Negative electrode sheet and preparation method therefor, bipolar electrode sheet and preparation method therefor, and battery and electric apparatus

Abstract

Disclosed in the present invention are a negative electrode sheet and a preparation method therefor, a bipolar electrode sheet and a preparation method therefor, and a battery and an electric apparatus. The negative electrode sheet comprises: a first current collector, wherein the first current collector comprises a first side and a second side opposite each other; and a first active material layer and a second active material layer, which are sequentially arranged on the first side in the direction away from the first current collector, wherein the first active material layer comprises metallic lithium, and the second active material layer comprises a metallic lithium alloy. By using the negative electrode sheet or the bipolar electrode sheet, the problems of continuous thickening of an SEI film, persistent growth of lithium dendrites, dead lithium, lithium dendrites penetrating a separator, etc., can be avoided, thereby facilitating an improvement in the cyclic stability of a battery to which the negative electrode sheet or the bipolar electrode sheet is applied.

Description

Negative electrode sheet and preparation method thereof, bipolar electrode sheet and preparation method thereof, battery and electrical device

[0001] This application claims priority and benefits of patent application No. 202311525462.0 filed with the State Intellectual Property Office of China on November 15, 2023, and the entire text of which is incorporated herein by reference. Technical Field

[0002] The present invention belongs to the technical field of batteries, and in particular relates to a negative electrode plate and a preparation method thereof, a bipolar electrode plate and a preparation method thereof, a battery and an electrical device. Background Art

[0003] Compared to the theoretical specific capacity of 372 mAh / g for graphite anodes, metallic lithium has an ultra-high theoretical specific capacity of 3860 mAh / g and the most negative standard reduction potential (-3.04 V). Furthermore, it has low density and a small ionic radius. Using metallic lithium as the active material for the negative electrode of a battery can further increase the energy density of the battery. However, direct contact between metallic lithium and the electrolyte or electrolyte leads to problems such as lithium dendrite growth and puncture of the separator, hindering the large-scale application of lithium metal batteries.

[0004] Summary of the Invention

[0005] The present invention aims to solve, at least to a certain extent, one of the technical problems in the related art. To this end, one object of the present invention is to provide a negative electrode plate and a method for preparing the same, a bipolar electrode plate and a method for preparing the same, a battery, and an electrical device. The use of such a negative electrode plate or bipolar electrode plate can avoid problems such as continuous thickening of the SEI film, continuous growth of lithium dendrites, dead lithium, and lithium dendrites piercing the diaphragm, thereby improving the cycling stability of batteries using such a negative electrode plate or bipolar electrode plate.

[0006] In a first aspect of the present invention, the present invention provides a negative electrode plate. According to an embodiment of the present invention, the negative electrode plate includes:

[0007] a first current collector comprising opposing first and second sides;

[0008] A first active material layer and a second active material layer, wherein the first active material layer and the second active material layer are sequentially arranged on the first side in a direction away from the first current collector, the first active material layer includes metallic lithium, and the second active material layer includes a metallic lithium alloy.

[0009] According to the negative electrode sheet of the above embodiment of the present invention, a first active material layer and a second active material layer are sequentially arranged on the first side of the first current collector in a direction away from the first current collector, the first active material layer includes metallic lithium, which can serve as a supplementary lithium source to improve the cycle life of the battery, and the second active material layer includes a metallic lithium alloy. On the one hand, it can prevent the metallic lithium with high reactivity in the first active material layer from directly contacting the electrolyte or electrolyte, and on the other hand, it can enable the metallic lithium and the metallic lithium alloy in the second active material layer to undergo alloying reaction during the battery charge and discharge process, effectively avoiding the growth of lithium dendrites caused by uneven deposition of metallic lithium, as well as the problems of continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate, thereby improving the cycle stability of the lithium metal battery using the negative electrode sheet. Therefore, the negative electrode sheet of the present invention can avoid the growth of lithium dendrites caused by uneven deposition of metallic lithium on the negative electrode surface, solve the problems of continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate of metallic lithium, thereby improving the cycle stability of the lithium metal battery.

[0010] In addition, the negative electrode sheet according to the above embodiment of the present invention may also have the following additional technical features:

[0011] In some embodiments of the present invention, the first current collector is a composite current collector.

[0012] In some embodiments of the present invention, the first current collector is a metal foil current collector, and the metal foil current collector includes at least one of copper, aluminum, nickel, and chromium.

[0013] In some embodiments of the present invention, the first current collector includes a first base film, a first conductive layer disposed on one side of the first base film, and a second conductive layer disposed on the other side opposite to the first base film.

[0014] In some embodiments of the present invention, the first conductive layer and the second conductive layer each independently include at least one of copper, aluminum, nickel, and chromium, thereby improving the conductivity of the first current collector.

[0015] In some embodiments of the present invention, the thickness of the first conductive layer and the second conductive layer are independently 0.2 μm-100 μm.

[0016] In some embodiments of the present invention, the first base film includes at least one of polyethylene, polyethylene terephthalate, polyimide, polypropylene, polyamide, polyphenylene sulfide, and polyethylene naphthalate.

[0017] In some embodiments of the present invention, the thickness of the first base film is 1 μm-300 μm.

[0018] In some embodiments of the present invention, a third active material layer is disposed on the second side of the first current collector, and the third active material layer includes metallic lithium or a metallic lithium alloy.

[0019] In some embodiments of the present invention, the first active material layer is disposed on the first conductive layer, and the third active material layer is disposed on the second conductive layer.

[0020] In some embodiments of the present invention, the third active material layer includes metallic lithium, a fourth active material layer is provided on a side of the third active material layer away from the first current collector, and the fourth active material layer includes a metallic lithium alloy.

[0021] In some embodiments of the present invention, the metal lithium alloy comprises an alloy formed by metal lithium and at least one of gold, silver, indium, magnesium, zinc, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, manganese, aluminum, copper, tin, sodium, calcium, gallium, boron, silicon, carbon, and phosphorus. This can solve problems such as lithium dendrite growth caused by uneven deposition of metal lithium on the negative electrode surface, continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm during the cycling of lithium metal batteries.

[0022] In some embodiments of the present invention, the lithium content of the metallic lithium alloy is 2 atm% to 98 atm%. This can solve the problems of lithium dendrite growth, continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator caused by uneven deposition of metallic lithium on the negative electrode surface during the cycle of lithium metal batteries.

[0023] In some embodiments of the present invention, the thicknesses of the first active material layer, the second active material layer, the third active material layer, and the fourth active material layer are independently 0.1 μm-100 μm.

[0024] In a second aspect of the present invention, a method for preparing a negative electrode sheet is provided. According to an embodiment of the present invention, the method comprises:

[0025] providing a first current collector comprising opposing first and second sides;

[0026] forming a first active material layer on a first side of the first current collector, wherein the first active material layer includes metallic lithium;

[0027] A second active material layer is formed on the first active material layer at a side away from the first current collector, wherein the second active material layer includes a metal lithium alloy.

[0028] According to the method for preparing a negative electrode plate in the above embodiment of the present invention, a first current collector including a first side and a second side relative to each other is provided, and a first active material layer is formed on the first side of the first current collector, and a second active material layer is formed on the side of the first active material layer away from the first current collector. The first active material layer includes metallic lithium, which can be used as a supplementary lithium source to improve the cycle life of the battery. The second active material layer includes a metallic lithium alloy. On the one hand, it can avoid direct contact between the metallic lithium with high reactivity in the first active material layer and the electrolyte or electrolyte. On the other hand, it can enable the metallic lithium and the metallic lithium alloy in the second active material layer to undergo alloying reaction during the charge and discharge process of the battery, effectively avoiding the uneven deposition of metallic lithium causing the growth of lithium dendrites, as well as the problems such as continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate, thereby helping to improve the cycle stability of the lithium metal battery using the negative electrode plate. Therefore, the negative electrode plate obtained by the method for preparing the negative electrode plate of the present invention can avoid the growth of lithium dendrites caused by the uneven deposition of metallic lithium on the negative electrode surface, and solve the problems of continuous thickening of SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate of metallic lithium, thereby helping to improve the cycle stability of lithium metal batteries.

[0029] In addition, the method for preparing a negative electrode sheet according to the above embodiment of the present invention may also have the following additional technical features:

[0030] In some embodiments of the present invention, the method for preparing a negative electrode sheet further includes: forming a third active material layer on the second side of the first current collector, wherein the third active material layer includes metallic lithium or a metallic lithium alloy.

[0031] In some embodiments of the present invention, the third active material layer comprises metallic lithium, and the method for preparing a negative electrode sheet further comprises forming a fourth active material layer on a side of the third active material layer away from the first current collector, wherein the fourth active material layer comprises a metallic lithium alloy. This can improve the cycling stability of the lithium metal battery.

[0032] In a third aspect of the present invention, a bipolar pole piece is provided. According to an embodiment of the present invention, the bipolar pole piece includes:

[0033] a second current collector comprising opposing first and second sides;

[0034] A fifth active material layer and a sixth active material layer, the second current collector includes a first side and a second side relative to each other, the fifth active material layer is arranged on the first side of the second current collector, the sixth active material layer is arranged on the second side of the second current collector, the fifth active material layer includes a metallic lithium alloy, and the sixth active material layer includes a positive electrode active material.

[0035] According to the bipolar pole piece of the above embodiment of the present invention, by providing a second current collector including a first side and a second side relative to each other, and forming a fifth active material layer on the first side of the second current collector, and forming a sixth active material layer on the second side of the second current collector, the fifth active material layer includes a metal lithium alloy, so that the metal lithium and the metal lithium alloy in the fifth active material layer can undergo an alloying reaction during the charge and discharge process of the battery, effectively avoiding the growth of lithium dendrites caused by uneven deposition of metal lithium, as well as the problems of continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate, thereby facilitating the improvement of the cycle stability of the battery using the bipolar pole piece. The sixth active material layer includes a positive electrode active material, and a bipolar pole piece can be obtained. As a result, the bipolar pole piece of the present invention can avoid the growth of lithium dendrites caused by uneven deposition of metal lithium on the negative electrode surface, solve the problems of continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate of metal lithium, thereby facilitating the improvement of the cycle stability of the battery.

[0036] In addition, the bipolar pole piece according to the above embodiment of the present invention may also have the following additional technical features:

[0037] In some embodiments of the present invention, a seventh active material layer is disposed on the first side of the second current collector, the seventh active material layer includes metallic lithium, and the fifth active material layer is disposed on a side of the seventh active material layer away from the second current collector.

[0038] In some embodiments of the present invention, the second current collector is a composite current collector.

[0039] In some embodiments of the present invention, the second current collector is a metal foil current collector, and the metal foil current collector includes a stainless steel alloy foil, and the stainless steel alloy foil includes at least one of nickel, chromium, and copper.

[0040] In some embodiments of the present invention, the second current collector includes a second base film, a third conductive layer arranged on one side of the second base film, and a fourth conductive layer arranged on the other side opposite to the second base film, the fifth active material layer is arranged on the third conductive layer, and the sixth active material layer is arranged on the fourth conductive layer.

[0041] In some embodiments of the present invention, the second current collector includes a second base film, a third conductive layer arranged on one side of the second base film, and a fourth conductive layer arranged on the other side opposite to the second base film, the seventh active material layer is arranged on the third conductive layer, and the sixth active material layer is arranged on the fourth conductive layer.

[0042] In some embodiments of the present invention, the third conductive layer includes at least one of copper, aluminum, nickel, and chromium, preferably copper, thereby improving the conductivity of the second current collector.

[0043] In some embodiments of the present invention, the fourth conductive layer includes at least one of copper, aluminum, nickel, and chromium, preferably aluminum, thereby improving the conductivity of the second current collector.

[0044] In some embodiments of the present invention, the positive electrode active material includes at least one of lithium nickel cobalt manganese oxide, lithium iron manganese phosphate, lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium-rich manganese-based positive electrode material, lithium nickel manganese oxide and lithium vanadium oxyphosphate.

[0045] In a fourth aspect of the present invention, a method for preparing a bipolar pole piece is provided. According to an embodiment of the present invention, the method comprises:

[0046] providing a second current collector comprising opposing first and second sides;

[0047] forming a fifth active material layer on the first side of the second current collector, wherein the fifth active material layer includes a metallic lithium alloy;

[0048] A sixth active material layer is formed on the second side of the second current collector, the sixth active material layer including a positive electrode active material.

[0049] According to the method for preparing a bipolar pole piece according to the above embodiment of the present invention, a second current collector including a first side and a second side is provided, and a fifth active material layer is formed on the first side of the second current collector, and a sixth active material layer is formed on the second side of the second composite current collector. The fifth active material layer comprises a metallic lithium alloy. This allows the metallic lithium to undergo an alloying reaction with the metallic lithium alloy in the fifth active material layer during the charge and discharge process of the battery, effectively avoiding the problems of lithium dendrite growth caused by uneven deposition of metallic lithium, as well as the continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator caused by the infinite volume change rate, thereby improving the cycle stability of the battery using the bipolar pole piece. The sixth active material layer comprises a positive electrode active material, and a bipolar pole piece can be obtained. Thus, the bipolar pole piece obtained by the method for preparing a bipolar pole piece according to the present invention can avoid the lithium dendrite growth caused by uneven deposition of metallic lithium on the negative electrode surface, solve the problems of continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator caused by the infinite volume change rate of metallic lithium, thereby improving the cycle stability of the battery.

[0050] In addition, the method for preparing a bipolar pole piece according to the above embodiment of the present invention may also have the following additional technical features:

[0051] In some embodiments of the present invention, the method for preparing a bipolar pole piece further includes forming a seventh active material layer on the second side of the second current collector before forming the fifth active material layer on the first side of the second current collector, wherein the seventh active material layer includes metallic lithium. Thus, the seventh active material layer can serve as a supplemental lithium source to improve the cycle life of the battery.

[0052] In its fifth aspect, the present invention provides a battery. According to an embodiment of the present invention, the battery comprises the aforementioned negative electrode sheet, or a negative electrode sheet obtained using the aforementioned method for preparing a negative electrode sheet, or the aforementioned bipolar electrode sheet, or a bipolar electrode sheet obtained using the aforementioned method for preparing a bipolar electrode sheet. As a result, the battery exhibits high cycling stability.

[0053] In addition, the battery according to the above embodiment of the present invention may also have the following additional technical features:

[0054] In some embodiments of the present invention, the battery includes a liquid battery, a semi-solid battery and an all-solid battery.

[0055] In some embodiments of the present invention, the battery includes a liquid battery and a semi-solid battery, and the battery includes an electrolyte, and the electrolyte includes a lithium salt and a solvent.

[0056] In some embodiments of the present invention, the electrolyte further includes an additive.

[0057] In some embodiments of the present invention, the lithium salt includes at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonyl-perfluorobutylsulfonylimide, lithium fluorosulfonyl-perfluorobutylsulfonylimide, lithium bis(oxalatoborate) and tris(trifluoromethylsulfonyl)methyllithium.

[0058] In some embodiments of the present invention, the solvent includes at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, tetrahydrofuran, 2-methyl-tetrahydrofuran, dimethoxydimethyl ether, 1,2-dimethoxyethane and acetonitrile.

[0059] In some embodiments of the present invention, the additive includes at least one of a film-forming additive, a conductive additive, a flame retardant additive, an overcharge protection additive, an additive for controlling water and HF content, a low-temperature additive, and a negative electrode stabilizer.

[0060] In some embodiments of the present invention, the battery includes a semi-solid-state battery and an all-solid-state battery, and the battery includes an electrolyte, and the electrolyte includes at least one of an inorganic solid electrolyte, a polymer solid electrolyte, and a composite solid electrolyte.

[0061] In some embodiments of the present invention, the inorganic solid electrolyte includes at least one of an oxide solid electrolyte, a sulfide solid electrolyte and a halide solid electrolyte; the oxide solid electrolyte includes at least one of a NASICON-type solid electrolyte, a perovskite-type solid electrolyte and a garnet-type solid electrolyte; the sulfide solid electrolyte includes at least one of Li6PS5F, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li2S-SiS2, Li2S-P2S5, Li2S-GeS2, Li2S-SiS2-P2S5, Li2S-GeS2-P2S5, Li2S-SnS2-P2S5 and Li2S-AlS2-P2S5; the halide solid electrolyte includes at least one of Li2MnCl4, Li2ZnCl4, LiYbF4, LiAlF4, Li3YCl6, Li3BrCl6 and Li6CoCl8.

[0062] In some embodiments of the present invention, the polymer solid electrolyte includes a polymer matrix, an inorganic filler and a lithium salt, wherein the polymer matrix includes at least one of polyethylene oxide, polycarbonate, polytrimethylene carbonate, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoroethylene copolymer and lithium polyacrylate, and the inorganic filler includes Li 1.3 Al 0.3 Ti 1.7 (PO4)3, lithium lanthanum zirconium oxide, aluminum oxide and metal organic framework, and the lithium salt includes at least one of LiAsF6, LiPF6, LiClO4, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium tetrafluoroborate.

[0063] In a sixth aspect, the present invention provides an electrical device. According to an embodiment of the present invention, the electrical device includes the aforementioned battery. The electrical device and the aforementioned battery have the same advantages over the prior art, which will not be further elaborated here.

[0064] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0066] FIG1 is a schematic structural diagram of a negative electrode sheet according to an embodiment of the present invention;

[0067] FIG2 is a schematic structural diagram of a first current collector according to an embodiment of the present invention;

[0068] FIG3 is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present invention;

[0069] FIG4 is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present invention;

[0070] FIG5 is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present invention;

[0071] FIG6 is a schematic flow chart of a method for preparing a negative electrode sheet according to one embodiment of the present invention;

[0072] FIG7 is a schematic structural diagram of a bipolar pole piece according to an embodiment of the present invention;

[0073] FIG8 is a schematic structural diagram of a second current collector according to one embodiment of the present invention;

[0074] FIG9 is a schematic structural diagram of a bipolar pole piece according to yet another embodiment of the present invention;

[0075] FIG10 is a schematic structural diagram of a bipolar pole piece according to yet another embodiment of the present invention;

[0076] FIG11 is a schematic flow chart of a method for preparing a bipolar pole piece according to an embodiment of the present invention.

[0077] Figure numerals: 100 - negative electrode plate; 10 - first current collector; 11 - first base film; 12 - first conductive layer; 13 - second conductive layer; 20 - first active material layer; 30 - second active material layer; 40 - third active material layer; 50 - fourth active material layer; 200 - bipolar plate; 210 - second current collector; 211 - second base film; 212 - third conductive layer; 213 - fourth conductive layer; 220 - fifth active material layer; 230 - sixth active material layer; 240 - seventh active material layer. DETAILED DESCRIPTION

[0078] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0079] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0080] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0081] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0082] In a first aspect of the present invention, a negative electrode sheet is provided. According to an embodiment of the present invention, referring to FIG1 , the negative electrode sheet 100 includes a first current collector 10 , a first active material layer 20 , and a second active material layer 30 .

[0083] According to an embodiment of the present invention, the first current collector 10 includes a first side and a second side opposite to each other. It should be noted that the specific type of the first current collector 10 is not particularly limited, and those skilled in the art can select it according to actual needs. For example, the first current collector 10 can be a metal foil current collector or a composite current collector.

[0084] According to a specific embodiment of the present invention, the first current collector 10 is a metal foil current collector, and the metal foil current collector may include at least one of copper, aluminum, nickel and chromium.

[0085] According to a specific embodiment of the present invention, referring to FIG. 2 , the first current collector 10 is a composite current collector. The first current collector 10 may include a first base film 11 , a first conductive layer 12 , and a second conductive layer 13 .

[0086] According to a specific embodiment of the present invention, the first base film 11 is made of a polymer. The polymer material of the first base film 11 has a lower density than that of metal current collectors such as copper foil. Therefore, the first current collector 10 prepared using the polymer also has a lower density than that of metal current collectors such as copper foil, thereby improving the energy density of the battery.

[0087] It should be noted that the specific material of the first base film 11 is not particularly limited, and those skilled in the art can select it according to actual needs. For example, it may include at least one of polyethylene (PE), polyethylene terephthalate (PET), polyimide (PI), polypropylene (PP), polyamide (PA), polyphenylene sulfide (PPS), and polyethylene naphthalate (PEN). Optionally, the first base film 11 includes at least one of polyethylene terephthalate (PET), polypropylene (PP) and polyimide (PI); alternatively, the first base film 11 includes polyimide and / or polyphenylene sulfide. Polyimide and polyphenylene sulfide have flame retardant effects, thereby reducing the fire problem caused by lithium dendrites piercing the film short circuit.

[0088] According to a specific embodiment of the present invention, the thickness of the first base film 11 may be 1 μm-300 μm, for example, 1 μm, 5 μm, 10 μm, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, etc.

[0089] 2 , the first conductive layer 12 is disposed on one side of the first base film 11. By disposing the first conductive layer 12 on one side of the first base film 11, the conductivity of the first current collector 10 can be improved.

[0090] It should be noted that the material of the first conductive layer 12 is not particularly limited. Those skilled in the art can select it according to actual needs, as long as it has excellent conductivity and good mechanical properties. For example, it can include at least one of copper, aluminum, nickel, and chromium. Specifically, the thickness of the first conductive layer 12 can be 0.2μm-100μm, for example, 0.2μm, 0.5μm, 1μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, etc.

[0091] 2 , the second conductive layer 13 is disposed on the other side of the first base film 11. By disposing the second conductive layer 13 on the other side of the first base film 11, the conductivity of the first current collector 10 can be further improved.

[0092] It should be noted that the material of the second conductive layer 13 is not particularly limited. Those skilled in the art can select it according to actual needs, as long as it has excellent conductivity and good mechanical properties. For example, it can include at least one of copper, aluminum, nickel, and chromium. Specifically, the thickness of the second conductive layer 13 can be 0.2μm-100μm, for example, 0.2μm, 0.5μm, 1μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, etc.

[0093] According to a specific embodiment of the present invention, the first conductive layer 12 and the second conductive layer 13 can be independently prepared by physical vapor deposition (PVD), chemical vapor deposition (CVD) or water electroplating. For example, when aluminum is used as the first conductive layer 12 or the second conductive layer 13, aluminum can be directly plated on the first base film 11 by vapor evaporation; when copper is used as the first conductive layer 12 or the second conductive layer 13, it can be prepared on the first base film 11 by a one-step method, a two-step method or a three-step method, wherein the one-step method includes a chemical deposition one-step method, a vacuum magnetron sputtering one-step method and a vacuum evaporation one-step method. The chemical deposition one-step method is to deposit a copper layer by chemical reaction, the vacuum magnetron sputtering one-step method is to deposit a copper layer by repeated magnetron sputtering, and the vacuum evaporation one-step method is to deposit a copper layer by repeated evaporation; the two-step method is to first use magnetron sputtering to prime, and then use water electroplating to thicken the copper layer; the three-step method is to first use magnetron sputtering to prime, then use vacuum evaporation, and finally use water electroplating to thicken the copper layer.

[0094] Therefore, the negative electrode plate 100 of the present invention can improve the mechanical strength and mechanical properties of the negative electrode plate 100 by adopting the first current collector 10. On the other hand, compared with metal current collectors such as copper foil, the first current collector 10 has the characteristics of low manufacturing cost, high safety, and good compatibility. On the other hand, the density of the first current collector 10 is lower than that of metal current collectors such as copper foil (weight reduction of more than 60%), which can improve the energy density of the battery.

[0095] According to an embodiment of the present invention, referring to FIG1 , a first active material layer 20 and a second active material layer 30 are sequentially disposed on a first side of the first current collector 10 in a direction away from the first current collector 10 . The inventors have discovered that by sequentially disposing the first active material layer 20 and the second active material layer 30 on the first side of the first current collector 10 in a direction away from the first current collector 10 , the first active material layer 20 comprises metallic lithium, which can serve as a supplementary lithium source to improve the cycle life of the battery, and the second active material layer 30 comprises a metallic lithium alloy. This can, on the one hand, prevent the highly reactive metallic lithium in the first active material layer 20 from directly contacting the electrolyte or electrolyte, and on the other hand, enable the metallic lithium to alloy with the metallic lithium alloy in the second active material layer 30 during the charge and discharge process of the battery, effectively avoiding the growth of lithium dendrites caused by uneven deposition of metallic lithium, as well as problems such as continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator caused by an infinite volume change rate, thereby facilitating improved cycle stability of a lithium metal battery using the negative electrode sheet 100 .

[0096] The inventors found that in the related art, the first active material layer is a metallic lithium alloy and the second active material layer is metallic lithium. This solution still causes the metallic lithium to come into direct contact with the electrolyte or electrolyte, causing the growth of lithium dendrites.

[0097] According to a specific embodiment of the present invention, referring to FIG. 3 , the first active material layer 20 may be disposed on the first conductive layer 12 .

[0098] It should be noted that the thickness of the first active material layer 20 and the second active material layer 30 is not particularly limited and can be selected by those skilled in the art according to actual needs. As a preferred embodiment, the thickness of the first active material layer 20 and the second active material layer 30 can be independently 0.1 μm-100 μm, for example, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc.

[0099] According to a specific embodiment of the present invention, the specific composition of the metal lithium alloy is not particularly limited and can be selected by those skilled in the art according to actual needs. For example, the metal lithium alloy may include an alloy formed by metal lithium and at least one of gold, silver, indium, magnesium, zinc, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, manganese, aluminum, copper, tin, sodium, calcium, gallium, boron, silicon, carbon, and phosphorus. Specifically, the content of lithium in the metal lithium alloy may be 2 atm% to 98 atm%, for example, 2 atm%, 5 atm%, 15 atm%, 25 atm%, 35 atm%, 45 atm%, 55 atm%, 65 atm%, 75 atm%, 85 atm%, 95 atm%, 98 atm%, etc.

[0100] According to an embodiment of the present invention, referring to FIG4 , a third active material layer 40 is provided on the second side of the first current collector 10, and the third active material layer 40 includes metallic lithium or a metallic lithium alloy. If the third active material layer 40 includes metallic lithium, the third active material layer 40 can be used as a supplementary lithium source to improve the cycle life of the battery. If the third active material layer 40 includes a metallic lithium alloy, an alloying reaction can be generated between metallic lithium and the metallic lithium alloy in the third active material layer 40 during the charge and discharge process of the battery, thereby further avoiding the growth of lithium dendrites caused by uneven deposition of metallic lithium, as well as problems such as continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by an infinite volume change rate, thereby further facilitating the improvement of the cycle stability of the lithium metal battery using the negative electrode plate 100. Specifically, the third active material layer 40 can be provided on the second conductive layer 13.

[0101] It should be noted that the thickness of the third active material layer 40 is not particularly limited and can be selected by those skilled in the art according to actual needs. As a preferred embodiment, the thickness of the third active material layer 40 can be 0.1 μm-100 μm, for example, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc.

[0102] According to a specific embodiment of the present invention, referring to FIG5 , the third active material layer 40 includes metallic lithium, and a fourth active material layer 50 is provided on the side of the third active material layer 40 away from the first current collector 10. The fourth active material layer 50 includes a metallic lithium alloy. By providing the fourth active material layer 50 on the side of the third active material layer 40 away from the first current collector 10, and by including the metallic lithium alloy, the highly reactive metallic lithium in the third active material layer 40 can be prevented from directly contacting the electrolyte / electrolyte. Furthermore, alloying reaction can occur between the metallic lithium and the metallic lithium alloy in the fourth active material layer 50 during battery charge and discharge, further preventing the growth of lithium dendrites caused by uneven deposition of metallic lithium, as well as problems such as continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator caused by an infinite volume change rate. This helps improve the cycling stability of a metallic lithium battery using the negative electrode sheet 100.

[0103] It should be noted that the thickness of the fourth active material layer 50 is not particularly limited and can be selected by those skilled in the art according to actual needs. As a preferred embodiment, the thickness of the fourth active material layer 50 can be 0.1 μm-100 μm, for example, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc.

[0104] According to a specific embodiment of the present invention, the first active material layer 20, the second active material layer 30, the third active material layer 40, and the fourth active material layer 50 can be prepared by roller pressing (i.e., rolling the metal strip as the active material layer to the surface of the current collector or other active material layer) or physical vapor deposition (PVD, such as magnetron sputtering, vacuum evaporation, etc.). The physical vapor deposition method is preferred, which is conducive to reducing the thickness of the active material layer and achieving uniform deposition, thereby reducing the amount of active material used and reducing the cost of the battery. Specifically, the metal lithium alloy (Li-M) can be formed by magnetron sputtering the metal M onto the surface of the metal Li layer to form an active material layer comprising the metal lithium alloy. A vacuum evaporation method can also be used, that is, metal Li and metal M in the shape of strips, blocks, etc. are placed in a container (e.g., an evaporation boat, a crucible, etc.). Considering the melting points of the metal Li and metal M, different evaporation methods (such as resistance heating, electron beam evaporation, high-frequency heating, laser heating, etc.) and different evaporation temperatures can be used to control the composition and deposition rate of the metal lithium alloy under the premise of setting a reasonable evaporation chamber pressure and substrate temperature.

[0105] Therefore, the negative electrode plate 100 of the present invention can avoid the growth of lithium dendrites caused by uneven deposition of metallic lithium on the negative electrode surface, and solve the problems of continuous thickening of SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate of metallic lithium, thereby helping to improve the cycle stability of lithium metal batteries using the negative electrode plate 100.

[0106] In a second aspect of the present invention, a method for preparing a negative electrode sheet is provided. According to an embodiment of the present invention, referring to FIG6 , the method comprises:

[0107] S100: Providing a first current collector, the first current collector including a first side and a second side opposite to each other

[0108] In this step, a first current collector 10 is provided, comprising a first side and a second side opposite to each other. It should be noted that the specific method for preparing the first current collector 10 is not particularly limited and may include, for example, forming a first conductive layer 12 on one side of a first base film 11; and forming a second conductive layer 13 on a side of the first base film 11 away from the first conductive layer 12. Forming the first conductive layer 12 on one side of the first base film 11 improves the conductivity of the first current collector 10, while forming the second conductive layer 13 on the opposite side of the first base film 11 further improves the conductivity of the first current collector 10.

[0109] S200: forming a first active material layer on the first side of the first current collector, the first active material layer including metallic lithium

[0110] In this step, a first active material layer 20 comprising metallic lithium is formed on the first side of the first current collector 10. The inventors have discovered that forming the first active material layer 20 comprising metallic lithium on the first side of the first current collector 10 can serve as a supplementary lithium source to improve the cycle life of the battery.

[0111] S300: forming a second active material layer on the first active material layer away from the first current collector, the second active material layer including a metal lithium alloy

[0112] In this step, a second active material layer 30 is formed on the first active material layer 20 on the side away from the first current collector 10, and the second active material layer 30 includes a metal lithium alloy. The inventors have discovered that by forming the second active material layer 30 including a metal lithium alloy on the side away from the first current collector 10 of the first active material layer 20, on the one hand, it is possible to prevent the highly reactive metal lithium in the first active material layer 20 from directly contacting the electrolyte or electrolyte, and on the other hand, it is possible to allow the metal lithium to undergo an alloying reaction with the metal lithium alloy in the second active material layer 30 during the battery charge and discharge process, effectively avoiding the uneven deposition of metal lithium causing the growth of lithium dendrites, as well as the problems of continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate, thereby improving the cycle stability of the lithium metal battery using the negative electrode sheet. Specifically, the above-mentioned first active material layer 20 can be formed on the first conductive layer 12.

[0113] The materials of the first base film 11, the first conductive layer 12, the second conductive layer 13, the first active material layer 20 and the second active material layer 30, as well as the preparation methods and thicknesses of the first conductive layer 12, the second conductive layer 13, the first active material layer 20 and the second active material layer 30 have been described in detail above and will not be repeated here.

[0114] According to an embodiment of the present invention, the above-mentioned method for preparing a negative electrode plate further includes: forming a third active material layer 40 on the second side of the first current collector 10, and the third active material layer 40 includes metallic lithium or a metallic lithium alloy. If the third active material layer 40 includes metallic lithium, the third active material layer 40 can be used as a supplementary lithium source to improve the cycle life of the battery. If the third active material layer 40 includes a metallic lithium alloy, an alloying reaction can be caused between the metallic lithium and the metallic lithium alloy in the third active material layer 40 during the charge and discharge process of the battery, thereby further avoiding the growth of lithium dendrites caused by uneven deposition of metallic lithium, as well as problems such as continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by an infinite volume change rate, thereby further facilitating the improvement of the cycle stability of the lithium metal battery using the negative electrode plate 100. Specifically, the third active material layer 40 can be formed on the second conductive layer 13.

[0115] According to a specific embodiment of the present invention, if the third active material layer 40 includes metallic lithium, the above-mentioned method for preparing a negative electrode sheet further includes: forming a fourth active material layer 50 on a side of the third active material layer 40 away from the first current collector 10, wherein the fourth active material layer 50 includes a metallic lithium alloy. By forming the fourth active material layer 50 including a metallic lithium alloy on a side of the third active material layer 40 away from the first current collector 10, on the one hand, direct contact between the highly reactive metallic lithium in the third active material layer 40 and the electrolyte / electrolyte can be avoided; on the other hand, alloying reaction can occur between the metallic lithium and the metallic lithium alloy in the fourth active material layer 50 during the charge and discharge process of the battery, further avoiding the growth of lithium dendrites caused by uneven deposition of metallic lithium, as well as problems such as continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator caused by an infinite volume change rate, thereby improving the cycling stability of the metallic lithium battery.

[0116] It should be noted that the preparation method and thickness of the third active material layer 40 and the fourth active material layer 50 have been described in detail above and will not be repeated here.

[0117] Therefore, the negative electrode plate obtained by the method for preparing the negative electrode plate of the present invention can avoid the growth of lithium dendrites caused by the uneven deposition of metallic lithium on the negative electrode surface, and solve the problems of continuous thickening of SEI film, continuous growth of lithium dendrites, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate of metallic lithium, thereby helping to improve the cycle stability of the lithium metal battery using the negative electrode plate obtained by the method.

[0118] In a third aspect of the present invention, a bipolar pole piece is provided. According to an embodiment of the present invention, referring to FIG7 , the bipolar pole piece 200 includes a second current collector 210 , a fifth active material layer 220 , and a sixth active material layer 230 .

[0119] According to an embodiment of the present invention, the second current collector 200 includes a first side and a second side that are opposite to each other. It should be noted that the specific type of the second current collector 210 is not particularly limited, and those skilled in the art may select it according to actual needs. For example, the second current collector 210 may be a metal foil current collector or a composite current collector.

[0120] According to an embodiment of the present invention, the second current collector 210 is a metal foil current collector. The metal foil current collector may include a stainless steel alloy foil. The stainless steel alloy foil may include at least one of nickel, chromium, and copper.

[0121] According to an embodiment of the present invention, referring to FIG. 8 , the second current collector 210 is a composite current collector, and the second current collector 210 may include a second base film 211 , a third conductive layer 212 , and a fourth conductive layer 213 .

[0122] According to a specific embodiment of the present invention, the second base film 211 is made of a polymer. The second base film 211 is made of a polymer and has a lower density than a metal current collector. Therefore, the second current collector 210 prepared using the polymer also has a lower density than a metal current collector, which can improve the energy density of the battery.

[0123] It should be noted that the specific material of the second base film 211 is not particularly limited, and those skilled in the art can select it according to actual needs. For example, it may include at least one of polyethylene (PE), polyethylene terephthalate (PET), polyimide (PI), polypropylene (PP), polyamide (PA), polyphenylene sulfide (PPS), and PEN. Optionally, the second base film 211 includes at least one of polyethylene terephthalate (PET), polypropylene (PP) and polyimide (PI); alternatively, the second base film 211 includes polyimide and / or polyphenylene sulfide. Polyimide and polyphenylene sulfide have flame retardant effects, thereby reducing the fire problem caused by lithium dendrites piercing the film short circuit.

[0124] According to a specific embodiment of the present invention, the thickness of the second base film 211 may be 1 μm-300 μm, for example, 1 μm, 5 μm, 10 μm, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, etc.

[0125] 8 , the third conductive layer 212 is disposed on one side of the second base film 211. By disposing the third conductive layer 212 on one side of the second base film 211, the conductivity of the second current collector 210 can be improved.

[0126] It should be noted that the material of the third conductive layer 212 is not particularly limited. Those skilled in the art can select it according to actual needs, as long as it has excellent conductivity and good mechanical properties. For example, it can include at least one of copper, aluminum, nickel, and chromium, with copper being preferred. Specifically, the thickness of the third conductive layer 212 can be 0.2 μm-100 μm, for example, 0.2 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc.

[0127] 8 , the fourth conductive layer 213 is disposed on the other side of the second base film 211. By disposing the fourth conductive layer 213 on the other side of the second base film 211, the conductivity of the second current collector 210 can be improved.

[0128] It should be noted that the material of the fourth conductive layer 213 is not particularly limited. Those skilled in the art can select it according to actual needs, as long as it has excellent conductivity and good mechanical properties. For example, it can include at least one of copper, aluminum, nickel and chromium, preferably aluminum. Specifically, the thickness of the fourth conductive layer 213 can be 0.2μm-100μm, for example, 0.2μm, 0.5μm, 1μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, etc.

[0129] According to a specific embodiment of the present invention, the third conductive layer 212 and the fourth conductive layer 213 can be independently formed using physical vapor deposition (PVD), chemical vapor deposition (CVD), or water electroplating. For example, when copper is used as the third conductive layer 212, it can be formed on the second base film 211 using a one-step method, a two-step method, or a three-step method. The specific steps of the one-step method, the two-step method, and the three-step method have been described in detail above and will not be repeated here. When aluminum is used as the fourth conductive layer 213, aluminum can be directly plated on the second base film 211 by vapor evaporation.

[0130] Therefore, the bipolar pole piece 200 of the present invention can improve the mechanical strength and mechanical properties of the bipolar pole piece 200 by adopting the second current collector 210. On the other hand, compared with the metal current collector, the second current collector 210 has the characteristics of low manufacturing cost, high safety and good compatibility. On the other hand, the density of the second current collector 210 is lower than that of the metal current collector (weight reduction of more than 60%), which can improve the energy density of the battery.

[0131] According to a specific embodiment of the present invention, referring to FIG9 , a fifth active material layer 220 is provided on the first side of the second current collector 210 , and the fifth active material layer 220 includes a metal lithium alloy. The inventors have discovered that by providing the fifth active material layer 220 including a metal lithium alloy on the first side of the second current collector 210 , an alloying reaction can occur between the metal lithium and the metal lithium alloy in the fifth active material layer 220 during the charge and discharge process of the battery. This can effectively avoid the growth of lithium dendrites caused by uneven deposition of metal lithium, as well as the problems of continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by an infinite volume change rate, thereby improving the cycle stability of the battery using the bipolar pole piece. Specifically, the fifth active material layer 220 can be provided on the third conductive layer 212 .

[0132] According to a specific embodiment of the present invention, the fifth active material layer 220 can be prepared by rolling or physical vapor deposition. Specifically, the thickness of the fifth active material layer 220 can be 0.1μm-100μm, for example, it can be 0.1μm, 0.5μm, 1μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, etc.

[0133] It should be noted that the specific composition and preparation method of the metallic lithium alloy have been described in detail above and will not be repeated here.

[0134] According to a specific embodiment of the present invention, referring to FIG9 , a sixth active material layer 230 is disposed on the second side of the second current collector 210 . The sixth active material layer 230 includes a positive electrode active material. By disposing the sixth active material layer 230 on the second side of the second current collector 210 , a bipolar electrode sheet can be obtained. Specifically, the sixth active material layer 230 can be disposed on the fourth conductive layer 213 .

[0135] According to a specific embodiment of the present invention, the sixth active material layer 230 can be prepared by a wet coating method or a dry coating method, and the thickness can be 0.1μm-100μm, for example, it can be 0.1μm, 0.5μm, 1μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, etc.

[0136] It should be noted that the specific composition of the positive electrode active material is not particularly limited, and those skilled in the art can select it according to actual needs. For example, it can include lithium nickel cobalt manganese oxide (LiN x M y C z O2, x+y+z=1), lithium manganese iron phosphate (LiFe a Mn bPO4, a+b=1), lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium-rich manganese-based positive electrode materials, lithium nickel manganese oxide (LMNO), lithium vanadium phosphate (Li3V2(PO4)3, LiVOPO4), etc.

[0137] According to an embodiment of the present invention, referring to FIG10 , a seventh active material layer 240 including metallic lithium is disposed on a first side of the second current collector 210. The fifth active material layer 220 is disposed on the seventh active material layer 240 on a side away from the second current collector 210. Compared to the theoretical specific capacity of 372 mAh / g for a graphite negative electrode, metallic lithium has an ultra-high theoretical specific capacity of 3860 mAh / g and a most negative standard reduction potential (-3.04 V). It also has the characteristics of low density and small ionic radius. By disposing the seventh active material layer 240 including metallic lithium on the first side of the second current collector 210, it can serve as a supplementary lithium source to improve the cycle life of the battery. The fifth active material layer 220, comprising a metallic lithium alloy, is disposed on the seventh active material layer 240 on a side away from the second current collector 210. This prevents the highly reactive metallic lithium in the seventh active material layer 240 from direct contact with the electrolyte. Furthermore, it allows the metallic lithium to alloy with the metallic lithium alloy in the fifth active material layer 220 during battery charge and discharge, effectively preventing problems such as uneven deposition of metallic lithium leading to lithium dendrite growth, and the continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator due to an infinite volume change rate. This helps improve the cycling stability of batteries using the bipolar pole piece 200. Specifically, the seventh active material layer 240 can be disposed on the third conductive layer 212.

[0138] According to a specific embodiment of the present invention, the seventh active material layer 240 can be prepared by rolling or physical vapor deposition, and the thickness can be 0.1μm-100μm, for example, it can be 0.1μm, 0.5μm, 1μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, etc.

[0139] Therefore, the bipolar pole piece 200 of the present invention can avoid the growth of lithium dendrites caused by uneven deposition of metallic lithium on the negative electrode surface, and solve the problems of continuous thickening of SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate of metallic lithium, thereby helping to improve the cycle stability of the battery using the bipolar pole piece 200.

[0140] In a fourth aspect of the present invention, referring to FIG11 , the present invention provides a method for preparing a bipolar pole piece. According to an embodiment of the present invention, the method comprises:

[0141] S1000: Providing a second current collector, the second current collector including a first side and a second side opposite to each other

[0142] In this step, a second current collector 210 is provided. The second current collector 210 includes a first side and a second side that are opposite to each other. It should be noted that the specific method for preparing the second current collector 210 is not particularly limited and may, for example, include: forming a third conductive layer 212 on one side of the second base film 211; and forming a fourth conductive layer 213 on the side of the second base film 211 away from the third conductive layer 212. Forming the third conductive layer 212 on one side of the second base film 211 can improve the conductivity of the second current collector 210. Simultaneously, forming the fourth conductive layer 213 on the side of the second base film 211 away from the third conductive layer 212 can also improve the conductivity of the second current collector 210.

[0143] S2000: forming a fifth active material layer on the first side of the second current collector, the fifth active material layer including a metal lithium alloy

[0144] In this step, a fifth active material layer 220 is formed on the first side of the second current collector 210. The fifth active material layer 220 includes a metallic lithium alloy. The inventors have discovered that by forming the fifth active material layer 220 including a metallic lithium alloy on the first side of the second current collector 210, an alloying reaction can occur between the metallic lithium and the metallic lithium alloy in the fifth active material layer 220 during the battery charge and discharge process. This effectively avoids the problems of lithium dendrite growth caused by uneven deposition of metallic lithium, as well as the continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by an infinite volume change rate, thereby improving the cycle stability of the battery using this bipolar pole piece. Specifically, the fifth active material layer 220 can be formed on the third conductive layer 212.

[0145] S3000: forming a sixth active material layer on the second side of the second current collector, the sixth active material layer including a positive electrode active material

[0146] In this step, a sixth active material layer 230 including a positive electrode active material is formed on the second side of the second current collector 210. By forming the sixth active material layer 230 including a positive electrode active material on the second side of the second current collector 210, a bipolar electrode sheet can be obtained.

[0147] The materials of the second base film 211, the third conductive layer 212, the fourth conductive layer 213, the fifth active material layer 220 and the sixth active material layer 230, as well as the preparation methods and thicknesses of the third conductive layer 212, the fourth conductive layer 213, the fifth active material layer 220 and the sixth active material layer 230 have been described in detail above and will not be repeated here.

[0148] According to an embodiment of the present invention, the method for preparing the bipolar pole piece 200 further includes: forming a seventh active material layer 240 on the first side of the second current collector 210 before forming the fifth active material layer 220 on the first side of the second current collector 210. The seventh active material layer 240 includes metallic lithium. Compared to the theoretical specific capacity of 372 mAh / g for a graphite negative electrode, metallic lithium has an ultra-high theoretical specific capacity of 3860 mAh / g and a most negative standard reduction potential (-3.04 V). It also has the characteristics of low density and small ionic radius. By forming the seventh active material layer 240 including metallic lithium on the first side of the second current collector 210 before forming the fifth active material layer 220 on the first side of the second current collector 210, the seventh active material layer 240 can serve as a supplementary lithium source to improve the cycle life of the battery. The fifth active material layer 220 comprising a metallic lithium alloy is formed on the side of the seventh active material layer 240 away from the second current collector 210, which is beneficial to reducing problems such as continuous thickening of the SEI film, continuous growth of lithium dendrites, dead lithium, and lithium dendrites piercing the diaphragm caused by direct contact between the highly reactive metallic lithium in the seventh active material layer 240 and the electrolyte / electrolyte, thereby helping to improve the cycle stability of the battery.

[0149] Therefore, the bipolar pole piece obtained by the method for preparing the bipolar pole piece of the present invention can avoid the growth of lithium dendrites caused by the uneven deposition of metallic lithium on the negative electrode surface, and solve the problems of continuous thickening of SEI film, dead lithium, and lithium dendrites piercing the diaphragm caused by the infinite volume change rate of metallic lithium, thereby helping to improve the cycle stability of the battery.

[0150] In its fifth aspect, the present invention provides a battery. According to an embodiment of the present invention, the battery comprises the aforementioned negative electrode sheet, or a negative electrode sheet obtained using the aforementioned method for preparing a negative electrode sheet, or the aforementioned bipolar electrode sheet, or a bipolar electrode sheet obtained using the aforementioned method for preparing a bipolar electrode sheet. As a result, the battery exhibits high cycling stability. It should be noted that the features and advantages described above for the negative electrode sheet or bipolar electrode sheet also apply to this battery and will not be further elaborated here.

[0151] According to an embodiment of the present invention, the above-mentioned battery may include a liquid battery, a semi-solid battery and an all-solid battery.

[0152] According to a specific embodiment of the present invention, the battery may include the above-mentioned negative electrode sheet or a negative electrode sheet obtained by the above-mentioned method for preparing a negative electrode sheet, a positive electrode sheet, a separator and an electrolyte, which are composed of a liquid laminate battery, a liquid wound battery or a liquid cylindrical battery.

[0153] According to a specific embodiment of the present invention, the above-mentioned electrolyte mainly includes a lithium salt, a solvent and an optional additive. Specifically, the solvent may include carbonates (such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone (BL)), ethers (such as tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (2-Me-THF), dimethoxydimethyl ether (DMM), 1,2-dimethoxyethane (DME)), nitriles (such as acetonitrile (AN)), etc.; the lithium salt may include lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), other organic lithium salts (such as lithium trifluoromethanesulfonate (LiCF3SO), bis(trifluoromethanesulfonic acid) Lithium amide (LiTFSI), lithium bisfluorosulfonyl imide (LiFSI), lithium trifluoromethylsulfonyl-perfluorobutylsulfonyl imide (LiTNFSI), lithium fluorosulfonyl-perfluorobutylsulfonyl imide (LiFNFSI), lithium bisoxalatoborate (LiBOB), tris(trifluoromethylsulfonyl)methyl lithium (LiC(SO2CF3)3), etc.); additives may include film-forming additives, conductive additives, flame retardant additives, overcharge protection additives, water and HF content control additives (i.e., additives for controlling the water and HF content in the electrolyte), low-temperature additives (i.e., general additives for improving low-temperature performance), and may also include negative electrode stabilizers, i.e., additives for improving the interface stability of the metallic lithium negative electrode (such as fluoroethylene carbonate (FEC), lithium nitrate (LiNO3), etc.).

[0154] According to a specific embodiment of the present invention, the battery may also include a semi-solid laminated battery, a semi-solid wound battery or a semi-solid cylindrical battery consisting of the above-mentioned negative electrode sheet or the negative electrode sheet obtained by the above-mentioned method for preparing the negative electrode sheet, a positive electrode sheet and a gel electrolyte.

[0155] According to a specific embodiment of the present invention, the battery may also include the above-mentioned negative electrode sheet or the negative electrode sheet obtained by the above-mentioned method for preparing the negative electrode sheet, a positive electrode sheet, a gel electrolyte and optionally 0.5wt%-50wt% of additives, forming a semi-solid laminated battery, a semi-solid wound battery or a semi-solid cylindrical battery.

[0156] According to a specific embodiment of the present invention, the battery may also include a solid-state laminated battery, a solid-state wound battery or a solid-state cylindrical battery consisting of the above-mentioned negative electrode sheet or a negative electrode sheet obtained by the above-mentioned method for preparing the negative electrode sheet, a positive electrode sheet and a solid electrolyte.

[0157] According to a specific embodiment of the present invention, the battery may include the above-mentioned bipolar pole piece or a liquid laminated battery, a liquid wound battery or a liquid cylindrical battery consisting of a bipolar pole piece obtained by the above-mentioned method for preparing a bipolar pole piece, a diaphragm and an electrolyte.

[0158] According to a specific embodiment of the present invention, the battery may also include a semi-solid laminated battery, a semi-solid wound battery or a semi-solid cylindrical battery consisting of the above-mentioned bipolar pole piece or the bipolar pole piece obtained by the above-mentioned method for preparing the bipolar pole piece and a gel electrolyte.

[0159] According to a specific embodiment of the present invention, the battery may also include a semi-solid laminated battery, a semi-solid wound battery or a semi-solid cylindrical battery consisting of the above-mentioned bipolar pole piece or a bipolar pole piece obtained by the above-mentioned method for preparing a bipolar pole piece, a gel electrolyte and optionally 0.5wt%-50wt% of an additive.

[0160] According to a specific embodiment of the present invention, the battery may also include a solid-state laminated battery, a solid-state wound battery or a solid-state cylindrical battery consisting of the above-mentioned bipolar pole piece or the bipolar pole piece obtained by the above-mentioned method for preparing the bipolar pole piece and a solid-state electrolyte.

[0161] According to a specific embodiment of the present invention, the specific types of the above-mentioned positive electrode plate and its positive electrode active material are not particularly limited, and those skilled in the art can select according to actual needs. For example, the positive electrode plate can be a positive electrode plate using a metal foil current collector, or a positive electrode plate using a current collector, and its positive electrode active material can include lithium nickel cobalt manganese oxide (LiN x M y C z O2, x+y+z=1), lithium manganese iron phosphate (LiFe a Mn b PO4, a+b=1), at least one of lithium iron phosphate, lithium manganate, lithium cobaltate, lithium nickelate, lithium-rich manganese-based positive electrode material, lithium nickel manganate (LMNO) and lithium vanadium phosphate (Li3V2(PO4)3, LiVOPO4).

[0162] According to a specific embodiment of the present invention, the separator may include polypropylene (PP) and / or polyethylene (PE).

[0163] According to a specific embodiment of the present invention, the above-mentioned solid electrolyte may include an inorganic solid electrolyte (such as an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte), a polymer solid electrolyte and a composite solid electrolyte (such as a composite solid electrolyte based on a polymer matrix and an inorganic filler). Specifically, the oxide solid electrolyte may include a NASICON type (stable structure, such as LATP (Li 1.3 Al 0.3 Ti1.7 (PO4)3)、LAGP(Li 1.5 Al 0.5 Ge 1.5 P3O 12 ), perovskite type, garnet type (highest conductivity, 10 -3 S / cm, which has good stability to metallic lithium, such as lithium lanthanum zirconium oxide (LLZO); sulfide solid electrolytes can include binary compounds (such as Li2S-SiS2 and Li2S-P2S5, Li2S-GeS2, etc.), ternary compounds (such as Li2S-MS2-P2S5 (M=Si, Ge, Sn, Al, etc.), and Li6PS5X (X=F, Cl, Br, I); halide solid electrolytes can include Li a MX4 type (X represents halogen elements, such as Li2MnCl4, Li2ZnCl4, etc. formed by divalent metal ions, and halide electrolytes formed by trivalent and other valence metal ions M, such as LiYbF4, LiAlF4), Li a MX6 (such as Li3YCl6 (LYC) and Li3BrCl6 (LYB)) and Li a MX8 type (such as Li6CoCl8). The polymer solid electrolyte can include polyethylene oxide (PEO), polycarbonate, polytrimethylene carbonate (PTMC), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoroethylene copolymer, lithium polyacrylate (PAL) and other polymer matrices, LATP, lithium lanthanum zirconium oxide (LLZO), aluminum oxide (Al2O3), metal organic frameworks (MOFs) and other inorganic fillers and LiAsF6, lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4) and other lithium salts. Specifically, the gel electrolyte can include at least one of the above solid electrolytes and at least one of the above electrolytes.

[0164] In a sixth aspect, the present invention provides an electrical device. According to an embodiment of the present invention, the electrical device includes the aforementioned battery. The electrical device and the aforementioned battery have the same advantages over the prior art, which will not be further elaborated here.

[0165] The present invention is described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present invention in any way.

[0166] Example 1

[0167] A negative electrode sheet, referring to FIG1 and FIG2 , includes a first current collector 10 , a first active material layer 20 , and a second active material layer 30 ;

[0168] The first current collector 10 includes a first base film 11, a first conductive layer 12, and a second conductive layer 13. The first conductive layer 12 is provided on a surface of one side of the first base film 11, and the second conductive layer 13 is provided on a surface of the other side opposite to the first base film 11. The first base film 11 is made of polypropylene and has a thickness of 1 μm. The first conductive layer 12 is made of copper and has a thickness of 0.2 μm. The second conductive layer 13 is also made of copper and has a thickness of 0.2 μm.

[0169] The first current collector 10 includes a first side and a second side facing each other. The first active material layer 20 and the second active material layer 30 are sequentially arranged on the first side of the first current collector 10 in a direction away from the first current collector 10. The first active material layer 20 is made of metallic lithium and has a thickness of 100 μm. The second active material layer 30 is made of metallic lithium alloy and has a thickness of 100 μm. The metallic lithium alloy in the second active material layer 30 is an alloy formed by metallic lithium and magnesium, and the lithium content is 2 atm%.

[0170] Example 2

[0171] A negative electrode sheet, referring to FIG1 and FIG2 , includes a first current collector 10 , a first active material layer 20 , and a second active material layer 30 ;

[0172] The first current collector 10 includes a first base film 11, a first conductive layer 12, and a second conductive layer 13. The first conductive layer 12 is provided on a surface of one side of the first base film 11, and the second conductive layer 13 is provided on a surface of the other side opposite to the first base film 11. The first base film 11 is made of polypropylene and has a thickness of 300 μm. The first conductive layer 12 is made of copper and has a thickness of 100 μm. The second conductive layer 13 is also made of copper and has a thickness of 100 μm.

[0173] The first current collector 10 includes a first side and a second side opposite to each other, and the first active material layer 20 and the second active material layer 30 are sequentially arranged on the first side of the first current collector 10 in a direction away from the first current collector 10; the material of the first active material layer 20 is metallic lithium with a thickness of 0.1 μm, and the material of the second active material layer 30 is metallic lithium alloy with a thickness of 0.1 μm. The metallic lithium alloy in the second active material layer 30 is an alloy formed by metallic lithium and magnesium, and the lithium content is 98 atm%.

[0174] Example 3

[0175] A negative electrode sheet, referring to Figure 4, includes a first current collector 10, a first active material layer 20, a second active material layer 30 and a third active material layer 40. The material of the third active material layer 40 is metallic lithium and has a thickness of 0.1 μm. The third active material layer 40 is arranged on the second side of the first current collector 10. The rest is the same as in Example 1.

[0176] Example 4

[0177] A negative electrode sheet, referring to Figure 4, includes a first current collector 10, a first active material layer 20, a second active material layer 30 and a third active material layer 40. The material of the third active material layer 40 is metallic lithium and has a thickness of 100 μm. The third active material layer 40 is arranged on the second side of the first current collector 10. The rest is the same as in Example 1.

[0178] Example 5

[0179] A negative electrode sheet, referring to FIG4 , includes a first current collector 10 , a first active material layer 20 , a second active material layer 30 and a third active material layer 40 . The third active material layer 40 is made of a metallic lithium alloy. The rest is the same as in Example 3.

[0180] Example 6

[0181] A negative electrode sheet, referring to FIG4 , includes a first current collector 10 , a first active material layer 20 , a second active material layer 30 and a third active material layer 40 . The third active material layer 40 is made of a metallic lithium alloy and has a thickness of 100 μm. The rest is the same as in Example 3.

[0182] Example 7

[0183] A negative electrode sheet, referring to Figure 5, includes a first current collector 10, a first active material layer 20, a second active material layer 30, a third active material layer 40 and a fourth active material layer 50. The fourth active material layer 50 is made of a metallic lithium alloy with a thickness of 0.1 μm. The fourth active material layer 50 is arranged on a side of the third active material layer 40 including metallic lithium away from the first current collector 10. The rest is the same as in Example 3.

[0184] Example 8

[0185] A negative electrode sheet, referring to Figure 5, includes a first current collector 10, a first active material layer 20, a second active material layer 30, a third active material layer 40 and a fourth active material layer 50. The fourth active material layer 50 is made of a metallic lithium alloy and has a thickness of 100 μm. The fourth active material layer 50 is arranged on a side of the third active material layer 40 including metallic lithium away from the first current collector 10. The rest is the same as in Example 3.

[0186] Example 9

[0187] A bipolar pole piece, referring to FIG7 and FIG8 , includes a second current collector 210 , a fifth active material layer 220 and a sixth active material layer 230 ;

[0188] The second current collector 210 includes a second base film 211, a third conductive layer 212, and a fourth conductive layer 213. The third conductive layer 212 is provided on one surface of the second base film 211, and the fourth conductive layer 213 is provided on the other surface of the second base film 211. The second base film 211 is made of polypropylene and has a thickness of 300 μm. The third conductive layer 212 is made of copper and has a thickness of 100 μm. The fourth conductive layer 213 is made of aluminum and has a thickness of 100 μm.

[0189] The second current collector 210 includes a first side and a second side opposite to each other. The fifth active material layer 220 is provided on the first side of the second current collector 210 (i.e., the side of the third conductive layer 212 away from the second base film 211). The sixth active material layer 230 is provided on the second side of the second current collector 210 (i.e., the side of the fourth conductive layer 213 away from the second base film 211). The material of the fifth active material layer 220 is a metal lithium alloy with a thickness of 1 μm. The metal lithium alloy in the fifth active material layer 220 is an alloy formed by metal lithium and magnesium, and the lithium content is 2 atm%. The sixth active material layer 230 includes a positive electrode active material lithium nickel cobalt manganese oxide (LiN 0.8 M 0.1 C 0.1 O2), with a thickness of 1 μm.

[0190] Example 10

[0191] A bipolar pole piece, referring to FIG7 and FIG8 , includes a second current collector 210 , a fifth active material layer 220 and a sixth active material layer 230 ;

[0192] The second current collector 210 includes a second base film 211, a third conductive layer 212, and a fourth conductive layer 213. The third conductive layer 212 is provided on one surface of the second base film 211, and the fourth conductive layer 213 is provided on the other surface of the second base film 211. The second base film 211 is made of polypropylene with a thickness of 1 μm, the third conductive layer 212 is made of copper with a thickness of 0.5 μm, and the fourth conductive layer 213 is made of aluminum with a thickness of 0.5 μm.

[0193] The second current collector 210 includes a first side and a second side opposite to each other. The fifth active material layer 220 is provided on the first side of the second current collector 210 (i.e., the side of the third conductive layer 212 away from the second base film 211). The sixth active material layer 230 is provided on the second side of the second current collector 210 (i.e., the side of the fourth conductive layer 213 away from the second base film 211). The material of the fifth active material layer 220 is a metal lithium alloy with a thickness of 100 μm. The metal lithium alloy in the fifth active material layer 220 is an alloy formed by metal lithium and magnesium, and the lithium content is 98 atm%. The sixth active material layer 230 includes a positive electrode active material lithium nickel cobalt manganese oxide (LiN 0.8 M 0.1 C 0.1 O2), with a thickness of 100 μm.

[0194] Example 11

[0195] A bipolar pole piece, referring to FIG10 , includes a second current collector 210 , a fifth active material layer 220 , a sixth active material layer 230 and a seventh active material layer 240 . The seventh active material layer 240 is made of metallic lithium and has a thickness of 100 μm. The seventh active material layer 240 is arranged on a first side of the second current collector 210 , and the fifth active material layer 220 is arranged on a surface of the seventh active material layer 240 away from the second current collector 210 . The rest is the same as in Example 9.

[0196] Example 12

[0197] A bipolar pole piece, referring to Figure 10, includes a second current collector 210, a fifth active material layer 220, a sixth active material layer 230 and a seventh active material layer 240. The material of the seventh active material layer 240 is metallic lithium and has a thickness of 1 μm. The seventh active material layer 240 is arranged on the first side of the second current collector 210, and the fifth active material layer 220 is arranged on the surface of the seventh active material layer 240 away from the second current collector 210. The rest is the same as Example 9.

[0198] Liquid batteries were assembled using the negative electrode sheets of Examples 1-8 and the bipolar electrode sheets of Examples 9-12:

[0199] 1. Preparation of positive electrode sheet

[0200] The positive electrode active material LiNi 0.7 Co 0.1 Mn 0.1 O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are prepared into positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 50wt%, and the solid content of LiNi 0.7 Co 0.1 Mn 0.1The mass ratio of O2, Super P and PVDF is 8:1:1. The positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil and dried at 85°C and then cold pressed. Then, it is trimmed, cut and striped, and dried under vacuum conditions at 85°C for 4 hours to make the positive electrode sheet.

[0201] 2. Preparation of electrolyte

[0202] In an argon atmosphere glove box (H2O <0.1ppm, O2 <0.1ppm), the fully dried electrolyte salt LiPF6 was dissolved in a mixed solvent (the mixed solvent included ethylene carbonate (EC) and diethyl carbonate (DEC), and ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a mass ratio of 50:50), and after mixing evenly, an electrolyte solution with a concentration of 1 mol / L was obtained.

[0203] 3. Isolation film

[0204] A 16 μm polyethylene film was used as the separator.

[0205] 4. Preparation of lithium metal batteries

[0206] The positive electrode sheet, the isolation film, and the negative electrode sheet of Examples 1-8 are stacked in order, so that the isolation film is placed between the positive and negative electrode sheets to isolate the positive and negative electrodes. The bare battery cell is wound and the tabs are welded. The bare battery cell is placed in an outer package, and the electrolyte prepared above is injected into the dried battery cell. The battery cell is packaged, allowed to stand, formed, shaped, and capacity tested to complete the preparation of the lithium metal battery.

[0207] The bipolar pole pieces and isolation films of Examples 9-12 are stacked in order, wound to obtain bare cells, and the tabs are welded. The bare cells are placed in outer packaging, and the above-prepared electrolyte is injected into the dried cells. The cells are packaged, allowed to stand, formed, shaped, and capacity tested to complete the preparation of the lithium metal battery.

[0208] The cycle performance of the lithium metal batteries obtained from the negative electrode sheets of Examples 1-8 and the bipolar electrode sheets of Examples 9-12 was characterized.

[0209] Cycling performance test method for lithium metal batteries

[0210] The battery was charged at a constant current of 0.2C at 25°C±2°C until the battery voltage reached 4.2V. The battery was then switched to constant voltage charging until the charging current dropped to 0.05C and charging was stopped. The battery was allowed to stand for 30 minutes after charging and discharged at a current of 0.3C until the battery voltage reached 2.6V. After 50 cycles of the above charge and discharge process, the battery was disassembled and the negative electrode sheets of Examples 1-8 and the bipolar electrode sheets of Examples 9-12 were tested by scanning electron microscope (SEM).

[0211] From the obtained SEM images, it can be seen that the surfaces of the negative electrode sheets of Examples 1-8 and the negative electrode surfaces of the bipolar sheets of Examples 9-12 are uniform and relatively flat, and no obvious growth of lithium dendrites is observed.

[0212] It can be seen from Examples 1-12 that the use of this negative electrode plate or bipolar electrode plate can avoid problems such as continuous thickening of the SEI film, continuous growth of lithium dendrites, dead lithium, and lithium dendrites piercing the diaphragm, thereby helping to improve the cycle stability of the battery using the negative electrode plate or bipolar electrode plate.

[0213] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0214] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A negative electrode plate, characterized in that: include: a first current collector comprising opposing first and second sides; A first active material layer and a second active material layer, wherein the first active material layer and the second active material layer are sequentially arranged on the first side in a direction away from the first current collector, the first active material layer includes metallic lithium, and the second active material layer includes a metallic lithium alloy.

2. The negative electrode sheet according to claim 1, characterized in that: The first current collector is a composite current collector.

3. The negative electrode sheet according to claim 1, characterized in that: The first current collector is a metal foil current collector, and the metal foil current collector includes at least one of copper, aluminum, nickel and chromium.

4. The negative electrode sheet according to claim 2, characterized in that: The first current collector includes a first base film, a first conductive layer disposed on one side of the first base film, and a second conductive layer disposed on the other side opposite to the first base film.

5. The negative electrode sheet according to claim 4, characterized in that: The first conductive layer and the second conductive layer each independently include at least one of copper, aluminum, nickel and chromium.

6. The negative electrode sheet according to claim 4 or 5, characterized in that: The thickness of the first conductive layer and the second conductive layer are independently 0.2 μm-100 μm.

7. The negative electrode sheet according to claim 4, characterized in that: The first base film includes at least one of polyethylene, polyethylene terephthalate, polyimide, polypropylene, polyamide, polyphenylene sulfide, and polyethylene naphthalate.

8. The negative electrode sheet according to claim 4 or 7, characterized in that: The thickness of the first base film is 1 μm-300 μm.

9. The negative electrode sheet according to claim 4, characterized in that: A third active material layer is disposed on the second side of the first current collector, and the third active material layer includes metallic lithium or metallic lithium alloy.

10. The negative electrode sheet according to claim 9, characterized in that: The first active material layer is disposed on the first conductive layer, and the third active material layer is disposed on the second conductive layer.

11. The negative electrode sheet according to claim 9, characterized in that: The third active material layer includes metallic lithium. A fourth active material layer is disposed on a side of the third active material layer away from the first current collector. The fourth active material layer includes metallic lithium alloy.

12. The negative electrode sheet according to claim 1, 9 or 11, characterized in that: The metallic lithium alloy includes an alloy formed by metallic lithium and at least one of gold, silver, indium, magnesium, zinc, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, manganese, aluminum, copper, tin, sodium, calcium, gallium, boron, silicon, carbon and phosphorus.

13. The negative electrode sheet according to claim 12, characterized in that: The content of lithium element in the metal lithium alloy is 2atm%-98atm%.

14. The negative electrode sheet according to claim 11, characterized in that: The thickness of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer are independently 0.1 μm to 100 μm.

15. A method for preparing a negative electrode sheet, characterized in that: include: providing a first current collector comprising opposing first and second sides; forming a first active material layer on a first side of the first current collector, wherein the first active material layer includes metallic lithium; A second active material layer is formed on the first active material layer at a side away from the first current collector, and the second active material layer includes a metal lithium alloy.

16. The method according to claim 15, characterized in that Also includes: A third active material layer is formed on the second side of the first current collector, wherein the third active material layer includes metallic lithium or a metallic lithium alloy.

17. The method according to claim 16, characterized in that The third active material layer includes metallic lithium, and the method further includes: A fourth active material layer is formed on a side of the third active material layer away from the first current collector, and the fourth active material layer includes a metal lithium alloy.

18. A bipolar pole piece, characterized in that: include: a second current collector comprising opposing first and second sides; A fifth active material layer and a sixth active material layer, wherein the fifth active material layer is disposed on the first side of the second current collector, and the sixth active material layer is disposed on the second side of the second current collector, the fifth active material layer comprises a metallic lithium alloy, and the sixth active material layer comprises a positive electrode active material.

19. The bipolar pole piece according to claim 18, characterized in that: A seventh active material layer is disposed on a first side of the second current collector, the seventh active material layer includes metallic lithium, and the fifth active material layer is disposed on a side of the seventh active material layer away from the second current collector.

20. The bipolar pole piece according to claim 18 or 19, characterized in that: The second current collector is a composite current collector.

21. The bipolar pole piece according to claim 18 or 19, characterized in that: The second current collector is a metal foil current collector, and the metal foil current collector includes a stainless steel alloy foil, and the stainless steel alloy foil includes at least one of nickel, chromium and copper.

22. The bipolar pole piece according to claim 18, characterized in that: The second current collector includes a second base film, a third conductive layer disposed on one side of the second base film, and a fourth conductive layer disposed on the other side opposite to the second base film, the fifth active material layer is disposed on the third conductive layer, and the sixth active material layer is disposed on the fourth conductive layer.

23. The bipolar pole piece according to claim 19, characterized in that: The second current collector includes a second base film, a third conductive layer arranged on one side of the second base film, and a fourth conductive layer arranged on the other side opposite to the second base film, the seventh active material layer is arranged on the third conductive layer, and the sixth active material layer is arranged on the fourth conductive layer.

24. The bipolar pole piece according to claim 22 or 23, characterized in that: The third conductive layer and the fourth conductive layer each independently include at least one of copper, aluminum, nickel, and chromium.

25. The bipolar pole piece according to claim 18, characterized in that: The positive electrode active material includes at least one of lithium nickel cobalt manganese oxide, lithium iron manganese phosphate, lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium rich manganese-based positive electrode material, lithium nickel manganese oxide and lithium vanadium oxyphosphate.

26. A method for preparing a bipolar pole piece, characterized in that: include: providing a second current collector comprising opposing first and second sides; forming a fifth active material layer on the first side of the second current collector, wherein the fifth active material layer includes a metal lithium alloy; A sixth active material layer is formed on the second side of the second current collector, the sixth active material layer including a positive electrode active material.

27. The method according to claim 26, characterized in that Also includes: Before forming the fifth active material layer on the first side of the second current collector, a seventh active material layer is formed on the first side of the second current collector in advance, and the seventh active material layer includes metallic lithium.

28. A battery, characterized in that: It comprises the negative electrode sheet according to any one of claims 1 to 14, or the negative electrode sheet obtained by the method according to any one of claims 15 to 17, or the bipolar electrode sheet according to any one of claims 18 to 25, or the bipolar electrode sheet obtained by the method according to claim 26 or 27.

29. The battery according to claim 28, characterized in that The batteries include liquid batteries, semi-solid batteries and all-solid batteries.

30. The battery according to claim 28, characterized in that The battery includes a liquid battery and a semi-solid battery, and the battery includes an electrolyte, and the electrolyte includes a lithium salt and a solvent.

31. The battery according to claim 30, characterized in that The lithium salt includes at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethylsulfonate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethylsulfonyl-perfluorobutylsulfonylimide, lithium fluorosulfonyl-perfluorobutylsulfonylimide, lithium bis(oxalatoborate) and tris(trifluoromethylsulfonyl)methyllithium.

32. The battery according to claim 30 or 31, characterized in that The solvent includes at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, tetrahydrofuran, 2-methyl-tetrahydrofuran, dimethoxydimethyl ether, 1,2-dimethoxyethane and acetonitrile.

33. The battery according to claim 30, characterized in that The electrolyte also includes additives.

34. The battery according to claim 33, characterized in that The additive includes at least one of a film-forming additive, a conductive additive, a flame retardant additive, an overcharge protection additive, an additive for controlling water and HF content, a low-temperature additive, and a negative electrode stabilizer.

35. The battery according to claim 28, characterized in that The battery includes a semi-solid-state battery and an all-solid-state battery. The battery includes an electrolyte, and the electrolyte includes at least one of an inorganic solid electrolyte, a polymer solid electrolyte, and a composite solid electrolyte.

36. The battery according to claim 35, characterized in that The inorganic solid electrolyte includes at least one of an oxide solid electrolyte, a sulfide solid electrolyte and a halide solid electrolyte; the oxide solid electrolyte includes at least one of a NASICON-type solid electrolyte, a perovskite-type solid electrolyte and a garnet-type solid electrolyte; the sulfide solid electrolyte includes at least one of Li6PS5F, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li2S-SiS2, Li2S-P2S5, Li2S-GeS2, Li2S-SiS2-P2S5, Li2S-GeS2-P2S5, Li2S-SnS2-P2S5 and Li2S-AlS2-P2S5; the halide solid electrolyte includes at least one of Li2MnCl4, Li2ZnCl4, LiYbF4, LiAlF4, Li3YCl6, Li3BrCl6 and Li6CoCl8.

37. The battery according to claim 35, characterized in that The polymer solid electrolyte comprises a polymer matrix, an inorganic filler and a lithium salt, wherein the polymer matrix comprises at least one of polyethylene oxide, polycarbonate, polytrimethylene carbonate, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoroethylene copolymer and lithium polyacrylate, and the inorganic filler comprises Li 1.3 Al 0.3 Ti 1.7 (PO4)3, lithium lanthanum zirconium oxide, aluminum oxide and metal organic framework, and the lithium salt includes at least one of LiAsF6, LiPF6, LiClO4, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium tetrafluoroborate.

38. An electrical device, characterized in that: A battery comprising any one of claims 28-37.

Images