Dispersant composition for dispersing lithium iron phosphate precursor, lithium iron phosphate positive electrode material and secondary battery

Abstract

The invention provides a dispersing agent composition for dispersing a lithium iron phosphate precursor, a lithium iron phosphate positive electrode material and a secondary battery. The dispersing agent composition comprises a first dispersing agent and a second dispersing agent; the first dispersing agent is selected from any one or a combination of at least two of sulfonate, sulfate, organic ammonium salt, polyoxyethylene ether, cross-linked modified polyoxyethylene, phosphate and derivatives thereof, alkoxy polyethylene glycol silane, polyhydroxy alcohol or high fructose corn syrup; the second dispersing agent is selected from any one or a combination of at least two of polyoxyalkylene ether and a derivative thereof, polyether modified polysiloxane, unsaturated carboxylate and a derivative thereof, quaternary ammonium salt, alkyl sulfonate, alkyl sulfonate, polyethylene glycol and a derivative thereof or polyamino amide. The dispersant composition provided by the invention not only can significantly improve the solid content of the lithium iron phosphate precursor, but also can reduce the water consumption in the preparation process of lithium iron phosphate.

Description

Technical Field

[0001] The present invention belongs to the technical field of dispersant materials, and in particular relates to a dispersant composition for dispersing a lithium iron phosphate precursor, a lithium iron phosphate positive electrode material and a secondary battery. Background Art

[0002] As a cathode material, olivine-type lithium iron phosphate has become one of the most promising cathode materials for lithium-ion batteries due to its advantages such as low price, safety, environmental protection, long cycle life and good thermal stability. The conductivity of lithium iron phosphate currently used in the market is poor, mainly due to two reasons: on the one hand, the particle size of lithium iron phosphate is too large; on the other hand, the particle size of lithium iron phosphate is uneven. The size and uniformity of the precursor particles of lithium iron phosphate directly affect the particle size and uniformity of the prepared lithium iron phosphate, and ultimately affect the electrochemical performance of the entire battery.

[0003] In the process of preparing lithium iron phosphate by carbothermal reduction, the preparation of precursor is an essential and important link. The precursor preparation process requires that the carbon source and lithium source are evenly distributed around the iron source. Uneven mixing of precursors directly reduces the purity of lithium iron phosphate. Therefore, the uniformity and dispersion performance of the precursor raw material mixing directly affect the electrochemical performance of lithium iron phosphate.

[0004] The mixing and dispersion process of lithium iron phosphate precursor is one of the important links in the production of lithium batteries. The quality of its dispersion and uniformity directly affects the electrochemical performance of the sintered material. At the same time, the electrode active materials in the slurry are prone to form secondary agglomerates, which causes serious agglomeration of lithium battery slurry and affects the subsequent sintering quality. In order to avoid the above situation, a large amount of solvent is needed to disperse the precursor material, resulting in a continuous increase in material costs, equipment investment and energy consumption.

[0005] Therefore, in the art, there is an urgent need to develop a dispersant for dispersing lithium iron phosphate precursors, so as to improve the dispersion performance and mixing uniformity of the lithium iron phosphate precursors, thereby improving the dispersion uniformity of the slurry and the sintering quality of lithium iron phosphate. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a dispersant composition for dispersing a lithium iron phosphate precursor, a lithium iron phosphate positive electrode material and a secondary battery. The dispersant composition provided by the present invention can not only significantly increase the solid content of the lithium iron phosphate precursor, but also reduce the amount of water consumed in the preparation process of lithium iron phosphate.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a dispersant composition for dispersing a lithium iron phosphate precursor, the dispersant composition comprising a first dispersant and a second dispersant;

[0009] The first dispersant is selected from any one or a combination of at least two of lignin sulfonate, alkyl aryl sulfonate, phenolic condensate sulfonate, succinate ester sulfonate, fatty alcohol sulfate, fatty alcohol polyoxyethylene ether sulfate, organic ammonium salt, polyoxyethylene ether, cross-linked modified polyoxyethylene, phosphate and its derivatives, alkoxy polyethylene glycol silane, polyhydroxy alcohol or fructose syrup;

[0010] The second dispersant is selected from any one or a combination of at least two of polyoxyalkylene ethers and their derivatives, polyether-modified polysiloxanes, unsaturated carboxylates and their derivatives, quaternary ammonium salts, alkyl sulfonates, alkyl sulfonate esters, polyethylene glycol and its derivatives, or polyaminoamides.

[0011] The present invention aims at solving the technical problems in the prior art that the lithium iron phosphate precursor has poor dispersibility and the prepared slurry is prone to agglomeration. The present invention provides a dispersant for increasing the solid content of the lithium iron phosphate precursor, and can also reduce the amount of water consumed in the preparation process of the lithium iron phosphate, thereby ensuring the mixing uniformity of the precursor, and further preparing a lithium iron phosphate product with superior performance.

[0012] Among them, the first dispersant contains a hydrophobic backbone and a hydrophilic long chain. The adsorption of the dispersant on the surface of the precursor effectively promotes the dispersion of the agglomerated structure in the precursor slurry and enhances the electrostatic repulsion and steric hindrance between the particles. The hydrophobic backbone is closer to the precursor side due to the electrostatic attraction of the negative charge, while the hydrophilic long side chain stretches in the solution to form a hydrated film on the surface.

[0013] The second dispersant is an oil phase, which has a low surface tension and can continuously diffuse and penetrate into the surface of the precursor liquid film. The surface tension between the oil phase and the water phase is very different. Under the continuous traction of the water phase, the oil phase is stretched and thinned to a certain range, which can prevent the gas phase from penetrating, eliminate gas phase interference, and improve the dispersion effect.

[0014] Preferably, the first dispersant is selected from any one or a combination of at least two of phenolic condensate sulfonates, succinate sulfonates, phosphates and their derivatives, polyhydroxy alcohols, organic ammonium salts, cross-linked modified polyoxyethylene, fatty alcohol sulfates, fatty alcohol polyoxyethylene ether sulfates or fructose syrup.

[0015] In the present invention, the first dispersant selected from the above preferred types has the advantages of simple acquisition and better dispersing effect.

[0016] Preferably, the first dispersant is selected from a combination of at least two of phenolic condensate sulfonates, succinate sulfonates, phosphates and their derivatives, polyhydroxy alcohols, organic ammonium salts, cross-linked modified polyoxyethylene, fatty alcohol sulfates, fatty alcohol polyoxyethylene ether sulfates or fructose syrup.

[0017] Preferably, the alkyl aryl sulfonate comprises alkyl naphthalene sulfonate and / or alkyl benzene sulfonate.

[0018] Preferably, the alkylnaphthalene sulfonate comprises Any one or a combination of at least two of the following.

[0019] Preferably, the alkylbenzene sulfonate comprises sodium dodecylbenzene sulfonate.

[0020] Preferably, the structural formula of the succinate sulfonate is R 1 OOC-H2C-CHSO3M-COOR 2 , where R 1 is selected from any one of a fatty alcohol group, a fatty amine group, an alkanoic acid amide group, a fatty acid monoglyceride group, an organic silicate group or a nonylphenol group, and M is selected from K + 、Na + , Li + NH4 + or -[N(CH2CH2OH) x ] +y -Any one of R 2 Selected from fatty alcohol groups, fatty amine groups, alkanoic acid amide groups, fatty acid monoglyceride groups, organic siliconic acid groups, nonylphenol groups, K + 、Na + , Li + NH4 + or -[N(CH2CH2OH) m ] +n -, where the value range of x is 1-3, the value range of y is 1-3, the value range of m is 1-3, and the value range of n is 1-3.

[0021] Preferably, the structural formula of the fatty alcohol sulfate is R1-OSO3M, wherein M is selected from Na + or NH4 + The R1 group is selected from a hydrocarbon group having 12 to 18 carbon atoms, and the number of carbon atoms can be, for example, 12, 13, 14, 15, 16, 17, 18, etc.

[0022] Preferably, the fatty alcohol polyoxyethylene ether sulfate includes lauryl alcohol polyoxyethylene ether sulfate.

[0023] Preferably, the organic ammonium salt comprises ammonium citrate and / or ammonium polycarboxylate.

[0024] Preferably, the polyoxyethylene ether includes polyoxyethylene alkylphenol ether and / or polyoxyethylene fatty secondary alcohol ether.

[0025] Preferably, the structural formula of the polyoxyethylene alkylphenol ether is Wherein R2 is selected from -C8H 17 or -C9H 19 , the value range of n is an integer from 5 to 10, for example, it can be 5, 6, 7, 8, 9, 10, etc.

[0026] Preferably, the cross-linked modified polyoxyethylene has a structural formula of R5[(CHR3CHR4O) k (CH2CH2O) m ] p , wherein R5 is selected from an organic compound matrix containing at least two active hydrogen atoms, and R3 and R4 are each independently selected from -H or C1~C 22 Alkyl, and R3 and R4 are not all -H, and the value of p is an integer in the range of 1 to 5, for example, it can be 1, 2, 3, 4, 5, etc.

[0027] In the present invention, R5 is selected from an organic compound matrix containing at least two active hydrogen atoms, for example, CH3NH-, C6H5NH-, etc.

[0028] Preferably, the -(CHR3CHR4O) k The weight average molecular weight of the structural unit is 2000 to 7000, for example, 2000, 2200, 2500, 2800, 3000, 3200, 3500, 3800, 4000, 4200, 4500, 4800, 5000, 5200, 5500, 5800, 6000, 6200, 6500, 6800, 7000, etc.

[0029] In the present invention, by regulating -(CHR3CHR4O) k -The weight-average molecular weight of the structural unit makes the molecular chain length more appropriate, forming steric hindrance. If the molecular weight is too low, the dispersion effect will be reduced, otherwise it will lead to unstable dispersion structure.

[0030] Preferably, based on the total mass of the cross-linked modified polyoxyethylene as 100%, the -(CH2CH2O) m -The mass percentage of the structural unit is 35% to 75%, for example, it can be 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, etc.

[0031] In the present invention, by regulating -(CH2CH2O) m -The mass percentage of the structural unit makes the anchoring structure with the precursor particles more stable. If the content is too low, the anchoring effect will be reduced, and vice versa, the dispersion effect will be reduced.

[0032] Preferably, the phosphate ester and its derivatives include ethylene glycol monobutyl ether sodium phosphate and / or nonylphenol polyoxyethylene ether phosphate monoester.

[0033] Preferably, the structural formula of the alkoxypolyethylene glycol silane is Wherein R6 is selected from C1~C 12 Alkyl, where C1~C 12 The number of carbon atoms of the alkyl group can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.; the value range of t is an integer from 10 to 40, for example, it can be 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, etc.

[0034] Preferably, the polyhydric alcohol comprises any one of mannitol, sorbitol, xylitol, propylene glycol, glycerol or cyclohexanehexasol, or a combination of at least two thereof.

[0035] Preferably, the polyoxyalkylene ether and its derivatives include any one of polyoxypropylene glycerol polyether, polyoxypropylene polyoxyethylene glycerol ether or polyoxypropylene polyoxyethylene glycerol polyether ester, or a combination of at least two thereof.

[0036] Preferably, the unsaturated carboxylate and its derivatives include any one of sodium oleate, octadecenylamine acetate or aminopropylamine dioleate, or a combination of at least two thereof.

[0037] Preferably, the polyethylene glycol and its derivatives include polyethylene glycol and / or polyethylene glycol monolauryl ether.

[0038] Preferably, the number of amino groups in the polyaminoamide structure is 2-5, for example, 2, 3, 4, or 5.

[0039] Preferably, the mass percentage of the first dispersant in the dispersant composition is 10-99%, preferably 25-50%, for example, it can be 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, 92%, 95%, 98%, 99% and the like.

[0040] In the present invention, the optimal dispersion effect is achieved by adjusting the mass percentage of the first dispersant. If the content is too low, the dispersion effect will be reduced, and vice versa, it will increase the difficulty of use and preparation.

[0041] Preferably, the mass percentage of the second dispersant in the dispersant composition is 1-3%, preferably 1-2%, for example, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, etc.

[0042] In the present invention, the optimal barrier effect is achieved by adjusting the mass percentage of the second dispersant. If the content is too low, the barrier effect will be reduced, and vice versa, the cost will be increased.

[0043] Preferably, the dispersant composition may further include a solvent.

[0044] Preferably, the solvent comprises deionized water.

[0045] Preferably, the mass percentage of the solvent in the dispersant composition is 10-90%, for example, it can be 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90% and the like.

[0046] In a second aspect, the present invention provides a method for preparing a dispersant composition, comprising the following steps:

[0047] The optional solvent is mixed with the first dispersant, and stirred for 20-40 minutes at a stirring speed of 40-60 rpm; then the second dispersant is added, and stirred for 10-40 minutes at a stirring speed of 30-70 rpm to obtain the dispersant composition.

[0048] In a third aspect, the present invention provides a lithium iron phosphate positive electrode material, wherein the lithium iron phosphate positive electrode material comprises the dispersant composition according to the first aspect.

[0049] In a fourth aspect, the present invention provides a secondary battery, comprising a positive electrode, a negative electrode, an electrolyte and a separator, wherein the positive electrode comprises the lithium iron phosphate positive electrode material according to the third aspect.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] The present invention provides a dispersant composition, which aims to solve the technical problems in the prior art that a lithium iron phosphate precursor has poor dispersibility and the prepared slurry is prone to agglomeration, and provides a dispersant for increasing the solid content of the lithium iron phosphate precursor, and can also reduce the amount of water consumed in the preparation process of the lithium iron phosphate, ensure the mixing uniformity of the precursor, and thus prepare a lithium iron phosphate product with superior performance. DETAILED DESCRIPTION

[0052] The technical solution of the present invention is further described below by specific implementation methods. 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.

[0053] Example 1

[0054] The present embodiment provides a dispersant composition for dispersing a lithium iron phosphate precursor, the dispersant composition comprising a first dispersant, a second dispersant and deionized water; the first dispersant is fructose syrup and sodium dodecylbenzene sulfonate, and the second dispersant is polyoxypropylene glycerol ether (purchased from Jining Tangyi GP-330).

[0055] This embodiment also provides a method for preparing the above dispersant composition, which comprises the following steps:

[0056] According to the mass parts, 83 mass parts of deionized water, 12 mass parts of fructose syrup, and 4 mass parts of sodium dodecylbenzene sulfonate were stirred for 30 minutes at a speed of 50 rpm, and then 1 mass part of polyoxypropylene glycerol ether was added and stirred for 20 minutes at a speed of 60 rpm to obtain a dispersant composition.

[0057] Example 2

[0058] This embodiment provides a dispersant composition for dispersing a lithium iron phosphate precursor, the dispersant composition comprising a first dispersant, a second dispersant and deionized water; the first dispersant is sodium lignin sulfonate and polyoxyethylene alkylphenol ether (purchased from Shandong Yonglida OP-10), and the second dispersant is sodium oleate.

[0059] This embodiment also provides a method for preparing the above dispersant composition, which comprises the following steps:

[0060] According to the mass parts, 40 mass parts of deionized water, 53 mass parts of sodium lignin sulfonate, and 5 mass parts of polyoxyethylene alkylphenol ether were stirred for 30 minutes at a speed of 50 rpm, and then 2 mass parts of sodium oleate were added and stirred for 20 minutes at a speed of 60 rpm to obtain a dispersant composition.

[0061] Example 3

[0062] This embodiment provides a dispersant composition for dispersing a lithium iron phosphate precursor, the dispersant composition comprising a first dispersant, a second dispersant and deionized water; the first dispersant is sorbitol, sodium succinate sulfonate and sodium lauryl alcohol polyoxyethylene ether sulfate, and the second dispersant is polyoxypropylene polyoxyethylene glycerol polyether ester (purchased from Wuhan Jiyesheng JYS1554).

[0063] This embodiment also provides a method for preparing the above dispersant composition, which comprises the following steps:

[0064] According to the weight parts, 75 weight parts of deionized water, 15 weight parts of sorbitol, 5 weight parts of succinate sulfonic acid Sodium and 3 parts by mass of sodium lauryl alcohol polyoxyethylene ether sulfate were stirred for 30 min at a speed of 50 rpm, and then 2 parts by mass of polyoxypropylene polyoxyethylene glycerol polyether ester were added and stirred for 20 min at a speed of 60 rpm to obtain a dispersant composition.

[0065] Example 4

[0066] This embodiment provides a dispersant composition for dispersing a lithium iron phosphate precursor, the dispersant composition comprising a first dispersant, a second dispersant and deionized water; the first dispersant is (R6 is decyl), sodium sulfosuccinate and high fructose corn syrup, and the second dispersant is polyoxypropylene glyceryl ether (purchased from Jining Tangyi GP-330).

[0067] This embodiment also provides a method for preparing the above dispersant composition, which comprises the following steps:

[0068] According to the mass fraction, 77 mass parts of deionized water, 13 mass parts of (R6 is decyl), 3 parts by mass of sodium sulfosuccinate The mixture was stirred with 4 parts by mass of fructose syrup at a speed of 50 rpm for 30 min, and then 3 parts by mass of polyoxypropylene glycerol ether was added and stirred for 20 min at a speed of 60 rpm to obtain a dispersant composition.

[0069] Example 5

[0070] The difference between this embodiment and embodiment 1 is that, based on the mass parts, 1 mass part of polyoxypropylene glyceryl ether is replaced by 0.5 mass parts of polyoxypropylene glyceryl ether and 0.5 mass parts of sodium oleate, and the rest is the same as embodiment 1.

[0071] Example 6

[0072] The difference between this embodiment and embodiment 1 is that, by weight, 12 parts by weight of high fructose corn syrup are replaced by 6 parts by weight of sorbitol and 6 parts by weight of sodium lauryl polyoxyethylene ether sulfate, and the rest are the same as in embodiment 1.

[0073] Example 7

[0074] The difference between this embodiment and embodiment 1 is that in the preparation method, according to the mass parts, 83 mass parts of deionized water, 1 mass part of fructose syrup, and 4 mass parts of sodium dodecylbenzene sulfonate are stirred for 30 minutes at a speed of 50 rpm, and then 12 mass parts of polyoxypropylene glycerol ether are added and stirred for 20 minutes at a speed of 60 rpm to obtain a dispersant composition. The rest is the same as in embodiment 1.

[0075] Example 8

[0076] The difference between this embodiment and embodiment 1 is that in the preparation method, according to the mass parts, 83.5 mass parts of deionized water, 12 mass parts of fructose syrup, and 4 mass parts of sodium dodecylbenzene sulfonate are stirred for 30 minutes at a speed of 50 rpm, and then 0.5 mass parts of polyoxypropylene glycerol ether are added and stirred for 20 minutes at a speed of 60 rpm to obtain a dispersant composition. The rest is the same as in embodiment 1.

[0077] Example 9

[0078] The difference between this embodiment and embodiment 1 is that high fructose corn syrup and sodium dodecylbenzene sulfonate are replaced by high fructose corn syrup in equal parts by mass, and the rest is the same as embodiment 1.

[0079] Comparative Example 1

[0080] The difference between this comparative example and Example 1 is that polyoxypropylene glycerol ether is replaced with an equal mass portion of sodium dodecylbenzene sulfonate, and the rest is the same as Example 1.

[0081] Comparative Example 2

[0082] The difference between this comparative example and Example 1 is that fructose syrup and sodium dodecylbenzene sulfonate are replaced by polyoxypropylene glycerol ether in equal parts by mass, and the rest are the same as Example 1.

[0083] Application Examples 1 to 9 and Comparative Application Examples 1 to 3

[0084] The dispersant compositions provided in Examples 1 to 9 and Comparative Examples 1 to 2 are used to prepare lithium iron phosphate, and the preparation method is as follows:

[0085] The prepared dispersant is added to a mixture of iron phosphate, lithium carbonate and glucose in a certain proportion (doping amount is 0.5%), and an appropriate amount of water (solid content is 75%) is added, and stirred evenly in a ball mill for 5 hours to obtain a lithium iron phosphate precursor. The precursor is then dried, sintered and ground to obtain a lithium iron phosphate product.

[0086] Comparative Application Example 3

[0087] Add appropriate amount of water (solid content 75%) to a mixture of iron phosphate, lithium carbonate and glucose in a certain proportion (doping amount is 0.5%), stir evenly in a ball mill for 5 hours to obtain lithium iron phosphate precursor. Then, the precursor is dried, sintered and ground to obtain lithium iron phosphate products.

[0088] Test conditions

[0089] The lithium iron phosphate provided by Application Examples 1 to 9 and Comparative Application Examples 1 to 3 was tested, and the test method was as follows:

[0090] Using lithium iron phosphate material as the positive electrode active material and lithium sheet as the negative electrode, a double-electrode experimental battery was assembled and a constant current charge and discharge cycle test was carried out at room temperature using a battery tester. The charge and discharge voltage was 2.0-4.0V and the charge and discharge rate was 0.2C.

[0091] The test results are shown in Table 1:

[0092] Table 1

[0093]

[0094] It can be seen from Table 1 that the dispersant composition provided in Application Examples 1-6 of the present invention, at the same solid content, can not only reduce the amount of water consumed in the preparation process of lithium iron phosphate and ensure the mixing uniformity of the precursor, but also improve the capacity and cycle life of the lithium iron phosphate material.

[0095] Application Example 7 is a case where the contents of the first dispersant and the second dispersant exceed the preferred range. When the content of the first dispersant is too low and the content of the second dispersant is too high, the dispersing effect of the dispersant is affected, causing the performance of the material to deteriorate. Application Example 8 is a case where the content of the second dispersant is too low, which affects the barrier effect of the dispersant and causes the performance of the material to deteriorate.

[0096] Comparative Application Examples 1-2 show that a single type of dispersant cannot achieve the synergistic effect of the first dispersant and the second dispersant.

[0097] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A dispersant composition for dispersing a lithium iron phosphate precursor, characterized in that: The dispersant composition includes a first dispersant and a second dispersant; The first dispersant is selected from any one or a combination of at least two of lignin sulfonate, alkyl aryl sulfonate, phenolic condensate sulfonate, succinate ester sulfonate, fatty alcohol sulfate, fatty alcohol polyoxyethylene ether sulfate, organic ammonium salt, polyoxyethylene ether, cross-linked modified polyoxyethylene, phosphate and its derivatives, alkoxy polyethylene glycol silane, polyhydroxy alcohol or fructose syrup; The second dispersant is selected from any one or a combination of at least two of polyoxyalkylene ethers and their derivatives, polyether-modified polysiloxanes, unsaturated carboxylates and their derivatives, quaternary ammonium salts, alkyl sulfonates, alkyl sulfonate esters, polyethylene glycol and its derivatives, or polyaminoamides.

2. The dispersant composition according to claim 1, characterized in that The first dispersant is selected from any one or a combination of at least two of phenolic condensate sulfonates, succinate sulfonates, phosphates and their derivatives, polyhydroxy alcohols, organic ammonium salts, cross-linked modified polyoxyethylene, fatty alcohol sulfates, fatty alcohol polyoxyethylene ether sulfates or fructose syrup; Preferably, the first dispersant is selected from a combination of at least two of phenolic condensate sulfonates, succinate sulfonates, phosphates and their derivatives, polyhydroxy alcohols, organic ammonium salts, cross-linked modified polyoxyethylene, fatty alcohol sulfates, fatty alcohol polyoxyethylene ether sulfates or fructose syrup; Preferably, the alkyl aryl sulfonate comprises alkyl naphthalene sulfonate and / or alkyl benzene sulfonate; Preferably, the alkylnaphthalene sulfonate comprises Any one or a combination of at least two of the following: Preferably, the alkylbenzene sulfonate comprises sodium dodecylbenzene sulfonate; Preferably, the structural formula of the succinate sulfonate is R 1 OOC-H2C--CHSO3M-COOR 2 Where R 1 is selected from any one of a fatty alcohol group, a fatty amine group, an alkanoic acid amide group, a fatty acid monoglyceride group, an organic silicate group or a nonylphenol group, and M is selected from K + 、Na + , Li + NH4 + or -[N(CH2CH2OH) x ] +y -Any one of R 2 Selected from fatty alcohol groups, fatty amine groups, alkanoic acid amide groups, fatty acid monoglyceride groups, organic siliconic acid groups, nonylphenol groups, K + 、Na + , Li + NH4 + or -[N(CH2CH2OH) m ] +n -, where x is in the range of 1-3, y is in the range of 1-3, m is in the range of 1-3, and n is in the range of 1-3; Preferably, the structural formula of the fatty alcohol sulfate is R1-OSO3M, wherein M is selected from Na + or NH4 + , the R1 group is selected from a hydrocarbon group having 12 to 18 carbon atoms; Preferably, the fatty alcohol polyoxyethylene ether sulfate includes lauryl alcohol polyoxyethylene ether sulfate.

3. The dispersant composition according to claim 1 or 2, characterized in that The organic ammonium salt includes ammonium citrate and / or polycarboxylate ammonium salt; Preferably, the polyoxyethylene ether includes polyoxyethylene alkylphenol ether and / or polyoxyethylene fatty secondary alcohol ether; Preferably, the structural formula of the polyoxyethylene alkylphenol ether is Wherein R2 is selected from -C8H 17 or -C9H 19 , the value of n is an integer ranging from 5 to 10; Preferably, the cross-linked modified polyoxyethylene has a structural formula of R5[(CHR3CHR4O) k (CH2CH2O) m ] p , wherein R5 is selected from an organic compound matrix containing at least two active hydrogen atoms, and R3 and R4 are each independently selected from -H or C1~C 22 Alkyl, R3 and R4 are not all -H, and the value of p is an integer ranging from 1 to 5; Preferably, the -(CHR3CHR4O) k -The weight average molecular weight of the structural unit is 2000 to 7000; Preferably, based on the total mass of the cross-linked modified polyoxyethylene as 100%, the -(CH2CH2O) m -The mass percentage of the structural unit is 35% to 75%.

4. The dispersant composition according to any one of claims 1 to 3, characterized in that The phosphate ester and its derivatives include ethylene glycol monobutyl ether sodium phosphate and / or nonylphenol polyoxyethylene ether phosphate monoester; Preferably, the structural formula of the alkoxypolyethylene glycol silane is Wherein R6 is selected from C1~C 12 Alkyl, t is an integer ranging from 10 to 40; Preferably, the polyhydric alcohol comprises any one of mannitol, sorbitol, xylitol, propylene glycol, glycerol or cyclohexanehexasol, or a combination of at least two thereof.

5. The dispersant composition according to any one of claims 1 to 4, characterized in that The polyoxyalkylene ether and its derivatives include any one or a combination of at least two of polyoxypropylene glycerol polyether, polyoxypropylene polyoxyethylene glycerol ether or polyoxypropylene polyoxyethylene glycerol polyether ester; Preferably, the unsaturated carboxylate and its derivatives include any one of sodium oleate, octadecenylamine acetate or aminopropylamine dioleate, or a combination of at least two thereof.

6. The dispersant composition according to any one of claims 1 to 5, characterized in that The polyethylene glycol and its derivatives include polyethylene glycol and / or polyethylene glycol monolauryl ether; Preferably, the number of amino groups in the polyaminoamide structure is 2-5.

7. The dispersant composition according to any one of claims 1 to 6, characterized in that The mass percentage of the first dispersant in the dispersant composition is 10 to 99%, preferably 25 to 50%; Preferably, the mass percentage of the second dispersant in the dispersant composition is 1 to 3%, preferably 1 to 2%.

8. The dispersant composition according to any one of claims 1 to 7, characterized in that The dispersant composition may further include a solvent; Preferably, the solvent comprises deionized water; Preferably, the mass percentage of the solvent in the dispersant composition is 10 to 90%.

9. A lithium iron phosphate positive electrode material, characterized in that: The lithium iron phosphate positive electrode material comprises the dispersant composition according to any one of claims 1-8.

10. A secondary battery, characterized in that: The secondary battery comprises a positive electrode, a negative electrode, an electrolyte and a separator, and the positive electrode comprises the lithium iron phosphate positive electrode material according to claim 9.

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