5, 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.

[0075] The battery cells provided in the embodiments of the present application may include negative electrode-free battery cells, for example, at least one of negative electrode-free lithium metal battery cells, negative electrode-free sodium metal battery cells, and the like.

[0076] 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.

[0077] An embodiment of the present application provides a negative electrode current collector, which can be used in 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, to enable the battery to have good cycle performance and high reliability.

[0078] The negative electrode current collector provided in the embodiment of the present application includes a metal matrix and nano-metal particles located on at least a portion of the surface of the metal matrix. The metal matrix includes a first metal element, and the first metal element and the nano-metal particles are made of the same material.

[0079] Metals such as lithium and sodium have poor wettability on the skeleton of conventional metal current collectors, which leads to a large nucleation overpotential. At the same time, they are prone to preferential nucleation at certain surface defect locations of conventional metal current collectors. The preferential nucleation locations will form advantageous growth points, which in turn will easily lead to dendrite formation. In severe cases, it will also cause internal short circuits in the battery, affecting the reliability and cycle performance of the battery.

[0080] The negative electrode current collector provided in the embodiment of the present application includes a metal matrix and nano-metal particles located on at least a portion of the surface of the metal matrix, the metal matrix includes a first metal element, and the first metal element and the nano-metal particles are made of the same material. The nano-metal particles located on at least a portion of the surface of the metal matrix can serve as active points for inducing nucleation, thereby effectively reducing the nucleation overpotential of the negative electrode current collector and improving the reliability and cycle performance of the battery. The material of the nano-metal particles is the same as the first metal element in the metal matrix, so that during the charge and discharge process of the battery, the binding force between metals such as lithium and sodium and the nano-metal particles is higher, thereby better improving the reliability and cycle performance of the battery.

[0081] In some embodiments, the nano-metal particles may include nano-Cu particles or nano-Ni particles.

[0082] In some embodiments, the first metal element may include Cu or Ni.

[0083] In some embodiments, the diameter of the nano-metal particles may be 10 nm to 500 nm.

[0084] In some embodiments, the metal matrix may further include a second metal element, the standard electrode potential of the second metal element being lower than the standard electrode potential of the first metal element.

[0085] Optionally, the second metal element may include one or more of Zn, Ni, Sn, Pb, Be, and Al.

[0086] In some embodiments, the metal substrate may include a smooth metal substrate or a mesh metal substrate.

[0087] For example, the negative electrode current collector may include a smooth metal substrate and nano-metal particles located on at least a portion of the surface of the smooth metal substrate, with the nano-metal particles protruding from the surface of the smooth metal substrate. Alternatively, the negative electrode current collector may include a mesh metal substrate and nano-metal particles located on at least a portion of the rib surface of the mesh metal substrate, with the nano-metal particles protruding from the rib surface of the mesh metal substrate.

[0088] In some embodiments, the mesh number of the mesh metal substrate may be greater than or equal to 100 mesh, and may be optionally 200 mesh to 500 mesh.

[0089] In some embodiments, the rib diameter of the mesh metal matrix may be 75 μm-150 μm, and optionally 80 μm-120 μm.

[0090] In some embodiments, the tensile strength of the negative electrode current collector may be 8N-30N, optionally 10N-30N.

[0091] In some embodiments, the specific surface area of ​​the negative electrode current collector can be 190 cm 2 / g-250cm 2 / g.

[0092] The specific surface area of ​​the negative electrode current collector is well known in the art and can be measured using instruments and methods known in the art. For example, it can be measured using the nitrogen adsorption specific surface area analysis method in accordance with GB / T 19587-2017 and calculated using the BET (Brunauer Emmett Teller) method. The test instrument can be a Micromeritics Tri-Star 3020 Specific Surface Area Pore Size Analyzer.

[0093] The present invention also provides a method for preparing a negative electrode current collector.

[0094] The preparation method includes the following steps: providing a metal substrate, the metal substrate including a first metal element and a second metal element, the standard electrode potential of the second metal element being less than the standard electrode potential of the first metal element; providing a reaction solution, the reaction solution including a metal salt and an acid, the metal element in the metal salt being the same as the first metal element; immersing the metal substrate in the reaction solution, removing at least a portion of the second metal element in the metal substrate through a replacement reaction and forming nano-metal particles on at least a portion of the surface of the metal substrate to obtain a negative electrode current collector, wherein the material of the first metal element and the nano-metal particles is the same.

[0095] The metal matrix comprises a first metal element and a second metal element, with the second metal element having a lower standard electrode potential than the first metal element. Therefore, the principle of a displacement reaction can be used to dissolve the more active second metal element in the metal matrix, thereby forming pores on the surface of the metal matrix and increasing the electrochemically active specific surface area of ​​the metal matrix. Furthermore, the electroless plating process can displace the metal in the reaction solution and deposit nano-metal particles on the surface of the metal matrix.

[0096] The nano-metal particles formed on at least part of the surface of the metal matrix can serve as active sites for inducing nucleation, thereby effectively reducing the nucleation overpotential of the negative electrode current collector and improving the reliability and cycle performance of the battery.

[0097] The material of the nano-metal particles is the same as the first metal element in the metal matrix. Therefore, during the battery charging and discharging process, the binding force between metals such as lithium and sodium and the nano-metal particles is higher, thereby better improving the reliability and cycle performance of the battery.

[0098] In addition, since the replacement reaction has an indiscriminate effect on the metal matrix, nano-metal particles will not be selectively precipitated on the surface of the metal matrix, thereby avoiding the emergence of dominant growth points, reducing dendrite formation, and thus improving the reliability and cycle performance of the battery.

[0099] Therefore, the negative electrode current collector prepared by the preparation method provided in the embodiment of the present application is applied to 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, which can make the battery have good cycle performance and high reliability.

[0100] In some embodiments, the reaction time may be 15 min to 60 min.

[0101] In some embodiments, the metal substrate and the reaction liquid can undergo a replacement reaction under ultrasonic conditions. Ultrasonic treatment can enhance the wetting effect between the metal substrate and the reaction liquid, thereby facilitating a uniform reaction.

[0102] Optionally, the ultrasound frequency may be 28 Hz-80 Hz.

[0103] In some embodiments, the generated nano-metal particles may include nano-Cu particles or nano-Ni particles.

[0104] In some embodiments, the first metal element may include Cu or Ni.

[0105] In some embodiments, the second metal element may include one or more of Zn, Ni, Sn, Pb, Be, and Al.

[0106] In some embodiments, the first metal element may include Cu, and the second metal element may include one or more of Zn, Ni, Sn, Pb, and Be.

[0107] The standard electrode potential of the second metal element is lower than that of Cu, and its metal activity is higher than that of Cu. Therefore, the more active second metal element on the surface of the metal matrix can be dissolved by the displacement reaction principle, and the Cu in the reaction solution can be replaced to form nano Cu metal particles.

[0108] In some embodiments, the first metal element may include Ni, and the second metal element may include Al.

[0109] The standard electrode potential of the second metal element is lower than that of Ni, and its metal activity is higher than that of Ni. Therefore, the more active second metal element on the surface of the metal matrix can be dissolved by the displacement reaction principle, and the Ni in the reaction solution can be replaced to form nano-Ni metal particles.

[0110] In some embodiments, the mass content of the second metal element in the metal matrix may be less than or equal to 35%, optionally 4%-35%, and more optionally 15%-30%.

[0111] The higher the mass content of the second metal element, the more pores are formed on the surface of the metal matrix after the replacement reaction, the higher the electrochemically active specific surface area of ​​the metal matrix, and the more uniform the nano-metal particles formed. This can better reduce the nucleation overpotential of the negative electrode current collector and reduce the dominant growth points, thereby improving the reliability and cycle performance of the battery. However, as the mass content of the second metal element increases, the tensile strength of the prepared negative electrode current collector decreases. In the battery preparation process, the negative electrode current collector usually needs to pass through the roller multiple times, which reduces the tensile strength of the negative electrode current collector and deteriorates the processing performance of the negative electrode current collector.

[0112] Therefore, by adjusting the mass content of the second metal element within the above range, the negative electrode current collector can have both high tensile strength and high electrochemical active specific surface area, thereby enabling the battery to have good cycle performance, good processing performance and high reliability.

[0113] In some embodiments, the metal substrate may include a smooth metal substrate or a mesh metal substrate. The nano-metal particles formed on the surface of the smooth metal substrate protrude from the surface of the smooth metal substrate. The nano-metal particles formed on the surface of the mesh metal substrate protrude from the ridge surface of the mesh metal substrate.

[0114] In some embodiments, the metal matrix may include a brass mesh, a nickel silver mesh, or a bronze mesh. Based on comprehensive considerations of electrical conductivity, ductility, tensile strength, cost, and other factors, the brass mesh is optional.

[0115] In some embodiments, the mesh number of the mesh metal substrate may be greater than or equal to 100 mesh, and may be optionally 200 mesh to 500 mesh.

[0116] In some embodiments, the rib diameter of the mesh metal matrix may be 75 μm-150 μm, and optionally 80 μm-120 μm.

[0117] The electrochemically active surface area of ​​the negative electrode current collector can be adjusted by adjusting the rib diameter and / or mesh size of the mesh metal matrix. The electrochemically active surface area of ​​the negative electrode current collector reflects the effective area of ​​the negative electrode current collector participating in the battery reaction. When the current is the same, the larger the electrochemically active surface area of ​​the negative electrode current collector, the lower the current density, and thus the probability of dendrite formation during battery charge and discharge.

[0118] By adjusting the rib diameter and / or mesh number of the mesh-like metal matrix, the tensile strength of the negative electrode current collector can also be adjusted, so that the battery has good processing performance.

[0119] In some embodiments, the mesh metal matrix may be a planar mesh metal matrix or a three-dimensional mesh metal matrix.

[0120] In some embodiments, the mesh metal matrix can be commercially available or obtained through a weaving process. The weaving method of the mesh metal matrix can adopt weaving methods known in the art, such as, but not limited to, one or more of plain weave, twill weave, mat plain weave, mat twill weave, contrast mat weave, and five-harness weave.

[0121] In some embodiments, the metal salt in the reaction solution is selected based on the principle that the salt formed by the anion in the reaction solution and the second metal element has a large solubility in the reaction solution.

[0122] In some embodiments, the solvent in the reaction solution may include water.

[0123] In some embodiments, the metal salt in the reaction solution may be a water-soluble metal salt. The water-soluble metal salt is not particularly limited as long as it is soluble in the reaction solution and can produce a reaction solution of the desired concentration. For example, it may include, but is not limited to, one or more of metal sulfates, nitrates, hydrochlorides, and acetates.

[0124] For example, if the first metal element includes Cu, the metal salt in the reaction liquid may include but is not limited to one or more of CuSO4, CuCl2, and Cu(NO3)2; if the first metal element includes Ni, the metal salt in the reaction liquid may include but is not limited to one or more of NiSO4, NiCl2, and nickel acetate.

[0125] In some embodiments, the concentration of metal ions in the reaction solution may be 0.05 mol / L-10 mol / L, optionally 0.5 mol / L-5 mol / L.

[0126] By adjusting the concentration of metal ions in the reaction solution within the above range, the replacement reaction rate can be increased, the precipitation rate of nano-metal particles can be increased, the reaction can be prevented from becoming very slow and resulting in an excessive increase in reaction time, thereby reducing energy consumption, and the degree of replacement reaction can be easily controlled, which is conducive to the uniform precipitation of nano-metal particles. The diameter of the nano-metal particles can also be adjusted.

[0127] In some embodiments, the acid in the reaction solution may include, but is not limited to, one or more of acetic acid and citric acid.

[0128] The acid in the reaction liquid can enhance the wetting effect between the metal substrate and the reaction liquid, thereby facilitating a uniform reaction.

[0129] In some embodiments, the pH of the reaction solution may be 3-6.5, optionally 6-6.5.

[0130] By adjusting the pH of the reaction liquid within the above range, the reaction liquid can be made weakly acidic, thereby enhancing the wetting effect between the metal matrix and the reaction liquid, thereby facilitating the precipitation of uniform nano-metal particles on the surface of the metal matrix; it can also avoid excessive reaction of the second metal element in the metal matrix with the acid, thereby affecting the effect of the replacement reaction and the precipitation of nano-metal particles; it can also make the prepared negative electrode current collector have high tensile strength.

[0131] Unless otherwise specified, some raw materials used in the preparation process of the negative electrode current collector provided in the embodiments of the present application can be obtained commercially.

[0132] [Positive electrode]

[0133] The battery cell also includes a positive electrode plate.

[0134] 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.

[0135] In some embodiments, the positive electrode active material includes a material capable of extracting and inserting lithium.

[0136] 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.

[0137] In some embodiments, in order to further improve the energy density of the battery, the positive electrode active material may include a general formula of Li a Ni b Co c M d O e D f 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.

[0138] 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 with both high capacity and high reliability.

[0139] 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 0.2O2(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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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).

[0145] 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 (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0146] 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).

[0147] [Electrolytes]

[0148] The battery cells also include an electrolyte.

[0149] In some embodiments, the electrolyte is an electrolyte solution including an electrolyte salt and an organic solvent.

[0150] 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 - )

[0151] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0152] 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.

[0153] 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.

[0154] 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), ethyl methyl 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, C4F9OCH3, 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-trifluoromethyldecanoate One or more of fluoropentyl 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 hexadecafluorooctyl methyl ether, 7-trifluoromethyl hexadecafluorooctyl ethyl ether, and 7-trifluoromethyl hexadecafluorooctyl propyl ether.

[0155] 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 battery properties, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.

[0156] [Isolation film]

[0157] A battery cell may also include a separator, which is located between the positive electrode and the negative electrode and mainly serves to prevent internal short circuits.

[0158] The present application has no particular limitation on the type of isolation membrane, and any known isolation membrane with a porous structure having good chemical stability and mechanical stability can be selected.

[0159] In some embodiments, the material of the isolation membrane may include, but is not limited to, one or more of fiberglass, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different.

[0160] The preparation method of battery cells is well known. In some embodiments, the positive electrode, separator, negative electrode and 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 lamination process. The electrode assembly is placed in an outer package, dried, and then injected with the above-mentioned electrolyte. After vacuum packaging, standing, formation and other processes, a battery cell is obtained. Multiple battery cells can also be further connected in series, in parallel, or in a mixed manner to form a battery module. Multiple battery modules can also be connected in series, in parallel, or in a mixed manner to form a battery pack. In some embodiments, multiple battery cells can also directly form a battery pack.

[0161] 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.

[0162] The electrical device can select the type of battery according to its usage requirements, such as a battery cell, a battery module or a battery pack.

[0163] Figure 6 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.

[0164] 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.

[0165] Example

[0166] 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.

[0167] Example 1

[0168] The commercially available brass mesh has a grade of H75 (indicating that the mass fraction of Cu is 75% and the mass fraction of Zn is 25%), a wire diameter of 100 μm, and a mesh size of 200 meshes.

[0169] First, wipe the surface of the brass mesh with a 1 mol / L acetic acid aqueous solution, then ultrasonically clean it with ethanol and deionized water, and then vacuum dry it at 80°C for later use.

[0170] Prepare a 1 mol / L aqueous acetic acid solution, add it dropwise to 200 mL of a 1 mol / L aqueous CuSO4 solution, and adjust the pH of the mixed system to 6.5 to obtain a reaction solution for later use.

[0171] The dried brass mesh sample was immersed in the reaction solution and then placed in an ultrasonic cleaner for ultrasonic reaction for 30 minutes. During the reaction, it was observed that the surface of the brass mesh sample changed from yellow to dark red. After the reaction was completed, the sample was taken out and washed with deionized water and ethanol several times, and then vacuum dried at 80°C to obtain the negative electrode current collector.

[0172] Example 2

[0173] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the Cu content in the commercially available brass mesh is different.

[0174] The alloy grade of the commercially available brass mesh is H65, which means that the mass fraction of Cu is 65% and the mass fraction of Zn is 35%.

[0175] Example 3

[0176] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the Cu content in the commercially available brass mesh is different.

[0177] The alloy grade of the commercially available brass mesh is H85, which means that the mass fraction of Cu is 85% and the mass fraction of Zn is 15%.

[0178] Example 4

[0179] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the Cu content in the commercially available brass mesh is different.

[0180] The alloy grade of the commercially available brass mesh is H96, which means that the mass fraction of Cu is 96% and the mass fraction of Zn is 4%.

[0181] Example 5

[0182] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the diameter of the ribs of the commercially available brass mesh is 75 μm.

[0183] Example 6

[0184] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the diameter of the ribs of the commercially available brass mesh is 150 μm.

[0185] Example 7

[0186] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the mesh size of the commercially available brass mesh is 100 mesh.

[0187] Example 8

[0188] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the mesh size of the commercially available brass mesh is 300 mesh.

[0189] Example 9

[0190] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the mesh size of the commercially available brass mesh is 500 mesh.

[0191] Example 10

[0192] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the concentration of the prepared CuSO4 aqueous solution is 5 mol / L.

[0193] Example 11

[0194] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the pH of the reaction solution is adjusted to 3.

[0195] Comparative Example 1

[0196] The commercially available brass mesh has an alloy grade of H75 (indicating that the mass fraction of Cu is 75% and the mass fraction of Zn is 25%), a rib diameter of 100 μm, and a mesh size of 200 meshes.

[0197] The surface of the brass mesh was first wiped with a 1 mol / L acetic acid aqueous solution, then ultrasonically cleaned with ethanol and deionized water, and then vacuum-dried at 80°C to serve as the negative electrode current collector.

[0198] Comparative Example 2

[0199] The commercially available brass mesh has an alloy grade of H75 (indicating that the mass fraction of Cu is 75% and the mass fraction of Zn is 25%), a rib diameter of 100 μm, and a mesh size of 200 meshes.

[0200] 3 g of brass mesh was placed in 30 g of concentrated hydrochloric acid solution with a mass concentration of 20%, and the reaction was kept at 80° C. for 5 hours. The brass mesh was then taken out, rinsed with deionized water, and dried to obtain a copper frame with a three-dimensional porous shape.

[0201] The copper frame with three-dimensional porous shape obtained after dealloying was placed in a 5mmol / L silver nitrate aqueous solution in a semi-reactive reaction mode for 1 minute. + The replacement reaction between them causes a layer of Ag to adhere to the surface of the porous copper frame. The three-dimensional porous copper frame after the reaction is cleaned with deionized water and then placed in an oven at 80°C to dry to obtain the negative electrode current collector.

[0202] Performance Testing

[0203] (1) Electrochemically active specific surface area test of negative electrode current collector

[0204] The negative electrode current collector prepared above was cut into small disc samples with a diameter of 20 mm. A button cell was prepared using a lithium metal sheet as the counter electrode. The electrolyte salt in the button cell's electrolyte solution was LiFSI at a concentration of 1 mol / L, the solvent was ethylene glycol dimethyl ether (DME), and the probe molecule was ferrocene at a concentration of 50 mmol / L. The separator of the button cell could be a 12 μm thick PE film.

[0205] A series of cyclic voltammetry curves were obtained at different scan rates using an electrochemical workstation, and the peak currents were determined from these curves. The peak currents of these CV curves were plotted against the square root of the scan rate using linear regression to obtain the slopes. The electrochemically active surface area of ​​the negative electrode current collector was calculated using the Randles-Sevick equation. The scan rates used during testing were 4mV / s, 3mV / s, 2mV / s, 1mV / s, and 0.5mV / s. The test instrument was a UK-based SOLARTRON electrochemical workstation.

[0206] (2) Tensile strength test of negative electrode current collector

[0207] Cut the prepared negative electrode current collector into rectangular samples 150 mm long and 15 mm wide. Test the tensile strength of the negative electrode current collector using a tensile testing machine. Six or more negative electrode current collector samples can be used for testing, and the test results are averaged.

[0208] Before testing, adjust the spacing between the upper and lower fixtures in the test area to 100mm. Secure the upper end of the cut rectangular sample to the upper fixture in the tensile testing machine's test area, ensuring the sample is as vertical as possible. Secure the lower end of the rectangular sample to the lower fixture. Use the "Metal Sheet Tensile Test" test template, set the tensile mode to constant rate, and set the tensile rate to 50mm / min. The maximum force (N) at break is used as the tensile strength. The testing instrument can be the KJ-1069 High-Speed ​​Peel Tester from Guangdong Kejian Instrument Co., Ltd.

[0209] (3) Nucleation overpotential test of negative electrode current collector

[0210] In an argon-protected glove box, a button-type battery was assembled using a lithium metal sheet as the counter electrode and the anode current collector prepared above. The electrolyte salt was LiFSI at a concentration of 1 mol / L, and the solvent was ethylene glycol dimethyl ether (DME). A 12 μm thick PE film was used as the separator.

[0211] At 25°C, the assembled button cell was left to stand for 12 hours and the current was measured 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 between the voltage at the lowest point and the flat part of the voltage platform is used as the nucleation overpotential of the negative electrode current collector.

[0212] During the test, the number of negative electrode current collector samples can be more than 6, and the test results are averaged.

[0213] (4) Cyclic performance test

[0214] 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.

[0215] In an argon-protected glove box, the positive electrode sheet and the prepared negative current collector were assembled into a button-type battery. 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.

[0216] 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.

[0217] During the test, the number of button battery samples can be more than 6, and the test results are averaged.

[0218] Table 1

[0219] Figure 7 shows a scanning electron microscope (SEM) image of the negative electrode current collector prepared in Comparative Example 1. Figure 8 shows a scanning electron microscope (SEM) image of the negative electrode current collector prepared in Example 1. As can be seen from Figures 7 and 8, the preparation method provided in this application can precipitate nanometal particles on at least a portion of the surface of the metal substrate.

[0220] It can be seen from the test results of Example 1 and Comparative Examples 1 to 2 that the formation of nano-copper particles and nano-pores on the surface of the brass mesh through the replacement reaction can effectively improve the lithium affinity and electrochemically active specific surface area of ​​the negative electrode current collector without significantly reducing the tensile strength of the negative electrode current collector, and can also reduce the nucleation overpotential of the negative electrode current collector and improve the cycle performance of the battery.

[0221] In Comparative Example 2, a porous copper frame is first obtained through a dealloying process, and then a layer of nano-Ag metal particles is attached to the surface of the porous copper frame through a replacement reaction to form a negative electrode current collector. This reduces the tensile strength of the negative electrode current collector. In addition, the material of the formed nano-Ag metal particles is different from the first metal element (i.e., Cu) in the metal matrix. Due to the high solubility of Ag in Li, Ag is more likely to form an alloy with Li and separate from the Cu metal matrix than the Cu metal matrix, resulting in poor battery cycle performance.

[0222] From the test results of Examples 1 to 4, it can be seen that by further adjusting the copper content in the brass mesh, the negative electrode current collector can have high tensile strength, high electrochemically active specific surface area, high lithium affinity and low nucleation overpotential, thereby making the battery have good cycle performance.

[0223] It can be seen from the test results of Examples 1, 5 to 9 that by further adjusting the wire diameter and mesh size of the brass mesh, the negative electrode current collector can have high tensile strength, high electrochemically active specific surface area, high lithium affinity and low nucleation overpotential, thereby enabling the battery to have good cycle performance.

[0224] It can be seen from the test results of Examples 1, 10, and 11 that by further adjusting the concentration and pH of the reaction solution, the negative electrode current collector can have high tensile strength, high electrochemically active specific surface area, high lithium affinity, and low nucleation overpotential, thereby enabling the battery to have good cycle performance.

[0225] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solution of the present application, embodiments having substantially the same structure as the technical concept and exerting the same effects are all included in the technical scope of the present application. In addition, within the scope of the subject matter of the present application, various modifications that can be conceived by those skilled in the art to the embodiments, and other methods constructed by combining 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, wherein: The negative electrode current collector includes a metal matrix and nano-metal particles located on at least a portion of the surface of the metal matrix. The metal matrix includes a first metal element, and the first metal element and the nano metal particles are made of the same material.

2. The negative electrode current collector according to claim 1, wherein: The nano metal particles include nano Cu particles or nano Ni particles; and / or, The first metal element includes Cu or Ni.

3. The negative electrode current collector according to any one of claims 1 to 2, wherein: The diameter of the nano metal particles is 10nm-500nm.

4. The negative electrode current collector according to any one of claims 1 to 3, wherein: The metal matrix includes a smooth metal matrix or a mesh metal matrix.

5. The negative electrode current collector according to claim 4, wherein: The mesh number of the mesh metal substrate is greater than or equal to 100 meshes, and can be 200 meshes to 500 meshes; and / or, The rib diameter of the mesh metal matrix is ​​75 μm-150 μm, and can be optionally 80 μm-120 μm.

6. The negative electrode current collector according to any one of claims 4 to 5, wherein: The tensile strength of the negative electrode current collector is 8N-30N; and / or, The specific surface area of ​​the negative electrode current collector is 190 cm 2 / g-250cm 2 / g.

7. The negative electrode current collector according to any one of claims 1 to 6, wherein: The metal matrix also includes a second metal element, the standard electrode potential of the second metal element is less than the standard electrode potential of the first metal element, and optionally, the second metal element includes one or more of Zn, Ni, Sn, Pb, Be, and Al.

8. A method for preparing a negative electrode current collector, comprising the following steps: Providing a metal matrix, the metal matrix comprising a first metal element and a second metal element, wherein a standard electrode potential of the second metal element is smaller than a standard electrode potential of the first metal element; Providing a reaction solution, the reaction solution comprising a metal salt and an acid, wherein the metal element in the metal salt is the same as the first metal element; The metal substrate is immersed in the reaction solution, at least part of the second metal element in the metal substrate is removed by replacement reaction and nano metal particles are formed on at least part of the surface of the metal substrate to obtain a negative electrode current collector, and the first metal element and the nano metal particles are made of the same material.

9. The preparation method according to claim 8, wherein: The metal matrix and the reaction liquid undergo a replacement reaction under ultrasonic conditions.

10. The preparation method according to any one of claims 8 to 9, wherein: The reaction time is 15 min-60 min.

11. The preparation method according to any one of claims 8 to 10, wherein: The nano metal particles include nano Cu particles or nano Ni particles; and / or, The first metal element includes Cu or Ni; and / or, The second metal element includes one or more of Zn, Ni, Sn, Pb, Be, and Al; and / or, The mass content of the second metal element in the metal matrix is ​​less than or equal to 35%, and can be optionally 15%-30%.

12. The preparation method according to any one of claims 8 to 11, wherein: The metal matrix includes a smooth metal matrix or a mesh metal matrix.

13. The preparation method according to claim 12, wherein: The mesh number of the mesh metal substrate is greater than or equal to 100 meshes, and can be 200 meshes to 500 meshes; and / or, The rib diameter of the mesh metal matrix is ​​75 μm-150 μm, and can be optionally 80 μm-120 μm.

14. The preparation method according to any one of claims 8 to 13, wherein: The metal salt in the reaction solution includes one or more of metal sulfates, nitrates, hydrochlorides, and acetates; and / or, The concentration of the metal ions in the reaction solution is 0.05 mol / L-10 mol / L, and can be 0.5 mol / L-5 mol / L; and / or, The acid in the reaction solution includes one or more of acetic acid and citric acid; and / or, The solvent in the reaction solution includes water; and / or, The pH of the reaction solution is 3-6.5, and can be optionally 6-6.

5.

15. A battery cell, comprising the negative electrode current collector according to any one of claims 1 to 7 or the negative electrode current collector prepared by the preparation method according to any one of claims 8 to 14, optionally, the battery cell comprises at least one of a negative electrode-free lithium metal battery cell and a negative electrode-free sodium metal battery cell.

16. A battery comprising the battery cell according to claim 15.

17. An electrical device comprising the battery according to claim 16, wherein the battery is used to provide electrical energy.

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