Phosphate pulverizer and method of use

Abstract

The grinding method comprises the steps of forming a slurry by combining FePO4, Li2CO3, water, a carbon source, and a grinding agent, wherein the grinding agent of the slurry has structure (I), where n of structure (I) is 1 to 10, R1 is selected from the group consisting of hydrogen, alkylphenyl group, linear or branched primary or secondary alkyl chain, and R2 is selected from the group consisting of hydrogen, methyl group, ethyl group, or a combination thereof, and grinding the slurry.

Description

[Technical Field]

[0001] Areas of this disclosure This disclosure relates to a grinding agent, and more particularly to a method for using a phosphoric acid grinding agent.

[0002] Introduction The increasing number of battery-powered home appliances and, more recently, vehicles has led to a significant increase in demand for lithium-ion batteries and the products used in their manufacture. Each lithium-ion battery contains a cathode typically composed of LiFePO4 ("LFP"). While the industrial production of LFPs is achieved through various processes, the most common is solid-phase synthesis. Solid-phase synthesis of LFPs involves several steps. In the first step of producing LFPs, raw materials (FePO4, Li2CO3, a carbon source, and a grinding agent) are dispersed in water, and the resulting slurry has a raw material particle size of approximately 400 nm or less. 50 The material is ground in a sand mill until it reaches a certain size. Next, the slurry is spray-dried to obtain aggregated particles of the mixed raw materials. The resulting spray-dried particle size is approximately 10 μm. 50 It should exhibit the following characteristics. Finally, the spray-dried LFP particles are calcined in an N2 atmosphere. From there, the LFP can be fabricated into a cathode for battery manufacturing.

[0003] One of the most time-consuming processes in LFP production is the grinding time of the raw materials. The grinding of the LFP raw materials is necessary to achieve the desired D 50 It can take more than 8 hours to reach the desired particle size. During the grinding process, grinding agents are used to help disperse the solid raw materials and increase grinding efficiency. High efficiency in sand mill grinding means shorter grinding times, which leads to higher production efficiency, lower costs, and better sustainability. Therefore, by utilizing high-performance grinding agents, the development of LFP can be greatly accelerated. Grinding agents that achieve particle sizes of 400 nm to less than 1% (i.e., 404 nm) in less than 4 hours will dramatically improve the efficiency of the grinding process.

[0004] The selection of materials used, and when those materials are used in the fabrication of LFPs and LFP-based cathodes, involves additional considerations that take into account the electrochemical properties of the battery. For example, most grinding agents are surfactants such as sodium dodecyl sulfate ("SDS"), hexadecyltrimethylammonium bromide ("CTAB"), and polyethylene glycol (PEG). However, in the case of SDS and CTAB, heteroatoms present in such grinding agents, such as S, N, and Br, significantly reduce the electrochemical stability of the LFP cathode. Furthermore, metal ions, such as Na, also contribute to this. + Li + This hinders the transport of these elements and significantly impacts the electrical performance of the LFP. Therefore, alkali atoms, such as those neutralized with alkali atoms as provided in Patent Publication No. 2014-149968(A), should be avoided because such neutralization introduces undesirable heteroatoms. Ideally, grinding agents should not introduce detectable S, N, Br, and metal ions into the LFP slurry.

[0005] Considering the above, it would be remarkable and advantageous to discover a grinding agent and method that not only achieves a particle size of 1% or less from 400 nm (i.e., 404 nm) within 4 hours of grinding, but also does not introduce S, N, Br, and metal ions into the LFP slurry. [Overview of the project]

[0006] The inventors of this disclosure have discovered a grinding agent and method that not only achieves a particle size of 1% or less (i.e., 404 nm) from 400 nm by grinding within 4 hours, but also does not introduce S, N, Br, and metal ions into the LFP slurry.

[0007] This disclosure is the result of a discovery that the affinity between FePO4 and the grinding agent can be increased by using a grinding agent containing an unneutralized phosphate moiety. It was found that the increased affinity between the phosphate-containing grinding agent and FePO4 allows FePO4 to be ground to within 1% from 400 nm faster than with conventional grinding agents. Furthermore, by utilizing the unneutralized phosphate moiety in the grinding agent, the grinding agent does not donate heteroatoms to the LFP slurry and any resulting products. As a result, using the grinding agent of the present invention in the grinding process not only saves time and energy in grinding but also avoids contamination of the LFP slurry, as occurs with conventional grinding agents.

[0008] According to the first feature of this disclosure, the grinding method comprises the steps of: mixing FePO4, Li2CO3, water, a carbon source, and a grinding agent to form a slurry, wherein the grinding agent of the slurry has structure (I), where n of structure (I) is 1 to 10, R1 is selected from the group consisting of hydrogen, alkylphenyl groups, linear or branched primary or secondary alkyl chains, and R2 is selected from the group consisting of hydrogen, methyl groups, ethyl groups, or combinations thereof; and grinding the slurry.

[0009] According to the second feature of this disclosure, the step of grinding the slurry involves grinding the slurry for 4 hours to obtain a slurry D of 404 nm or less, as measured according to a particle size test. 50 The process further includes obtaining particle size.

[0010] According to the third feature of this disclosure, the step of mixing FePO4, Li2CO3, water, a carbon source, and a grinding agent to form a slurry further includes the step of mixing FePO4, Li2CO3, water, a carbon source, a grinding agent, and polyethylene glycol to form a slurry.

[0011] According to the fourth feature of this disclosure, the carbon source is glucose.

[0012] According to the fifth feature of this disclosure, R2 in structure (I) is hydrogen.

[0013] According to the sixth feature of this disclosure, R1 is not hydrogen, and the total number of carbon atoms in structure (I) is between 6 and 18.

[0014] According to the seventh feature of this disclosure, R1 is an alkylphenol selected from the group consisting of octylphenyl, nonylphenyl, and combinations thereof.

[0015] According to the eighth feature of this disclosure, R1 is C 12 ~C 14 It is a secondary alkyl group.

[0016] According to the ninth feature of this disclosure, the slurry comprises, based on the total weight of the slurry, 20% to 30% by weight of FePO4, 1% to 10% by weight of Li2CO3, 5% to 15% by weight of a carbon source, 50% to 70% by weight of water, and 0.1% to 5% by weight of a grinding agent.

[0017] According to the tenth feature of this disclosure, the slurry contains 1% to 2% by weight of a grinding agent, based on the total weight of the slurry. [Modes for carrying out the invention]

[0018] As used herein, the term "and / or" means, when used in an enumeration of two or more items, that any one of the enumerated items may be used alone, or any combination of two or more of the enumerated items may be used. For example, if a composition is described as containing components A, B, and / or C, the composition may contain A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0019] Unless otherwise indicated, all ranges include their endpoints.

[0020] Unless the test method is indicated with a two-digit number with hyphens for the date together with the test method number, it refers to the latest test method at the priority date of this document. References to test methods contain both a reference to the test society and a reference to the test method number. Test method organizations are referred to by one of the following abbreviations. That is, ASTM refers to ASTM International (formerly known as American Society for Testing and Materials), IEC refers to International Electrotechnical Commission, EN refers to European Norm, DIN refers to Deutsches Institut fuer Normung, and ISO refers to International Organization for Standards.

[0021] As used herein, the term weight percent ("wt%") refers to the percentage by weight that a component occupies in the total weight of the polymer composition, unless otherwise specified.

[0022] As used herein, the Chemical Abstract Services Registry Number ("CAS#") refers to the unique numerical identifier last assigned by Chemical Abstract Service to a chemical compound at the priority date of this document.

[0023] Method The present disclosure is directed to a grinding method. This method includes a step of mixing FePO4, Li2CO3, water, a carbon source, and a grinding agent to form a slurry, and a step of grinding the slurry. The grinding of the slurry can be carried out in a bead mill, a sand mill, a basket mill, or other types of mills configured to grind the particles in the slurry to a small and uniform size using a grinding medium. The grinding medium (i.e., beads, sand, etc.) is typically spherical and has a diameter of 0.1 mm to 5 mm. The grinding medium is harder than the components of the slurry to be ground. During grinding, the slurry and the grinding medium can be rotated, subjected to a rotating drum, shaken, or otherwise agitated to induce grinding of the slurry. In an example where grinding is achieved by rotation, the mill can be rotated at a speed of 500 revolutions per minute (「rpm」) to 2000 rpm. The grinding of the slurry is carried out for 1 hour or more, or 2 hours or more, or 3 hours or more, or 4 hours or more, or 5 hours or more, or 6 hours or more, or 7 hours or more, or 8 hours or more, or 9 hours or more, but at the same time, for a period of 10 hours or less, or 9 hours or less, or 8 hours or less, or 7 hours or less, or 6 hours or less, or 5 hours or less, or 4 hours or less, or 3 hours or less, or 2 hours or less.

[0024] The grinding of the slurry is carried out for a period until the particles of FePO4 and Li2CO3 reach the desired D 50 particle size. The D 50 particle size is the median particle size of the distribution, indicating that 50% by volume of the particles are larger than the D 50 value and 50% by volume of the particles are smaller than the D 50 value. The D 50 particle size is determined according to the particle size test described in more detail below. The slurry can have a D 50 particle size of 404 nm or less, or 400 nm or less, or 380 nm or less, or 360 nm or less, or 340 nm or less, or 320 nm or less, or 300 nm or less, or 280 nm or less, or 260 nm or less, or 240 nm or less, or 220 nm or less, or 200 nm or less, measured according to the particle size test.

[0025] Ferric phosphate The slurry contains ferric phosphate. Ferric phosphate has the chemical formula FePO4. Ferric phosphate may be added to the slurry as a powder, as multiple particles, or as an aqueous dispersion. The slurry contains 20% to 30% by weight of FePO4 based on the total weight of the slurry. For example, the slurry may contain 20% or more by weight, or 21% or more by weight, or 22% or more by weight, or 23% or more by weight, or 24% or more by weight, or 25% or more by weight, or 26% or more by weight, or 27% or more by weight, or 28% or more by weight, or 29% or more by weight, based on the total weight of the slurry, but at the same time may contain 30% or less by weight, or 29% or less by weight, or 28% or less by weight, or 27% or less by weight, or 26% or less by weight, or 25% or less by weight, or 24% or less by weight, or 23% or less by weight, or 22% or less by weight, or 21% or less by weight, or less than that amount of ferric phosphate.

[0026] Lithium carbonate The slurry contains lithium carbonate. Lithium carbonate has the chemical formula Li2CO3. Lithium carbonate may be added to the slurry as a powder, as multiple particles, or as an aqueous dispersion. The slurry contains 1% to 10% by weight of lithium carbonate based on the total weight of the slurry. For example, the slurry may contain 1% or more by weight, or 2% or more by weight, or 3% or more by weight, or 4% or more by weight, or 5% or more by weight, or 6% or more by weight, or 7% or more by weight, or 8% or more by weight, or 9% or more by weight, based on the total weight of the slurry, but at the same time may contain 10% or less by weight, or 9% or less by weight, or 8% or less by weight, or 7% or less by weight, or 6% or less by weight, or 5% or less by weight, or 4% or less by weight, or 3% or less by weight, or 2% or less by weight, or 1% or less by weight, or less than that amount of lithium carbonate.

[0027] Carbon source The slurry may contain one or more carbon sources. The carbon sources are selected from the group consisting of carbon black, glucose, carbon nanotubes, graphene, polyethylene glycol, sucrose, and combinations thereof. The slurry contains 5% to 15% by weight of carbon sources based on the total weight of the slurry. For example, the slurry may contain 5% or more by weight, or 6% or more by weight, or 7% or more by weight, or 8% or more by weight, or 9% or more by weight, or 10% or more by weight, or 11% or more by weight, or 12% or more by weight, or 13% or more by weight, or 14% or more by weight, based on the total weight of the slurry, but at the same time may contain 15% or less by weight, or 14% or less by weight, or 13% or less by weight, or 12% or less by weight, or 11% or less by weight, or 10% or less by weight, or 9% or less by weight, or 8% or less by weight, or 7% or less by weight, or 6% or less by weight, or less of the carbon source.

[0028] water The slurry contains water. The slurry may contain 50% to 70% by weight of water, based on the total weight of the slurry. For example, the slurry may contain 50% or more by weight, or 52% or more by weight, or 54% or more by weight, or 56% or more by weight, or 58% or more by weight, or 60% or more by weight, or 62% or more by weight, or 64% or more by weight, or 66% or more by weight, or 68% or more by weight, but at the same time may contain 70% or less by weight, or 68% or less by weight, or 66% or less by weight, or 64% or less by weight, or 62% or less by weight, or 60% or less by weight, or 58% or less by weight, or 56% or less by weight, or 54% or less by weight, or 52% or less by weight, or less than that, of water. The slurry may have 20% to 60% by weight of solids (i.e., the sum of the weights of the solid components divided by the total weight of the slurry). For example, the slurry must contain 20% or more solids by weight, or 22% or more solids by weight, or 24% or more solids by weight, or 26% or more solids by weight, or 28% or more solids by weight, or 30% or more solids by weight, or 32% or more solids by weight, or 34% or more solids by weight, or 36% or more solids by weight, or 38% or more solids by weight, or 40% or more solids by weight, or 42% or more solids by weight, or 44% or more solids by weight, or 46% or more solids by weight, or 48% or more solids by weight, or 50% or more solids by weight, or 52% or more solids by weight, or 54% or more solids by weight, or 56% or more solids by weight, or 58% or more solids by weight. However, at the same time, the solid content may be 60% by weight or less, or 58% by weight or less, or 56% by weight or less, or 54% by weight or less, or 52% by weight or less, or 50% by weight or less, or 48% by weight or less, or 46% by weight or less, or 44% by weight or less, or 42% by weight, or 40% by weight or less, or 38% by weight or less, or 36% by weight or less, or 34% by weight or less, or 32% by weight or less, or 30% by weight or less, or 28% by weight or less, or 26% by weight or less, or 24% by weight or less, or 22% by weight.

[0029] Grinding agent The slurry contains a grinding agent. The grinding agent has structure (I),

[0030] [ka] In the formula, n in structure (I) is 1 to 10, R1 is selected from the group consisting of hydrogen, an alkylphenyl group, and a linear or branched primary or secondary alkyl chain, and R2 is selected from the group consisting of hydrogen, a methyl group, an ethyl group, or a combination thereof. If R2 is not hydrogen, it will be understood that structure (I) may have one or both of a methyl group and an ethyl group, depending on the value of n. Furthermore, such combinations of methyl and ethyl groups may be random or in block order within structure (I). If R1 is an alkylphenol, R1 may be an alkylphenol selected from the group consisting of octylphenyl, nonylphenyl, and combinations thereof. In yet another example, R1 is C 12 ~C 14 A secondary alkyl group may also be used.

[0031] In cases where R1 is not hydrogen, the total number of carbon atoms in structure (I) can be 6 to 18. For example, the total number of carbon atoms in structure (I) is 13 Determined by ¹¹C nuclear magnetic resonance, it may be 6 or higher, or 7 or higher, or 8 or higher, or 9 or higher, or 10 or higher, or 11 or higher, or 12 or higher, or 13 or higher, or 14 or higher, or 15 or higher, or 16 or higher, or 17 or higher, but at the same time it may be 18 or lower, or 17 or lower, or 16 or lower, or 15 or lower, or 14 or lower, or 13 or lower, or 12 or lower, or 11 or lower, or 10 or lower, or 9 or lower, or 8 or lower, or 7 or lower.

[0032] The value of n in structure (I) is 13 Determined by ¹¹¹ nuclear magnetic resonance, it may be 1 or more, or 2 or more, or 3 or more, or 4 or more, or 5 or more, or 6 or more, or 7 or more, or 8 or more, or 9 or more, but at the same time, it may be 10 or less, or 9 or less, or 8 or less, or 7 or less, or 6 or less, or 5 or less, or 4 or less, or 3 or less, or 2 or less.

[0033] Specific examples of pulverizing agents include glycol octylphenyl ether phosphoric acid such as structure (II), ethoxylated C12-14 secondary alcohol phosphoric acid such as structure (III), and C6-12 ethoxylated alcohol phosphoric acid and propoxylated alcohol phosphoric acid such as structure (IV).

[0034] [ka]

[0035] The slurry contains 0.1% to 5% by weight of grinding agent based on the total weight of the slurry. For example, the slurry contains 0.1% or more by weight, or 0.2% or more by weight, or 0.4% or more by weight, or 0.6% or more by weight, or 0.8% or more by weight, or 1.0% or more by weight, or 1.2% or more by weight, or 1.4% or more by weight, or 1.6% or more by weight, or 1.8% or more by weight, or 2.0% or more by weight, or 2.2% or more by weight, or 2.4% or more by weight, or 2.6% or more by weight, or 2.8% or more by weight, or 2.0% or more by weight, or 3.2% or more by weight, or 3.4% or more by weight, or 3.6% or more by weight, or 3.8% or more by weight, or 4.0% or more by weight, or 4.2% or more by weight, or 4.4% or more by weight, or 4.6% or more by weight, or 4.8% or more by weight. It is % or more, but at the same time may contain 5.0% by weight or less, or 4.8% by weight or less, or 4.6% by weight or less, or 4.4% by weight or less, or 4.2% by weight or less, or 4.0% by weight or less, or 3.8% by weight or less, or 3.6% by weight or less, or 3.4% by weight or less, or 3.2% by weight or less, or 3.0% by weight or less, or 2.8% by weight or less, or 2.6% by weight or less, or 2.4% by weight or less, or 2.2% by weight or less, or 2.0% by weight or less, or 1.8% by weight or less, or 1.6% by weight or less, or 1.4% by weight or less, or 1.2% by weight or less, or 1.0% by weight or less, or 0.8% by weight or less, or 0.6% by weight or less, or 0.4% by weight or less, or 0.2% by weight or less of a grinding agent.

[0036] Polyethylene glycol The slurry contains polyethylene glycol. Polyethylene glycol is a compound having structure (V), H-(O-CH2-CH2) n -OH structure (V) In the formula, n refers to the number of repeating units in the polyethylene glycol polymer. The value of n for polyethylene glycol is: 13 The molecular weight can range from 10 to 80, as determined by 14C nuclear magnetic resonance. Polyethylene glycol has a weight-average molecular weight of 1000 g / mol to 3500 g / mol, as measured by gel permeation chromatography. For example, the weight-average molecular weight of polyethylene glycol, as measured by gel permeation chromatography, may be 1000 g / mol or more, or 1250 g / mol or more, or 1450 g / mol or more, or 1500 g / mol or more, or 1750 g / mol or more, or 2000 g / mol or more, or 2250 g / mol or more, or 2500 g / mol or more, or 2750 g / mol or more, or 3000 g / mol or more, or 3250 g / mol or more, but at the same time, it may be 3500 g / mol or less, or 3250 g / mol or less, or 3000 g / mol or less, or 2750 g / mol or less, or 2500 g / mol or less, or 2250 g / mol or less, or 2000 g / mol or less, or 1750 g / mol or less, or 1500 g / mol or less, or 1250 g / mol or less. An example of a commercially available polyethylene glycol is CARBOWAX® polyethylene glycol 1450 manufactured by The Dow Chemical Company (Midland, Michigan). [Examples]

[0037] material The following materials were used in the comparative example ("CE") and the embodiment of the present invention ("IE").

[0038] FePO4 is ferric phosphate and is commercially available from Sinopharm (Beijing, China).

[0039] Li2CO3 is lithium carbonate and is commercially available from Sinopharm (Beijing, China).

[0040] Glucose is C6H 12 It is O6 and is commercially available from Sinopharm (Beijing, China).

[0041] PEG1450 is a polyethylene glycol with a weight-average molecular weight of 1,450 g / mol and is commercially available from The Dow Chemical Company (Midland, Michigan) as CARBOWAX® polyethylene glycol 1450.

[0042] MA1 is a structure (II) active substance present in 100% by weight in water and is commercially available from The Dow Chemical Company (Midland, Michigan).

[0043] MA2 is a structure (III) active substance present in 100% by weight in water and is commercially available from The Dow Chemical Company (Midland, Michigan).

[0044] PPA is phosphoric acid with a concentration of 99.7% by weight or higher, and is commercially available from Sinopharm (Beijing, China).

[0045] SURF1 is a surfactant having structure (VI),

[0046] [ka] It is commercially available from The Dow Chemical Company (Midland, Michigan).

[0047] MA3 is the active substance of structure (IV) at 100% by weight in water. MA3 is synthesized by the following procedure. First, 58 grams of SURF1 were placed in a three-necked flask under an N2 atmosphere and heated to 35°C with mechanical stirring at 300 rpm. Mechanical stirring was kept constant throughout the formation of MA3. Next, 10.69 grams of PPA were added dropwise to the flask over 10 minutes to form a solution. After the addition of PPA was complete, the temperature was raised to 45°C and the system was stirred for a further 30 minutes. Next, the temperature was raised to 80°C and the system was stirred for a further 3.5 hours. Next, the solution turned yellow and 1 mL of water was added to accelerate hydrolysis. Next, the solution was cooled to 65°C and stirred for a further 10 hours to complete hydrolysis. Next, the solution was cooled to 23°C.

[0048] Sample preparation The LFP slurries of the examples and comparative examples of the present invention were prepared according to the following procedure and had the composition in wt% shown in Table 1. First, the pulverizers used (i.e., MA1, MA2, and MA3) were dried in an oven at 80°C for 24 hours. Next, FePO4 and Li2CO3 were dispersed in water and mixed at 1200 rpm for 2 minutes using a SPEEDMIXER® DAC150 mixer to form a system. Next, glucose was added to the system and mixed at 1200 rpm until completely dissolved. Next, the indicated amounts of pulverizers were added to the system and mixed at 1200 rpm until completely dissolved.

[0049] [Table 1]

[0050] Test method Grinding: Grinding was performed in a 215 ml grinding tank with an inner diameter of 5 cm. Zirconium beads (0.8-1.2 mm in diameter) and slurry were added to the grinding tank in a 1:1 mass ratio. The grinding tank was operated at 1400 rpm for 8 hours. The grinding tank was stopped every 2 hours, and a 0.2 ml sample of the slurry was collected for particle size characteristic evaluation.

[0051] Particle size test: Particle size was measured using a Malvern Panasonic ZEN3600™ particle size analyzer. For measurement, the sample was diluted 20-fold with water. The refractive indices of the material and water were set to 1.71 and 1.33, respectively. The temperature was 25°C.

[0052] result Table 2 provides the grinding results for the examples and comparative examples of the present invention.

[0053] [Table 2]

[0054] Referring to Tables 1 and 2, glucose and glucose + PEG were set as comparative examples because they are typical materials conventionally used in the grinding of LFP slurries. As shown, glucose and PEG fall far short of achieving the target particle size of 400 nm to 1% (i.e., 404 nm) or less with grinding within 4 hours. Specifically, CE1 required 6 hours of grinding to achieve a size of 400 nm or less, while CE2 still failed to achieve the target.

[0055] Referring to IE1-IE6, using a grinding agent having structure (I) clearly achieves a target particle size of 1% or less from 400 nm (i.e., 404 nm) within 4 hours of grinding. As described above, the phosphate group of structure (I) is thought to contribute to increasing the affinity between the grinding agent and the ferric phosphate of the LFP precursor. At the same time, the ethylene oxide and / or ethylene oxide / propylene oxide portion of the grinding agent contributes to improving the affinity between the grinding agent and water. By effectively combining water and ferric phosphate, the grinding agent can accelerate the dispersion of the raw materials, thereby increasing grinding efficiency and thus achieving smaller LFP particle sizes faster than those provided by conventional materials. In addition to saving time and costs associated with the grinding process, the grinding agent of the present invention has the additional advantage of not introducing heteroatoms into the slurry.

Claims

1. FePO ４ And, Li ２ CO ３ A step of forming a slurry by combining water, a carbon source, and a grinding agent, wherein the grinding agent of the slurry has structure (I), 【Chemistry 1】 In the formula, n of structure (I) is 1 to 10, and R １ R is selected from the group consisting of hydrogen, alkylphenyl groups, and primary or secondary alkyl chains that are linear or branched, ２ This involves a process selected from the group consisting of hydrogen, a methyl group, an ethyl group, or a combination thereof, A grinding method comprising the step of grinding the slurry.

2. The step of crushing the slurry is The slurry is ground for 4 hours to obtain a slurry D with a particle size of 404 nm or less, as measured according to the particle size test. ５０ The method according to claim 1, further comprising obtaining particle size.

3. FePO ４ and Li ２ CO ３ and water, a carbon source, and a pulverizing agent are combined such that the step of forming a slurry is The aforementioned FePO ４ And the Li ２ CO ３ The method according to claim 1 or 2, further comprising combining the water, the carbon source, the pulverizer, and polyethylene glycol to form the slurry.

4. The method according to any one of claims 1 to 3, wherein the carbon source is glucose.

5. R of structure (I) ２ The method according to any one of claims 1 to 4, wherein is hydrogen.

6. R １ The method according to claim 5, wherein is not hydrogen, and the total number of carbon atoms in structure (I) is 6 to 18.

7. R １ The method according to claim 5, wherein the alkylphenol is selected from the group consisting of octylphenyl, nonylphenyl, and combinations thereof.

8. R １ C １２ ~C １４ The method according to claim 5, wherein the alkyl is a secondary alkyl.

9. The slurry, Based on the total weight of the slurry, 20% to 30% by weight of the FePO ４ and, Based on the total weight of the slurry, 1% to 10% by weight of the Li ２ CO ３ and, Based on the total weight of the slurry, 5% to 15% by weight of the carbon source and Based on the total weight of the slurry, 50% to 70% by weight of water, The method according to any one of claims 1 to 8, comprising 0.1% to 5% by weight of a grinding agent based on the total weight of the slurry.

10. The method according to any one of claims 1 to 9, wherein the slurry contains 1% to 2% by weight of the pulverizer based on the total weight of the slurry.

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