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

Abstract

The present application discloses a negative electrode current collector, a battery cell, a battery and an electric device. The negative electrode current collector comprises a substrate and an alloy layer located on at least one side of the substrate; the alloy layer comprises a first metal element and a second metal element; the substrate comprises a third metal element; the nucleation overpotential of a simple substance of the second metal element is smaller than that of a simple substance of the first metal element; the nucleation overpotential of a lithium metal of the simple substance of the first metal element is greater than or equal to 0.10 V; and the nucleation overpotential of the simple substance of the second metal element is smaller than the nucleation overpotential of a simple substance of the third metal element. The present application can enable the battery to have high coulombic efficiency, high reliability and long cycle life.

Description

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

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202410004799.5, filed on January 2, 2024, entitled “Negative electrode current collector, battery cell, battery and electrical device,” the entire contents of which are incorporated herein by reference. Technical Field

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

[0004] Compared to ionic batteries, metal batteries can have higher energy densities. However, unlike the negative electrodes of ionic batteries, metal batteries suffer from uneven deposition. Applying a coating with a better affinity for the deposited metal on the negative electrode current collector surface of metal batteries can help regulate the deposition behavior of the deposited metal. However, current coatings are prone to detachment during long-term battery cycling, thus affecting the reliability and electrochemical performance of metal batteries.

[0005] Summary of the Invention

[0006] The present application provides a negative electrode current collector, a battery cell, a battery and an electrical device, which can enable the battery to have high coulombic efficiency, high reliability and long cycle life.

[0007] In a first aspect, the present application provides a negative electrode current collector comprising a substrate and an alloy layer located on at least one side of the substrate, the alloy layer comprising a first metal element and a second metal element, the substrate comprising a third metal element, the nucleation overpotential of the second metal element as a single substance is less than the nucleation overpotential of the first metal element as a single substance, the nucleation overpotential of lithium metal as a single substance of the first metal element is greater than or equal to 0.10 V, and the nucleation overpotential of the second metal element as a single substance is less than the nucleation overpotential of the third metal element as a single substance.

[0008] The embodiment of the present application sets an alloy layer on the substrate of the negative electrode current collector, and makes the alloy layer include a second metal element with a nucleation overpotential less than that of the substrate. Thus, when the battery is charged, the second metal element in the alloy layer can provide a large number of active sites, induce uniform metal deposition, and can also form an alloy with the deposited metal, thereby reducing the nucleation overpotential of the negative electrode current collector, reducing local nucleation, and slowing down dendrite growth. The alloy layer also includes a first metal element with a nucleation overpotential greater than or equal to 0.10V for lithium metal. Thus, the first metal element mainly plays the role of an inert skeleton in the alloy layer and hardly participates in the reaction. Thus, it can serve as a framework in the alloy layer to limit the volume expansion caused by the second metal element and the deposited metal forming an alloy when the battery is charged, thereby reducing the risk of the alloy layer falling off as a whole due to the volume expansion of the alloy layer, reducing the internal porosity of the battery, deteriorating the electrolyte wettability, and deteriorating the alkali metal deposition and stripping activity. Therefore, the negative electrode current collector provided by the embodiment of the present application can reduce the loss of active ions during the battery cycle and improve the battery's cycle stability, coulombic efficiency and reliability.

[0009] In addition, since the alloy layer includes both a second metal element with a nucleation overpotential less than that of the matrix and a first metal element with a nucleation overpotential greater than or equal to 0.10V for lithium metal, it can also reduce the loss of active ions during the first charge of the battery and improve the first coulombic efficiency of the battery.

[0010] Therefore, the negative electrode current collector provided in the embodiment of the present application can enable the battery to have high coulombic efficiency, high reliability and long cycle life.

[0011] In some embodiments, the first metal element is the same as the third metal element.

[0012] When the first metal element and the third metal element are the same, the bonding force between the same materials is stronger, thereby further increasing the bonding force between the alloy layer and the substrate, so that the alloy layer can be more stably covered on the surface of the substrate, reducing the risk of the alloy layer falling off, and further improving the coulombic efficiency and cycle life of the battery.

[0013] In some embodiments, the nucleation overpotential of lithium metal, which is a single substance of the first metal element, is 0.10V-0.50V, and can be optionally 0.10V-0.35V.

[0014] In some embodiments, the nucleation overpotential of lithium metal as a single substance of the second metal element is less than 0.10V, and can be optionally 0.030V-0.095V.

[0015] In some embodiments, the nucleation overpotential of lithium metal as a single substance of the third metal element is 0.10V-0.50V, and can be optionally 0.10V-0.35V.

[0016] In some embodiments, the nucleation overpotential of lithium metal of the单质 of the first metal element is denoted as V1, and the nucleation overpotential of lithium metal of the单质 of the second metal element is denoted as V2, where 0V < V1 - V2 ≤ 0.47V. Optionally, 0.05V ≤ V1 - V2 ≤ 0.30V.

[0017] In some embodiments, the nucleation overpotential of lithium metal of the单质 of the second metal element is denoted as V2, and the nucleation overpotential of lithium metal of the单质 of the third metal element is denoted as V3, where 0V < V3 - V2 ≤ 0.47V. Optionally, 0.05V ≤ V3 - V2 ≤ 0.30V.

[0018] In some embodiments, the weight content of the first metal element in the alloy layer is 50wt% - 90wt%, and the weight content of the second metal element is 10wt% - 50wt%. Optionally, the weight content of the first metal element in the alloy layer is 60wt% - 70wt%, and the weight content of the second metal element is 30wt% - 40wt%.

[0019] By adjusting the weight contents of the first metal element and the second metal element in the alloy layer within the above ranges, the synergistic effect of the first metal element and the second metal element can be better exerted, whereby the battery can have both high Coulomb efficiency, high reliability and long cycle life.

[0020] In some embodiments, the areal density of the alloy layer is 10g / m 2 - 30g / m 2 , optionally 15g / m 2 - 25g / m 2 .

[0021] By adjusting the areal density of the alloy layer within the above ranges, on the one hand, the role of the second metal in increasing active sites, reducing nucleation overpotential, reducing local nucleation and slowing down dendrite growth, as well as the framework role of the first metal element, can be better exerted, whereby the battery can have better cycling performance and reliability. On the other hand, the battery can also have high Coulomb efficiency taken into account. Because as the areal density of the alloy layer increases, the weight of the second metal in the alloy layer increases, which will irreversibly consume a part of the active ions.

[0022] In some embodiments, the ratio of the atomic radius of the first metal element to the atomic radius of the second metal element is (0.70 - 1.15):1, optionally (0.75 - 0.95):1.

[0023] Since the atomic radius of the second metal element is close to that of the first metal element, the inert skeleton formed by the first metal element can better maintain structural stability and reduce the risk of collapse, so that the alloy layer can be more stably covered on the surface of the substrate, which can further improve the coulombic efficiency, reliability and cycle life of the battery.

[0024] In some embodiments, the first metal element includes one or more of Fe, Ni, and Cu, and may be Cu.

[0025] In some embodiments, the second metal element includes one or more of Zn, Ag, Mg, Be, Ga, In, Ge, Sb, Sn, Pb, As, Te, and Bi, and may optionally include one or more of Zn, Ga, Ge, and Sb.

[0026] In some embodiments, the third metal element includes one or more of Fe, Ni, and Cu, and may be Cu.

[0027] In some embodiments, the substrate includes one or more of a metal foil, a metal foam substrate, a metal mesh substrate, and a composite substrate, the composite substrate includes a polymer material base layer and a metal layer formed on at least one side of the polymer material base layer, and the metal layer includes a third metal element.

[0028] In a second aspect, the present application provides a battery cell comprising the negative electrode current collector according to the first aspect of the present application.

[0029] In some embodiments, the battery cell includes at least one of a negative electrode-free lithium metal battery cell and a negative electrode-free sodium metal battery cell.

[0030] In a third aspect, the present application provides a battery comprising the battery cell according to the second aspect of the present application.

[0031] In a fourth aspect, the present application provides an electrical device comprising the battery according to the third aspect of the present application, wherein the battery is used to provide electrical energy.

[0032] 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

[0033] 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.

[0034] FIG1 is a schematic diagram of a battery cell provided by some embodiments of the present application.

[0035] FIG2 shows an exploded schematic diagram of a battery cell provided in some embodiments of the present application.

[0036] FIG3 shows a schematic diagram of a battery module provided in some embodiments of the present application.

[0037] FIG4 shows a schematic diagram of a battery pack provided in some embodiments of the present application.

[0038] FIG5 is an exploded schematic diagram of the battery pack shown in FIG4 .

[0039] FIG6 shows a schematic diagram of an electrical device provided in some embodiments of the present application.

[0040] In the accompanying drawings, the drawings are not necessarily drawn to scale.

[0041] The description of the accompanying figures is as follows: 1. battery pack; 2. upper box; 3. lower box; 4. battery module; 5. battery cell; 51. shell; 52. electrode assembly; 53. cover plate. DETAILED DESCRIPTION

[0042] Below, with appropriate reference to the accompanying drawings, the embodiments of the negative electrode current collector, battery cell, battery, and electrical device of the present application are described in detail. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0043] " 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In this application, the terms "plurality" and "multiple" refer to two or more.

[0048] 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.

[0049] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0055] 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.

[0056] The battery cell may also include an outer packaging that can be used to encapsulate the electrode assembly. The outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, steel shell, etc. The outer packaging can also be a soft shell, such as a bag-type soft shell. The soft shell can be made of plastic, such as one or more of polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] The battery cells provided in the embodiments of the present application may be metal battery cells, for example, may include at least one of a negative electrode-free lithium metal battery cell and a negative electrode-free sodium metal battery cell.

[0063] 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 formed. During initial charging, ions on the negative electrode gain electrons and deposit on the surface of the negative electrode current collector, forming metal. During discharge, the metal converts to ions and returns to the positive electrode, enabling cyclic charge and discharge. Compared to other battery cells, the absence of a negative electrode active material layer allows for higher energy density. The cell balance (CB) value of a negative electrode-free battery cell is typically very low. For example, in some embodiments, the CB value of a negative electrode-free battery cell can be less than or equal to 0.1. The CB value is the unit area capacity of the negative electrode divided by the unit area capacity of the positive electrode in the battery cell. Because negative electrode-free battery cells contain no or only a small amount of negative electrode active material, the unit area capacity of the negative electrode is relatively low, resulting in a very low CB value, typically less than or equal to 0.1.

[0064] An embodiment of the present application provides a negative electrode current collector.

[0065] The negative electrode current collector includes a substrate and an alloy layer located on at least one side of the substrate, the alloy layer includes a first metal element and a second metal element, the substrate includes a third metal element, the nucleation overpotential of the second metal element is less than the nucleation overpotential of the first metal element, the lithium metal nucleation overpotential of the first metal element is greater than or equal to 0.10V, and the nucleation overpotential of the second metal element is less than the nucleation overpotential of the third metal element.

[0066] Alkali metals such as lithium and sodium have poor wettability on conventional negative electrode current collectors, resulting in a high nucleation overpotential and insufficient nucleation sites. Lithium, sodium, and other alkali metals tend to preferentially nucleate at certain surface defects in conventional negative electrode current collectors. These preferential nucleation sites become advantageous growth points, leading to localized metal deposition and dendrite formation. Dendrites can affect battery reliability and cycle performance.

[0067] The embodiment of the present application sets an alloy layer on the substrate of the negative electrode current collector, and makes the alloy layer include a second metal element with a nucleation overpotential less than that of the substrate. Thus, when the battery is charged, the second metal element in the alloy layer can provide a large number of active sites, induce uniform metal deposition, and can also form an alloy with the deposited metal, thereby reducing the nucleation overpotential of the negative electrode current collector, reducing local nucleation, and slowing down dendrite growth. The alloy layer also includes a first metal element with a nucleation overpotential greater than or equal to 0.10V for lithium metal. Thus, the first metal element mainly plays the role of an inert skeleton in the alloy layer and hardly participates in the reaction. Thus, it can serve as a framework in the alloy layer to limit the volume expansion caused by the second metal element and the deposited metal forming an alloy when the battery is charged, thereby reducing the risk of the alloy layer falling off as a whole due to the volume expansion of the alloy layer, reducing the internal porosity of the battery, deteriorating the electrolyte wettability, and deteriorating the alkali metal deposition and stripping activity. Therefore, the negative electrode current collector provided by the embodiment of the present application can reduce the loss of active ions during the battery cycle and improve the battery's cycle stability, coulombic efficiency and reliability.

[0068] In addition, since the alloy layer includes both a second metal element with a nucleation overpotential less than that of the matrix and a first metal element with a nucleation overpotential greater than or equal to 0.10V for lithium metal, it can also reduce the loss of active ions during the first charge of the battery and improve the first coulombic efficiency of the battery.

[0069] Therefore, the negative electrode current collector provided in the embodiment of the present application can enable the battery to have high coulombic efficiency, high reliability and long cycle life.

[0070] In some embodiments, the first metal element and the third metal element may be the same.

[0071] When the first metal element and the third metal element are the same, the bonding force between the same materials is stronger, thereby further increasing the bonding force between the alloy layer and the substrate, so that the alloy layer can be more stably covered on the surface of the substrate, reducing the risk of the alloy layer falling off, and further improving the coulombic efficiency and cycle life of the battery.

[0072] In some embodiments, the nucleation overpotential of lithium metal as a single substance of the first metal element may be 0.10V-0.50V, and optionally 0.10V-0.35V.

[0073] In some embodiments, the nucleation overpotential of lithium metal as a single substance of the second metal element may be less than 0.10V, and may be optionally 0.030V-0.095V.

[0074] In some embodiments, the nucleation overpotential of lithium metal as a single substance of the third metal element may be greater than or equal to 0.10 V, and may be optionally 0.10 V to 0.50 V, and more optionally 0.10 V to 0.35 V.

[0075] The nucleation overpotential of the elemental form of the first metal element, the nucleation overpotential of the elemental form of the second metal element, and the nucleation overpotential of the elemental form of the third metal element can be prepared as follows: In a glove box protected by argon, using a lithium metal sheet as the counter electrode, a button cell is assembled with the sheet of the elemental form of the first (second or third) metal element. The electrolyte salt of the electrolyte is LiFSI with a concentration of 1 mol / L, and the solvent of the electrolyte uses a mixed solvent of ethylene glycol dimethyl ether (DME) and 1,1,2,2 - tetrafluoroethyl - 2,2,3,3 - tetrafluoropropyl ether (TTE) with a weight ratio of 1:1. The separator uses a PE film with a thickness of 12 μm.

[0076] At 25 °C, after the assembled button cell is left standing for 12 h, it is discharged at a constant current density of 1 mA / cm 2 to 1 mAh / cm 2 . At the beginning of the lithium metal deposition process, there will first be an obvious voltage drop, and then a flat voltage plateau. The difference (here representing the absolute value) between the voltage at the lowest point and the flat part of the voltage plateau is used as the nucleation overpotential of the lithium metal of the elemental form of the first (second or third) metal element.

[0077] It should be noted that the specific value of the nucleation overpotential of the lithium metal of the elemental form of the above - mentioned first (second or third) metal element is used to represent the physical and chemical properties of the first (second or third) metal element, as well as the affinity between the first (second or third) metal element and the deposited metal. It does not mean that the negative electrode current collector provided by the embodiments of the present application can only be used in a non - negative - electrode lithium metal battery monomer. The negative electrode current collector provided by the embodiments of the present application can also be used in a non - negative - electrode sodium metal battery monomer.

[0078] In some embodiments, the nucleation overpotential of the lithium metal of the elemental form of the first metal element is denoted as V1, the nucleation overpotential of the elemental form of the second metal element is denoted as V2, 0V < V1 - V2 ≤ 0.47V, and optionally, 0.05V ≤ V1 - V2 ≤ 0.30V.

[0079] In some embodiments, the nucleation overpotential of the elemental form of the second metal element is denoted as V2, the nucleation overpotential of the lithium metal of the elemental form of the third metal element is denoted as V3, 0V < V3 - V2 ≤ 0.47V, and optionally, 0.05V ≤ V3 - V2 ≤ 0.30V.

[0080] In some embodiments, the weight content of the first metal element in the alloy layer can be 50 wt% - 90 wt%, and the weight content of the second metal element can be 10 wt% - 50 wt%.

[0081] When the battery is charging and discharging, the first metal in the alloy layer mainly plays a framework role, and the second metal is mainly used to provide active sites, reduce nucleation overpotential, reduce local nucleation, and slow down dendrite growth. The second metal can also form an alloy with the deposited metal, which will cause a certain volume expansion of the alloy layer.

[0082] When the content of the first metal element in the alloy layer is low and the content of the second metal element is high, the framework of the first metal in the alloy layer may not be able to effectively limit the volume expansion caused by the second metal and the deposited metal forming an alloy. As a result, the alloy layer still has the risk of falling off during the long-term cycle charge and discharge of the battery. At the same time, due to the high volume expansion of the alloy layer as a whole, it will also lead to problems such as reduced internal porosity, poor electrolyte wettability, and poor alkali metal deposition and stripping activity. In addition, when the content of the second metal element is high, some active ions will be irreversibly consumed. Therefore, when the content of the first metal element in the alloy layer is low and the content of the second metal element is high, the battery's cycle stability, coulombic efficiency, and reliability will be reduced.

[0083] When the content of the first metal element in the alloy layer is high and the content of the second metal element is low, the second metal in the alloy layer can provide fewer active sites, thereby failing to effectively reduce local nucleation and slow dendrite growth. Therefore, when the content of the first metal element in the alloy layer is high and the content of the second metal element is low, the battery's cycling stability, coulombic efficiency, and reliability will also be reduced.

[0084] By adjusting the weight content of the first metal element and the second metal element in the alloy layer within the above range, the synergistic effect of the first metal element and the second metal element can be better exerted, thereby enabling the battery to have high coulombic efficiency, high reliability and long cycle life.

[0085] Optionally, the weight content of the first metal element in the alloy layer may be 60 wt%-70 wt%, and the weight content of the second metal element may be 30 wt%-40 wt%, thereby further improving the coulombic efficiency, reliability and cycle life of the battery.

[0086] In some embodiments, the surface density of the alloy layer can be 10 g / m 2 -30g / m 2 , optional 15g / m 2 -25g / m 2 .

[0087] By adjusting the surface density of the alloy layer within the above range, the second metal can better play its role in increasing active sites, reducing nucleation overpotential, reducing localized nucleation, and slowing dendrite growth, as well as the framework effect of the first metal element, thereby improving the battery's cycle performance and reliability. On the other hand, it can also achieve high coulombic efficiency. As the surface density of the alloy layer increases, the weight of the second metal in the alloy layer increases, which will irreversibly consume some active ions.

[0088] In some embodiments, the ratio of the atomic radius of the first metal element to the atomic radius of the second metal element may be (0.70-1.15):1, and may optionally be (0.75-0.95):1.

[0089] The second metal element in the alloy layer can provide active sites, allowing the alkali metal to be deposited evenly, thereby reducing local nucleation and slowing dendrite growth. The second metal element is also evenly distributed within the inert skeleton formed by the first metal element. Therefore, when the second metal element reacts with the deposited metal, since the atomic radius of the second metal element is close to that of the first metal element, the inert skeleton formed by the first metal element can better maintain structural stability and reduce the risk of collapse, thereby allowing the alloy layer to be more stably covered on the substrate surface, which can further improve the coulombic efficiency, reliability and cycle life of the battery.

[0090] In some embodiments, the first metal element may include one or more of Fe, Ni, and Cu, and may be Cu.

[0091] In some embodiments, the second metal element may include one or more of Zn, Ag, Mg, Be, Ga, In, Ge, Sb, Sn, Pb, As, Te, and Bi, and may optionally include one or more of Zn, Ga, Ge, and Sb.

[0092] In some embodiments, the third metal element may include one or more of Fe, Ni, and Cu, and may be Cu.

[0093] In some embodiments, the first metal element and the third metal element may both be Cu.

[0094] In some embodiments, the alloy layer can be deposited on the substrate surface by magnetron sputtering, chemical plating, electroplating, or spraying. Alternatively, the alloy layer can be deposited on the substrate surface by magnetron sputtering. Compared to other methods, magnetron sputtering is simpler, faster, and more convenient to operate. Furthermore, the alloy layer formed by magnetron sputtering has a stronger bond with the substrate and better stability.

[0095] In some embodiments, the substrate may include one or more of a metal foil, a metal foam substrate, a metal mesh substrate, and a composite substrate.

[0096] The composite matrix may include a polymer material base layer and a metal layer formed on at least one side of the polymer material base layer, wherein the metal layer includes a third metal element.

[0097] Optionally, the substrate may include copper foil, nickel foil, and more preferably copper foil.

[0098] [Positive electrode]

[0099] The battery cell includes a positive electrode plate.

[0100] 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.

[0101] In some embodiments, the positive electrode active material includes a material capable of extracting and inserting lithium.

[0102] 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.

[0103] 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 fOne 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.

[0104] 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.

[0105] As an example, the positive electrode active material may include but is not limited to LiCoO2, LiNiO2, LiMnO2, LiNi 1 / 2 Mn 1 / 2 O2、LiMn2O4、Li 4 / 3 Ti 5 / 3 O4、LiNi 1 / 2 Mn 1 / 2 O2、LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333),LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622),LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.80 Co 0.15 Al 0.05 O2, LiFePO4, LiMnPO4, Li 1.13 Ti 0.57 Fe 0.3 One or more of S2.

[0106] The battery cells are accompanied by Li intercalation and deintercalation and consumption during the charge and discharge process. The molar content of Li in the battery cells varies when discharged to different states. The molar content of Li in the list of positive electrode active materials in this application refers to the initial state of the material, that is, the state before the material is added. The molar content of Li will change after the positive electrode active material is applied to the battery cells and the charge and discharge cycles. The molar content of O in the list of positive electrode active materials in this application is only a theoretical state value. Lattice oxygen release will cause the molar content of O to change, and the actual molar content of O will also fluctuate.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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).

[0112] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0113] 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).

[0114] [Electrolytes]

[0115] The battery cells include an electrolyte.

[0116] In some embodiments, the electrolyte is an electrolyte solution including an electrolyte salt and an organic solvent.

[0117] 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 - )

[0118] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0119] 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.

[0120] 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.

[0121] 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 (MPC), P), 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), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), 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 One or more of trifluoromethyl hexafluorooctyl methyl ether, 7-trifluoromethyl hexafluorooctyl ethyl ether and 7-trifluoromethyl hexafluorooctyl propyl ether.

[0122] 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.

[0123] [Isolation film]

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] Example

[0133] 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.

[0134] Performance Testing

[0135] (1) Coulomb efficiency test

[0136] In an argon-protected glove box, button-type cells were assembled using a lithium metal sheet as the counter electrode and the negative electrode current collectors prepared in each example and comparative example. The electrolyte salt was LiFSI at a concentration of 1 mol / L, and the solvent was a mixture of ethylene glycol dimethyl ether (DME) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) in a 1:1 weight ratio. A 12 μm thick PE film was used as the separator.

[0137] 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 constant current cycle charge and discharge was carried out at a current density of 1000 nm until the discharge capacity after the cycle decayed to 90% of the discharge capacity in the first cycle, and the test was stopped.

[0138] The first coulombic efficiency of a button cell = first cycle charge capacity / first cycle discharge capacity × 100%.

[0139] The average coulombic efficiency of a button cell is the average of the coulombic efficiencies per cycle.

[0140] During the test, the number of button battery samples can be more than 6, and the test results are averaged.

[0141] (2) Cyclic performance test

[0142] 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 95:1.7:3.3 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.

[0143] In an argon-protected glove box, the positive electrode sheet and the negative electrode current collectors prepared in each example and comparative example were assembled into a button-type battery. The electrolyte salt was LiFSI at a concentration of 1 mol / L, and the electrolyte solvent was a mixed solvent of ethylene glycol dimethyl ether (DME) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) in a weight ratio of 1:1. The separator was a 12 μm thick PE film.

[0144] 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 0.1C. After the button cell was allowed to rest for 10 minutes, it was discharged at a constant current of 1C to 2.5V. The button cell was cycled according to the above method until the discharge capacity after the cycle reached 50% of the discharge capacity of the first cycle. The number of cycles was recorded.

[0145] During the test, the number of button battery samples can be more than 6, and the test results are averaged.

[0146] Example 1

[0147] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0148] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Zn-Cu alloy target with a weight ratio of Zn to Cu of 40:60. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0149] Example 2

[0150] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0151] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Zn-Ni alloy target with a weight ratio of Zn to Ni of 40:60. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0152] Comparative Example 1

[0153] Commercially available two-dimensional copper foil with a thickness of 35 μm was purchased as the negative electrode current collector.

[0154] Comparative Example 2

[0155] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0156] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain the negative electrode current collector. The target material is a pure Zn target. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa, and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0157] Table 1

[0158] It can be seen from the test results of Example 1, Example 2 and Comparative Example 1 that by providing an alloy layer on the base copper foil, the average coulombic efficiency and cycle life of the battery can be improved, the short-circuit time can be extended, and the reliability of the battery can be improved.

[0159] The test results of Comparative Example 2 show that when a lithiophilic layer composed of a second metal is provided on the substrate surface, the battery's initial coulombic efficiency is significantly reduced. Furthermore, the improvements in battery reliability and cycle life are less than excellent compared to Comparative Example 1. This is because the second metal element irreversibly consumes a portion of the active ions when forming an alloy with the deposited lithium, resulting in a significant reduction in the battery's initial coulombic efficiency compared to Comparative Example 1. Furthermore, due to the lack of the framework effect of the first metal element of the present application in the lithiophilic layer, the volume expansion caused by the alloying of the second metal element with the deposited lithium cannot be suppressed. Excessive volume expansion can cause the lithiophilic layer to become unstable and easily fall off during long-term battery cycling. Furthermore, the large volume expansion of the lithiophilic layer can also lead to problems such as reduced internal porosity, poor electrolyte wettability, and poor alkali metal deposition and stripping activity.

[0160] The test results of Examples 1 and 2 also show that when the first metal element in the alloy layer is made of the same material as the substrate, the battery can achieve higher average coulombic efficiency, longer short-circuit time, and longer cycle life. This is because the bonding between the same materials is stronger, and the bonding between the alloy layer and the substrate is higher, which allows the alloy layer to cover the substrate surface more stably and reduces the risk of the alloy layer falling off.

[0161] Example 3

[0162] Purchase commercially available two-dimensional nickel foil with a thickness of 35 μm.

[0163] The nickel foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Zn-Ni alloy target with a weight ratio of Zn to Ni of 40:60. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0164] Example 4

[0165] Purchase commercially available two-dimensional nickel foil with a thickness of 35 μm.

[0166] The nickel foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Zn-Cu alloy target with a weight ratio of Zn to Cu of 40:60. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0167] Comparative Example 3

[0168] Commercially available two-dimensional nickel foil with a thickness of 35 μm was purchased as the negative electrode current collector.

[0169] Comparative Example 4

[0170] Purchase commercially available two-dimensional nickel foil with a thickness of 35 μm.

[0171] The nickel foil was placed in an ion sputtering instrument and an alloy layer was formed by vacuum magnetron sputtering to obtain the negative electrode current collector. The target material was a pure Zn target. The upper limit of the vacuum pressure of the ion sputtering instrument was set to 1.0 MPa and the sputtering current was 30 mA. After the sputtering started, the surface density of the alloy layer could be adjusted by controlling the sputtering time. The surface density of the alloy layer was 20 g / m 2 .

[0172] Table 2

[0173] It can be seen from the test results of Example 3, Example 4 and Comparative Example 3 that by providing an alloy layer on the base nickel foil, the average coulombic efficiency and cycle life of the battery can be improved, the short-circuit time can be extended, and the reliability of the battery can be improved.

[0174] The test results of Comparative Example 4 show that when a lithiophilic layer composed of a second metal is provided on the substrate surface, the battery's initial coulombic efficiency is significantly reduced, and the improvements in battery reliability and cycle life are less than excellent compared to Comparative Example 3. This is because the second metal element irreversibly consumes a portion of the active ions when forming an alloy with the deposited lithium, resulting in a significant reduction in the battery's initial coulombic efficiency compared to Comparative Example 3. Furthermore, due to the lack of the framework effect of the first metal element of the present application in the lithiophilic layer, the volume expansion caused by the alloying of the second metal element with the deposited lithium cannot be suppressed. Excessive volume expansion can cause the lithiophilic layer to be unstable and easily fall off during long-term battery cycling. Furthermore, the large volume expansion of the lithiophilic layer can also lead to problems such as reduced internal porosity, poor electrolyte wettability, and poor alkali metal deposition and stripping activity.

[0175] The test results of Examples 3 and 4 also show that when the first metal element in the alloy layer is made of the same material as the substrate, the battery can achieve higher average coulombic efficiency, longer short-circuit time, and longer cycle life. This is because the bonding between the same materials is stronger, and the bonding between the alloy layer and the substrate is higher, which allows the alloy layer to cover the substrate surface more stably and reduces the risk of the alloy layer falling off.

[0176] It can also be seen from the test results of Example 1 and Example 3 that when the matrix includes the Cu element, the battery can have a higher average coulombic efficiency, a longer short-circuit time and a longer cycle life.

[0177] Example 5

[0178] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0179] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Sn-Cu alloy target with a weight ratio of Sn to Cu of 40:60. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0180] Example 6

[0181] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0182] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Ga-Cu alloy target with a weight ratio of Ga to Cu of 40:60. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0183] Example 7

[0184] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0185] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Ge-Cu alloy target with a weight ratio of Ge to Cu of 40:60. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0186] Example 8

[0187] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0188] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Sb-Cu alloy target with a weight ratio of Sb to Cu of 40:60. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0189] Table 3

[0190] From the test results of Examples 1, 5 to 8, it can be seen that different types of the second metal element have different effects on improving battery performance.

[0191] Example 9

[0192] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0193] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Zn-Cu alloy target with a weight ratio of Zn to Cu of 10:90. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0194] Example 10

[0195] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0196] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Zn-Cu alloy target with a weight ratio of Zn to Cu of 20:80. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0197] Example 11

[0198] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0199] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Zn-Cu alloy target with a weight ratio of Zn to Cu of 30:70. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0200] Example 12

[0201] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0202] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Zn-Cu alloy target with a weight ratio of Zn and Cu of 50:50. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0203] Example 13

[0204] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0205] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Zn-Cu alloy target with a weight ratio of Zn to Cu of 60:40. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0206] Example 14

[0207] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0208] The copper foil is placed in an ion sputtering instrument and an alloy layer is formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target material is a Zn-Cu alloy target with a weight ratio of Zn to Cu of 5:95. The upper limit of the vacuum pressure of the ion sputtering instrument is set to 1.0 MPa and the sputtering current is 30 mA. After the sputtering starts, the surface density of the alloy layer can be adjusted by controlling the sputtering time. The surface density of the alloy layer is 20 g / m 2 .

[0209] Table 4

[0210] It can also be seen from the test results of Examples 1, 9 to 14 that when the surface density of the alloy layer is the same, by further adjusting the weight ratio of the first metal element to the second metal element in the alloy layer, the synergistic effect of the first metal element and the second metal element can be better exerted, thereby enabling the battery to have a higher average coulombic efficiency, a longer short-circuit time and a longer cycle life.

[0211] Example 15

[0212] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the surface density of the alloy layer is adjusted to 5 g / m 2 .

[0213] Example 16

[0214] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the surface density of the alloy layer is adjusted to 10 g / m 2 .

[0215] Example 17

[0216] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the surface density of the alloy layer is adjusted to 15 g / m 2 .

[0217] Example 18

[0218] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the surface density of the alloy layer is adjusted to 25 g / m 2 .

[0219] Example 19

[0220] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the surface density of the alloy layer is adjusted to 30 g / m 2.

[0221] Example 20

[0222] The preparation method of the negative electrode current collector is similar to that of Example 1, except that the surface density of the alloy layer is adjusted to 35 g / m by adjusting the sputtering time. 2 .

[0223] Table 5

[0224] It can also be seen from the test results of Examples 1, 15 to 20 that when the elements and proportions of the alloy layer are the same, by further adjusting the surface density of the alloy layer, the battery can have a higher average coulombic efficiency, a longer short-circuit time and a longer cycle life.

[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 any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A negative electrode current collector, comprising a substrate and an alloy layer located on at least one side of the substrate, wherein, the alloy layer comprises a first metal element and a second metal element, and the substrate comprises a third metal element, the nucleation overpotential of the second metal element in its elemental form is less than that of the first metal element in its elemental form, the nucleation overpotential of the first metal element in its elemental form with respect to lithium metal is greater than or equal to 0.10 V, the nucleation overpotential of the second metal element in its elemental form is less than that of the third metal element in its elemental form.

2. The negative electrode current collector according to claim 1, wherein The first metal element is the same as the third metal element.

3. The negative electrode current collector according to any one of claims 1-2, wherein, The nucleation overpotential of the first metal element in its elemental form with respect to lithium metal is 0.10 V - 0.50 V, and optionally 0.10 V - 0.35 V.

4. The negative electrode current collector according to any one of claims 1 - 3, wherein, the nucleation overpotential of the second metal element in its elemental form with respect to lithium metal is less than 0.10 V, and optionally 0.030 V - 0.095 V; and / or, the nucleation overpotential of the third metal element in its elemental form with respect to lithium metal is 0.10 V - 0.50 V, and optionally 0.10 V - 0.35 V.

5. The negative electrode current collector according to any one of claims 1-4, wherein, The nucleation overpotential of the first metal element in its elemental form with respect to lithium metal is denoted as V1, the nucleation overpotential of the second metal element in its elemental form with respect to lithium metal is denoted as V2, and the nucleation overpotential of the third metal element in its elemental form with respect to lithium metal is denoted as V3, 0 V < V1 - V2 ≤ 0.47 V, optionally, 0.05 V ≤ V1 - V2 ≤ 0.30 V; and / or, 0 V < V3 - V2 ≤ 0.47 V, optionally, 0.05 V ≤ V3 - V2 ≤ 0.30 V.

6. The negative electrode current collector according to any one of claims 1 - 5, wherein, the weight content of the first metal element in the alloy layer is 50 wt% - 90 wt%, and the weight content of the second metal element is 10 wt% - 50 wt%, optionally, the weight content of the first metal element in the alloy layer is 60 wt% - 70 wt%, and the weight content of the second metal element is 30 wt% - 40 wt%.

7. The negative electrode current collector according to any one of claims 1-6, wherein, The areal density of the alloy layer is 10 g / m 2 -30 g / m 2 , and can be optionally 15 g / m 2 -25 g / m 2 .

8. The negative electrode current collector according to any one of claims 1-7, wherein, The ratio of the atomic radius of the first metal element to the atomic radius of the second metal element is (0.70 - 1.15):1, and optionally (0.75 - 0.95):

1.

9. The negative electrode current collector according to any one of claims 1 - 8, wherein, the first metal element comprises one or more of Fe, Ni, Cu, and optionally Cu; and / or, the second metal element comprises one or more of Zn, Ag, Mg, Be, Ga, In, Ge, Sb, Sn, Pb, As, Te, Bi, and optionally comprises one or more of Zn, Ga, Ge, Sb; and / or, the third metal element comprises one or more of Fe, Ni, Cu, and optionally Cu.

10. The negative electrode current collector according to any one of claims 1-9, wherein, The substrate comprises one or more of a metal foil, a metal foam substrate, a metal mesh substrate, a composite substrate, and the composite substrate comprises a polymer material base layer and a metal layer formed on at least one side of the polymer material base layer, and the metal layer comprises a third metal element.

11. A battery cell, comprising a negative current collector according to any one of claims 1-10.

12. The battery cell according to claim 11, wherein, The battery cell includes at least one of a lithium metal battery cell without a negative electrode and a sodium metal battery cell without a negative electrode.

13. A battery, comprising a battery cell according to any one of claims 11-12.

14. An electrical device, comprising the battery according to claim 13, wherein the battery is used to provide electrical energy.

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