KR101650979B1 - Apparatus for continuous hydrothermal synthesis process in super critical condition using switching of mixer - Google Patents

Abstract

The present invention relates to a supercritical continuous hydrothermal synthesis apparatus. The present invention relates to a pre-mixer in which iron (Fe) / phosphorus (P) solution and lithium (Li) solution are separately introduced; And two main mixers into which a mixed solution of an iron / phosphorus solution and a lithium solution is charged and a supercritical water is added and stirred with a mixed solution of the iron / phosphorus solution and the lithium solution, wherein the two main mixers are at least one Or more can be selectively controlled. According to the present invention, two main mixers are arranged in parallel and controlled so that they can be switched to each other, so that even if the pressure in one main mixer is increased, the process can be continuously performed while maintaining synthesis in another main mixer.

Description

[0001] The present invention relates to a supercritical continuous hydrothermal synthesis apparatus using a mixer,

The present invention relates to a supercritical continuous hydrothermal synthesis apparatus, and more particularly, to a supercritical continuous hydrothermal synthesis apparatus in which two main mixers can be switched to each other so that stable continuous synthesis and easy maintenance are facilitated.

As the development and demand for portable electronic devices such as mobile devices have increased, the demand for secondary batteries as energy sources has been rapidly increasing. Among these secondary batteries, high energy density and voltage, long cycle life, Low lithium secondary batteries have been commercialized and widely used.

Particularly, the lithium secondary battery has a working voltage of 3.6 V or higher, which is three times higher than a nickel-cadmium battery or a nickel-hydrogen battery which is widely used as a power source for portable electronic devices, and is rapidly expanded in terms of high energy density per unit weight There is a trend.

The lithium secondary battery is manufactured by using a material capable of inserting and desorbing lithium ions as a cathode and an anode, filling an organic electrolyte or a polymer electrolyte between the anode and the cathode, and inserting and removing lithium ions from the anode and the cathode. And generates electrical energy by oxidation and reduction reactions when they are desorbed.

In such a lithium secondary battery, a transition metal oxide having a layered or spinel structure is used as a cathode active material, and recently, a lithium transition metal phosphate cathode active material having excellent safety has been extensively studied.

Lithium transition metal phosphate materials are classified into LixM ₂ (PO ₄ ) ₃ , which is a Nasicon structure, and LiMPO ₄ , which has an olivine structure, and has been studied as a material superior in high temperature stability to LiCoO ₂ .

In particular, the olivine-structured lithium iron phosphate (LiFePO ₄ ), despite the somewhat low voltage disadvantage of ~ 3.4 V versus lithium, has the advantages of a high theoretical capacity of 170 mAh / g, excellent high temperature stability, There is a possibility of being applied to a cathode active material of a lithium secondary battery in the future and much research has been conducted as a cathode active material of a lithium ion secondary battery for a hybrid electric vehicle (HEV).

Korean Patent Publication No. 2012-0015278 discloses an apparatus for producing an inorganic compound and a method for producing an inorganic compound using the same.

However, in the apparatus for producing an inorganic compound disclosed in the above prior art documents, the supply flow rate of the raw material changes due to the pressure increase due to the scale of the pipe under stable reaction conditions in the supercritical continuous hydrothermal synthesis and causes the synthesis pH and nonuniformity of particles There was a problem.

In addition, there has been a problem that the continuous hydrothermal synthesis should be stopped when clogging occurs in the reactor.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the problems of the prior art as described above, and it is an object of the present invention to provide a mixer, And to provide a hydrothermal synthesis device.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise forms disclosed. Other objects, which will be apparent to those skilled in the art, It will be possible.

According to an aspect of the present invention, there is provided a method of manufacturing an iron / phosphorus solution tube, comprising the steps of: passing a center tube through an iron / phosphorus solution tube to which an iron (Fe) A pre-mixer through which a lithium solution tube into which a lithium (Li) solution is injected is connected to the center tube; And two main mixers through which the center tube passes and a supercritical water tube into which supercritical water is introduced is connected to the center tube and stirred with a solution mixed with the iron / phosphorus solution and the lithium solution, The main mixers may be switched so that at least one of them can be selectively operated.

The center tube may be branched into two branch tubes to penetrate the main mixer.

The branch tube may be bent to extend along the curve.

A slurry shutoff valve may be provided at a front end of the main mixer to shut off the clogging when the main mixer is clogged.

The slurry shut-off valve may be a high-pressure ball valve.

A supercritical water shutoff valve may be provided in the supercritical water tube to block the supernatant when the clogging occurs in the main mixer.

The supercritical shut-off valve may be a special needle valve for high temperature and high pressure.

The lithium solution tube and the supercritical water tube may be symmetrically connected to both sides of the center tube, respectively.

The lithium solution tube and the supercritical water tube may be inclined with respect to the extending direction of the center tube.

The lithium solution tube and the supercritical water tube and the center tube may be connected to form an acute angle with each other.

And a reactor for producing a cathode active material through a supercritical reaction of the mixture stirred in the main mixer.

And a filter for filtering the powder of the cathode active material produced in the reactor.

Water reservoir; A heat exchanger for exchanging heat between the water supplied from the water reservoir and the mixed solution mixed in the main mixer to bring the mixture into a high temperature state; And a heater for heating the water passing through the heat exchanger to produce supercritical water.

According to another aspect of the present invention, there is provided a lithium secondary battery comprising: a lithium tube through which a center tube passes and a lithium solution into the tube; A pre-mixer to which an iron / phosphorus solution tube into which the phosphorus (P) solution is introduced is connected; And a plurality of main mixers through which the center tube passes and a supercritical water tube into which supercritical water is introduced is connected to the center tube and stirred with a mixed solution of the iron / phosphorus solution and the lithium solution, The main mixers may be switched so that at least one of them can be selectively operated.

According to the present invention, two main mixers are arranged in parallel and controlled so that they can be switched to each other, so that even if the pressure in one main mixer is increased, the process can be continuously performed while maintaining synthesis in another main mixer.

1 is a view showing an apparatus for manufacturing a cathode active material according to an embodiment of the present invention;
FIG. 2 is a view showing a supercritical continuous hydrothermal synthesis apparatus according to an embodiment of the present invention. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of an apparatus for producing a cathode active material according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view showing an apparatus for manufacturing a cathode active material according to an embodiment of the present invention.

According to the present invention, the cathode active material according to the present invention is prepared by reacting a mixed solution of Fe (Fe) / phosphorus (P) solution and lithium (Li) solution with a supercritical water. First, the iron / phosphorus solution and the lithium solution stored in the iron / phosphorus solution reservoir 5 and the lithium solution reservoir 6, respectively, are introduced into the pre-mixer 10 through different lines.

The pre-mixer 10 pre-mixes the iron / phosphorus solution and the lithium solution in order to prevent the Fe salt from being precipitated on the line due to the decrease in solubility due to the supercritical iron / phosphorus solution at high temperature . When iron / phosphorus solution and lithium solution are stirred, FePO ₄ type Phosphrous Fe salt is produced without generating independent Fe salt. The Fe salt of phosphoric acid is less hardenable to heat than FeSO ₄ and can prevent the solution input line from being clogged by the Fe salt because it is not precipitated in the mid-temperature range (about 300 ° C). That is, in the pre-mixer 10, the iron / phosphorus solution and the lithium solution are preliminarily stirred to form a phosphate salt of Fe, so that the two main mixers 20 to be described below meet the supercritical water coefficient.

On the other hand, the water stored in the water storage tank 7 is heat-exchanged with the mixture mixed in the main mixer 20 through the heat exchanger 40, is raised to about 300 ° C, and is introduced into the heater 42. The temperature of the heater 42 is raised to a temperature required for the supercritical reaction (about 400 ° C.), and the mixed gas is moved to the main mixer 20 side.

Since the iron solution and the lithium solution are preliminarily mixed before the supercritical water is mixed with the supercritical water, the Fe salt is not precipitated in the premixer 10 even if it meets the supercritical water having a high temperature (about 400 ° C) So that it can be normally flowed without interfering with the flow.

Next, the solution stirred in the main mixer 20 is introduced into the reactor 30. A supercritical reaction can be performed in the reactor 30 under the conditions of high temperature and high pressure, and lithium iron phosphate (LiFePO ₄ ) can be produced. For example, the reactor 30 may include a tube having a predetermined length, and the outer surface of the tube may be provided with a thermal insulating material.

On the other hand, since the product obtained through supercritical reaction contains powder, it is introduced into the filter 44 to filter it. The product filtered by the filter 44 is stored in the product storage tank 46.

As described above, in the present invention, the supercritical reaction is used to prepare the cathode active material and the supercritical water is mixed with the iron solution and the lithium solution at the same time, So that the supercritical reaction can be performed more smoothly.

Although lithium iron phosphate is described as a cathode active material in this embodiment, it is not necessarily limited thereto, and any material may be used as long as it is an olivine structure of LiMPO ₄ .

Hereinafter, an embodiment of a supercritical continuous hydrothermal synthesis apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a view illustrating a supercritical continuous hydrothermal synthesis apparatus according to an embodiment of the present invention. Referring to FIG.

As shown, a center tube 11 is installed through the center of the pre-mixer 10. The center tube 11 passes through the center of the main mixer 20 as well. The center tube 11 is a portion where the iron / phosphorus solution and the lithium solution injected into the pre-mixer 10 are mixed.

Further, the center tube 11 is provided with an iron / phosphorus solution tube 12 penetrating therethrough. The iron / phosphorus solution tube 12 extends through the center tube 11 to the inlet of the main mixer 20. The reason why the iron / phosphorus solution tube 12 is disposed at the center in the present embodiment is to prevent the Fe / phosphorus solution from being dissolved due to the decrease of solubility due to heat, and thus the Fe salt is precipitated. That is, the iron / phosphorus solution tube 12 is positioned at the center and the lithium solution tube 14 is connected to both sides to minimize the influence of heat transmitted from the supercritical water. Of course, it is also possible that the lithium solution tube 14 is located at the center and the iron / phosphorus solution tube 12 is connected to both sides.

On the other hand, on both sides of the center tube 11, the lithium solution tube 14 is symmetrically connected. Of course, the lithium solution tube 14 may be connected only to one side of the center tube 11. Further, it is preferable that the lithium solution tubes 14 are connected to be inclined with respect to the extending direction of the center tube 11 and connected to form an acute angle with each other. Thus, the center tube 11 and the lithium solution tube 14 form an acute angle, so that a negative pressure is generated in the lithium solution tube 14 and sucked into the center tube 11 side.

Here, the iron / phosphorus solution and the lithium solution have to be introduced into the main mixer 20 after being premixed in the center tube 11. When the iron / phosphorus solution and the lithium solution are stirred, FePO ₄ -type Phosphrous Fe salt is produced without generating any Fe salt. The Fe salt of phosphoric acid is less hardenable to heat than FeSO ₄ and can prevent the solution input line from being clogged by the Fe salt because it is not precipitated in the mid-temperature range (about 300 ° C). Therefore, in this embodiment, the iron / phosphorus solution and the lithium solution are mixed in advance, and the iron / phosphorus solution tube 12 passes through the center tube 11 so that it can be mixed in advance, And is connected to the tube 11. For reference, when the iron / phosphorus solution and the lithium solution are stirred in the pre-mixer 10, a mixed solution of Fe ₃ (PO ₄ ) ₂ .8H ₂ O may be generated.

Next, a cooling device 15 is provided between the pre-mixer 10 and the main mixer 20 to prevent the heat generated by the supercritical water from flowing into the corresponding center tube 11. [ As the cooling device 15, for example, a cooling jacket in the form of a double pipe tube or a tube type in which cooling water flows inside can be used.

On the other hand, the rear end of the pre-mixer 10 is connected to the two main mixers 20. In this embodiment, two main mixers 20 are connected in parallel and can be controlled so that they can be switched to each other. Switching means that the two main mixers 20 are controlled so as to be selectively operable. In other words, when clogging occurs in any of the main mixers 20, the main mixer 20 is stopped and only the other main mixer 20 can be operated. Of course, most preferably, the two main mixers 20 are operated at the same time to increase the production efficiency, but when this is not the case, the main mixer 20 is selectively operated.

As described above, at least one of the main mixers 20 operates normally, and the supercritical continuous hydrothermal synthesis is continuously performed, so that it is possible to maintain a stable and stable process. In other words, if the pressure in the main mixer 20 is increased due to the scale, the continuous synthesis should be terminated and the scale in the main mixer 20 should be removed. However, according to the present embodiment, continuous synthesis can be continuously performed.

On the other hand, the center tube 11 passing through the pre-mixer 10 is branched into two branch tubes 16 and extends into the main mixer 20. At this time, it is preferable that the branch tube 16 is bent to extend along a curve, which is not bent at a right angle. This is because it is possible to prevent the mixed slurry form solution in the pre-mixer 10 from being adsorbed in the tube.

A slurry shutoff valve 18 is provided in the branch tube 16 corresponding to the front end of the main mixer 20 to shut off the clogging when the main mixer 20 is clogged. For example, the slurry shutoff valve 18 is controlled by a separate control unit (not shown), and when any one of the main mixers 20 is clogged, the slurry shutoff valve 18 receives the signal immediately and closes the line to shut off the signal. In this state, the suprathermal coefficient is continuously injected through the supercritical water tube 22. Therefore, only the supercritical water is supplied to the inside of the main mixer 20 where the clogging phenomenon occurs, and it is easy to remove the scale causing clogging of the main mixer 20 with the supercritical pressure.

On the other hand, a supercritical water shutoff valve 24 may be installed on one side of the supercritical water tube 22. That is, the supercritical water shutoff valve 24 blocks the supernatant flowing into the main mixer 20, which has occurred with the slurry shutoff valve 18. For example, when the clogging phenomenon is excessive in the main mixer 20 and it is difficult to remove the scale with only the introduction of the supercritical water, the supercritical water tube 22 is shut off and the cleaning solution is introduced into the main mixer 20 . As the cleaning solution, a nitric acid solution or the like may be used.

The slurry shutoff valve 18 preferably uses a high-pressure ball valve so as not to interfere with the flow of the flow path. The supercritical water shut-off valve 24 is a high- ) Is preferably used.

At the center of each main mixer 20, a branch tube 16 extends and penetrates. On both sides of the branch tube 16, a supercritical water tube 22 is symmetrically connected. Of course, the supercritical water tube 22 may be connected to only one side of the branch tube 16. It is also preferred that the supercritical water tubes 22 be connected in an inclined manner with respect to the extending direction of the branch tube 16 and connected to form an acute angle with each other. As such, the branch tube 16 and the suprathymetric tube 22 form an acute angle, so that a negative pressure is generated in the suprathymetric tube 22 and sucked into the branch tube 16 side.

Next, the solution agitated in the main mixer 20 is subjected to supercritical reaction through continuous synthesis while flowing along the tube, and lithium phosphate (LiFePO ₄ ) as a cathode active material can be produced.

The present invention also includes a lithium secondary battery comprising the above-mentioned cathode active material. The lithium secondary battery generally comprises an anode, a cathode, a separator, and a non-aqueous electrolyte containing a lithium salt. The positive electrode is prepared, for example, by coating a mixture of a positive electrode active material, a conductive material and a binder on a positive electrode current collector, and drying the mixture. Optionally, a filler may be further added to the mixture.

The scope of the present invention is not limited to the embodiments described above, but may be defined by the scope of the claims, and those skilled in the art may make various modifications and alterations within the scope of the claims It is self-evident.

5: iron / phosphorus solution storage tank 6: lithium solution storage tank
7: water storage tank 10: pre-mixer
11: center tube 12: iron / phosphorus solution tube
14: lithium solution tube 15: cooling device
16: branch tube 18: slurry shutoff valve
20: main mixer 22: supercritical water tube
24: Supercritical water shutoff valve 30: Reactor
40: heat exchanger 42: heater
44: filter 46: product storage tank

Claims (19)

A pre-mixer in which iron (Fe) / phosphorus (P) solution and lithium (Li) solution are separately introduced; And
A main mixer in which a mixed solution of the iron / phosphorus solution and the lithium solution is introduced, and a supercritical water is charged and stirred with a mixed solution of the iron / phosphorus solution and the lithium solution,
The two main mixers are controlled so that at least one of the two main mixers can be selectively operated,
A slurry shutoff valve is installed at a front end of the main mixer to shut off the clogging when the main mixer is clogged,
Wherein supercritical water is introduced into the supercritical water tube and supercritical water shutoff valves are installed in the main mixer to shut off the supercritical water tube when the main mixer is clogged, Hydrothermal synthesis device. The method according to claim 1,
The iron / phosphorus solution tube through which the iron / phosphorous solution is injected passes through the center tube, and a lithium solution tube into which the lithium solution is injected is connected to the center tube Wherein the supercritical continuous hydrothermal synthesis apparatus comprises: 3. The method of claim 2,
Wherein the center tube passes through the interior of the main mixer and a supercritical water tube into which the supercritical water is introduced is connected to the center tube to be stirred with a mixed solution of the iron / phosphorus solution and the lithium solution. Continuous hydrothermal synthesis apparatus. The method of claim 3,
Wherein the center tube is divided into two branch tubes to penetrate the main mixer. 5. The method of claim 4,
Wherein the branch tube extends bending along a curve. ≪ RTI ID = 0.0 > 21. < / RTI > delete The method according to claim 1,
Characterized in that the slurry shut-off valve is a high-pressure ball valve. delete The method according to claim 1,
Characterized in that the supercritical water shutoff valve is a special needle valve for high temperature and high pressure. The method of claim 3,
Wherein the lithium solution tube and the supercritical water tube are symmetrically connected to both sides of the center tube, respectively. The method of claim 3,
Wherein the lithium solution tube and the supercritical water tube are inclined with respect to the extending direction of the center tube. The method of claim 3,
Wherein the lithium solution tube, the supercritical water tube, and the center tube are connected to form an acute angle with each other. The method according to claim 1,
And a reactor for producing a cathode active material through supercritical reaction of the mixture stirred in the main mixer. 14. The method of claim 13,
Further comprising a filter for filtering the powder of the cathode active material produced in the reactor. The method according to claim 1,
Water reservoir;
A heat exchanger for exchanging heat between the water supplied from the water reservoir and the mixed solution mixed in the main mixer to bring the mixture into a high temperature state; And
Further comprising a heater for heating water passing through the heat exchanger to produce supercritical water. delete A cathode active material synthesized by the supercritical continuous hydrothermal synthesis apparatus according to claim 1. 18. The method of claim 17,
Wherein the cathode active material is an olivine structure lithium iron phosphate (LiFePO ₄ ). A lithium secondary battery comprising the cathode active material according to claim 17.

Images