Negative current collector and preparation method thereof, battery monomer, battery and electric device

Abstract

The invention discloses a negative electrode current collector and a preparation method thereof, a battery monomer, a battery and a power utilization device, the negative electrode current collector comprises a metal matrix and nano metal particles located on at least part of the surface of the metal matrix, the metal matrix comprises a first metal element, and the first metal element and the nano metal particles are made of the same material. According to the negative current collector provided by the invention, the battery has good cycle performance, and the battery can also have high reliability.

Description

Technical Field

[0001] 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

[0002] 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 rebuilt, which will continuously consume active ions and electrolytes, thereby affecting the battery's cycle performance. The above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art. Summary of the invention

[0003] 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.

[0004] 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.

[0005] The nano-metal particles located on at least part 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 battery charging and discharging process, the metals such as lithium and sodium have a higher binding force with the nano-metal particles, thereby better improving the reliability and cycle performance of the battery.

[0006] In some embodiments, the nano-metal particles include nano-Cu particles or nano-Ni particles.

[0007] In some embodiments, the first metal element includes Cu or Ni.

[0008] In some embodiments, the diameter of the nano-metal particles is 10 nm-500 nm.

[0009] In some embodiments, the metal substrate comprises a smooth metal substrate or a mesh metal substrate.

[0010] 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.

[0011] In some embodiments, the wire diameter of the mesh metal matrix is ​​75 μm-150 μm, and can be 80 μm-120 μm.

[0012] In some embodiments, the tensile strength of the negative electrode current collector is 8N-30N.

[0013] In some embodiments, the specific surface area of ​​the negative electrode current collector is 190 cm 2 / g-250cm 2 / g.

[0014] In some embodiments, 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.

[0015] In a second aspect, the present application provides a method for preparing a negative electrode current collector, comprising the following steps: providing a metal substrate, the metal substrate 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 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 first metal element and the nano-metal particles are made of the same material.

[0016] The metal matrix includes a first metal element and a second metal element, and the standard electrode potential of the second metal element is lower than the standard electrode potential of the first metal element. Therefore, the more active second metal element in the metal matrix can be dissolved by using the substitution reaction principle, thereby forming holes on the surface of the metal matrix and increasing the electrochemically active specific surface area of ​​the metal matrix. At the same time, the metal in the reaction solution can be replaced by the chemical plating process and nano-metal particles can be precipitated on the surface of the metal matrix.

[0017] 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.

[0018] 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.

[0019] 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 and reducing dendrite formation, thereby improving the reliability and cycle performance of the battery.

[0020] 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 and a negative electrode-free sodium metal battery cell, which can make the battery have good cycle performance and high reliability.

[0021] In some embodiments, the metal substrate and the reaction liquid undergo a replacement reaction under ultrasonic conditions. Ultrasonic treatment can enhance the wetting effect of the metal substrate and the reaction liquid, thereby facilitating a uniform reaction.

[0022] In some embodiments, the reaction time is 15 min-60 min.

[0023] In some embodiments, the nano-metal particles include nano-Cu particles or nano-Ni particles.

[0024] In some embodiments, the first metal element includes Cu or Ni.

[0025] In some embodiments, the second metal element includes one or more of Zn, Ni, Sn, Pb, Be, and Al.

[0026] 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 electrochemical active specific surface area, thereby enabling the battery to have good cycle performance, good processing performance and high reliability.

[0027] In some embodiments, the metal substrate comprises a smooth metal substrate or a mesh metal substrate.

[0028] 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.

[0029] In some embodiments, the wire diameter of the mesh metal matrix is ​​75 μm-150 μm, and can be 80 μm-120 μm.

[0030] By adjusting the wire diameter and / or mesh number of the mesh metal matrix, the electrochemically active specific surface area of ​​the negative electrode current collector can be adjusted. The electrochemically active specific surface area of ​​the negative electrode current collector reflects the effective area of ​​the negative electrode current collector participating in the battery reaction, and when the current is the same, the larger the electrochemically active specific surface area of ​​the negative electrode current collector, the smaller the current density, and thus the smaller the probability of dendrite formation during battery charging and discharging.

[0031] By adjusting the wire diameter and / or mesh number of the mesh metal matrix, the tensile strength of the negative electrode current collector can also be adjusted, so that the battery has good processing performance.

[0032] In some embodiments, the metal salt in the reaction solution includes one or more of metal sulfates, nitrates, hydrochlorides, and acetates.

[0033] In some embodiments, the concentration of the metal ions in the reaction solution is 0.05mol / L-10mol / L, and can be optionally 0.5mol / L-5mol / L. By adjusting the concentration of the metal ions in the reaction solution within the above range, the replacement reaction rate and the precipitation rate of the nano-metal particles can be increased, and the reaction time can be prevented from being excessively increased due to the reaction becoming very slow, thereby reducing energy consumption, and the degree of replacement reaction can be easily controlled, thereby facilitating the uniform precipitation of nano-metal particles, and the diameter of the nano-metal particles can be adjusted.

[0034] 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.

[0035] In some embodiments, the solvent in the reaction solution includes water.

[0036] In some embodiments, the pH of the reaction solution is 3-6.5, and can be 6-6.5. By adjusting the pH of the reaction solution within the above range, the reaction solution can be weakly acidic, and the wetting effect between the metal matrix and the reaction solution can be improved, which is conducive to the precipitation of uniform nano-metal particles on the surface of the metal matrix; it can also avoid the second metal element in the metal matrix from excessively reacting with the acid to affect the effect of the replacement reaction and the precipitation of the nano-metal particles; it can also make the prepared negative electrode current collector have high tensile strength.

[0037] 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.

[0038] 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.

[0039] In a fourth aspect, the present application provides a battery, which includes the battery cell of the third aspect of the present application.

[0040] In a fifth aspect, the present application provides an electrical device, which includes the battery of the fourth aspect of the present application, and the battery is used to provide electrical energy.

[0041] 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

[0042] In order 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 implementation methods of the present application, and for ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0043] Figure 1 A schematic diagram showing a battery cell provided by some embodiments of the present application.

[0044] Figure 2 A schematic diagram of an exploded view of a battery cell provided by some embodiments of the present application is shown.

[0045] Figure 3 A schematic diagram of a battery module provided in some embodiments of the present application is shown.

[0046] Figure 4 A schematic diagram of a battery pack provided in some embodiments of the present application is shown.

[0047] Figure 5 yes Figure 4 An exploded diagram of the battery pack is shown.

[0048] Figure 6 A schematic diagram of an electrical device provided in some embodiments of the present application is shown.

[0049] Figure 7 A scanning electron microscope (SEM) image of the negative electrode current collector prepared in Comparative Example 1 is shown.

[0050] Figure 8 A scanning electron microscope (SEM) image of the negative electrode current collector prepared in Example 1 is shown.

[0051] In the drawings, the drawings may not be drawn according to the actual scale. The reference numerals are as follows: 1 battery pack, 2 upper box, 3 lower box, 4 battery module, 5 battery, 51 housing, 52 electrode assembly, 53 cover plate. DETAILED DESCRIPTION

[0052] Hereinafter, the negative electrode current collector and its preparation method, battery cell, battery and electric device of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. 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 descriptions 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.

[0053] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a 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 a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present 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 real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it 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.

[0054] If not otherwise specified, all embodiments and optional embodiments of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0055] Unless otherwise specified, all technical features and optional technical features of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0056] If there is no special explanation, all steps of the present application can 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 also 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.

[0057] In the present application, the terms "plurality" and "multiple" refer to two or more.

[0058] 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”, or “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 higher in level than the second feature. A first feature being “below”, “below”, or “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 lower in level than the second feature.

[0059] Unless otherwise specified, the terms used in this application have the commonly understood meanings that are commonly understood by those skilled in the art.

[0060] Unless otherwise specified, the values ​​of the parameters mentioned in this application can be measured by 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 specified, the test temperature of each parameter is 25°C.

[0061] 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.

[0062] A battery cell is the smallest unit of a battery, which can independently realize the functions of charging and discharging. The battery cell can be cylindrical, rectangular or in other shapes, etc., which is not limited in the embodiments of the present application. Figure 1 The battery cell 5 is a rectangular parallelepiped structure as an example.

[0063] When there are multiple battery cells, the multiple battery cells are connected in series, in parallel, or in mixed connection through 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 case and battery cells, and the battery cells or battery modules are accommodated in the case. In some embodiments, the case may serve as part of the chassis structure of the vehicle. For example, part of the case may become at least a part of the floor of the vehicle, or part of the case may become at least a part of the crossbeam and longitudinal beam of the vehicle.

[0064] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0065] The battery cell includes an electrode assembly. The electrode assembly may be a winding structure or a laminated structure, which is not limited in the present application.

[0066] The battery cell may also include an outer package, which may be used to encapsulate the electrode assembly. The outer package may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT) and polybutylene succinate (PBS).

[0067] In some embodiments, Figure 2 As shown, the outer package may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity. The electrode assembly 52 is encapsulated in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be adjusted according to demand.

[0068] In some embodiments, battery cells may be assembled into a battery module. The battery module may contain multiple battery cells, and the specific number may be adjusted according to the application and capacity of the battery module. Figure 3 FIG. 4 is a schematic diagram of a battery module 4 as an example. Figure 3 As shown, in the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0069] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0070] 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.

[0071] Figure 4 and Figure 5 is a schematic diagram of a battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a box body and a plurality of battery modules 4 disposed in the box body. The box body includes an upper box body 2 and a lower box body 3, and the upper box body 2 is used to cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the box body in any manner.

[0072] The battery cells provided in the embodiments of the present application may include negative electrode-free battery cells, such as at least one of negative electrode-free lithium metal battery cells, negative electrode-free sodium metal battery cells, and the like.

[0073] A negative electrode-free battery cell generally refers to a battery cell that is formed by not actively setting a negative electrode active material layer on the negative electrode side during the manufacturing process of the battery cell, for example, in the manufacturing process of the battery cell, a layer is not set at the negative electrode through processes such as coating or deposition, or a negative electrode active material layer is formed by a carbonaceous active material layer. During the first charge, the ions obtain electrons on the negative electrode side and deposit on the surface of the negative electrode current collector to form a metal. During discharge, the metal can be converted into ions and return to the positive electrode to achieve cyclic charge and discharge. Compared with other battery cells, a negative electrode-free battery cell can obtain a higher energy density because it does not have a negative electrode active material layer. In some embodiments, in order to improve the performance of the battery cell, some conventional substances that can be used as negative electrode active materials, such as carbon materials, can also be set on the negative electrode side of the negative electrode-free battery cell. Although these substances have a certain capacity, due to their low content and not being used as the main negative electrode active material in the battery cell, the battery cell thus constructed can still be regarded as a negative electrode-free battery cell. The CB (Cell Balance) value of a battery cell without a negative electrode is usually very small. For example, in some embodiments, the CB value of a battery cell without a negative electrode may 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. Since the battery cell without a negative electrode does not contain or contains only a small amount of negative electrode active material, the unit area capacity of the negative electrode is small, and thus the CB value is very small, for example, usually less than or equal to 0.1.

[0074] 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.

[0075] 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.

[0076] 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 cause internal short circuits in the battery, affecting the reliability and cycle performance of the battery.

[0077] 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 battery charge and discharge 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.

[0078] In some embodiments, the nano-metal particles may include nano-Cu particles or nano-Ni particles.

[0079] In some embodiments, the first metal element may include Cu or Ni.

[0080] In some embodiments, the diameter of the nano-metal particles may be 10 nm to 500 nm.

[0081] 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.

[0082] Optionally, the second metal element may include one or more of Zn, Ni, Sn, Pb, Be, and Al.

[0083] In some embodiments, the metal substrate may include a smooth metal substrate or a mesh metal substrate.

[0084] For example, the negative electrode current collector may include a smooth metal matrix and nano-metal particles located on at least a portion of the surface of the smooth metal matrix, and the nano-metal particles protrude from the surface of the smooth metal matrix. Alternatively, the negative electrode current collector may include a mesh metal matrix and nano-metal particles located on at least a portion of the rib surface of the mesh metal matrix, and the nano-metal particles protrude from the rib surface of the mesh metal matrix.

[0085] In some embodiments, the mesh number of the mesh metal substrate may be greater than or equal to 100 meshes, and may be 200 meshes to 500 meshes.

[0086] In some embodiments, the wire diameter of the mesh metal matrix may be 75 μm-150 μm, and may be 80 μm-120 μm.

[0087] In some embodiments, the tensile strength of the negative electrode current collector may be 8N-30N, and may be 10N-30N.

[0088] In some embodiments, the specific surface area of ​​the negative electrode current collector may be 190 cm 2 / g-250cm 2 / g.

[0089] The specific surface area of ​​the negative electrode current collector is a well-known meaning in the art and can be measured using instruments and methods known in the art. For example, it can be measured by nitrogen adsorption specific surface area analysis test method according to GB / T 19587-2017 and calculated by BET (Brunauer Emmett Teller) method. The test instrument can be the Tri-Star 3020 specific surface area pore size analysis tester from Micromeritics, USA.

[0090] The embodiment of the present application also provides a method for preparing a negative electrode current collector.

[0091] The preparation method comprises the following steps: providing a metal substrate, the metal substrate 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 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, thereby obtaining a negative electrode current collector, wherein the material of the first metal element and the nano-metal particles is the same.

[0092] The metal matrix includes a first metal element and a second metal element, and the standard electrode potential of the second metal element is lower than the standard electrode potential of the first metal element. Therefore, the more active second metal element in the metal matrix can be dissolved by using the substitution reaction principle, thereby forming holes on the surface of the metal matrix and increasing the electrochemically active specific surface area of ​​the metal matrix. At the same time, the metal in the reaction solution can be replaced by the chemical plating process and nano-metal particles can be precipitated on the surface of the metal matrix.

[0093] 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.

[0094] 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.

[0095] 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 and reducing dendrite formation, thereby improving the reliability and cycle performance of the battery.

[0096] 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 and a negative electrode-free sodium metal battery cell, which can make the battery have good cycle performance and high reliability.

[0097] In some embodiments, the reaction time may be 15 min-60 min.

[0098] In some embodiments, the metal substrate and the reaction liquid can undergo a replacement reaction under ultrasound. Ultrasonic treatment can enhance the wetting effect of the metal substrate and the reaction liquid, thereby facilitating a uniform reaction.

[0099] Optionally, the ultrasound frequency may be 28 Hz-80 Hz.

[0100] In some embodiments, the generated nano-metal particles may include nano-Cu particles or nano-Ni particles.

[0101] In some embodiments, the first metal element may include Cu or Ni.

[0102] In some embodiments, the second metal element may include one or more of Zn, Ni, Sn, Pb, Be, and Al.

[0103] 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.

[0104] 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 substitution reaction principle, and Cu in the reaction solution can be replaced to form nano Cu metal particles.

[0105] In some embodiments, the first metal element may include Ni, and the second metal element may include Al.

[0106] 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 substitution reaction principle, and Ni in the reaction solution can be replaced to form nano Ni metal particles.

[0107] 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%.

[0108] The higher the mass content of the second metal element, the more holes are formed on the surface of the metal matrix after the replacement reaction, the higher the electrochemical 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 will decrease. In the battery preparation process, the negative electrode current collector usually needs to be rolled multiple times, the tensile strength of the negative electrode current collector decreases, and the processing performance of the negative electrode current collector deteriorates.

[0109] 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.

[0110] In some embodiments, the metal matrix may include a smooth metal matrix or a mesh metal matrix. The nano-metal particles formed on the surface of the smooth metal matrix protrude from the surface of the smooth metal matrix. The nano-metal particles formed on the surface of the mesh metal matrix protrude from the ridge surface of the mesh metal matrix.

[0111] In some embodiments, the metal matrix may include a brass mesh, a nickel silver mesh, or a bronze mesh. Based on comprehensive considerations of conductivity, ductility, tensile strength, cost, and other factors, the brass mesh is optional.

[0112] In some embodiments, the mesh number of the mesh metal substrate may be greater than or equal to 100 meshes, and may be 200 meshes to 500 meshes.

[0113] In some embodiments, the wire diameter of the mesh metal matrix may be 75 μm-150 μm, and may be 80 μm-120 μm.

[0114] By adjusting the wire diameter and / or mesh number of the mesh metal matrix, the electrochemically active specific surface area of ​​the negative electrode current collector can be adjusted. The electrochemically active specific surface area of ​​the negative electrode current collector reflects the effective area of ​​the negative electrode current collector participating in the battery reaction, and when the current is the same, the larger the electrochemically active specific surface area of ​​the negative electrode current collector, the smaller the current density, and thus the smaller the probability of dendrite formation during battery charging and discharging.

[0115] By adjusting the wire diameter and / or mesh number of the mesh metal matrix, the tensile strength of the negative electrode current collector can also be adjusted, so that the battery has good processing performance.

[0116] In some embodiments, the mesh metal matrix may be a planar mesh metal matrix or a three-dimensional mesh metal matrix.

[0117] In some embodiments, the mesh metal matrix can be commercially available or obtained by a weaving process. The weaving method of the mesh metal matrix can adopt a weaving method known in the art, for example, it can include but is not limited to one or more of plain weave, twill weave, mat plain weave, mat twill weave, contrast mat weave, and five-harness weave.

[0118] 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 greater solubility in the reaction solution.

[0119] In some embodiments, the solvent in the reaction solution may include water.

[0120] In some embodiments, the metal salt in the reaction solution may be a water-soluble metal salt. As the above-mentioned water-soluble metal salt, there is no particular limitation as long as it is soluble in the reaction solution and can obtain 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.

[0121] For example, when 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; when 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.

[0122] In some embodiments, the concentration of metal ions in the reaction solution may be 0.05 mol / L-10 mol / L, and may be optionally 0.5 mol / L-5 mol / L.

[0123] By adjusting the concentration of metal ions in the reaction solution within the above range, the rate of the replacement reaction can be increased, the rate of precipitation of nano-metal particles can be increased, and the reaction can be prevented from becoming very slow and causing the reaction time to increase excessively, thereby reducing energy consumption. It can also ensure that the degree of replacement reaction is easy to control, which is conducive to the uniform precipitation of nano-metal particles. The diameter of the nano-metal particles can also be adjusted.

[0124] 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.

[0125] The acid in the reaction solution can enhance the wetting effect between the metal substrate and the reaction solution, thereby facilitating a uniform reaction.

[0126] In some embodiments, the pH of the reaction solution may be 3-6.5, and may be 6-6.5.

[0127] 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 to affect 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.

[0128] 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 through commercial purchase.

[0129] [Positive electrode]

[0130] The battery cell also includes a positive electrode plate.

[0131] 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 including a positive electrode active material. For example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0132] In some embodiments, the positive electrode active material includes a material capable of extracting and inserting lithium.

[0133] 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.

[0134] 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 of 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.

[0135] In some embodiments, the positive electrode active material may include both lithium transition metal oxide and lithium-containing phosphate, thereby facilitating obtaining a battery having both large capacity and high reliability.

[0136] As an example, the positive electrode active material may include but is not limited to LiCoO2, LiNiO2, LiMnO2, LiNi 1 / 2 Mn 1 / 2O2, 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.

[0137] In some embodiments, the positive electrode active material includes a material capable of extracting and embedding 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.

[0138] 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, and Mo), NaMO2 (M includes at least two of Fe, Co, Ni, V, Ti, and Mo), NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, Prussian white, and one or more of their respective modified compounds.

[0139] The modified compounds of the above-mentioned positive electrode active materials may be the ones that undergo doping modification and / or surface coating modification on the positive electrode active materials.

[0140] In some embodiments, the positive electrode film layer may also 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.

[0141] In some embodiments, the positive electrode film layer may also 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), carboxymethyl chitosan (CMCS) One or more.

[0142] 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).

[0143] The positive electrode film layer is usually formed by coating the positive electrode slurry on the positive electrode current collector, drying and cold pressing. The positive electrode slurry is usually formed by dispersing the positive electrode active material, the optional positive electrode conductive agent, the optional positive electrode binder and any other components in a solvent and stirring them uniformly. The solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.

[0144] [Electrolytes]

[0145] The battery cells also include an electrolyte.

[0146] In some embodiments, the electrolyte is an electrolyte solution including an electrolyte salt and an organic solvent.

[0147] In some embodiments, the electrolyte includes anions, which may include bis(fluorosulfonyl)imide anions (FSI - ), bis(trifluoromethanesulfonyl)imide anion (TFSI - ), borate oxalate anion (BOB - ), difluorooxalatoborate anion (DFOB - ), difluorobis(oxalate)phosphate anion (DFOP - ), tetrafluorooxalophosphate anion (TFOP -), difluorophosphate anion (PO2F2 - ), hexafluorophosphate anion (PF6 - ), tetrafluoroborate anion (BF4 - ), hexafluoroarsenate anion (AsF6 - ), trifluoromethanesulfonate anion (CF3SO3 - )

[0148] In some embodiments, the electrolyte includes cations, and the cations may include one or more of lithium ions and sodium ions.

[0149] In some embodiments, the concentration of the electrolyte salt may be 0.3 mol / L or more, and may be 0.7 mol / L or more, and the concentration of the electrolyte salt may be 4 mol / L or less, and may be 2.5 mol / L or less, or 1.7 mol / L or less. When the concentration of the electrolyte salt is within the above range, the electrolyte solution may have a suitable ionic conductivity.

[0150] Organic solvents may include, but are not limited to, one or more of esters, ethers, sulfones, nitriles, etc. Esters may include, but are not limited to, one or more of carbonates, phosphates, carboxylates, sulfates, sulfonates, etc. Carbonates may include cyclic carbonates and / or linear carbonates, and optionally, carbonates may include cyclic carbonates and linear carbonates simultaneously. Linear carbonates may include low-viscosity polar linear carbonates, aliphatic branched-chain carbonates, etc.

[0151] 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 The invention further comprises 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 hexadecafluorooctyl methyl ether, 7-trifluoromethyl hexadecafluorooctyl ethyl ether, and 7-trifluoromethyl hexadecafluorooctyl propyl ether.

[0152] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery 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.

[0153] [Isolation film]

[0154] The battery cell may also include a separator, which is located between the positive electrode and the negative electrode and mainly plays a role in preventing internal short circuits.

[0155] The present application has no particular limitation on the type of isolation membrane, and any known porous isolation membrane with good chemical stability and mechanical stability can be selected.

[0156] In some embodiments, the material of the isolation membrane may include, but is not limited to, one or more of glass fiber, 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 are the same or different.

[0157] 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, and the electrode assembly is placed in an outer package, and the above-mentioned electrolyte is injected after drying. 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 mixed connection to form a battery module. Multiple battery modules can also be connected in series, in parallel or in mixed connection to form a battery pack. In some embodiments, multiple battery cells can also directly form a battery pack.

[0158] 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 and a satellite, an energy storage system, etc.

[0159] 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.

[0160] Figure 6 Schematic diagram of an electric device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the requirements of the electric device for high power and high energy density, a battery pack or a battery module may be used.

[0161] As another example, the electric device may be a mobile phone, a tablet computer, a notebook computer, etc. The electric device is usually required to be light and thin, and a battery cell may be used as a power source.

[0162] Example

[0163] The following examples describe the disclosure of the present application in more detail, and these examples are intended for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present application are apparent to those skilled in the art. Unless otherwise stated, 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 can be used directly without further processing, and the instruments used in the examples are commercially available.

[0164] Example 1

[0165] 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 rib diameter of 100 μm, and a mesh number of 200 meshes.

[0166] 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 use.

[0167] Prepare a 1 mol / L acetic acid aqueous solution, add it dropwise into the prepared 200 mL 1 mol / L CuSO4 aqueous solution, adjust the pH of the mixed system to 6.5, and obtain a reaction solution for use.

[0168] 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 can be observed that the surface of the brass mesh sample changes from yellow to dark red. After the reaction is completed, the sample is taken out, and then washed with deionized water and ethanol several times, and then vacuum dried at 80°C to obtain the negative electrode current collector.

[0169] Example 2

[0170] 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.

[0171] 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%.

[0172] Example 3

[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 H85, which means that the mass fraction of Cu is 85% and the mass fraction of Zn is 15%.

[0175] Example 4

[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 H96, which means that the mass fraction of Cu is 96% and the mass fraction of Zn is 4%.

[0178] Example 5

[0179] 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.

[0180] Example 6

[0181] 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.

[0182] Example 7

[0183] 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 meshes.

[0184] Example 8

[0185] 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 meshes.

[0186] Example 9

[0187] 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 meshes.

[0188] Example 10

[0189] 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.

[0190] Embodiment 11

[0191] 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.

[0192] Comparative Example 1

[0193] 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 wire diameter of 100 μm, and a mesh number of 200 meshes.

[0194] 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.

[0195] Comparative Example 2

[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 wire diameter of 100 μm, and a mesh number of 200 meshes.

[0197] 3 g of the brass mesh was placed in 30 g of a concentrated hydrochloric acid solution with a mass concentration of 20%, and the mixture was kept warm 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.

[0198] The three-dimensional porous copper framework obtained after dealloying was placed in a 5 mmol / L silver nitrate aqueous solution for 1 min in a semi-reactive reaction mode. + The replacement reaction between them makes a layer of Ag adhere to the surface of the porous copper frame. The three-dimensional porous copper frame after the reaction is cleaned with deionized water and placed in an oven at 80°C to obtain a negative electrode current collector.

[0199] Performance Testing

[0200] (1) Electrochemically active specific surface area test of negative electrode current collector

[0201] The negative electrode current collector prepared above was cut into small disc samples with a diameter of 20 mm, and a button cell was prepared with a metal lithium sheet as the counter electrode. The electrolyte salt of the button cell electrolyte is LiFSI with a concentration of 1 mol / L, the solvent of the electrolyte is ethylene glycol dimethyl ether (DME), and the probe molecule is ferrocene with a concentration of 50 mmol / L. The isolation membrane of the button cell can be a PE film with a thickness of 12 μm.

[0202] A series of cyclic voltammetry curves are obtained at different scan rates using an electrochemical workstation, and the peak current is obtained from the cyclic voltammetry curves; the peak current of the obtained series of CV curves and the square root of the scan rate are plotted using the linear regression method to obtain the slope; the electrochemical active specific surface area of ​​the negative electrode current collector is calculated according to the Randles-Sevick equation. During the test, the scan rate can be 4mV / s, 3mV / s, 2mV / s, 1mV / s, and 0.5mV / s. The test instrument can be a British SOLARTRON electrochemical workstation.

[0203] (2) Tensile strength test of negative electrode current collector

[0204] The negative electrode current collector prepared above was cut into rectangular samples with a length of 150 mm and a width of 15 mm. The tensile strength of the negative electrode current collector was tested using a tensile testing machine. During the test, the number of negative electrode current collector samples may be more than 6, and the test results are averaged.

[0205] Before the test, the spacing between the upper and lower fixtures of the test area needs to be adjusted to 100mm, and then the upper end of the cut rectangular sample is first fixed on the upper fixture of the test area of ​​the tensile machine, and the sample is kept vertical as much as possible, and then the lower end of the rectangular sample is fixed on the lower fixture. The test template uses the "metal sheet tensile test", the tensile mode is the constant rate mode, the tensile rate is 50mm / min, and the maximum force (N) that the sample withstands when it breaks is used as the tensile strength. The test instrument can be the KJ-1069 high-speed peeling force tester of Guangdong Kejian Instrument Co., Ltd.

[0206] (3) Nucleation overpotential test of negative electrode current collector

[0207] In an argon-protected glove box, a metal lithium sheet was used as the counter electrode and assembled into a button cell with the negative electrode current collector prepared above. The electrolyte salt of the electrolyte was LiFSI with a concentration of 1 mol / L, and the solvent of the electrolyte was ethylene glycol dimethyl ether (DME). The isolation membrane was a PE film with a thickness of 12 μm.

[0208] At 25°C, the assembled button cell was left to stand for 12 hours and then 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 an obvious 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.

[0209] During the test, the number of negative electrode current collector samples may be more than 6, and the test results are averaged.

[0210] (4) Cyclic performance test

[0211] Lithium iron phosphate, conductive agent carbon black (Super P), and binder polyvinylidene fluoride (PVDF) are mixed evenly in a proper 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 a positive electrode current collector aluminum foil, and after drying, a positive electrode sheet is obtained.

[0212] In an argon-protected glove box, the positive electrode sheet and the negative electrode current collector prepared above were assembled into a button cell. The electrolyte salt of the electrolyte was LiFSI with a concentration of 1 mol / L, and the solvent of the electrolyte was ethylene glycol dimethyl ether (DME). The isolation membrane was a PE film with a thickness of 12 μm.

[0213] At 25°C, after the assembled button cell was left to stand for 12 hours, it was charged to 3.65V at a constant current of 0.2C, and then charged to 0.05C at a constant voltage of 3.65V; after the button cell was left to stand for 10 minutes, it was discharged to 2V at a constant current of 0.5C. The button cell was charged and discharged cyclically according to the above method until the discharge capacity decayed to 50% of the first cycle discharge capacity, and the number of cycles was recorded.

[0214] During the test, the number of button cell samples may be more than 6, and the test results shall be averaged.

[0215] Table 1

[0216]

[0217] Figure 7 A scanning electron microscope (SEM) image of the negative electrode current collector prepared in Comparative Example 1 is shown. Figure 8 The scanning electron microscope (SEM) image of the negative electrode current collector prepared in Example 1 is shown. Figure 7 and Figure 8 It can be seen that the preparation method provided in the present application can precipitate nano-metal particles on at least a portion of the surface of the metal matrix.

[0218] 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 electrochemical 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.

[0219] Comparative Example 2: A porous copper frame is first obtained by a dealloying process, and then a layer of nano-Ag metal particles is attached to the surface of the porous copper frame by a replacement reaction to form a negative electrode current collector, thereby reducing 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. Since Ag has a large solubility 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 cycle performance of the battery.

[0220] It can be seen from the test results of Examples 1 to 4 that by further adjusting the content of copper in the brass mesh, the negative electrode current collector can have high tensile strength, high electrochemical active specific surface area, high lithium affinity and low nucleation overpotential, thereby making the battery have good cycle performance.

[0221] 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 electrochemical active specific surface area, high lithium affinity and low nucleation overpotential, thereby enabling the battery to have good cycle performance.

[0222] 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 electrochemical active specific surface area, high lithium affinity and low nucleation overpotential, thereby making the battery have good cycle performance.

[0223] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and embodiments having substantially the same structure as the technical idea and exerting the same effects within the scope of the technical solution of the present application 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 thought of by those skilled in the art to the embodiments, and other methods of combining some of the constituent elements in the embodiments to construct the embodiments are also included in the scope of the present application.

Claims

1. A negative electrode current collector, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: The metal matrix includes a smooth metal matrix or a mesh metal matrix.

5. The negative electrode current collector according to claim 4, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: The steps include: 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, characterized in that: 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, characterized in that: The reaction time is 15 min-60 min.

11. The preparation method according to any one of claims 8 to 10, characterized in that: 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, characterized in that: The metal matrix includes a smooth metal matrix or a mesh metal matrix.

13. The preparation method according to claim 12, characterized in that: 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, characterized in that: 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, characterized in that: The negative electrode current collector comprises 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, characterized in that: Comprising the battery cell according to claim 15.

17. An electrical device, characterized in that: The battery according to claim 16 is used to provide electrical energy.

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