CN117542960A - Composite positive electrode plate and preparation method and application thereof - Google Patents

Composite positive electrode plate and preparation method and application thereof Download PDF

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Publication number
CN117542960A
CN117542960A CN202311650632.8A CN202311650632A CN117542960A CN 117542960 A CN117542960 A CN 117542960A CN 202311650632 A CN202311650632 A CN 202311650632A CN 117542960 A CN117542960 A CN 117542960A
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positive electrode
composite positive
solid electrolyte
halide solid
equal
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余乐
李谦
吕文彬
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai Co Ltd
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes

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  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
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  • Manufacturing & Machinery (AREA)
  • Inorganic Chemistry (AREA)
  • Composite Materials (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides a composite positive electrode plate, a preparation method and application thereof, wherein the composite positive electrode plate at least comprises: a positive electrode active material including LiNi m Co n Mn (1‑m‑n) O 2 WhereinM is more than or equal to 0.8 and less than 1, n is more than or equal to 0 and less than or equal to 0.1; a halide solid electrolyte; wherein: the chemical formula of the halide solid electrolyte is Li 2+a Zr 1‑a Fe a Cl 6‑x‑y Br x I y A is more than 0 and less than or equal to 0.5; x=0 to 6, y=0 to 6, x+y is less than or equal to 6; the compaction density of the composite positive electrode plate is 2.8g/cm 3 ‑3.4g/cm 3 . By the composite positive electrode plate, the preparation method and the application thereof, the compaction density of the positive electrode plate is improved, so that the rate performance and the cycle life of the lithium ion battery are improved.

Description

Composite positive electrode plate and preparation method and application thereof
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a composite positive electrode plate, a preparation method and application thereof.
Background
With the development of secondary batteries mainly comprising lithium ion batteries, the lithium ion batteries are widely applied to the fields of portable electronic products, electric automobiles and the like, but due to the fact that flammable organic solvents are used as electrolyte in the traditional lithium ion batteries, serious potential safety hazards exist, so that safety accidents frequently occur in recent new energy automobiles, and the problem cannot be completely solved through a conventional improvement method. In contrast, all-solid-state lithium ion batteries employing inorganic solid-state electrolytes have higher safety, and one major challenge facing all-solid-state lithium ion batteries is matching between electrode materials and solid-state electrolytes to reduce interface impedance and ensure interface stability. However, the conventional solid electrolyte has the problems of high cost, low matching with the positive electrode material, difficult matching with the positive electrode material, low compaction density, poor cycling stability of the positive electrode material, serious side reaction with the inorganic solid electrolyte and the like.
Disclosure of Invention
The invention provides a composite positive electrode plate, a preparation method and application thereof, and by the composite positive electrode plate, the preparation method and application thereof, the compaction density of the positive electrode plate can be improved, the lithium ion conduction capacity of the composite positive electrode plate is improved, meanwhile, the side reaction of the composite positive electrode plate and sulfide electrolyte under high voltage is effectively inhibited, and the interface stability of the positive electrode plate and solid electrolyte is improved, so that the multiplying power performance and the cycle life of a lithium ion battery are improved.
In order to solve the technical problems, the invention is realized by the following technical scheme.
The invention provides a composite positive pole piece, which at least comprises:
a positive electrode active material including LiNi m Co n Mn (1-m-n) O 2 Wherein m is more than or equal to 0.8 and less than 1, n is more than or equal to 0 and less than or equal to 0.1; and
a halide solid electrolyte;
wherein: the chemical formula of the halide solid electrolyte is Li 2+a Zr 1-a Fe a Cl 6-x-y Br x I y A is more than 0 and less than or equal to 0.5; x=0 to 6, y=0 to 6, x+y is less than or equal to 6; the compaction density of the composite positive electrode plate is 2.8g/cm 3 -3.4g/cm 3 。
In one embodiment of the invention, the halide solid state electrolyte has a median particle diameter D50 of 0.1 μm to 10 μm.
In one embodiment of the present invention, the positive electrode active material includes LiNi 0.92 Co 0.4 Mn 0.4 O 2 。
In one embodiment of the present invention, the halide solid state electrolyte comprises Li 2.3 Zr 0.7 Fe 0.3 Cl 6 。
In one embodiment of the invention, the ionic conductivity of the halide solid state electrolyte is greater than or equal to 1mS/cm.
The invention also provides a preparation method of the composite positive plate, which at least comprises the following steps:
uniformly mixing an anode active material, a halide solid electrolyte, a conductive agent and a binder according to a mass ratio to obtain mixed powder; and
and manufacturing the mixed powder on a current collector with a conductive acid corrosion resistant coating by a dry method or a wet method to obtain the composite positive plate.
In an embodiment of the present invention, the conductive corrosion-resistant coating is one of a conductive carbon layer, a conductive polymer layer, a gold layer, or a silver layer, and the thickness of the conductive corrosion-resistant coating is 0.01 μm-10 μm.
In one embodiment of the present invention, the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent, and the binder is (68-78): (15-25): (1-3): (2-4).
The invention also provides a lithium ion battery, which comprises the composite positive plate.
The invention also provides electronic equipment comprising the lithium ion battery.
In summary, the invention provides a composite positive plate, a preparation method and application thereof, which can obtain a halide solid electrolyte with low cost, small size, high ionic conductivity and high voltage resistance, and can improve the compaction density of the positive plate, thereby improving the multiplying power performance and the cycle life of a lithium ion battery. Meanwhile, the halide solid electrolyte has good compatibility with the positive electrode with high specific capacity, and the loss of contact of the positive electrode active material caused by the micro stress of the positive electrode particles is reduced, so that the rate capability and the cycle life of the battery are improved. The positive electrode active material can improve the energy density and the cycle life of the lithium ion battery, improve the endurance energy of the lithium ion battery and effectively solve the problem of light weight of the battery. The method can construct an all-solid-state battery with high density, improves the lithium ion conduction capacity of the composite positive pole piece, effectively inhibits side reactions of the composite positive pole piece and sulfide electrolyte, reduces the interface impedance of the battery, improves the capacity of inhibiting the growth of metal dendrites, and further improves the circulation and rate capability.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a flow chart of a process for preparing a halide solid electrolyte according to the present invention.
Fig. 2 is a flow chart of the preparation of a composite positive electrode sheet in the present invention.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
It should be understood that the present invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Unless otherwise specified, "%" and "parts" shown in the following examples refer to "% by mass" and "parts by mass", respectively.
The technical solution of the present invention will be described in further detail below with reference to several embodiments and the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a composite positive electrode plate, which comprises a current collector and a positive electrode active layer coated on the current collector. The current collector is, for example, a current collector with a conductive acid corrosion-resistant coating, and the current collector is, for example, an aluminum foil, a stainless steel foil or a titanium foil, wherein the conductive acid corrosion-resistant coating comprises at least one of a conductive carbon layer, a conductive polymer layer, a gold layer or a silver layer, and the thickness of the conductive acid corrosion-resistant coating is, for example, 0.01-10 μm, and is, for example, 0.01-1 μm. The positive electrode active layer includes at least a positive electrode active material, a halide solid electrolyte, and the like, and the thickness of the positive electrode active layer is, for example, 80 μm to 140 μm. The application provides the halide solid electrolyte with low cost, small size, high ionic conductivity and high voltage resistance, which can improve the compaction density of the positive electrode plate and reduce the micro-scale caused by positive electrode particlesThe positive electrode active material loses contact due to stress, so that the rate performance and the cycle life of the battery are improved. Meanwhile, can solve the problems of high specific capacity nickel cobalt manganese positive electrode active material and traditional electrolyte material (such as Li 3 InCl 6 Etc.), the problem of interfacial instability, reduced side reactions, improved battery initial capacity and cycle life.
In one embodiment of the present invention, the positive electrode active material includes, for example, a high specific capacity nickel cobalt manganese positive electrode active material having the chemical formula LiNi m Co n Mn (1-m-n) O 2 Wherein m is more than or equal to 0.8 and less than 1, n is more than or equal to 0 and less than or equal to 0.1. The positive electrode active material can improve the energy density and the cycle life of the lithium ion battery, improve the endurance energy of the lithium ion battery and effectively solve the problem of light weight of the battery.
In one embodiment of the present invention, the halide solid electrolyte has the formula Li 2+a Zr 1-a Fe a Cl 6-x-y Br x I y And 0 < a.ltoreq.0.5, x=0 to 6, y=0 to 6, x+y.ltoreq.6, and the ionic conductivity of the halide solid electrolyte is 1mS/cm or more, the median particle diameter D50 of the halide solid electrolyte is, for example, 0.1 μm to 10. Mu.m, and is, for example, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm or 8 μm or the like. The size of the halide solid electrolyte is smaller, the matching property of the size of the halide solid electrolyte and the nickel-cobalt-manganese positive electrode active material with high specific capacity can be improved, and the compaction density of the composite positive electrode sheet can reach 2.8g/cm 3 -3.4g/cm 3 . The halide electrolyte material has better oxidation stability, can be better compatible with high specific capacity positive electrode active materials, in particular to nickel cobalt manganese positive electrode active materials with high nickel and high specific capacity, is used as an ion conductive agent in a positive electrode plate of an all-solid-state battery, improves the lithium ion conductivity of the composite positive electrode plate, and builds the high-density all-solid-state battery, thereby reducing the interface impedance of the battery, improving the capability of inhibiting the growth of metal dendrites, and further improving the cycle and rate performance. The halide solid electrolyte does not contain rare earth metal, so that the cost can be obviously reduced, and the halide solid electrolyte takes iron element as doping elementThe element can further reduce the cost and simultaneously ensure that Fe in crystal lattice 3+ The equivalent substitution of (c) can increase the ionic conductivity of the halide solid state electrolyte. Meanwhile, the particle size of the halide solid electrolyte is matched with that of the positive electrode active material, so that a composite positive electrode plate with high compaction density is obtained, the rate performance and the cycle life of the battery are improved, meanwhile, the halide solid electrolyte has good compatibility with the positive electrode, the side reaction is reduced, and the first-week coulomb efficiency of the battery is improved.
In an embodiment of the present invention, the positive electrode active layer further includes a conductive agent, a binder, and the like, wherein the conductive agent is one or a combination of at least two of conductive Carbon black (Super P, SP), carbon Nanotube (CNT), vapor grown Carbon fiber (Vapor Grown Carbon Fiber, VGCF), graphene, and the like. In this embodiment, the conductive agent is, for example, a combination of conductive carbon black and vapor grown carbon fiber, and the mass ratio of conductive carbon black to vapor grown carbon fiber is, for example, 1:1. The binder can be dispersed in a low polarity solvent, and includes, for example, at least one of hydrogenated nitrile rubber (Hydrogenated Nitrile Rubber, HNBR), styrene-butadiene-styrene block copolymer (Styreneic Block Copolymers, SBS), styrene Acrylate (Styrene Acrylate Copolymer, SAC), acrylate (Acrylate), styrene-butadiene rubber (Polymerized Styrene Butadiene Rubber, SBR), nitrile rubber (Nitrile Butadiene Rubber, NBR), silica Gel (Silica Gel), polyvinylidene fluoride (Polyvinylidene Fluoride, PVDF), lithium carboxymethyl cellulose (CMC-Li), or the like, and further, hydrogenated nitrile rubber, fluororubber, styrene-butadiene-styrene block copolymer, styrene-butadiene rubber, or the like. In one embodiment of the present invention, the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent, and the binder is, for example, (68-78): (15-25): (1-3): (2-4).
Referring to fig. 1, the present invention also provides a preparation method of the halide solid electrolyte, which includes, but is not limited to, step S11-step S12.
And S11, mixing corresponding amounts of compounds containing Li, zr and Fe according to the chemical formula of the halide solid electrolyte to obtain mixed powder.
And step S12, grinding and sintering the mixed powder to obtain the halide solid electrolyte.
Referring to FIG. 1, in step S11, according to the chemical formula Li of the halide solid electrolyte 2+a Zr 1- a Fe a Cl (6-x-y) Br x I y Corresponding molar amounts of Li, zr and Fe ion-containing compounds were mixed to obtain a mixed powder. In one embodiment of the invention, the halide solid electrolyte has the formula Li 2.3 Zr 0.7 Fe 0.3 Cl 6 The raw materials selected are, for example, lithium chloride (LiCl), zirconium chloride (ZrCl) 4 ) Ferric chloride (FeCl) 3 ) Etc. In this example, the various materials are mixed, for example, by ball milling, to make the materials more uniform for mixing and contacting, and the rotational speed of the ball milling is, for example, 200rpm to 500rpm, for example, 300rpm, for example, 1h to 2h, for example, for 1h, for example, for ball milling, for example, for 8mm to 15mm, for example, for 10mm, for example, for ball milling, for example, for a ball to ball ratio of (20 to 30): 1, for example, for 30:1, for example.
Referring to fig. 1, in an embodiment of the present invention, after the mixed powder is obtained in step S12, the mixed powder is processed, for example, by ball milling, solid phase sintering or heating co-melting, and the mixed powder is prepared, for example, by grinding and sintering. Wherein the grinding speed is, for example, 500rpm-800rpm, and also, for example, 600rpm, and the grinding time is, for example, 8h-15h, and also, for example, 10h. After grinding the powder mixture, the median particle diameter D50 of the powder mixture is, for example, from 0.1 μm to 10. Mu.m, for example, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm or 8. Mu.m, or the like, for example, 3. Mu.m. And sintering the ground mixture to obtain the halide solid electrolyte. Wherein the temperature rising rate of sintering is, for example, 4 ℃/min-5 ℃/min, the sintering temperature is, for example, 250 ℃ -350 ℃, the sintering time is 3-5 hours, the sintering atmosphere is, for example, inert gas, and the sintering time is the time after the temperature rises to the sintering temperature. The crystallinity of the halide solid electrolyte can be enhanced by the sintering process. And cooling the halide solid electrolyte by furnace cooling after sintering. In the halide solid electrolyte, the invention takes Fe element as the elementAs doping element, fe in lattice 3+ The equivalent substitution of (c) may increase the ionic conductivity of the electrolyte. In one embodiment of the invention, the ionic conductivity of the halide solid state electrolyte is, for example, greater than or equal to 1mS/cm.
Referring to fig. 2, the present invention further provides a method for preparing a composite positive electrode sheet, which includes, but is not limited to, steps S100-S200.
And step S100, uniformly mixing the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder according to the mass ratio to obtain mixed powder.
And step 200, manufacturing the mixed powder on a current collector with a conductive acid corrosion resistant coating by a dry method or a wet method to obtain the composite positive plate.
Referring to fig. 2, in step S100, the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder are uniformly mixed according to the mass ratio to obtain a mixed powder. Wherein the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder is, for example, (68-78): (15-25): (1-3): (2-4). In this embodiment, the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent, and the binder is, for example, 75:20:2:3. The conductive agent is a combination of conductive carbon black and vapor grown carbon fiber, and the mass ratio of the conductive carbon black to the vapor grown carbon fiber is 1:1.
Referring to fig. 2, in step S200, in the dry manufacturing process, the uniformly mixed powder is pressed or sprayed by a dry method and rolled on a current collector with a conductive acid corrosion resistant coating to obtain a composite positive electrode sheet. The current collector is any applicable positive current collector, such as aluminum foil, stainless steel foil or titanium foil, the conductive acid corrosion-resistant coating comprises one of a conductive carbon layer, a conductive polymer layer, a gold layer or a silver layer, and the thickness of the conductive corrosion-resistant coating is 0.01-10 μm, such as 0.01-1 μm. In the wet process, the mixed powder which is uniformly mixed is dispersed into a solvent to obtain slurry, the slurry is coated on a current collector with a conductive acid corrosion resistant coating,and drying and rolling to obtain the composite positive electrode plate. The solvent is, for example, a good solvent for the binder, such as alkanes, benzenes, ethers or esters, which are low-polarity solvents. The slurry is coated on a current collector with a conductive acid corrosion resistant coating by adopting a traditional wet method, such as a doctor blade coating method, a roller coating method or a spraying method, the temperature of the slurry is for example 80-200 ℃, the time is for example 0.5-12 h, and the method of blast drying or vacuum drying is selected. After drying, the temperature of rolling is 50-70 ℃, the pressure is 80-100 MPa, and the compaction density of the rolled composite positive pole piece is 2.8g/cm 3 -3.4g/cm 3 . The positive electrode active layer in the application has high compactness, can enhance ion transmission among the positive electrode active material, the halide solid electrolyte and each other, has higher capacity exertion, and has more excellent electrochemical performance.
The invention also provides a lithium ion battery, which comprises a positive electrode plate, a solid electrolyte and a negative electrode plate, wherein the solid electrolyte is arranged between the positive electrode plate and the negative electrode plate. Wherein the solid electrolyte is selected from one or more of halides, sulfides, oxides, polymers, or the like, and in the present embodiment, the solid electrolyte is selected from Li 6 PS 5 Cl, and the like. The positive electrode plate is the composite positive electrode plate obtained by the method. The negative electrode tab is selected from, for example, metallic indium, metallic lithium, alloys, carbon negative electrodes, tin-based negative electrodes, nano-oxides, or the like, and in this embodiment, the negative electrode tab is selected from, for example, metallic lithium tabs. The positive electrode sheet is added to one side of the solid electrolyte, for example, pressed into a sheet at a pressure of 300MPa, and the positive electrode sheet and the electrolyte are laminated together. And then placing a negative electrode plate at the other side of the solid electrolyte, and sealing under vacuum or inert atmosphere to obtain the all-solid-state lithium ion battery.
Hereinafter, the present invention will be more specifically explained by referring to examples, which should not be construed as limiting. Appropriate modifications may be made within the scope consistent with the gist of the invention, which fall within the technical scope of the invention.
Example 1
In the environment of dew point of minus 30 ℃, the anode active material LiNi 0.92 Co 0.4 Mn 0.4 O 2 Solid electrolyte of halide Li 2.3 Zr 0.7 Fe 0.3 Cl 6 Dispersing the conductive agent Super P, VGCF and the adhesive hydrogenated nitrile rubber into dimethylbenzene according to a mass ratio of 75:20:1:1:3, and adjusting the viscosity of the slurry by adjusting the addition amount of the dimethylbenzene, wherein the solid content of the slurry is about 50%. The slurry was coated on an aluminum foil having a conductive carbon layer of a thickness of 13 μm and a thickness of 1 μm by a blade coating method. Drying the coated current collector by blowing at 110 ℃ for 2 hours, and then rolling and compacting at 60 ℃ under the pressure of 90MPa to obtain the composite positive electrode plate with the compacted density of 3.1g/cm 3 . In the composite positive electrode sheet, the thickness of the positive electrode active layer was 100 μm.
Thin lithium sheet is used as negative electrode, and solid electrolyte layer is Li 6 PS 5 Cl, adding a composite positive electrode plate at one side of the solid electrolyte layer, tabletting at 300MPa pressure, and laminating the positive electrode plate and the electrolyte together. And then a thin lithium sheet is put on the other side of the electrolyte to serve as a negative electrode sheet, and the negative electrode sheet is sealed under vacuum, so that the all-solid-state lithium ion battery can be obtained.
Example 2
Rolling compaction is carried out at 60 ℃ and 80MPa, and the compaction density of the obtained composite positive electrode plate is 2.8g/cm 3 Other operations remain the same as in example 1.
Example 3
Rolling compaction is carried out at 60 ℃ under the pressure of 100MPa, and the compaction density of the obtained composite positive electrode plate is 3.4g/cm 3 Other operations remain the same as in example 1.
Comparative example 1
Replacement of halide solid electrolyte in composite positive electrode sheet with sulfide electrolyte Li 6 PS 5 Cl, other operations remain the same as in example 1.
Comparative example 2
Rolling compaction is carried out at 60 ℃ under the pressure of 40MPa, and the compaction density of the obtained composite positive electrode plate is 2.0g/cm 3 Other operations remain the same as in example 1.
Comparative example 3
Rolling compaction is carried out at 60 ℃ and 120MPa, and the compaction density of the obtained composite positive electrode plate is 4.0g/cm 3 Other operations remain the same as in example 1.
In the invention, different composite positive pole pieces are adopted in the examples 1-3 and the comparative examples 1-3 to prepare lithium ion batteries, and the prepared full-solid lithium ion batteries are subjected to long-cycle charge and discharge at 25 ℃ to measure the capacity retention rate. The working voltage range of the battery test is 3.0V-4.2V, the testing multiplying power is 0.3C, the discharge capacity of each circle is recorded, and when the battery capacity reaches 80% of the first circle capacity (80% State of Health,80% SOH), the test is ended, and the normal-temperature cycle number is obtained.
Table 1, examples 1-3 and comparative examples 1-3 results of performance test of lithium ion batteries
Referring to table 1, in comparative examples 1 and 1, the initial discharge specific capacity and the normal temperature cycle performance of the all-solid lithium ion battery can be improved by adding a halide solid electrolyte to the composite positive electrode sheet. The capacity of the lithium ion battery can be improved and the cycle performance can be improved by adding the halide solid electrolyte, which shows that the halide solid electrolyte has good compatibility with the nickel-cobalt-manganese positive electrode active material with high specific capacity, the side reaction of the composite positive electrode plate and the sulfide electrolyte under high voltage can be effectively inhibited, the interface stability of the positive electrode and the solid electrolyte is improved, the side reaction is reduced, the first-week coulomb efficiency of the battery is improved, and the cycle life of the battery is prolonged.
Referring to table 1, comparative examples 1 to 3 and comparative examples 2 to 3 show that the initial discharge specific capacity and the normal temperature cycle performance of the all-solid lithium ion battery are increased and then decreased with the increase of the compacted density of the composite positive electrode sheet. And when the compaction density is low, the porosity of the composite positive electrode plate is improved, the contact between the electrolyte and the positive electrode active material is less, and a small amount or part of active materials are not contacted, so that the performance of the lithium ion battery is reduced. However, when the compaction density is higher, a small amount of electrolyte material is crushed and reacts with residual alkali on the surface of the positive electrode plate, so that the ionic conductivity of the composite positive electrode plate is reduced, the performance of the lithium ion battery is reduced, and the pole plate is wrinkled along with the further improvement of the compaction density to cause short circuit. Therefore, the application controls the range of the compaction density while improving the compaction density of the composite positive electrode plate, thereby improving the multiplying power performance and the cycle life of the battery.
The invention also provides electronic equipment, which comprises at least one lithium ion battery, wherein the lithium ion battery is used for providing electric energy. The electronic device may be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. In an embodiment of the present invention, the vehicle is, for example, a new energy vehicle, which may be a pure electric vehicle, a hybrid electric vehicle, or an extended range vehicle. Spacecraft include airplanes, rockets, space planes, spacecraft, and the like, and electric toys include fixed or mobile electric toys, including, for example, game consoles, electric car toys, electric ship toys, electric airplane toys, and the like. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railroad power tools, including, for example, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete shakers, and electric planers, among others. The electronic device comprises the above-described lithium ion battery and thus the advantages of the above-described lithium ion battery are not described herein.
In summary, the invention provides a composite positive plate, a preparation method and application thereof, which can obtain a halide solid electrolyte with low cost, small size, high ionic conductivity and high voltage resistance, and can improve the compaction density of the positive plate, thereby improving the multiplying power performance and the cycle life of a lithium ion battery. Meanwhile, the halide solid electrolyte has good compatibility with the high-specific-capacity positive electrode active material, and the loss of contact of the positive electrode active material caused by the microstress of the positive electrode particles is reduced, so that the rate capability and the cycle life of the battery are improved. The positive electrode active material can improve the energy density and the cycle life of the lithium ion battery, improve the endurance energy of the lithium ion battery and effectively solve the problem of light weight of the battery. The method can construct an all-solid-state battery with high density, improves the lithium ion conduction capacity of the composite positive pole piece, effectively inhibits side reactions of the composite positive pole piece and sulfide electrolyte, reduces the interface impedance of the battery, improves the capacity of inhibiting the growth of metal dendrites, and further improves the circulation and rate capability.
The foregoing description is only illustrative of the preferred embodiments of the present application and the technical principles employed, and it should be understood by those skilled in the art that the scope of the invention in question is not limited to the specific combination of features described above, but encompasses other technical solutions which may be formed by any combination of features described above or their equivalents without departing from the inventive concept, such as the features described above and the features disclosed in the present application (but not limited to) having similar functions being interchanged.
Other technical features besides those described in the specification are known to those skilled in the art, and are not described herein in detail to highlight the innovative features of the present invention.

Claims (10)

1. The composite positive plate is characterized by at least comprising:
a positive electrode active material including LiNi m Co n Mn (1-m-n) O 2 Wherein m is more than or equal to 0.8 and less than 1, n is more than or equal to 0 and less than or equal to 0.1; and
a halide solid electrolyte;
wherein: the chemical formula of the halide solid electrolyte is Li 2+a Zr 1-a Fe a Cl 6-x-y Br x I y A is more than 0 and less than or equal to 0.5; x=0 to 6, y=0 to 6, x+y is less than or equal to 6; the compaction density of the composite positive electrode plate is 2.8g/cm 3 -3.4g/cm 3 。
2. The composite positive electrode sheet according to claim 1, wherein the halide solid electrolyte has a median particle diameter D50 of 0.1 μm to 10 μm.
3. The composite positive electrode sheet according to claim 1, wherein the positive electrode active material comprises LiNi 0.92 Co 0.4 Mn 0.4 O 2 。
4. The composite positive electrode sheet according to claim 1, wherein the halide solid state electrolyte comprises Li 2.3 Zr 0.7 Fe 0.3 Cl 6 。
5. The composite positive electrode sheet of claim 1, wherein the halide solid state electrolyte has an ionic conductivity greater than or equal to 1mS/cm.
6. The preparation method of the composite positive plate is characterized by at least comprising the following steps:
uniformly mixing an anode active material, a halide solid electrolyte, a conductive agent and a binder according to a mass ratio to obtain mixed powder; and
and manufacturing the mixed powder on a current collector with a conductive acid corrosion resistant coating by a dry method or a wet method to obtain the composite positive plate.
7. The method for preparing a composite positive electrode sheet according to claim 6, wherein the conductive corrosion-resistant coating is one of a conductive carbon layer, a conductive polymer layer, a gold layer or a silver layer, and the thickness of the conductive corrosion-resistant coating is 0.01 μm to 10 μm.
8. The method for producing a composite positive electrode sheet according to claim 6, wherein the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder is (68-78): (15-25): (1-3): (2-4).
9. A lithium ion battery comprising the composite positive electrode sheet of any one of claims 1-5.
10. An electronic device comprising the lithium-ion battery of claim 9.
CN202311650632.8A 2023-12-04 2023-12-04 Composite positive electrode plate and preparation method and application thereof Pending CN117542960A (en)

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