Method for treating pole piece and pole lug

Abstract

The invention relates to the technical field of batteries, in particular to a method for treating a pole piece and a pole lug. The PET resin is prepared by adding the composite flame retardant, terephthalic acid, ethylene glycol and antimony trioxide and carrying out esterification reaction and polycondensation reaction. And mixing the PET resin, the silane coupling agent KH550, the silicon dioxide filler and the antioxidant 168, and treating to obtain the PET base film. And sequentially carrying out pretreatment and layer-by-layer self-assembly coating on the PET base film to obtain the modified PET base film. And plating the metal layers on the upper and lower surfaces of the modified PET base film to obtain the current collector. The current collector is used for preparing a pole piece, and the tab part of the pole piece is soaked in a dissolving reagent to obtain a pure metal tab. The prepared pole piece has good flame retardant property and antibacterial property, the welding time cost required by production can be reduced, and the thickness of the tab is reduced, so that the pole piece has a wide application prospect in the technical field of batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, in particular to a method for processing pole pieces and pole tabs. Background Art

[0002] As a core component of batteries, the modern value of battery electrodes is self-evident. In today's society, with the rapid advancement of technology and the continuous improvement of people's living standards, a wide range of electronic products are emerging. As the energy source for these products, batteries are becoming increasingly important. With the widespread adoption of products such as electric vehicles and smartphones, the battery industry is experiencing unprecedented development opportunities. As a core component in battery manufacturing, the market size of battery electrodes has naturally expanded accordingly. However, during use, batteries may catch fire or explode due to overheating, short circuits, or external physical damage. As a core component of batteries, excellent flame retardant properties in battery electrodes can effectively suppress fires and reduce the risk of accidents. In recent years, numerous safety incidents caused by battery failures have occurred in the market, resulting in not only property damage but also threats to human life. Therefore, improving the flame retardant properties of battery electrodes can significantly enhance battery safety and reduce potential safety hazards. During use, batteries may be exposed to microorganisms from various environments. The growth and reproduction of these microorganisms can negatively impact battery performance and even cause internal short circuits or other failures. By improving the antibacterial properties of battery electrodes, the invasion and reproduction of microorganisms can be effectively prevented, ensuring the long-term stability and safety of the battery.

[0003] In addition, with the pursuit of high specific energy in lithium-ion batteries, lightweighting has become a research focus. The current collector intermediate layer uses polymer materials instead of metals, which reduces the weight by 50% to 80% compared to pure metal current collectors. This can increase the battery's specific energy by 5% to 10%. If the current collector is to be used in a battery, it is necessary to first perform a transfer welding operation and weld the transfer body to the current collector using an ultrasonic welding machine to achieve circuit conductivity. Further improving the specific energy on this basis requires reducing the thickness of the transfer body and using thinner metal foil. However, for the current collector transfer welding technology, for example, for the positive electrode current collector, 12um or 13um thick aluminum foil is often used as the transfer body. If the thickness of the aluminum foil is further reduced to 9um or even thinner aluminum foil, the welded samples often have damage to the aluminum foil or current collector; the same is true for the negative electrode current collector.

[0004] In order to overcome the defects of the prior art, the present invention provides a method for processing pole pieces and tabs. Summary of the Invention

[0005] The object of the present invention is to provide a method for processing a pole piece and a pole tab to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for processing electrode tabs includes the following steps: clamping and fixing the electrode tabs, immersing the electrode tabs in a dissolving agent, which fully infiltrates and dissolves the polymer layer inside the tabs; air-drying the dissolved electrode tabs to obtain pure metal tabs, and then welding the tabs so that the metal conductive layers can be directly contacted without the need for additional transfer.

[0008] More optimally, the dissolving agent is a mixed solvent of phenol and tetrachloroethane or a hexafluoroisopropanol reagent.

[0009] A pole piece comprises the following steps: coating a metal layer on the upper and lower surfaces of a modified PET base film to obtain a current collector; then coating an active slurry on the surface of the current collector and drying it to obtain the pole piece; wherein the metal layer is a copper layer or an aluminum layer, and the coating thickness is 0.5-1.5 μm.

[0010] More optimally, the preparation process of the modified PET base film is as follows: Step S1: mixing the composite flame retardant, terephthalic acid, ethylene glycol, and antimony trioxide, and performing an esterification reaction at 220-250°C and 0.30-0.35 MPa for 3-4 hours, then increasing the temperature to 280-290°C and the pressure to 0.60-0.80 MPa for polycondensation reaction for 5-7 hours, and finally performing polycondensation at 0.06-0.08 MPa for 6-8 hours to obtain a PET resin;

[0011] Step S2: PET resin, silane coupling agent KH550, silica filler, and antioxidant 168 are mixed, extruded into a film, and biaxially stretched to obtain a PET base film; the PET base film is immersed in a 0.1-0.2 wt % polyethyleneimine solution for 5-8 minutes, dried, and then immersed in a 1-2 wt % polyacrylic acid solution for 5-8 minutes, and then dried to obtain a pretreated PET base film;

[0012] Step S3: adding dopamine-modified sodium alginate and carboxymethyl chitosan to deionized water respectively, ultrasonically treating for 40-60 minutes, then mixing the two solutions, and continuing ultrasonic treatment for 20-30 minutes to obtain a positive ion solution; adding sodium hexametaphosphate to deionized water, ultrasonically treating for 10-15 minutes to obtain a negative ion solution; immersing the pretreated PET base film in the positive ion solution for 1-2 minutes, drying it, and then immersing it in the negative ion solution for 1-2 minutes, repeating the above immersion steps of the positive ion solution and the negative ion solution 4-6 times to obtain a modified PET base film.

[0013] Preferably, in step S1, the contents of the components of the PET resin are as follows: in terms of parts by mass, 35 - 40 parts of a composite flame retardant, 400 - 450 parts of terephthalic acid, 220 - 250 parts of ethylene glycol, and 0.1 - 0.2 parts of antimony trioxide.

[0014] Preferably, in step S1, the preparation process of the composite flame retardant is as follows: dissolve aminobenzoic acid in a 1,4 - dioxane solvent, then add hexachlorocyclotriphosphazene and stir at 80 - 90 °C for 6 - 7 h to obtain a modified cyclotriphosphazene; then mix the modified cyclotriphosphazene and deionized water, and after mixing evenly, add magnesium hydroxide and react at 90 - 100 °C for 6 - 7 h to obtain the composite flame retardant; the reaction mass ratio of aminobenzoic acid, hexachlorocyclotriphosphazene, and magnesium hydroxide is (8 - 10):3.5:0.2.

[0015] Preferably, in step S2, the contents of the components of the PET base film are as follows: in terms of parts by mass, 120 - 140 parts of PET resin, 6 - 10 parts of silane coupling agent KH550, 8 - 10 parts of silica filler, and 2 - 3 parts of antioxidant 168.

[0016] Preferably, in step S3, the concentration of dopamine - modified sodium alginate in the positive ion solution is 0.008 - 0.009 g / mL, the concentration of carboxymethyl chitosan is 0.016 - 0.018 g / mL, and the concentration of sodium hexametaphosphate in the negative ion solution is 0.17 - 0.19 g / mL.

[0017] Preferably, in step S3, the preparation process of dopamine - modified sodium alginate is as follows: dissolve sodium alginate and sodium periodate in deionized water respectively, then slowly add the sodium periodate solution to the sodium alginate solution, stir and react at 25 - 30 °C for 6 - 8 h, then add ethylene glycol to terminate the reaction, and after the reaction is completed, dialyze and freeze - dry to obtain modified sodium alginate; under a nitrogen environment, dissolve the modified sodium alginate in deionized water, then add 1 - ethyl - 3 - (3 - dimethylaminopropyl)carbodiimide hydrochloride and N - hydroxysuccinimide, stir and react for 1.0 - 1.5 h and adjust the pH to 4.5 - 5.0, then add dopamine hydrochloride and continue to stir and react for 25 - 30 h, and after the reaction is completed, dialyze and freeze - dry to obtain dopamine - modified sodium alginate.

[0018] Preferably, the concentration of the sodium periodate solution is 0.10 - 0.15 g / mL, the concentration of the sodium alginate solution is 0.2 - 0.4 g / mL; the contents of the components of dopamine - modified sodium alginate are as follows: in terms of parts by mass, 1.0 - 1.5 parts of modified sodium alginate, 50 - 80 parts of deionized water, 1.0 - 1.5 parts of 1 - ethyl - 3 - (3 - dimethylaminopropyl)carbodiimide hydrochloride, 0.3 - 0.5 parts of N - hydroxysuccinimide, and 0.2 - 0.3 parts of dopamine hydrochloride.

[0019] The beneficial effects of the present invention:

[0020] The characteristics of the present invention are as follows. In step S1, by adding p-aminobenzoic acid and hexachlorocyclotriphosphazene, a modified cyclotriphosphazene is obtained; then the modified cyclotriphosphazene and magnesium hydroxide are mixed and reacted to obtain a composite flame retardant. In this step, first, a nucleophilic substitution reaction occurs between the amino group of p-aminobenzoic acid and the chloro group of hexachlorocyclotriphosphazene to obtain a modified cyclotriphosphazene with a carboxyl group, and then magnesium hydroxide is added to undergo a neutralization reaction to obtain the composite flame retardant. The modified cyclotriphosphazene in this composite flame retardant is an efficient flame retardant with good phosphorus-nitrogen synergistic effect. Phosphorus and nitrogen can promote the charring reaction during combustion, forming a dense char layer, thereby isolating oxygen and heat and inhibiting the further development of combustion. Magnesium hydroxide is a common inorganic flame retardant with an efficient heat absorption and cooling effect. At high temperatures, magnesium hydroxide decomposes into magnesium oxide and water, absorbing a large amount of heat, thereby reducing the surface temperature of the material and delaying the combustion process. At the same time, the decomposition products of magnesium hydroxide (magnesium oxide and water) can dilute the oxygen concentration in the combustion area and inhibit flame spread. Magnesium hydroxide also has good smoke suppression performance, which can reduce the smoke generated during combustion and lower the fire risk.

[0021] Furthermore, by adding the composite flame retardant, terephthalic acid, ethylene glycol and antimony trioxide, through esterification reaction and polycondensation reaction, a PET resin is prepared. By adding the composite flame retardant to this PET resin, a large number of flame retardant segments are introduced, and a PET resin with good flame retardant performance is obtained.

[0022] The characteristics of the present invention are as follows. In step S2, the PET resin, silane coupling agent KH550, silica filler and antioxidant 168 are mixed, and then extruded and cast into a film and biaxially stretched to obtain a PET base film. Then, pretreatment is carried out. The purpose of the pretreatment is to enhance the hydrophilicity and surface chemical activity of the PET base film by introducing functionalized amino and carboxyl groups, providing a basis for electrostatic interaction for subsequent layer-by-layer self-assembly, and finally realizing the preparation of a functional multi-layer film.

[0023] The features of the present invention are as follows. In step S3, the pretreated PET base film is repeatedly immersed in a positive ion solution and a negative ion solution for multiple times, and through layer-by-layer self-assembly coating, a modified PET base film is obtained. The solute of the positive ion solution is dopamine-modified sodium alginate and carboxymethyl chitosan, and these two substances can undergo a Schiff base reaction. The specific principle is as follows: The aldehyde group in dopamine-modified sodium alginate reacts with the amino group in carboxymethyl chitosan to form a Schiff base structure with good antibacterial activity. In addition, both dopamine molecules and carboxymethyl chitosan molecules themselves have good biological antibacterial properties. Therefore, through the synergistic effect of various substances, a positive ion solution with significant antibacterial performance is obtained. Through layer-by-layer self-assembly, these antibacterial components can be effectively deposited on the surface of the PET base film, thus significantly improving the antibacterial performance of the base film. The solute of the negative ion solution is sodium hexametaphosphate, and this component contains a large amount of phosphorus elements, which helps to promote the formation of residual carbon. These components can be deposited on the surface of the base film through layer-by-layer self-assembly to form a flame retardant coating, thereby improving the flame retardant performance of the entire base film.

[0024] A metal layer is plated on the upper and lower surfaces of the modified PET base film to obtain a current collector. Then, a pole piece is prepared using the current collector of the present invention. By immersing the tab portion of the pole piece into a dissolution reagent, the polymer layer inside the tab can be fully dissolved to obtain a pure metal tab. At this time, when welding the tab, there is no need to add a current collector for welding, which can reduce the time cost required for welding during production, reduce the thickness of the tab, and slightly reduce the weight of the pole piece, thereby improving the energy ratio. In summary, the pole piece prepared by the present invention has good flame retardant performance and antibacterial performance, and can also reduce the time cost required for welding during production and reduce the thickness of the tab. Therefore, it has broad application prospects in the field of battery technology. Detailed implementation mode

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] Source of raw materials:

[0027] Silica filler, provided by Lianyungang Haosen Mineral Products Co., Ltd., with a particle size of 300 mesh; polyethyleneimine, provided by Shanghai Hanluo New Materials Co., Ltd., model SP-018, with a molecular weight of 1800; polyacrylic acid, provided by Hubei Keward Chemical Co., Ltd., model 001, with a molecular weight of 72; sodium alginate, provided by Shanghai Zhongfeng Biotechnology Co., Ltd., with a particle size of 120 mesh; carbodiimide hydrochloride, provided by Shanghai McLean Biochemical Technology Co., Ltd., analytical grade; carboxymethyl chitosan, provided by Jiangsu Caiwei Biotechnology Co., Ltd., with a molecular weight of 543; in terms of mass, one portion is 1 g.

[0028] Example 1: A method for processing electrode tabs is as follows: the electrode is clamped and fixed, and the tab portion of the electrode is immersed in a dissolving reagent, which will fully infiltrate and dissolve the polymer layer inside the tab; the dissolved electrode is then air-dried to obtain a pure metal tab, and the tab is then welded, at which time the metal conductive layer can be directly contacted without the need for additional transfer; the dissolving reagent is a mixed solvent of phenol and tetrachloroethane.

[0029] Example 2: A method for processing electrode tabs is as follows: clamp and fix the electrode, and immerse the tab portion of the electrode in a dissolving reagent, which will fully infiltrate and dissolve the polymer layer inside the tab; then air-dry the dissolved electrode to obtain a pure metal tab, and then weld the tab. At this time, the metal conductive layer can be directly contacted without the need for additional transfer; the dissolving reagent is a hexafluoroisopropanol reagent.

[0030] Example 3: Step S1: dissolving aminobenzoic acid in 1,4-dioxane solvent, adding hexachlorocyclotriphosphazene, and stirring at 90°C for 7 hours to obtain a modified cyclotriphosphazene; then mixing the modified cyclotriphosphazene with deionized water, mixing evenly, adding magnesium hydroxide, and reacting at 100°C for 7 hours to obtain a composite flame retardant; wherein the reaction mass ratio of aminobenzoic acid, hexachlorocyclotriphosphazene, and magnesium hydroxide is 9:3.5:0.2;

[0031] 40 g of composite flame retardant, 400 g of terephthalic acid, 230 g of ethylene glycol and 0.2 g of antimony trioxide were mixed and subjected to esterification reaction at 250°C and 0.35 MPa for 4 h, and then the temperature was increased to 290°C and the pressure was increased to 0.80 MPa for polycondensation reaction for 7 h, and finally polycondensation was carried out at 0.08 MPa for 8 h to obtain PET resin;

[0032] Step S2: Mix 120 g of PET resin, 6 g of silane coupling agent KH550, 10 g of silica filler, and 2 g of antioxidant 168, and then extrude and cast into a film and perform biaxial stretching to obtain a PET base film; Immerse the PET base film in a 0.2 wt% polyethyleneimine solution for 8 min, dry it, and then immerse it in a 2 wt% polyacrylic acid solution for 8 min, and then dry it again to obtain a pretreated PET base film;

[0033] Step S3: Dissolve sodium alginate and sodium periodate in deionized water respectively, and then slowly add the sodium periodate solution to the sodium alginate solution, stir and react at 30 °C for 8 h, then add ethylene glycol to terminate the reaction. After the reaction is completed, dialyze and freeze-dry to obtain modified sodium alginate; Under a nitrogen atmosphere, dissolve 1 g of modified sodium alginate in 60 g of deionized water, then add 1 g of carbodiimide hydrochloride and 0.3 g of N-hydroxysuccinimide, stir and react for 1.5 h and adjust the pH to 5, then add 0.2 g of dopamine hydrochloride and continue to stir and react for 30 h. After the reaction is completed, dialyze and freeze-dry to obtain dopamine-modified sodium alginate; The concentration of the sodium periodate solution is 0.1 g / mL, and the concentration of the sodium alginate solution is 0.2 g / mL;

[0034] Add dopamine-modified sodium alginate and carboxymethyl chitosan to deionized water respectively, perform ultrasonic treatment for 60 min, then mix the two solutions and continue ultrasonic treatment for 30 min to obtain a positive ion solution; Add sodium hexametaphosphate to deionized water and perform ultrasonic treatment for 15 min to obtain a negative ion solution; The concentration of dopamine-modified sodium alginate is 0.008 g / mL, and the concentration of carboxymethyl chitosan is 0.016 g / mL; The concentration of sodium hexametaphosphate is 0.17 g / mL;

[0035] Immerse the pretreated PET base film in the positive ion solution for 2 min, dry it, and then immerse it in the negative ion solution for 2 min. Repeat the impregnation steps of the positive ion solution and the negative ion solution 6 times to obtain a modified PET base film; Coat a metal layer on the upper and lower surfaces of the modified PET base film to obtain a current collector; Then coat the active slurry on the surface of the current collector and dry it to obtain a pole piece; The metal layer is a copper layer, and the coating thickness is 1 μm.

[0036] Example 4: Step S1: Dissolve p-aminobenzoic acid in a 1,4-dioxane solvent, then add hexachlorocyclotriphosphazene and stir at 85 °C for 6.5 h to obtain a modified cyclotriphosphazene; Then mix the modified cyclotriphosphazene and deionized water, and after mixing evenly, add magnesium hydroxide and react at 95 °C for 6.5 h to obtain a composite flame retardant; The reaction mass ratio of p-aminobenzoic acid, hexachlorocyclotriphosphazene, and magnesium hydroxide is 9:3.5:0.2;

[0037] Mix 40 g of the composite flame retardant, 400 g of terephthalic acid, 230 g of ethylene glycol, and 0.2 g of antimony trioxide, and carry out an esterification reaction at 230 °C and 0.302 MPa for 3.5 h. Then raise the temperature to 285 °C and the pressure to 0.7 MPa for a polycondensation reaction for 6 h. Finally, carry out the polycondensation at 0.07 MPa for 7 h to obtain PET resin;

[0038] Step S2: Mix 120 g of PET resin, 6 g of silane coupling agent KH550, 10 g of silica filler, and 2 g of antioxidant 168, and extrude and cast into a film and biaxially stretch to obtain a PET base film; Immerse the PET base film in a 0.2 wt% polyethyleneimine solution for 6 min, dry it, and then immerse it in a 2 wt% polyacrylic acid solution for 7 min, and then dry it to obtain a pretreated PET base film;

[0039] Step S3: Dissolve sodium alginate and sodium periodate in deionized water respectively, and then slowly add the sodium periodate solution to the sodium alginate solution, stir and react at 27 °C for 7 h, then add ethylene glycol to terminate the reaction. After the reaction is completed, carry out dialysis and freeze-drying to obtain modified sodium alginate; Under a nitrogen atmosphere, dissolve 1 g of modified sodium alginate in 60 g of deionized water, then add 1 g of carbodiimide hydrochloride and 0.3 g of N-hydroxysuccinimide, stir and react for 1.3 h and adjust the pH to 4.7, then add 0.2 g of dopamine hydrochloride and continue to stir and react for 27 h. After the reaction is completed, carry out dialysis and freeze-drying to obtain dopamine-modified sodium alginate; The concentration of the sodium periodate solution is 0.1 g / mL, and the concentration of the sodium alginate solution is 0.2 g / mL;

[0040] Add dopamine-modified sodium alginate and carboxymethyl chitosan to deionized water respectively, carry out ultrasonic treatment for 50 min, then mix the two solutions and continue ultrasonic treatment for 25 min to obtain a positive ion solution; Add sodium hexametaphosphate to deionized water and carry out ultrasonic treatment for 103 min to obtain a negative ion solution; The concentration of dopamine-modified sodium alginate is 0.008 g / mL, the concentration of carboxymethyl chitosan is 0.016 g / mL; The concentration of sodium hexametaphosphate is 0.17 g / mL;

[0041] Immerse the pretreated PET base film in the positive ion solution for 1.5 min, dry it, and then immerse it in the negative ion solution for 1.5 min. Repeat the impregnation steps of the positive ion solution and the negative ion solution 6 times to obtain a modified PET base film; Deposit a metal layer on the upper and lower surfaces of the modified PET base film to obtain a current collector; Then coat the active paste on the surface of the current collector and dry it to obtain a pole piece; The metal layer is a copper layer with a coating thickness of 1 μm.

[0042] Example 5: Step S1: Dissolve aminobenzoic acid in 1,4-dioxane solvent, then add hexachlorocyclotriphosphazene and stir at 80 °C for 6 h to obtain a modified cyclotriphosphazene; then mix the modified cyclotriphosphazene with deionized water, and after mixing evenly, add magnesium hydroxide and react at 90 °C for 6 h to obtain a composite flame retardant; the reaction mass ratio of aminobenzoic acid, hexachlorocyclotriphosphazene, and magnesium hydroxide is 9:3.5:0.2;

[0043] Mix 40 g of the composite flame retardant, 400 g of terephthalic acid, 230 g of ethylene glycol, and 0.2 g of antimony trioxide, carry out an esterification reaction at 220 °C and 0.30 MPa for 3 h, then raise the temperature to 280 °C and the pressure to 0.60 MPa and carry out a polycondensation reaction for 5 h, and finally carry out the polycondensation at 0.06 MPa for 6 h to obtain PET resin;

[0044] Step S2: Mix 120 g of PET resin, 6 g of silane coupling agent KH550, 10 g of silica filler, and 2 g of antioxidant 168, extrude and cast into a film, and carry out biaxial stretching to obtain a PET base film; Immerse the PET base film in a 0.2 wt% polyethyleneimine solution for 5 min, dry it, then immerse it in a 2 wt% polyacrylic acid solution for 5 min, and then dry it to obtain a pretreated PET base film;

[0045] Dissolve sodium alginate and sodium periodate in deionized water respectively, then slowly add the sodium periodate solution to the sodium alginate solution, stir and react at 25 °C for 6 h, then add ethylene glycol to terminate the reaction. After the reaction is completed, carry out dialysis and freeze-drying to obtain modified sodium alginate; Under a nitrogen atmosphere, dissolve 1 g of modified sodium alginate in 60 g of deionized water, then add 1 g of carbodiimide hydrochloride and 0.3 g of N-hydroxysuccinimide, stir and react for 1 h and adjust the pH to 4.5, then add 0.2 g of dopamine hydrochloride and continue to stir and react for 25 h. After the reaction is completed, carry out dialysis and freeze-drying to obtain dopamine-modified sodium alginate; the concentration of the sodium periodate solution is 0.1 g / mL, and the concentration of the sodium alginate solution is 0.2 g / mL;

[0046] Add dopamine-modified sodium alginate and carboxymethyl chitosan to deionized water respectively, carry out ultrasonic treatment for 40 min, then mix the two solutions and continue ultrasonic treatment for 20 min to obtain a positive ion solution; Add sodium hexametaphosphate to deionized water and carry out ultrasonic treatment for 10 min to obtain a negative ion solution; the concentration of dopamine-modified sodium alginate is 0.008 g / mL, the concentration of carboxymethyl chitosan is 0.016 g / mL; the concentration of sodium hexametaphosphate is 0.17 g / mL;

[0047] The pretreated PET base film was immersed in a positive ion solution for 1 min, dried, and then immersed in a negative ion solution for 1 min. The above-mentioned impregnation steps of the positive ion solution and the negative ion solution were repeated 6 times to obtain a modified PET base film; a metal layer was plated on the upper and lower surfaces of the modified PET base film to obtain a current collector; then an active slurry was coated on the surface of the current collector and dried to obtain a pole piece; the metal layer was a copper layer with a coating thickness of 1 μm.

[0048] Comparative Example 1: The preparation step of the composite flame retardant was removed, and the rest was the same as in Example 1. The specific steps were as follows: Step S1: 400 g of terephthalic acid, 230 g of ethylene glycol, and 0.2 g of antimony trioxide were mixed and subjected to an esterification reaction at 250 °C and 0.35 MPa for 4 h, then the temperature was raised to 290 °C and the pressure was raised to 0.80 MPa for a polycondensation reaction for 7 h, and finally the polycondensation was carried out at 0.08 MPa for 8 h to obtain a PET resin;

[0049] Step S2: 120 g of PET resin, 6 g of silane coupling agent KH550, 10 g of silica filler, and 2 g of antioxidant 168 were mixed, extruded and cast into a film, and biaxially stretched to obtain a PET base film; the PET base film was immersed in a 0.2 wt% polyethyleneimine solution for 8 min, dried, and then immersed in a 2 wt% polyacrylic acid solution for 8 min, and then dried to obtain a pretreated PET base film;

[0050] Step S3: Sodium alginate and sodium periodate were respectively dissolved in deionized water, and then the sodium periodate solution was slowly added to the sodium alginate solution, and the reaction was stirred at 30 °C for 8 h, and then ethylene glycol was added to terminate the reaction. After the reaction, dialysis and freeze-drying were carried out to obtain modified sodium alginate; in a nitrogen environment, 1 g of modified sodium alginate was dissolved in 60 g of deionized water, and then 1 g of carbodiimide hydrochloride and 0.3 g of N-hydroxysuccinimide were added, and the reaction was stirred for 1.5 h and the pH was adjusted to 5, and then 0.2 g of dopamine hydrochloride was added and the reaction was stirred for another 30 h. After the reaction, dialysis and freeze-drying were carried out to obtain dopamine-modified sodium alginate; the concentration of the sodium periodate solution was 0.1 g / mL, and the concentration of the sodium alginate solution was 0.2 g / mL;

[0051] Dopamine-modified sodium alginate and carboxymethyl chitosan were respectively added to deionized water, ultrasonically treated for 60 min, and then the two solutions were mixed and ultrasonically treated for another 30 min to obtain a positive ion solution; sodium hexametaphosphate was added to deionized water and ultrasonically treated for 15 min to obtain a negative ion solution; the concentration of dopamine-modified sodium alginate was 0.008 g / mL, the concentration of carboxymethyl chitosan was 0.016 g / mL; the concentration of sodium hexametaphosphate was 0.17 g / mL;

[0052] The pretreated PET base film was immersed in a positive ion solution for 2 min, dried, and then immersed in a negative ion solution for 2 min. The above steps of immersing in the positive ion solution and the negative ion solution were repeated 6 times to obtain a modified PET base film. A metal layer was plated on the upper and lower surfaces of the modified PET base film to obtain a current collector. Then, an active slurry was coated on the surface of the current collector and dried to obtain a pole piece. The metal layer was a copper layer with a coating thickness of 1 μm.

[0053] Comparative Example 2: The surface coating treatment step of the base film was removed, and the rest was the same as in Example 1. The specific steps were as follows: Step S1: Ammonobenzoic acid was dissolved in a 1,4-dioxane solvent, and hexachlorocyclotriphosphazene was added and stirred at 90 °C for 7 h to obtain a modified cyclotriphosphazene. Then, the modified cyclotriphosphazene and deionized water were mixed, and after mixing evenly, magnesium hydroxide was added and reacted at 100 °C for 7 h to obtain a composite flame retardant. The reaction mass ratio of ammonobenzoic acid, hexachlorocyclotriphosphazene, and magnesium hydroxide was 9:3.5:0.2.

[0054] 40 g of the composite flame retardant, 400 g of terephthalic acid, 230 g of ethylene glycol, and 0.2 g of antimony trioxide were mixed and subjected to an esterification reaction at 250 °C and 0.35 MPa for 4 h. Then, the temperature was raised to 290 °C and the pressure was raised to 0.80 MPa for a polycondensation reaction for 7 h. Finally, the polycondensation was carried out at 0.08 MPa for 8 h to obtain a PET resin.

[0055] Step S2: 120 g of the PET resin, 6 g of the silane coupling agent KH550, 10 g of the silica filler, and 2 g of the antioxidant 168 were mixed, extruded and cast into a film, and biaxially stretched to obtain a PET base film. A metal layer was plated on the upper and lower surfaces of the PET base film to obtain a current collector. Then, an active slurry was coated on the surface of the current collector and dried to obtain a pole piece. The metal layer was a copper layer with a coating thickness of 1 μm.

[0056] Detection test:

[0057] Limiting oxygen index test: The base film finally prepared in the present invention was cut into specimens of 130×7×4 mm, and the limiting oxygen index was measured using an HC-2CZ oxygen index meter. The average value was taken from three measurements.

[0058] Antibacterial performance test: Take the final prepared base film of the present invention as a sample. Prepare two nutrient agar medium plates. Using aseptic operation techniques, use a pipette to aspirate an Escherichia coli bacterial suspension with a concentration of 1×1015 CFU / mL and evenly inoculate it on the surfaces of the two media. Use a sterile spreading rod to gently spread the bacterial suspension evenly on the surface of the medium to ensure that the bacteria are evenly distributed. One of the media inoculated with Escherichia coli serves as a blank control without covering any sample; the other medium inoculated with Escherichia coli serves as the experimental group. Carefully cover the cut PET base film sample onto the surface of the medium with sterile forceps, and avoid generating bubbles or displacement during the covering process to ensure the accuracy of the antibacterial test. Place the inoculated and processed blank control group and experimental group medium plates in a constant temperature incubator, incubate at 30°C for 20 h, check the bacterial growth status, calculate the colony counts of the two media, and then substitute them into the formula to calculate the antibacterial rate. The results are shown in the following table:

[0059] Limiting oxygen index / % Antibacterial rate / % Example 3 32 96 Example 4 32 95 Example 5 31 94 Comparative Example 1 20 92 Comparative Example 2 26 77

[0060] Conclusion: The dosages in Examples 3 to 5 remain unchanged, and only some reaction parameters are modified. From the experimental data, it can be seen that there are no obvious fluctuations in the performance of the samples.

[0061] Comparative Example 1: Remove the preparation steps of the composite flame retardant, and the rest is the same as in Example 1. From the experimental data, it can be seen that compared with Example 1, the limiting oxygen index is reduced to 20%, and the antibacterial rate is reduced to 92%. The reason for the analysis is as follows: The composite flame retardant includes phosphorus-nitrogen synergistic flame retardant modified cyclotriphosphazene and magnesium components. Phosphorus and nitrogen can promote the charring reaction during combustion, form a dense carbon layer, thereby isolating oxygen and heat and inhibiting the further development of combustion; at the same time, the decomposition products of magnesium hydroxide (magnesium oxide and water) can dilute the oxygen concentration in the combustion area and inhibit flame spread. Therefore, after removing the composite flame retardant, the flame retardant performance decreases significantly, and the limiting oxygen index decreases.

[0062] Comparative Example 2: Remove the surface coating treatment steps of the base film, and the rest is the same as in Example 1. From the experimental data, it can be seen that compared with Example 1, the limiting oxygen index is reduced to 26%, and the antibacterial rate is reduced to 77%. The reason for the analysis is as follows: The surface coating has antibacterial structures such as Schiff base structure and carboxymethyl chitosan. These antibacterial components can be effectively deposited on the surface of the PET base film, thereby significantly improving the antibacterial performance of the base film; in addition, sodium hexametaphosphate in the surface coating can also improve the flame retardant performance of the base film. Therefore, after removing the surface coating treatment steps of the base film, the antibacterial performance and flame retardant performance decrease.

[0063] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0064] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for processing the tab of an electrode, characterized in that: It includes the following steps: Clamp and fix the electrode plate, immerse the tab part of the electrode plate into the dissolving reagent, and the dissolving reagent will fully infiltrate and dissolve the polymer layer inside the tab. Then, air-dry the electrode plate after the dissolution is completed to obtain a pure metal tab, and then weld the tab. At this time, the metal conductive layers can be in direct contact without additional transfer.

2. The method for processing the tab of the electrode sheet according to claim 1, characterized in that: The dissolving reagent is a mixed solvent of phenol and tetrachloroethane or a hexafluoroisopropanol reagent.

3. The pole piece according to any one of claims 1-2, characterized in that: It includes the following steps: Deposit a metal layer on the upper and lower surfaces of the modified PET base film to obtain a current collector; then coat the active paste on the surface of the current collector and dry it to obtain an electrode plate. The metal layer is a copper layer or an aluminum layer, and the coating thickness is 0.5 - 1.5 μm.

4. A pole piece according to claim 3, characterized in that: The preparation process of the modified PET base film is as follows: Step S1: Mix a composite flame retardant, terephthalic acid, ethylene glycol, and antimony trioxide, carry out an esterification reaction at 220 - 250 °C and 0.30 - 0.35 MPa for 3 - 4 h, then raise the temperature to 280 - 290 °C and raise the pressure to 0.60 - 0.80 MPa for a polycondensation reaction for 5 - 7 h, and finally carry out the polycondensation at 0.06 - 0.08 MPa for 6 - 8 h to obtain PET resin. Step S2: Mix the PET resin, silane coupling agent KH550, silica filler, and antioxidant 168, extrude and cast into a film, and carry out biaxial stretching to obtain a PET base film; immerse the PET base film in a 0.1 - 0.2 wt% polyethyleneimine solution for 5 - 8 min, dry it and then immerse it in a 1 - 2 wt% polyacrylic acid solution for 5 - 8 min, and then dry it to obtain a pretreated PET base film. Step S3: Add dopamine-modified sodium alginate and carboxymethyl chitosan to deionized water respectively, carry out ultrasonic treatment for 40 - 60 min, then mix the two solutions and continue ultrasonic treatment for 20 - 30 min to obtain a positive ion solution; add sodium hexametaphosphate to deionized water and carry out ultrasonic treatment for 10 - 15 min to obtain a negative ion solution; immerse the pretreated PET base film in the positive ion solution for 1 - 2 min, dry it and then immerse it in the negative ion solution for 1 - 2 min, and repeat the impregnation steps of the positive ion solution and the negative ion solution 4 - 6 times to obtain the modified PET base film.

5. A kind of electrode tab according to claim 4, characterized in that: In Step S1, the content of each component of the PET resin is: in terms of mass parts, 35 - 40 parts of the composite flame retardant, 400 - 450 parts of terephthalic acid, 220 - 250 parts of ethylene glycol, and 0.1 - 0.2 parts of antimony trioxide.

6. The anode according to claim 4, characterized in that: In Step S1, the preparation process of the composite flame retardant is: dissolve aminobenzoic acid in a 1,4-dioxane solvent, then add hexachlorocyclotriphosphazene and stir at 80 - 90 °C for 6 - 7 h to obtain a modified cyclotriphosphazene; then mix the modified cyclotriphosphazene and deionized water, add magnesium hydroxide after mixing evenly, and react at 90 - 100 °C for 6 - 7 h to obtain the composite flame retardant. The reaction mass ratio of aminobenzoic acid, hexachlorocyclotriphosphazene, and magnesium hydroxide is (8 - 10):3.5:0.

2.

7. A pole piece according to claim 4, characterized in that: In step S2, the component contents of the PET base film are as follows: in terms of parts by mass, 120 - 140 parts of PET resin, 6 - 10 parts of silane coupling agent KH550, 8 - 10 parts of silica filler, and 2 - 3 parts of antioxidant 168.

8. A pole piece according to claim 4, characterized in that: In step S3, the concentration of dopamine - modified sodium alginate in the positive ion solution is 0.008 - 0.009 g / mL, the concentration of carboxymethyl chitosan is 0.016 - 0.018 g / mL, and the concentration of sodium hexametaphosphate in the negative ion solution is 0.17 - 0.19 g / mL.

9. A pole piece according to claim 4, characterized in that: In step S3, the preparation process of dopamine - modified sodium alginate is as follows: Dissolve sodium alginate and sodium periodate in deionized water respectively, then slowly add the sodium periodate solution to the sodium alginate solution, stir and react at 25 - 30 °C for 6 - 8 h, then add ethylene glycol to terminate the reaction. After the reaction is completed, dialyze and freeze - dry to obtain modified sodium alginate; Under a nitrogen atmosphere, dissolve the modified sodium alginate in deionized water, then add carbodiimide hydrochloride and N - hydroxysuccinimide, stir and react for 1.0 - 1.5 h and adjust the pH to 4.5 - 5.0, then add dopamine hydrochloride and continue to stir and react for 25 - 30 h. After the reaction is completed, dialyze and freeze - dry to obtain dopamine - modified sodium alginate.

10. A pole piece according to claim 9, characterized in that: The concentration of the sodium periodate solution is 0.10 - 0.15 g / mL, and the concentration of the sodium alginate solution is 0.2 - 0.4 g / mL; The component contents of dopamine - modified sodium alginate are as follows: in terms of parts by mass, 1.0 - 1.5 parts of modified sodium alginate, 50 - 80 parts of deionized water, 1.0 - 1.5 parts of carbodiimide hydrochloride, 0.3 - 0.5 parts of N - hydroxysuccinimide, and 0.2 - 0.3 parts of dopamine hydrochloride.