Electrode slurry additive and preparation method and application thereof

Abstract

The present invention relates to the technical field of lithium-ion batteries, and in particular to an electrode slurry additive and a preparation method and application thereof. The electrode slurry additive comprises a main dispersant, and the main dispersant is prepared by polymerization of the following components: monomer A, monomer B and monomer C; wherein the structural formula of the monomer A is: CH2=CR 1 R 2 , where R 1 is -H or a C1-C3 saturated hydrocarbon group, R 2 Selected from ‑OR 3 or ‑COOR 3 The structural formula of the monomer B is: O=P(OR 4 )(OR 5 )(OR 6 ), where R 4 , R 5 and R 6 The same or different, and each independently selected from -H or -R 7 R 8 C=CHR 9 , and R 4 , R 5 and R 6 The structural formula of the monomer C is: CH2=CR 10 R 11 The electrode slurry additive provided by the present invention can improve the stability of the slurry viscosity and improve the consistency of the electrode sheet coating surface density.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to an electrode slurry additive and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries are a clean energy source with excellent performance. In recent years, with the advancement of science and technology, people's demand for lithium-ion batteries has increased, and their performance requirements have also become higher and higher. Improving energy density is an effective way to obtain high-performance lithium-ion batteries.

[0003] At present, increasing the thickness of the coating on the positive and negative electrodes and reducing the proportion of the current collector and separator within the limited volume of the battery is one of the effective ways to increase the high energy density of the battery. However, as the thickness of the electrode electrode coating increases, the amount of current collector sizing increases. Under fixed production line equipment and processes, it will bring about thorny problems such as increased energy consumption and difficulty in drying the electrode. Such problems can be alleviated by increasing the solid content of the electrode slurry and reducing the proportion of solvent in the electrode slurry. However, after increasing the solid content of the electrode slurry, the viscosity stability of the slurry deteriorates significantly, and the consistency of the electrode coating surface density deteriorates.

[0004] The commonly used slurry dispersants are polyvinyl pyrrolidone (PVP) materials, which have relatively simple structures and functions and cannot significantly solve the problems of poor slurry viscosity stability and poor consistency of electrode coating surface density. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide an electrode slurry additive and a preparation method and application thereof. The electrode slurry additive provided by the present invention is applied to electrode slurry, which can reduce the slurry viscosity growth rate, improve the slurry viscosity stability, and at the same time improve the consistency of the electrode coating surface density, thereby improving the battery cell yield.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an electrode slurry additive, the electrode slurry additive comprising a primary dispersant, the primary dispersant being prepared by polymerization of the following components: monomer A, monomer B and monomer C;

[0008] Wherein, the structural formula of the monomer A is: CH2=CR 1 R 2 ,

[0009] Among them, R 1 is -H or a C1-C3 saturated hydrocarbon group, R 2 Select from -OR 3 or -COOR 3 , R 3Selected from C5-C36 saturated or unsaturated chain hydrocarbon groups;

[0010] The structural formula of the monomer B is: O=P(OR 4 )(OR 5 )(OR 6 );

[0011] Among them, R 4 , R 5 and R 6 are the same or different and are each independently selected from -H or -R 7 R 8 C=CHR 9 , and R 4 , R 5 and R 6 Not at the same time -H;

[0012] R 7 -(CH2CH2O) n (CH2CH2CH2O) m (CH2CH(CH3)O) k -or

[0013] -(CH2CH2O) n (CH2CH2CH2O) m (CH2CH(CH3)O) k -CH2- or

[0014] -(CH2CH2O) n (CH2CH2CH2O) m (CH2CH(CH3)O) k -OC-;

[0015] n, m and k are each independently any integer from 0 to 60, and n, m and k are not 0 at the same time;

[0016] R 8 is -H or a C1-C3 saturated hydrocarbon group;

[0017] R 9 is -H or -COOH;

[0018] The structural formula of the monomer C is: CH2=CR 10 R 11 ;

[0019] Among them, R 10 is -H or a C1-C3 saturated hydrocarbon group;

[0020] R 11 For-R 12 -(CH2CH2O) x(CH2CH2CH2O) y (CH2CH(CH3)O) z -R 13 or -R 12 -(CH2CH2O) x (CH2CH2CH2O) y (CH2CH(CH3)O) z -CH2CH2NHCO-R 13 or -R 12 -(CH2CH2O) x (CH2CH2CH2O) y (CH2CH(CH3)O) z -CH2CH2NH-R 13 ;

[0021] x, y and z are each independently any integer from 0 to 60, and x, y and z are not 0 at the same time;

[0022] R 12 is selected from -O-, -COO-, -CH2O-, -CH2CH2O- or -CH2CH2CH2O-; R 13 Selected from C5~C36 saturated or unsaturated chain hydrocarbon groups.

[0023] The electrode slurry additive provided by the present invention is applied to electrode slurry, which can reduce the slurry viscosity growth rate, improve the stability of slurry viscosity, and simultaneously improve the consistency of electrode sheet coating surface density, thereby improving the battery cell yield.

[0024] Furthermore, the R 3 -CH2(CH2CH2)5CH3, -CH2CH(CH2CH3)CH2CH2CH2CH3, -CH2(CH2CH2)8CH3, -CH2(CH2CH2) 14 CH3 or -CH2(CH2CH2)3CH2CH=CH(CH2CH2)3CH2CH3;

[0025] and / or, the R 7 -(CH2CH2O) 12 -、-(CH2CH2O) 24 CH2-、-(CH2CH2O) 18 (CH2CH2CH2O) 12 OC-、-(CH2CH2O) 12 OC-、-(CH2CH2O) 60 -or-(CH2CH2O) 24 -;

[0026] and / or, the R 11 -O(CH2CH2O) 42 CH2(CH2CH2)5CH3、-COO(CH2CH2O) 42 CH2CH2NHCOCH2(CH2CH2)8CH3、-CH2CH2O(CH2CH2O) 12 CH2CH2NHCOCH2(CH2CH2)3CH=CH(CH2CH2)3CH2CH3 or -CH2O(CH2CH2O) 22 (CH2CH(CH3)O) 10 CH2CH2NHCH2(CH2CH2)5CH3.

[0027] Furthermore, the monomer A is selected from the following compounds:

[0028] CH2=CHOCH2(CH2CH2)5CH3、

[0029] CH2=CHOCH2CH(CH2CH3)CH2CH2CH2CH3,

[0030] CH2=C(CH3)COOCH2(CH2CH2)8CH3,

[0031] CH2=C(CH3)COOCH2(CH2CH2)3CH2CH=CH(CH2CH2)3CH2CH3;

[0032] And / or, the monomer B is selected from the following compounds:

[0033] O=P(OH)(OH)(O(CH2CH2O) 12 CH=CH2),

[0034] O=P(OH)(O(CH2CH2O) 24 CH2CH=CH2)(O(CH2CH2O) 24 CH2CH=CH2)

[0035] O=P(O(CH2CH2O) 18 (CH2CH2CH2O) 12 OCCH=CH2)(O(CH2CH2O) 12 OCCH=CH2)

[0036] (O(CH2CH2O) 24 CH=CH2),

[0037] O=P(OH)(OH)(O(CH2CH2O) 60CH=CHCOOH);

[0038] And / or, the monomer C is selected from the following compounds:

[0039] CH2=CHO(CH2CH2O) 42 CH2(CH2CH2)5CH3,

[0040] CH2=CHCOO(CH2CH2O) 42 CH2CH2NHCOCH2(CH2CH2)8CH3,

[0041] CH2=CHCH2O(CH2CH2O) 22 (CH2CH(CH3)O) 10 CH2CH2NHCH2(CH2CH2)5CH3,

[0042] CH2=C(CH3)CH2CH2O(CH2CH2O) 12 CH2CH2NHCOCH2(CH2CH2)3CH=CH(CH2CH2)3CH2C

[0043] H3;

[0044] and / or, the weight average molecular weight of the primary dispersant is 3000 to 50000;

[0045] And / or, the mass ratio of the monomer A, the monomer B and the monomer C is (10-30): (35-65): (25-40);

[0046] And / or, the mass of monomer B is not less than the mass of monomer C.

[0047] Furthermore, the electrode slurry additive further comprises a pH regulator, and the amount of the pH regulator is such that the pH value of a 10 wt % aqueous solution of the electrode slurry additive is 1.0 to 9.0;

[0048] And / or, the electrode slurry additive further includes an auxiliary dispersant, and the auxiliary dispersant is a cyano-containing polymer.

[0049] Further, the pH adjuster includes at least one of alkali metal hydroxide, ammonia, and organic amine compounds;

[0050] And / or, the cyano group-containing polymer includes at least one of polyacrylonitrile, poly(acrylonitrile-butadiene), poly(acrylonitrile-vinyl pyrrolidone), hydrogenated poly(acrylonitrile-butadiene), poly(acrylonitrile-acrylic acid), poly(acrylonitrile-hydroxyethyl acrylate), and poly(acrylonitrile-acrylic acid-hydroxyethyl acrylate);

[0051] And / or, based on the total mass of the monomer A, the monomer B and the monomer C being 100%, the mass of the auxiliary dispersant accounts for 1% to 5% of the total mass of the monomer A, the monomer B and the monomer C.

[0052] In a second aspect, the present invention provides a method for preparing the electrode slurry additive as described in the first aspect, the preparation method comprising the following steps:

[0053] S1, dissolving the monomer A, the monomer B and the monomer C in a first solvent to obtain a monomer mixed solution;

[0054] S2. Continuously charging the monomer mixed solution with an inert gas, and adding an initiator and a chain transfer agent to carry out a polymerization reaction to obtain an electrode slurry additive including the main dispersant.

[0055] Further, the first solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, toluene, xylene, tetrahydrofuran, dioxane, and water;

[0056] and / or, based on the total mass of the electrode slurry additive and the first solvent being 100%, the mass of the first solvent accounts for 10% to 70%;

[0057] And / or, the inert gas is N2;

[0058] and / or, the initiator comprises at least one of azobisisobutyronitrile, azobisisoheptylnitrile, dibenzoyl peroxide, persulfate, hydrogen peroxide, peroxycarboxylate, and peroxydicarbonate;

[0059] and / or, based on the total mass of the monomer A, the monomer B and the monomer C being 100%, the added mass of the initiator accounts for 0.1 to 5% of the total mass of the monomer A, the monomer B and the monomer C;

[0060] And / or, the chain transfer agent includes at least one of mercaptoethanol, thioglycolic acid, mercaptopropionic acid, n-butyl mercaptan, n-octyl mercaptan, tert-butyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, hexadecyl mercaptan, octadecyl mercaptan, 2-ethylhexyl thioglycolate, isooctyl thioglycolate, and isooctyl mercaptopropionate;

[0061] And / or, based on the total mass of the monomer A, the monomer B and the monomer C being 100%, the added mass of the chain transfer agent accounts for 0.1% to 3% of the total mass of the monomer A, the monomer B and the monomer C;

[0062] And / or, after step S2, the preparation method further comprises the following steps:

[0063] adding the pH adjusting agent;

[0064] And / or, after step S2, the preparation method further comprises the following steps:

[0065] The auxiliary dispersant is added.

[0066] In a third aspect, the present invention provides an electrode slurry, wherein the electrode slurry comprises the electrode slurry additive as described in the first aspect or the electrode slurry additive prepared by the preparation method of the electrode slurry additive as described in the second aspect.

[0067] In a fourth aspect, the present invention provides an electrode plate, which comprises the electrode slurry additive described in the first aspect, or the electrode slurry additive prepared by the preparation method of the electrode slurry additive described in the second aspect, or the electrode slurry described in the third aspect.

[0068] In a fifth aspect, the present invention provides a lithium-ion battery, comprising the electrode slurry additive described in the first aspect, or the electrode slurry additive prepared by the preparation method of the electrode slurry additive described in the second aspect, or the electrode slurry described in the third aspect, or the electrode plate described in the fourth aspect.

[0069] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0070] The electrode slurry additive provided by the present invention is applied to electrode slurry, which can reduce the slurry viscosity growth rate, improve the stability of slurry viscosity, and simultaneously improve the consistency of electrode sheet coating surface density, thereby improving the battery cell yield. DETAILED DESCRIPTION

[0071] To make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. The process parameters of the following examples that do not specify specific conditions are usually based on conventional conditions. Unless otherwise specified, the raw materials used in the present invention can be obtained from commercially available products.

[0072] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0073] In a first aspect, the present invention provides an electrode slurry additive, the electrode slurry additive comprising a primary dispersant, the primary dispersant being prepared by polymerization of the following components: monomer A, monomer B and monomer C;

[0074] Wherein, the structural formula of the monomer A is: CH2=CR 1 R 2 ,

[0075] Among them, R 1 is -H or a C1-C3 saturated hydrocarbon group, R 2 Select from -OR 3 or -COOR 3 , R 3 Selected from C5-C36 saturated or unsaturated chain hydrocarbon groups;

[0076] The structural formula of the monomer B is: O=P(OR 4 )(OR 5 )(OR 6 );

[0077] Among them, R 4 , R 5 and R 6 are the same or different and are each independently selected from -H or -R 7 R 8 C=CHR 9 , and R 4 , R 5 and R 6 Not at the same time -H;

[0078] R 7 -(CH2CH2O) n (CH2CH2CH2O) m (CH2CH(CH3)O) k -or

[0079] -(CH2CH2O) n (CH2CH2CH2O) m (CH2CH(CH3)O) k -CH2- or

[0080] -(CH2CH2O) n (CH2CH2CH2O) m (CH2CH(CH3)O) k -OC-;

[0081] n, m and k are each independently any integer from 0 to 60 (for example, 0, 5, 10, 15, 20, 25, 30, 40, 50 or 60), preferably 5 to 25, and n, m and k are not 0 at the same time;

[0082] R 8 is -H or a C1-C3 saturated hydrocarbon group;

[0083] R 9 is -H or -COOH;

[0084] The structural formula of the monomer C is: CH2=CR 10 R 11 ;

[0085] Among them, R 10 is -H or a C1-C3 saturated hydrocarbon group;

[0086] R 11 For-R 12 -(CH2CH2O) x (CH2CH2CH2O) y (CH2CH(CH3)O) z -R 13 or -R 12 -(CH2CH2O) x (CH2CH2CH2O) y (CH2CH(CH3)O) z -CH2CH2NHCO-R 13 or -R 12 -(CH2CH2O) x (CH2CH2CH2O) y (CH2CH(CH3)O) z -CH2CH2NH-R 13 ;

[0087] x, y and z are each independently any integer from 0 to 60 (for example, 0, 5, 10, 15, 20, 25, 30, 40, 50 or 60), preferably 10 to 45, and x, y and z are not 0 at the same time;

[0088] R 12 is selected from -O-, -COO-, -CH2O-, -CH2CH2O- or -CH2CH2CH2O-; R 13 Selected from C5~C36 saturated or unsaturated chain hydrocarbon groups.

[0089] In view of the poor viscosity stability of the slurry when a high-solid content electrode slurry is used in the prior art, the slurry is prone to blockage in the flow channel, the density consistency of the electrode coating surface becomes poor, and the air mixed into the slurry during the stirring process becomes gradually difficult to overflow, resulting in a series of problems such as pits and cracks on the surface of the electrode after drying. The purpose of the present invention is to provide an electrode slurry additive, which reduces the slurry viscosity growth rate and improves the slurry stability by adding an electrode slurry additive, while reducing slurry foaming and improving the electrode coating quality, thereby improving the performance of the battery cell.

[0090] The electrode slurry additive provided by the present invention is applied to electrode slurry, which can reduce the slurry viscosity growth rate, effectively improve the fluidity of the electrode slurry, stabilize the slurry viscosity at high solid content, improve the stability of the slurry viscosity, and simultaneously improve the consistency of the electrode sheet coating surface density, thereby improving the battery cell yield.

[0091] Specifically, the monomer A contains a low-polarity C5-C36 saturated or unsaturated chain hydrocarbon group, which can form a good adsorption effect on the surface of the inorganic main material particles coated with a carbon layer, reducing the possibility of the slurry additive falling off and becoming ineffective; at the same time, the unabsorbed hydrocarbon group part can form an effective spatial volume steric hindrance to prevent the slurry particles from re-aggregating, thereby improving the slurry stability.

[0092] It should be noted that the "C5-C36 saturated or unsaturated chain hydrocarbon group" in the present invention refers to a saturated or unsaturated chain hydrocarbon group having 5 to 36 carbon atoms.

[0093] The monomer B has high surface activity and can significantly reduce surface tension, greatly enhancing the additive's ability to wet the particle surface, making the contact with the particle surface more complete and uniform; at the same time, it increases the anchoring speed of the additive, allowing the additive to function efficiently. On the other hand, the monomer B can give the electrode slurry additive a certain degree of crosslinking without producing a gel phenomenon that makes processing difficult. This forms a micro-crosslinked network structure, which is conducive to further stabilizing the slurry state and improving the consistency of electrode processing.

[0094] The monomer C has a better solvation effect, can be stretched in a polar solvent system (such as water, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, 1,4-dioxane, etc.), covered on the particle surface, improve particle dispersibility and prevent particle flocculation. Therefore, if the values ​​of x, y and z in monomer C are too small, the molecular chain length is insufficient, and sufficient coating and steric hindrance cannot be generated, and the particles are more likely to produce secondary agglomeration, thereby reducing the viscosity stabilization effect of the additive; if the values ​​of x, y and z in monomer C are too large, the molecular chain length is too long, which not only causes the additive to be desorbed from the particle surface, but also causes the molecular chain to fold on the particle surface, thereby compressing the space or causing entanglement with adjacent molecules, and finally causing reaggregation or flocculation of the particles.

[0095] In the above electrode slurry additive, as an optional embodiment, the R 3 -CH2(CH2CH2)5CH3, -CH2CH(CH2CH3)CH2CH2CH2CH3, -CH2(CH2CH2)8CH3, -CH2(CH2CH2)3CH2CH=CH(CH2CH2)3CH2CH3 or -CH2(CH2CH2) 14 CH3.

[0096] In the above electrode slurry additive, as an optional embodiment, the R 7 -(CH2CH2O) 12 -、-(CH2CH2O) 24 CH2-、-(CH2CH2O) 18 (CH2CH2CH2O) 12 OC-、-(CH2CH2O) 12 OC-、-(CH2CH2O) 60 -or-(CH2CH2O) 24 -.

[0097] In the above electrode slurry additive, as an optional embodiment, the R 11 -O(CH2CH2O) 42 CH2(CH2CH2)5CH3、-COO(CH2CH2O) 42 CH2CH2NHCOCH2(CH2CH2)8CH3、-CH2CH2O(CH2CH2O) 12 CH2CH2NHCOCH2(CH2CH2)3CH=CH(CH2CH2)3CH2CH3 or -CH2O(CH2CH2O) 22 (CH2CH(CH3)O) 10CH2CH2NHCH2(CH2CH2)5CH3.

[0098] In the above electrode slurry additive, as an optional embodiment, the monomer A is selected from the following compounds:

[0099] CH2=CHOCH2(CH2CH2)5CH3、

[0100] CH2=CHOCH2CH(CH2CH3)CH2CH2CH2CH3,

[0101] CH2=C(CH3)COOCH2(CH2CH2)8CH3 or

[0102] CH2=C(CH3)COOCH2(CH2CH2)3CH2CH=CH(CH2CH2)3CH2CH3.

[0103] In the above electrode slurry additive, as an optional embodiment, the monomer B is selected from the following compounds:

[0104] O=P(OH)(OH)(O(CH2CH2O) 12 CH=CH2),

[0105] O=P(OH)(O(CH2CH2O) 24 CH2CH=CH2)(O(CH2CH2O) 24 CH2CH=CH2)

[0106] O=P(O(CH2CH2O) 18 (CH2CH2CH2O) 12 OCCH=CH2)(O(CH2CH2O) 12 OCCH=CH2)(

[0107] O(CH2CH2O) 24 CH=CH2) or

[0108] O=P(OH)(OH)(O(CH2CH2O) 60 CH=CHCOOH).

[0109] In the above electrode slurry additive, as an optional embodiment, the monomer C is selected from the following compounds:

[0110] CH2=CHO(CH2CH2O) 42 CH2(CH2CH2)5CH3,

[0111] CH2=CHCOO(CH2CH2O) 42CH2CH2NHCOCH2(CH2CH2)8CH3,

[0112] CH2=CHCH2O(CH2CH2O) 22 (CH2CH(CH3)O) 10 CH2CH2NHCH2(CH2CH2)5CH3 or

[0113] CH2=C(CH3)CH2CH2O(CH2CH2O) 12 CH2CH2NHCOCH2(CH2CH2)3CH=CH(CH2CH2)3

[0114] CH2CH3.

[0115] In the above electrode slurry additive, as an optional embodiment, the weight average molecular weight of the main dispersant is 3000-50000, for example, it can be 3000, 5000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000 or 50000.

[0116] In the above-mentioned electrode slurry additive, as an optional embodiment, the mass ratio of the monomer A, the monomer B and the monomer C is (10-30): (35-65): (25-40). Preferably, the sum of the mass ratios of the three is equal to 100, for example, it can be 20:55:25, 10:65:25, 30:35:35, 20:40:40.

[0117] In the above electrode slurry additive, as an optional implementation, the mass of the monomer B is not less than the mass of the monomer C. When the mass of the monomer B is less than the mass of the monomer C, the effect of the additive will be reduced and the viscosity of the slurry will increase.

[0118] In the above-mentioned electrode slurry additive, as an optional embodiment, the electrode slurry additive also includes a pH adjuster, and the amount of the pH adjuster is such that the pH value of a 10wt% aqueous solution of the electrode slurry additive is 1.0 to 9.0, for example, it can be 1.0, 3.0, 5.0, 7.0 or 9.0, preferably 5 to 9. The electrode slurry additive with a suitable pH value can enable the additive to form a charged ring layer of a certain thickness on the surface of the inorganic main material particles of the slurry, so that the inorganic main material particles produce a repulsive effect, prevent material coagulation, and improve the dispersion stability of the slurry. To obtain a suitable pH value, it can be adjusted by adding a pH adjuster.

[0119] In the above electrode slurry additive, as an optional implementation, the pH adjuster includes at least one of alkali metal hydroxide, ammonia, and organic amine compounds.

[0120] In the above electrode slurry additive, as an optional embodiment, the alkali metal hydroxide is selected from at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide.

[0121] In the above-mentioned electrode slurry additive, as an optional embodiment, the organic amine compound is selected from at least one of diethylamine, triethylamine, triethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, n-butanolamine, isobutanolamine, tetramethylammonium hydroxide, and tetramethylguanidine.

[0122] In the above electrode slurry additive, as an optional implementation, the electrode slurry additive also includes an auxiliary dispersant, and the auxiliary dispersant is a cyano-containing polymer.

[0123] In the above-mentioned electrode slurry additive, as an optional embodiment, the cyanide-containing polymer includes at least one of polyacrylonitrile, poly(acrylonitrile-butadiene), poly(acrylonitrile-vinyl pyrrolidone), hydrogenated poly(acrylonitrile-butadiene), poly(acrylonitrile-acrylic acid), poly(acrylonitrile-hydroxyethyl acrylate), and poly(acrylonitrile-acrylic acid-hydroxyethyl acrylate).

[0124] In the above electrode slurry additive, as an optional implementation, the mass of the auxiliary dispersant accounts for 1% to 5% of the total mass of the monomer A, monomer B and monomer C, calculated based on the total mass of the monomer A, monomer B and monomer C as 100%. If the mass proportion of the auxiliary dispersant is too much or too little, the stability of the slurry viscosity will be reduced.

[0125] In a second aspect, the present invention provides a method for preparing the electrode slurry additive as described in the first aspect, the preparation method comprising the following steps:

[0126] S1, dissolving the monomer A, the monomer B and the monomer C in a first solvent to obtain a monomer mixed solution;

[0127] S2. Continuously charging the monomer mixed solution with an inert gas, and adding an initiator and a chain transfer agent to carry out a polymerization reaction to obtain an electrode slurry additive including the main dispersant.

[0128] The present invention provides a method for preparing the electrode slurry additive, which is simple and easy to implement and suitable for large-scale production. The electrode slurry additive of the present invention can exist or be used in the form of a solid additive without the first solvent or in the form of a mixed solution containing the first solvent and the electrode slurry additive. The specific form of existence or use is determined according to actual needs.

[0129] In the preparation method of the electrode slurry additive, the type of the polymerization reaction is a free radical polymerization reaction, and the reaction conditions are not limited as long as the monomer A, the monomer B and the monomer C can be polymerized to form a polymer with a certain chain length.

[0130] In the above-mentioned preparation method of the electrode slurry additive, as an optional embodiment, the first solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, toluene, xylene, tetrahydrofuran, dioxane, and water.

[0131] In the preparation method of the above-mentioned electrode slurry additive, as an optional embodiment, taking the total mass of the electrode slurry additive and the first solvent as 100%, the mass of the first solvent accounts for 10% to 70%; (for example, it can be 10%, 30%, 50% or 70%). It should be noted that the total mass of the electrode slurry additive and the first solvent is the total mass of all substances in the electrode slurry additive and the first solvent. For example, when the electrode slurry additive includes monomer A, monomer B, monomer C and an auxiliary dispersant, the total mass of the electrode slurry additive and the first solvent is the total mass of monomer A, monomer B, monomer C, the auxiliary dispersant and the first solvent.

[0132] In the above-mentioned method for preparing the electrode slurry additive, as an optional implementation, the inert gas is N2.

[0133] In the preparation method of the above-mentioned electrode slurry additive, the type of the initiator is not limited, and all compounds that can be decomposed into free radicals by heat can be used as the initiator in the present invention. As an optional method, the initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dibenzoyl peroxide, persulfate, hydrogen peroxide, peroxycarboxylic acid ester, and peroxydicarbonate.

[0134] In the above-mentioned preparation method of the electrode slurry additive, the amount of the initiator added varies according to the total mass of all monomers (monomer A, monomer B and monomer C) in the reaction system. As an optional method, taking the total mass of the monomer A, monomer B and monomer C as 100%, the added mass of the initiator accounts for 0.1 to 5% of the total mass of the monomer A, monomer B and monomer C, for example, it can be 0.1%, 0.5%, 1%, 3% or 5%.

[0135] In the preparation method of the above-mentioned electrode slurry additive, in order to control the stability of the reaction, a chain transfer agent can be additionally added at the same time as the initiator is added. The type of the chain transfer agent is not limited. All substances that can cause free radical transfer of chain growth free radicals can be used as the chain transfer agent in the present invention. As an optional method, the chain transfer agent can include at least one of mercaptoethanol, thioglycolic acid, mercaptopropionic acid, n-butyl mercaptan, n-octyl mercaptan, tert-butyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, hexadecyl mercaptan, octadecyl mercaptan, 2-ethylhexyl thioglycolate, isooctyl thioglycolate, and isooctyl mercaptopropionate.

[0136] In the preparation method of the above-mentioned electrode slurry additive, the added amount of the chain transfer agent varies according to the total mass of all monomers (monomer A, monomer B and monomer C) in the reaction system. As an optional method, taking the total mass of the monomer A, monomer B and monomer C as 100%, the added mass of the chain transfer agent accounts for 0.1% to 3% of the total mass of the monomer A, monomer B and monomer C, for example, it can be 0.1%, 0.5%, 1% or 3%.

[0137] In the preparation method of the above-mentioned electrode slurry additive, the conditions of the polymerization reaction include the reaction time, but in order to improve the reaction efficiency and reduce energy consumption, a suitable reaction time can be selected. As an optional method, the reaction time is 2h to 24h, for example, it can be 2h, 4h, 6h, 8h, 10h, 15h, 20h or 24h.

[0138] In the preparation method of the above-mentioned electrode slurry additive, the conditions of the polymerization reaction also include the reaction temperature. However, in order to improve the reaction efficiency and reduce energy consumption, a suitable reaction temperature can be selected. As an optional method, the reaction temperature is 60 to 100°C, for example, 60°C, 70°C, 80°C, 90°C or 100°C.

[0139] In the preparation method of the electrode slurry additive, the polymerization reaction conditions also include reaction pressure. However, in order to improve reaction efficiency and reduce energy consumption, a suitable reaction pressure can be selected. As an optional method, the reaction pressure is normal pressure.

[0140] In the above-mentioned preparation method of the electrode slurry additive, as an optional implementation, after step S2, the preparation method further includes the following steps:

[0141] The pH adjuster is added.

[0142] In the above-mentioned preparation method of the electrode slurry additive, as an optional implementation, after step S2, the preparation method further includes the following steps:

[0143] The auxiliary dispersant is added.

[0144] In a third aspect, the present invention provides an electrode slurry, wherein the electrode slurry comprises the electrode slurry additive as described in the first aspect or the electrode slurry additive prepared by the preparation method of the electrode slurry additive as described in the second aspect.

[0145] The present invention provides an electrode slurry, comprising the electrode slurry additive. In view of the advantages of the electrode slurry additive, the electrode slurry containing the electrode slurry additive has excellent viscosity stability.

[0146] As an optional manner, the electrode slurry may further include an electrode active material, a conductive agent, a binder, and a second solvent.

[0147] In the electrode slurry, based on the total mass of the electrode active material, the conductive agent and the binder being 100%, the mass of the electrode slurry additive accounts for 0.05% to 1.0% of the total mass of the electrode active material, the conductive agent and the binder.

[0148] In the above electrode slurry, the electrode slurry is a positive electrode slurry, and the electrode active material is a positive electrode active material.

[0149] The electrode slurry and / or electrode plate of the present invention have no particular restrictions on the particle size and type of the electrode active material, the conductive agent, and the binder. Regarding the electrode active material used, it may include but is not limited to any one or more combinations of lithium iron phosphorus oxide, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron oxide, lithium nickel manganese oxide, lithium cobalt nickel oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their composites. Regarding the conductive agent used, it may include but is not limited to any one or more combinations of conductive carbon black, conductive graphite, modified conductive graphite, metal particles, Ketjen black, acetylene black, carbon nanotubes, carbon fibers, graphene, conductive polymers, and their composites. Regarding the binder used, it may include but is not limited to polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride copolymer, polytetrafluoroethylene copolymer, polyimide, polyetherimide, polyamideimide, polyesterimide, polycarbonateimide, polyureaimide, styrene-butadiene rubber, polyacrylonitrile, polyacrylic acid, polyacrylate, polyacrylic acid-polyacrylonitrile copolymer, polyacrylate-polyacrylonitrile copolymer and any one or more combinations of their composites.

[0150] In a fourth aspect, the present invention provides an electrode plate, which comprises the electrode slurry additive described in the first aspect, or the electrode slurry additive prepared by the preparation method of the electrode slurry additive described in the second aspect, or the electrode slurry described in the third aspect.

[0151] The present invention provides an electrode plate, comprising the electrode slurry additive. In view of the advantages of the electrode slurry additive, the consistency of the surface density of the electrode plate can be significantly improved.

[0152] In a fifth aspect, the present invention provides a lithium-ion battery, comprising the electrode slurry additive described in the first aspect, or the electrode slurry additive prepared by the preparation method of the electrode slurry additive described in the second aspect, or the electrode slurry described in the third aspect, or the electrode plate described in the fourth aspect.

[0153] The present invention will be further described in detail below with reference to specific embodiments and comparative examples.

[0154] The structures of the monomers used in the following examples and comparative examples are as follows:

[0155] A1: CH2=CHOCH2(CH2CH2)5CH3

[0156] A2: CH2=CHOCH2CH(CH2CH3)CH2CH2CH2CH3

[0157] A3: CH2=C(CH3)COOCH2(CH2CH2)8CH3

[0158] A4: CH2=C(CH3)COOCH2(CH2CH2)3CH2CH=CH(CH2CH2)3CH2CH3

[0159] B1: O=P(OH)(OH)(O(CH2CH2O) 12 CH=CH2)

[0160] B2: O=P(OH)(O(CH2CH2O) 24 CH2CH=CH2)(O(CH2CH2O) 24 CH2CH=CH2)

[0161] B3: O=P(O(CH2CH2O) 18 (CH2CH2CH2O) 12 OCCH=CH2)(O(CH2CH2O) 12 O CCH

[0162] =CH2)(O(CH2CH2O) 24 CH=CH2)

[0163] B4: O=P(OH)(OH)(O(CH2CH2O) 60 CH=CHCOOH)

[0164] C1:CH2=CHO(CH2CH2O) 42 CH2(CH2CH2)5CH3

[0165] C2:CH2=CHCOO(CH2CH2O) 42 CH2CH2NHCOCH2(CH2CH2)8CH3

[0166] C3:CH2=CHCH2O(CH2CH2O) 22 (CH2CH(CH3)O) 10 CH2CH2NHCH2(CH2C H2)5CH3.

[0167] C4:CH2=C(CH3)CH2CH2O(CH2CH2O) 12 CH2CH2NHCOCH2(CH2CH2)3CH=CH(CH2C

[0168] H2)3CH2CH3

[0169] Example 1

[0170] The electrode slurry additive provided in this embodiment includes a main dispersant and a pH adjuster, lithium hydroxide. The main dispersant is prepared by polymerization of the following components: monomer A1, monomer B1 and monomer C1.

[0171] The preparation method of the electrode slurry additive comprises the following steps:

[0172] S1, dissolving 20 g of monomer A1, 55 g of monomer B1 and 25 g of monomer C1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0173] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5 g of initiator azobisisobutyronitrile and 0.5 g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6 hours to obtain a main dispersant, then add lithium hydroxide, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of lithium hydroxide added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 6.1.

[0174] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 6.1.

[0175] The weight average molecular weight of the main dispersant was 11,000 as determined by gel permeation chromatography (GPC).

[0176] Example 2

[0177] The electrode slurry additive provided in this embodiment includes a main dispersant, and the main dispersant is prepared by polymerization of the following components: monomer A1, monomer B2 and monomer C2.

[0178] The preparation method of the electrode slurry additive comprises the following steps:

[0179] S1, dissolving 10 g of monomer A1, 65 g of monomer B2 and 25 g of monomer C2 in 160 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0180] S2. Inert gas N2 is continuously charged into the monomer mixed solution, 1.0 g of initiator azobisisobutyronitrile and 0.3 g of chain transfer agent mercaptoethanol are added thereto, the mixture is heated to 60° C. for reaction for 8 h, and the solvent is evaporated to obtain an electrode slurry additive (main dispersant).

[0181] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 1.6.

[0182] The weight average molecular weight of the main dispersant was found to be 24,000 by GPC test.

[0183] Example 3

[0184] The electrode slurry additive provided in this embodiment includes a main dispersant and a pH adjuster, triethanolamine. The main dispersant is prepared by polymerization of the following components: monomer A2, monomer B2, and monomer C3.

[0185] The preparation method of the electrode slurry additive comprises the following steps:

[0186] S1, dissolving 30 g of monomer A2, 35 g of monomer B2 and 35 g of monomer C3 in 100 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0187] S2. Continuously fill the monomer mixed solution with inert gas N2, add 1.0g of initiator azobisisobutyronitrile and 0.5g of chain transfer agent mercaptoethanol, heat to 70°C and react for 8h to obtain a main dispersant, then add triethanolamine, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of triethanolamine added is such that the pH value of a 10wt% aqueous solution of the electrode slurry additive is 5.4.

[0188] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 5.4.

[0189] The weight average molecular weight of the main dispersant was 17,000 as determined by GPC.

[0190] Example 4

[0191] The electrode slurry additive provided in this embodiment includes a main dispersant and a pH adjuster N,N-diethylethanolamine, wherein the main dispersant is prepared by polymerization of the following components: monomer A3, monomer B3 and monomer C3.

[0192] The preparation method of the electrode slurry additive comprises the following steps:

[0193] S1, dissolving 20 g of monomer A2, 40 g of monomer B2 and 40 g of monomer C3 in 200 g of a first solvent, N-methylpyrrolidone, to obtain a monomer mixed solution;

[0194] S2. Continuously fill the monomer mixed solution with inert gas N2, add 1.4 g of initiator azobisisobutyronitrile and 0.6 g of chain transfer agent mercaptoethanol, heat to 80°C for reaction for 4 hours to obtain a main dispersant, then add N,N-diethylethanolamine, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of N,N-diethylethanolamine added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 8.8.

[0195] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 8.8.

[0196] The weight average molecular weight of the main dispersant was 48,000 as determined by GPC.

[0197] Example 5

[0198] The electrode slurry additive provided in this embodiment includes a main dispersant, a pH regulator lithium hydroxide and an auxiliary dispersant polyacrylonitrile, the weight average molecular weight of the polyacrylonitrile is 30,000, and the main dispersant is prepared by polymerization of the following components: monomer A1, monomer B1 and monomer C1.

[0199] The preparation method of the electrode slurry additive comprises the following steps:

[0200] S1, dissolving 20 g of monomer A1, 55 g of monomer B1 and 25 g of monomer C1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0201] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5g of initiator azobisisobutyronitrile and 0.5g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6h to obtain the main dispersant, then add 2.0g of polyacrylonitrile and lithium hydroxide, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of lithium hydroxide added is such that the pH value of a 10wt% aqueous solution of the electrode slurry additive is 6.1.

[0202] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 6.1.

[0203] The weight average molecular weight of the main dispersant was 11,000 as determined by GPC.

[0204] Example 6

[0205] The electrode slurry additive provided in this embodiment includes a main dispersant, a pH adjuster lithium hydroxide and an auxiliary dispersant poly(acrylonitrile-vinyl pyrrolidone), the weight average molecular weight of the poly(acrylonitrile-vinyl pyrrolidone) is 25,000, and the main dispersant is prepared by polymerization reaction of the following components: monomer A1, monomer B1 and monomer C1.

[0206] The preparation method of the electrode slurry additive comprises the following steps:

[0207] S1, dissolving 20 g of monomer A1, 55 g of monomer B1 and 25 g of monomer C1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0208] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5g of initiator azobisisobutyronitrile and 0.5g of chain transfer agent mercaptoethanol, heat to 75°C for reaction for 6h to obtain the main dispersant, then add 5.0g of poly(acrylonitrile-vinyl pyrrolidone) and lithium hydroxide, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of lithium hydroxide added is such that the pH value of a 10wt% aqueous solution of the electrode slurry additive is 6.1.

[0209] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 6.1.

[0210] The weight average molecular weight of the main dispersant was 11,000 as determined by GPC.

[0211] Example 7

[0212] The electrode slurry additive provided in this embodiment includes a main dispersant, a pH adjuster lithium hydroxide and an auxiliary dispersant poly(acrylonitrile-acrylic acid-hydroxyethyl acrylate), the weight average molecular weight of the poly(acrylonitrile-acrylic acid-hydroxyethyl acrylate) is 26000, and the main dispersant is prepared by polymerization reaction of the following components: monomer A1, monomer B1 and monomer C1.

[0213] The preparation method of the electrode slurry additive comprises the following steps:

[0214] S1, dissolving 20 g of monomer A1, 55 g of monomer B1 and 25 g of monomer C1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0215] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5g of initiator azobisisobutyronitrile and 0.5g of chain transfer agent mercaptoethanol, heat to 75°C for reaction for 6h to obtain the main dispersant, then add 1.0g of poly(acrylonitrile-acrylic acid-hydroxyethyl acrylate) and lithium hydroxide, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of lithium hydroxide added is such that the pH value of a 10wt% aqueous solution of the electrode slurry additive is 6.1.

[0216] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 6.1.

[0217] The weight average molecular weight of the main dispersant was 11,000 as determined by GPC.

[0218] Example 8

[0219] The preparation method of the electrode slurry additive provided in this embodiment is basically the same as that in Example 1, except that 0.5 g of the initiator azobisisobutyronitrile is replaced by 3 g of the initiator azobisisobutyronitrile.

[0220] The weight average molecular weight of the main dispersant was 9600 as measured by GPC.

[0221] Example 9

[0222] The preparation method of the electrode slurry additive provided in this embodiment is the same as that in Embodiment 1, except that 0.5 g of the chain transfer agent mercaptoethanol is replaced with 2 g of the chain transfer agent mercaptoethanol.

[0223] The weight average molecular weight of the main dispersant was 6700 as measured by GPC.

[0224] Example 10

[0225] The electrode slurry additive provided in this embodiment includes a main dispersant and a pH regulator, lithium hydroxide. The main dispersant is prepared by polymerization of the following components: monomer A1, monomer B2, and monomer C2.

[0226] The preparation method of the electrode slurry additive is basically the same as that of Example 2, except that lithium hydroxide is added, and specifically comprises the following steps:

[0227] S1, dissolving 10 g of monomer A1, 65 g of monomer B2 and 25 g of monomer C2 in 160 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0228] S2. Continuously fill the monomer mixed solution with inert gas N2, add 1.0g of initiator azobisisobutyronitrile and 0.3g of chain transfer agent mercaptoethanol, heat to 60°C and react for 8h to obtain the main dispersant, then add lithium hydroxide, mix, evaporate the solvent to obtain the electrode slurry additive, the amount of lithium hydroxide added is such that the pH value of the 10wt% aqueous solution of the electrode slurry additive is 5.9.

[0229] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 5.9.

[0230] The weight average molecular weight of the main dispersant was found to be 24,000 by GPC test.

[0231] Embodiment 11

[0232] The electrode slurry additive provided in this embodiment includes a main dispersant and a pH adjuster, isobutanolamine. The main dispersant is prepared by polymerization of the following components: monomer A4, monomer B1, and monomer C1.

[0233] The preparation method of the electrode slurry additive comprises the following steps:

[0234] S1, dissolving 20 g of monomer A4, 55 g of monomer B1 and 25 g of monomer C1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0235] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5 g of initiator azobisisobutyronitrile and 0.5 g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6 hours to obtain a main dispersant, then add isobutanolamine, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of isobutanolamine added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 7.0.

[0236] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 7.0.

[0237] The weight average molecular weight of the main dispersant was measured by gel permeation chromatography (GPC) and was found to be 22,000.

[0238] Example 12

[0239] The electrode slurry additive provided in this embodiment includes a main dispersant and a pH adjuster, isobutanolamine. The main dispersant is prepared by polymerization of the following components: monomer A1, monomer B4 and monomer C1.

[0240] The preparation method of the electrode slurry additive comprises the following steps:

[0241] S1, dissolving 20 g of monomer A1, 55 g of monomer B4 and 25 g of monomer C1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0242] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5 g of initiator azobisisobutyronitrile and 0.5 g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6 hours to obtain a main dispersant, then add isobutanolamine, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of isobutanolamine added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 7.5.

[0243] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 7.5.

[0244] The weight average molecular weight of the main dispersant was 18,000 as determined by gel permeation chromatography (GPC).

[0245] Example 13

[0246] The electrode slurry additive provided in this embodiment includes a main dispersant and a pH adjuster, isobutanolamine. The main dispersant is prepared by polymerization of the following components: monomer A1, monomer B1, and monomer C4.

[0247] The preparation method of the electrode slurry additive comprises the following steps:

[0248] S1, dissolving 20 g of monomer A1, 55 g of monomer B1 and 25 g of monomer C4 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0249] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5 g of initiator azobisisobutyronitrile and 0.5 g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6 hours to obtain a main dispersant, then add isobutanolamine, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of isobutanolamine added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 8.7.

[0250] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 8.7.

[0251] The weight average molecular weight of the main dispersant was 47,000 as measured by gel permeation chromatography (GPC).

[0252] Comparative Example 1

[0253] This comparative example provides an electrode slurry additive. Except for replacing the type of monomer A1 from CH2=CHOCH2(CH2CH2)5CH3 to CH2=CHOCH2CH3, the types and amounts of other raw materials are the same as those in Example 1.

[0254] The preparation method of the electrode slurry additive comprises the following steps:

[0255] S1, dissolving 20 g of monomer CH2=CHOCH2CH3, 55 g of monomer B1 and 25 g of monomer C1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0256] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5 g of initiator azobisisobutyronitrile and 0.5 g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6 hours to obtain a main dispersant, then add lithium hydroxide, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of lithium hydroxide added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 6.1.

[0257] The pH value of the electrode slurry additive prepared in this comparative example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 6.1.

[0258] The weight average molecular weight of the main dispersant was 9200 as measured by GPC.

[0259] Comparative Example 2

[0260] The electrode slurry additive provided in this comparative example includes a main dispersant and a pH regulator, lithium hydroxide. The main dispersant is prepared by polymerization of the following components: monomer A1 and monomer C1.

[0261] The preparation method of the electrode slurry additive comprises the following steps:

[0262] S1, dissolving 44 g of monomer A1 and 56 g of monomer C1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0263] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5 g of initiator azobisisobutyronitrile and 0.5 g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6 hours to obtain a main dispersant, then add lithium hydroxide, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of lithium hydroxide added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 6.1.

[0264] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 6.1.

[0265] The weight average molecular weight of the main dispersant was 10,000 as determined by GPC.

[0266] Comparative Example 3

[0267] The electrode slurry additive provided in this comparative example includes a main dispersant and a pH regulator, lithium hydroxide. The main dispersant is prepared by polymerization of the following components: monomer A1 and monomer B1.

[0268] The preparation method of the electrode slurry additive comprises the following steps:

[0269] S1, dissolving 27 g of monomer A1 and 73 g of monomer B1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0270] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5 g of initiator azobisisobutyronitrile and 0.5 g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6 hours to obtain a main dispersant, then add lithium hydroxide, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of lithium hydroxide added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 6.1.

[0271] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 6.1.

[0272] The weight average molecular weight of the main dispersant was 8800 as measured by GPC.

[0273] Comparative Example 4

[0274] This comparative example provides an electrode slurry additive, except that the type of monomer C1 is changed from CH2=CHO(CH2CH2O) 42 CH2(CH2CH2)5CH3 is replaced by CH2=CHO(CH2CH2O) 42 CH2CH3, and the types and amounts of other raw materials are the same as those in Example 1.

[0275] The preparation method of the electrode slurry additive comprises the following steps:

[0276] S1, 20g monomer A1, 55g monomer B1 and 25g monomer CH2=CHO(CH2CH2O) 42 CH2CH3 is dissolved in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0277] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5 g of initiator azobisisobutyronitrile and 0.5 g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6 hours to obtain a main dispersant, then add lithium hydroxide, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of lithium hydroxide added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 6.1.

[0278] The pH value of the electrode slurry additive prepared in this comparative example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 6.1.

[0279] The weight average molecular weight of the main dispersant was 12,000 as determined by GPC.

[0280] Comparative Example 5

[0281] The electrode slurry additive provided in this comparative example is polyvinyl pyrrolidone (PVP K30) material.

[0282] Comparative Example 6

[0283] The electrode slurry additive provided in this comparative example includes a main dispersant and a pH regulator, lithium hydroxide. The main dispersant is prepared by polymerization of the following components: monomer A1, monomer B1 and monomer C1.

[0284] The preparation method of the electrode slurry additive is basically the same as that of Example 1, except that the mass of the monomer B1 is less than the mass of the monomer C1, and specifically comprises the following steps:

[0285] S1, dissolving 20 g of monomer A1, 25 g of monomer B1 and 55 g of monomer C1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0286] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5 g of initiator azobisisobutyronitrile and 0.5 g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6 hours to obtain a main dispersant, then add lithium hydroxide, mix, evaporate the solvent to obtain an electrode slurry additive, and the amount of lithium hydroxide added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 6.1.

[0287] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 6.1.

[0288] The weight average molecular weight of the main dispersant was 13,000 as determined by gel permeation chromatography (GPC).

[0289] Comparative Example 7

[0290] The electrode slurry additive provided in this comparative example is basically the same as that in Example 5, except that the auxiliary dispersant polyacrylonitrile is replaced by PVP K30. The electrode slurry additive provided in this comparative example includes a main dispersant, a pH adjuster lithium hydroxide and PVP K30, and the main dispersant is prepared by polymerization reaction of the following components: monomer A1, monomer B1 and monomer C1.

[0291] The preparation method of the electrode slurry additive comprises the following steps:

[0292] S1, dissolving 20 g of monomer A1, 55 g of monomer B1 and 25 g of monomer C1 in 140 g of the first solvent N-methylpyrrolidone to obtain a monomer mixed solution;

[0293] S2. Continuously fill the monomer mixed solution with inert gas N2, add 0.5 g of initiator azobisisobutyronitrile and 0.5 g of chain transfer agent mercaptoethanol, heat to 75°C and react for 6 hours to obtain a main dispersant, then add 2.0 g of PVP K30 and lithium hydroxide, mix, evaporate the solvent, and obtain an electrode slurry additive. The amount of lithium hydroxide added is such that the pH value of a 10 wt% aqueous solution of the electrode slurry additive is 6.2.

[0294] The pH value of the electrode slurry additive prepared in this example was tested: the electrode slurry additive was dissolved in deionized water to obtain an aqueous solution with a concentration of 10 wt %, and the pH value of the aqueous solution was 6.2.

[0295] In order to compare the technical effects of the above embodiments and comparative examples, the following experimental examples are specially designed.

[0296] Experimental Example 1

[0297] The electrode slurry additives prepared in Examples 1 to 13 and Comparative Examples 1 to 7 were added to the battery electrode slurry formula to prepare slurry by the following method:

[0298] In parts by weight, 95.5 parts of lithium iron phosphate (Hunan Yuneng New Energy Battery Materials Co., Ltd., model Y9C), 1.5 parts of conductive carbon black Super P, 0.5 parts of conductive carbon nanotubes (Tiannai Technology, model LB156), and 2.5 parts of binder PVDF (US Solvay, model PVDF5130) were added with N-methylpyrrolidone at a total solid content of 67% (solid components are lithium iron phosphate, conductive carbon black Super P, conductive carbon nanotubes and binder PVDF) to prepare a slurry matrix, and then the electrode slurry additives prepared in each embodiment and comparative example were added to the slurry matrix according to 0.2% of the total solid mass, and mixed evenly using a double planetary mixer to obtain an electrode slurry.

[0299] At the same time, the slurry matrix without adding electrode slurry additives was used as a blank control group.

[0300] The NDJ-8S digital rotational viscometer produced by Shanghai Fangrui Instrument Co., Ltd. was used to test the initial dynamic viscosity of the electrode slurry at 25°C after uniform dispersion, as well as the dynamic viscosity of the electrode slurry at 25°C after standing for 24 hours. The specific results are shown in Table 1.

[0301] Table 1

[0302]

[0303]

[0304] From Table 1, we can see at least the following points:

[0305] (1) It can be seen from Examples 1-13 and the blank control group that the electrode slurry additive provided by the present invention is applied to the electrode slurry, which can reduce the slurry viscosity growth rate and improve the slurry viscosity stability. At the same time, the initial viscosity of the slurry is also greatly reduced. Under the same solid content conditions, low viscosity slurry means improved coating efficiency. Similarly, under the same existing construction viscosity conditions, increasing the slurry solid content can improve the energy density of lithium batteries.

[0306] (2) It can be seen from Example 1 and Examples 5-7 that when the electrode slurry additive includes an auxiliary dispersant, the stability of the electrode slurry viscosity can be further improved.

[0307] (3) It can be seen from Examples 2 and 10 that when the electrode slurry additive contains a pH adjuster, the electrode slurry additive with a suitable pH value can improve the stability of the slurry viscosity.

[0308] (4) It can be seen from Example 1 and Comparative Example 6 that when the mass of monomer B is less than the mass of monomer C, the effect of the additive decreases and the viscosity of the slurry increases.

[0309] (5) It can be seen from Example 5 and Comparative Example 7 that when the auxiliary dispersant in the electrode slurry additive is a cyano group-containing polymer, the stability of the electrode slurry viscosity can be improved.

[0310] (6) By comparing Example 1 with Comparative Example 1, it can be seen that R 3 The electrode slurry additive obtained by using an alkyl group with more than 5 carbon atoms has a significant effect on the slurry viscosity stability, while R 3 When the group is ethyl, the electrode slurry additive has a poor effect on the slurry viscosity stability; from the comparison between Example 1 and Comparative Example 4, it can be seen that the R 13 The electrode slurry additive obtained by using an alkyl group with more than 5 carbon atoms has a significant effect on the viscosity stability of the slurry, while R 13 When the group is ethyl, the electrode slurry additive obtained has a very poor effect on the slurry viscosity stability.

[0311] (7) By comparing Example 1 with Comparative Examples 2 and 3, it can be seen that reducing any of the three monomers cannot produce an electrode slurry additive that has a good effect on the slurry viscosity stability.

[0312] Experimental Example 2

[0313] The slurry prepared by using the electrode slurry additives prepared in Examples 1-13 and Comparative Examples 1-7 in Experimental Example 1 and the slurry matrix as a blank control group were made into electrode sheets, and the specific steps were as follows:

[0314] The electrode slurry or slurry matrix was filtered through a 100-mesh screen, coated on an aluminum foil with a thickness of 16 μm by an extrusion coater, dried in a blast oven at 110°C, and coated on an electrode sheet with a length of 2000 m. The surface density of the electrode sheet 5 m after the start of coating and the surface density of the electrode sheet 5 m before the end of coating were detected and recorded. The specific results are shown in Table 2.

[0315] Table 2

[0316]

[0317]

[0318] From Table 2, we can see at least the following points:

[0319] (1) It can be seen from Examples 1-13 and the blank control group that the surface density of the electrode slurry containing the electrode slurry additive provided by the present invention hardly changes before and after coating, indicating that the electrode slurry additive provided by the present invention can improve the consistency of the surface density of the electrode slurry coated on the electrode sheet while improving the viscosity stability of the electrode slurry, thereby improving the yield of the battery cell.

[0320] (2) It can be seen from Examples 1-13 and Comparative Examples 1-6 that the reason why the electrode slurry additive provided by the present invention can improve the stability of the slurry viscosity and at the same time improve the consistency of the electrode coating surface density depends on the selection and combination of monomer A, monomer B and monomer C, and the selection of the pH regulator also plays a crucial role in further improving the effect of the additive.

[0321] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode slurry additive, characterized in that: The electrode slurry additive includes a main dispersant, which is prepared by polymerization of the following components: monomer A, monomer B and monomer C; Wherein, the structural formula of the monomer A is: CH2=CR 1 R 2 , Among them, R 1 is -H or a C1-C3 saturated hydrocarbon group, R 2 Select from -OR 3 or -COOR 3 , R 3 Selected from C5-C36 saturated or unsaturated chain hydrocarbon groups; The structural formula of the monomer B is: O=P(OR 4 )(OR 5 )(OR 6 ); Among them, R 4 , R 5 and R 6 are the same or different and are each independently selected from -H or -R 7 R 8 C=CHR 9 , and R 4 , R 5 and R 6 Not at the same time -H; R 7 -(CH2CH2O) n (CH2CH2CH2O) m (CH2CH(CH3)O) k -or -(CH2CH2O) n (CH2CH2CH2O) m (CH2CH(CH3)O) k -CH2-or -(CH2CH2O) n (CH2CH2CH2O) m (CH2CH(CH3)O) k -OC-; n, m and k are each independently any integer from 0 to 60, and n, m and k are not 0 at the same time; R 8 is -H or a C1-C3 saturated hydrocarbon group; R 9 is -H or -COOH; The structural formula of the monomer C is: CH2=CR 10 R 11 ; Among them, R 10 is -H or a C1-C3 saturated hydrocarbon group; R 11 For-R 12 -(CH2CH2O) x (CH2CH2CH2O) y (CH2CH(CH3)O) z -R 13 or -R 12 -(CH2CH2O) x (CH2CH2CH2O) y (CH2CH(CH3)O) z -CH2CH2NHCO-R 13 or -R 12 -(CH2CH2O) x (CH2CH2CH2O) y (CH2CH(CH3)O) z -CH2CH2NH-R 13 ; x, y and z are each independently any integer from 0 to 60, and x, y and z are not 0 at the same time; R 12 is selected from -O-, -COO-, -CH2O-, -CH2CH2O- or -CH2CH2CH2O-; R 13 Selected from C5-C36 saturated or unsaturated chain hydrocarbon groups; The mass ratio of the monomer A, the monomer B and the monomer C is (10-30): (35-65): (25-40); The mass of the monomer B is not less than the mass of the monomer C.

2. The electrode slurry additive according to claim 1, characterized in that: The R 3 -CH2(CH2CH2)5CH3, -CH2CH(CH2CH3)CH2CH2CH2CH3, -CH2(CH2CH2)8CH3, -CH2(CH2CH2) 14 CH3 or -CH2(CH2CH2)3CH2CH=CH(CH2CH2)3CH2CH3; and / or, the R 7 -(CH2CH2O) 12 -、-(CH2CH2O) 24 CH2-、-(CH2CH2O) 18 (CH2CH2CH2O) 12 OC-、-(CH2CH2O) 12 OC-、-(CH2CH2O) 60 -or-(CH2CH2O) 24 -; and / or, the R 11 -O(CH2CH2O) 42 CH2(CH2CH2)5CH3、-COO(CH2CH2O) 42 CH2CH2NHCOCH2(CH2CH2)8CH3、-CH2CH2O(CH2CH2O) 12 CH2CH2NHCOCH2(CH2CH2)3CH=CH(CH2CH2)3CH2CH3 or -CH2O(CH2CH2O) 22 (CH2CH(CH3)O) 10 CH2CH2 NHCH2(CH2CH2)5CH3。 3. The electrode slurry additive according to claim 1 or 2, characterized in that: The monomer A is selected from the following compounds: CH2=CHOCH2(CH2CH2)5CH3、 CH2=CHOCH2CH(CH2CH3)CH2CH2CH2CH3, CH2=C(CH3)COOCH2(CH2CH2)8CH3, CH2=C(CH3)COOCH2(CH2CH2)3CH2CH=CH(CH2CH2)3CH2CH3; And / or, the monomer B is selected from the following compounds: O=P(OH)(OH)(O(CH2CH2O) 12 CH=CH2)、 O=P(OH)(O(CH2CH2O) 24 CH2CH=CH2)(O(CH2CH2O) 24 CH2CH=CH2)、 O=P(O(CH2CH2O) 18 (CH2CH2CH2O) 12 OCCH=CH2)(O(CH2CH2O) 12 OC CH=CH2)(O(CH2CH2O) 24 CH=CH2)、 O=P(OH)(OH)(O(CH2CH2O) 60 CH=CHCOOH); And / or, the monomer C is selected from the following compounds: CH2=CHO(CH2CH2O) 42 CH2(CH2CH2)5CH3、 CH2=CHCOO(CH2CH2O) 42 CH2CH2NHCOCH2(CH2CH2)8CH3、 CH2=CHCH2O(CH2CH2O) 22 (CH2CH(CH3)O) 10 CH2CH2NHCH2(CH2CH2)5CH3、 CH2=C(CH3)CH2CH2O(CH2CH2O) 12 CH2CH2NHCOCH2(CH2CH2)3CH=CH(CH2CH2)3CH2C H3； And / or, the weight average molecular weight of the primary dispersant is 3,000 to 50,000.

4. The electrode slurry additive according to claim 1, characterized in that: The electrode slurry additive further includes a pH regulator, and the amount of the pH regulator is such that the pH value of a 10 wt % aqueous solution of the electrode slurry additive is 1.0 to 9.0; And / or, the electrode slurry additive further includes an auxiliary dispersant, and the auxiliary dispersant is a cyano-containing polymer.

5. The electrode slurry additive according to claim 4, characterized in that: The pH regulator includes at least one of alkali metal hydroxide, ammonia, and organic amine compounds; And / or, the cyano group-containing polymer includes at least one of polyacrylonitrile, poly(acrylonitrile-butadiene), poly(acrylonitrile-vinyl pyrrolidone), hydrogenated poly(acrylonitrile-butadiene), poly(acrylonitrile-acrylic acid), poly(acrylonitrile-hydroxyethyl acrylate), and poly(acrylonitrile-acrylic acid-hydroxyethyl acrylate); And / or, based on the total mass of the monomer A, the monomer B and the monomer C being 100%, the mass of the auxiliary dispersant accounts for 1% to 5% of the total mass of the monomer A, the monomer B and the monomer C.

6. A method for preparing an electrode slurry additive according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: S1, dissolving the monomer A, the monomer B and the monomer C in a first solvent to obtain a monomer mixed solution; S2. Continuously charging the monomer mixed solution with an inert gas, and adding an initiator and a chain transfer agent to carry out a polymerization reaction to obtain an electrode slurry additive including the main dispersant.

7. The method for preparing an electrode slurry additive according to claim 6, characterized in that: The first solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, toluene, xylene, tetrahydrofuran, dioxane, and water; and / or, based on the total mass of the electrode slurry additive and the first solvent being 100%, the mass of the first solvent accounts for 10% to 70%; And / or, the inert gas is N2; And / or, the initiator includes at least one of azobisisobutyronitrile, azobisisoheptylnitrile, dibenzoyl peroxide, persulfate, hydrogen peroxide, peroxycarboxylate, and peroxydicarbonate; and / or, based on the total mass of the monomer A, the monomer B and the monomer C being 100%, the added mass of the initiator accounts for 0.1 to 5% of the total mass of the monomer A, the monomer B and the monomer C; And / or, the chain transfer agent includes at least one of mercaptoethanol, thioglycolic acid, mercaptopropionic acid, n-butyl mercaptan, n-octyl mercaptan, tert-butyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, hexadecyl mercaptan, octadecyl mercaptan, 2-ethylhexyl thioglycolate, isooctyl thioglycolate, and isooctyl mercaptopropionate; and / or, based on the total mass of the monomer A, the monomer B and the monomer C being 100%, the added mass of the chain transfer agent accounts for 0.1% to 3% of the total mass of the monomer A, the monomer B and the monomer C; And / or, after step S2, the preparation method further comprises the following steps: adding the pH adjusting agent; And / or, after step S2, the preparation method further comprises the following steps: The auxiliary dispersant is added.

8. An electrode slurry, characterized in that: The electrode slurry comprises the electrode slurry additive according to any one of claims 1 to 5 or the electrode slurry additive prepared by the method for preparing the electrode slurry additive according to claim 6 or 7.

9. An electrode plate, characterized in that: The electrode plate comprises the electrode slurry additive described in any one of claims 1 to 5, or the electrode slurry additive prepared by the preparation method of the electrode slurry additive described in claim 6 or 7, or the electrode slurry described in claim 8.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the electrode slurry additive according to any one of claims 1 to 5, or the electrode slurry additive prepared by the preparation method of the electrode slurry additive according to claim 6 or 7, or the electrode slurry according to claim 8, or the electrode plate according to claim 9.

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