Dispersing agent, dispersion liquid and preparation method and application of dispersing agent and dispersion liquid

Abstract

The invention provides a dispersant, a dispersion liquid, and a preparation method and application thereof. The dispersant comprises a copolymer containing a nonionic hydrophilic group and a long-chain hydrophobic group or a derivative thereof, an infrared absorption spectrum of the dispersant obtained by an attenuated total reflection method through Fourier transform infrared spectroscopy has an absorption peak at 1725-1740 cm <-1 >, the absorption peak exists at 2840-2960 cm <-1 >, and the peak width of the absorption peak at 2840-2960 cm <-1 > is 90-500 cm <-1 >; the dispersing agent is prepared from the following raw materials: an acrylic monomer, a long-chain acrylate monomer, an acrylamide monomer and a nonionic hydrophilic monomer. Dispersion liquid containing the dispersing agent provided by the invention has a good dispersion effect on polymer microsphere powder, diaphragm coating slurry prepared from the dispersion liquid has excellent stability, and a battery diaphragm prepared from the diaphragm coating slurry is low in air permeability increment.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries, and in particular relates to a dispersant, a dispersion liquid, and a preparation method and application thereof. Background Art

[0002] Dispersants used on the market to disperse polymer microsphere powders (such as PVDF powders) in battery separator coating slurries are usually used by adding water to the dispersant in advance to form an aqueous solution, and then dispersing the polymer microsphere powders to prepare the battery separator coating slurry. The dispersion effect of the polymer microsphere powders has not yet reached the optimal ideal state, resulting in poor adhesion performance, air permeability uniformity, etc. of the prepared battery separator.

[0003] Therefore, it is necessary to develop a dispersant with better dispersion effect on polymer microsphere powder. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a dispersant, a dispersion liquid, a preparation method and an application thereof. The dispersion liquid containing the dispersant has a good dispersing effect on polymer microsphere powder, the diaphragm coating slurry prepared using the dispersion liquid has excellent stability, and the battery diaphragm prepared using the diaphragm coating slurry has a low air permeability increase.

[0005] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a dispersant, comprising a copolymer containing a nonionic hydrophilic group and a long-chain hydrophobic group or a derivative thereof, wherein the dispersant has an infrared absorption spectrum of 1725-1740 cm-1 obtained by Fourier transform infrared spectroscopy using attenuated total reflectance. -1 (e.g. 1727cm -1 、1729cm -1 、1731cm -1 、1733cm -1 、1735cm -1 、1737cm -1 or 1739cm -1 The absorption peaks are at 2840~2960cm -1 (e.g. 2840cm -1 、2860cm -1 、2880cm -1 , 2900cm -1 、2920cm -1 or 2940cm -1 There is an absorption peak at 2840~2960cm -1 The absorption peak width is 90~500cm -1(For example 95cm -1 、98cm -1 , 100cm -1 , 150cm -1 , 200cm -1 , 250cm -1 , 300cm -1 、350cm -1 , 400cm -1 or 450cm -1 etc.), more preferably 100 cm -1 ~500cm -1 The raw materials for preparing the dispersant include acrylic monomers, long-chain acrylic ester monomers, acrylamide monomers and non-ionic hydrophilic monomers.

[0007] In the present invention, the special wave number is between 1725 and 1740 cm -1 The absorption peak is the infrared characteristic peak of C=O. C=O mainly comes from non-ionic hydrophilic groups, which can be the carboxyl group of acrylic monomers, the amide group of acrylamide monomers and the hydrophilic group in non-ionic hydrophilic monomers; the wave number is 2840~2960cm -1 The absorption peaks are characteristic absorption peaks of the asymmetric stretching vibration absorption peaks and / or symmetric stretching vibration absorption peaks of the CH on the methylene group, mainly originating from the hydrocarbon backbone of the copolymer or its derivatives and the long-chain hydrophobic groups in the non-ionic hydrophilic monomer. By anchoring the surface of the polymer microsphere powder with the C=O group and the long-chain hydrophobic group, respectively, the dispersant is adsorbed on the surface of the polymer microsphere powder to form a core-shell microsphere structure. By utilizing the combination of non-ionic hydrophilic groups and long-chain hydrophobic groups, a dual mechanism of "hydrogen bonding + hydrophobic interaction" is achieved, breaking through the limitations of traditional single polar adsorption, significantly outperforming the effect of a single polar group and significantly improving the dispersion stability of the polymer microsphere powder.

[0008] In the present invention, the long chain refers to a molecular chain with 8 or more carbon atoms (e.g., 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20). Controlling the number of carbon atoms within the above range is beneficial for synthesizing a dispersant with a suitable molecular chain length and a suitable viscosity. It is also beneficial for controlling the specific absorption peak and its proportion in the infrared absorption spectrum of the dispersant, so that when used in a coating slurry, it has a better dispersing effect on the polymer powder. Preferably, the long chain is a molecular chain with 12 to 16 carbon atoms (e.g., 12, 13, 14, 15, 16, etc.).

[0009] Preferably, set 1725-1740cm -1 The absorbance of the absorption peak at 2915-2930 cm is 100%, and the dispersant has a peak at 2915-2930 cm -1The absorbance of the absorption peak at is 60% to 90% (for example, 65%, 66%, 70%, 75%, 80% or 85%, etc.).

[0010] In the present invention, when setting 1725-1740cm -1 The absorbance of the absorption peak at 2915-2930 cm is 100%, and the dispersant has a peak at 2915-2930 cm -1 There is an absorption peak at , and its absorbance is preferably 60% to 90%, which means that the dispersant contains both non-ionic hydrophilic groups and long-chain hydrophobic groups and the proportion of the two is controlled within an appropriate range, which can further balance the affinity of the dispersant with the polymer microsphere powder (such as PVDF powder) and the affinity with the water solvent, so that the dispersant and the polymer microsphere powder form good binding properties, and the polymer microsphere powder can have a good dispersion effect in water.

[0011] Preferably, the acrylic monomer includes acrylic acid and / or methacrylic acid.

[0012] In the present invention, the long-chain acrylic ester monomer refers to a long-chain acrylic ester monomer having 8 to 20 carbon atoms (eg, 10, 12, 14, 16, or 18).

[0013] Preferably, the long-chain acrylic acid ester monomer includes any one of dodecyl acrylate, dodecyl methacrylate, tetradecyl acrylate, tetradecyl methacrylate, hexadecyl acrylate or hexadecyl methacrylate, or a combination of at least two thereof.

[0014] Preferably, the acrylamide monomers include acrylamide and / or methacrylamide.

[0015] Preferably, the nonionic hydrophilic monomer includes any one or a combination of at least two of the monomers having the structure represented by Formula I, Formula II or Formula III.

[0016]

[0017]

[0018] Among them, R1, R2, and R3 are each independently selected from H, an alkyl group with 1 to 5 carbon atoms (for example, 2, 3, or 4, etc.), or an aryl group with 6 to 12 carbon atoms (for example, 7, 8, 9, 10, or 11, etc.); R4 is selected from an alkylene group with 2 to 4 carbon atoms (for example, 3, etc.).

[0019] Preferably, the monomer having the structure shown in Formula I includes any one of N-vinylformamide, N-vinylacetamide or N-vinyl-N-methylacetamide, or a combination of at least two thereof.

[0020] Preferably, the monomer having the structure shown in Formula II includes N-vinyl pyrrolidone and / or N-vinyl-ε-caprolactam.

[0021] Preferably, the monomer having the structure represented by Formula III comprises any one of methyl vinyl sulfone, phenyl vinyl sulfone or vinyl ethyl sulfone, or a combination of at least two thereof.

[0022] Preferably, the raw materials for preparing the dispersant further include polymerizable sulfonate.

[0023] Preferably, the polymerizable sulfonate comprises sodium 2-acrylamido-2-methylpropanesulfonate.

[0024] Preferably, the raw materials for preparing the dispersant further include acrylonitrile monomers.

[0025] Preferably, the acrylonitrile monomer includes acrylonitrile and / or methacrylonitrile.

[0026] Preferably, the raw materials for preparing the dispersant include the following components in parts by weight: 80 to 160 parts (e.g., 90 parts, 100 parts, 110 parts, 120 parts, 130 parts, 140 parts or 150 parts) of acrylic acid monomer, 60 to 100 parts (e.g., 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts or 95 parts) of acrylamide monomer, 100 to 300 parts (e.g., 120 parts, 140 parts, 160 parts, 180 parts, 200 parts, 220 parts, 240 parts) of nonionic hydrophilic monomer. , 260 parts or 280 parts, etc.), 3-30 parts of polymerizable sulfonate (for example, 6 parts, 9 parts, 12 parts, 15 parts, 18 parts, 21 parts, 24 parts or 27 parts, etc.), 180-260 parts of acrylonitrile monomer (for example, 190 parts, 200 parts, 210 parts, 220 parts, 230 parts, 240 parts or 250 parts, etc.) and 300-350 parts of long-chain acrylate monomer (for example, 305 parts, 310 parts, 315 parts, 320 parts, 325 parts, 330 parts, 335 parts, 340 parts or 345 parts, etc.).

[0027] Preferably, the raw materials for preparing the dispersion further include 3 to 5 parts by weight of an initiator, for example, 3.2 parts by weight, 3.4 parts by weight, 3.6 parts by weight, 3.8 parts by weight, 4.0 parts by weight, 4.2 parts by weight, 4.4 parts by weight, 4.6 parts by weight or 4.8 parts by weight.

[0028] Preferably, the initiator comprises ammonium persulfate.

[0029] Preferably, the raw materials for preparing the dispersant further include 20 to 30 parts by weight of an emulsifier, for example, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight or 29 parts by weight.

[0030] Preferably, the emulsifier includes polyoxyethylene octylphenol ether-10 (emulsifier OP-10).

[0031] In the present invention, acrylic acid monomers, acrylamide monomers and non-ionic hydrophilic monomers are added to the raw materials for preparing the dispersant. The acrylic acid monomers and acrylamide monomers allow the prepared dispersant to contain non-ionic hydrophilic groups such as carboxylic acid groups and amide groups. The non-ionic hydrophilic monomers also contain non-ionic hydrophilic groups. After the dispersant is combined with the polymer microsphere powder, the surface of the core-shell microsphere structure formed is hydrophilic, which helps to improve the dispersibility in water. Long-chain acrylic acid ester monomers and acrylonitrile monomers are used as hydrophobic monomers. Their addition helps to adjust the hydrophobic-hydrophilic balance of the polymer chain and enhance the compatibility with the polymer microsphere powder.

[0032] In the present invention, the polymerizable sulfonate in the raw material for preparing the dispersant can introduce sulfonic acid groups, which can enhance the stability of the dispersion system through electrostatic repulsion and improve salt resistance. Its strong ionization characteristics can prevent particle aggregation and can perform excellently in an electrolyte-containing environment.

[0033] In a second aspect, the present invention provides a dispersion comprising the dispersant as described in the first aspect.

[0034] Preferably, the raw materials for preparing the dispersion include the following components in parts by weight: 80-160 parts (e.g., 90 parts, 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, or 150 parts) of acrylic acid monomer, 60-100 parts (e.g., 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, or 95 parts) of acrylamide monomer, 100-300 parts (e.g., 120 parts, 140 parts, 160 parts, 180 parts, 200 parts, 220 parts, 240 parts, 260 parts, or 280 parts) of nonionic hydrophilic monomer, 30-50 parts (e.g., 50 parts) of polymerizable sulfonate aqueous solution. For example, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, 42 parts, 44 parts, 46 parts or 48 parts, etc.), 180-260 parts of acrylonitrile monomer (for example, 190 parts, 200 parts, 210 parts, 220 parts, 230 parts, 240 parts or 250 parts, etc.), 300-350 parts of long-chain acrylate monomer (for example, 305 parts, 310 parts, 315 parts, 320 parts, 325 parts, 330 parts, 335 parts, 340 parts or 345 parts, etc.) and 20-30 parts of emulsifier (for example, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts or 29 parts, etc.).

[0035] Preferably, the emulsifier includes polyoxyethylene octylphenol ether-10 (emulsifier OP-10).

[0036] Preferably, the raw materials for preparing the dispersion further include 4000 to 4600 parts by weight of water, for example, 4000 parts by weight, 4050 parts by weight, 4100 parts by weight, 4150 parts by weight, 4200 parts by weight, 4250 parts by weight, 4300 parts by weight, 4350 parts by weight, 4400 parts by weight, 4450 parts by weight, 4500 parts by weight or 4550 parts by weight, etc.

[0037] Preferably, the raw materials for preparing the dispersion further include 70 to 100 parts by weight of a first neutralizer, for example, 73 parts by weight, 76 parts by weight, 79 parts by weight, 82 parts by weight, 85 parts by weight, 88 parts by weight, 91 parts by weight, 94 parts by weight or 97 parts by weight.

[0038] Preferably, the raw materials for preparing the dispersion further include a second neutralizing agent.

[0039] Preferably, the first neutralizing agent and the second neutralizing agent each independently comprise aqueous ammonia and / or sodium hydroxide.

[0040] Preferably, the mass percentage concentration of the polymerizable sulfonate in the polymerizable sulfonate aqueous solution is 20% to 60%, for example, 25%, 30%, 35%, 40%, 45%, 50% or 55%.

[0041] Preferably, the D50 particle size of the dispersion is 10 to 100 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm or 90 nm.

[0042] In the present invention, the D50 particle size of the dispersion refers to the D50 particle size of the polymer particles in the dispersion.

[0043] Preferably, the solid content of the dispersion is 17% to 24%, for example, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, 23% or 23.5%, etc.

[0044] Preferably, the viscosity of the dispersion at 25° C. is 1500 to 5000 cP.s, for example, 2000 cP.s, 2500 cP.s, 3000 cP.s, 3500 cP.s, 4000 cP.s or 4500 cP.s.

[0045] Preferably, the pH of the dispersion is 7 to 9, for example, 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6 or 8.8.

[0046] In a third aspect, the present invention provides a method for preparing the dispersion as described in the second aspect, the preparation method comprising the following steps: mixing acrylic monomers, long-chain acrylic ester monomers, acrylamide monomers, non-ionic hydrophilic monomers, optionally a polymerizable sulfonate aqueous solution, optionally an emulsifier, optionally an acrylonitrile monomer, optionally a first neutralizing agent, optionally an initiator, optionally water and optionally a second neutralizing agent, and reacting to obtain the dispersion.

[0047] Preferably, the preparation method comprises the following steps:

[0048] (1) A first neutralizing agent, a portion of water, and an acrylic monomer are mixed to obtain a first intermediate product.

[0049] (2) The first intermediate product obtained in step (1), an acrylamide monomer, a nonionic hydrophilic monomer and a polymerizable sulfonate aqueous solution are mixed to obtain a second intermediate product.

[0050] (3) The second intermediate product obtained in step (2), an emulsifier, an acrylonitrile monomer and a long-chain acrylate monomer are mixed to obtain a third intermediate product.

[0051] (4) mixing the third intermediate product obtained in step (3), the initiator and the remaining water, reacting them, and adding a second neutralizer to adjust the pH to 7 to 9 (e.g., 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6 or 8.8, etc.) to obtain the dispersion.

[0052] In the present invention, step (1) uses a first neutralizing agent to react with acrylic acid monomers to generate acrylic acid salt monomers, and adjusts the pH of the system to provide a water-soluble monomer environment for subsequent polymerization.

[0053] Preferably, based on the total mass of water being 100%, the mass of the water in the portion is 60% to 100%, for example, 65%, 70%, 75%, 80%, 85%, 90% or 95%.

[0054] Preferably, the mixing in step (1) is to mix the first neutralizing agent and a portion of water, and then dropwise add the acrylic monomer and stir and mix.

[0055] Preferably, the dripping time in step (1) is ≥10 min, for example, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min or 28 min, etc.

[0056] Preferably, the stirring temperature in step (1) is 5-10°C, such as 6°C, 7°C, 8°C or 9°C.

[0057] Preferably, the stirring speed in step (1) is 50 to 300 rpm (for example, 80 rpm, 100 rpm, 120 rpm, 140 rpm, 160 rpm, 180 rpm, 200 rpm, 220 rpm, 240 rpm, 260 rpm or 280 rpm, etc.), and more preferably 200 rpm.

[0058] In the present invention, the time for adding the mixture with acrylic acid in step (1) dropwise is preferably ≥10 min, which helps to maintain the temperature of the system stable. If the addition time is less than 10 minutes, more heat will be generated, making the system temperature unstable. The stirring speed is preferably controlled at 50-300 rpm to avoid that too slow stirring speed affects the homogeneity of the system, while too fast stirring speed will cause excessive system solution to splash onto the bottle wall, resulting in a reduction of reactive substances.

[0059] Preferably, step (2) comprises adding acrylamide to the first intermediate product obtained in step (1) for dissolution, and dropwise adding a nonionic hydrophilic monomer and a polymerizable sulfonate aqueous solution to obtain a second intermediate product.

[0060] Preferably, step (2) is carried out at a stirring speed of 50 to 300 rpm (e.g., 80 rpm, 100 rpm, 120 rpm, 140 rpm, 160 rpm, 180 rpm, 200 rpm, 220 rpm, 240 rpm, 260 rpm or 280 rpm, etc.).

[0061] Preferably, the dropping time in step (2) is 5 to 10 min, for example, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min or 9.5 min.

[0062] In the present invention, the dripping time of step (2) is preferably 5 to 10 minutes. If the time is too short, the viscosity of the system will increase instantly, hindering mass transfer and heat dissipation, resulting in local temperature increase or reaction runaway. If the time is too long, it is easy to induce side reactions, such as monomer hydrolysis or chain transfer.

[0063] Preferably, the dissolution time is 20 to 30 min, for example, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min or 29 min.

[0064] Preferably, step (3) comprises mixing the second intermediate product with an emulsifier, adding acrylonitrile and a long-chain acrylic ester monomer dropwise, and then stirring at high speed for emulsification to obtain a third intermediate product.

[0065] Preferably, the mixing with the emulsifier in step (3) is carried out at a stirring speed of 30 to 60 rpm (eg, 35 rpm, 40 rpm, 45 rpm, 50 rpm or 55 rpm, etc.).

[0066] In the present invention, when the emulsifier is added, the stirring speed is preferably 30 to 60 rpm. If the stirring speed is too low, the added emulsifier cannot be evenly distributed in the system. If the stirring speed is too high, severe foaming will occur after the emulsifier is added.

[0067] Preferably, the dropwise addition of acrylonitrile and long-chain acrylic ester monomers is carried out at a stirring speed of 30 to 50 rpm (e.g., 33 rpm, 36 rpm, 39 rpm, 42 rpm, 45 rpm or 48 rpm, etc.), and the dropwise addition time is 3 to 6 h, e.g., 3.5 h, 4 h, 4.5 h, 5 h or 5.5 h, etc.

[0068] Preferably, the high-speed stirring speed is 1000-6000 rpm (eg, 2000 rpm, 3000 rpm, 4000 rpm, or 5000 rpm), and the high-speed stirring time is 4-10 min, eg, 5 min, 6 min, 7 min, 8 min, or 9 min.

[0069] In the present invention, controlling the stirring speed and the raw material addition rate within a certain range is conducive to a more complete reaction and reduces side reactions. High-speed shearing at 1000 to 6000 rpm helps control the microsphere particle size distribution and avoids mechanical shearing from destroying the particle structure.

[0070] Preferably, the mixing in step (4) comprises first dissolving the initiator in water and then mixing it with the third intermediate product.

[0071] Preferably, the reaction in step (4) is carried out under an inert gas atmosphere, and the inert gas flow rate is 15 to 25 mL / min, for example, 16 mL / min, 17 mL / min, 18 mL / min, 19 mL / min, 20 mL / min, 21 mL / min, 23 mL / min or 24 mL / min.

[0072] In the present invention, the initiator is protected by an inert gas during the thermal initiation reaction, which helps to reduce side reactions and improve polymerization efficiency.

[0073] Preferably, the inert gas comprises argon.

[0074] Preferably, the reaction temperature in step (4) is 60-70°C, for example, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C or 69°C.

[0075] Preferably, the reaction time of step (4) is 5 to 10 h, for example, 5.5 h, 6 h, 6.5 h, 7.0 h, 7.5 h, 8.0 h, 8.5 h, 9.0 h or 9.5 h.

[0076] Preferably, the reaction in step (4) is carried out under stirring at a speed of 100 to 300 rpm / min, for example, 120 rpm / min, 140 rpm / min, 160 rpm / min, 180 rpm / min, 200 rpm / min, 220 rpm / min, 240 rpm / min, 260 rpm / min or 280 rpm / min.

[0077] Preferably, after adjusting the pH to 7-9 (e.g., 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6 or 8.8, etc.) in step (4), the step of adding water to adjust the solid content is further included.

[0078] In a fourth aspect, the present invention provides a diaphragm coating slurry, which includes the following components in parts by weight: 1 to 20 parts (for example, 3 parts, 5 parts, 7 parts, 9 parts, 11 parts, 13 parts, 15 parts, 17 parts or 19 parts) of the dispersion described in the second aspect or the dispersion prepared by the preparation method described in the third aspect, 1 to 30 parts (for example, 3 parts, 6 parts, 9 parts, 12 parts, 15 parts, 18 parts, 21 parts, 24 parts or 27 parts, etc.) of polymer microsphere powder, 0 to 1 part (for example, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part or 0.9 part, etc.) of a wetting agent, and 30 to 120 parts (for example, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts or 110 parts, etc.) of water.

[0079] Preferably, the polymer microsphere powder includes any one or a combination of at least two of PVDF homopolymer, PVDF-HFP copolymer, a derivative of PVDF homopolymer, or a derivative of PVDF-HFP copolymer.

[0080] Preferably, the wetting agent includes any one of sodium lauryl sulfate, sodium dodecylbenzene sulfonate, polyether siloxane, or polyoxyethylene alkyl ether-polyoxyethylene polyoxypropylene block copolymer, or a combination of at least two thereof.

[0081] In the present invention, the diaphragm coating slurry can be prepared illustratively by the following method: first mixing the dispersion as described in the second aspect or the dispersion prepared by the preparation method as described in the third aspect and part of the water, adding the polymer microsphere powder and mixing for the second time, adding the remaining water and the aqueous wetting agent and mixing for the third time, and vacuum defoaming to obtain the diaphragm coating slurry.

[0082] Preferably, in the preparation of the diaphragm coating slurry, the mass of the water portion is 60% to 99%, such as 65%, 70%, 75%, 80%, 85%, 90% or 95%, based on the total mass of water as 100%.

[0083] Preferably, the stirring speed of the first mixing is 100-200 rpm (for example, 110 rpm, 120 rpm, 130 rpm, 140 rpm, 150 rpm, 160 rpm, 170 rpm, 180 rpm or 190 rpm, etc.), and the time is 5-20 min (for example, 7 min, 9 min, 11 min, 13 min, 15 min, 17 min or 19 min, etc.).

[0084] Preferably, the stirring speed of the second mixing is 600-1000 rpm (for example, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm or 950 rpm, etc.), and the time is 40-120 min (for example, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min or 110 min, etc.).

[0085] Preferably, the stirring speed of the third mixing is 100-200 rpm (for example, 110 rpm, 120 rpm, 130 rpm, 140 rpm, 150 rpm, 160 rpm, 170 rpm, 180 rpm or 190 rpm, etc.), and the time is 5-20 min (for example, 7 min, 9 min, 11 min, 13 min, 15 min, 17 min or 19 min, etc.).

[0086] Preferably, the vacuum degree of the vacuum defoaming is 0.001-0.1 MPa, for example, 0.005 MPa, 0.01 MPa, 0.02 MPa, 0.03 MPa, 0.04 MPa, 0.05 MPa, 0.06 MPa, 0.07 MPa, 0.08 MPa or 0.09 MPa.

[0087] In a fifth aspect, the present invention provides a battery separator, comprising a substrate and a coating layer on at least one side of the substrate, wherein the coating layer comprises the dispersant as described in the first aspect or the dispersant prepared by the preparation method as described in the third aspect, or the coating layer is prepared from the separator coating slurry as described in the fourth aspect as claimed in claim 1.

[0088] In a sixth aspect, the present invention provides a battery, comprising the battery separator as described in the fourth aspect.

[0089] Compared with the prior art, the present invention has the following beneficial effects:

[0090] The dispersant of the present invention contains a copolymer or a derivative thereof containing both nonionic hydrophilic groups and long-chain hydrophobic groups, which can break through the limitations of traditional single polarity adsorption. The dispersion containing the dispersant has a good dispersing effect on polymer microsphere powder. The diaphragm coating slurry prepared using the dispersion has excellent stability. The battery diaphragm prepared using the diaphragm coating slurry has a low air permeability increase. The diaphragm coating slurry prepared using the dispersion has a D10 particle size ≤8.5μm, a D50 particle size of 4.5μm≤<14.5μm, and a D90 particle size ≤70μm, and there is no precipitation or stratification after being placed for ≥1 day, and the battery diaphragm prepared using the diaphragm coating slurry has an air permeability increase of ≤17.5s; preferably, the diaphragm coating slurry has a D10 particle size <2.0μm, a D50 particle size of 2.0μm≤<6.0μm, and a D90 particle size <20μm, and there is no precipitation or stratification after being placed for ≥5 days, and the battery diaphragm prepared using the diaphragm coating slurry has an air permeability increase of ≤12.5s. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Figure 1 This is the infrared spectrum of the dispersion provided in Example 1 after drying;

[0092] Figure 2 This is the infrared spectrum of the dispersion provided in Comparative Example 4 after drying. DETAILED DESCRIPTION

[0093] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0094] Some of the components in the following examples and comparative examples are as follows, which are conventional commercially available products.

[0095] Sodium hydroxide: Shanghai Aladdin Biochemical Technology Co., Ltd., catalog number: S111498;

[0096] Acrylic acid: Shanghai Aladdin Biochemical Technology Co., Ltd., catalog number: A397753;

[0097] Acrylamide: Shanghai Aladdin Biochemical Technology Co., Ltd., catalog number: A108465;

[0098] N-vinylpyrrolidone: Shanghai Aladdin Biochemical Technology Co., Ltd., catalog number: V106155;

[0099] Sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution: 50% sodium 2-acrylamido-2-methylpropanesulfonate; Shanghai Aladdin Biochemical Technology Co., Ltd., Catalog Number: A303866

[0100] Emulsifier OP-10: Shanghai Aladdin Biochemical Technology Co., Ltd., product number: O113278;

[0101] Acrylonitrile: Shanghai Aladdin Biochemical Technology Co., Ltd., product number: A299303;

[0102] Dodecyl acrylate: Shanghai Aladdin Biochemical Technology Co., Ltd., product number: L138491;

[0103] Ammonia: Shanghai Aladdin Biochemical Technology Co., Ltd., product number: A112079.

[0104] Example 1

[0105] This embodiment provides a dispersant, a dispersion and a preparation method thereof, and the preparation method is as follows:

[0106] (1) 80 parts by weight of sodium hydroxide were dissolved in 4200 parts by weight of water in a reaction kettle at 5° C. and a stirring speed of 200 rpm, and the mixture was stirred and mixed. Then, 120 parts by weight of acrylic acid was added dropwise at a uniform rate over 15 minutes to obtain a first intermediate product.

[0107] (2) Add 80 parts by weight of acrylamide to the first intermediate product obtained in step (1) at a stirring speed of 200 rpm and 5° C. to dissolve the acrylamide, and then simultaneously dropwise add 200 parts by weight of N-vinyl pyrrolidone and 40 parts by weight of an aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate for 10 minutes to obtain a second intermediate product.

[0108] (3) reducing the stirring speed to 50 rpm, adding 25 parts by weight of emulsifier OP-10 to the second intermediate product obtained in step (2), adjusting the stirring speed to 40 rpm, and simultaneously adding 200 parts by weight of acrylonitrile and 330 parts by weight of lauryl acrylate dropwise for 5 hours, stirring at 6000 rpm for another 6 minutes for emulsification to obtain a third intermediate product.

[0109] (4) The reactor was evacuated three times to expel oxygen, and the temperature was raised to 60° C. and argon was kept flowing at a flow rate of 20 mL / min throughout the process. An aqueous solution of ammonium persulfate (prepared by dissolving 5 parts by weight of ammonium persulfate in 40 parts by weight of water) was injected into the reactor and mixed with the third intermediate product obtained in step (3). After reacting for 8 hours, the temperature was lowered to room temperature (25° C.), and aqueous ammonia was added to adjust the pH to 8 to obtain the dispersion.

[0110] Example 2

[0111] This embodiment provides a dispersant, a dispersion and a preparation method thereof, and the preparation method is as follows:

[0112] (1) In a reaction kettle, 100 parts by weight of sodium hydroxide was dissolved in 4000 parts by weight of water at 5° C. and a stirring speed of 200 rpm, and the mixture was stirred and mixed. Then, 160 parts by weight of acrylic acid was added dropwise at a uniform rate over 10 minutes to obtain a first intermediate product.

[0113] (2) Add 100 parts by weight of acrylamide to the first intermediate product obtained in step (1) at 5° C. and a stirring speed of 200 rpm to dissolve the acrylamide, and then simultaneously add 150 parts by weight of N-vinyl pyrrolidone and 50 parts by weight of an aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate dropwise for 8 minutes to obtain a second intermediate product.

[0114] (3) reducing the stirring speed to 50 rpm, adding 30 parts by weight of emulsifier OP-10 to the second intermediate product obtained in step (2), adjusting the stirring speed to 40 rpm, and simultaneously adding 260 parts by weight of acrylonitrile and 350 parts by weight of tetradecyl acrylate dropwise for 6 hours, and stirring at 3000 rpm for another 10 minutes for emulsification to obtain a third intermediate product.

[0115] (4) The reactor was evacuated three times to expel oxygen, the temperature was raised to 60° C., and argon was kept flowing at a flow rate of 20 mL / min throughout the process. An aqueous solution of ammonium persulfate (prepared by dissolving 4 parts by weight of ammonium persulfate in 40 parts by weight of water) was injected into the reactor and mixed with the third intermediate product obtained in step (3). After reacting for 8 hours, the temperature was lowered to room temperature (25° C.), and aqueous ammonia was added to adjust the pH to 7.5. The dispersant was added.

[0116] Example 3

[0117] This embodiment provides a dispersant, a dispersion and a preparation method thereof, and the preparation method is as follows:

[0118] (1) In a reaction kettle, 70 parts by weight of sodium hydroxide were dissolved in 4500 parts by weight of water at 5° C. and a stirring speed of 200 rpm, and the mixture was stirred and mixed. Then, 160 parts by weight of acrylic acid was added dropwise at a uniform rate over 15 minutes to obtain a first intermediate product.

[0119] (2) Add 60 parts by weight of acrylamide to the first intermediate product obtained in step (1) at 5° C. and a stirring speed of 200 rpm to dissolve the acrylamide, and then simultaneously add 250 parts by weight of N-vinyl pyrrolidone and 30 parts by weight of an aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate dropwise for 5 minutes to obtain a second intermediate product.

[0120] (3) Add 20 parts by weight of emulsifier OP-10 to the second intermediate product obtained in step (2), adjust the stirring speed to 50 rpm, and simultaneously dropwise add 180 parts by weight of acrylonitrile and 300 parts by weight of hexadecyl acrylate for 3 hours, and stir at 1000 rpm for 10 minutes for emulsification to obtain a third intermediate product.

[0121] (4) The reactor was evacuated three times to expel oxygen, and the temperature was raised to 60° C. and argon was kept flowing at a flow rate of 20 mL / min throughout the process. An aqueous solution of ammonium persulfate (prepared by dissolving 3 parts by weight of ammonium persulfate in 40 parts by weight of water) was injected into the reactor and mixed with the third intermediate product obtained in step (3). After stirring for 10 hours, the mixture was cooled to room temperature (25° C.), and aqueous ammonia was added to adjust the pH to 9 to obtain the dispersant.

[0122] Example 4

[0123] This embodiment provides a dispersant, a dispersion liquid and a preparation method thereof. The difference between this embodiment and embodiment 1 is that N-vinyl pyrrolidone is replaced with N-vinyl-ε-caprolactam of the same mass, and other conditions are the same as those in embodiment 1.

[0124] Example 5

[0125] This embodiment provides a dispersant, a dispersion liquid and a preparation method thereof. The difference between this embodiment and embodiment 1 is that N-vinyl pyrrolidone is replaced with N-vinyl formamide of the same mass, and other conditions are the same as those in embodiment 1.

[0126] Example 6

[0127] This embodiment provides a dispersant, a dispersion liquid and a preparation method thereof. The difference between this embodiment and Example 1 is that N-vinyl pyrrolidone is replaced with phenyl vinyl sulfone of the same mass, and other conditions are the same as those in Example 1.

[0128] Example 7

[0129] This embodiment provides a dispersant, a dispersion liquid, and a preparation method thereof. The difference between this embodiment and embodiment 1 is that the steps of evacuating the reactor with argon three times to expel oxygen, heating the reactor to 60° C., and maintaining argon flow at a flow rate of 20 mL / min throughout the process are not included. Other conditions are the same as those in embodiment 1.

[0130] Example 8

[0131] This embodiment provides a dispersant, a dispersion liquid and a preparation method thereof. The difference between this embodiment and Example 1 is that the stirring speed for emulsification is adjusted to 500 rpm, and other conditions are the same as those in Example 1.

[0132] Example 9

[0133] This embodiment provides a dispersant, a dispersion liquid and a preparation method thereof. The difference between this embodiment and Example 1 is that the stirring speed for emulsification is adjusted to 7000 rpm, and other conditions are the same as those in Example 1.

[0134] Example 10

[0135] This embodiment provides a dispersant, a dispersion liquid and a preparation method thereof. The difference between this embodiment and embodiment 1 is that the weight parts of N-vinyl pyrrolidone are adjusted to 100 parts, and other conditions are the same as those in embodiment 1.

[0136] Example 11

[0137] This embodiment provides a dispersant, a dispersion liquid and a preparation method thereof. The difference between this embodiment and embodiment 1 is that the weight parts of N-vinyl pyrrolidone are adjusted to 300 parts, and other conditions are the same as those in embodiment 1.

[0138] Example 12

[0139] This embodiment provides a dispersant, a dispersion liquid, and a preparation method thereof. The difference between this embodiment and embodiment 1 is that no aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate is added, and other conditions are the same as those in embodiment 1.

[0140] Comparative Example 1

[0141] This comparative example provides a dispersant, a dispersion and a preparation method thereof. The difference between the comparative example and Example 1 is that dodecyl acrylate is replaced with butyl acrylate of the same mass, and other conditions are the same as those in Example 1.

[0142] Comparative Example 2

[0143] This comparative example provides a dispersant, a dispersion and a preparation method thereof. The difference between the comparative example and Example 1 is that dodecyl acrylate is replaced with acrylonitrile of the same mass, and other conditions are the same as those in Example 1.

[0144] Comparative Example 3

[0145] This comparative example provides a dispersant, a dispersion and a preparation method thereof. The difference between the comparative example and Example 1 is that N-vinyl pyrrolidone is replaced with acrylamide of the same mass, and other conditions are the same as those in Example 1.

[0146] Comparative Example 4

[0147] This comparative example provides a dispersion liquid, wherein the dispersant is a commercially available water-based adhesive (LA133 from Sichuan Yindile Materials Technology Group Co., Ltd.).

[0148] Application Example 1

[0149] This application example provides a diaphragm coating slurry, which is prepared by the following method: adding water to the dispersion provided in Example 1 to adjust the solid content of the dispersion to 15%, then adding 10 parts by weight of the above-mentioned dispersion with a solid content of 15% to 60 parts by weight of water, stirring at a stirring speed of 150 rpm for 15 minutes, adding 15 parts by weight of polymer microsphere powder (PVDF powder, purchased from Arkema Co., Ltd., France, D50 particle size of 200 nm) and stirring at a stirring speed of 800 rpm for 80 minutes, adding 5 parts by weight of water and 0.3 parts by weight of an aqueous wetting agent (purchased from BYK Additives (Shanghai) Co., Ltd., brand BYK-ET 3030), stirring at a stirring speed of 150 rpm for 15 minutes, and performing vacuum defoaming at 0.08 MPa for 10 minutes to obtain the diaphragm coating slurry.

[0150] Application Examples 2-12

[0151] This application example provides a diaphragm coating slurry, which differs from Application Example 1 only in that the dispersion prepared in Example 1 is replaced with the dispersions prepared in Examples 2 to 12 of the same mass, and other conditions are the same as those in Application Example 1.

[0152] Comparative Application Examples 1 to 4

[0153] This application example provides a diaphragm coating slurry, which differs from Application Example 1 only in that the dispersion prepared in Example 1 is replaced with the dispersions prepared in Comparative Examples 1 to 4 of the same mass, and other conditions are the same as those in Application Example 1.

[0154] The dispersions provided in Examples 1 to 12 and Comparative Examples 1 to 4 were subjected to the following tests.

[0155] (1) Particle size: The particle size was measured using an LS-609 laser particle size analyzer. The refractive index was set to 1.50 and the absorbance was set to 0.01 to obtain the cumulative particle size distribution. The particle size at which 50% of the particle size is accumulated from the particle side was recorded as the D50 particle size of the dispersion. Other instruments and equipment may also be used for testing, but the present invention is not limited thereto.

[0156] (2) Viscosity: The viscosity was measured using a Brookfield viscometer with an LV-01 (61) rotor and a rotation speed of 30 rpm.

[0157] (3) Infrared testing: After the dispersion is dried, Fourier transform infrared spectroscopy is performed using the ATR method.

[0158] (4) Solid content: After the dispersion is dried, the ratio of the remaining solids to the weight of the original dispersion is calculated and expressed as a percentage.

[0159] The test results are shown in Table 1.

[0160] The following tests were performed on the diaphragm coating slurries provided in Application Examples 1 to 12 and Comparative Application Examples 1 to 4.

[0161] (1) Particle size: The test was performed using an LS-609 laser particle size analyzer with the refractive index set to 1.41 and the absorptivity set to 0.1. The particle size at the cumulative 10% from the particle side was recorded as the D10 particle size, the particle size at the cumulative 50% was recorded as the D50 particle size, and the particle size at the cumulative 90% was recorded as the D90 particle size. The particle size distribution width (Span value) = (D90 particle size - D10 particle size) / D50 particle size. Other instruments and equipment may also be used for testing, but the present invention is not limited thereto.

[0162] (2) Viscosity: The viscosity was measured using a Brookfield viscometer with an LV-01 (61) rotor and a rotation speed of 30 rpm.

[0163] (3) pH: The test was performed using a Leiji PHS-25 pH meter.

[0164] (4) Stability: Pour 200 ml of the diaphragm coating slurry into a 500 ml transparent measuring cylinder and place it at room temperature (e.g., 25°C ± 2°C). Observe every 0.5 days (d) to see if interface stratification occurs, and record the time when stratification occurs.

[0165] (5) Battery diaphragm air permeability increase: The diaphragm coating slurry provided in the above application examples 1 to 11 and comparative application examples 1 to 5 was sprayed onto one side of the base membrane. The base membrane was SW509I from Shenzhen Xingyuan Material Technology Co., Ltd. with a loading of 1 g / m 2 A battery separator was produced. The battery separator and the pre-coated base film were separated by 10 cm in the TD direction and the air permeability was tested. The air permeability at five locations was measured and the average was taken. The difference between the air permeability of the battery separator and the pre-coated base film was recorded as the air permeability increment. Air permeability testing can be conducted in accordance with GB / T36363-2018.

[0166] The test results are shown in Table 2.

[0167] Table 1

[0168]

[0169]

[0170]

[0171] Table 2

[0172]

[0173] From the contents of Table 1 and Table 2, it can be seen that the dispersants in the dispersions provided by Examples 1 to 12 are all at 1725 to 1740 cm-1 2840~2960cm -1 There is an absorption peak at 2840~2960cm -1 The peak width is 90~500cm -1 The D10 particle size of the prepared diaphragm coating slurry is ≤8.5μm, 4.5μm≤D50 particle size<14.5μm, and D90 particle size is ≤70μm. There is no precipitation or stratification after being placed for ≥1d. The effect of dispersing polymer microsphere powder is good and the stability is good. The battery diaphragm prepared by using the diaphragm coating slurry has an air permeability increment of ≤17.5s.

[0174] The infrared spectrum of the dispersant prepared in Example 1 is as follows: Figure 1 As shown, 2921.8cm -1 and 2852.9cm -1 The peaks at 1732.7 cm are the characteristic peaks of CH symmetric stretching vibration and asymmetric stretching vibration of methylene (-CH2-); -1 The strong peak at is the characteristic peak of the superimposed absorption of carbonyl (C=O), which comes from the carboxylic acid group and / or carboxylate group of acrylic acid, the amide group of acrylamide, and the lactam ring of N-vinyl pyrrolidone.

[0175] Compared with Example 1, if N-vinyl pyrrolidone is replaced with phenyl vinyl sulfone of the same mass (Example 6), the wavelength of 1725-1740 cm -1 The absorbance of the absorption peak at 2915-2930 cm is 100%, and the dispersant has a peak at 2915-2930 cm -1 The absorbance of the absorption peak at is too low, the D50 particle size of the dispersion increases, the effect of dispersing the polymer microsphere powder in the diaphragm coating slurry (Application Example 6) prepared therefrom becomes worse, and the stability decreases.

[0176] Compared with Example 1, if inert gas protection is not used in the reaction of step (4) (Example 7), the D50 particle size of the obtained dispersion increases, and is set at 1725-1740 cm -1 The absorbance of the absorption peak at 2915-2930 cm is 100%, and the dispersant has a peak at 2915-2930 cm -1 The absorbance of the absorption peak at is too high, and the effect of dispersing the polymer microsphere powder in the diaphragm coating slurry (Application Example 7) prepared therefrom becomes poor and the stability decreases. This is because the α-H of the monomer (such as acrylate) used in the synthesized dispersant is captured by peroxy radicals, triggering the formation of branched structure or an increase in the carbonyl index, resulting in excessive peak intensity. When applied to the diaphragm coating slurry, the dispersant as a whole shows a better affinity with the polymer microsphere powder, while the hydrophilic chain segment accounts for a small proportion or cannot be exposed after combining with the polymer microsphere powder, resulting in a decrease in the overall stability of the diaphragm coating slurry.

[0177] Compared with Example 1, if the speed of the emulsification stirring in step (3) is too low (Example 8), sufficient emulsification cannot be achieved, and the D50 particle size of the obtained dispersion is large. When the diaphragm coating slurry (Application Example 8) is prepared, the steric hindrance of the dispersion is insufficient, and the van der Waals force between the polymer microsphere powders cannot be effectively blocked, resulting in particle agglomeration; the anchoring efficiency is low, the long-chain hydrophobic groups cannot fully cover the surface of the large-sized polymer microsphere powders, the adsorption energy decreases, and thus the dispersion effect decreases and the stability decreases.

[0178] Compared with Example 1, if the speed of the emulsification stirring in step (3) is too high (Example 9), the excessive mechanical shearing destroys the polymer particle structure in the dispersion, and the D50 particle size of the dispersion is small. When the diaphragm coating slurry is prepared (Application Example 9), due to the electrostatic shielding effect, the dispersion with too small a D50 particle size may cause counter ion aggregation due to excessive charge density, thereby destroying the Zeta potential stability. Too small a D50 particle size produces excessive solvation, and the high specific surface area of small particles (>50m 2 / g) results in an excessively thick solvation layer, diluting the concentration of the effective dispersant and reducing the adsorption density, thereby leading to a decrease in the dispersion effect and stability.

[0179] Compared with Example 1, if the content of the non-ionic hydrophilic monomer is low (Example 10), the hydrophilicity of the dispersant in the prepared dispersion decreases, and the stability of the diaphragm coating slurry (Application Example 10) prepared therefrom becomes worse, and emulsion stratification and even solid particles are more likely to precipitate.

[0180] Compared with Example 1, if the content of non-ionic hydrophilic monomer is too high (Example 11), the polymerization reaction will be accelerated, N-vinyl pyrrolidone is highly active, the reaction rate is too fast, and it is easy to induce a gel effect or a widening of the molecular weight distribution. The D50 particle size in the obtained dispersion is too large, the effect of dispersing the polymer microsphere powder is deteriorated, and the stability of the diaphragm coating slurry (Application Example 11) prepared therefrom is deteriorated.

[0181] Compared with Example 1, if the sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution is not added (Example 12), the effect of the obtained dispersion in dispersing the polymer microsphere powder becomes worse, and the stability of the diaphragm coating slurry prepared therefrom (Application Example 12) decreases.

[0182] Compared with Example 1, if dodecyl acrylate is replaced with butyl acrylate (Comparative Example 1) or acrylonitrile (Comparative Example 2) of the same mass, the effect of the obtained dispersion in dispersing the polymer microsphere powder becomes worse, and the stability of the diaphragm coating slurry (Comparative Application Example 1) or (Comparative Application Example 2) prepared therefrom becomes worse. It can be seen that the long alkyl chain of the long-chain acrylate monomer can anchor the polymer microsphere powder through hydrophobic action to form a stable core-shell microsphere structure. The short-chain acrylate monomer or acrylonitrile is not hydrophobic enough and cannot effectively combine with the polymer microsphere powder, resulting in easy stratification of the diaphragm coating slurry and low stability.

[0183] Compared with Example 1, if N-vinyl pyrrolidone is replaced with acrylamide of the same mass (Comparative Example 3), the D50 particle size of the obtained dispersion is large, the effect of dispersing the polymer microsphere powder is deteriorated, and the stability of the diaphragm coating slurry prepared therefrom is very poor. The reason is that acrylamide acts as a backbone monomer in the dispersant synthesis process, easily forming an alternating copolymer structure, destroying the amphiphilic block structure, making the synthesized dispersant have poor affinity for the polymer microsphere powder, which is not conducive to dispersion.

[0184] The infrared spectrum of the dispersant provided in Comparative Example 4 is as follows Figure 2 As shown, there is no wave number between 1725 and 1740 cm -1 The absorption peak of the membrane coating slurry prepared by using it is large in particle size and has a poor dispersion effect on the polymer microsphere powder.

[0185] The applicant states that while the above-described embodiments illustrate the process of the present invention, the present invention is not limited to the above-described process steps, nor does it imply that the present invention must rely on the above-described process steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A dispersant, characterized in that The dispersant comprises a copolymer or a derivative thereof containing a nonionic hydrophilic group and a long-chain hydrophobic group. The dispersant has an infrared absorption spectrum of 1725-1740 cm-1 obtained by Fourier transform infrared spectroscopy using attenuated total reflectance. -1 The absorption peak is at 2840~2960cm -1 There is an absorption peak at 2840~2960cm -1 The absorption peak width is 90~500cm -1 ; The raw materials for preparing the dispersant include acrylic acid monomers, long-chain acrylic ester monomers, acrylamide monomers and non-ionic hydrophilic monomers.

2. The dispersant according to claim 1, characterized in that Set 1725~1740cm -1 The absorbance of the absorption peak at 2915-2930 cm is 100%, and the dispersant has a peak at 2915-2930 cm -1 The absorbance of the absorption peak at is 60% to 90%; Preferably, the acrylic monomer comprises acrylic acid and / or methacrylic acid; Preferably, the long-chain acrylic acid ester monomer includes any one or a combination of at least two of dodecyl acrylate, dodecyl methacrylate, tetradecyl acrylate, tetradecyl methacrylate, hexadecyl acrylate or hexadecyl methacrylate; Preferably, the acrylamide monomers include acrylamide and / or methacrylamide; Preferably, the nonionic hydrophilic monomer comprises any one or a combination of at least two of the monomers having the structure shown in Formula I, Formula II or Formula III; wherein R1, R2, and R3 are each independently selected from any one of H, an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 12 carbon atoms; and R4 is selected from an alkylene group having 2 to 4 carbon atoms; Preferably, the monomer having the structure shown in Formula I comprises any one or a combination of at least two of N-vinylformamide, N-vinylacetamide or N-vinyl-N-methylacetamide; Preferably, the monomer having the structure shown in Formula II comprises N-vinyl pyrrolidone and / or N-vinyl-ε-caprolactam; Preferably, the monomer having the structure shown in Formula III comprises any one or a combination of at least two of methyl vinyl sulfone, phenyl vinyl sulfone or vinyl ethyl sulfone; Preferably, the raw materials for preparing the dispersant further include polymerizable sulfonate; Preferably, the polymerizable sulfonate comprises sodium 2-acrylamido-2-methylpropanesulfonate; Preferably, the raw materials for preparing the dispersant further include acrylonitrile monomers; Preferably, the acrylonitrile monomer includes acrylonitrile and / or methacrylonitrile; Preferably, the raw materials for preparing the dispersant include the following components in parts by weight: 80-160 parts of acrylic acid monomer, 60-100 parts of acrylamide monomer, 100-300 parts of non-ionic hydrophilic monomer, 3-30 parts of polymerizable sulfonate, 180-260 parts of acrylonitrile monomer and 300-350 parts of long-chain acrylate monomer; Preferably, the raw materials for preparing the dispersant further include 3 to 5 parts by weight of an initiator; Preferably, the initiator comprises ammonium persulfate; Preferably, the raw materials for preparing the dispersant further include 20 to 30 parts by weight of an emulsifier; Preferably, the emulsifier includes polyoxyethylene octylphenol ether-10.

3. A dispersion, characterized in that: The dispersion liquid comprises the dispersant according to claim 1 or 2.

4. The dispersion according to claim 3, characterized in that The raw materials for preparing the dispersion include the following components in parts by weight: 80-160 parts of acrylic acid monomer, 60-100 parts of acrylamide monomer, 100-300 parts of non-ionic hydrophilic monomer, 30-50 parts of polymerizable sulfonate aqueous solution, 180-260 parts of acrylonitrile monomer, 300-350 parts of long-chain acrylic acid ester monomer and 20-30 parts of emulsifier; Preferably, the raw materials for preparing the dispersion further include 4000 to 4600 parts by weight of water; Preferably, the raw materials for preparing the dispersion further include 70 to 100 parts by weight of a first neutralizer; Preferably, the raw materials for preparing the dispersion further include a second neutralizing agent; Preferably, the first neutralizing agent and the second neutralizing agent each independently comprise aqueous ammonia and / or sodium hydroxide; Preferably, the mass percentage concentration of the polymerizable sulfonate in the polymerizable sulfonate aqueous solution is 20% to 60%; Preferably, the D50 particle size of the dispersion is 10 to 100 nm; Preferably, the solid content of the dispersion is 17% to 24%; Preferably, the viscosity of the dispersion at 25° C. is 1500 to 5000 cP.s; Preferably, the pH of the dispersion is 7-9.

5. A method for preparing a dispersion according to claim 3 or 4, characterized in that: The preparation method comprises the following steps: mixing acrylic monomers, long-chain acrylic ester monomers, acrylamide monomers, nonionic hydrophilic monomers, optionally a polymerizable sulfonate aqueous solution, optionally an emulsifier, optionally an acrylonitrile monomer, optionally a first neutralizing agent, optionally an initiator, optionally water and optionally a second neutralizing agent, and reacting the mixture to obtain the dispersion.

6. The preparation method according to claim 5, characterized in that The preparation method comprises the following steps: (1) mixing a first neutralizing agent, a portion of water, and an acrylic monomer to obtain a first intermediate product; (2) mixing the first intermediate product obtained in step (1), an acrylamide monomer, a nonionic hydrophilic monomer, and a polymerizable sulfonate aqueous solution to obtain a second intermediate product; (3) mixing the second intermediate product obtained in step (2), an emulsifier, an acrylonitrile monomer, and a long-chain acrylate monomer to obtain a third intermediate product; (4) mixing the third intermediate product obtained in step (3), the initiator, and the remaining water, reacting the mixture, and adding a second neutralizer to adjust the pH to 7 to 9 to obtain the dispersion; Preferably, based on the total mass of water being 100%, the mass of the water in step (1) is 60% to 100%; Preferably, the mixing in step (1) is to mix the first neutralizing agent and a portion of water, and then dropwise add the acrylic monomer and stir and mix; Preferably, step (2) comprises adding acrylamide to the first intermediate product obtained in step (1) to dissolve the mixture, and dropwise adding a nonionic hydrophilic monomer and a polymerizable sulfonate aqueous solution to obtain a second intermediate product; Preferably, step (3) comprises mixing the second intermediate product with an emulsifier, adding acrylonitrile and a long-chain acrylic ester monomer dropwise, and then stirring at high speed for emulsification to obtain a third intermediate product; Preferably, the dropwise addition of acrylonitrile and long-chain acrylic ester monomers is carried out at a stirring speed of 30 to 50 rpm, and the dropwise addition time is 3 to 6 hours; Preferably, the speed of the high-speed stirring is 1000-6000 rpm, and the time of the high-speed stirring is 4-10 minutes; Preferably, the mixing in step (4) comprises first dissolving the initiator in water and then mixing it with the third intermediate product; Preferably, the reaction in step (4) is carried out under an inert gas atmosphere, and the inert gas is introduced at a flow rate of 15 to 25 mL / min.

7. A diaphragm coating slurry, characterized in that: The membrane coating slurry includes the following components in parts by weight: 1-20 parts of the dispersion according to claim 3 or 4 or the dispersion prepared by the preparation method according to claim 5 or 6, 1-30 parts of polymer microsphere powder, 0-1 part of wetting agent and 30-120 parts of water.

8. The diaphragm coating slurry according to claim 7, characterized in that: The polymer microsphere powder includes any one or a combination of at least two of PVDF homopolymer, PVDF-HFP copolymer, a derivative of PVDF homopolymer or a derivative of PVDF-HFP copolymer.

9. A battery separator, characterized in that: The battery separator includes a substrate and a coating layer disposed on at least one side of the substrate; The coating layer comprises the dispersant according to claim 1; Or the coating layer is made from a diaphragm coating slurry containing the dispersion according to claim 3 or 4 or the dispersion prepared by the preparation method according to claim 5 or 6; Or the coating layer is made from the diaphragm coating slurry according to claim 7 or 8.

10. A battery, characterized in that: The battery includes the battery separator of claim 9.

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