CN116487578A - Lithium battery cathode material, lithium battery and preparation method - Google Patents

Lithium battery cathode material, lithium battery and preparation method Download PDF

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CN116487578A
CN116487578A CN202310225740.4A CN202310225740A CN116487578A CN 116487578 A CN116487578 A CN 116487578A CN 202310225740 A CN202310225740 A CN 202310225740A CN 116487578 A CN116487578 A CN 116487578A
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lithium battery
acid
carbon
lithium
silicon
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陈鹏
秦大亮
王钢
金昌植
牟丽莎
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Chongqing Changan New Energy Automobile Technology 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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
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    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • H01M4/625—Carbon or graphite
    • 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
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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
    • H01M2004/027—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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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10—Energy storage using batteries

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Abstract

The invention relates to a lithium battery cathode material, a lithium battery and a preparation method. The lithium battery cathode material consists of carbon nano tubes and silicon and carbon loaded in the carbon nano tubes. The invention also provides a preparation method of the lithium battery cathode material, which comprises the steps of etching two ends of the carbon nano tube by acid, introducing a silicon precursor into the carbon nano tube, and calcining under the mixed gas of inert gas and organic gas to obtain the lithium battery cathode material. The invention also provides a lithium battery, and the negative electrode active material of the lithium battery is the negative electrode material of the lithium battery. The invention also provides a preparation method of the lithium battery, which comprises the following steps: and homogenizing, coating, rolling and tabletting the positive electrode active material and the negative electrode material with a conductive agent and an adhesive respectively to obtain a positive electrode plate and a negative electrode plate, and then carrying out lamination assembly and the like with a lithium battery diaphragm to obtain the lithium battery. The invention solves the problems that the existing lithium battery anode material is difficult to simultaneously have high specific energy, fast electron and ion transmission rate, good cycle stability and the like.

Description

Lithium battery cathode material, lithium battery and preparation method
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a lithium battery negative electrode material, a lithium battery and a preparation method.
Background
The lithium ion battery has been widely used in the fields of mobile communication, electronic equipment, electric vehicles and the like in recent years due to the advantages of high voltage, high specific energy, longer cycle life, better safety performance and the like, and gradually replaces the traditional chemical power sources such as lead-acid batteries and the like. The great development of lithium ion batteries has become an important work in the field of new energy materials.
In lithium ion batteries, electrode materials are critical factors in determining the performance of lithium ion batteries. Although the cost of the cathode material battery system is low, the cycle life of the battery is greatly influenced. At present, graphite in the carbon material is the most commonly used negative electrode active material of a commercial lithium ion battery due to the advantages of abundant reserves, low price, high specific capacity, low voltage platform and the like. However, due to the low theoretical capacity (372 mAh/g) and low specific energy density of graphite carbon materials, the requirements of long-term running and high power of the battery cannot be met, and therefore, development of an electrode material with high energy density is urgently needed.
Silicon is an element with abundant reserves on the earth, meanwhile, the silicon cathode also has higher theoretical specific capacity (4200 mAh/g) and lower embedded potential (< 0.5V), so the silicon cathode has very important significance in the field of high-energy-density batteries. However, silicon is often accompanied by a huge volume expansion phenomenon (about 300%) in the process of lithium intercalation/deintercalation, and the structure of the material is extremely easy to damage and crush, so that the capacity is rapidly attenuated, and the cycle life of the battery is greatly shortened; in addition, the silicon-based material has the problems of low self conductivity, unstable SEI film formed in the charge and discharge process and the like, and the problems severely limit the further development of the silicon-based anode material.
CN 113964307A discloses a silicon-carbon negative electrode material of a lithium ion battery with a core-shell structure, wherein the core of the core-shell structure comprises nano silicon, carbon nanotubes, amorphous carbon and nano graphite sheets, and the shell layer is a carbon coating layer. The compact core-shell structure not only promotes the transmission of electrons, but also plays a role in buffering the expansion of the internal material, so that the material has excellent cycle performance and rate capability. However, experiments on the anode material show that the core structure inside the shell is compact and nonporous, so that the nano silicon has obvious volume expansion phenomenon in the process of lithium intercalation/deintercalation, thereby influencing the electrochemical performance of the lithium ion battery.
Currently, there are two main problems in developing silicon-carbon composite materials:
1. it is difficult to simultaneously have electrochemical properties such as high specific energy, fast electron and ion transport rate, and good cycling stability.
2. The design cost of the material structure is high, the preparation process is complex, the technical difficulty is high, and the actual mass production is difficult.
Disclosure of Invention
The invention aims to provide a lithium battery negative electrode material, a lithium battery and a preparation method thereof, which are used for solving the problem that the existing lithium battery negative electrode material is difficult to simultaneously have high specific energy, fast electron and ion transmission rate, good cycling stability and other electrochemical performances.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the lithium battery negative electrode material consists of carbon nanotubes, silicon nanoparticles and amorphous carbon, wherein the silicon nanoparticles are loaded in the carbon nanotubes, the carbon nanotubes are hollow tubular single-wall carbon nanotubes, the mass percentage of the amorphous carbon in the lithium battery negative electrode material is 5-25%, and the mass percentage of the silicon nanoparticles is 40-60%.
According to the technical means, the lithium battery anode material is composed of the carbon nano tube, the silicon nano particles and the amorphous carbon, and the silicon nano particles and the amorphous carbon are uniformly dispersed in the carbon nano tube, so that the internal space of the carbon nano tube can adapt to the volume expansion of silicon, the skeleton structure of the carbon nano tube can limit the volume expansion of silicon outwards, the problem of the volume expansion of silicon is effectively relieved, the cycling stability of the anode material is further improved, and meanwhile, the gram capacity and the conductivity of the anode material can be guaranteed. The negative electrode material is adopted to replace the artificial graphite negative electrode with high cost, has the advantages of low design cost and easy realization, and is suitable for industrial production.
Preferably, the diameter of the carbon nano tube is between 20 and 50nm, and the length is between 50 and 500 mu m;
the particle diameter of the silicon nano particle is between 5 and 10nm, and the specific surface area is 1.3m 2 /g～6.8m 2 Between/g, a compaction density of 1.0g/cm 3 ～1.8g/cm 3 。
The invention also provides a preparation method of the lithium battery anode material, which comprises the following steps:
etching two ends of the carbon nanotube by acid to obtain a hollow tubular single-wall carbon nanotube;
dispersing a silicon precursor in an organic solvent, and introducing the silicon precursor into the hollow tubular single-walled carbon nanotube in an infiltration manner to obtain an intermediate product;
calcining the intermediate product under the mixed atmosphere condition of inert gas and carbon-containing organic gas to enable the organic gas to be carbonized in the carbon nano tube to form amorphous carbon, and simultaneously reducing the silicon precursor in the hollow tubular single-wall carbon nano tube into silicon nano particles to obtain the silicon-carbon composite lithium battery anode material.
According to the technical means, the two ends of the carbon nano tube are etched by acid, then the silicon precursor is introduced into the carbon nano tube in an infiltration mode, the silicon precursor is reduced into silicon nano particles in the carbon nano tube in a calcination mode, and simultaneously, carbon-containing organic gas is introduced to form amorphous carbon in the carbon nano tube, so that the gram capacity of the anode material can be ensured, the conductivity of the material can be ensured, and the anode material has the advantages of mild process conditions, simplicity in operation and low cost.
The two ends of the calcined carbon nano tube are not blocked, namely, the two ends of the carbon nano tube are open, when the space inside the carbon nano tube cannot meet the expansion of the silicon nano particles, the carbon nano tube can be expanded outwards, the damage of the expansion of the silicon nano particles to the carbon nano tube is effectively avoided, and the electrochemical performance of the cathode material is further effectively ensured.
Preferably, the carbon-containing organic gas is selected from one or more of methane, ethylene, ethane, propane, n-butene, isobutene, 1,2 butadiene, 1,3 butadiene, cis-butene, trans-butene, n-butane, isobutane, propylene and cyclopropane.
Preferably, the silicon precursor is selected from one or more of Dichlorosilane (DCS), disilane (DS), octamethyl cyclotetrasiloxane (OMCTS), tetramethylsilane (4 MS), tetraethylsilane (4 ES), hexachlorodisilane (HCDS), bis (t-butylamino) silane (BTBAS), bis (diethylamino) silane (BDEAS), tris (dimethylamino) silane (3 DMAS), and Trisilylamine (TSA).
Preferably, the volume ratio of the inert gas to the carbon-containing organic gas in the mixed gas is 9:1;
the calcination temperature is 700-1100 ℃, and the calcination time is 2-8 h.
Preferably, the acid is selected from one or more of permanganate, hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, selenoic acid, hydrobromic acid, hydroiodic acid, chloric acid, carborane acid, phosphoric acid, tartaric acid, sulfurous acid, pyruvic acid, oxalic acid, nitrous acid, hydrofluoric acid, formic acid, carbonic acid, boric acid and acetic acid;
the organic solvent is selected from one or more of tetrahydrofuran, dimethylacetamide, methanol, ethanol, ethylene glycol, propanol, isopropanol, 1, 2-propylene glycol, 1, 3-propylene glycol, glycerol, N-butanol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, N-pentanol, 2-hexanol, acetone, methyl ethyl ketone, methyl propyl ketone, N-methyl pyrrolidone, ethyl propyl ketone, methyl butyl ketone, ethyl N-butyl ketone, methyl amyl ketone and methyl hexyl ketone.
The invention also provides a lithium battery, and the negative electrode active material of the lithium battery is the negative electrode material of the lithium battery.
The invention also provides a preparation method of the lithium battery, which comprises the following steps:
1) Homogenizing, coating, rolling and tabletting the positive electrode active material, the positive electrode conductive agent and the positive electrode adhesive to obtain a positive electrode plate;
2) Mixing and homogenizing the lithium battery anode material, the anode conductive agent and the anode adhesive, coating, rolling and tabletting to obtain an anode piece;
3) And (3) carrying out lamination assembly, liquid injection, formation, secondary sealing and capacity division on the positive pole piece, the negative pole piece and the lithium battery diaphragm to obtain the lithium battery.
Preferably, the positive electrode active material is selected from one or more of lithium cobaltate, lithium nickelate, lithium manganate, lithium nickelate cobalt manganate, lithium nickelate aluminate, lithium iron phosphate, lithium manganese iron phosphate, lithium-rich manganese-based material and lithium vanadium phosphate;
the positive electrode conductive agent is selected from one or more of conductive carbon black, acetylene black, ketjen black, graphene, carbon nano tubes, conductive graphite, carbon fibers and mixed conductive slurry;
the positive electrode adhesive is one or more selected from polyvinylidene fluoride, polyacrylonitrile, polytetrafluoroethylene, polyvinyl alcohol and polyurethane;
the negative electrode conductive agent is one or more selected from conductive carbon black, acetylene black, ketjen black, graphene, carbon nanotubes, conductive graphite, carbon fibers and mixed conductive slurry;
the negative electrode binder is one or more selected from sodium carboxymethyl cellulose, styrene-butadiene rubber, sodium alginate, conductive polymer polyacrylonitrile, hydroxymethyl chitosan, polyacrylic acid and polyvinyl alcohol;
the electrolyte is selected from lithium hexafluorophosphate, lithium tetrafluoroborate or lithium bis (fluorosulfonyl) imide.
The invention has the beneficial effects that:
1) According to the lithium battery anode material, the silicon nano particles and the amorphous carbon are loaded in the carbon nano tube to form a stable shell-core structure, so that on one hand, the gram capacity of the anode material is effectively improved by the silicon nano particles, and on the other hand, the defect of poor conductivity of the silicon material is overcome by the convenient amorphous carbon filling, so that the power performance of the material is greatly ensured, meanwhile, the volume expansion of the internal silicon nano particles is greatly limited by the stable carbon nano tube shell, the circulation stability of the material is greatly improved, and the prepared anode material has high specific energy, fast electron and ion transmission rate and good circulation stability;
2) According to the preparation method of the lithium battery anode material, the two ends of the carbon nano tube are etched by acid, then the silicon precursor is introduced into the carbon nano tube in an infiltration mode, the silicon precursor is reduced into silicon nano particles in the carbon nano tube in a calcination mode, and simultaneously, carbon-containing organic gas is introduced to form amorphous carbon in the carbon nano tube, so that the preparation method has the advantages of simplicity, mild process conditions and easiness in industrial production, and has popularization and application values in the technical field of lithium ion batteries.
Drawings
Fig. 1 is a cycle performance curve of a lithium battery of the present invention.
Detailed Description
Further advantages and effects of the present invention will become readily apparent to those skilled in the art from the disclosure herein, by referring to the accompanying drawings and the preferred embodiments. 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 preferred embodiments are presented by way of illustration only and not by way of limitation.
It should be noted that the illustrations provided in the following embodiments merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.
In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present application, however, it will be apparent to one skilled in the art that embodiments of the present application may be practiced without these specific details.
Example 1
The preparation method of the lithium battery anode material comprises the following steps:
s1, etching two ends of a carbon nano tube by nitric acid to obtain a hollow tubular single-wall carbon nano tube;
s2, dispersing a tetraethyl silane (4 ES) precursor in absolute ethyl alcohol, and introducing the precursor into the hollow tubular single-walled carbon nanotube in the S1 in an infiltration mode to obtain an intermediate product;
s3, placing the intermediate product in the S2 into a carbonization furnace, and introducing nitrogen (N) 2 ) (V%: 90%) and ethane (C) 2 H 6 ) (V%: 10 percent) and heating to 800 ℃ to calcine the intermediate product, so that ethane is carbonized in the carbon nano tube to form amorphous carbon, and simultaneously, the silicon precursor in the hollow tubular single-wall carbon nano tube is reduced into silicon nano particles to obtain the silicon-carbon composite lithium battery anode material;
in the lithium battery anode material, the mass percentage of the hollow tubular single-wall carbon nano tube is 30%, the mass percentage of the silicon nano particles is 60%, and the mass percentage of the amorphous carbon is 10%.
Example 2
The preparation method of the lithium battery anode material comprises the following steps:
s1, etching two ends of a carbon nano tube by sulfuric acid to obtain a hollow tubular single-wall carbon nano tube;
s2, dispersing a tetramethylsilane (4 MS) precursor in absolute ethyl alcohol, and introducing the precursor into the hollow tubular single-walled carbon nanotube in the S1 in an infiltration mode to obtain an intermediate product;
s3, placing the intermediate product in the S2 into a carbonization furnace, and introducing nitrogen (N) 2 ) (V%: 90%) and ethane (C) 2 H 6 ) (V%: 10 percent) and heating to 800 ℃ to calcine the intermediate product, so that ethane is carbonized in the carbon nano tube to form amorphous carbon, and simultaneously, the silicon precursor in the hollow tubular single-wall carbon nano tube is reduced into silicon nano particles to obtain the silicon-carbon composite lithium battery anode material;
in the lithium battery anode material, the mass percentage of the hollow tubular single-wall carbon nano tube is 35%, the mass percentage of the silicon nano particles is 50%, and the mass percentage of the amorphous carbon is 15%.
Example 3
The preparation method of the lithium battery anode material comprises the following steps:
s1, etching two ends of a carbon nano tube by hydrochloric acid to obtain a hollow tubular single-wall carbon nano tube;
s2, dispersing a bis (tertiary butylamino) silane (BTBAS) precursor in absolute ethyl alcohol, and introducing the precursor into the hollow tubular single-walled carbon nanotube in the S1 in an infiltration mode to obtain an intermediate product;
s3, placing the intermediate product in the S2 into a carbonization furnace, and introducing nitrogen (N) 2 ) (V%: 90%) and ethane (C) 2 H 6 ) (V%: 10 percent) and heating to 800 ℃ to calcine the intermediate product, so that ethane is carbonized in the carbon nano tube to form amorphous carbon, and simultaneously, the silicon precursor in the hollow tubular single-wall carbon nano tube is reduced into silicon nano particles to obtain the silicon-carbon composite lithium battery anode material;
in the lithium battery anode material, the mass percentage of the hollow tubular single-wall carbon nano tube is 35%, the mass percentage of the silicon nano particles is 60%, and the mass percentage of the amorphous carbon is 5%.
Example 4
The preparation method of the lithium battery anode material comprises the following steps:
s1, etching two ends of a carbon nano tube by hydrofluoric acid to obtain a hollow tubular single-wall carbon nano tube;
s2, dispersing a Dichlorosilane (DCS) precursor in absolute ethyl alcohol, and introducing the precursor into the hollow tubular single-walled carbon nanotube in the S1 in an infiltration mode to obtain an intermediate product;
s3, placing the intermediate product in the S2 into a carbonization furnace, and introducing nitrogen (N) 2 ) (V%: 90%) and ethane (C) 2 H 6 ) (V%: 10 percent) and heating to 800 ℃ to calcine the intermediate product, so that ethane is carbonized in the carbon nano tube to form amorphous carbon, and simultaneously, the silicon precursor in the hollow tubular single-wall carbon nano tube is reduced into silicon nano particles to obtain the silicon-carbon composite lithium battery anode material;
in the lithium battery anode material, the mass percentage of the hollow tubular single-wall carbon nano tube is 35%, the mass percentage of the silicon nano particles is 45%, and the mass percentage of the amorphous carbon is 20%.
Example 5
The preparation method of the lithium battery anode material comprises the following steps:
s1, etching two ends of a carbon nano tube by hydrobromic acid to obtain a hollow tubular single-wall carbon nano tube;
s2, dispersing Disilane (DS) precursors in absolute ethyl alcohol, and introducing the precursors into the hollow tubular single-walled carbon nanotubes in the S1 in an infiltration mode to obtain an intermediate product;
s3, placing the intermediate product in the S2 into a carbonization furnace, and introducing nitrogen (N) 2 ) (V%: 90%) and ethane (C) 2 H 6 ) (V%: 10 percent) and heating to 800 ℃ to calcine the intermediate product, so that ethane is carbonized in the carbon nano tube to form amorphous carbon, and simultaneously, the silicon precursor in the hollow tubular single-wall carbon nano tube is reduced into silicon nano particles to obtain the silicon-carbon composite lithium battery anode material;
in the lithium battery anode material, the mass percentage of the hollow tubular single-wall carbon nano tube is 35%, the mass percentage of the silicon nano particles is 40%, and the mass percentage of the amorphous carbon is 25%.
Comparative example 1
The preparation method of the lithium battery anode material comprises the following steps:
s1, etching two ends of a carbon nano tube by nitric acid to obtain a hollow tubular single-wall carbon nano tube;
s2, dispersing a tetraethyl silane (4 ES) precursor in absolute ethyl alcohol, and introducing the precursor into the hollow tubular single-walled carbon nanotube in the S1 in an infiltration mode to obtain an intermediate product;
s3, placing the intermediate product in the S2 into a carbonization furnace, and introducing nitrogen (N) 2 ) (V%: 100 percent) and heating to 800 ℃ to calcine the intermediate product, so that the silicon precursor in the hollow tubular single-walled carbon nanotube is reduced into silicon nano particles, and the silicon-carbon composite lithium battery anode material is obtained.
Preparation of lithium batteries
The lithium battery negative electrode materials prepared in examples 1 to 5 and comparative example 1 were prepared into a pouch battery, and the preparation method comprises the steps of:
negative pole piece: the mass ratio of the active material, the conductive carbon black (SP), the sodium carboxymethylcellulose (CMC) and the Styrene Butadiene Rubber (SBR) is 94.5:1.5:1.5:2.5, stirring by a refiner to obtain negative electrode slurry, uniformly coating the uniformly dispersed negative electrode slurry on copper foil with the thickness of 8 mu m, and rolling and tabletting to obtain a negative electrode plate; wherein the active materials are the lithium battery anode materials prepared in examples 1 to 5 and comparative example 1;
positive pole piece: the mass ratio of the lithium iron phosphate active substance (LFP), the conductive carbon black (SP) and the polyvinylidene fluoride (PVDF) is 96.5:1:2.5, stirring by a refiner to obtain anode slurry, uniformly coating the anode slurry which is uniformly dispersed on aluminum foil with the thickness of 20 mu m, and rolling and tabletting to obtain an anode plate;
the membrane is a base membrane (7 mu mPE) +double-sided ceramic (2 mu m Al) 2 O 3 ) +double sided adhesive (1. Mu. MPVDF), electrolyte 1M LiPF 6 (solvent mass ratio EC: DMC: emc=1:1:1);
and respectively carrying out lamination, liquid injection, formation, secondary sealing, capacity division and K value test on each negative pole piece, each positive pole piece and each diaphragm to obtain a finished product of the soft package battery.
Detection analysis
The soft pack batteries prepared in examples 1 to 5 and comparative example 1 were subjected to a charge-discharge performance test on a blue charge-discharge meter at a temperature of 25C, a test voltage range of 2.5V-3.7V, a current of 0.1C, 400 cycles of charge-discharge cycles, and capacity retention after recording initial effect and 200 cycles, 400 cycles, and then the full-charge expansion and conductivity of the negative electrode sheet thereof were further tested, wherein the soft pack batteries prepared in examples 1 to 5 and comparative example 1 were recorded as soft pack battery-1, soft pack battery-2, soft pack battery-3, soft pack battery-4, soft pack battery-5 and soft pack battery-0, respectively, and the test results are shown in table 1 and fig. 1.
TABLE 1 electrochemical Performance test results
As can be seen from the comprehensive analysis of table 1 and fig. 1, the first effect, the capacity retention rate after 200 cycles and 400 cycles of charge and discharge, and the conductivity of the soft-pack lithium ion batteries prepared in examples 1 to 5 are all significantly improved compared with those of the soft-pack battery prepared in comparative example 1, and meanwhile, the full-charge expansion rate of the negative electrode sheets prepared in examples 1 to 5 is significantly smaller than that of comparative example 1. Therefore, the silicon-carbon composite material designed by the invention can not relieve the problem of volume expansion of silicon, and simultaneously promote rapid conduction of lithium ions, and improve the cycle stability and conductivity of the cathode material.
In conclusion, experiments prove that the silicon-carbon composite lithium battery provided by the inventionAccording to the negative electrode material, silicon nano particles and amorphous carbon are loaded in the hollow tubular single-wall carbon nano tube with stable structure, the gram capacity of the negative electrode material is greatly improved, the amorphous carbon co-filling ensures the high conductivity of the material, the conduction rate of lithium ions in the negative electrode material is greatly improved, the good rate capability of the material is ensured, meanwhile, the carbon nano tube frame with stable outer layer avoids the exposure of silicon on the surface, the volume expansion of silicon is greatly limited, the full-charge expansion rate of the material is effectively reduced, and the cycle stability of the battery is effectively improved. Compared with the carbon nanotube array negative electrode composite material with the silicon material filled inside prepared by a template method, the preparation method of the silicon-carbon composite lithium battery negative electrode material adopts a simple synthesis method, and the preparation method of the silicon-carbon composite lithium battery negative electrode material skillfully introduces a silicon precursor into a carbon nanotube etched by acid through a simple dipping mode, and then introduces the silicon precursor into an inert atmosphere (v% and 90% N) containing 10% of organic gas 2 ) And (3) calcining at high temperature to generate a filler of silicon nano particles and amorphous carbon in the carbon nano tube, thereby obtaining the silicon-carbon composite anode material with the shell-core structure. The invention has ingenious material structure design, simple and easily obtained preparation raw materials, low operation and implementation technical difficulty, is suitable for industrial production, and has popularization and application values in the technical field of lithium ion batteries.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness and are not intended to limit the application. Modifications and variations may be made to the above-described embodiments by those of ordinary skill in the art without departing from the spirit and scope of the present application. It is therefore contemplated that the appended claims will cover all such equivalent modifications and changes as fall within the true spirit and scope of the disclosure.

Claims (10)

1. The lithium battery cathode material is characterized by comprising a carbon nano tube, silicon nano particles loaded in the carbon nano tube and amorphous carbon, wherein the carbon nano tube is a hollow tubular single-wall carbon nano tube; in the lithium battery anode material, the mass percentage of amorphous carbon is 5-25%, and the mass percentage of silicon nano particles is 40-60%.
2. The lithium battery anode material according to claim 1, wherein the carbon nanotubes have a diameter of 20-50 nm and a length of 50-500 μm;
the particle diameter of the silicon nano particles is 5-10 nm, and the specific surface area is 1.3m 2 /g～6.8m 2 Between/g, a compaction density of 1.0g/cm 3 ～1 .8g/cm 3 。
3. A method for preparing the negative electrode material for a lithium battery as claimed in claim 1 or claim 2, comprising the steps of:
etching two ends of the carbon nanotube by acid to obtain a hollow tubular single-wall carbon nanotube;
dispersing a silicon precursor in an organic solvent, and introducing the silicon precursor into the hollow tubular single-walled carbon nanotube in an infiltration manner to obtain an intermediate product;
calcining the intermediate product under the mixed atmosphere condition of inert gas and carbon-containing organic gas to enable the organic gas to be carbonized in the carbon nano tube to form amorphous carbon, and simultaneously reducing the silicon precursor in the hollow tubular single-wall carbon nano tube into silicon nano particles to obtain the silicon-carbon composite lithium battery anode material.
4. The method for producing a negative electrode material for a lithium battery according to claim 3, wherein the carbonaceous organic gas is one or more selected from the group consisting of methane, ethylene, ethane, propane, n-butene, isobutylene, 1,2 butadiene, 1,3 butadiene, cis-butene, trans-butene, n-butane, isobutane, propylene and cyclopropane.
5. The method for producing a negative electrode material for a lithium battery according to claim 3, wherein the silicon precursor is selected from one or more of Dichlorosilane (DCS), disilane (DS), octamethylcyclotetrasiloxane (OMCTS), tetramethylsilane (4 MS), tetraethylsilane (4 ES), hexachlorodisilane (HCDS), bis (t-butylamino) silane (BTBAS), bis (diethylamino) silane (BDEAS), tris (dimethylamino) silane (3 DMAS), and Trisilylamine (TSA).
6. The method for preparing a negative electrode material for a lithium battery according to claim 3, wherein the volume ratio of the inert gas to the carbon-containing organic gas in the mixed gas is 9:1;
the calcination temperature is 700-1100 ℃, and the calcination time is 2-8 hours.
7. The method for producing a negative electrode material for a lithium battery according to claim 3, wherein the acid is one or more selected from the group consisting of permanganate, hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, selenoic acid, hydrobromic acid, hydroiodic acid, chloric acid, carborane acid, phosphoric acid, tartaric acid, sulfurous acid, pyruvic acid, oxalic acid, nitrous acid, hydrofluoric acid, formic acid, carbonic acid, boric acid and acetic acid;
the organic solvent is selected from one or more of tetrahydrofuran, dimethylacetamide, methanol, ethanol, ethylene glycol, propanol, isopropanol, 1, 2-propylene glycol, 1, 3-propylene glycol, glycerol, N-butanol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, N-pentanol, 2-hexanol, acetone, methyl ethyl ketone, methyl propyl ketone, N-methyl pyrrolidone, ethyl propyl ketone, methyl butyl ketone, ethyl N-butyl ketone, methyl amyl ketone and methyl hexyl ketone.
8. A lithium battery characterized in that the negative active material of the lithium battery is the negative material of the lithium battery according to claim 1 or claim 2.
9. A method of preparing a lithium battery according to claim 8, comprising the steps of:
1) Homogenizing, coating, rolling and tabletting the positive electrode active material, the positive electrode conductive agent and the positive electrode adhesive to obtain a positive electrode plate;
2) Mixing and homogenizing the lithium battery anode material, the anode conductive agent and the anode adhesive, coating, rolling and tabletting to obtain an anode piece;
3) And (3) carrying out lamination assembly, liquid injection, formation, secondary sealing and capacity division on the positive pole piece, the negative pole piece and the lithium battery diaphragm to obtain the lithium battery.
10. The method for producing a lithium battery according to claim 9, wherein the positive electrode active material is selected from one or more of lithium cobaltate, lithium nickelate, lithium manganate, lithium nickelate aluminate, lithium iron phosphate, lithium manganese iron phosphate, lithium-rich manganese-based material, and lithium vanadium phosphate;
the positive electrode conductive agent is selected from one or more of conductive carbon black, acetylene black, ketjen black, graphene, carbon nano tubes, conductive graphite, carbon fibers and mixed conductive slurry;
the positive electrode adhesive is one or more selected from polyvinylidene fluoride, polyacrylonitrile, polytetrafluoroethylene, polyvinyl alcohol and polyurethane;
the negative electrode conductive agent is one or more selected from conductive carbon black, acetylene black, ketjen black, graphene, carbon nanotubes, conductive graphite, carbon fibers and mixed conductive slurry;
the negative electrode binder is one or more selected from sodium carboxymethyl cellulose, styrene-butadiene rubber, sodium alginate, conductive polymer polyacrylonitrile, hydroxymethyl chitosan, polyacrylic acid and polyvinyl alcohol;
the electrolyte is selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorosulfimide or lithium perchlorate electrolyte.
CN202310225740.4A 2023-03-10 2023-03-10 Lithium battery cathode material, lithium battery and preparation method Pending CN116487578A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117304584A (en) * 2023-11-29 2023-12-29 广州双一乳胶制品有限公司 Anti-frosting glove latex, preparation method thereof and application thereof in preparation of anti-frosting glove

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117304584A (en) * 2023-11-29 2023-12-29 广州双一乳胶制品有限公司 Anti-frosting glove latex, preparation method thereof and application thereof in preparation of anti-frosting glove

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