KR20210080088A - Lithium phosphates and method of preparing thereof - Google Patents

Abstract

The present invention provides lithium phosphate and a manufacturing method thereof. In the lithium phosphate according to an embodiment of the present invention, a difference between D10 and D90 is 30 μm or less, and D10 is 13 μm or more. According to the method, it is possible to manufacture the lithium phosphate having a low water content from brine and not having a large particle size difference.

Description

Lithium phosphate and manufacturing method thereof

The present invention relates to lithium phosphate and a method for preparing lithium phosphate thereof. More specifically, it relates to a method for producing lithium phosphate having a low water content from brine and not having a large particle size difference.

Recently, as lithium secondary batteries are rapidly growing in the field of electronic communication devices such as tablet PCs and smart phones, and further, the application fields of electric vehicles are expanding, research and development efforts to increase energy storage capacity are becoming more concrete. Due to the increase in the lithium secondary battery market, the amount of lithium (Li), which is a major raw material for a cathode material, is gradually increasing.

Sources of lithium include mineral, brine, and sea water. Among them, the minerals are spodumene, petalite, and lepidolite, and lithium is contained in a relatively large amount of about 1 to 1.5% by weight. However, in order to extract lithium from minerals, it has to go through processes such as flotation, high-temperature heating, pulverization, acid mixing, extraction, refining, concentration, and precipitation, so the recovery procedure is complicated and expensive due to high energy consumption. There is a problem in that environmental pollution becomes severe by using acid in the process of extracting lithium.

Currently, lithium is mainly extracted from brine, which is produced from a natural salt lake, and _{salts such as lithium, Mg, Ca, B, Na, K, SO 4} are dissolved together.

Meanwhile, various attempts have been made to effectively recover lithium (Li) from such brine. As a known technique, there is a technique for synthesizing _{Li 3} PO ₄ in order to effectively separate Na and Li ions from brine to recover high-yield, high-purity Li.

However, in the process of recovering lithium from brine through _{Li 3} PO _{4 synthesis, the amount of water due to the properties of the particles of Li 3} PO ₄ , in particular, the powder properties such as particle size and specific surface area, and the amount of water dissolved therein There is a problem in that an additional washing process must be performed by adsorption of ions such as Na and K and crystallization occurring during drying.

The present invention provides lithium phosphate and a method for preparing the same. More specifically, there is provided a method for producing lithium phosphate having a low water content from brine and not having a large particle size difference.

In lithium phosphate according to an embodiment of the present invention, the difference between D10 and D90 is 30 μm or less, and D10 is 13 μm or more.

The specific surface area of the lithium phosphate may be 1.3 m 2 /g or less.

A method for manufacturing lithium phosphate according to an embodiment of the present invention includes preparing a raw material composition including a lithium-containing solution and a phosphorus supply material; controlling the pH of the raw material composition to 5 to 7 to generate lithium phosphate nuclear particles; and increasing the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles.

The step of generating lithium phosphate nuclear particles by controlling the pH of the raw material composition to 5 to 7; is to be performed by adding a separate lithium-containing solution, a separate phosphorus supply material, and an alkali material to the raw material composition can

The step of increasing the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles; may be performed by adding a separate alkali material to the raw material composition.

In the step of preparing a raw material composition including a lithium-containing solution and a phosphorus supply material, a molar ratio of Li and P in the raw material composition may be 5:1 to 2:1.

Controlling the pH of the raw material composition to 5 to 7 to generate lithium phosphate nuclear particles; the input time may be 10 to 60 minutes.

controlling the pH of the raw material composition to 5 to 7 to generate lithium phosphate nuclear particles; The subsequent holding time may be 10 minutes or less.

The step of increasing the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles; may be to control the pH of the raw material composition to 11.5 to 12.

Increasing the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles; the input time may be 5 minutes or more.

increasing the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles; The subsequent holding time may be 30 minutes or more.

The lithium containing solution may be brine.

The phosphorus source material may be phosphoric acid, a phosphate salt, an aqueous phosphoric acid solution, or a combination thereof.

The alkali material may be NaOH.

The lithium phosphate manufacturing method according to an embodiment of the present invention can produce lithium phosphate particles with a high yield.

The lithium phosphate manufacturing method according to an embodiment of the present invention may produce lithium phosphate particles having a low moisture content.

The lithium phosphate manufacturing method according to an embodiment of the present invention can produce lithium phosphate particles having a small difference in particle size and size.

1 is a schematic diagram of a method for manufacturing lithium phosphate according to an embodiment of the present invention.
2 is a 3000-fold SEM image of lithium phosphate particles prepared according to Example 1 of the present invention.
3 is a 3000-fold SEM image of lithium phosphate particles prepared according to Example 2 of the present invention.
4 is a 3000-fold SEM image of lithium phosphate particles prepared according to Example 3 of the present invention.
5 is a 3000-fold SEM image of lithium phosphate particles prepared according to Example 3 of the present invention.
6 is a 3000-fold SEM image of lithium phosphate particles prepared according to Comparative Example 1 of the present invention.
7 is a 3000-fold SEM image of lithium phosphate particles prepared in Comparative Example 2 of the present invention.
8 is a 3000-fold SEM image of lithium phosphate particles prepared according to Comparative Example 3 of the present invention.
9 is a 3000-fold SEM image of lithium phosphate particles prepared according to Comparative Example 4 of the present invention.

In this specification, terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are used only to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

In the present specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

In this specification, the terminology used is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising," as used herein, specifies a particular characteristic, region, integer, step, operation, element and/or component, and includes the presence or absence of another characteristic, region, integer, step, operation, element and/or component. It does not exclude additions.

In the present specification, the term "combination of these" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, and the components It means to include one or more selected from the group consisting of.

In this specification, when a part is referred to as being “on” or “on” another part, it may be directly on or on the other part, or the other part may be accompanied in between. In contrast, when a part refers to being "directly above" another part, the other part is not interposed therebetween.

Although not defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Commonly used terms defined in the dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and unless defined, they are not interpreted in an ideal or very formal meaning.

In addition, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

In an embodiment of the present invention, the meaning of further including the additional element means that the remaining iron (Fe) is included by replacing the additional amount of the additional element.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

The method for producing lithium phosphate according to an embodiment of the present invention controls the size and pore characteristics of the generated particles by controlling the reaction input sequence, speed, and pH of the reaction system, thereby reducing the water content of lithium phosphate particles. suggest a way The present invention proposes a method for controlling the pH of the reaction solution by dividing it into two major steps. Basically, it is based on preparing an acidic solution in which brine and a phosphorus supply material are first mixed, and then reacting with an alkali material such as NaOH to induce a precipitation reaction. At this time, in an embodiment of the present invention, a multi-step pH range is performed. That is, a raw material composition including a lithium-containing solution and a phosphorus supply material is prepared, the pH of the raw material composition ^{is controlled to 5 to 7 (1 st} target pH), lithium phosphate nucleus particles are generated, and then the raw material composition is By increasing the pH (2 ^nd target pH), lithium phosphate core particles are grown to obtain lithium phosphate particles, and finally lithium phosphate having a low moisture content is prepared. The particle size and precipitation reaction rate are controlled while going through the multi-step pH range. In this reaction, a precipitate starts to form from pH 4, and in a low pH region, a reaction that forms a seed of the precipitate and a dissolution reaction occur competitively. As the pH increases, the rate of the lithium phosphate formation reaction proceeds rapidly, and the seed formation occurs rapidly, and the aggregation rate of small particles tends to proceed rapidly. In an embodiment of the present invention, the particle size is controlled by using the reaction rate difference according to the pH range, and thus lithium phosphate having a low moisture content is manufactured.

A method for manufacturing lithium phosphate according to an embodiment of the present invention includes preparing a raw material composition including a lithium-containing solution and a phosphorus supply material; controlling the pH of the raw material composition to 5 to 7 to generate lithium phosphate nuclear particles; and increasing the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles.

1 schematically shows a method for manufacturing lithium phosphate according to an embodiment of the present invention.

First, a raw material composition including a lithium-containing solution and a phosphorus supply material is prepared. Step 1 is to pre-inject the raw material composition into the reaction vessel.

The lithium-containing solution in the raw material composition may be brine. More specifically, the Li content may be 4.0 g/L or more, and the Na content may be brine having a concentration of 98 g/L or more. More specifically, the Ca content may be 0.1 g/L or less, and the Mg content may be brine having a concentration of 0.1 g/L or less.

The phosphorus source material may be phosphoric acid, a phosphate salt, an aqueous phosphoric acid solution, or a combination thereof. More specifically, the phosphorus feed material may be an aqueous solution of 75% by weight phosphoric acid.

In the raw material composition, the volume ratio of the lithium-containing solution and the phosphorus-supplying material may be 30:1 to 70:1 when the concentration of Li in the lithium-containing solution is 4 g/L and the phosphorus-supplying material is 75% by weight of an aqueous phosphoric acid solution. More specifically, it may be 40:1 to 60:1. More specifically, it may be 50:1.

The molar ratio of Li and P in the raw material composition may be 5:1 to 2:1. More specifically, it may be 4:1 to 3:1.

The amount of the raw material composition may be 300 to 700 ml. More specifically, it may be 400 to 600 ml.

Thereafter, by controlling the pH of the raw material composition to 5 to 7, a step of generating lithium phosphate nucleus particles is performed. This can be called Step 2. More specifically, it may be carried out by a method of adding a separate lithium-containing solution, a separate phosphorus supply material, and an alkali material to the raw material composition.

The lithium containing solution at this stage may be brine. More specifically, the Li content may be 4.0 g/L or more, and the Na content may be brine having a concentration of 98 g/L or more. More specifically, the Ca content may be 0.1 g/L or less, and the Mg content may be brine having a concentration of 0.1 g/L or less.

The phosphorus source material may include phosphoric acid, a phosphate salt, an aqueous phosphoric acid solution, or a combination thereof. More specifically, the phosphorus feed material may be an aqueous solution of 75% by weight phosphoric acid.

In this step, a mixture of a separate lithium-containing solution and a separate phosphorus supply material may be separately prepared, and an alkali material may be prepared separately.

The volume ratio of the lithium-containing solution and the phosphorus source material in the mixture may be 30:1 to 70:1 when the concentration of Li in the lithium-containing solution is 4 g/L and the phosphorus source material is an aqueous solution of phosphoric acid of 75% by weight. More specifically, it may be 40:1 to 60:1. More specifically, it may be 50:1.

The molar ratio of Li and P in the mixture may be 5:1 to 2:1. More specifically, it may be 4:1 to 3:1.

A mixture of the raw material composition including the lithium-containing solution of Step 1 and the phosphorus-supplying material, the separate lithium-containing solution of Step 2, and the separate phosphorus-supplying material may be the same solution.

The alkali material may be NaOH.

The amount of the mixture of the lithium-containing solution and the phosphorus supply material in this step may be 1300 to 1700 ml. More specifically, it may be 1500 to 1600ml.

The amount of the alkali substance in this step may be 30 to 70 ml. More specifically, it may be 40 to 60 ml.

In this step, the volume ratio of the lithium-containing solution and the mixture of the phosphorus supply material and the alkali material may be 40:1 to 20:1. More specifically, it may be 35:1 to 25:1.

In this step, the input time of a separate lithium-containing material, a separate phosphorus supply material, and an alkali material may be 10 to 60 minutes. More specifically, it may be 20 to 50 minutes. More specifically, it may be 30 minutes.

In conclusion, this step is a step of generating lithium phosphate nuclear particles by controlling the pH of the raw material composition to 5 to 7, and pH 5 to 7 may be the ^{1st target pH in the present invention.} A mixture of each solution, a separate lithium-containing solution, and a separate phosphorus feed material, to maintain the ^{1 st} target pH at this stage; and an alkali substance; it is possible to control the input speed of the metering pump. 1 ^st target pH may be 5 to 6 more specifically.

controlling the pH of the raw material composition to 5 to 7 to generate lithium phosphate nuclear particles; The subsequent holding time may be 50 minutes or less. That is, the raw material composition controlled to pH 5 to 7 may be maintained for 50 minutes or less. More specifically, the holding time may be 40 minutes or less, more specifically, it may be 10 minutes or less, and more specifically, there may be no holding time.

Thereafter, the pH of the raw material composition is increased to grow lithium phosphate core particles to obtain lithium phosphate particles. This can be called Step 3. More specifically, this step may be performed by adding a separate alkali material to the raw material composition. In addition, it may be to control the pH of the raw material composition to 11.5 to 12.

The alkali material may be NaOH.

This step is there to conclusion additionally added an alkaline substance to be a step of controlling the pH of the raw material composition to 11.5 to 12, and pH is 11.5 to 12 may be a 2 ^nd target pH in the present invention.

The input time of the alkali material may be 5 minutes or more. More specifically, it may be 10 minutes or more, and more specifically, it may be 1 hour or more. That is, the alkali material may be introduced at a low speed.

After the step of increasing the pH of the raw material composition to obtain lithium phosphate particles by growing lithium phosphate core particles, the holding time may be set to 30 minutes or more. This can be referred to as Step 4. 2 after reaching the target pH ^nd to get complete and the reaction holding time. More specifically, the holding time may be 40 minutes or more. More specifically, it may be 50 minutes or longer.

Thereafter, lithium phosphate powder can be obtained through a filtration process for the lithium phosphate slurry (LP Slurry) prepared as Step 5. In the filtration process applied in these Examples, solid-liquid separation was performed using an aspirator connected to a vacuum pump. However, the solid-liquid separation process is not limited to the above equipment, and a filter press or a centrifuge may be applied.

In the lithium phosphate particles prepared according to an embodiment of the present invention, the difference between D10 and D90 is 30 μm or less, and D10 is 13 μm or more. That is, the difference in particle size between D10 and D90 is not large, and the particle size of D10 is small. In the lithium phosphate particle size distribution, if the difference between D10 and D90 is large, lithium phosphate particles having a small particle size are located between lithium phosphate particles having a large particle size, thereby increasing the specific surface area of the total lithium phosphate. The large total lithium phosphate specific surface area means that the moisture content can be high. The lithium phosphate production method according to an embodiment of the present invention to adjust the pH to a multi-level, in the initial 1 ^st target pH of pH 5 to 7 and quickly produce a lithium phosphate core particle, 2 ^nd target pH of pH 11.5 to 12 The lithium phosphate particle size distribution can be controlled by slowly growing lithium phosphate nucleus particles. That is, the difference between D10 and D90 is not large, and the size of D10 can be adjusted to be large. Therefore, it is possible to lower the specific surface area of the entire lithium phosphate, and thereby lower the moisture content of the lithium phosphate cake. If the moisture content of the lithium phosphate cake is low, the content of elements such as K, Na, and B that may remain in the final product by being present in the water may be small. More specifically, the difference between D10 and D90 may be 24 μm or less, and more specifically, 20 μm or less. D10 may be 18 μm or more, and more specifically, 19 μm or more.

The specific surface area of the lithium phosphate according to an embodiment of the present invention may be 1.5 m 2 /g or less. More specifically, it may be 1.3 m 2 /g or less.

The moisture content of the lithium phosphate cake prepared according to an embodiment of the present invention may be 17% or less. More specifically, it may be 15% or less, and more specifically, it may be 12.5% by weight or less.

Lithium phosphate according to an embodiment of the present invention by weight%, Na: 4% or less (not including 0), K: 1% or less (not including 0), and B: 0.38% or less (0 not included) may be included.

Lithium phosphate according to an embodiment of the present invention may have a D50 of 15 μm or more.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for illustrating the present invention, and the present invention is not limited thereto.

Example

1. Preparation of raw materials

A brine having the composition of Table 1 below was prepared. The following brine is a solution that has been subjected to a process of precipitating Ca and Mg components in the form of hydroxide or carbonate through constant pH control and removing them through solid-liquid separation. At this time, the composition of the components of Ca and Mg is not fixed to the following values, and the method of the removal process is not limited to specific conditions.

element Concentration (g/L) Li 4.25 S 1.99 P 0.00 Ca 0.08 Mg 0.02 K 38.74 B 0.88 Na 98.97

As an auxiliary material used in the process of manufacturing lithium phosphate (Li ₃ PO ₄ ), 45 wt% of NaOH and 75 wt% of H ₃ PO ₄ aqueous solution were used. As a reaction solution in Examples and Comparative Examples of the present invention, a mixture of brine and 75 wt% phosphoric acid aqueous solution was prepared, and 45 wt% NaOH was also prepared separately. The compositions of the solutions used in Examples and Comparative Examples of the present invention are shown in Table 2 below.

Input solution A Input solution B Input solution C Furtherance Volume (ml) Furtherance Volume (ml) Furtherance Volume (ml) Examples 1,2,3,4 75% phosphoric acid: brine
(volume ratio 1:50) 500 75% phosphoric acid: brine
(volume ratio 1:50) 1540 NaOH
45%
solution 90 Comparative Example 1 75% phosphoric acid: brine (volume ratio 1:50) 500 75% phosphoric acid: brine
(volume ratio 1:50) 1540 90 Comparative Example 2 45% NaOH aqueous solution 50 75% phosphoric acid: brine
(volume ratio 1:50) 2040 40 Comparative Example 3 75% phosphoric acid: brine
(volume ratio 1:50) 2040 - - 90 Comparative Example 4 brine 2000 75% aqueous phosphoric acid solution 40 90

In the composition of Table 2, a mixed solution of brine and phosphoric acid in solution A and solution B was prepared by mixing in a volume ratio of 50:1. At this time, the stirring process is accompanied and the stirring time lasts about 30 minutes. When the solution A is a mixture of 75% by weight phosphoric acid and brine, Li ₃ PO ₄ is temporarily generated during the manufacturing process, but it is dissolved again into a solution because the pH of the prepared solution is 0.7 level, resulting in a transparent solution can be obtained. Preparation of a mixture of 75 wt% phosphoric acid and brine (which can be either Solution A or Solution B) is obtained as a clear solution by stirring 2 L of brine and 40 mL of 75 wt% phosphoric acid in a beaker for 30 minutes using a magnetic stirrer. could The ratio of Li and P in this mixed solution is shown in Table 3 below.

element Concentration (g/l) Solution volume (L) Elemental mass in mixed solution Li mol Li:P molar ratio Li 4.16 2 8.32 1.20 3:1.12 P 370.67 0.04 14.8268 0.48

2. Preparation of lithium phosphate

1) Examples

Lithium phosphate production in Examples of the present invention was carried out as follows. First, solution A (a mixed solution of brine and 75 wt% phosphoric acid) was first introduced into the reactor. Thereafter, the same solution as Solution A, Solution B (a mixed solution of brine and 75 wt% phosphoric acid) and Solution C (45 wt% NaOH aqueous solution) were added to the reactor using a metering pump.

The volume in each Example, the target pH in each step, the input time, the holding time, etc. are shown in Table 4 below.

Step 1 Step 2 Step 3 Step 4 solution A
volume
(ml) Early
pH solution B
volume
(ml) solution C
volume
(ml) 1 ^st
Target
pH input
time
(min) maintain
time
(min) solution C
volume
(ml) 2nd Target pH Dosing time (min) Target
pH
range maintain
time
(hr) Example 1 500 0.7 1540 45 5-6 30 - 45 11.5~12 60 11.5~12 One Example 2 500 0.7 1540 55 6-7 30 30 35 11.5~12 10 11.5~12 One Example 3 500 0.7 1540 45 5-6 30 30 45 11.5~12 10 11.5~12 One Example 4 500 0.7 1540 45 5-6 50 60 45 11.5~12 10 11.5~12 One

In Example 1, 500ml of a solution (solution A) in which a mixed solution of brine and 75 wt% phosphoric acid was fixed in a ratio of 50:1 by volume in Step 1 was first put into the reaction vessel. In Step 2, 1540 ml of solution B and 45 ml of solution C were added to the same brine and phosphoric acid mixture as in solution A (solution B) and a 45 wt% aqueous solution of NaOH (solution C) using a metering pump, respectively. The input time was 30 minutes, and there was no separate holding time. At this time, the 1 ^st target pH was 5-6. In Step 3 it was to reach the 2 ^nd target pH of 11.5 to 12 by introducing an additional 45ml NaOH 45% by weight aqueous solution (Solution C). In Step 4, after reaching the 2 ^nd target pH of 11.5 to 12. The reaction was completed by maintaining for a predetermined time. In Step 5, lithium phosphate powder was obtained through a filtration process for the prepared lithium phosphate slurry (LP Slurry). In the filtration process applied at this time, solid-liquid separation was performed using an aspirator connected to a vacuum pump. However, the solid-liquid separation process is not limited to the above equipment, and a filter press or a centrifuge may be applied. The cake containing moisture thus obtained was dried at 100°C for 10 hours or more to remove moisture.

That is, Example 1 is characterized in that the solution B (brine and 75 wt% phosphoric acid mixed solution) and solution C (45 wt% NaOH aqueous solution) are added so that the pH can be maintained in the range of 5 to 6 in Step 2, It is characterized in that there is no separate holding time. In addition, in Step 3, it is characterized in that the rate is adjusted so that the additionally added solution C (45 wt% NaOH aqueous solution) can be added for 1 hour. The purpose of adjusting the pH and input time in Step 2 and Step 3 is to induce a seeding reaction in the lowest pH region to lower the aggregation rate of the seed particles formed through the precipitation reaction and induce a growth reaction in which the size of the particles grows. it is for

In Example 2 ^{, it is characterized in that the 1 st} target pH is 6 to 7. In Step 2, unlike Example 1, it is characterized in that the holding time is set to 30 minutes. In Step 3, it is characterized in that the input time of solution C (45 wt% NaOH aqueous solution) is 10 minutes.

In Example 3, unlike Example 1, the holding time in Step 2 is set to 30 minutes. In Step 3, the input time of solution C (45 wt% NaOH aqueous solution) was set to 10 minutes, and the remaining conditions were the same as in Example 1.

In Example 4, unlike Example 1, the holding time of Step 2 was 1 hour, and the NaOH input time of Step 3 was 10 minutes.

2) Comparative Example

In the comparative example of the present invention, the order of input of the solutions is different, and the 1 ^st target pH and the holding time of Step 2 are different as compared with the Example.

The volume in each comparative example, the target pH in each step, the input time, the holding time, etc. are shown in Table 5 below.

Step 1 Step 2 Step 3 Step 4 solution A
volume
(ml) Early
pH solution B
volume
(ml) solution C
volume
(ml) 1 ^st
Target
pH input
time
(min) maintain
time
(min) solution C
volume
(ml) 2nd Target pH Dosing time (min) Target
pH
range maintain
time
(hr) Comparative Example 1 500 0.7 1540 70 8-10 30 30 20 11.5~12 10 11.5~12 One Comparative Example 2 50 12.7 2040 20 8-10 30 30 40 11.5~12 10 11.5~12 One Comparative Example 3 2040 1.3 - 70 8-10 50 30 20 11.5~12 10 11.5~12 One Comparative Example 4 2000 11.5 40 45 5-6 15 30 45 11.5~12 10 11.5~12 One

In Comparative Example 1, unlike Example 1, ^{the range of 1 st} target pH is 8 to 10.

In Comparative Example 2, unlike Examples 1 to 3, the type of solution A pre-injected into the reactor was a 45 wt% NaOH aqueous solution. Therefore, the initial pH value is 12.7, which is different. In addition, ^{the range of 1st} target pH is 8-10.

In Comparative Example 3, the amount of solution A (a mixed solution of brine and 75 wt% phosphoric acid) was 2050 ml, which is different from the examples. In Examples, an amount corresponding to the total amount of solution A and solution C was added in Step 1. In Step 2, only solution C (45 wt% NaOH aqueous solution) was added, and the ^1st target pH was maintained at 8 to 10.

In Comparative Example 4, unlike the Examples, the solution A in Step 1 was only brine. In addition, in Step 2, solution C was only used as a 75 wt% aqueous solution of phosphoric acid, and the input time was 15 minutes, and the reaction holding time was 30 minutes. In Step 3, the input time of solution C (45 wt% NaOH aqueous solution) was 10 minutes.

3. Experimental results

The main test results of Examples 1 to 4 and Comparative Examples 1 to 4 are as follows.

1) Moisture content and cake recovery rate in the washing process

Table 6 below shows the data of the filtrate obtained in the filtration process after the lithium phosphate manufacturing process, the Li ₃ PO ₄ Cake content, and the water content confirmed in the drying process.

In the case of the Examples, it was possible to confirm the moisture content of 17% or less. This confirms that the characteristics of the lithium phosphate particles obtained under the manufacturing conditions of Examples have powder characteristics that can contain less moisture.

filtrate volume
(ml) filtrate mass
(g) Cake mass
(g) Cake moisture content
(%) Function volume in Cake
(ml) Comparative Example 1 2080 2532.3 68.46 18.7 10.5 Comparative Example 2 2052 2491.6 76.14 25.2 15.8 Comparative Example 3 2048 2485.0 82.67 27.7 18.9 Comparative Example 4 2058 2497.4 68.03 20.5 11.5 Example 1 2100 2563.7 59.70 12.0 5.9 Example 2 2070 2514.4 59.28 14.97 7.3 Example 3 2066 2510.4 56.28 12.8 5.9 Example 4 2062 2508.1 62 16.8 8.5

Table 7 shows the recovery rate of the prepared cake after the cleaning process. The washing process of lithium phosphate cake was carried out by stirring 10 g of lithium phosphate cake with 30 g of deionized water from which ions were removed for 1 hour. The cake recovery rate after the washing process was calculated based on the moisture content of the cake obtained by filtration after washing. After the washing process, a drying process was performed, and the cake recovery rate after the drying process was calculated based on the moisture content of the cake after drying. The cake recovery rate was calculated by subtracting the moisture content from 100% (Cake recovery rate = 100 - Cake moisture content).

After LP Cake filtration
Cake recovery
(weight%) after washing process
Cake recovery
(weight%) after drying process
Final Cake Recovery
(weight%) Comparative Example 1 81.33 77.05 62.7 Comparative Example 2 74.83 66.96 50.1 Comparative Example 3 72.29 65.53 47.4 Comparative Example 4 79.49 68.91 54.8 Example 1 87.98 78.39 69.0 Example 2 85.03 74.58 63.4 Example 3 87.20 76.22 66.5 Example 4 83.25 74.81 62.3

2) Composition and physical properties of lithium phosphate powder

Table 8 below shows the results of solid ICP analysis of the dried lithium phosphate powders of Examples and Comparative Examples of the present invention. It can be seen that the content of elements such as K, Na, and B of the samples of Examples is relatively low compared to Comparative Examples. Elements such as K, Na and B are elements derived from brine in water contained in lithium phosphate before drying.

LP Cake composition (wt%) Li S P Ca Mg K B Na Comparative Example 1 14.78 0.17 22.77 0.28 0.79 0.77 0.48 4.44 Comparative Example 2 14.56 0.27 22.05 0.28 0.54 1.39 0.43 5.09 Comparative Example 3 14.31 0.20 21.68 0.27 0.23 1.64 0.29 6.02 Comparative Example 4 14.59 0.23 22.46 0.29 1.25 1.17 0.38 4.77 Example 1 15.09 0.18 24.04 0.30 1.85 0.69 0.37 3.50 Example 2 14.99 0.20 23.41 0.31 0.19 0.97 0.37 3.71 Example 3 15.63 0.18 24.39 0.32 0.54 0.65 0.34 3.09 Example 4 14.86 0.20 23.10 0.30 1.23 0.89 0.40 4.11

Table 9 below compares the particle size and specific surface area of the obtained lithium phosphate particles. As a result of comparing the size, specific surface area, and pore volume of the particles prepared in the Example and Comparative Example conditions, the particles of the Example have a larger particle size, a lower specific surface area, and a lower pore volume than the particles of the Comparative Example. was able to confirm that This can be seen as a result that proves that the particle size change is possible through the pH control for each step, which was intended in the present invention. In this case, the specific surface area and the pore volume were measured using the ASAP2020 product of Micromeritics, and the BET surface area and the pore volume in the DFT method were measured. This measurement method was measured through the N2 adsorption/desorption method after pretreatment through vacuum heat treatment at 400° C. for 8 hours with reference to the routinely published specific surface area measurement method.

particle size distribution Specific surface area and pore properties SD
(μm) D10
(μm) D50
(μm) D90
(μm) D90 - D10 BET specific surface area (m ² /g) pore volume
(For diameters less than 11.79 Å)
(cm ³ /g) pore volume
(For diameters less than 1720.79Å)
(cm ³ /g) Comparative Example 1 12.6 20.2 34.3 52.2 32.0 1.32 0.00002 0.0049 Comparative Example 2 5.1 7.7 13.7 20.6 12.9 2.81 0.00038 0.0227 Comparative Example 3 16.9 5.1 16.5 43.3 38.2 1.58 0.00009 0.0061 Comparative Example 4 9.0 9.0 21.3 32.2 23.2 2.04 0.00012 0.0136 Example 1 7.6 19.5 28.9 38.9 19.4 0.82 0 0.0020 Example 2 9.3 24.3 36.2 47.7 23.4 1.07 0 0.0011 Example 3 8.7 22.6 34.0 44.8 22.2 0.76 0.00018 0.0070 Comparative Example 4 8.6 18.9 28.8 40.8 21.9 0.85 0.00014 0.0084

3) Observation of the morphology of lithium phosphate particles

SEM images of the lithium phosphate particles prepared in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in FIGS. 2 to 9 .

2 is a 3000-fold SEM image of lithium phosphate particles prepared according to Example 1 of the present invention. 3 is a 3000-fold SEM image of lithium phosphate particles prepared according to Example 2 of the present invention. 4 is a 3000-fold SEM image of lithium phosphate particles prepared according to Example 3 of the present invention. 5 is a 3000-fold SEM image of lithium phosphate particles prepared according to Example 4 of the present invention.

6 is a 3000-fold SEM image of lithium phosphate particles prepared according to Comparative Example 1 of the present invention. 7 is a 3000-fold SEM image of lithium phosphate particles prepared in Comparative Example 2 of the present invention. 8 is a 3000-fold SEM image of lithium phosphate particles prepared according to Comparative Example 3 of the present invention. 9 is a 3000-fold SEM image of lithium phosphate particles prepared according to Comparative Example 4 of the present invention.

It was confirmed that the particles of Examples 1 to 4 were more dense and larger than the particles of Comparative Examples 1 to 4, and were consistent with the BET specific surface area and particle size data of Table 9 above. In particular, in the case of Example 1, it was confirmed that the final particle as well as the size or density of the primary particles constituting the final particle can exhibit a low moisture content structure.

The present invention is not limited to the embodiments, but may be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains may develop other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (14)

The difference between D10 and D90 is 30 μm or less,
D10 is 13 μm or more,
lithium phosphate.
According to claim 1,
Lithium phosphate having a specific surface area of 1.3 m 2 /g or less.
preparing a raw material composition including a lithium-containing solution and a phosphorus supply material;
generating lithium phosphate nuclear particles by controlling the pH of the raw material composition to 5 to 7; and
increasing the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles;
Lithium phosphate manufacturing method comprising a.
4. The method of claim 3,
generating lithium phosphate nuclear particles by controlling the pH of the raw material composition to 5 to 7;
A method for producing lithium phosphate, which is performed by adding a separate lithium-containing solution, a separate phosphorus supply material, and an alkali material to the raw material composition.
4. The method of claim 3,
raising the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles;
A method for producing lithium phosphate, which is performed by adding a separate alkali material to the raw material composition.
4. The method of claim 3,
Preparing a raw material composition comprising the lithium-containing solution and a phosphorus supply material; In,
A method for producing lithium phosphate wherein the molar ratio of Li and P in the raw material composition is 5: 1 to 2: 1.
4. The method of claim 3,
Controlling the pH of the raw material composition to 5 to 7 to generate lithium phosphate core particles; the input time of the lithium phosphate manufacturing method is 10 to 60 minutes.
4. The method of claim 3,
generating lithium phosphate nuclear particles by controlling the pH of the raw material composition to 5 to 7; Thereafter, the holding time is 10 minutes or less.
4. The method of claim 3,
raising the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles;
A method for producing lithium phosphate by controlling the pH of the raw material composition to 11.5 to 12.
4. The method of claim 3,
Increasing the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles; the input time of the lithium phosphate manufacturing method is 5 minutes or more.
4. The method of claim 3,
increasing the pH of the raw material composition to grow lithium phosphate core particles to obtain lithium phosphate particles; The subsequent holding time is a method for producing lithium phosphate that is 30 minutes or more.
5. The method of claim 3 or 4,
The lithium-containing solution is a brine method for producing lithium phosphate.
5. The method of claim 3 or 4,
The phosphorus supply material is phosphoric acid, a phosphate salt, an aqueous phosphoric acid solution, or a combination thereof.
6. The method according to claim 4 or 5,
The method for producing lithium phosphate, wherein the alkali material is NaOH.

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