CN116995221B - Porous composite negative electrode and preparation method and application thereof - Google Patents

Porous composite negative electrode and preparation method and application thereof Download PDF

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CN116995221B
CN116995221B CN202311269449.3A CN202311269449A CN116995221B CN 116995221 B CN116995221 B CN 116995221B CN 202311269449 A CN202311269449 A CN 202311269449A CN 116995221 B CN116995221 B CN 116995221B
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current collector
active material
porous
electron
rich
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CN116995221A (en
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钟应声
刘娇
焦晓岚
王明辉
陈景新
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Jiangsu Zenio New Energy Battery Technologies Co Ltd
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Jiangsu Zenio New Energy Battery Technologies 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
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    • 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
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    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
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    • 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
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
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    • 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
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
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    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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    • 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
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E60/10—Energy storage using batteries

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Abstract

The invention relates to a porous composite negative electrode, a preparation method and application thereof. The porous composite anode electrode comprises a porous current collector provided with a first active material layer and a second active material layer; a carbon film layer is arranged in the pores of the porous current collector; slurry A of the first active material layer comprises a silicon anode material and a first graphite anode material which are activated by an electron-rich activator. The carbon film layer porous current collector is connected with the active material filling layer of the porous current collector pores, so that the bonding strength of the porous current collector pores and silicon particles is improved, and the conductivity of the active material filling layer is effectively improved; the interface compatibility between the silicon particles and the bonding substance contacted with the silicon particles is improved through the electron-rich activator, the connection capability of the silicon particles and the outside is improved, and the conductive network and the electron transmission capability inside the electrode are improved.

Description

Porous composite negative electrode and preparation method and application thereof
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a porous composite negative electrode, a preparation method and application thereof.
Background
With the gradual maturity of the graphite cathode material industry, the high-end graphite cathode (the gram capacity of practical use reaches 340-360 mAh/g) is very close to the theoretical capacity (372 mAh/g) at present, and the energy density of a battery is severely limited by the relatively low theoretical reversible capacity of the graphite cathode, and the lifting space is very limited. Over the past decade, many researchers have been working on finding alternative high energy density anode materials.
Silicon-based anode materials with high reversible capacity (half cell 1.5V gram capacity can be greater than 1000 mAh/g) are considered as one of the next generation lithium ion battery anode materials that is most promising to replace commercial graphite, likely leading the market in future development. The main development direction of the silicon-based negative electrode material with high reversible capacity is composite silicon-based negative electrode materials such as carbon-coated nano silicon, carbon-coated amorphous silicon, pre-lithiated silicon oxide and the like.
However, no matter what kind of composite silicon-based anode material is, there is a serious volume effect in the battery cycle process, for example, as the cycle number of the battery increases, a plurality of cracks are generated between the silicon particles on the surface of the anode active material layer and the anode active material layer, so that electrical contact is lost, the connection positions of the silicon particles in the anode active material layer, the conductive material, graphite and the like are cracked, the connection capability is reduced, the electron transmission capability of the conductive network in the anode electrode is reduced, and finally the battery cycle is serious.
Disclosure of Invention
In order to solve the technical problems, the invention provides a porous composite negative electrode, and a preparation method and application thereof. According to the invention, the porous composite negative electrode is improved to improve the electrical contact between the active material layer and the silicon particles, reduce the cracking condition of the connection parts of the silicon particles in the active material layer, the conductive material, the graphite and the like, and improve the structural stability of the pole piece and the service life of the battery.
A first object of the present invention is to provide a porous composite anode electrode including a porous current collector provided with a first active material layer and a second active material layer;
a carbon film layer is arranged in the pores of the porous current collector;
the first active material of the first active material layer comprises a silicon anode material and a first graphite anode material which are activated by an electron-rich activating agent; the first active material of the first active material layer is filled in the pores of the porous current collector;
the second active material of the second active material layer includes a second graphite anode material.
The first active material layer comprises a silicon anode material and a first graphite anode material which are activated by an electron-rich activator;
the second active material layer includes a graphite anode material.
In particular embodiments, at least one or more of the following conditions are satisfied:
the thickness of the porous composite negative electrode is 120-350 mu m;
the pore diameter of the inside of the porous current collector is 20-80 mu m;
the thickness of the porous current collector is 20-120 mu m;
the thickness of the first active material layer or the second active material layer on the porous composite anode electrode is independently 2.5-174 μm.
In one embodiment of the invention, the first active material layer further comprises a first binding material, a first conductive material; the second active material layer further includes a second binding material and a second conductive material.
The second object of the present invention is to provide a method for preparing a porous composite anode electrode, comprising the steps of:
mixing a carbon source, a dispersing agent and a catalyst to obtain a carbonaceous slurry, wherein the carbonaceous slurry is uniformly distributed on the surface of a porous current collector, and a carbon film layer is formed on the surface of the porous current collector;
mixing a silicon anode material, a first graphite anode material, a first bonding substance, a first conductive material and water which are activated by using an electron-rich activator to obtain a slurry A;
mixing a second graphite anode material, a second binding substance, a second conductive material and water to obtain slurry B;
and sequentially coating the slurry A and the slurry B on the surface of the porous current collector of the carbon film layer to form a first active material layer and a second active material layer, thereby obtaining the porous composite anode electrode.
In one embodiment of the invention, at least one or more of the following conditions are met:
the carbon source is selected from one or more of polyaniline, polyamide, polyacrylonitrile and polyurethane;
the dispersing agent is selected from one or more of water, acetone, NMP, diethyl ether, propanol and ethanol;
the catalyst is selected from one or more of nickel acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, copper acetylacetonate and zinc acetylacetonate;
the mass ratio of the carbon source, the dispersing agent and the catalyst is (0.1-10): 100: (0.01 to 0.5).
In one embodiment of the present invention, the carbonaceous slurry is uniformly distributed on the surface of the porous current collector by a conventional technical means in the art, such as suction filtration, backlog coating, soaking, etc., and the carbonaceous slurry is not limited to the form; the suction filtration is preferred here, by which the carbonaceous slurry can be uniformly filled into the pores of the porous current collector and the outer surface of the current collector.
In one embodiment of the present invention, the porous current collector is selected from at least one of copper, nickel, titanium, nickel-plated copper, nickel-plated titanium, nickel-plated aluminum, nickel-plated manganese, nickel-plated titanium.
In one embodiment of the invention, one or more of the following conditions are met:
and (3) carrying out electron-rich activation treatment on the silicon anode material subjected to the electron-rich activator activation treatment: mixing the electron-rich activator and the silicon anode material to obtain an activated electron-rich liquid, and heating and activating the liquid at 50-100 ℃ for 10-60 min;
the mass ratio of the composite anode material, the first conductive material and the first binding substance in the slurry A is (85-99): (0.2 to 7): (0.2-7); the composite anode material comprises a silicon anode material subjected to activation treatment by an electron-rich activator and a first graphite anode material;
the mass ratio of the first graphite anode material to the silicon anode material subjected to activation treatment by the electron-rich activator in the composite anode material is (5-99): (1-60).
In one embodiment of the invention, the electron rich activator is selected from one or more of ethylene oxide, propylene oxide, sodium styrene sulfonate, ethyl methacrylate, polymers of hydroxyethyl methacrylate, hydroxyethyl methacrylate monomers.
In one embodiment of the invention, the electron-rich activator is used in an amount of 0.1-8 wt% of the silicon anode material.
The third object of the present invention is to provide a lithium ion battery, which comprises the porous composite negative electrode, or the porous composite negative electrode obtained by the preparation method.
Compared with the prior art, the technical scheme of the invention has the following advantages:
1. according to the invention, a carbon source, a dispersing agent and a catalyst are mixed to obtain carbonaceous slurry, the carbonaceous slurry is mixed in the porous current collector, a carbon film layer grows on the inner surface of the pore of the porous current collector by utilizing the catalysis of the catalyst, the porous current collector of the carbon film layer is connected with the active material layer of the pore of the porous current collector, meanwhile, the bonding strength of the pore of the porous current collector and silicon particles is improved, and the conductivity of the active material layer and the electrode can be effectively improved.
2. According to the invention, the electron-rich activator is used for activating the silicon anode material particles at 50-100 ℃, the electron-rich activator is used for modifying the surfaces of the silicon particles, and ionic groups or high-polarity groups (the ionic groups contain-O- (ether oxygen bonds)) are formed on the surfaces of the anode silicon particles, so that the ionic conductivity of the ionic groups is higher and the ionic groups are compatible with Li + Has good interfacial compatibility and stability, and Li is treated by the method + Strong affinity to promote lithium ion transfer. In addition, the electron-rich activator improves interface compatibility between silicon particles and silicon particles, and between silicon particles and a bonding substance, and the connection capability of silicon particles and the outside is increased, and the conductive network and electron transport capability inside the electrode are improved.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which,
FIG. 1 is a schematic cross-sectional view of a porous composite negative electrode of the present invention;
FIG. 2 is an SEM of a porous current collector of a carbon-containing film of the present invention;
description of the specification reference numerals: 1. a porous current collector; 2. a carbon film layer; 3. a first active material layer; 4. a second active material layer.
Detailed Description
In order to solve the technical problems pointed out in the background art, the invention provides a porous composite negative electrode and a preparation method thereof.
The invention is realized by the following scheme:
the invention provides a porous composite anode electrode, which comprises a porous current collector, wherein the porous current collector is provided with a first active material layer and a second active material layer;
a carbon film layer is arranged in the pores of the porous current collector;
the first active material of the first active material layer comprises a silicon anode material and a first graphite anode material which are activated by an electron-rich activating agent; the first active material is filled in pores of the porous current collector;
the second active material of the second active material layer includes a second graphite anode material.
Specifically, the porous composite anode electrode comprises a carbon film layer in the pores of a porous current collector, and the surface of the porous current collector can be partially or completely provided with the carbon film layer; and filling the first active material on the surface of the carbon film layer of the current collector until the pores are completely filled, forming a first active material layer, and arranging a second active material layer on the first active material layer to finally obtain the porous composite anode electrode.
In particular embodiments, at least one or more of the following conditions are satisfied:
the thickness of the porous composite negative electrode is 120-350 mu m; the thickness of the porous composite anode electrode is 120-260 μm, for example, the thickness is not equal in 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, 155 μm, 160 μm, 180 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm;
the pore diameter of the inside of the porous current collector is 20-80 mu m;
the thickness of the porous current collector is 20-120 mu m;
the thickness of the first active material layer or the second active material layer on the porous composite anode electrode is independently 2.5-174 μm.
In a specific embodiment, the first active material layer further includes a first binding material, a first conductive material; the second active layer further comprises a second binding substance, a second conductive material.
The invention also provides a preparation method of the porous composite negative electrode, which comprises the following steps:
mixing a carbon source, a dispersing agent and a catalyst to obtain a carbonaceous slurry, wherein the carbonaceous slurry is uniformly distributed on the surface of a porous current collector in a suction filtration mode, a backlog coating or soaking mode and the like to realize uniform distribution, and a carbon film layer is formed on the surface of the porous current collector;
mixing the silicon anode material, the first graphite anode material, the first bonding substance, the first conductive material and water which are activated by using an electron-rich activator until the solid content is 40-70%, and stirring and mixing for 120-420 min under vacuum to obtain slurry A;
mixing a second graphite anode material, a second binding substance, a second conductive material and water, adding water, mixing to adjust the solid content to 40-70%, and stirring and mixing under vacuum for 120-420 min to obtain slurry B;
and sequentially coating the slurry A and the slurry B on the surface of the porous current collector of the carbon film layer to form a first active material layer and a second active material layer, and drying and then pressing at 80-120 ℃ to obtain the porous composite anode electrode.
Specifically, the method comprises the following steps: the slurry A is coated on the surface of the porous current collector, the pores are filled with the slurry A through seepage to form a first active material layer filled in the pores, and the slurry B is coated on the first active material layer to form an external active material layer of the porous current collector.
In a specific embodiment, the carbon source has an areal density of 10-80 g/m on the porous current collector 2 。
In particular embodiments, at least one or more of the following conditions are satisfied:
the carbon source is selected from one or more of polyaniline, polyamide, polyacrylonitrile and polyurethane;
the dispersing agent is selected from one or more of water, acetone, NMP, diethyl ether, propanol and ethanol;
the catalyst is selected from one or more of nickel acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, copper acetylacetonate and zinc acetylacetonate;
the mass ratio of the carbon source, the dispersing agent and the catalyst is (0.1-10): 100: (0.01 to 0.5).
In a specific embodiment, the porous current collector is selected from at least one of copper, nickel, titanium, nickel-plated copper, nickel-plated titanium, nickel-plated aluminum, nickel-plated manganese, nickel-plated titanium. Further, copper and nickel-plated copper are preferable.
In a specific embodiment, the carbon film layer is a carbon source, the carbon source is subjected to suction filtration and dispersed in the pores inside the porous current collector, and the catalyst catalyzes the carbon source to form a stable carbon film layer in the pores inside the porous current collector at a high temperature of 300-900 ℃.
In the specific embodiment, in the preparation of the carbon film layer, after the carbonaceous slurry is uniformly distributed on the surface of the porous current collector in a suction filtration mode, the carbon film layer further comprises high-temperature treatment, wherein the high-temperature treatment is carried out for 1-6 hours at 300-900 ℃ in an inert atmosphere environment. The inert atmosphere gas is nitrogen and/or argon.
In particular embodiments, one or more of the following conditions are met:
and (3) carrying out electron-rich activation treatment on the silicon anode material subjected to the electron-rich activator activation treatment: mixing the electron-rich activator and the silicon anode material to obtain an activated electron-rich liquid, and heating and activating the liquid at 50-100 ℃ for 10-60 min; activation refers to activation of the surface interface of the silicon anode material by using an electron-rich activator.
The mass ratio of the composite anode material, the first conductive material and the first binding substance in the slurry A is (85-99): (0.2 to 7): (0.2-7); the composite anode material comprises a silicon anode material subjected to activation treatment by an electron-rich activator and a first graphite anode material;
the mass ratio of the first graphite anode material to the silicon anode material subjected to activation treatment by the electron-rich activator in the composite anode material is (5-99): (1-60).
In specific embodiments, the electron rich activator is selected from one or more of ethylene oxide, propylene oxide, sodium styrene sulfonate, ethyl methacrylate, polymers of hydroxyethyl methacrylate, hydroxyethyl methacrylate monomers. The ionic group of the electron-rich activator has higher ionic conductivity, higher dielectric constant (better conductivity), wider electrochemical stability window, is rich in-C-C, -C-O-and the like, has good interfacial compatibility with lithium ions and better stability, and utilizes the ionic group to carry out Li + Strong affinity to promote lithium ion transfer.
In a specific embodiment, the dosage of the electron-rich activator is 0.1-8wt% of the silicon anode material.
In a specific embodiment, the first graphite anode material or the second graphite anode material is independently selected from one or more graphite anode materials obtained by graphitizing needle coke, asphalt tar and petroleum coke, or one or more graphite anode materials obtained by coating, oxidizing, reducing natural graphite, and the like.
In a specific embodiment, the silicon negative electrode material is one or more of a silane deposition type silicon-carbon negative electrode material, a carbon coated nano silicon negative electrode material, a pre-lithiated silicon-oxygen negative electrode material, a pre-magnesia silicon-oxygen negative electrode material and a carbon coated silicon-oxygen material;
in specific embodiments, the first binding substance and the second binding substance are independently selected from one or more of polyvinylidene fluoride, carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium carboxymethyl cellulose, polyimide, polyurethane, guar gum, polyethylene glycol, polyacrylic acid, lithium acrylate, styrene butadiene rubber and sodium alginate;
in a specific embodiment, the first conductive material and the second conductive material are independently selected from one or more of conductive carbon black, conductive acetylene black, conductive graphite, graphene, carbon micro-nano linear conductive material, carbon nanotube, carbon micro-tube, nano silver, nano nickel powder, sponge iron powder and sponge copper powder.
In a specific embodiment, the density of the filled first active material layer or the outer second active material layer of the obtained porous composite anode electrode is independently 0.003-0.042 g/cm 2 . Further, the area density of the active material layer or the external active material layer filled on the porous composite anode electrode is 0.008-0.036 g/cm 2 For example at 0.009g/cm 2 、0.010g/cm 2 、0.012g/cm 2 、0.015g/cm 2 、0.016g/cm 2 、0.017g/cm 2 、0.018g/cm 2 、0.020g/cm 2 、0.022g/cm 2 、0.024g/cm 2 、0.026g/cm 2 、0.027g/cm 2 、0.028g/cm 2 、0.030g/cm 2 、0.032g/cm 2 、0.035g/cm 2 、0.036g/cm 2 And not equal.
The invention also provides a lithium ion battery, which comprises the porous composite negative electrode or the porous composite negative electrode obtained by the preparation method.
In a specific embodiment, the lithium ion battery is prepared by the following method: and (3) conveying the porous composite negative electrode, the isolating film and the positive electrode to a winding machine, winding to obtain an electrode group with a winding structure, adhering a fixed pole piece and a diaphragm, welding lugs of the negative electrode and the positive electrode to obtain a bare cell, packaging the cell into a cell shell, drying, injecting electrolyte, packaging, forming and separating the cell to obtain the battery.
Further, the positive electrode comprises a positive electrode material, a conductive material and a binding substance.
Further, the positive electrode material in the positive electrode is selected from any one of lithium cobaltate, lithium manganate, ternary nickel cobalt manganese lithium, ternary nickel cobalt aluminum lithium, nickel lithium manganate, lithium iron phosphate or lithium manganese iron phosphate.
Further, the positive electrode material, the conductive material and the bonding substance in the positive electrode respectively comprise 80-99.8wt%, 0.1-10wt% and 0.1-10wt%.
Further, the conductive material in the positive electrode is one or more of conductive carbon black, conductive acetylene black, conductive graphite, graphene, carbon micro-nano linear conductive material, carbon nanotube, carbon micro-tube, nano silver, nano nickel powder, sponge iron powder and sponge copper powder.
Further, the binding substance in the positive electrode is one or more of polyvinylidene fluoride, carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium carboxymethyl cellulose, polyimide, polyurethane, guar gum, polyethylene glycol, polyacrylic acid, lithium acrylate, styrene butadiene rubber and sodium alginate.
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
Example 1
The embodiment provides a preparation method of a porous composite negative electrode, which comprises the following steps:
s10: dispersing a ground catalyst nickel acetylacetonate in a dispersing agent NMP (N-methyl pyrrolidone) by ultrasonic, adding a carbon source polyaniline to obtain a suspension, carrying out suction filtration on the suspension into a porous current collector copper foil, accommodating the carbon source polyaniline in the carbonaceous slurry by utilizing pores in the porous copper foil, drying to remove the dispersing agent, and uniformly dispersing the carbon source and the catalyst in the pores in the porous current collector. And the porous current collector is sent to 450 ℃ under the nitrogen environment and kept for 4 hours, then cooled to room temperature, and a carbon film is formed inside the porous copper foil, so that the porous current collector of the carbon film layer is obtained; wherein, the mass ratio of the carbon source, the dispersing agent and the catalyst is 3:100:0.2, and the porous current collector with the carbon film layer formed is characterized, and the result is shown in fig. 2.
S20: (1) the pre-lithiated silicon oxide negative electrode material and the graphite negative electrode material (graphite negative electrode material graphitized by petroleum coke) which are subjected to activation treatment by the electron-rich activating agent are prepared according to the mass ratio of 9:91, mixing to obtain a composite anode material, mixing the composite anode material, a binding substance (20 wt% of polyacrylic acid, 20wt% of sodium carboxymethyl cellulose and 60wt% of styrene-butadiene rubber) and a conductive material (96 wt% of conductive carbon black and 4wt% of carbon nano tubes) in a stirring tank, adding deionized water to adjust the solid content to 49%, and stirring and uniformly mixing under vacuum with the viscosity of 3 Pa.s-100 KPa to obtain slurry A.
(2) The graphite cathode material (graphite cathode material graphitized by petroleum coke), bonding substances (20 wt% of polyacrylic acid, 20wt% of sodium carboxymethyl cellulose and 60wt% of styrene-butadiene rubber) and conductive materials (96 wt% of conductive carbon black and 4wt% of carbon nano tubes) are mixed in a stirring tank, and deionized water is added to adjust the solid content to 51%, the viscosity to 3Pa.s and the stirring is carried out under the vacuum degree of-100 KPa for uniformly mixing for 350min, so as to obtain slurry B.
S20:
and (3) activating treatment: the electron-rich activator propylene oxide and the pre-lithiated silica anode material (lithium content 3wt%, si/O atomic ratio 41:32, dv50=7.5 μm) are placed in a heating device to obtain an activated electron-rich liquid, and the activated electron-rich liquid is activated at 85 ℃ for 25min, and the propylene oxide content is 1.5wt% of the pre-lithiated silica anode material.
The mass ratio of the composite anode material, the conductive material and the bonding substance of the slurry A is 96:1.5:2.5.
the mass ratio of the graphite anode material, the conductive material and the bonding substance of the slurry B is 96:1.5:2.5.
s30: coating slurry A on the porous current collector pores obtained in step S10 to form a first active material filling layer, coating slurry B on the first active material filling layer to form an external second active material layer of the porous current collector at two sides, drying at 95deg.C, and pressing to obtain a first active material filling layer with a density of 0.004g/cm 2 The density of the external second active material layer is 0.003g/cm 2 A porous composite negative electrode with a thickness of 168 μm.
Example 2
The embodiment provides a preparation method of a porous composite negative electrode, which comprises the following steps:
s10: dispersing a ground catalyst nickel acetylacetonate in a dispersing agent NMP (N-methyl pyrrolidone) by ultrasonic, adding a carbon source polyaniline to obtain a suspension, carrying out suction filtration on the suspension into a porous current collector copper foil, accommodating the carbon source polyaniline in the carbonaceous slurry by utilizing pores in the porous copper foil, drying to remove the dispersing agent, and uniformly dispersing the carbon source and the catalyst in the pores in the porous current collector. And the porous current collector is sent to 450 ℃ under the nitrogen environment and kept for 4 hours, then cooled to room temperature, and a carbon film is formed inside the porous copper foil, so that the porous current collector of the carbon film layer is obtained; wherein, the mass ratio of the carbon source, the dispersing agent and the catalyst is 3:100: 0.2.
S20: (1) the pre-lithiated silicon oxide negative electrode material and the graphite negative electrode material (graphite negative electrode material graphitized by petroleum coke) which are subjected to activation treatment by the electron-rich activating agent are prepared according to the mass ratio of 9:91, mixing to obtain a composite anode material, mixing the composite anode material, a bonding substance (20 wt% of polyacrylic acid, 20wt% of sodium carboxymethyl cellulose and 60wt% of styrene-butadiene rubber) and a conductive material (96 wt% of conductive carbon black and 4wt% of carbon nano tubes) in a stirring tank, adding deionized water to adjust the solid content to 49%, and stirring and uniformly mixing under vacuum with the viscosity of 3 Pa.s-100 KPa to obtain slurry A;
(2) mixing graphite cathode material (graphite cathode material graphitized by petroleum coke), bonding substance (20 wt% polyacrylic acid, 20wt% sodium carboxymethyl cellulose, 60wt% styrene-butadiene rubber) and conductive material (96 wt% conductive carbon black, 4wt% carbon nano tube) in a stirring tank, adding deionized water to adjust the solid content to 51%, and stirring and uniformly mixing at the viscosity of 3 Pa.s-100 KPa vacuum degree for 350min to obtain slurry B;
s20:
and (3) activating treatment: the electron-rich activator propylene oxide and the pre-lithiated silica anode material (lithium content 3wt%, si/O atomic ratio 41:32, dv50=7.5 μm) are placed in a heating device to obtain an activated electron-rich liquid, and the activated electron-rich liquid is activated at 85 ℃ for 25min, and the propylene oxide content is added to be 3.0wt% of the pre-lithiated silica anode material.
The mass ratio of the composite anode material, the conductive material and the bonding substance of the slurry A is 96:1.5:2.5.
the mass ratio of the graphite anode material, the conductive material and the bonding substance of the slurry B is 96:1.5:2.5.
s30: applying slurry A to the porous current collector pores obtained in step S10 to form a first active material-filled layer, and applying slurry BForming an outer second active material layer of the porous current collector on the first active material layer, drying at 95deg.C, and pressing to obtain a second active material layer with a density of 0.004g/cm 2 The external active material layer density is 0.003g/cm 2 A porous composite negative electrode with a thickness of 168 μm.
Example 3
The embodiment provides a preparation method of a porous composite negative electrode, which comprises the following steps:
s10: dispersing a ground catalyst nickel acetylacetonate in a dispersing agent NMP (N-methyl pyrrolidone) by ultrasonic, adding a carbon source polyacrylonitrile to obtain a suspension, carrying out suction filtration on the suspension into a porous current collector copper foil, accommodating the carbon source polyacrylonitrile in the carbonaceous slurry by utilizing pores in the porous copper foil, drying to remove the dispersing agent, and uniformly dispersing the carbon source and the catalyst in the pores in the porous current collector. And the porous current collector is sent to 450 ℃ under the nitrogen environment and kept for 4 hours, then cooled to room temperature, and a carbon film is formed inside the porous copper foil, so that the porous current collector of the carbon film layer is obtained; wherein, the mass ratio of the carbon source, the dispersing agent and the catalyst is 4:100:0.3 mixing.
S20: (1) the pre-lithiated silicon oxygen negative electrode material and the graphite negative electrode material (the graphite negative electrode material graphitized by petroleum coke) which are subjected to the activation treatment by the electron-rich activating agent are prepared according to the mass ratio of 27:73, mixing to obtain a composite anode material, mixing the composite anode material, a binding substance (10 wt% polyacrylic acid, 20wt% sodium carboxymethyl cellulose and 70wt% styrene-butadiene rubber) and a conductive material (96 wt% conductive carbon black and 4wt% carbon nano tube) in a stirring tank, adding deionized water to adjust the solid content to 50%, and stirring and uniformly mixing under vacuum with the viscosity of 3 Pa.s-100 KPa to obtain slurry A;
(2) mixing graphite cathode material (graphite cathode material graphitized by petroleum coke), bonding substance (10 wt% polyacrylic acid, 20wt% sodium carboxymethyl cellulose, 70wt% styrene-butadiene rubber) and conductive material (96 wt% conductive carbon black, 4wt% carbon nano tube) in a stirring tank, adding deionized water to adjust the solid content to 53%, and stirring at the viscosity of 3 Pa.s-100 KPa vacuum degree for uniformly mixing for 350min to obtain slurry B;
s20:
and (3) activating treatment: the electron-rich activator ethylene oxide and the pre-lithiated silica anode material (lithium content 3wt%, si/O atomic ratio 41:32, dv50=7.5 μm) are placed in a heating device to obtain an activated electron-rich liquid, and the activated electron-rich liquid is activated at 85 ℃ for 25min, and the ethylene oxide content is 1.5wt% of the pre-lithiated silica anode material is added.
The mass ratio of the composite anode material, the conductive material and the bonding substance of the slurry A is 95:1.5:3.5.
the mass ratio of the graphite anode material, the conductive material and the bonding substance of the slurry B is 95:1.5:3.5.
s30: coating slurry A on the porous current collector pores obtained in step S10 to form a first active material filling layer, coating slurry B on the first active material filling layer to form an external second active material layer of the porous current collector at two sides, drying at 95deg.C, and pressing to obtain a first active material filling layer with a density of 0.004g/cm 2 The density of the external second active material layer is 0.005g/cm 2 A porous composite negative electrode with a thickness of 180 μm.
Example 4
The embodiment provides a preparation method of a porous composite negative electrode, which comprises the following steps:
s10: dispersing the ground catalyst nickel acetylacetonate and ultrasonic in a dispersing agent NMP, adding a carbon source polyacrylonitrile to obtain a suspension, carrying out suction filtration to the inside of a porous current collector copper foil, utilizing pores in the porous copper foil to contain the carbon source polyacrylonitrile in the carbonaceous slurry, drying to remove the dispersing agent, and uniformly dispersing the carbon source and the catalyst in the pores in the inside of the porous current collector. And the porous current collector is sent to 450 ℃ under the nitrogen (argon) environment and kept for 4 hours, then cooled to room temperature, and a carbon film is formed inside the porous copper foil, so that the porous current collector of the carbon film layer is obtained; wherein, the mass ratio of the carbon source, the dispersing agent and the catalyst is 4:100: 0.3.
S20: (1) the pre-lithiated silicon oxygen negative electrode material and the graphite negative electrode material (the graphite negative electrode material graphitized by petroleum coke) which are subjected to the activation treatment by the electron-rich activating agent are prepared according to the mass ratio of 27:73, mixing to obtain a composite anode material, mixing the composite anode material, a binding substance (10 wt% of polyacrylic acid, 20wt% of sodium carboxymethyl cellulose and 70wt% of styrene-butadiene rubber) and a conductive material (96 wt% of conductive carbon black and 4wt% of carbon nano tubes) in a stirring tank, adding deionized water to adjust the solid content to 48%, and stirring and uniformly mixing under vacuum with the viscosity of 3 Pa.s-100 KPa to obtain slurry A;
(2) mixing graphite cathode material (graphite cathode material graphitized by petroleum coke), bonding substance (10 wt% polyacrylic acid, 20wt% sodium carboxymethyl cellulose, 70wt% styrene-butadiene rubber) and conductive material (96 wt% conductive carbon black, 4wt% carbon nano tube) in a stirring tank, adding deionized water to adjust the solid content to 53%, and stirring at the viscosity of 3 Pa.s-100 KPa vacuum degree for uniformly mixing for 350min to obtain slurry B;
s20:
and (3) activating treatment: the electron-rich activator ethylene oxide and the pre-lithiated silica anode material (lithium content 3wt%, si/O atomic ratio 41:32, dv50=7.5 μm) are placed in a heating device to obtain an activated electron-rich liquid, and the activated electron-rich liquid is activated at 85 ℃ for 25min, and the ethylene oxide content is added to be 3.0wt% of the pre-lithiated silica anode material.
The mass ratio of the composite anode material, the conductive material and the bonding substance of the slurry A is 95:1.5:3.5.
the mass ratio of the graphite anode material, the conductive material and the bonding substance of the slurry B is 95:1.5:3.5.
s30: coating slurry A on the porous current collector pores obtained in step S10 to form a first active material filling layer, coating slurry B on the first active material filling layer to form an external second active material layer of the porous current collector at two sides, drying at 95deg.C, and pressing to obtain a first active material filling layer with a density of 0.004g/cm 2 The density of the external second active material layer is 0.005g/cm 2 A porous composite negative electrode with a thickness of 180 μm.
Application of porous composite negative electrodes of examples 1-4:
the porous composite negative electrode, the polypropylene isolating film and the positive electrode (95.6wt% of nickel cobalt lithium manganate, 1.5wt% of conductive material (60 wt% of conductive carbon black and 40wt% of carbon nano tube) and 1.5wt% of bonding substance polyvinylidene fluoride) of the embodiment are sent to a winding machine to be wound to obtain an electrode pole group with a winding structure, the electrode pole group is fixed by rubberizing and the membrane is fixed, the electrode lugs of the negative electrode and the positive electrode are welded to obtain a bare cell, the cell is provided with a cell shell, and the battery shell is vacuum-dried, injected with electrolyte, packaged, formed and separated to obtain the lithium ion battery.
Comparative example 1 (similar to example 1, except that the porous current collector in which the carbon film layer was not formed in S10)
The comparative example provides a preparation method of a porous composite negative electrode, which comprises the following steps:
s10: a carbon film is not formed inside the porous copper foil, namely the porous current collector without the carbon film layer;
s20: (1) the pre-lithiated silicon oxide negative electrode material and the graphite negative electrode material (graphite negative electrode material graphitized by petroleum coke) which are subjected to activation treatment by the electron-rich activating agent are prepared according to the mass ratio of 9:91, mixing to obtain a composite anode material, mixing the composite anode material, a binding substance (20 wt% of polyacrylic acid, 20wt% of sodium carboxymethyl cellulose and 60wt% of styrene-butadiene rubber) and a conductive material (96 wt% of conductive carbon black and 4wt% of carbon nano tubes) in a stirring tank, adding deionized water to adjust the solid content, and stirring and uniformly mixing under vacuum to obtain slurry A;
(2) mixing graphite cathode material (graphite cathode material graphitized by petroleum coke), bonding substance (20 wt% polyacrylic acid, 20wt% sodium carboxymethyl cellulose and 60wt% styrene-butadiene rubber) and conductive material (96 wt% conductive carbon black and 4wt% carbon nano tube) in a stirring tank, adding deionized water to adjust the solid content to 51%, stirring under-100 KPa vacuum degree, and uniformly mixing for 350min to obtain slurry B;
s20:
and (3) activating treatment: the electron-rich activator propylene oxide and the pre-lithiated silica anode material are placed in heating equipment to obtain activated electron-rich liquid, the activation is carried out for 25min at 85 ℃, and the content of the propylene oxide is 1.5wt% of the pre-lithiated silica anode material.
The mass ratio of the composite anode material, the conductive material and the bonding substance of the slurry A is 96:1.5:2.5.
the mass ratio of the graphite anode material, the conductive material and the bonding substance of the slurry B is 96:1.5:2.5.
s30: coating slurry A on the porous current collector pores in step S1 to form a first active material filling layer, coating slurry B on the first active material filling layer to form an external second active material layer of the porous current collector at two sides, drying at 95deg.C, and repressing to obtain a first active material filling layer with a density of 0.005g/cm 2 The density of the external second active material layer is 0.003g/cm 2 A porous negative electrode with a thickness of 168 μm.
Comparative example 2 (similar to example 1, except that the pre-lithiated silicon oxygen negative electrode material in S20 was not subjected to electron-rich activation treatment)
The comparative example provides a preparation method of a porous composite negative electrode, which comprises the following steps:
s10: dispersing a ground catalyst nickel acetylacetonate in a dispersing agent NMP (N-methyl pyrrolidone) by ultrasonic, adding a carbon source polyaniline to obtain a suspension, carrying out suction filtration on the suspension into a porous current collector copper foil, accommodating carbonaceous materials in carbonaceous slurry by utilizing pores in the porous copper foil, drying to remove the dispersing agent, and uniformly dispersing the carbon source and the catalyst in the pores in the porous current collector. And the porous current collector is sent to 450 ℃ under the nitrogen environment and kept for 4 hours, then cooled to room temperature, and a carbon film is formed inside the porous copper foil, so that the porous current collector of the carbon film layer is obtained; wherein, the mass ratio of the carbon source, the dispersing agent and the catalyst is 3:100: 0.2.
S20: (1) the pre-lithiated silicon oxide negative electrode material and the graphite negative electrode material (graphite negative electrode material graphitized by petroleum coke) are prepared according to the mass ratio of 9:91, mixing to obtain a composite anode material, mixing the composite anode material, a binding substance (20% polyacrylic acid, 20% sodium carboxymethyl cellulose and 60% styrene-butadiene rubber) and a conductive material (96% conductive carbon black and 4% carbon nano tubes) in a stirring tank, adding deionized water to adjust the solid content, and stirring and mixing under vacuum to obtain slurry A.
(2) The graphite cathode material (graphite cathode material graphitized by petroleum coke), bonding substances (20 wt% of polyacrylic acid, 20wt% of sodium carboxymethyl cellulose and 60wt% of styrene-butadiene rubber) and conductive materials (96 wt% of conductive carbon black and 4wt% of carbon nano tubes) are mixed in a stirring tank, deionized water is added to adjust the solid content to 51%, and the mixture is stirred and uniformly mixed for 350min under the vacuum degree of 100KPa to obtain slurry B.
S20:
the mass ratio of the composite anode material, the conductive material and the bonding substance of the slurry A is 96:1.5:2.5.
the mass ratio of the graphite anode material, the conductive material and the bonding substance of the slurry B is 96:1.5:2.5.
s30: coating slurry A on the porous current collector pores obtained in step S10 to form a first active material filling layer, coating slurry B on the first active material filling layer to form an external active material layer of the porous current collector at two sides, drying at 95deg.C, and pressing to obtain active material filling layer with a density of 0.004g/cm 2 The external active material layer density is 0.003g/cm 2 A porous negative electrode with a thickness of 168 μm.
Comparative example 3 (similar to example 1, except that the pre-lithiated silicon oxygen negative electrode material in S20 was treated with ethanol)
The comparative example provides a preparation method of a porous composite negative electrode, which comprises the following steps:
s10: the mass ratio of the carbon source to the dispersing agent to the catalyst is 3:100: and 0.2, mixing to obtain carbonaceous slurry, and carrying out suction filtration on the carbonaceous slurry on the porous copper foil. Grinding catalyst nickel acetylacetonate, dispersing in dispersing agent NMP by ultrasonic, adding carbon source polyaniline to obtain suspension, suction filtering to the interior of porous current collector, drying to remove dispersing agent by using carbonaceous material in pore-containing slurry, dispersing carbon source and catalyst in the pores of porous current collector. And (3) sending the copper foil to 450 ℃ under a nitrogen environment, keeping the temperature for 4 hours, and cooling the copper foil to room temperature, wherein a carbon film is formed inside the porous copper foil, and the carbon film is the porous current collector of the carbon film layer.
S20: the ethanol-treated pre-lithiated silica anode material and the graphite anode material (petroleum coke graphitized graphite anode material) are prepared according to the mass ratio of 9:91, mixing to obtain a composite anode material, mixing the composite anode material, a binding substance (20 wt% of polyacrylic acid, 20wt% of sodium carboxymethyl cellulose and 60wt% of styrene-butadiene rubber) and a conductive material (96 wt% of conductive carbon black and 4wt% of carbon nano tubes) in a stirring tank, adding deionized water to adjust the solid content, and stirring and mixing under vacuum to obtain slurry A.
Mixing graphite cathode material (graphite cathode material graphitized by petroleum coke), bonding substance (20 wt% polyacrylic acid, 20wt% sodium carboxymethyl cellulose and 60wt% styrene-butadiene rubber) and conductive material (96 wt% conductive carbon black and 4% carbon nano tube) in a stirring tank, adding deionized water to adjust the solid content to 51%, stirring under-100 KPa vacuum degree, and uniformly mixing for 350min to obtain slurry B;
s20:
ethanol-treated pre-lithiated silicon oxide negative electrode material: and placing the ethanol and the pre-lithiated silica anode material into heating equipment to obtain an ethanol-treated pre-lithiated silica anode material, and activating the material at 85 ℃ for 25min, wherein the amount of ethanol added is 1.5wt% of the pre-lithiated silica anode material.
The mass ratio of the composite anode material, the conductive material and the bonding substance of the slurry A is 96:1.5:2.5.
the mass ratio of the graphite anode material, the conductive material and the bonding substance of the slurry B is 96:1.5:2.5.
s30: coating slurry A on the porous current collector pores obtained in step S10 to form a first active material filling layer, coating slurry B on the first active material filling layer to form an external second active material layer of the porous current collector at two sides, drying at 95deg.C, and pressing to obtain a first active material filling layer with a density of 0.004g/cm 2 The density of the external second active material layer is 0.003g/cm 2 A porous negative electrode with a thickness of 168 μm.
Application of porous composite negative electrodes of comparative examples 1 to 3:
the porous negative electrode, the polypropylene isolating film and the positive electrode (95.6wt% of nickel cobalt lithium manganate, 1.5wt% of conductive material (60 wt% of conductive carbon black and 40wt% of carbon nano tube) and 1.5wt% of bonding substance polyvinylidene fluoride) of the comparative example are sent to a winding machine to be wound to obtain an electrode pole group with a winding structure, the electrode pole group is fixed by rubberizing and the membrane is fixed, the electrode lugs of the negative electrode and the positive electrode are welded to obtain a bare cell, the cell is provided with a cell shell, and the battery shell is vacuum-dried, injected with electrolyte, packaged, formed and separated to obtain the lithium ion battery.
(1) Negative electrode resistance before cycling
The negative electrode prepared in the examples and the comparative examples is cut into long-strip electrodes with the length of 50+/-2 mm and the width of 20+/-2 mm, then the positive electrode post and the negative electrode post of the diaphragm resistance meter are used for contacting the upper surface and the lower surface of the negative electrode, the resistance of the negative electrode is tested by the meter, the test result is recorded, and the average value of the resistance is taken as the resistance of the negative electrode of the corresponding examples and the comparative examples.
(2) Examples, comparative lithium ion battery cycling
At 45 ℃, the lithium ion batteries obtained in the examples and the comparative examples are charged and discharged at 1C/1C within a voltage range of 2.75-4.25V (the battery after capacity division is fully charged at 1C to 4.25V, the constant voltage charge at 4.25V is carried out until the current is less than or equal to 0.05C, then the discharge at 1C to 2.75V is carried out, and the battery stands for 10min, so that the charge and discharge are circulated), and the capacity of the lithium ion battery is attenuated to 80% corresponding circulation turns.
(3) Negative electrode surface condition at capacity decay to 80%
In the examples and comparative examples, the lithium ion battery having a capacity of 80% was disassembled, the negative electrode was taken out, washed with dimethyl carbonate, dried to obtain a negative electrode having a capacity of 80%, and then the surface cracking of the negative electrode was observed by using an electron microscope.
(4) Negative electrode resistance at capacity fade to 80%
In the embodiment and the comparative lithium ion battery with the capacity attenuated to 80%, the negative electrode is disassembled, taken out, washed by dimethyl carbonate, dried to obtain the negative electrode with the capacity attenuated to 80%, the negative electrode is cut into strips with the length of 50+/-2 mm and the width of 20+/-2 mm, then the positive electrode post and the negative electrode post of a diaphragm resistance meter are used for contacting the upper surface and the lower surface of the negative electrode, the resistance of the negative electrode is tested by the instrument, the test result is recorded, and the average value of the resistance of the negative electrode of the corresponding embodiment and the comparative example is taken.
TABLE 1 negative electrode resistance for examples, comparative examples
Table 2 cycling conditions of lithium ion batteries of examples and comparative examples
TABLE 3 surface conditions of the negative electrode of examples and comparative examples
。
Compared with the carbon film layer of the porous current collector of the comparative example 1, the resistance of the anode electrode before and after circulation is increased by 10.2mΩ, 11.2mΩ, 10.4mΩ and 11.6mΩ, while the resistance of the anode electrode of the comparative example 1 is increased by 16.6mΩ, the resistance increase is higher, and the joint of the silicon particles and the graphite on the surface of the anode electrode has more cracks, the carbon film layer formed by the pores in the porous current collector improves the bonding strength of the pores of the porous current collector and the silicon particles, and the conductivity of the anode electrode can be effectively improved; compared with comparative examples 2 and 3, examples 1 to 4 are subjected to the activation treatment of the electron-rich activator, the resistance of the negative electrode is reduced, the surface condition of the negative electrode is better, and the cycle number is higher when the capacity is attenuated to 80%, so that the interface compatibility between the silicon particles and the interface compatibility between the silicon particles and the bonding material are facilitated, the connection capability between the silicon particles and the outside is improved, and the conductive network and the electron transmission capability inside the electrode are improved.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications will be apparent to persons skilled in the art from the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (10)

1. The porous composite negative electrode is characterized by comprising a porous current collector, wherein a carbon film layer is arranged in the pores of the porous current collector, and a first active material layer and a second active material layer are arranged on the surface of the carbon film layer;
mixing a carbon source, a dispersing agent and a catalyst to obtain carbonaceous slurry, wherein the carbonaceous slurry is uniformly distributed in the pores of the porous current collector; in an inert atmosphere, forming a carbon film layer by the carbonaceous slurry distributed in the pores of the porous current collector under the heating condition of 300-900 ℃;
the first active material of the first active material layer comprises a silicon anode material activated by an electron-rich activator and a first graphite anode material; the first active material is filled in pores of the porous current collector;
the second active material of the second active material layer comprises a second graphite anode material;
the electron-rich activator is selected from one or more of ethylene oxide, propylene oxide, sodium styrene sulfonate, ethyl methacrylate, hydroxyethyl methacrylate polymer and hydroxyethyl methacrylate monomer;
the activation treatment refers to heating and activating for 10-60 min at 50-100 ℃.
2. The porous composite anode according to claim 1, wherein at least one or more of the following conditions are satisfied:
the thickness of the porous composite anode is 120-350 mu m;
the pore diameter of the inside of the porous current collector is 20-80 mu m;
the thickness of the porous current collector is 20-120 mu m;
the thickness of the first active material layer or the second active material layer on the porous composite negative electrode is independently 2.5-174 μm.
3. The porous composite anode according to claim 1, wherein the first active material layer further comprises a first binder material, a first conductive material; the second active material layer further includes a second binding material and a second conductive material.
4. A method for producing a porous composite anode according to any one of claims 1 to 3, comprising the steps of:
mixing a carbon source, a dispersing agent and a catalyst to obtain a carbonaceous slurry, wherein the carbonaceous slurry is uniformly distributed in the pores of the porous current collector, and a carbon film layer is formed in the pores of the porous current collector;
mixing a silicon anode material, a first graphite anode material, a first bonding substance, a first conductive material and water which are activated by using an electron-rich activator to obtain a slurry A;
mixing a second graphite anode material, a second binding substance, a second conductive material and water to obtain slurry B;
and sequentially coating the slurry A and the slurry B on the surface of the porous current collector of the carbon film layer to form a first active material layer and a second active material layer, thereby obtaining the porous composite anode.
5. The method of claim 4, wherein at least one or more of the following conditions are satisfied:
the carbon source is selected from one or more of polyaniline, polyamide, polyacrylonitrile and polyurethane;
the dispersing agent is selected from one or more of water, acetone, NMP, diethyl ether, propanol and ethanol;
the catalyst is selected from one or more of nickel acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, copper acetylacetonate and zinc acetylacetonate;
the mass ratio of the carbon source, the dispersing agent and the catalyst is (0.1-10): 100: (0.01 to 0.5).
6. The method of preparing according to claim 4, wherein the porous current collector is at least one selected from the group consisting of copper, nickel, titanium, nickel-plated copper, nickel-plated titanium, nickel-plated aluminum, nickel-plated manganese, and nickel-plated titanium.
7. The preparation method according to claim 4, wherein the following conditions are satisfied:
and (3) carrying out electron-rich activation treatment on the silicon anode material subjected to the electron-rich activator activation treatment: mixing the electron-rich activator and the silicon anode material, and heating and activating for 10-60 min at 50-100 ℃;
the mass ratio of the composite anode material, the first conductive material and the first binding substance in the slurry A is (85-99): (0.2 to 7): (0.2-7); the composite anode material comprises a silicon anode material subjected to activation treatment by an electron-rich activator and a first graphite anode material;
the mass ratio of the first graphite anode material to the silicon anode material subjected to activation treatment by the electron-rich activator in the composite anode material is (5-99): (1-60).
8. The method of claim 7, wherein the electron rich activator is selected from one or more of ethylene oxide, propylene oxide, sodium styrene sulfonate, ethyl methacrylate, hydroxyethyl methacrylate polymer, hydroxyethyl methacrylate monomer.
9. The method of claim 7, wherein the electron-rich activator is used in an amount of 0.1 to 8wt% of the silicon negative electrode material.
10. A lithium ion battery comprising the porous composite anode of any one of claims 1 to 3, or the porous composite anode obtained by the production method of any one of claims 4 to 9.
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