Negative electrode plate, battery cell, battery and electrical device

Abstract

This application discloses a negative electrode sheet, a battery cell, a battery, and an electrical device. The negative electrode sheet includes a negative current collector and a modification layer located on at least one surface of the negative current collector. The modification layer includes an alkali metal affinity layer and a non-metallic conductive layer located on the surface of the alkali metal affinity layer away from the negative current collector. The nucleation overpotential of the alkali metal affinity layer is denoted as V1, and the nucleation overpotential of the non-metallic conductive layer is denoted as V2, both in mV, and V2 - V1 is greater than or equal to 40 mV. The negative electrode sheet provided by this application enables the battery to have good cycle performance and high reliability.

Description

Technical Field

[0001] This application relates to a negative electrode sheet, a battery cell, a battery, and an electrical device. Background Technology

[0002] Compared to ion-ion batteries, metal batteries can achieve higher energy densities. However, unlike the negative electrode of ion-ion batteries, the negative electrode of metal batteries suffers from a more severe dendrite problem, thus affecting their commercialization. Dendrite growth can cause internal short circuits in the battery, affecting its reliability; simultaneously, the repeated tearing and rebuilding of the unstable solid electrolyte interface (SEI) film during metal deposition and stripping continuously consumes active ions and electrolyte, thereby affecting the battery's cycle performance. The above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0003] This application provides a negative electrode sheet, a battery cell, a battery, and an electrical device, which enable the battery to have good cycle performance and high reliability.

[0004] In a first aspect, this application provides a negative electrode sheet, which includes a negative current collector and a modification layer located on at least one surface of the negative current collector. The modification layer includes an alkali metal affinity layer and a non-metallic conductive layer located on the surface of the alkali metal affinity layer away from the negative current collector. The nucleation overpotential of the alkali metal affinity layer is denoted as V1, and the nucleation overpotential of the non-metallic conductive layer is denoted as V2, both in mV, and V2-V1 is greater than or equal to 40mV.

[0005] This application starts from the structure of the negative electrode sheet, by first forming an alkali metal affinity layer on the negative electrode current collector, and then forming a non-metallic conductive layer. Since the non-metallic conductive layer itself is conductive, it will not affect the passage of metal ions such as lithium ions and sodium ions.

[0006] Alkali metal affinity layers include those that can be affinity-bonded with metals such as lithium and sodium. This can reduce the volume change of the negative electrode sheet caused by metal deposition and stripping during battery cycling, thereby stabilizing the skeleton structure of the negative electrode sheet and improving the cycle stability of the battery.

[0007] By further adjusting the nucleation overpotential V2 of the non-metallic conductive layer and the nucleation overpotential V1 of the alkali metal affinity layer to be greater than or equal to 40 mV, under the induction of this differential nucleation overpotential, metal ions such as lithium ions and sodium ions can pass through the non-metallic conductive layer and land on the surface of the alkali metal affinity layer, forming a large number of active sites. These active sites can act as "seeds" to induce uniform deposition of metals such as lithium and sodium, thereby reducing dominant growth points, dendrite formation, and localized metal deposition. Furthermore, the formed active sites can also increase the negative electrode potential, thus helping to improve the film quality of the SEI film on the negative electrode surface.

[0008] In addition, under the pressure of the non-metallic conductive layer, the deposited lithium, sodium and other metals can grow uniformly between the non-metallic conductive layer and the negative electrode current collector, which can further reduce dendrite formation, and thus reduce electrolyte side reactions and active ion consumption caused by repeated tearing and rebuilding of the SEI film.

[0009] Therefore, the negative electrode provided in this application embodiment can enable the battery to have good cycle performance and high reliability.

[0010] In some embodiments, V2-V1 is 48mV-121mV, optionally 57mV-94mV. By further adjusting V2-V1 within the above range, the battery can better balance high reliability and good cycle performance.

[0011] In some embodiments, V1 is 0mV-40mV, and can be selected as 8mV-22mV.

[0012] In some embodiments, V2 is 60mV-120mV, and optionally 78mV-110mV.

[0013] By further adjusting the nucleation overpotential V1 of the alkali metal affinity layer and / or the nucleation overpotential V2 of the non-metallic conductive layer within the above range, the battery can better combine high reliability and good cycle performance.

[0014] In some embodiments, the non-metallic conductive layer comprises a non-metallic conductive material.

[0015] Optionally, the non-metallic conductive material includes one or more of carbon-based conductive materials and phosphorus-based conductive materials.

[0016] Alternatively, the non-metallic conductive material includes one or more of porous carbon, hard carbon, carbon nanotubes, red phosphorus, black phosphorus, and phosphorus-carbon composites.

[0017] In some embodiments, the alkali metal affinity layer comprises a lithiophilic material.

[0018] In some embodiments, the lithiophilic material comprises a lithiophilic metal element. Optionally, the lithiophilic metal element comprises one or more of Ag, Mg, Sn, Al, Bi, Au, In, Cu, and Zn.

[0019] In some embodiments, the lithiophilic material includes one or more of the elemental form, oxide, nitride, and phosphide of the lithiophilic metal element, and may be selected from one or more of elemental Ag, elemental Mg, elemental Sn, elemental Al, elemental Bi, elemental Au, elemental In, silver oxide, magnesium oxide, aluminum oxide, bismuth oxide, cuprous oxide, zinc oxide, magnesium nitride, aluminum nitride, copper nitride, zinc nitride, copper phosphide, and zinc phosphide.

[0020] In some embodiments, the alkali metal affinity layer comprises a sodium-loving material.

[0021] In some embodiments, the naphophilic material comprises a naphophilic metal element. Optionally, the naphophilic metal element comprises one or more of Ag, Mg, Sn, Cu, and Zn.

[0022] In some embodiments, the sodium-loving material includes one or more of the sodium-loving metal element as a single substance, oxide, nitride, or phosphide, and may be selected from one or more of elemental Ag, elemental Mg, elemental Sn, silver oxide, magnesium oxide, cuprous oxide, zinc oxide, magnesium nitride, copper nitride, zinc nitride, copper phosphide, and zinc phosphide.

[0023] In some embodiments, the total thickness of the modification layer is 11 μm-55 μm, and optionally 18 μm-53 μm.

[0024] In some embodiments, the thickness of the alkali metal affinity layer is 1 μm-6 μm, optionally 1 μm-5 μm. A thickness within this range provides a large number of active sites, inducing uniform metal deposition and resulting in high battery reliability. Furthermore, it reduces active ion consumption, leading to good cycle performance.

[0025] In some embodiments, the thickness of the non-metallic conductive layer is 10 μm-50 μm, optionally 15 μm-50 μm. A thickness within this range can increase the driving force for lithium ions, sodium ions, and other metal ions to penetrate the non-metallic conductive layer and reach the alkali metal affinity layer, inducing uniform metal deposition. Furthermore, under pressure, the deposited lithium, sodium, and other metals can grow uniformly between the non-metallic conductive layer and the negative electrode current collector, further reducing dendrite formation, electrolyte side reactions, and the consumption of active ions. In addition, it can reduce the resistance of lithium ions, sodium ions, and other metal ions when they pass through the non-metallic conductive layer, reduce battery polarization, reduce battery kinetic losses, and give the battery good cycle performance.

[0026] In some embodiments, the areal density of the alkali metal affinity layer is 1 g / m². 2 -8g / m 2 When the areal density of the alkali metal affinity layer is within the aforementioned range, it can provide a large number of active sites, inducing uniform metal deposition and giving the battery high reliability. On the other hand, it can also reduce the consumption of active ions, giving the battery good cycle performance.

[0027] In some embodiments, the areal density of the non-metallic conductive layer is 18 g / m². 2 -92g / m 2 When the areal density of the metallic conductive layer is within the aforementioned range, it can increase the driving force for metal ions such as lithium and sodium ions to pass through the non-metallic conductive layer and reach the alkali metal affinity layer, inducing uniform metal deposition. Furthermore, under pressure, the deposited lithium, sodium, and other metals can grow uniformly between the non-metallic conductive layer and the negative electrode current collector, further reducing dendrite formation and minimizing electrolyte side reactions and active ion consumption. In addition, it can reduce the resistance of metal ions such as lithium and sodium ions when passing through the non-metallic conductive layer, giving the battery good cycle performance.

[0028] In some embodiments, the negative current collector comprises a metallic material, which includes one or more of copper, nickel, titanium, magnesium, aluminum, copper alloys, nickel alloys, titanium alloys, magnesium alloys, and aluminum alloys.

[0029] Secondly, this application provides a battery cell that includes the negative electrode sheet of the first aspect of this application, wherein 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] Thirdly, this application provides a battery that includes the battery cell of the second aspect of this application.

[0031] Fourthly, this application provides an electrical device that includes the battery of the third aspect of this application, the battery being used to provide electrical energy.

[0032] The electrical device of this application includes the battery provided in this application, and therefore has at least the same advantages as the battery. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0034] Figure 1The diagram shows a schematic of a battery cell provided in some embodiments of this application.

[0035] Figure 2 An exploded view of a battery cell provided in some embodiments of this application is shown.

[0036] Figure 3 This document shows schematic diagrams of battery modules provided in some embodiments of this application.

[0037] Figure 4 This illustration shows a schematic diagram of a battery pack provided in some embodiments of this application.

[0038] Figure 5 yes Figure 4 The diagram shown is an exploded view of the battery pack.

[0039] Figure 6 This diagram illustrates the metal deposition process of a conventional metal current collector during battery charging and discharging.

[0040] Figure 7 This diagram illustrates the metal deposition process of the negative electrode sheet provided in this application during the battery charging and discharging process.

[0041] Figure 8 A schematic diagram of an electrical device provided in some embodiments of this application is shown.

[0042] In the accompanying drawings, the figures may not be drawn to scale. The reference numerals are explained as follows: 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery module; 5. Battery; 51. Housing; 52. Electrode assembly; 53. Cover plate; 101. Negative current collector; 102. Alkali metal affinity layer; 102a. Alkali metal affinity layer with active sites; 103. Non-metallic conductive layer; 104. Deposited metal layer. Detailed Implementation

[0043] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the negative electrode, battery cell, battery, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0044] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; 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, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

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

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

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

[0048] In this application, the terms "multiple" or "various" refer to two or more kinds of things.

[0049] In the description of the embodiments of this application, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

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

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

[0052] The battery mentioned in the embodiments of this application can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application can include battery cells, battery modules, or battery packs.

[0053] A battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. A battery cell can be cylindrical, cuboid, or other shapes, etc., and the embodiments of this application are not limited in this respect. Figure 1 The example shown is a rectangular battery cell 5.

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

[0055] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0056] The battery cell includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to this.

[0057] The battery cell may also include an outer packaging, which can be used to encapsulate the electrode assembly. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0058] In some embodiments, such as Figure 2 As shown, the outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates enclosing a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 is used to cover the opening to close the receiving cavity. Electrode assemblies 52 are encapsulated in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, and can be adjusted according to requirements.

[0059] In some embodiments, individual battery cells can be assembled into a battery module, and the number of individual battery cells contained in the battery module can be multiple, the specific number of which can be adjusted according to the application and capacity of the battery module. Figure 3 This is a schematic diagram of battery module 4 as an example. Figure 3 As shown, in battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0060] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0061] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0062] Figure 4 and Figure 5 This is a schematic diagram of battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The housing includes an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the housing.

[0063] The battery cells provided in the embodiments of this application may include negative electrode-free lithium metal battery cells, negative electrode-free sodium metal battery cells, etc.

[0064] A negative electrode-free battery cell typically refers to a battery cell in which no negative electrode active material layer is actively formed on the negative electrode side during the battery cell manufacturing process. For example, the negative electrode active material layer is not formed at the negative electrode through coating or deposition processes, nor is it formed by a carbonaceous active material layer. During the first charge, ions gain electrons on the negative electrode side and deposit metal on the surface of the negative electrode current collector. During discharge, the metal can be converted back into ions and return to the positive electrode, achieving cyclic charging and discharging. Compared to other battery cells, a negative electrode-free battery cell can achieve a higher energy density due to the absence of a negative electrode active material layer. The CB (Cell Balance) value of a negative electrode-free battery cell is typically very small; for example, in some embodiments, the CB value can be less than or equal to 0.1. The CB value is the capacity per unit area of ​​the negative electrode divided by the capacity per unit area of ​​the positive electrode. Because a negative electrode-free battery cell contains little or no negative electrode active material, the capacity per unit area of ​​the negative electrode is small, resulting in a very small CB value, typically less than or equal to 0.1.

[0065] Unlike the negative electrode of ion batteries, the negative electrode of metal batteries suffers from a more severe dendrite problem, making the negative electrode of metal batteries crucial to their performance.

[0066] This application provides a negative electrode sheet that can be used in negative electrode-free lithium metal batteries and negative electrode-free sodium metal batteries to give the battery good cycle performance and high reliability.

[0067] The negative electrode provided in this application includes a negative current collector and a modification layer located on at least one surface of the negative current collector. The modification layer includes an alkali metal affinity layer and a non-metallic conductive layer located on the surface of the alkali metal affinity layer away from the negative current collector. The nucleation overpotential of the alkali metal affinity layer is denoted as V1, and the nucleation overpotential of the non-metallic conductive layer is denoted as V2, both in mV, and V2-V1 is greater than or equal to 40mV.

[0068] Because metals such as lithium and sodium have high nucleation overpotentials on conventional metal current collectors (e.g., copper foil), they tend to preferentially nucleate at certain surface defect sites on these current collectors. These preferential nucleation sites become dominant growth points, easily leading to dendrite formation and potentially causing internal short circuits in the battery, thus affecting battery reliability. Furthermore, during metal deposition and stripping, the unstable SEI film repeatedly tears and rebuilds, constantly exposing fresh surfaces and continuously consuming active ions and electrolyte, impacting the battery's cycle performance.

[0069] Figure 6 This diagram illustrates metal deposition using a conventional metal current collector during battery charging and discharging. Figure 6As shown, conventional metal current collectors tend to form dominant growth points on their surfaces, which in turn can easily lead to the formation of sharp dendrites during battery charging and discharging.

[0070] This application starts from the structure of the negative electrode sheet, by first forming an alkali metal affinity layer on the negative electrode current collector, and then forming a non-metallic conductive layer. Since the non-metallic conductive layer itself is conductive, it will not affect the passage of metal ions such as lithium ions and sodium ions.

[0071] Alkali metal affinity layers include those that can be affinity-bonded with metals such as lithium and sodium. This can reduce the volume change of the negative electrode sheet caused by metal deposition and stripping during battery cycling, thereby stabilizing the skeleton structure of the negative electrode sheet and improving the cycle stability of the battery.

[0072] By further adjusting the nucleation overpotential V2 of the non-metallic conductive layer and the nucleation overpotential V1 of the alkali metal affinity layer to be greater than or equal to 40 mV, under the induction of this differential nucleation overpotential, metal ions such as lithium ions and sodium ions can pass through the non-metallic conductive layer and land on the surface of the alkali metal affinity layer, forming a large number of active sites. These active sites can act as "seeds" to induce uniform deposition of metals such as lithium and sodium, thereby reducing dominant growth points, dendrite formation, and localized metal deposition. Furthermore, the formed active sites can also increase the negative electrode potential, thus helping to improve the film quality of the SEI film on the negative electrode surface.

[0073] In addition, under the pressure of the non-metallic conductive layer, the deposited lithium, sodium and other metals can grow uniformly between the non-metallic conductive layer and the negative electrode current collector, which can further reduce dendrite formation, and thus reduce electrolyte side reactions and active ion consumption caused by repeated tearing and rebuilding of the SEI film.

[0074] When the difference between the nucleation overpotential V2 of the non-metallic conductive layer and the nucleation overpotential V1 of the alkali metal affinity layer is less than 40mV, the driving force for metal ions such as lithium ions and sodium ions to pass through the non-metallic conductive layer to reach the alkali metal affinity layer is small. At this time, metal ions such as lithium ions and sodium ions tend to nucleate directly in the non-metallic conductive layer, thus failing to play the role of the alkali metal affinity layer, and also failing to reduce local metal deposition and dendrite formation, which in turn reduces the reliability and cycle performance of the battery.

[0075] Therefore, the negative electrode provided in this application embodiment can enable the battery to have good cycle performance and high reliability.

[0076] Figure 7 This diagram illustrates the metal deposition process of the negative electrode sheet provided in this application during the battery charging and discharging process.

[0077] like Figure 7As shown in Figure A, the negative electrode includes a negative current collector 101, an alkali metal affinity layer 102 on one surface of the negative current collector 101, and a non-metallic conductive layer 103 on the surface of the alkali metal affinity layer 102 away from the negative current collector 101.

[0078] like Figure 7 As shown in B, during the initial charging of the battery, metal ions such as lithium ions and sodium ions can pass through the non-metallic conductive layer 103 and land on the surface of the alkali metal affinity layer 102, forming a large number of active sites on the alkali metal affinity layer 102, thereby forming an alkali metal affinity layer 102a with a large number of active sites.

[0079] like Figure 7 C and Figure 7 As shown in Figure D, the active sites in the alkali metal affinity layer 102a can act as "seeds" to induce uniform deposition of metals such as lithium and sodium, forming a deposited metal layer 104. Furthermore, under the pressure of the non-metallic conductive layer 103, the deposited metals such as lithium and sodium can grow uniformly between the non-metallic conductive layer 103 and the negative electrode current collector 101, thereby further reducing dendrite formation.

[0080] The difference between the nucleation overpotential V2 of the non-metallic conductive layer and the nucleation overpotential V1 of the alkali metal affinity layer, V2-V1, is greater than or equal to 40 mV. For example, it can be 40 mV, 48 mV, 54 mV, 57 mV, 60 mV, 64 mV, 70 mV, 75 mV, 80 mV, 85 mV, 89 mV, 94 mV, 100 mV, 108 mV, 121 mV, or any range of the above values. In some embodiments, V2-V1 can be 48 mV-121 mV, and can be selected as 48 mV-108 mV or 57 mV-94 mV.

[0081] By further adjusting V2-V1 within the aforementioned range, the battery can better combine high reliability and good cycle performance.

[0082] In some embodiments, the nucleation overpotential V1 of the alkali metal affinity layer can be 0mV-40mV, for example, it can be 0mV, 4mV, 8mV, 10mV, 11mV, 12mV, 13mV, 14mV, 15mV, 16mV, 17mV, 18mV, 19mV, 20mV, 21mV, 22mV, 24mV, 26mV, 28mV, 30mV, 32mV, 34mV, 36mV, 38mV, 40mV, or any range of the above values. In some embodiments, the nucleation overpotential V1 of the alkali metal affinity layer can be 0mV-35mV, 0mV-30mV, 8mV-30mV, or 8mV-22mV.

[0083] In some embodiments, the nucleation overpotential V2 of the non-metallic conductive layer can be 60mV-120mV, for example, it can be 60mV, 65mV, 69mV, 74mV, 78mV, 82mV, 88mV, 96mV, 102mV, 110mV, 120mV, or any range of the above values. In some embodiments, the nucleation overpotential V2 of the non-metallic conductive layer can be 69mV-120mV, 78mV-110mV, or 78mV-102mV.

[0084] By further adjusting the nucleation overpotential V1 of the alkali metal affinity layer and / or the nucleation overpotential V2 of the non-metallic conductive layer within the above range, the battery can better combine high reliability and good cycle performance.

[0085] The nucleation overpotential V1 of the alkali metal affinity layer and the nucleation overpotential V2 of the nonmetallic conductive layer can be tested using a coin cell.

[0086] During testing, a coin cell can be assembled in an argon-protected glove box using a lithium metal sheet as the counter electrode and a negative electrode sheet; then, after the assembled coin cell is left to stand at 25°C for 12 hours, it is tested at 1 mA / cm². 2 Constant current discharge to 1 mAh / cm 2 At the start of the lithium metal deposition process, a significant voltage drop occurs, followed by a flat voltage plateau. The difference between the voltage at the lowest point and the flat portion of the voltage plateau is taken as the nucleation overpotential. The electrolyte salt for the coin cell can be LiFSI at a concentration of 1 mol / L, and the solvent can be dimethyl ethylene glycol ether (DME). The separator for the coin cell can be a 12 μm thick PE membrane.

[0087] In the above-mentioned nucleation overpotential test, the negative electrode includes both an alkali metal affinity layer and a non-metallic conductive layer. When testing the nucleation overpotential of the alkali metal affinity layer, a negative electrode including an alkali metal affinity layer but excluding the non-metallic conductive layer can be prepared under the same process conditions for testing. Similarly, when testing the nucleation overpotential of the non-metallic conductive layer, a negative electrode including a non-metallic conductive layer but excluding the alkali metal affinity layer can be prepared under the same process conditions for testing.

[0088] The nucleation overpotential V1 of the alkali metal affinity layer is related to the material of the alkali metal affinity layer, as well as parameters such as the thickness, areal density, and preparation process of the alkali metal affinity layer. By adjusting one or more of the above parameters, the desired nucleation overpotential V1 can be obtained.

[0089] The nucleation overpotential V2 of the non-metallic conductive layer is related to the material of the non-metallic conductive layer, as well as parameters such as its thickness, areal density, and fabrication process. By adjusting one or more of these parameters, the desired nucleation overpotential V2 can be obtained.

[0090] In some embodiments, the alkali metal affinity layer may include an alkali metal affinity material. During the initial charging of the battery, metal ions such as lithium ions and sodium ions can pass through the non-metallic conductive layer and land on the surface of the alkali metal affinity layer. They can form a large number of active sites in the alkali metal affinity layer by forming an alloy or solid solution with the alkali metal affinity material, or by a conversion reaction between the alkali metal affinity material and the alkali metal affinity material.

[0091] Taking lithium as the metal and cuprous oxide (Cu₂O) as the alkali metal affinity material as an example, the conversion reaction is as follows: Cu₂O + Li → Cu + Li₂O. The products of the conversion reaction can also serve as inorganic salts in the SEI film, thereby helping to improve the film quality of the SEI film on the negative electrode surface.

[0092] In some embodiments, the alkali metal affinity layer may include a lithiophilic material.

[0093] Alternatively, the lithiophilic material may include a lithiophilic metal element.

[0094] Optionally, the lithium-loving metal element may include one or more of Ag, Mg, Sn, Al, Bi, Au, In, Cu, and Zn.

[0095] In some embodiments, the lithiophilic material may include one or more of the following: elemental form, oxide, nitride, and phosphide of a lithiophilic metal element. For example, the lithiophilic material may include one or more of elemental Ag, elemental Mg, elemental Sn, elemental Al, elemental Bi, elemental Au, elemental In, silver oxide, magnesium oxide, aluminum oxide, bismuth oxide, cuprous oxide, zinc oxide, magnesium nitride, aluminum nitride, copper nitride, zinc nitride, copper phosphide, and zinc phosphide. Optionally, the lithiophilic material may include elemental Ag and elemental Bi.

[0096] In some embodiments, the alkali metal affinity layer may include a sodium-loving material.

[0097] Alternatively, sodium-loving materials may include sodium-loving metal elements.

[0098] Optionally, the sodium-loving metal element may include one or more of Ag, Mg, Sn, Cu, and Zn.

[0099] In some embodiments, the naphophilic material may include one or more of the following: elemental form, oxide, nitride, and phosphide of the naphophilic metal element. For example, the naphophilic material may include one or more of elemental Ag, elemental Mg, elemental Sn, silver oxide, magnesium oxide, cuprous oxide, zinc oxide, magnesium nitride, copper nitride, zinc nitride, copper phosphide, and zinc phosphide. Optionally, the naphophilic material may include elemental Ag.

[0100] In some embodiments, the non-metallic conductive layer may include a non-metallic conductive material.

[0101] Optionally, the non-metallic conductive material may include one or more of carbon-based conductive materials and phosphorus-based conductive materials.

[0102] Optionally, the non-metallic conductive material may include one or more of porous carbon, hard carbon, carbon nanotubes, red phosphorus, black phosphorus, and phosphorus-carbon composites.

[0103] In some embodiments, the total thickness of the modification layer can be 11μm-55μm, and optionally 13μm-53μm or 18μm-53μm.

[0104] In some embodiments, the thickness of the alkali metal affinity layer can be 1 μm-6 μm, and can be selected as 1 μm-5 μm, 1.5 μm-5 μm, 1.5 μm-4 μm, or 1.5 μm-3 μm.

[0105] Increasing the thickness of the alkali metal affinity layer provides more active sites, thus better inducing uniform metal deposition. However, it also increases the consumption of active ions during metal deposition, which can reduce battery capacity and affect cycle performance. Therefore, maintaining the thickness of the alkali metal affinity layer within the aforementioned range allows for both the provision of numerous active sites to induce uniform metal deposition and enhance battery reliability, and the reduction of active ion consumption, resulting in good cycle performance.

[0106] In some embodiments, the thickness of the non-metallic conductive layer can be 10μm-50μm, and can be selected as 15μm-50μm, 15μm-40μm, or 20μm-40μm.

[0107] Increasing the thickness of the non-metallic conductive layer increases the difference between its nucleation overpotential and that of the alkali metal affinity layer, thus increasing the driving force for lithium and sodium ions to penetrate the non-metallic conductive layer and reach the alkali metal affinity layer. However, this also increases the resistance to lithium and sodium ions penetrating the non-metallic conductive layer, leading to increased battery polarization and kinetic losses, which in turn affects the battery's cycle performance. Therefore, maintaining the thickness of the non-metallic conductive layer within the aforementioned range can increase the driving force for lithium and sodium ions to penetrate the non-metallic conductive layer and reach the alkali metal affinity layer, inducing uniform metal deposition. Furthermore, under pressure, the deposited lithium and sodium metals can grow uniformly between the non-metallic conductive layer and the negative electrode current collector, further reducing dendrite formation and minimizing electrolyte side reactions and active ion consumption. In addition, it can reduce the resistance of lithium and sodium ions penetrating the non-metallic conductive layer, reduce battery polarization, and decrease battery kinetic losses, resulting in better battery cycle performance.

[0108] In some embodiments, the areal density of the alkali metal affinity layer can be 1 g / m². 2 -8g / m 2 .

[0109] When the areal density of the alkali metal affinity layer is within the above range, it can provide a large number of active sites, induce uniform metal deposition, and enable the battery to have high reliability. On the other hand, it can also reduce the consumption of active ions, enabling the battery to have good cycle performance.

[0110] In some embodiments, the areal density of the non-metallic conductive layer may be 18 g / m². 2 -92g / m 2 .

[0111] When the areal density of the non-metallic conductive layer is within the aforementioned range, it can increase the driving force for metal ions such as lithium ions and sodium ions to pass through the non-metallic conductive layer and reach the alkali metal affinity layer, inducing uniform metal deposition. Under pressure, it can also cause the deposited lithium, sodium, and other metals to grow uniformly between the non-metallic conductive layer and the negative electrode current collector, further reducing dendrite formation and electrolyte side reactions and active ion consumption. In addition, it can reduce the resistance when metal ions such as lithium ions and sodium ions pass through the non-metallic conductive layer, giving the battery good cycle performance.

[0112] In some embodiments, the alkali metal affinity layer can be formed by processes such as electrodeposition, vapor deposition, magnetron sputtering, ion beam sputtering, and atomic layer deposition.

[0113] In some embodiments, the non-metallic conductive layer can be formed by processes such as electrodeposition, vapor deposition, magnetron sputtering, ion beam sputtering, and atomic layer deposition.

[0114] The parameters (e.g., thickness, areal density, etc.) of the aforementioned modifying layer, alkali metal affinity layer, and non-metallic conductive layer are all parameters of one side of the negative electrode current collector. When the modifying layer is disposed on both sides of the negative electrode current collector, if the parameters of either side satisfy the requirements of this application, it is considered to fall within the protection scope of this application.

[0115] In some embodiments, the negative current collector includes a metallic material, which may include one or more of copper, nickel, titanium, magnesium, aluminum, copper alloys, nickel alloys, titanium alloys, magnesium alloys, and aluminum alloys.

[0116] In some embodiments, the negative electrode current collector may include a metal foil or a three-dimensional porous current collector. Examples of three-dimensional porous current collectors include mesh metal structures and foam metal structures.

[0117] [Positive electrode plate]

[0118] A single battery cell includes a positive electrode plate.

[0119] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and comprising a positive electrode active material. For example, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0120] In some embodiments, the positive electrode active material includes a material capable of extracting and inserting lithium.

[0121] As examples, positive electrode active materials may include, but are 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 oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, lithium titanium oxides, 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, lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, lithium iron manganese phosphate and carbon composites, and their respective modified compounds.

[0122] In some embodiments, to further improve the energy density of the battery, the positive electrode active material may include materials with the general formula Li. a Ni b Co c M d O e D fOne or more of lithium transition metal oxides and their modified compounds. 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.

[0123] In some embodiments, the positive electrode active material may simultaneously comprise lithium transition metal oxide and lithium phosphate. This is advantageous for obtaining a battery that balances high capacity and high reliability.

[0124] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, and 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.

[0125] 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.

[0126] In some embodiments, as an example, the positive electrode active material may include, but is not limited to, NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, Na 0.67MO2 (M includes at least two of Fe, Co, Cr, Mn, Ni, V, Ti, and Mo), NaMO2 (M includes at least two of Fe, Co, Ni, V, Ti, and Mo), NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, Prussian white, and one or more of their respective modified compounds.

[0127] The modified compounds for the above-mentioned positive electrode active materials can be obtained by doping and / or surface coating of the positive electrode active materials.

[0128] In some embodiments, the positive electrode film may 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.

[0129] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene oxide, fluorinated acrylate resins, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0130] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0131] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, optional positive electrode conductive agents, optional positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to it.

[0132] [Electrolytes]

[0133] A single battery cell includes an electrolyte.

[0134] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0135] In some embodiments, the electrolyte includes anion, which may include bis(fluorosulfonyl)imide anion (FSI). - ), bis(trifluoromethanesulfonyl)imide anion (TFSI) - ), dioxaborate anion (BOB) - ), difluorooxalate borate anion (DFOB) - ), difluorodioxanol phosphate anion (DFOP) - ), tetrafluorooxalate phosphate anion (TFOP) - ), difluorophosphate anion (PO2F2) - ), hexafluorophosphate anion (PF6) - ), tetrafluoroborate anion (BF4) - ), hexafluoroarsenate anion (AsF6) - ), trifluoromethanesulfonate anion (CF3SO3) - One or more of the following.

[0136] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0137] In some embodiments, the concentration of the electrolyte salt may be 0.3 mol / L or higher, optionally 0.7 mol / L or higher, and further optionally 4 mol / L or lower, optionally 2.5 mol / L or lower, or 1.7 mol / L or lower. When the concentration of the electrolyte salt is within the above range, the electrolyte can have a suitable ionic conductivity.

[0138] Organic solvents may include, but are not limited to, one or more of esters, ethers, sulfones, and nitriles. Esters may include, but are not limited to, one or more of carbonates, phosphate esters, carboxylic esters, sulfate esters, and sulfonates. Carbonates may include cyclic carbonates and / or chain carbonates; optionally, carbonates may include both cyclic and chain carbonates. Chain carbonates may include low-viscosity polar chain carbonates, aliphatic branched carbonates, etc.

[0139] As an example, organic solvents may include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), butene carbonate, ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), dimethyl ether tetraethylene glycol (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL), trimethyl phosphate, 3-methoxypropionitrile, H(CF2)2OCH3, C4F9O CH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, H(CF2)2CH2O(CF2)2H, CF3CHFCF2OCH3, CF3CHFCF2OCH2CH3, 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyloctafluorobutyl methyl ether, 3-trifluoromethyloctafluorobutyl ethyl ether, 3-trifluoromethyloctafluorobutyl propyl ether, 4-trifluoromethyl One or more of the following: decafluoropentyl methyl ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether, 5-trifluoromethyl dodecylfluorohexyl methyl ether, 5-trifluoromethyl dodecylfluorohexyl ethyl ether, 5-trifluoromethyl dodecylfluorohexyl propyl ether, 6-trifluoromethyl tetradecafluoroheptyl methyl ether, 6-trifluoromethyl tetradecafluoroheptyl ethyl ether, 6-trifluoromethyl tetradecafluoroheptyl propyl ether, 7-trifluoromethyl hexadecylfluorooctyl methyl ether, 7-trifluoromethyl hexadecylfluorooctyl ethyl ether, and 7-trifluoromethyl hexadecylfluorooctyl propyl ether.

[0140] 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, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, additives that improve battery low-temperature power performance, etc.

[0141] [Isolation membrane]

[0142] A single battery cell may also include a separator. The separator is located between the positive and negative electrodes and mainly serves to prevent internal short circuits.

[0143] This application does not impose any particular restrictions on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0144] In some embodiments, the material of the separator may include, but is not limited to, one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.

[0145] Methods for preparing battery cells are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an 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 stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with the aforementioned electrolyte. After vacuum sealing, settling, and formation processes, a battery cell is obtained. Multiple battery cells can further be connected in series, parallel, or a combination thereof to form a battery module. Multiple battery modules can also be connected in series, parallel, or a combination thereof to form a battery pack. In some embodiments, multiple battery cells can also be directly assembled into a battery pack.

[0146] This application also provides an electrical device, which includes the battery provided in this application embodiment. 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, mobile devices (such as mobile phones, tablets, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0147] Electrical devices can choose the type of battery according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0148] Figure 8 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0149] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0150] Example

[0151] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0152] Example 1

[0153] Commercially available double-sided bright copper foil with a thickness of 8μm was first wiped with a 1mol / L acetic acid solution, then ultrasonically cleaned with ethanol and deionized water, and finally vacuum dried at 80℃.

[0154] After drying, the copper foil was cut into 4cm × 4cm samples and placed on the sample stage of the ion sputtering instrument. Sputtering was first performed using an Ag target with the following parameters: vacuum 3.0 Pa, current 30 mA, and sputtering time 2 min. After sputtering, air was introduced into the working chamber, the chamber door was opened, and the Ag target was replaced with a carbon target. The ion sputtering parameters were adjusted to: vacuum 3.0 Pa, current 60 mA, and sputtering time 4 min. After sputtering, air was introduced into the working chamber, and the sample was removed, yielding the negative electrode sheet.

[0155] Example 2

[0156] The preparation method of the negative electrode sheet is similar to that in Example 1, except that the sputtering time of the carbon target is 6 minutes.

[0157] Example 3

[0158] The preparation method of the negative electrode sheet is similar to that in Example 1, except that the sputtering time of the carbon target is 16 min.

[0159] Example 4

[0160] The preparation method of the negative electrode sheet is similar to that in Example 1, except that the sputtering time of the carbon target is 20 min.

[0161] Example 5

[0162] The preparation method of the negative electrode sheet is similar to that in Example 1, except that the sputtering time of the carbon target is 28 min.

[0163] Example 6

[0164] The preparation method of the negative electrode sheet is similar to that in Example 1, except that the sputtering time of Ag target is 40s and the sputtering time of carbon target is 16min.

[0165] Example 7

[0166] The preparation method of the negative electrode sheet is similar to that in Example 1, except that the sputtering time of Ag target is 3.3 min and the sputtering time of carbon target is 16 min.

[0167] Example 8

[0168] The preparation method of the negative electrode sheet is similar to that in Example 1, except that the sputtering time of the Ag target is 4.7 min and the sputtering time of the carbon target is 16 min.

[0169] Example 9

[0170] Commercially available double-sided bright copper foil with a thickness of 8μm was first wiped with a 1mol / L acetic acid solution, then ultrasonically cleaned with ethanol and deionized water, and finally vacuum dried at 80℃.

[0171] After drying, the copper foil was cut into 4cm × 4cm samples and placed on the sample stage of the ion sputtering instrument. Sputtering was first performed using a Bi target with the following parameters: vacuum 3.0 Pa, current 30 mA, and sputtering time 4 min. After sputtering, air was introduced into the working chamber, the chamber door was opened, and the Bi target was replaced with a carbon target. The ion sputtering parameters were adjusted to: vacuum 3.0 Pa, current 60 mA, and sputtering time 28 min. Finally, air was introduced into the working chamber, and the sample was removed, yielding the negative electrode sheet.

[0172] Example 10

[0173] Commercially available double-sided bright copper foil with a thickness of 8μm was first wiped with a 1mol / L acetic acid solution, then ultrasonically cleaned with ethanol and deionized water, and finally vacuum dried at 80℃.

[0174] After drying, the copper foil was cut into 4cm × 4cm samples and placed on the sample stage of the ion sputtering instrument. Sputtering was first performed using a Bi target with the following parameters: vacuum 3.0 Pa, current 30 mA, and sputtering time 4 min. After sputtering, air was introduced into the working chamber, the chamber door was opened, and the Bi target was replaced with a carbon target. The ion sputtering parameters were adjusted to: vacuum 3.0 Pa, current 60 mA, and sputtering time 16 min. After sputtering, air was introduced into the working chamber, and the sample was removed, yielding the negative electrode sheet.

[0175] Example 11

[0176] Commercially available double-sided bright copper foil with a thickness of 8μm was first wiped with a 1mol / L acetic acid solution, then ultrasonically cleaned with ethanol and deionized water, and finally vacuum dried at 80℃.

[0177] After drying, the copper foil was cut into 4cm × 4cm samples and placed on the sample stage of the ion sputtering instrument. Sputtering was first performed using an Ag target with the following parameters: vacuum 3.0 Pa, current 30 mA, and sputtering time 2 min. After sputtering, air was introduced into the working chamber, the chamber door was opened, and the Ag target was replaced with a phosphorus target. The ion sputtering parameters were adjusted to: vacuum 3.0 Pa, current 60 mA, and sputtering time 22 min. Finally, air was introduced into the working chamber, and the sample was removed, yielding the negative electrode sheet.

[0178] Example 12

[0179] Commercially available double-sided bright copper foil with a thickness of 8μm was first wiped with a 1mol / L acetic acid solution, then ultrasonically cleaned with ethanol and deionized water, and finally vacuum dried at 80℃.

[0180] After drying, the copper foil was cut into 4cm × 4cm samples and placed on the sample stage of the ion sputtering instrument. Sputtering was first performed using a silver oxide target with the following parameters: vacuum 3.0 Pa, current 30 mA, and sputtering time 1.5 min. After sputtering, air was introduced into the working chamber, the chamber door was opened, and the silver oxide target was replaced with a carbon target. The ion sputtering parameters were adjusted to: vacuum 3.0 Pa, current 60 mA, and sputtering time 16 min. Finally, air was introduced into the working chamber, and the sample was removed to obtain the negative electrode sheet.

[0181] Example 13

[0182] Commercially available double-sided bright copper foil with a thickness of 8μm was first wiped with a 1mol / L acetic acid solution, then ultrasonically cleaned with ethanol and deionized water, and finally vacuum dried at 80℃.

[0183] After drying, the copper foil was cut into 4cm × 4cm samples and placed on the sample stage of the ion sputtering instrument. Sputtering was first performed using a copper nitride target with the following parameters: vacuum 3.0 Pa, current 30 mA, and sputtering time 1.5 min. After sputtering, air was introduced into the working chamber, the chamber door was opened, and the copper nitride target was replaced with a carbon target. The ion sputtering parameters were adjusted to: vacuum 3.0 Pa, current 60 mA, and sputtering time 16 min. After sputtering, air was introduced into the working chamber, and the sample was removed, yielding the negative electrode.

[0184] Example 14

[0185] Commercially available double-sided bright copper foil with a thickness of 8μm was first wiped with a 1mol / L acetic acid solution, then ultrasonically cleaned with ethanol and deionized water, and finally vacuum dried at 80℃.

[0186] After drying, the copper foil was cut into 4cm × 4cm samples and placed on the sample stage of the ion sputtering instrument. Sputtering was first performed using a copper-phosphorus alloy target. The ion sputtering parameters were: vacuum 3.0 Pa, current 30 mA, and sputtering time 1.5 min. After sputtering, air was introduced into the working chamber, the chamber door was opened, and the copper-phosphorus alloy target was replaced with a carbon target. The ion sputtering parameters were adjusted to: vacuum 3.0 Pa, current 60 mA, and sputtering time 16 min. After sputtering, air was introduced into the working chamber, and the sample was removed, yielding the negative electrode sheet.

[0187] Comparative Example 1

[0188] The preparation method of the negative electrode sheet is similar to that in Example 1, except that no carbon target is sputtered.

[0189] Comparative Example 2

[0190] The preparation method of the negative electrode sheet is similar to that in Example 1, except that Ag target material was not sputtered.

[0191] Comparative Example 3

[0192] Commercially available double-sided bright copper foil with a thickness of 8μm was first wiped with a 1mol / L acetic acid solution, then ultrasonically cleaned with ethanol and deionized water, and finally vacuum dried at 80℃.

[0193] After drying, the copper foil was cut into 4cm × 4cm samples and placed on the sample stage of the ion sputtering instrument. Sputtering was first performed using an Fe target with the following parameters: vacuum 3.0 Pa, current 30 mA, and sputtering time 1.6 min. After sputtering, air was introduced into the working chamber, the chamber door was opened, and the Fe target was replaced with a carbon target. The ion sputtering parameters were adjusted to: vacuum 3.0 Pa, current 60 mA, and sputtering time 16 min. After sputtering, air was introduced into the working chamber, and the sample was removed, yielding the negative electrode sheet.

[0194] Comparative Example 4

[0195] Commercially available double-sided bright copper foil with a thickness of 8μm was first wiped with a 1mol / L acetic acid solution, then ultrasonically cleaned with ethanol and deionized water, and finally vacuum dried at 80℃.

[0196] After drying, the copper foil was cut into 4cm × 4cm samples and placed on the sample stage of the ion sputtering instrument. Sputtering was first performed using an Ag target with the following parameters: vacuum 3.0 Pa, current 30 mA, and sputtering time 2 min. After sputtering, air was introduced into the working chamber, the chamber door was opened, and the sample was removed. The sample was then placed in the deposition furnace, and a hydrogen-argon mixture was introduced as a protective gas. The furnace was heated to approximately 1000°C and held at this temperature for about 20 min. The hydrogen-argon mixture was then stopped, and methane gas was introduced instead. The reaction was allowed to complete after 30 min. The power was then cut off, the methane gas supply was stopped, and a hydrogen-argon mixture was introduced to purge the methane gas from the furnace tubes. The temperature was then lowered to approximately 25°C under the hydrogen-argon protective gas atmosphere, and the sample was removed, yielding the negative electrode. The volume ratio of hydrogen to argon in the hydrogen-argon mixture was 5:95.

[0197] Comparative Example 5

[0198] After drying, the copper foil was cut into 4cm × 4cm samples and placed on the sample stage of the ion sputtering instrument. Sputtering was first performed using a copper-phosphorus alloy target. The ion sputtering parameters were: vacuum 3.0 Pa, current 30 mA, and sputtering time 1.5 min. After sputtering, air was introduced into the working chamber, the chamber door was opened, and the copper-phosphorus alloy target was replaced with a carbon target. The ion sputtering parameters were adjusted to: vacuum 3.0 Pa, current 60 mA, and sputtering time 4 min. After sputtering, air was introduced into the working chamber, and the sample was removed, yielding the negative electrode sheet.

[0199] Performance testing

[0200] (1) Short-circuit time test

[0201] In an argon-protected glove box, a coin cell was assembled with a lithium metal sheet as the counter electrode and the aforementioned prepared negative electrode sheet. The electrolyte salt was LiFSI with a concentration of 1 mol / L, and the solvent was dimethyl ethylene glycol ether (DME). A 12 μm thick PE membrane was used as the separator.

[0202] After the assembled button cell was left to stand for 12 hours at 25°C, it was tested at 1 mA / cm². 2 The current density is constant current discharge until a short circuit signal appears, that is, the coin cell voltage jumps to 0V, and the time T from the start of discharge to the short circuit is recorded.

[0203] During testing, the number of button cell samples can be more than 6, and the average value of the test results is taken.

[0204] (2) Nucleation overpotential test

[0205] In an argon-protected glove box, a coin cell was assembled with a lithium metal sheet as the counter electrode and a negative electrode. The electrolyte salt was LiFSI with a concentration of 1 mol / L, and the solvent was dimethyl ethylene glycol ether (DME). A 12 μm thick PE membrane was used as the separator.

[0206] After the assembled button cell was left to stand for 12 hours at 25°C, it was tested at 1 mA / cm². 2 Constant current discharge to 1 mAh / cm 2 At the start of the lithium metal deposition process, there is a significant voltage drop followed by a flat voltage plateau. The difference between the voltage at the lowest point and the flat portion of the voltage plateau is taken as the nucleation overpotential of the negative electrode current collector.

[0207] The negative electrode sheets of Examples 1 to 14 and Comparative Examples 3 to 5 simultaneously include an alkali metal affinity layer and a non-metallic conductive layer. When testing the nucleation overpotential of the alkali metal affinity layer, the negative electrode sheets were prepared according to the same process conditions described above, but without sputtering carbon or phosphorus targets; that is, the negative electrode sheets did not have a non-metallic conductive layer. When testing the nucleation overpotential of the non-metallic conductive layer, the negative electrode sheets were prepared according to the same process conditions described above, but without sputtering Fe, Ag, Bi, silver oxide, copper nitride, or copper-phosphorus alloy targets; that is, the negative electrode sheets did not have an alkali metal affinity layer.

[0208] (3) Cyclic performance test

[0209] Lithium iron phosphate, conductive carbon black (Super P), and binder polyvinylidene fluoride (PVDF) are mixed evenly in an appropriate amount of solvent N-methylpyrrolidone (NMP) at a weight ratio of 8:1:1 to obtain a positive electrode slurry. The positive electrode slurry is coated onto the positive electrode current collector aluminum foil and dried to obtain the positive electrode sheet.

[0210] In an argon-protected glove box, the positive electrode and the prepared negative electrode were assembled into a coin cell. The electrolyte salt was LiFSI with a concentration of 1 mol / L, and the solvent was dimethyl ethylene glycol ether (DME). The separator was a 12 μm thick PE membrane.

[0211] At 25°C, after the assembled coin cells were left to stand for 12 hours, they were charged at a constant current of 0.2C to 3.65V, and then charged at a constant voltage of 3.65V to 0.05C. After the coin cells were left to stand for 10 minutes, they were discharged at a constant current of 0.5C to 2V. The coin cells were cycled 200 times according to the above method, and the number of cycles corresponding to when the discharge capacity was 50% of the discharge capacity of the first cycle was recorded.

[0212] During testing, the number of button cell samples can be more than 6, and the average value of the test results is taken.

[0213] Table 1 shows the test results of Examples 1 to 14 and Comparative Examples 1 to 5.

[0214] Table 1

[0215]

[0216] As shown in Table 1, by setting an alkali metal affinity layer and a non-metallic conductive layer on the surface of the negative electrode current collector, and controlling the difference between the nucleation overpotential V2 of the non-metallic conductive layer and the nucleation overpotential V1 of the alkali metal affinity layer to be greater than or equal to 40mV, uniform Li deposition can be induced, the battery short-circuit time can be extended, the side reactions of the electrolyte can be reduced, and the cycle performance of the battery can be improved.

[0217] The test results in Table 1 also show that by further adjusting the nucleation overpotential V2 of the non-metallic conductive layer, the nucleation overpotential V1 of the alkali metal affinity layer, and the range of the difference between the two V2-V1, the battery short-circuit time can be further extended and the battery cycle performance can be further improved.

[0218] The test results in Table 1 also show that by further adjusting the thickness of the alkali metal affinity layer and / or the thickness of the non-metallic conductive layer, the battery short-circuit time can be further extended and the battery cycle performance can be further improved.

[0219] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A negative electrode sheet, comprising a negative electrode current collector and a modifying layer located on at least one surface of the negative electrode current collector, characterized in that, The modification layer includes an alkali metal affinity layer and a non-metallic conductive layer located on the surface of the alkali metal affinity layer away from the negative electrode current collector; The nucleation overpotential of the alkali metal affinity layer is denoted as V1, and the nucleation overpotential of the non-metallic conductive layer is denoted as V2, both in mV, and V2-V1 is greater than or equal to 40mV.

2. The negative electrode sheet according to claim 1, characterized in that, V2-V1 ranges from 48mV to 121mV.

3. The negative electrode sheet according to claim 2, characterized in that, V2-V1 ranges from 57mV to 94mV.

4. The negative electrode sheet according to any one of claims 1-3, characterized in that, V1 is 0mV-40mV; and / or, V2 is 60mV-120mV.

5. The negative electrode sheet according to claim 4, characterized in that, V1 is 8mV-22mV; and / or, V2 is 78mV-110mV.

6. The negative electrode sheet according to any one of claims 1-3, characterized in that, The non-metallic conductive layer comprises a non-metallic conductive material.

7. The negative electrode sheet according to claim 6, characterized in that, The non-metallic conductive material includes one or more of carbon-based conductive materials and phosphorus-based conductive materials.

8. The negative electrode sheet according to claim 7, characterized in that, The non-metallic conductive material includes one or more of porous carbon, hard carbon, carbon nanotubes, red phosphorus, black phosphorus, and phosphorus-carbon composites.

9. The negative electrode sheet according to any one of claims 1-3, characterized in that, The alkali metal affinity layer includes a lithiophilic material.

10. The negative electrode sheet according to claim 9, characterized in that, The lithiophilic material includes a lithiophilic metal element.

11. The negative electrode sheet according to claim 10, characterized in that, The lithiophilic metal element includes one or more of Ag, Mg, Sn, Al, Bi, Au, In, Cu, and Zn.

12. The negative electrode sheet according to claim 10, characterized in that, The lithiophilic material includes one or more of the elemental form, oxide, nitride, and phosphide of the lithiophilic metal element.

13. The negative electrode sheet according to claim 12, characterized in that, The lithiophilic materials include one or more of the following: elemental Ag, elemental Mg, elemental Sn, elemental Al, elemental Bi, elemental Au, elemental In, silver oxide, magnesium oxide, aluminum oxide, bismuth oxide, cuprous oxide, zinc oxide, magnesium nitride, aluminum nitride, copper nitride, zinc nitride, copper phosphide, and zinc phosphide.

14. The negative electrode sheet according to any one of claims 1-3, characterized in that, The alkali metal affinity layer includes a sodium-loving material.

15. The negative electrode sheet according to claim 14, characterized in that, The sodium-loving material includes sodium-loving metal elements.

16. The negative electrode sheet according to claim 15, characterized in that, The sodium-loving metal element includes one or more of Ag, Mg, Sn, Cu, and Zn.

17. The negative electrode sheet according to claim 15, characterized in that, The sodium-loving material includes one or more of the sodium-loving metal element in its elemental form, oxide, nitride, or phosphide form.

18. The negative electrode sheet according to claim 17, characterized in that, The sodium-loving material includes one or more of elemental Ag, elemental Mg, elemental Sn, silver oxide, magnesium oxide, cuprous oxide, zinc oxide, magnesium nitride, copper nitride, zinc nitride, copper phosphide, and zinc phosphide.

19. The negative electrode sheet according to any one of claims 1-3, characterized in that, The total thickness of the modified layer is 11μm-55μm.

20. The negative electrode sheet according to claim 19, characterized in that, The total thickness of the modified layer is 18μm-53μm.

21. The negative electrode sheet according to any one of claims 1-3, characterized in that, The thickness of the alkali metal affinity layer is 1 μm-6 μm; and / or, The thickness of the non-metallic conductive layer is 10μm-50μm.

22. The negative electrode sheet according to claim 21, characterized in that, The thickness of the alkali metal affinity layer is 1 μm-5 μm; and / or, The thickness of the non-metallic conductive layer is 15μm-50μm.

23. The negative electrode sheet according to any one of claims 1-3, characterized in that, The areal density of the alkali metal affinity layer is 1 g / m³. 2 -8g / m 2 ; and / or, The areal density of the non-metallic conductive layer is 18 g / m³. 2 -92g / m 2 .

24. The negative electrode sheet according to any one of claims 1-3, characterized in that, The negative electrode current collector includes a metallic material, which includes one or more of copper, nickel, titanium, magnesium, aluminum, copper alloys, nickel alloys, titanium alloys, magnesium alloys, and aluminum alloys.

25. A single battery cell, characterized in that, The battery cell includes the negative electrode sheet according to any one of claims 1-24, and 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.

26. A battery, characterized in that, Includes the battery cell as described in claim 25.

27. An electrical appliance, characterized in that, Includes the battery of claim 26, the battery being used to provide electrical energy.

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