CN114975930B

CN114975930B - Silicon-oxygen negative electrode material, preparation method thereof, secondary battery and power utilization device

Info

Publication number: CN114975930B
Application number: CN202210600305.0A
Authority: CN
Inventors: 陈鹏; 褚春波; 张耀
Original assignee: Sunwoda Electric Vehicle Battery Co Ltd
Current assignee: Xinwangda Power Technology Co ltd
Priority date: 2022-05-30
Filing date: 2022-05-30
Publication date: 2023-08-15
Anticipated expiration: 2042-05-30
Also published as: CN114975930A

Abstract

The application discloses a silicon-oxygen anode material, a preparation method thereof, a secondary battery and an electric device. The silica cathode material comprises an inner core and an outer shell coated on the surface of the inner core, wherein the inner core comprises a silica-based material, the outer shell is a flexible coating layer containing M, and M is a metal element. The flexible coating layer can alleviate the damage degree of the silicon-oxygen negative electrode to the interface SEI film due to the huge volume effect of lithium intercalation and lithium deintercalation in the charge and discharge process, and reduce the generation of fresh interfaces, thereby reducing the consumption of reversible lithium and improving the cycle performance of the battery.

Description

Silicon-oxygen negative electrode material, preparation method thereof, secondary battery and power utilization device

Technical Field

The application belongs to the technical field of batteries, and particularly relates to a silicon-oxygen anode material, a preparation method thereof, a secondary battery and an electric device.

Background

With the popularization of electric vehicles, general mileage and charging anxiety of the public on the electric vehicles are increasing, and the requirements of high energy density and quick charging are urgent. Conventional graphite cathodes have difficulty meeting current power cell energy density requirements. Silicon oxygen cathode SiO compared with graphite _x (0<x<2) Because of the high gram capacity, the dosage of the cathode and the coating surface density can be reduced, and the energy density and the quick charge can be improved, so that great attention is paid. But SiO in the related art _x The problems of large expansion, poor circulation and the like exist to prevent the commercial popularization and application of the novel high-pressure water heater.

Disclosure of Invention

The present application aims to solve at least one of the technical problems in the prior art described above. Therefore, the application provides the silicon-oxygen anode material with good cycle performance.

The application also provides a preparation method of the silicon-oxygen anode material.

The application also provides a secondary battery.

The application also provides an electric device.

According to a first aspect of the application, a silicon-oxygen anode material is provided, the silicon-oxygen anode material comprises an inner core and an outer shell coated on the surface of the inner core, the inner core comprises a silicon-oxygen base material, the outer shell is a flexible coating layer containing M, and M is a metal element.

The silicon-oxygen anode material provided by the embodiment of the application has at least the following beneficial effects: compared with inorganic matters, the flexible coating layer has flexibility, can limit huge volume change of the silicon-oxygen negative electrode caused by lithium intercalation and lithium deintercalation in the charge and discharge process, reduce damage to an interface SEI film, alleviate the SEI film cracking degree and reduce fresh interface generation, thereby reducing reversible lithium consumption and improving the cycle performance of the battery. In addition, compared with the conventional organic matters, the flexible coating layer containing the metal element M has high conductivity, so that the conductivity of the flexible coating layer can be improved, and the quick charge performance of the silicon-oxygen negative electrode is improved. The flexible coating layer containing the metal element M has the flexibility of common organic matters and the high conductivity of metals, and the quick charge performance and the cycle life of the silicon-oxygen negative electrode can be improved under the synergistic effect of the metals and the organic matters in the flexible coating layer.

The SEI film refers to a solid electrolyte interface film formed on the surface of a negative electrode material in the cycling process of the lithium battery.

In some embodiments of the application, the flexible coating is a self-healing flexible coating.

The self-repairing and restoring of the flexible coating layer mainly comes from the action of secondary bonds (such as hydrogen bonds) between molecules and in molecules, the secondary bonds are automatically generated after the flexible coating layer is stressed and expanded and then disconnected, and external force is removed.

In some embodiments of the application, the flexible coating comprises a self-healing flexible polymeric compound.

The self-repairing flexible high molecular compound contains a group (such as-OH) capable of generating a secondary bond, the group contains an atom with strong electronegativity, such as an oxygen atom, and the group can generate a secondary bond, such as a hydrogen bond, between molecules or in molecules of the self-repairing flexible high molecular compound.

According to the above embodiment of the present application, at least the following advantageous effects are provided:

the flexible coating layer containing the self-repairing flexible high molecular compound has the advantages that the flexibility can improve the interface stability and reduce the reforming repair degree of the SEI film, so that the irreversible lithium consumption is reduced. In addition, the flexible coating layer contains oxygen and hydrogen elements, hydrogen bonds (including intramolecular hydrogen bonds) can be formed, a large number of hydrogen bonds can be formed, the high polymer fatigue caused by expansion of the flexible coating layer during lithium intercalation and volume shrinkage during lithium deintercalation of the silicon-oxygen negative electrode can be reduced, the long-term stability of a coating interface is improved, and the protection effect of the whole life cycle of the silicon-oxygen negative electrode material is ensured. In addition, the metal element M in the flexible coating layer can also react with lithium to generate an alloy to promote the intercalation and deintercalation of lithium in the flexible coating layer, so that the electric conductivity of the flexible coating layer is improved, and the quick charge performance of the silicon-oxygen negative electrode material is improved. The flexible coating layer improves the interface and the lithium ion diffusion capacity, improves the cycle life of the silicon-oxygen anode material, and can ease the silicon particle spacing and reduce the volume expansion of the silicon-oxygen anode material in the cycle process.

The self-repairing restoration of the flexible coating layer mainly comes from hydrogen bonds among molecules and inside molecules of the self-repairing flexible high polymer compound, the self-repairing flexible high polymer compound is disconnected after being stressed and expanded, and the self-repairing restoration is automatically generated due to strong electronegativity of oxygen after external force is removed.

In some embodiments of the application, the flexible coating comprises a self-healing flexible polymeric compound comprising MO _a R _b And the unit structure is characterized in that R is a hydrocarbon group, O is oxygen, two ends of the unit structure are O and R respectively, M is connected with R through O, a is more than or equal to 2, and b is more than or equal to 1.

In some embodiments of the application, the MO _a R _b The unit structure comprises ZnO ₂ C ₂ H ₄ 、ZnO ₂ C ₃ H ₆ 、ZnO ₂ C ₂₀ H ₄₀ 、CuO ₂ C ₂ H ₄ 、GeO ₂ C ₂ H ₄ Or SnO ₂ C ₃ H ₆ One of them.

In some embodiments of the application, the flexible coating comprises a metal alkyl and an alcohol as raw materials.

According to the above embodiment of the present application, at least the following advantageous effects are provided: the alkyl metal reacts with alcohol to obtain a flexible high polymer material (comprising self-repairing flexible high polymer compound), and the flexible high polymer material has the characteristic of self-repairing due to the action of hydrogen bonds (comprising intermolecular and intramolecular hydrogen bonds), can improve the interface stability and fatigue resistance of a flexible coating layer in the long-term circulation process, and ensures the protection effect of the whole life cycle of the silicon-oxygen anode material. The flexible polymer material contains metal elements from alkyl metal, so that the conductivity of the silicon-oxygen anode material is improved.

In some embodiments of the application, the alkyl group in the metal alkyl comprises at least one of methyl, ethyl, propyl, butyl, and pentyl.

In some embodiments of the application, the metal alkyl contains a plurality of the alkyl groups.

In some embodiments of the application, the alcohol comprises a lower alcohol.

In some embodiments of the application, the lower alcohol comprises at least one of a monohydric alcohol and a polyhydric alcohol.

In some embodiments of the application, the alcohol comprises at least one of methanol, ethanol, propanol, butanol, ethylene glycol, and propylene glycol.

In some embodiments of the application, the M comprises at least one of Zn, al, cu, ge and Sn.

In some embodiments of the application, the ratio of the mass fraction of M to the shell is (17-62): 100.

According to the above embodiment of the present application, at least the following advantageous effects are provided: the higher the content of the same metal element M in the shell, the better the quick charge performance of the silicon-oxygen anode material. The content of the metal element M is positively correlated with the thickness of the shell and the mass of the shell.

In some embodiments of the application, the ratio of the flexible coating to the mass fraction of the core is (0.1-10): 100.

According to the above embodiment of the present application, at least the following advantageous effects are provided: the proper ratio of the flexible coating layer to the core mass can lead the silicon-oxygen anode material to show better performance, and compared with the better ratio of the flexible coating layer to the core mass, if the content of the flexible coating layer is too high, the coating layer has high coating quantity, and the coating layer does not provide capacity, so the gram capacity of the silicon-oxygen anode material can be reduced.

In some embodiments of the application, the flexible coating has a thickness of 0.1-200nm.

According to the above embodiment of the present application, at least the following advantageous effects are provided: the thickness of the flexible coating layer is suitable to enable the silicon-oxygen anode material to show better performance, and compared with the better coating layer thickness, if the coating layer is too thick, the coating quantity is high, and the gram capacity of the silicon-oxygen anode material can be reduced because the coating layer does not provide capacity.

In some embodiments of the application, the flexible coating has a thickness of 1-50nm.

In some embodiments of the application, the particle size D of the inner core ₅₀ Is 3-15 μm.

Particle diameter D ₅₀ May be measured based on a laser particle size distribution, such as with a laser particle size distribution meter.

In some embodiments of the application, the feedstock of silicone-based material comprises waste silicone material.

According to the above embodiment of the present application, at least the following advantageous effects are provided: at present, 40wt% of waste silicon is generated in the slicing process of metal silicon in the photovoltaic industry in China, and the global solar grade bulk silicon yield in 2019 is 45.8 ten thousand tons, namely more than one hundred thousand tons of waste silicon is generated. The waste silicon material is waste silicon generated in the process of cutting silicon ingots in the photovoltaic industry. The application adopts waste silicon material as raw material, which greatly reduces the cost of silicon oxygen cathode material.

In some embodiments of the present application, the silicon-oxygen-based material comprises at least one of a Q element or an a element, wherein Q is a metal element, a is a non-metal element, and the silicon-oxygen-based material comprises SiO _x ，0<x<2。

According to the above embodiment of the present application, at least the following advantageous effects are provided: the doped inner core and the flexible coating layer improve the intrinsic electronic conductivity (the conductivity of the silicon-oxygen anode material body) and the ionic conductivity and the interface stability of the silicon-oxygen anode material, thereby synergistically improving the cycle life of the silicon-oxygen anode material. The inner core doping of the silicon-oxygen anode material improves the conductivity, is beneficial to the circulation performance and improves the quick charge performance. Meanwhile, the flexible coating layer stabilizes the interface, improves circulation and is beneficial to quick charge performance. The doped inner core and the flexible coating layer have the inner and outer synergistic effect, so that the silicon-oxygen anode material has the characteristics of quick charge performance and long service life.

In some embodiments of the application, the Q comprises at least one of Ge, sn, cu, ti and V.

According to the above embodiment of the present application, at least the following advantageous effects are provided: the addition of the metal element improves the ionic conductivity. For example, the atomic radius of metal germanium is large, so that the diffusion channel of the lithium ion bulk phase can be widened, and the ion conductivity is improved.

In some embodiments of the application, the a comprises at least one of B, P and N.

According to the above embodiment of the present application, at least the following advantageous effects are provided: the nonmetallic doping can promote electron conductivity (such as electron conductivity of silicon in the silicon-oxygen anode material) and improve the performance of the silicon-oxygen anode material.

In some embodiments of the application, the starting material for the silicon-oxygen based material comprises SiO _x A source and a Q source, wherein 0<x<2。

In some embodiments of the application, the Q source comprises at least one of an elemental substance of Q and an oxide of Q.

In some embodiments of the application, the source of a comprises at least one of an elemental substance of a and an oxide of a.

In some embodiments of the application, the element Q in the Q source and the SiO _x The ratio of the mass sum of the elements A in the source A to the mass sum of the elements A in the source A is 100 (0.001-10).

According to the above embodiment of the present application, at least the following advantageous effects are provided: the doping amount of the element A has an important influence on the performance of the silicon-oxygen anode material, compared with the better doping amount, if the doping amount is lower, the doping effect is not achieved, the quick charge effect is not obvious, if the doping amount is too high, part of the element A exists in the form of simple substance A under the high doping amount, and the non-metal simple substance conductivity is not good, so if the doping amount of the element A is too high, the quick charge performance of the silicon-oxygen anode material is not good, and the initial effect is low. Therefore, the proper doping amount of the A element can play a good role in doping.

In some embodiments of the application, the element Q in the Q source and the SiO _x The ratio of the mass sum of the elements A in the source A to the mass sum of the elements A in the source A is 100 (0.1-5).

In some embodiments of the application, the element Q in the Q source and the SiO _x The ratio of the mass sum of the elements A in the source A to the mass sum of the elements A in the source A is 100 (0.1-2).

In some embodiments of the application, the element Q in the source Q is the same as the SiO _x The mass fraction ratio of (1) is (0.001-10): 100.

In some embodiments of the application, the element Q in the source Q is the same as the SiO _x The mass fraction ratio of (1-5) is 100.

In some embodiments of the application, the element Q in the source Q is the same as the SiO _x The mass fraction ratio of (2-0.05): 100.

In some embodiments of the application, the element Q in the source Q is the same as the SiO _x The mass fraction ratio of (1-2) is 100.

In some embodiments of the application, the starting material for the silicon-oxygen based material comprises SiO ₂ Waste silicon material, source a and source Q.

According to the above embodiment of the present application, at least the following advantageous effects are provided: the application adopts waste silicon material as raw material, which greatly reduces the cost of silicon oxygen cathode material.

In a second aspect of the present application, a method for preparing a silicon-oxygen anode material is provided, including the following steps: preparing a kernel; preparing a flexible coating layer: the method comprises the steps of preparing a flexible coating layer containing M on the surface of an inner core by taking alkyl metal and alcohol as raw materials, wherein M is a metal element.

According to the above embodiment of the present application, at least the following advantageous effects are provided: according to the application, the flexible coating layer is prepared from the alkyl metal and the alcohol, and is flexible, so that huge volume change of the silicon-oxygen negative electrode caused by lithium intercalation and lithium deintercalation in the charge and discharge process can be limited, the damage to an interface SEI film is reduced, the cracking degree of the SEI film is alleviated, the generation of a fresh interface is reduced, the consumption of reversible lithium is reduced, and the cycle performance of a battery is improved. In addition, the flexible coating layer contains a metal element M, so that the electric conductivity of the flexible coating layer can be improved, and the quick charge performance of the silicon-oxygen negative electrode is improved. The flexible coating layer containing the metal element M has the flexibility of common organic matters and the high conductivity of metal, and the quick charge performance and the cycle life of the silicon-oxygen negative electrode can be improved under the synergistic effect of the metal and the organic matters in the flexible coating layer.

In some embodiments of the application, the flexible coating containing M is prepared on the surface of the core using atomic layer deposition techniques.

According to the embodiment of the application, the formation and thickness of the flexible coating layer are easy to control by adopting an atomic layer deposition technology, and the design is reasonable.

In some embodiments of the application, the preparation of the flexible coating comprises the following operations:

s1, depositing alkyl metal on the surface of the inner core by adopting an atomic layer deposition technology to obtain a material I;

s2, depositing alcohol on the surface of the material I obtained in the step S1 by adopting an atomic layer deposition technology to obtain a material II;

s3, repeating the steps S1-S2 n times on the surface of the material II by adopting an atomic layer deposition technology to obtain the silicon-oxygen anode material, wherein 199 is more than or equal to n is more than or equal to 0.

According to the above embodiment of the present application, at least the following advantageous effects are provided: the metal alkyl is attached to the surface of the inner core of the silicon-oxygen negative electrode material, and the metal alkyl has a bridge-like effect, can be connected with the inner core silicon-oxygen base material of the silicon-oxygen negative electrode material and alcohols, and can cooperatively improve various electrochemical properties of the silicon-oxygen negative electrode material. The flexible coating layer is prepared by adopting an atomic layer deposition technology, has reasonable design and is easy to control the formation and thickness of the flexible coating layer.

In some embodiments of the application, the flexible coating is prepared in a deposition reaction chamber having a temperature of 100-200 ℃.

In some embodiments of the application, the vacuum level of the deposition reaction chamber is from 5 Pa to 100Pa prior to depositing the metal alkyl on the surface of the core.

In some embodiments of the present application, in the step S1 or step S3, in the step of depositing the metal alkyl, the gaseous metal alkyl is transported with a carrier gas to obtain a first mixed gas, the first mixed gas has a velocity of 1-100sccm, and the first reaction time is 0-5S, wherein the carrier gas is an inert gas, and the first reaction time is not 0S.

The first reaction time refers to the action time of the first mixed gas and the deposition target.

In some embodiments of the application, the ratio of the carrier gas to the metal alkyl in the first mixed gas is about 2:1 by mass.

In some embodiments of the present application, in step S1 or step S3, after each time of delivering the gaseous metal alkyl, a carrier gas is introduced for 0 to 100 seconds, wherein the carrier gas is an inert gas, and the time for introducing the carrier gas is not 0 seconds.

According to the above embodiment of the present application, at least the following advantageous effects are provided: after each gaseous alkyl metal delivery is completed, a carrier gas is introduced to remove excess gaseous alkyl metal so as to avoid the residual gaseous alkyl metal in the deposition reaction chamber from adversely affecting the formation of the flexible coating layer. Wherein the inert gas comprises argon.

In some embodiments of the present application, in the step S2 or step S3, in the step of depositing alcohol, the gaseous alcohol is transported by a carrier gas to obtain a second mixed gas, the second mixed gas has a rate of 1-100sccm, and the second reaction time is 0-5S, wherein the carrier gas is an inert gas, and the second reaction time is not 0S.

The second reaction time refers to the action time of the second mixed gas and the deposition target. The inert gas includes argon.

In some embodiments of the application, the ratio of the carrier gas to the alcohol in the second mixed gas is about 2:1 by mass.

In some embodiments of the present application, in step S2 or step S3, after each time of transporting the gaseous alcohol is completed, a carrier gas is introduced for 0-100S, wherein the carrier gas is an inert gas, and the time for introducing the carrier gas is not 0S.

According to the above embodiment of the present application, at least the following advantageous effects are provided: after each gaseous alcohol delivery, a carrier gas is introduced to remove excess gaseous alcohol so as to avoid the residual gaseous alcohol in the deposition reaction chamber from adversely affecting the formation of the flexible coating layer. Wherein the inert gas comprises argon.

In the step S3, n is more than or equal to 0 and less than or equal to 199, and the method has at least the following beneficial effects: the number of times of alternately and repeatedly depositing the alkyl metal material and the alcohol on the surface of the material II influences the thickness of the final flexible coating layer, and further influences each property of the silicon-oxygen anode material, so that the proper n value has important significance on the property of the silicon-oxygen anode material.

In some embodiments of the present application, in step S3, 0.ltoreq.n.ltoreq.99.

In some embodiments of the application, in step S3, 4.ltoreq.n.ltoreq.49.

In some embodiments of the application, the preparation step of the core comprises the following operations:

s0-1, Q doping: taking SiO _x And a Q source, in a closed environment, adopting a vapor deposition technology to obtain Q-phase doped SiO _x Wherein 0 is<x<2；

S0-2, A doping: taking the source A and the Q phase doped SiO obtained in the step S0-1 _x Grinding to obtain SiO co-doped with A and Q _x And obtaining the kernel.

According to the above embodiment of the present application, at least the following advantageous effects are provided: the application realizes the doping of the metal element Q by the vapor deposition technology, and realizes the doping of the nonmetal element A by mechanical ball milling, which is superior to the traditional one-step doping, and avoids the problems of metal element and nonmetal element in the one-step methodExcessive consumption of energy due to excessive difference in sublimation temperature of (a) doping element and SiO _x The doping uniformity is poor due to the overlarge boiling point difference.

In some embodiments of the present application, in step S0-1, siO is the starting material _x Comprises waste silicon material and SiO ₂ 。

According to the above embodiment of the present application, at least the following advantageous effects are provided: the application directly uses the waste silicon material in the photovoltaic industry as a raw material, does not need acid washing and water washing to remove impurities, removes impurities by utilizing the difference of metal sublimation temperatures, removes impurities such as Fe/Al/Ni/Mn and the like, and reduces the influence of the impurities on the performance of the silicon-oxygen anode material. (e.g., metallic Fe impurities may cause self-discharge of the cell and localized micro-shorting.)

In some embodiments of the application, the waste silicon material is mixed with SiO ₂ The molar ratio of (2) is (0-100): 1.

In some embodiments of the application, the waste silicon material is mixed with SiO ₂ The molar ratio of (2) is (0.33-3): 1.

In some embodiments of the present application, in step S0-1, the closed environment comprises a reaction zone and a deposition zone which are communicated, and SiO is taken out _x And a Q source is arranged in the reaction zone, the Q phase doped SiO _x Is formed in the deposition area.

In some embodiments of the application, the Q source is elemental germanium, the temperature of the reaction zone is 1000-1400 ℃, the temperature of the deposition zone is 600-800 ℃, and the pressure of the closed environment is 10-300Pa.

In some embodiments of the application, in step S0-2, the ball milling atmosphere is argon.

In some embodiments of the application, in step S0-2, the ball milling time is 0-3 hours.

In some embodiments of the present application, in step S0-2, when the source a is elemental phosphorus or elemental boron, a plasma ball mill is used to perform ball milling, the voltage is applied to the ball mill at 5-20kV, the ball milling atmosphere is argon, and the ball milling time is 0.01-3h.

In some embodiments of the present application, the method further comprises a step S0-3, wherein the step S0-2 The obtained A and Q co-doped SiO _x The particle diameter D is obtained by jet milling and classification ₅₀ 3-15 μm A and Q co-doped SiO _x 。

In a third aspect of the present application, a secondary battery is provided that includes a negative electrode that includes the silicon-oxygen negative electrode material described above.

In a fourth aspect of the present application, there is provided an electric device including the above secondary battery, the secondary battery being used as a power source of the electric device.

Detailed Description

The conception and the technical effects produced by the present application will be clearly and completely described in conjunction with the embodiments below to fully understand the objects, features and effects of the present application. It is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments, and that other embodiments obtained by those skilled in the art without inventive effort are within the scope of the present application based on the embodiments of the present application.

Example 1

The embodiment prepares a silicon oxygen anode material, which comprises the following specific processes:

doping metal elements:

directly using waste silicon materials (waste silicon powder, washing with acid and water to remove impurities, and utilizing the difference of metal sublimation temperature to remove impurities) in the photovoltaic industry as raw materials, taking 1kg of waste silicon materials in the photovoltaic industry, 2.143kg of silicon dioxide (although the waste silicon materials contain partial impurities, the quantity of the impurities is very small and can be ignored, wherein the molar ratio of silicon to silicon dioxide is 1:1), 0.0157kg of metal germanium, placing the three raw materials into a closed reaction kettle with adjustable temperature and pressure, and communicating the reaction kettle with a closed deposition chamber with adjustable temperature and pressure through a pipeline. Wherein the temperature of the reaction kettle is set to 1200 ℃, the temperature of the deposition chamber is set to 700 ℃, the pressure of the whole space of the reaction kettle and the deposition chamber which are communicated is regulated to 100Pa, and metal silicon, silicon dioxide and germanium in the reaction kettle react under heating to generate bulk germanium doped SiO _x Depositing the gas in a deposition chamber to obtain bulk germanium-phase doped SiO _x (reaction of silicon and silicon dioxide at high temperature)SiO formation _x ，0<x<2, germanium element is doped in SiO _x In (c) a).

(II) non-metallic element doping:

taking SiO doped with germanium phase in the step (I) _x 1kg of red phosphorus 0.005kg is put into a plasma ball mill for ball milling, wherein parameters of the plasma ball mill are set: the plasma adopts the application voltage of 10kV, the ball milling atmosphere is argon, and the ball milling time is 1h; finally obtaining the phosphorus-germanium co-doped SiO _x Jet milling and classifying to obtain particle diameter D ₅₀ SiO of 6 μm _x Designated as core sample 1. (wherein D ₅₀ Can be measured by a laser particle size distribution instrument

(III) taking 1kg of the core sample 1 prepared in the step (II), placing the core sample 1 in a reaction chamber of an atomic layer deposition device, heating and vacuumizing, and regulating the temperature of the reaction chamber to 130 ℃ and the vacuum degree to 20Pa.

(IV) introducing gaseous diethyl zinc Zn (C) into the reaction chamber by taking argon as carrier gas ₂ H ₅ ) ₂ (according to argon and gaseous diethyl Zinc Zn (C) ₂ H ₅ ) ₂ Introducing the mixture into a reaction chamber at a mass ratio of 2:1) at a gas rate of 10sccm (gas rate of a mixed gas of gaseous diethyl zinc and argon), a first reaction time of 1s, and then introducing argon gas into the reaction chamber for 30s by taking argon gas as a cleaning gas to remove excessive diethyl zinc Zn (C) ₂ H ₅ ) ₂ And (3) gas. The first reaction time is the action time of the mixed gas of the gaseous diethyl zinc and the argon and the deposition target.

And (V) taking argon as carrier gas, introducing gaseous ethylene glycol (the ratio of the argon to the ethylene glycol is 2:1 by mass) into the reaction chamber, wherein the gas introducing rate is 10sccm (the gas rate of the mixed gas of the gaseous ethylene glycol and the argon), the second reaction time is 1s, and then taking the argon as cleaning gas, introducing the argon into the reaction chamber for 30s, and removing the redundant gaseous ethylene glycol. The second reaction time is the action time of the mixed gas of glycol and argon and the deposition target.

(VI) repeating the steps (IV) - (V) for 1 time to finally obtain the product with the surface layer coated by the flexible coating layer and the inner core dopedDoped SiO _x The sample prepared in this example is designated sample 1.

Example 2

This example prepared a silicon oxygen negative electrode material, which was different from example 1 in that: in step (vi) of the present embodiment: the steps (IV) - (V) "were repeated 99 times, and in this example, diethyl zinc/ethylene glycol was alternately deposited 100 times on the surface of the core sample, and the sample prepared in this example was designated as sample 2.

Example 3

This example prepared a silicon oxygen negative electrode material, which was different from example 1 in that: in step (vi) of the present embodiment: the steps "(IV) - (V)" were repeated 29 times, and in this example, diethyl zinc/ethylene glycol was alternately deposited on the surface of the core sample 30 times, and the sample prepared in this example was designated as sample 3.

Example 4

This example prepared a silicon oxygen negative electrode material, which was different from example 3 in that: the order of the gaseous ethylene glycol and the gaseous diethyl zinc are changed. That is, the steps "(IV)", "(V)", and "(IV)", of example 3 were exchanged, and the steps "(V)", "(IV)", and "," were used in this example. The sample prepared in this example was designated sample 4 by introducing gaseous ethylene glycol followed by gaseous diethyl zinc and then alternately depositing ethylene glycol/diethyl zinc 29 times.

Example 5

This example prepared a silicon oxygen negative electrode material, which was different from example 1 in that:

in the step (II) nonmetallic element doping: the doped "red phosphorus 0.005kg" in example 1 was replaced by "elemental boron 0.001kg";

in step (vi): repeating the steps (IV) - (V) 29 times to finally obtain the SiO with the surface layer coated by the flexible coating layer and the doped inner core _x The sample prepared in this example is designated sample 5.

Example 6

This example prepared a silicon oxygen negative electrode material, which differs from example 5 in that: the amount of elemental boron added was 0.05kg, and the sample prepared in this example was designated sample 6.

Example 7

This example prepared a silicon oxygen negative electrode material, which differs from example 5 in that: the amount of elemental boron added was 0.005kg, and the sample prepared in this example was designated sample 7.

Example 8

This example produced a silicon oxygen negative electrode material, which was different from example 7 in that "0.0157 kg of metallic germanium" was replaced with "0.0157 kg of metallic tin" in the doping of the metallic element in step (i), and the sample produced in this example was designated as sample 8.

Example 9

This example produced a silicon oxygen negative electrode material, which was different from example 7 in that "0.0157 kg of metallic germanium" was replaced with "0.0157 kg of metallic copper" in the doping of the metallic element in step (i), and the sample produced in this example was designated as sample 9.

Example 10

This example produced a silicon oxygen negative electrode material, which was different from example 7 in that "0.0157 kg of metallic germanium" was replaced with "0.0157 kg of metallic titanium" in the doping of the metallic element in step (i), and the sample produced in this example was designated as sample 10.

Example 11

This example produced a silicon oxygen negative electrode material, which was different from example 7 in that "0.0157 kg of metallic germanium" was replaced with "0.0157 kg of metallic vanadium" in the doping of the metallic element in step (i), and the sample produced in this example was designated as sample 11.

Example 12

This example prepared a silicon oxygen negative electrode material, which was different from example 7 in that:

in the step (I), the amount of germanium metal added was 0.0314kg, and the sample prepared in this example was designated as sample 12.

Example 13

in the step (I), the amount of germanium metal added was 0.06286kg, and the sample prepared in this example was designated as sample 13.

Example 14

in the step (I), the amount of germanium metal added was 0.15715kg, and the sample prepared in this example was designated as sample 14.

Example 15

in the step (I), the amount of germanium metal added was 0.0000314kg, and the sample prepared in this example was designated as sample 9.

Example 16

in the step (I), the amount of germanium metal added was 0.314kg, and the sample prepared in this example was designated as sample 10.

Example 17

the amount of elemental boron added was 0.00001kg, and the sample prepared in this example was designated as sample 17.

Example 18

The amount of elemental boron added was 0.1kg, and the sample prepared in this example was designated as sample 18.

Example 19

the amount of elemental boron added was 0.01kg, and the sample prepared in this example was designated as sample 19.

Example 20

the amount of elemental boron added was 0.02kg, and the sample prepared in this example was designated as sample 20.

Example 21

in step (vi): and (3) the steps (IV) - (V) are not repeated, and finally the SiO with the surface layer coated by the flexible coating layer and the doped inner core is obtained _x The sample prepared in this example is designated sample 21.

Example 22

in step (vi): repeating the steps (IV) - (V) 199 times to finally obtain SiO with the surface layer coated by the flexible coating layer and the doped inner core _x The sample prepared in this example is designated sample 22.

Example 23

This example produced a silicon oxygen negative electrode material, which differs from example 12 in that:

And (3) replacing the original material ethylene glycol in the step (V) with 1, 3-propylene glycol.

The sample prepared in this example is designated sample 23.

Example 24

replacing the original material ethylene glycol in the step (V) with 1, 20-eicosane glycol C ₂₀ H ₄₂ O ₂ 。

The sample prepared in this example is designated sample 24.

Example 25

the raw material diethyl zinc Zn (C) in the step (IV) ₂ H ₅ ) ₂ Replaced by C ₂ H ₆ CuLi。

The sample prepared in this example was designated sample 25.

Example 26

the raw material diethyl zinc Zn (C) in the step (IV) ₂ H ₅ ) ₂ Replaced by Ge (C) ₂ H ₅ ) ₄ 。

The sample prepared in this example is designated sample 26.

Example 27

replacing the original material ethylene glycol in the step (V) with 1, 3-propylene glycol;

the raw material diethyl zinc Zn (C) in the step (IV) ₂ H ₅ ) ₂ Replaced by Sn (C) ₂ H ₅ ) ₄ 。

The sample prepared in this example is designated sample 27.

Comparative example 1

The comparative example prepared a silicon oxygen negative electrode material comprising the steps of:

Doping metal elements:

directly using waste silicon materials (waste silicon powder, washing with acid and water to remove impurities, and utilizing the difference of metal sublimation temperature to remove impurities) in the photovoltaic industry as raw materials, taking 1kg of waste silicon materials in the photovoltaic industry, 2.143kg of silicon dioxide (although the waste silicon materials contain partial impurities, the quantity of the impurities is very small and can be ignored, wherein the molar ratio of silicon to silicon dioxide is 1:1), 0.0157kg of metal germanium, placing the three raw materials into a closed reaction kettle with adjustable temperature and pressure, and communicating the reaction kettle with a closed deposition chamber with adjustable temperature and pressure through a pipeline. Wherein the temperature of the reaction kettle is set to 1200 ℃, the temperature of the deposition chamber is set to 700 ℃, the pressure of the whole space of the reaction kettle and the deposition chamber which are communicated is regulated to 100Pa, and metal silicon, silicon dioxide and germanium in the reaction kettle react under heating to generate bulk germanium doped SiO _x Depositing the gas in a deposition chamber to obtain bulk germanium-phase doped SiO _x (silicon and silicon dioxide react at high temperature to form SiO) _x ，0<x<2, germanium element is doped in SiO _x In (c) a).

(II) non-metallic element doping:

taking the stepsSiO doped with germanium phase in (I) _x 1kg of red phosphorus 0.001kg is put into a plasma ball mill for ball milling, wherein parameters of the plasma ball mill are set: the plasma adopts the application voltage of 10kV, the ball milling atmosphere is argon, and the ball milling time is 1h; finally obtaining the phosphorus-germanium co-doped SiO _x Jet milling and classifying to obtain particle diameter D ₅₀ SiO of 6 μm _x The sample is denoted as a reference S1. (wherein D ₅₀ Can be measured by a laser particle size distribution instrument

Comparative example 2

A silicon oxygen anode material was prepared in this comparative example, which was different from comparative example 1 in that the addition amount of red phosphorus was 0.05kg, and the sample prepared in this comparative example was designated as comparative sample S2.

Comparative example 3

A silicon oxygen anode material was prepared in this comparative example, which was different from comparative example 1 in that the addition amount of red phosphorus was 0.005kg, and the sample prepared in this comparative example was designated as comparative sample S3.

Comparative example 4

This comparative example produced a silicon oxygen anode material, which was different from comparative example 1 in that: the mass of silica was 2.143kg, and the addition amounts of phosphorus and germanium were 0, to obtain comparative example comparative sample S4.

Comparative example 5

This comparative example prepared a silicon oxygen negative electrode material, which differs from comparative example 3 in that: the phosphorus addition was 0, giving a comparative sample S5 doped with germanium only.

Comparative example 6

This comparative example prepared a silicon oxygen negative electrode material, which differs from comparative example 3 in that: the germanium addition was adjusted to 0 to obtain a phosphorus-doped control S6 alone.

Comparative example 7

This comparative example produced a silicon oxygen anode material, which differs from comparative example 6 in that: and replacing the elemental phosphorus with elemental boron to obtain a comparison sample S7 doped with boron only.

Specific parameters of the silicon-based anode materials prepared according to the methods of the above examples and comparative examples are shown in table 1, in which the mass ratio of the metal element M to the outer shell is measured using energy spectrum EDS; the mass ratio of the flexible coating layer to the inner core is measured by adopting TG, wherein the temperature-raising program is as follows: after rising to 600℃from room temperature at 10℃per minute, the temperature was kept constant for 1 hour.

TABLE 1

Test examples

Making buckling CR2032 and 3Ah soft package full-electric performance detection on samples 1-27 obtained in examples 1-27 and comparative samples S1-7 obtained in comparative examples 1-7, wherein the test results are shown in Table 2;

wherein, the negative electrode proportion of the button cell is that the active material: conductive agent SP: modified polyacrylic acid=93:3:4, wherein the active material is a sample of example or comparative example, the coin cell battery tests the gram capacity and first effect of the negative electrode, first effect=charge capacity/discharge capacity; (the buckling corresponds to half-cells, and metal Li is used as a counter electrode, and some electrochemical properties about the anode material itself can be obtained by buckling).

The negative electrode formula of the soft package battery comprises the following active substances: conductive agent SP: the mass ratio of the modified polyacrylic acid is 93:3:4, the positive electrode adopts a nickel cobalt lithium manganate NCM811 positive electrode material, and the active substances are as follows: conductive agent SP: the mass ratio of the binder is 97:2:1. The pouch cell characterizes cycle life and anode thickness expansion, wherein the active material consists of 12% of the example or comparative sample and 88% of artificial graphite. LPF with 1.2mol/L electrolyte is selected ₆ The solvent was EC/DMC with a molar ratio of 1:1 plus 10wt% FEC (equivalent to 10% of the mass of FEC as the sum of the masses of EC and DMC). (EC: ethylene carbonate, DMC: dimethyl carbonate, FEC: fluoroethylene carbonate).

(II) the cells Cell 1-27 to Cell-S1-7 obtained in examples 1-27 and comparative examples 1-7 were subjected to electrical performance test, and the test results are shown in Table 3;

1) And (3) initial efficiency test of the battery cell: the first-turn discharge capacity of the battery cell/the first-turn charge capacity of the battery cell.

2) And (3) performing test on the capacity of the first coil positive electrode gram of the battery cell: the first circle discharge capacity mAh of the battery cell/the mass g of the positive electrode active material.

3) And D, testing the DC internal resistance DCR of the battery cell: the battery capacity was divided and adjusted to 50% soc,5C 10S was discharged, and the discharge resistance, resistance dcr= (V0-V10)/I, where V0 is the potential before discharge, V10 is the 10 th S potential of discharge, and I is the discharge current 5C, was tested.

4) Capacity retention test: (1) charging: 1C CC to 4.2V,Rest 10min; (2) discharging: 1C DC to 2.5V,Rest 0min, the discharge capacity was noted as Qn (n=1, 2,3 … … 400); (3) repeating the steps (1) and (2) for 400 circles. The capacity retention rate of 400 circles of full electricity is as follows: Q400/Q1.

5) High temperature storage test:

dividing the capacity of the battery cell at room temperature of 25 ℃ at 1C, and recording the obtained capacity as D0;

fully filling the battery cell 1C, then placing the battery cell in a 60 ℃ oven for high-temperature storage for 30 days, then taking out, cooling at room temperature, testing the recovery capacity, marking as D1, and calculating the recovery rate of the high-temperature storage capacity of the battery cell: D1/D0.

6) Volume expansion test:

400 circles of battery cells are circulated, the battery cells are disassembled fully, the thickness of a micrometer card is d2, the rolling thickness d1 of a fresh pole piece is calculated fully by 400 circles of battery cells fully, and the expansion is calculated fully: (d 2-d 1)/(d 1-8). (copper foil thickness of 8 μm)

7) Lithium precipitation test:

(1) charging: 2.4C CC to 4.2V,Rest 10min; (2) discharging: 1C DC to 2.5V,Rest 10min;

after 10cls (10 circles), the negative electrode interface was observed after 2.4C CC to 4.2V full charge and disassembly.

TABLE 2 sample power-down data for examples 1-27 and comparative examples 1-7

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Table 3 all cell electrical performance data were made for examples 1-27 and comparative examples 1-7

From tables 2 and 3 above:

(1) Regarding the presence or absence of the flexible coating layer:

test results by comparative example 3, examples 1-3: comparative example 3 has no high electrical conductivity flexible coating and is far inferior to examples 1-3 which contain a flexible coating. The product obtained in examples 1-3 is coated with a flexible coating layer (containing a high molecular compound), the flexibility of the product can improve the interface stability, and reduce the SEI reforming repair degree, so that irreversible lithium consumption is reduced, in addition, the flexible coating layer contains oxygen and hydrogen elements, hydrogen bonds (including intramolecular hydrogen bonds and intermolecular hydrogen bonds) can be formed, a large number of hydrogen bonds form high molecular fatigue caused by expansion of the flexible coating layer during lithium intercalation of a silicon-oxygen negative electrode and volume shrinkage of lithium extraction, the long-term stability of a coating interface is improved, in addition, zinc in the flexible coating layer can also react with lithium to generate lithium-zinc alloy to promote lithium intercalation and extraction of lithium in the flexible coating layer, and the conductance of the flexible coating layer is improved, so that the extremely fast charging performance of the silicon-oxygen negative electrode is improved. The improvement of the flexible coating layer on the interface and the improvement of the lithium ion diffusion capability improve the cycle life of the silicon-oxygen cathode, and the flexibility of the high polymer compound can alleviate the silicon inter-particle distance and reduce the expansion, so that the expansion and the cycle life of the examples 1-3 are superior to those of the uncoated comparative example 3. The physical isolation of the flexible coating layer reduces the side reaction of the silicon oxygen cathode and the electrolyte at high temperature, thereby improving high-temperature storage and gas production, so that the high-temperature storage and gas production of the examples 1-3 are superior to the comparative example 3 without the coating of the flexible coating layer.

The test "2.4C lithium analysis" for Cell S3 and Cell 1-3 is not lithium analysis, and the results are not equivalent to those of Cell S3 and Cell 1-3, but are not further distinguished: that is, the material is required to be quickly charged at 2.4C, and both Cell S3 and Cell 1-3 are satisfied, but the substantial performance of Cell 1-3 is superior to Cell S3.

(2) Regarding the thickness of the flexible coating layer:

in tables 2 and 3, from the test results of examples 1 to 3 and examples 7, 21, and 22, the high-conductivity flexible coating layer thickness (including the polymer coating amount) had an influence on the initial effect and gram capacity, and the polymer coating amount was too low for good coating effect, and the polymer coating layer thickness was too high for examples 2 and 22, and the gram capacity was deteriorated to some extent, compared with the preferable flexible coating layer thickness (examples 3 and 7).

Therefore, the performance of the silicon-oxygen anode material can be further optimized by selecting a proper thickness of the flexible coating layer.

(3) With respect to exchanging molecular deposition coating gas source sequence:

from the comparative data of example 3 and example 4 in tables 2 and 3, changing the molecular deposition coating gas source sequence affects the silica performance: first, the adsorbed alcohol may not adhere to the silica surface more firmly, and may not form a "nail-like effect", and may exist as a separate polymer rather than a coating layer, failing to provide a good coating effect.

Regarding the flexible coating layer: diethyl zinc corresponds to a bridge, for SiO _x And ethylene glycol is connected, in addition, zinc in diethyl zinc provides electric conduction, ethylene glycol contains-OH, hydrogen bonds can be generated between O and H, elasticity is provided, self-repairing restoration of the flexible coating layer at present is derived from the hydrogen bonds between molecules and inside the molecules, the self-repairing restoration is disconnected after being stressed and expanded, and strong electronegativity due to oxygen can be automatically generated after external force is removed.

(4) Regarding the doping amount of the metal element:

according to the embodiment 7, 12-16, the addition of metal germanium can widen a diffusion channel of a core, promote bulk diffusion coefficient of lithium, reduce core delithiation resistance, reduce dead lithium quantity of the core (lithium can not be extracted due to diffusion resistance), and promote initial effect and gram capacity of the battery, and particularly according to the embodiment 7, 12, 13, 14 and 16, along with the improvement of germanium doping quantity, initial effect and gram capacity of the battery are promoted, and the embodiment 15 does not achieve doping effect due to too low germanium doping quantity, so that the battery performance is not obviously improved. If the doping amount is too high, germanium as an inactive ingredient may cause gram capacity sacrifice, and at the same time, part of germanium may exist in the form of oxide, which is poor in electron conductivity and has a risk of deterioration of the fast charge and the cycle life. Specifically, examples 12, 13, 14, 16 show a decreasing trend in the silicon gram capacity (29-185 mAh/g decrease) as the germanium doping increases gradually, and as part of the germanium may exist in the form of germanium oxide, which has high resistance relative to the metal germanium, deteriorating the internal resistance of the cell, examples 13, 14, 16 increase by 1-3mohm as compared with example 12, the internal resistance of the cell increases, deteriorating the cycle life, storage life and other electrical properties of the battery.

(5) Regarding the non-metal element doping amount:

from examples 5 to 7 and examples 17 to 18, too low or too high boron doping is detrimental to the silicon oxygen capacity and the first effect compared to the preferred boron doping amount. Too low to have a doping effect, too high, boron as inactive ingredient, which exists in elemental or oxide form deteriorating gram capacity: specifically, in the embodiment 5 and the embodiment 17 with extremely low boron doping amount, the obvious doping effect is not achieved because the boron doping amount is too low, the first gram capacity and the first effect are lower than those of the embodiment 7, the boron doping amount is improved in the embodiment 7, and the synergistic effect of boron and germanium co-doping further improves the silicon oxygen gram capacity and the first effect. However, since the boron doping amount in examples 6 and 18 was too high, the gram capacity test result of example 6 was lower than that of comparative example 3, and example 18 further increased the boron doping amount on the basis of example 6, the gram capacity was further deteriorated, and the gram capacity test result was lower than that of comparative examples 1 to 3.

Similarly, from comparative examples 1 to 3 in Table 2, the excessively low or excessively high phosphorus doping amount is detrimental to the silicon oxygen gram capacity and the first effect, the excessively low or excessively high phosphorus doping amount does not exert the doping effect, the phosphorus exists as a simple substance phase, the first effect of the simple substance phosphorus is low, the electric conductivity is low, and the first effect and the gram capacity are affected.

Specifically, in Cell S1, the doping amount of phosphorus is low, the doping effect is not achieved, and the rapid charging effect is not obvious, so that lithium is separated out by 2.4; in Cell S2, the doping amount of phosphorus is higher, part of phosphorus exists in the form of elemental phosphorus under the high doping amount, and the elemental phosphorus is characterized in that: the conductivity is not good, the first effect is low, so the Cell S2 has not good quick charge performance, the lithium is separated out from 2.4C, and the first effect is low. The phosphorus doping amount of the Cell S3 is in a better range, so that a better doping effect is achieved.

Because the phosphorus doping amount is too much in comparative example 2, part of the phosphorus exists in the form of elemental phosphorus, and the elemental phosphorus has low electric conduction and low initial efficiency, so that the initial efficiency, internal resistance, quick charge performance and other performances of the materials and the battery cells are deteriorated. Thus, comparative example 2 was inferior in partial performance to comparative examples 5 to 7 as compared with comparative examples 5 to 7.

(6) Regarding core single element doping and multi-element doping:

from tables 2 and 3, comparative examples 4 to 7: compared with comparative example 4, the single doping of germanium, phosphorus and boron has positive effects, the gram capacity of the first circle of the silicon-oxygen negative electrode is improved by 57-79mAh/g, the first effect is improved by about 11%, the doping of germanium, phosphorus or boron can reduce the internal resistance and improve the conductance of the silicon-oxygen negative electrode, the intercalation and deintercalation of lithium are more facilitated, the lithium intercalation and deintercalation resistance is reduced, the lithium loss is reduced, the gram capacity and the first effect of the battery cell are improved, meanwhile, the quick charging performance of the battery cell is improved, the lithium is slightly separated from serious lithium separation of 2.4C, and the first effect, the cycle life and other electrical performances of the battery cell are improved.

From the comparison examples 5-6 and 3 in Table 2, the comparison example 5 doped with germanium alone and the comparison example 6 doped with phosphorus alone have lower gram capacity for initial charge and lower initial effect than those of the comparison example 3 doped with germanium and phosphorus together, and from the internal resistance of the cell in Table 3, the co-doping of germanium and phosphorus can further reduce the internal resistance of the cell, improve the conductivity of the silicon oxygen cathode, and be more beneficial to the intercalation and deintercalation of lithium, thereby improving the gram capacity and initial effect.

From table 3, comparative examples 5-6 and 3, comparative example 5 doped with germanium alone and comparative example 6 doped with phosphorus alone, the battery performance is inferior to that of comparative example 3 doped with germanium and phosphorus together, and the co-doping of germanium and phosphorus can further reduce the internal resistance of the battery cell, reduce the resistance of lithium intercalation and deintercalation, and reduce the lithium loss, thereby improving the first efficiency and the cycle life of the battery cell and other electrical performances. It can be seen from examples 5 to 7, 17 and 18 that in examples 5 and 17, which have extremely low boron doping levels, the boron doping levels are too low, so that no obvious doping effect is achieved, and the appropriate amount of boron and germanium are co-doped, which further reduces the internal resistance of the cell and improves the electrical performance.

(7) Regarding the kind and content of metal elements of the flexible coating layer of the outer shell:

from examples 12, 23 and 24, the content of metallic zinc in the outer shell has an effect on gram capacity and electrical properties, with the preferred zinc content of example 23, the best overall battery performance.

From examples 8 and 25 to 27, the metal elements Cu/Ge/Sn of the shell can all play the role of metal Zn, and the performances of the obtained silicon-oxygen anode material are equivalent, so that the electrical performance of the silicon-oxygen anode material is improved.

Similarly, from comparative examples 1-3, the right amount of phosphorus doping combined with germanium doping is superior to germanium doping alone, and excessive phosphorus doping results in phosphorus existing in the form of simple substance, and the electric conductivity of simple substance phosphorus is low, thereby deteriorating the rapid charging performance of silicon oxide, resulting in slight lithium precipitation of 2.4C, while the same doping amount is too low to exert the effect of doping, and the electric conductivity of silicon oxide is limited to promote, and also resulting in slight lithium precipitation of 2.4C.

In this context, the meaning of "about" with respect to a numerical value is an error of ±2%.

The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the present application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application.

Claims

1. The silica anode material is characterized by comprising an inner core and an outer shell coated on the surface of the inner core, wherein the inner core comprises a silica-based material, the outer shell is a flexible coating layer containing M, and M is a metal element;

The flexible coating layer is a self-repairing flexible coating layer, the flexible coating layer comprises a self-repairing flexible high polymer compound, and the unit structure of the main chain of the self-repairing flexible high polymer compound is MO _a R _b The unit structure is characterized in that R is hydrocarbon radical, O is oxygen, two ends of the unit structure are O and R respectively, M is connected with R through O, a is more than or equal to 2, and b is more than or equal to 1;

the M comprises at least one of Zn, al, cu, ge and Sn;

the mass fraction ratio of the M to the shell is (17-62): 100.

2. The silicon-oxygen anode material according to claim 1, wherein the ratio of the flexible coating layer to the core is (0.1-10) 100 by mass.

3. The silicon-oxygen anode material of claim 1, wherein the flexible coating layer has a thickness of 0.1-200 nm.

4. The silicon-oxygen anode material according to claim 1, wherein the silicon-oxygen-based material contains at least one of Q element or a element, wherein Q is a metal element, a is a non-metal element, and the silicon-oxygen-based material comprises SiO _x ，0 < x < 2。

5. The silicon-oxygen anode material of claim 4, wherein Q comprises at least one of Ge, sn, cu, ti and V.

6. The silicon-oxygen anode material of claim 4, wherein a comprises at least one of B, P and N.

7. A method for preparing the silicon-oxygen anode material according to claim 1, comprising the steps of: preparing a kernel; preparing a flexible coating layer: the method comprises the steps of preparing a flexible coating layer containing M on the surface of an inner core by taking alkyl metal and alcohol as raw materials, wherein M is a metal element.

8. A secondary battery comprising a negative electrode comprising the silicon-oxygen negative electrode material according to any one of claims 1 to 6 or the silicon-oxygen negative electrode material produced by the method according to claim 7.

9. An electric device comprising the secondary battery according to claim 8, the secondary battery being used as a power source of the electric device.