Hydrothermal synthesis device and method of preparing cathode active material using the same

1. A hydrothermal synthesis device for continuously preparing an inorganic slurry using a hydrothermal method, the hydrothermal synthesis device comprising:

a mixer to mix at least one precursor solution for preparing an inorganic material, injected via at least one supply tube, to prepare an intermediate slurry;

a connection tube provided at a side of the mixer, continuously discharging the prepared intermediate slurry to a reactor, and having a hydrophobic coating on an inner surface of a portion thereof adjacent to the reactor; and

the reactor performing hydrothermal reaction of the intermediate slurry supplied from the connection tube by receiving a liquid stream heated to supercritical or subcritical conditions using a heat exchanger and connected to the connection tube into which the intermediate slurry prepared from the mixer is introduced and to at least one injection tube into which the heated liquid stream is injected,

wherein the hydrophobic coating is a coating comprising a hydrophobic material, and

wherein the hydrophobic material is an inorganic compound having a fluorine group or the hydrophobic material includes carbon particles.

2. The hydrothermal synthesis device according to claim 1 , wherein the at least one supply tube comprises a first supply tube disposed at a central portion of an upper surface of the mixer, a second supply tube disposed at a side part of the mixer so as to form an internal angle of 10° to 90° with respect to the first supply tube, and a third supply tube disposed at another side of the mixer so as to face the second supply tube.

3. The hydrothermal synthesis device according to claim 1 , wherein the hydrophobic coating is formed by coating an inner surface of the connection tube with a coating solution prepared through mixing of a hydrophobic organic solvent and the hydrophobic material and heat-treating the coated inner surface of the connection tube.

4. The hydrothermal synthesis device according to claim 3 , wherein a mixing ratio (volume ratio) of the hydrophobic organic solvent to the hydrophobic material is 300-1200:0.1-50, and the heat-treating is performed at 100° C. to 600° C. for 30 minutes to 1 hour.

5. The hydrothermal synthesis device according to claim 1 , wherein the hydrophobic coating has a thickness of 10 μm to 50 μm.

6. The hydrothermal synthesis device according to claim 1 , wherein the hydrophobic coating is formed on an entire inner surface of the connection tube.

7. The hydrothermal synthesis device according to claim 1 , wherein the hydrophobic coating is formed on an inner surface of at least one of the mixer, the reactor, and the at least one injection tube.

8. The hydrothermal synthesis device according to claim 1 , wherein the connection tube is provided at an outer portion thereof with a cooling member to dissipate heat transferred from the heated liquid stream.

9. The hydrothermal synthesis device according to claim 1 , wherein the liquid stream is supercritical water heated at a temperature of 350° C. to 800° C. and a pressure of 180 bar to 550 bar.

10. The hydrothermal synthesis device according to claim 1 , wherein the at least one injection tube comprises two injection tubes disposed at outer sides of the reactor.

11. A method of preparing an inorganic slurry by using the hydrothermal synthesis device according to claim 1 , the method comprising:

injecting, into a mixer, a first precursor solution for preparation of an inorganic material via a first supply tube and a second precursor solution for preparation of the inorganic material via each of second and third supply tubes;

introducing, into a reactor, an intermediate slurry prepared through mixing of the injected first and second precursor solutions via a connection tube;

injecting supercritical water containing high-temperature and high-pressure water into the reactor via an injection tube; and

preparing an inorganic slurry by hydrothermal reaction in the reactor and continuously discharging the prepared inorganic slurry.

12. The hydrothermal synthesis device according to claim 1 , wherein the inorganic compound is MgF 2 and/or CaF 2 .

13. A hydrothermal synthesis device for continuously preparing an inorganic slurry using a hydrothermal method, the hydrothermal synthesis device comprising:

a mixer to mix at least one precursor solution for preparing an inorganic material, injected via at least one supply tube, to prepare an intermediate slurry;

a connection tube provided at a side of the mixer, continuously discharging the prepared intermediate slurry to a reactor, and having a hydrophobic coating on an inner surface of a portion thereof adjacent to the reactor; and

the reactor performing hydrothermal reaction of the intermediate slurry supplied from the connection tube by receiving a liquid stream heated to supercritical or subcritical conditions using a heat exchanger and connected to the connection tube into which the intermediate slurry prepared from the mixer is introduced and to at least one injection tube into which the heated liquid stream is injected,

wherein the hydrophobic coating is formed of a lubricant coating material, and

wherein the lubricant coating material is tungsten disulfide (WS 2 ) and/or molybdenum disulfide (MoS 2 ).

14. The hydrothermal synthesis device according to claim 13 , wherein the at least one supply tube comprises a first supply tube disposed at a central portion of an upper surface of the mixer, a second supply tube disposed at a side part of the mixer so as to form an internal angle of 10° to 90° with respect to the first supply tube, and a third supply tube disposed at another side of the mixer so as to face the second supply tube.

15. The hydrothermal synthesis device according to claim 13 , wherein the hydrophobic coating has a thickness of 10 μm to 50 μm.

16. The hydrothermal synthesis device according to claim 13 , wherein the hydrophobic coating is formed on an entire inner surface of the connection tube.

17. The hydrothermal synthesis device according to claim 13 , wherein the hydrophobic coating is formed on an inner surface of at least one of the mixer, the reactor, and the at least one injection tube.

18. The hydrothermal synthesis device according to claim 13 , wherein the connection tube is provided at an outer portion thereof with a cooling member to dissipate heat transferred from the heated liquid stream.

19. The hydrothermal synthesis device according to claim 13 , wherein the liquid stream is supercritical water heated at a temperature of 350° C. to 800° C. and a pressure of 180 bar to 550 bar.

20. The hydrothermal synthesis device according to claim 13 , wherein the at least one injection tube comprises two injection tubes disposed at outer sides of the reactor.

21. A method of preparing an inorganic slurry by using the hydrothermal synthesis device according to claim 13 , the method comprising:

injecting, into a mixer, a first precursor solution for preparation of an inorganic material via a first supply tube and a second precursor solution for preparation of the inorganic material via each of second and third supply tubes;

introducing, into a reactor, an intermediate slurry prepared through mixing of the injected first and second precursor solutions via a connection tube;

injecting supercritical water containing high-temperature and high-pressure water into the reactor via an injection tube; and

preparing an inorganic slurry by hydrothermal reaction in the reactor and continuously discharging the prepared inorganic slurry.