Porous negative pole piece and preparation method thereof, battery monomer, battery device and power utilization device

Abstract

The invention provides a porous negative pole piece and a preparation method thereof, a battery monomer, a battery device and a power utilization device. The porous negative pole piece comprises a porous polymer substrate, and the porous polymer substrate comprises a plurality of pores; the porous negative pole piece comprises a lithium metal layer, and the lithium metal layer is located on the edge wires on the surface of the porous polymer substrate in the thickness direction of the lithium metal layer and on the edge wires of internal pores of the porous polymer substrate. Or the porous negative pole piece comprises a lithium alloy layer, and the lithium alloy layer is positioned on the edge wires on the surface of the porous polymer substrate along the thickness direction of the lithium alloy layer and the edge wires of the internal pores of the porous polymer substrate. The porous negative pole piece is used in the battery monomer, so that the battery monomer has high mass energy density, high first coulombic efficiency and good cycle performance.

Description

Technical Field

[0001] This disclosure relates to a porous negative electrode sheet and its preparation method, a battery cell, a battery device, and an electrical device. Background Technology

[0002] To further improve the mass energy density of battery cells, porous polymers can be used as the negative electrode framework. Using a porous polymer framework can reduce the mass of the negative electrode and increase the surface area of ​​the internal pores, thereby reducing the current density, mitigating lithium dendrite growth, and providing expansion space for lithium deposition. However, porous polymer framework negative electrodes will reduce the initial coulombic efficiency of the battery cell, affecting its cycle performance. Summary of the Invention

[0003] This disclosure provides a porous negative electrode sheet and its preparation method, a battery cell, a battery device, and an electrical device. The porous negative electrode sheet, when used in a battery cell, enables the battery cell to have high energy density, high initial coulombic efficiency, and good cycle performance.

[0004] In a first aspect, this disclosure provides a porous negative electrode sheet, the porous negative electrode sheet comprising a porous polymer substrate, the porous polymer substrate comprising a plurality of pores; the porous negative electrode sheet comprising a lithium metal layer, the lithium metal layer being located on the ridges of the surface of the porous polymer substrate along its own thickness direction and on the ridges of the pores inside the porous polymer substrate; or, the porous negative electrode sheet comprising a lithium alloy layer, the lithium alloy layer being located on the ridges of the surface of the porous polymer substrate along its own thickness direction and on the ridges of the pores inside the porous polymer substrate.

[0005] A lithium metal layer or lithium alloy layer is present on the ridges of the porous polymer substrate along its thickness direction and on the ridges of the pores inside the porous polymer substrate. This lithium metal layer or lithium alloy layer pre-compensates the potential lithium intercalation of the porous polymer substrate, thereby enabling the battery cell using this porous negative electrode to have high initial coulombic efficiency and good cycle performance. The lithium metal layer or lithium alloy layer is located on both the ridges of the porous polymer substrate along its thickness direction and on the ridges of the pores inside the porous polymer substrate, which can further compensate for lithium loss caused by the formation of the solid electrolyte (SEI) film and the generation of dead lithium, thus enabling the battery cell to have high initial coulombic efficiency and good cycle performance. Therefore, the porous negative electrode provided in this disclosure, when used in battery cells, enables the battery cell to have high energy density, high initial coulombic efficiency, and good cycle performance.

[0006] In some embodiments, the porous polymer substrate is a nonwoven polymer fiber structure substrate or a porous foam polymer substrate.

[0007] In some embodiments, the material of the nonwoven polymer fiber structure substrate includes one or more of polyimide, polyvinylidene fluoride, polyacrylonitrile, polyethylene terephthalate, poly(p-phenylene terephthalate), polymethyl methacrylate, polyurethane, polystyrene, polyhexamethylene adipamide, polycaprolactam, polyetherimide, and their respective derivatives.

[0008] In some embodiments, the porous foam polymer substrate includes one or more of polyimide foam, polyethylene foam, polypropylene foam, polyurethane foam, polystyrene foam, melamine-formaldehyde foam, and polyvinyl alcohol foam.

[0009] In some embodiments, the porous negative electrode includes a lithium metal layer located on the ribs of the porous polymer substrate along its thickness direction and on the ribs of the pores inside the porous polymer substrate, and the microstructure of the lithium metal layer is nodular.

[0010] This can induce uniform lithium deposition, alleviate lithium dendrite growth, improve the electrolyte wettability of porous negative electrode sheets, and thus enhance the cycle performance of battery cells.

[0011] In some embodiments, the porous negative electrode includes a lithium metal layer located on the ribs of the porous polymer substrate along its thickness direction and on the ribs of the pores inside the porous polymer substrate, and the thickness of the lithium metal layer is 0.1 μm-1 μm.

[0012] When the thickness of the lithium metal layer is within the above range, the porous negative electrode sheet can have both high initial coulombic efficiency and high tensile and compressive strength.

[0013] In some embodiments, the porous negative electrode includes a lithium metal layer located on the ribs of the surface of the porous polymer substrate along its thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium metal layer also has a passivation layer, which includes Li2O.

[0014] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium metal layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium metal layer is located on the conductive metal layer, the conductive metal layer is close to the porous polymer substrate, and the lithium metal layer is far away from the porous polymer substrate.

[0015] In some embodiments, the conductive metal layer includes one or more of elemental Cu, Fe, Ni, Ti, and their alloys.

[0016] In some embodiments, the areal density of the conductive metal layer is 40 g / m². 2 -60g / m 2 .

[0017] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium metal layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium metal layer is located on the conductive metal layer. The conductive metal layer is close to the porous polymer substrate, and the lithium metal layer is far away from the porous polymer substrate. The lithium metal layer includes a plurality of lithium metal particles.

[0018] This can induce uniform lithium deposition, alleviate lithium dendrite growth, improve the electrolyte wettability of porous negative electrode sheets, and thus enhance the cycle performance of battery cells.

[0019] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium metal layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium metal layer is located on the conductive metal layer. The conductive metal layer is close to the porous polymer substrate, and the lithium metal layer is far away from the porous polymer substrate. The thickness of the lithium metal layer is 0.1 μm-1 μm.

[0020] When the thickness of the lithium metal layer is within the above range, the porous negative electrode sheet can have both high initial coulombic efficiency and high tensile and compressive strength.

[0021] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium metal layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium metal layer is located on the conductive metal layer, the conductive metal layer is close to the porous polymer substrate, and the lithium metal layer is far away from the porous polymer substrate. The lithium metal layer also has a passivation layer, which includes Li2O.

[0022] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium alloy layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium alloy layer is located on the conductive metal layer, with the conductive metal layer close to the porous polymer substrate and the lithium alloy layer away from the porous polymer substrate.

[0023] In some embodiments, the conductive metal layer includes one or more of elemental Cu, Fe, Ni, Ti, and their alloys.

[0024] In some embodiments, the areal density of the conductive metal layer is 40 g / m². 2 -60g / m 2 .

[0025] In some embodiments, the porous negative electrode sheet includes a conductive metal layer and a lithium alloy layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium alloy layer is located on the conductive metal layer, the conductive metal layer is close to the porous polymer substrate, and the lithium alloy layer is far away from the porous polymer substrate. The lithium alloy layer includes a plurality of lithium alloy particles.

[0026] This can induce uniform lithium deposition, alleviate lithium dendrite growth, improve the electrolyte wettability of porous negative electrode sheets, and thus enhance the cycle performance of battery cells.

[0027] In some embodiments, the porous negative electrode sheet includes a conductive metal layer and a lithium alloy layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium alloy layer is located on the conductive metal layer, the conductive metal layer is close to the porous polymer substrate, and the lithium alloy layer is far away from the porous polymer substrate. The lithium alloy layer includes the element Li and at least one element selected from Sn, Zn, Bi, Au, Ag, Al, Si, Mg, Pt, Pb, Be, Ga, In, Ge, Sb, and Te.

[0028] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium alloy layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium alloy layer is located on the conductive metal layer, the conductive metal layer is close to the porous polymer substrate, and the lithium alloy layer is far away from the porous polymer substrate. The thickness of the lithium alloy layer is 0.1 μm-2 μm.

[0029] When the thickness of the lithium alloy layer is within the above range, the porous negative electrode sheet can have both high initial coulombic efficiency and high tensile and compressive strength.

[0030] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium alloy layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium alloy layer is located on the conductive metal layer, the conductive metal layer is close to the porous polymer substrate, and the lithium alloy layer is far away from the porous polymer substrate. The lithium alloy layer also has a passivation layer, which includes Li2O.

[0031] In some embodiments, the thickness of the porous negative electrode sheet is 50μm-100μm.

[0032] In some embodiments, the porosity of the porous negative electrode sheet is 85%-95%.

[0033] In some embodiments, the pore size distribution range of the porous negative electrode sheet is 4μm-12μm.

[0034] In some embodiments, the porosity of the porous negative electrode sheet is greater than or equal to 99%.

[0035] In some embodiments, the diameter distribution of the ribs of the porous negative electrode sheet ranges from 0.5 μm to 2.5 μm.

[0036] Secondly, this disclosure provides a method for preparing a porous negative electrode sheet, comprising the following steps: providing a porous polymer substrate, the porous polymer substrate comprising a plurality of pores; and forming a lithium metal layer on the ribs of the surface of the porous polymer substrate along its thickness direction and on the ribs of the pores inside the porous polymer substrate by a lithium evaporation plating process.

[0037] In some embodiments, the method for preparing the porous negative electrode sheet includes the following steps: providing a porous polymer substrate, the porous polymer substrate including a plurality of pores, and having conductive metal layers on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate; and forming a lithium metal layer on the conductive metal layer on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the conductive metal layer on the ribs of the pores inside the porous polymer substrate by a lithium evaporation plating process.

[0038] In some embodiments, the method for preparing the porous negative electrode sheet includes the following steps: providing a porous polymer substrate, the porous polymer substrate including a plurality of pores, and having a conductive metal layer and a lithiophilic layer on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate, the conductive metal layer being located between the lithiophilic layer and the porous polymer substrate, and reacting lithium metal with the lithiophilic layer on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the lithiophilic layer on the ribs of the pores inside the porous polymer substrate through an evaporation lithium plating process to form a lithium alloy layer.

[0039] In some embodiments, the lithiophilic layer comprises one or more of the elemental Sn, Zn, Bi, Au, Ag, Al, Si, Mg, Pt, Pb, Be, Ga, In, Ge, Sb, and Te, and their alloys.

[0040] In some embodiments, the areal density of the lithiophilic layer is 2 g / m³. 2 -3g / m 2 .

[0041] In some embodiments, the conductive metal layer includes one or more of elemental Cu, Fe, Ni, Ti, and their alloys.

[0042] In some embodiments, the areal density of the conductive metal layer is 40 g / m². 2 -60g / m 2 .

[0043] In some embodiments, the deposition rate of the evaporative lithium plating process is less than or equal to 5 angstroms / second.

[0044] In some embodiments, the preparation method further includes a passivation treatment step after the lithium evaporation plating step.

[0045] In some embodiments, the passivation treatment is performed in an oxygen-containing atmosphere, an inert gas atmosphere, or a carbon dioxide atmosphere.

[0046] Thirdly, this disclosure provides a battery cell including a positive electrode sheet, a separator, and a porous negative electrode sheet according to the first aspect or a porous negative electrode sheet prepared by the preparation method of the second aspect, wherein the separator is disposed between the positive electrode sheet and the porous negative electrode sheet.

[0047] Fourthly, this disclosure provides a battery device comprising a plurality of battery cells according to the third aspect of this disclosure.

[0048] Fifthly, this disclosure provides an electrical device that includes a battery cell according to the third aspect of this disclosure or a battery device according to the fourth aspect of this disclosure. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0050] Figure 1 A schematic diagram of a battery cell provided in some embodiments of this disclosure is shown.

[0051] Figure 2 A schematic diagram of an electrical device provided in some embodiments of this disclosure is shown.

[0052] Figure 3 This image shows a scanning electron microscope (SEM) image of a commercially available nonwoven polyimide fiber membrane.

[0053] Figure 4 and Figure 5 The image shows a scanning electron microscope (SEM) image of the porous negative electrode sheet prepared in Example 1.

[0054] Figure 6 The image shows a scanning electron microscope (SEM) image of the porous negative electrode sheet prepared in Example 2.

[0055] Figure 7 The image shows a scanning electron microscope (SEM) image of the porous negative electrode sheet prepared in Example 3. Detailed Implementation

[0056] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the porous negative electrode sheet and its preparation method, battery cell, battery device, and power-consuming device of this disclosure. 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 for a full understanding of this disclosure by those skilled in the art and are not intended to limit the subject matter of the claims.

[0057] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the 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 expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​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 disclosure, 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.

[0058] Unless otherwise specified, all embodiments and optional embodiments of this disclosure may be combined with each other to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0059] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0060] Unless otherwise specified, all steps in this disclosure 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 mention that the method may also include step (c) indicates 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.

[0061] Unless otherwise specified, in this disclosure, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0062] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0063] In the description of the embodiments of this disclosure, 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" of the second feature 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.

[0064] Unless otherwise stated, the test temperature for all parameters mentioned in this disclosure is 25°C.

[0065] The battery cells mentioned in the embodiments of this disclosure are capable of charging and discharging independently. The battery cells may be cylindrical, cuboid, or other shapes, and this disclosure does not limit this. Figure 1 The example shown is a rectangular battery cell 5.

[0066] The battery apparatus mentioned in the embodiments of this disclosure may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0067] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0068] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0069] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0070] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0071] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0072] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0073] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0074] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0075] The technical solutions described in this disclosure are applicable to various electrical devices that use battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., 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. Battery cells and battery devices are used to store or provide electrical energy.

[0076] Figure 2 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, etc.

[0077] The battery cell provided in the embodiments of this disclosure includes an electrode assembly and an electrolyte. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this disclosure are not limited in this regard.

[0078] The battery cell also includes an outer packaging, which encapsulates the electrode components and electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. It can also be a flexible package, such as a pouch. The material of the flexible package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0079] In view of the problems in the background technology, this disclosure provides a porous negative electrode sheet, which, when used in a battery cell, enables the battery cell to have high energy density, high initial coulombic efficiency and good cycle performance.

[0080] The porous negative electrode sheet provided in this disclosure includes a porous polymer substrate, the porous polymer substrate including a plurality of pores; the porous negative electrode sheet includes a lithium metal layer, the lithium metal layer being located on the ridges of the surface of the porous polymer substrate along its own thickness direction and on the ridges of the pores inside the porous polymer substrate; or, the porous negative electrode sheet includes a lithium alloy layer, the lithium alloy layer being located on the ridges of the surface of the porous polymer substrate along its own thickness direction and on the ridges of the pores inside the porous polymer substrate.

[0081] Porous negative electrode sheets include a porous polymer substrate, which can reduce the mass of the negative electrode and increase the mass energy density of the battery cell.

[0082] The porous polymer substrate contains multiple pores, which can reduce the current density of the negative electrode, alleviate the growth of lithium dendrites, and provide expansion space for lithium deposition.

[0083] A lithium metal layer or lithium alloy layer is provided on the ribs on the surface of the porous polymer substrate along its thickness direction and on the ribs in the pores inside the porous polymer substrate. This lithium metal layer or lithium alloy layer pre-fills the potential lithium intercalation amount of the porous polymer substrate, thereby enabling the battery cell using this porous negative electrode to have high initial coulombic efficiency and good cycle performance.

[0084] The lithium metal layer or lithium alloy layer is located on the ridges of the porous polymer substrate along its thickness direction and on the ridges of the pores inside the porous polymer substrate. This can better compensate for lithium loss caused by the formation of the solid electrolyte (SEI) film and the generation of dead lithium in the negative electrode, thereby enabling the battery cell to have high initial coulombic efficiency and good cycle performance.

[0085] Therefore, the porous negative electrode sheet provided in this disclosure, when used in a battery cell, enables the battery cell to have high energy density, high initial coulombic efficiency, and good cycle performance.

[0086] In some embodiments, the porous polymer substrate can be a nonwoven polymer fiber structure substrate or a porous foam polymer substrate. The nonwoven polymer fiber structure refers to a porous polymer structure obtained through an electrospinning process.

[0087] In some embodiments, the material of the nonwoven polymer fiber structure substrate may include one or more of polyimide, polyvinylidene fluoride, polyacrylonitrile, polyethylene terephthalate, poly(p-phenylene terephthalamide), polymethyl methacrylate, polyurethane, polystyrene, polyhexamethylene adipamide, polycaprolactam, polyetherimide, and their respective derivatives. Derivatives refer to products derived from the substitution of hydrogen atoms or groups of atoms in the polymer by other atoms or groups of atoms.

[0088] In some embodiments, the porous foam polymer substrate may include one or more of polyimide foam, polyethylene foam, polypropylene foam, polyurethane foam, polystyrene foam, melamine-formaldehyde foam, and polyvinyl alcohol foam.

[0089] In some embodiments, the porous negative electrode includes a lithium metal layer located on the ribs of the surface of the porous polymer substrate along its thickness direction and on the ribs of the pores inside the porous polymer substrate.

[0090] At this point, the lithium metal layer serves as both a conductive layer and a lithium replenishment layer.

[0091] In some embodiments, the porous negative electrode includes a lithium metal layer located on the ribs of the surface of the porous polymer substrate along its thickness direction and on the ribs of the pores inside the porous polymer substrate, and the microstructure of the lithium metal layer is nodular.

[0092] This can induce uniform lithium deposition, alleviate lithium dendrite growth, improve the electrolyte wettability of porous negative electrode sheets, and thus enhance the cycle performance of battery cells.

[0093] In some embodiments, the porous negative electrode includes a lithium metal layer located on the ribs of the porous polymer substrate along its thickness direction and on the ribs of the pores inside the porous polymer substrate. The thickness of the lithium metal layer can be 0.1 μm to 1 μm, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, or any range of the above values.

[0094] When the thickness of the lithium metal layer is within the above range, the porous negative electrode sheet can have both high initial coulombic efficiency and high tensile and compressive strength.

[0095] Optionally, the thickness of the lithium metal layer can be 0.2μm-1μm, 0.3μm-1μm, 0.4μm-1μm, or 0.5μm-1μm.

[0096] In some embodiments, the porous negative electrode includes a lithium metal layer located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium metal layer may also have a passivation layer, which may optionally include Li2O.

[0097] Optionally, the microstructure of the lithium metal layer is nodular, and the passivation layer can be located on the surface of the nodular lithium metal.

[0098] Alternatively, the passivation layer is obtained by passivating the lithium metal layer.

[0099] A dense passivation layer can be obtained by artificially passivating the lithium metal layer, thereby improving the storage performance of porous negative electrode sheets.

[0100] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium metal layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium metal layer is located on the conductive metal layer, with the conductive metal layer close to the porous polymer substrate and the lithium metal layer away from the porous polymer substrate.

[0101] In some embodiments, the conductive metal layer may include one or more of elemental Cu, Fe, Ni, Ti and their alloys.

[0102] In some embodiments, the areal density of the conductive metal layer may be 40 g / m². 2 -60g / m 2 .

[0103] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium metal layer. The conductive metal layer is located on the ribs of the porous polymer substrate along its thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium metal layer is located on the conductive metal layer, with the conductive metal layer close to the porous polymer substrate and the lithium metal layer away from the porous polymer substrate. The lithium metal layer includes multiple lithium metal particles. That is, the microstructure of the lithium metal layer is granular, and multiple lithium metal particles are present on the ribs, and the accumulation of multiple lithium metal particles forms the lithium metal layer.

[0104] This can induce uniform lithium deposition, alleviate lithium dendrite growth, improve the electrolyte wettability of porous negative electrode sheets, and thus enhance the cycle performance of battery cells.

[0105] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium metal layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium metal layer is located on the conductive metal layer, with the conductive metal layer close to the porous polymer substrate and the lithium metal layer away from the porous polymer substrate. The thickness of the lithium metal layer can be 0.1 μm-1 μm, for example, it can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, or any range of the above values.

[0106] When the thickness of the lithium metal layer is within the above range, the porous negative electrode sheet can have both high initial coulombic efficiency and high tensile and compressive strength.

[0107] Optionally, the thickness of the lithium metal layer can be 0.2μm-1μm, 0.3μm-1μm, 0.4μm-1μm, or 0.5μm-1μm.

[0108] Optionally, the lithium metal layer may also have a passivation layer, which may include Li2O.

[0109] Optionally, the lithium metal layer comprises multiple lithium metal particles, and the passivation layer may be located on the surface of the lithium metal particles.

[0110] Alternatively, the passivation layer is obtained by passivating the lithium metal layer.

[0111] A dense passivation layer can be obtained by artificially passivating the lithium metal layer, thereby improving the storage performance of porous negative electrode sheets.

[0112] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium alloy layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium alloy layer is located on the conductive metal layer, with the conductive metal layer close to the porous polymer substrate and the lithium alloy layer away from the porous polymer substrate.

[0113] In some embodiments, the conductive metal layer may include one or more of elemental Cu, Fe, Ni, Ti and their alloys.

[0114] In some embodiments, the areal density of the conductive metal layer may be 40 g / m². 2 -60g / m 2 .

[0115] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium alloy layer. The conductive metal layer is located on the ribs of the porous polymer substrate along its thickness direction and on the ribs of the internal pores of the porous polymer substrate. The lithium alloy layer is located on the conductive metal layer, close to the porous polymer substrate and far from the porous polymer substrate. The lithium alloy layer includes multiple lithium alloy particles. That is, the microstructure of the lithium alloy layer is granular, and multiple lithium alloy particles are present on the ribs, and the accumulation of multiple lithium alloy particles forms the lithium alloy layer.

[0116] This can induce uniform lithium deposition, alleviate lithium dendrite growth, improve the electrolyte wettability of porous negative electrode sheets, and thus enhance the cycle performance of battery cells.

[0117] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium alloy layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium alloy layer is located on the conductive metal layer, with the conductive metal layer close to the porous polymer substrate and the lithium alloy layer away from the porous polymer substrate. The lithium alloy layer may include the element Li and at least one element selected from Sn, Zn, Bi, Au, Ag, Al, Si, Mg, Pt, Pb, Be, Ga, In, Ge, Sb, and Te.

[0118] These metallic elements have a good affinity for lithium, which can induce uniform lithium metal deposition, alleviate dendrite growth, and further improve the cycle performance of battery cells.

[0119] Optionally, the lithium alloy layer may include the element Li and at least one element selected from Sn, Zn, Bi, Au, Ag, Al, Si, and Mg.

[0120] Alternatively, the lithium alloy layer may include element Li and at least one element selected from Sn, Bi, Au, and Ag.

[0121] In some embodiments, the alloying material in the lithium alloy layer can be one or more.

[0122] In some embodiments, the lithium alloy layer may further include an elemental metal.

[0123] In some embodiments, the lithium alloy layer may include an alloy of Li with at least one element selected from Sn, Zn, Bi, Au, Ag, Al, Si, Mg, Pt, Pb, Be, Ga, In, Ge, Sb, and Te.

[0124] Optionally, the lithium alloy layer may also include at least one element selected from Sn, Zn, Bi, Au, Ag, Al, Si, Mg, Pt, Pb, Be, Ga, In, Ge, Sb, and Te.

[0125] In some embodiments, the lithium alloy layer may include one or more of the following: Li-Sn alloy, Li-Zn alloy, Li-Bi alloy, Li-Au alloy, Li-Ag alloy, Li-Al alloy, Li-Si alloy, Li-Mg alloy, Li-Pt alloy, Li-Pb alloy, Li-Be alloy, Li-Ga alloy, Li-In alloy, Li-Ge alloy, Li-Sb alloy, and Li-Te alloy.

[0126] It should be noted that a single alloying material in the lithium alloy layer can be composed of multiple alloy phases. Taking a Li-Bi alloy as an example, the lithium alloy layer may include one or both of LiBi and Li3Bi, and may also include elemental Bi. Taking a Li-Sn alloy as an example, the lithium alloy layer may include one or both of LiSn and Li7Sn3, and may also include elemental Sn.

[0127] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium alloy layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium alloy layer is located on the conductive metal layer, with the conductive metal layer close to the porous polymer substrate and the lithium alloy layer away from the porous polymer substrate. The thickness of the lithium alloy layer can be 0.1μm-2μm, for example, it can be 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, or any range of the above values.

[0128] When the thickness of the lithium alloy layer is within the above range, the porous negative electrode sheet can have both high initial coulombic efficiency and high tensile and compressive strength.

[0129] Optionally, the thickness of the lithium alloy layer can be 0.3μm-2μm, 0.3μm-1.8μm, 0.3μm-1.5μm, 0.3μm-1.2μm, 0.3μm-1μm, 0.5μm-2μm, 0.5μm-1.8μm, 0.5μm-1.5μm, 0.5μm-1.2μm, or 0.5μm-1μm.

[0130] In some embodiments, the porous negative electrode includes a conductive metal layer and a lithium alloy layer. The conductive metal layer is located on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate. The lithium alloy layer is located on the conductive metal layer. The conductive metal layer is close to the porous polymer substrate, and the lithium alloy layer is far away from the porous polymer substrate. The lithium alloy layer may also have a passivation layer. Optionally, the passivation layer may include Li2O.

[0131] Optionally, the lithium alloy layer comprises multiple lithium alloy particles, and the passivation layer may be located on the surface of the lithium alloy particles.

[0132] Alternatively, the passivation layer is obtained by passivating the lithium alloy layer.

[0133] A dense passivation layer can be obtained by artificially passivating the lithium alloy layer, thereby improving the storage performance of porous negative electrode sheets.

[0134] In some embodiments, the thickness of the porous negative electrode sheet can be 50μm-100μm.

[0135] In some embodiments, the porosity of the porous negative electrode sheet can be 85%-95%. This can reduce the current density of the negative electrode, alleviate the growth of lithium dendrites, and provide expansion space for lithium deposition.

[0136] In some embodiments, the pore size distribution range of the porous negative electrode sheet can be 4μm-12μm.

[0137] In some embodiments, the porosity of the porous negative electrode sheet can be greater than or equal to 99%.

[0138] In some embodiments, the diameter distribution of the prisms in the porous negative electrode sheet can range from 0.5 μm to 2.5 μm.

[0139] This disclosure also provides a method for preparing a porous negative electrode sheet, which can prepare the porous negative electrode sheet provided in this disclosure.

[0140] In some embodiments, the method for preparing a porous negative electrode sheet includes the following steps: providing a porous polymer substrate, the porous polymer substrate including a plurality of pores; and forming a lithium metal layer on the ribs of the surface of the porous polymer substrate along its own thickness direction and on the ribs of the pores inside the porous polymer substrate by a lithium evaporation plating process.

[0141] Evaporation lithium plating is a process in which raw lithium (such as lithium sheets or lithium ingots) is melted and evaporated into gaseous particles under vacuum by heating and evaporation, and then deposited on a substrate.

[0142] Optionally, the lithium metal layer has a nodular microstructure. The porous polymer substrate has a weak binding force to lithium, and during the evaporation lithium plating process, lithium deposition and accumulation occur in small areas, resulting in a nodular microstructure of the lithium metal layer.

[0143] Optionally, the deposition rate of the evaporative lithium plating process can be less than or equal to 5 angstroms / second. More preferably, the deposition rate of the evaporative lithium plating process can be less than or equal to 2 angstroms / second.

[0144] In the evaporation lithium plating process, gaseous lithium is directly deposited on a porous polymer substrate to form a lithium metal layer. Using a lower plating rate is beneficial for forming a denser and more uniform lithium metal layer.

[0145] In other embodiments, the method for preparing a porous negative electrode sheet includes the following steps: providing a porous polymer substrate, the porous polymer substrate including a plurality of pores, and having conductive metal layers on the ridges of the surface of the porous polymer substrate along its own thickness direction and on the ridges of the pores inside the porous polymer substrate; and forming a lithium metal layer on the conductive metal layer on the ridges of the surface of the porous polymer substrate along its own thickness direction and on the conductive metal layer on the ridges of the pores inside the porous polymer substrate by a lithium evaporation plating process.

[0146] Optionally, the microstructure of the lithium metal layer is granular, in which case there are multiple lithium metal particles on the filaments, and the accumulation of multiple lithium metal particles forms the lithium metal layer.

[0147] Optionally, the deposition rate of the evaporative lithium plating process can be less than or equal to 5 angstroms / second. More preferably, the deposition rate of the evaporative lithium plating process can be less than or equal to 2 angstroms / second.

[0148] Using a lower deposition rate during the evaporation lithium plating process is beneficial for forming a denser and more uniform lithium metal layer.

[0149] In some other embodiments, the method for preparing a porous negative electrode sheet includes the following steps: providing a porous polymer substrate, the porous polymer substrate including multiple pores, and having a conductive metal layer and a lithiophilic layer on the ridges of the surface of the porous polymer substrate along its own thickness direction and on the ridges of the pores inside the porous polymer substrate, the conductive metal layer being located between the lithiophilic layer and the porous polymer substrate, and reacting lithium metal with the lithiophilic layer on the ridges of the surface of the porous polymer substrate along its own thickness direction and on the lithiophilic layer on the ridges of the pores inside the porous polymer substrate through an evaporation lithium plating process to form a lithium alloy layer.

[0150] Optionally, the microstructure of the lithium alloy layer is granular, in which case there are multiple lithium alloy particles on the filaments, and the accumulation of multiple lithium alloy particles forms the lithium alloy layer.

[0151] Optionally, the deposition rate of the evaporative lithium plating process can be less than or equal to 5 angstroms / second. More preferably, the deposition rate of the evaporative lithium plating process can be less than or equal to 2 angstroms / second.

[0152] During the evaporation lithium plating process, gaseous lithium reacts with the lithiophilic layer and forms a lithium alloy layer in situ on the prism. Using a lower plating rate is beneficial for forming a denser and more uniform lithium alloy layer.

[0153] Battery cells using porous polymer framework anodes exhibit low initial coulombic efficiency. Lithium supplementation of the anode can improve this initial efficiency. Depending on the method, lithium supplementation can be categorized into physical, chemical, and electrochemical methods. Chemical supplementation carries inherent risks and toxicity, while electrochemical supplementation is complex; therefore, these two methods are rarely used in industrial production. Currently, physical supplementation is the most widely used industrial method, which includes melt-coating and lithium foil rolling. Porous polymer frameworks have poor heat resistance; melt-coating supplementation may damage the internal functional group structure, leading to irreversible changes in the physical and chemical properties of the porous polymer framework. Lithium foil rolling supplementation only forms a lithium metal layer on the surface of the porous polymer framework, failing to fully utilize the porous structure.

[0154] This disclosure describes a lithium metal layer or lithium alloy layer formed on the ridges of the surface along the thickness direction of a porous polymer substrate and on the ridges of the internal pores of the porous polymer substrate using an evaporation lithium plating process. The lithium deposition temperature of the evaporation lithium plating process is less than 50°C, thus not affecting the physical and chemical properties of the porous polymer substrate. Furthermore, the evaporation lithium plating process allows for the simultaneous formation of lithium metal or lithium alloy layers on both the ridges of the surface along the thickness direction of the porous polymer substrate and on the ridges of the internal pores of the porous polymer substrate.

[0155] By pre-complementing the potential lithium intercalation amount of the porous polymer substrate through the evaporation lithium plating process, the battery cell using this porous negative electrode can have high initial coulombic efficiency and good cycle performance.

[0156] The evaporation lithium plating process also pre-fills the potential lithium-affinity layer alloying capacity, thereby reducing the lithium consumed by the lithium-affinity layer during the use of the battery cell. This allows the battery cell using this porous negative electrode to have high initial coulombic efficiency and good cycle performance.

[0157] In some embodiments, the lithium heating and evaporation method in the evaporation lithium plating process may include electron gun beam heating, resistance wire heating, laser heating, high-frequency heating, etc.

[0158] In some embodiments, the lithiophilic layer may include one or more of the elemental Sn, Zn, Bi, Au, Ag, Al, Si, Mg, Pt, Pb, Be, Ga, In, Ge, Sb, and Te, and their alloys.

[0159] In some embodiments, the areal density of the lithiophilic layer can be 2 g / m². 2 -3g / m 2 .

[0160] In some embodiments, the process of forming a conductive metal layer on the ribs of the surface of the porous polymer substrate along its thickness direction and on the ribs of the pores inside the porous polymer substrate may include electroplating, physical vapor deposition (such as magnetron sputtering), or a combination of electroplating and physical vapor deposition.

[0161] In some embodiments, the conductive metal layer may include one or more of elemental Cu, Fe, Ni, Ti and their alloys.

[0162] In some embodiments, the areal density of the conductive metal layer may be 40 g / m². 2 -60g / m 2 .

[0163] In some embodiments, the method for preparing porous negative electrode sheets may further include a passivation treatment step after the evaporation and lithium plating step.

[0164] In some embodiments, the passivation treatment can be performed in an oxygen-containing atmosphere, an inert gas atmosphere, or a carbon dioxide atmosphere. Optionally, the inert gas may include one or more of nitrogen, argon, and helium.

[0165] The oxygen-containing atmosphere may include oxygen and an inert gas. Optionally, the oxygen-containing atmosphere may be a mixture of air and an inert gas. Optionally, the inert gas may include one or more of nitrogen, argon, and helium.

[0166] In some embodiments, passivation can be performed in an oxygen-containing atmosphere.

[0167] Passivation using an oxygen-containing atmosphere can form a denser oxide passivation layer on the surface of the lithium metal layer or lithium alloy layer, thereby reducing the oxidation and corrosion of lithium in the air and further improving the storage performance of the porous negative electrode.

[0168] Optionally, the volume fraction of oxygen in the oxygen-containing atmosphere can be 20%-70%, more preferably 30%-70%, 30%-60%, 35%-60%, 35%-55%, or 40%-50%.

[0169] This disclosure also provides a battery cell, which includes a porous negative electrode sheet provided in this disclosure, or a porous negative electrode sheet prepared by the preparation method provided in this disclosure.

[0170] The battery cell also includes a positive electrode, a separator, and an electrolyte, with the separator positioned between the positive electrode and the porous negative electrode.

[0171] [Positive electrode plate]

[0172] 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, the positive electrode film layer comprising a positive 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.

[0173] In some embodiments, the positive current collector may be a metal foil or a composite current collector. The metal foil may be a pure metal, an alloy, or a surface-treated metal; for example, aluminum foil may be used. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. For 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. For example, the polymer substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene.

[0174] In some embodiments, the positive electrode active material includes a material capable of extracting and inserting lithium. Optionally, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, 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, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds.

[0175] In some embodiments, to further improve the energy density of a single battery cell, the positive electrode active material may include materials of the general formula Li. a Ni b Co c M d O e A f One 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 one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A may include one or more of N, F, S and Cl.

[0176] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811), LiNi 0.83 Mn 0.08 Co 0.07 O2 (abbreviated as Ni83), LiNi 0.90 Mn 0.05 Co 0.05 O2 (abbreviated as Ni90), LiNi 0.94 Mn 0.03 Co 0.03 O2 (abbreviated as Ni94), LiNi 0.96 Co 0.02 Mn 0.02 O2 (abbreviated as Ni96), LiNi 0.80 Co 0.15 Al 0.05 One or more of O2, LiFePO4, LiMnPO4 and their respective modified compounds.

[0177] During the charging and discharging process, lithium (Li) undergoes insertion / extraction and consumption within a single battery cell, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar Li content represents the initial state of the material, i.e., the state before material addition. As the positive electrode active material is applied to the battery cell, the molar Li content changes after charge-discharge cycles. Similarly, the molar O content in the examples of positive electrode active materials in this disclosure is only a theoretical value. Oxygen release from the crystal lattice causes changes in the molar O content, leading to fluctuations in the actual molar O content.

[0178] 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.

[0179] In some embodiments, the positive electrode film layer may further include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0180] In some embodiments, the positive electrode film may further include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0181] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, positive conductive agent, positive binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0182] [Isolation membrane]

[0183] A separator can be disposed between the positive electrode and the porous negative electrode, primarily serving to prevent internal short circuits. This disclosure does not impose any particular limitation on the type of separator; any known porous membrane with good chemical and mechanical stability can be selected. In some embodiments, the separator material may include, but is not limited to, one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and polyimide. The separator can 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. The separator can be a single component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be coated on the surface of the separator.

[0184] [Electrolytes]

[0185] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0186] In some embodiments, the electrolyte salt may be one or more of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium di(oxalate borate) (LiBOB), lithium difluorooxalate borate (LiDFOB), lithium difluorodi(oxalate phosphate) (LiDFOP), lithium tetrafluorooxalate phosphate (LiTFOP), lithium difluorophosphate (LiPO2F2), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), and lithium trifluoromethanesulfonate (LiCF3SO3).

[0187] In some embodiments, the concentration of the electrolyte salt can 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.

[0188] 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.

[0189] As an example, organic solvents may include, but are not limited to, dimethyl ether tetraethylene glycol (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL), trimethyl phosphate, 3-methoxypropionitrile, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), H(CF2)2OCH3, C4F9OCH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, CF3CHFCF2OCH3, CF3CHFCF2OCH2CH3, 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethyl One or more of the following: hexafluoropropyl 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-trifluoromethyldodecylfluorohexyl methyl ether, 5-trifluoromethyldodecylfluorohexyl ethyl ether, 5-trifluoromethyldodecylfluorohexyl propyl ether, 6-trifluoromethyltetradecylfluoroheptyl methyl ether, 6-trifluoromethyltetradecylfluoroheptyl ethyl ether, 6-trifluoromethyltetradecylfluoroheptyl propyl ether, 7-trifluoromethylhexadecylfluorooctyl methyl ether, 7-trifluoromethylhexadecylfluorooctyl ethyl ether, and 7-trifluoromethylhexadecylfluorooctyl propyl ether.

[0190] In some embodiments, the electrolyte may also include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve overcharge performance, additives that improve high-temperature performance, additives that improve low-temperature power performance, etc.

[0191] The methods for preparing battery cells are well known. In some embodiments, a positive electrode, a separator, a porous negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, a positive electrode, a separator, and a porous negative electrode can be assembled to obtain an electrode assembly. The electrode assembly is placed in an outer packaging, dried, and then injected with the electrolyte. After encapsulation, settling, and other processes, a battery cell is obtained.

[0192] Example

[0193] The following embodiments describe the contents of this disclosure 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 this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, 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.

[0194] Comparative Example 1

[0195] Preparation of porous negative electrode sheet

[0196] Commercially available nonwoven polyimide fiber membranes were cut into 10cm × 10cm sheets, baked in an 80℃ vacuum drying oven for 10 minutes, and then a conductive Ni layer was formed on the filaments of the nonwoven polyimide fiber membrane using magnetron sputtering. The areal density of the conductive Ni layer was 50 g / m². 2 It is used as a porous negative electrode sheet for backup.

[0197] The porous negative electrode sheet has a thickness of 75μm, a porosity of 91%, a pore size distribution range of 5μm-10μm, and a rib diameter distribution range of 0.5μm-1μm.

[0198] Preparation of positive electrode sheet

[0199] LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1O2, conductive carbon black (positive electrode conductive agent), and polyvinylidene fluoride (PVDF) (positive electrode binder) are mixed in a mass ratio of 98:1:1 and then N-methylpyrrolidone (N-methylpyrrolidone) is added to form a slurry. The slurry is coated onto aluminum foil (positive electrode current collector), dried, cold-pressed, and cut to obtain the positive electrode sheet for later use.

[0200] Preparation of the separating membrane

[0201] A 12μm thick porous polyethylene membrane was used as the separator.

[0202] Preparation of electrolyte

[0203] Lithium bis(fluorosulfonyl)imide (LiFSI) was dissolved in dimethyl ethylene glycol (DME) to prepare an electrolyte. The concentration of LiFSI was 1 mol / L.

[0204] Preparation of battery cells

[0205] In the glove box, the cells are assembled in the following order: negative electrode shell - spring piece - gasket - porous negative electrode plate - electrolyte - separator membrane - electrolyte - positive electrode plate - gasket - positive electrode shell, and then sealed to obtain a button cell.

[0206] Comparative Example 2

[0207] Except for the different preparation of the porous negative electrode sheet, the preparation of the battery cell is the same as that of Comparative Example 1.

[0208] Preparation of porous negative electrode sheet

[0209] Commercially available nonwoven polyimide fiber membranes were cut into 10cm × 10cm sheets, baked in an 80℃ vacuum drying oven for 10 minutes, and then removed. A conductive Ni layer was formed on the filaments of the nonwoven polyimide fiber membrane using magnetron sputtering. A lithium-philic Bi layer was then formed on the conductive Ni layer using magnetron sputtering. The areal density of the conductive Ni layer was 50 g / m³. 2 The areal density of the metallic Bi layer is 3 g / m³. 2 It is used as a porous negative electrode sheet for backup.

[0210] The porous negative electrode sheet has a thickness of 75μm, a porosity of 91%, a pore size distribution range of 5μm-10μm, and a rib diameter distribution range of 0.5μm-1μm.

[0211] Example 1

[0212] Except for the different preparation of the porous negative electrode sheet, the preparation of the battery cell is the same as that of Comparative Example 1.

[0213] Preparation of porous negative electrode sheet

[0214] Commercially available nonwoven polyimide fiber membranes were cut into 10cm × 10cm sheets, baked in an 80℃ vacuum drying oven for 10 minutes, and then fixed onto a deposition tray. The deposition tray was fixed above the evaporation source, and lithium sheets or ingots were placed in the crucible as the evaporation source. The chamber door was closed, and a vacuum of 5 × 10⁻⁶ was initiated. -4 Pa. Set the coating parameters, select Li as the coating material, and choose 1 μm as the final coating thickness. Start the coating process. Close the substrate baffle, turn on the electron gun, and slowly increase the gun filament current until the film thickness gauge rate increases from 0 to 5 Å / s. Stop increasing the gun filament current and repeatedly adjust the current until the coating rate stabilizes. Open the substrate baffle, zero the film thickness gauge, and recalculate the thickness. The coating process begins. When the coating thickness accumulates to 1 μm, close the substrate baffle, turn off the electron gun, turn off the vacuum system, and fill the vacuum chamber with a 50:50 mixture of oxygen and nitrogen for passivation treatment until the internal pressure of the vacuum chamber is the same as the external pressure. Open the chamber door, take a sample, and obtain a modified nonwoven polyimide fiber membrane, which will be used as a porous negative electrode for later use. The porous negative electrode includes a lithium metal layer located on the ribs of the nonwoven polyimide fiber membrane along its thickness direction and on the ribs of the pores inside the nonwoven polyimide fiber membrane. The microstructure of the lithium metal layer is nodular. A passivation layer, including Li2O, is also formed on the surface of the lithium metal layer.

[0215] The porous negative electrode sheet has a thickness of 75μm, a porosity of 91%, a pore size distribution range of 5μm-10μm, and a rib diameter distribution range of 1μm-1.5μm.

[0216] Example 2

[0217] Except for the different preparation of the porous negative electrode sheet, the preparation of the battery cell is the same as that of Comparative Example 1.

[0218] Preparation of porous negative electrode sheet

[0219] Commercially available nonwoven polyimide fiber membranes were cut into 10cm × 10cm sheets, baked in an 80℃ vacuum drying oven for 10 minutes, and then a conductive Ni layer was formed on the filaments of the nonwoven polyimide fiber membrane using magnetron sputtering. The areal density of the conductive Ni layer was 50 g / m². 2 Next, a nonwoven polyimide fiber membrane coated with a conductive Ni metal layer is fixed onto the deposition chassis. The deposition chassis is then fixed above the evaporation source, and lithium sheets or ingots are placed in the crucible as the evaporation source. The chamber door is closed, and a vacuum of 5 × 10⁻⁶ is initiated. -4Pa. Set the coating parameters, select Li as the coating material, and choose a final coating thickness of 0.5 μm. Start the coating process. Close the substrate baffle, turn on the electron gun, and slowly increase the gun filament current until the film thickness gauge rate increases from 0 to 5 Å / s. Stop increasing the gun filament current and repeatedly adjust the current until the coating rate stabilizes. Open the substrate baffle, zero the film thickness gauge, and recalculate the thickness. The coating process begins. When the coating thickness accumulates to 0.5 μm, close the substrate baffle, turn off the electron gun, turn off the vacuum system, and fill the vacuum chamber with a 50:50 mixture of oxygen and nitrogen for passivation treatment until the internal pressure of the vacuum chamber is the same as the external pressure. Open the chamber door, take a sample, and obtain a modified nonwoven polyimide fiber membrane, which will be used as a porous negative electrode for later use. The porous negative electrode includes a conductive metal Ni layer and a lithium metal layer. The conductive metal Ni layer is located on the ribs of the surface of the nonwoven polyimide fiber membrane along its own thickness direction and on the ribs of the pores inside the nonwoven polyimide fiber membrane. The lithium metal layer is located on the conductive metal Ni layer. The microstructure of the lithium metal layer is granular. A passivation layer is also formed on the surface of the lithium metal layer, which includes Li2O.

[0220] The porous negative electrode sheet has a thickness of 75μm, a porosity of 91%, a pore size distribution range of 5μm-10μm, and a rib diameter distribution range of 0.75μm-1.25μm.

[0221] Example 3

[0222] Except for the different preparation of the porous negative electrode sheet, the preparation of the battery cell is the same as that of Comparative Example 1.

[0223] Preparation of porous negative electrode sheet

[0224] Commercially available nonwoven polyimide fiber membranes were cut into 10cm × 10cm sheets, baked in an 80℃ vacuum drying oven for 10 minutes, and then removed. A conductive Ni layer was formed on the filaments of the nonwoven polyimide fiber membrane using magnetron sputtering. A lithium-philic Bi layer was then formed on the conductive Ni layer using magnetron sputtering. The areal density of the conductive Ni layer was 50 g / m². 2 The areal density of the metallic Bi layer is 3 g / m³. 2 Next, a nonwoven polyimide fiber membrane coated with a conductive Ni layer and a lithium-philic Bi layer is fixed onto the deposition chassis. The deposition chassis is then fixed above the evaporation source, and lithium sheets or ingots are placed in the crucible as the evaporation source. The chamber door is closed, and a vacuum of 5 × 10⁻⁶ is initiated. -4Pa. Set the coating parameters, select Li as the coating material, and choose 1 μm as the final coating thickness. Start the coating process. Close the substrate baffle, turn on the electron gun, and slowly increase the gun filament current until the film thickness gauge rate increases from 0 to 5 Å / s. Stop increasing the gun filament current and repeatedly adjust the current until the coating rate stabilizes. Open the substrate baffle, zero the film thickness gauge, and recalculate the thickness. The coating process begins. When the coating thickness accumulates to 1 μm, close the substrate baffle, turn off the electron gun, turn off the vacuum system, and fill the vacuum chamber with a 50:50 mixture of oxygen and nitrogen for passivation treatment until the internal pressure of the vacuum chamber is the same as the external pressure. Open the chamber door, take a sample, and obtain a modified nonwoven polyimide fiber membrane, which will be used as a porous negative electrode for later use. The porous negative electrode sheet includes a conductive metal Ni layer and a Li-Bi alloy layer. The conductive metal Ni layer is located on the ribs of the surface of the nonwoven polyimide fiber membrane along its own thickness direction and on the ribs of the pores inside the nonwoven polyimide fiber membrane. The Li-Bi alloy layer is located on the conductive metal Ni layer. The microstructure of the Li-Bi alloy layer is granular. A passivation layer is also formed on the surface of the Li-Bi alloy layer, which includes Li2O.

[0225] The porous negative electrode sheet has a thickness of 75μm, a porosity of 91%, a pore size distribution range of 5μm-10μm, and a rib diameter distribution range of 1μm-1.5μm.

[0226] Performance testing

[0227] (1) First Coulomb efficiency test

[0228] The ambient temperature was set to 25℃. The coin cell battery was charged using constant current-constant voltage (CC-CV) mode, and discharged using constant current mode. First, in constant current mode, the coin cell battery was charged at a fixed rate of 0.2C until the voltage reached 4.3V, obtaining the first charge capacity. Then, the system switched to constant voltage mode and charged until the cutoff current reached 0.05C. Finally, it was discharged at a constant current rate of 0.5C to 2.8V, obtaining the first discharge capacity. The initial coulombic efficiency = (first discharge capacity / first charge capacity) × 100%.

[0229] (2) Cyclic performance test

[0230] The ambient temperature was set to 25℃. The coin cells were charged using constant current-constant voltage (CC-CV) mode, and discharged using constant current mode. First, in constant current mode, the coin cells were charged at a fixed rate of 0.2C until the voltage reached 4.3V. Then, the system switched to constant voltage mode and charged until the cutoff current reached 0.05C. Next, the cells were discharged at a constant current rate of 0.5C until the voltage reached 2.8V. This charging and discharging cycle was repeated, and the number of cycles completed when the discharge capacity decreased to 80% of the initial discharge capacity was recorded. This number characterizes the cycle performance of the individual cells. A higher value indicates better cycle performance.

[0231] Table 1

[0232] Serial Number First Coulomb Efficiency / % Number of loops / revolutions Comparative Example 1 71.2 33 Comparative Example 2 66.3 38 Example 1 79.2 45 Example 2 76.7 58 Example 3 77.0 51

[0233] Figure 3 This image shows a scanning electron microscope (SEM) image of a commercially available nonwoven polyimide fiber membrane. Figure 4 and Figure 5 The image shows a scanning electron microscope (SEM) image of the porous negative electrode sheet prepared in Example 1. Figure 6 The image shows a scanning electron microscope (SEM) image of the porous negative electrode sheet prepared in Example 2. Figure 7 The image shows a scanning electron microscope (SEM) image of the porous negative electrode sheet prepared in Example 3.

[0234] like Figure 3 As shown, commercially available nonwoven polyimide fiber membranes exhibit an interlaced distribution of ribbed filaments with smooth surfaces.

[0235] like Figure 4 and Figure 5 As shown, the surface of the porous negative electrode sheet prepared in this disclosure exhibits a nodular shape.

[0236] like Figure 6 As shown, the porous negative electrode sheet prepared in this disclosure has a granular surface on its ribbed surface.

[0237] like Figure 7 As shown, the porous negative electrode sheet prepared in this disclosure has a granular surface on its ribbed surface.

[0238] The test results above show that the porous negative electrode sheet prepared in this disclosure can enable the battery cell to have high initial coulombic efficiency and long cycle life.

[0239] It should be noted that this disclosure 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 disclosure are included within the technical scope of this disclosure. 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, are also included within the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. A porous negative electrode sheet, characterized in that, the porous negative electrode sheet comprises a porous polymer substrate, the porous polymer substrate comprises a plurality of pores; the porous negative electrode sheet comprises a lithium metal layer, the lithium metal layer is located on the filaments on the surface of the porous polymer substrate along the thickness direction of the porous polymer substrate and the filaments of the internal pores of the porous polymer substrate; or, the porous negative electrode sheet comprises a lithium alloy layer, the lithium alloy layer is located on the filaments on the surface of the porous polymer substrate along the thickness direction of the porous polymer substrate and the filaments of the internal pores of the porous polymer substrate.

2. The porous negative electrode sheet according to claim 1, characterized by The porous polymer substrate is a non-woven polymer fiber structure substrate or a porous foam polymer substrate. 3.The porous negative electrode sheet according to claim 2, characterized in that, the material of the non-woven polymer fiber structure substrate comprises one or more of polyimide, polyvinylidene fluoride, polyacrylonitrile, polyethylene terephthalate, polyphenylene terephthalamide, polymethyl methacrylate, polyurethane, polystyrene, polyhexamethylene adipate, polycaprolactam, polyetherimide and their respective derivatives; and / or, the porous foam polymer substrate comprises one or more of polyimide foam, polyethylene foam, polypropylene foam, polyurethane foam, polystyrene foam, melamine formaldehyde foam, polyvinyl alcohol foam.

4. The porous negative electrode sheet according to any one of claims 1 to 3, characterized by, The porous negative electrode sheet comprises a lithium metal layer, the lithium metal layer is located on the filaments on the surface of the porous polymer substrate along the thickness direction of the porous polymer substrate and the filaments of the internal pores of the porous polymer substrate, and the micro-morphology of the lithium metal layer is nodular.

5. The porous negative electrode sheet according to any one of claims 1 to 4, characterized by, The porous negative electrode sheet comprises a lithium metal layer, the lithium metal layer is located on the filaments on the surface of the porous polymer substrate along the thickness direction of the porous polymer substrate and the filaments of the internal pores of the porous polymer substrate, and the thickness of the lithium metal layer is 0.1 μm-1 μm.

6. The porous negative electrode sheet according to any one of claims 1 to 5, characterized by, The porous negative electrode sheet comprises a lithium metal layer, the lithium metal layer is located on the filaments on the surface of the porous polymer substrate along the thickness direction of the porous polymer substrate and the filaments of the internal pores of the porous polymer substrate, and the lithium metal layer further has a passivation layer, and the passivation layer comprises Li 2 O.

7. The porous negative electrode sheet according to any one of claims 1 to 3, characterized by, The porous negative electrode sheet comprises a conductive metal layer and a lithium metal layer, the conductive metal layer is located on the filaments on the surface of the porous polymer substrate along the thickness direction of the porous polymer substrate and the filaments of the internal pores of the porous polymer substrate, the lithium metal layer is located on the conductive metal layer, the conductive metal layer is close to the porous polymer substrate, and the lithium metal layer is away from the porous polymer substrate. 8.The porous negative electrode sheet according to claim 7, characterized in that, the conductive metal layer comprises one or more of the elements Cu, Fe, Ni, Ti and their alloys; and / or, The areal density of the electrically conductive metal layer is 40 g / m 2 - 60 g / m 2 .

9. The porous negative electrode sheet according to any one of claims 7-8, wherein, the lithium metal layer comprises a plurality of lithium metal particles.

10. The porous negative electrode sheet according to any one of claims 7 to 9, characterized by, The thickness of the lithium metal layer is 0.1 μm-1 μm.

11. The porous negative electrode sheet according to any one of claims 7 to 10, characterized by The lithium metal layer further has a passivation layer, and the passivation layer comprises Li 2 O.

12. The porous negative electrode sheet according to any one of claims 1 to 3, characterized by, The porous negative electrode sheet includes a conductive metal layer and a lithium alloy layer, the conductive metal layer is located on the rib of the surface of the porous polymer substrate along the thickness direction of itself and the rib of the internal pore of the porous polymer substrate, the lithium alloy layer is located on the conductive metal layer, the conductive metal layer is close to the porous polymer substrate, and the lithium alloy layer is away from the porous polymer substrate.

13. The porous negative electrode sheet according to claim 12, wherein the conductive metal layer comprises one or more of Cu, Fe, Ni, Ti, and alloys thereof; and / or the lithium alloy layer comprises a plurality of lithium alloy particles. The lithium alloy layer comprises elements Li and at least one of Sn, Zn, Bi, Au, Ag, Al, Si, Mg, Pt, Pb, Be, Ga, In, Ge, Sb, and Te. The areal density of the electrically conductive metal layer is 40 g / m 2 - 60 g / m 2 .

14. The porous negative electrode sheet according to any one of claims 12-13, wherein, The thickness of the lithium alloy layer is 0.1 μm-2 μm.

15. The porous negative electrode sheet according to any one of claims 12 to 14, characterized by, The lithium alloy layer further has a passivation layer, and the passivation layer comprises Li2O.

16. The porous negative electrode sheet according to any one of claims 12 to 15, characterized by, The porous negative electrode sheet satisfies one or more of the following conditions (1) to (5):

17. The porous negative electrode sheet according to any one of claims 12 to 16, characterized by, (1) The thickness of the porous negative electrode sheet is 50 μm-100 μm; 18. The porous negative electrode sheet according to any one of claims 1 to 17, wherein (2) The porosity of the porous negative electrode sheet is 85%-95%; (3) The pore size distribution range of the porous negative electrode sheet is 4 μm-12 μm; (4) The through-hole rate of the porous negative electrode sheet is greater than or equal to 99%; (5) The rib diameter distribution range of the porous negative electrode sheet is 0.5 μm-2.5 μm.

19. A method for preparing a porous negative electrode sheet, comprising the following steps: providing a porous polymer substrate, the porous polymer substrate comprising a plurality of pores; and forming a lithium metal layer on the rib of the surface of the porous polymer substrate along the thickness direction of itself and the rib of the internal pore of the porous polymer substrate by an evaporation plating lithium process. The method for preparing the porous negative electrode sheet comprises the following steps: providing a porous polymer substrate, the porous polymer substrate comprising a plurality of pores, and the porous polymer substrate having a conductive metal layer on the rib of the surface of the porous polymer substrate along the thickness direction of itself and the rib of the internal pore of the porous polymer substrate; and forming a lithium metal layer on the conductive metal layer on the rib of the surface of the porous polymer substrate along the thickness direction of itself and the conductive metal layer on the rib of the internal pore of the porous polymer substrate by an evaporation plating lithium process. The method for preparing the porous negative electrode sheet comprises the following steps: providing a porous polymer substrate, the porous polymer substrate comprising a plurality of pores, and the porous polymer substrate having a conductive metal layer and a lithium-philic layer on the rib of the surface of the porous polymer substrate along the thickness direction of itself and the rib of the internal pore of the porous polymer substrate, the conductive metal layer being located between the lithium-philic layer and the porous polymer substrate; and reacting lithium metal with the lithium-philic layer on the rib of the surface of the porous polymer substrate along the thickness direction of itself and the lithium-philic layer on the rib of the internal pore of the porous polymer substrate by an evaporation plating lithium process to form a lithium alloy layer.

20. The method of claim 19, wherein, 22. The method according to claim 21, wherein the lithium alloy layer comprises elements Li and at least one of Sn, Zn, Bi, Au, Ag, Al, Si, Mg, Pt, Pb, Be, Ga, In, Ge, Sb, and Te.

21. The method of claim 19, wherein, ​ ​ The lithium-philic layer comprises one or more of Sn, Zn, Bi, Au, Ag, Al, Si, Mg, Pt, Pb, Be, Ga, In, Ge, Sb, Te, and alloys thereof; and / or, The areal density of the lithiumophilic layer is 2 g / m 2 - 3 g / m 2 .

23. The preparation method of any one of claims 20-22, wherein, The conductive metal layer comprises one or more of Cu, Fe, Ni, Ti, and alloys thereof; and / or, The areal density of the electrically conductive metal layer is 40 g / m 2 - 60 g / m 2 .

24. The method of any one of claims 19-23, wherein, The evaporation lithium plating process has a plating rate of less than or equal to 5 angstroms per second.

25. The method of any one of claims 19-24, wherein, The preparation method further comprises a passivation treatment step after the evaporation lithium plating step.

26. The method of claim 25, wherein, The passivation treatment is performed in an oxygen-containing atmosphere, an inert gas atmosphere, or a carbon dioxide atmosphere.

27. A battery cell, characterized by The battery device comprises the porous negative electrode sheet of any one of claims 1-18 or prepared by the preparation method of any one of claims 19-26.

28. A battery device, characterized by The battery device comprises the battery cell of claim 27 or the battery device of claim 28.

29. An electrical device, comprising: ​

Images