Electrode sheet, manufacturing method therefor, and solid-state battery and manufacturing method therefor

Abstract

An electrode sheet, a manufacturing method therefor, and a solid-state battery and a manufacturing method therefor. A mixed conductive layer comprising a nano-conductive agent and an organic polymer solid-state electrolyte is introduced to the surface of an electrode sheet, the use of the nano-conductive agent effectively increases the contact area between the mixed conductive layer and the electrode sheet, and the organic polymer solid-state electrolyte can reduce the interface impedance, thus improving the cycling stability of solid-state batteries. Using ultrasonic spraying methods to spray slurry used for forming the mixed conductive layer can sufficiently refine slurry particles, so as to improve the stability of coatings and achieve uniform layered structures having controllable thicknesses, thus improving the structural stability of solid-state batteries.

Description

A pole piece and its preparation method and a solid-state battery and its preparation method

[0001] This application is based on the Chinese patent application with application number 202311007569.6 and application date August 10, 2023, and claims the priority of the Chinese patent application. The entire content of the Chinese application is hereby introduced into this application as a reference. Technical Field

[0002] The present invention belongs to the field of solid-state batteries and relates to a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. Background Art

[0003] Solid-state batteries have attracted widespread attention due to their reliable safety and high energy density. The thermal stability and chemical stability of solid-state electrolytes ensure the safety of solid-state batteries, while the structural design of solid-state battery electrodes and the interfacial contact between active materials are the key to improving the safety and energy density of solid-state batteries.

[0004] The existing solid-state battery structures can be divided into systems with diaphragms and systems without diaphragms. In the system with diaphragms, the diaphragm materials currently widely used are all organic polymer materials, which have the following two problems: on the one hand, they will shrink and melt when the battery is abnormally heated, causing large-area contact between the positive and negative pole pieces, short circuits, or even explosions; on the other hand, impurities and burrs in the battery may also pierce the diaphragm, causing direct contact between the positive and negative pole pieces, short circuits, and safety issues. For an ideal system without diaphragms, the solid-state battery structure can adopt a stacked structure of positive active material, solid electrolyte layer, and negative active material to form a battery cell. However, the existing solid-state battery structure and related processes have problems such as easy detachment of the active material coating and poor solid interface contact, which leads to battery performance degradation. In addition, the process of mass-producing pole pieces containing solid electrolytes is relatively difficult, which restricts the current development of solid-state battery industrialization.

[0005] Therefore, in order to solve the above-mentioned problems mentioned in the membrane-free system, a reasonable design of the solid-state structure and the selection of appropriate process methods can effectively solve the problem of interface contact between the solid-state electrolyte and the positive and negative active materials.

[0006] Solid-state lithium batteries with multifunctional layered composite solid electrolytes are currently available. This multifunctional layered solid electrolyte layer is formed by coating a solution containing a composite solid electrolyte onto the surface of the positive electrode, acting as a buffering solid electrolyte layer. The solid electrolyte layer is then positioned between the positive and negative electrodes to improve the interfacial contact between the solid electrolyte layer and the battery electrode. However, the interfacial contact between the composite solid electrolyte layer and the battery electrode is still point contact, and the coating thickness is uneven, failing to reduce the interfacial impedance and resulting in reduced battery cycling stability.

[0007] Summary of the Invention

[0008] Problems to be solved by the invention

[0009] In view of the problem that the interface contact between the above-mentioned composite solid electrolyte layer and the electrode is insufficient and the interface impedance still needs to be reduced, there is an urgent need for a electrode and solid-state battery with a reasonable electrode structure design and appropriate interlayer composition, which can improve the interface contact between the solid electrolyte and the battery electrode and enhance the cycle stability of the solid-state battery, as well as a preparation method that can improve the process effect of solid-state electrolyte introduction and solve the problem of mass production of solid-state battery electrodes.

[0010] Solutions for solving problems

[0011] To address the above-mentioned issues, the present invention provides a pole piece that can effectively solve the interfacial contact problem between the solid electrolyte and the battery pole piece, achieve close contact between the solid electrolyte and the positive and negative electrode active material particles, and reduce the thickness of the solid electrolyte layer, thereby achieving a uniform and stable interlayer structure, reducing the interfacial impedance, and improving the cycle stability of the solid-state battery. In addition, the present invention also provides a method for preparing the pole piece, which utilizes ultrasonic spraying to fully refine the slurry particles, improve the stability of the coating, and achieve a uniform layered structure with controllable thickness, thereby improving the structural stability of the solid-state battery and solving the problem of mass production of solid-state battery pole pieces.

[0012] Specifically, the present invention provides a pole piece, which includes a mixed conductive layer on a positive pole piece or a negative pole piece, wherein the mixed conductive layer includes a nano-conductive agent and an organic polymer solid electrolyte.

[0013] According to the pole piece described above, in the mixed conductive layer, the mass ratio of the nano-conductive agent to the organic polymer solid electrolyte is (85-20): (15-80), preferably (80-25): (20-75).

[0014] According to the above-mentioned pole piece, the particle size of the nano-conductive agent is 5-500 nm, preferably 10-300 nm.

[0015] According to the above-mentioned pole piece, the thickness of the mixed conductive layer is 100nm-1000nm, preferably 150-800nm;

[0016] Preferably, the mixed conductive layer further comprises a binder;

[0017] Preferably, the binder is selected from one or more of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium hydroxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-butadiene-styrene copolymer, polyacrylic acid, and lithium polyacrylate.

[0018] According to the pole piece described above, the nano-conductive agent is selected from one or more of conductive graphite, conductive carbon black, acetylene black, carbon nanotubes, Ketjen black, graphene, carbon nanofibers and polyethylene dioxythiophene;

[0019] Preferably, the organic polymer solid electrolyte is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, polypentylene succinate, polyvinyl chloride, polyvinyl carbonate, polyvinyl pyrrolidone, polyimide, polyacrylate, and polyurethane.

[0020] According to the pole piece described above, the pole piece further comprises a first composite solid electrolyte layer on the mixed conductive layer;

[0021] Preferably, the thickness of the first composite solid electrolyte layer is 200-3000 nm, preferably 250-2000 nm;

[0022] Preferably, the first composite solid electrolyte layer comprises an inorganic ceramic material, an organic polymer solid electrolyte, and a lithium salt.

[0023] According to the pole piece described above, the inorganic ceramic material used for the first composite solid electrolyte layer is selected from one or more of nitrides, carbides, metal oxides, and non-metallic oxides;

[0024] Preferably, the nitride is selected from one or more of silicon nitride, titanium nitride, aluminum nitride, boron nitride, and magnesium nitride; the carbide is selected from one or more of silicon carbide and boron carbide; the metal oxide is selected from one or more of aluminum oxide, titanium dioxide, zirconium dioxide, and magnesium oxide; and the non-metallic oxide is selected from one or more of silicon dioxide and boron oxide.

[0025] According to the pole piece described above, the pole piece further comprises a second solid electrolyte layer on the first composite solid electrolyte layer;

[0026] Preferably, the thickness of the second solid electrolyte layer is 2 μm-50 μm, preferably 5 μm-40 μm;

[0027] Preferably, the second solid electrolyte layer further comprises a lithium salt and / or a binder.

[0028] According to the pole piece described above, the solid electrolyte used for the second solid electrolyte layer includes one or more of an inorganic solid electrolyte and an organic polymer solid electrolyte;

[0029] Preferably, the inorganic solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, borate solid electrolytes, and nitride solid electrolytes.

[0030] According to the above-mentioned electrode sheet, wherein the oxide solid electrolyte is selected from one or more of perovskite-type oxide solid electrolytes, garnet-type oxide solid electrolytes, and NASICON-type oxide solid electrolytes;

[0031] The sulfide solid electrolyte is selected from one or more of lithium germanium phosphorus sulfur, lithium silicon phosphorus sulfur chlorine, lithium phosphorus sulfur bromine, lithium phosphorus sulfur iodine, lithium phosphorus sulfur chlorine, lithium thiophosphate, and vitreous sulfide;

[0032] The halide solid electrolyte is selected from g ijini3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1), Li2XCl4 (X is selected from Cd and / or Mg), Li2X′I4 (X′ is selected from Cd and / or Zn), LiMCl5X″ (M is selected from one or more of La, Ta, Nb, and X″ is selected from O, Cl, F, or OH), Li 3-y Zr y M′ 1-y Cl6 (M′ is selected from one or more of Y, Er, Yb, Ho, Lu, 0 < y < 1);

[0033] The borate solid electrolyte is selected from one or more of Li2B4O7, Li2O - B2O3 - P2O5;

[0034] The nitride solid electrolyte is selected from one or more of LiPON, Li3N, Li7PN4, LiSi2N3;

[0035] The organic polymer solid electrolyte is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene, polyvinylidene fluoride - chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, poly(ethylene succinate), polyvinyl chloride, poly(vinylidene carbonate), polyvinylpyrrolidone, polyimide, and polyacrylate polyurethane;

[0036] Preferably, the perovskite-type oxide solid electrolyte is selected from lithium lanthanum titanium oxide;

[0037] The garnet-type oxide solid electrolyte is selected from one or more of lithium lanthanum zirconium oxide, niobium-doped lithium lanthanum zirconium oxide, tantalum-doped lithium lanthanum zirconium oxide, and niobium-tantalum co-doped lithium lanthanum zirconium oxide;

[0038] The NASICON type oxide solid electrolyte is selected from one or more of lithium titanium aluminum phosphate, lithium yttrium titanium phosphate, and lithium germanium aluminum phosphate.

[0039] According to the pole piece described above, the binder is selected from one or more of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium hydroxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-butadiene-styrene copolymer, polyacrylic acid, and lithium polyacrylate;

[0040] Preferably, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide) and lithium difluorooxalatoborate.

[0041] The present invention provides a method for preparing a pole piece, which comprises the following steps:

[0042] Step S2: spraying a conductive slurry containing a composition of a nano-conductive agent and an organic polymer solid electrolyte onto the surface of the positive electrode sheet or the negative electrode sheet by ultrasonic spraying, and then optionally heating and curing it to obtain a positive electrode sheet or a negative electrode sheet with a mixed conductive layer.

[0043] According to the preparation method described above, the preparation method further comprises the following steps:

[0044] Step S4: spraying the slurry containing the inorganic ceramic material onto the surface of the mixed conductive layer obtained in step S2 by ultrasonic spraying, thereby obtaining a positive electrode sheet or a negative electrode sheet having the mixed conductive layer and the first composite solid electrolyte layer in sequence.

[0045] According to the preparation method described above, the preparation method further comprises the following steps:

[0046] Step S6: spraying the second solid electrolyte slurry onto the surface of the first composite solid electrolyte layer obtained in step S4 by ultrasonic spraying, thereby obtaining a positive electrode sheet or a negative electrode sheet having a mixed conductive layer, a first composite solid electrolyte layer and a second solid electrolyte layer in sequence.

[0047] According to the preparation method described above, the preparation method further comprises the following steps:

[0048] Step Sx: hot pressing the finally prepared positive electrode sheet or negative electrode sheet;

[0049] Preferably, the hot pressing temperature is 40-60° C., the pressure is 0.1-0.5 MPa, and the hot pressing time is 5-20 minutes.

[0050] According to the preparation method described above, the solid content of the conductive paste is 5 to 40% by mass;

[0051] Preferably, the solid content of the slurry containing the inorganic ceramic material is 5 to 30% by mass;

[0052] Preferably, the solid content of the second solid electrolyte slurry is 5 to 40% by mass.

[0053] According to the preparation method described above, in the conductive paste of step S2, the mass ratio of the nano-conductive agent to the organic polymer solid electrolyte is (85-20): (15-80), preferably (80-25): (20-75);

[0054] Preferably, the particle size of the nano-conductive agent is 5-500 nm, preferably 10-300 nm.

[0055] According to the preparation method described above, in the ultrasonic spraying in step S2, step S4 and step S6, the spraying conditions are as follows: ultrasonic power of 10-100 W, ultrasonic frequency of 20-200 kHz, continuous spraying rate of 0-3000 ml / h, preferably 800-1700 ml / h, spraying distance of 10-100 mm, air pressure of 0.1-0.3 MPa, spray width of 50-400 mm, spraying angle of 85-90°, and temperature of the positive electrode sheet or the negative electrode sheet of 30-80°C;

[0056] Preferably, the spraying conditions in step S2, step S4 and step S6 are the same or different.

[0057] According to the preparation method described above, in step S2, the temperature for heating and curing is 60-120°C, preferably 80-100°C.

[0058] According to the preparation method described above, the nano-conductive agent used in step S2 is selected from one or more of conductive graphite, conductive carbon black, acetylene black, carbon nanotubes, Ketjen black, graphene, carbon nanofibers and polyethylene dioxythiophene;

[0059] Preferably, the organic polymer solid electrolyte used in step S2 is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, polypentylene succinate, polyvinyl chloride, polyvinyl carbonate, polyvinyl pyrrolidone, polyimide, polystyrene sulfonic acid, polyacrylate, and polyurethane.

[0060] According to the preparation method described above, the slurry containing the inorganic ceramic material used in step S4 further contains an organic polymer solid electrolyte and a lithium salt;

[0061] The inorganic ceramic material used in step S4 is selected from one or more of nitrides, carbides, metal oxides, and non-metal oxides;

[0062] Preferably, the nitride is selected from one or more of silicon nitride, titanium nitride, aluminum nitride, boron nitride, and magnesium nitride; the carbide is selected from one or more of silicon carbide and boron carbide; the metal oxide is selected from one or more of aluminum oxide, titanium dioxide, zirconium dioxide, and magnesium oxide; the non-metal oxide is selected from one or more of silicon dioxide and boron oxide;

[0063] Preferably, the organic polymer solid electrolyte is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene, polyvinylidene fluoride - trichlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, poly(ethylene succinate), polyvinyl chloride, poly(vinylidene carbonate), polyvinylpyrrolidone, polyimide, polystyrene sulfonic acid, and polyacrylate;

[0064] Preferably, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium difluorooxalate borate

[0065] According to the preparation method described above, the second solid electrolyte used in step S6 is selected from one or more of inorganic solid electrolytes and organic polymer solid electrolytes;

[0066] Preferably, the inorganic solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, borate solid electrolytes, and nitride solid electrolytes;

[0067] Preferably, the oxide solid electrolyte is selected from one or more of perovskite - type oxide solid electrolytes, garnet - type oxide solid electrolytes, and NASICON - type oxide solid electrolytes;

[0068] The sulfide solid electrolyte is selected from one or more of lithium germanium phosphorus sulfur, lithium phosphorus sulfur chlorine, lithium silicon phosphorus sulfur chlorine, lithium phosphorus sulfur bromine, lithium phosphorus sulfur iodine, lithium thiophosphate, and vitreous sulfide;

[0069] The halide solid electrolyte is selected from Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1), Li2XCl4 (X is selected from Cd and / or Mg), Li2X′I4 (X′ is selected from Cd and / or Zn), LiMCl5X″ (M is selected from one or more of La, Ta, Nb, and X″ is selected from O, Cl, F, or OH), Li 3-yZr y M′ 1-y Cl6 (M′ is one or more selected from Y, Er, Yb, Ho, Lu, 0 < y < 1);

[0070] The borate solid electrolyte is one or more selected from Li2B4O7, Li2O - B2O3 - P2O5;

[0071] The nitride solid electrolyte is one or more selected from LiPON, Li3N, Li7PN4, LiSi2N3;

[0072] The organic polymer solid electrolyte is one or more selected from polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene, polyvinylidene fluoride - chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, poly(ethylene succinate), polyvinyl chloride, poly(vinylidene carbonate), polyvinylpyrrolidone, polyimide, polystyrene sulfonic acid, and polyacrylate;

[0073] Preferably, the perovskite - type oxide solid electrolyte is selected from lithium lanthanum titanium oxide;

[0074] The garnet - type oxide solid electrolyte is one or more selected from lithium lanthanum zirconium oxide, niobium - doped lithium lanthanum zirconium oxide, tantalum - doped lithium lanthanum zirconium oxide, niobium - tantalum co - doped lithium lanthanum zirconium oxide;

[0075] The NASICON - type oxide solid electrolyte is one or more selected from lithium aluminum titanium phosphate, lithium yttrium titanium phosphate, lithium germanium aluminum phosphate.

[0076] According to the preparation method described above, the slurry in step S2 further includes a binder;

[0077] Preferably, the slurry in step S6 further includes a lithium salt and / or a binder.

[0078] According to the preparation method described above, the binder is one or more selected from polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene - butadiene rubber, nitrile rubber, styrene - butadiene - styrene copolymer, polyacrylic acid, lithium polyacrylate;

[0079] The lithium salt is one or more selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium difluorooxalate borate;

[0080] Preferably, the binders used in the slurry in step S2 and the slurry in step S6 are the same or different from each other.

[0081] The present invention also provides a solid-state battery, which includes the above-mentioned electrode sheet or the positive electrode sheet or negative electrode sheet obtained by the above-mentioned preparation method.

[0082] The present invention further provides a method for preparing a solid-state battery, which comprises the steps of preparing a positive electrode sheet or a negative electrode sheet by the above-mentioned preparation method.

[0083] According to the preparation method described above, it also includes the steps of rolling and drying the positive electrode sheet and / or the negative electrode sheet, and then hot pressing and integrating them.

[0084] According to the preparation method described above, in the hot pressing integration, the hot pressing temperature is 50-85° C., the pressure is 0.2-0.9 MPa, and the hot pressing time is 20-40 minutes.

[0085] Effects of the Invention

[0086] The above technical solution of the present invention has the following beneficial effects:

[0087] 1. A mixed conductive layer comprising a nano-conductive agent and an organic polymer solid electrolyte is introduced on the surface of the positive and negative electrode sheets. The nano-conductive agent can effectively increase the contact area between the positive and negative electrode active materials, and the organic polymer solid electrolyte can effectively reduce the interfacial impedance.

[0088] 2. The present invention utilizes an ultrasonic spraying method to prepare the pole piece, which can fully refine the slurry particles, improve the stability of the coating, and realize a uniform layered structure with controllable thickness, thereby improving the structural stability of the solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] FIG1 is a scanning electron microscope representation of the composite solid-state battery electrode obtained in Example 1. DETAILED DESCRIPTION

[0090] The following describes embodiments of the present invention, but the present invention is not limited thereto. The present invention is not limited to the various configurations described below; various modifications may be made within the scope of the invention claims, and embodiments obtained by appropriately combining different embodiments and appropriately combining the technical means disclosed in the examples are also included in the technical scope of the present invention. In addition, all documents listed in this specification are cited as references in this specification.

[0091] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0092] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0093] In this specification, unless otherwise specified, "multiple" in "multiple", "multiple", "many" and the like means a numerical value of 2 or more.

[0094] In this specification, the term “substantially”, “generally” or “essentially” means that the error is less than 5%, or less than 3%, or less than 1% compared with the relevant perfect standard or theoretical standard.

[0095] In this specification, unless otherwise specified, "%" means percentage by mass.

[0096] In this specification, when "room temperature" or "normal temperature" appears, the temperature may generally be 10-37°C, or 15-35°C.

[0097] In this specification, the meanings of “may” or “can” include both existence and non-existence, and both performing a certain process and not performing a certain process.

[0098] Throughout this specification, “optionally,” “optionally,” and “optionally” mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

[0099] The term "comprises" and any variations thereof in the specification and claims of the present invention and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0100] In this specification, references to "some / certain / preferred embodiments," "embodiments," etc., mean that the specific elements (e.g., features, structures, properties, and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it should be understood that the elements may be combined in any suitable manner in various embodiments.

[0101] <First Aspect>

[0102] A first aspect of the present invention relates to a pole piece, comprising a mixed conductive layer on a positive pole piece or a negative pole piece, wherein the mixed conductive layer comprises a nano-conductive agent and an organic polymer solid electrolyte.

[0103] In this invention, a mixed conductive layer consisting of a nano-conductive agent and an organic polymer solid electrolyte is introduced onto the surface of the positive or negative electrode. The nano-conductive agent effectively increases the contact area between the mixed conductive layer and the positive or negative electrode, while the organic polymer solid electrolyte in the mixed conductive layer effectively reduces interfacial impedance, thereby improving the cycling stability of the solid-state battery.

[0104] In some preferred embodiments of the present invention, the mass ratio of the nano-conductive agent to the organic polymer solid electrolyte is (85-20): (15-80), preferably (80-25): (20-75), for example, 85:15, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, 25:75, 20:80, etc. The mass ratio of the nano-conductive agent to the organic polymer solid electrolyte within the above range is beneficial for improving the dispersion of the conductive particles and the uniformity of the entire slurry during preparation, and can improve the close contact with the positive or negative electrode interface; if the ratio of the nano-conductive agent is too high, the particles are likely to agglomerate, which is not conducive to dispersion and affects the uniformity of the mixed conductive layer prepared by ultrasonic spraying, affecting the cycle stability of the battery.

[0105] In some preferred embodiments of the present invention, the particle size of the nano-conductive agent may be 5-500 nm, preferably 10-300 nm, for example, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 50 nm, 75 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, etc. Nano-scale conductive agents can effectively increase the contact area with the positive electrode active material or the negative electrode active material, solve the problem of poor interfacial contact between the active material and the solid electrolyte, and reduce interfacial impedance.

[0106] In the present invention, the nano-conductive agent used for the mixed conductive layer can be selected from one or more of conductive graphite, conductive carbon black, acetylene black, carbon nanotubes, Ketjen black, graphene, carbon nanofibers and polyethylene dioxythiophene.

[0107] In the present invention, the organic polymer solid electrolyte used for the mixed conductive layer can be selected from one or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride-chlorotrifluoroethylene (PVDF-CTFE), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polypropylene carbonate (PPC), polyphenylene sulfide (PPS), polyethyl cyanoacrylate (PCA), polypentylene succinate, polyvinyl chloride (PVC), polyvinyl carbonate, polyvinyl pyrrolidone (PVP), polyimide (PI), polystyrene sulfonic acid and polyacrylate, polyurethane.

[0108] In some preferred embodiments of the present invention, the thickness of the mixed conductive layer may be 100 nm-1000 nm, preferably 150-800 nm, for example, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, etc. The thickness of the mixed conductive layer within the above range can effectively increase the structural stability of the solid-state battery electrode.

[0109] In some preferred embodiments of the present invention, the mixed conductive layer further comprises a binder. The present invention does not particularly limit the binder, and any binder commonly used in the art may be used. For example, the binder may be selected from one or more of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium hydroxymethyl cellulose, styrene-butadiene rubber, nitrile-butadiene rubber, styrene-butadiene-styrene copolymer, polyacrylic acid, and lithium polyacrylate.

[0110] The content of the binder is not particularly limited and can be adjusted according to actual needs. For example, it can be 1-10% by mass of the mixed conductive layer.

[0111] It should be noted that the mixed conductive layer of the present invention preferably does not contain an inorganic solid electrolyte. This is because the inorganic solid electrolyte has a large particle size, usually in the micron level, which may have an adverse effect on the electrode of the present invention.

[0112] In some preferred embodiments of the present invention, the electrode further comprises a first composite solid electrolyte layer on the mixed conductive layer, wherein the first composite solid electrolyte layer comprises an inorganic ceramic material, an organic polymer solid electrolyte, and a lithium salt.

[0113] Introducing a first composite solid electrolyte layer onto the mixed conductive layer can fill interfacial gaps in solid-state batteries, improve interfacial contact between layers, reduce interfacial impedance, increase the transfer rate of lithium ions across the interface, prevent the occurrence of interfacial side reactions, and enhance the battery's cycling and thermal stability. Furthermore, the first composite solid electrolyte layer increases the solid-solid contact area, providing a transport channel for lithium ions.

[0114] In some preferred embodiments of the present invention, the thickness of the first composite solid electrolyte layer is 200-3000 nm, preferably 250-2000 nm, for example, 200 nm, 250 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm, etc. A thickness of the first composite solid electrolyte layer within the above range can effectively enhance ion conduction at the interface and improve interface stability. A thickness that is too high can increase interfacial impedance and affect the rate performance of the battery.

[0115] In the present invention, the inorganic ceramic material used for the first composite solid electrolyte layer can be selected from one or more of nitrides, carbides, metal oxides, and non-metal oxides.

[0116] Specifically, the nitride may be selected from one or more of silicon nitride (Si3N4), titanium nitride (TiN), aluminum nitride (AlN), boron nitride (BN), and magnesium nitride (Mg3N2). The carbide may be selected from one or more of silicon carbide (SiC) and boron carbide (B4C); the metal oxide may be selected from one or more of aluminum oxide (Al2O3), titanium dioxide (TiO2), zirconium dioxide (ZrO2), and magnesium oxide (MgO). The non-metallic oxide may be selected from one or more of silicon dioxide (SiO2) and boron oxide (B2O3).

[0117] The organic polymer solid electrolyte used for the first composite solid electrolyte layer can be selected from one or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride-chlorotrifluoroethylene (PVDF-CTFE), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polypropylene carbonate (PPC), polyphenylene sulfide (PPS), polyethyl cyanoacrylate (PCA), polypentylene succinate, polyvinyl chloride (PVC), polyvinyl carbonate, polyvinyl pyrrolidone (PVP), polyimide (PI), polystyrene sulfonic acid, polyacrylate, and polyurethane.

[0118] The lithium salt used for the first composite solid electrolyte layer may be selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium bisfluorosulfonyl imide, and lithium difluorooxalatoborate.

[0119] In some preferred embodiments of the present invention, the pole piece further includes a second solid electrolyte layer on the first composite solid electrolyte layer.

[0120] In some preferred embodiments of the present invention, the thickness of the second solid electrolyte layer is 2 μm-50 μm, preferably 5 μm-40 μm, for example, 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc. A thickness of the second solid electrolyte layer within the above range can improve the cycle stability of the solid-state battery and increase the safety of the battery. A thickness that is too low can easily cause a short circuit, which is not conducive to improving the cycle stability of the battery.

[0121] In some preferred embodiments of the present invention, the second solid electrolyte used in the second solid electrolyte layer includes one or more of an inorganic solid electrolyte and an organic polymer solid electrolyte.

[0122] Specifically, the inorganic solid electrolyte can be selected from one or more of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, a borate solid electrolyte, and a nitride solid electrolyte.

[0123] More specifically, the oxide solid electrolyte can be selected from one or more of a perovskite oxide solid electrolyte, a garnet oxide solid electrolyte, and a NASICON oxide solid electrolyte. Preferably, the perovskite oxide solid electrolyte can be selected from lithium lanthanum titanium oxide; the garnet oxide solid electrolyte can be selected from one or more of lithium lanthanum zirconium oxide, niobium-doped lithium lanthanum zirconium oxide, tantalum-doped lithium lanthanum zirconium oxide, and niobium-tantalum dual-doped lithium lanthanum zirconium oxide; and the NASICON oxide solid electrolyte can be selected from one or more of lithium aluminum titanium phosphate, lithium yttrium titanium phosphate, and lithium aluminum germanium phosphate.

[0124] The sulfide solid electrolyte can be selected from one or more of lithium germanium phosphosulfur (LGPS), lithium phosphorus sulfur chloride (LPSCl), lithium silicon phosphorus sulfur chloride, lithium phosphorus sulfur bromine, lithium phosphorus sulfur iodide, lithium thiophosphate (LPS), and glassy sulfide (Li2S-P2S5, Li2S-SiS2, Li2S-B2S3). The halide solid electrolyte can be selected from one or more of Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x(where 0 < x < 1), Li2XCl4 (X is selected from Cd and / or Mg), Li2X′I4 (X′ is selected from Cd and / or Zn), LiMCl5X″ (M is selected from one or more of La, Ta, Nb, and X″ is selected from O, Cl, F, or OH), Li 3-y Zr y M′ 1-y Cl6 (M′ is selected from one or more of Y, Er, Yb, Ho, Lu, 0 < y < 1). The borate solid electrolyte can be selected from one or more of Li2B4O7, Li2O - B2O3 - P2O5. The nitride solid electrolyte can be selected from one or more of LiPON, Li3N, Li7PN4, LiSi2N3.

[0125] In the present invention, the organic polymer solid electrolyte can be selected from one or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyvinylidene fluoride - hexafluoropropylene (PVDF - HFP), polyvinylidene fluoride - chlorotrifluoroethylene (PVDF - CTFE), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polypropylene carbonate (PPC), polyphenylene sulfide (PPS), polyethyl cyanoacrylate (PCA), poly(ethylene succinate), polyvinyl chloride (PVC), poly(vinylidene carbonate), polyvinylpyrrolidone (PVP), polyimide (PI), polystyrenesulfonic acid, polyacrylate, polyurethane.

[0126] In some preferred embodiments of the present invention, the second solid electrolyte layer further comprises a lithium salt and / or a binder. In the present invention, there is no particular limitation on the lithium salt and the binder, and those commonly used in the art can be used. Examples of the lithium salt can be the same as those listed above for the first composite solid electrolyte layer. Examples of the binder can be the same as those listed above for the mixed conductive layer.

[0127] In a specific embodiment, the lithium salt optionally used for the second solid electrolyte layer and the lithium salt used for the first composite solid electrolyte layer can be the same or different; the binder optionally used for the second solid electrolyte layer and the binder optionally used for the mixed conductive layer can be the same or different.

[0128] There is no particular limitation on the content of the lithium salt and the binder when present in the second solid electrolyte layer, and it can be adjusted according to actual needs. For example, they can each be 1 - 20% by mass of the second solid electrolyte layer.

[0129] <Second aspect>

[0130] The second aspect of the present invention relates to a method for preparing the electrode sheet described in <First aspect>, which comprises the following steps:

[0131] Step S2: spraying a conductive slurry containing a composition of a nano-conductive agent and an organic polymer solid electrolyte onto the surface of the positive electrode sheet or the negative electrode sheet by ultrasonic spraying, and then optionally heating and curing it to obtain a positive electrode sheet or a negative electrode sheet with a mixed conductive layer.

[0132] In some preferred embodiments of the present invention, the preparation method further comprises the following steps:

[0133] Step S4: spraying the slurry containing the inorganic ceramic material onto the surface of the mixed conductive layer obtained in step S2 by ultrasonic spraying, thereby obtaining a positive electrode sheet or a negative electrode sheet having the mixed conductive layer and the first composite solid electrolyte layer in sequence.

[0134] In some preferred embodiments of the present invention, the preparation method further comprises the following steps:

[0135] Step S6: spraying the second solid electrolyte slurry onto the surface of the first composite solid electrolyte layer obtained in step S4 by ultrasonic spraying, thereby obtaining a positive electrode sheet or a negative electrode sheet having a mixed conductive layer, a first composite solid electrolyte layer and a second solid electrolyte layer in sequence.

[0136] In addition, in some specific embodiments of the present invention, the preparation method may further include the following slurry preparation steps:

[0137] Step S1: homogenizing a composition containing a nano-conductive agent and an organic polymer solid electrolyte in a solvent to prepare a conductive paste; and / or

[0138] Step S3: homogenizing the composition containing the inorganic ceramic material in a solvent to prepare a slurry containing the inorganic ceramic material; and / or

[0139] Step S5: slurrying the composition containing the second solid electrolyte in a solvent to prepare a second solid electrolyte slurry.

[0140] In some preferred embodiments, the preparation method of the present invention may further include step Sx: hot pressing the finally prepared positive electrode sheet or negative electrode sheet.

[0141] In the present invention, there is no particular limitation on the method for preparing the positive electrode sheet or the negative electrode sheet before spraying the conductive slurry, and the positive electrode sheet can be prepared using common methods in the art such as conventional coating method, electrostatic spraying method, etc.

[0142] There are no particular limitations on the positive electrode active material or negative electrode active material used in the positive electrode sheet or negative electrode sheet, and those commonly used in the art can be used. Preferably, the positive electrode active material of the present invention includes, but is not limited to, one or more combinations of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and lithium vanadium phosphate.

[0143] Preferably, the negative electrode active material described in the present invention includes but is not limited to one or more of graphite, graphene, carbon nanotubes, silicon-based alloys, silicon-oxygen negative electrodes, silicon-carbon negative electrodes, lithium metal negative electrodes, lithium alloy negative electrodes, lithium titanium oxides, transition metal oxides and transition metal sulfides.

[0144] The following describes each step in detail.

[0145] Step S1

[0146] In step S1 , a composition containing a nano-conductive agent and an organic polymer solid electrolyte is slurried in a solvent to prepare a conductive paste.

[0147] Examples of the nano-conductive agent and the organic polymer solid electrolyte used in step S1 are the same as those listed in the above <First Aspect>, and are not described in detail here.

[0148] In the present invention, the solid content of the conductive paste may be 5 to 40% by mass, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% by mass, etc.

[0149] In the conductive slurry of step S1, the mass ratio of the nano-conductive agent to the organic polymer solid electrolyte is (85-20): (15-80), preferably (80-25): (20-75), for example, it can be 85:15, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, 25:75, 20:80, etc. The mass ratio of the nano-conductive agent to the organic polymer solid electrolyte within the above range is beneficial to improving the dispersion of the conductive particles and the uniformity of the entire slurry during preparation, and can improve the close contact with the positive electrode interface; if the ratio of the nano-conductive agent is too high, the particles will agglomerate, which is not conducive to dispersion and affects the uniformity of the mixed conductive layer prepared by ultrasonic spraying, affecting the cycle stability of the battery.

[0150] In step S1, the organic solvent used for homogenization can be selected from one or more of N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide, butyrate, toluene, xylene, anisole, hexane, heptane, dibromomethane, dichloroethane, ethanol and glycol ether.

[0151] In some preferred embodiments, the composition containing the nano-conductive agent and the organic polymer solid electrolyte in step S1 further comprises a binder, examples of which are the same as those listed in the above <First Aspect>.

[0152] Step S2

[0153] In step S2, the conductive slurry prepared in step S1 is sprayed onto the surface of the positive electrode sheet or the negative electrode sheet by ultrasonic spraying, and then optionally heated and cured to obtain a positive electrode sheet or a negative electrode sheet with a mixed conductive layer.

[0154] In the present invention, in the ultrasonic spraying of step S2, the spraying conditions are as follows:

[0155] The ultrasonic power is 10-100W, for example, 10W, 20W, 30W, 40W, 50W, 60W, 70W, 80W, 90W, 100W, etc.

[0156] The ultrasonic frequency is 20-200 kHz, for example, 20 kHz, 30 kHz, 40 kHz, 50 kHz, 80 kHz, 100 kHz, 120 kHz, 150 kHz, 200 kHz, etc.

[0157] The continuous spraying rate is 0-3000ml / h (greater than 0ml / h and less than 3000ml / h), preferably 100-1700ml / h, more preferably 200-1200ml / h, for example, 10ml / h, 50ml / h, 100ml / h, 200ml / h, 300ml / h, 400ml / h, 500ml / h, 600ml / h, 800ml / h, 1000ml / h, 1100ml / h, 1200ml / h, 1300ml / h, 1400ml / h, etc. 00ml / h, 1500ml / h, 1600ml / h, 1700ml / h, 1800ml / h, 2000ml / h, 2500ml / h, 3000ml / h, etc. When the spraying amount is within the above range, the slurry particles can be refined and the slurry can be evenly sprayed on the surface of the battery electrode, which is beneficial to control the thickness of the obtained solid electrolyte layer and achieve close contact between layers, avoiding the problem of electrolyte particles agglomerating due to excessive spraying speed, causing clogging of equipment and waste of slurry, thereby improving the efficiency of preparing solid-state battery electrodes;

[0158] The spraying distance is 10-100mm, for example, it can be 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, etc.

[0159] The air guide pressure is 0.1-0.3MPa, for example, 0.1MPa, 0.15MPa, 0.2MPa, 0.25MPa, 0.3MPa, etc., so as to prevent material splashing;

[0160] The spray width is 50-400 mm, for example, it can be 50 mm, 80 mm, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, etc.

[0161] The spraying distance is 20 to 100 mm, for example, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, etc.

[0162] The spraying angle is 85-90°, for example, 85°, 86°, 87°, 88°, 89°, 90°, etc.

[0163] In some preferred embodiments of the present invention, the positive or negative electrode sheet can be heated during spraying. The heating temperature can be 30-80°C, for example, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, etc. By heating the electrode sheet, the slurry can be evenly distributed on the electrode sheet surface, reducing particle agglomeration during the mixing process and improving the battery's cycling stability.

[0164] In some specific embodiments, heat curing is optionally performed after spraying. Heat curing is preferred to further stabilize the interface between the mixed conductive layer and the electrode, thereby reducing interfacial impedance. The heat curing temperature is 70°C to 120°C, for example, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, etc.

[0165] In some embodiments, the positive electrode sheet or the negative electrode sheet is placed on a work plate during spraying. Thus, both heating the positive electrode sheet or the negative electrode sheet and drying the sheet after spraying can be accomplished on the work plate, thereby reducing the process flow and enabling mass production.

[0166] In some specific embodiments, when spraying the slurry, the positive electrode sheet or the negative electrode sheet is placed on a working plate, then heated and the spraying conditions are set, the slurry is sprayed onto the surface of the sheet to the desired thickness, and the static coating equipment is turned off after standing for a period of time, and then dried and naturally cooled to obtain a positive electrode sheet or a negative electrode sheet with a mixed conductive layer.

[0167] In some embodiments, during the standing period, the temperature of the working plate may be raised to a temperature slightly higher than the heating temperature during spraying, for example, 10 to 30° C. higher. The standing period may be, for example, 20 to 120 minutes.

[0168] Step S3

[0169] In some preferred embodiments of the present invention, the method for preparing a pole piece may further include step S3: homogenizing the composition containing the inorganic ceramic material in a solvent to prepare a slurry containing the inorganic ceramic material.

[0170] In the present invention, the composition containing the inorganic ceramic material further comprises an organic polymer solid electrolyte and a lithium salt.

[0171] Examples of the inorganic ceramic material, organic polymer solid electrolyte and lithium salt used in step S3 are the same as those listed in the above <First Aspect>, and are not described again here.

[0172] In the present invention, the solid content of the slurry containing the inorganic ceramic material may be 5 to 30% by mass, for example, 5%, 10%, 15%, 20%, 25%, 30% by mass, etc.

[0173] In step S3, examples of the organic solvent used in the homogenization are the same as those in step S1. In a specific embodiment, the organic solvent used in step S3 can be the same as or different from that in step S1.

[0174] Step S4

[0175] In step S4, the slurry containing the inorganic ceramic material prepared in step S3 is sprayed onto the surface of the mixed conductive layer obtained in step S2 by ultrasonic spraying, thereby obtaining a positive electrode sheet or a negative electrode sheet having a mixed conductive layer and a first composite solid electrolyte layer in sequence.

[0176] The range of each condition of ultrasonic spraying in step S4 is the same as that in step S2 above, and will not be repeated here. In a specific embodiment, the conditions of ultrasonic spraying adopted in step S4 can be the same as or different from those in step S2.

[0177] Step S5

[0178] In some preferred embodiments of the present invention, the method for preparing a pole piece may further include step S5: slurrying the composition containing the second solid electrolyte in a solvent to prepare a second solid electrolyte slurry.

[0179] In the present invention, there is no particular limitation on the second solid electrolyte, and those commonly used in the art can be used.

[0180] In some embodiments of the present invention, the second solid electrolyte may be selected from one or more of an inorganic solid electrolyte and an organic polymer solid electrolyte. Examples of the inorganic solid electrolyte and the organic polymer solid electrolyte are the same as those listed in the first aspect above.

[0181] In step S5, examples of the organic solvent used in homogenization are the same as those in step S1. In a specific embodiment, the organic solvent used in step S5 can be the same as or different from those in step S1 and step S3.

[0182] In the present invention, the solid content of the second solid electrolyte slurry may be 5 to 40% by mass, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% by mass, etc.

[0183] In some preferred embodiments, the composition containing the second solid electrolyte in step S5 further contains a lithium salt and / or a binder.

[0184] There is no particular limitation on the lithium salt, and those commonly used in the art can be used. In some embodiments of the present invention, the lithium salt can be selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), and lithium difluorooxalatoborate. Examples of the binder are the same as those listed in the first aspect above, and in specific embodiments, the binder used in step S5 can be the same as or different from that in step S1.

[0185] Step S6

[0186] In step S6, the second solid electrolyte slurry prepared in step S5 is sprayed onto the surface of the first composite solid electrolyte layer obtained in step S4 by ultrasonic spraying, thereby obtaining a positive electrode sheet or a negative electrode sheet having a mixed conductive layer, a first composite solid electrolyte layer and a second solid electrolyte layer in sequence.

[0187] The range of each condition of ultrasonic spraying in step S6 is the same as that in step S2 above, and will not be repeated here. In a specific embodiment, the conditions of ultrasonic spraying adopted in step S6 can be the same as or different from those in step S2 and step S4.

[0188] In the preparation method of the present invention, a mixed conductive layer is introduced on the surface of the positive active material and the negative active material by ultrasonic spraying, thereby increasing the interface contact between the active material and the solid electrolyte and reducing the interface impedance. In addition, a multi-layer solid electrolyte layer can be introduced on the positive electrode sheet or the negative electrode sheet by ultrasonic spraying, thereby preparing a sheet with uniform coating thickness and uniform and stable interlayer structure, and can effectively increase the structural stability of the solid-state battery sheet and improve the cycle stability of the solid-state battery.

[0189] Step Sx

[0190] In some preferred embodiments, the preparation method of the present invention may further include step Sx: hot pressing the finally prepared positive electrode sheet or negative electrode sheet.

[0191] In the hot pressing of the present invention, the temperature is 40-60°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, etc., the pressure can be 0.1-0.5 MPa, for example, 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, etc., and the hot pressing time can be 5-20 minutes, for example, 5 minutes, 10 minutes, 15 minutes, 20 minutes, etc.

[0192] During the hot pressing process, the interface contact between the positive electrode sheet or the negative electrode sheet, the mixed conductive layer, and the optional first composite solid electrolyte layer and the second solid electrolyte layer is increased, the crystallization area of ​​the polymer is reduced, ion transport behavior is induced and a new ion transport interface is formed, the electrochemical stability window of the solid electrolyte is improved, the ionic conductivity between the multilayer structure is improved, and the compatibility of the electrode and solid electrolyte interface is increased.

[0193] <Third Aspect>

[0194] The third aspect of the present invention relates to a solid-state battery, which includes the pole piece in the above <first aspect> or the pole piece obtained by the preparation method described in the above <second aspect>.

[0195] <Fourth Aspect>

[0196] The fourth aspect of the present invention relates to a method for preparing a solid-state battery, comprising: preparing a positive electrode sheet and / or a negative electrode sheet by the preparation method described in the above <second aspect>; and

[0197] The positive electrode sheets and / or negative electrode sheets are rolled, dried, and then hot-pressed to form an integrated whole.

[0198] The "hot pressing integration" here refers to integrating the positive and negative electrode sheets by hot pressing. The "hot pressing" in the above step Sx refers to hot pressing the positive electrode sheet or the negative electrode sheet.

[0199] In the hot pressing integration of the present invention, the hot pressing temperature is 50 to 85°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, etc., the pressure can be 0.2 to 0.9 MPa, for example, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, etc., and the hot pressing time can be 20 to 40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.

[0200] Example

[0201] The present invention will be described in detail below by way of examples. The examples of the examples are intended to explain the present invention and are not to be construed as limiting the present invention. Where specific techniques or conditions are not specified in the examples, the methods were performed according to the techniques or conditions described in the literature in the art or according to the product specifications. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be obtained commercially.

[0202] Example 1

[0203] The present invention provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. Ultrasonic spraying is used to introduce an ultrathin mixed conductive layer on the surface of the positive electrode active material and the negative electrode active material, thereby increasing the interface contact between the active material and the solid electrolyte and reducing the interface impedance. In addition, a multi-layer solid electrolyte layer is introduced on the positive electrode piece or the negative electrode piece to improve the cycle stability of the solid-state battery. The specific steps are as follows:

[0204] (1) Nano-scale conductive carbon black (particle size 200 nm) and polyimide were mixed uniformly in a ratio of 70%:30% by mass, dissolved in DMF solvent and stirred thoroughly, and a binder of polyvinylidene fluoride was added to prepare a slurry with a solid content of 35% by mass;

[0205] (2) The slurry was introduced onto the surface and gaps of the positive active material by ultrasonic spraying on the surface of the lithium iron phosphate positive electrode sheet (purchased from Aladdin L-68230, the same below), wherein the ultrasonic power was 40W, the ultrasonic frequency was controlled at 100kHz, the spray width was 50mm, the spray angle was 88°, the continuous spraying amount was controlled at 500ml / h, the spraying distance was 35mm, and the air pressure was controlled at 0.2MPa to obtain a mixed conductive layer with a thickness of 1μm, which was then heated and cured at 60°C for 1 hour;

[0206] (3) Boron nitride, polyvinylidene fluoride, and LiTFSI were dissolved in DMF solvent in a mass ratio of 5:3:2 and stirred thoroughly to prepare a slurry with a solid content of 55% by mass, which was sprayed on the surface of the mixed conductive layer by ultrasonic spraying, wherein the ultrasonic power was 40 W, the ultrasonic frequency was controlled at 80 kHz, the spray width was 50 mm, the spray angle was 88°, the continuous spraying amount was controlled at 500 ml / h, the spraying distance was 35 mm, and the gas pressure was controlled at 0.1 MPa to obtain a first composite solid electrolyte layer with a thickness of 2 μm;

[0207] (4) Tantalum-doped lithium lanthanum zirconium oxide, polypentanediol succinate, and LiTFSI were mixed and stirred in DMF in a mass ratio of 7:2:1 to prepare a slurry with a solid content of 40% by mass, which was sprayed on the surface of the first composite solid electrolyte layer by ultrasonic spraying, wherein the ultrasonic frequency was controlled at 90 kHz, the continuous spraying amount was controlled at 800 ml / h, the spraying distance was 35 mm, and the air guide pressure was controlled at 0.2 MPa to obtain a composite electrode containing a second solid electrolyte, the thickness of the second solid electrolyte layer was 30 μm, and the slurry was heated and cured at 60°C for 1 hour;

[0208] (5) The composite battery positive electrode sheet and the lithium metal negative electrode stack obtained in the above steps are assembled into a solid-state battery by hot pressing at a temperature of 65°C and a pressure of 0.4 MPa.

[0209] Example 2

[0210] The present invention provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. A multi-layer solid electrolyte is introduced on the pole piece by ultrasonic spraying. The specific steps are as follows:

[0211] (1) Nano-scale conductive carbon black (particle size 200 nm) and PVDF-HFP were mixed uniformly in a ratio of 60%:40% by mass, dissolved in DMF solvent and stirred thoroughly, and a binder of polyvinylidene fluoride was added to prepare a slurry with a solid content of 35% by mass;

[0212] (2) The slurry was introduced onto the surface and gaps of the positive active material by ultrasonic spraying on the surface of the lithium iron phosphate positive electrode sheet, wherein the ultrasonic power was 60W, the ultrasonic frequency was controlled at 110kHz, the spray width was 50mm, the spray angle was 88°, the continuous spraying amount was controlled at 500ml / h, the spraying distance was 30mm, and the air pressure was controlled at 0.2MPa to obtain a mixed conductive layer with a thickness of 1μm, and heated and cured at 60°C for 1 hour;

[0213] (3) Boron oxide, polyvinylidene fluoride, and LiTFSI were dissolved in DMF solvent in a mass ratio of 3:5:2 and stirred thoroughly to prepare a slurry with a solid content of 60% by mass, which was sprayed on the surface of the mixed conductive layer by ultrasonic spraying, wherein the ultrasonic frequency was controlled at 80 kHz, the continuous spraying amount was controlled at 500 ml / h, the spraying distance was 35 mm, and the gas pressure was controlled at 0.1 MPa to obtain a first composite solid electrolyte layer with a thickness of 2 μm;

[0214] (4) Tantalum-doped lithium lanthanum zirconium oxide, polypentanediol succinate, and LiTFSI were mixed and stirred in DMF in a mass ratio of 7:2:1 to prepare a slurry with a solid content of 40% by mass, and the slurry was sprayed on the surface of the first composite solid electrolyte layer by ultrasonic spraying, wherein the ultrasonic power was 60W, the ultrasonic frequency was controlled at 80kHz, the spray width was 50mm, the spray angle was 90°, the continuous spraying amount was controlled at 800ml / h, the spraying distance was 35mm, and the air guide pressure was controlled at 0.2MPa to obtain a composite electrode containing a second solid electrolyte, the thickness of the second solid electrolyte layer was 30μm, and the composite electrode was heated and cured at 60°C for 1 hour;

[0215] (5) The composite battery positive electrode sheet and the lithium metal negative electrode stack obtained in the above steps are assembled into a solid-state battery by hot pressing at a temperature of 65°C and a pressure of 0.4 MPa.

[0216] Example 3

[0217] The present invention provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. A multi-layer solid electrolyte is introduced on the pole piece by ultrasonic spraying. The specific steps are as follows:

[0218] (1) Carbon nanotubes (particle size 100 nm) and polyimide were mixed uniformly in a ratio of 60%:40% by mass, dissolved in DMF solvent and stirred thoroughly, and a binder of polyvinylidene fluoride was added to prepare a slurry with a solid content of 35% by mass;

[0219] (2) The slurry was introduced onto the surface and gaps of the positive active material by ultrasonic spraying on the surface of the lithium iron phosphate positive electrode sheet, wherein the ultrasonic power was 60W, the ultrasonic frequency was controlled at 110kHz, the spray width was 50mm, the spray angle was 88°, the continuous spraying amount was controlled at 500ml / h, the spraying distance was 30mm, and the air pressure was controlled at 0.2MPa to obtain a mixed conductive layer with a thickness of 1μm, and heated and cured at 60°C for 1 hour;

[0220] (3) Boron oxide, polyvinylidene fluoride, and LiTFSI were dissolved in DMF solvent in a mass ratio of 5:3:2 and stirred thoroughly to prepare a slurry with a solid content of 50% by mass, which was sprayed on the surface of the mixed conductive layer by ultrasonic spraying, wherein the ultrasonic power was 60W, the ultrasonic frequency was controlled at 80kHz, the spray width was 50mm, the spray angle was 90°, the continuous spraying amount was controlled at 500ml / h, the spraying distance was 35mm, and the gas pressure was controlled at 0.1MPa to obtain a first composite solid electrolyte layer with a thickness of 2μm;

[0221] (4) Tantalum-doped lithium lanthanum zirconium oxide, polypentanediol succinate, and LiTFSI were mixed and stirred in DMF in a mass ratio of 7:2:1 to prepare a slurry with a solid content of 40% by mass, which was sprayed on the surface of the first composite solid electrolyte layer by ultrasonic spraying, wherein the ultrasonic frequency was controlled at 90 kHz, the continuous spraying amount was controlled at 800 ml / h, the spraying distance was 35 mm, and the air guide pressure was controlled at 0.2 MPa to obtain a composite electrode containing a second solid electrolyte, the thickness of the second solid electrolyte layer was 30 μm, and the slurry was heated and cured at 60°C for 1 hour;

[0222] (5) The composite battery positive electrode sheet and the lithium metal negative electrode stack obtained in the above steps are assembled into a solid-state battery by hot pressing at a temperature of 65°C and a pressure of 0.4 MPa.

[0223] Example 4

[0224] The present invention provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. A multi-layer solid electrolyte is introduced on the pole piece by ultrasonic spraying. The specific steps are as follows:

[0225] (1) Carbon nanotubes (particle size 100 nm) and PVDF-HFP were mixed uniformly in a mass percentage ratio of 65%:35%, dissolved in DMF solvent and stirred thoroughly, and a binder of polyvinylidene fluoride was added to prepare a slurry with a solid content of 35% by mass;

[0226] (2) The slurry was introduced onto the surface and gaps of the positive active material by ultrasonic spraying on the surface of the lithium iron phosphate positive electrode sheet, wherein the ultrasonic power was 70W, the ultrasonic frequency was controlled at 110kHz, the spray width was 50mm, the spray angle was 88°, the continuous spraying amount was controlled at 500ml / h, the spraying distance was 30mm, and the air pressure was controlled at 0.2MPa to obtain a mixed conductive layer with a thickness of 1μm, and heated and cured at 60°C for 1 hour;

[0227] (3) Boron oxide, polyvinylidene fluoride, and LiTFSI were dissolved in DMF solvent in a mass ratio of 5:3:2 and stirred thoroughly to prepare a slurry with a solid content of 40% by mass, which was sprayed on the surface of the mixed conductive layer by ultrasonic spraying, wherein the ultra-ultrasonic power was 60W, the ultrasonic frequency was controlled at 80kHz, the spray width was 50mm, the spray angle was 90°, the continuous spraying amount was controlled at 500ml / h, the spraying distance was 35mm, and the gas pressure was controlled at 0.1MPa to obtain a first composite solid electrolyte layer with a thickness of 2μm;

[0228] (4) Tantalum-doped lithium lanthanum zirconium oxide, polypentanediol succinate, and LiTFSI were mixed and stirred in DMF in a mass ratio of 7:2:1 to prepare a slurry with a solid content of 40% by mass, which was sprayed on the surface of the first composite solid electrolyte layer by ultrasonic spraying, wherein the ultrasonic frequency was controlled at 90 kHz, the continuous spraying amount was controlled at 800 ml / h, the spraying distance was 35 mm, and the air guide pressure was controlled at 0.2 MPa to obtain a composite electrode containing a second solid electrolyte, the thickness of the second solid electrolyte layer was 30 μm, and the slurry was heated and cured at 60°C for 1 hour;

[0229] (5) The composite battery positive electrode sheet and the lithium metal negative electrode stack obtained in the above steps are assembled into a solid-state battery by hot pressing at a temperature of 65°C and a pressure of 0.4 MPa.

[0230] Example 5

[0231] The present invention provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. A multi-layer solid electrolyte is introduced on the pole piece by ultrasonic spraying. The specific steps are as follows:

[0232] (1) Carbon nanotubes (particle size 100 nm) and PVDF-HFP were mixed uniformly in a mass percentage ratio of 65%:35%, dissolved in DMF solvent and stirred thoroughly, and a binder of polyvinylidene fluoride was added to prepare a slurry with a solid content of 35% by mass;

[0233] (2) The slurry was introduced onto the surface and gaps of the positive active material by ultrasonic spraying on the surface of the NCM622 (C-96500) positive electrode sheet, wherein the ultrasonic power was 30 W, the ultrasonic frequency was controlled at 110 kHz, the spray width was 50 mm, the spray angle was 87°, the continuous spraying amount was controlled at 500 ml / h, the spraying distance was 30 mm, and the air pressure was controlled at 0.2 MPa to obtain a mixed conductive layer with a thickness of 1 μm, which was then heated and cured at 60°C for 1 hour;

[0234] (3) Boron oxide, polyvinylidene fluoride, and LiTFSI were dissolved in DMF solvent in a mass ratio of 3:5:2 and stirred thoroughly to prepare a slurry with a solid content of 45% by mass, which was sprayed on the surface of the mixed conductive layer by ultrasonic spraying, wherein the ultrasonic power was 60 W, the ultrasonic frequency was controlled at 80 kHz, the spray width was 50 mm, the spray angle was 90°, the continuous spraying amount was controlled at 500 ml / h, the spraying distance was 35 mm, and the gas pressure was controlled at 0.1 MPa to obtain a first composite solid electrolyte layer with a thickness of 2 μm;

[0235] (4) Li7La3Zr2O 12The solid electrolyte, polypentane succinate, and LiTFSI were mixed and stirred in DMF in a mass ratio of 7:2:1 to prepare a slurry with a solid content of 40% by mass. The slurry was sprayed on the surface of the first composite solid electrolyte layer by ultrasonic spraying, wherein the ultrasonic frequency was controlled at 90 kHz, the continuous spraying amount was controlled at 800 ml / h, the spraying distance was 35 mm, and the air pressure was controlled at 0.2 MPa to obtain a composite electrode containing a second solid electrolyte. The thickness of the second solid electrolyte layer was 30 μm, and the slurry was heated and cured at 60°C for 1 hour.

[0236] (5) The composite battery positive electrode sheet and the lithium metal negative electrode stack obtained in the above steps are assembled into a solid-state battery by hot pressing at a temperature of 65°C and a pressure of 0.4 MPa.

[0237] Example 6

[0238] The present invention provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. A multi-layer solid electrolyte is introduced on the pole piece by ultrasonic spraying. The specific steps are as follows:

[0239] (1) Nano-scale conductive carbon black (particle size 200 nm) and PVDF-HFP were mixed uniformly in a ratio of 55%:45% by mass, dissolved in DMF solvent and stirred thoroughly, and a binder of polyvinylidene fluoride was added to prepare a slurry with a solid content of 35% by mass;

[0240] (2) The slurry was introduced onto the surface and gaps of the positive active material by ultrasonic spraying on the surface of the NCM622 (C-96500) positive electrode sheet, wherein the ultrasonic power was 60 W, the ultrasonic frequency was controlled at 110 kHz, the spray width was 50 mm, the spray angle was 87°, the continuous spraying amount was controlled at 500 ml / h, the spraying distance was 30 mm, and the air pressure was controlled at 0.2 MPa to obtain a mixed conductive layer with a thickness of 1 μm, which was then heated and cured at 60°C for 1 hour;

[0241] (3) Boron oxide, polyvinylidene fluoride, and LiTFSI were dissolved in DMF solvent in a mass ratio of 3:5:2 and stirred thoroughly to prepare a slurry with a solid content of 50% by mass, which was sprayed on the surface of the mixed conductive layer by ultrasonic spraying, wherein the ultrasonic power was 50 W, the ultrasonic frequency was controlled at 80 kHz, the spray width was 50 mm, the spray angle was 90°, the continuous spraying amount was controlled at 500 ml / h, the spraying distance was 35 mm, and the gas pressure was controlled at 0.1 MPa to obtain a first composite solid electrolyte layer with a thickness of 2 μm;

[0242] (4) Li7La3Zr2O 12The solid electrolyte, polypentane succinate, and LiTFSI were mixed and stirred in DMF in a mass ratio of 7:2:1 to prepare a slurry with a solid content of 40% by mass. The slurry was sprayed on the surface of the first composite solid electrolyte layer by ultrasonic spraying, wherein the ultrasonic frequency was controlled at 90 kHz, the continuous spraying amount was controlled at 800 ml / h, the spraying distance was 35 mm, and the air pressure was controlled at 0.2 MPa to obtain a composite electrode containing a second solid electrolyte. The thickness of the second solid electrolyte layer was 30 μm, and the slurry was heated and cured at 60°C for 1 hour.

[0243] (5) The composite battery positive electrode sheet and the lithium metal negative electrode stack obtained in the above steps are assembled into a solid-state battery by hot pressing at a temperature of 65°C and a pressure of 0.4 MPa.

[0244] Example 7

[0245] The present invention provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. A multi-layer solid electrolyte is introduced on the pole piece by ultrasonic spraying. The specific steps are as follows:

[0246] (1) Nano-conductive carbon black (particle size 200 nm) and styrene-butadiene rubber were mixed uniformly in a ratio of 85% by mass to 15% by mass, dissolved in DMF solvent and stirred thoroughly, and sodium hydroxymethyl cellulose was added to prepare a slurry with a solid content of 40% by mass;

[0247] (2) The slurry was introduced onto the surface and gaps of the negative electrode active material by ultrasonic spraying on the surface of the silicon-carbon negative electrode plate, wherein the ultrasonic power was 60 W, the ultrasonic frequency was controlled at 60 kHz, the spray width was 50 mm, the spray angle was 90°, the continuous spraying amount was controlled at 700 ml / h, the spraying distance was 20 mm, and the air pressure was controlled at 0.2 MPa to obtain a mixed conductive layer with a thickness of 1 μm, and then heated and cured at 60°C for 1 hour;

[0248] (3) Boron nitride, styrene-butadiene rubber, and LiTFSI were dissolved in DMF solvent in a mass ratio of 3:5:2 and stirred thoroughly to prepare a slurry with a solid content of 50% by mass, which was sprayed on the surface of the mixed conductive layer by ultrasonic spraying, wherein the ultrasonic power was 30 W, the ultrasonic frequency was controlled at 80 kHz, the spray width was 50 mm, the spray angle was 90°, the continuous spraying amount was controlled at 700 ml / h, the spraying distance was 20 mm, and the gas pressure was controlled at 0.1 MPa to obtain a first composite solid electrolyte layer with a thickness of 2 μm;

[0249] (4) Li7La3Zr2O 12The solid electrolyte, styrene-butadiene rubber, and LiTFSI were mixed and stirred in DMF in a mass ratio of 7:2:1 to prepare a slurry with a solid content of 40% by mass. The slurry was sprayed on the surface of the first composite solid electrolyte layer by ultrasonic spraying, wherein the ultrasonic frequency was controlled at 90 kHz, the continuous spraying amount was controlled at 800 ml / h, the spraying distance was 35 mm, and the air pressure was controlled at 0.2 MPa to obtain a composite electrode containing the second solid electrolyte. The thickness of the second solid electrolyte layer was 30 μm, and the slurry was heated and cured at 60°C for 1 hour.

[0250] (5) The composite negative electrode sheet and the lithium iron phosphate positive electrode stack obtained in the above steps are assembled into a solid-state battery by hot pressing at a temperature of 65°C and a pressure of 0.4 MPa.

[0251] Example 8

[0252] The present invention provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. A multi-layer solid electrolyte is introduced on the pole piece by ultrasonic spraying. The specific steps are as follows:

[0253] (1) carbon nanotubes (particle size 50 nm) and styrene-butadiene rubber were mixed uniformly in a ratio of 70% by mass to 30% by mass, dissolved in DMF solvent and stirred thoroughly, and sodium hydroxymethyl cellulose was added to prepare a slurry with a solid content of 40% by mass;

[0254] (2) The slurry was introduced onto the surface and gaps of the negative electrode active material by ultrasonic spraying on the surface of the silicon-carbon negative electrode plate, wherein the ultrasonic power was 60 W, the ultrasonic frequency was controlled at 60 kHz, the spray width was 50 mm, the spray angle was 90°, the continuous spraying amount was controlled at 700 ml / h, the spraying distance was 20 mm, and the air pressure was controlled at 0.2 MPa to obtain a mixed conductive layer with a thickness of 1 μm, and then heated and cured at 60°C for 1 hour;

[0255] (3) Boron oxide, styrene-butadiene rubber, and LiTFSI were dissolved in DMF solvent in a mass ratio of 3:5:2 and stirred thoroughly to prepare a slurry with a solid content of 50% by mass, which was sprayed on the surface of the mixed conductive layer by ultrasonic spraying, wherein the ultrasonic power was 30 W, the ultrasonic frequency was controlled at 80 kHz, the spray width was 50 mm, the spray angle was 90°, the continuous spraying amount was controlled at 700 ml / h, the spraying distance was 20 mm, and the gas pressure was controlled at 0.1 MPa to obtain a first composite solid electrolyte layer with a thickness of 2 μm;

[0256] (4) Li7La3Zr2O 12The solid electrolyte, styrene-butadiene rubber, and LiTFSI were mixed and stirred in DMF in a mass ratio of 7:2:1 to prepare a slurry with a solid content of 40% by mass. The slurry was sprayed on the surface of the first composite solid electrolyte layer by ultrasonic spraying, wherein the ultrasonic frequency was controlled at 90 kHz, the continuous spraying amount was controlled at 800 ml / h, the spraying distance was 35 mm, and the air pressure was controlled at 0.2 MPa to obtain a composite electrode containing the second solid electrolyte. The thickness of the second solid electrolyte layer was 30 μm, and the slurry was heated and cured at 60°C for 1 hour.

[0257] (5) The composite negative electrode sheet and the lithium iron phosphate positive electrode stack obtained in the above steps are assembled into a solid-state battery by hot pressing at a temperature of 65°C and a pressure of 0.4 MPa.

[0258] Example 9

[0259] The present invention provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. A multi-layer solid electrolyte is introduced on the pole piece by ultrasonic spraying. The specific steps are as follows:

[0260] (1) Nano-conductive carbon black (particle size 300 nm) and styrene-butadiene rubber were mixed uniformly in a ratio of 70% by mass to 30% by mass, dissolved in DMF solvent and stirred thoroughly, and sodium hydroxymethyl cellulose was added to prepare a slurry with a solid content of 40% by mass;

[0261] (2) The slurry was introduced onto the surface and gaps of the negative electrode active material by ultrasonic spraying on the surface of the silicon-carbon negative electrode plate, wherein the ultrasonic power was 60 W, the ultrasonic frequency was controlled at 60 kHz, the spray width was 50 mm, the spray angle was 90°, the continuous spraying amount was controlled at 700 ml / h, the spraying distance was 20 mm, and the air pressure was controlled at 0.2 MPa to obtain a mixed conductive layer with a thickness of 1 μm, and then heated and cured at 60°C for 1 hour;

[0262] (3) Boron oxide, styrene-butadiene rubber, and LiTFSI were dissolved in DMF solvent in a mass ratio of 3:5:2 and stirred thoroughly to prepare a slurry with a solid content of 35% by mass, which was sprayed on the surface of the mixed conductive layer by ultrasonic spraying, wherein the ultrasonic power was 30 W, the ultrasonic frequency was controlled at 80 kHz, the spray width was 50 mm, the spray angle was 90°, the continuous spraying amount was controlled at 700 ml / h, the spraying distance was 20 mm, and the gas pressure was controlled at 0.1 MPa to obtain a first composite solid electrolyte layer with a thickness of 2 μm;

[0263] (4) Tantalum-doped lithium lanthanum zirconium oxide, styrene-butadiene rubber, and LiTFSI were mixed and stirred in DMF in a mass ratio of 7:2:1 to prepare a slurry with a solid content of 40% by mass, which was sprayed on the surface of the first composite solid electrolyte layer by ultrasonic spraying, wherein the ultrasonic frequency was controlled at 90 kHz, the continuous spraying amount was controlled at 800 ml / h, the spraying distance was 35 mm, and the air pressure was controlled at 0.2 MPa to obtain a composite electrode containing a second solid electrolyte, the thickness of the second solid electrolyte layer was 30 μm, and the composite electrode was heated and cured at 60°C for 1 hour;

[0264] (5) The composite negative electrode sheet and the lithium iron phosphate positive electrode stack obtained in the above steps are assembled into a solid-state battery by hot pressing at a temperature of 65°C and a pressure of 0.4 MPa.

[0265] Example 10

[0266] The present invention provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof. A multi-layer solid electrolyte is introduced on the pole piece by ultrasonic spraying. The specific steps are as follows:

[0267] (1) carbon nanotubes (particle size 50 nm) and styrene-butadiene rubber were mixed uniformly in a ratio of 8% by mass to 20% by mass, dissolved in DMF solvent and stirred thoroughly, and sodium hydroxymethyl cellulose was added to prepare a slurry with a solid content of 40% by mass;

[0268] (2) The slurry was introduced onto the surface and gaps of the negative electrode active material by ultrasonic spraying on the surface of the silicon-carbon negative electrode plate, wherein the ultrasonic power was 60 W, the ultrasonic frequency was controlled at 60 kHz, the spray width was 50 mm, the spray angle was 90°, the continuous spraying amount was controlled at 700 ml / h, the spraying distance was 20 mm, and the air pressure was controlled at 0.2 MPa to obtain a mixed conductive layer with a thickness of 1 μm, and then heated and cured at 60°C for 1 hour;

[0269] (3) Boron nitride, styrene-butadiene rubber, and LiTFSI were dissolved in DMF solvent in a mass ratio of 3:5:2 and stirred thoroughly to prepare a slurry with a solid content of 40% by mass, which was sprayed on the surface of the mixed conductive layer by ultrasonic spraying, wherein the ultrasonic power was 30 W, the ultrasonic frequency was controlled at 80 kHz, the spray width was 50 mm, the spray angle was 90°, the continuous spraying amount was controlled at 700 ml / h, the spraying distance was 20 mm, and the gas pressure was controlled at 0.1 MPa to obtain a first composite solid electrolyte layer with a thickness of 2 μm;

[0270] (4) Tantalum-doped lithium lanthanum zirconium oxide, styrene-butadiene rubber, and LiTFSI were mixed and stirred in DMF in a mass ratio of 7:2:1 to prepare a slurry with a solid content of 40% by mass, which was sprayed on the surface of the first composite solid electrolyte layer by ultrasonic spraying, wherein the ultrasonic frequency was controlled at 90 kHz, the continuous spraying amount was controlled at 800 ml / h, the spraying distance was 35 mm, and the air pressure was controlled at 0.2 MPa to obtain a composite electrode containing a second solid electrolyte, the thickness of the second solid electrolyte layer was 30 μm, and the composite electrode was heated and cured at 60°C for 1 hour;

[0271] (5) The composite negative electrode sheet and the lithium iron phosphate positive electrode stack obtained in the above steps are assembled into a solid-state battery by hot pressing at a temperature of 65°C and a pressure of 0.4 MPa.

[0272] Comparative Example 1

[0273] This comparative example provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof, wherein a multi-layer solid electrolyte is introduced by ultrasonic spraying. Unlike Example 1, no mixed conductive layer is provided.

[0274] Comparative Example 2

[0275] This comparative example provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof, wherein a multi-layer solid electrolyte is introduced by ultrasonic spraying. The difference from Example 1 is that the first composite solid electrolyte layer is not provided;

[0276] Comparative Example 3

[0277] This comparative example provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof, wherein a multilayer solid electrolyte is introduced by ultrasonic spraying. The difference from Example 1 is that the ultrasonic frequency is different, being 10 kHz.

[0278] Comparative Example 4

[0279] This comparative example provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof, wherein a multilayer solid electrolyte is introduced by ultrasonic spraying. The difference from Example 1 is that the solid content of the slurry is different, being 80% by mass.

[0280] Comparative Example 5

[0281] This comparative example provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof, wherein a multilayer solid electrolyte is introduced by ultrasonic spraying. Unlike Example 1, no nano-conductive agent is used, and the particle size of the conductive agent used is 3.5 μm.

[0282] Comparative Example 6

[0283] This comparative example provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof, wherein a multi-layer solid electrolyte is introduced by ultrasonic spraying. The difference from Example 1 is that the thickness of the mixed conductive layer is different, and the thickness is 1.5 μm;

[0284] Comparative Example 7

[0285] This comparative example provides a pole piece and a preparation method thereof, a solid-state battery and a preparation method thereof, and uses an ultrasonic spraying method to introduce a multilayer solid electrolyte. The difference from Example 1 is that the mass ratio of the nano-conductive agent to the organic polymer solid electrolyte is 95:5.

[0286] Comparative Example 8

[0287] This comparative example provides a pole piece and a preparation method thereof, and a solid-state battery and a preparation method thereof, using an ultrasonic spraying method to introduce a multilayer solid electrolyte. The difference from Example 1 is that the continuous spraying amount used is 3100 mL / h.

[0288] Performance testing:

[0289] Peel strength test: The test was carried out in a peel force tester. At room temperature of 25°C and air humidity of -35°C dew point, one side of the prepared battery electrode collector was adhered to the working panel with a test double-sided tape, and the active material surface and the peel force tester were connected with a test tape. The peeling speed was 60 mm / min and the peeling angle was 180°. The peeling force was tested and recorded.

[0290] Interface impedance test: The prepared composite electrode and lithium metal sheet were assembled into a button cell, and the AC impedance was tested in an electrochemical workstation using the AC impedance method. The voltage amplitude was set to 5 mV and the frequency range was 0.1 Hz to 1 MHz.

[0291] Cycling stability test: The positive electrode sheet and the negative electrode sheet, the positive electrode sheet containing a solid electrolyte, or the negative electrode sheet were cut and assembled into button batteries. The batteries were charged and discharged at a rate of 0.3C at 25°C for 200 cycles. The battery capacity before and after the cycle was recorded 200 times. The initial charge and discharge capacity was also recorded, and the initial coulombic efficiency was calculated.

[0292] Table 1

[0293] By comparing and analyzing the test results of Examples 1-10 and Comparative Examples 1-8, when the applied process conditions are within the preferred range of ultrasonic spraying, the battery pole pieces prepared in Examples 1-10 have higher peel strength, the adhesion between the active substances of the composite pole pieces containing solid electrolytes is stronger, and the contact with the current collector is closer, which effectively reduces the interface impedance. Ultrasonic spraying of organic polymer solid electrolytes can reduce the interface impedance, maintain the stability and close contact of the interlayer interface, and effectively improve the cycle stability of the solid-state battery. The cycle capacity retention rate of the solid-state battery in Examples 1-10 is much higher than that of Comparative Examples 1-8, and it can be stably cycled for more than 200 times at a rate of 0.3C, showing good cycle stability.

[0294] Figure 1 is a scanning electron microscope characterization of the composite solid-state battery electrode obtained in Example 1. The particles on the electrode surface prepared by ultrasonic spraying are fully refined and no agglomeration of solid electrolyte particles is found. The solid electrolyte is evenly dispersed on the surface of the electrode, constructing a continuous and dense solid electrolyte layer.

[0295] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

[0296] Industrial applicability

[0297] In the present invention, a mixed conductive layer comprising a nano-conductive agent and an organic polymer solid electrolyte is introduced onto the surface of the electrode. The use of the nano-conductive agent effectively increases the contact area between the mixed conductive layer and the electrode, and the organic polymer solid electrolyte can reduce interfacial impedance, thereby improving the cycling stability of the solid-state battery. The present invention uses ultrasonic spraying to spray the slurry used to form the mixed conductive layer, which can fully refine the slurry particles, improve the stability of the coating, and achieve a uniform layered structure with controllable thickness, thereby improving the structural stability of the solid-state battery.

Claims

1. A pole piece, characterized in that: The invention comprises a mixed conductive layer on a positive electrode sheet or a negative electrode sheet, wherein the mixed conductive layer comprises a nano conductive agent and an organic polymer solid electrolyte.

2. The pole piece according to claim 1, wherein in the mixed conductive layer, the mass ratio of the nano conductive agent to the organic polymer solid electrolyte is (85-20): (15-80), preferably (80-25): (20-75).

3. The pole piece according to claim 1 or 2, wherein the particle size of the nano conductive agent is 5-500nm, preferably 10-300nm.

4. The pole piece according to any one of claims 1 to 3, wherein the thickness of the mixed conductive layer is 100 nm to 1000 nm, preferably 150 to 800 nm; Preferably, the mixed conductive layer further comprises a binder; Preferably, the binder is selected from one or more of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium hydroxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-butadiene-styrene copolymer, polyacrylic acid, and lithium polyacrylate.

5. The pole piece according to any one of claims 1 to 4, wherein the nano conductive agent is selected from one or more of conductive graphite, conductive carbon black, acetylene black, carbon nanotubes, Ketjen black, graphene, carbon nanofibers and polyethylene dioxythiophene; Preferably, the organic polymer solid electrolyte is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, polypentylene succinate, polyvinyl chloride, polyvinyl carbonate, polyvinyl pyrrolidone, polyimide, polyacrylate, and polyurethane.

6. The pole piece according to any one of claims 1 to 5, wherein the pole piece further comprises a first composite solid electrolyte layer on the mixed conductive layer; Preferably, the thickness of the first composite solid electrolyte layer is 200-3000 nm, preferably 250-2000 nm; Preferably, the first composite solid electrolyte layer comprises an inorganic ceramic material, an organic polymer solid electrolyte, and a lithium salt.

7. The pole piece according to claim 6, wherein the inorganic ceramic material used for the first composite solid electrolyte layer is selected from one or more of nitrides, carbides, metal oxides, and non-metal oxides; Preferably, the nitride is selected from one or more of silicon nitride, titanium nitride, aluminum nitride, boron nitride, and magnesium nitride; the carbide is selected from one or more of silicon carbide and boron carbide; the metal oxide is selected from one or more of aluminum oxide, titanium dioxide, zirconium dioxide, and magnesium oxide; the non-metallic oxide is selected from one or more of silicon dioxide and boron oxide.

8. The pole piece according to claim 6 or 7, wherein the pole piece further comprises a second solid electrolyte layer on the first composite solid electrolyte layer; Preferably, the thickness of the second solid electrolyte layer is 2 μm-50 μm, preferably 5 μm-40 μm; Preferably, the second solid electrolyte layer further comprises a lithium salt and / or a binder.

9. The pole piece according to claim 8, wherein the solid electrolyte used for the second solid electrolyte layer comprises one or more of an inorganic solid electrolyte and an organic polymer solid electrolyte; Preferably, the inorganic solid electrolyte is selected from one or more of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, a borate solid electrolyte, and a nitride solid electrolyte.

10. The pole piece according to claim 9, wherein the oxide solid electrolyte is selected from one or more of a perovskite oxide solid electrolyte, a garnet oxide solid electrolyte, and a NASICON oxide solid electrolyte; The sulfide solid electrolyte is selected from one or more of lithium germanium phosphosulfur, lithium silicon phosphosulfur chlorine, lithium phosphosulfur bromine, lithium phosphosulfur iodine, lithium phosphosulfur chlorine, lithium thiophosphate, and glassy sulfide; The halide solid electrolyte is selected from g ijini3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1), Li2XCl4 (X is selected from Cd and / or Mg), Li2X′I4 (X′ is selected from Cd and / or Zn), LiMCl5X″ (M is selected from one or more of La, Ta, Nb, X″ is selected from O, Cl, F or OH), Li 3-y Zr y M′ 1-y Cl6 (M′ is selected from one or more of Y, Er, Yb, Ho, Lu, 0 < y < 1); The borate solid electrolyte is selected from one or more of Li2B4O7, Li2O-B2O3-P2O5; The nitride solid electrolyte is selected from one or more of LiPON, Li3N, Li7PN4, and LiSi2N3; The organic polymer solid electrolyte is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, polypentylene succinate, polyvinyl chloride, polyvinyl carbonate, polyvinyl pyrrolidone, polyimide, and polyacrylate polyurethane; Preferably, the perovskite-type oxide solid electrolyte is selected from lithium lanthanum titanium oxide; The garnet-type oxide solid electrolyte is selected from one or more of lithium lanthanum zirconium oxide, niobium-doped lithium lanthanum zirconium oxide, tantalum-doped lithium lanthanum zirconium oxide, and niobium-tantalum dual-doped lithium lanthanum zirconium oxide; The NASICON type oxide solid electrolyte is selected from one or more of lithium aluminum titanium phosphate, lithium yttrium titanium phosphate, and lithium aluminum germanium phosphate.

11. The pole piece according to claim 8, wherein the binder is selected from one or more of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium hydroxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-butadiene-styrene copolymer, polyacrylic acid, and lithium polyacrylate; Preferably, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide) and lithium difluorooxalatoborate.

12. A method for preparing a pole piece, characterized in that: It includes the following steps: Step S2: spraying a conductive slurry containing a nano conductive agent and an organic polymer solid electrolyte onto the surface of the positive electrode sheet or the negative electrode sheet by ultrasonic spraying, and then optionally heating and curing to obtain a positive electrode sheet or a negative electrode sheet with a mixed conductive layer.

13. The preparation method according to claim 12, wherein the preparation method further comprises the following steps: Step S4: spraying the slurry containing the inorganic ceramic material onto the surface of the mixed conductive layer obtained in step S2 by ultrasonic spraying, thereby obtaining a composite conductive layer having the mixed conductive layer and the first composite solid in sequence. The positive electrode sheet or the negative electrode sheet of the electrolyte layer.

14. The preparation method according to claim 13, wherein the preparation method further comprises the following steps: Step S6: spraying the second solid electrolyte slurry onto the surface of the first composite solid electrolyte layer obtained in step S4 by ultrasonic spraying, thereby obtaining a positive electrode sheet or a negative electrode sheet having a mixed conductive layer, a first composite solid electrolyte layer and a second solid electrolyte layer in sequence.

15. The preparation method according to any one of claims 12 to 14, wherein the preparation method further comprises the following steps: step Sx: hot pressing the final positive electrode sheet or negative electrode sheet; Preferably, the hot pressing temperature is 40-60° C., the pressure is 0.1-0.5 MPa, and the hot pressing time is 5-20 minutes.

16. The preparation method according to claims 12-15, wherein the solid content of the conductive paste is 5 to 40% by mass; Preferably, the solid content of the slurry containing the inorganic ceramic material is 5 to 30% by mass; Preferably, the second solid electrolyte slurry has a solid content of 5 to 40% by mass.

17. The preparation method according to any one of claims 12 to 16, wherein in the conductive paste of step S2, the mass ratio of the nano conductive agent to the organic polymer solid electrolyte is (85-20): (15-80), preferably (80-25): (20-75); Preferably, the particle size of the nano conductive agent is 5-500 nm, preferably 10-300 nm.

18. The preparation method according to claim 14, wherein in the ultrasonic spraying in step S2, step S4 and step S6, the spraying conditions are as follows: ultrasonic power is 10-100 W, ultrasonic frequency is 20-200 kHz, continuous spraying amount is 0-3000 ml / h, preferably 800-1700 ml / h, spraying distance is 10-100 mm, air pressure is 0.1-0.3 MPa, spray width is 50-400 mm, spraying angle is 85-90°, and the temperature of the positive electrode sheet or the negative electrode sheet is 30-80°C; Preferably, the spraying conditions in step S2, step S4 and step S6 are the same or different.

19. The preparation method according to any one of claims 12 to 18, wherein in step S2, the temperature of heating and curing is 60-120°C, preferably 80-100°C.

20. The preparation method according to any one of claims 12 to 19, wherein the nano-conductive agent used in step S2 is selected from one or more of conductive graphite, conductive carbon black, acetylene black, carbon nanotubes, Ketjen black, graphene, carbon nanofibers and polyethylene dioxythiophene; Preferably, the organic polymer solid electrolyte used in step S2 is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, polypentylene succinate, polyvinyl chloride, polyvinyl carbonate, polyvinyl pyrrolidone, polyimide, polystyrene sulfonic acid, polyacrylate, and polyurethane.

21. The preparation method according to claim 13, wherein the slurry containing the inorganic ceramic material used in step S4 further contains an organic polymer solid electrolyte and a lithium salt; The inorganic ceramic material used in step S4 is selected from one or more of nitrides, carbides, metal oxides, and non-metal oxides; Preferably, the nitride is selected from one or more of silicon nitride, titanium nitride, aluminum nitride, boron nitride, and magnesium nitride; the carbide is selected from one or more of silicon carbide and boron carbide; the metal oxide is selected from one or more of aluminum oxide, titanium dioxide, zirconium dioxide, and magnesium oxide; the non-metallic oxide is selected from one or more of silicon dioxide and boron oxide; Preferably, the organic polymer solid electrolyte is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, polypentylene succinate, polyvinyl chloride, polyvinyl carbonate, polyvinyl pyrrolidone, polyimide, polystyrene sulfonic acid and polyacrylate; Preferably, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), and lithium difluorooxalatoborate.

22. The preparation method according to claim 14, wherein the second solid electrolyte used in step S6 is selected from one or more of an inorganic solid electrolyte and an organic polymer solid electrolyte; Preferably, the inorganic solid electrolyte is selected from oxide solid electrolyte, sulfide solid electrolyte, halide solid electrolyte, borate solid electrolyte, nitride solid electrolyte. kind or kinds; Preferably, the oxide solid electrolyte is selected from one or more of a perovskite oxide solid electrolyte, a garnet oxide solid electrolyte, and a NASICON oxide solid electrolyte; The sulfide solid electrolyte is selected from one or more of lithium germanium phosphosulfur, lithium phosphosulfuryl chloride, lithium silicon phosphosulfuryl chloride, lithium phosphosulfuryl bromine, lithium phosphosulfuryl iodide, lithium thiophosphate, and glassy sulfide; The halide solid electrolyte is selected from Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1), Li2XCl4 (X is selected from Cd and / or Mg), Li2X′I4 (X′ is selected from Cd and / or Zn), LiMCl5X″ (M is selected from one or more of La, Ta, Nb, and X″ is selected from O, Cl, F, or OH), Li 3-y Zr y M′ 1-y Cl6 (M′ is selected from one or more of Y, Er, Yb, Ho, Lu, 0 < y < 1); The borate solid electrolyte is selected from one or more of Li2B4O7, Li2O-B2O3-P2O5; The nitride solid electrolyte is selected from one or more of LiPON, Li3N, Li7PN4, and LiSi2N3; The organic polymer solid electrolyte is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, polypentylene succinate, polyvinyl chloride, polyvinyl carbonate, polyvinyl pyrrolidone, polyimide, polystyrene sulfonic acid and polyacrylate; Preferably, the perovskite-type oxide solid electrolyte is selected from lithium lanthanum titanium oxide; The garnet-type oxide solid electrolyte is selected from one or more of lithium lanthanum zirconium oxide, niobium-doped lithium lanthanum zirconium oxide, tantalum-doped lithium lanthanum zirconium oxide, and niobium-tantalum dual-doped lithium lanthanum zirconium oxide; The NASICON type oxide solid electrolyte is selected from one or more of lithium aluminum titanium phosphate, lithium yttrium titanium phosphate, and lithium aluminum germanium phosphate.

23. The preparation method according to claim 14, wherein the slurry in step S2 further comprises a binder; Preferably, the slurry in step S6 further includes a lithium salt and / or a binder.

24. The preparation method according to claim 23, wherein the binder is selected from one or more of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium hydroxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-butadiene-styrene copolymer, polyacrylic acid, and lithium polyacrylate; The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), and lithium difluorooxalatoborate; Preferably, the binder used in the slurry in step S2 and the binder used in the slurry in step S6 are the same as or different from each other.

25. A solid-state battery, comprising the electrode sheet according to any one of claims 1 to 11 or the positive electrode sheet or negative electrode sheet obtained by the preparation method according to any one of claims 12 to 24.

26. A method for preparing a solid-state battery, comprising: The step of preparing a positive electrode sheet or a negative electrode sheet by the preparation method according to any one of claims 12 to 24.

27. The preparation method according to claim 26, further comprising the step of rolling, drying, and then hot-pressing the positive electrode sheet and / or the negative electrode sheet for integration.

28. The preparation method according to claim 27, wherein in the hot pressing integration, the hot pressing temperature is 50-85°C, the pressure is 0.2-0.9 MPa, and the hot pressing time is 20-40 minutes.

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