Negative pole piece and preparation method thereof, bipolar pole piece and preparation method thereof, battery and electric device

Abstract

The invention discloses a negative pole piece and a preparation method thereof, a bipolar pole piece and a preparation method thereof, a battery and an electric device. The negative pole piece comprises a first current collector and a second current collector, wherein the first current collector comprises a first side and a second side which are opposite to each other; the first active material layer and the second active material layer are sequentially arranged on the first side in the direction away from the first current collector, the first active material layer comprises metal lithium, and the second active material layer comprises metal lithium alloy. By adopting the negative pole piece or the bipolar pole piece, the problems of continuous thickening of an SEI film, continuous growth of lithium dendrites, lithium death, penetration of the lithium dendrites to a diaphragm and the like can be avoided, so that the cycle stability of a battery applying the negative pole piece or the bipolar pole piece is favorably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and particularly relates to a negative electrode plate and a preparation method thereof, a bipolar plate and a preparation method thereof, a battery, and an electrical device. Background Art

[0002] Compared with the theoretical specific capacity of 372 mAh / g of the graphite negative electrode, metallic lithium has an ultra-high theoretical specific capacity of 3860 mAh / g and the most negative standard reduction potential (-3.04 V), and also has the characteristics of low density and small ionic radius. Using metallic lithium as the negative electrode active material of the battery can further improve the energy density of the battery. However, the direct contact between metallic lithium and the electrolyte or electrolyte brings problems such as the growth of lithium dendrites and the piercing of the separator, which hinders the large-scale application of lithium metal batteries. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, an object of the present invention is to provide a negative electrode plate and a preparation method thereof, a bipolar plate and a preparation method thereof, a battery, and an electrical device. Using the negative electrode plate or the bipolar plate can avoid problems such as the continuous thickening of the SEI film, the continuous growth of lithium dendrites, dead lithium, and the piercing of the separator by lithium dendrites, thereby being beneficial to improving the cycle stability of the battery using the negative electrode plate or the bipolar plate.

[0004] In the first aspect of the present invention, a negative electrode plate is provided. According to an embodiment of the present invention, the negative electrode plate includes:

[0005] A first current collector, the first current collector including a first side and a second side opposite to each other;

[0006] A first active material layer and a second active material layer, the first active material layer and the second active material layer are sequentially arranged on the first side along the 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.

[0007] According to the negative electrode sheet of the above embodiment of the present invention, by sequentially arranging a first active material layer and a second active material layer 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. The second active material layer includes a metallic lithium alloy. On the one hand, it can prevent the highly reactive metallic lithium in the first active material layer from directly contacting the electrolyte or the electrolyte. On the other hand, during the charge and discharge process of the battery, an alloying reaction occurs between the metallic lithium and the metallic lithium alloy in the second active material layer, effectively avoiding problems such as uneven deposition of metallic lithium causing lithium dendrite growth, and continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator caused by an infinitely large volume change rate, thereby being conducive to improving the cycle stability of the lithium metal battery using this negative electrode sheet. Thus, the negative electrode sheet of the present invention can avoid lithium dendrite growth caused by uneven deposition of metallic lithium on the surface of the negative electrode, and solve problems such as continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator caused by the infinitely large volume change rate of metallic lithium, thereby being conducive to improving the cycle stability of the lithium metal battery.

[0008] In addition, the negative electrode sheet according to the above embodiment of the present invention may further have the following additional technical features:

[0009] In some embodiments of the present invention, the first current collector is a composite current collector.

[0010] 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.

[0011] In some embodiments of the present invention, the first current collector includes a first base film, a first conductive layer provided on one side of the first base film, and a second conductive layer provided on the other side opposite to the first base film.

[0012] 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. This can improve the conductivity of the first current collector.

[0013] In some embodiments of the present invention, the thicknesses of the first conductive layer and the second conductive layer are each independently 0.2 μm - 100 μm.

[0014] 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.

[0015] In some embodiments of the present invention, the thickness of the first base film is 1 μm - 300 μm.

[0016] In some embodiments of the present invention, a third active material layer is provided on the second side of the first current collector, and the third active material layer includes metallic lithium or a metallic lithium alloy.

[0017] 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.

[0018] In some embodiments of the present invention, the third active material layer includes metallic lithium, and 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.

[0019] In some embodiments of the present invention, 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. Thus, problems such as 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 cycling of the lithium metal battery can be solved.

[0020] In some embodiments of the present invention, the content of lithium element in the metallic lithium alloy is 2 atm% - 98 atm%. Thus, problems such as 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 cycling of the lithium metal battery can be solved.

[0021] 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 respectively.

[0022] In a second aspect of the present invention, the present invention provides a method for preparing a negative electrode plate. According to an embodiment of the present invention, the method includes:

[0023] providing a first current collector, the first current collector including opposite first and second sides;

[0024] forming a first active material layer on the first side of the first current collector, the first active material layer including metallic lithium;

[0025] forming a second active material layer on a side of the first active material layer away from the first current collector, the second active material layer including a metallic lithium alloy.

[0026] According to the method for preparing a negative electrode sheet of the above embodiment of the present invention, by providing a first current collector including opposite first and second sides, forming a first active material layer on the first side of the first current collector, and forming a second active material layer on the side away from the first current collector on the first active material layer, the first active material layer includes metallic lithium, which can serve 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 prevent the highly reactive metallic lithium in the first active material layer from directly contacting the electrolyte or electrolyte. On the other hand, during the charge and discharge process of the battery, alloying reaction occurs between the metallic lithium and the metallic lithium alloy in the second active material layer, effectively avoiding problems such as uneven deposition of metallic lithium causing lithium dendrite growth, continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator due to an infinitely large volume change rate, thereby being beneficial to improving the cycle stability of the lithium metal battery using this negative electrode sheet. Thus, the negative electrode sheet obtained by using the method for preparing a negative electrode sheet of the present invention can avoid lithium dendrite growth caused by uneven deposition of metallic lithium on the surface of the negative electrode, and solve problems such as continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator due to an infinitely large volume change rate of metallic lithium, thereby being beneficial to improving the cycle stability of the lithium metal battery.

[0027] In addition, the method for preparing a negative electrode sheet according to the above embodiment of the present invention may further have the following additional technical features:

[0028] In some embodiments of the present invention, the method for preparing the negative electrode sheet further includes: forming a third active material layer on the second side of the first current collector, and the third active material layer includes metallic lithium or a metallic lithium alloy.

[0029] In some embodiments of the present invention, the third active material layer includes metallic lithium, and the method for preparing the negative electrode sheet further includes: forming a fourth active material layer on the side away from the first current collector of the third active material layer, and the fourth active material layer includes a metallic lithium alloy. Thereby, the cycle stability of the lithium metal battery can be improved.

[0030] In the third aspect of the present invention, the present invention provides a bipolar electrode sheet. According to an embodiment of the present invention, the bipolar electrode sheet includes:

[0031] A second current collector, the second current collector including opposite first and second sides;

[0032] A fifth active material layer and a sixth active material layer, the second current collector includes opposite first and second sides, the fifth active material layer is disposed on the first side of the second current collector, the sixth active material layer is disposed 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.

[0033] According to the bipolar electrode of the above embodiment of the present invention, by providing a second current collector including opposite first and second sides, 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 lithium metal alloy, which can cause an alloying reaction between metallic lithium and the lithium metal alloy in the fifth active material layer during the charge and discharge process of the battery, effectively avoiding problems such as the growth of lithium dendrites caused by uneven deposition of metallic lithium, and the continuous thickening of the SEI film, dead lithium, and the piercing of the separator by lithium dendrites due to an infinitely large volume change rate. Therefore, it is beneficial to improve the cycle stability of the battery using this bipolar electrode. The sixth active material layer includes a positive electrode active material, and a bipolar electrode can be obtained. Thus, the bipolar electrode of the present invention can avoid the growth of lithium dendrites caused by uneven deposition of metallic lithium on the surface of the negative electrode, and solve problems such as the continuous thickening of the SEI film, dead lithium, and the piercing of the separator by lithium dendrites due to an infinitely large volume change rate of metallic lithium, thereby being beneficial to improving the cycle stability of the battery.

[0034] In addition, the bipolar electrode according to the above embodiment of the present invention may further have the following additional technical features:

[0035] In some embodiments of the present invention, a seventh active material layer including metallic lithium is provided on the first side of the second current collector, and the fifth active material layer is provided on the side of the seventh active material layer away from the second current collector.

[0036] In some embodiments of the present invention, the second current collector is a composite current collector.

[0037] In some embodiments of the present invention, the second current collector is a metal foil current collector, 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.

[0038] In some embodiments of the present invention, the second current collector includes a second base film, a third conductive layer provided on one side of the second base film, and a fourth conductive layer provided on the opposite side of the second base film, the fifth active material layer is provided on the third conductive layer, and the sixth active material layer is provided on the fourth conductive layer.

[0039] In some embodiments of the present invention, the second current collector includes a second base film, a third conductive layer provided on one side of the second base film, and a fourth conductive layer provided on the opposite side of the second base film, the seventh active material layer is provided on the third conductive layer, and the sixth active material layer is provided on the fourth conductive layer.

[0040] In some embodiments of the present invention, the third conductive layer comprises at least one of copper, aluminum, nickel, and chromium, preferably copper. Thereby, the conductivity of the second current collector can be improved.

[0041] In some embodiments of the present invention, the fourth conductive layer comprises at least one of copper, aluminum, nickel, and chromium, preferably aluminum. Thereby, the conductivity of the second current collector can be improved.

[0042] In some embodiments of the present invention, the positive electrode active material comprises at least one of lithium nickel cobalt manganese oxide, lithium iron manganese phosphate, lithium iron phosphate, lithium manganate, lithium cobaltate, lithium nickelate, lithium-rich manganese-based positive electrode material, lithium nickel manganate, and lithium vanadium phosphate oxide.

[0043] In the fourth aspect of the present invention, the present invention provides a method for preparing a bipolar electrode. According to an embodiment of the present invention, the method comprises:

[0044] providing a second current collector, the second current collector comprising an opposite first side and a second side;

[0045] forming a fifth active material layer on the first side of the second current collector, the fifth active material layer comprising a lithium metal alloy;

[0046] forming a sixth active material layer on the second side of the second current collector, the sixth active material layer comprising a positive electrode active material.

[0047] According to the method for preparing a bipolar electrode of the above embodiments of the present invention, by providing a second current collector comprising an opposite first side and a second side, 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 comprising a lithium metal alloy, during the charge and discharge process of the battery, an alloying reaction can occur between the lithium metal and the lithium metal alloy in the fifth active material layer, effectively avoiding problems such as uneven deposition of lithium metal causing lithium dendrite growth, continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator due to an infinitely large volume change rate, thereby being beneficial to improving the cycle stability of the battery using the bipolar electrode. The sixth active material layer comprises a positive electrode active material, and a bipolar electrode can be obtained. Thus, the bipolar electrode obtained by using the method for preparing a bipolar electrode of the present invention can avoid lithium dendrite growth caused by uneven deposition of lithium metal on the surface of the negative electrode, and solve problems such as continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator due to an infinitely large volume change rate of lithium metal, thereby being beneficial to improving the cycle stability of the battery.

[0048] In addition, the method for preparing a bipolar electrode according to the above embodiments of the present invention may further have the following additional technical features:

[0049] In some embodiments of the present invention, the method for preparing the bipolar electrode further includes: before forming the fifth active material layer on the first side of the second current collector, forming a seventh active material layer on the second side of the second current collector in advance, and the seventh active material layer includes metallic lithium. Thus, the seventh active material layer can serve as a supplementary lithium source to improve the cycle life of the battery.

[0050] In a fifth aspect of the present invention, the present invention provides a battery. According to embodiments of the present invention, the battery includes the above-mentioned negative electrode or a negative electrode obtained by the method for preparing the negative electrode or the above-mentioned bipolar electrode or a bipolar electrode obtained by the method for preparing the bipolar electrode. Thus, the battery has high cycle stability.

[0051] In addition, the battery according to the above embodiments of the present invention may further have the following additional technical features:

[0052] In some embodiments of the present invention, the battery includes a liquid battery, a semi-solid battery, and a solid-state battery.

[0053] In some embodiments of the present invention, the battery includes a liquid battery and a semi-solid battery, the battery includes an electrolyte, and the electrolyte includes a lithium salt and a solvent.

[0054] In some embodiments of the present invention, the electrolyte further includes an additive.

[0055] 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 trifluoromethylsulfonyl-n-perfluorobutanesulfonylimide, lithium fluorosulfonyl-n-perfluorobutanesulfonylimide, lithium bis(oxalato)borate, and lithium tris(trifluoromethylsulfonyl)methyl.

[0056] 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.

[0057] 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 the content of water and HF, a low-temperature additive, and a negative electrode stabilizer.

[0058] In some embodiments of the present invention, the battery includes a semi-solid battery and a 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.

[0059] 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 Li 6 PS 5 F, Li 6 PS 5 Cl, Li 6 PS 5 Br, Li 6 PS 5 I, Li 2 S-SiS 2 , Li 2 S-P 2 S 5 , Li 2 S-GeS 2 , Li 2 S-SiS 2 -P 2 S 5 , Li 2 S-GeS 2 -P 2 S 5 , Li 2 S-SnS 2 -P 2 S 5 and Li 2 S-AlS 2 -P 2 S 5 at least one of; the halide solid electrolyte includes Li 2 MnCl 4 , Li 2 ZnCl 4 , LiYbF 4 , LiAlF 4 , Li 3 YCl 6 , Li 3 BrCl 6 and Li 6 CoCl 8 at least one of.

[0060] In some embodiments of the present invention, the polymer solid electrolyte includes a polymer matrix, an inorganic filler, and a lithium salt. The polymer matrix includes at least one of polyethylene oxide, polycarbonate, poly(trimethylene carbonate), polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, poly(vinylidene fluoride - hexafluoroethylene) copolymer, and lithium polyacrylate. The inorganic filler includes Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 , lithium lanthanum zirconium oxide, alumina, and at least one of metal - organic frameworks. The lithium salt includes LiAsF 6 , LiPF 6 , LiClO 4 , lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and at least one of lithium tetrafluoroborate.

[0061] In a sixth aspect of the present invention, a power - consuming device is proposed. According to an embodiment of the present invention, the power - consuming device includes the above - mentioned battery. The power - consuming device has the same advantages as the above - mentioned battery compared with the prior art, which will not be elaborated here.

[0062] The additional aspects and advantages of the present invention will be partly given in the following description, partly will become apparent from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The above - mentioned and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0064] Figure 1 is a schematic structural diagram of a negative electrode sheet according to an embodiment of the present invention;

[0065] Figure 2 is a schematic structural diagram of a first current collector according to an embodiment of the present invention;

[0066] Figure 3 is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present invention;

[0067] Figure 4 is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present invention;

[0068] Figure 5 is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present invention;

[0069] Figure 6 is a schematic process flow diagram of a method for preparing a negative electrode sheet according to an embodiment of the present invention;

[0070] Figure 7 It is a schematic structural diagram of a bipolar pole piece according to an embodiment of the present invention;

[0071] Figure 8 It is a schematic structural diagram of a second current collector according to an embodiment of the present invention;

[0072] Figure 9 It is a schematic structural diagram of a bipolar pole piece according to another embodiment of the present invention;

[0073] Figure 10 It is a schematic structural diagram of a bipolar pole piece according to yet another embodiment of the present invention;

[0074] Figure 11 It is a schematic process flow diagram of a method for preparing a bipolar pole piece according to an embodiment of the present invention.

[0075] Reference numerals:

[0076] 100 - negative electrode pole piece; 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 pole piece; 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 of the Embodiment

[0077] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0078] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationship 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 thus should not be construed as limiting the present invention.

[0079] 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 quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0080] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0081] In the first aspect of the present invention, the present invention provides a negative electrode plate. According to an embodiment of the present invention, with reference to Figure 1 , the negative electrode plate 100 includes a first current collector 10, a first active material layer 20 and a second active material layer 30.

[0082] According to an embodiment of the present invention, the first current collector 10 includes opposite first and second sides. 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 according to actual needs. For example, the first current collector 10 can be a metal foil current collector or a composite current collector.

[0083] 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.

[0084] According to a specific embodiment of the present invention, with reference to Figure 2 , the first current collector 10 is a composite current collector, and the first current collector 10 may include a first base film 11, a first conductive layer 12 and a second conductive layer 13.

[0085] According to a specific embodiment of the present invention, the material of the first base film 11 is a polymer. The material of the first base film 11 being a polymer has a lower density compared to metal current collectors such as copper foil. Thus, the first current collector 10 prepared therefrom also has a lower density compared to metal current collectors such as copper foil, which can improve the energy density of the battery.

[0086] 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 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 a flame retardant effect, thereby reducing the fire problem caused by the short circuit of lithium dendrite piercing the thin film.

[0087] According to a specific embodiment of the present invention, the thickness of the first base film 11 can be 1 μm - 300 μm, for example, it can be 1 μm, 5 μm, 10 μm, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, etc.

[0088] According to a specific embodiment of the present invention, referring to Figure 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.

[0089] It should be noted that the material of the first conductive layer 12 is not particularly limited, and those skilled in the art can select according to actual needs as long as it has excellent conductivity and good mechanical properties. For example, it may include at least one of copper, aluminum, nickel, and chromium. Specifically, the thickness of the first conductive layer 12 can be 0.2 μm - 100 μm, for example, it can be 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.

[0090] According to a specific embodiment of the present invention, referring to Figure 2 , the second conductive layer 13 is disposed on the opposite side of the first base film 11. By disposing the second conductive layer 13 on the opposite side of the first base film 11, the conductivity of the first current collector 10 can be further improved.

[0091] It should be noted that the material of the second conductive layer 13 is not particularly limited, and 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 0.2 μm - 100 μm, such as 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.

[0092] According to specific embodiments of the present invention, the first conductive layer 12 and the second conductive layer 13 can be separately and independently prepared by physical vapor deposition (PVD), chemical vapor deposition (CVD), or electroplating with water. For example, when using aluminum 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 using copper 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. Among them, the one-step method includes a one-step chemical deposition method, a one-step vacuum magnetron sputtering method, and a one-step vacuum evaporation method. The one-step chemical deposition method deposits a copper layer through a chemical reaction, the one-step vacuum magnetron sputtering method deposits a copper layer through repeated magnetron sputtering, and the one-step vacuum evaporation method deposits a copper layer through repeated evaporation; the two-step method first uses magnetron sputtering for underlaying and then uses electroplating with water to thicken the copper layer; the three-step method first uses magnetron sputtering for underlaying, then uses vacuum evaporation, and finally uses electroplating with water to thicken the copper layer.

[0093] Thus, by using the first current collector 10 in the negative electrode sheet 100 of the present invention, on the one hand, the mechanical strength and mechanical properties of the negative electrode sheet 100 can be improved. On the other hand, compared with metal current collectors such as copper foils, 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 foils (weight reduction of more than 60%), which can improve the energy density of the battery.

[0094] According to an embodiment of the present invention, refer to Figure 1, 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 inventor found that by sequentially arranging 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 includes metallic lithium and can serve as a supplementary lithium source to improve the cycle life of the battery. The second active material layer 30 includes a metallic lithium alloy. On the one hand, it can prevent the highly reactive metallic lithium in the first active material layer 20 from directly contacting the electrolyte or the electrolyte. On the other hand, during the charge and discharge process of the battery, alloying reaction occurs between the metallic lithium and the metallic lithium alloy in the second active material layer 30, effectively avoiding problems such as uneven deposition of metallic lithium causing lithium dendrite growth, continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator due to an infinitely large volume change rate, thereby being beneficial to improving the cycle stability of the lithium metal battery applying the negative electrode sheet 100.

[0095] The inventor 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 directly contact the electrolyte or the electrolyte, resulting in lithium dendrite growth.

[0096] According to a specific embodiment of the present invention, referring to Figure 3 , the first active material layer 20 can be arranged on the first conductive layer 12.

[0097] It should be noted that the thicknesses of the first active material layer 20 and the second active material layer 30 are not particularly limited, and those skilled in the art can select according to actual needs. As a preferred solution, the thicknesses of the first active material layer 20 and the second active material layer 30 can be independently 0.1 μm - 100 μm respectively, for example, they can be 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.

[0098] According to a specific embodiment of the present invention, the specific composition of the metallic lithium alloy is not particularly limited, and those skilled in the art can select according to actual needs. For example, it can include 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, etc. Specifically, the content of lithium element in the above metallic lithium alloy can be 2 atm% - 98 atm%, for example, it can be 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.

[0099] According to an embodiment of the present invention, with reference to Figure 4 , a third active material layer 40 is provided on the second side of the first current collector 10. 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 serve 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, during the charge and discharge process of the battery, an alloying reaction can occur between the metallic lithium and the metallic lithium alloy in the third active material layer 40, further avoiding problems such as uneven deposition of metallic lithium causing lithium dendrite growth, continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator due to an infinitely large volume change rate, thereby further facilitating the improvement of the cycle stability of the lithium metal battery using the negative electrode sheet 100. Specifically, the third active material layer 40 can be provided on the second conductive layer 13.

[0100] It should be noted that the thickness of the third active material layer 40 is not particularly limited, and those skilled in the art can select it according to actual needs. As a preferred solution, the thickness of the third active material layer 40 can be 0.1 μm - 100 μm, for example, it can be 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.

[0101] According to a specific embodiment of the present invention, with reference to Figure 5 , 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 the fourth active material layer 50 includes a metallic lithium alloy, on the one hand, it can prevent the highly reactive metallic lithium in the third active material layer 40 from directly contacting the electrolyte / electrolyte, and on the other hand, during the charge and discharge process of the battery, an alloying reaction can occur between the metallic lithium and the metallic lithium alloy in the fourth active material layer 50, further avoiding problems such as uneven deposition of metallic lithium causing lithium dendrite growth, continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator due to an infinitely large volume change rate, thereby facilitating the improvement of the cycle stability of the lithium metal battery using the negative electrode sheet 100.

[0102] It should be noted that the thickness of the fourth active material layer 50 is not particularly limited, and those skilled in the art can select it according to actual needs. As a preferred solution, the thickness of the fourth active material layer 50 can be 0.1 μm - 100 μm, for example, it can be 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.

[0103] According to specific embodiments 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 separately and independently prepared by roll pressing (i.e., roll pressing a metal strip serving as the active material layer onto the surface of the current collector or other active material layers) or physical vapor deposition (PVD, such as magnetron sputtering, vacuum evaporation, etc.). The physical vapor deposition method is preferred. Thus, it is beneficial to reduce the thickness of the active material layer, achieve uniform deposition, thereby reducing the amount of active material used and lowering the battery cost. Specifically, the lithium metal alloy (Li-M) can form an active material layer including the lithium metal alloy by magnetron sputtering metal M onto the surface of the lithium metal layer. The vacuum evaporation method can also be used, that is, lithium metal and metal M in the shape of strips, blocks, etc. are respectively placed in a container (such as an evaporation boat, crucible, etc.). Considering the melting points of lithium metal 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 adopted to control the composition and deposition rate of the lithium metal alloy on the premise of setting a reasonable evaporation chamber pressure and substrate temperature.

[0104] Thus, the negative electrode sheet 100 of the present invention can avoid the growth of lithium dendrites caused by uneven deposition of metallic lithium on the negative electrode surface, solve problems such as the continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator brought about by the infinitely large volume change rate of metallic lithium, thereby being beneficial to improving the cycle stability of the lithium metal battery using the negative electrode sheet 100.

[0105] In the second aspect of the present invention, the present invention proposes a method for preparing a negative electrode sheet. According to an embodiment of the present invention, referring to Figure 6 , the method includes:

[0106] S100: Provide a first current collector, the first current collector including an opposite first side and a second side

[0107] In this step, a first current collector 10 is provided, and the first current collector 10 includes opposite first and second sides. It should be noted that the specific method for preparing the first current collector 10 is not particularly limited. For example, it may include: forming a first conductive layer 12 on one side of the first base film 11; forming a second conductive layer 13 on the side of the first base film 11 away from the first conductive layer 12. By forming 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. At the same time, by forming the second conductive layer 13 on the opposite side of the first base film 11, the conductivity of the first current collector 10 can be further improved.

[0108] S200: Form a first active material layer on the first side of the first current collector, and the first active material layer includes metallic lithium

[0109] In this step, a first active material layer 20 is formed on the first side of the first current collector 10, and the first active material layer 20 includes metallic lithium. The inventor found that by forming the first active material layer 20 including metallic lithium on the first side of the first current collector 10, it can serve as a supplementary lithium source to improve the cycle life of the battery.

[0110] S300: Form a second active material layer on the side of the first active material layer away from the first current collector, and the second active material layer includes a metallic lithium alloy

[0111] In this step, a second active material layer 30 is formed on the side of the first active material layer 20 away from the first current collector 10, and the second active material layer 30 includes a metallic lithium alloy. The inventor found that by forming the second active material layer 30 including a metallic lithium alloy on the side of the first active material layer 20 away from the first current collector 10, on the one hand, it can prevent the highly reactive metallic lithium in the first active material layer 20 from directly contacting the electrolyte or the electrolyte. On the other hand, during the charge and discharge process of the battery, alloying reaction can occur between the metallic lithium and the metallic lithium alloy in the second active material layer 30, effectively avoiding problems such as uneven deposition of metallic lithium causing lithium dendrite growth, and continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator due to an infinitely large volume change rate, thereby being beneficial to improving the cycle stability of the lithium metal battery using this negative electrode sheet. Specifically, the above-mentioned first active material layer 20 can be formed on the first conductive layer 12.

[0112] Regarding 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 elaborated here.

[0113] According to an embodiment of the present invention, the method for preparing the negative electrode sheet 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 serve 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, during the charge and discharge process of the battery, an alloying reaction can occur between the metallic lithium and the metallic lithium alloy in the third active material layer 40, further avoiding problems such as uneven deposition of metallic lithium causing lithium dendrite growth, continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator due to an infinitely large volume change rate, thereby further facilitating the improvement of the cycle stability of the lithium metal battery using the negative electrode sheet 100. Specifically, the third active material layer 40 can be formed on the second conductive layer 13.

[0114] According to a specific embodiment of the present invention, if the third active material layer 40 includes metallic lithium, the method for preparing the negative electrode sheet further includes: forming a fourth active material layer 50 on the side of the third active material layer 40 away from the first current collector 10, and the fourth active material layer 50 includes a metallic lithium alloy. By forming a fourth active material layer 50 including a metallic lithium alloy on the side of the third active material layer 40 away from the first current collector 10, on the one hand, it can prevent the highly reactive metallic lithium in the third active material layer 40 from directly contacting the electrolyte / electrolyte, and on the other hand, during the charge and discharge process of the battery, an alloying reaction can occur between the metallic lithium and the metallic lithium alloy in the fourth active material layer 50, further avoiding problems such as uneven deposition of metallic lithium causing lithium dendrite growth, continuous thickening of the SEI film, dead lithium, and lithium dendrites piercing the separator due to an infinitely large volume change rate, thereby facilitating the improvement of the cycle stability of the lithium metal battery.

[0115] It should be noted that the preparation methods and thicknesses of the third active material layer 40 and the fourth active material layer 50 have been described in detail above and will not be elaborated here.

[0116] Thus, the negative electrode sheet obtained by using the method for preparing the negative electrode sheet of the present invention can avoid lithium dendrite growth caused by uneven deposition of metallic lithium on the surface of the negative electrode, and solve problems such as continuous thickening of the SEI film, continuous growth of lithium dendrites, dead lithium, and lithium dendrites piercing the separator due to an infinitely large volume change rate of metallic lithium, thereby facilitating the improvement of the cycle stability of the lithium metal battery using the negative electrode sheet obtained by this method.

[0117] In the third aspect of the present invention, the present invention proposes a bipolar electrode sheet. According to an embodiment of the present invention, referring to Figure 7 , the bipolar electrode sheet 200 includes a second current collector 210, a fifth active material layer 220, and a sixth active material layer 230.

[0118] According to an embodiment of the present invention, the second current collector 200 includes opposite first and second sides. It should be noted that the specific type of the second current collector 210 is not particularly limited, and those skilled in the art can select according to actual needs. For example, the second current collector 210 can be a metal foil current collector or a composite current collector.

[0119] According to an embodiment of the present invention, the second current collector 210 is a metal foil current collector, and the metal foil current collector may include a stainless steel alloy foil, and the stainless steel alloy foil may include at least one of nickel, chromium, and copper.

[0120] According to an embodiment of the present invention, referring to Figure 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.

[0121] According to a specific embodiment of the present invention, the material of the second base film 211 is a polymer. The material of the second base film 211 is a polymer, which has a lower density than the metal current collector. Therefore, the second current collector 210 prepared therefrom also has a lower density than the metal current collector, and the energy density of the battery can be improved.

[0122] It should be noted that the specific material of the above-mentioned second base film 211 is not particularly limited, and those skilled in the art can select 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 above-mentioned second base film 211 includes at least one of polyethylene terephthalate (PET), polypropylene (PP), and polyimide (PI); alternatively, the above-mentioned second base film 211 includes polyimide and / or polyphenylene sulfide, and polyimide and polyphenylene sulfide have a flame retardant effect, thereby reducing the fire problem caused by the lithium dendrite piercing the thin film short circuit.

[0123] According to a specific embodiment of the present invention, the thickness of the above-mentioned second base film 211 can be 1 μm - 300 μm, for example, it can be 1 μm, 5 μm, 10 μm, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, etc.

[0124] According to a specific embodiment of the present invention, referring to Figure 8 , the third conductive layer 212 is provided on one side of the second base film 211. By providing 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.

[0125] It should be noted that the material of the third conductive layer 212 is not particularly limited, and 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, and copper is preferred. Specifically, the thickness of the third conductive layer 212 can be 0.2 μm - 100 μm, such as 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.

[0126] According to a specific embodiment of the present invention, referring to Figure 8 , the fourth conductive layer 213 is provided on the opposite side of the second base film 211. By providing the fourth conductive layer 213 on the opposite side of the second base film 211, the conductivity of the second current collector 210 can be improved.

[0127] It should be noted that the material of the fourth conductive layer 213 is not particularly limited, and 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, and aluminum is preferred. Specifically, the thickness of the fourth conductive layer 213 can be 0.2 μm - 100 μm, such as 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.

[0128] According to a specific embodiment of the present invention, the third conductive layer 212 and the fourth conductive layer 213 can be separately and independently prepared by physical vapor deposition (PVD), chemical vapor deposition (CVD), or electroplating with water. For example, when using copper as the third conductive layer 212, it can be prepared on the second base film 211 by a one-step method, a two-step method, or a three-step method. The specific steps of the one-step method, two-step method, and three-step method have been described in detail above and will not be repeated here; when using aluminum as the fourth conductive layer 213, aluminum can be directly plated on the second base film 211 by vapor evaporation.

[0129] Thus, by using the second current collector 210 in the bipolar electrode 200 of the present invention, on the one hand, the mechanical strength and mechanical properties of the bipolar electrode 200 can be improved. On the other hand, compared with a 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.

[0130] According to a specific embodiment of the present invention, referring to Figure 9, the fifth active material layer 220 is disposed on the first side of the second current collector 210, and the fifth active material layer 220 includes a lithium metal alloy. The inventor found that by disposing the fifth active material layer 220 including a lithium metal alloy on the first side of the second current collector 210, an alloying reaction can occur between the lithium metal and the lithium metal alloy in the fifth active material layer 220 during the charge and discharge process of the battery, which can effectively avoid problems such as uneven deposition of lithium metal causing lithium dendrite growth, continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator due to an infinitely large volume change rate, thereby being beneficial to improving the cycle stability of the battery using this bipolar electrode. Specifically, the above-mentioned fifth active material layer 220 can be disposed on the third conductive layer 212.

[0131] According to a specific embodiment of the present invention, the fifth active material layer 220 can be prepared by a method of rolling or physical vapor deposition. Specifically, the thickness of the fifth active material layer 220 can be 0.1 μm - 100 μm, for example, it can be 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.

[0132] It should be noted that the specific composition and preparation method of the lithium metal alloy have been described in detail above and will not be repeated here.

[0133] According to a specific embodiment of the present invention, refer to Figure 9 , the sixth active material layer 230 is disposed on the second side of the second current collector 210, and 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 can be obtained. Specifically, the sixth active material layer 230 can be disposed on the fourth conductive layer 213.

[0134] According to a specific embodiment of the present invention, the sixth active material layer 230 can be prepared by a method of wet coating or dry coating, and the thickness can be 0.1 μm - 100 μm, for example, it can be 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.

[0135] 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 according to actual needs. For example, it can include lithium nickel cobalt manganese oxide (LiN x M y C z O 2 , x + y + z = 1), lithium iron manganese phosphate (LiFe a Mn b PO4 , a + b = 1), lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium-rich manganese-based cathode material, lithium nickel manganese oxide (LMNO), lithium vanadium phosphate (Li 3 V 2 (PO 4 ) 3 , LiVOPO 4 ), etc.

[0136] According to an embodiment of the present invention, referring to Figure 10 , a seventh active material layer 240 is provided on the first side of the second current collector 210. The seventh active material layer 240 includes metallic lithium. The fifth active material layer 220 is provided on the side of the seventh active material layer 240 away from the second current collector 210. Compared with the theoretical specific capacity of the graphite negative electrode of 372 mAh / g, metallic lithium has an ultra-high theoretical specific capacity of 3860 mAh / g and the most negative standard reduction potential (-3.04 V), and also has the characteristics of low density and small ionic radius. By providing the seventh active material layer 240 including metallic lithium on the first side of the second current collector 210, it can be used as a supplementary lithium source to improve the cycle life of the battery. The fifth active material layer 220 including a metallic lithium alloy is provided on the side of the seventh active material layer 240 away from the second current collector 210. On the one hand, it can prevent the highly reactive metallic lithium in the seventh active material layer 240 from directly contacting the electrolyte / electrolyte. On the other hand, during the charge and discharge process of the battery, alloying reaction can occur between the metallic lithium and the metallic lithium alloy in the fifth active material layer 220, effectively avoiding problems such as uneven deposition of metallic lithium causing lithium dendrite growth, and continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator due to an infinitely large volume change rate, thereby being beneficial to improving the cycle stability of the battery applying the bipolar electrode 200. Specifically, the seventh active material layer 240 can be provided on the third conductive layer 212.

[0137] According to a specific embodiment of the present invention, the seventh active material layer 240 can be prepared by a method of rolling or physical vapor deposition, and the thickness can be 0.1 μm - 100 μm, for example, it can be 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.

[0138] Thus, the bipolar electrode 200 of the present invention can avoid lithium dendrite growth caused by uneven deposition of metallic lithium on the surface of the negative electrode, and solve problems such as continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator due to an infinitely large volume change rate of metallic lithium, thereby being beneficial to improving the cycle stability of the battery applying the bipolar electrode 200.

[0139] In the fourth aspect of the present invention, referring to Figure 11, the present invention provides a method for preparing a bipolar electrode. According to an embodiment of the present invention, the method includes:

[0140] S1000: Provide a second current collector, the second current collector including opposite first and second sides

[0141] In this step, a second current collector 210 is provided, and the second current collector 210 includes opposite first and second sides. It should be noted that the specific method for preparing the second current collector 210 is not particularly limited. For example, it may include: forming a third conductive layer 212 on one side of the second base film 211; forming a fourth conductive layer 213 on the side of the second base film 211 away from the third conductive layer 212. By forming 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. At the same time, by forming the fourth conductive layer 213 on the side of the second base film 211 away from the third conductive layer 212, the conductivity of the second current collector 210 can be improved.

[0142] S2000: Form a fifth active material layer on the first side of the second current collector, the fifth active material layer including a lithium metal alloy

[0143] In this step, a fifth active material layer 220 is formed on the first side of the second current collector 210, and the fifth active material layer 220 includes a lithium metal alloy. The inventors found that by forming the fifth active material layer 220 including a lithium metal alloy on the first side of the second current collector 210, an alloying reaction can occur between the lithium metal and the lithium metal alloy in the fifth active material layer 220 during the charge and discharge process of the battery. Thus, problems such as uneven deposition of lithium metal causing lithium dendrite growth, continuous thickening of the SEI film, dead lithium, and lithium dendrite piercing the separator due to an infinitely large volume change rate can be effectively avoided, which is beneficial to improving the cycle stability of the battery using this bipolar electrode. Specifically, the above-mentioned fifth active material layer 220 can be formed on the third conductive layer 212.

[0144] S3000: Form 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

[0145] In this step, a sixth active material layer 230 is formed on the second side of the second current collector 210, and the sixth active material layer includes a positive electrode active material. 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 can be obtained.

[0146] 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 elaborated here.

[0147] According to an embodiment of the present invention, the method for preparing the bipolar electrode 200 further includes: before forming the fifth active material layer 220 on the first side of the second current collector 210, a seventh active material layer 240 including metallic lithium is formed on the first side of the second current collector 210 in advance. Compared with the theoretical specific capacity of the graphite negative electrode of 372 mAh / g, metallic lithium has an ultra-high theoretical specific capacity of 3860 mAh / g and the most negative standard reduction potential (-3.04V), and also has the characteristics of low density and small ionic radius. By forming a seventh active material layer 240 including metallic lithium on the first side of the second current collector 210 in advance 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 including a 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 the continuous thickening of the SEI film, the continuous growth of lithium dendrites, dead lithium, and the piercing of the separator by lithium dendrites caused by the direct contact between the highly reactive metallic lithium in the seventh active material layer 240 and the electrolyte / electrolyte, thereby being beneficial to improving the cycle stability of the battery.

[0148] Therefore, the bipolar electrode obtained by using the method for preparing a bipolar electrode of the present invention can avoid the growth of lithium dendrites caused by the uneven deposition of metallic lithium on the surface of the negative electrode, and solve problems such as the continuous thickening of the SEI film, dead lithium, and the piercing of the separator by lithium dendrites caused by the infinitely large volume change rate of metallic lithium, thereby being beneficial to improving the cycle stability of the battery.

[0149] In the fifth aspect of the present invention, the present invention provides a battery. According to an embodiment of the present invention, the battery includes the above-mentioned negative electrode sheet or the negative electrode sheet obtained by using the method for preparing the negative electrode sheet or the above-mentioned bipolar electrode or the bipolar electrode obtained by using the method for preparing the bipolar electrode. Therefore, the battery has high cycle stability. It should be noted that the features and advantages described above for the negative electrode sheet or the bipolar electrode also apply to this battery and will not be elaborated here.

[0150] According to an embodiment of the present invention, the above-mentioned battery may include a liquid battery, a semi-solid battery, and a solid-state battery.

[0151] 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 method for preparing the negative electrode sheet described above, a positive electrode sheet, a separator, and an electrolyte to form a liquid laminated battery, a liquid wound battery, or a liquid cylindrical battery.

[0152] According to a specific embodiment of the present invention, the above-mentioned electrolyte mainly includes a lithium salt, a solvent, and optional additives. 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 (LiPF 6 )), lithium perchlorate (LiClO 4 ), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluoroarsenate (LiAsF 6 ), other organic lithium salts (such as lithium trifluoromethanesulfonate (LiCF 3 SO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium trifluoromethylsulfonyl-perfluorobutanesulfonylimide (LiTNFSI), lithium fluorosulfonyl-perfluorobutanesulfonylimide (LiFNFSI), lithium bis(oxalato)borate (LiBOB), lithium tris(trifluoromethylsulfonyl)methyl (LiC(SO 2 CF 3 )) 3 ), etc.); the additives may include film-forming additives, conductive additives, flame retardant additives, overcharge protection additives, additives for controlling the content of water and HF (i.e., additives for controlling the content of water and HF 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 lithium metal negative electrode (such as fluoroethylene carbonate (FEC), lithium nitrate (LiNO 3 ), etc.).

[0153] According to a specific embodiment of the present invention, the battery may also include the above-mentioned negative electrode sheet or a negative electrode sheet obtained by the method for preparing the negative electrode sheet described above, a positive electrode sheet, and a gel electrolyte to form a semi-solid laminated battery, a semi-solid wound battery, or a semi-solid cylindrical battery.

[0154] According to a specific embodiment of the present invention, the battery may further include the above-mentioned negative electrode sheet or a negative electrode sheet obtained by the method for preparing the negative electrode sheet, a positive electrode sheet, a gel electrolyte, and optionally an additive of 0.5 wt% - 50 wt%, to form a semi-solid laminated battery, a semi-solid wound battery, or a semi-solid cylindrical battery.

[0155] According to a specific embodiment of the present invention, the battery may further include the above-mentioned negative electrode sheet or a negative electrode sheet obtained by the method for preparing the negative electrode sheet, a positive electrode sheet, and a solid electrolyte to form a solid laminated battery, a solid wound battery, or a solid cylindrical battery.

[0156] According to a specific embodiment of the present invention, the battery may include the above-mentioned bipolar electrode sheet or a bipolar electrode sheet obtained by the method for preparing the bipolar electrode sheet, a separator, and an electrolyte solution to form a liquid laminated battery, a liquid wound battery, or a liquid cylindrical battery.

[0157] According to a specific embodiment of the present invention, the battery may further include the above-mentioned bipolar electrode sheet or a bipolar electrode sheet obtained by the method for preparing the bipolar electrode sheet and a gel electrolyte to form a semi-solid laminated battery, a semi-solid wound battery, or a semi-solid cylindrical battery.

[0158] According to a specific embodiment of the present invention, the battery may further include the above-mentioned bipolar electrode sheet or a bipolar electrode sheet obtained by the method for preparing the bipolar electrode sheet, a gel electrolyte, and optionally an additive of 0.5 wt% - 50 wt% to form a semi-solid laminated battery, a semi-solid wound battery, or a semi-solid cylindrical battery.

[0159] According to a specific embodiment of the present invention, the battery may further include the above-mentioned bipolar electrode sheet or a bipolar electrode sheet obtained by the method for preparing the bipolar electrode sheet and a solid electrolyte to form a solid laminated battery, a solid wound battery, or a solid cylindrical battery.

[0160] According to a specific embodiment of the present invention, the specific types of the above-mentioned positive electrode sheet 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 sheet may be a positive electrode sheet using a metal foil current collector or a positive electrode sheet using a current collector, and its positive electrode active material may include lithium nickel cobalt manganate (LiN x M y C z O 2 , x + y + z = 1), lithium iron manganese phosphate (LiFe a Mn b PO 4 , a + b = 1), lithium iron phosphate, lithium manganate, lithium cobaltate, lithium nickelate, lithium-rich manganese-based positive electrode material, lithium manganese nickel oxide (LMNO), and lithium vanadium phosphate oxide (Li 3 V2 (PO 4 ) 3 , LiVOPO 4 ) or at least one of them.

[0161] According to a specific embodiment of the present invention, the separator may include polypropylene (PP) and / or polyethylene (PE).

[0162] According to a specific embodiment of the present invention, the solid electrolyte may include inorganic solid electrolytes (such as oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes), polymer solid electrolytes, and composite solid electrolytes (such as composite solid electrolytes based on polymer matrices and inorganic fillers), etc. Specifically, the oxide solid electrolyte may include NASICON type (stable structure, such as LATP (Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 ), LAGP (Li 1.5 Al 0.5 Ge 1.5 P 3 O 12 ), perovskite type, garnet type (highest conductivity, 10 -3 S / cm, relatively stable to metallic lithium, such as lithium lanthanum zirconium oxide (LLZO)); the sulfide solid electrolyte may include binary compounds (such as Li 2 S - SiS 2 and Li 2 S - P 2 S 5 , Li 2 S - GeS 2 etc.), ternary compounds (such as Li 2 S - MS 2 - P 2 S 5 (M = Si, Ge, Sn, Al, etc.), and Li 6 PS 5 X (X = F, Cl, Br, I) type; the halide solid electrolyte may include Li a MX 4 type (X represents a halogen element, such as Li 2 MnCl 4 , Li 2 ZnCl 4 etc., and halide electrolytes formed by trivalent and other valence metal ions M, such as LiYbF 4 , LiAlF 4 ), Li a MX6 Classes (such as Li 3 YCl 6 (LYC) and Li 3 BrCl 6 (LYB)) and Li a MX 8 Classes (such as Li 6 CoCl 8 ). The polymer solid electrolyte may include polymer matrices such as polyethylene oxide (PEO), polycarbonate, poly(trimethylene carbonate) (PTMC), poly(methyl methacrylate) (PMMA), polyacrylonitrile (PAN), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride - hexafluoroethylene) copolymer, lithium polyacrylate (PAL), etc., inorganic fillers such as LATP, lithium lanthanum zirconium oxide (LLZO), aluminum oxide (Al 2 O 3 ), metal - organic frameworks (MOFs), etc., and lithium salts such as LiAsF 6 , lithium hexafluorophosphate (LiPF 6 ), lithium perchlorate (LiClO 4 ), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF 4 ). Specifically, the gel electrolyte may include at least one of the above - mentioned solid electrolytes and at least one of the above - mentioned electrolytes.

[0163] In a sixth aspect of the present invention, the present invention provides an electrical device. According to an embodiment of the present invention, the electrical device includes the above - mentioned battery. The electrical device has the same advantages as the above - mentioned battery compared with the prior art, and will not be elaborated herein.

[0164] The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0165] Example 1

[0166] A negative electrode plate, referring to Figure 1 and Figure 2 , includes a first current collector 10, a first active material layer 20, and a second active material layer 30;

[0167] 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 disposed on the surface of one side of the first base film 11, and the second conductive layer 13 is disposed on the surface of the opposite side of the first base film 11. The material of the first base film 11 is polypropylene with a thickness of 1 μm, the material of the first conductive layer 12 is copper with a thickness of 0.2 μm, and the material of the second conductive layer 13 is copper with a thickness of 0.2 μm;

[0168] The first current collector 10 includes opposite first and second sides. The first active material layer 20 and the second active material layer 30 are sequentially disposed 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 100 μm, and the material of the second active material layer 30 is a metallic lithium alloy with 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 element content is 2 atm%.

[0169] Example 2

[0170] A negative electrode tab, referring to Figure 1 and Figure 2 , includes a first current collector 10, a first active material layer 20, and a second active material layer 30;

[0171] 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 disposed on the surface of one side of the first base film 11, and the second conductive layer 13 is disposed on the surface of the opposite side of the first base film 11. The material of the first base film 11 is polypropylene with a thickness of 300 μm, the material of the first conductive layer 12 is copper with a thickness of 100 μm, and the material of the second conductive layer 13 is copper with a thickness of 100 μm;

[0172] The first current collector 10 includes opposite first and second sides. The first active material layer 20 and the second active material layer 30 are sequentially disposed 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 a 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 element content is 98 atm%.

[0173] Example 3

[0174] A negative electrode tab, 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 with a thickness of 0.1 μm. The third active material layer 40 is disposed on the second side of the first current collector 10, and the rest are the same as in Example 1.

[0175] Example 4

[0176] A negative electrode tab, referring to Figure 4, including 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, with a thickness of 100 μm. The third active material layer 40 is disposed on the second side of the first current collector 10, and the rest are the same as in Example 1.

[0177] Example 5

[0178] A negative electrode tab, referring to Figure 4 , including 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 a metallic lithium alloy, and the rest are the same as in Example 3.

[0179] Example 6

[0180] A negative electrode tab, referring to Figure 4 , including 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 a metallic lithium alloy, with a thickness of 100 μm, and the rest are the same as in Example 3.

[0181] Example 7

[0182] A negative electrode tab, referring to Figure 5 , including 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 material of the fourth active material layer 50 is a metallic lithium alloy, with a thickness of 0.1 μm. The fourth active material layer 50 is disposed on the side of the third active material layer 40 including metallic lithium away from the first current collector 10, and the rest are the same as in Example 3.

[0183] Example 8

[0184] A negative electrode tab, referring to Figure 5 , including 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 material of the fourth active material layer 50 is a metallic lithium alloy, with a thickness of 100 μm. The fourth active material layer 50 is disposed on the side of the third active material layer 40 including metallic lithium away from the first current collector 10, and the rest are the same as in Example 3.

[0185] Example 9

[0186] A bipolar tab, referring to Figure 7 and Figure 8 , including a second current collector 210, a fifth active material layer 220, and a sixth active material layer 230;

[0187] 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 disposed on the surface of one side of the second base film 211, and the fourth conductive layer 213 is disposed on the surface of the other opposite side of the second base film 211. The material of the second base film 211 is polypropylene with a thickness of 300 μm, the material of the third conductive layer 212 is copper with a thickness of 100 μm, and the material of the fourth conductive layer 213 is aluminum with a thickness of 100 μm;

[0188] The second current collector 210 includes an opposite first side and a second side. A fifth active material layer 220 is disposed on the first side of the second current collector 210 (i.e., on the side of the third conductive layer 212 away from the second base film 211), and a sixth active material layer 230 is disposed on the second side of the second current collector 210 (i.e., on 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 lithium metal alloy with a thickness of 1 μm. The lithium metal alloy in the fifth active material layer 220 is an alloy formed by lithium and magnesium, and the lithium element content is 2 atm%. The sixth active material layer 230 includes a cathode active material lithium nickel cobalt manganese oxide (LiN 0.8 M 0.1 C 0.1 O 2 ) with a thickness of 1 μm.

[0189] Example 10

[0190] A bipolar pole piece, referring to Figure 7 and Figure 8 , includes a second current collector 210, a fifth active material layer 220, and a sixth active material layer 230;

[0191] 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 disposed on the surface of one side of the second base film 211, and the fourth conductive layer 213 is disposed on the surface of the other opposite side of the second base film 211. The material of the second base film 211 is polypropylene with a thickness of 1 μm, the material of the third conductive layer 212 is copper with a thickness of 0.5 μm, and the material of the fourth conductive layer 213 is aluminum with a thickness of 0.5 μm;

[0192] The second current collector 210 includes opposite first and second sides. The fifth active material layer 220 is provided on the first side of the second current collector 210 (i.e., on the side of the third conductive layer 212 away from the second base film 211), and the sixth active material layer 230 is provided on the second side of the second current collector 210 (i.e., on 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 lithium metal alloy with a thickness of 100 μm. The lithium metal alloy in the fifth active material layer 220 is an alloy formed by lithium and magnesium, and the lithium element content is 98 atm%. The sixth active material layer 230 includes the positive electrode active material lithium nickel cobalt manganate (LiN 0.8 M 0.1 C 0.1 O 2 ), and the thickness is 100 μm.

[0193] Example 11

[0194] A bipolar electrode, 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 lithium metal with a thickness of 100 μm. The seventh active material layer 240 is provided on the first side of the second current collector 210, and the fifth active material layer 220 is provided on the surface of the seventh active material layer 240 on the side away from the second current collector 210. The rest are the same as in Example 9.

[0195] Example 12

[0196] A bipolar electrode, 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 lithium metal with a thickness of 1 μm. The seventh active material layer 240 is provided on the first side of the second current collector 210, and the fifth active material layer 220 is provided on the surface of the seventh active material layer 240 on the side away from the second current collector 210. The rest are the same as in Example 9.

[0197] The negative electrode sheets of Examples 1-8 and the bipolar electrode sheets of Examples 9-12 are respectively assembled into liquid batteries:

[0198] 1. Preparation of the positive electrode sheet

[0199] The positive electrode active material LiNi 0.7 Co 0.1 Mn 0.1 O 2, the conductive agent Super P and the binder polyvinylidene fluoride (PVDF) are made into a positive electrode paste in N-methylpyrrolidone (NMP). The solid content in the positive electrode paste is 50 wt%, and in the solid components, the mass ratio of LiNi 0.7 Co 0.1 Mn 0.1 O 2 , Super P, and PVDF is 8:1:1. The positive electrode paste is coated on the upper and lower surfaces of the current collector aluminum foil, dried at 85°C, cold-pressed, then trimmed, sliced, and slit. After that, it is dried in a vacuum at 85°C for 4 h to make the positive electrode plate.

[0200] 2. Preparation of the electrolyte

[0201] In a glove box under an argon atmosphere (H 2 O < 0.1 ppm, O 2 <0.1 ppm), the fully dried electrolyte salt LiPF 6 is dissolved in a mixed solvent (the mixed solvent includes ethylene carbonate (EC) and diethyl carbonate (DEC), and ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed in a mass ratio of 50:50). After mixing evenly, an electrolyte with a concentration of 1 mol / L is obtained.

[0202] 3. Separator

[0203] A 16-μm polyethylene film is used as the separator.

[0204] 4. Preparation of the lithium metal battery

[0205] The positive electrode plate, the separator, and the negative electrode plates of Examples 1-8 are stacked in sequence, with the separator placed in the middle of the positive and negative electrode plates to isolate the positive and negative electrodes. After winding, a bare battery core is obtained, the electrode tabs are welded, the bare battery core is placed in an outer package, and the above-prepared electrolyte is injected into the dried battery core. Then, processes such as encapsulation, standing, formation, shaping, and capacity testing are carried out to complete the preparation of the lithium metal battery.

[0206] The bipolar electrode plates of Examples 9-12 and the separator are stacked in sequence, wound to obtain a bare battery core, the electrode tabs are welded, the bare battery core is placed in an outer package, and the above-prepared electrolyte is injected into the dried battery core. Then, processes such as encapsulation, standing, formation, shaping, and capacity testing are carried out to complete the preparation of the lithium metal battery.

[0207] Characterize the cycle performance of the lithium metal batteries obtained from the negative electrode plates of Examples 1-8 and the bipolar electrode plates of Examples 9-12.

[0208] Cyclic performance test method for lithium metal batteries

[0209] The battery is charged at a constant current of 0.2C under the condition of 25°C ± 2°C. When the battery voltage reaches 4.2V, it is switched to constant voltage charging until the charging current drops to 0.05C and then the charging stops. After charging, it is left standing for 30 minutes and then discharged at a current of 0.3C until the voltage reaches 2.6V. After cycling 50 times according to the above charge-discharge process, the battery is disassembled, and the negative electrode plates of Examples 1-8 and the bipolar electrode plates of Examples 9-12 are tested by scanning electron microscope (SEM).

[0210] It can be seen from the obtained SEM images that the surfaces of the negative electrode plates of Examples 1-8 and the negative surfaces of the bipolar electrode plates of Examples 9-12 are uniform and relatively flat, and no obvious growth of lithium dendrites is observed.

[0211] It can be seen from Examples 1-12 that using the negative electrode plate or the 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 separator, which is beneficial to improving the cycle stability of the battery using the negative electrode plate or the bipolar electrode plate.

[0212] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection 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 a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0213] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A negative electrode plate, characterized in that, it includes: A first current collector, the first current collector includes opposite first and second sides; A first active material layer and a second active material layer, 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 plate according to claim 1, characterized in that, the first current collector is a composite current collector.

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

5. The negative electrode plate 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 plate according to claim 4 or 5, characterized in that, the thicknesses of the first conductive layer and the second conductive layer are each independently 0.2 μm - 100 μm.

7. The negative electrode plate 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 plate 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 plate according to claim 4, characterized in that, a third active material layer is provided on the second side of the first current collector, and the third active material layer includes metallic lithium or a metallic lithium alloy.

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

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

12. The negative electrode plate according to claim 1 or 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 plate according to claim 12, characterized in that, the content of lithium element in the metallic lithium alloy is 2 atm% - 98 atm%.

14. The negative electrode plate according to claim 11, characterized in that, 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 each independently 0.1 μm - 100 μm.

15. A method for preparing a negative electrode plate, characterized in that, comprising: providing a first current collector, the first current collector including opposite first and second sides; forming a first active material layer on the first side of the first current collector, the first active material layer including metallic lithium; forming a second active material layer on a side of the first active material layer away from the first current collector, the second active material layer including a metallic lithium alloy.

16. The method according to claim 15, characterized in that, further comprising: forming a third active material layer on the second side of the first current collector, the third active material layer including 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 comprises: forming a fourth active material layer on a side of the third active material layer away from the first current collector, the fourth active material layer including a metallic lithium alloy.

18. A bipolar plate, characterized in that, comprising: a second current collector, the second current collector including opposite first and second sides; a fifth active material layer and a sixth active material layer, the fifth active material layer being disposed on the first side of the second current collector, the sixth active material layer being disposed on the second side of the second current collector, the fifth active material layer including a metallic lithium alloy, and the sixth active material layer including a positive electrode active material.

19. The bipolar plate according to claim 18, characterized in that, a seventh active material layer including metallic lithium is disposed on the first side of the second current collector, 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 plate according to claim 18 or 19, characterized in that, the second current collector is a composite current collector.

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

22. The bipolar plate 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 opposite side of the second base film, the fifth active material layer being disposed on the third conductive layer, and the sixth active material layer being disposed on the fourth conductive layer.

23. The bipolar plate according to claim 19, 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 opposite side of the second base film, the seventh active material layer being disposed on the third conductive layer, and the sixth active material layer being disposed on the fourth conductive layer.

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

25. The bipolar electrode according to claim 18, characterized in that, the positive active material comprises at least one of lithium nickel cobalt manganese oxide, lithium manganese iron phosphate, lithium iron phosphate, lithium manganate, lithium cobaltate, lithium nickelate, lithium-rich manganese-based positive electrode material, lithium nickel manganese oxide, and lithium vanadium phosphate oxide.

26. A method for preparing a bipolar electrode, characterized in that, comprising: providing a second current collector, the second current collector comprising an opposite first side and a second side; forming a fifth active material layer on the first side of the second current collector, the fifth active material layer comprising a lithium metal alloy; forming a sixth active material layer on the second side of the second current collector, the sixth active material layer comprising a positive active material.

27. The method according to claim 26, characterized in that, further comprising: before forming the fifth active material layer on the first side of the second current collector, pre-forming a seventh active material layer on the first side of the second current collector, the seventh active material layer comprising lithium metal.

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

29. The battery according to claim 28, characterized in that, the battery comprises a liquid battery, a semi-solid battery, and a solid-state battery.

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

31. The battery according to claim 30, characterized in that, the lithium salt comprises at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethylsulfonyl-n-perfluorobutanesulfonylimide, lithium fluorosulfonyl-n-perfluorobutanesulfonylimide, lithium bis(oxalato)borate, and lithium tris(trifluoromethylsulfonyl)methyl.

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

33. The battery according to claim 30, characterized in that, the electrolyte further comprises an additive.

34. The battery according to claim 33, characterized in that, the additive comprises at least one of a film-forming additive, a conductive additive, a flame retardant additive, an overcharge protection additive, an additive for controlling the 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 battery and a 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, wherein, 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 Li 6 PS 5 F, Li 6 PS 5 Cl, Li 6 PS 5 Br, Li 6 PS 5 I, Li 2 S-SiS 2 , Li 2 S-P 2 S 5 , Li 2 S-GeS 2 , Li 2 S-SiS 2 -P 2 S 5 , Li 2 S-GeS 2 -P 2 S 5 , Li 2 S-SnS 2 -P 2 S 5 and Li 2 S-AlS 2 -P 2 S 5 and at least one of the following; the halide solid electrolyte includes Li 2 MnCl 4 , Li 2 ZnCl 4 , LiYbF 4 , LiAlF 4 , Li 3 YCl 6 , Li 3 BrCl 6 and Li 6 CoCl 8 and at least one of the following.

37. The battery according to claim 35, wherein, The polymer solid electrolyte includes a polymer matrix, inorganic fillers, and a lithium salt. The polymer matrix includes at least one of polyethylene oxide, polycarbonate, poly(trimethylene carbonate), polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, poly(vinylidene fluoride - hexafluoroethylene) copolymer, and lithium polyacrylate. The inorganic fillers include Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 , lithium lanthanum zirconium oxide, alumina, and at least one of metal - organic frameworks. The lithium salt includes at least one of LiAsF 6 , LiPF 6 , LiClO 4 , lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium tetrafluoroborate.

38. An electrical device, wherein, it includes the battery according to any one of claims 28-37.

Images