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

Abstract

The invention discloses a negative electrode current collector, a battery monomer, a battery and a power utilization 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, and the substrate comprises a third metal element, the nucleation overpotential of the elementary substance of the second metal element is smaller than the nucleation overpotential of the elementary substance of the first metal element, the nucleation overpotential of the lithium metal of the elementary substance of the first metal element is larger than or equal to 0.10 V, and the nucleation overpotential of the elementary substance of the second metal element is smaller than the nucleation overpotential of the elementary substance of the third metal element. According to the invention, the battery has high coulombic efficiency, high reliability and long cycle life.

Description

Technical Field

[0001] The present application relates to a negative current collector, a battery cell, a battery and an electrical device. Background Art

[0002] Compared with ionic batteries, metal batteries can have a higher energy density. However, different from the negative electrodes of ionic batteries, there is an uneven deposition problem in the negative electrodes of metal batteries. Setting a coating with better affinity for the deposited metal on the surface of the negative current collector of the metal battery helps to regulate the deposition behavior of the deposited metal. However, the currently set coating has the problem of easy peeling off during the long-term cycling of the battery, thereby affecting the reliability and electrochemical performance of the metal battery. Summary of the Invention

[0003] The present application provides a negative current collector, a battery cell, a battery and an electrical device, which can enable the battery to have a high Coulomb efficiency, high reliability and a long cycle life.

[0004] In a first aspect, the present application provides a negative current collector, including 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 simple substance of the second metal element is less than the nucleation overpotential of the simple substance of the first metal element, the nucleation overpotential of the simple substance of the first metal element with respect to lithium metal is greater than or equal to 0.10 V, and the nucleation overpotential of the simple substance of the second metal element is less than the nucleation overpotential of the simple substance of the third metal element.

[0005] In the embodiment of the present application, by setting an alloy layer on the substrate of the negative current collector and making the alloy layer include a second metal element with a nucleation overpotential less than that of the substrate, when the battery is charged, the second metal element in the alloy layer can provide a large number of active sites, induce uniform deposition of the metal, and can also form an alloy with the deposited metal, thereby reducing the nucleation overpotential of the negative 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 0.10 V with respect to 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, thereby serving as a framework in the alloy layer to limit the volume expansion caused by the formation of an alloy between the second metal element and the deposited metal during battery charging, and further reducing the risks such as the overall peeling off of the alloy layer, the reduction of the internal porosity of the battery, the deterioration of the electrolyte wettability, and the deterioration of the alkali metal deposition stripping activity due to the volume expansion of the alloy layer. Therefore, the negative current collector provided by the embodiment of the present application can reduce the loss of active ions during the battery cycling process, and improve the cycling stability, Coulomb efficiency and reliability of the battery.

[0006] In addition, since the alloy layer includes both a second metal element with a nucleation overpotential less than that of the substrate and a first metal element with a nucleation overpotential for lithium metal greater than or equal to 0.10 V, the loss of active ions during the first charge of the battery can also be reduced, thereby improving the first Coulombic efficiency of the battery.

[0007] Therefore, the negative electrode current collector provided by the embodiments of the present application can enable the battery to have high Coulombic efficiency, high reliability, and long cycle life.

[0008] In some embodiments, the first metal element is the same as the third metal element.

[0009] When the first metal element is the same as the third metal element, since the bonding force between the same materials is stronger, the bonding force between the alloy layer and the substrate can be further increased, enabling the alloy layer to cover the surface of the substrate more stably, reducing the risk of the alloy layer peeling off, and further improving the Coulombic efficiency and cycle life of the battery.

[0010] In some embodiments, the nucleation overpotential of the first metal element in its elemental form for lithium metal is 0.10 V - 0.50 V, and optionally 0.10 V - 0.35 V.

[0011] In some embodiments, the nucleation overpotential of the second metal element in its elemental form for lithium metal is less than 0.10 V, and optionally 0.030 V - 0.095 V.

[0012] In some embodiments, the nucleation overpotential of the third metal element in its elemental form for lithium metal is 0.10 V - 0.50 V, and optionally 0.10 V - 0.35 V.

[0013] In some embodiments, the nucleation overpotential of the first metal element in its elemental form for lithium metal is denoted as V1, the nucleation overpotential of the second metal element in its elemental form for lithium metal is denoted as V2, 0 V < V1 - V2 ≤ 0.47 V, and optionally, 0.05 V ≤ V1 - V2 ≤ 0.30 V.

[0014] In some embodiments, the nucleation overpotential of the second metal element in its elemental form for lithium metal is denoted as V2, the nucleation overpotential of the third metal element in its elemental form for lithium metal is denoted as V3, 0 V < V3 - V2 ≤ 0.47 V, and optionally, 0.05 V ≤ V3 - V2 ≤ 0.30 V.

[0015] In some embodiments, 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%.

[0016] 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.

[0017] In some embodiments, the areal density of the alloy layer is 10 g / m 2 -30 g / m 2 , optionally 15 g / m 2 -25 g / m 2 .

[0018] 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 the 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 take into account high Coulomb efficiency. Because 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.

[0019] 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.

[0020] 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 cover the surface of the substrate more stably, and further improve the Coulomb efficiency, reliability and cycle life of the battery.

[0021] In some embodiments, the first metal element includes one or more of Fe, Ni, Cu, and is optionally Cu.

[0022] In some embodiments, the second metal element includes one or more of Zn, Ag, Mg, Be, Ga, In, Ge, Sb, Sn, Pb, As, Te, Bi, and is optionally one or more of Zn, Ga, Ge, Sb.

[0023] In some embodiments, the third metal element includes one or more of Fe, Ni, Cu, and is optionally Cu.

[0024] 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.

[0025] In a second aspect, the present application provides a battery cell, which includes the negative electrode current collector of the first aspect of the present application.

[0026] In some embodiments, 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.

[0027] In a third aspect, the present application provides a battery, which includes the battery cell of the second aspect of the present application.

[0028] In a fourth aspect, the present application provides an electrical device, which includes the battery of the third aspect of the present application, and the battery is used to provide electrical energy.

[0029] The electrical 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

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and those of ordinary skill in the art can also obtain other drawings according to the drawings without creative efforts.

[0031] Figure 1 A schematic diagram showing a battery cell provided by some embodiments of the present application.

[0032] Figure 2 An exploded schematic diagram showing a battery cell provided by some embodiments of the present application.

[0033] Figure 3 A schematic diagram showing a battery module provided by some embodiments of the present application.

[0034] Figure 4 A schematic diagram showing a battery pack provided by some embodiments of the present application.

[0035] Figure 5 is Figure 4 An exploded schematic diagram of the battery pack shown.

[0036] Figure 6 A schematic diagram showing an electrical device provided by some embodiments of the present application.

[0037] In the drawings, the drawings are not necessarily drawn to actual scale.

[0038] Explanation of reference numerals: 1. Battery pack; 2. Upper box body; 3. Lower box body; 4. Battery module; 5. Battery cell; 51. Housing; 52. Electrode assembly; 53. Cover plate. Specific embodiments

[0039] Hereinafter, embodiments of the negative electrode current collector, battery cell, battery, and electrical device of the present application will be specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary details are omitted. For example, there are cases where details of well-known matters are omitted and repeated descriptions of actually identical structures 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 accompanying 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 recited in the claims.

[0040] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] If there is no special instruction, 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 content of the present application.

[0042] If there is no special instruction, all technical features and optional technical features 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 content of the present application.

[0043] Unless otherwise specified, all steps of the present application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method can include steps (a) and (b) carried out sequentially, or steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), indicating that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0044] In the present application, the terms "a plurality of" and "a variety of" refer to two or more than two.

[0045] In the description of the embodiments of the present application, unless otherwise specified, the first feature being "on" or "under" the second feature may mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0046] Unless otherwise specified, the terms used in the present application have the well-known meanings commonly understood by those skilled in the art.

[0047] Unless otherwise specified, the numerical values of the various parameters mentioned in the present application can be measured by various commonly used testing methods in the art. For example, they can be measured according to the testing methods given in the embodiments of the present application. Unless otherwise specified, the test temperature for each parameter is 25°C.

[0048] The battery mentioned in the embodiments of the present application can be a single physical module including one or more battery cells to provide a higher voltage and capacity. For example, the battery mentioned in the present application can include battery cells, battery modules, battery packs, etc.

[0049] A battery cell is the smallest unit that makes up a battery and can independently perform the functions of charging and discharging. The battery cell can be in the shape of a cylinder, a cuboid or other shapes, etc., and the embodiments of the present application do not limit this. As Figure 1 is a battery cell 5 with a cuboid structure as an example.

[0050] When there are multiple battery cells, the multiple battery cells are connected in series, parallel or in a hybrid connection through a busbar component. 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 box body and battery cells, and the battery cells or battery modules are accommodated in the box body. In some embodiments, the box body may be part of the chassis structure of a vehicle. For example, part of the box body may form at least part of the vehicle floor, or part of the box body may form at least part of the cross beams and longitudinal beams of the vehicle.

[0051] In some embodiments, the battery may be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0052] The battery cell includes an electrode assembly. The electrode assembly may be a wound structure or a stacked structure, and the embodiments of the present application do not limit this.

[0053] The battery cell may further include an outer package, and the outer package can 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).

[0054] In some embodiments, as Figure 2 shown, the outer package 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, and the bottom plate and the side plates enclose 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 to close the receiving cavity. The electrode assembly 52 is encapsulated in the receiving cavity. The number of electrode assemblies 52 included in the battery cell 5 may be one or more, which can be adjusted according to requirements.

[0055] In some embodiments, the battery cells can be assembled into a battery module, and the number of battery cells included in the 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 Figure 3 shown, in the battery module 4, multiple battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other way. Further, the multiple battery cells 5 can be fixed by fasteners.

[0056] Optionally, the battery module 4 may further include a housing having a receiving space, and the multiple battery cells 5 are accommodated in the receiving space.

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

[0058] Figure 4 and Figure 5 is a schematic diagram of a battery pack 1 as an example. As Figure 4 and Figure 5 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. 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 can be arranged in the box body in any manner.

[0059] The battery cell provided by the embodiment of the present application can be a metal battery cell, for example, it can include at least one of a lithium metal battery cell without a negative electrode and a sodium metal battery cell without a negative electrode.

[0060] A battery cell without a negative electrode generally refers to a battery cell that does not actively provide a negative electrode active material layer on the negative electrode side during the manufacturing process of the battery cell. For example, during the manufacturing process of the battery cell, a layer is not provided 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, 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 battery cell without a negative electrode can obtain a higher energy density because it does not have a negative electrode active material layer. 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 can be less than or equal to 0.1. The CB value is the unit area capacity of the negative electrode in the battery cell divided by the unit area capacity of the positive electrode. Since a battery cell without a negative electrode does not contain or only contains 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.

[0061] The embodiment of the present application provides a negative electrode current collector.

[0062] 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 in its elemental form is less than the nucleation overpotential of the first metal element in its elemental form. The lithium metal nucleation overpotential of the first metal element in its elemental form is greater than or equal to 0.10V, and the nucleation overpotential of the second metal element in its elemental form is less than the nucleation overpotential of the third metal element in its elemental form.

[0063] Alkali metals such as lithium and sodium have poor wettability on conventional negative electrode current collectors, resulting in a large nucleation overpotential and insufficient nucleation sites on conventional negative electrode current collectors. Alkali metals such as lithium and sodium are prone to preferential nucleation at certain surface defect positions of conventional negative electrode current collectors, and the positions of preferential nucleation will form dominant growth points, leading to local metal deposition and dendrite formation. Dendrites will affect the reliability of the battery and also affect the cycle performance of the battery.

[0064] In the embodiments of the present application, an alloy layer is provided on the substrate of the negative electrode current collector, and the alloy layer includes a second metal element with a nucleation overpotential smaller 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 deposition of the metal, 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 further includes a first metal element with a nucleation overpotential for lithium metal greater than or equal to 0.10 V. Thus, the first metal element mainly plays the role of an inert skeleton in the alloy layer and hardly participates in the reaction, thereby serving as a framework in the alloy layer to limit the volume expansion caused by the formation of an alloy between the second metal element and the deposited metal during battery charging, and further reducing the risks such as the overall peeling off of the alloy layer, the reduction of the internal porosity of the battery, the deterioration of the electrolyte wettability, and the deterioration of the alkali metal deposition stripping activity due to the volume expansion of the alloy layer. Therefore, the negative electrode current collector provided by the embodiments of the present application can reduce the loss of active ions during the battery cycle process, and improve the cycle stability, Coulomb efficiency, and reliability of the battery.

[0065] In addition, since the alloy layer includes both a second metal element with a nucleation overpotential smaller than that of the substrate and a first metal element with a nucleation overpotential for lithium metal greater than or equal to 0.10 V, the loss of active ions during the first charge of the battery can also be reduced, and the first Coulomb efficiency of the battery can be improved.

[0066] Therefore, the negative electrode current collector provided by the embodiments of the present application can enable the battery to have high Coulomb efficiency, high reliability, and long cycle life.

[0067] In some embodiments, the first metal element and the third metal element may be the same.

[0068] When the first metal element and the third metal element are the same, since the bonding force between the same materials is stronger, the bonding force between the alloy layer and the substrate can be further increased, enabling the alloy layer to cover the surface of the substrate more stably and reducing the risk of the alloy layer peeling off. It can also further improve the Coulomb efficiency and cycle life of the battery.

[0069] In some embodiments, the nucleation overpotential of the simple substance of the first metal element for lithium metal may be 0.10 V - 0.50 V, and may be optionally 0.10 V - 0.35 V.

[0070] In some embodiments, the nucleation overpotential of the lithium metal of the second metal element in its elemental form can be less than 0.10 V, and can be optionally 0.030 V - 0.095 V.

[0071] In some embodiments, the nucleation overpotential of the lithium metal of the third metal element in its elemental form can be greater than or equal to 0.10 V, and can be optionally 0.10 V - 0.50 V, and more optionally 0.10 V - 0.35 V.

[0072] The nucleation overpotentials of the lithium metal of the elemental forms of the first, second, and third metal elements can be prepared by the following method: In a glove box under argon protection, using a lithium metal sheet as the counter electrode, assemble a button cell with the sheet of the metal corresponding to 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 membrane with a thickness of 12 μm.

[0073] At 25 °C, after the assembled button cell is left standing for 12 h, discharge it 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. Use the difference (here representing the absolute value) between the voltage at the lowest point and the flat part of the voltage plateau as the nucleation overpotential of the lithium metal of the elemental form of the first (second or third) metal element.

[0074] It should be noted that the specific values of the nucleation overpotentials of the lithium metal of the elemental forms of the above - mentioned first (second or third) metal elements are 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 current collector provided by the embodiments of the present application can only be used in the non - negative lithium metal battery monomer. The negative current collector provided by the embodiments of the present application can also be used in the non - negative sodium metal battery monomer.

[0075] 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, 0 V < V1 - V2 ≤ 0.47 V, and optionally, 0.05 V ≤ V1 - V2 ≤ 0.30 V.

[0076] 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, 0 V < V3 - V2 ≤ 0.47 V, and optionally, 0.05 V ≤ V3 - V2 ≤ 0.30 V.

[0077] In some embodiments, the weight content of the first metal element in the alloy layer may be 50 wt% - 90 wt%, and the weight content of the second metal element may be 10 wt% - 50 wt%.

[0078] During battery 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 the 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.

[0079] 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 role of the first metal in the alloy layer may not be able to well limit the volume expansion caused by the alloy formation of the second metal and the deposited metal. Therefore, during the long-term cyclic charging and discharging process of the battery, there is still a risk of shedding of the alloy layer; at the same time, due to the still relatively high volume expansion of the alloy layer as a whole, this will also lead to problems such as a decrease in the internal porosity of the battery, poor electrolyte wettability, and poor activity of alkali metal deposition and stripping; in addition, when the content of the second metal element is high, it will irreversibly consume a part of the active ions. 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 cycle stability, Coulomb efficiency, and reliability of the battery will decrease.

[0080] 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, so it cannot well play the role of reducing local nucleation and slowing down 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 cycle stability, Coulomb efficiency, and reliability of the battery will also decrease.

[0081] 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, and thus the battery can have high Coulomb efficiency, high reliability, and long cycle life.

[0082] 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%. This can further improve the Coulomb efficiency, reliability, and cycle life of the battery.

[0083] In some embodiments, the areal density of the alloy layer may be 10 g / m 2 - 30 g / m 2 , and may be optionally 15 g / m 2 - 25 g / m 2 .

[0084] By adjusting the areal density of the alloy layer within the above range, 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 can be better exerted, as well as the framework role of the first metal element. Thus, the battery can have better cycling performance and reliability. On the other hand, the battery can also achieve high Coulomb efficiency. Because 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.

[0085] In some embodiments, the ratio of the atomic radius of the first metal element to the atomic radius of the second metal element can be (0.70 - 1.15):1, and can be optionally (0.75 - 0.95):1.

[0086] The second metal element in the alloy layer can provide active sites to enable uniform deposition of alkali metals. Thus, local nucleation can be reduced, dendrite growth can be slowed down, and the second metal element will be uniformly distributed within the inert framework formed by the first metal element. Therefore, when the second metal element reacts with the deposited metal, due to the atomic radius of the second metal element being close to that of the first metal element, the inert framework formed by the first metal element can better maintain structural stability and reduce the risk of collapse. Thus, the alloy layer can more stably cover the surface of the substrate, and further improve the Coulomb efficiency, reliability, and cycle life of the battery.

[0087] In some embodiments, the first metal element can include one or more of Fe, Ni, Cu, and can be optionally Cu.

[0088] In some embodiments, the second metal element can include one or more of Zn, Ag, Mg, Be, Ga, In, Ge, Sb, Sn, Pb, As, Te, Bi, and can be optionally including one or more of Zn, Ga, Ge, Sb.

[0089] In some embodiments, the third metal element can include one or more of Fe, Ni, Cu, and can be optionally Cu.

[0090] In some embodiments, both the first metal element and the third metal element can be Cu.

[0091] In some embodiments, the alloy layer can be disposed on the surface of the substrate by magnetron sputtering, electroless plating, electroplating, or spraying. Optionally, the alloy layer can be disposed on the surface of the substrate by magnetron sputtering. Compared with other methods, the magnetron sputtering method is simpler, faster, and more convenient to operate. At the same time, the alloy layer formed by magnetron sputtering has a higher bonding force with the substrate and better stability of the alloy layer.

[0092] 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.

[0093] The composite substrate may include 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.

[0094] Optionally, the substrate may include a copper foil, a nickel foil, and more preferably a copper foil.

[0095] [Positive electrode tab]

[0096] The battery cell includes a positive electrode tab.

[0097] In some embodiments, the positive electrode tab 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 own 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.

[0098] In some embodiments, the positive electrode active material includes a material capable of deintercalating and intercalating lithium.

[0099] 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. The lithium transition metal oxides may include, but are not limited to, a layered structure and a spinel structure. Examples of lithium-containing phosphates may include, but are not limited to, 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 manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and their respective modified compounds.

[0100] 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 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.

[0101] 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.

[0102] 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 0.2 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.

[0103] 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.

[0104] In some embodiments, as examples, the positive electrode active material may include but is not limited to NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, Na 0.67One or more of MO₂ (where M includes at least two of Fe, Co, Cr, Mn, Ni, V, Ti, and Mo), NaMO₂ (where 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 their respective modified compounds.

[0105] The modified compounds of the above-mentioned cathode active materials can be doping modification and / or surface coating modification of the cathode active materials.

[0106] In some embodiments, the cathode film layer may also optionally include a cathode conductive agent. As an example, the cathode conductive agent can 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.

[0107] In some embodiments, the cathode film layer may also optionally include a cathode binder. As an example, the cathode binder can include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene oxide, fluorinated acrylate 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 carboxymethyl chitosan (CMCS).

[0108] In some embodiments, the cathode current collector can be a metal foil or a composite current collector. As an example of the metal foil, aluminum foil can be used. The composite current collector can 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 can 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 can include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0109] The positive electrode film layer is usually formed by coating a positive electrode slurry on a positive electrode current collector and then drying and cold pressing. The positive electrode slurry is usually formed by dispersing a positive electrode active material, an optional positive electrode conductive agent, an optional positive electrode binder, and any other components in a solvent and stirring evenly. The solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.

[0110] [Electrolyte]

[0111] The battery cell includes an electrolyte.

[0112] In some embodiments, the electrolyte uses an electrolytic solution, and the electrolytic solution includes an electrolyte salt and an organic solvent.

[0113] In some embodiments, the electrolytic solution includes anions, and the anions can include one or more of bis(fluorosulfonyl)imide anion (FSI - ), bis(trifluoromethylsulfonyl)imide anion (TFSI - ), bis(oxalato)borate anion (BOB - ), difluoro(oxalato)borate anion (DFOB - ), difluoro(dioxalato)phosphate anion (DFOP - ), tetrafluoro(oxalato)phosphate anion (TFOP - ), difluorophosphate anion (PO2F2 - ), hexafluorophosphate anion (PF6 - ), tetrafluoroborate anion (BF4 - ), hexafluoroarsenate anion (AsF6 - ), trifluoromethanesulfonate anion (CF3SO3 - ).

[0114] In some embodiments, the electrolytic solution includes cations, and the cations can include one or more of lithium ions and sodium ions.

[0115] In some embodiments, the concentration of the electrolyte salt can be 0.3 mol / L or more, optionally 0.7 mol / L or more, and further can be 4 mol / L or less, optionally 2.5 mol / L or less, 1.7 mol / L or less. When the concentration of the electrolyte salt is within the above range, the electrolytic solution can have appropriate ionic conductivity.

[0116] The organic solvent can include, but is not limited to, one or more of esters, ethers, sulfones, nitriles, etc. The esters can include, but are not limited to, one or more of carbonates, phosphates, carboxylates, sulfates, sulfonates, etc. The carbonates can include cyclic carbonates and / or chain carbonates. Optionally, the carbonates can include both cyclic carbonates and chain carbonates at the same time. The chain carbonates can include low-viscosity polar chain carbonates, aliphatic branched carbonates, etc.

[0117] 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 sulfite (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), diethyl sulfone (ESE), tetraethylene glycol dimethyl ether (TEGDME), ethylene glycol dimethyl ether (DME), 1,1,2,2-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 propyl ether, 4-trifluoromethyldecafluoropentyl methyl ether, 4-trifluoromethyldecafluoropentyl ethyl ether, 4-trifluoromethyldecafluoropentyl propyl ether, 5-trifluoromethyldodecafluorohexyl methyl ether, 5-trifluoromethyldodecafluorohexyl ethyl ether, 5-trifluoromethyldodecafluorohexyl propyl ether, 6-trifluoromethyltetradecafluoroheptyl methyl ether, 6-trifluoromethyltetradecafluoroheptyl ethyl ether, 6-trifluoromethyltetradecafluoroheptyl propyl ether, 7-trifluoromethylhexadecafluorooctyl methyl ether, 7-trifluoromethylhexadecafluorooctyl ethyl ether, 7-trifluoromethylhexadecafluorooctyl propyl ether, or one or more of them.

[0118] In some embodiments, the electrolyte may also optionally include additives. For example, the additives may include negative electrode film-forming additives, may also include positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives for improving battery overcharge performance, additives for improving battery high-temperature performance, additives for improving battery low-temperature power performance, etc.

[0119] [Separator membrane]

[0120] The battery cell may also include a separator membrane. The separator membrane is located between the positive electrode and the negative electrode, mainly functioning to prevent internal short circuit.

[0121] There is no particular limitation on the type of the separator membrane in this application, and any well-known porous structure separator membrane with good chemical stability and mechanical stability can be selected.

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

[0123] The preparation method of the battery cell is well-known. In some embodiments, the positive electrode, separator membrane, negative electrode, and electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator membrane, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process, the electrode assembly is placed in an outer package, dried, and then the above-mentioned electrolyte is injected. After processes such as vacuum packaging, standing, and formation, a battery cell is obtained. Multiple battery cells can further be combined in series or in parallel or in a hybrid connection to form a battery module. Multiple battery modules can also be formed into a battery pack through series or parallel or hybrid connection. In some embodiments, multiple battery cells can also directly form a battery pack.

[0124] The embodiments of this application also provide an electrical device, and the electrical device includes the battery provided by the embodiments of this application. The battery can be used as the power source of the electrical device or as the energy storage unit of 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.

[0125] The electrical device can select the type of the battery according to its usage requirements, such as a battery cell, a battery module, or a battery pack.

[0126] Figure 6 It is a schematic diagram of an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of the electrical device for high power and high energy density, a battery pack or a battery module can be used.

[0127] Another example of the electrical device can be a mobile phone, a tablet computer, a laptop computer, etc. This electrical device usually requires being thin and light, and a battery cell can be used as the power source.

[0128] Embodiment

[0129] The following examples describe more specifically the content disclosed in the present application. These examples are for illustrative purposes only, as various modifications and variations within the scope of the present application disclosure are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and all instruments used in the examples are commercially available.

[0130] Performance Test

[0131] (1) Coulombic efficiency test

[0132] In an argon - protected glove box, a lithium metal sheet was used as the counter electrode, and a button cell was assembled with the negative electrode current collectors prepared in each example and comparative example. The electrolyte salt of the electrolyte was LiFSI with a concentration of 1 mol / L, and the solvent of the electrolyte used 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 used a PE film with a thickness of 12 μm.

[0133] At 25 °C, after the assembled button cell was allowed to stand for 12 h, a constant - current charge - discharge cycle was carried out at a current density of 1 mA / cm 2 until the discharge capacity after cycling decayed to 90% of the first - cycle discharge capacity, and the test was stopped.

[0134] The first - cycle Coulombic efficiency of the button cell = first - cycle charge capacity / first - cycle discharge capacity × 100%.

[0135] The average Coulombic efficiency of the button cell is the average value of the Coulombic efficiency per cycle.

[0136] During the test, the number of button cell samples can be more than 6, and the test results are averaged.

[0137] (2) Cycle performance test

[0138] Lithium iron phosphate, conductive agent carbon black (Super P), and binder polyvinylidene fluoride (PVDF) were mixed evenly in an appropriate amount of solvent N - methylpyrrolidone (NMP) according to a weight ratio of 95:1.7:3.3 to obtain a positive electrode slurry; the positive electrode slurry was coated on an aluminum foil positive electrode current collector and dried to obtain a positive electrode plate.

[0139] 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 coin - type batteries. The electrolyte salt of the electrolyte was LiFSI with a concentration of 1 mol / L, and the solvent of the electrolyte used 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 used a PE film with a thickness of 12 μm.

[0140] At 25 °C, after the assembled coin - type battery was left standing for 12 h, it was charged at a constant current of 0.2C to 3.65 V, and then charged at a constant voltage of 3.65 V to 0.1C; after the coin - type battery was left standing for 10 min, it was discharged at a constant current of 1C to 2.5 V. The coin - type battery was cycled for charge and discharge according to the above method until the discharge capacity after cycling was 50% of the discharge capacity in the first cycle, and the number of cycles was recorded.

[0141] During the test, the number of coin - type battery samples could be more than 6, and the test results were averaged.

[0142] Example 1

[0143] Commercially available two - dimensional copper foil with a thickness of 35 μm was purchased.

[0144] The copper foil was placed in an ion sputtering instrument, and an alloy layer was formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target used was a Zn - Cu alloy target with a weight ratio of Zn and Cu of 40:60. The upper limit of the vacuum - set air pressure of the ion sputtering instrument was 1.0 MPa, and the sputtering current was 30 mA. After starting sputtering, 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 。

[0145] Example 2

[0146] Commercially available two - dimensional copper foil with a thickness of 35 μm was purchased.

[0147] The copper foil was placed in an ion sputtering instrument, and an alloy layer was formed by vacuum magnetron sputtering to obtain a negative electrode current collector. The target used was a Zn - Ni alloy target with a weight ratio of Zn and Ni of 40:60. The upper limit of the vacuum - set air pressure of the ion sputtering instrument was 1.0 MPa, and the sputtering current was 30 mA. After starting sputtering, 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 。

[0148] Comparative Example 1

[0149] Commercially available two - dimensional copper foil with a thickness of 35 μm was purchased and used as the negative electrode current collector.

[0150] Comparative Example 2

[0151] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0152] Place the copper foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative electrode current collector. The target material uses a pure Zn target. The upper limit of the vacuum set pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 .

[0153] Table 1

[0154]

[0155] From the test results of Example 1, Example 2 and Comparative Example 1, it can be seen that by setting an alloy layer on the substrate copper foil, the average Coulomb 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 enhanced.

[0156] From the test results of Comparative Example 2, it can be seen that by setting a lithium-philic layer composed of a second metal on the substrate surface, the first Coulomb efficiency of the battery decreases significantly. At the same time, compared with Comparative Example 1, the improvement of the reliability and cycle life of the battery is not excellent enough. This is because when the second metal element forms an alloy with the deposited lithium, a part of the active ions will be irreversibly consumed, resulting in a significant decrease in the first Coulomb efficiency of the battery compared with Comparative Example 1. At the same time, due to the lack of the framework effect of the first metal element in the lithium-philic layer, the volume expansion caused by the formation of the alloy between the second metal element and the deposited lithium cannot be suppressed. The excessive volume expansion will cause the lithium-philic layer to be unstable and easy to fall off during the long-term cycling of the battery. In addition, due to the large volume expansion of the lithium-philic layer, problems such as a decrease in the internal porosity of the battery, poor wettability of the electrolyte, and poor activity of alkali metal deposition and stripping will also occur.

[0157] From the test results of Example 1 and Example 2, it can also be seen that when the first metal element in the alloy layer is the same as the substrate material, the battery can have a higher average Coulomb efficiency, a longer short circuit time and a longer cycle life. This is because the bonding force between the same materials is stronger, and the bonding force between the alloy layer and the substrate is higher, so that the alloy layer can cover the substrate surface more stably and reduce the risk of alloy layer peeling off.

[0158] Example 3

[0159] Purchase commercially available two-dimensional nickel foil with a thickness of 35 μm.

[0160] Place the nickel foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative current collector. The target material is a Zn-Ni alloy target, and the weight ratio of Zn to Ni is 40:60. The upper limit of the vacuum-set air pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 。

[0161] Example 4

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

[0163] Place the nickel foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative current collector. The target material is a Zn-Cu alloy target, and the weight ratio of Zn to Cu is 40:60. The upper limit of the vacuum-set air pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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] Comparative Example 3

[0165] Purchase commercially available two-dimensional nickel foil with a thickness of 35 μm as the negative current collector.

[0166] Comparative Example 4

[0167] Purchase commercially available two-dimensional nickel foil with a thickness of 35 μm.

[0168] Place the nickel foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative current collector. The target material is a pure Zn target. The upper limit of the vacuum-set air pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 。

[0169] Table 2

[0170]

[0171] From the test results of Example 3, Example 4 and Comparative Example 3, it can be seen that by setting an alloy layer on the substrate nickel foil, the average Coulomb 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 enhanced.

[0172] From the test results of Comparative Example 4, it can be seen that by providing a lithiophilic layer composed of a second metal on the surface of the substrate, the initial Coulombic efficiency of the battery decreases significantly. At the same time, compared with Comparative Example 3, the improvement in the reliability and cycle life of the battery is not excellent enough. This is because when the second metal element forms an alloy with the deposited lithium, a part of the active ions will be irreversibly consumed, resulting in a significant decrease in the initial Coulombic efficiency of the battery compared with Comparative Example 3. At the same time, 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 formation of an alloy between the second metal element and the deposited lithium cannot be suppressed. The excessive volume expansion will cause the lithiophilic layer to be unstable and prone to peeling off during the long-term cycling of the battery. In addition, due to the large volume expansion of the lithiophilic layer, problems such as a decrease in the internal porosity of the battery, poor wettability of the electrolyte, and poor activity of alkali metal deposition and stripping will also occur.

[0173] From the test results of Example 3 and Example 4, it can also be seen that when the first metal element in the alloy layer is the same as the substrate material, the battery can have a higher average Coulombic efficiency, a longer short-circuit time, and a longer cycle life. This is because the bonding force between the same materials is stronger, and the bonding force between the alloy layer and the substrate is higher, so that the alloy layer can cover the surface of the substrate more stably and reduce the risk of the alloy layer peeling off.

[0174] From the test results of Example 1 and Example 3, it can also be seen that when the substrate includes Cu element, the battery can have a higher average Coulombic efficiency, a longer short-circuit time, and a longer cycle life.

[0175] Example 5

[0176] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0177] Place the copper foil in an ion sputtering instrument and form an alloy layer by vacuum magnetron sputtering to obtain a negative current collector. The target is an Sn-Cu alloy target, and the weight ratio of Sn to Cu is 40:60. The upper limit of the vacuum set pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 。

[0178] Example 6

[0179] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0180] Place the copper foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative current collector. The target is a Ga-Cu alloy target, and the weight ratio of Ga to Cu is 40:60. The upper limit of the vacuum-set air pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 .

[0181] Example 7

[0182] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0183] Place the copper foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative current collector. The target is a Ge-Cu alloy target, and the weight ratio of Ge to Cu is 40:60. The upper limit of the vacuum-set air pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 .

[0184] Example 8

[0185] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0186] Place the copper foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative current collector. The target is an Sb-Cu alloy target, and the weight ratio of Sb to Cu is 40:60. The upper limit of the vacuum-set air pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 .

[0187] Table 3

[0188]

[0189] From the test results of Examples 1, 5 to 8, it can be seen that when the types of the second metal element are different, the improvement effects on the battery performance will be different.

[0190] Example 9

[0191] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0192] Place the copper foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative electrode current collector. The target is a Zn-Cu alloy target, and the weight ratio of Zn to Cu is 10:90. The upper limit of the vacuum set pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 .

[0193] Example 10

[0194] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0195] Place the copper foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative electrode current collector. The target is a Zn-Cu alloy target, and the weight ratio of Zn to Cu is 20:80. The upper limit of the vacuum set pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 .

[0196] Example 11

[0197] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0198] Place the copper foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative electrode current collector. The target is a Zn-Cu alloy target, and the weight ratio of Zn to Cu is 30:70. The upper limit of the vacuum set pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 .

[0199] Example 12

[0200] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0201] Place the copper foil in an ion sputtering instrument and form an alloy layer through vacuum magnetron sputtering to obtain a negative electrode current collector. The target is a Zn-Cu alloy target, and the weight ratio of Zn to Cu is 50:50. The upper limit of the vacuum set pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 .

[0202] Example 13

[0203] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0204] Place the copper foil in an ion sputtering instrument and form an alloy layer by vacuum magnetron sputtering to obtain a negative electrode current collector. The target is a Zn-Cu alloy target, and the weight ratio of Zn to Cu is 60:40. The upper limit of the vacuum set pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 .

[0205] Example 14

[0206] Purchase commercially available two-dimensional copper foil with a thickness of 35 μm.

[0207] Place the copper foil in an ion sputtering instrument and form an alloy layer by vacuum magnetron sputtering to obtain a negative electrode current collector. The target is a Zn-Cu alloy target, and the weight ratio of Zn to Cu is 5:95. The upper limit of the vacuum set pressure of the ion sputtering instrument is 1.0 MPa, and the sputtering current is 30 mA. After starting sputtering, 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 .

[0208] Table 4

[0209]

[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 Coulomb 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 by adjusting the sputtering time 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 by adjusting the sputtering time 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 by adjusting the sputtering time 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 by adjusting the sputtering time. 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 by adjusting the sputtering time. 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]

[0225] It can also be seen from the test results of Examples 1, 15 to 20 that when the composition elements and ratios of the alloy layer are the same, by further adjusting the surface density of the alloy layer, the battery can have a higher average Coulomb efficiency, a longer short-circuit time, and a longer cycle life.

[0226] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same structure and the same function and effect as the technical idea within the technical solution scope of this application are all included in the technical scope of this application. In addition, within the scope not departing from the gist of this application, various deformations that can be thought of by those skilled in the art are applied to the embodiments, and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of this application.

Claims

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

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, characterized in that, The nucleation overpotential of the single substance of the first metal element 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, characterized in that, the nucleation overpotential of the single substance of the second metal element 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 single substance of the third metal element 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, characterized in that, The nucleation overpotential of the single substance of the first metal element with respect to lithium metal is denoted as V1, the nucleation overpotential of the single substance of the second metal element with respect to lithium metal is denoted as V2, and the nucleation overpotential of the single substance of the third metal element 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, characterized in that, 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, characterized in that, 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, characterized in that, 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, characterized in that, 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, characterized in that, 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. The metal layer includes a third metal element.

11. A battery cell, characterized in that, Including the negative electrode current collector according to any one of claims 1-10.

12. The battery cell according to claim 11, characterized in that, 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, characterized in that, Including the battery cell according to any one of claims 11-12.

14. An electrical device, characterized in that, Including the battery according to claim 13, and the battery is used to provide electrical energy.

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