Dispersion agent for slurry with lithium iron phosphate

Abstract

For the present disclosure, the lithium iron phosphate (LFP) slurry comprises an iron compound, a lithium compound, a dispersant of Formula I: Formula I wherein n of Formula I is an integer from 1 to 10, and R1 of Formula I is selected from the group consisting of hydrogen, a C8 to C18 alkyl phenyl group, a straight chain or branched chain primary or secondary C1 to C18 alkyl chain, and R2 of Formula I is selected from the group consisting of hydrogen, a methyl group, an ethyl group, or a combination thereof; and an alkanolamine of Formula II: Formula II wherein R1, R2, and R3 of Formula II are independently selected from hydrogen or a hydroxyalkyl group having from 1 to 4 carbons.

Description

Technical Field

[0001] This disclosure generally relates to slurries, and more specifically to dispersants for slurries containing lithium iron phosphate. Background Technology

[0002] The electric vehicle (EV) market has expanded rapidly over the past decade due to increasingly stringent global environmental policies and government commitments to sustainability, leading to a growing demand for better energy storage devices. Lithium-ion batteries (LiB), currently the dominant energy storage product, have thus become one of the most popular industrial applications.

[0003] Global EV sales continue to grow at an unprecedented rate. By 2030, battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs) will account for >55% of new vehicle production in China, Europe, and North America. The global demand for LiB (Li-Bike) vehicles was 700 gigawatt-hours (GWh) by 2022 and is estimated to increase to 4.7 megawatt-hours (TWh) by 2030.

[0004] Of all the conventional cathode materials used in LiB, lithium iron phosphate (LiFePO4 or LFP) currently dominates the market due to its low cost, high stability, and high safety performance. However, with more and more manufacturers entering the market, competition among LFP manufacturers has intensified, and many key manufacturers are looking for new ways to not only commit to their sustainability goals but also reduce their production costs.

[0005] Currently, there are three different methods for manufacturing LFP: solid-state method, hydrothermal method, and sol-gel method. Among these three methods, the solid-state method is the most commonly used because the process is relatively straightforward, mature, and relatively inexpensive to set up. A typical solid-state process includes: (1) mixing all raw materials (Li source, Fe source, P source, etc.) and dispersing them in water; (2) milling the mixture for 6 to 10 hours until the desired particle size is achieved; (3) spray drying the precursor slurry; and (4) calcining the dried mixture to obtain the final LFP cathode active material product.

[0006] One of the many challenges of using LFP as a cathode active material is its low electronic conductivity. To improve the electrochemical performance of the battery, LFP manufacturers have carbon-coated LFP with various carbon sources, such as glucose, lactose, sucrose, maltose, and other carbon-containing organic compounds, to increase the conductivity of the active material. These carbon sources are added along with all other solid feedstocks in the process, and after the calcination step. The added carbon sources become a residual carbon layer surrounding the LFP particles, which promotes electron transport within the material.

[0007] Another challenge faced by many LFP manufacturers is improving their overall production efficiency by increasing the slurry solids content. Increasing the solids content can improve the production efficiency of the LFP, as well as the subsequent battery cathode and the quality of the final product. Both sand milling and spray drying in solid-state manufacturing methods require high energy inputs for prolonged sand milling or high water usage for spray drying.

[0008] Currently, the most common solids content used in this industry is approximately 30% to 40% by weight, with the remainder being water as a solvent. A limiting factor for any higher solids content is that when the slurry viscosity reaches greater than approximately 400 centipoise (cP), it can become very difficult to perform the subsequent spray drying step because the slurry is too viscous to be sprayed to the desired particle size. Therefore, the solids content cannot be increased without increasing the viscosity, and the maximum viscosity is approximately 400 cP when the spray drying step is necessary for LFP production. These drawbacks of not being able to increase the weight percentage of solids content indicate a continued need in the art to increase the solids content while keeping the viscosity below the threshold of the spray drying step. Summary of the Invention

[0009] In some respects, the techniques described herein relate to the production of lithium iron phosphate (LFP) slurries as components for cathode slurries. Increasing the solids content of LFP slurries results in higher quality cathode slurries; however, higher solids content leads to higher viscosity, which is detrimental to cathode production. LFP slurries may have viscosity limitations during different production steps. For example, the production may include a spray drying step to remove water from the LFP slurry. The spray drying step may require a viscosity of less than 400 cP. To increase the solids content of the LFP slurry while maintaining a viscosity below 400 cP, this disclosure utilizes a combination of dispersants and alkanolamines. Dispersants and alkanolamine LFP slurries address the disadvantages discussed herein and above.

[0010] For the purposes of this disclosure, the lithium iron phosphate (LFP) slurry comprises an iron compound, a lithium compound, and a dispersant of formula I:

[0011] Formula I

[0012] Wherein, n in Formula I is an integer from 1 to 10, and R1 in Formula I is selected from the group consisting of hydrogen, C8 to C18 alkylphenyl groups, straight-chain or branched primary or secondary C1 to C18 alkyl chains, and R2 in Formula I is selected from the group consisting of hydrogen, methyl groups, ethyl groups, or combinations thereof; and the alkanolamine of Formula II:

[0013] Formula II

[0014] In formula II, R1, R2, and R3 are independently selected from hydrogen or hydroxyalkyl groups having one to four carbons.

[0015] For the purposes of this disclosure, the solid content of the iron compound and lithium compound, based on the total weight of the lithium iron phosphate slurry, is greater than 50% by weight (wt.%) of the lithium iron phosphate slurry, and the lithium iron phosphate slurry has a viscosity of about 200 centipoise (cP) to about 700 cP. For the purposes of this disclosure, the iron compound is iron phosphate (FePO4), and the lithium compound is lithium carbonate (Li2CO3). For the purposes of this disclosure, the lithium iron phosphate slurry contains glucose as a carbon source. For the purposes of this disclosure, a dispersant of formula I and an alkanolamine of formula II are combined with the iron compound, the lithium compound, and water to form an aqueous mixture.

[0016] For this disclosure, the dispersant comprises 0.8% to 4.0% by weight of the total weight of both the iron compound and the lithium compound. For this disclosure, the alkanolamine is present in the slurry at 10 mol% to 120 mol% of the molar amount of the P(OH) site of the dispersant of Formula I. For this disclosure, R1 of the dispersant of Formula I is selected from alkylphenyl groups, straight-chain or branched groups, and primary or secondary alkyl chain groups having a total of 12 to 14 carbon atoms. For this disclosure, the molar ratio of lithium, iron, and phosphorus in the lithium iron phosphate slurry is approximately 1:1:1.

[0017] This disclosure also includes a method for producing a lithium iron phosphate slurry, the method comprising: a combination of an iron compound and a lithium compound, water, a carbon source of greater than 40% by weight of the lithium iron phosphate slurry, and a dispersant of combination I.

[0018] Formula I

[0019] Wherein, n of formula I is an integer from 1 to 10, and R1 of formula I is selected from the group consisting of hydrogen, C8 to C18 alkylphenyl groups, straight-chain or branched primary or secondary C1 to C18 alkyl chains, and R2 of formula I is selected from the group consisting of hydrogen, methyl groups, ethyl groups, or combinations thereof; and the alkanolamine of formula II:

[0020] Formula II

[0021] In formula II, R1, R2, and R3 are independently selected from hydrogen or hydroxyalkyl groups having one to four carbons.

[0022] The method further includes spray drying the lithium iron phosphate slurry when the viscosity of the lithium iron phosphate slurry is less than 400 centipoise (cP); and calcining the lithium iron phosphate mixture. For this disclosure, the iron compound is iron phosphate (FePO4), and the lithium compound is lithium carbonate (Li2CO3). For this disclosure, the composition of the dispersant of Formula I is in the range of 0.8 wt% to 4.0 wt% relative to the total amount of active material including iron phosphate (FePO4) and lithium carbonate (Li2CO3), and the composition of the alkanolamine of Formula II is in the range of 10 mol% to 120 mol% relative to the molar amount of P(OH) sites in the dispersant of Formula I.

[0023] For the purposes of this disclosure, the weight percentages of iron phosphate (FePO4) and lithium carbonate (Li2CO3) are greater than 45% by weight of the lithium iron phosphate slurry, and the viscosity of the lithium iron phosphate slurry is less than 200 cP. For the purposes of this disclosure, the carbon source is glucose. For the purposes of this disclosure, R1 of the dispersant of formula I is either octylphenyl or nonylphenyl. Detailed Implementation

[0024] In some respects, the techniques described herein relate to the production of LFP slurries as components used as cathode slurries. Increasing the solids content of an LFP slurry results in a higher quality cathode slurry; however, a higher solids content leads to a higher viscosity, which is detrimental to cathode production. LFP slurries may have viscosity limitations during different production steps. For example, the production may include a spray drying step to remove water from the LFP slurry. The spray drying step may require a viscosity of less than 400 cP, where the viscosity is measured as described in the Examples section herein. To increase the solids content of the LFP slurry while maintaining a viscosity below 400 cP, this disclosure utilizes a combination of dispersants and alkanolamines. Dispersants and alkanolamine LFP slurries address the disadvantages discussed herein and above.

[0025] This disclosure describes a combination formulation of phosphate ester and alkanolamine as an innovative dispersant for aqueous LFP precursor slurries. This dispersant can be added together with other raw materials during step (1) of a solid-state process. In some examples, no additional step is required other than adding the dispersant together with other raw materials of the solid-state process. The general chemical structure of the phosphate ester is shown in Formula I below, and the chemical structure of the alkanolamine is shown in Formula II below. As described herein, the composition of the phosphate ester dispersant can range from 0.8 wt% to 4.0 wt% relative to the total amount of active material added to the LFP slurry. The active material of the LFP slurry may comprise iron phosphate and / or lithium carbonate. The composition of the amine can range from 10 mol% to 120 mol% relative to the amount of P(OH) sites in the phosphate ester dispersant.

[0026] In some examples, the phosphate groups in the dispersant have a strong affinity for LFP precursor slurry particles and facilitate better dispersion of LFP particles during the milling process. Simultaneously, the alkanolamine provides neutralization of the OH groups to further stabilize the particles in water (aqueous mixtures). This dispersant formulation has demonstrated its ability to disperse LFP slurry particles, reduce the viscosity of the slurry after sand milling, and increase the maximum solids content to greater than 50% by weight.

[0027] For the purposes of this disclosure, the lithium iron phosphate (LFP) slurry comprises an iron compound, a lithium compound, and a dispersant of formula I:

[0028] Formula I

[0029] Wherein, n in Formula I is an integer from 1 to 10, and R1 in Formula I is selected from the group consisting of hydrogen, C8 to C18 alkylphenyl groups, straight-chain or branched primary or secondary C1 to C18 alkyl chains, and R2 in Formula I is selected from the group consisting of hydrogen, methyl groups, ethyl groups, or combinations thereof; and the alkanolamine of Formula II:

[0030] Formula II

[0031] In Formula II, R1, R2, and R3 are independently selected from hydrogen or hydroxyalkyl groups having one to four carbons. In a specific example, at least one of R1, R2, and R3 in Formula II is not hydrogen. In other examples, at least one of R1, R2, and R3 in Formula II is a hydroxyalkyl group having one to four carbons. In yet another example, R1 in Formula I is selected from the group consisting of hydrogen, C8 to C18 alkylphenyl groups, and straight-chain or branched primary or secondary C8 to C18 alkyl chains.

[0032] In some examples, n in Formula I is an integer from 3 to 8. In other examples, n in Formula I is one of 5 or 7.5. In some examples, R1 in Formula I is a C10 to C16 alkylphenyl group. In a specific example, R1 in Formula I is a C14 alkylphenyl group. In a specific example, R2 in Formula I is hydrogen. For the purposes of this disclosure, R1 in the dispersant of Formula I is selected from alkylphenyl groups, straight-chain or branched groups, and primary or secondary alkyl chain groups having a total of 12 to 14 carbon atoms. For the purposes of this disclosure, the molar ratio of lithium, iron, and phosphorus in the lithium iron phosphate slurry is approximately 1:1:1.

[0033] In some examples, at least one of the R1, R2, and R3 groups of Formula II includes one of a hydroxyalkyl group having one to four carbons. In some examples, at least two of the R1, R2, and R3 groups of Formula II include one of a hydroxyalkyl group having one to four carbons. In a specific example, the alkanolamine of Formula II is triisopropanolamine (TIPA), wherein each of the R1, R2, and R3 groups of Formula II is an isopropanolamine group. In a specific example, the alkanolamine of Formula II is triethanolamine (TEA), wherein each of the R1, R2, and R3 groups of Formula II is an ethanol group. In a specific example, the alkanolamine of Formula II is diethanolamine, wherein R1 is hydrogen, and R2 and R3 groups are ethanol groups. Furthermore, in a specific example, the alkanolamine of Formula II is ethanolamine (MEA), wherein R1 and R2 groups are hydrogen, and R3 group is an ethanol group.

[0034] In some examples, the solid content of iron and lithium compounds, based on the total weight of the lithium iron phosphate slurry, is greater than 40% by weight (wt.%) of the lithium iron phosphate slurry, and the lithium iron phosphate slurry has a viscosity of about 150 centipoise (cP) to about 600 cP, wherein the viscosity is measured as described in the Examples section herein. For the purposes of this disclosure, the solid content of iron and lithium compounds, based on the total weight of the lithium iron phosphate slurry, is greater than 50% by weight (wt%) of the lithium iron phosphate slurry, and the lithium iron phosphate slurry has a viscosity of about 200 centipoise (cP) to about 700 cP, wherein the viscosity is measured as described in the Examples section herein.

[0035] In this disclosure, the iron compound is iron phosphate (FePO4), and the lithium compound is lithium carbonate (Li2CO3). In this disclosure, the lithium iron phosphate slurry contains glucose as a carbon source. In this disclosure, a dispersant of formula I and an alkanolamine of formula II are combined with the iron compound, lithium compound, and water to form an aqueous mixture. As described herein, the iron compound and lithium compound can be active materials within the aqueous mixture. In this way, the iron compound and lithium compound can be 50% by weight of the aqueous mixture.

[0036] In some examples, the dispersant accounts for about 0.5 wt% to 5.0 wt% of the total weight of the two active materials (e.g., the combined weight of the iron compound and the lithium compound). For this disclosure, the dispersant accounts for 0.8 wt% to 4.0 wt% of the total weight of both the iron compound and the lithium compound. For this disclosure, the alkanolamine is present in the slurry at a molar amount of the P(OH) sites of the dispersant of Formula I, ranging from 10 mol% to 120 mol%. In some examples, the alkanolamine is present in the slurry at a molar amount of the P(OH) sites of the dispersant of Formula I, ranging from 10 mol% to 25 mol%. In other examples, the alkanolamine is present in the slurry at a molar amount of the P(OH) sites of the dispersant of Formula I, ranging from 25 mol% to 50 mol%. In still other examples, the alkanolamine is present in the slurry at a molar amount of the P(OH) sites of the dispersant of Formula I, ranging from 75 mol% to 100 mol%. In other examples, alkanolamines are present in the slurry at 100 mol% to 120 mol% of the molar amount of the P(OH) site of the dispersant of Formula I.

[0037] This disclosure also includes a method for producing a lithium iron phosphate slurry, the method comprising: a combination of an iron compound and a lithium compound, water, a carbon source of greater than 40% by weight of the lithium iron phosphate slurry, and a dispersant of combination I.

[0038] Formula I

[0039] Wherein, n of formula I is an integer from 1 to 10, and R1 of formula I is selected from the group consisting of hydrogen, C8 to C18 alkylphenyl groups, straight-chain or branched primary or secondary C1 to C18 alkyl chains, and R2 of formula I is selected from the group consisting of hydrogen, methyl groups, ethyl groups, or combinations thereof; and the alkanolamine of formula II:

[0040] Formula II

[0041] In formula II, R1, R2, and R3 are independently selected from hydrogen or hydroxyalkyl groups having one to four carbons.

[0042] In some examples, n in Formula I is an integer from 3 to 8. In other examples, n in Formula I is one of 5 or 7.5. In some examples, R1 in Formula I is a C10 to C16 alkylphenyl group. In a specific example, R1 in Formula I is a C14 alkylphenyl group. In a specific example, R2 in Formula I is hydrogen. For the purposes of this disclosure, R1 in the dispersant of Formula I is selected from alkylphenyl groups, straight-chain or branched groups, and primary or secondary alkyl chain groups having a total of 12 to 14 carbon atoms. For the purposes of this disclosure, the molar ratio of lithium, iron, and phosphorus in the lithium iron phosphate slurry is approximately 1:1:1.

[0043] In some examples, at least one of the R1, R2, and R3 groups of Formula II includes one of a hydroxyalkyl group having one to four carbons. In some examples, at least two of the R1, R2, and R3 groups of Formula II include one of a hydroxyalkyl group having one to four carbons. In a specific example, the alkanolamine of Formula II is triisopropanolamine (TIPA), wherein each of the R1, R2, and R3 groups of Formula II is an isopropanolamine group. In a specific example, the alkanolamine of Formula II is triethanolamine (TEA), wherein each of the R1, R2, and R3 groups of Formula II is an ethanol group. In a specific example, the alkanolamine of Formula II is diethanolamine, wherein R1 is hydrogen, and R2 and R3 groups are ethanol groups. Furthermore, in a specific example, the alkanolamine of Formula II is ethanolamine (MEA), wherein R1 and R2 groups are hydrogen, and R3 group is an ethanol group.

[0044] The method further includes spray drying the lithium iron phosphate slurry when the viscosity of the lithium iron phosphate slurry is less than 400 centipoise (cP); and calcining the lithium iron phosphate mixture, wherein the viscosity is measured as described in the Examples section herein. For this disclosure, the iron compound is iron phosphate (FePO4), and the lithium compound is lithium carbonate (Li2CO3). For this disclosure, the composition of the dispersant of Formula I is in the range of 0.8 wt% to 4.0 wt% relative to the total amount of active material comprising iron phosphate (FePO4) and lithium carbonate (Li2CO3), and the composition of the alkanolamine of Formula II is in the range of 10 mol% to 120 mol% relative to the molar amount of P(OH) sites in the dispersant of Formula I. In some examples, the alkanolamine is present in the slurry at 10 mol% to 25 mol% of the molar amount of P(OH) sites in the dispersant of Formula I. In other examples, the alkanolamine is present in the slurry at 25 mol% to 50 mol% of the molar amount of P(OH) sites in the dispersant of Formula I. In other examples, the alkanolamine is present in the slurry at 75 mol% to 100 mol% of the molar amount of the P(OH) sites of the dispersant of Formula I. In other examples, the alkanolamine is present in the slurry at 100 mol% to 120 mol% of the molar amount of the P(OH) sites of the dispersant of Formula I.

[0045] For the purposes of this disclosure, the weight percentages of iron phosphate (FePO4) and lithium carbonate (Li2CO3) are greater than 45% by weight of the lithium iron phosphate slurry, and the viscosity of the lithium iron phosphate slurry is less than 200 cP, wherein the viscosity is measured as described in the Examples section herein. For the purposes of this disclosure, the carbon source is glucose. For the purposes of this disclosure, R1 of the dispersant of Formula I is either octylphenyl or nonylphenyl.

[0046] Example

[0047] In the embodiments, various terms and names for materials are used, including, for example, the following:

[0048] Material

[0049] The materials used in the Examples (EX) and / or Comparative Examples (CE) include the following materials.

[0050]

[0051]

[0052]

[0053]

[0054] Preparation of Lithium Iron Phosphate (LFP) Slurry

[0055] The composition of the phosphate ester dispersant can range from 0.8 wt.% to 4.0 wt.% relative to the total amount of added active material (FePO4 + Li2CO3). The composition of the amine can range from 10 mol% to 120 mol% relative to the amount of P(OH) sites in the phosphate ester dispersant.

[0056] The formulations are shown in Table 3. The total active material solids content was set at 50% by weight, and water was used as the solvent. FePO4 was used as the Fe and P source, while Li2CO3 was used as the Li source. The Li:Fe:P molar ratio was approximately 1:1:1. In these embodiments, glucose was used as a carbon source to increase the electronic conductivity of the resulting LFP slurry.

[0057] The procedure for preparing LFP precursor slurries (e.g., LFP mixtures, LFP precursor blends) is as follows: First, FePO4 and Li2CO3 are pre-dispersed in water at 1000 rpm for 2 minutes using a Speedmixer DAC 150. Then, glucose is added to the mixture and mixed until completely dissolved. The remaining ingredients, as indicated in each formulation, are added to the mixture and mixed until completely dissolved. The mixture is then transferred to a grinding cadmium for a sand milling process. Sand milling is a process in which grinding beads are added to solid materials and mixed together at a relatively high speed. The laboratory-scale sand mill used for the sand milling process utilizes 1400 rpm. The cadmium is 200 mL and is surrounded by flowing cooling water during the milling process. Zirconia beads (0.8 mm to 1.2 mm in diameter) are added to the grinding cadmium at a 1:1 mass ratio. The mixture is then sand milled at room temperature (approximately 22 degrees Celsius) for 8 hours. If foaming is observed during this process, additional defoamer is added. After milling, all beads were filtered out, and the viscosity of the LFP precursor slurry was measured at room temperature (approximately 22 degrees Celsius) using a Brookfield viscometer DV-II+Pro. The rotation speed during the measurement was set to 60 1 / s. A No. 10 conical mandrel was used.

[0058] Data Analysis

[0059] CE1 represents a formulation without the addition of a dispersant or an amine (alkanolamine). After 8 hours of milling, the viscosity of the LFP precursor was measured to be 802 centipoise (cP). CE1 serves as a baseline for future comparative studies regarding the effect of viscosity reduction in the LFP precursor slurry. CE2 represents a formulation with only a phosphate ester added, without an amine. Comparing CE2 to CE1, the viscosity of the LFP precursor slurry in CE2 is even higher than that of the baseline example in CE1. IE1, IE2, IE3, and IE4 are embodiments of the invention using dispersant 1 as a phosphate ester and ethanolamine (MEA) as an alkanolamine, wherein the molar ratio of amine to P(OH) sites differs (120%, 100%, 75%, and 50%, respectively). When compared to CE1, the examples IE1, IE2, IE3, and IE4 effectively reduce the viscosity of the LFP precursor slurry. For example, CE1 has a measured viscosity of 802 cP, while IE1 has a measured viscosity of 640 cP, IE2 has a measured viscosity of 406 cP, IE3 has a measured viscosity of 632 cP, and IE4 has a measured viscosity of 426 cP. IE5 is an embodiment of the invention that also uses dispersant 1 as a phosphate ester and 25 mol% DEA as an alkanolamine. When compared with embodiments CE1 and CE2, embodiment IE5 effectively reduces the viscosity of the LFP precursor slurry. For example, CE1 has a measured viscosity of 802 cP, and CE2 has a measured viscosity of 1096 cP, while embodiment IE5 has a measured viscosity of 704 cP. IE6 and IE7 are embodiments of the invention that use dispersant 1 as a phosphate ester and triethanolamine (TEA) as an alkanolamine, wherein the molar ratio of amine to P(OH) site is 16.5% and 10%, respectively. When compared with CE1 and CE2, it was observed that both IE6 and IE7 effectively reduce the viscosity of the LFP precursor slurry. For example, CE1 has a measured viscosity of 802 cP, and CE2 has a measured viscosity of 1096 cP, while the IE6 example has a measured viscosity of 153 cP, and the IE7 example has a measured viscosity of 356 cP. IE8 is another embodiment of the invention using dispersant 1 as a phosphate ester and 25 mol% triisopropanolamine (TIPA) as an alkanolamine. When compared with examples CE1 and CE2, the IE8 example effectively reduces the viscosity of the LFP precursor slurry. For example, CE1 has a measured viscosity of 802 cP, and CE2 has a measured viscosity of 1096 cP, while the IE8 example has a measured viscosity of 226 cP. IE9 and IE10 are embodiments of the invention with varying ratios of phosphate ester dispersant 1. When the composition of phosphate ester dispersant 1 is changed from 3.2 wt% to 0.8 wt% (relative to the amount of active material (FePO4 + Li2CO3)), the IE9 and IE10 examples still effectively reduce the LFP viscosity compared to CE1. For example, CE1 has a measured viscosity of 802 cP, while the IE9 embodiment has a measured viscosity of 668 cP, and the IE10 embodiment has a measured viscosity of 594 cP.IE11 and IE12 are embodiments of the invention that vary the type of phosphate ester used. In these cases, dispersant 2 is used with different types of amines at a ratio of 3.2% by weight. When compared with embodiments CE1 and CE2, embodiments IE11 and IE12 effectively reduce the viscosity of the LFP precursor slurry. For example, CE1 has a measured viscosity of 802 cP, and CE2 has a measured viscosity of 1096 cP, while embodiment IE11 has a measured viscosity of 612 cP, and embodiment IE12 has a measured viscosity of 532 cP.

Claims

1. A lithium iron phosphate slurry, the lithium iron phosphate slurry comprising: Iron compounds; Lithium compounds; Dispersant of Formula I: Formula I In Formula I, n is an integer from 1 to 10, and R1 of Formula I is selected from the group consisting of hydrogen, C8 to C18 alkylphenyl groups, straight-chain or branched primary or secondary C1 to C18 alkyl chains, and R2 of Formula I is selected from the group consisting of hydrogen, methyl groups, ethyl groups, or combinations thereof; and Alkylamines of Formula II: Formula II In formula II, R1, R2, and R3 are independently selected from hydrogen or hydroxyalkyl groups having one to four carbons.

2. The lithium iron phosphate slurry according to claim 1, wherein, based on the total weight of the lithium iron phosphate slurry, the solid content of the iron compound and the lithium compound is greater than 50% by weight (wt.%) of the lithium iron phosphate slurry, and the lithium iron phosphate slurry has a viscosity of about 200 centipoise (cP) to about 700 cP.

3. The lithium iron phosphate slurry according to any one of claims 1 to 2, wherein the iron compound is iron phosphate (FePO4) and the lithium compound is lithium carbonate (Li2CO3).

4. The lithium iron phosphate slurry according to any one of claims 1 to 3, wherein the lithium iron phosphate slurry contains glucose as a carbon source.

5. The lithium iron phosphate slurry according to any one of claims 1 to 4, wherein the dispersant of formula I and the alkanolamine of formula II are combined with the iron compound, the lithium compound and water to form an aqueous mixture.

6. The lithium iron phosphate slurry according to any one of claims 1 to 5, wherein the dispersant accounts for 0.8% to 4.0% by weight of the total weight of the iron compound and the lithium compound.

7. The lithium iron phosphate slurry according to any one of claims 1 to 6, wherein the alkanolamine is present in the slurry at a molar amount of 10 mol% to 120 mol% of the P(OH) site of the dispersant of formula I.

8. The lithium iron phosphate slurry according to any one of claims 1 to 6, wherein the R1 of the dispersant of formula I is selected from alkylphenyl groups, straight-chain or branched groups, and primary or secondary alkyl chain groups having a total of 12 to 14 carbon atoms.

9. The lithium iron phosphate slurry according to any one of claims 1 to 8, wherein the molar ratio of lithium, iron and phosphorus in the lithium iron phosphate slurry is approximately 1:1:

1.

10. A method, the method comprising: The production of lithium iron phosphate slurry includes: The mixture contains iron and lithium compounds, water, and a carbon source of more than 40% by weight of the lithium iron phosphate slurry. Dispersant of compound I: Equation I In Formula I, n is an integer from 1 to 10, and R1 of Formula I is selected from the group consisting of hydrogen, C8 to C18 alkylphenyl groups, straight-chain or branched primary or secondary C1 to C18 alkyl chains, and R2 of Formula I is selected from the group consisting of hydrogen, methyl groups, ethyl groups, or combinations thereof; and Alkylamines of compound II: Formula II In formula II, R1, R2 and R3 are independently selected from hydrogen or hydroxyalkyl groups having one to four carbons; When the viscosity of the lithium iron phosphate slurry is less than 400 centipoise (cP), the lithium iron phosphate slurry is subjected to a spray drying process; and The lithium iron phosphate mixture is calcined.

11. The method of claim 10, wherein the iron compound is iron phosphate (FePO4) and the lithium compound is lithium carbonate (Li2CO3).

12. The method according to any one of claims 10 to 11, wherein the composition of the dispersant of formula I is in the range of 0.8 wt% to 4.0 wt% relative to the total amount of active material comprising the iron phosphate (FePO4) and the lithium carbonate (Li2CO3), and the composition of the alkanolamine of formula II is in the range of 10 mol% to 120 mol% relative to the molar amount of P(OH) sites in the dispersant of formula I.

13. The method according to any one of claims 10 to 12, wherein the weight percentage of said iron phosphate (FePO4) and said lithium carbonate (Li2CO3) is greater than 45% by weight of said lithium iron phosphate slurry, and the viscosity of said lithium iron phosphate slurry is less than 200 cP.

14. The method according to any one of claims 10 to 13, wherein the carbon source is glucose.

15. The method according to any one of claims 10 to 14, wherein R1 of the dispersant of formula I is one of octylphenyl or nonylphenyl.

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