Conductive film for zinc secondary battery, preparation method thereof, composite separator for zinc secondary battery, and zinc secondary battery

Abstract

This application relates to the field of battery technology, and specifically relates to a conductive film for a zinc secondary battery, a preparation method thereof, a composite separator for a zinc secondary battery, and a zinc secondary battery. The conductive film for a zinc secondary battery of this application includes a porous polymer film, and the pores of the porous polymer film are filled with a conductive composition. The conductive composition includes the following components in parts by weight: 1-10 parts of a conductive agent and 0.1-1 part of an additive. The conductive agent is at least one of graphite, conductive carbon black, acetylene black, graphene, carbon nanotubes, and copper powder; the additive is at least one of tin powder, tin dioxide powder, bismuth powder, bismuth oxide powder, indium powder, indium oxide powder, lead powder, lead oxide powder, cadmium powder, and cadmium oxide powder. The composite separator for a zinc secondary battery of this application is wrapped around the outer periphery of the battery cell, and can solve the problem that the existing conductive tin-plated copper foil cannot be welded to the battery separator.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a conductive film for a zinc secondary battery and a preparation method thereof, a composite diaphragm for a zinc secondary battery, and a zinc secondary battery. Background Art

[0002] Zinc is an excellent battery material, and numerous battery types have been developed around it, including nickel-zinc secondary batteries, manganese-zinc secondary batteries, and zinc-ion secondary batteries. However, these zinc secondary batteries all suffer from the following problem: during charging, the zinc in the negative electrode forms dendrites, which can pierce the separator or react with the metal in the battery casing.

[0003] Furthermore, direct contact between the negative electrode in the battery cell and the metal shell can also cause a reaction, generating large amounts of gas or corroding the metal shell. To prevent the negative electrode from reacting with the metal shell, the prior art employs a method of wrapping the battery cell with a layer of metal, which not only provides conductivity but also prevents the negative electrode from reacting with the shell. For example, Chinese utility model patent No. CN214477788U discloses a composite separator for a wound battery, comprising a separator, one end of which is bonded to an adhesive tape. The tape comprises a separator bonding portion, a separator portion, and a conductive bonding portion, which are sequentially arranged along the length of the tape. The separator bonding portion is bonded to one side of the corresponding end of the separator, and a conductive foil is bonded to the conductive bonding portion. The conductive foil is a metal foil, a graphite film, or a graphene film. The separator portion is used to bond to the surface of the corresponding electrode. However, separators are generally polymer films, and the conductive foil on the composite separator has poor compatibility with the separator, resulting in a weak connection. Summary of the Invention

[0004] In order to improve the connection effect between the external conductor of the battery cell and the polymer film, the present application provides a conductive film for a zinc secondary battery and a preparation method thereof, a composite separator for a zinc secondary battery, and a zinc secondary battery.

[0005] A conductive film for a zinc secondary battery comprises a porous polymer film, wherein the pores of the porous polymer film are filled with a conductive composition, wherein the conductive composition comprises the following components in parts by weight: 1-10 parts of a conductive agent and 0.1-1 parts of an additive, wherein the conductive agent is at least one of graphite, conductive carbon black, acetylene black, graphene, and carbon nanotubes; and the additive is at least one of tin powder, tin dioxide powder, bismuth powder, bismuth oxide powder, indium powder, indium oxide powder, lead powder, lead oxide powder, cadmium powder, and cadmium oxide powder.

[0006] The porous polymer membrane is any one of PVC membrane, PE membrane, PP membrane, PTFE membrane, SBR membrane and cellulose acetate membrane.

[0007] The additive is composed of a first additive and a second additive mixed in a mass ratio of 1 - 5:0.2 - 3; the first additive is at least one of tin powder, bismuth powder, indium powder, lead powder, and cadmium powder; the second additive is at least one of tin dioxide powder, bismuth oxide powder, indium oxide powder, lead oxide powder, and cadmium oxide powder.

[0008] The particle size of the additive is 10 - 500 nm. The particle size of the first additive is 10 - 100 nm, and the particle size of the second additive is 20 - 500 nm.

[0009] The pore size of the porous polymer membrane is 100 - 800 nm, and more preferably 500 - 800 nm.

[0010] The mass ratio of the porous polymer membrane to the conductive composition is 1:0.02 - 0.2.

[0011] The thickness range of the conductive film is 0.02 - 3.0 mm. When the thickness approaches 3.0 mm, the conductive film is actually a conductive plate. Preferably, it is 0.05 - 2.0 mm.

[0012] A method for preparing a conductive film for a zinc secondary battery includes the following steps:

[0013] 1) Mix the conductive composition and the solvent evenly to obtain a conductive paste; the solvent is at least one of water, NMP, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, carbonate solvents, and carboxylic acid esters;

[0014] 2) Spread the conductive paste in step 1) on the surface of the porous polymer membrane and dry it to obtain the conductive film; or immerse the porous polymer membrane in the conductive paste in step 1), take it out and dry it to obtain the conductive film.

[0015] In step 1), the even mixing is carried out by stirring at a rotation speed of 800 - 3000 rpm for 5 - 50 min. The rotation speed is preferably 1000 - 2000 rpm. The stirring time is preferably 10 - 30 min.

[0016] The dosage of the solvent is 10 - 100 mL of solvent per 1 g of the conductive agent.

[0017] In step (2), when applying the conductive paste on the surface of the porous polymer membrane, first lay the porous polymer membrane flat on the surface of the anti-seepage membrane or anti-seepage plate, then coat the conductive paste on the side of the porous polymer membrane facing away from the anti-seepage membrane or anti-seepage plate, and then scrape on the surface coated with the conductive paste for 0.5 - 10 minutes. Preferably, the scraping time is 1 - 3 minutes. A scraper or a squeegee is used for scraping. Further, after scraping on one surface, turn over the porous polymer membrane, attach the anti-seepage membrane or anti-seepage plate to the surface where the conductive paste has been scraped, then coat the conductive paste on the other surface, and then scrape on the surface coated with the conductive paste for 0.5 - 10 minutes. Preferably, the scraping time is 1 - 3 minutes.

[0018] In step (2), the soaking time of the porous polymer membrane is 10 - 300 minutes.

[0019] A preparation method of a conductive film for a zinc secondary battery, comprising the following steps: uniformly mixing polymer particles, an antioxidant, a conductive composition, and a pore-forming agent, extruding, casting, longitudinal stretching, transverse stretching, removing the pore-forming agent, and washing to obtain; the polymer particles are polyethylene particles or polypropylene particles.

[0020] The molecular weight of the polyethylene or polypropylene is not less than 1 million.

[0021] The antioxidant is at least one of tert-butylhydroquinone and 4,4'-thiobis(6-tert-butyl-m-cresol).

[0022] The pore-forming agent is any one of white oil, n-heptane, and paraffin.

[0023] The mass ratio of the polymer particles, antioxidant, conductive agent, additive, and pore-forming agent is 70 - 95:8 - 10:5 - 15:10 - 20.

[0024] After casting, a thick sheet is obtained, and the thickness of the thick sheet is 400 - 800 μm.

[0025] The temperature during longitudinal stretching is 100 - 120 °C.

[0026] The temperature during transverse stretching is 110 - 125 °C.

[0027] When removing the pore-forming agent, dichloromethane extraction is used.

[0028] The temperature during extrusion is 180 - 230 °C.

[0029] A composite separator for a zinc secondary battery, comprising a matrix separator and the above-mentioned conductive film for a zinc secondary battery connected to one end of the matrix separator. [[ID=з8]]

[0030] The conductive film for zinc secondary batteries is connected to the base separator by heat fusion welding or ultrasonic welding. Heat fusion welding is a hot melt point or surface welding method. Ultrasonic welding is an ultrasonic point or surface welding method.

[0031] A zinc secondary battery comprises a battery core and the composite diaphragm for the zinc secondary battery wrapped around the outer periphery of the battery core.

[0032] The battery core comprises a positive electrode sheet, a separator and a negative electrode sheet, and the composite separator for the zinc secondary battery is laminated with the negative electrode sheet.

[0033] A zinc secondary battery comprises a shell and a battery core arranged in the shell, wherein the inner wall of the shell is laminated with the composite diaphragm for the zinc secondary battery.

[0034] The battery core is a cylindrical wound battery core or a square laminated battery core.

[0035] Beneficial effects:

[0036] The zinc secondary battery of the present application uses a composite diaphragm wrapped around the periphery of the battery core, which can solve the problem that the existing conductive tin-plated copper foil and the battery diaphragm cannot be welded.

[0037] The conductive film in the composite separator for zinc secondary batteries of the present application contains organic polymers, conductive agents, and additives, resulting in low resistance and good conductivity. The organic matter contained in the conductive film can also reduce heat generation during an external short circuit of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the structure of the composite diaphragm in Example 1.

[0039] Figure 2 Schematic diagram of the structure of the negative electrode sheet in other embodiments.

[0040] Figure 3 yes Figure 2 side view.

[0041] Figure 4 Schematic diagram of the structure of zinc secondary batteries in other embodiments.

[0042] Figure 5 yes Figure 4 A partial enlarged view of area A in the middle.

[0043] Figure 6 yes Figure 4 Top view of .

[0044] Figure 7 yes Figure 6 A partial enlarged view of area B in the middle. DETAILED DESCRIPTION

[0045] The technical solution of the present application will be described in detail below in conjunction with specific embodiments. In the following embodiments, unless otherwise specified, the raw materials used are commercially available products.

[0046] Example 1

[0047] The conductive film for zinc secondary battery in this embodiment includes a porous polymer film, and the porous polymer film is a porous polypropylene film. The pores of the porous polymer film are filled with a conductive composition. The conductive composition includes the following components by weight: 2 g of a conductive agent and 0.1 g of an additive. The conductive agent is conductive carbon black, and the additive is tin powder. The particle size of the conductive carbon black is 25 nm, and the particle size of the tin powder is 20 nm. The mass ratio of the porous polymer film to the conductive composition is 5:1.

[0048] The preparation method of the conductive film for zinc secondary battery in this embodiment includes the following steps:

[0049] 1) Mix the conductive agent, additive, and solvent, and stir evenly at a speed of 1500 rpm to obtain a conductive paste; the amount of the solvent used is 20 mL of the solvent for every 2 g of the conductive agent. The solvent in this embodiment is deionized water;

[0050] 2) Attach one side of the porous polypropylene film to the first glass plate, then place the side of the porous polypropylene film that is not in contact with the first glass plate facing up, coat the conductive paste on the upper surface of the porous polypropylene film, and scrape it back and forth with a scraper for 1 min;

[0051] Then attach the second glass plate to the upper surface of the porous polypropylene film, turn the porous polypropylene film over, place the side with the first glass plate attached facing up, peel off the first glass plate, then coat the conductive paste on this surface of the porous polypropylene film, and scrape it back and forth with a scraper for 1 min;

[0052] 3) Place the porous polypropylene film with the paste scraped on both sides in step 2) together with the second glass plate in a vacuum drying oven, dry it at 60 °C for 2 h, cool it, and take it out.

[0053] As Figure 1 shown, the composite separator in this embodiment includes a matrix separator 1, the matrix separator is a cellulose acetate film, one end of the matrix separator is connected to the above-mentioned conductive film 2 for zinc secondary battery, and one end of the conductive film for zinc secondary battery is laminated and melt-welded together with one end of the matrix separator to form a welded portion 3. The length of the matrix separator is 120 mm, the length of the conductive film for zinc secondary battery is 30 mm, the widths of the matrix separator and the conductive film for zinc secondary battery are both 42 mm, and the length of the laminated part of the matrix separator and the conductive film for zinc secondary battery is 5 mm.

[0054] The zinc secondary battery of this embodiment is a zinc-nickel battery, which includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. The positive electrode plate is a foamed nickel electrode. The negative electrode plate includes a negative current collector copper strip and a negative electrode material layer provided on the negative current collector. The negative electrode material layer includes a negative active material, a conductive agent, and a binder. The negative active material is a mixture composed of zinc oxide, calcium zincate, and zinc powder in a mass ratio of 60:10:22; the conductive agent is acetylene black; the binder is composed of CMC, polyvinyl alcohol, and PTFE in a mass ratio of 2.5:2:30. The mass ratio of zinc oxide, calcium zincate, zinc powder, acetylene black, CMC, polyvinyl alcohol, and PTFE is 60:10:22:6:0.025:0.02:0.3. The electrolyte is an electrolyte composed of a KOH solution with a mass concentration of 30% saturated with ZnO and a LiOH solution with a mass concentration of 2%. The separator is a special separator for zinc-nickel batteries.

[0055] Example 2

[0056] The conductive film for the zinc secondary battery of this embodiment includes a porous polymer film, and the porous polymer film is a porous polypropylene film. The pores of the porous polymer film are filled with a conductive composition. The conductive composition includes the following components by weight: 5 g of a conductive agent and 0.2 g of an additive. The conductive agent is conductive carbon black, and the additive is tin powder. The particle size of the conductive carbon black is 25 nm, and the particle size of the tin powder is 50 nm. The mass ratio of the porous polymer film to the conductive composition is 5:1.

[0057] The preparation method of the conductive film for the zinc secondary battery of this embodiment includes the following steps:

[0058] 1) Mix the conductive agent, the additive, and the solvent, and stir evenly at a speed of 1500 rpm to obtain a conductive paste; the amount of the solvent used is 50 mL of the solvent for every 5 g of the conductive agent. The solvent in this embodiment is deionized water;

[0059] 2) Attach one side of the porous polypropylene film to the first glass plate, then place the side of the porous polypropylene film that is not in contact with the first glass plate facing up, coat the conductive paste on the upper surface of the porous polypropylene film, and scrape it back and forth with a scraper for 1 min;

[0060] Then attach a second glass plate to the upper surface of the porous polypropylene film, flip the porous polypropylene film, place the side with the first glass plate attached facing up, peel off the first glass plate, then coat the conductive paste on this surface of the porous polypropylene film, and scrape it back and forth with a scraper for 1 min;

[0061] 3) Place the porous polypropylene film with the paste scraped on both sides in step 2) together with the second glass plate in a vacuum drying oven, dry it at 60 °C for 2 h, cool it, and take it out.

[0062] Others are the same as in Example 1.

[0063] Example 3

[0064] The conductive film for zinc secondary battery in this example comprises a porous polymer film, and the porous polymer film is a porous polypropylene film. The pores of the porous polymer film are filled with a conductive composition. The conductive composition comprises components in the following weights: 10 g of a conductive agent and 0.5 g of an additive. The conductive agent is conductive carbon black, and the additive is tin powder. The particle size of the conductive carbon black is 25 nm, and the particle size of the tin powder is 50 nm. The mass ratio of the porous polymer film to the conductive composition is 5:1.

[0065] The preparation method of the conductive film for zinc secondary battery in this example comprises the following steps:

[0066] 1) Mix the conductive agent, the additive and a solvent, and stir evenly at a speed of 1500 rpm to obtain a conductive paste; the amount of the solvent used is 90 mL of the solvent for every 10 g of the conductive agent. The solvent in this example is deionized water;

[0067] 2) Bond one side of the porous polypropylene film to a first glass plate, then place the side of the porous polypropylene film that is not in contact with the first glass plate facing upward, coat the conductive paste on the upper surface of the porous polypropylene film, and scrape it back and forth with a squeegee for 1 min;

[0068] Then bond a second glass plate to the upper surface of the porous polypropylene film, turn over the porous polypropylene film, place the side with the first glass plate attached facing upward, peel off the first glass plate, then coat the conductive paste on this surface of the porous polypropylene film, and scrape it back and forth with a squeegee for 1 min;

[0069] 3) Place the porous polypropylene film with the paste scraped on both sides in Step 2) together with the second glass plate in a vacuum drying oven, dry it at 60 °C for 2 h, cool it, and take it out.

[0070] Others are the same as in Example 1.

[0071] Example 4

[0072] The conductive film for zinc secondary battery in this example comprises a porous polymer film, and the porous polymer film is a porous cellulose film. The pores of the porous polymer film are filled with a conductive composition. The conductive composition comprises components in the following weights: 5 g of a conductive agent, 0.2 g of an additive and 0.1 g of a binder. The conductive agent is conductive carbon black, and the additive is tin powder. The particle size of the conductive carbon black is 25 nm, and the particle size of the tin powder is 50 nm. The binder is PVDF. The mass ratio of the cellulose film to the conductive composition is 5:1.

[0073] The preparation method of the conductive film for zinc secondary battery in this example comprises the following steps:

[0074] 1) Mix the binder and the solvent, stir evenly at a rotation speed of 1500 rpm to obtain a binder solution, then add the conductive agent and the additive, and stir evenly at a rotation speed of 1500 rpm to obtain a conductive paste; the amount of the solvent used is 50 mL of the solvent for every 5 g of the conductive agent, and the solvent in this example is N-methylpyrrolidone;

[0075] Steps 2) and 3) are the same as those in Example 2.

[0076] Others are the same as those in Example 2.

[0077] Example 5

[0078] The conductive film for a zinc secondary battery in this example includes a porous polymer film, and the porous polymer film is a porous cellulose film. The pores of the porous polymer film are filled with a conductive composition. The conductive composition includes the following components by weight: 5 g of a conductive agent, 0.2 g of an additive, and 0.1 g of a binder, wherein the conductive agent is conductive carbon black, the additive is a mixture of tin powder and tin dioxide, and the mass ratio of tin powder to tin dioxide is 1:1; the particle size of the conductive carbon black is 25 nm, the particle size of the tin powder is 50 nm, and the particle size of the tin dioxide is 20 nm. The binder is obtained by mixing PVDF and CMC in a mass ratio of 2:1. The mass ratio of the cellulose film to the conductive composition is 5:1.

[0079] The preparation method of the conductive film for a zinc secondary battery in this example includes the following steps:

[0080] 1) Mix the binder and the solvent, stir evenly at a rotation speed of 1500 rpm to obtain a binder solution, then add the conductive agent and the additive, and stir evenly at a rotation speed of 2000 rpm to obtain a conductive paste; the amount of the solvent used is 50 mL of the solvent for every 5 g of the conductive agent, and the solvent in this example is N-methylpyrrolidone;

[0081] Steps 2) and 3) are the same as those in Example 2.

[0082] Others are the same as those in Example 2.

[0083] Example 6

[0084] The conductive film for zinc secondary battery in this embodiment includes a porous polymer film, and the porous polymer film is a porous cellulose film. The pores of the porous polymer film are filled with a conductive composition. The conductive composition includes the following components by weight: 5 g of a conductive agent, 0.38 g of an additive, and 0.1 g of a binder. The conductive agent is conductive carbon black, and the additive is composed of a mixture of tin powder, tin dioxide, bismuth powder, and indium powder with a mass ratio of 1.5:1.5:0.5:0.3. The particle size of the conductive carbon black is 25 nm, the particle size of the tin powder is 50 nm, the particle size of the tin dioxide is 20 nm, the particle size of the bismuth powder is 50 nm, and the particle size of the indium powder is 60 nm. The binder is obtained by mixing PVDF and CMC in a mass ratio of 2:1. The mass ratio of the cellulose film to the conductive composition is 5:1.

[0085] The others are the same as in Example 5.

[0086] Example 7

[0087] The difference between this embodiment and Example 6 is that the additive is composed of a mixture of tin powder, tin oxide, bismuth oxide powder, indium powder, lead oxide, and cadmium oxide with a mass ratio of 1.5:1.2:0.5:0.3:0.2:0.1. The particle size of the tin powder is 50 nm, the particle size of the tin dioxide is 20 nm, the particle size of the bismuth oxide powder is 50 nm, the particle size of the indium powder is 60 nm, the particle size of the lead oxide is 100 nm, and the particle size of the cadmium oxide is 150 nm.

[0088] The others are the same as in Example 6.

[0089] Example 8

[0090] The conductive film for zinc secondary battery in this embodiment includes a porous polymer film, and the porous polymer film is a porous polyethylene film. The pores of the porous polymer film are filled with a conductive composition. The conductive composition includes the following components by weight: 5 g of a conductive agent and 0.38 g of an additive. The conductive agent is conductive carbon black, and the additive is composed of a mixture of tin powder, tin oxide, bismuth oxide powder, indium powder, lead oxide, and cadmium oxide with a mass ratio of 1.5:1.2:0.5:0.3:0.2:0.1. The particle size of the conductive carbon black is 25 nm, and the particle size of the tin powder is 50 nm.

[0091] The preparation method of the conductive film for zinc secondary battery in this embodiment includes the following steps: uniformly mixing ultra-high molecular weight polyethylene particles (molecular weight 1 million), 4,4-thiobis(6-tert-butyl-m-cresol), the conductive composition, and white oil in a mass ratio of 80:8:15:20, adding them into an extruder, heating and melting, extruding at 225 °C, casting, and obtaining a thick sheet with a thickness of 500 μm. Then, it is longitudinally stretched at 110 °C and transversely stretched at 115 °C, and the white oil is removed by extraction with dichloromethane, and then washed to obtain the product.

[0092] In other embodiments, the binder can also be replaced by at least one of PVA, PAAS, CMC, PEO, PVDF, PAN, HPMC, and SBR.

[0093] In other embodiments, as Figure 2 and Figure 3 shown, the negative electrode sheet includes the electrode sheet 11. One end of the negative electrode sheet is connected to the above-mentioned conductive film 22 for zinc secondary battery. One end of the conductive film for zinc secondary battery is laminated and fusion-welded or glued together with one end of the negative electrode sheet to form a welded portion 33. The negative electrode sheet is disposed on the outermost side of the battery cell, and the length of the conductive film for zinc secondary battery is set such that after winding, the conductive film for zinc secondary battery completely wraps the battery cell.

[0094] In other embodiments, as Figures 4 to 7 shown, the zinc secondary battery includes a metal casing 00 and a battery cell disposed within the metal casing. The metal casing is a cylindrical casing, and the inner wall is provided with the above-mentioned conductive film 01 for zinc secondary battery.

[0095] Experimental Examples

[0096] (1) Tensile Test

[0097] The composite separator for zinc secondary battery prepared in Examples 1-4 was taken for tensile test. The test results are shown in the following table.

[0098] Table 1 Comparison of Test Results of Composite Separators in Examples 1-4

[0099] Item Example 1 Example 2 Example 3 Example 4 Breaking strength (longitudinal) MPa ≥100 ≥100 ≥100 ≥100 Breaking strength (transverse) MPa ≥25 ≥25 ≥25 ≥25

[0100] As can be seen from the above table, the composite separator prepared by the present invention has a high breaking strength and good mechanical properties.

[0101] (2) Electrochemical Performance Test

[0102] The composite separator for zinc secondary battery prepared in Examples 1-4 was taken and wrapped around the outer peripheral surface of the battery cell to prepare a cylindrical zinc-nickel battery (AA 1000 mAh battery).

[0103] After the battery was activated at 0.2C, charged at 0.2C for 5 h, then the battery was left standing for 10 min, and then charged and discharged at 1C for testing. After 500 cycles, the test was terminated. The capacity retention rate was calculated.

[0104] Table 2 Comparison of Test Results of Zinc Secondary Batteries in Examples 1-4

[0105] Number of cycles Example 1 Example 2 Example 3 Example 4 The 1st time 1003 1014 1010 1010 The 100th time 989 997 1000 997 Capacity retention rate 98.6% 98.3% 99.0% 98.7% The 200th time 967 971 977 973 Capacity retention rate 96.4% 95.8% 96.7% 96.3% The 300th time 935 941 938 940 Capacity retention rate 93.2% 92.8% 92.9% 93.1% The 400th time 902 898 904 906 Capacity retention rate 89.9% 88.6% 89.5% 89.7% The 500th time 843 847 845 841 Capacity retention rate 84.1% 83.5% 83.7% 83.3%

[0106] As can be seen from the above table, the zinc secondary battery of the present invention has good high-rate discharge cycle performance and can still maintain a very high capacity retention rate after 500 cycles.

Claims

1. A composite separator for a zinc secondary battery, characterized in that, It includes a matrix separator and a conductive film for a zinc secondary battery connected to one end of the matrix separator; The conductive film for the zinc secondary battery includes a porous polymer film, and the pores of the porous polymer film are filled with a conductive composition. The conductive composition includes the following components in parts by weight: 1-10 parts of a conductive agent, 0.1-1 part of an additive. The conductive agent is at least one of graphite, conductive carbon black, acetylene black, graphene, and carbon nanotubes; The additive is composed of a first additive and a second additive mixed in a mass ratio of 1-5:0.2-3; the first additive is at least one of tin powder, bismuth powder, indium powder, lead powder, and cadmium powder; the second additive is at least one of tin dioxide powder, bismuth oxide powder, indium oxide powder, lead oxide powder, and cadmium oxide powder; The pore size of the porous polymer film is 500-800 nm; The mass ratio of the porous polymer film to the conductive composition is 1:0.02-0.2; The particle size of the first additive is 10-100 nm, and the particle size of the second additive is 20-500 nm.

2. The composite separator for a zinc secondary battery according to claim 1, wherein The preparation method of the conductive film for the zinc secondary battery includes the following steps: 1) Mix the conductive composition and a solvent evenly to obtain a conductive paste; the solvent is at least one of water, NMP, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, carbonate solvents, and carboxylic acid esters; 2) Spread the conductive paste obtained in step 1) on the surface of the porous polymer film and dry it to obtain the product; or immerse the porous polymer film in the conductive paste obtained in step 1), take it out and dry it to obtain the product.

3. The composite separator for zinc secondary battery according to claim 2, characterized in that, In step 1), the even mixing is carried out by stirring at a rotation speed of 800-3000 rpm for 5-50 min.

4. The composite separator for zinc secondary battery according to claim 2, characterized in that, When spreading the conductive paste on the surface of the porous polymer film in step 2), first lay the porous polymer film flat on the surface of an anti-seepage film or an anti-seepage plate, then coat the conductive paste on the side of the porous polymer film facing away from the anti-seepage film or the anti-seepage plate, and then scrape it on the surface coated with the conductive paste for 0.5-10 min.

5. A zinc secondary battery, characterized in that, It includes an electric core and the composite separator for the zinc secondary battery as described in claim 1 wrapped around the outer periphery of the electric core.

6. A secondary zinc battery, characterized in that, It includes a housing and an electric core arranged in the housing, and the inner wall of the housing is attached with the composite separator for the zinc secondary battery as described in claim 1.

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