Preparation method and application of multifunctional binder

Abstract

The invention relates to the technical field of lithium batteries, in particular to a preparation method and application of a multifunctional binder. The preparation method of the multifunctional binder comprises the following steps: dissolving a polyvinylidene fluoride-hexafluoropropylene copolymer in an organic solvent, adding a photoinitiator, deoxidizing, carrying out ultraviolet radiation, adding a LiNBTI monomer, carrying out graft polymerization reaction, and carrying out post-treatment to obtain the multifunctional binder. The multifunctional binder is applied to slurry preparation, and the preparation method comprises the following steps: uniformly grinding a lithium-rich manganese-based positive electrode material, a conductive agent and the multifunctional binder, and adding an organic solvent to obtain the slurry.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a preparation method and application of a multifunctional binder. Background Art

[0002] Ternary cathode material LiCo x Mn y Ni 1-x-y O2 (NCM) has become a mainstream cathode material in lithium-ion batteries due to its high specific capacity of 280 mAh / g and wide operating voltage range of 2.5-4.2 V. However, its crystal structure undergoes irreversible phase transitions during charge and discharge, accompanied by metal ion mixing and dislocation effects, resulting in a significant decrease in its cycling stability.

[0003] Current research on optimizing ternary cathode systems focuses primarily on active material modification, separator performance enhancement, and electrolyte formulation optimization, with relatively little research on binders. Although binders represent a relatively small proportion of the total, they fulfill the crucial functions of adhering active material particles, dispersing conductive agents, and maintaining the integrity of the electrode structure, making them a key component of electrode materials.

[0004] Traditional polyvinylidene fluoride (PVDF) binders only achieve physical bonding through van der Waals forces. Their bonding strength is limited and they lack the ability to inhibit the dissolution of transition metals, making it difficult to meet the structural stability requirements of the ternary system.

[0005] Therefore, developing a multifunctional binder with both strong adhesion and interface protection functions has become an important technical path to improve the cycle performance of ternary positive electrodes. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method of a multifunctional adhesive and its application to solve the problems raised in the above background technology.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: A method for preparing a multifunctional adhesive comprises the following steps: The polyvinylidene fluoride-hexafluoropropylene copolymer is dissolved in an organic solvent, a photoinitiator is added, oxygen is removed, ultraviolet irradiation is performed, LiNBTI monomer is added, graft polymerization reaction is carried out, and post-treatment is performed to obtain a multifunctional adhesive.

[0008] In a further embodiment, the multifunctional binder comprises a polyvinylidene fluoride-hexafluoropropylene copolymer backbone and LiNBTI polymer side chains grafted onto the backbone. The LiNBTI monomer serves as the starting material for the graft polymerization reaction, resulting in the LiNBTI polymer side chains. The LiNBTI polymer side chains are polymer chains formed by the polymerization of the LiNBTI monomers and grafted onto the PVDF-HFP backbone. These chains contain repeating LiNBTI monomer units.

[0009] In a further embodiment, the polyvinylidene fluoride-hexafluoropropylene copolymer is poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP); and the LiNBTI monomer is N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide lithium p-styrenesulfonyl imide.

[0010] In a further embodiment, the photoinitiator includes but is not limited to benzophenone; the organic solvent includes but is not limited to N-methylpyrrolidone (NMP) and acetonitrile.

[0011] More optimally, the graft polymerization reaction temperature is 85-95° C., and the reaction time is 9.5-10.5 h.

[0012] More optimally, in the raw materials of the multifunctional binder, the mass ratio of polyvinylidene fluoride-hexafluoropropylene copolymer to LiNBTI monomer is 8-9:1.

[0013] More optimally, the preparation process of the LiNBTI monomer is: Step 1: Sodium p-styrenesulfonate and N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide were mixed at once, and oxalyl chloride was added under nitrogen atmosphere to carry out chlorination reaction to obtain p-styrenesulfonyl chloride; Step 2: Add trifluoromethanesulfonamide, an acid-binding agent, and a catalyst into an organic solvent and mix them again, add p-styrenesulfonyl chloride, carry out an amidation reaction, and perform post-treatment to obtain compound A; Step 3: Dissolve compound A in an organic solvent, add 18-22 wt% sodium carbonate aqueous solution, react to form a salt, and post-treat to obtain a crude potassium salt product; recrystallize the crude potassium salt product to obtain a potassium salt; dissolve the potassium salt in an organic solvent, add lithium perchlorate, perform a displacement reaction, and post-treat to obtain a LiNBTI monomer.

[0014] In a further embodiment, the acid-binding agent includes but is not limited to triethylamine; the catalyst includes but is not limited to 4-dimethylaminopyridine (DMAP).

[0015] In a further embodiment, compound A is N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide-p-styrenesulfonyl imide; and the potassium salt is potassium N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide-p-styrenesulfonyl imide.

[0016] More optimally, in step 1, the primary mixing temperature is 0°C; the acyl chlorination reaction temperature is 10-30°C, and the reaction time is 22.5-23.5h; In step 2, the secondary mixing temperature is 0°C; the amidation reaction temperature is 10-30°C, and the reaction time is 21.5-22.5h; In step 3, the salt-forming reaction temperature is 0° C., and the stirring speed is 1200-1600 rpm; the replacement reaction temperature is 10-30° C., and the reaction time is 9.5-10.5 h.

[0017] More optimally, in step 1, in the chlorination reaction, the mass ratio of sodium p-styrenesulfonate, N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide, and oxalyl chloride is 40:1:27-28; Step 2, in the amidation reaction, the mass ratio of trifluoromethanesulfonamide to p-styrenesulfonyl chloride is 14.8-15:23-23.5; In step 3, in the salt-forming reaction, the mass ratio of compound A to 18-22 wt% sodium carbonate aqueous solution is 1-1.3:1; in the displacement reaction, the mass ratio of potassium salt to lithium perchlorate is 3-3.5:1.

[0018] More optimally, a multifunctional binder is used, which is characterized in that: the lithium-rich manganese-based positive electrode material, the conductive agent, and the multifunctional binder are evenly ground, and an organic solvent is added to obtain a slurry.

[0019] More optimally, in the raw materials of the slurry, the mass ratio of the lithium-rich manganese-based positive electrode material, the conductive agent, and the multifunctional binder is 8:1:0.8~1.2.

[0020] In a further solution, the conductive carbon black (Super P) in the conductive agent is the main conductive agent, and acetylene black is the auxiliary conductive agent.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) This scheme designs a PVDF-based polyelectrolyte binder (multifunctional binder) modified by N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide p-styrenesulfonyl imide lithium anion polymer side chains based on PVDF, making it more suitable for the NCM811 positive electrode system. By forming lithium ion conductive channels in the positive electrode through the anion polymer side chains in this structure, lithium ions can be regulated to be transported faster in the positive electrode. In addition, the polarity and charge-charge interaction between the side chains and the active material and the current collector are utilized to improve the adhesion of the PVDF binder and enhance the integrity of the positive electrode structure, thereby further improving the positive electrode performance and cycle stability.

[0022] (2) This scheme improves the electrochemical and mechanical properties of the positive electrode material. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0024] It should be noted that the following parts are by mass, and all raw materials involved in the present invention are purchased from manufacturers without any special restrictions. Examples include: in the following embodiments, poly (vinylidene fluoride-co-hexafluoropropylene), battery grade, purchased from Arkema Kynar 2801, France; N-methyl pyrrolidone with a purity of 99.9% was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; benzophenone was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; lithium hexafluorophosphate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; methanol was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; ethanol was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; nickel cobalt manganese with a purity of ≥98%, model NCM811; conductive carbon black was battery grade, purchased from Guangdong Candlelight New Energy Technology Co., Ltd.; electrolyte (1.0MLiPF6 / EC+DMC, volume ratio 1:1), purchased from Guangdong Candlelight New Energy Technology Co., Ltd.; aluminum foil, battery grade, purchased from Hefei Kejing; acetylene black, purchased from Hefei Kejing; diaphragm, battery grade, purchased from Celgard, USA; CA of sodium p-styrene sulfonate The purity of the product is ≥98% and it was purchased from Aladdin. The CAS number of N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide is 82113-66-4 and it was purchased from Aladdin. The purity of acetonitrile is ≥99.5% and it was purchased from Aladdin. The purity of oxalyl chloride is ≥98% and it was purchased from Aladdin. The purity of trifluoromethanesulfonamide is >98.0% and it was purchased from Aladdin. The purity of triethylamine is ≥99% and it was purchased from Aladdin. The purity of 4-dimethylaminopyridine is ≥99% and it was purchased from Aladdin. The purity of dichloromethane is ≥99.5% and it was purchased from Aladdin. The purity of anhydrous magnesium sulfate is ≥99.5% and it was purchased from Aladdin. The purity of sodium carbonate, anhydrous grade, is ≥99.5% and it was purchased from Aladdin. The purity of lithium perchlorate, anhydrous grade, is ≥99.99% and it was purchased from Aladdin.

[0025] Example 1: A method for preparing a multifunctional adhesive and its application, comprising the following steps: Step 1: 20.6 g (0.1 mol) of sodium p-styrenesulfonate and 0.51 g (0.007 mol) of N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide were added to 200 mL of acetonitrile and stirred to obtain System I. Under a nitrogen atmosphere, System I was cooled to 0°C, and then 13.96 g (0.11 mol) of oxalyl chloride was slowly added dropwise. After the addition was complete, the temperature was raised to 20°C and the chlorination reaction was carried out for 23 hours to obtain p-styrenesulfonyl chloride. Step 2: 14.9 g (0.1 mol) of trifluoromethanesulfonamide, 30.36 g (0.03 mol) of triethylamine, and 1.1 g (0.009 mol) of 4-dimethylaminopyridine were added sequentially to 170 mL of acetonitrile and stirred evenly to obtain System II; System II was cooled to 0°C, and then p-styrenesulfonyl chloride was slowly added dropwise. After the addition was complete, the temperature was raised to 20°C for amidation reaction for 22 hours. After the amidation reaction was completed, the acetonitrile was distilled off under reduced pressure, and dichloromethane was added to dissolve the mixture, and the mixture was washed twice with 20 mL of a 0.5 mol / L sodium bicarbonate aqueous solution and once with 20 mL of a 1 mol / L hydrochloric acid aqueous solution, followed by drying over anhydrous magnesium sulfate and concentration under reduced pressure to obtain 23.51 g of a brown viscous substance, namely, Compound A; Step 3: (1) Take 23.51g of compound A and add it to 60mL of acetonitrile to dissolve it, cool it to 0℃, add 100mL of 20wt% sodium carbonate aqueous solution, stir it at 0℃ at a stirring speed of 1600rmp to carry out salt-forming reaction, precipitate light brown precipitate, and after the salt-forming reaction is completed, directly filter it and dry it at 40℃ to obtain 23.67g of light brown crude product, i.e. crude potassium salt product; add water to the crude potassium salt product and recrystallize it twice to obtain 22.53g of potassium salt; (2) Take 21.2g (0.06mol) of potassium salt and add it to 300mL of sodium carbonate aqueous solution to dissolve it, then add 6.38g (0.06mol) of lithium perchlorate, carry out displacement reaction at 20℃ for 10h, filter it directly after the displacement reaction is completed, and the obtained filtrate is concentrated under reduced pressure and dried in vacuo at 40℃ to obtain 18.14g of white solid, i.e. LiNBTI monomer; Step 4: 2g PVDF-HFP was dissolved in 30mL NMP. Under a nitrogen atmosphere, 1.2g benzophenone was added and nitrogen was bubbled for 15min to remove oxygen from the solution. After the system was sealed, it was irradiated with a high-pressure mercury lamp (365nm) for 45min. Then, LiNBTI monomer was added and graft polymerization was carried out at 90°C under a nitrogen atmosphere for 10h. After the reaction, it was poured into 200mL anhydrous ethanol for precipitation and centrifugation, and the solid component was collected. It was then dissolved in NMP and then precipitated and centrifuged again with anhydrous ethanol. This was repeated three times. Finally, the collected product was extracted with methanol for 36h and then vacuum-dried at 60°C overnight to obtain a multifunctional binder. Step 5: Grind the lithium-rich manganese-based positive electrode material, the conductive agent, and the multifunctional binder in a mass ratio of 8:1:1 and add N-methylpyrrolidone to obtain a slurry.

[0026] Example 2: A preparation method and application of a multifunctional adhesive, comprising the following steps: Step 1: 20.6 g (0.1 mol) of sodium p-styrenesulfonate and 0.51 g (0.007 mol) of N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide were added to 200 mL of acetonitrile and stirred to obtain System I. Under a nitrogen atmosphere, System I was cooled to 0°C, and then 13.96 g (0.11 mol) of oxalyl chloride was slowly added dropwise. After the addition was complete, the temperature was raised to 20°C and the chlorination reaction was carried out for 23 hours to obtain p-styrenesulfonyl chloride. Step 2: 14.9 g (0.1 mol) of trifluoromethanesulfonamide, 30.36 g (0.03 mol) of triethylamine, and 1.1 g (0.009 mol) of 4-dimethylaminopyridine were added sequentially to 170 mL of acetonitrile and stirred evenly to obtain System II; System II was cooled to 0°C, and then p-styrenesulfonyl chloride was slowly added dropwise. After the addition was complete, the temperature was raised to 20°C for amidation reaction for 22 hours. After the amidation reaction was completed, the acetonitrile was distilled off under reduced pressure, and dichloromethane was added to dissolve the mixture, and the mixture was washed twice with 20 mL of a 0.5 mol / L sodium bicarbonate aqueous solution and once with 20 mL of a 1 mol / L hydrochloric acid aqueous solution, followed by drying over anhydrous magnesium sulfate and concentration under reduced pressure to obtain 23.51 g of a brown viscous substance, namely, Compound A; Step 3: (1) Take 23.51g of compound A and add it to 60mL of acetonitrile to dissolve it, cool it to 0℃, add 100mL of 20wt% sodium carbonate aqueous solution, stir it at 0℃ at a stirring speed of 1600rmp to carry out salt-forming reaction, precipitate light brown precipitate, and after the salt-forming reaction is completed, directly filter it and dry it at 40℃ to obtain 23.67g of light brown crude product, i.e. crude potassium salt product; add water to the crude potassium salt product and recrystallize it twice to obtain 22.53g of potassium salt; (2) Take 21.2g (0.06mol) of potassium salt and add it to 300mL of sodium carbonate aqueous solution to dissolve it, then add 6.38g (0.06mol) of lithium perchlorate, carry out displacement reaction at 20℃ for 10h, filter it directly after the displacement reaction is completed, and the obtained filtrate is concentrated under reduced pressure and dried in vacuo at 40℃ to obtain 18.14g of white solid, i.e. LiNBTI monomer; Step 4: 2g PVDF-HFP was dissolved in 30mL NMP. Under a nitrogen atmosphere, 1.2g benzophenone was added and nitrogen was bubbled for 15min to remove oxygen from the solution. After the system was sealed, it was irradiated with a high-pressure mercury lamp (365nm) for 45min. Then, LiNBTI monomer was added and graft polymerization was carried out at 90°C under a nitrogen atmosphere for 10h. After the reaction, it was poured into 200mL anhydrous ethanol for precipitation and centrifugation, and the solid component was collected. It was then dissolved in NMP and then precipitated and centrifuged again with anhydrous ethanol. This was repeated three times. Finally, the collected product was extracted with methanol for 36h and then vacuum-dried at 60°C overnight to obtain a multifunctional binder. Step 5: Grind the lithium-rich manganese-based positive electrode material, the conductive agent, and the multifunctional binder in a mass ratio of 8:1:1.2 and add N-methylpyrrolidone to obtain a slurry.

[0027] Example 3: A preparation method and application of a multifunctional adhesive, comprising the following steps: Step 1: 20.6 g (0.1 mol) of sodium p-styrenesulfonate and 0.51 g (0.007 mol) of N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide were added to 200 mL of acetonitrile and stirred to obtain System I. Under a nitrogen atmosphere, System I was cooled to 0°C, and then 13.96 g (0.11 mol) of oxalyl chloride was slowly added dropwise. After the addition was complete, the temperature was raised to 20°C and the chlorination reaction was carried out for 23 hours to obtain p-styrenesulfonyl chloride. Step 2: 14.9 g (0.1 mol) of trifluoromethanesulfonamide, 30.36 g (0.03 mol) of triethylamine, and 1.1 g (0.009 mol) of 4-dimethylaminopyridine were added sequentially to 170 mL of acetonitrile and stirred evenly to obtain System II; System II was cooled to 0°C, and then p-styrenesulfonyl chloride was slowly added dropwise. After the addition was complete, the temperature was raised to 20°C for amidation reaction for 22 hours. After the amidation reaction was completed, the acetonitrile was distilled off under reduced pressure, and dichloromethane was added to dissolve the mixture, and the mixture was washed twice with 20 mL of a 0.5 mol / L sodium bicarbonate aqueous solution and once with 20 mL of a 1 mol / L hydrochloric acid aqueous solution, followed by drying over anhydrous magnesium sulfate and concentration under reduced pressure to obtain 23.51 g of a brown viscous substance, namely, Compound A; Step 3: (1) Take 23.51g of compound A and add it to 60mL of acetonitrile to dissolve it, cool it to 0℃, add 100mL of 20wt% sodium carbonate aqueous solution, stir it at 0℃ at a stirring speed of 1600rmp to carry out salt-forming reaction, precipitate light brown precipitate, and after the salt-forming reaction is completed, directly filter it and dry it at 40℃ to obtain 23.67g of light brown crude product, i.e. crude potassium salt product; add water to the crude potassium salt product and recrystallize it twice to obtain 22.53g of potassium salt; (2) Take 21.2g (0.06mol) of potassium salt and add it to 300mL of sodium carbonate aqueous solution to dissolve it, then add 6.38g (0.06mol) of lithium perchlorate, carry out displacement reaction at 20℃ for 10h, filter it directly after the displacement reaction is completed, and the obtained filtrate is concentrated under reduced pressure and dried in vacuo at 40℃ to obtain 18.14g of white solid, i.e. LiNBTI monomer; Step 4: 2g PVDF-HFP was dissolved in 30mL NMP. Under a nitrogen atmosphere, 1.2g benzophenone was added and nitrogen was bubbled for 15min to remove oxygen from the solution. After the system was sealed, it was irradiated with a high-pressure mercury lamp (365nm) for 45min. Then, LiNBTI monomer was added and graft polymerization was carried out at 90°C under a nitrogen atmosphere for 10h. After the reaction, it was poured into 200mL anhydrous ethanol for precipitation and centrifugation, and the solid component was collected. It was then dissolved in NMP and then precipitated and centrifuged again with anhydrous ethanol. This was repeated three times. Finally, the collected product was extracted with methanol for 36h and then vacuum-dried at 60°C overnight to obtain a multifunctional binder. Step 5: Grind the lithium-rich manganese-based positive electrode material, the conductive agent, and the multifunctional binder in a mass ratio of 8:1:0.8 and add N-methylpyrrolidone to obtain a slurry.

[0028] Comparative Example 1: Traditional PVDF binder.

[0029] Testing experiment: The slurries obtained in Examples 1 to 3 and Comparative Example 1 were prepared into electrode sheets and button batteries, respectively, and their performance was tested: The electrode sheet preparation process is as follows: the slurries of Examples 1 to 3 and Comparative Example 1 are uniformly coated on aluminum foil using a film applicator to a coating thickness of 200 μm, vacuum dried at 80°C for 12 hours, and finally cut and pressed using a manual slicer to obtain circular electrode sheets with a diameter of 11 mm, namely the electrode sheets of Examples 1 to 3 and Comparative Example 1.

[0030] The preparation process of button batteries is as follows: Step 1: Assemble a CR2025 button cell: Use the electrode sheets obtained in Examples 1 to 3 and Comparative Example 1 as the positive electrode; a lithium metal sheet (15.6 mm in diameter and 0.45 mm in thickness) as the negative electrode; a Celgard 2400 polypropylene film (16 mm in diameter) as the separator; and use 5V high-voltage electrolyte LB111 as the electrolyte. Step 2: Under an argon atmosphere, the negative electrode shell, the metal lithium sheet, a small amount of electrolyte, the diaphragm, the electrolyte, the positive electrode sheet, the gasket, the spring, and the positive electrode shell were assembled in order and sealed using a hydraulic press. The batteries were then allowed to stand for 12 hours to obtain the button batteries of Examples 1 to 3 and Comparative Example 1.

[0031] (1) Peel test: The electrode sheets of Examples 1 to 3 and Comparative Example 1 were cut into 40×25 mm strips, and then 3M double-sided tape (9×1 mm) was affixed to the back of each sheet to bond the surface of the electrode sheet to the glass slide. The specific bonding process is as follows: first, double-sided tape was affixed to the back of the electrode sheet and fixed to the glass slide, and then double-sided tape of another specification was affixed to the active material surface of the electrode sheet. During the test, one end of the sample was fixed to the upper fixture of the electronic universal testing machine (holding the area not covered by the double-sided tape), and the other end of the glass slide was fixed to the lower fixture. The test mode was set to 180° peel test, the mode was selected as tension-displacement mode, and the tensile rate was 5 mm / min. The test results are shown in Table 1. (2) Charge and discharge performance test: The button batteries prepared in Examples 1 to 3 and Comparative Example 1 were tested for cycle performance and rate performance using a CT2001A blue battery test system and a CT-4008 Xinwei battery test system in a constant current charge and discharge mode. The voltage range was set to 5mV~2V. First, the battery was discharged to 5mV at a constant current of 0.05C, and then allowed to stand for 5 minutes to allow the electrode to reach a stable state. Then, the battery was discharged to 5mV at a constant current of 200μA, and allowed to stand for another 5 minutes. Finally, the battery was completely discharged to 5mV at a constant current of 50μA. The charging process was tested by charging to 2V at a constant current of 0.1C. The test results are shown in Table 1. Table 1

[0032] Result analysis: According to the data analysis in Table 1, it can be seen that PVDF binder achieves bonding through intermolecular van der Waals forces, and its bonding force is weak. By introducing this polar ionic ion polymer side chain and utilizing the charge-charge interaction force between the side chain and the active material and the current collector, the adhesion force of the PVDF binder can be significantly improved.

[0033] (1) In this study, a multifunctional binder with anionic polymer side chains was synthesized using PVDF as the main chain by means of UV grafting. This anionic polymer side chain has a relatively good interaction with lithium ions and can serve as a transmission channel in the positive electrode to help lithium ions reach the surface of the positive electrode active material faster to participate in the electrochemical reaction, which significantly improves the battery performance. After 100 cycles at a rate of 0.2C, the battery based on the multifunctional binder still maintains a specific capacity of 178.3mAh / g. At the same time, the introduction of this polar side chain enables the multifunctional binder to maintain a high capacity at a current density, and its specific capacity can reach 162.1mAh / g at a rate of 2C.

[0034] The above results show that the multifunctional binder prepared in this scheme can effectively improve the cycle stability of the ternary positive electrode system and enhance the performance of the battery.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing a multifunctional adhesive, characterized in that: The following steps are involved: The polyvinylidene fluoride-hexafluoropropylene copolymer is dissolved in an organic solvent, a photoinitiator is added, oxygen is removed, ultraviolet irradiation is performed, LiNBTI monomer is added, graft polymerization reaction is carried out, and post-treatment is performed to obtain a multifunctional adhesive.

2. The method for preparing a multifunctional adhesive according to claim 1, characterized in that: The graft polymerization reaction temperature is 85-95° C., and the reaction time is 9.5-10.5 hours.

3. The method for preparing a multifunctional adhesive according to claim 1, wherein: In the raw materials of the multifunctional binder, the mass ratio of polyvinylidene fluoride-hexafluoropropylene copolymer to LiNBTI monomer is 8-9:

1.

4. The method for preparing a multifunctional adhesive according to claim 3, wherein: The preparation process of the LiNBTI monomer is as follows: Step 1: Sodium p-styrenesulfonate and N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide were mixed at once, and oxalyl chloride was added under nitrogen atmosphere to carry out chlorination reaction to obtain p-styrenesulfonyl chloride; Step 2: Add trifluoromethanesulfonamide, an acid-binding agent, and a catalyst into an organic solvent and mix them again, add p-styrenesulfonyl chloride, carry out an amidation reaction, and perform post-treatment to obtain compound A; Step 3: Dissolve compound A in an organic solvent, add 18-22 wt% sodium carbonate aqueous solution, react to form a salt, and post-treat to obtain a crude potassium salt product; recrystallize the crude potassium salt product to obtain a potassium salt; dissolve the potassium salt in an organic solvent, add lithium perchlorate, perform a displacement reaction, and post-treat to obtain a LiNBTI monomer.

5. The method for preparing a multifunctional adhesive according to claim 4, characterized in that: In step 1, the primary mixing temperature is 0°C; the acyl chlorination reaction temperature is 10-30°C, and the reaction time is 22.5-23.5h; In step 2, the secondary mixing temperature is 0°C; the amidation reaction temperature is 10-30°C, and the reaction time is 21.5-22.5h; In step 3, the salt-forming reaction temperature is 0° C., and the stirring speed is 1200-1600 rpm; the replacement reaction temperature is 10-30° C., and the reaction time is 9.5-10.5 h.

6. The method for preparing a multifunctional adhesive according to claim 4, characterized in that: Step 1, in the chlorination reaction, the mass ratio of sodium p-styrenesulfonate, N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide, and oxalyl chloride is 40:1:27-28; Step 2, in the amidation reaction, the mass ratio of trifluoromethanesulfonamide to p-styrenesulfonyl chloride is 14.8-15:23-23.5; In step 3, in the salt-forming reaction, the mass ratio of compound A to 18-22 wt% sodium carbonate aqueous solution is 1-1.3:1; in the displacement reaction, the mass ratio of potassium salt to lithium perchlorate is 3-3.5:

1.

7. Use of a multifunctional adhesive according to any one of claims 1 to 6, characterized in that: The lithium-rich manganese-based positive electrode material, the conductive agent and the multifunctional binder are ground evenly, and an organic solvent is added to obtain a slurry.

8. The use of a multifunctional adhesive according to claim 7, characterized in that: In the raw materials of the slurry, the mass ratio of the lithium-rich manganese-based positive electrode material, the conductive agent, and the multifunctional binder is 8:1:0.8-1.2.

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