CN106560940A - High volume capacity silicon carbon negative electrode and preparation method thereof, and lithium ion battery - Google Patents

High volume capacity silicon carbon negative electrode and preparation method thereof, and lithium ion battery Download PDF

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Publication number
CN106560940A
CN106560940A CN201610681521.7A CN201610681521A CN106560940A CN 106560940 A CN106560940 A CN 106560940A CN 201610681521 A CN201610681521 A CN 201610681521A CN 106560940 A CN106560940 A CN 106560940A
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active layer
silicon
parts
negative electrode
weight
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王继生
孟亚斌
於志锋
蔡家培
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SHENZHEN UTILITY POWER SOURCE Co Ltd
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SHENZHEN UTILITY POWER SOURCE Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of 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
    • H01M4/621—Binders
    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • 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

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The present invention provides a silicon carbon negative electrode and a preparation method thereof, and a lithium ion battery. The silicon carbon negative electrode comprises a current collector, which is provided with two oppositely arranged surfaces, wherein one surface is coated with a first active layer, and the other surface is coated with a second active layer. According to the present invention, the silicon carbon negative electrode has characteristics of stable structure and good electrochemical performance, the process condition of the preparation method is controllable, and the prepared silicon carbon negative electrode has the stable performance; and the lithium ion battery contains the silicon carbon negative electrode, and has characteristics of stable cycle performance, long service life, and high safety performance.

Description

High gram capacity silicon-carbon negative electrode and preparation method thereof and lithium ion battery
Technical Field
The invention belongs to the technical field of batteries, and particularly relates to a high-gram-capacity silicon-carbon negative electrode, a preparation method thereof and a lithium ion battery.
Background
Lithium ion batteries are widely used in mobile phones and notebook batteries, power batteries, energy storage batteries, and the like due to their excellent properties such as high voltage, high energy density, and long cycle life. The battery of the mobile phone and the notebook computer is completely occupied by the lithium ion battery, and the battery of other types can not meet the strict requirements of the portable intelligent equipment. With the development of lithium ion battery technology, the proportion of the lithium ion battery in the power battery energy storage battery is also getting larger and larger, and from the current development trend, the lithium ion battery is in a rapid development stage and has a wide application prospect.
With the increase of the light weight, the multi-functionality and the screen of smart phones and notebook computers, the existing lithium ion batteries are also difficult to meet the increasingly harsh requirements of consumer electronics on the batteries, and a novel technology is urgently needed to effectively improve the specific energy of the lithium ion batteries. Lithium ion batteries generally include four key materials, including a negative electrode, a separator, an electrolyte, a positive electrode, and other auxiliary materials. In the four key materials, the negative electrode and the positive electrode are core materials, and the specific capacity and the lithium intercalation and deintercalation voltage of the negative electrode and the positive electrode determine the specific energy of the lithium ion battery. The commonly used anode materials of the current lithium ion battery comprise lithium cobaltate, lithium manganate, ternary lithium iron phosphate and lithium iron phosphate, and the specific capacity is between 100 and 200 mAh/g; the commonly used negative electrode material is a carbon negative electrode material, and the specific capacity is 250-360 mAh/g.
The specific capacity of the negative electrode material is improved, so that the specific capacity of the battery is effectively improved. At present, graphite, silicon-based, tin-based, nano carbon materials, metal oxides and the like are used as negative electrode materials of lithium ion batteries. However, the silicon-based negative electrode material is accompanied by severe volume expansion in the lithium intercalation and deintercalation process, leading to pulverization and exfoliation of electroactive substances and continuous formation of a solid electrolyte membrane, directly leading to the problems of rapid specific capacity attenuation, low charging and discharging efficiency, short cycle life and the like, and leading to severe limitation on the application of the high-gram-capacity silicon-carbon composite negative electrode material in the lithium ion battery. Although the silicon-carbon composite negative electrode material, such as the carbon-coated silicon composite negative electrode material, is adopted at present to overcome the defect of volume expansion of silicon in the lithium intercalation and deintercalation process, the effect is limited, and the composite material still undergoes volume expansion in the charging and discharging process, so that the problems of pulverization and exfoliation of a silicon-carbon composite active substance and formation of a solid electrolyte membrane still occur, and the problems of fast capacity attenuation, short cycle life and the like are still directly caused. Although a binder is added to the silicon-carbon composite negative electrode, conventional binder systems have limited binding strength, and during silicon-carbon cycling, peeling between negative active materials occurs, thereby losing effective electrical contact.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a silicon-carbon negative electrode and a preparation method thereof, so as to solve the technical problems of pulverization and falling of active substances and unstable structure of a silicon-carbon electrode plate caused by volume expansion of a silicon-carbon active material in the charging and discharging processes of a battery.
Another objective of the present invention is to provide a silicon-carbon lithium ion battery to solve the technical problems of fast capacity fading, poor cyclicity and short service life of the existing silicon-carbon lithium ion battery.
In order to achieve the above object, according to one aspect of the present invention, there is provided a silicon-carbon negative electrode.
A silicon-carbon negative electrode comprises a current collector, wherein the current collector comprises two oppositely arranged surfaces, a first active layer is coated on one surface, and a second active layer is coated on the other surface; wherein,
the first active layer comprises the following components in parts by weight:
92.5-94.5 parts of silicon-carbon composite material
2.5-3.5 parts of first conductive agent
Sodium carboxymethyl cellulose 1.0-1.5 parts
2.0-2.5 parts of modified acrylic acid binder;
the second active layer comprises the following components in parts by weight:
92.5-94.5 parts of silicon-carbon composite material
1.5-2.5 parts of second conductive agent
Polyimide binder 4.0-5.0 parts
Oxalic acid 1.5-3.0 parts.
In another aspect of the invention, a method for preparing a silicon-carbon negative electrode is provided. The preparation method of the silicon-carbon negative electrode comprises the following steps:
preparing a first active layer slurry according to the following components contained in the first active layer slurry and the component proportion thereof and a preparation method of the electrode slurry, wherein the first active layer slurry comprises the following components in parts by weight:
92.5-94.5 parts of silicon-carbon composite material
2.5-3.5 parts of first conductive agent
Sodium carboxymethyl cellulose 1.0-1.5 parts
2.0-2.5 parts of modified acrylic acid binder
NMP 3.0-5.0 parts
3.0 to 5.0 portions of absolute ethyl alcohol
Deionized water content: 120-150 parts;
preparing a second active layer slurry according to the components contained in the second active layer slurry and the component proportion thereof and the preparation method of the electrode slurry, wherein the second active layer slurry comprises the following components in parts by weight:
92.5-94.5 parts of silicon-carbon composite material
1.5-2.5 parts of second conductive agent
Polyimide binder 4.0-5.0 parts
Oxalic acid 1.5-3.0 parts
30.0-80.0 parts of an oily solvent;
coating the first active layer slurry on one surface of two oppositely arranged surface negative current collectors, and drying to form a first active layer;
and coating the second active layer slurry on the other surface of the negative current collector, and drying to form a second active layer.
In another aspect of the present invention, a lithium ion battery is provided, which contains the silicon-carbon negative electrode of the present invention or the silicon-carbon negative electrode prepared by the preparation method of the present invention.
Compared with the prior art, the silicon-carbon negative electrode has the advantages that the modified acrylic acid binder contained in the first active layer can reduce the volume expansion of the silicon-carbon composite material in the circulation process, and the polyimide binder contained in the second active layer and oxalic acid act to enhance the binding performance of the silicon-carbon composite negative electrode material and enhance the binding performance between the silicon-carbon composite negative electrode material and a current collector. Therefore, the first active layer can form a more stable SEI film after being charged for the first time, the second active layer can enhance the bonding performance among negative active materials and between the negative active materials and a current collector, and can effectively inhibit the volume expansion of a silicon-carbon negative electrode, so that the cycle performance of the battery is enhanced through the synergistic effect of the first active layer and the second active layer.
According to the preparation method of the silicon-carbon negative electrode, the surface of one side of a negative current collector is coated with the modified acrylic acid to be used as the binder of the silicon-carbon composite material to prepare the water-based slurry, the other side of the current collector is coated with the polyimide to be used as the binder of the silicon-carbon composite material to prepare the oil-based slurry, and the prepared silicon-carbon negative electrode has excellent structural stability through the synergistic effect of the two active layers, so that the phenomenon of pulverization and falling of the negative active layer caused by the volume expansion of the silicon-carbon composite active material in the charging and discharging processes can be effectively overcome. In addition, the preparation method has controllable process conditions, and the prepared silicon-carbon negative electrode has stable performance.
The lithium ion battery of the invention contains the silicon-carbon negative electrode, so the lithium ion battery of the invention can apply the silicon-carbon composite material with high gram capacity, and has stable cycle performance, long service life and high safety performance.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a process step diagram of a silicon-carbon negative electrode preparation method according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The parts by weight of the relevant components mentioned in the description of the embodiments of the present invention may not only refer to the content of each component but also to the weight ratio among the components, and therefore, it is within the scope of the disclosure of the description of the embodiments of the present invention to scale up or down the content of the relevant components according to the description of the embodiments of the present invention. Specifically, the weight described in the description of the embodiment of the present invention may be a unit of mass known in the chemical industry field, such as μ g, mg, g, and kg.
In one aspect, the embodiment of the invention provides a silicon-carbon negative electrode with stable structure and electrochemical performance and good cyclicity. The silicon-carbon negative electrode comprises a current collector and a negative active layer coated on the surface of the current collector.
The current collector comprises two opposite surfaces, the negative active layer is composed of a first active layer and a second active layer, the first active layer is coated on one side surface of the current collector, and the second active layer is coated on the other side surface of the current collector.
In one embodiment, the first active layer (dry powder) comprises the following components in parts by weight:
92.5-94.5 parts of silicon-carbon composite material
2.5-3.5 parts of first conductive agent
Sodium carboxymethyl cellulose 1.0-1.5 parts
2.0-2.5 parts of modified acrylic acid binder.
In a specific embodiment, the silicon-carbon composite material is a high-capacity silicon-carbon material, such as a silicon-carbon composite material containing silicon monoxide or a silicon-carbon composite material containing pure silicon. Wherein the weight content of the inferior silicon in the silicon carbon composite material of the inferior silicon oxide is not less than 5 percent, and the weight content of the pure silicon in the silicon carbon composite material containing the pure silicon is not less than 3 percent. For example, in one embodiment, the silicon-carbon composite material is silicon oxide + artificial graphite, i.e., the silicon-carbon composite material is obtained by mixing synthesized silicon oxide and artificial graphite; or carbon-coated nano-silicon and artificial graphite, namely a silicon-carbon composite material obtained by mixing carbon-coated nano-silicon and artificial graphite.
The silicon-carbon composite material with high gram capacity has high specific capacity on one hand and relatively small volume expansion rate on the other hand. This can assist the negative active layer to further improve the structural stability and chemical stability of the negative electrode.
The first conductive agent can be a conventional conductive agent, and in one embodiment, the first conductive agent is a mixture of CNTs and SP, and the weight ratio of CNTs to SP is (1-1.5): (1.5-2). The conductive performance of the first active layer is provided by using the linear CNTs in combination with SP.
The modified acrylic acid adhesive can be directly purchased in the market, such as a modified acrylic acid emulsion adhesive and an acrylic acid modified chitosan derivative adhesive (such as a modified acrylic acid emulsion adhesive supplied by Shanghai Yi of suppliers and an acrylic acid modified chitosan derivative adhesive supplied by Korland).
In another embodiment, the second active layer (dry powder) comprises the following components in parts by weight:
92.5-94.5% of silicon-carbon composite material
1.5 to 2.5 percent of second conductive agent
Polyimide binder 4.0-5.0%
Oxalic acid 1.5-3.0 parts.
In a specific embodiment, the silicon-carbon composite material is a high-capacity silicon-carbon material, such as a silicon-carbon composite material containing silicon monoxide or a silicon-carbon composite material containing pure silicon. Wherein the weight content of the inferior silicon in the silicon carbon composite material of the inferior silicon oxide is not less than 5 percent, and the weight content of the pure silicon in the silicon carbon composite material containing the pure silicon is not less than 3 percent. For example, in one embodiment, the silicon-carbon composite material is silicon oxide + artificial graphite, i.e., the silicon-carbon composite material is obtained by mixing synthesized silicon oxide and artificial graphite; or carbon-coated nano-silicon and artificial graphite, namely a silicon-carbon composite material obtained by mixing carbon-coated nano-silicon and artificial graphite. The silicon-carbon composite material has high specific capacity on one hand and relatively small volume expansion rate on the other hand. This can assist the negative active layer to further improve the structural stability and chemical stability of the negative electrode.
The first conductive agent can be a conventional conductive agent, and in one embodiment, the first conductive agent is a mixture of CNTs and SP, and the weight ratio of CNTs to SP is (1-1.5): (1.5-2). The conductive performance of the first active layer is provided by using the linear CNTs in combination with SP.
In another embodiment, the polyimide binder may be, but is not limited to, a polyimide binder having a solids content of 15.0% to 25.0%.
Therefore, the modified acrylic acid binder contained in the first active layer can reduce the volume expansion of the silicon-carbon composite material in the circulation process, and more importantly, the first active layer can form a more stable SEI film in the first charging process; the polyimide binder contained in the second active layer and oxalic acid act to enhance the binding property of the silicon-carbon composite negative electrode material, enhance the binding property between the silicon-carbon composite negative electrode material and a current collector, and effectively inhibit the volume expansion of the silicon-carbon composite negative electrode material. Therefore, the silicon-carbon negative electrode of the invention is endowed with excellent structural stability and electrochemical stability performance, such as cycle performance, through the synergistic action of the two active layers.
In addition, in order to make the silicon carbon negative electrode have high gram capacity and stable structure, in a specific embodiment, the thickness of the first active layer is 90 μm-100 μm. In another specific embodiment, the thickness of the second active layer is 90 μm to 100 μm.
In a specific embodiment, in each of the above silicon-carbon negative electrode embodiments, the current collector included in the silicon-carbon negative electrode may be a negative current collector commonly used in lithium ion batteries, such as a copper foil.
Therefore, the silicon-carbon negative electrode of the embodiment of the invention has the advantages that the first active layer containing the modified acrylic acid binder and the second active layer containing the polyimide binder are combined with each other to generate a synergistic effect, so that the silicon-carbon negative electrode of the embodiment of the invention has high gram capacity and stable structure, the phenomena of pulverization and shedding of the negative active layer and continuous formation of a solid electrolyte membrane caused by volume expansion of the silicon-carbon composite material in the charging and discharging processes are effectively overcome, and the electrochemical performance of the silicon-carbon negative electrode is effectively improved.
On the other hand, the embodiment of the invention also provides a preparation method of the silicon-carbon negative electrode in the embodiment of the invention. In one embodiment, the process steps of the preparation method of the silicon-carbon negative electrode according to the embodiment of the invention are shown in fig. 1, and the preparation method comprises the following steps:
step S01, preparing a first active layer slurry: preparing a first active layer slurry according to components contained in the first active layer slurry and the component proportion thereof and a preparation method of the electrode slurry:
step S02, preparing second active layer slurry: preparing a second active layer slurry according to components contained in the second active layer slurry and the component proportion thereof and a preparation method of the electrode slurry;
step S03, coating a first active layer on one side of the surface of the current collector: coating the first active layer slurry on one surface of two oppositely-arranged surface negative current collectors, and drying to form a first active layer;
step S04, coating a second active layer on the other side of the surface of the current collector: and coating the second active layer slurry on the other surface of the negative current collector, and drying to form a second active layer.
Specifically, in step S01, as an embodiment of the present invention, the first active layer slurry includes the following components in parts by weight, and therefore, the first active layer slurry is an aqueous slurry:
92.5-94.5 parts of silicon-carbon composite material
2.5-3.5 parts of first conductive agent
Sodium carboxymethyl cellulose 1.0-1.5 parts
2.0-2.5 parts of modified acrylic acid binder
NMP 3.0-5.0 parts
3.0 to 5.0 portions of absolute ethyl alcohol
The content of the deionized water is 120 to 150 portions.
The silicon-carbon composite material, the first conductive agent, the sodium carboxymethyl cellulose and the modified acrylic acid binder contained in the first active layer slurry of the first active layer are all as described above, and are not described again. In specific examples, the NMP may be contained in an amount of 3.0 parts by weight, 4.0 parts by weight, 5.0 parts by weight, or 4.0 parts by weight, or the absolute ethyl alcohol may be contained in an amount of 3.0 parts by weight, 4.0 parts by weight, or 5.0 parts by weight, or 4.0 parts by weight. In one embodiment, the viscosity of the first active layer slurry is adjusted to 3000-4000mpa.s by the addition amount of the aqueous solvent, so as to realize uniform coating of the first active layer slurry and ensure uniformity of the active layer.
In step S02, as an embodiment of the present invention, the second active layer slurry includes the following components in parts by weight, and therefore, the second active layer slurry is an oil-based slurry:
92.5-94.5 parts of silicon-carbon composite material
1.5-2.5 parts of second conductive agent
Polyimide binder 4.0-5.0 parts
Oxalic acid 1.5-3.0 parts
30.0-80.0 parts of oily solvent.
The silicon-carbon composite material, the second conductive agent and the polyimide binder contained in the slurry of the second active layer are all as described above, and are not described again. The oily solvent can be an organic solvent capable of effectively loading a polyimide binder and dispersing a silicon-carbon composite material, such as NMP and the like. In an embodiment, the viscosity of the second active layer slurry is set to be 5000-7000mpa.s by the addition amount of the oily solvent, so as to realize uniform coating of the second active layer slurry and ensure uniformity of the whole active layer.
In addition, the step S01 and the step S02 have no sequence.
In the above step S03, the first active layer slurry is coated on the negative electrode current collector surface side, which may be, but not exclusively, coated according to a conventional coating process.
In one embodiment, the thickness of the first active layer formed by controlling the amount of the first active layer slurry applied is 90 μm to 100 μm. The silicon-carbon negative electrode of the embodiment of the invention has high gram capacity and excellent structural stability by controlling the thickness of the coating and playing a synergistic effect with the second active layer in the step S04.
As an embodiment of the present invention, the drying condition of step S03 is 120-130 ℃ to remove the solvent.
The negative electrode current collector in step S03 may be a negative electrode current collector commonly used in lithium ion batteries, such as a copper foil.
The second active layer slurry coated on the other side of the surface of the negative current collector in the above step S04 may be, but is not limited to, coated according to a conventional coating process.
In one embodiment, the thickness of the second active layer formed by controlling the amount of the second active layer slurry applied is 90 μm to 100 μm. The silicon-carbon negative electrode of the embodiment of the invention has high gram capacity and excellent structural stability by controlling the thickness of the coating and playing a synergistic effect with the second active layer in the step S03.
As an embodiment of the present invention, the drying condition of step S04 is 140-150 ℃ to remove the oily solvent.
On the basis of the above preparation method embodiments, after the step S04, the method further includes a step of subjecting the electrode coated with the first active layer and the second active layer to a heat treatment at 350 ℃ to 380 ℃. In a particular embodiment, the time of the heat treatment is 8 to 12 hours, preferably 8 hours. It is preferred to perform the vacuum heat treatment at this temperature. Through the heat treatment, the polyimide binder can be activated to increase the bonding strength, so that the polyimide binder and the anode material are uniformly and tightly bonded.
It is needless to say that the method for preparing a silicon-carbon negative electrode according to the embodiment of the present invention further includes other conventional process steps of the electrode sheet, such as sheet production and the like, after the step S04.
Therefore, in the silicon-carbon negative electrode preparation method provided by the embodiment of the invention, the modified acrylic acid is used as the binder of the silicon-carbon composite material to prepare the aqueous slurry, the polyimide is used as the binder of the silicon-carbon composite material to prepare the oily slurry, the first active layer and the second active layer are respectively formed on the two sides of the current collector, and the prepared silicon-carbon negative electrode has excellent structural stability through the synergistic effect of the two active layers. In addition, the preparation method provided by the embodiment of the invention has controllable process conditions, and the prepared silicon-carbon negative electrode has stable performance.
In another aspect, based on the silicon-carbon negative electrode and the preparation method thereof, embodiments of the present invention further provide a lithium ion battery. The structure of the lithium ion battery can be similar to the conventional structure of the lithium ion battery, wherein the negative electrode contained in the lithium ion battery is the silicon-carbon negative electrode of the embodiment of the invention or the silicon-carbon negative electrode prepared by the preparation method of the embodiment of the invention.
Thus, since the lithium ion battery of the embodiment of the invention contains the silicon-carbon negative electrode of the embodiment of the invention, the lithium ion battery of the embodiment of the invention has excellent electrochemical performance, such as excellent cycle performance and safety performance, long service life and high gram capacity.
A number of embodiments of the above-described silicon-carbon negative electrodes and methods of making the same will now be provided to further illustrate the invention.
Example 1
The embodiment provides a silicon-carbon negative electrode and a preparation method thereof. The silicon-carbon negative electrode comprises a negative current collector and a negative active layer coated on the surface of the current collector, wherein the negative active layer is composed of a first active layer and a second active layer, the first active layer is coated on one side of the current collector, the second active layer is coated on the other side of the current collector, the first active layer contains a modified acrylic emulsion binder, and the second active layer contains a polyimide binder.
The preparation method of the silicon-carbon negative electrode of the embodiment is as follows:
s11, preparing first active layer slurry:
93.0 parts of silicon carbon, 1.2 parts of CNTs, 1.8 parts of SP, 1.5 parts of CMC, 2.5 parts of modified acrylic emulsion binder, 4.0 parts of NMP, 4.0 parts of absolute ethyl alcohol and 120.0 parts of deionized water are prepared into first active layer slurry.
S12, preparing second active layer slurry:
93.0 parts of silicon carbon, CNTs: 1.2 parts by weight, 0.8 part by weight of SP, 5.0 parts by weight of polyimide binder, 2 parts by weight of oxalic acid, and 80.0 parts by weight of NMP were prepared into a second active layer slurry.
S13, coating the first active layer slurry on the surface of one side of a negative current collector, and drying to form a first active layer with the thickness of 100 +/-2 microns;
s14, coating the second active layer slurry on the other side surface of the negative current collector, and drying to form a second active layer of 100 +/-2 microns;
and S15, baking for 8 hours in a vacuum oven at 350-380 ℃ to uniformly bond the polyimide binder and the negative electrode material, and then performing subsequent tabletting and other procedures on the pole piece to prepare the silicon-carbon negative electrode.
Comparative example 1
93.0 parts by weight of silicon carbon, 1.2 parts by weight of CNTs, 1.8 parts by weight of SP, 1.5 parts by weight of CMC, 2.5 parts by weight of SBR, 4.0 parts by weight of NMP, 4.0 parts by weight of absolute ethyl alcohol and 120.0 parts by weight of deionized water are prepared into slurry, and an active layer of 100 +/-2 mu m is formed on the surface coating of the negative current collector according to the coating mode of the embodiment 1 to form a silicon carbon negative electrode.
Example 2
The embodiment provides a silicon-carbon negative electrode and a preparation method thereof. The silicon-carbon negative electrode of this example was constructed as in example 1.
The preparation method of the silicon-carbon negative electrode of the embodiment is as follows:
step S21, preparing first active layer slurry:
93.0 parts by weight of silicon carbon, 1.4 parts by weight of CNTs, 1.8 parts by weight of SP, 1.4 parts by weight of CMC, 2.4 parts by weight of acrylic acid modified chitosan derivative binder, 4.0 parts by weight of NMP, 4.0 parts by weight of absolute ethyl alcohol and 120.0 parts by weight of deionized water are prepared into first active layer slurry.
Step S22, preparing second active layer slurry:
93.0 parts by weight of silicon carbon, 1.3 parts by weight of CNTs, 0.9 part by weight of SP, 4.8% by weight of polyimide binder, 1.5 parts by weight of oxalic acid and 30.0 parts by weight of NMP are prepared into second active layer slurry.
S23, coating the first active layer slurry on the surface of one side of a negative current collector, and drying to form a first active layer with the thickness of 100 +/-2 microns;
s24, coating the second active layer slurry on the other side surface of the negative current collector, and drying to form a second active layer of 100 +/-2 microns;
and S25, baking for 8 hours in a vacuum oven at 350-380 ℃ to uniformly bond the polyimide binder and the negative electrode material, and then performing subsequent tabletting and other procedures on the pole piece to prepare the silicon-carbon negative electrode.
Comparative example 2
93.0 parts by weight of silicon carbon, 1.4 parts by weight of CNTs, 1.8 parts by weight of SP, 1.4 parts by weight of CMC, 2.4 parts by weight of SBR, 4.0 parts by weight of NMP, 4.0 parts by weight of absolute ethyl alcohol and 120.0 parts by weight of deionized water are prepared into slurry, and an active layer with the thickness of 100 +/-2 mu m is formed on the surface coating of the negative current collector according to the coating mode of the embodiment 2 to form a silicon carbon negative electrode.
Example 3
The embodiment provides a silicon-carbon negative electrode and a preparation method thereof. The silicon-carbon negative electrode of this example was constructed as in example 1.
The preparation method of the silicon-carbon negative electrode of the embodiment is as follows:
step S31, preparing first active layer slurry:
93.0 parts by weight of silicon carbon, 1.5 parts by weight of CNTs, 1.7 parts by weight of SP, 1.3 parts by weight of CMC, 2.5 parts by weight of acrylic acid modified chitosan derivative binder, 4.0 parts by weight of NMP, 4.0 parts by weight of absolute ethyl alcohol and 120.0 parts by weight of deionized water are prepared into first active layer slurry.
Step S32, preparing second active layer slurry:
93.0 parts of silicon carbon, CNTs: 1.5 parts by weight, 1.0 part by weight of SP, 4.5 parts by weight of polyimide binder, 3 parts by weight of oxalic acid, and 50.0 parts by weight of NMP were prepared to prepare a second active layer slurry.
S33, coating the first active layer slurry on the surface of one side, and drying to form a first active layer with the thickness of 100 +/-2 microns;
s34, coating the second active layer slurry on the other side surface of the negative current collector, and drying to form a second active layer of 100 +/-2 microns;
and S35, baking for 8 hours at 350-380 ℃ in a vacuum oven to uniformly bond the polyimide binder and the negative electrode material, and then performing subsequent tabletting and other procedures on the pole piece to prepare the silicon-carbon negative electrode.
Comparative example 3
93.0 parts by weight of silicon carbon, 1.5 parts by weight of CNTs, 1.7 parts by weight of SP, 1.3 parts by weight of CMC, 2.5 parts by weight of SBR, 4.0 parts by weight of NMP, 4.0 parts by weight of absolute ethyl alcohol and 120.0 parts by weight of deionized water are prepared into slurry, and an active layer with the thickness of 100 +/-2 mu m is formed on the surface coating of the negative current collector according to the coating mode of the embodiment 3 to form a silicon carbon negative electrode.
Example 4
The embodiment provides a silicon-carbon negative electrode and a preparation method thereof. The silicon-carbon negative electrode of this example was constructed as in example 1.
The preparation method of the silicon-carbon negative electrode of the embodiment is as follows:
step S41, preparing first active layer slurry:
93.0 parts by weight of silicon carbon, 1.5 parts by weight of CNTs, 1.5 parts by weight of SP, 1.5 parts by weight of CMC, 2.5 parts by weight of acrylic acid modified chitosan derivative binder, 4.0 parts by weight of NMP, 4.0 parts by weight of absolute ethyl alcohol and 120.0 parts by weight of deionized water are prepared into aqueous first active layer slurry;
step S42, preparing second active layer slurry:
93.0 parts by weight of silicon carbon, 1.5 parts by weight of CNTs, 0.5 part by weight of SP, 5.0 parts by weight of polyimide binder, 2 parts by weight of oxalic acid and 60.0 parts by weight of NMP are prepared into oil-type second active layer slurry;
s43, coating the first active layer slurry on the surface of one side of a negative current collector, and drying to form a first active layer with the thickness of 100 +/-2 microns;
s44, coating the second active layer slurry on the other side surface of the negative current collector, and drying to form a second active layer of 100 +/-2 microns;
and S45, baking for 8 hours in a vacuum oven at 350-380 ℃ to uniformly bond the polyimide binder and the negative electrode material, and then performing subsequent tabletting and other procedures on the pole piece to prepare the silicon-carbon negative electrode.
Comparative example 4
93.0 parts by weight of silicon carbon, 1.5 parts by weight of CNTs, 1.5 parts by weight of SP, 1.5 parts by weight of CMC, 2.5 parts by weight of SBR, 4.0 parts by weight of NMP, 4.0 parts by weight of absolute ethyl alcohol and 120.0 parts by weight of deionized water are prepared into slurry, and an active layer with the thickness of 100 +/-2 mu m is formed on the surface coating of the negative current collector according to the coating mode of the embodiment 1 to form a silicon carbon negative electrode.
Example 5
The embodiment provides a silicon-carbon negative electrode and a preparation method thereof. The silicon-carbon negative electrode of this example was constructed as in example 1.
The preparation method of the silicon-carbon negative electrode of the embodiment is as follows:
step S51, preparing first active layer slurry:
93.0 parts by weight of silicon carbon, 1.0 part by weight of CNTs, 2.0 parts by weight of SP, 1.3 parts by weight of CMC, 2.5 parts by weight of modified acrylic emulsion binder, 4.0 parts by weight of NMP, 4.0 parts by weight of absolute ethyl alcohol and 120.0 parts by weight of deionized water are prepared into first active layer slurry;
s52, preparing second active layer slurry:
93.0 parts of silicon carbon, 1.5 parts of CNTs, 1.0 part of SP, 4.5 parts of polyimide binder, 2 parts of oxalic acid and 30.0 parts of NMP;
s53, coating the first active layer slurry on the surface of one side of a negative current collector, and drying to form a first active layer with the thickness of 100 +/-2 microns;
s54, coating the second active layer slurry on the other side surface of the negative current collector, and drying to form a second active layer of 100 +/-2 microns;
and S55, baking for 8 hours in a vacuum oven at 350-380 ℃ to uniformly bond the polyimide binder and the negative electrode material, and then performing subsequent tabletting and other procedures on the pole piece to prepare the silicon-carbon negative electrode.
Comparative example 5
93.0 parts by weight of silicon carbon, 1.0 part by weight of CNTs, 2.0 parts by weight of SP, 1.5 parts by weight of CMC, 2.5 parts by weight of SBR, 4.0 parts by weight of NMP and 4.0 parts by weight of absolute ethyl alcohol are prepared into slurry, and an active layer with the thickness of 100 +/-2 mu m is formed on the surface coating of the negative current collector according to the coating mode of the embodiment 1 to form the silicon-carbon negative electrode.
Electrochemical performance test
The silicon-carbon negative electrodes provided in examples 1 to 5 and the negative electrode sheets provided in comparative examples 1 to 5 were assembled into lithium ion batteries according to a conventional procedure with a positive electrode sheet, an electrolyte, and the like, and each lithium ion battery was subjected to a 0.2C cycle performance test, wherein the positive electrode sheet, the electrolyte, and the like were the same except for the negative electrode sheet. The test results are shown in the following table:
from the data, the gram capacity of the battery is high, and the cycle performance is stable when the silicon-carbon negative electrode provided by the embodiment of the invention is contained, so that the silicon-carbon negative electrode provided by the embodiment of the invention effectively overcomes the phenomenon of pulverization and falling of a negative active layer caused by volume expansion of a silicon-carbon composite material in the charging and discharging processes, and has excellent structural stability. Therefore, the lithium ion battery provided by the embodiment of the invention has the advantages of long service life, stable cycle performance and high safety performance.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (9)

1. A silicon-carbon negative electrode comprises a current collector, wherein the current collector comprises two oppositely arranged surfaces, a first active layer is coated on one surface, and a second active layer is coated on the other surface; wherein,
the first active layer comprises the following components in parts by weight:
the second active layer comprises the following components in parts by weight:
2. the silicon-carbon negative electrode of claim 1, wherein: the thickness of the first active layer is 90-100 μm; and/or the thickness of the second active layer is 90 μm to 100 μm.
3. The silicon-carbon negative electrode of claim 1 or 2, wherein: the first conductive agent is a mixture of CNTs and SP, and the weight ratio of CNTs to SP is (1-1.5) to (1.5-2); and/or the second conductive agent is a mixture of CNTs and SP, and the weight ratio of the CNTs to the SP is (1-1.5): (0.5-1).
4. A method for preparing a silicon-carbon negative electrode, characterized by: the method comprises the following steps:
preparing a first active layer slurry according to the following components contained in the first active layer slurry and the component proportion thereof and a preparation method of the electrode slurry, wherein the first active layer slurry comprises the following components in parts by weight:
preparing a second active layer slurry according to the components contained in the second active layer slurry and the component proportion thereof and the preparation method of the electrode slurry, wherein the second active layer slurry comprises the following components in parts by weight:
coating the first active layer slurry on one surface of two oppositely arranged surface negative current collectors, and drying to form a first active layer;
and coating the second active layer slurry on the other surface of the negative current collector, and drying to form a second active layer.
5. The method of claim 4, wherein: the method also comprises the step of placing the electrode coated with the first active layer and the second active layer at 350-380 ℃ for heat treatment.
6. The method of claim 5, wherein: the heat treatment time is 8-12 hours.
7. The production method according to any one of claims 4 to 6, characterized in that: controlling the amount of the first active layer slurry to be applied so that the first active layer is formed to have a thickness of 90 μm to 100 μm; and/or by controlling the amount of the second active layer slurry applied so that the thickness of the second active layer formed is 90 μm to 100 μm.
8. The production method according to any one of claims 4 to 6, characterized in that: the first conductive agent is a mixture of CNTs and SP, and the weight ratio of CNTs to SP is (1-1.5) to (1.5-2); and/or
The second conductive agent is a mixture of CNTs and SP, and the weight ratio of the CNTs to the SP is (1-1.5): (0.5-1).
9. A lithium ion battery comprising a negative electrode, characterized in that: the negative electrode is the silicon-carbon negative electrode as defined in any one of claims 1 to 3 or prepared by the preparation method as defined in any one of claims 4 to 8.
CN201610681521.7A 2016-08-17 2016-08-17 High volume capacity silicon carbon negative electrode and preparation method thereof, and lithium ion battery Pending CN106560940A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4064383A1 (en) * 2021-03-25 2022-09-28 SK Innovation Co., Ltd. Anode for secondary battery and lithium secondary battery including the same

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102760883A (en) * 2012-07-13 2012-10-31 中国科学院广州能源研究所 Novel chitosan used for lithium ion cell and derivative water-based binder of chitosan
CN104282881A (en) * 2013-07-11 2015-01-14 浙江万向亿能动力电池有限公司 Flexible package lithium ion battery silicon negative pole and manufacturing method thereof
CN105406039A (en) * 2015-11-03 2016-03-16 山东精工电子科技有限公司 Silicon-carbon anode paste and preparation method thereof
CN105789556A (en) * 2016-04-26 2016-07-20 中国科学院长春应用化学研究所 Electrode plate and lithium ion battery

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102760883A (en) * 2012-07-13 2012-10-31 中国科学院广州能源研究所 Novel chitosan used for lithium ion cell and derivative water-based binder of chitosan
CN104282881A (en) * 2013-07-11 2015-01-14 浙江万向亿能动力电池有限公司 Flexible package lithium ion battery silicon negative pole and manufacturing method thereof
CN105406039A (en) * 2015-11-03 2016-03-16 山东精工电子科技有限公司 Silicon-carbon anode paste and preparation method thereof
CN105789556A (en) * 2016-04-26 2016-07-20 中国科学院长春应用化学研究所 Electrode plate and lithium ion battery

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4064383A1 (en) * 2021-03-25 2022-09-28 SK Innovation Co., Ltd. Anode for secondary battery and lithium secondary battery including the same
KR20220133624A (en) * 2021-03-25 2022-10-05 에스케이온 주식회사 Anode for secondary battery and lithium secondary battery including the same
EP4220752A3 (en) * 2021-03-25 2023-08-09 SK On Co., Ltd. Anode for secondary battery and lithium secondary battery including the same
KR102570427B1 (en) 2021-03-25 2023-08-24 에스케이온 주식회사 Anode for secondary battery and lithium secondary battery including the same

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