A silicon-based negative electrode, its preparation method, and its application

Abstract

This invention provides a silicon-based anode sheet, its preparation method, and its applications, relating to the field of lithium-ion battery technology. Specifically, it includes a current collector layer, an electrolyte layer, and a silicon substrate connected in sequence; wherein the electrolyte layer comprises an ion-conducting agent and a lithium salt, and is composed of several filaments. The silicon-based anode sheet of this invention, while ensuring high specific capacity, can suppress the volume expansion of silicon particles, prevent electrode shedding and powder loss, and improve the cycle performance of the electrode. When preparing all-solid-state batteries using the silicon-based anode sheet of this invention, it can effectively improve the specific capacity of the anode sheet and the cycle stability of the battery, which is beneficial for promoting the improvement of the energy density of sulfide all-solid-state battery cells and for facilitating the early application of sulfide all-solid-state batteries in various industries, showing broad application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a silicon-based negative electrode sheet and a preparation method and application thereof. BACKGROUND

[0002] Solid-state batteries replace flammable organic liquid electrolytes with non-flammable solid-state electrolytes, greatly improving the safety of battery systems and achieving synchronous improvement of energy density. Among various new battery systems, solid-state batteries are the closest next-generation technology to industrialization, which has become the consensus of the industry and the scientific community. Among them, sulfide electrolytes have relatively high lithium ion conductivity, mainly including thio-LISICON, Li 10 GeP2S 12 , Li 10 SnP2S 12 , Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, etc. The room temperature ionic conductivity of sulfide electrolyte can reach 10 -3 ~ 10 -2 S / cm, close to or even exceeding organic electrolyte, and has the characteristics of high thermal stability, good safety performance, wide electrochemical stability window (up to 5V or more), etc. It has outstanding advantages in high-power and high-low temperature solid-state batteries, and has broad prospects in the research and development of high-safety and high-energy-density batteries.

[0003] When using sulfide solid electrolyte to prepare a full-solid-state battery system, in order to ensure the energy density advantage, the negative electrode of the full-solid-state battery will usually use a silicon-containing negative electrode or a lithium metal negative electrode. At present, the application cost and technical difficulty of lithium metal negative electrode are still very high, while silicon-based negative electrode materials have very high mass specific capacity and volume specific capacity, and also have the advantages of low cost, non-toxic and non-polluting, low lithium intercalation platform, etc. Therefore, the development of silicon-based negative electrode is one of the most effective methods to improve the energy density of lithium ion batteries.

[0004] The silicon-based negative electrode sheet is generally composed of silicon material, conductive agent, graphite material and nano metal particles; the silicon material has low conductivity, as an active material, the volume change of silicon reaches 300% when lithium is inserted and extracted in the charging and discharging cycle, the cycle life is poor, the volume expansion will cause the crushing of silicon particles, the repeated cracking of the electrode sheet in the charging and discharging process will cause the separation of the electrode sheet coating from the current collector, and then the powdering and attenuation, and finally the failure of the lithium ion battery due to the large capacity reduction. The current process generally adds graphite material or other metal particles with small expansion coefficient in the negative electrode sheet to alleviate the volume effect of the silicon material, although the addition of graphite can to some extent inhibit the increase of interface impedance and the powdering of the electrode sheet caused by the volume change of the silicon material in the charging and discharging process, but due to the fact that the specific capacity of the graphite material is much lower than that of the silicon material, a small amount of addition has no obvious effect on inhibiting the cycle cracking and powdering of the silicon negative electrode sheet, and too much addition not only affects the energy density of the battery, but also increases the thickness of the electrode sheet, resulting in the length of the lithium ion transmission path, which will make the rate performance of the battery worse; at the same time, the alloy material also has the defects of large volume change and low mass advantage.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The first object of the present application is to provide a silicon-based negative electrode sheet which can inhibit the volume expansion of silicon particles, prevent the falling off and powdering of the electrode sheet, and improve the cycle performance of the electrode sheet under the premise of ensuring high specific capacity of the electrode sheet.

[0007] The second object of the present application is to provide a preparation method of the silicon-based negative electrode sheet, which is simple and easy to operate and suitable for batch production.

[0008] The third object of the present application is to provide the application of the silicon-based negative electrode sheet; when a full solid structure battery is prepared by using the silicon-based negative electrode sheet, the specific capacity and cycle stability of the silicon-based full solid negative electrode sheet can be effectively improved, which is beneficial to promote the energy density of the sulfide full solid battery, so as to promote the early application of the sulfide full solid battery in various industries and promote the development of the lithium battery industry.

[0009] In order to achieve the above objects of the present application, the following technical scheme is adopted: a silicon-based negative electrode sheet, comprising a current collector layer, an electrolyte layer and a silicon-based layer connected in sequence; wherein the electrolyte layer comprises an ion-conducting agent and a lithium salt, and the electrolyte layer is composed of a plurality of filaments.

[0010] Preferably, in the electrolyte layer, the filaments are distributed in parallel or in a mesh pattern;

[0011] More preferably, the diameter of the filaments is ≤200μm;

[0012] More preferably, when the filaments are in parallel distribution, the interval of the filaments is 1mm-5mm; when the filaments are in net format distribution, the side length of the net is 1mm-5mm.

[0013] Preferably, the ion conductor comprises at least one of polyethylene oxide, polyethylene glycol dimethacrylate, polyacrylonitrile, polycarbonate, polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene or polyvinylpyrrolidone.

[0014] Preferably, the lithium salt comprises at least one of lithium bistrifluoromethylsulfonylimide, lithium trifluoromethylsulfonylimide, lithium chloride, lithium tetrafluoroborate, lithium tetrafluoroborate, lithium hexafluorophosphate or lithium perchlorate.

[0015] Preferably, the mass ratio of the ion conductor and the lithium salt is (3-4):1.

[0016] Preferably, the silicon-based layer comprises a silicon material, a conductive agent and a binder; wherein the silicon material comprises at least one of single-crystal nanosilicon, silicon monoxide, silicon-carbon material, pre-lithiated silicon-oxygen material or pre-magnesiumated silicon-oxygen material; the conductive agent comprises at least one of SP, AB, CNT, VGCF; the binder comprises at least one of conductive carbon black (SP, AB), carbon nanotube (CNT), nano-carbon fiber (VGCF), conductive graphite or graphene.

[0017] More preferably, the silicon-based layer comprises, in mass parts, 80-99 parts of the silicon material, 0.5-2 parts of the conductive agent and 0.5-3 parts of the binder.

[0018] More preferably, the silicon-based layer further comprises a graphite material; further preferably, the silicon-based layer further comprises 0.1-25 parts of the graphite material, in mass parts.

[0019] The preparation method of the silicon-based negative electrode sheet comprises the following steps: step one, mixing an ion conductor, a lithium salt and a first solvent to obtain an electrolyte layer slurry; performing filament drawing treatment on the electrolyte layer slurry and laying it on the surface of a current collector to obtain a first intermediate; step two, performing drying treatment on the first intermediate to obtain a second intermediate; step three, mixing a silicon material, a conductive agent, a binder and a second solvent to obtain a silicon-based layer slurry; coating the silicon-based layer slurry on the surface of the electrolyte layer of the second intermediate to obtain a negative electrode precursor; step four, performing second drying treatment and rolling on the negative electrode precursor to obtain a silicon-based negative electrode sheet.

[0020] Preferably, in step one, the first solvent comprises at least one of methyl formamide, acetonitrile, cyclohexanone, heptane, N-methyl pyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide or N,N-dimethylacetamide.

[0021] More preferably, the mass concentration of the first solvent in the electrolyte layer slurry is 90% to 97%.

[0022] Preferably, in step two, the temperature of the drying treatment is 30°C to 80°C, and the time of the drying treatment is 3 days to 10 days.

[0023] Preferably, in step three, the second solvent comprises at least one of water, dichloromethane, tetrahydrofuran, n-hexane, n-heptane, toluene, 2,4-dimethyl-3-pentanone, monochlorobenzene, dimethylbenzene, anisole, cyclohexanone, 1,3,5-trimethylbenzene, n-decane, or methylformamide.

[0024] More preferably, the solid content of the silicon-based layer slurry is 15% to 75%.

[0025] Preferably, in step four, the temperature of the second drying treatment is 50°C to 90°C, and the time of the second drying treatment is 24h to 72h.

[0026] Preferably, in step four, the temperature of the rolling is 40°C to 65°C.

[0027] The use of the silicon-based negative electrode sheet in the field of lithium ion batteries includes, but is not limited to, a lithium ion battery prepared based on the silicon-based negative electrode sheet, or an electric element or electric appliance comprising the lithium ion battery.

[0028] Preferably, the lithium ion battery is a full solid-state structure battery prepared by using a sulfide solid electrolyte.

[0029] Compared with the prior art, the present application has the following beneficial effects: by using polymer electrolyte filaments with micron-level diameters, the present application builds a filamentous parallel or grid structure on the current collector, which has multiple effects: first, the electrolyte filaments (i.e., the electrolyte layer and the filaments) themselves not only have ion conductivity, but also improve the lithium ion transfer capacity in the silicon-based layer, reduce polarization, and improve the rate performance; second, the adhesion of the electrolyte filaments can also reduce the use of the binder of the silicon active layer slurry, and the barrier-like structure formed by the electrolyte filaments on the current collector is conducive to the combination of the silicon-based layer on the foil; third, the electrolyte filaments play a role of a skeleton structure in the negative electrode, providing strength support for the silicon-based layer, and their soft and elastic properties provide a compression space for the expansion of silicon during the charging process, inhibit the extrusion and breakage between silicon particles or agglomerates, and reduce the probability of pulverization and side reactions, while the silicon particles shrink during the discharging process, and the polymer rebounds to prevent the generation of gaps between the particles, ensuring that the silicon-based layer does not crack and is conducive to the integrity of the silicon-based layer, which also significantly improves the cycle stability of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the accompanying drawings required to be used in the description of the specific embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0031] Figure 1 Process flow diagram of Example 1 of the present application;

[0032] Figure 2 Cycle performance comparison chart of Example 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be described clearly and completely in the following description in combination with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, which are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, which are conventional products that can be purchased on the market.

[0034] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "step one", "step two", "step three" and the like are only for description purposes and cannot be understood as indicating or implying relative importance.

[0035] The present application is implemented by the following specific embodiments: a silicon-based negative electrode sheet, comprising a current collector layer, an electrolyte layer and a silicon-based layer connected in sequence; wherein the electrolyte layer comprises an ion-conducting agent and a lithium salt, and the electrolyte layer is composed of a plurality of filaments.

[0036] As a preferred embodiment, the silicon-based negative electrode sheet is composed of only a current collector layer, an electrolyte layer and a silicon-based layer, i.e. a three-layer structure.

[0037] As a preferred embodiment, the current collector layer includes but is not limited to carbon-coated copper foil, copper foil, carbon-coated stainless steel foil, steel foil or other alloy foil.

[0038] As a preferred embodiment, in the electrolyte layer, the filaments are distributed in parallel or in a mesh pattern; for the parallel distribution, the filaments can be transversely parallel, longitudinally parallel, or obliquely parallel relative to the current collector, preferably maintaining a vertical spacing of the parallel filaments of 1-5 mm; for the mesh pattern distribution, the mesh formed by the filaments can be any quadrilateral, preferably maintaining any one side length of the quadrilateral within 1-5 mm.

[0039] As a preferred embodiment, the mass ratio of the ion-conducting agent to the lithium salt includes but is not limited to 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1.

[0040] As a preferred embodiment, the silicon-based layer includes a silicon material, a conductive agent, and a bonding agent; in terms of mass fraction, the silicon material includes but is not limited to 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 (unit: parts), the conductive agent includes but is not limited to 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, 2 (unit: parts), and the bonding agent includes but is not limited to 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3 (unit: parts).

[0041] As a more preferred embodiment, the molecular weight of the bonding agent is 200-1000 thousand, including but not limited to 20, 30, 40, 50, 60, 70, 80, 90, 100 (unit: thousand).

[0042] As a more preferred embodiment, the silicon-based layer further includes a graphite material, such as artificial graphite, etc., which can be mixed with different models and particle sizes; in terms of mass fraction, the amount of the graphite material includes but is not limited to 0.1, 0.2, 0.5, 1, 2, 5, 10, 15, 20, 25 (unit: parts).

[0043] The preparation method of the silicon-based negative electrode sheet comprises the following steps: Step 1, mixing an ion-conducting agent, a lithium salt and a first solvent to obtain an electrolyte layer slurry; performing a wire drawing treatment on the electrolyte layer slurry and laying the electrolyte layer slurry on the surface of a current collector to obtain a first intermediate body; Step 2, performing an oven drying treatment on the first intermediate body to obtain a second intermediate body; Step 3, mixing a silicon material, a conductive agent, a binder and a second solvent to obtain a silicon-based layer slurry; coating the silicon-based layer slurry on the surface of the electrolyte layer of the second intermediate body to obtain a negative electrode precursor; and Step 4, performing a second oven drying treatment and roller pressing on the negative electrode precursor to obtain a silicon-based negative electrode sheet.

[0044] As a preferred embodiment, in Step 1, before the wire drawing treatment, the electrolyte layer slurry is pre-dried to a state that can be drawn into a micron level; and the pre-drying degree varies according to the molecular weight and solid content of the polymer, which is not specifically limited in the present application, and the time and temperature of the pre-drying can be determined by the person skilled in the art according to the requirements of the wire drawing treatment.

[0045] As a preferred embodiment, in Step 2, the temperature of the oven drying treatment includes but is not limited to 30, 40, 50, 60, 70, 80 (unit: ℃), and the time of the oven drying treatment includes but is not limited to 3, 4, 5, 6, 7, 8, 9, 10 (unit: days).

[0046] As a preferred embodiment, in Step 4, the temperature of the second oven drying treatment includes but is not limited to 50, 60, 70, 80, 90 (unit: ℃), and the time of the second oven drying treatment includes but is not limited to 24, 28, 30, 35, 40, 45, 50, 55, 60, 65, 70, 72 (unit: h).

[0047] As a preferred embodiment, in Step 4, the roller pressing is hot roller pressing, and the temperature of the hot roller includes but is not limited to 40, 45, 50, 55, 60, 65 (unit: ℃).

[0048] Example 1

[0049] (1) Polyethylene oxide (molecular weight 400w) and lithium bis-trifluoromethylsulfonylimide were mixed, dissolved in acetonitrile, and a mixed slurry with a mass concentration of 5% was obtained, wherein the mass ratio of polyethylene oxide and lithium bis-trifluoromethylsulfonylimide was 3:1.

[0050] (2) The mixed slurry obtained in Step (1) was coated and dried to a state that can be drawn into a wire, and a square grid structure was formed on a carbon-coated copper foil with a wire drawing diameter of 200 μm and a wire drawing interval of 2 mm. After drying at 60 ℃ for 7 days, the polymer filament structure was shrunk to a level of 30 μm.

[0051] (3) Respectively measure monocrystalline nanometer silicon, graphite, CNT and PAA (mass ratio of the four is 80%:17%:1.5%:1.5%), then dissolve PAA using ultrapure water, mix and homogenate the glue liquid and other component materials, coat on the intermediate prepared in step (2) (coat on the side containing the wire), dry and then roll, until the silicon-carbon layer thickness is 40 μm.

[0052] Figure 1 The preparation process flow chart of the present embodiment is given.

[0053] Example 2

[0054] The same as example 1, the only difference is that in step (1), polyethylene oxide is replaced by polyvinylidene fluoride-hexafluoropropylene (molecular weight 40w), and lithium bis-trifluoromethyl sulfonimide is replaced by lithium chloride.

[0055] Example 3

[0056] The same as example 1, the only difference is that in step (1), polyethylene oxide is replaced by polymethyl methacrylate (molecular weight 300w), and lithium bis-trifluoromethyl sulfonimide is replaced by lithium hexafluorophosphate.

[0057] Example 4

[0058] The same as example 1, the only difference is that in step (1), the mass ratio 3:1 is replaced by 4:1.

[0059] Example 5

[0060] The same as example 1, the only difference is that in step (2), the wire drawing treatment is replaced by: forming a square grid structure with a wire diameter of 200 μm and a wire spacing of 5 mm.

[0061] Example 6

[0062] The same as example 1, the only difference is that in step (2), a transverse parallel structure is formed with a wire diameter of 150 μm and a wire spacing of 3 mm.

[0063] Example 7

[0064] The same as example 1, the only difference is that in step (2), a longitudinal parallel structure is formed with a wire diameter of 150 μm and a wire spacing of 1 mm.

[0065] Example 8

[0066] The same as example 1, the only difference is that in step (3), monocrystalline nanometer silicon, CNT and PAA are replaced in turn by silicon monoxide, AB and SBR.

[0067] Comparative Example 1

[0068] The same as Example 1, except that steps (1) and (2) are omitted, and the slurry prepared in step (3) is directly coated on the carbon-coated copper foil to a coating thickness of 40 μm.

[0069] Comparative Example 2

[0070] (1) Polyethylene oxide (molecular weight 400 w) and lithium bis-trifluoromethylsulfonylimide were mixed and dissolved in acetonitrile to obtain a mixed slurry with a mass concentration of 5%, wherein the mass ratio of polyethylene oxide and lithium bis-trifluoromethylsulfonylimide was 3:1; the mixed slurry was coated on a carbon-coated copper foil, dried at 60°C for 7 days, and the thickness after drying and coating was 20 μm;

[0071] (2) Single-crystal nanosilicon, graphite, CNT and PAA (mass ratio of the four was 80%:17%:1.5%:1.5%) were weighed respectively, then PAA was dissolved in ultrapure water, and the glue solution and other component materials were stirred and mixed uniformly, and then coated on the intermediate prepared in step (1) (coated on the side containing the coating), and dried and rolled to a silicon-carbon layer thickness of 40 μm.

[0072] Comparative Example 3

[0073] The polymer slurry of step (1) in Example 1 was mixed with the silicon negative electrode slurry in step (3) at the same mass content, and then coated on the carbon-coated copper foil, with the same surface capacity as Example 1.

[0074] Test Example:

[0075] The negative electrode sheets prepared in the above examples and comparative examples were assembled together with positive electrode sheets (active material was NCM811), and a sulfide electrolyte (Li6PS5Cl) electrolyte film to prepare a 1.5 Ah soft package battery, which was tested under the condition of 30°C, with a pressure of 0.5 MPa, and a rate of 0.5C for charging and discharging, and the battery capacity retention rate at 150 cycles was compared. Figure 2 The cycle performance comparison chart of Example 1 and Comparative Example 1 is given.

[0076] Table 1

[0077] Capacity retention at 150 cycles Example 1 89.6％ Example 2 82.2％ Example 3 85.8％ Example 4 76.7％ Example 5 81.5％ Example 6 80.8％ Example 7 77.9％ Example 8 91.6％ Comparative Example 1 49.3％ Comparative Example 2 36.36％ Comparative Example 3 60.1％

[0078] Although the present application has been described and illustrated with a certain degree of particularity, it is understood that the present application has been made by way of examples only and that numerous changes in the details of execution can be made by those skilled in the art without departing from the spirit and scope of the application. It is therefore intended to cover in the appended claims all such changes and modifications that come within the scope of the application.

Claims

1. A silicon-based negative electrode sheet, characterized by, The application relates to a silicon-based negative electrode sheet, which comprises a current collector layer, an electrolyte layer and a silicon-based layer connected in sequence; the electrolyte layer is composed of ion-conducting agents and lithium salts, and the electrolyte layer is composed of a plurality of filaments; the silicon-based layer comprises a silicon material, a conductive agent and a bonding agent. In the electrolyte layer, the filaments are distributed in parallel or in a mesh pattern. The diameter of the filaments is less than or equal to 200 microns. When the filaments are distributed in parallel, the interval of the filaments is 1-5 mm; when the filaments are distributed in a mesh pattern, the side length of the mesh is 1-5 mm. The ion-conducting agent comprises at least one of polyethylene oxide, polyethylene glycol dimethyl acrylate, polycarbonate, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene or polyvinylpyrrolidone.

2. The silicon-based negative electrode sheet according to claim 1, characterized by, The lithium salt comprises at least one of lithium bistrifluoromethylsulfonylimide, lithium trifluoromethylsulfonylimide, lithium chloride, lithium tetrafluoroborate, lithium tetrafluoroborate, lithium hexafluorophosphate or lithium perchlorate.

3. The silicon-based negative electrode sheet according to claim 1, characterized by The mass ratio of the ion-conducting agent to the lithium salt is (3-4):

1.

4. The silicon-based negative electrode sheet according to claim 1, characterized by, The silicon material comprises at least one of single-crystal nanosilicon, silicon monoxide, silicon-carbon material, pre-lithiated silicon-oxygen material or pre-magnesiumated silicon-oxygen material. The conductive agent comprises at least one of conductive carbon black, carbon nanotube, nanometer carbon fiber, conductive graphite or graphene. The bonding agent comprises at least one of PAA, Li-PAA, NBR, HNBR, SBR, SBS, SEBS, PTEF or PEO.

5. The silicon-based negative electrode sheet according to claim 1, wherein In terms of mass fraction, the silicon-based layer comprises 80-99 parts of the silicon material, 0.5-2 parts of the conductive agent and 0.5-3 parts of the bonding agent.

6. The silicon-based negative electrode sheet according to claim 1, wherein The silicon-based layer further comprises a graphite material. In terms of mass fraction, the silicon-based layer further comprises 0.1-25 parts of the graphite material.

7. The method of producing a silicon-based negative electrode sheet according to any one of claims 1 to 6, wherein The application further discloses a preparation method of the silicon-based negative electrode sheet. Step one: the ion-conducting agent, the lithium salt and a first solvent are fully mixed to obtain electrolyte layer slurry; the electrolyte layer slurry is subjected to wire drawing treatment and laid on the surface of a current collector to obtain a first intermediate body; Step two: the first intermediate body is subjected to drying treatment to obtain a second intermediate body; Step three: a silicon material, a conductive agent, a bonding agent and a second solvent are fully mixed to obtain silicon-based layer slurry; the silicon-based layer slurry is coated on the surface of the electrolyte layer of the second intermediate body to obtain a negative electrode precursor; Step four: after the negative electrode precursor is subjected to second drying treatment and rolling, a silicon-based negative electrode sheet is obtained.

8. The method for preparing a silicon-based negative electrode according to claim 7, characterized in that, In step one, the first solvent comprises at least one of methyl formamide, acetonitrile, cyclohexanone, heptane, N-methyl pyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide or N,N-dimethylacetamide; In the electrolyte layer slurry, the mass concentration of the first solvent is 90%-97%.

9. The method for preparing a silicon-based negative electrode according to claim 7, characterized in that, In step two, the temperature of the drying treatment is 30-80 DEG C, and the time of the drying treatment is 3-10 days.

10. The method of claim 7, wherein the silicon-based negative electrode sheet is prepared by the steps of: In step three, the second solvent comprises at least one of water, dichloromethane, tetrahydrofuran, n-hexane, n-heptane, toluene, 2,4-dimethyl-3-pentanone, monochlorobenzene, xylene, anisole, cyclohexanone, 1,3,5-trimethylbenzene, n-decane or methyl formamide; ​ The solid content of the silicon-based layer slurry is 15% to 75%.

11. The method for preparing a silicon-based negative electrode according to claim 7, characterized in that, In step four, the temperature of the second drying treatment is 50°C to 90°C, and the time of the second drying treatment is 24h to 72h. And / or, the temperature of the rolling is 40°C to 65°C.

12. Use of the silicon-based negative electrode sheet according to any one of claims 1 to 6 in the field of lithium-ion batteries.

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