CN112968155A - Composite negative electrode material for lithium ion battery and preparation method thereof - Google Patents

Composite negative electrode material for lithium ion battery and preparation method thereof Download PDF

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CN112968155A
CN112968155A CN202110143078.9A CN202110143078A CN112968155A CN 112968155 A CN112968155 A CN 112968155A CN 202110143078 A CN202110143078 A CN 202110143078A CN 112968155 A CN112968155 A CN 112968155A
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composite
lithium ion
carbon
negative electrode
ion battery
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阳柳
王燕飞
周桂民
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Ganzhou Litan New Energy Technology Co.,Ltd.
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Changde Sucarbon New Energy 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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—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
    • 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
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

A composite anode material for a lithium ion battery and a preparation method thereof are provided, wherein the composite anode material comprises: the carbon material is not graphitized and has a disordered microcrystalline structure; the size of silicon crystal grains in the silicon particles is less than 15 nm; the coated carbon is amorphous carbon formed by cracking a carbon source material at a high temperature, and at least part of the surfaces of the carbonaceous material and the silicon particles is covered by the coated carbon. Compared with graphite, the composite negative electrode material prepared by the invention has the advantages that the carbon material can obviously improve the multiplying power, has low-temperature performance and long cycle performance, the silicon particles can obviously improve the specific capacity of the composite negative electrode material, the carbon is coated, the early-stage lithium ion loss can be reduced, and the structural stability of the material is improved; the first reversible capacity of the composite negative electrode material reaches over 600mAh/g, the first efficiency is more than 85 percent, the raw materials are low in price, the preparation process and equipment are mature, and the composite negative electrode material is suitable for large-scale production.

Description

Composite negative electrode material for lithium ion battery and preparation method thereof
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a composite negative electrode material for a lithium ion battery and a preparation method thereof.
Background
The lithium ion battery has the advantages of good stability, high energy density, no memory effect and the like, and is widely applied to the field of 3C consumer batteries, power batteries and energy storage batteries, the current commercial lithium ion battery composite negative electrode material mainly comprises a graphite negative electrode, but the theoretical specific capacity of the graphite negative electrode is lower and is only 372mAh/g, and the high-rate continuous charging and discharging capacity and the low-temperature performance are difficult to effectively improve, so that the development of a novel lithium ion battery negative electrode material which is high in specific capacity, excellent in rate performance and good in low-temperature performance is an important direction of current research.
Disclosure of Invention
In order to solve the above problems, the present invention provides a composite anode material for a lithium ion battery, comprising: the carbon material is not graphitized and has a disordered microcrystalline structure; the size of silicon crystal grains in the silicon particles is less than 15 nm; the coated carbon is amorphous carbon formed by cracking a carbon source material at a high temperature, and at least part of the surfaces of the carbonaceous material and the silicon particles is covered by the coated carbon.
Preferably, the mass fraction of the carbonaceous material is 50% -90%, the mass fraction of the silicon particles is 5% -30%, and the mass fraction of the coated carbon is 5% -20%.
Preferably, the particle size D50 of the carbonaceous material is 3-10 μm, and the powder compaction density is 1.0g/cm3-1.4g/cm3Tap density of 0.8g/cm3-1.5g/cm3。
Preferably, the interlayer spacing d002 of the 002 face of the carbonaceous material is 0.33nm-0.37nm detected by XRD.
Preferably, the silicon particles are one of simple substance silicon, nano silicon oxygen, silicon carbon composite material, silicon monoxide (SiOx, wherein x is more than or equal to 0.5 and less than or equal to 2), silicon alloy and porous silicon.
Preferably, the carbon source material is one or more of methane, ethane, ethylene, acetylene, propane, propylene, acetone, butylene, pentane and hexane.
Preferably, the coated carbon has an average thickness of 50nm to 1000 nm.
Preferably, the specific surface area of the composite anode material is 1m2/g-20m2And the median particle diameter D50 of the composite negative electrode material is 5-30 μm.
Preferably, the specific surface area of the composite anode material is 1m2/g-12m2The median particle diameter D50 of the composite negative electrode material is 6-18 μm.
The invention also provides a preparation method of the composite anode material for the lithium ion battery, the composite anode material comprises the composite anode material for the lithium ion battery, and the method comprises the following steps:
preparing a carbonaceous material precursor, silicon particles and a carbon source material;
sintering the carbonaceous material precursor at the low temperature of 300-500 ℃ for 2-5 h in an inert gas environment to obtain a first sintered material;
soaking the first calcined material by using dilute hydrochloric acid, and then cleaning the first calcined material by using pure water until the pH value of a soaking solution is 6-8 to obtain a first purified material;
sintering the first purified material at the high temperature of 1000-1300 ℃ for 2-5 h in an inert gas environment to obtain a second sintered material;
crushing the second fired material to obtain a carbonaceous material;
compounding the carbonaceous material and the silicon particles to obtain a composite powder material;
and calcining the composite powder and the carbon source material at the high temperature of 700-1000 ℃ for 2-6 h in an inert gas environment to obtain the composite cathode material.
The composite negative electrode material for the lithium ion battery and the preparation method thereof have the following beneficial effects:
(1) the composite negative electrode material for the lithium ion battery prepared by the invention contains the carbon material, so that the multiplying power, the low temperature and the long cycle performance of the lithium ion battery can be obviously improved;
(2) the composite negative electrode material for the lithium ion battery prepared by the invention contains silicon particles, has high specific capacity and first reversible capacity of more than 600 mAh/g;
(3) the composite negative electrode material for the lithium ion battery prepared by the invention contains the coated carbon, so that the early-stage lithium ion loss can be reduced, the initial coulomb efficiency is more than 85%, and meanwhile, the structural stability of the material is improved, and the cycle performance is improved;
(4) the composite cathode material for the lithium ion battery prepared by the invention has the advantages of low price of raw materials, mature preparation process and equipment, and suitability for large-scale production;
(5) when the composite negative electrode material prepared by the invention is used as a negative electrode active material of a lithium ion battery, the composite negative electrode material has excellent cycle performance, and the capacity retention rate after 1500 cycles under the 1C/1C multiplying power is about 84%.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is an SEM image of a composite anode material obtained in example 1 of the present invention;
FIG. 2 is an SEM image of a composite anode material prepared in example 1 of the present invention;
FIG. 3 is an EDS diagram of a composite anode material prepared in example 1 of the present invention;
FIG. 4 is an XRD pattern of a composite anode material prepared in example 1 of the present invention;
FIG. 5 is the first charge-discharge curve of button cell with composite negative electrode material prepared in example 1 of the present invention;
fig. 6 is a cycle curve of the composite negative electrode material prepared in example 1 of the present invention at a 1C/1C rate in a pouch full cell.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
The invention provides a composite anode material for a lithium ion battery, which comprises the following components: the carbon material is not graphitized and has a disordered microcrystalline structure; the size of silicon crystal grains in the silicon particles is less than 15 nm; the coated carbon is amorphous carbon formed by cracking a carbon source material at a high temperature, and at least part of the surfaces of the carbonaceous material and the silicon particles is covered by the coated carbon.
In the embodiment of the application, the mass fraction of the carbonaceous material is 50-90%, the mass fraction of the silicon particles is 5-30%, and the mass fraction of the coated carbon is 5-20%.
In the embodiment of the application, the particle size D50 of the carbonaceous material is 3-10 μm, and the powder compaction density is 1.0g/cm3-1.4g/cm3Tap density of 0.8g/cm3-1.5g/cm3。
In the examples of the present application, the interlayer spacing d002 of the 002 face of the carbonaceous material was detected to be 0.33nm to 0.37nm by XRD.
In the embodiment of the application, the silicon particles are one of simple substance silicon, nano silicon oxygen, silicon carbon composite material, silicon monoxide (SiOx, wherein x is more than or equal to 0.5 and less than or equal to 2), silicon alloy and porous silicon.
In the embodiment of the present application, the carbon source material is one or more of methane, ethane, ethylene, acetylene, propane, propylene, acetone, butylene, pentane and hexane.
In the examples of the present application, the coated carbon has an average thickness of 50nm to 1000 nm.
In the embodiment of the present application,the specific surface area of the composite negative electrode material is 1m2/g-20m2And the median particle diameter D50 of the composite negative electrode material is 5-30 μm.
In the embodiment of the application, the specific surface area of the composite anode material is 1m2/g-12m2The median particle diameter D50 of the composite negative electrode material is 6-18 μm.
In an embodiment of the present application, the present invention further provides a method for preparing a composite anode material for a lithium ion battery, where the composite anode material includes the composite anode material for a lithium ion battery as described above, and the method includes the steps of:
preparing a carbonaceous material precursor, silicon particles and a carbon source material;
sintering the carbonaceous material precursor at the low temperature of 300-500 ℃ for 2-5 h in an inert gas environment to obtain a first sintered material;
soaking the first calcined material by using dilute hydrochloric acid, and then cleaning the first calcined material by using pure water until the pH value of a soaking solution is 6-8 to obtain a first purified material;
sintering the first purified material at the high temperature of 1000-1300 ℃ for 2-5 h in an inert gas environment to obtain a second sintered material;
crushing the second fired material to obtain a carbonaceous material;
compounding the carbonaceous material and the silicon particles to obtain a composite powder material;
and calcining the composite powder and the carbon source material at the high temperature of 700-1000 ℃ for 2-6 h in an inert gas environment to obtain the composite cathode material.
Specifically, the silicon particles were analyzed by X-ray diffraction pattern analysis, and the half-width value of the diffraction line assigned to the Si (111) plane near 28.4 ° 2 θ was determined.
Specifically, the inert gas is one of nitrogen, argon and helium.
Specifically, the low-temperature sintering equipment, the high-temperature sintering equipment and the high-temperature calcining equipment are one or more of a box furnace, a tubular furnace, a rotary kiln, a roller kiln, a pushed slab kiln and a shuttle kiln.
Specifically, the carbonaceous material precursor includes a biomass material, a polymer resin, a carbon product, and a saccharide. Preferably, the carbonaceous material precursor is one or more of coconut shell, phenolic resin, petroleum coke and glucose.
Specifically, the carbonaceous material and the silicon particles are compounded in a solid phase, liquid phase or gas phase. Further, the solid phase compounding is to add the carbonaceous material and the silicon particles into a VC mixer, the stirring speed is 800rpm/min, the stirring time is 1h, and obtain composite powder; the liquid phase compounding is to dissolve a carbonaceous material in an ethanol solution, add silicon particles, stir, and dry to obtain a composite powder material; the gas phase compounding is to add a carbonaceous material into an inner container of a CVD furnace, introduce nitrogen to remove air until the oxygen content is lower than 100ppm, then heat up to 600-900 ℃ at a heating rate of 1-5 ℃/min, and introduce an organic silicon source gas during the period of heating up to the temperature of 1-900 ℃ for chemical vapor deposition for 1-5 hours, wherein the flow rate of the organic silicon source gas is 5-10L/min, so as to obtain a composite material, and the organic silicon source gas is one or a combination of more than two of silane, dichlorosilane, trichlorosilane, silicon tetrachloride and silicon tetrafluoride.
Example 1
In an embodiment of the present application, a preparation method of a composite anode material for a lithium ion battery provided by the present application specifically includes the following steps:
(1) 1kg of coconut shell coarse crushed materials (carbonaceous material precursors) are placed in a box furnace, nitrogen is introduced until the oxygen content in the box furnace is lower than 100ppm, then the temperature is raised to 300 ℃ at 3 ℃/min, and the firing is carried out for 5h, thus obtaining 0.34kg of fired materials. And (3) placing the fired material in dilute hydrochloric acid, repeatedly washing to remove impurities, washing with pure water until the pH value of the solution is 6-8, and drying. And (3) placing the dried material in a box-type furnace, introducing nitrogen until the oxygen content in the box-type furnace is lower than 100ppm, heating to 1300 ℃ at the temperature of 3 ℃/min, and sintering for 2 h. And (3) crushing the fired material, and controlling the particle size D50 after crushing to be 3 +/-1 mu m to obtain the carbonaceous material.
(2) And (2) adding the carbonaceous material obtained in the step (1) and the silicon-carbon composite material into a VC mixer according to the mass ratio of 7:3, wherein the mixing rotating speed is 800rpm, and the stirring time is 1h, so as to obtain the composite powder.
(3) And (3) placing the composite powder obtained in the step (2) in a vapor deposition furnace, introducing nitrogen for protection, heating to 700 ℃ at a heating rate of 3 ℃/min, introducing methane for vapor deposition, and controlling the content of deposited carbon to be 5 wt% to obtain the composite anode material.
In the composite negative electrode material, the mass fraction of the carbonaceous material was 66.5%, the mass fraction of the silicon particles was 28.5%, and the mass fraction of the coated carbon was 5%.
Example 2
The difference from the embodiment 1 is that the carbonaceous material precursor in the step (1) is phenolic resin, the low-temperature sintering temperature is 350 ℃, and the sintering time is 4 hours; the high-temperature sintering temperature is 1200 ℃, and sintering is carried out for 3 hours; the pulverized particle size D50 of the calcined material was 5. + -. 1 μm, and a carbonaceous material was obtained.
And (2) adopting liquid phase compounding, adding the carbonaceous material and the silicon monoxide into an ethanol solution according to the mass ratio of 8:2, uniformly stirring, and drying to obtain the composite powder.
And (3) using acetylene as a carbon source gas, controlling the treatment temperature to be 800 ℃, and controlling the content of deposited carbon to be 10 wt.% to obtain the composite cathode material.
In the composite negative electrode material, the ratio of the carbonaceous material is 72.0 wt.%, the ratio of the silicon particles is 18 wt.%, and the ratio of the coated carbon is 10 wt.%.
Example 3
The difference from the embodiment 1 is that the carbonaceous material precursor in the step (1) is petroleum coke, the low-temperature sintering temperature is 400 ℃, and the sintering is carried out for 3 hours; the high-temperature sintering temperature is 1100 ℃, and sintering is carried out for 4 hours; the pulverized particle size D50 of the calcined material was 8. + -. 1 μm, to obtain a carbonaceous material.
The step (2) adopts gas phase compounding, carbonaceous materials are added into an inner container of a CVD furnace, nitrogen is introduced to remove air until the oxygen content is lower than 100ppm, then the temperature is raised to 700 ℃ at the temperature raising speed of 2 ℃/min, silane gas is introduced during the period of heating to carry out chemical vapor deposition, the flow rate is 5L/min, nano silicon is deposited on the carbonaceous materials, and the mass ratio of the nano silicon to the carbonaceous materials is controlled to be 1: 9, obtaining the composite powder.
And (4) using acetone as a carbon source gas in the step (3), controlling the treatment temperature to be 900 ℃, and controlling the content of deposited carbon to be 15 wt%, so as to obtain the composite cathode material.
In the composite negative electrode material, the ratio of the carbonaceous material is 76.5 wt.%, the ratio of the silicon particles is 8.5 wt.%, and the ratio of the coated carbon is 15 wt.%.
Example 4
The precursor of the carbonaceous material in the step (1) is glucose, the low-temperature sintering temperature is 500 ℃, and the sintering is carried out for 2 hours; the high-temperature sintering temperature is 1000 ℃, and the sintering time is 5 hours; the pulverized particle size D50 of the calcined material was 10. + -. 1 μm, to obtain a carbonaceous material.
The step (2) adopts gas phase compounding, the carbonaceous material is added into an inner container of a CVD furnace, nitrogen is introduced to remove air until the oxygen content is lower than 100ppm, then the temperature is raised to 900 ℃ at the temperature raising speed of 5 ℃/min, trichlorosilane is introduced to carry out chemical vapor deposition during the period, the flow rate is 2L/min, nano silicon is deposited on the carbonaceous material, and the mass ratio of the nano silicon to the carbonaceous material is controlled to be 0.8: 9.2, obtaining the composite powder.
And (3) using hexane as a carbon source gas, controlling the treatment temperature to be 1000 ℃, and controlling the content of deposited carbon to be 20 wt.% to obtain the composite cathode material.
In the composite negative electrode material, the ratio of the carbonaceous material was 73.6 wt.%, the ratio of the silicon particles was 6.4 wt.%, and the ratio of the coated carbon was 20 wt.%.
Comparative example 1
The difference from example 1 is that in step (1), acid washing purification is not performed, and the rest is the same as example 1, which is not described herein again.
Comparative example 2
The difference from example 1 is that in step (1), the pulverized particle size of the fired material D50 is 15 + -1 μm, and the rest is the same as example 1, and will not be described herein again.
Comparative example 3
The difference from example 1 is that step (2) is not performed, that is, silicon particles are not added, and the description is omitted as in example 1.
In the composite negative electrode material, the mass fraction of the carbonaceous material is 95%, and the mass fraction of the coated carbon is 5%.
Comparative example 4
The difference from the example 1 is that in the step (2), the carbonaceous material and the silicon-carbon composite material are mixed according to the mass ratio of 95:5, and the rest is the same as the example 1 and is not described again.
In the composite negative electrode material, the mass fraction of the carbonaceous material is 90.25%, the mass fraction of the silicon particles is 2.85%, and the mass fraction of the coated carbon is 5%.
Comparative example 5
The difference from the example 1 is that in the step (2), the carbonaceous material and the silicon-carbon composite material are mixed according to the mass ratio of 5:5, and the rest is the same as the example 1 and is not described again.
In the composite negative electrode material, the mass fraction of the carbonaceous material is 47.5%, the mass fraction of the silicon particles is 47.5%, and the mass fraction of the coated carbon is 5%.
Comparative example 6
The difference from example 1 is that step (3) is not performed, i.e., no carbon coating is added, and the description is omitted as in example 1.
In the composite negative electrode material, the mass fraction of the carbonaceous material is 70%, and the mass fraction of the silicon particles is 30%.
The composite anode materials in examples 1 to 4 and comparative examples 1 to 6 were tested by the following methods:
the material particle size range was tested using a malvern laser particle sizer Mastersizer 3000.
The material was subjected to morphological analysis using a JSM-7160 scanning electron microscope from Japan Electron corporation.
The material was subjected to phase analysis using an XRD diffractometer (X' Pert3 Powder) to determine the grain size of the material.
The material was tested for specific surface area using the american conta NOVA 4000 e.
The composite negative electrode material obtained in the embodiments 1 to 4 and the comparative examples 1 to 6 is mixed in pure water according to the mass ratio of 92:3:5 of a carbon material, conductive carbon black and a binder, homogenized, controlled in solid content of 45%, coated on a copper foil current collector, vacuum-baked for 12 hours at 110-120 ℃, pressed and formed, and then punched to prepare a negative electrode piece. The button cells were assembled in an argon-filled glove box, the counter electrode was a metallic lithium plate, the separator used was Celgard2400 and the electrolyte was 1mol/L EC/DMC from LiPF6 (Vol 1: 1). And (3) performing charge and discharge tests on the button cell, wherein the voltage interval is 5 mV-1.5V, and the current density is 80 mA/g. The first reversible capacity and efficiency of the composite anode materials in examples and comparative examples were measured.
The composite negative electrode material in example 1 was evaluated using a pouch full cell, wherein the positive electrode was a mature ternary positive electrode sheet, 1mol/L LiPF6/EC + DMC + EMC (v/v ═ 1:1:1) electrolyte, and a Celgard2400 separator. On a LanD battery test system of Wuhanjinnuo electronics Limited company, the electrochemical performance of the prepared soft package battery is tested, and the test conditions are as follows: and (3) charging and discharging at a constant current of 1.0 ℃ at normal temperature, wherein the charging and discharging voltage is limited to 2.75V-4.2V.
The testing equipment of the button cell and the soft package battery is a LAND battery testing system of Wuhanjinnuo electronic Co.
Performance test results of the composite anode materials of examples 1 to 4 and comparative examples 1 to 6:
table 1 preparation process and components of composite anode materials in examples 1 to 4 and comparative examples 1 to 6:
Figure BDA0002929890340000091
Figure BDA0002929890340000101
table 2 electrochemical performance test data of the composite anode materials in examples 1 to 4 and comparative examples 1 to 6:
Figure BDA0002929890340000102
as can be seen from table 1, the composite negative electrode material prepared by the method of the present application has the advantages that the carbon material can obviously improve the multiplying power, the low-temperature performance and the long cycle performance, the silicon particles can obviously improve the specific capacity of the composite negative electrode material, and meanwhile, the effective carbon coating layer can reduce the lithium ion loss in the early stage and improve the structural stability of the material. The first reversible capacity of the composite negative electrode material reaches over 600mAh/g, and the first efficiency is more than 85%.
In examples 1 to 5, the electrochemical performance of the composite anode material can be greatly affected by changing the carbonaceous raw material, the type and content of the silicon particles, and the type and content of the carbon coating, when the content of the silicon particles is the highest, the first reversible capacity of the obtained composite anode material is the highest, and is 648.6mAh/g, and the first efficiency is also the highest at this time, and is 85.1%, because the silicon-carbon composite material not only has a higher reversible capacity, but also has a good first efficiency, and can significantly improve the performance of the composite anode material in this respect, but the silicon-carbon anode material has a poor cycle performance, and when the content of the silicon particles is the highest, the cycle performance is also significantly reduced, and the capacity retention ratio of the soft-package battery 1C/1C cycle for 1500 weeks is only 84.9%.
In comparative example 1, the electrochemical performance of the composite negative electrode material is obviously affected by the magnetic foreign matters with higher inevitable content in the material without acid cleaning and purification, and the capacity retention rate of the soft package battery with 1C/1C cycle for 1500 weeks is only 78.3%.
In comparative example 2, the particle size D50 after sintering is 15 ± 1 μm, which is significantly larger than that in the example, the lithium ion diffusion path is increased, the morphology is irregular, which is not favorable for uniform coating of the polymer, and the electrochemical performance of the prepared composite anode material is far inferior to that of the anode material prepared in the example.
In comparative example 3, the first reversible capacity and the first efficiency of the obtained composite anode material were significantly decreased without adding silicon particles, respectively 391.5mAh/g, 81.8%.
In comparative example 4, the carbonaceous material and the silicon-carbon composite material were mixed at a mass ratio of 95:5 to reduce the silicon particle content, and the first reversible capacity and the first efficiency of the obtained composite anode material were reduced accordingly, respectively 417.2mAh/g and 83.6%.
In comparative example 5, the carbonaceous material and the silicon-carbon composite material are mixed according to the mass ratio of 5:5, the content of silicon particles is higher, although the prepared composite negative electrode material has higher first reversible capacity and first efficiency, the cycle performance is obviously deteriorated, and the capacity retention rate of the soft package battery after 1C/1C cycle for 1500 weeks is only 67.4 percent
In comparative example 6, carbon coating is not added, the reversible capacity and the first efficiency of the prepared composite negative electrode material are slightly improved, but the cycle performance is obviously reduced, and the capacity retention rate of the soft-package battery after 1C/1C cycle for 1500 weeks is 75.9%.
The composite negative electrode material for the lithium ion battery and the preparation method thereof have the following beneficial effects:
(1) the composite negative electrode material for the lithium ion battery prepared by the invention contains the carbon material, so that the multiplying power, the low temperature and the long cycle performance of the lithium ion battery can be obviously improved;
(2) the composite negative electrode material for the lithium ion battery prepared by the invention contains silicon particles, has high specific capacity and first reversible capacity of more than 600 mAh/g;
(3) the composite negative electrode material for the lithium ion battery prepared by the invention contains the coated carbon, so that the early-stage lithium ion loss can be reduced, the initial coulomb efficiency is more than 85%, and meanwhile, the structural stability of the material is improved, and the cycle performance is improved;
(4) the composite cathode material for the lithium ion battery prepared by the invention has the advantages of low price of raw materials, mature preparation process and equipment, and suitability for large-scale production;
(5) when the composite negative electrode material prepared by the invention is used as a negative electrode active material of a lithium ion battery, the composite negative electrode material has excellent cycle performance, and the capacity retention rate after 1500 cycles under the 1C/1C multiplying power is about 84%.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.

Claims (10)

1. A composite anode material for a lithium ion battery, comprising: the carbon material is not graphitized and has a disordered microcrystalline structure; the size of silicon crystal grains in the silicon particles is less than 15 nm; the coated carbon is amorphous carbon formed by cracking a carbon source material at a high temperature, and at least part of the surfaces of the carbonaceous material and the silicon particles is covered by the coated carbon.
2. The composite anode material for a lithium ion battery according to claim 1, wherein the mass fraction of the carbonaceous material is 50% to 90%, the mass fraction of the silicon particles is 5% to 30%, and the mass fraction of the coated carbon is 5% to 20%.
3. The composite negative electrode material for lithium ion batteries according to claim 1, wherein the carbonaceous material has a particle size D50 of 3 μm to 10 μm and a powder compacted density of 1.0g/cm3-1.4g/cm3Tap density of 0.8g/cm3-1.5g/cm3。
4. The composite negative electrode material for a lithium ion battery according to claim 1, wherein the carbonaceous material has an interlayer spacing d002 of 002 face of 0.33nm to 0.37nm as measured by XRD.
5. The composite anode material for lithium ion batteries according to claim 1, wherein the silicon particles are one of elemental silicon, nano silica, silicon carbon composite, silicon oxide (SiOx, wherein 0.5. ltoreq. x.ltoreq.2), silicon alloy, and porous silicon.
6. The composite anode material for the lithium ion battery according to claim 1, wherein the carbon source material is one or more of methane, ethane, ethylene, acetylene, propane, propylene, acetone, butylene, pentane and hexane.
7. The composite anode material for a lithium ion battery according to claim 1, wherein an average thickness of the coated carbon is 50nm to 1000 nm.
8. The composite anode material for a lithium ion battery according to claim 1, wherein the composite anode material has a specific surface area of 1m2/g-20m2And the median particle diameter D50 of the composite negative electrode material is 5-30 μm.
9. The composite anode material for a lithium ion battery according to claim 1 or 8, wherein the specific surface area of the composite anode material is 1m2/g-12m2The median particle diameter D50 of the composite negative electrode material is 6-18 μm.
10. A method for preparing a composite anode material for a lithium ion battery, wherein the composite anode material comprises the composite anode material for a lithium ion battery according to any one of claims 1 to 9, and the method comprises the steps of:
preparing a carbonaceous material precursor, silicon particles and a carbon source material;
sintering the carbonaceous material precursor at the low temperature of 300-500 ℃ for 2-5 h in an inert gas environment to obtain a first sintered material;
soaking the first calcined material by using dilute hydrochloric acid, and then cleaning the first calcined material by using pure water until the pH value of a soaking solution is 6-8 to obtain a first purified material;
sintering the first purified material at the high temperature of 1000-1300 ℃ for 2-5 h in an inert gas environment to obtain a second sintered material;
crushing the second fired material to obtain a carbonaceous material;
compounding the carbonaceous material and the silicon particles to obtain a composite powder material;
and calcining the composite powder and the carbon source material at the high temperature of 700-1000 ℃ for 2-6 h in an inert gas environment to obtain the composite cathode material.
CN202110143078.9A 2021-02-02 2021-02-02 Composite negative electrode material for lithium ion battery and preparation method thereof Pending CN112968155A (en)

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