Anode sheet and use thereof

Abstract

The application provides an anode sheet and a secondary battery using the same, the anode sheet comprising an anode active material layer, the anode active material layer comprising an anode active material and a binder, the anode active material comprising a silicon-based active substance, and the binder comprising polyacrylic acid and its derivatives and polyvinyl alcohol; the anode sheet is laser-perforated; when the mass content of the silicon-based active substance is a constant value, the mass content of the polyvinyl alcohol is in a positive proportional relationship with the power of the laser perforation; and when the power of the laser perforation is a constant value, the mass content of the polyvinyl alcohol is in a positive proportional relationship with the mass content of the silicon-based active substance. Compared with the prior art, the anode sheet provided by the application selects anode sheets containing different contents of the binder according to different laser perforation powers or different silicon contents of the silicon anode sheet, thereby avoiding excessive burning of the active substance at the non-perforated part of the silicon anode sheet, and improving the cycle performance and safety performance of the battery in the charging and discharging process.

Description

Technical Field

[0001] This invention relates to the field of secondary batteries, and more specifically to an anode sheet and its application. Background Technology

[0002] In existing lithium-ion battery manufacturing technologies, the fabrication and design of the anode electrode is a crucial step. Specific processes and material choices significantly impact battery performance, such as energy density, charge / discharge rate, and lifespan. In recent years, laser drilling of the anode electrode has gained widespread attention as a novel manufacturing technology.

[0003] Laser drilling of anode plates utilizes a high-power-density laser beam to irradiate the material being processed, rapidly heating it to its vaporization temperature and then evaporating it to form holes. This technology has effectively improved the charging window of the battery cell, opening up new avenues for enhancing the performance of lithium-ion batteries.

[0004] However, some problems need to be addressed during the implementation of this technology. In particular, since anode laser drilling requires high-temperature etching of the electrode sheets, this may cause the silicon particles in the anode to be burned, thus affecting the long-term stability and consistency of the battery. Specifically, this may lead to problems in the later stages of cell cycling, such as performance degradation and reduced lifespan.

[0005] Therefore, finding and developing a method to solve the problems in existing laser drilling technology for anode plates and improve the performance and lifespan of lithium-ion batteries has become an important task and research hotspot in this field. Summary of the Invention

[0006] One of the objectives of this invention is to provide an anode sheet that addresses the shortcomings of existing technologies by solving the problem of high-temperature burning of the active material on the anode sheet outside the drilling location caused by high-power laser drilling.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An anode sheet includes an anode active material layer, the anode active material layer comprising an anode active material and a binder, the anode active material comprising a silicon-based active substance, and the binder comprising polyacrylic acid and its derivatives and polyvinyl alcohol; the anode sheet also includes laser-penetrating holes;

[0009] Wherein, the glass transition temperature of the polyacrylic acid and its derivatives is greater than that of polyvinyl alcohol, and the mass content of polyvinyl alcohol in the binder, the mass content of the silicon-based active material in the anode active material, and the laser drilling power satisfy at least one of the following relationships:

[0010] (a) When the mass content of the silicon-based active material is a constant, the mass content of the polyvinyl alcohol is directly proportional to the power of the laser drilling.

[0011] (b) When the power of laser drilling is constant, the mass content of the polyvinyl alcohol is directly proportional to the mass content of the silicon-based active material.

[0012] Preferably, when the mass content of the silicon-based active material is 1-5%, the mass content of the polyvinyl alcohol and the power of the laser drilling satisfy the following relationship:

[0013] When the laser drilling power is <200W, the mass content of the polyvinyl alcohol is 0.1% to 3%;

[0014] When the laser drilling power is 200W to 700W, the mass content of the polyvinyl alcohol is 3% to 10%.

[0015] When the laser drilling power is 700W to 1500W, the mass content of the polyvinyl alcohol is 10% to 35%.

[0016] When the laser drilling power is >1500W, the mass content of the polyvinyl alcohol is 35% to 50%.

[0017] Preferably, when the laser drilling power is 700W to 1500W, the mass content of the polyvinyl alcohol and the mass content of the silicon-based active material satisfy the following relationship:

[0018] The silicon-based active material has a mass content of 1-5%, and the polyvinyl alcohol has a mass content of 10%-35%.

[0019] The silicon-based active material has a mass content of 5-10%, and the polyvinyl alcohol has a mass content of 35%-50%.

[0020] The silicon-based active material has a mass content of >10%, and the polyvinyl alcohol has a mass content of 50% to 75%.

[0021] Preferably, when the laser drilling power is <200W, the mass content of the polyvinyl alcohol is 0.1-3%, and the depth of the laser-drilled hole is <10μm.

[0022] Preferably, when the laser drilling power is 200W to 700W, the mass content of the polyvinyl alcohol is 3% to 10%; and the depth of the laser-drilled hole is 10 to 15 μm.

[0023] Preferably, when the laser drilling power is 700W to 1500W, the mass content of the polyvinyl alcohol is 10% to 35%, and the depth of the laser-drilled hole is 15 to 20 μm.

[0024] Preferably, when the laser drilling power is >1500W, the mass content of the polyvinyl alcohol is 35% to 50%, and the depth of the laser-drilled hole is >25μm.

[0025] Preferably, the depth of the laser-drilled hole is 15–20 μm.

[0026] Preferably, the mass ratio of the polyvinyl alcohol to the polyacrylic acid and its derivatives is (1-75):(25-99).

[0027] Preferably, the polyacrylic acid and its derivatives include at least one of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, polyacrylamide, and calcium polyacrylate.

[0028] Preferably, the silicon-based active material includes at least one of silicon-carbon, silicon-oxygen, and nano-silicon; the anode active material further includes graphite particles, wherein the OI value of the graphite particles is 7 to 9.

[0029] The present invention also provides a secondary battery comprising the anode sheet described in any of the preceding claims.

[0030] Compared to existing technologies, the beneficial effects of this invention are as follows: The anode sheet in this invention includes an anode active material layer, which includes an anode active material and a binder. The anode active material includes a silicon-based active substance, and the binder includes polyacrylic acid and its derivatives and polyvinyl alcohol. Depending on the laser drilling power or the silicon content of the silicon anode sheet, anode sheets containing different amounts of binder can be selected, thereby avoiding excessive burning of the active material in the non-drilled areas of the silicon anode sheet, thus improving the cycle performance and safety performance of the battery during charging and discharging.

[0031] The polyvinyl alcohol in the binder is a linear polymer that has good compatibility with the other binder, linear chain polyacrylic acid and its derivatives. This effectively binds the silicon particles in the electrode, reducing the expansion effect caused by repeated charging and discharging of the silicon particles. At the same time, when laser drilling is performed, the polyvinyl alcohol added to the silicon anode has a lower glass transition temperature, and its blending with polyacrylic acid and its derivatives can lower the overall glass transition temperature, making the binder in a rubbery state. The rubbery state of the material has high fluidity and plasticity, meaning that the fluid binder moves around the silicon particles, and the linear binder can wrap around the silicon particles. Therefore, when etching the silicon anode, the probability of the silicon particles, i.e., the active material, being etched through is greatly reduced, protecting the electrode portion outside the laser-drilled area. Detailed Implementation

[0032] To make the technical solution and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0033] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] To make the technical solution and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0035] According to a first aspect of the invention, an anode sheet is provided, comprising an anode active material layer, the anode active material layer comprising an anode active material and a binder, the anode active material comprising a silicon-based active substance, and the binder comprising polyacrylic acid (PAA) and its derivatives and polyvinyl alcohol (PVA); the anode sheet is laser-drilled.

[0036] Wherein, the mass content of polyvinyl alcohol in the binder, the mass content of the silicon-based active material in the anode active material, and the power of the laser drilling shall satisfy at least one of the following relationships:

[0037] (a) When the mass content of the silicon-based active material is a constant, the mass content of the polyvinyl alcohol is directly proportional to the power of the laser drilling.

[0038] (b) When the power of laser drilling is constant, the mass content of the polyvinyl alcohol is directly proportional to the mass content of the silicon-based active material.

[0039] The binder contained in the laser-drilled anode sheet of the present invention includes polyacrylic acid and its derivatives and polyvinyl alcohol. The amount of binder needs to be added according to the laser drilling power and the content of silicon-based active material in the silicon anode sheet, so as to avoid the anode sheet being burned by high temperature under high-power laser drilling. Polyvinyl alcohol is an important synthetic polymer material. Its molecular chain contains a large number of hydroxyl (-OH) functional groups. These hydroxyl groups interact with each other through hydrogen bonds to form an interlaced lattice structure, thus having good adhesion. The glass transition temperature of polyvinyl alcohol is generally between 60 and 85°C, while the glass transition temperature of polyacrylic acid and its derivatives is about 105°C to 155°C. The blending of the two can reduce the overall glass transition temperature.

[0040] During laser etching and drilling, the drilling power represents the etching intensity of the electrode. Higher drilling power results in deeper drilling, which in turn increases the etching temperature, requiring a corresponding increase in the amount of polyvinyl alcohol (PVA) added. The sudden temperature rise during drilling causes the binder to be in a rubbery state. This rubbery state exhibits high fluidity and plasticity, allowing the fluid binder to move freely around the silicon particles. Linear binders can wrap around the silicon particles, significantly reducing the probability of the silicon particles (the active material) being etched through during the etching of the silicon anode. Conversely, when the binder is in a glassy state, it is hard and brittle, resulting in weak adhesion between the bound silicon particles and the binder. This leads to a peeling state between the binder and the silicon particles, increasing the likelihood of the silicon particles being etched.

[0041] It should also be noted that polyvinyl alcohol, as a linear polymer, has good compatibility with the linear chain PAA binder in the silicon anode sheet formulation, which can effectively bind silicon particles and reduce the expansion effect generated by the silicon particles themselves during repeated charging and discharging.

[0042] In one embodiment of the present invention, when the mass content of the silicon anode sheet is 1-5% and the laser drilling power is <200W, the mass content of the polyvinyl alcohol is 0.1-3%.

[0043] In one embodiment of the present invention, when the mass content of the silicon anode sheet is 1-5%, and the laser drilling power is 200W-700W, the mass content of the polyvinyl alcohol is 3%-10%.

[0044] In one embodiment of the present invention, when the mass content of the silicon anode sheet is 1-5%, and the laser drilling power is 700W-1500W, the mass content of the polyvinyl alcohol is 10%-35%.

[0045] In one embodiment of the present invention, when the mass content of the silicon anode sheet is 1-5%, and the laser drilling power is >1500W, the mass content of the polyvinyl alcohol is 35%-50%.

[0046] In one embodiment of the present invention, when the laser drilling power is 700W to 1500W, the mass content of the silicon-based active material is 1% to 5%, and the mass content of the polyvinyl alcohol is 10% to 35%.

[0047] In one embodiment of the present invention, when the laser drilling power is 700W to 1500W, the mass content of the silicon-based active material is 5% to 10%, and the mass content of the polyvinyl alcohol is 35% to 50%.

[0048] In one embodiment of the present invention, when the laser drilling power is 700W to 1500W, the mass content of the silicon-based active material is >10%, and the mass content of the polyvinyl alcohol is 50% to 75%.

[0049] In this invention, laser drilling is performed on the silicon anode sheet. The depth of the hole left by different laser powers on the anode sheet also has a certain numerical range. In some embodiments, when the laser drilling power is <200W, the mass content of the polyvinyl alcohol is 0.1-3%, and the depth of the laser-drilled hole is <10μm.

[0050] In some embodiments, when the laser drilling power is 700W to 1500W, the mass content of the polyvinyl alcohol is 10% to 35%, and the depth of the laser-drilled hole is 15 to 20 μm.

[0051] In some embodiments, when the laser drilling power is >1500W, the mass content of the polyvinyl alcohol is 35% to 50%, and the depth of the laser-drilled hole is >25μm.

[0052] In this invention, the mass ratio of the binder polyvinyl alcohol (PVA) to the polyacrylic acid and its derivatives in the active material layer on the laser-drilled anode sheet is (1–75):(25–99), specifically 1:99, (3–10):(90–97), (10–35):(65–90), (35–50):(50–65), (50–75):(25–50), and may include, but is not limited to, the examples mentioned above. The mass content of PVA is directly proportional to the laser drilling power and the content of silicon-based active material in the silicon anode sheet.

[0053] In one embodiment of the present invention, the polyacrylic acid and its derivatives include at least one of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, polyacrylamide and calcium polyacrylate, preferably polyacrylic acid.

[0054] In one embodiment of the present invention, the silicon-based active material includes at least one of silicon-carbon, silicon-oxygen, and nano-silicon, preferably silicon-carbon.

[0055] In addition, the selection of the OI value (oxidation index) of graphite in the anodic active material of the present invention is crucial. The matching graphite OI value in the present invention is selected in the range of 7 to 9, specifically 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, and 9.0, and may include but is not limited to the values ​​listed above, with 8.6 being the preferred value.

[0056] In particular, adjusting the graphite OI value to improve the distribution and interaction of the binder, along with variations in the amount of polyvinyl alcohol (PVA), can enhance the thermal stability of the anolyte, allowing it to maintain its performance at higher temperatures. A suitable OI value can enhance the compatibility between graphite and the binder, improve the uniformity and stability of the electrode, and thus compensate for the adverse effects of excessive PVA. Excessive PVA can negatively impact slurry performance and electrode quality; however, by adjusting the OI value of graphite, the interaction between graphite and the binder can be optimized, thereby balancing the effects of PVA and improving the overall performance of the electrode.

[0057] In this invention, the OI value of graphite is obtained by X-ray diffraction (XRD) pattern analysis. In one embodiment of this invention, the anodic active material, conductive agent, and binder are mixed in a weight ratio of (95.5–97.8):(0.1–1):(2.0–3.8) to prepare an anodic active slurry; specifically, the ratio can be 95.5:0.7:3.8, 96:0.5:3.5, 96.3:1:2.7, 96.5:0.1:3.4, 97.2:0.5:2.3, or 97.5:0.4:2.1; it can include, but is not limited to, the examples above, and is preferably 97.2:0.5:2.3.

[0058] To make the technical solution and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0059] Example 1

[0060] Preparation of the anode sheet:

[0061] 1) Anode active material (graphite with an OI value of 8.6 + 5% wt silicon carbide), conductive agent (SWCNT + SP), and binder (PAA + 2% PVA) are mixed in a weight ratio of 97.2%: 0.5%: 2.3% to prepare anode active material slurry;

[0062] 2) The prepared anodic active slurry is coated onto the current collector copper foil, cold-pressed, and slit to obtain anode sheets;

[0063] 3) The anode sheet obtained in step 2) is perforated with a laser at a power of 150W to a hole depth of 5μm, thus obtaining the laser-perforated anode sheet. Preparation of the cathode sheet: The active material LiCoO2, conductive agent acetylene black, conductive carbon nanotubes, and binder polyvinylidene fluoride (PVDF) are fully dispersed and uniformly coated onto an aluminum current collector in an N-methylpyrrolidone solvent system at a weight ratio of 98.2%:0.5%:0.3%:1.0%. The resulting coating is then cold-pressed and slit to obtain the cathode sheet.

[0064] The preparation parameters of the anode electrode are summarized in Table 1 below.

[0065] Separator: A ceramic mixture is coated on the PE surface to serve as a separator.

[0066] Electrolyte: Ethyl carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and propyl propionate (PP) are mixed in a volume ratio of 1:1:4:4. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent at a ratio of 1 mol / L to prepare the electrolyte.

[0067] Soft-pack cell preparation: The above-mentioned cathode electrode, separator, and laser-drilled anode sheet are wound or stacked to make a bare cell, which is then packaged and injected with electrolyte to produce a finished lithium-ion battery.

[0068] Example 2-

[0069] Unlike Example 1, in step 1), PVA accounts for 5% of the total amount of adhesive, and in step 3), the laser drilling power is 500W and the hole depth is 12μm.

[0070] The rest is the same as in Example 1, and will not be repeated here.

[0071] Example 3

[0072] Unlike Example 1, in step 1), PVA accounts for 25% of the total amount of adhesive, and in step 3), the laser drilling power is 1200W and the hole depth is 18μm.

[0073] The rest is the same as in Example 1, and will not be repeated here.

[0074] Example 4

[0075] Unlike Example 1, in step 1), PVA accounts for 45% of the total adhesive volume, and in step 3), the laser drilling power is 1800W and the hole depth is 28μm.

[0076] The rest is the same as in Example 1, and will not be repeated here.

[0077] Example 5

[0078] Unlike Example 3, the added anolyte material (graphite + 8 wt% silicon carbide) and the binder contain PVA accounting for 45% of the total binder volume.

[0079] The rest is the same as in Example 3, and will not be repeated here.

[0080] Example 6

[0081] Unlike Example 3, the added anolyte material (graphite + 15 wt% silicon carbide) and the binder contain PVA accounting for 65% of the total binder volume.

[0082] The rest is the same as in Example 3, and will not be repeated here.

[0083] Comparative Examples 1-3

[0084] The difference from Example 2 is the amount of PVA adhesive added in step 1), as shown in Table 1.

[0085] The rest is the same as in Example 2, and will not be repeated here.

[0086] Comparative Examples 4-6

[0087] The difference from Example 3 is the amount of PVA adhesive added in step 1), as shown in Table 1.

[0088] The rest is the same as in Example 3, and will not be repeated here.

[0089] Comparative Examples 7-9

[0090] The difference from Example 5 is the amount of PVA adhesive added in step 1), as shown in Table 1.

[0091] The rest is the same as in Example 5, and will not be repeated here.

[0092] Comparative Examples 10-11

[0093] The difference from Example 6 is the amount of PVA adhesive added in step 1), as shown in Table 1.

[0094] The rest is the same as in Example 6, and will not be repeated here.

[0095] Comparative Example 12

[0096] Unlike Example 4, in step 1), PVA accounts for a certain percentage of the total amount of adhesive, as shown in Table 1.

[0097] The rest is the same as in Example 4, and will not be repeated here.

[0098] Comparative Example 13

[0099] Unlike Example 1, in step 1), PVA accounts for a certain percentage of the total adhesive volume, as shown in Table 1.

[0100] The rest is the same as in Example 1, and will not be repeated here.

[0101] Comparative Example 14

[0102] The difference from Example 3 is the laser drilling power and hole depth in step 3), as shown in Table 1;

[0103] The rest is the same as in Example 3, and will not be repeated here.

[0104] Comparative Example 15

[0105] The difference from Example 4 is the laser drilling power and hole depth in step 3), as shown in Table 1;

[0106] The rest is the same as in Example 4, and will not be repeated here.

[0107] Comparative Example 16

[0108] The difference from Example 5 is the laser drilling power and hole depth in step 3), as shown in Table 1;

[0109] The rest is the same as in Example 5, and will not be repeated here.

[0110] Comparative Examples 17-18

[0111] The difference from Example 3 is the OI value of the graphite in step 1), as shown in Table 1;

[0112] The rest is the same as in Example 3, and will not be repeated here.

[0113] Comparative Example 19

[0114] Unlike Example 3, the PVA in the adhesive of step 1) is replaced with styrene-butadiene rubber;

[0115] The rest is the same as in Example 3, and will not be repeated here.

[0116] Cyclic performance tests were conducted on the pouch cells of Examples 1-6 and Comparative Examples 1-19, respectively, and the test results are shown in Table 1.

[0117] Test method: The cell is charged to 4.25V in a 4.0C step charge, then charged to the cutoff voltage at a 3.0C rate. After 800 cycles, the remaining capacity is the percentage of the initial capacity, i.e., the capacity retention rate.

[0118] The method for testing the graphite OI value is: OI = C002 / C110, where C002 is the peak area of ​​the 002 characteristic diffraction peak in the X-ray diffraction pattern of the negative electrode active material powder, and C110 is the peak area of ​​the 110 characteristic diffraction peak in the X-ray diffraction pattern of the negative electrode active material powder.

[0119] Table 1

[0120]

[0121]

[0122] Results Analysis: In Examples 1-6 within the scope of this invention, both PAA and PVA binders were added simultaneously. PVA, as a linear polymer, has good compatibility with the linear chain PAA binder in the silicon anode sheet formulation. It can effectively bind silicon particles, reduce the expansion effect generated by the silicon particles during repeated charging and discharging, effectively protect the capacity retention rate of the electrode sheet and improve the safety performance of the electrode sheet, and avoid the high temperature generated during laser drilling that could burn the silicon particles and cause capacity failure.

[0123] As can be seen from Comparative Examples 4-9, the amount of PVA added has a limited range, and its effect roughly follows a parabolic curve. Too little PVA will not achieve the best effect, while excessive PVA can even worsen the capacity retention rate. In Comparative Examples 12-16, if any of the contents of the adhesive PAA and PVA, the drilling power, or the drilling depth is outside the scope of this invention, the capacity retention rate deteriorates significantly.

[0124] As can be seen from comparative examples 2-3, 5-6, 9, and 13-16, excessive PVA will reduce the bonding strength of the electrode and the electrochemical performance of the cell. On the one hand, excessive polyvinyl alcohol will increase the viscosity of the slurry and affect the coating uniformity. On the other hand, its high content will easily cause the slurry to crack during the drying process, affecting the performance of the anode sheet. Therefore, polyvinyl alcohol needs to be controlled within a reasonable range according to the silicon content and the laser drilling power.

[0125] As shown in Comparative Example 19, although the Tg (glass transition temperature) of styrene-butadiene rubber (SBR) is lower than that of polyvinyl alcohol (PVA), its adhesion and tensile strength do not meet the specific requirements of the anode electrode during laser drilling. The anode electrode needs to maintain good structural integrity after laser drilling, which requires the adhesive to have sufficient bonding strength. Insufficient adhesion of SBR leads to delamination or peeling of the electrode after drilling, affecting battery performance and safety. The thermal and mechanical stresses generated during laser drilling may cause tension on the material. Due to the insufficient tensile strength of SBR, it cannot effectively resist these stresses, leading to cracks or breakage of the electrode during or after drilling.

[0126] In summary, this invention adjusts the amount of PVA in the binder based on the laser drilling power and the silicon-carbon content of the silicon anode sheet, so that the electrode sheet in the non-laser-drilled area is not burned by the high temperature generated by the high-power laser, which can effectively ensure the capacity retention rate of the battery and improve the cycle performance and safety performance of the battery during charging and discharging.

[0127] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. An anode sheet characterized by: The anode sheet comprises an anode active material layer, the anode active material layer comprises an anode active material and a binder, the anode active material comprises a silicon-based active substance, and the binder comprises polyacrylic acid and its derivatives and polyvinyl alcohol; the anode sheet is laser-perforated; Wherein, the glass transition temperature of the polyacrylic acid and its derivatives is greater than that of the polyvinyl alcohol, the mass content of the polyvinyl alcohol in the binder, the mass content of the silicon-based active substance in the anode active material and the power of the laser perforation at least meet one of the following relationships: (a) When the mass content of the silicon-based active substance is 1%~5%, the mass content of the polyvinyl alcohol is in a positive proportional relationship with the power of the laser perforation, and satisfies: When the laser perforation power is <200W, the mass content of the polyvinyl alcohol is 0.1%~3%; When the laser perforation power is 200W~700W, the mass content of the polyvinyl alcohol is 3%~10%; When the laser perforation power is 700W~1500W, the mass content of the polyvinyl alcohol is 10%~35%; When the laser perforation power is >1500W, the mass content of the polyvinyl alcohol is 35%~50%; (b) When the power of the laser perforation is 700W~1500W, the mass content of the polyvinyl alcohol is in a positive proportional relationship with the mass content of the silicon-based active substance, and satisfies: When the mass content of the silicon-based active substance is 1%~5%, the mass content of the polyvinyl alcohol is 10%~35%; When the mass content of the silicon-based active substance is 5%~10%, the mass content of the polyvinyl alcohol is 35%~50%; When the mass content of the silicon-based active substance is >10%, the mass content of the polyvinyl alcohol is 50%~75%.

2. The anode sheet according to claim 1, characterized by: When the laser perforation power is <200W, the mass content of the polyvinyl alcohol is 0.1%~3%, and the hole depth of the laser perforation is <10μm.

3. The anode sheet according to claim 1, characterized by: When the laser perforation power is 200W~700W, the mass content of the polyvinyl alcohol is 3%~10%, and the hole depth of the laser perforation is 10~15μm.

4. The anode sheet according to claim 1, characterized by: When the laser perforation power is 700W~1500W, the mass content of the polyvinyl alcohol is 10%~35%, and the hole depth of the laser perforation is 15~20μm.

5. The anode sheet according to claim 1, characterized by: When the laser perforation power is >1500W, the mass content of the polyvinyl alcohol is 35%~50%, and the hole depth of the laser perforation is >25μm.

6. The anode sheet according to claim 1, characterized by: The hole depth of the laser perforation is 15~20μm.

7. The anode sheet according to claim 1, characterized by: The mass ratio of the polyvinyl alcohol to the polyacrylic acid and its derivatives is (1~75):(25~99).

8. The pole piece of claim 1, wherein: The polyacrylic acid and its derivatives comprise at least one of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, polyacrylamide and calcium polyacrylate.

9. The anode sheet according to claim 1, characterized by: The silicon-based active substance comprises at least one of silicon-carbon, silicon-oxygen and nano-silicon; the anode active material further comprises graphite particles, and the OI value of the graphite particles is 7~9.

10. A secondary battery characterized by comprising: The anode sheet comprises the anode sheet according to any one of claims 1~9.

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