Zinc-p1 / p2 bilayer composite fiber electrode, preparation thereof and application thereof in negative electrode-free zinc battery

Abstract

The application belongs to the field of zinc batteries, and particularly relates to a preparation method of a zinc-P1 / P2 double-layer composite fiber electrode, a spinning solution A in which zinc salt and polymer P1 are dissolved is obtained, and a spinning solution B in which polymer P2 is dissolved is obtained; the first-stage electrostatic spinning is performed by using the spinning solution A to prepare a zinc-P1 layer; the second-stage electrostatic spinning is performed by using the spinning solution B with the zinc-P1 layer as a substrate to form a P2 layer on the surface of the zinc-P1 layer, and then drying treatment is performed, so that the zinc-P1 / P2 double-layer composite fiber electrode is obtained. The application also includes the electrode prepared by the method and the application of the electrode in zinc batteries. The electrode prepared by the method can help to reduce the hydrogen evolution reaction, dendrite growth, dead zinc evolution and energy density, and can effectively improve the performance of the prepared material in the zinc battery without a negative electrode, especially the low-temperature performance.

Description

Technical Field

[0001] This invention belongs to the field of zinc batteries, and specifically relates to a zinc battery without a negative electrode. Background Technology

[0002] Zinc-ion batteries possess advantages such as high energy density, long cycle life, low cost, and environmental friendliness, making them promising for applications in electric vehicles, energy storage systems, and mobile devices. Compared to traditional lithium-ion batteries, zinc-ion batteries are less expensive, and zinc is a widely available metal with abundant resources, eliminating supply shortages. With continuous technological advancements and expanding applications, zinc-ion batteries are poised to become a key representative of future battery technologies. However, current zinc-ion batteries suffer from insufficient energy density, and zinc metal experiences severe dendrite growth, electrode side reactions, and gas generation during cycling, seriously jeopardizing battery safety.

[0003] Currently, researchers have conducted extensive research on improving zinc anodes and developing novel electrolytes, but the corresponding problems have not yet been fully resolved. Anode-free battery solutions, on the other hand, avoid the use of zinc metal, effectively addressing the issues of zinc dendrite growth and interfacial reactions. Furthermore, anode-free batteries have smaller size and mass, which can significantly improve the energy density of the new battery.

[0004] However, research on electrodeless batteries is still in its infancy, and the few existing methods mainly involve forming a zinc layer or zinc-affinity layer on existing current collectors. For example, Chinese patent document CN113013496A discloses a high-safety, low-cost electrodeless zinc battery and its application, wherein the electrodeless zinc battery consists of a positive current collector, a positive electrode, a separator, an electrolyte, and a negative current collector.

[0005] Chinese patent document CN115764005A discloses a high-performance, electrodeless, aqueous zinc metal battery based on a composite layered negative electrode current collector, comprising the steps of: coating a conductive layer on the surface of a zinc metal deposition substrate; preparing a guiding layer solvent and coating it onto the conductive layer using a coating method, and then drying it in an oven. For example, publication number... Chinese patent document CN113036152A discloses a negative electrode-free zinc metal battery using a zwitterionic polymer as a binder. This negative electrode-free zinc metal battery is assembled from a positive electrode, a separator, a negative electrode current collector loaded with a zwitterionic polymer binder, and an electrolyte. CN113036152A discloses a high-energy-density, high-safety negative electrode-free zinc metal battery, its preparation method, and its applications. This zinc metal battery uses a negative electrode current collector with a zinc-loving layer, which is one or more of a zinc-loving ionic, electronic, or mixed-ionic conductor layer.

[0006] In summary, the prior art discloses a few no-negative zinc batteries with a small number of digits, but the prior art still needs to face the steps of hydrogen evolution reaction, dendrite growth, dead zinc evolution, insufficient energy density, and the research on cycle stability, especially low temperature stability, is still in the industry blank. SUMMARY

[0007] In view of the problems of hydrogen evolution reaction, dendrite growth, dead zinc evolution, insufficient energy density, and low temperature performance of no-negative zinc metal batteries during the cycle process, the first object of the present application is to provide a preparation method of a zinc-P1 / P2 double-layer composite fiber electrode suitable for the characteristics of no-negative zinc batteries, and to improve the performance of the prepared material in no-negative zinc batteries.

[0008] The second object of the present application is to provide the zinc-P1 / P2 double-layer composite fiber electrode prepared by the preparation method and its application in no-negative zinc metal batteries.

[0009] The third object of the present application is to provide a no-negative zinc metal battery comprising the zinc-P1 / P2 double-layer composite fiber electrode.

[0010] Compared with zinc ion batteries using zinc metal, no-negative batteries have the advantages of low cost, high mass energy density, and high volume energy density, but the key problem is the poor reversibility and poor kinetics of zinc ions on the negative side, which leads to poor wide temperature range rate performance. In view of this problem, the present application provides the following solutions after research:

[0011] A preparation method of a zinc-P1 / P2 double-layer composite fiber electrode, a spinning solution A in which zinc salt and polymer P1 are dissolved is obtained, and a spinning solution B in which polymer P2 is dissolved is obtained;

[0012] The first stage of electrospinning is performed using the spinning solution A to prepare a zinc-P1 layer; the second stage of electrospinning is performed using the spinning solution B with the zinc-P1 layer as the substrate to form a P2 layer on the surface of the zinc-P1 layer, and then the drying treatment is performed to obtain the zinc-P1 / P2 double-layer composite fiber electrode.

[0013] The present application innovatively forms the zinc-P1 layer (three-dimensional framework layer 1) based on electrospinning means, and further uses it as a substrate to form the P2 layer (three-dimensional framework layer 2) on its surface based on electrospinning means, wherein the P2 layer under the action of electrospinning gives the double-layer material a good intermingled interface. The present application research shows that based on the two-stage electrospinning means, combined with the joint control of the spinning solution composition, a good hierarchical fusion interface can be formed, which helps to reduce the hierarchical impedance, adapt to the problems faced by no-negative zinc batteries, reduce the hydrogen evolution reaction, dendrite growth, dead zinc evolution, and insufficient energy density, and effectively improve the performance of the prepared material in no-negative zinc batteries, especially the low temperature performance.

[0014] The zinc salt is one or more of zinc chloride, zinc triflate, zinc sulfate, bis-trifluoromethanesulfonate zinc, zinc acetate, zinc perchlorate; preferably at least one of zinc triflate and bis-trifluoromethanesulfonate zinc. Studies have shown that, based on the two-stage spinning process, further optimization control of the zinc salt helps to further improve the low-temperature performance of the prepared material in the zinc-free negative electrode battery.

[0015] In the present application, the polymer P1 and the polymer P2 are each one or more of polyacrylonitrile PAN, polyacrylic acid PAA, and polyvinylpyrrolidone PVP.

[0016] Preferably, the polymer P1 and the polymer P2 are different polymers. Further preferably, the polymer P1 is PAN and the polymer P2 is PAA. Based on the two-stage spinning process, further optimization control of the polymers P1 and P2 helps to further improve the interface physicochemical structure and helps to further improve the low-temperature performance of the prepared material in the zinc-free negative electrode battery.

[0017] In the present application, the solvent in the spinning solution A and the spinning solution B includes one or more of N,N-dimethylformamide DMF and N,N-dimethylacetamide DMA.

[0018] Preferably, the solvent in the spinning solution A is DMF and the solvent in the spinning solution B is DMA. Based on the two-stage spinning process, further optimization control of the solvent helps to further improve the interface physicochemical structure and helps to further improve the low-temperature performance of the prepared material in the zinc-free negative electrode battery.

[0019] Preferably, in the spinning solution A, the zinc salt content is 5-30 wt.%, and further can be 10-25 wt.%; the polymer P1 content is 1-40 wt.%, and further can be 10-25 wt.%. The zinc salt content refers to the weight content of the zinc salt relative to the solvent. The polymer P1 content refers to the weight percentage of the polymer P1 relative to the solvent.

[0020] Preferably, in the spinning solution B, the polymer P2 content is 5-50 wt.%, and further can be 10-25 wt.%. The polymer P2 content refers to the weight percentage of the polymer P2 relative to the solvent.

[0021] In the present application, the voltage for electrospinning is 12-18 kV, and further can be 14-16 kV.

[0022] Preferably, the thickness of the zinc-P1 layer is 20-100 μm, further can be 40-60 μm; the thickness of the P2 layer is 200-700 μm, further can be 300-500 μm, further can be 350-450 μm. Research shows that, under the preferred thickness, the synergy of the structure can be further strengthened, and the low-temperature cycle performance can be further improved.

[0023] In the present application, the rate of the first-stage electrospinning and the second-stage electrospinning is 0.01-0.05 mm / min -1 . Preferably, the spinning speed of the first-stage electrospinning is 0.01-0.03 mm / min -1 , the spinning speed of the second-stage electrospinning is 0.03-0.05 mm / min -1 , and the rate of the second-stage electrospinning is 1.5-2.5 times of the rate of the first-stage electrospinning. Research shows that, under the combined control of the preferred spinning rate, the hierarchical synergy can be further strengthened, and the low-temperature and wide-temperature stability of the prepared material can be further improved.

[0024] In the present application, the drying temperature is 45-70℃.

[0025] The present application also provides a zinc-P1 / P2 double-layer composite fiber electrode prepared by the preparation method.

[0026] The material of the present application comprises a zinc-P1 layer and a P2 layer compounded on the surface thereof; wherein the zinc-P1 layer is a fiber layer in which polymer P1 fibers interlaced with zinc salt are dispersed; the P2 layer is a fiber layer in which polymer P2 fibers are interlaced, and there is a special intermingled interface between the two fiber layers. Research shows that, the material prepared by the preparation method can unexpectedly adapt to the application requirements of the negative-electrode-free zinc battery, and can unexpectedly improve the structural stability, especially the low-temperature stability.

[0027] The present application also provides an application of the zinc-P1 / P2 double-layer composite fiber electrode prepared by the preparation method, which is used for preparing a negative-electrode-free zinc battery.

[0028] Preferably, the zinc-P1 / P2 double-layer composite fiber electrode and the positive electrode are compounded to form an electric core of the negative-electrode-free zinc battery, wherein the surface of the P2 layer of the zinc-P1 / P2 double-layer composite fiber electrode is close to the positive electrode side.

[0029] The positive electrode can be a material known in the industry, for example, the positive electrode active material therein can be one or more of manganese dioxide, vanadium pentoxide, and ammonium vanadate.

[0030] The non-negative zinc battery also comprises an aqueous electrolyte. The electrolyte in the aqueous electrolyte includes one or more of a solution of zinc chloride ZnCl2, zinc triflate Zn(CF3SO3)2, zinc sulfate ZnSO4, bis-trifluoromethanesulfonate zinc Zn(TFSI)2, zinc acetate Zn(CH3COO)2, zinc perchlorate Zn(ClO4)2, etc.

[0031] In the present application, the battery does not need to contain a zinc negative electrode or a negative electrode containing zinc metal.

[0032] The present application also provides a non-negative zinc battery, comprising a battery core compounded by a zinc-P1 / P2 double-layer composite fiber electrode and a positive electrode, and an electrolyte soaked in the battery core, wherein the P2 layer surface of the zinc-P1 / P2 double-layer composite fiber electrode is close to the positive electrode side.

[0033] Advantages

[0034] The present application is based on the combination of the two-stage electrospinning and the process, which can improve the adaptability of the prepared material in the non-negative zinc battery, and effectively improve the performance of the prepared material in the non-negative zinc battery, especially the low temperature performance.

[0035] The present application further controls the combination of the polymers P1 and P2, zinc salt and two-stage spinning process, which can further strengthen the hierarchical interface and structure of the material, and help to further improve the performance of the prepared material in the non-negative zinc battery. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The cycle performance graph of the full battery of Example 1 and Comparative Example 1 at 25℃;

[0037] Figure 2 The cycle performance graph of the full battery of Example 1 and Comparative Example 1 at-20℃;

[0038] Figure 3 The cycle performance graph of the symmetric battery of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0039] An alternative preparation method of the zinc-P1 / P2 double-layer composite fiber electrode of the present application is as follows:

[0040] I. Dissolve the organic solvent, polymer P1 and zinc salt to obtain spinning solution A; dissolve the organic solvent and polymer P2 to obtain spinning solution B,

[0041] II. Use electrospinning method to spin the spinning solution A to the surface of the aluminum foil, control the thickness by spinning time, and obtain the first layer material (zinc-P1 layer);

[0042] III. Then, the spinning solution B is spun onto the surface of the first layer of material to form a P2 layer;

[0043] IV. The obtained spinning layer is dried at high temperature, and after stripping the aluminum, a zinc-P1 / P2 double-layer composite fiber electrode is obtained.

[0044] The organic solvent in step I is one or more of N,N-dimethylformamide DMF, N,N-dimethylacetamide DMA, etc.

[0045] The polymer P1 in step I is one or more of polyacrylonitrile PAN, polyacrylic acid PAA, polyvinylpyrrolidone PVP, etc.

[0046] The mass ratio of the polymer P1 and the organic solvent in step I is (0.01-0.5):1, and further can be 0.1-0.2:1.

[0047] The zinc salt in step I is one or more of zinc chloride ZnCl2, zinc triflate Zn(CF3SO3)2, zinc sulfate ZnSO4, bis-trifluoromethanesulfonate zinc Zn(TFSI)2, zinc acetate Zn(CH3COO)2, zinc perchlorate Zn(ClO4)2, etc.

[0048] The molar amount of the zinc salt in step I is (0.1-3):1 of the total mass of the mixed solution B, and further can be 0.1-0.2:1.

[0049] The electrostatic spinning voltage in steps II and III is 12-18 kV, the spinning speed is 0.01-0.05 mm / min -1 , the spinning thickness is 0.01-50 μm, and the higher the spinning voltage, the slower the spinning speed can be.

[0050] The spinning time of step II is 2-4 h, or the spinning thickness is controlled to be 20-100 μm; the spinning time of step III is 5-20 h, or the spinning thickness is controlled to be 200-700 μm.

[0051] The drying temperature in step IV is 45-70℃, air atmosphere, and air blowing drying.

[0052] In the present application, the raw materials can be commercially available components known in the field of zinc batteries.

[0053] Example 1

[0054] Step 1: the mass ratio of the controlled polymer P1 (polyacrylonitrile PAN) to the solvent (N,N-dimethylformamide DMF) is 0.11:1, and a certain amount of zinc triflate Zn(CF3SO3)2 is added to the mixed solution to make the zinc salt 14wt.% of the weight of the solvent, to obtain a spinning solution A;

[0055] The polymer P2 (polyacrylic acid PAA) is mixed with N,N-dimethylacetamide DMA to form a spinning solution B, wherein the weight ratio of the polymer P2 to the solvent is 0.11:1;

[0056] Step 2: the spinning solution A is spun onto the surface of an aluminum foil by an electrostatic spinning method, the spinning voltage is controlled at 15kV, the spinning speed is 0.02ml min -1 , and the spinning thickness is 50μm, to form a first fiber layer (Z surface);

[0057] Step 3: the spinning solution B is further spun on the first fiber layer (Z surface) to form a second fiber layer (G surface), wherein the spinning voltage is 15kV, the spinning speed is 0.04ml min -1 , and the spinning thickness is 400μm, and after the double-layer spinning material is dried at 50℃, the aluminum foil is peeled off to obtain a double-layer material.

[0058] V2O5 is used as the positive electrode, and the mass ratio of V2O5:carbon black:PVDF is 7:2:1, which is uniformly mixed to form a slurry, which is uniformly coated on a titanium foil, and the titanium foil is cut into a positive electrode sheet with a diameter of 12mm, and the double-layer material is used as the electrode sheet and the positive electrode sheet (the G surface is close to the positive electrode sheet), and the CR2025 type button cell is assembled in the air, which is the full cell of Example 1. The double-layer material is assembled into a symmetrical battery (two pieces of the double-layer material are used as electrodes, and the G surfaces of the two pieces of the double-layer material are close to each other), which is the half cell of Example 1. The electrolyte of the full cell and the half cell is 1M zinc sulfate aqueous solution.

[0059] Comparative Example 1

[0060] Compared with the full cell and the half cell of Example 1, the difference is that the zinc metal is used to replace the double-layer material as the negative electrode in the battery of the present application, and on this basis, a conventional separator (such as a PAN separator with a thickness of 450±10μm) is arranged between the electrodes, and the CR2025 type button cell is assembled under the same conditions.

[0061] The above batteries are tested for charge and discharge cycles under the same test equipment and test conditions, wherein the voltage range of the battery test is 0.2~1.6V, and the test temperature is 25℃ and -20℃, such as Figure 1, the first discharge capacity of the battery of Example 1 is 260 mAh / g at 25℃, and the capacity retention rate is 57% after 1000 cycles, the discharge capacity of Comparative Example 1 is 223 mAh / g, and the discharge capacity is 10% after 1000 cycles;

[0062] Figure 2 The initial discharge capacity of Example 1 shown in the figure is 125 mAh / g at -20℃, and the discharge capacity of the comparative battery is 78 mAh / g under the same conditions, Figure 3 The symmetrical battery of Example 1 shows more than 1100 hours of cycle at -20℃, and Comparative Example 1 short-circuits after 400 hours of cycle.

[0063] Example 2

[0064] Compared with Example 1, the only difference is that the zinc salt is bis-trifluoromethanesulfonyl zincate Zn(TFSI)2, and the mass ratio is unchanged. Other operations, parameters and tests are the same as Example 1, and the results are as follows:

[0065] The first discharge capacity is 252 mAh / g at 25℃, and the capacity retention rate is 53% after 1000 cycles. The initial discharge capacity is 118 mAh / g at -20℃, and the symmetrical battery is cycled for 900 hours.

[0066] Example 3

[0067] Compared with Example 1, the only difference is that the organic solvent of solution A (spinning solution A) is N,N-dimethylacetamide DMA, and the organic solvent of solution B (spinning solution B) is DMF, and the mass ratio is unchanged. Other operations, parameters and tests are the same as Example 1, and the results are as follows:

[0068] The first discharge capacity is 251 mAh / g at 25℃, and the capacity retention rate is 54% after 1000 cycles. The initial discharge capacity is 116 mAh / g at -20℃, and the symmetrical battery is cycled for 920 hours.

[0069] Example 4

[0070] Compared with Example 1, the only difference is that the polymer P1 is polyacrylic acid PAA, and the polymer P2 is PAN, and the mass ratio is unchanged. Other operations, parameters and tests are the same as Example 1, and the results are as follows:

[0071] The first discharge capacity is 248 mAh / g at 25℃, and the capacity retention rate is 50% after 1000 cycles. The initial discharge capacity is 112 mAh / g at -20℃, and the symmetrical battery is cycled for 880 hours.

[0072] Example 5

[0073] The difference compared with Example 1 is that the zinc salt is 20wt.% of the solvent weight of the spinning solution A. The first discharge capacity at 25°C is 256mAh / g, and the capacity retention rate after 1000 cycles is 52%. The initial discharge capacity at -20°C is 117mAh / g, and the symmetric battery cycle is 990 hours.

[0074] Example 6

[0075] The difference compared with Example 1 is that the Z face thickness is 100 microns. Other operations, parameters and tests are the same as Example 1, and the results are:

[0076] The first discharge capacity at 25°C is 249mAh / g, and the capacity retention rate after 1000 cycles is 52%. The initial discharge capacity at -20°C is 120mAh / g, and the symmetric battery cycle is 1000 hours.

[0077] Example 7

[0078] The difference compared with Example 1 is that the G face thickness is 700 microns. Other operations, parameters and tests are the same as Example 1, and the results are:

[0079] The first discharge capacity at 25°C is 238mAh / g, and the capacity retention rate after 1000 cycles is 47%. The initial discharge capacity at -20°C is 108mAh / g, and the symmetric battery cycle is 860 hours.

[0080] Example 8

[0081] The difference compared with Example 1 is that the two-stage spinning speed is 0.03ml / min. Other operations, parameters and tests are the same as Example 1, and the results are:

[0082] The first discharge capacity at 25°C is 259mAh / g, and the capacity retention rate after 1000 cycles is 54%. The initial discharge capacity at -20°C is 118mAh / g, and the symmetric battery cycle is 990 hours.

[0083] Example 9

[0084] The difference compared with Example 1 is that the polymers in the spinning solution A and the spinning solution B are changed, and the experimental groups are:

[0085] Group A: The polymers in the spinning solution A and the spinning solution B are both the PAN, and other operations and parameters are the same as Example 1.

[0086] Group B: The polymers in the spinning solution A and the spinning solution B are both the PAA, and other operations and parameters are the same as Example 1.

[0087] The tests are carried out according to the method of Example 1, and the results are:

[0088] Group A: the first discharge capacity at 25℃ cycle is 239mAh / g, and the capacity retention rate is 45% after 1000 cycles. The initial discharge capacity at -20℃ is 105mAh / g, and the symmetric battery cycle is 845 hours.

[0089] Group B: the first discharge capacity at 25℃ cycle is 236mAh / g, and the capacity retention rate is 46% after 1000 cycles. The initial discharge capacity at -20℃ is 108mAh / g, and the symmetric battery cycle is 860 hours.

[0090] Example 10

[0091] Compared with Example 1, the only difference is that the content of spinning solution A polymer P1 is 15wt.%, and the content of spinning solution B polymer P2 is 18wt.%; the voltage of two-stage electrospinning is 16kv, and other operations and parameters are the same as Example 1.

[0092] The first discharge capacity at 25℃ cycle is 259mAh / g, and the capacity retention rate is 55% after 1000 cycles. The initial discharge capacity at -20℃ is 121mAh / g, and the symmetric battery cycle is 1090 hours.

[0093] Comparative Example 2

[0094] Compared with Example 1, after the spinning in step 2 is completed, the first fiber material is obtained by drying; in step 3, an aluminum foil is used as the substrate, and the second fiber material is formed by using the conditions in step 3; the first fiber material and the second fiber material are assembled according to the structure relationship in Example 1 to obtain a battery, and the battery is tested. The first discharge capacity at 25℃ cycle is 186mAh / g, and the capacity retention rate is 42% after 1000 cycles. The initial discharge capacity at -20℃ is 96mAh / g, and the symmetric battery cycle is 780 hours.

[0095] Comparative Example 3

[0096] Compared with Example 1, the only difference is that the spinning solution in step 2 is spinning solution B, and other operations and parameters are the same as Example 1. The first discharge capacity at 25℃ cycle is 223mAh / g, and the capacity retention rate is 41% after 1000 cycles. The initial discharge capacity at -20℃ is 98mAh / g, and the symmetric battery cycle is 810 hours.

Claims

1. A method for preparing a zinc-P1 / P2 double-layer composite fiber electrode for a negative electrode-free zinc battery, characterized by, obtain a spinning solution A dissolving zinc salt and polymer P1, and obtain a spinning solution B dissolving polymer P2; perform the first-stage electrospinning using the spinning solution A to obtain a zinc-P1 layer; perform the second-stage electrospinning using the spinning solution B on the basis of the zinc-P1 layer to form a P2 layer on the surface of the zinc-P1 layer, and then perform drying treatment to obtain the zinc-P1 / P2 double-layer composite fiber electrode; the zinc salt is one or more of zinc chloride, zinc trifluoromethanesulfonate, zinc sulfate, bis-trifluoromethanesulfonyl zinc, zinc acetate, and zinc perchlorate; the polymer P1 and the polymer P2 are one or more of polyacrylonitrile (PAN), polyacrylic acid (PAA), and polyvinylpyrrolidone (PVP).

2. The production method according to claim 1, wherein the zinc salt is at least one of zinc trifluoromethanesulfonate and bis-trifluoromethanesulfonyl zinc.

3. The production method according to claim 1, wherein the polymer P1 and the polymer P2 are different polymers.

4. The production method according to claim 1, wherein the polymer P1 is PAN, and the polymer P2 is PAA.

5. The production method according to claim 1, wherein the solvent in the spinning solution A and the spinning solution B includes one or more of N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA).

6. The production method according to claim 1, wherein the solvent in the spinning solution A is DMF, and the solvent in the spinning solution B is DMA.

7. The production method according to claim 1, wherein in the spinning solution A, the content of the zinc salt is 5-30 wt.% and the content of the polymer P1 is 1-40 wt.%.

8. The production method according to claim 1, wherein in the spinning solution A, the content of the zinc salt is 10-25 wt.% and the content of the polymer P1 is 10-25 wt.%.

9. The production method according to claim 1, wherein in the spinning solution B, the content of the polymer P2 is 5-50 wt.%.

10. The production method according to claim 1, wherein the voltage for electrospinning is 12-18 kV.

11. The production method according to claim 1, wherein the thickness of the zinc-P1 layer is 20-100 μm, and the thickness of the P2 layer is 200-700 μm.

12. The production method according to claim 1, wherein The way rate of the first electrospun segment and the second electrospun segment is 0.01-0.05 mm min -1 .

13. The production method according to claim 1, wherein The spinning speed of the first-stage electrostatic spinning is 0.01~0.03 ml min -1 The spinning speed of the second-stage electrostatic spinning is 0.03~0.05 ml min -1 , and the speed of the second-stage electrostatic spinning is 1.5~2.5 times of the speed of the first-stage electrostatic spinning.

14. The production method according to claim 1, wherein the temperature for drying is 45-70 °C.

15. A zinc-P1 / P2 double-layer composite fiber electrode prepared by the preparation method in any one of claims 1-14.

16. Use of a zinc-P1 / P2 double layer composite fiber electrode prepared by the method of any one of claims 1 to 14. The zinc-P1 / P2 double-layer composite fiber electrode is used to prepare a negative-electrode-free zinc battery.

17. The use according to claim 16, wherein The zinc-P1 / P2 double-layer composite fiber electrode and a positive electrode are combined to form an electric cell of the negative-electrode-free zinc battery, without adding a separator, wherein the surface of the P2 layer of the zinc-P1 / P2 double-layer composite fiber electrode is close to the positive electrode side.

18. The use according to claim 17, wherein The negative-electrode-free zinc battery further comprises an aqueous electrolyte.

19. A negative electrode-free zinc battery, characterized in that, An electric cell comprising a zinc-P1 / P2 double-layer composite fiber electrode prepared by the preparation method in any one of claims 1-14 and a positive electrode, and an electrolyte soaked in the electric cell, wherein the surface of the P2 layer of the zinc-P1 / P2 double-layer composite fiber electrode is close to the positive electrode side.

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