Lithium sulfide heat treatment method and system

Abstract

The present invention relates to an apparatus used in a heat treatment process for obtaining purified lithium sulfide powder. Presented are a method and a system in which a lithium sulfide heat treatment process requiring significant cost and time is automated such that production costs can be lowered and yield of a product can be improved.

Description

Lithium sulfide heat treatment method and system

[0001] The present invention relates to a process method for purifying impurities contained within lithium sulfide powder produced by drying through a thermal reduction process, an extraction process, and a drying process by heating it in a vertical furnace. More specifically, the invention relates to a method for improving production speed and maintenance costs by automating the lithium sulfide powder purification process.

[0002]

[0003] As the demand for electric vehicles and large-capacity power storage devices increases, various batteries have been developed to meet this need.

[0004] Lithium-ion batteries have been widely commercialized because they have the best energy density and power output characteristics among various types of rechargeable batteries.

[0005] While lithium secondary batteries containing liquid-type electrolytes with organic solvents are mainly used, it has been pointed out that liquid-type secondary batteries cause battery expansion due to the decomposition of the liquid electrolyte by electrode reactions and pose a risk of ignition due to leakage of the liquid electrolyte.

[0006] To address the problems of these liquid-type secondary batteries, lithium secondary batteries using solid electrolytes with excellent stability have recently been attracting attention.

[0007] Solid electrolytes can be classified into oxide-based and sulfide-based types. Since sulfide-based solid electrolytes have higher lithium-ion conductivity and are stable over a wide voltage range compared to oxide-based solid electrolytes, sulfide-based solid electrolytes are primarily used for all-solid-state batteries.

[0008] However, lithium sulfide, one of the main raw materials for sulfide-based solid electrolytes, has the disadvantage of being very expensive.

[0009] The reason for this is that a process is required to increase purity by removing organic substances, such as residual ethanol and carbon molecules, as well as inorganic substances, such as sulfur and other impurities, that remain during the lithium sulfide manufacturing process.

[0010] While existing prior art presents methods for purifying impurities contained in the lithium sulfide mentioned above, it does not introduce a method to lower production costs by automating this process.

[0011] For example, prior art disclosed prior to the present application (Published Patent 10-2023-0054519) also introduces only a method for purifying lithium sulfide.

[0012] Therefore, it is essential to develop technology to increase the production speed of lithium sulfide by automating the purification process for impurities in powdered lithium sulfide.

[0013]

[0014] The present invention has been devised to solve the aforementioned problems and provides a method for removing internal impurities from lithium sulfide powder without exposing it to external oxygen or moisture.

[0015] In addition, it provides a method to minimize production costs and maintenance time by automating the lithium sulfide refining process.

[0016] In addition, a method is provided to increase the purity of lithium sulfide by safely removing various impurities, such as VOCs, generated during the lithium sulfide heat treatment process.

[0017] In addition, a method is provided to prevent damage to filters or pumps caused by various impurities, such as VOCs, generated during the lithium sulfide heat treatment process.

[0018]

[0019] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0020]

[0021] To solve the above-mentioned problem, the present invention relates to a system that heat-treats lithium sulfide in a plurality of vertical furnaces (40) equipped with a heater (412) inside and is controlled by a control unit (800), comprising: a first step of passing a crucible (100) loaded with unrefined lithium sulfide through a first transfer path (91) disposed on the lower side of the plurality of vertical furnaces (40) at a constant speed; a second step of identifying a vertical furnace (40) among the plurality of vertical furnaces (40) for which heat treatment is not performed; a third step of introducing the crucible (100) loaded with unrefined lithium sulfide into the vertical furnace (40) for which heat treatment is not performed; and a fourth step of heat-treating and refining the unrefined lithium sulfide inside the vertical furnace (40). and a fifth step of withdrawing the crucible (100) loaded with the refined lithium sulfide from the vertical furnace (40) and transferring it to the first transfer furnace (91); may be included.

[0022] In one embodiment of the present invention, the control unit (800) may be characterized by introducing the crucible (100) loaded with unrefined lithium sulfide into the vertical furnace (40) closest to the crucible (100) loaded with unrefined lithium sulfide passing through the first transfer path (91) and the furnace where heat treatment is not performed.

[0023] In one embodiment of the present invention, one end of the first transfer path (91) is connected to a supply unit, and the supply unit may be characterized by supplying a plate (110) on which a crucible (100) loaded with unrefined lithium sulfide is placed to the first transfer path (91).

[0024] In one embodiment of the present invention, the other end of the first transfer path (91) is connected to a discharge section, and the first transfer path (91) may be characterized by supplying a plate (11) on which the crucible (100) loaded with lithium sulfide powder, which has been heat-treated and refined in the vertical path (40), is placed to the discharge section.

[0025] In one embodiment of the present invention, the control unit (800) may be characterized by lowering the transfer speed of the first transfer path (91) when it is expected that the unpurified lithium sulfide passing through the first transfer path (91) will not be introduced into the vertical furnace (40) where heat treatment is not performed until the crucible (100) loaded with the unpurified lithium sulfide reaches the discharge section.

[0026] In one embodiment of the present invention, the first transfer path (91) may be characterized by being composed of a plurality of rotating rollers (90).

[0027] In one embodiment of the present invention, the control unit (800) may be characterized by setting the spacing between the crucibles (100) loaded with unrefined lithium sulfide supplied from the supply unit to be greater than or equal to the spacing between the vertical furnaces (40).

[0028] In one embodiment of the present invention, the control unit (800) may be characterized by setting the minimum speed of the first transfer path (91) to a speed at which the crucible (100) moves on the first vertical path (40) by a distance greater than the gap between the vertical paths (40) during the time that the vertical path (40) heat-treats the unpurified lithium sulfide.

[0029] In one embodiment of the present invention, the control unit (800) may be characterized by setting the maximum speed of the first transfer path (91) to the speed at which the crucible (100) moves from the supply section to the discharge section on the first vertical path (40) during the time that the vertical path (40) heat-treats the unpurified lithium sulfide.

[0030] In one embodiment of the present invention, the time for heat-treating the unpurified lithium sulfide in the vertical furnace (40) may be characterized as the time required until the crucible (100) loaded with the unpurified lithium sulfide is transferred from the first transfer furnace (91) to the vertical furnace (40) and heat-treated, and then the crucible (100) loaded with purified lithium sulfide is re-transferred to the first transfer furnace (91).

[0031] To solve the above-mentioned problem, the present invention comprises: a control unit (800) for controlling a lithium sulfide heat treatment process facility; a vertical furnace (40) having an opening (421) through which lithium sulfide can move vertically downward and a first discharge port (420) formed to allow impurities to be discharged vertically upward; a heater (412) installed on one side of the inner surface of the vertical furnace (40); a vertical transfer device (300) that moves vertically up and down and moves the lithium sulfide in and out through the opening (421); and a first transfer furnace (91) installed at a lower side spaced a predetermined distance from the vertical furnace (40) and moving a plate (110) on which a crucible (100) loaded with lithium sulfide is placed using a plurality of rollers (90). It may include a supply unit connected to one end of the first transfer path (91) and supplying a plate (110) on which a crucible (100) loaded with unpurified lithium sulfide is placed to the first transfer path (91); and a discharge unit connected to the other end of the first transfer path (91) and receiving a plate (11) on which a crucible (100) loaded with purified lithium sulfide heat-treated in the vertical furnace (40) is placed.

[0032]

[0033] According to various embodiments of the present invention, the generation of impurities can be minimized by preventing the lithium sulfide powder produced through the drying process from being exposed to air or external moisture.

[0034] According to various embodiments of the present invention, the lithium sulfide powder purification process can be automated to increase productivity and ultimately lower production costs.

[0035] According to various embodiments of the present invention, the yield of the product can be increased by preventing gases containing impurities, such as VOCs generated during the lithium sulfide heat treatment process, from penetrating the lithium sulfide being heat-treated.

[0036] According to various embodiments of the present invention, maintenance costs can be minimized by preventing gases containing impurities, such as VOCs generated during the lithium sulfide heat treatment process, from damaging vacuum maintenance devices or filters.

[0037] According to various embodiments of the present invention, the operational efficiency of the heat treatment facility can be maximized by having a manager directly control the lithium sulfide powder purification process.

[0038]

[0039] FIG. 1 is a schematic diagram of the lithium sulfide powder heat treatment process system of the present invention.

[0040] FIG. 2 is a side view illustrating lithium sulfide powder produced in the dryer of the present invention being divided and loaded into a crucible within the first loading section.

[0041] FIG. 3 is a side view illustrating that a mover moves lithium sulfide powder, which is divided and loaded in a crucible in the first loading section of the present invention, to a loading chamber.

[0042] FIG. 4 is a front view illustrating that a mover moves lithium sulfide powder, which is divided and loaded in a crucible in the first loading section of the present invention, to a loading chamber.

[0043] FIG. 5 is a working diagram illustrating a mechanism in which a crucible and a plate loaded with lithium sulfide powder of the present invention are introduced into a loading chamber, the interior is made vacuum, and then transferred to a first transfer path.

[0044] FIG. 6 is an operational diagram illustrating a mechanism in which a mover moves a crucible and a fleet loading chamber loaded with lithium sulfide powder of the present invention to the direct lower side of the vertical path when they reach the front of the vertical path along the first transfer path.

[0045] FIG. 7 is an operational diagram illustrating a mechanism for introducing a crucible and a fleet loading chamber loaded with lithium sulfide powder of the present invention into a vertical furnace using a vertical transfer device when the crucible and the fleet loading chamber are moved directly downwards in a vertical furnace.

[0046] FIG. 8 is a conceptual diagram illustrating a mechanism for inhaling and treating byproducts, such as VOCs, generated during the heat treatment of lithium sulfide powder in the vertical furnace of the present invention.

[0047] FIG. 9 is a flowchart schematically illustrating the process of purifying unrefined lithium sulfide powder using the vacuum heat treatment apparatus of the present invention.

[0048]

[0049] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0050] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0051] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0052] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0053] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0054] Singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may be omitted or additional components or steps may be included.

[0055] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less unless specifically stated otherwise.

[0056]

[0057] Hereinafter, a lithium sulfide vacuum heat treatment apparatus according to various embodiments will be described with reference to the attached drawings.

[0058]

[0059] [Basic Configuration]

[0060] High-purity lithium sulfide powder can be produced through a thermal reduction process, an extraction process, a drying process, and a heat treatment process.

[0061] Among the above processes, the heat treatment process described in the present invention is pointed out as the biggest cause of the increase in the unit price of lithium sulfide because it requires a lot of time and cost to remove impurities.

[0062] FIG. 1 schematically illustrates the configuration of a lithium sulfide vacuum heat treatment apparatus presented in the present invention to solve these problems.

[0063] In the present invention, vacuum refers to a state within a space filled with gas at a pressure lower than atmospheric pressure, and may mean, for example, a state of a space reduced from atmospheric pressure by a pump, etc.

[0064] The lithium sulfide vacuum heat treatment device presented in the present invention can have the operation and function of all components controlled by a control unit (800).

[0065] The above control unit (800) can report the control results to the lithium sulfide vacuum heat treatment device manager in real time or by creating a database of control and measurement result information.

[0066] The device configuration used in the heat treatment process can be broadly divided into a dryer (10), a first loading section (21), a loading chamber (30), a first transfer path (91), a vertical path (40), a second loading section (22), and an impurity post-treatment device.

[0067] The above vertical path (40) is a collective name for the plurality of vertical paths (41, 42, 43, 44) described above.

[0068] The above loading chamber (30), first transfer path (91), and vertical path (40) can be installed inside a sealed body (500) and configured to be isolated from external air or moisture.

[0069] The interior of the above-mentioned seal (500) can always maintain a vacuum level above a certain level through a plurality of vacuum pumps.

[0070] The above-described dryer (10) is a device used at the end of the aforementioned drying process and performs the role of finally producing lithium sulfide containing impurities.

[0071] The above impurities occur because the previous process involves preparing a mixture by mixing a sulfide-based solid electrolyte raw material containing carbon-containing lithium sulfide in an ethanol solvent.

[0072] In addition, other causes of impurities may arise because various elements, such as phosphorus (P) or chlorine (Cl), are used as raw materials for sulfide-based solid electrolytes.

[0073] Lithium sulfide produces hydrogen sulfide, which is harmful to the human body, when it reacts with oxygen or moisture. Furthermore, since it is an impurity itself, it must never be exposed to outside air or moisture.

[0074] Generally, for lithium sulfide powder to be commercialized, the oxygen content must be managed to be 0.4% or less.

[0075] Accordingly, the lithium sulfide produced in the dryer (10) is transferred into the interior through the inlet (25) of the first loading section (21), and then argon gas can be injected through the second outlet (24) installed on one side of the first loading section (21) to suppress the lithium sulfide from reacting with oxygen.

[0076] One end of the first transfer path (91) is connected to a supply unit, and the supply unit can supply a plate (110) on which a crucible (100) loaded with unrefined lithium sulfide is placed to the first transfer path (91).

[0077] At this time, it may be a loading chamber (30) connected to the first loading section (21).

[0078] In addition, the other end of the first transfer path (91) is connected to the discharge section, and the first transfer path (91) can supply to the discharge section a plate (11) on which the crucible (100) loaded with lithium sulfide powder, which has been heat-treated and refined in the vertical path (40), is placed.

[0079] At this time, the discharge section may be an unloading chamber (50) connected to the second loading section (22).

[0080] As shown in FIG. 2, the unrefined lithium sulfide inside the first loading section (21) is divided and loaded into a crucible (100), and can then be placed on a plate (110) with markings on the side.

[0081] To facilitate movement within the first loading section (21), the crucible (100) and plate (110) can be placed back on the support (120).

[0082] The crucible (100) and plate (110) placed on the support (120) can first be moved to the loading chamber (30) for the heat treatment process.

[0083] The loading chamber (30) above serves as a transition section to create a complete vacuum state before heat-treating the unrefined lithium sulfide.

[0084] First, when the crucible (100) and plate (110) placed on the support (120) arrive at the entrance of the loading chamber (30), the first sealing window (31) that seals between the first loading section (21) and the loading chamber (30) can be opened.

[0085] When the first sealing window (31) is opened, argon and air inside the first loading section (21) penetrate into the loading chamber (30).

[0086] A second transport path (92) composed of a plurality of rollers (90) is installed at the bottom of the first loading section (21), and a mover (200) may be installed at the bottom of the second transport path.

[0087] As illustrated in FIGS. 3 and 4, the mover (200) can protrude above the second transfer path (92) when the first sealing window (31) is opened to move the crucible (100) and plate (110) loaded with the unrefined lithium sulfide into the loading chamber (30).

[0088] The mover (200) may be composed of a first support (210) that holds the lower end of the plate (110), and a first cylinder (220) which has one side connected to the first support (210) and the other side connected to a first driving unit (230), and which moves the plate (110) from the first loading unit (21) to the loading chamber (30) by adjusting its length using the power transmitted by the first driving unit (230).

[0089] When the crucible (100) and plate (110) are introduced into the loading chamber (30), the first sealing window (31) is driven to isolate them from the first loading section (21), and then the discharge device (33) is driven to discharge internal air and argon gas to the outside, thereby creating a vacuum inside.

[0090] In addition, the above mover (200) can be hidden again in the lower part of the second transfer path (92).

[0091] The interior of the loading chamber (30) is at most 10 by the discharge device (33). -4 The vacuum state is maintained up to torr, and the vacuum level can be measured through a barometer (34) installed on one side of the loading chamber (30) and then transmitted to the control unit (800).

[0092] As illustrated in FIG. 5, the control unit (800) can move the crucible (100) and plate (110) loaded with unrefined lithium sulfide to the first transfer path (91) by opening the second sealing window (32) that seals the space between the first loading unit (21) and the first transfer path (91) when the vacuum inside the loading chamber (30) is sufficient.

[0093] As described above, the first transfer path (91) is normally at a maximum of 10 -4 Since a vacuum state of about torr is maintained, even if the second sealing window (32) is opened, no change in the vacuum level may occur.

[0094] The first conveyor (91) above is also composed of a plurality of rollers (90) and can convey the crucible (100) and plate (110) loaded with the unrefined lithium sulfide in one direction.

[0095] A plurality of vertical furnaces (40) may be arranged on the side of the first transfer path (91) to heat-treat unpurified active lithium powder and remove internal impurities (ethanol, carbon, sulfur, etc.).

[0096] The reason the above vertical furnace (40) is installed in multiple numbers may be that the time spent heat-treating in the vertical furnace (40) is longer than the number of crucibles (100) and plates (110) loaded with unrefined lithium sulfide supplied from the first loading section (21).

[0097] Accordingly, the number of vertical furnaces (40) can be modified or changed according to the number of crucibles (100) and plates (110) loaded with unrefined lithium sulfide supplied from the first loading section (21).

[0098] A plurality of position sensors (410) may be arranged on one side of the vertical path (40) or the first transfer path (91).

[0099] A pattern (111) or identification symbol, etc., may be placed on one side of the plate (110) supporting the crucible (100).

[0100] The position sensor (410) can identify the pattern (111) or identification symbol of the plate (110), detect a change in position, and transmit measurement information to the control unit (800).

[0101] As illustrated in FIGS. 6 and 7, the vertical furnace (40) is formed as a sealed space consisting of a side plate (419), a top plate (418), and a bottom plate (416). On one side of the bottom plate (416), a bottom opening (421) is located for vertical entry and exit of a crucible (100) loaded with lithium sulfide powder and a plate (110) supporting it. On one side of the side plate (419), a heater (412) for heat treatment of lithium sulfide powder is located, and on one side of the top plate (418), a first discharge port (420) for sucking in volatile organic compounds (VOC, CO2, CO) and inorganic substances (H2S, COS, SO2), etc., generated during heat treatment of lithium sulfide powder may be located.

[0102] The heater (412) can raise the temperature inside the vertical furnace (40) to 1,000°C to heat-treat the lithium sulfide powder, thereby gasifying and removing impurities contained in the lithium sulfide powder.

[0103] The first discharge port (420) is fluidly connected to the inlet of the first filter (71) through the first pipe (L1), the outlet of the first filter (71) is fluidly connected to the inlet of a plurality of chillers (721, 722) through the second pipe (L2), and the outlet of the plurality of chillers (721, 722) can be fluidly connected to the first vacuum pump (81) through the third pipe (L3).

[0104] The configuration following the first discharge port (420) described above will be explained in detail later.

[0105] A first inlet (413) through which argon gas is discharged may be disposed on one side of the bottom plate (416) or side plate (419).

[0106] The above argon gas can prevent impurities from being gasified during the heat treatment of the lithium sulfide powder and penetrating back into the lithium sulfide powder or adhering in the form of soot inside the vertical furnace (40), and can also perform the role of guiding the gas generated during the heat treatment process to be discharged through the first outlet (420) without interference.

[0107] In addition, the process manager or the control unit (800) can check the amount and condition of the gas generated during the heat treatment process through the optical sensor (415) installed inside the vertical furnace (40) and adjust the amount of argon gas discharged from the first inlet (413).

[0108] Additionally, a vertical transfer device (300) may be arranged at the lower end of the opening (421), comprising a second support (310) that holds the lower end of a plate (110) on which a crucible (100) loaded with lithium sulfide is placed, a sealing plate (320) that is spaced apart from the lower end of the second support (310) and seals the opening (421) when the crucible (100) and the plate (110) enter the vertical path (40), and a second cylinder (330) that is coupled to one side of the second support (310) and the sealing plate (320) and adjusts its length using power supplied to a second drive unit (340) to move the crucible (100) and the plate (110) in and out through the opening (421).

[0109] That is, the vertical transfer device (300) performs the function of transferring the crucible (100) loaded with unrefined lithium sulfide powder and the plate (110) supporting it to the area directly below the opening (421) by vertically raising and lowering it so that heat treatment is performed within the vertical furnace (40), and also discharges the refined lithium sulfide after heat treatment is completed.

[0110] The sealing plate (320) may have a packing (325) installed at its end so that impurity gas generated during heat treatment does not leak out through the opening (421) through complete contact with the bottom plate (416).

[0111] The above packing (325) can fill the uneven bonding surface between the sealing plate (320) and the bottom plate (416) end with internal elasticity.

[0112] Additionally, a coupling groove (417) for accommodating the packing (325) may be installed at the end of the bottom plate (416).

[0113] Ultimately, the crucible (100) and plate (110) can be fixed at a position higher than the bottom plate (416) within the vertical furnace (40) by the distance between the second support (310) and the sealing plate (320).

[0114] This is to ensure that the unrefined lithium sulfide inside the crucible (100) receives heat energy transferred from the heater (412).

[0115] A plurality of movers (200) may be arranged at the bottom of the first transfer path facing the front of each vertical path (40), comprising a first support (210) that holds the bottom of the plate (110), and a first cylinder (220) which has one side connected to the first support (210) and the other side connected to the first drive unit (230), and which adjusts the length using power transmitted by the first drive unit (230) to move the plate (110) on which a crucible (100) loaded with lithium sulfide that has not undergone a heat treatment process in the vertical path (40) is placed from the first transfer path (91) to the lower end of the opening (421), or move the plate (110) on which a crucible (100) loaded with lithium sulfide powder that has undergone heat treatment in the vertical path (40) is placed from the lower end of the opening (421) to the first transfer path (91).

[0116] The control unit (800) can operate the mover (200) by capturing the moment when the crucible (100) loaded with unrefined lithium sulfide and the plate (110) supporting it, which are moving along the first transport path (91), reach the front of the vertical path (40), or conversely, when the crucible (100) loaded with lithium sulfide and the plate (110) supporting it, which has finished heat treatment in the vertical path (40), are placed directly below the opening (421).

[0117] In addition, the mover (200) is protruded above the first transfer path (91) to perform the function described above when in operation, but in other states, it is hidden below the first transfer path (91) so as not to interfere with the movement of other crucibles (100) and plates (110).

[0118] A crucible (100) loaded with refined lithium sulfide that has been heat-treated through the vertical furnace (40) and a plate (110) supporting it can be transferred to an unloading chamber (50) along the first transfer path (91).

[0119] The above unloading chamber (50) can serve as a transition device to prevent external air or moisture from entering the seal (500) and lowering the internal vacuum level during the process in which the heat-treated refined lithium sulfide is transferred to the second loading section (22) and discharged to the outside.

[0120] When the crucible (100) loaded with the refined lithium sulfide and the plate (110) supporting it arrive at the entrance of the unloading chamber (50), the third sealing window (51) that was sealing the passage with the first transfer path (91) can be opened to bring the crucible (100) and the plate (110) into the unloading chamber (50).

[0121] A third transfer path (93) composed of a plurality of rollers (90) is installed at the bottom of the above unloading chamber (50), and a mover (200) may be installed at the bottom of the above third transfer path.

[0122] Additionally, on one side of the unloading chamber (50), an exhaust device (53) for maintaining the internal vacuum level and a barometer (54) for checking the appropriateness of the vacuum level may be installed.

[0123] Even in the step where the crucible (100) loaded with the refined lithium sulfide and the plate (110) supporting it are introduced into the unloading chamber (50), the fourth sealing window (52) that seals the passage between the unloading chamber (50) and the second loading section (22) is closed, so the interior can be maintained in a vacuum state.

[0124] When the crucible (100) loaded with the refined lithium sulfide and the plate (110) supporting it are fully inserted into the unloading chamber (50), the third sealing window (51) can be closed, and after a certain period of time, the fourth sealing window (52) can be opened.

[0125] This is because if the opening times of the third sealing window (51) and the fourth sealing window (52) overlap, the vacuum level inside the sealing body (500) may be damaged.

[0126] When the fourth sealed window (52) is opened, the mover (200) can protrude above the third transfer path (93) to move the crucible (100) and plate (110) loaded with the refined lithium sulfide into the second loading section (22).

[0127] At this time, the crucible (100) and plate (110) loaded with the refined lithium sulfide can be placed on the support (120) for ease of movement.

[0128] When the crucible (100) and plate (110) are moved to the second loading section (22), the fourth sealing window (52) is closed again, and the air and argon gas, etc. delivered from the second loading section (22) are removed through the discharge device (53) to maintain a vacuum level equivalent to that of the sealing body (500).

[0129] The interior of the second loading unit (22) may perform a process of vacuum packaging the purified lithium sulfide powder from which impurities have been removed, or measuring the concentration of impurities in the lithium sulfide powder that has undergone heat treatment through XRD analysis and transmitting the result to the control unit (800).

[0130] In addition, argon gas can be discharged through the second outlet (24) to minimize exposure to external air and moisture during the above processing.

[0131] The above XRD analysis can measure the concentration of lithium hydroxide generated when the lithium sulfide powder reacts with oxygen during the heat treatment process, and can serve as a reference for determining whether there is leakage inside the seal (500).

[0132] The above XRD analysis results can be transmitted to the process manager or the control unit (800) and provided as information for changing process operations or performing maintenance.

[0133] As illustrated in FIG. 8, volatile organic compound VOCs (CO2, CO, C2H6O) and inorganic gases (H2S, C, COS, SO2) generated while heat-treating lithium sulfide powder in the vertical furnace (40) can be delivered to the first filter (71) along the first pipe (L1) connected to the first outlet (420).

[0134] Inorganic materials such as lithium sulfide powder and carbon powder mixed in the gas of the first filter (71) can be filtered first.

[0135] The outlet of the first filter (71) can be fluidly connected to the Euro control valve (74).

[0136] Generally, organic gas generated during heat treatment in the vertical furnace (40) is generated at temperatures below 500°C, and at temperatures above that, inorganic gas begins to be generated, but the amount is very small.

[0137] Accordingly, the process manager or the control unit (800) can monitor the internal conditions of the vertical furnace (40) and, if there is no gas generated during heat treatment, control the flow control valve (74) to discharge the generated gas to the outside without undergoing a separate post-treatment process.

[0138] On the other hand, if gas containing organic or inorganic impurities is generated during heat treatment inside the vertical furnace (40), the gases that have passed through the first filter (71) can be transferred to a plurality of chillers (721, 722) through the second pipe (L2).

[0139] The chillers (721, 722) perform the function of cooling the gas (about -30°C), and during this process, the organic matter contained in the gas is liquefied and can be discharged through the recovery pipes (L41, L42) installed on one side of each chiller (721, 722).

[0140] Finally, the gas that has passed through the plurality of chillers (721, 722) can be delivered to the second filter (73).

[0141] The second filter above performs the role of filtering the remaining solidified by-products among the inorganic gas.

[0142] In addition, the second filter may be a filter composed of an activated carbon component, which is a porous material.

[0143] The organic or inorganic gas generated during the above heat treatment can be discharged from the vertical furnace (40) through the suction force provided by the first vacuum pump (81) which is fluidly connected to the first filter (71), chiller (721, 722) and second filter (73) described above.

[0144] Organic and inorganic gases generated during the above heat treatment process can affect the purity of the lithium sulfide powder, and as mentioned above, can adhere to the heat treatment device (especially the vacuum pump) in the form of soot, causing malfunctions; therefore, complete disposal of these gases is of the utmost importance.

[0145]

[0146] [Purification Device Control Process]

[0147] FIG. 9 illustrates the process of purifying unrefined lithium sulfide powder using the lithium sulfide vacuum heat treatment apparatus described above.

[0148] First, after completing the drying process, which is a preliminary step to the lithium sulfide heat treatment process, the lithium sulfide powder containing impurities from the dryer (10) can be transferred into the first loading section (21) which is composed of an argon atmosphere.

[0149] The above unrefined lithium sulfide powder can be divided and loaded into a crucible (100) inside the first loading section (21).

[0150] The above control unit (800) can adjust the amount of argon gas supplied through the second discharge port (24) installed on one side of the first loading unit (21).

[0151] The crucible (100) loaded with the above unrefined lithium sulfide powder can be placed on top of a plate (110) equipped with a pattern (111) or an identification symbol.

[0152] The above crucible (100) and plate (110) can be placed on a support (120) and transferred to a loading chamber (30) connected to the first loading section (21).

[0153] The control unit (800) can open a first sealing window (31) that seals the passage connected to the first loading unit (21) to introduce the crucible (100) and plate (110) loaded with the unrefined lithium sulfide powder into the loading chamber (30) through the mover (200).

[0154] The control unit (800) can close the first sealed window (31) after the crucible (100) and plate (110) loaded with the unrefined lithium sulfide powder are introduced, and drive the discharge device (33) to discharge the air and argon gas inside to create a vacuum state.

[0155] The control unit (800) can check whether the internal vacuum state is at the same level as the seal (500) from the barometer (34) installed inside the loading chamber (30).

[0156] When the internal vacuum state is the same as that of the sealing body (500), the control unit (800) can open the second sealing window (32) and then transfer the crucible (100) and plate (110) loaded with the unrefined lithium sulfide powder to the first transfer path (91).

[0157] The position sensor (410) installed on one side of the first transport path (91) or vertical path (40) can identify the pattern (111) or identification symbol of the plate (110) to track the position of the crucible (100) moving along the first transport path (91) and transmit the measurement result to the control unit (800).

[0158] When the crucible (100) and plate (110) loaded with the unrefined lithium sulfide powder reach the front of the vertical furnace (40) where the heat treatment process is not being performed, the control unit (800) can move the crucible (100) and plate (110) by extending the mover (200) positioned at the bottom of the first transfer path (91) to the lower end of the opening (421) of the vertical furnace (40).

[0159] The control unit (800) can reduce the transport speed of the crucible (100) and plate (110) loaded with unrefined lithium sulfide powder by adjusting the rotation speed of the roller (90) of the first transport path (91) when it is determined that there is no opportunity to heat treat the crucible (100) and plate (110) loaded with unrefined lithium sulfide powder in the vertical path (40) while they are passing through the first transport path (91), based on the speed at which the crucible (100) and plate (110) loaded with unrefined lithium sulfide powder pass through the first transport path (91) and the heat treatment speed of the vertical path (40).

[0160] The control unit (800) can drive the vertical transfer device (300) to bring the crucible (100) and plate (110) loaded with the unrefined lithium sulfide powder located directly below the opening (421) into the vertical furnace (40) through the opening (421).

[0161] At this time, the crucible (100) and the plate (110) supporting it can be positioned in the center of the vertical furnace (40).

[0162] The control unit (800) can drive a heater (412) installed inside the vertical furnace (40) to heat-treat the unrefined lithium sulfide powder and remove internal impurities.

[0163] The control unit (800) can deliver argon gas toward the crucible through the first inlet (413) installed at the bottom of the vertical furnace (40).

[0164] At this time, the first inlet (413) may be positioned below the crucible (100).

[0165] The control unit (800) can monitor the heat treatment process through a thermometer (414) or optical sensor (415) installed inside the vertical furnace (40) and transmit the results to the process manager.

[0166] The organic or inorganic gas generated during the heat treatment process of the above-mentioned unrefined lithium sulfide powder can be discharged through the first pipe (L1) connected to the first discharge port (420) located on one side of the top plate (418), together with the argon gas discharged from the first inlet port (413).

[0167] The control unit (800) can operate a first vacuum pump (81) connected in series with the first pipe (L1) to filter powder-shaped solids from the gas generated during the heat treatment process through the first filter (71).

[0168] The gas that passes through the first filter (71) can pass through a plurality of chillers (721, 722) to liquefy and filter the organic gas.

[0169] The above-mentioned liquefied organic material can be discharged to the outside through a recovery pipe (L41, L42) installed at the bottom of the plurality of chillers (721, 722).

[0170] The gas from which organic components have been removed by the above plurality of chillers (721, 722) can be filtered to include inorganic components in the second filter (73) equipped with an activated carbon filter.

[0171] When the heat treatment is completed, the control unit (800) can turn off the heater (412) and use the vertical transfer device (300) to move the crucible (100) and the plate (110) supporting it to the lower end of the opening (421).

[0172] The control unit (800) can move the crucible (100) and plate (110) loaded with the heat-treated lithium sulfide powder back to the first transfer path (91) via the mover (200).

[0173] The control unit (800) can open the third sealing window (51) of the unloading chamber (50) that seals the passage connected to the first transfer path (91) to bring the crucible (100) and plate (110) loaded with the heat-treated lithium sulfide powder into the unloading chamber (50).

[0174] The control unit (800) can close the third sealed window (51) after insertion.

[0175] The control unit (800) can open the fourth sealing window (52) that seals the passage on the side of the second loading unit (22) after closing the third sealing window (51).

[0176] The control unit (800) can move the crucible (100) and plate (110) loaded with the heat-treated lithium sulfide powder to the second loading unit (22) after protruding the mover (200) installed at the bottom of the third transfer path (93) at the bottom of the unloading chamber (50).

[0177] The control unit (800) can move the mover (200) to the bottom of the third transfer path (93) when the crucible (100) and plate (110) loaded with the heat-treated lithium sulfide powder are moved to the second loading unit (22).

[0178] The control unit (800) can drive the discharge device (33) installed on one side of the unloading chamber (50) to discharge air or argon gas that has penetrated into the unloading chamber (50) while the fourth sealing window (52) is open, thereby creating a vacuum state identical to that of the sealing body (500).

[0179] The control unit (800) can discharge argon gas through the second discharge port (24) installed inside the second loading unit (22) to prevent the heat-treated lithium sulfide powder inside the second loading unit (22) from being exposed to air or moisture.

[0180] Inside the second loading section (22), the purified lithium sulfide powder can be vacuum-packed or XRD analysis can be performed.

[0181] The control unit (800) receives the concentration of lithium hydroxide inside the lithium sulfide powder obtained through the XRD analysis and can adjust the vacuum level of the seal (500), loading chamber (30), or unloading chamber (50) or the driving speed of the first vacuum pump (81).

[0182] It may be preferable to set the spacing between the crucibles (100) loaded with unrefined lithium sulfide supplied from the above supply unit to be greater than the minimum spacing between the vertical furnaces (40).

[0183] This is because, in an ideal situation where not all vertical furnaces (40) undergo a heat treatment process simultaneously, this is the minimum interval at which unrefined lithium sulfide on the first transfer furnace (91) can be simultaneously fed into the vertical furnaces (40).

[0184] As described above, the first transfer path (91) can be set to transfer the crucible (100) and plate (110) at a constant speed by means of a rotating roller (90).

[0185] This is because frequent acceleration and deceleration of the first transport path (91) can cause acceleration to be applied to the crucible (100), which can lead to an accident in which lithium sulfide loaded inside leaks out.

[0186] Therefore, it is important that the transfer speed of the first transfer path (91) is initially set so that it does not fluctuate as much as possible.

[0187] The control unit (800) can set the minimum speed of the first transfer path (91) to a speed at which the crucible (100) moves on the first vertical path (40) by more than the distance between the vertical paths (40) during the time that the vertical path (40) heat-treats the unpurified lithium sulfide.

[0188] This is because the above minimum speed is the speed at which the first transfer path (91) can move without stopping while all vertical paths (40) are performing the heat treatment process.

[0189] If the above minimum speed is not set, the operation of the supply unit supplying the above unrefined lithium sulfide will also become unpredictable in terms of supply speed, resulting in a decrease in overall production efficiency.

[0190] Likewise, the control unit (800) can be set to the maximum speed of the first transfer path (91) at the speed at which the crucible (100) moves from the supply section to the discharge section on the first vertical path (40) during the time that the vertical path (40) heat-treats the unpurified lithium sulfide.

[0191] This is set up by assuming a case where a vertical furnace (40) capable of heat-treating a crucible (100) that has entered the first transfer path (91) through the supply section is located near the discharge section.

[0192] Of course, it is obvious that the transfer speed of the first transfer path (91) can be adjusted by the control unit (800) due to reasons such as a malfunction of the vertical path (40) or a change in the supply speed of unrefined lithium sulfide in the supply unit.

[0193] The first loading section (21) and the second loading section (22) specified in the detailed description of the present invention may be formed in the shape of a glove box according to the embodiment to facilitate the supply and packaging of lithium sulfide.

[0194]

[0195] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. In a system that heat-treats lithium sulfide in a plurality of vertical furnaces (40) equipped with heaters (412) inside and is controlled by a control unit (800), A first step of passing a crucible (100) loaded with unrefined lithium sulfide through a first transfer path (91) positioned at the lower side of the plurality of vertical paths (40) at a constant speed; Step 2, identifying a vertical furnace (40) among the plurality of vertical furnaces (40) for which heat treatment has not been performed; A third step of introducing the crucible (100) loaded with the above unrefined lithium sulfide into the vertical furnace (40) where heat treatment is not performed; A fourth step of purifying the above unrefined lithium sulfide by heat treating it inside the vertical furnace (40); and A lithium sulfide heat treatment method comprising: a fifth step of withdrawing the crucible (100) loaded with the refined lithium sulfide from the vertical furnace (40) and transferring it to the first transfer path (91).

2. In Claim 1, A method for heat treating lithium sulfide, characterized in that the control unit (800) introduces the crucible (100) loaded with unrefined lithium sulfide into the vertical furnace (40) closest to the crucible (100) loaded with unrefined lithium sulfide passing through the first transfer path (91) and the heat treatment not performed therein.

3. In Claim 1, A lithium sulfide heat treatment method characterized in that one end of the first transfer path (91) is connected to a supply unit, and the supply unit supplies a plate (110) on which a crucible (100) loaded with unrefined lithium sulfide is placed to the first transfer path (91).

4. In Claim 3, A lithium sulfide heat treatment method characterized in that the other end of the first transfer path (91) is connected to a discharge section, and the first transfer path (91) supplies to the discharge section a plate (11) on which the crucible (100) loaded with lithium sulfide powder refined by heat treatment in the vertical furnace (40) is placed.

5. In Claim 4, A method for heat treating lithium sulfide, characterized in that the control unit (800) lowers the transfer speed of the first transfer path (91) when it is expected that the unpurified lithium sulfide passing through the first transfer path (91) will not be introduced into the vertical furnace (40) where heat treatment is not performed until the crucible (100) loaded with the unpurified lithium sulfide is reached at the discharge section.

6. In Claim 1, A lithium sulfide heat treatment method characterized in that the first transfer path (91) is composed of a plurality of rotating rollers (90).

7. In Claim 4, A lithium sulfide heat treatment method characterized in that the control unit (800) sets the spacing between crucibles (100) loaded with unrefined lithium sulfide supplied from the supply unit to be at least greater than the spacing between the vertical furnaces (40).

8. In Claim 4, A method for heat treating lithium sulfide, characterized in that the control unit (800) sets the minimum speed of the first transfer path (91) to a speed at which the crucible (100) moves on the first vertical path (40) by a distance greater than the gap between the vertical paths (40) during the time that the vertical path (40) heat treats the unrefined lithium sulfide.

9. In Claim 4, A method for heat treating lithium sulfide, characterized in that the control unit (800) sets the maximum speed of the first transfer path (91) to the speed at which the crucible (100) moves from the supply section to the discharge section on the first vertical path (40) during the time that the vertical path (40) heat treats the unrefined lithium sulfide.

10. In either claim 8 or 9, A method for heat treating lithium sulfide, characterized in that the time for the vertical furnace (40) to heat treat the unrefined lithium sulfide is the time required from when the crucible (100) loaded with the unrefined lithium sulfide is transferred from the first transfer furnace (91) to the vertical furnace (40) and heat treated, until when the crucible (100) loaded with refined lithium sulfide is re-transferred to the first transfer furnace (91).

11. A control unit (800) that controls the lithium sulfide heat treatment process equipment; A vertical passage (40) having an opening (421) through which lithium sulfide can move vertically downward and a first discharge port (420) through which impurities can be discharged vertically upward; A heater (412) installed on one side of the inner surface of the above vertical furnace (40); A vertical transfer device (300) that moves up and down vertically and moves lithium sulfide into and out through the opening (421); A first transfer path (91) installed at a lower side spaced a predetermined distance from the vertical path (40) and moving a plate (110) on which a crucible (100) loaded with lithium sulfide is placed using a plurality of rollers (90); A supply unit connected to one end of the first transfer path (91) and supplying a plate (110) on which a crucible (100) loaded with unrefined lithium sulfide is placed to the first transfer path (91); and A lithium sulfide heat treatment system comprising a discharge section connected to the first transfer path (91) and receiving a plate (11) on which a crucible (100) loaded with refined lithium sulfide heat-treated in the vertical path (40) is placed.

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