A vinyl monomer, a preparation method thereof and a flexible dispersant containing the same
By using a flexible dispersant prepared by a modified vinyl monomer, the problem of poor flexibility of the cathode slurry of lithium-ion battery is solved, and the flexibility of the slurry and the gram capacity of the electrode sheet are improved.
Patent Information
- Application Number
- CN202411972947.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-04-08
AI Technical Summary
The electrode sheet of the positive electrode slurry of lithium-ion batteries is poor in flexibility, resulting in coating cracking, increasing the electrode sheet resistance and reducing the capacity.
An acrylic polymer with a softening effect is prepared by combining a polyether polyol, isocyanate, chain extender, dihydroxycarboxylic acid and blocking agent.
The flexibility of the positive electrode slurry is significantly improved, the phenomenon of electrode sheet coating cracking is reduced, the electrode sheet resistance is reduced, and the gram capacity of lithium-ion batteries is increased.
Smart Images
Figure CN119775528A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a vinyl monomer, a preparation method thereof and a flexible dispersant containing the vinyl monomer. Background Art
[0002] Lithium-ion batteries are widely used in aerospace, national defense, automobile, 3C and other fields due to their advantages such as high specific energy, long cycle life, low self-discharge rate, no memory effect and environmental friendliness.
[0003] Lithium-ion batteries are composed of a positive electrode, a negative electrode, a separator and an electrolyte. Taking lithium iron phosphate batteries as an example, the reaction that occurs during charging is: LiFePO4→Li-xFePO4+xLi+xe-, and the reaction that occurs during discharging is: Li-xFePO4+xLi++xe-→LiFePO4. In short, the working principle of lithium-ion batteries is the flow of electrons between the positive and negative electrodes.
[0004] When lithium-ion batteries are formed, the prepared slurry containing electrode active materials needs to be coated on aluminum foil respectively.
[0005] The positive and negative electrodes are made, so the viscosity of the slurry is directly related to the quality of the coating. In view of the increasingly high requirements for the capacity of lithium batteries, the usual solution is to increase the proportion of electrode active materials in the slurry. However, this will cause the solid content of the slurry to be too high, resulting in viscosity and poor fluidity, which will affect the coating effect of the electrode and further affect the efficiency of the lithium battery preparation process.
[0006] In response to the above problems, the current solution in the industry is to add dispersants to the slurry to improve the dispersion flexibility of the slurry. Existing dispersants include acrylates and phosphates. These dispersants can solve the fluidity problem of the slurry to a certain extent, but they are still not powerful enough to solve the viscosity and gel problems of the slurry. In addition, the flexibility of these dispersants is defective. Summary of the invention
[0007] The present invention aims to solve the problems of poor flexibility of electrode sheets and cracking of electrode sheet coating in positive electrode slurry for lithium ion batteries, which lead to increased resistance of electrode sheets and reduced gram capacity, and provides a vinyl monomer, a preparation method thereof and a flexible dispersant containing the same.
[0008] The present invention provides a vinyl monomer comprising a fragment as shown in formula I
[0009]
[0010] R is selected from One or more constituent fragments of
[0011] Ra is hydrogen, halogen or C1-C6 alkyl; R b is hydrogen, halogen or C1-C6 alkyl; R c is hydrogen or C1-C6 alkyl; R d is hydrogen or C1-C6 alkyl; R e are independently hydrogen, halogen or C1-C6 alkyl; R f is hydrogen, halogen or C1-C6 alkyl; R g is hydrogen or C1-C6 alkyl;
[0012] R1 is One or more of the corresponding fragments, wherein R5 is -NH- or -O-, and n is an integer from 1 to 100;
[0013] R2 is Corresponding to one or more components in the fragment, R 2-1 is hydrogen or C1-C6 alkyl;
[0014] R3 is Corresponding to one or more components in the fragment, R 3-1 is hydrogen or C1-C6 alkyl;
[0015] R4 is selected from
[0016] One or more fragments of a .
[0017] In some embodiments, in the fragment as shown in Formula I, certain groups have the following definitions, and the definitions of the groups not mentioned are as described in any scheme of the present invention (hereinafter referred to as "in some embodiments").
[0018] In some embodiments, R is
[0019] In some embodiments, R1 is Wherein R5 represents -NH- or -O-, and n is an integer of 1-100.
[0020] In some embodiments, R2 is
[0021] In some embodiments, R3 is
[0022] In some embodiments, R4 is
[0023] In some embodiments, R is For example
[0024] In some embodiments, R a is a C1-C6 alkyl group, for example, a methyl group.
[0025] In some embodiments, R1 is Wherein R5 represents -O-, and n is an integer of 15-35.
[0026] In some embodiments, R1 is Wherein R5 represents -O-, and the molecular weight of the raw material of R1 is 1800-2200, for example 2000.
[0027] In some embodiments, the raw material of R1 is polyether polyol N220.
[0028] In some embodiments, R is
[0029] In some embodiments, R2 is
[0030] In some embodiments, R3 is
[0031] In some embodiments, R4 is
[0032] The present invention also provides a polyurethane modified vinyl monomer, the raw materials of which include polyether polyol, isocyanate, chain extender, dihydroxy carboxylic acid and end-capping agent;
[0033] The polyether polyol Wherein R5 is -NH2 or -OH, and n is an integer from 1 to 100;
[0034] The isocyanate is selected from
[0035] One or more of;
[0036] R a is hydrogen, halogen or C1-C6 alkyl; R b is hydrogen, halogen or C1-C6 alkyl; R c is hydrogen or C1-C6 alkyl; R d is hydrogen or C1-C6 alkyl; R e are independently hydrogen, halogen or C1-C6 alkyl; R f is hydrogen, halogen or C1-C6 alkyl; R g is hydrogen or C1-C6 alkyl;
[0037] The chain extender is One or more of the compounds represented by R 2-1 is hydrogen or C1-C6 alkyl;
[0038] The dihydroxycarboxylic acid is One or more of the compounds represented by R 3-1 is hydrogen or C1-C6 alkyl;
[0039] The end-capping agent is selected from One or more of .
[0040] In some embodiments, the polyether polyol is Wherein R5 is -OH, n is an integer of 15-35, preferably polyether polyol N220, for example, dehydrated polyether polyol N220, wherein the dehydrated polyether polyol N220 is prepared by the following preparation method, which comprises dehydrating the polyether polyol N220 at 95-120°C (for example, 105°C) and 0.08-0.12Mpa (for example, 0.1Mpa) for 2-3 hours (1 hour).
[0041] In some embodiments, the molecular weight of the polyether polyol is 1800-2000, such as 2200.
[0042] In some embodiments, the isocyanate is Best For example
[0043] In some embodiments, R a is a C1-C6 alkyl group, for example, a methyl group.
[0044] In some embodiments, the isocyanate is Preferably
[0045]
[0046] In some embodiments, the chain extender is
[0047] In some embodiments, the dihydroxy carboxylic acid is
[0048] In some embodiments, the capping agent is
[0049] In some embodiments, the raw material further includes a solvent.
[0050] In some embodiments, the solvent may be N-methylpyrrolidone.
[0051] In some embodiments, the mass ratio of the polyether polyol to isocyanate is (2-3):1, for example, 2.8:1.
[0052] In some embodiments, the mass ratio of the chain extender to the isocyanate is 1:(4-5), for example 1:4.4.
[0053] In some embodiments, the mass ratio of the dihydroxycarboxylic acid to the isocyanate is 1:(6-7), for example 1:6.3.
[0054] In some embodiments, the mass ratio of the blocking agent to the isocyanate is 1:(2-4), for example, 1:2.7.
[0055] In some embodiments, the mass ratio of the solvent to the isocyanate is (2-3):1, for example 2.8:1.
[0056] In some embodiments, the raw materials consist of polyether polyol, isocyanate, chain extender, dihydroxy carboxylic acid and end-capping agent.
[0057] In some embodiments, the polyurethane modified vinyl monomer is prepared by the following method, which includes the following steps: sequentially adding the polyether polyol, the isocyanate, the chain extender, the dihydroxycarboxylic acid and the end-capping agent into the solvent to react to obtain a polyurethane vinyl monomer.
[0058] In some embodiments, the isocyanate is added at a temperature of 70-80°C, such as 75°C.
[0059] In some embodiments, the reaction time of the polyether polyol and the isocyanate is 0.5-2 hours, such as 1 hour.
[0060] In some embodiments, after the polyether polyol and the isocyanate react, the temperature is lowered and the chain extender is added.
[0061] In some embodiments, the polyether polyol and the isocyanate are reacted and then cooled to 55-65° C., for example, 60° C.
[0062] In some embodiments, the reaction temperature after the chain extender is added is 75-85°C, such as 80°C.
[0063] In some embodiments, the reaction time after the chain extender is added is 0.5-2 hours, such as 1 hour.
[0064] In some embodiments, after the chain extender is added for reaction, the temperature is lowered and the dihydroxycarboxylic acid is added.
[0065] In some embodiments, the reaction temperature after the addition of the dihydroxycarboxylic acid is 65-75°C, for example Such as 70℃.
[0066] In some embodiments, the reaction time after the dihydroxycarboxylic acid is added is 0.5-2 hours, such as 1 hour.
[0067] In some embodiments, after the dihydroxycarboxylic acid is added for reaction, the temperature is lowered and the end-capping agent is added.
[0068] In some embodiments, the reaction temperature after the end-capping agent is added is 65-75°C, such as 70°C.
[0069] In some embodiments, the reaction time after the end-capping agent is added is 0.5-2 hours, for example, 1 hour.
[0070] The present invention also provides an acrylic polymer, the raw materials of which include solvent, acrylic acid, acrylic ester, initiator and the vinyl monomer as mentioned above; the acrylic ester is selected from one or more of butyl acrylate, lauryl acrylate and octadecyl acrylate.
[0071] In some embodiments, the vinyl monomer is used in an amount of 5% to 55% of the total monomers (all olefin-containing raw materials used in the acrylic polymer) by mass percentage, such as 10%, 20% or 50%.
[0072] In some embodiments, the amount of acrylic acid used is 8%-15% of the total monomers, for example, 10%, by mass percentage.
[0073] In some embodiments, the amount of the acrylic acid ester used is 30-90% of the total monomers, such as 40%, 70% or 80%, by mass.
[0074] In some embodiments, the amount of butyl acrylate used is 0-60% of the total monomers, such as 30%, 40% or 50%, by mass.
[0075] In some embodiments, the amount of lauryl acrylate is 25-35% of the total monomers, for example 30%, by mass percentage.
[0076] In some embodiments, the amount of octadecyl acrylate used is 8%-15% of the total monomers, for example, 10%, by mass percentage.
[0077] In some embodiments, the acrylate is selected from two or three of butyl acrylate, lauryl acrylate and octadecyl acrylate.
[0078] In some embodiments, the initiator is azobisisobutyronitrile.
[0079] In some embodiments, the mass ratio of the initiator to the acrylic acid is 1:(40-60), for example 1:50.
[0080] In some embodiments, the solvent is N-methylpyrrolidone.
[0081] In some embodiments, the mass ratio of the solvent to the acrylic acid is (0.5-2):1, for example 1:1.
[0082] In some embodiments, the raw materials consist of the solvent, acrylic acid, acrylic ester, initiator and vinyl monomer.
[0083] In some embodiments, the acrylic polymer is prepared by the following preparation method, which includes adding a mixed solvent, acrylic acid, acrylic ester, an initiator and the vinyl monomer as described above, adding an initiator solution, and polymerizing to obtain the acrylic polymer.
[0084] In some embodiments, the solvent of the initiator solution is N-methylpyrrolidone.
[0085] In some embodiments, in the initiator solution, the mass ratio of the initiator to the solvent is 1:(8-15), for example, 1:10.
[0086] In some embodiments, the initiator solution is added by dropwise addition, and preferably the dropwise addition speed is 8-10 g / h, such as 11 g / h. Preferably the dropwise addition speed is 1-3 hours, such as 2 hours.
[0087] In some embodiments, the polymerization reaction temperature is 80-90°C, such as 85°C.
[0088] In some embodiments, the polymerization reaction time is 3-5 hours, such as 4 hours.
[0089] The present invention also provides a use of the acrylic acid polymer as described above as a dispersant in a battery.
[0090] The present invention also provides a battery slurry, characterized in that it comprises the acrylic polymer, lithium iron phosphate, a binder and a conductive agent as described above.
[0091] The present invention also provides a battery pole piece, characterized in that it comprises the battery slurry as described above.
[0092] On the basis of violating the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.
[0093] The reagents and raw materials used in the present invention are commercially available.
[0094] The positive improvement effect of the present invention is that: the present invention is aimed at the existing positive electrode slurry for lithium ion batteriesThe electrode sheet has poor flexibility and cracks in the electrode coating, which leads to increased electrode sheet resistance and reduced gram capacity. BRIEF DESCRIPTION OF THE DRAWINGS
[0095] Figure 1 This is the infrared image of the polymerized monomer in Example 1. DETAILED DESCRIPTION
[0096] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.
[0097] Example 1
[0098] The dehydration method of polyether polyol N220 is as follows: 200 grams of polyether polyol N220 are added into a four-necked flask with a negative pressure vacuum pumping device, heated to 105°C and dehydrated under negative pressure for 1 hour, with a negative pressure of 0.1 MPa.
[0099] Add 100g of N-methylpyrrolidone to a four-necked flask with a polytetrafluoroethylene stirring rod and heat it to 75°C in an electric heating mantle after sealing. Add 100g of the dehydrated polyether polyol N220 to the four-necked flask in step 1. When the temperature stabilizes to 75°C, add 35.55g of toluene diisocyanate (CAS No. 584-84-9), react for 1 hour, cool to 60°C, add 8g of trimethylolpropane, heat to 80°C and react for 1 hour, cool to 70°C, add 5.6g of dimethylolbutyric acid, react for 1 hour, then add 15g of hydroxyethyl acrylate to cap it, keep warm at 70°C for 1 hour, cool down and filter the material to obtain a homemade vinyl monomer. Its infrared structure is characterized as follows Figure 1 As shown, among them, 3324cm -1 It is the N—H stretching vibration peak on carbamate, 3066cm -1 It is the unsaturated C-H stretching vibration peak of olefins, 2933 cm -1 、2858cm -1 Yes - CH2 stretching vibration peak, 1720cm -1 It is the C=O stretching vibration peak in acrylate.
[0100] Preparation method of flexible dispersant
[0101] The components of the flexible dispersant are shown in Table 1 below:
[0102] Table 1
[0103] Example 2 Example 3 Example 4 Example 5 Dispersant A Dispersant B Dispersant C Dispersant D Homemade monomer 0 10％ 20％ 50％ Butyl acrylate 50％ 40％ 30％ 0 Lauryl acrylate 30％ 30％ 30％ 30％ Octadecyl acrylate 10％ 10％ 10％ 10％ acrylic acid 10％ 10％ 10％ 10％
[0104] The data in the table are the percentages of each monomer in the total monomer mass.
[0105] 100g of N-methylpyrrolidone was added to a four-necked flask with a polytetrafluoroethylene stirring rod and was sealed. The flask was heated to 85°C in an electric heating jacket for standby use. The monomers in the above table were mixed according to the ratio, and a total mass of 100g of mixed monomers was added (as in Example 2, 0g of homemade monomer, 50g of butyl acrylate, 30g of lauryl acrylate, 10g of octadecyl acrylate, and 10g of acrylic acid, respectively). 2g of azobisisobutyronitrile as an initiator was dissolved in 20g of N-methylpyrrolidone, and the mixture was added dropwise to the four-necked flask simultaneously with the mixed monomer. The addition was completed in 2 hours, and the mixture was kept warm for 2 hours and cooled to 40°C to obtain a flexible dispersant for lithium iron phosphate positive electrode slurry.
[0106] The polymer softener of the above-mentioned embodiment is used in the positive electrode slurry formula, and the components of the positive electrode slurry of the lithium battery and N-methylpyrrolidone are wet-mixed in a planetary degassing machine (the slurry solid content is 60%) to obtain the positive electrode slurry of the embodiment. The blank group is the positive electrode slurry obtained without adding a flexible dispersant. The positive electrode slurry is coated on the carbon-coated foil with a small coating machine and then heated and baked to obtain a positive electrode plate. The plate is folded in half to observe whether the plate leaks foil or cracks. The flexibility of the plate is judged by the number of folds when the foil leaks or cracks appear. The proportions of the positive electrode slurry are shown in Table 2 (based on 100% total solid mass), and the blank group is the one without adding a flexible dispersant. The flexibility results of the pole pieces of each embodiment are shown in Table 3:
[0107] Table 2 Amount of each component of the positive electrode slurry in the embodiment
[0108]
[0109]
[0110] Table 3 Example slurry pole piece test performance
[0111]
[0112] It can be seen from Table 3 that the polymer in the embodiment has certain dispersibility and significantly improves the folding flexibility of the prepared electrode, and has a good softening effect. The slurry prepared by the dispersant of the present invention has a low viscosity coefficient. Furthermore, the electrode prepared by the dispersant of the present invention has a large number of folding times.
Claims
1. A vinyl monomer, characterized in that It contains a fragment as shown in formula I R is selected from One or more constituent fragments of R a is hydrogen, halogen or C1-C6 alkyl; R b is hydrogen, halogen or C1-C6 alkyl; R c is hydrogen or C1-C6 alkyl; R d is hydrogen or C1-C6 alkyl; R e are independently hydrogen, halogen or C1-C6 alkyl; R f is hydrogen, halogen or C1-C6 alkyl; R g is hydrogen or C1-C6 alkyl; R1 is One or more of the corresponding fragments, wherein R5 is -NH- or -O-, and n is an integer from 1 to 100; R2 is Corresponding to one or more components in the fragment, R 2-1 is hydrogen or C1-C6 alkyl; R3 is Corresponding to one or more components in the fragment, R 3-1 is hydrogen or C1-C6 alkyl; R4 is selected from One or more fragments of a .
2. The vinyl monomer according to claim 1, characterized in that The vinyl monomer meets one or more of the following conditions: (1) R is (2) R1 is Wherein R5 represents -NH- or -O-, and n is an integer of 1-100; (3) R2 is (4) R3 is 3. The vinyl monomer according to claim 1 or 2, characterized in that The vinyl monomer meets one or more of the following conditions: (1) R is For example (2)R a is a C1-C6 alkyl group, such as a methyl group; (3) R1 is Wherein R5 represents -O-, and n is an integer from 15 to 35; and (4)R1 is Wherein R5 represents -O-, and the molecular weight of the raw material of R1 is 1800-2200, for example 2000; Preferably, the vinyl monomer meets one or more of the following conditions: (1) The raw material of R1 is polyether polyol N220; (2) R is (3) R3 is and (4)R4 is 4. A polyurethane-modified vinyl monomer, characterized in that: Its raw materials include polyether polyol, isocyanate, chain extender, dihydroxy carboxylic acid and end-capping agent; The polyether polyol Wherein R5 is -NH2 or -OH, and n is an integer from 1 to 100; The isocyanate is selected from One or more of; R a is hydrogen, halogen or C1-C6 alkyl; R b is hydrogen, halogen or C1-C6 alkyl; R c is hydrogen or C1-C6 alkyl; R d is hydrogen or C1-C6 alkyl; R e are independently hydrogen, halogen or C1-C6 alkyl; R f is hydrogen, halogen or C1-C6 alkyl; R g is hydrogen or C1-C6 alkyl; The chain extender is One or more of the compounds represented by R 2-1 is hydrogen or C1-C6 alkyl; The dihydroxycarboxylic acid is One or more of the compounds represented by R 3-1 is hydrogen or C1-C6 alkyl; The end-capping agent is selected from One or more of .
5. The polyurethane-modified vinyl monomer according to claim 4, characterized in that: The raw materials meet one or more of the following conditions: (1) The polyether polyol is Wherein R5 is -OH, n is an integer of 15-35, and / or, the molecular weight of the polyether polyol is 1800-2000, for example, 2200, preferably polyether polyol N220, for example, dehydrated polyether polyol N220, the dehydrated polyether polyol N220 is prepared by the following preparation method, which comprises dehydrating the polyether polyol N220 at 95-120° C. (for example, 105° C.) and 0.08-0.12 MPa (for example, 0.1 MPa) for 2-3 hours (1 hour); (2) The isocyanate is Best For example (3)R a is a C1-C6 alkyl group, such as a methyl group; Preferably, the raw materials meet one or more of the following conditions: (1) The isocyanate is (2) The chain extender is (3) The dihydroxycarboxylic acid is (4) The end-capping agent is and (5) the raw material further includes a solvent; More preferably, the raw materials meet one or more of the following conditions: (1) The solvent is N-methylpyrrolidone; (2) The mass ratio of the polyether polyol to the isocyanate is (2-3):1, for example, 2.8:1; (3) The mass ratio of the chain extender to the isocyanate is 1:(4-5), for example 1:4.4; (4) The mass ratio of the dihydroxycarboxylic acid to the isocyanate is 1:(6-7), for example 1:6.3; (5) The mass ratio of the blocking agent to the isocyanate is 1:(2-4), for example, 1:2.7; and (6) the mass ratio of the solvent to the isocyanate is (2-3):1, for example, 2.8:1; Preferably, the polyurethane modified vinyl monomer is prepared by the following method, which comprises the following steps: sequentially adding the polyether polyol, the isocyanate, the chain extender, the dihydroxy carboxylic acid and the end-capping agent into the solvent to react to obtain a polyurethane vinyl monomer; Optimally, the preparation method satisfies one or more of the following conditions: (1) The isocyanate is added at a temperature of 70-80° C., for example 75° C.; (2) the reaction time of the polyether polyol and the isocyanate is 0.5-2 hours, for example, 1 hour; (3) After the polyether polyol and the isocyanate react, the temperature is lowered and the chain extender is added; (4) adding the chain extender to react, cooling, and adding the dihydroxycarboxylic acid; (5) adding the dihydroxycarboxylic acid to react, cooling, and adding the end-capping agent; and (6) the raw materials consist of polyether polyol, isocyanate, chain extender, dihydroxy carboxylic acid and end-capping agent; For example, the preparation method satisfies one or more of the following conditions: (1) After the polyether polyol and the isocyanate react, the temperature is lowered to 55-65° C., for example, 60° C.; (2) the reaction temperature after the chain extender is added is 75-85°C, for example 80°C; (3) The reaction time after the chain extender is added is 0.5-2 hours, for example 1 hour; (4) the reaction temperature after the dihydroxycarboxylic acid is added is 65-75° C., for example 70° C.; (5) The reaction time after the addition of the dihydroxycarboxylic acid is 0.5-2 hours, for example 1 hour; (6) The reaction temperature after the end-capping agent is added is 65-75° C., for example 70° C.; and (7) the reaction time after the end-capping agent is added is 0.5-2 hours, for example 1 hour.
6. An acrylic acid polymer, characterized in that The raw materials include solvent, acrylic acid, acrylate, initiator and the vinyl monomer as claimed in any one of claims 1 to 5; the acrylate is selected from one or more of butyl acrylate, lauryl acrylate and octadecyl acrylate.
7. The acrylic polymer according to claim 6, characterized in that The raw materials meet one or more of the following conditions: (1) The amount of the vinyl monomer is 5% to 55% of the total monomers, such as 10%, 20% or 50% by mass; (2) In terms of mass percentage, the amount of acrylic acid used is 8% to 15% of the total monomers, for example, 10%; (3) The amount of the acrylic acid ester is 30-90% of the total monomers, such as 40%, 70% or 80% by mass; (4) The amount of butyl acrylate is 0-60% of the total monomers, for example 30%, 40% or 50% by mass; (5) In terms of mass percentage, the amount of lauryl acrylate is 25-35% of the total monomers, for example, 30%; (6) In terms of mass percentage, the amount of octadecyl acrylate is 8% to 15% of the total monomers, for example, 10%; (7) The acrylic acid ester is selected from two or three of butyl acrylate, lauryl acrylate and octadecyl acrylate; (8) The initiator is azobisisobutyronitrile; (9) The mass ratio of the initiator to the acrylic acid is 1:(40-60), for example 1:50; (10) The solvent is N-methylpyrrolidone; (11) The mass ratio of the solvent to the acrylic acid is (0.5-2):1, for example 1:1; and (12) the raw materials consist of the solvent, acrylic acid, acrylic ester, initiator and vinyl monomer. Preferably, the acrylic polymer is prepared by the following preparation method, which comprises a mixed solvent, acrylic acid, acrylic ester, an initiator and the vinyl monomer as described above, adding an initiator solution, and polymerizing to obtain the acrylic polymer; More preferably, the preparation method satisfies one or more of the following conditions: (1) The solvent of the initiator solution is N-methylpyrrolidone; (2) In the initiator solution, the mass ratio of the initiator to the solvent is 1:(8-15), for example 1:10; (4) the initiator solution is added dropwise, preferably the dropping speed is 8-10 g / h, for example 11 g / h; and / or the dropping speed is 1-3 hours, for example 2 hours; (5) The reaction temperature of the polymerization reaction is 80-90°C, for example 85°C; The reaction time of the polymerization reaction (6) is 3-5 hours, for example 4 hours.
8. Use of the acrylic acid polymer according to any one of claims 1 to 7 as a dispersant in a battery.
9. A battery slurry, characterized in that: The method comprises the acrylic polymer as claimed in claim 8, lithium iron phosphate, a binder and a conductive agent.
10. A battery pole piece, characterized in that: It comprises the battery slurry as claimed in claim 9.