Silicon negative electrode and method for manufacturing the same, and battery

Abstract

The embodiment of the present application provides a silicon negative electrode and a preparation method thereof, and a battery, and belongs to the technical field of batteries. The negative active material layer of the silicon negative electrode comprises a silicon-containing negative active material and a polymer binder, wherein the polymer binder is formed by in-situ polymerization of a polymer precursor in the negative active material layer, and the polymer precursor comprises at least two of ethoxylated trimethylolpropane triacrylate, polyethylene glycol methyl ether methacrylate, polyethylene glycol methyl ether acrylate, polyethylene glycol diglycidyl ether, polyethylene glycol diacrylate and polyurethane. The preparation method of the silicon negative electrode comprises: coating a negative electrode slurry on a substrate; and performing light treatment or heating treatment to make the polymer precursor form the polymer binder in-situ under the initiation of an initiator. The silicon negative electrode and the preparation method can effectively inhibit the expansion of the silicon electrode, and can avoid affecting the stability of the ion conductor in the case of doping the ion conductor.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a silicon anode, a method for preparing the anode, and a battery. Background Technology

[0002] Currently, graphite is the primary anode material for lithium-ion batteries, and its capacity utilization in batteries is approaching its limit of 372 mAh / g. Silicon anode materials, with a capacity close to 4200 mAh / g, several times that of graphite, are widely considered a promising next-generation anode material for lithium-ion batteries.

[0003] However, in the application of silicon anodes, it has been found that the silicon anode expands significantly during charging and discharging, leading to performance instability and hindering its widespread application. One of the main methods for solving this problem in existing technologies is to research and develop novel binders to suppress excessive volume expansion of the silicon anode during charging and discharging.

[0004] However, most mainstream adhesives currently require water-based binders, while commonly used lithium-ion conductors for silicon anodes, such as LLZO and sulfide electrolytes, are sensitive to or unstable in water, thus limiting the use of water-based binders. Other oil-based binders commonly used in lithium-ion batteries, such as PVDF, are not suitable as binders for silicon anode materials because they cannot effectively suppress the expansion of the silicon electrode. Summary of the Invention

[0005] The purpose of this application is to provide a silicon anode, a method for preparing the same, and a battery. The silicon anode and the method for preparing the same can effectively suppress the expansion of the silicon electrode and avoid affecting the stability of the ionic conductor when it is doped with an ionic conductor.

[0006] The embodiments of this application are implemented as follows:

[0007] In a first aspect, embodiments of this application provide a silicon anode. The anode active material layer of the silicon anode includes a silicon-containing anode active material and a polymer binder. The polymer binder is formed by in-situ polymerization of a polymer precursor in the anode active material layer. The polymer precursor includes at least two of ethoxylated trimethylolpropane triacrylate, polyethylene glycol methyl ether methacrylate, polyethylene glycol methyl ether acrylate, polyethylene glycol diglycidyl ether, polyethylene glycol diacrylate, and polyurethane.

[0008] In some possible implementations, the polymer precursor includes polyethylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate.

[0009] In some possible implementations, the mass ratio of polyethylene glycol diacrylate to ethoxylated trimethylolpropane triacrylate is 6–12:3–6.

[0010] In some possible implementations, the silicon-containing anode active material includes at least one of nano-silicon, micro-silicon, silicon / carbon composite, SiO, and SiO / carbon composite.

[0011] In some possible implementations, the negative electrode active material layer of the silicon negative electrode also includes one or more of an electronic conductive agent and an ionic conductor.

[0012] In some possible implementations, the electronically conductive agent includes at least one of carbon black, Ketjen black, graphite, carbon nanotubes, and graphene.

[0013] In some possible implementations, the ionic conductor includes at least one of oxide ionic conductors, sulfide ionic conductors, and halide ionic conductors.

[0014] In some possible implementations, the negative electrode active material layer also includes a lithium salt.

[0015] In some possible implementations, the lithium salt includes at least one of LiPF6, LiTFSI, LiFSI, LiBF4, and LiBOB.

[0016] Secondly, embodiments of this application provide a method for preparing the silicon anode of the above embodiments, comprising:

[0017] A negative electrode slurry is provided, which includes an organic solvent, a silicon-containing negative electrode active material polymer precursor, and an initiator;

[0018] The negative electrode slurry is coated onto the substrate;

[0019] After being treated with light or heat, the polymer precursor is induced to form a polymer adhesive in situ by an initiator.

[0020] In some possible implementations, the heating temperature for the heat treatment is 40–85°C.

[0021] In some possible implementations, the negative electrode slurry also includes an electronically conductive agent and an ionic conductor, and the preparation process of the negative electrode slurry includes:

[0022] An organic solvent and a polymer precursor are mixed to obtain a precursor solution; the precursor solution is then mixed with an electronically conductive agent to obtain a first intermediate slurry; the first intermediate slurry, a silicon-containing anode active material, and an ion conductor are then mixed to obtain a second intermediate slurry; the second intermediate slurry is then mixed with an initiator to obtain an anode slurry.

[0023] In some possible implementations, the organic solvent includes at least one of dimethylacetamide, N-methylpyrrolidone, ethanol, and propanol.

[0024] In some possible implementations, the initiator includes at least one of azobisisobutyronitrile, di-tert-butyl peroxide, and azobisisoheptanenitrile.

[0025] Thirdly, embodiments of this application provide a battery comprising a silicon anode provided in the above embodiments or prepared by the above methods.

[0026] The beneficial effects of the silicon anode and its preparation method provided in this application, as well as the battery, include:

[0027] In silicon anodes and their preparation methods, the polymer binder, which is polymerized from at least two specific types of polymer precursors, has at least the following advantages:

[0028] (1) No aqueous solvent is required during the preparation process, and the stability of the ionic conductor can be avoided when it is doped with an ionic conductor.

[0029] (2) Compared with adhesives obtained by polymerization of only one polymer precursor, this polymer adhesive with a specific structure has a higher degree of crosslinking and flexibility, which can improve the bonding effect and thus effectively suppress the expansion of silicon anode.

[0030] (3) Certain types of polymer precursors can improve the interfacial contact of silicon anodes, thereby helping to reduce interfacial impedance and improve the overall performance of the battery.

[0031] (4) The method of in-situ polymerization to form polymer binder involves mixing the materials of the negative electrode slurry before polymerization, which is beneficial to improving batch stability and the operability of actual scale-up production. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A process flow diagram of a method for preparing a silicon anode provided in this application embodiment;

[0034] Figure 2 This is an external view of the silicon anode prepared in Example 1;

[0035] Figure 3 The first charge-discharge curve of the silicon anode provided in Example 1;

[0036] Figure 4 A rate performance chart of the silicon anode provided in Example 1;

[0037] Figure 5 A statistical chart of the cycle performance of the silicon anode provided in Example 1;

[0038] Figure 6 The first charge-discharge curve of the silicon anode provided for Comparative Example 1;

[0039] Figure 7 Rate performance statistics of the silicon anode provided for Comparative Example 1;

[0040] Figure 8 The cycle performance statistics of the silicon anode provided for Comparative Example 1. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0042] It should be noted that the terms "and / or" in this application, such as "feature 1 and / or feature 2", all refer to the three cases of "feature 1" alone, "feature 2" alone, and "feature 1" plus "feature 2".

[0043] In addition, in the description of this application, unless otherwise stated, "one or more" means two or more; the range of "numerical value a to numerical value b" includes the two endpoints "a" and "b"; and "unit of measurement" in "numerical value a to numerical value b + unit of measurement" represents the "unit of measurement" of both "numerical value a" and "numerical value b".

[0044] The following provides a detailed description of the silicon anode, its preparation method, and the battery according to embodiments of this application.

[0045] In a first aspect, embodiments of this application provide a silicon anode. The anode active material layer of the silicon anode includes a silicon-containing anode active material and a polymer binder. The polymer binder is formed by in-situ polymerization of a polymer precursor in the anode active material layer. The polymer precursor includes at least two of ethoxylated trimethylolpropane triacrylate (ETPTA), polyethylene glycol methyl ether methacrylate, polyethylene glycol methyl ether acrylate, polyethylene glycol diglycidyl ether (PEGDE), polyethylene glycol diacrylate (PEGDA), and polyurethane (PU).

[0046] In some possible implementations, the negative electrode active material layer of the silicon negative electrode also includes one or more of an electronic conductive agent and an ionic conductor.

[0047] In this application, the polymer binder is formed by in-situ polymerization of a polymer precursor, meaning that the polymer binder is added to the negative electrode slurry in the form of a polymer precursor, and then the polymer precursor is generated by in-situ polymerization when the negative electrode active material layer is formed. The polymer binder has structural units corresponding to the polymer precursor in its structural formula.

[0048] In the negative electrode active material layer, the silicon negative electrode active material, electronic conductive agent, ionic conductor and polymer binder are dispersed among each other, and the silicon negative electrode active material, electronic conductive agent and ionic conductor are mainly bonded together by the polymer binder.

[0049] It is understood that, in the embodiments of this application, the silicon anode may include, in addition to the anode active material layer, other conventional structures such as a substrate for coating the anode active material layer. The substrate may be, for example, copper foil or a polyethylene terephthalate (PET) material layer.

[0050] The inventors have discovered that, in the embodiments of this application, the polymer binder obtained by in-situ polymerization of a polymer precursor with a specific composition can effectively suppress the expansion of the silicon anode and improve the interfacial contact of the silicon anode. Some examples will be given below.

[0051] In some possible implementations, the polymer precursor includes polyethylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate.

[0052] As an example, the polymer precursor consists of polyethylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate.

[0053] Furthermore, the mass ratio of polyethylene glycol diacrylate to ethoxylated trimethylolpropane triacrylate is 9–12:3–6, and the mass ratio is, for example, but not limited to, any one of the following values ​​or any range between the two: 9:3, 9:4, 9:5, 9:6, 10:3, 10:4, 10:5, 10:6, 11:3, 11:4, 11:5, 11:6, 12:3, 12:4, 12:5, and 12:6.

[0054] It should be noted that in this application, the types of silicon-containing anode active material, electronic conductive agent and ionic conductor can be selected according to conventional standards. The following are some examples that can be well matched with the embodiments of this application.

[0055] In some possible implementations, the silicon-containing anode active material includes at least one of nano-silicon, micro-silicon, silicon / carbon composite, SiO, and SiO / carbon composite.

[0056] In some possible implementations, the electronically conductive agent includes at least one of carbon black, Ketjen black, graphite, carbon nanotubes, and graphene.

[0057] In some possible implementations, the ionic conductor includes at least one of oxide ionic conductors, sulfide ionic conductors, and halide ionic conductors.

[0058] Among them, oxide ionic conductors are selected for example, lithium lanthanum zirconium oxide (LLZO) and lithium titanium aluminum phosphate (LATP).

[0059] Based on the above embodiments of this application, in some possible implementations, the negative electrode active material layer further includes lithium salt.

[0060] In some possible implementations, the lithium salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), and lithium dioxolaneborate (LiBOB).

[0061] Secondly, embodiments of this application provide a method for preparing the silicon anode of the above embodiments, comprising:

[0062] S1. Provide a negative electrode slurry, which includes an organic solvent, a silicon-containing negative electrode active material, a polymer precursor, and an initiator.

[0063] S2. Coat the negative electrode slurry onto the substrate.

[0064] S3. After light or heat treatment, the polymer precursor is formed in situ into a polymer adhesive under the initiation of the initiator.

[0065] In step S1, the types of silicon-containing anode active material, electronic conductive agent, ionic conductor, and polymer precursor used are as described in the embodiments of the first aspect and will not be repeated here. The types of organic solvent and initiator can be selected according to conventional standards. Some examples that can be well matched with the embodiments of this application are given below.

[0066] In some possible implementations, the organic solvent includes at least one of dimethylacetamide (DMAC), N-methylpyrrolidone, ethanol, and propanol.

[0067] In some possible implementations, the initiator includes at least one of azobisisobutyronitrile, di-tert-butyl peroxide, and azobisisoheptanenitrile.

[0068] In order to ensure that the components in the negative electrode slurry are more fully and uniformly dispersed, the negative electrode slurry is prepared by way of example according to the following procedure.

[0069] See Figure 1As an example, the negative electrode slurry also includes an electronic conductive agent and an ionic conductor, and the preparation process of the negative electrode slurry includes:

[0070] An organic solvent and a polymer precursor are mixed to obtain a precursor solution; the precursor solution is then mixed with an electronically conductive agent to obtain a first intermediate slurry; the first intermediate slurry, a silicon-containing anode active material, and an ion conductor are then mixed to obtain a second intermediate slurry; the second intermediate slurry is then mixed with an initiator to obtain an anode slurry.

[0071] In step S2, the method of coating the negative electrode slurry onto the substrate is not limited, such as but not limited to conventional methods such as spraying and roller coating.

[0072] In step S3, in order to enable the polymer precursor to be initiated and fully reacted for polymerization at a suitable rate, the heating temperature of the heat treatment is optionally 40 to 85°C, for example, but not limited to, any one of 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C and 85°C or any range between two of them.

[0073] Thirdly, embodiments of this application provide a battery comprising a silicon anode provided in the above embodiments or prepared by the above methods.

[0074] In this application, the type of battery is not limited, such as, but not limited to, solid-state batteries, semi-solid-state batteries, etc.

[0075] In batteries, functional structures or materials such as positive electrode plates, separators, and electrolytes can also be configured in a conventional manner.

[0076] The technical solution of this application will be described below with reference to specific embodiments.

[0077] I. Preparation of silicon anode

[0078] Example 1

[0079] Add 12 grams of polyethylene glycol diacrylate and 3 grams of ethoxylated trimethylolpropane triacrylate to 300 grams of DMAC and stir until homogeneous.

[0080] S2. Add 15 g of KS6 graphite conductive agent and stir at 1000 rpm for 2 hours to ensure uniform dispersion.

[0081] S3. Add 270 g of silica suboxide (model SS-450) powder and stir at 1000 rpm for 2 h to ensure uniform dispersion.

[0082] S4. Add 1.5 g of azobisisobutyronitrile and stir evenly to obtain the negative electrode slurry.

[0083] S5. Apply the negative electrode slurry onto a copper foil with a thickness of 8 micrometers or cast it into a PET mold, and preheat it at 60°C for 10 minutes.

[0084] S6. Heating at 100℃ for 6 hours yields silicon anode material.

[0085] Example 2

[0086] Add 12 grams of polyethylene glycol diacrylate and 3 grams of ethoxylated trimethylolpropane triacrylate to 300 grams of DMAC and stir until homogeneous.

[0087] S2. Add 6 grams of KS6 graphite conductive agent and stir at 1000 rpm for 2 hours to ensure uniform dispersion.

[0088] S3. Add 9 grams of LLZO and 270 grams of silica (model SS-450) powder in sequence, and stir at 1000 rpm for 2 hours to ensure uniform dispersion.

[0089] S4. Add 1.5 g of azobisisobutyronitrile and stir evenly to obtain the negative electrode slurry.

[0090] S5. Coat the negative electrode slurry onto an 8-micron copper foil and preheat it at 60°C for 10 minutes.

[0091] S6. Then heat at 100℃ for 6 hours to obtain silicon anode material.

[0092] Example 3

[0093] Add 12 grams of polyethylene glycol diacrylate and 3 grams of ethoxylated trimethylolpropane triacrylate to 300 grams of DMAC and stir until homogeneous.

[0094] S2. Add 6 grams of KS6 graphite conductive agent and stir at 1000 rpm for 2 hours to ensure uniform dispersion.

[0095] S3. Add 9g of LLZO and 270g of Si / C composite (Si content <30%) powder in sequence, and stir at 1000rpm for 2h to disperse evenly.

[0096] S4. Add 1.5 g of azobisisobutyronitrile and stir evenly to obtain the negative electrode slurry.

[0097] S5. Coat the negative electrode slurry onto an 8-micron copper foil and preheat it at 60°C for 10 minutes.

[0098] S6. Then heat at 100℃ for 6 hours to obtain silicon anode material.

[0099] Example 4

[0100] Add 9 grams of polyethylene glycol diacrylate and 6 grams of ethoxylated trimethylolpropane triacrylate to 300 grams of DMAC, and stir until homogeneous.

[0101] S2. Add 6 grams of KS6 graphite conductive agent and stir at 1000 rpm for 2 hours to ensure uniform dispersion.

[0102] S3. Add 9 grams of LLZO and 270 grams of silica (model SS-450) powder in sequence, and stir at 1000 rpm for 2 hours to ensure uniform dispersion.

[0103] S4. Add 1 gram of azobisisobutyronitrile and stir evenly to obtain the negative electrode slurry.

[0104] S5. Coat the negative electrode slurry onto an 8-micron copper foil and preheat it at 60°C for 10 minutes.

[0105] S6. Then heat at 100℃ for 6 hours to obtain silicon anode material.

[0106] Example 5

[0107] Add 12 grams of polyethylene glycol diacrylate and 3 grams of ethoxylated trimethylolpropane triacrylate to 300 grams of DMAC and stir until homogeneous.

[0108] S2. Add 6 grams of KS6 graphite conductive agent and stir at 1000 rpm for 2 hours to ensure uniform dispersion.

[0109] S3. Add 5g of LiTFSI, 9g of LLZO and 270g of silica (model SS-450) powder in sequence, and stir at 1000rpm for 2h to disperse evenly.

[0110] S4. Add 1.5 g of azobisisobutyronitrile and stir evenly to obtain the negative electrode slurry.

[0111] S5. Coat the negative electrode slurry onto an 8-micron copper foil and preheat it at 60°C for 10 minutes.

[0112] S6. Then heat at 100℃ for 6 hours to obtain silicon anode material.

[0113] Example 6

[0114] Add 9 grams of polyethylene glycol diacrylate and 6 grams of ethoxylated trimethylolpropane triacrylate to 300 grams of DMAC, and stir until homogeneous.

[0115] S2. Add 6 grams of KS6 graphite conductive agent and stir at 1000 rpm for 2 hours to ensure uniform dispersion.

[0116] S3. Add 19g of LLZO and 270g of silica (model SS-450) powder in sequence, and stir at 1000rpm for 2h to disperse evenly.

[0117] S4. Add 1 gram of azobisisobutyronitrile and stir evenly to obtain the negative electrode slurry.

[0118] S5. Coat the negative electrode slurry onto an 8-micron copper foil and preheat it at 60°C for 10 minutes.

[0119] S6. Then heat at 100℃ for 6 hours to obtain silicon anode material.

[0120] Example 7

[0121] Add 9 grams of polyethylene glycol diacrylate and 6 grams of ethoxylated trimethylolpropane triacrylate to 300 grams of isopropanol, stir until homogeneous, and obtain the negative electrode slurry.

[0122] S2. Add 6 grams of KS6 graphite conductive agent and stir at 1000 rpm for 2 hours to ensure uniform dispersion.

[0123] S3. Add 12g of Li6PS5Cl and 270g of silicon suboxide (model SS-450) powder in sequence, and stir at 1000rpm for 2h to disperse evenly.

[0124] S4. Add 1 gram of azobisisobutyronitrile and stir evenly to obtain the negative electrode slurry.

[0125] S5. Coat the negative electrode slurry onto an 8-micron copper foil and preheat it at 50°C for 10 minutes.

[0126] S6. Then heat at 80℃ for 6 hours to obtain silicon anode material.

[0127] Example 8

[0128] The only difference from Example 1 is that:

[0129] The polymer precursor was replaced with 12 grams of polyurethane and 3 grams of polyethylene glycol diglycidyl ether, and the mixture was stirred evenly to obtain the negative electrode slurry.

[0130] Comparative Example 1

[0131] S1. Add 3g of sodium carboxymethyl cellulose (CMC) and 12g of acrylonitrile copolymer (LA133) to 300g of water and stir until homogeneous.

[0132] S2. Add 15 g of KS6 graphite conductive agent and stir at 1000 rpm for 2 hours to ensure uniform dispersion.

[0133] S3. Add 270 g of silicon suboxide powder and stir at 1000 rpm for 2 h to disperse evenly and obtain the negative electrode slurry.

[0134] S4. Coat the negative electrode slurry onto an 8-micron copper foil and preheat it at 50°C for 10 minutes.

[0135] S5. Then heat at 100℃ for 6 hours to obtain silicon anode material.

[0136] Comparative Example 2

[0137] The only difference from Example 1 is that:

[0138] Replace the polymer precursor with 15 grams of polyethylene glycol diacrylate.

[0139] Comparative Example 3

[0140] The only difference from Example 1 is that:

[0141] The polymer precursor was replaced with 15 grams of ethoxylated trimethylolpropane triacrylate.

[0142] Comparative Example 4

[0143] The only difference from Example 1 is that:

[0144] Replace the polymer precursor with 15 grams of polyethylene glycol methyl ether methacrylate.

[0145] II. Product Testing

[0146] 1. The appearance of the silicon anode prepared in Example 1 was observed and photographed, and the results are as follows: Figure 2 As shown. (a) is a silicon anode formed by coating on copper foil, and (b) is a silicon anode material formed by casting in a PET mold.

[0147] according to Figure 2 (b) It can be seen that the silicon anode material obtained by casting has good flexibility. The reason is that the polymer binder formed in situ by a certain type of polymer precursor has excellent bonding effect. This means that it can effectively alleviate the large volume expansion of the silicon anode material during charging and discharging, which is conducive to improving the overall electrochemical performance of the battery.

[0148] 2. The silicon anode was assembled into a CR2016 coin cell, and its electrochemical performance was tested in the voltage range of 0.005V to 2V. The test results are as follows.

[0149] Figure 3 The first charge-discharge curve of the silicon anode provided in Example 1.

[0150] according to Figure 3It can be seen that the silicon anode provided in Example 1 has an initial charging capacity of 458.51 mAh / g at 0.1C and a first-cycle coulombic efficiency of 90.74%.

[0151] Figure 4 A rate performance chart of the silicon anode provided in Example 1.

[0152] according to Figure 4 It can be seen that the silicon anode provided in Example 1 has a reversible capacity of 345.21 mAh / g at 1C.

[0153] Figure 5 The cycle performance statistics of the silicon anode provided in Example 1 are shown in the figure.

[0154] according to Figure 5 It can be seen that the silicon anode provided in Example 1 retains 70.33% of its capacity after 60 cycles at 0.5C.

[0155] Figure 6 The first charge-discharge curve of the silicon anode provided for Comparative Example 1.

[0156] according to Figure 6 It can be seen that the silicon anode provided by Comparative Example 1 has an initial charging capacity of 451.29 mAh / g at 0.1C and a first-cycle coulombic efficiency of 89.44%.

[0157] Figure 7 A statistical chart of the rate performance of the silicon anode provided for Comparative Example 1.

[0158] according to Figure 7 It can be seen that the silicon anode provided in Comparative Example 1 has a reversible capacity of 125.3 mAh / g at 1C.

[0159] Figure 8 The cycle performance statistics of the silicon anode provided for Comparative Example 1.

[0160] according to Figure 8 It can be seen that the silicon anode provided in Comparative Example 1 has a capacity retention rate of 57.06% after 60 cycles at 0.5C.

[0161] The test performance statistics of each embodiment and Comparative Example 1 are shown in Table 1 below.

[0162] Table 1

[0163]

[0164]

[0165] according to Figures 3-6 As shown in Table 1:

[0166] Compared with Comparative Example 1 which uses an aqueous binder, the silicon anode provided in Example 1 of this application shows a significant improvement in electrochemical performance, indicating that the polymer binder formed in situ by the polymer precursor can effectively suppress the expansion of the silicon anode.

[0167] Compared to Example 1, the polymer binder formed by polyurethane and polyethylene glycol diglycidyl ether in Example 8 under the initiation of free radicals has a relatively poor bonding effect, resulting in a relatively poor quality of the electrode. The electrode is relatively easy to swell and pulverize and fall off when immersed in electrolyte, thus resulting in relatively poor electrochemical performance.

[0168] In Comparative Examples 2 to 4, only one polymer was used as a binder. Because the bonding effect of a single polymer is weak, the active material in the electrode has poor adhesion. Therefore, compared with the examples, it is very easy to peel off and fall off, ultimately resulting in poor electrochemical performance.

[0169] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A silicon anode, characterized in that, The anode active material layer of the silicon anode includes a silicon-containing anode active material and a polymer binder, wherein the polymer binder is formed by in-situ polymerization of a polymer precursor in the anode active material layer; the polymer precursor includes polyethylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate, and the mass ratio of polyethylene glycol diacrylate to ethoxylated trimethylolpropane triacrylate is 9-12:3-6.

2. The silicon anode according to claim 1, characterized in that, The silicon-containing anode active material includes at least one of nano-silicon, micron-silicon, silicon / carbon composite material, SiO, and SiO / carbon composite material.

3. The silicon anode according to claim 1, characterized in that, The anode active material layer of the silicon anode also includes one or more of electronic conductive agents and ionic conductors.

4. The silicon anode according to claim 3, characterized in that, The electronically conductive agent includes at least one of carbon black, Ketjen black, graphite, carbon nanotubes, and graphene.

5. The silicon anode according to claim 3, characterized in that, The ionic conductor includes at least one of oxide ionic conductors, sulfide ionic conductors, and halide ionic conductors.

6. The silicon anode according to claim 1, characterized in that, The negative electrode active material layer also includes lithium salt.

7. The silicon anode according to claim 6, characterized in that, The lithium salt includes at least one of LiPF6, LiTFSI, LiFSI, LiBF4, and LiBOB.

8. A method for preparing a silicon anode as described in any one of claims 1 to 7, characterized in that, include: A negative electrode slurry is provided, the negative electrode slurry comprising an organic solvent, the silicon-containing negative electrode active material, the polymer precursor, and an initiator; The negative electrode slurry is coated onto the substrate; The polymer precursor is subjected to light or heat treatment to form the polymer adhesive in situ under the initiation of the initiator.

9. The preparation method according to claim 8, characterized in that, The heating temperature for the heat treatment is 40–85°C.

10. The preparation method according to claim 8, characterized in that, The negative electrode slurry further includes an electronic conductive agent and an ionic conductor, and the preparation process of the negative electrode slurry includes: The organic solvent and the polymer precursor are mixed to obtain a precursor solution; the precursor solution is then mixed with the electronic conductive agent to obtain a first intermediate slurry; the first intermediate slurry, the silicon-containing anode active material, and the ion conductor are then mixed to obtain a second intermediate slurry; the second intermediate slurry is then mixed with the initiator to obtain the anode slurry.

11. The preparation method according to any one of claims 8 to 10, characterized in that, The organic solvent includes at least one of dimethylacetamide, N-methylpyrrolidone, ethanol, and propanol.

12. The preparation method according to any one of claims 8 to 10, characterized in that, The initiator includes at least one of azobisisobutyronitrile, di-tert-butyl peroxide, and azobisisoheptanenitrile.

13. A battery, characterized in that, It includes the silicon anode provided in any one of claims 1 to 7 or the silicon anode prepared by any one of claims 8 to 12.

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