Negative pole piece, solid-state battery and electric device

Abstract

The invention discloses a negative pole piece, a solid-state battery and an electric device, and belongs to the technical field of batteries, the negative pole piece comprises a negative current collector, and a metal layer, an insulating layer and a first electrolyte layer which are sequentially arranged on at least one surface of the negative current collector; the insulating layer and the metal layer are provided with a plurality of hole structures, the hole structures penetrate through the insulating layer, and the hole structures extend to the metal layer; the pore structure is filled with a second electrolyte layer, and the second electrolyte layer is in contact with the first electrolyte layer; the metal layer comprises at least one of lithium and lithium alloy. According to the negative electrode piece, interface damage caused by volume change in the deposition process can be buffered, the structural stability and the self-repairing capability of the electrolyte layer are improved, the structural integrity of an electrolyte membrane after long circulation is kept, the circulation stability of a solid-state battery is effectively improved, and volume expansion is reduced.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a negative electrode plate, a solid-state battery and an electrical device. Background Art

[0002] Solid-state batteries (such as solid-state lithium metal batteries) offer high safety and high energy density, and are an important development direction for future high-performance lithium batteries. However, solid-state lithium metal batteries currently face numerous challenges, severely restricting their large-scale application.

[0003] The charging and discharging process of the lithium metal negative electrode is accompanied by drastic volume changes and is prone to the formation of dendrites, making it difficult to maintain a stable interface between the lithium negative electrode and the solid electrolyte layer, resulting in problems such as interface separation and electrolyte layer cracking, which ultimately leads to rapid attenuation of battery capacity, and even dendrites penetrating the electrolyte layer, causing safety problems.

[0004] In view of this, this application is filed. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a negative electrode plate, a solid-state battery and an electrical device, which can effectively improve the cycle stability of the solid-state battery and reduce volume expansion.

[0006] To achieve the above objectives, the first aspect of the present application provides a negative electrode sheet, comprising a negative electrode current collector and a metal layer, an insulating layer, and a first electrolyte layer sequentially disposed on at least one surface of the negative electrode current collector; the insulating layer and the metal layer are provided with a plurality of pore structures, the pore structures penetrating the insulating layer and extending to the metal layer;

[0007] The pore structure is filled with a second electrolyte layer, and the second electrolyte layer is in contact with the first electrolyte layer;

[0008] The metal layer includes at least one of lithium and a lithium alloy.

[0009] As an embodiment of the present application, the distance between adjacent second electrolyte layers is D, which satisfies: 1 μm≤D≤40 μm.

[0010] As an embodiment of the present application, the shape of the hole structure is one of cylindrical and conical.

[0011] As an embodiment of the present application, the diameter of the pore structure is R, which satisfies: 10 μm ≤ R ≤ 100 μm; and / or

[0012] The height of the pore structure is h, 1 μm≤h≤100 μm.

[0013] As an embodiment of the present application, the volume ratio of the second electrolyte layer to the pore structure is (5-50): (50-95).

[0014] As an embodiment of the present application, the first solid electrolyte layer includes a solid electrolyte, and the mass percentage of the solid electrolyte in the first solid electrolyte layer is -50 to 98%; and / or

[0015] The second solid electrolyte layer includes a solid electrolyte, and the mass percentage of the solid electrolyte in the second solid electrolyte layer is 50 to 98%;

[0016] As an embodiment of the present application, the first solid electrolyte further includes a binder, a filler and a lithium salt;

[0017] The second solid electrolyte layer further includes a binder, a filler and a lithium salt.

[0018] As an embodiment of the present application, at least one of the following (1) to (10) is satisfied:

[0019] (1) The solid electrolyte includes at least one of a sulfide electrolyte, an oxide electrolyte, a polymer electrolyte, and a halide electrolyte;

[0020] (2) The binder comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, butyl rubber, polyurethane, and polymethyl methacrylate;

[0021] (3) The filler comprises at least one of alumina, silica, titanium oxide, montmorillonite, zeolite, and metal organic framework;

[0022] (4) The lithium salt includes at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium chlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalatoborate), and lithium difluorooxalatoborate;

[0023] (5) The mass percentage of the binder in the first electrolyte layer is 0 to 10%;

[0024] (6) The mass percentage of the binder in the second electrolyte layer is 0 to 10%;

[0025] (7) The mass percentage of the filler in the first electrolyte layer is 0 to 50%;

[0026] (8) The mass percentage of the filler in the second electrolyte layer is 0 to 50%;

[0027] (9) The mass percentage of the lithium salt in the first electrolyte layer is 0 to 20%;

[0028] (10) The mass percentage of the lithium salt in the second electrolyte layer is 0 to 20%.

[0029] As an embodiment of the present application, at least one of the following (11) to (13) is satisfied:

[0030] (11) The thickness of the first electrolyte layer is 0.1 to 100 μm;

[0031] (12) The thickness of the metal layer is 1 to 100 μm;

[0032] (13) The thickness of the insulating layer is 0.1 to 10 μm.

[0033] As an embodiment of the present application, the mass percentage of lithium element in the metal layer is ≥5%; and / or

[0034] The insulating layer includes at least one of lithium oxide, lithium nitride, lithium fluoride, lithium hydroxide, lithium carbonate, aluminum oxide, silicon dioxide, lithium oxide, polyacrylonitrile, polypropylene, polyethylene, polytetrafluoroethylene, polyvinylidene fluoride, polyimide, and polyurethane.

[0035] A second aspect of the present application provides a solid-state battery comprising the negative electrode plate described above.

[0036] A third aspect of the present application provides an electrical device comprising the solid-state battery described above.

[0037] The beneficial effects of the present invention are as follows: the negative electrode current collector of the present application and the metal layer, the insulating layer and the first electrolyte layer sequentially arranged on at least one surface of the negative electrode current collector, and multiple pore structures are provided on the insulating layer and the metal layer, and the pore structure is filled with a second electrolyte layer. The negative electrode sheet of the present application is provided with multiple pore structures on the insulating layer and the metal layer, which can effectively reduce the mass and thickness of the negative electrode, effectively improve the energy density of the solid-state battery, and does not require pre-lithiation or the introduction of a porous conductive matrix. It has high affinity for lithium and high utilization of the pore structure, which can effectively reduce the volume expansion of the negative electrode sheet. At the same time, the pore structure is provided to provide sufficient deposition space for lithium elements. The second electrolyte layer is provided in the pore structure to ensure that lithium is deposited inside the pore structure, effectively avoiding internal and surface lithium deposition. At the same time, the second electrolyte layer has excellent ionic conductivity and lithium stability as well as certain rigidity and flexibility, which can effectively reduce lithium dendrites, buffer the interface damage caused by volume change during deposition, improve the structural stability and self-repair ability of the electrolyte layer, maintain the structural integrity of the electrolyte membrane after long cycles, effectively improve the cycle stability of the solid-state battery, and reduce volume expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1Schematic diagram of the structure of the negative electrode sheet according to one embodiment of the present invention.

[0039] Figure 2 Schematic diagram of the structure of the negative electrode sheet of Comparative Example 1.

[0040] Figure 3 Schematic diagram of the structure of the negative electrode sheet of Comparative Example 2.

[0041] Figure 4 Schematic diagram of the structure of the negative electrode sheet of Comparative Example 3.

[0042] Figure 5 Schematic diagram of the structure of the negative electrode sheet of Comparative Example 4.

[0043] Markings in the figure: 1, negative electrode current collector; 2, metal layer; 3, insulating layer; 4, first electrolyte layer; 5, pore structure; 6, second electrolyte layer. DETAILED DESCRIPTION

[0044] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0045] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0046] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0047] Unless otherwise specified, the components, raw materials or instruments used in the embodiments and comparative examples of the present invention are all commercially available raw materials or instruments, and the components and raw materials used in each parallel experiment are all of the same kind.

[0048] The inventors of this application have found that in order to reduce the volume change of solid-state lithium metal batteries during the charging and discharging process and avoid the formation of lithium dendrites, the existing technology uses a highly conductive porous matrix (referred to as a porous conductive matrix) as a lithium metal negative electrode current collector: but the preparation process of the porous conductive matrix is ​​relatively complicated, and the material is usually a conductive carbon material, a porous metal network material, etc., with a large volume and mass; resulting in a decrease in the energy density of the battery. At the same time, the porous conductive matrix has a weak affinity for lithium: complex lithium-affinity modifications are required, such as coating the surface of the conductive matrix with lithium-affinity oxides, lithium-affinity metal layers, etc., to ensure that lithium can be deposited in the reserved pore structure. In addition, the porous conductive matrix needs to be pre-lithiated before use, such as melt infiltration, mechanical rolling composite method, in-situ deposition method, etc., to ensure the high initial efficiency of the battery; but the preparation process is complicated and not suitable for scale.

[0049] Therefore, based on the above questions, Figure 1 As shown, the embodiment of the present application provides a negative electrode sheet, including a negative electrode current collector 1 and a metal layer 2, an insulating layer 3 and a first electrolyte layer 4 sequentially arranged on at least one surface of the negative electrode current collector; a plurality of pore structures 5 are provided on the insulating layer and the metal layer, the pore structures penetrate the insulating layer and extend to the metal layer;

[0050] The pore structure is filled with a second electrolyte layer 6, which is in contact with the first electrolyte layer;

[0051] The metal layer includes at least one of lithium and a lithium alloy.

[0052] The negative electrode collector of the present application and the metal layer, insulating layer and first electrolyte layer sequentially arranged on at least one surface of the negative electrode collector, and multiple pore structures are provided on the insulating layer and the metal layer, and the pore structure is filled with a second electrolyte layer. The negative electrode plate of the present application is provided with multiple pore structures on the insulating layer and the metal layer, which can effectively reduce the mass and thickness of the negative electrode, effectively improve the energy density of the solid-state battery, and does not require pre-lithiation or the introduction of a porous conductive matrix. It has high affinity for lithium and high utilization of the pore structure, which can effectively reduce the volume expansion of the negative electrode plate. At the same time, the pore structure is provided to provide sufficient deposition space for lithium elements. A second electrolyte layer is provided in the pore structure to ensure that lithium is deposited inside the pore structure, effectively avoiding internal and surface lithium deposition. At the same time, the second electrolyte layer has excellent ionic conductivity and lithium stability as well as certain rigidity and flexibility, which can effectively reduce lithium dendrites, buffer the interface damage caused by volume change during deposition, improve the structural stability and self-repair ability of the electrolyte layer, maintain the structural integrity of the electrolyte membrane after long cycles, effectively improve the cycle stability of the solid-state battery, and reduce volume expansion.

[0053] In some embodiments, the distance between adjacent second electrolyte layers is D, satisfying: 1μm≤D≤40μm, for example, it can be 1, 2, 4, 5, 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40 or a range consisting of any two of these values. By controlling D within this range, the structural stability of the negative electrode sheet can be improved, excessive local current can be avoided, lithium dendrites can be reduced, the deposition and release of lithium metal can be promoted, the collapse of the pore structure can be avoided, and the cycle life of the solid-state battery can be effectively improved.

[0054] In some embodiments, the pore structure is cylindrical in shape. By setting the pore structure to be cylindrical, a higher pore volume can be provided, which can more effectively improve the deposition effect of lithium metal and promote the deposition and removal of lithium metal.

[0055] In some embodiments, the shape of the pore structure is conical. By setting the pore structure to a conical shape, the structural stability of the negative electrode plate can be improved, the filling effect of the electrolyte in the pore structure can be improved, the pore utilization rate can be improved, the impedance can be reduced, and the cycle life performance of the solid-state battery can be improved.

[0056] In some embodiments, the diameter of the pore structure is R, which satisfies: 10μm≤R≤100μm, for example, it can be 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or a range consisting of any two of these values. Controlling R within this range can increase the specific surface area, improve the filling effect of the electrolytic electrolyte in the pore structure, improve the pore utilization, reduce the impedance, and increase the cycle life of the solid-state battery.

[0057] In some embodiments, 50 μm ≤ R ≤ 80 μm is satisfied.

[0058] In some embodiments, the height of the pore structure is h, 1μm≤h≤100μm, for example, it can be 1, 3, 5, 10, 20, 30, 50, 100 or a range consisting of any two values ​​therein. By controlling h within this range, it is possible to ensure that there is sufficient space for lithium deposition, reduce volume expansion, and improve the cycle stability of the solid-state battery.

[0059] In some embodiments, the volume ratio of the second electrolyte layer to the pore structure is (5-50): (50-95), for example, it can be 5:95, 10:90, 20:80, 30:70, 40:60, 50:50 or a range consisting of any two of these values. By controlling the volume ratio of the second electrolyte layer to the pore structure within a certain range, the utilization rate of the pore structure can be improved, the transmission performance of lithium ions can be improved, the volume expansion can be further reduced, and the cycle stability of the solid-state battery can be improved.

[0060] In some embodiments, the second electrolyte layer completely covers the sides of the metal layer and the insulating layer.

[0061] In some embodiments, the second electrolyte layer is in the shape of a groove with an open top.

[0062] In some embodiments, the first solid electrolyte layer includes a solid electrolyte, and the mass percentage of the solid electrolyte in the first solid electrolyte layer is 50 to 98%, for example, it can be 50%, 60%, 70%, 80%, 90%, 98% or a range consisting of any two values ​​therein. By controlling the mass percentage of the solid electrolyte in the first solid electrolyte layer within this range, it is possible to ensure that the first solid electrolyte layer has high ionic conductivity, reduce impedance, and improve rate performance and cycle life.

[0063] In some embodiments, the first solid electrolyte further includes a binder, a filler, and a lithium salt.

[0064] In some embodiments, the mass percentage of the binder in the first electrolyte layer is 0-10%, for example, it can be 0%, 1%, 2%, 3%, 5%, 8%, 10% or a range consisting of any two values ​​therein.

[0065] In some embodiments, the mass percentage of the filler in the first electrolyte layer is 0-50%, for example, it can be 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50% or a range consisting of any two values ​​therein.

[0066] In some embodiments, the mass percentage of the lithium salt in the first electrolyte layer is 0-20%, for example, it can be 0%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20% or a range consisting of any two values ​​therein.

[0067] By controlling the mass percentage of solid electrolyte, filler, lithium salt and binder within the above range, an ionic conductivity of ≥10 -4 S / cm, an elastic modulus of 0.1-10GPa, and an electrolyte porosity of ≤5%; the first electrolyte layer can provide high ionic conductivity, reduce impedance, and improve rate performance; in addition, it can provide high mechanical strength, inhibit the growth of lithium dendrites, avoid short circuits, maintain the stability of the negative electrode structure, and improve the battery cycle life.

[0068] In some embodiments, the second solid electrolyte layer includes a solid electrolyte, and the mass percentage of the solid electrolyte in the second solid electrolyte layer is 50 to 98%, for example, it can be 50%, 60%, 70%, 80%, 90%, 98% or a range consisting of any two values ​​therein. By controlling the mass percentage of the solid electrolyte in the second solid electrolyte layer within this range, it is possible to ensure that the second solid electrolyte layer has high ionic conductivity, reduce impedance, and improve rate performance and cycle life.

[0069] In some embodiments, the second solid electrolyte further includes a binder, a filler, and a lithium salt.

[0070] In some embodiments, the mass percentage of the binder in the second electrolyte layer is 0-10%, for example, it can be 0%, 1%, 2%, 3%, 5%, 8%, 10% or a range consisting of any two values ​​therein.

[0071] In some embodiments, the mass percentage of the filler in the second electrolyte layer is 0 to 50%, for example, it can be 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50% or a range consisting of any two values ​​therein.

[0072] In some embodiments, the mass percentage of the lithium salt in the second electrolyte layer is 0-20%, for example, it can be 0%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20% or a range consisting of any two values ​​therein.

[0073] By controlling the mass percentage of solid electrolyte, filler, lithium salt and binder within the above range, an ionic conductivity of ≥10 -4 S / cm, an elastic modulus of 0.1-10GPa, and a second electrolyte layer with an electrolyte porosity of ≤5%. The second electrolyte layer can provide high ionic conductivity, reduce impedance, and improve rate performance; in addition, it can provide high mechanical strength, inhibit the growth of lithium dendrites, avoid short circuits, maintain the stability of the negative electrode structure, and improve the battery cycle life.

[0074] In some embodiments, the solid electrolyte includes at least one of a sulfide electrolyte, an oxide electrolyte, a halide electrolyte, and a polymer electrolyte.

[0075] In some embodiments, the sulfide electrolyte includes Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 10 GeP2S 12 , Li2S-P2S5, LiSiPSCl, Li7P3S11 、Li 5.5 PS 4.5 Cl 1.5 、Li 10 SnP2S 12 At least one of .

[0076] In some embodiments, the oxide electrolyte includes Li 1+x Al x Ti 2-x (PO4)3Li 1+x Al x Ti 2-x (PO4)3、Li 7-y La3Zr 2-y O 12 、Li 3z La 2 / 3-z At least one of TiO3, wherein 0≤x≤0.5, 0≤y≤0.2, and 0≤z≤0.16.

[0077] In some embodiments, the halide electrolyte includes at least one of Li3M1X16, Li2M2X24, and Li3OX3;

[0078] Among them, M1 includes at least one of Y, Er, Ho, In, Sc, Tb, Dy, Gd, and Sm, M2 includes at least one of Zr, Hf, Ti, and Sn; and X1, X2, and X3 each independently include at least one of Cl and Br.

[0079] In some embodiments, the D50 particle size of the above-mentioned inorganic solid electrolyte is 5 to 200 nm, for example, it can be 5 nm, 8 nm, 10 nm, 20 nm, 40 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 160 nm, 200 nm or a range consisting of any two values ​​therein.

[0080] In some embodiments, the polymer electrolyte includes at least one of polyethylene oxide, polyvinyl pyrrolidone, polyvinylidene fluoride, polyacrylonitrile, polyethylene glycol, and polyethylene glycol dimethyl ether.

[0081] In some embodiments, the binder includes at least one of polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), butyl rubber, polyurethane, and polymethyl methacrylate.

[0082] In some embodiments, the filler comprises at least one of alumina, silica, titania, montmorillonite, zeolite, and metal-organic framework;

[0083] In some embodiments, the lithium salt includes at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium chlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalatoborate), and lithium difluorooxalatoborate;

[0084] In some embodiments, the thickness of the first electrolyte layer is 0.1 to 100 μm, for example, it can be 0.1 μm, 0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, 20 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or a range consisting of any two of these values. By controlling the thickness of the first electrolyte layer within this range, a continuous and complete solid electrolyte layer is formed, ensuring the uniformity of ion distribution at various positions on the negative electrode surface, improving the lithium metal deposition morphology, and improving the cycle stability; when the thickness of the first electrolyte layer is relatively small (0.1 to 10 μm), it acts as an interface buffer layer to improve the stability of the negative electrode and the electrolyte membrane in the solid-state battery and improve the cycle performance; when the thickness of the first electrolyte layer is relatively large (10 to 100 μm), it can be used as an electrolyte membrane in a solid-state battery, has high mechanical strength, can be directly assembled with the positive electrode to make a battery, and simplifies the battery manufacturing process.

[0085] In some embodiments, the thickness of the first electrolyte layer is 0.1 to 10 μm.

[0086] In some embodiments, the thickness of the first electrolyte layer is 0.1 to 5 μm.

[0087] In some embodiments, the thickness of the metal layer is 1 to 100 μm, for example, it can be 1 μm, 2 μm, 4 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or a range consisting of any two of these values. By controlling the thickness of the metal layer within this range, sufficient pore structure can be provided to provide space for lithium deposition, reduce volume expansion, and improve circulation; in addition, the metal layer acts as a lithium source, ensuring that the battery has high coulombic efficiency and improving cycle life.

[0088] In some embodiments, the metal layer has a thickness of 10 to 100 μm.

[0089] In some embodiments, the thickness of the metal layer is 20-100 μm.

[0090] In some embodiments, the thickness of the insulating layer is 0.1 to 10 μm, for example, it can be 0.1 μm, 0.2 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.8 μm, 1 μm, 2 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm or a range consisting of any two of these values. By controlling the thickness of the insulating layer within this range, it is ensured that the insulating layer has high mechanical strength, maintains structural stability, and improves cycle performance; at the same time, it can reduce the impact of excessive thickness of the insulating layer on the mass and volume of the battery, ensuring high energy density.

[0091] In some embodiments, the mass percentage of lithium in the metal layer is ≥5%; and / or

[0092] The insulating layer includes at least one of lithium oxide, lithium nitride, lithium fluoride, lithium hydroxide, lithium carbonate, aluminum oxide, silicon dioxide, lithium oxide, polyacrylonitrile, polypropylene, polyethylene, polytetrafluoroethylene, polyvinylidene fluoride, polyimide, and polyurethane.

[0093] In some embodiments, the electronic conductivity of the insulating layer is 10 -18 ~10 -8 s / cm.

[0094] In some embodiments, the thickness of the negative electrode current collector is 1 to 20 μm, for example, it can be 1 μm, 2 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 15 μm, 16 μm, 18 μm, 20 μm or a range consisting of any two values ​​therein.

[0095] In the present application, there is no particular limitation on the negative electrode current collector, as long as it can achieve the purpose of the present application. For example, it can be copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foamed nickel, conductive carbon, graphene, foamed copper or a composite current collector.

[0096] In some embodiments, the method for preparing the negative electrode sheet comprises the following steps:

[0097] The metal layer and the negative electrode current collector are compounded, an insulating layer is formed on the surface of the metal layer, and a pore structure is formed between the metal layer and the insulating layer.

[0098] The polymer, inorganic filler, lithium salt, and solid electrolyte layer are added to the solvent and mixed evenly to obtain a slurry. The slurry is used to form a second solid electrolyte layer in the pore structure, and the slurry is dried and solidified to form a second solid electrolyte layer.

[0099] Composite the lithium layer with the current collector; apply an insulating layer on the surface of the lithium layer by evaporation, coating, transfer printing, etc.; create a pore structure by mechanical drilling or laser drilling, etc. to obtain a porous lithium metal matrix;

[0100] The slurry is coated on the surface of the release substrate, dried and solidified, and the surface of the transfer insulation layer is removed, and hot pressing and compounding are performed to obtain the negative electrode sheet.

[0101] Exemplarily, the insulating layer may be formed by the following method:

[0102] 1. In-situ reaction method: Polish the surface of the metallic lithium to remove the original impurity layer; expose it to a reaction environment (such as standing in an oxygen atmosphere, or coating the surface with a trace amount of polar solvent), react for a certain period of time, clean and dry it, and complete the preparation of the insulating layer.

[0103] 2. Coating method: Inorganic fillers are mixed with adhesives, polymers, etc. to prepare slurry, or without adding inorganic fillers, polymer slurry or melt is directly used: Method 1, directly applied to the surface of lithium metal, methods include but are not limited to coating, spraying, dipping, etc., after drying and solidification, strong adhesion, simple operation, suitable for solvent systems that are stable to lithium; Method 2, first apply to the surface of a blank substrate, methods include but are not limited to coating, spraying, dipping, sputtering, evaporation, in situ polymerization, etc., after drying and solidification, transfer to the surface of the negative electrode, and a wide range of applicable solvent systems.

[0104] In the present application, the hole structure is achieved by laser drilling and / or mechanical drilling.

[0105] Methods for forming the second solid electrolyte layer in the pore structure include, but are not limited to, casting, dipping, and in-situ deposition.

[0106] One embodiment of the present application provides a solid-state battery, comprising the negative electrode plate described above.

[0107] In one embodiment, the solid-state battery includes a positive electrode sheet, the positive electrode sheet includes a positive electrode collector and a positive electrode active material layer disposed on at least one surface of the positive electrode collector, and the positive electrode active material layer includes a positive electrode active material.

[0108] In one embodiment, the positive electrode active material may be a positive electrode active material for solid-state batteries known in the art.

[0109] As non-limiting examples, the positive electrode active material may include lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials or substances, and other traditional materials or substances that can be used as solid-state battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, non-limiting examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds.

[0110] In one embodiment, the positive electrode active material layer further includes a solid electrolyte, and the solid electrolyte includes at least one of a sulfide electrolyte, an oxide electrolyte, a polymer electrolyte, and a halide electrolyte.

[0111] In some embodiments, the sulfide electrolyte includes Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 10 GeP2S 12 , Li2S-P2S5, LiSiPSCl, Li7P3S 11 、Li 5.5 PS 4.5 Cl 1.5 、Li 10 SnP2S 12 At least one of .

[0112] In some embodiments, the oxide electrolyte includes Li 1+x Al x Ti 2-x (PO4)3、Li 7-y La3Zr 2- y O 12 、Li 3z La 2 / 3-z At least one of TiO3, wherein 0≤x≤0.5, 0≤y≤0.2, and 0≤z≤0.16.

[0113] In some embodiments, the halide electrolyte includes at least one of Li3M1X16, Li2M2X24, and Li3OX3;

[0114] Among them, M1 includes at least one of Y, Er, Ho, In, Sc, Tb, Dy, Gd, and Sm, M2 includes at least one of Zr, Hf, Ti, and Sn; and X1, X2, and X3 each independently include at least one of Cl and Br.

[0115] In some embodiments, the polymer electrolyte includes at least one of polyethylene oxide, polyvinyl pyrrolidone, polyacrylonitrile, polyethylene glycol, and polyethylene glycol dimethyl ether.

[0116] In some embodiments, the type of the positive electrode current collector is not particularly limited, and the positive electrode current collector can be any material known to be suitable for use as a positive electrode current collector.

[0117] In some embodiments, the positive electrode current collector includes metal materials such as aluminum, stainless steel, nickel plating, titanium, tantalum, and carbon materials such as carbon cloth and carbon paper.

[0118] The form of the positive electrode current collector is not particularly limited. When the positive electrode current collector is a metal material, the positive electrode current collector may be in the form of metal foil, metal cylinder, metal strip coil, metal plate, metal foil, metal mesh, stamped metal, foamed metal, etc. When the positive electrode current collector is a carbon material, the positive electrode current collector may be in the form of, but not limited to, carbon plate, carbon film, carbon cylinder, etc.

[0119] In some embodiments, the type of the conductive agent mentioned in the present application is not limited, and known conductive agents can be used.

[0120] In some embodiments, the solid-state battery may include an outer packaging, which can be used to encapsulate the above-mentioned electrode assembly and electrolyte.

[0121] In some embodiments, the outer packaging of the solid-state battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the solid-state battery can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0122] The present application has no particular limitation on the shape of the solid-state battery, which may be cylindrical, square, or any other shape.

[0123] One embodiment of the present application provides an electrical device, comprising the solid-state battery described above, wherein the solid-state battery serves as a power supply for the electrical device.

[0124] Exemplarily, the above-mentioned electrical devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.

[0125] The following examples are provided to facilitate understanding of the present invention. These examples are not provided to limit the scope of the claims.

[0126] Example 1

[0127] A preparation method of a solid-state battery comprises the following steps:

[0128] (1) Preparation of negative electrode sheet:

[0129] Using 8μm copper foil as the negative electrode current collector, lithium foil was roll-pressed onto the copper foil surface to form a 20μm thick lithium metal layer on the copper foil surface;

[0130] Alumina and polyacrylonitrile were dispersed in dimethylformamide (DMF) at a mass ratio of 1:4, and the mixture was stirred thoroughly to form a slurry with a solid content of 20%. The slurry was coated on the surface of a PET film, dried at 60°C for 6 hours, and the PET film was removed to obtain an insulating layer with a thickness of 1 μm. The insulating layer was transferred to the surface of the lithium metal layer and rolled to obtain a composite membrane.

[0131] The composite membrane is rolled using a roller with a needle roller. The needle roller is cylindrical (with a diameter of 50 μm and a depth (also known as height) of 17 μm). The spacing D of the pore structure formed by rolling is controlled to be 10 μm (the distance between adjacent second solid electrolyte layers after the second solid electrolyte layer is formed).

[0132] Disperse 7 g of polyethylene oxide (PEO), 1 g of polyacrylonitrile (PAN), 0.5 g of aluminum oxide, and 1.5 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) powder in acetonitrile, fully dissolve and disperse uniformly to obtain a slurry (the amount of slurry is sufficient for subsequent steps);

[0133] The slurry is coated in the pore structure to form a second solid electrolyte layer, and the slurry is coated on the PET surface, dried and solidified to obtain an electrolyte membrane with a thickness of 5μm, and the insulating layer surface is transferred, the PET is removed, and hot pressing and compounding are performed to obtain the negative electrode sheet.

[0134] The parameters of the negative electrode are shown in Table 1.

[0135] (2) Preparation of positive electrode: lithium cobalt oxide, sulfide electrolyte Li6PS5Cl, PVDF, and SP were added to toluene in a mass ratio of 80:10:5:5, stirred and mixed for 4 hours, and the mixed slurry was evenly coated on the surface of aluminum foil and dried at 80°C in a vacuum oven for 8 hours to obtain a positive electrode; the surface capacity was 3 mAh / cm 2 .

[0136] (3) Solid electrolyte membrane: Sulfide electrolyte Li6PS5Cl and PVDF were added to toluene in a mass ratio of 95:5, stirred and mixed for 2 h, and then the mixed slurry was evenly coated on the PET surface and dried at 80 °C in a vacuum for 8 h to obtain a Li6PS5Cl self-supporting membrane with a thickness of 30 μm.

[0137] (4) Assembly of solid-state batteries: stack the positive electrode sheet, electrolyte membrane, and negative electrode sheet in order to obtain an electrode assembly; place the electrode assembly in a packaging shell and encapsulate it. After encapsulation, the battery is pressurized to ensure sufficient interface contact to obtain a solid-state battery.

[0138] Examples 2 to 4

[0139] The difference between Examples 2 to 4 and Example 1 is that the thickness of the insulating layer is adjusted, as shown in Table 1.

[0140] Examples 5 to 7

[0141] The difference between Examples 5 to 7 and Example 1 is that the thickness of the lithium metal layer and the depth (h) of the needle roller are adjusted, as shown in Table 1.

[0142] Examples 8 to 11

[0143] The difference between Examples 8 to 11 and Example 1 is that the thickness of the first solid electrolyte layer is adjusted, as shown in Table 1.

[0144] Examples 12 to 14

[0145] The difference between Examples 12 to 14 and Example 1 is that the spacing D of the hole structure formed by rolling is adjusted, as shown in Table 1.

[0146] Examples 15 to 17

[0147] The difference between Examples 15 to 17 and Example 1 is that the diameter of the needle and the volume ratio of the second electrolyte layer to the pore structure are adjusted, as shown in Table 1.

[0148] Examples 18 to 20

[0149] The difference between Examples 18 to 20 and Example 1 is that the ratio and type of raw materials of the solid electrolyte layer are adjusted, as shown in Table 2.

[0150] Wherein, the LATP of Example 20 includes Li 1.3 Al 0.3 Ti 1.7 (PO4)3.

[0151] Comparative Example 1

[0152] The difference between Comparative Example 1 and Example 1 is that the preparation method of the negative electrode sheet is different, and Comparative Example 1 does not contain the first electrolyte layer. Figure 2 shown.

[0153] Comparative Example 2

[0154] The difference between Comparative Example 2 and Example 1 is that the preparation method of the negative electrode sheet is different, and Comparative Example 2 does not contain a pore structure, such as Figure 3 shown.

[0155] Comparative Example 3

[0156] The difference between Comparative Example 3 and Example 1 is that the pore structure of Comparative Example 3 does not contain a second solid electrolyte layer. Figure 4 shown.

[0157] Comparative Example 4

[0158] The difference between Comparative Example 4 and Example 1 is that the hole structure of Comparative Example 4 does not contain an insulating layer. Figure 5 shown.

[0159] Table 1

[0160]

[0161] Table 2

[0162]

[0163]

[0164] Performance Testing

[0165] The solid-state batteries prepared in the comparative examples and the examples were repeatedly charged and discharged through the following steps, and the cycle capacity retention rate of the solid-state batteries was calculated.

[0166] First, perform the first charge and discharge at 25°C. Perform constant current and constant voltage charging at a charging current of 0.1C (i.e., the current value that completely discharges the theoretical capacity within 10 hours) until the upper limit voltage reaches 4.5V. Then, perform constant current discharge at a discharge current of 1C until the final voltage reaches 3V. Record the discharge capacity of the first cycle. Then, perform 200 charge and discharge cycles, and record the discharge capacity of the 200th cycle. Cycle capacity retention = (discharge capacity of the 200th cycle / discharge capacity of the first cycle) × 100%.

[0167] Expansion rate: Initial thickness: Before assembling the negative electrode sheet into a secondary battery, use a micrometer to measure the thickness of the center area of ​​the negative electrode sheet. Take 3 points and measure 3 times. The average thickness is taken as the initial thickness T0;

[0168] Thickness after expansion: After the secondary battery is fully charged, disassemble and remove the negative electrode; use a micrometer to measure the thickness of the center area of ​​the electrode, select 3 points, measure 3 times, and the average thickness is the thickness after expansion T1;

[0169] Calculation of expansion rate: (T1-T0) / T0×100%.

[0170] Table 3

[0171]

[0172] As can be seen from Table 3, the negative electrode current collector of the present application and the metal layer, insulating layer and first electrolyte layer sequentially arranged on at least one surface of the negative electrode current collector, and multiple pore structures are provided on the insulating layer and the metal layer, and the pore structure is filled with the second electrolyte layer. The negative electrode plate described in the present application is provided with multiple pore structures on the insulating layer and the metal layer, which effectively improves the cycle stability of the solid-state battery and reduces volume expansion.

[0173] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A negative electrode plate, characterized in that: The invention comprises a negative electrode current collector and a metal layer, an insulating layer and a first electrolyte layer sequentially provided on at least one surface of the negative electrode current collector; a plurality of pore structures are provided on the insulating layer and the metal layer, the pore structures penetrate the insulating layer and extend to the metal layer; The pore structure is filled with a second electrolyte layer, and the second electrolyte layer is in contact with the first electrolyte layer; The metal layer includes at least one of lithium and a lithium alloy.

2. The negative electrode sheet according to claim 1, characterized in that: The distance between adjacent second electrolyte layers is D, which satisfies: 1 μm≤D≤40 μm.

3. The negative electrode sheet according to claim 1, characterized in that: The shape of the hole structure is cylindrical or conical.

4. The negative electrode sheet according to claim 3, characterized in that: The diameter of the pore structure is R, which satisfies: 10 μm ≤ R ≤ 100 μm; and / or The height of the pore structure is h, 1 μm≤h≤100 μm.

5. The negative electrode sheet according to claim 1, characterized in that: The volume ratio of the second electrolyte layer to the pore structure is (5-50):(50-95).

6. The negative electrode sheet according to claim 1, characterized in that: The first solid electrolyte layer comprises a solid electrolyte, and the mass percentage of the solid electrolyte in the first solid electrolyte layer is 50-98%; and / or The second solid electrolyte layer includes a solid electrolyte, and the mass percentage of the solid electrolyte in the second solid electrolyte layer is 50-98%.

7. The negative electrode sheet according to claim 6, characterized in that: The first solid electrolyte further includes a binder, a filler and a lithium salt; The second solid electrolyte layer further includes a binder, a filler and a lithium salt.

8. The negative electrode sheet according to claim 7, characterized in that: Satisfy at least one of the following (1) to (10): (1) The solid electrolyte includes at least one of a sulfide electrolyte, an oxide electrolyte, a polymer electrolyte, and a halide electrolyte; (2) The binder comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, butyl rubber, polyurethane, and polymethyl methacrylate; (3) The filler comprises at least one of alumina, silica, titanium oxide, montmorillonite, zeolite, and metal organic framework; (4) The lithium salt includes at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium chlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalatoborate), and lithium difluorooxalatoborate; (5) The mass percentage of the binder in the first electrolyte layer is 0 to 10%; (6) The mass percentage of the binder in the second electrolyte layer is 0 to 10%; (7) The mass percentage of the filler in the first electrolyte layer is 0 to 50%; (8) The mass percentage of the filler in the second electrolyte layer is 0 to 50%; (9) The mass percentage of the lithium salt in the first electrolyte layer is 0 to 20%; (10) The mass percentage of the lithium salt in the second electrolyte layer is 0 to 20%.

9. The negative electrode sheet according to claim 1, characterized in that: Satisfy at least one of the following (11) to (13): (11) The thickness of the first electrolyte layer is 0.1 to 100 μm; (12) The thickness of the metal layer is 1 to 100 μm; (13) The thickness of the insulating layer is 0.1 to 10 μm.

10. The negative electrode sheet according to claim 1, characterized in that: The mass percentage of lithium element in the metal layer is ≥5%; and / or The insulating layer includes at least one of lithium oxide, lithium nitride, lithium fluoride, lithium hydroxide, lithium carbonate, aluminum oxide, silicon dioxide, lithium oxide, polyacrylonitrile, polypropylene, polyethylene, polytetrafluoroethylene, polyvinylidene fluoride, polyimide, and polyurethane.

11. A solid-state battery, characterized in that: The negative electrode sheet comprises the negative electrode sheet according to any one of claims 1 to 10.

12. An electrical device, characterized in that: Including the solid-state battery according to claim 11.

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