Pre-lithiated anode material and preparation method thereof, pre-lithiated electrochemical device and application

Abstract

The application provides a pre-lithiated negative material and a preparation method, a pre-lithiated electrochemical device and application thereof, and relates to the technical field of battery materials. The pre-lithiated negative material comprises a silicon-based negative material and an artificial SEI film coated on the surface of the silicon-based negative material, wherein the artificial SEI film is mainly prepared from an electrolyte containing a fluorine-containing additive heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether; the fluorine-containing additive can coordinate with lithium salt, can form a stable artificial SEI film on the surface of the silicon-based negative material, the artificial SEI film has good flexibility and rigidity, can effectively relieve the volume expansion of the silicon-based material, and has small interface resistance with the electrolyte, excellent lithium ion transmission performance, improved electrochemical performance of the silicon-based negative material, and effectively improved high-temperature storage performance and cycle performance of the lithium battery. The application also provides a preparation method of the pre-lithiated negative material, and the preparation method makes the pre-lithiation process controllable.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery materials, and relates to a pre-lithiated negative electrode material, a preparation method thereof, a pre-lithiated electrochemical device and application. BACKGROUND

[0002] With the vigorous development of the global new energy industry, lithium ion batteries are widely used in electronic products, electric tools, electric vehicles and energy storage fields due to their high energy density, low self-discharge, long service life, green environmental protection, reasonable cost and other advantages. With the increasing demand for energy reserves, lithium ion batteries need to carry higher energy density and exhibit better electrochemical performance.

[0003] Silicon-based negative electrodes have become a research hotspot in the field of high-energy-density lithium ion battery negative electrode materials at home and abroad due to their high theoretical specific capacity. However, the silicon-based negative electrode material has a high volume expansion rate during charging and discharging, and the silicon particles are prone to breakage and pulverization, which affects the mechanical structural integrity of the electrode. At the same time, the repeated rupture and formation of the SEI film on the surface of the silicon-based negative electrode material consumes a large amount of electrolyte and active lithium ions, resulting in an increase in the internal resistance of the lithium battery and a decrease in the electrochemical performance. Especially at high temperatures, the stability of the SEI film is poor, the side reactions are intensified, and the performance of the lithium battery is severely deteriorated. Therefore, it is crucial to develop a stable SEI film, improve the interface stability of the silicon-based negative electrode material, and improve the high-temperature storage performance and cycle performance of the lithium battery.

[0004] For example, Chinese Patent Application CN115036492A discloses a preparation method of a lithium ion battery surface modified silicon negative electrode material, which specifically coats PAN on the surface of Si. The PAN coated on the surface of Si can react with S or Se under heat treatment conditions to generate PANS or PANSe. PANS / Se generates PAN-Li x S / Se artificial SEI film after pre-lithiation by soaking in a diphenyl lithium-tetrahydrofuran solution, effectively improving the first coulombic efficiency, cycle performance and rate performance of the silicon-based negative electrode lithium ion battery. However, the diphenyl lithium-tetrahydrofuran solution has high flammability and high safety risks, and PAN-Li x S / Se as an artificial SEI film, on the one hand, PAN is not conductive, and on the other hand, it is prone to produce non-conductive residues (S, SeO3) during charging and discharging, affecting the spatial continuity of the electrode and restricting electron transmission.

[0005] Chinese patent application CN113745519A discloses a silicon-based negative electrode material with an artificial SEI film and a preparation method and application thereof. The silicon-based negative electrode material and agarose are mixed and heated, and then dried to obtain a silicon-based negative electrode material. The silicon-based negative electrode material prepared by the present application has good combination of silicon-based negative electrode material and agarose. The non-polar bond in agarose improves the ionic conductivity. The polar group inhibits the growth of lithium dendrites, reduces the consumption of lithium ions in the first charge and discharge, and further reduces the irreversible capacity of the battery, improves the first coulomb efficiency and cycle stability of the battery. However, the artificial SEI film does not contain Li, and the contact resistance with the electrolyte component is large, which reduces the battery performance.

[0006] In summary, the prior art still lacks a negative electrode material capable of alleviating the volume expansion of a silicon-based negative electrode material and having a chemically stable artificial SEI film and a preparation method thereof. In view of this, the present application is proposed. SUMMARY

[0007] In view of the deficiencies and shortcomings of the prior art, the present application aims to provide a pre-lithiated negative electrode material and a preparation method thereof to prepare a pre-lithiated negative electrode material capable of alleviating the volume expansion of a silicon-based negative electrode material and having a chemically stable artificial SEI film.

[0008] In order to achieve the above-mentioned purpose, the following technical solution is adopted:

[0009] The present application provides a pre-lithiated negative electrode material, comprising a silicon-based negative electrode material and an artificial SEI film coated on the surface of the silicon-based negative electrode material.

[0010] The electrolyte used to form the artificial SEI film comprises a lithium salt, a fluorine-containing additive and a solvent. The fluorine-containing additive comprises heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, and the solvent comprises an ether organic solvent.

[0011] Further, based on the above technical solution of the present application, the mass fraction of the fluorine-containing additive in the electrolyte is 5-15% based on 100% of the mass of the electrolyte.

[0012] And / or, the mass ratio of the electrolyte to the silicon-based negative electrode material is (40-60):(40-60).

[0013] Further, based on the above technical solution of the present application, the lithium salt comprises any one or a combination of at least two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bisfluorosulfonylimide or lithium nitrate.

[0014] And / or, the solvent comprises any one or a combination of at least two of 1,3-dioxolane, 1,2-dimethoxyethane, ethylene glycol dimethyl ether, diethyl ether or 2,2-dimethoxy-4-(trifluoromethyl)-1,3-dioxolane.

[0015] And / or, the electrolyte comprises the following mass fractions of components, based on 100% of the mass fraction of the electrolyte: lithium salt 5-15%, fluorine-containing additive 5-15%, and solvent 70-90%.

[0016] Further, on the basis of the above technical solutions of the present application, the silicon-based negative electrode material comprises any one or a combination of at least two of pure silicon negative electrode material, silicon-carbon negative electrode material, or silicon-oxygen negative electrode material.

[0017] Further, on the basis of the above technical solutions of the present application, the main component of the artificial SEI film comprises Li2CO3 and LiF.

[0018] And / or, the thickness of the artificial SEI film is 50-300 nm.

[0019] The present application also provides a preparation method of the above pre-lithiated negative electrode material, comprising the following steps:

[0020] The mixed solution formed by the silicon-based negative electrode material and the electrolyte is placed in an inert atmosphere, and is subjected to charging and discharging treatment under a certain flow rate, voltage window, and current density, so as to form an artificial SEI film on the surface of the silicon-based negative electrode material.

[0021] The mixed solution after the charging and discharging treatment is subjected to centrifugal separation, and the solid material obtained by the separation is subjected to washing and vacuum drying, so as to obtain a pre-lithiated negative electrode material.

[0022] Further, on the basis of the above technical solutions of the present application, the inert atmosphere comprises helium or argon.

[0023] And / or, the flow rate is 0.01-1 L / min.

[0024] And / or, the voltage window is 2.0-0.005 V.

[0025] And / or, the current density is 1 / 600-1 / 10 C.

[0026] And / or, before the charging and discharging treatment, the step of stirring and heating treatment of the mixed solution placed in the inert atmosphere is further included, the stirring speed is 500-2000 rpm / min, and the heating treatment temperature is 25-50℃.

[0027] And / or, during the charging and discharging treatment, the number of charging and discharging cycles is 1-5 times.

[0028] And / or, the solvent used for washing comprises any one or a combination of at least two of pure water, ethanol, or dimethyl carbonate.

[0029] And / or, the temperature for drying is -50-80 DEG C, and the time for drying is 10-20h.

[0030] The application further provides a pre-lithiation electrochemical device for implementing the preparation method of the pre-lithiation negative electrode material.

[0031] The pre-lithiation device comprises a lithium supplement foil, a diaphragm, a clamping plate, a heating and stirring device and a copper foil, the lithium supplement foil and the diaphragm are stacked on the clamping plate, the diaphragm is located between the lithium supplement foil and the clamping plate, the copper foil is located on the side of the clamping plate away from the lithium supplement foil, the copper foil and the clamping plate form an internal circuit space for storing a mixed solution formed by the silicon-based negative electrode material and the electrolyte, and the heating and stirring device is further arranged in the internal circuit space formed by the copper foil and the clamping plate.

[0032] The circulation device comprises a vacuum tank and a peristaltic pump, the vacuum tank is communicated with the internal circuit space of the pre-lithiation device through a pipeline, and the peristaltic pump is arranged on the pipeline.

[0033] Further, on the basis of the above technical scheme of the application, the clamping plate is a polytetrafluoroethylene clamping plate.

[0034] And / or, the vacuum tank is provided with a stirring device.

[0035] The application further provides application of the pre-lithiation negative electrode material, the preparation method of the pre-lithiation negative electrode material or the pre-lithiation electrochemical device in the field of lithium ion batteries.

[0036] Compared with the prior art, the technical scheme of the application has at least the following technical effects:

[0037] (1) The application provides a pre-lithiation negative electrode material, which comprises a silicon-based negative electrode material and an artificial SEI film coated on the surface of the silicon-based negative electrode material, wherein the artificial SEI film is mainly prepared from an electrolyte containing a fluorine-containing additive heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether; the fluorine-containing additive can coordinate with a lithium salt, can form a stable artificial SEI film on the surface of the silicon-based negative electrode material, and has good flexibility and rigidity, can effectively relieve the volume expansion of the silicon-based material, and has small interface resistance between the artificial SEI film and the electrolyte, excellent lithium ion transmission performance, improved electrochemical performance of the silicon-based negative electrode material and improved high-temperature storage performance and cycle performance of the lithium battery.

[0038] (2) The application further provides a preparation method of the pre-lithiation negative electrode material, which mainly realizes pre-lithiation on the surface of the silicon-based negative electrode material by electrolysis of the electrolyte; the preparation method makes the pre-lithiation process controllable, the artificial SEI film formed has stable chemical properties and good contact with the electrolyte.

[0039] (3) The application provides a pre-lithiation electrochemical device for implementing the preparation method of the pre-lithiation negative electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A structural diagram of the pre-lithiation electrochemical device according to an embodiment of the application.

[0041] 1-lithium supplementing foil; 2-separator; 3-clamping plate; 4-heating and stirring device; 5-copper foil; 6-internal circuit space; 7-peristaltic pump; and 8-vacuum tank. DETAILED DESCRIPTION

[0042] In order to make the objects, technical solutions and advantages of the application clearer, the following will combine the embodiments of the application to clearly and completely describe the technical solutions in the embodiments of the application. It should be understood by those skilled in the art that the embodiments are only used to help understand the application and should not be regarded as specific limitation on the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application. The process parameters not specified in the following embodiments are usually according to conventional conditions.

[0043] The endpoints of the ranges and any values disclosed in the application are not limited to the precise values stated. The ranges or values should be interpreted as approximately between the stated values. For ranges, the endpoints are included between each respective range; the endpoints are included in the respective range or ranges; and each respective range is a separate and independent range. Any numerical values include all values from the lower numerical limit to the upper numerical limit.

[0044] According to a first aspect of the application, a pre-lithiation negative electrode material is provided, comprising a silicon-based negative electrode material and an artificial SEI film coated on the surface of the silicon-based negative electrode material.

[0045] The electrolyte for forming the artificial SEI film comprises a lithium salt, a fluorine-containing additive and a solvent, the fluorine-containing additive comprises heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, and the solvent comprises an ether organic solvent.

[0046] Specifically, the structure of the pre-lithiation negative electrode material in the application is actually a core-shell structure, the inner core is the silicon-based negative electrode material, and the shell is the artificial SEI film coated on the surface of the silicon-based negative electrode material. The artificial SEI film can be completely coated on the surface of the silicon-based negative electrode material or partially coated on the surface of the silicon-based negative electrode material.

[0047] In the present application, a specific type of fluorine-containing additive, heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, is added to the electrolyte for forming the artificial SEI film. The heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether has a molecular structure containing a large number of fluorine atoms, which can coordinate with lithium salt and reduce to form a stable artificial SEI film with LiF as the main component on the surface of the silicon-based negative electrode material. The artificial SEI film rich in LiF can, on the one hand, adjust the uniform deposition of the lithium flux, optimize the lithium storage structure of the pre-lithiated negative electrode material, and avoid local over-lithiation leading to stress cracking of the silicon-based negative electrode material; on the other hand, it has good mechanical stability, good flexibility and rigidity, and can effectively alleviate the volume expansion of the silicon-based negative electrode material. The in-situ formed LiF has a certain self-repairing function. At the same time, the interface resistance between the artificial SEI film and the electrolyte is small, and the lithium ion transport performance is excellent, which can effectively improve the electrochemical performance of the silicon-based negative electrode material and improve the high-temperature storage performance and cycle performance of the lithium ion battery. Through pre-lithiation of the silicon-based negative electrode material, the irreversible capacity loss of the lithium battery can be effectively reduced, and the coulombic efficiency can be improved. +

[0048] As an optional embodiment of the present application, the electrolyte includes the following components in mass fraction of 100%: lithium salt 5-15%, fluorine-containing additive 5-15%, and solvent 70-90%.

[0049] The typical but non-limiting mass fraction of the fluorine-containing additive is 5%, 6%, 8%, 10%, 12%, 14%, or 15%, and any numerical range between any two of the above values. Too little or too much of the fluorine-containing additive will have adverse effects. Too little (less than 5%) of the fluorine-containing additive will affect the proportion of LiF in the SEI film, and too much (more than 15%) of the fluorine-containing additive will easily lead to a decrease in the ionic conductivity of the electrolyte, which is not conducive to the uniform deposition of lithium ions. Therefore, the amount of the fluorine-containing additive is preferably controlled within the above numerical range.

[0050] The typical but non-limiting mass fraction of the lithium salt in the electrolyte is 5%, 6%, 8%, 10%, 12%, 14%, or 15%, and any numerical range between any two of the above values. In addition to the limited amount of lithium salt, the type of lithium salt is also further limited. As an optional embodiment of the present application, the lithium salt includes any one or a combination of at least two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bisfluorosulfonylimide, or lithium nitrate.

[0051] The typical but non-limiting mass fraction of the solvent used in the electrolyte is 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, or 90%, and any numerical range between any two of the above values.

[0052] ​Different from the traditional use of ethylene carbonate and / or methyl ethyl carbonate as electrolyte solvent, the present application has further improvement on the type of solvent. As an optional embodiment of the present application, the solvent includes any one of 1,3-dioxolane, 1,2-dimethoxyethane, ethylene glycol dimethyl ether, diethyl ether or 2,2-dimethoxy-4-(trifluoromethyl)-1,3-dioxolane, or a combination of at least two of them. Such solvent will not cause the agglomeration of negative electrode material, and hinder the flow of electrolyte.

[0053] When the electrolyte forms an artificial SEI film on the surface of the silicon-based negative electrode material, the mass ratio of the electrolyte to the silicon-based negative electrode material will affect the uniformity of the electrochemical reaction. If the mass ratio is too low, the electrolyte flowability is poor, and if the mass ratio is too high, the whole negative electrode material cannot contact the copper foil during the pre-lithiation process, and the formed SEI film is incomplete. As an optional embodiment of the present application, the mass ratio of the electrolyte to the silicon-based negative electrode material is 40-60:40-60. The typical but non-limiting mass ratio of the electrolyte to the silicon-based negative electrode material is 40:40, 40:50, 40:60, 50:40, 50:50, 50:60, 60:40, 60:50 or 60:60, etc.

[0054] As an optional embodiment of the present application, the silicon-based negative electrode material includes any one of pure silicon negative electrode material, silicon-carbon negative electrode material or silicon-oxygen negative electrode material, or a combination of at least two of them.

[0055] The carbon in the silicon-carbon negative electrode material includes any one of soft carbon, hard carbon, artificial graphite or natural graphite, or a combination of at least two of them, wherein typical but non-limiting combination examples include: a combination of soft carbon and hard carbon, a combination of hard carbon and artificial graphite, a combination of artificial graphite and natural graphite.

[0056] Typical but non-limiting combination examples of the silicon-based negative electrode material include: a combination of natural graphite and silicon, a combination of silicon and silicon oxide compound, a combination of silicon oxide compound and silicon carbon compound, a combination of silicon and silicon carbon compound, etc. For example, SiC / graphite or SiO / graphite, wherein the mass ratio of SiC / SiO:graphite is 3-20:80-97. It should be noted that in the above combination examples, the silicon-containing substance (pure silicon, silicon oxide compound or silicon carbon compound) needs to be pre-lithiated, while the carbon-containing substance (soft carbon, hard carbon, hard carbon or artificial graphite, etc.) can be pre-lithiated or not, and the relevant operation is carried out according to the actual needs.

[0057] As an optional embodiment of the present application, the main components of the artificial SEI film include Li2CO3 and LiF. The above main components are mainly the products combined with lithium ions after the reduction and decomposition of the fluorine-containing additive and part of the solvent.

[0058] As an optional embodiment of the present application, the thickness of the artificial SEI film is 50-300 nm. The artificial SEI film has a typical but non-limiting thickness of 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm or 300 nm, and a range between any two values.

[0059] According to a second aspect of the present application, a preparation method of the above-mentioned pre-lithiated negative electrode material is also provided, comprising the following steps:

[0060] The mixed solution of the silicon-based negative electrode material and the electrolyte is placed in an inert atmosphere, and subjected to charge-discharge treatment under a certain flow rate, voltage window and current density, so as to form an artificial SEI film on the surface of the silicon-based negative electrode material.

[0061] The mixed solution after the charge-discharge treatment is subjected to centrifugal separation, and the separated solid material is washed and dried to obtain the pre-lithiated negative electrode material.

[0062] The preparation method mainly realizes the lithium supplement (or pre-lithiation) on the surface of the silicon-based negative electrode material through electrolysis of the electrolyte, and the formed artificial SEI film has stable chemical properties and good contact with the electrolyte.

[0063] As an optional embodiment of the present application, the inert atmosphere includes helium or argon. The mixed solution of the silicon-based negative electrode material and the electrolyte is placed in an inert atmosphere to prevent the electrolyte from absorbing water. If the water content in the electrolyte is more than the required content for the system to form the SEI film, POF3 and LiF precipitates will be generated on the surface of the SEI film, resulting in an increase in the internal resistance of the negative electrode.

[0064] As an optional embodiment of the present application, the flow rate is 0.01-1 L / min, and a typical but non-limiting flow rate is 0.01 L / min, 0.05 L / min, 0.1 L / min, 0.2 L / min, 0.4 L / min, 0.5 L / min, 0.6 L / min, 0.8 L / min or 1 L / min, and a range between any two values.

[0065] As an optional embodiment of the present application, the voltage window is 2.0 V-0.005 V; and a typical but non-limiting voltage window is 2.0 V, 1.5 V, 1.0 V, 0.5 V, 0.2 V, 0.1 V, 0.01 V or 0.005 V, and a range between any two values.

[0066] As an optional embodiment of the present application, the current density is 1 / 600-1 / 10C. Typical but non-limiting current densities are 1 / 600C, 1 / 500C, 1 / 400C, 1 / 300C, 1 / 200C, 1 / 100C, 1 / 50C, 1 / 20C, 1 / 10C or a numerical range between any two values.

[0067] By further limiting the voltage window and the current density, the degree and rate of pre-lithiation can be accurately controlled, and the structure of the artificial SEI film can be precisely regulated.

[0068] As an optional embodiment of the present application, before the charge-discharge treatment, a step of stirring and heating treatment of the mixed solution placed in an inert atmosphere is further included.

[0069] Stirring can make the electrochemical reaction more uniform. As an optional embodiment of the present application, the stirring speed is 500-2000 rpm / min. Typical but non-limiting stirring speeds are 500 rpm / min, 600 rpm / min, 800 rpm / min, 1000 rpm / min, 1200 rpm / min, 1500 rpm / min, 1600 rpm / min, 1800 rpm / min or 2000 rpm / min and a numerical range between any two values.

[0070] Heating treatment can make the electrolyte have low viscosity and good flowability, and the artificial SEI film formed has high density and good consistency. As an optional embodiment of the present application, the heating treatment temperature is 25-50°C, preferably 30-40°C, and more preferably 35°C. Typical but non-limiting heating treatment temperatures are 25°C, 30°C, 35°C, 40°C, 45°C or 50°C and a numerical range between any two values.

[0071] As an optional embodiment of the present application, the solvent used for washing includes any one or a combination of at least two of pure water, ethanol or dimethyl carbonate. The above-mentioned solvents are used for washing to facilitate the recycling of the electrolyte.

[0072] As an optional embodiment of the present application, the drying temperature is -50-80°C, and the drying time is 10-20h. Typical but non-limiting drying temperatures are -50°C, -40°C, -30°C, -20°C, -10°C, 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C.

[0073] According to a third aspect of the present application, a pre-lithiation electrochemical device for implementing the above-mentioned preparation method of the pre-lithiation negative electrode material is also provided, which comprises a pre-lithiation device and a circulation device in communication with the pre-lithiation device, as shown in Figure 1 specifically.

[0074] The prelithiation device comprises a lithium supplementing foil 1, a diaphragm 2, a clamping plate 3, a heating and stirring device 4 and a copper foil 5, the lithium supplementing foil 1 and the diaphragm 2 are stacked on the clamping plate 3, the diaphragm 2 is located between the lithium supplementing foil 1 and the clamping plate 3, the copper foil 5 is located on the side of the clamping plate 3 away from the lithium supplementing foil 1, the copper foil 5 and the clamping plate 3 form an internal circuit space 6 for storing a mixed solution formed by the silicon-based negative electrode material and the electrolyte, and the heating and stirring device 4 is further arranged in the internal circuit space 6 formed by the copper foil 5 and the clamping plate 3.

[0075] The circulating device comprises a vacuum tank 8 and a peristaltic pump 7, the vacuum tank 8 is communicated with the internal circuit space 6 of the prelithiation device through a pipeline, and the peristaltic pump 7 is arranged on the pipeline.

[0076] In the present application, the prelithiation device is mainly used for prelithiation treatment of the mixed solution formed by the silicon-based negative electrode material and the electrolyte. The vacuum tank in the circulating device is mainly used for preparation of the mixed solution, and the peristaltic pump 7 mainly provides circulating power for the mixed solution. After the prelithiation device is communicated with the circulating device, an internal space formed thereby can realize circulating flow of the mixed solution.

[0077] The specific process steps of the above prelithiation electrochemical device are as follows: the solvent, lithium salt and fluorine-containing additive are added into the vacuum tank, and after being stirred and mixed uniformly, an electrolyte is formed, then the silicon-based negative electrode material is added into the electrolyte and mixed uniformly to form a mixed solution formed by the silicon-based negative electrode material and the electrolyte. After inert gas is introduced into the electrochemical device and the air in the internal space is removed, the peristaltic pump is started, and the flow rate and time are controlled to make the electrolyte circulate in the device and fully soak the device.

[0078] The internal stirring of the electrochemical device is started and heated, the flow rate is controlled by the peristaltic pump, and after the voltage window is set, the charging and discharging cycle is carried out at a certain current density until the prelithiation is completed, then the centrifuge is used for washing and drying to obtain the prelithiation negative electrode material.

[0079] The prelithiation electrochemical device has simple structure and easy operation, can be used for prelithiation process of other negative electrode materials, and can also be expanded for mass production, and has strong expandability.

[0080] The clamping plate mainly plays a role in fixing the diaphragm and forming an internal circuit space with the copper foil, and since it needs to be in contact with the electrolyte, the material used cannot react with the electrolyte. As an optional embodiment of the present application, the clamping plate is a polytetrafluoroethylene clamping plate.

[0081] As an optional embodiment of the present application, a stirring device is arranged in the vacuum tank.

[0082] As an optional embodiment of the present application, the lithium supplementing foil comprises a lithium foil.

[0083] According to a fourth aspect of the present application, there is also provided a lithium ion battery comprising the pre-lithiated anode material described above.

[0084] In view of the advantages of the pre-lithiated anode material described above, the lithium ion battery comprising the same has good high-temperature storage performance and cycle performance.

[0085] According to a fifth aspect of the present application, there is also provided the use of the pre-lithiated anode material, the preparation method of the pre-lithiated anode material or the pre-lithiated electrochemical device in the field of lithium ion batteries.

[0086] The pre-lithiated anode material described above can be directly and individually used as an anode material to make an anode slurry, an anode sheet, and form a lithium ion battery, or can be compounded with other anode materials to make an anode slurry, an anode sheet, and form a lithium ion battery.

[0087] In view of the advantages of the pre-lithiated anode material, the preparation method of the pre-lithiated anode material or the pre-lithiated electrochemical device, it has good application prospects in the field of lithium ion battery production.

[0088] The present application will be further described in detail below in conjunction with specific examples and comparative examples.

[0089] Example 1

[0090] The present example provides a pre-lithiated anode material, which comprises a silicon-based anode material and an artificial SEI film coated on the surface of the silicon-based anode material.

[0091] The electrolyte used to form the artificial SEI film comprises a solvent, a lithium salt and a fluorine-containing additive, the solvent is 1,3-dioxolane, the lithium salt is lithium bisfluorosulfonylimide and lithium nitrate, and the fluorine-containing additive is heptafluoropropyl 1,2,2,2-tetrafluoroether. The mass ratio of 1,3-dioxolane, lithium bisfluorosulfonylimide, lithium nitrate and heptafluoropropyl 1,2,2,2-tetrafluoroether is 79:10:1:10, based on 100% of the mass of the electrolyte.

[0092] The silicon-based anode material is SiO, and the mass ratio of the electrolyte to the silicon-based anode material is 50:50.

[0093] The main components of the artificial SEI film are Li2CO3 and LiF, and the thickness of the artificial SEI film is 80-100 nm.

[0094] The preparation method of the pre-lithiated anode material of the present example comprises the following steps:

[0095] (a) at room temperature, the solvent, lithium salt and fluorine-containing additive are added into a vacuum tank in a mass ratio of 1,3-dioxolane: lithium bisfluorosulfonylimide: lithium nitrate: heptafluoropropyl 1,2,2,2-tetrafluoroethoxy ether = 79:10:1:10 to form an electrolyte by stirring, a silicon-based negative electrode material is added according to a mass ratio of the silicon-based negative electrode material to the electrolyte of 50:50, and the mixture is stirred at 1000 rpm / min for 2h until it is uniformly dispersed to obtain a mixed solution of the silicon-based negative electrode material and the electrolyte;

[0096] (b) argon is introduced into the electrochemical device for 10min to remove air in the device, a peristaltic pump is started, the pump speed is controlled to 1L / min, the mixed solution of the silicon-based negative electrode material and the electrolyte is allowed to infiltrate the device for 10min, the device is heated and stirred to be warmed to 35℃, the stirring speed is 100rpm / min, the peristaltic pump speed is reduced to 0.1L / min, and the silicon-based negative electrode material is subjected to charge-discharge cycling 3 times at a voltage window of 2.0V-0.005V (vs. Li / Li+) at 1 / 400C (vs. the amount of the negative electrode added) to form an artificial SEI film on the surface of the silicon-based negative electrode material;

[0097] (c) the mixed solution after the charge-discharge treatment is subjected to centrifugal separation using a centrifuge, the separated solid material is washed with a solvent dimethyl carbonate, and then dried at 60℃ for 15h to obtain a pre-lithiated negative electrode material.

[0098] Example 2

[0099] The present embodiment provides a pre-lithiated negative electrode material, which comprises a silicon-based negative electrode material and an artificial SEI film coated on the surface of the silicon-based negative electrode material.

[0100] The electrolyte used for forming the artificial SEI film comprises a solvent, a lithium salt and a fluorine-containing additive, the solvent is 1,3-dioxolane, the lithium salt is lithium bisfluorosulfonylimide and lithium nitrate, and the fluorine-containing additive is heptafluoropropyl 1,2,2,2-tetrafluoroethoxy ether. The mass ratio of 1,3-dioxolane, lithium bisfluorosulfonylimide, lithium nitrate and heptafluoropropyl 1,2,2,2-tetrafluoroethoxy ether is 79:10:1:10, based on 100% of the mass of the electrolyte.

[0101] The silicon-based negative electrode material is SiO, and the mass ratio of the silicon-based negative electrode material to the electrolyte is 40:60.

[0102] The main components of the artificial SEI film are Li2CO3 and LiF, and the thickness of the artificial SEI film is 120-140nm.

[0103] The preparation method of the pre-lithiated negative electrode material of the present embodiment comprises the following steps:

[0104] (a) at room temperature, the solvent, lithium salt and fluorine-containing additive were added into a vacuum tank in a mass ratio of 1,3-dioxolane: lithium bisfluorosulfonylimide: lithium nitrate: heptafluoropropyl 1,2,2,2-tetrafluoroethoxy ether = 79:10:1:10 to form an electrolyte by stirring, and then the silicon-based negative electrode material was added in a mass ratio of 40:60 to the electrolyte, and the mixture was stirred at 2000 rpm / min for 1 h to form a mixed solution of the silicon-based negative electrode material and the electrolyte;

[0105] (b) the air in the electrochemical device was removed by argon for 10 min, the peristaltic pump was started, the pump speed was controlled to 1 L / min, the mixed solution of the silicon-based negative electrode material and the electrolyte was allowed to infiltrate the device for 10 min, the device was heated and stirred to a temperature of 45°C, the stirring rate was 100 rpm / min, the peristaltic pump speed was reduced to 0.5 L / min, and the silicon-based negative electrode material was subjected to charge-discharge cycling 3 times at a rate of 1 / 200 C (vs. the amount of negative electrode added) in a voltage window of 2.0 V-0.005 V (vs. Li / Li + ) to form an artificial SEI film on the surface of the silicon-based negative electrode material;

[0106] (c) the mixed solution after the charge-discharge treatment was centrifuged using a centrifuge, the separated solid material was washed with the solvent dimethyl carbonate, and then dried at 60°C for 15 h to obtain a pre-lithiated negative electrode material.

[0107] Example 3

[0108] The present embodiment provides a pre-lithiated negative electrode material, which comprises a silicon-based negative electrode material and an artificial SEI film coated on the surface of the silicon-based negative electrode material.

[0109] The electrolyte used to form the artificial SEI film comprises a solvent, a lithium salt and a fluorine-containing additive, the solvent is 1,3-dioxolane, the lithium salt is lithium bisfluorosulfonylimide and lithium nitrate, and the fluorine-containing additive is heptafluoropropyl 1,2,2,2-tetrafluoroethoxy ether. The mass ratio of 1,3-dioxolane, lithium bisfluorosulfonylimide, lithium nitrate and heptafluoropropyl 1,2,2,2-tetrafluoroethoxy ether is 79:10:1:10, based on 100% of the mass of the electrolyte.

[0110] The silicon-based negative electrode material is SiO, and the mass ratio of the silicon-based negative electrode material to the electrolyte is 60:40.

[0111] The main components of the artificial SEI film are Li2CO3 and LiF, and the thickness of the artificial SEI film is 50-70 nm.

[0112] The preparation method of the pre-lithiated negative electrode material of the present embodiment comprises the following steps:

[0113] (a) The solvent, lithium salt and fluorine-containing additive with a mass ratio of 1,3-dioxolane: lithium bisfluorosulfonylimide: lithium nitrate: heptafluoropropyl 1,2,2,2-tetrafluoroethylether = 79:10:1:10 were added into a vacuum tank at room temperature and stirred to form an electrolyte, a silicon-based negative electrode material was added according to a mass ratio of the silicon-based negative electrode material to the electrolyte of 60:40, and the mixture was stirred at 1000 rpm / min for 2 h until it was uniformly dispersed to obtain a mixed solution of the silicon-based negative electrode material and the electrolyte;

[0114] (b) The air in the electrochemical device was removed by argon for 10 min, a peristaltic pump was started, the pump speed was controlled to 1 L / min, the mixed solution of the silicon-based negative electrode material and the electrolyte was allowed to infiltrate the device for 10 min, the device was heated and stirred to be warmed to 25℃, the stirring speed was 100 rpm / min, the peristaltic pump speed was reduced to 0.1 L / min, and the silicon-based negative electrode material was subjected to charge-discharge cycling 3 times at a voltage window of 2.0 V-0.005 V (vs. Li / Li+) and a rate of 1 / 600 C (vs. the amount of the negative electrode added) to form an artificial SEI film on the surface of the silicon-based negative electrode material;

[0115] (c) The mixed solution after the charge-discharge treatment was subjected to centrifugal separation using a centrifuge, the separated solid material was washed with the solvent dimethyl carbonate, and then dried at 60℃ for 15 h to obtain a pre-lithiated negative electrode material.

[0116] Example 4

[0117] The present example provides a pre-lithiated negative electrode material and a preparation method thereof, wherein the mass ratio of 1,3-dioxolane, lithium bisfluorosulfonylimide, lithium nitrate and heptafluoropropyl 1,2,2,2-tetrafluoroethylether in the electrolyte is replaced by 84:10:1:5 instead of 79:10:1:10, and other conditions are the same as those in Example 1.

[0118] Example 5

[0119] The present example provides a pre-lithiated negative electrode material and a preparation method thereof, wherein the mass ratio of 1,3-dioxolane, lithium bisfluorosulfonylimide, lithium nitrate and heptafluoropropyl 1,2,2,2-tetrafluoroethylether in the electrolyte is replaced by 74:10:1:15 instead of 79:10:1:10, and other conditions are the same as those in Example 1.

[0120] Example 6

[0121] The present example provides a pre-lithiated negative electrode material and a preparation method thereof, wherein the type of lithium salt in the electrolyte is replaced by lithium hexafluorophosphate instead of lithium bisfluorosulfonylimide, and other conditions are the same as those in Example 5.

[0122] Example 7

[0123] The embodiment provides a pre-lithiated negative electrode material and a preparation method thereof, wherein, except that the solvent type in the electrolyte is replaced from 1,3-dioxolane to ethylene glycol dimethyl ether, other conditions are the same as those in embodiment 1.

[0124] Embodiment 8

[0125] The embodiment provides a pre-lithiated negative electrode material and a preparation method thereof, wherein, except that the number of charge and discharge cycles is replaced from 3 times to 5 times, other conditions are the same as those in embodiment 1.

[0126] Embodiment 9

[0127] The embodiment provides a pre-lithiated negative electrode material and a preparation method thereof, wherein, except that the mass ratio of 1,3-dioxolane, lithium bisfluorosulfonylimide, lithium nitrate and heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether in the electrolyte is replaced from 79:10:1:10 to 86:10:1:3, other conditions are the same as those in embodiment 1.

[0128] Embodiment 10

[0129] The embodiment provides a pre-lithiated negative electrode material and a preparation method thereof, wherein, except that the mass ratio of 1,3-dioxolane, lithium bisfluorosulfonylimide, lithium nitrate and heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether in the electrolyte is replaced from 79:10:1:10 to 70:10:1:19, other conditions are the same as those in embodiment 1.

[0130] Comparative example 1

[0131] The comparative example provides a pre-lithiated negative electrode material, wherein, except that the solvent type in the electrolyte is replaced from 1,3-dioxolane to ethylene carbonate, other conditions are the same as those in embodiment 1.

[0132] The preparation method of the pre-lithiated negative electrode material in the comparative example, wherein, except that the solvent type in the electrolyte in step (a) is replaced from 1,3-dioxolane to ethylene carbonate, other steps and process parameters are the same as those in embodiment 1.

[0133] Comparative example 2

[0134] The comparative example provides a pre-lithiated negative electrode material, wherein, except that the fluorine-containing additive type in the electrolyte is replaced from heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether to fluoroethylene carbonate, other conditions are the same as those in embodiment 1.

[0135] The preparation method of the pre-lithiated negative electrode material in the comparative example, wherein, except that the fluorine-containing additive type in the electrolyte in step (a) is replaced from heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether to fluoroethylene carbonate, other steps and process parameters are the same as those in embodiment 1.

[0136] Comparative example 3

[0137] The comparative example provides a pre-lithiated negative electrode material, except that the fluorine-containing additive species in the electrolyte is replaced by vinylene carbonate instead of heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, and other conditions are the same as in Example 1.

[0138] The preparation method of the pre-lithiated negative electrode material in the comparative example, except that the fluorine-containing additive species in the electrolyte in step (a) is replaced by vinylene carbonate instead of heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, other steps and process parameters are the same as in Example 1.

[0139] Comparative Example 4

[0140] The comparative example provides a pre-lithiated negative electrode material, except that the fluorine-containing additive species in the electrolyte is replaced by perfluoro-n-propyl vinyl ether instead of heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, and other conditions are the same as in Example 1.

[0141] The preparation method of the pre-lithiated negative electrode material in the comparative example, except that the fluorine-containing additive species in the electrolyte in step (a) is replaced by perfluoro-n-propyl vinyl ether instead of heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, other steps and process parameters are the same as in Example 1.

[0142] Comparative Example 5

[0143] The comparative example provides a pre-lithiated negative electrode material, except that the fluorine-containing additive species in the electrolyte is replaced by 3-trifluoromethyl tetrahydrofuran instead of heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, and other conditions are the same as in Example 1.

[0144] The preparation method of the pre-lithiated negative electrode material in the comparative example, except that the fluorine-containing additive species in the electrolyte in step (a) is replaced by 3-trifluoromethyl tetrahydrofuran instead of heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, other steps and process parameters are the same as in Example 1.

[0145] Comparative Example 6

[0146] The comparative example provides a preparation method of a pre-lithiated negative electrode material, comprising the following steps:

[0147] (a) At room temperature, the solvent, lithium salt and fluorine-containing additive are added into a vacuum tank in a mass ratio of 1,3-dioxolane: lithium bisfluorosulfonylimide: lithium nitrate: heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether = 79:10:1:10 to form an electrolyte, lithium pieces are added into the electrolyte in a mass ratio of 1:10, and a silicon-based negative electrode material is added in a mass ratio of 50:50 of the silicon-based negative electrode material to the electrolyte, and stirred at 1000 rpm for 2h to obtain a mixed solution of the silicon-based negative electrode material and the electrolyte;

[0148] (b) removing air in the electrochemical device by argon for 10 min, starting the peristaltic pump and controlling the pump speed to 1 L / min, so that the mixed solution of the silicon-based negative electrode material and the electrolyte infiltrates the device for 10 min, heating and stirring the device to 35°C, the stirring rate is 100 rpm / min, and the reaction is carried out for 30 min, so that the surface of the silicon-based negative electrode material is spontaneously pre-lithiated to form an artificial SEI film (i.e. without charge and discharge cycles), and a pre-lithiated mixed solution is obtained;

[0149] (c) centrifuging the pre-lithiated mixed solution using a centrifuge, washing the separated solid material with the solvent dimethyl carbonate, and then drying at 60°C for 15 h to obtain a pre-lithiated negative electrode material.

[0150] It should be noted that the pre-lithiation electrochemical device used in the above-mentioned preparation method of the pre-lithiated negative electrode material in Examples 1-10 and Comparative Examples 1-6 includes a pre-lithiation device and a circulation device in communication with the pre-lithiation device, as shown in Figure 1

[0151] The pre-lithiation device includes a lithium supplement foil 1 (lithium foil), a separator 2, a clamping plate 3, a heating and stirring device 4, and a copper foil 5. The lithium supplement foil 1 and the separator 2 are stacked on the clamping plate 3, and the separator 2 is located between the lithium supplement foil 1 and the clamping plate 3. The copper foil 5 is located on the side of the clamping plate 3 away from the lithium supplement foil 1, and the copper foil 5 and the clamping plate 3 (polytetrafluoroethylene clamping plate) form an internal circuit space 6 for storing the mixed solution of the silicon-based negative electrode material and the electrolyte. The heating and stirring device 4 is also arranged in the internal circuit space 6 formed by the copper foil 5 and the clamping plate 3.

[0152] The circulation device includes a vacuum tank 8 and a peristaltic pump 7. The vacuum tank 8 is in communication with the internal circuit space 6 of the pre-lithiation device through a pipeline, and the peristaltic pump 7 is arranged on the pipeline.

[0153] In order to compare the technical effects of the above-mentioned examples and comparative examples, the following experimental examples are provided.

[0154] Experimental Example 1

[0155] ​The pre-lithiated negative material in Examples 1-10 and Comparative Examples 1-6 was prepared into soft package 505060 lithium ion batteries using a soft package lamination process. The NCM811 positive electrode sheet, negative electrode sheet (mass ratio of negative electrode material: conductive agent: carboxymethyl cellulose sodium CMC: polyacrylic acid PAA was 96.0: 1.0: 1.2: 1.8, wherein the negative electrode material included graphite and the pre-lithiated negative electrode material, and the mass ratio of the pre-lithiated negative electrode material and the graphite was 10:90) and a polyethylene separator (for example, a PE+OBS separator) were laminated, assembled, baked to pass moisture, injected with electrolyte (solvents were ethylene carbonate EC, propylene carbonate PC, methyl ethyl carbonate EMC and dimethyl carbonate DMC, lithium salts were LiPF6 and LiFSI, and additives were vinylene carbonate VC, fluoroethylene carbonate FEC, vinyl sulfate DTD and 1,3-propane sulfonolide 1-3 PS), packaged after heat pressing formation and high temperature standing, and stored at room temperature after being divided and contained to obtain soft package 505060 finished batteries. The above batteries were subjected to electrochemical performance testing.

[0156] Discharge performance at different temperatures: constant current and constant voltage charging was performed at 25°C and 1C on an electrochemical workstation battery test system, the cutoff current was 0.05C, and discharge was performed at different temperatures (-20°C, 0°C, 25°C, 45°C) and 1C, and the charge and discharge voltage window was 2.75V-4.2V.

[0157] Storage performance: constant current and constant voltage charging was performed at 25°C and 1C on an electrochemical workstation battery test system until the voltage was 4.2V, then the lithium ion battery was placed in a constant temperature oven at 60°C, and stored for 30 days, then the capacity retention was calculated. The capacity retention = the discharge capacity after storage / the discharge capacity before storage.

[0158] At the same time, considering that the formation of the SEI film requires consumption of lithium ions, if the SEI film structure is unstable, it is more likely to decompose at high temperatures, and when recharged, lithium ions inside the battery will be consumed to regenerate the SEI film, and the consumed lithium ions will cause irreversible capacity of the battery, so the recovery rate was determined. The recovery rate = the average of the discharge capacity of the last 3 times of 5 standard cycles after storage / the discharge capacity before storage. The standard cycle is a charge and discharge cycle at 1C.

[0159] Cycle performance: the charge and discharge current density was 0.5C / 1C, and the charge and discharge voltage window was 2.75V-4.2V, which were tested at 25°C on an electrochemical workstation battery test system.

[0160] Table 1

[0161]

[0162] As can be seen from Examples 1-10 and Comparative Examples 1-6, the fluorine ether electrolyte additive heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether can form an artificial SEI film on the surface of the silicon-based negative electrode material, which has good contact with the electrolyte, small interface resistance, can accelerate the transmission rate of lithium ions at the electrode / electrolyte interface, and improve the discharge retention rate of the lithium battery at low temperature. At the same time, from the above retention rate and recovery rate data, it can be seen that the artificial SEI film formed on the surface of the silicon-based negative electrode material has stable chemical properties and good high temperature stability, avoids the occurrence of electrode / electrolyte interface side reactions during high temperature process, and improves the high temperature storage performance of the lithium battery. The SEI film rich in LiF adjusts the uniform deposition of the flux, optimizes the lithium storage structure of the pre-lithiated silicon-based negative electrode, avoids local over-lithiation leading to stress rupture of the silicon material, and effectively relieves the volume expansion of the silicon-based material by its flexibility and rigidity, thereby improving the cycle performance of the lithium battery. + The flux adjusts the uniform deposition of the flux, optimizes the lithium storage structure of the pre-lithiated silicon-based negative electrode, avoids local over-lithiation leading to stress rupture of the silicon material, and effectively relieves the volume expansion of the silicon-based material by its flexibility and rigidity, thereby improving the cycle performance of the lithium battery.

[0163] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application is within the scope of the claims of the present application.

Claims

1. A pre-lithiated anode material, characterized in that, The silicon-based negative electrode material and an artificial SEI film coated on the surface of the silicon-based negative electrode material; The electrolyte used to form the artificial SEI film comprises a lithium salt, a fluorine-containing additive and a solvent, the fluorine-containing additive comprises heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, and the solvent comprises an ether organic solvent; The method for forming the artificial SEI film comprises: placing a mixed solution formed by the silicon-based negative electrode material and the electrolyte in an inert atmosphere, and performing charging and discharging treatment on the mixed solution under a certain flow rate, voltage window and current density, so that the artificial SEI film is formed on the surface of the silicon-based negative electrode material; The mixed solution formed by the silicon-based negative electrode material and the electrolyte is subjected to pre-lithiation treatment by using a pre-lithiation device, the mixed solution is prepared by using a vacuum tank in a circulation device, a peristaltic pump in the circulation device provides circulation power for the mixed solution, and an internal space formed after the pre-lithiation device and the circulation device are communicated can realize circulation flow of the mixed solution; The pre-lithiation device comprises a lithium supplement foil, a diaphragm, a clamping plate, a heating and stirring device and a copper foil, the lithium supplement foil and the diaphragm are stacked on the clamping plate, the diaphragm is located between the lithium supplement foil and the clamping plate, the copper foil is located on the side of the clamping plate away from the lithium supplement foil, the copper foil and the clamping plate form an internal circuit space for storing the mixed solution formed by the silicon-based negative electrode material and the electrolyte, and the heating and stirring device is further arranged in the internal circuit space formed by the copper foil and the clamping plate; The circulation device comprises a vacuum tank and a peristaltic pump, the vacuum tank is communicated with the internal circuit space of the pre-lithiation device through a pipeline, and the peristaltic pump is arranged on the pipeline.

2. The prelithiated anode material of claim 1, wherein, The mass fraction of the fluorine-containing additive in the electrolyte is 5-15% based on 100% of the mass of the electrolyte; And / or, the mass ratio of the electrolyte to the silicon-based negative electrode material is (40-60):(40-60). 3.The pre-lithiated anode material of claim 1, wherein, The lithium salt comprises at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bisfluorosulfonylimide or lithium nitrate; And / or, the solvent comprises at least one of 1,3-dioxolane, 1,2-dimethoxyethane, ethylene glycol dimethyl ether, diethyl ether or 2,2-dimethoxy-4-(trifluoromethyl)-1,3-dioxolane; And / or, the electrolyte comprises the following components in the following mass fractions based on 100% of the mass fraction of the electrolyte: lithium salt 5-15%, fluorine-containing additive 5-15% and solvent 70-90%. 4.The pre-lithiated anode material of claim 1, wherein, The silicon-based negative electrode material comprises at least one of pure silicon negative electrode material, silicon-carbon negative electrode material or silicon-oxygen negative electrode material.

5. The prelithiated anode material of any one of claims 1-4, wherein, The main components of the artificial SEI film comprise Li2CO3 and LiF; And / or, the thickness of the artificial SEI film is 50-300 nm.

6. The method for producing a prelithiated negative material according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: The mixed solution formed by the silicon-based negative electrode material and the electrolyte is placed in an inert atmosphere, and charging and discharging treatment is performed on the mixed solution under a certain flow rate, voltage window and current density, so that the artificial SEI film is formed on the surface of the silicon-based negative electrode material; The mixed solution after the charging and discharging treatment is subjected to centrifugal separation, the solid material obtained by the separation is washed and vacuum dried, and a pre-lithiation negative electrode material is obtained.

7. The method of preparing a prelithiated negative material according to claim 6, wherein The inert atmosphere comprises helium and / or argon. And / or, the flow rate is 0.01-1 L / min; And / or, the voltage window is 2.0-0.005 V; And / or, the current density is 1 / 600-1 / 10 C; And / or, before the charge-discharge treatment, the method further comprises a step of stirring and heating the mixed solution in an inert atmosphere, the stirring speed is 500-2000 rpm / min, and the heating temperature is 25-50℃; And / or, during the charge-discharge treatment, the number of charge-discharge cycles is 1-5 times; And / or, the solvent used for washing comprises at least one of pure water, ethanol or dimethyl carbonate; And / or, the drying temperature is -50~80℃, and the drying time is 10-20h.

8. A prelithiation electrochemical device for carrying out the method of preparing the prelithiated anode material of claim 6 or 7, characterized in that, The pre-lithiation device and a circulation device in communication with the pre-lithiation device are included. The pre-lithiation device includes a lithium supplement foil, a separator, a clamping plate, a heating and stirring device, and a copper foil. The lithium supplement foil and the separator are stacked on the clamping plate, the separator is between the lithium supplement foil and the clamping plate, the copper foil is on the side of the clamping plate away from the lithium supplement foil, the copper foil and the clamping plate form an internal circuit space for storing a mixed solution of a silicon-based negative electrode material and an electrolyte, and the heating and stirring device is arranged in the internal circuit space formed by the copper foil and the clamping plate. The circulation device includes a vacuum tank and a peristaltic pump. The vacuum tank is in communication with the internal circuit space of the pre-lithiation device through a pipeline, and the peristaltic pump is arranged on the pipeline.

9. The prelithiated electrochemical device of claim 8, wherein, The clamping plate is a polytetrafluoroethylene clamping plate. And / or, the vacuum tank is provided with a stirring device.

10. The pre-lithiation negative electrode material of any one of claims 1-5, the preparation method of the pre-lithiation negative electrode material of claim 6 or 7, or the application of the pre-lithiation electrochemical device of claim 8 or 9 in the field of lithium ion batteries.

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