CN111900335A - Silicon-based negative electrode with self-repairing property and preparation method and application thereof - Google Patents

Silicon-based negative electrode with self-repairing property and preparation method and application thereof Download PDF

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CN111900335A
CN111900335A CN202010839274.5A CN202010839274A CN111900335A CN 111900335 A CN111900335 A CN 111900335A CN 202010839274 A CN202010839274 A CN 202010839274A CN 111900335 A CN111900335 A CN 111900335A
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active material
negative electrode
self
silicon
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CN111900335B (en
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郭盼龙
李素丽
陈伟平
李俊义
徐延铭
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Zhuhai Cosmx Battery Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/137—Electrodes based on electro-active polymers
    • 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
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • H01M4/602—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
    • 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
    • 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
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Abstract

The invention aims to provide a silicon-based negative electrode with self-repairing property, a preparation method and application thereof, wherein the self-repairing elastomer material comprises a polypropylene oxide (PPG) chain segment, a polyethylene glycol (PEG) chain segment, a polytetramethylene ether glycol (PTMG) chain segment or a Polybutadiene (PB) chain segment; the invention can solve the problems that the SEI film is damaged and the performance of the battery is influenced due to the volume expansion of the silicon-based negative electrode, and the invention improves the toughness of the SEI film and endows the SEI film with the capability of repairing the damage by constructing the high-toughness and high-strength self-repairing SEI film, realizes the adaptation and the inhibition of the volume expansion of the silicon-based negative electrode, timely repairs the damage of the SEI film, and solves the problems of continuous damage and continuous formation of the SEI film due to the volume change of the silicon-based negative electrode.

Description

Silicon-based negative electrode with self-repairing property and preparation method and application thereof
Technical Field
The invention belongs to the field of lithium ion battery cathodes, and relates to a silicon-based cathode with self-repairing property, and a preparation method and application thereof.
Background
The silicon-based cathode has extremely high theoretical capacity (nano silicon Si is 4200mAh/g, silicon oxide SiOy2680mAh/g) which is far larger than that of a graphite cathode (370mAh/g), and the partial replacement of the graphite cathode by the silicon-based cathode is the simplest and most effective method for improving the energy density of the battery. However, silicon-based materials still face a series of challenges from laboratories to enterprises, and the most important technical bottleneck at present is how to effectively inhibit the volume expansion of the silicon-based negative electrode and improve the stability of the SEI film. As more lithium ions can be inserted into and removed from the silicon-based negative electrode in the charging and discharging processes, a huge volume expansion-contraction effect is caused, further cracks and even pulverization are generated, the SEI film is continuously cracked, repeatedly formed and continuously thickened, the electrolyte is continuously consumed in the process, and finally capacity attenuation and cycle failure are caused.
At present, the improvement of the performance of the silicon-based negative electrode is mainly started from the following aspects:
(1) additives such as VC, FEC and the like are added into the electrolyte to improve the stability of the SEI film;
(2) novel binders such as polyacrylic acids and the like are used in the pole pieces, and the binders can effectively inhibit the expansion of the silicon-based negative electrode and improve the stability of the silicon-based negative electrode;
(3) the silicon-based material is coated or doped, such as carbon coating, and the coating or doping can improve the conductivity of the silicon cathode and inhibit the volume expansion of the silicon cathode.
Although the methods can improve the performance of the silicon-based negative electrode, the problems of SEI film cracking and thickening caused by volume expansion of the silicon-based negative electrode are not completely solved, and further improvement is needed. Particularly in a full battery, along with the increase of cycle times, the volume expansion of the silicon-based negative electrode leads to serious cell thickening, and the capacity is accelerated to attenuate at the later cycle period and leads to complete failure, so that the application of the silicon-based negative electrode is limited. Therefore, new methods for improving the stability of silicon-based negative electrodes need to be explored.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a silicon-based negative electrode with self-repairing property and a preparation method and application thereof, and can solve the problems that the SEI film is damaged and the battery performance is influenced due to the volume expansion of the silicon-based negative electrode.
The purpose of the invention is realized by the following technical scheme:
a self-healing elastomeric material comprising a repeating unit represented by formula I:
Figure BDA0002640837890000021
in the formula I, R1And R3Is composed of
Figure BDA0002640837890000022
Wherein R is
Figure BDA0002640837890000023
Figure BDA0002640837890000024
Figure BDA0002640837890000025
Two types of the connecting lines are different from each other, and the wavy line represents the connecting line;
R2and R4Identical or different, independently of one another, from a polypropylene oxide (PPG) segment, a polyethylene glycol (PEG) segment, a polytetramethylene ether glycol (PTMG) segment or a Polybutadiene (PB) segment;
1>x>0。
according to the invention, R is2And R4Are identical or different and are selected independently of one another
Figure BDA0002640837890000026
Figure BDA0002640837890000027
Figure BDA0002640837890000028
The wavy lines represent connecting lines, and n and m represent the number of repeating units.
According to the invention, the weight average molecular weight of the polypropylene oxide (PPG) chain segment, the polyethylene glycol (PEG) chain segment, the polytetramethylene ether glycol (PTMG) chain segment or the Polybutadiene (PB) chain segment is 500-20000.
According to the invention, the number average molecular weight of the self-repairing elastomer material is 5000-.
The invention also provides a modified silicon-based negative electrode active material, which is a silicon-based negative electrode active material with a coating layer, wherein the coating layer comprises a self-repairing elastomer material, and the self-repairing elastomer material comprises a repeating unit shown as a formula II:
Figure BDA0002640837890000031
in the formula II, R1And R3Is composed of
Figure BDA0002640837890000032
Wherein R is
Figure BDA0002640837890000033
Figure BDA0002640837890000034
Figure BDA0002640837890000035
Two types of the connecting lines are different from each other, and the wavy line represents the connecting line;
R’2and R'4The same or different, independently from each other, are selected from polypropylene oxide (PPG) segments, polyethylene glycol (PEG) segments, Polydimethylsiloxane (PDMS) segments, polytetramethylene ether glycol (PTMG) segments or Polybutadiene (PB) segments;
1>x>0。
according to the invention, R'2And R'4Are identical or different and are selected independently of one another
Figure BDA0002640837890000036
Figure BDA0002640837890000037
Figure BDA0002640837890000038
The wavy lines represent connecting lines, and n and m represent the number of repeating units.
According to the invention, the weight average molecular weight of the polypropylene oxide (PPG) chain segment, the polyethylene glycol (PEG) chain segment, the Polydimethylsiloxane (PDMS) chain segment, the polytetramethylene ether glycol (PTMG) chain segment or the Polybutadiene (PB) chain segment is 500-20000.
According to the invention, the number average molecular weight of the self-repairing elastomer material is 5000-.
According to the invention, the silicon-based negative active material is nano silicon or silicon oxide (SiO)y，0<y<2) Or a silicon carbon material.
According to the invention, the silicon-based negative electrode active material is a silicon-based negative electrode active material with a hydroxylated and aminated surface.
According to the invention, the coating layer is coated on the surface of the silicon-based negative electrode active material, and the thickness of the coating layer is 1nm-1000 nm.
According to the invention, the mass ratio of the silicon-based negative electrode active material to the coating layer is 0.01-20 wt%.
The invention also provides a negative plate, which comprises a negative active material, wherein the negative active material comprises the modified silicon-based negative active material.
According to the present invention, the anode active material further includes a carbon-based anode active material.
According to the present invention, the carbon-based negative active material is selected from at least one of natural graphite, artificial graphite, mesocarbon fiber, mesocarbon microbeads, and soft carbon.
According to the invention, the negative plate comprises a negative active material layer, the negative active material layer comprises the negative active material, a conductive agent and a binder, and the negative active material layer comprises the following components in percentage by mass:
70-99 wt% of negative electrode active material, 0.5-15 wt% of conductive agent and 0.5-15 wt% of binder.
The invention also provides a lithium ion battery which comprises the negative plate.
The invention has the beneficial effects that:
the invention provides a silicon-based negative electrode with self-repairing property, and a preparation method and application thereof. The self-repairing elastomer material is a polymer material (comprising polypropylene oxide, polyethylene glycol, polydimethylsiloxane, polytetramethylene ether glycol or polybutadiene and the like) containing dynamic interaction crosslinking of hydrogen bonds, disulfide bonds and the like, and the self-repairing elastomer material is coated on the surface of the silicon-based negative electrode to play a role of an SEI film, so that the toughness of the SEI film of the silicon-based negative electrode can be improved, the silicon-based negative electrode is adapted to and restrained from volume expansion, damage of the SEI film is repaired, side reactions of the surface of the silicon negative electrode and electrolyte are reduced, continuous thickening of the SEI film is restrained, and the function of improving the performance of the.
Specifically, the isocyanate group reacts with amine groups on the silicon-based negative active material, and the surface of the silicon-based negative active material is coated with the isocyanate group. The self-repairing performance is mainly that the polymer contains carbamido which can form hydrogen bonds, and the glass-transition temperature of the selected polymer material is lower, thereby being beneficial to realizing the repair.
Drawings
FIG. 1: an infrared spectrum of the self-repairing elastomer material PDMS prepared in preparation example 2.
FIG. 2: preparation example 2 the stress-strain curves of the original sample of the self-repairing elastomer material PDMS and the sample after repair at different times.
FIG. 3: optical microscope photographs of the self-repairing elastomer material PDMS prepared in preparation example 2 before and after repairing.
FIG. 4: nuclear magnetic spectrum of the self-repairing elastomer material PB prepared in preparation example 3.
FIG. 5: stress-strain curves of the original sample of the self-repairing elastomer material PB prepared in the preparation example 3 and the samples repaired at different times.
FIG. 6: optical micrographs of the self-repairing elastomer material PB prepared in preparation example 3 before and after repair.
FIG. 7: and (3) an infrared spectrum of the self-repairing elastomer material PPG prepared in the preparation example 4.
FIG. 8: preparation example 4 stress-strain curves of the original PPG sample and the repaired PPG sample of the self-repairing elastomeric material prepared.
FIG. 9: an infrared spectrum of the PEG self-repairing elastomer material prepared in the preparation example 5.
FIG. 10: preparation example 5 the stress-strain curves of the original sample and the repaired sample of the self-repairing elastomer material PEG prepared in the preparation example 5.
FIG. 11: the battery capacity retention rate-cycle curves of example 1, comparative example 1, and comparative example 2.
FIG. 12: SEM images of the cross-section of the negative electrode after 220 cycles of the batteries of example 1, comparative example 1 and comparative example 2.
FIG. 13: negative electrode cross-sectional SEM images and pole piece thickness after 220 cycles of the cells of example 1, comparative example 1, and comparative example 2.
FIG. 14: the battery capacity retention rate-cycle curves of example 2, comparative example 1, and comparative example 3.
FIG. 15: the battery capacity retention rate-cycle curves of example 3, comparative example 1, and comparative example 4.
FIG. 16: the battery capacity retention rate-cycle curves of example 4, comparative example 1, and comparative example 5.
FIG. 17: the preparation process of the aminated silicon-based negative electrode material is shown schematically.
Detailed Description
Self-repairing elastomer material and preparation method thereof
As described above, the present invention provides a self-healing elastomeric material comprising a repeating unit represented by formula I:
Figure BDA0002640837890000051
in the formula I, R1And R3Is composed of
Figure BDA0002640837890000052
Wherein R is
Figure BDA0002640837890000053
Figure BDA0002640837890000054
Figure BDA0002640837890000061
Two types of the connecting lines are different from each other, and the wavy line represents the connecting line;
R2and R4Identical or different, independently of one another, from a polypropylene oxide (PPG) segment, a polyethylene glycol (PEG) segment, a polytetramethylene ether glycol (PTMG) segment or a Polybutadiene (PB) segment;
1>x>0。
in one embodiment of the invention, R is2And R4Are identical or different and are selected independently of one another
Figure BDA0002640837890000062
Figure BDA0002640837890000063
The wavy lines represent connecting lines, and n and m represent the number of repeating units.
In one embodiment of the present invention, the weight average molecular weight of the polypropylene oxide (PPG) segment, the polyethylene glycol (PEG) segment, the polytetramethylene ether glycol (PTMG) segment or the Polybutadiene (PB) segment is 500 to 20000.
In one embodiment of the present invention, the self-healing elastomeric material comprises a repeating unit represented by formula III, formula IV, or formula V:
Figure BDA0002640837890000064
wherein n and x are as defined above.
In a specific example of the present invention, the self-healing elastomeric material has a strain of 20% to 600%; the stress of the self-repairing elastomer material is 0.1MPa-200 MPa.
In one specific example of the present invention, the number average molecular weight of the self-healing elastomeric material is 5000-.
In a specific example of the invention, the self-repairing elastomer material has a self-repairing performance, and the self-repairing performance refers to that when the material is damaged or broken, the damage can be repaired within 1min-2h at the temperature of between room temperature and 100 ℃ so as to achieve the mechanical property and the apparent state when the material is not damaged or broken.
The invention also provides a preparation method of the self-repairing elastomer material, which comprises the following steps:
mixing and reacting a diamine-terminated high polymer material and isocyanate in an organic solvent to prepare the self-repairing elastomer material;
wherein the diamine-terminated high polymer material is selected from diamine-terminated high polymer materials containing the following chain segments: one or two of a polypropylene oxide (PPG) segment, a polyethylene glycol (PEG) segment, a Polydimethylsiloxane (PDMS) segment, a polytetramethylene ether glycol (PTMG) segment or a Polybutadiene (PB) segment;
wherein the isocyanate is selected from two of 1, 3-phenylene diisocyanate, 4 '-methylene bis (phenyl isocyanate), isophorone diisocyanate, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, dicyclohexylmethane 4,4' -diisocyanate, 1, 4-cyclohexyl diisocyanate, trimethylhexamethylene diisocyanate or 1, 6-hexamethylene diisocyanate.
Wherein the organic solvent is dichloromethane.
Wherein the reaction temperature is 60-120 ℃, and the reaction time is 6-24 h.
Among them, the amine group in the diamine group may be, for example, 3-aminopropyl group.
Wherein the molar ratio of the diamine-terminated polymer material to the isocyanate is (0.8-1.2): 1.
< modified silicon-based negative active material and method for producing the same >
As described above, the present invention provides a modified silicon-based anode active material, which is a silicon-based anode active material having a coating layer, wherein the coating layer includes a self-repairing elastomer material, and the self-repairing elastomer material includes a repeating unit represented by formula II:
Figure BDA0002640837890000071
in the formula II, R1And R3Is composed of
Figure BDA0002640837890000072
Wherein R is
Figure BDA0002640837890000073
Figure BDA0002640837890000081
Figure BDA0002640837890000082
Two types of the connecting lines are different from each other, and the wavy line represents the connecting line;
R’2and R'4The same or different, independently from each other, are selected from polypropylene oxide (PPG) segments, polyethylene glycol (PEG) segments, Polydimethylsiloxane (PDMS) segments, polytetramethyleneEther glycol (PTMG) segments or Polybutadiene (PB) segments;
1>x>0。
in a specific example of the invention, the R'2And R'4Are identical or different and are selected independently of one another
Figure BDA0002640837890000083
Figure BDA0002640837890000084
The wavy lines represent connecting lines, and n and m represent the number of repeating units.
In one embodiment of the present invention, the weight average molecular weight of the polypropylene oxide (PPG) segment, the polyethylene glycol (PEG) segment, the Polydimethylsiloxane (PDMS) segment, the polytetramethylene ether glycol (PTMG) segment or the Polybutadiene (PB) segment is 500 to 20000.
In one specific example of the present invention, the number average molecular weight of the self-healing elastomeric material is 5000-.
In one embodiment of the present invention, the self-healing elastomeric material comprises a repeating unit represented by formula III, formula IV, formula V, or formula VI:
Figure BDA0002640837890000085
Figure BDA0002640837890000091
wherein n and x are as defined above.
In a specific example of the present invention, the self-healing elastomeric material has a strain of 20% to 600%; the stress of the self-repairing elastomer material is 0.1MPa-200 MPa.
In a specific example of the invention, the self-repairing elastomer material has a self-repairing performance, and the self-repairing performance refers to that when the material is damaged or broken, the damage can be repaired within 1min-2h at the temperature of between room temperature and 100 ℃ so as to achieve the mechanical property and the apparent state when the material is not damaged or broken.
In one embodiment of the present invention, the silicon-based negative active material is nano silicon, silicon oxide (SiO)y，0<y<2) Or a silicon carbon material.
In one embodiment of the present invention, the silicon-based negative electrode active material is a silicon-based negative electrode active material whose surface is hydroxylated and aminated.
In one specific example of the invention, the coating layer is coated on the surface of the silicon-based negative active material, and the thickness of the coating layer is 1nm-1000 nm.
In one embodiment of the present invention, the mass ratio of the silicon-based negative electrode active material to the clad layer is 0.01 to 20 wt%, for example, 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 15 wt%, 20 wt%.
The invention also provides a preparation method of the modified silicon-based negative electrode active material, which comprises the following steps:
mixing and reacting a silicon-based negative active material, a diamine-terminated high polymer material and isocyanate to prepare the modified silicon-based negative active material;
wherein the diamine-terminated high polymer material is selected from diamine-terminated high polymer materials containing the following chain segments: one or two of a polypropylene oxide (PPG) segment, a polyethylene glycol (PEG) segment, a Polydimethylsiloxane (PDMS) segment, a polytetramethylene ether glycol (PTMG) segment or a Polybutadiene (PB) segment;
wherein the isocyanate is selected from two of 1, 3-phenylene diisocyanate, 4 '-methylene bis (phenyl isocyanate), isophorone diisocyanate, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, dicyclohexylmethane 4,4' -diisocyanate, 1, 4-cyclohexyl diisocyanate, trimethylhexamethylene diisocyanate or 1, 6-hexamethylene diisocyanate.
Wherein the reaction temperature is 60-120 ℃, and the reaction time is 6-24 h.
Among them, the amine group in the diamine group may be, for example, 3-aminopropyl group.
Wherein the mass ratio of the silicon-based negative electrode active material to the self-repairing high polymer material is 0.01-20 wt%, such as 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 15 wt%, 20 wt%.
In one embodiment of the present invention, the silicon-based negative electrode active material is preferably a silicon-based negative electrode active material with a surface subjected to hydroxylation and amination, and the silicon-based negative electrode active material with a surface subjected to hydroxylation and amination is prepared by the following method:
(a) silicon-based negative electrode active material is added in H2O2Stirring in the ethanol mixed solution, carrying out oxidation treatment, and introducing hydroxyl on the surface; or directly carrying out oxygen plasma treatment on the silicon-based negative electrode active material, and introducing hydroxyl on the surface;
(b) dispersing the silicon material with hydroxyl introduced on the surface into ethanol, adding a silane coupling agent (such as 3-aminopropyl trimethoxy silane), stirring and centrifuging to obtain a silicon-based negative active material with the surface subjected to hydroxylation and amination;
(c) optionally, washing with ethanol for several times, and vacuum drying.
< negative plate and method for producing the same >
As mentioned above, the present invention also provides a negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode active material, and the negative electrode active material comprises the modified silicon-based negative electrode active material.
In a specific example of the present invention, the negative electrode active material further includes a carbon-based negative electrode active material selected from at least one of natural graphite, artificial graphite, mesophase carbon fiber, mesophase carbon microsphere, and soft carbon.
In a specific example of the present invention, the surface of the carbon-based negative active material may further be coated with the self-repairing elastomer material.
In one specific example of the present invention, the mass ratio of the silicon-based anode active material to the carbon-based anode active material is 1% to 99% to 1%, for example: 97% for 3%, 96% for 4%, 95% for 5%, 94% for 6%, 93% for 7%, 92% for 8%, 91% for 9%, 90% for 10%, 85% for 15%, 80% for 20%, 75% for 25%, 70% for 30%, 65% for 35%, 60% for 40%, 50% for 50% and 40% for 60%.
In a specific example of the present invention, the negative electrode sheet includes a negative electrode active material layer including the negative electrode active material described above, a conductive agent, and a binder.
In one specific example of the invention, the negative electrode active material layer comprises the following components in percentage by mass:
70-99 wt% of negative electrode active material, 0.5-15 wt% of conductive agent and 0.5-15 wt% of binder.
Preferably, the negative electrode active material layer comprises the following components in percentage by mass:
80-98 wt% of negative electrode active material, 1-10 wt% of conductive agent and 1-10 wt% of binder.
Wherein the conductive agent is at least one selected from conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotube, metal powder and carbon fiber.
Wherein the binder is selected from at least one of sodium carboxymethylcellulose, styrene-butadiene latex, polytetrafluoroethylene and polyethylene oxide.
The invention also provides a preparation method of the negative plate, which comprises the following steps:
1) respectively preparing slurry for forming the negative active material layers;
2) and coating the slurry for forming the negative active material layer on the surfaces of the two sides of the negative current collector by using a coating machine to prepare the negative plate.
In one embodiment of the present invention, in step 1), the solid content of the slurry for forming the anode active material layer is 40 wt% to 45 wt%.
< lithium ion Battery >
As mentioned above, the present invention further provides a lithium ion battery, which includes the above negative electrode sheet.
In one embodiment of the present invention, the lithium ion battery further includes a positive electrode sheet.
The positive active material in the positive plate comprises at least one of lithium iron phosphate, lithium vanadium phosphate, lithium cobaltate, ternary material or lithium manganate.
The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
Optionally indicating the presence or absence of the stated feature, and also indicating that the stated feature must be present, although the particular choice may be arbitrary.
Preparation example 1:
amino modified SiOyPreparation of the material:
mixing SiOy(20g) Dispersing in ethanol (200mL), stirring for 15min, adding hydrogen peroxide (30%, 200mL), stirring at 75 deg.C for 48h, filtering, and washing with ethanol to obtain surface-hydroxylated SiOyA material.
Hydroxylating SiOy(20g) Dispersing the particles in ethanol (100mL), adding 3-aminopropyltrimethoxysilane (30mL) into the dispersion, stirring at room temperature for 72h, and centrifuging to obtain aminated SiOyWashing with ethanol for 3 times, and vacuum drying to obtain aminated SiOy。
Preparation example 2:
preparation of self-repairing elastomer material PDMS:
weighing bis (3-aminopropyl) terminated poly (dimethylsiloxane) (0.42g, 0.14mmol, Mn:3000), 4' -methylenebis (phenyl isocyanate) (0.0175g, 0.07mmol) and isophorone diisocyanate (0.0178, 0.08mmol), adding into a round-bottom flask containing dichloromethane (10ml), stirring at normal temperature for 2h, stirring at 80 ℃ for 12h, adding the reacted solution into a tetrafluoroethylene mold, and drying the solvent to obtain the self-repairing elastomer material. The structure is characterized by an infrared spectrum as shown in figure 1. The mechanical and repair properties are characterized by stress-strain properties as shown in figure 2.
The structural formula of the prepared self-repairing elastomer material PDMS is as follows:
Figure BDA0002640837890000121
the specific repairing process comprises the following steps: the sample is made into a standard sample strip (the length is multiplied by the width is multiplied by the thickness is multiplied by 80mm multiplied by 10mm multiplied by 1mm), the standard sample strip is cut into two parts by a scalpel, the section is contacted for different time at normal temperature, the mechanical property of the repaired sample is measured, and the test shows that the mechanical property of the repaired sample at normal temperature can basically reach the initial sample mechanical property after being repaired for 30 min. The scratches on the sample can be seen to disappear basically after 30min through a microscope, as shown in fig. 3, which shows that the sample is well repaired, the self-repairing elastomer material PDMS has good mechanical properties, the elongation at break can reach 1500%, and the self-repairing elastomer material PDMS also has good repairing properties, and the characteristics can be used as an artificial SEI film material of a silicon cathode.
Preparation example 3:
preparation of self-repairing elastomer material Polybutadiene (PB):
weighing bis (3-aminopropyl) terminated polybutadiene (0.75g, 0.3mmol, Mn:2500), 4' -methylenebis (phenyl isocyanate) (0.037g, 0.15mmol) and isophorone diisocyanate (0.034, 0.16mmol), adding into a round-bottom flask containing dichloromethane (10ml), stirring at normal temperature for 2h, stirring at 80 ℃ for 12h, adding the reacted solution into a tetrafluoroethylene mold, and drying with a solvent to obtain the self-repairing material. The structure is characterized by a nuclear magnetic spectrum as shown in figure 4. Mechanical and repair properties are characterized by stress-strain properties, as shown in fig. 5.
The structural formula of the prepared self-repairing elastomer material PB is as follows:
Figure BDA0002640837890000131
the specific repairing process comprises the following steps: the sample is made into a standard sample strip (the length is multiplied by the width is multiplied by the thickness is multiplied by 80mm multiplied by 10mm multiplied by 1mm), the standard sample strip is cut into two parts by a scalpel, the section is contacted for different time at normal temperature, the mechanical property of the repaired sample is measured, the test shows that after the sample is repaired at the normal temperature for 40min, the stress can be recovered to 96 percent of the initial sample, and the strain can be recovered to 84 percent. The scratches on the sample can be seen to basically disappear after 40min through a microscope, as shown in fig. 6, which shows that the sample is well repaired, the self-repairing elastomer material PB has good mechanical properties, the elongation at break of the material can reach 400%, and the material also has good repairing properties, and the characteristics can be used as a silicon negative electrode artificial SEI film material.
Preparation example 4:
preparing the self-repairing elastomer material PPG:
weighing bis (3-aminopropyl) terminated polypropylene oxide (0.78g, 0.26mmol, Mn:3000), dicyclohexylmethane 4,4' -diisocyanate (0.033g, 0.133mmol) and isophorone diisocyanate (0.029, 0.133mmol) into a round-bottom flask containing dichloromethane (10ml), stirring for 6h at 60 ℃, adding the reacted solution into a tetrafluoroethylene mold, and drying the solvent to obtain the self-repairing material. The structure is characterized by an infrared spectrogram as shown in figure 7, and isocyanate bond-NCO basically disappears after 6 hours of reaction. Mechanical and repair properties were characterized by stress-strain properties, as shown in fig. 8.
The structural formula of the prepared self-repairing elastomer material PPG is as follows:
Figure BDA0002640837890000132
the specific repairing process comprises the following steps: the sample is made into a standard sample strip (the length is multiplied by the width is multiplied by the thickness is multiplied by 80mm multiplied by 10mm multiplied by 1mm), the standard sample strip is cut into two parts by a scalpel, the section is contacted for different time at normal temperature, the mechanical property of the repaired sample is measured, and the test shows that the mechanical property of the repaired sample at normal temperature can basically reach the initial sample mechanical property after 20min of normal temperature repair. The PPG has good mechanical properties, the elongation at break of the PPG can reach 120%, and the PPG also has good repairing performance, and the characteristics can be used as an artificial SEI film material of a silicon cathode.
Preparation example 5:
preparation of self-repairing elastomer material PEG:
weighing bis (3-aminopropyl) terminated polyethylene glycol (0.6g, 0.3mmol, Mn:2000), dicyclohexylmethane 4,4' -diisocyanate (0.025g, 0.10mmol) and isophorone diisocyanate (0.046, 0.21mmol), adding into a round-bottom flask containing dichloromethane (10ml), stirring at normal temperature for 2h, stirring at 80 ℃ for 12h, adding the reacted solution into a tetrafluoroethylene mold, and drying the solvent to obtain the self-repairing material. The structure is characterized by an infrared spectrum as shown in figure 9. Mechanical and repair properties were characterized by stress-strain properties, as shown in fig. 10.
The structural formula of the prepared self-repairing elastomer material PEG is as follows:
Figure BDA0002640837890000141
the specific repairing process comprises the following steps: the sample is made into a standard sample strip (the length is multiplied by the width is multiplied by the thickness is multiplied by 80mm multiplied by 10mm multiplied by 1mm), the sample is cut into two parts by a scalpel, the section is contacted for different time at normal temperature, the mechanical property of the repaired sample is measured, the test shows that the stress can be recovered to 28 percent of the initial sample and the strain can be recovered to 42 percent when the repaired sample is repaired for 1 hour at 45 ℃. The PEG self-repairing elastomer material has good mechanical properties, the elongation at break of the PEG self-repairing elastomer material can reach 82%, and the PEG self-repairing elastomer material also has good repairing properties, and the characteristics can be used as an artificial SEI film material of a silicon cathode.
Comparative example 1:
uncoated SiOyAs a negative electrode battery fabrication and performance test:
the method comprises the following specific steps: mixing SiOyWas blended with graphite 2:8 by mass ratio, and then the blended active material, conductive agent and binder PAA (molecular weight Mw:45w) were dispersed in water at a mass ratio of 9:0.5:0.5, formed into a uniform slurry by grinding and stirring, and coated on a copper foil.Then the pole piece is placed in a drying oven, dried for 36h at 80 ℃, cut into a circular pole piece with the diameter of 1cm, and stored in a glove box (the surface density is 1 mg/cm)2). And assembling 2032 button cells by using lithium sheets as counter electrodes. Wherein the electrolyte adopts 1M LiPF6The battery is an EC/DMC/DEC solution with a lithium salt volume ratio of 1:1:1, an FEC additive (10 vol%) is contained in an electrolyte, the assembled battery is kept stand for 12 hours, constant-current charging and discharging are carried out on the battery which is kept stand on a blue-ray test system at 25 ℃, the first-circle charging adopts small-current formation, and the current is 25.0mA/g (about 0.05C) and 0.01-1.5V. At the beginning of the sub-period, the charging and discharging current is 250mA/g (about 0.5C), the voltage range is 0.01-1.5V, and the discharging capacity of the battery is 495 mAh/g. After 220 cycles, the capacity was 424mAh/g, and the capacity retention was 85.7% (FIG. 11). SEM pictures of the cathode cut after cycle 220 cycles were taken and the silicon surface was found to produce a thick SEI film, about 0.35 μm (fig. 12). The cathode pole piece is thickened seriously, the initial thickness is 48.4 mu m, and the pole piece thickness is 102.9 mu m after the cycle of 220 cycles (figure 13).
Comparative example 2:
ordinary PDMS coated SiOy：
Aminated SiO prepared in preparation example 1y(10g) Dispersed in 50mL of methylene chloride, bishydroxy-terminated poly (dimethylsiloxane) (0.42g, 0.14mmol, Mn:3000), 4,4' -methylenebis (phenyl isocyanate) (0.0175g, 0.07mmol), isophorone diisocyanate (0.0178, 0.08mmol), and 2 drops of dibutyltin dilaurate as a catalyst were added, reacted at 65 ℃ for 12 hours under nitrogen protection, reacted at 85 ℃ for 24 hours, the solvent was distilled off under reduced pressure, and washed with methylene chloride to remove the uncoated starting material. Coating the SiOyAnd drying the materials for later use.
The general PDMS prepared has the following structural formula:
Figure BDA0002640837890000151
battery preparation and performance testing:
the method comprises the following specific steps: SiO coated with PDMSyGraphite 28 mass ratio, then the blended active material, conductive agent and binder PAA (molecular weight Mw:45w) were dispersed in water at a mass ratio of 9:0.5:0.5, formed into a uniform slurry by grinding and stirring, and coated on a copper foil. Then the pole piece is placed in a drying oven, dried for 36h at 80 ℃, cut into a circular pole piece with the diameter of 1cm, and stored in a glove box (the surface density is 1 mg/cm)2). And assembling 2032 button cells by using lithium sheets as counter electrodes. Wherein the electrolyte adopts 1M LiPF6The lithium salt is EC/DMC/DEC solution with the volume ratio of 1:1:1, the electrolyte contains FEC additive (10 vol%), the assembled battery is kept still for 12h, and the battery kept still is charged and discharged at a constant current at 25 ℃ on a blue test system. The first charging loop adopts small current formation, the current is 25.0mA/g (about 0.05C), and the voltage is 0.01-1.5V. At the beginning of the sub-period, the charging and discharging current is 250mA/g (about 0.5C), the voltage range is 0.01-1.5V, and the discharging capacity of the battery is 495 mAh/g. After 220 cycles, the capacity was 430mAh/g, and the capacity retention was 86.8% (FIG. 11). And taking an SEM image of a section of the negative electrode after the cycle 220, and finding that a thicker SEI film is generated on the silicon surface, the thickness of the negative electrode plate is about 0.29 mu m, the thickening of the negative electrode plate is serious, the initial thickness of the negative electrode plate is 49.8 mu m, and the thickness of the negative electrode plate after the cycle 220 is 99.6 mu m.
Comparative example 3:
SiO coated with ordinary Polybutadiene (PB)y：
Aminated SiO prepared in preparation example 1y(10g) Dispersed in 50mL of methylene chloride, bishydroxy-terminated polybutadiene (0.75g, 0.3mmol, Mn:2500), 4' -methylenebis (phenyl isocyanate) (0.037g, 0.15mmol), isophorone diisocyanate (0.034, 0.16mmol), and 2 drops of dibutyltin dilaurate as a catalyst were added, and the mixture was reacted at 65 ℃ for 12 hours and 85 ℃ for 24 hours under nitrogen protection, and the solvent was distilled off under reduced pressure and washed with methylene chloride to remove the uncoated starting material. Coating the SiOyAnd drying the materials for later use.
The general PB prepared has the following structural formula:
Figure BDA0002640837890000152
battery preparation and performance testing:
the method comprises the following specific steps: SiO coated with PByWas blended with graphite 2:8 by mass ratio, and then the blended active material, conductive agent and binder PAA (molecular weight Mw:45w) were dispersed in water at a mass ratio of 9:0.5:0.5, formed into a uniform slurry by grinding and stirring, and coated on a copper foil. Then the pole piece is placed in a drying oven, dried for 36h at 80 ℃, cut into a circular pole piece with the diameter of 1cm, and stored in a glove box (the surface density is 1 mg/cm)2). And assembling 2032 button cells by using lithium sheets as counter electrodes. Wherein the electrolyte adopts 1M LiPF6The lithium salt is EC/DMC/DEC solution with the volume ratio of 1:1:1, the electrolyte contains FEC additive (10 vol%), the assembled battery is kept still for 12h, and the battery kept still is charged and discharged at a constant current at 25 ℃ on a blue test system. The first charging loop adopts small current formation, the current is 25.0mA/g (about 0.05C), and the voltage is 0.01-1.5V. At the beginning of the secondary period, the charging and discharging current is 250mA/g (about 0.5C), the voltage range is 0.01-1.5V, and the discharging capacity of the battery is 496 mAh/g. After 220 cycles of circulation, the capacity was 429mAh/g, with a capacity retention of 86.5% (FIG. 14). And (3) taking an SEM image of a section of the negative electrode after the cycle 220, and finding that a thicker SEI film is generated on the silicon surface, the thickness of the negative electrode pole piece is about 0.28 mu m, the thickening of the negative electrode pole piece is serious, the initial thickness is 47.8 mu m, and the thickness of the pole piece after the cycle 220 is 97.4 mu m.
Comparative example 4:
ordinary polypropylene oxide (PPG) coated SiOy：
Aminated SiO prepared in preparation example 1y(10g) Dispersing into 50mL of dichloromethane, adding dihydroxy-terminated polypropylene oxide (0.78g, 0.26mmol, Mn:3000), dicyclohexylmethane-4, 4' -diisocyanate (0.033g, 0.133mmol) and isophorone diisocyanate (0.029, 0.133mmol) respectively and 2 drops of catalyst dibutyltin dilaurate, reacting at 65 ℃ for 12h under the protection of nitrogen, reacting at 85 ℃ for 24h, distilling off the solvent under reduced pressure, washing with dichloromethane, and removing the uncoated raw material. Coating the SiOyAnd drying the materials for later use.
The general PPG prepared has the following structural formula:
Figure BDA0002640837890000161
battery preparation and performance testing:
the method comprises the following specific steps: SiO coated with PPGyWas blended with graphite 2:8 by mass ratio, and then the blended active material, conductive agent and binder PAA (molecular weight Mw:45w) were dispersed in water at a mass ratio of 9:0.5:0.5, formed into a uniform slurry by grinding and stirring, and coated on a copper foil. Then the pole piece is placed in a drying oven, dried for 36h at 80 ℃, cut into a circular pole piece with the diameter of 1cm, and stored in a glove box (the surface density is 1 mg/cm)2). And assembling 2032 button cells by using lithium sheets as counter electrodes. Wherein the electrolyte adopts 1M LiPF6The lithium salt is EC/DMC/DEC solution with the volume ratio of 1:1:1, the electrolyte contains FEC additive (10 vol%), the assembled battery is kept still for 12h, and the battery kept still is charged and discharged at a constant current at 25 ℃ on a blue test system. The first charging loop adopts small current formation, the current is 25.0mA/g (about 0.05C), and the voltage is 0.01-1.5V. At the beginning of the sub-period, the charging and discharging current is 250mA/g (about 0.5C), the voltage range is 0.01-1.5V, and the discharging capacity of the battery is 495 mAh/g. After 220 cycles, the capacity was 424mAh/g, and the capacity retention was 85.6% (FIG. 15). And taking an SEM image of a section of the negative electrode after the cycle 220, and finding that a thicker SEI film is generated on the silicon surface, the thickness of the negative electrode pole piece is about 0.27 mu m, the thickening of the negative electrode pole piece is serious, the initial thickness is 47.9 mu m, and the thickness of the pole piece after the cycle 220 is 98.6 mu m.
Comparative example 5:
ordinary polyethylene glycol (PEG) coated SiOy：
Aminated SiO prepared in preparation example 1y(10g) Dispersing into 50mL of NMP solvent, adding dihydroxy-terminated polyethylene glycol (0.6g, 0.3mmol, Mn:2000), dicyclohexylmethane-4, 4' -diisocyanate (0.025g, 0.10mmol), isophorone diisocyanate (0.046, 0.21mmol) and 2 drops of dibutyltin dilaurate serving as a catalyst respectively, reacting at 65 ℃ for 12h under the protection of nitrogen, reacting at 85 ℃ for 24h,the solvent was distilled off under reduced pressure and washed with dichloromethane to remove uncoated starting material. Coating the SiOyAnd drying the materials for later use.
The general PEG prepared has the following structural formula:
Figure BDA0002640837890000171
battery preparation and performance testing:
the method comprises the following specific steps: SiO coated with PEGyWas blended with graphite 2:8 by mass ratio, and then the blended active material, conductive agent and binder PAA (molecular weight Mw:45w) were dispersed in water at a mass ratio of 9:0.5:0.5, formed into a uniform slurry by grinding and stirring, and coated on a copper foil. Then the pole piece is placed in a drying oven, dried for 36h at 80 ℃, cut into a circular pole piece with the diameter of 1cm, and stored in a glove box (the surface density is 1 mg/cm)2). And assembling 2032 button cells by using lithium sheets as counter electrodes. Wherein the electrolyte adopts 1M LiPF6The lithium salt is EC/DMC/DEC solution with the volume ratio of 1:1:1, the electrolyte contains FEC additive (10 vol%), the assembled battery is kept still for 12h, and the battery kept still is charged and discharged at a constant current at 25 ℃ on a blue test system. The first charging loop adopts small current formation, the current is 25.0mA/g (about 0.05C), and the voltage is 0.01-1.5V. At the beginning of the sub-cycle, the charging and discharging current was 250mA/g (about 0.5C), the voltage range was 0.01-1.5V, and the discharge capacity of the battery was 489 mAh/g. After 220 cycles, the capacity was 421mAh/g, and the capacity retention was 86.1% (FIG. 16). And taking an SEM image of a section of the negative electrode after the cycle 220, and finding that a thicker SEI film is generated on the silicon surface, the thickness of the negative electrode pole piece is about 0.29 mu m, the thickening of the negative electrode pole piece is serious, the initial thickness is 48.8 mu m, and the thickness of the pole piece after the cycle 220 is 98.9 mu m.
Example 1:
self-repairing elastomer material PDMS coated SiOy：
Aminated SiO prepared in preparation example 1y(10g) Dispersed in 50mL of methylene chloride, and bis (3-aminopropyl) -terminated poly (dimethylsiloxane) (0.42g, 0.14mmol, Mn: 300) was added0) 4,4' -methylenebis (phenyl isocyanate) (0.0175g, 0.07mmol) and isophorone diisocyanate (0.0178, 0.08mmol) were reacted at room temperature for 12 hours, at 85 ℃ for 24 hours, the solvent was distilled off under reduced pressure, and the uncoated starting material was removed by washing with dichloromethane. Coating the SiOyAnd drying the materials for later use.
Battery preparation and performance testing:
the method comprises the following specific steps: SiO coated with PDMSyWas blended with graphite 2:8 by mass ratio, and then the blended active material, conductive agent and binder PAA (molecular weight Mw:45w) were dispersed in water at a mass ratio of 9:0.5:0.5, formed into a uniform slurry by grinding and stirring, and coated on a copper foil. Then the pole piece is placed in a drying oven, dried for 36h at 80 ℃, cut into a circular pole piece with the diameter of 1cm, and stored in a glove box (the surface density is 1 mg/cm)2). And assembling 2032 button cells by using lithium sheets as counter electrodes. Wherein the electrolyte adopts 1M LiPF6The lithium salt is EC/DMC/DEC solution with the volume ratio of 1:1:1, the electrolyte contains FEC additive (10 vol%), the assembled battery is kept still for 12h, and the battery kept still is charged and discharged at a constant current at 25 ℃ on a blue test system. The first charging loop adopts small current formation, the current is 25.0mA/g (about 0.05C), and the voltage is 0.01-1.5V. At the beginning of the secondary period, the charging and discharging current is 250mA/g (about 0.5C), the voltage range is 0.01-1.5V, and the discharging capacity of the battery is 496 mAh/g. After 220 cycles of circulation, the capacity was 457mAh/g, and the capacity retention was 92.1% (FIG. 11). SEM images of the negative electrode cut after cycle 220 cycles revealed that the silicon surface produced a thin SEI film, about 0.2 μm (fig. 12). The negative pole piece is less thickened, the initial thickness is 44.8 μm, and the pole piece thickness is 79.4 μm after the cycle 220 period (fig. 13).
Example 2:
self-repairing elastomer material PB coated SiOy：
Aminated SiO prepared in preparation example 1y(10g) Dispersed in 50mL of methylene chloride, bisaminopropyl-terminated polybutadiene (0.75g, 0.3mmol, Mn:2500), 4' -methylenebis (phenyl isocyanate) (0.037g, 0.15mmol) and isophorone diisocyanate (0.034, 0.16mmol) were added, respectivelyThe reaction was carried out at a temperature of 85 ℃ for 24 hours, the solvent was distilled off under reduced pressure and washed with dichloromethane to remove uncoated starting materials. Coating the SiOyAnd drying the materials for later use.
Battery preparation and performance testing:
the method comprises the following specific steps: SiO coated with PByWas blended with graphite 2:8 by mass ratio, and then the blended active material, conductive agent and binder PAA (molecular weight Mw:45w) were dispersed in water at a mass ratio of 9:0.5:0.5, formed into a uniform slurry by grinding and stirring, and coated on a copper foil. Then the pole piece is placed in a drying oven, dried for 36h at 80 ℃, cut into a circular pole piece with the diameter of 1cm, and stored in a glove box (the surface density is 1 mg/cm)2). And assembling 2032 button cells by using lithium sheets as counter electrodes. Wherein the electrolyte adopts 1M LiPF6The battery is an EC/DMC/DEC solution with a lithium salt volume ratio of 1:1:1, an FEC additive (10 vol%) is contained in an electrolyte, the assembled battery is kept stand for 12 hours, constant-current charging and discharging are carried out on the battery which is kept stand on a blue-ray test system at 25 ℃, the first-circle charging adopts small-current formation, and the current is 25.0mA/g (about 0.05C) and 0.01-1.5V. At the beginning of the sub-cycle, the charging and discharging current is 250mA/g (about 0.5C), the voltage range is 0.01-1.5V, and the discharging capacity of the battery is 497 mAh/g. After 220 cycles, the capacity was 463mAh/g, with a capacity retention of 93.2% (FIG. 14). SEM pictures of the negative electrode cut after cycle 220 cycles were taken and the silicon surface was found to produce a thin SEI film, about 0.22 μm. The negative pole piece is less thickened, the initial thickness is 45.8 mu m, and the pole piece thickness is 83.4 mu m after the cycle of 220 cycles.
Example 3:
self-repairing elastomer material polypropylene oxide (PPG) coated SiOy：
Aminated SiO prepared in preparation example 1y(10g) Dispersing into 50mL of dichloromethane, adding bis (3-aminopropyl) terminated polypropylene oxide (0.78g, 0.26mmol, Mn:3000), dicyclohexylmethane 4,4' -diisocyanate (0.033g, 0.133mmol) and isophorone diisocyanate (0.029, 0.133mmol), reacting at room temperature for 12h, reacting at 85 ℃ for 24h, distilling off the solvent under reduced pressure, washing with dichloromethane, and removing the non-coatingCoating raw materials. Coating the SiOyAnd drying the materials for later use.
Battery preparation and performance testing:
the method comprises the following specific steps: SiO coated with PPGyWas blended with graphite 2:8 by mass ratio, and then the blended active material, conductive agent and binder PAA (molecular weight Mw:45w) were dispersed in water at a mass ratio of 9:0.5:0.5, formed into a uniform slurry by grinding and stirring, and coated on a copper foil. Then the pole piece is placed in a drying oven, dried for 36h at 80 ℃, cut into a circular pole piece with the diameter of 1cm, and stored in a glove box (the surface density is 1 mg/cm)2). And assembling 2032 button cells by using lithium sheets as counter electrodes. Wherein the electrolyte adopts 1M LiPF6The lithium salt is EC/DMC/DEC solution with the volume ratio of 1:1:1, the electrolyte contains FEC additive (10 vol%), the assembled battery is kept still for 12h, and the battery kept still is charged and discharged at a constant current at 25 ℃ on a blue test system. The first charging loop adopts small current formation, the current is 25.0mA/g (about 0.05C), and the voltage is 0.01-1.5V. At the beginning of the secondary period, the charging and discharging current is 250mA/g (about 0.5C), the voltage range is 0.01-1.5V, and the discharging capacity of the battery is 496 mAh/g. After 220 cycles of circulation, the capacity was 467mAh/g, and the capacity retention was 93.2% (FIG. 15). SEM pictures of the negative electrode cut after cycle 220 cycles revealed that the silicon surface produced a thin SEI film, about 0.19 μm. The negative pole piece is less thickened, the initial thickness is 46.5 mu m, and the pole piece thickness is 86.4 mu m after the cycle of 220 cycles.
Example 4:
self-repairing elastomer material polyethylene glycol (PEG) coated SiOy：
Aminated SiO prepared in preparation example 1y(10g) Dispersing into 50mL of dichloromethane, adding bis (3-aminopropyl) terminated polyethylene glycol (0.6g, 0.3mmol, Mn:2000), dicyclohexylmethane 4,4' -diisocyanate (0.025g, 0.10mmol) and isophorone diisocyanate (0.046, 0.21mmol), reacting at room temperature for 12h, reacting at 85 ℃ for 24h, distilling off the solvent under reduced pressure, washing with dichloromethane, and removing the uncoated raw material. Coating the SiOyAnd drying the materials for later use.
Battery preparation and performance testing:
the method comprises the following specific steps: SiO coated with PEGyWas blended with graphite 2:8 by mass ratio, and then the blended active material, conductive agent and binder PAA (molecular weight Mw:45w) were dispersed in water at a mass ratio of 9:0.5:0.5, formed into a uniform slurry by grinding and stirring, and coated on a copper foil. Then the pole piece is placed in a drying oven, dried for 36h at 80 ℃, cut into a circular pole piece with the diameter of 1cm, and stored in a glove box (the surface density is 1 mg/cm)2). And assembling 2032 button cells by using lithium sheets as counter electrodes. Wherein the electrolyte adopts 1M LiPF6The lithium salt is EC/DMC/DEC solution with the volume ratio of 1:1:1, the electrolyte contains FEC additive (10 vol%), the assembled battery is kept still for 12h, and the battery kept still is charged and discharged at a constant current at 25 ℃ on a blue test system. The first charging loop adopts small current formation, the current is 25.0mA/g (about 0.05C), and the voltage is 0.01-1.5V. At the beginning of the sub-cycle, the charge and discharge current is 250mA/g (about 0.5C), the voltage range is 0.01-1.5V, and the discharge capacity of the battery is 488 mAh/g. After 220 cycles, the capacity was 451mAh/g, and the capacity retention was 92.5% (FIG. 15). SEM pictures of the negative electrode cut after cycle 220 cycles were taken and the silicon surface was found to produce a thin SEI film, about 0.24 μm. The negative pole piece is less thickened, the initial thickness is 46.5 mu m, and the pole piece thickness is 96.4 mu m after the cycle of 220 cycles.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A self-healing elastomeric material, wherein the self-healing elastomeric material comprises repeating units represented by formula I:
Figure FDA0002640837880000011
in the formula I, R1And R3Is composed of
Figure FDA0002640837880000012
Wherein R is
Figure FDA0002640837880000013
Figure FDA0002640837880000014
Figure FDA0002640837880000015
Two types of the connecting lines are different from each other, and the wavy line represents the connecting line;
R2and R4Identical or different, independently of one another, from a polypropylene oxide (PPG) segment, a polyethylene glycol (PEG) segment, a polytetramethylene ether glycol (PTMG) segment or a Polybutadiene (PB) segment;
1>x>0。
2. the self-healing elastomeric material of claim 1, wherein R is2And R4Are identical or different and are selected independently of one another
Figure FDA0002640837880000016
Figure FDA0002640837880000017
The wavy lines represent connecting lines, and n and m represent the number of repeating units.
3. The self-healing elastomeric material of claim 1 or 2, wherein the weight average molecular weight of the polypropylene oxide (PPG) segment, the polyethylene glycol (PEG) segment, the polytetramethylene ether glycol (PTMG) segment, or the Polybutadiene (PB) segment is 500 to 20000; and/or the presence of a gas in the gas,
the number average molecular weight of the self-repairing elastomer material is 5000-; and/or the presence of a gas in the gas,
the Tg of the self-healing elastomeric material is less than 100 ℃.
4. A modified silicon-based anode active material, which is a silicon-based anode active material having a coating layer, wherein the coating layer comprises a self-repairing elastomeric material, and the self-repairing elastomeric material comprises a repeating unit represented by formula II:
Figure FDA0002640837880000021
in the formula II, R1And R3Is composed of
Figure FDA0002640837880000022
Wherein R is
Figure FDA0002640837880000023
Figure FDA0002640837880000024
Figure FDA0002640837880000025
Two types of the connecting lines are different from each other, and the wavy line represents the connecting line;
R’2and R'4The same or different, independently from each other, are selected from polypropylene oxide (PPG) segments, polyethylene glycol (PEG) segments, Polydimethylsiloxane (PDMS) segments, polytetramethylene ether glycol (PTMG) segments or Polybutadiene (PB) segments;
1>x>0。
5. the modified silicon-based negative electrode active material of claim 4, wherein R'2And R'4Are identical or different and are selected independently of one another
Figure FDA0002640837880000026
Figure FDA0002640837880000027
The wavy lines represent connecting lines, and n and m represent the number of repeating units.
6. The modified silicon-based negative active material of claim 4 or 5, wherein the weight average molecular weight of the polypropylene oxide (PPG) segment, the polyethylene glycol (PEG) segment, the Polydimethylsiloxane (PDMS) segment, the polytetramethylene ether glycol (PTMG) segment or the Polybutadiene (PB) segment is 500 to 20000; and/or the presence of a gas in the gas,
the number average molecular weight of the self-repairing elastomer material is 5000-; and/or the presence of a gas in the gas,
the Tg of the self-healing elastomeric material is less than 100 ℃.
7. The modified silicon-based anode active material according to any one of claims 4 to 6, wherein the silicon-based anode active material is a silicon-based anode active material with a hydroxylated and aminated surface; and/or the presence of a gas in the gas,
the coating layer is coated on the surface of the silicon-based negative electrode active material, and the thickness of the coating layer is 1nm-1000 nm; and/or the presence of a gas in the gas,
the mass ratio of the silicon-based negative electrode active material to the coating layer is 0.01-20 wt%.
8. A negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode active material, and the negative electrode active material comprises the modified silicon-based negative electrode active material according to any one of claims 4 to 7.
9. The negative electrode sheet of claim 8, wherein the negative electrode active material further comprises a carbon-based negative electrode active material; and/or the presence of a gas in the gas,
the negative plate comprises a negative active material layer, the negative active material layer comprises a negative active material, a conductive agent and a binder, and the negative active material layer comprises the following components in percentage by mass: 70-99 wt% of negative electrode active material, 0.5-15 wt% of conductive agent and 0.5-15 wt% of binder; the negative electrode active material comprises the modified silicon-based negative electrode active material of any one of claims 4 to 7; and/or the presence of a gas in the gas,
the negative plate comprises a negative active material layer, the negative active material layer comprises a negative active material, a conductive agent and a binder, and the negative active material layer comprises the following components in percentage by mass: 70-99 wt% of negative electrode active material, 0.5-15 wt% of conductive agent and 0.5-15 wt% of binder; the negative electrode active material comprises the modified silicon-based negative electrode active material and the carbon-based negative electrode active material of any one of claims 4 to 7; and/or the presence of a gas in the gas,
the carbon-based negative active material is selected from at least one of natural graphite, artificial graphite, mesocarbon fiber, mesocarbon microbeads and soft carbon.
10. A lithium ion battery comprising the negative electrode sheet of claim 8 or 9.
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