Apparatus and method for recycling lithium-ion battery using dry heat treatment method based on hydrogen-containing gas

Abstract

Disclosed is a method according to various embodiments of the present invention in order to achieve the described objective. The method comprises the steps of: inputting a storage unit having an object received therein into a heating apparatus; and performing a heat treatment on the object by controlling a heating unit provided in the heating apparatus, wherein the heat treatment may be performed in an atmosphere of a hydrogen-containing gas which comprises hydrogen.

Description

Lithium-ion battery recycling device and method using a dry heat treatment method based on a functional gas

[0001] The present invention relates to a technology for recycling waste batteries, and more specifically, to a lithium-ion battery recycling device and method using a dry heat treatment process using hydrogen gas.

[0002] As the global movement toward electric vehicles accelerates in line with carbon neutrality declarations, the use of battery packs containing multiple battery cells is increasing, and the need for research on battery recycling methods is also growing.

[0003] Meanwhile, secondary batteries have high energy density and minimal self-discharge, making them widely used in portable electronic devices and electric vehicles. Unlike primary batteries, secondary batteries operate through reversible oxidation and reduction reactions, allowing them to be recharged. In particular, lithium-ion secondary batteries, due to their high energy density, enable miniaturization and weight reduction, and their high electromotive force and minimal memory effect ensure long lifespans. For these reasons, lithium-ion secondary batteries are being utilized in a wide range of fields, and the disposal of used batteries is rapidly increasing, with an estimated 5.7 million electric vehicle batteries being generated by 2040. Secondary batteries contain valuable metals such as cobalt, nickel, manganese, and lithium, raising concerns about their loss and environmental pollution during disposal. Therefore, technologies for recovering these valuable metals are crucial for resource conservation and environmental protection.

[0004] Meanwhile, dry heat treatment processes for lithium-ion battery recycling are typically performed in a gaseous atmosphere containing carbon monoxide and carbon dioxide. However, heat treatment processes performed in a gaseous environment containing carbon monoxide and carbon dioxide have limited effectiveness in reducing certain cathode active materials. For example, while NMC (nickel, manganese, cobalt)-based batteries can be effectively reduced, LFP (lithium, iron, phosphate) batteries undergo insufficient or very slow reduction under conventional heat treatment conditions. This is because LFP has a higher reducibility than other existing cathode active materials.

[0005] Accordingly, research and development of heat treatment in other gas atmospheres that can provide stronger reduction driving force and improve reaction rate are required.

[0006] Various embodiments of the present invention are intended to solve the above problems, and to provide a dry heat treatment process method capable of promoting an efficient reduction reaction by providing a gas atmosphere capable of more effectively inducing reduction of various positive electrode active materials, including LFP batteries.

[0007] The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0008] To address the above-described challenges, a lithium-ion battery recycling method utilizing a dry heat treatment method based on a hydrogen-containing gas is disclosed, according to various embodiments of the present invention. The method comprises the steps of: introducing a storage unit containing an object into a heating device; and controlling a heating unit provided in the heating device to perform heat treatment on the object. The heat treatment may be characterized in that it is performed in a hydrogen-containing hydrogen gas atmosphere.

[0009] In an alternative embodiment, the functional gas is composed of a combination of the hydrogen and an inert gas, and the step of performing a heat treatment on the object is characterized in that the heat treatment is performed in the functional gas atmosphere, and the heat treatment is performed based on a preset hydrogen content condition and a preset temperature condition, wherein the preset hydrogen content condition is a condition in which the hydrogen is at least 30 parts by weight or more with respect to 100 parts by weight of the total functional gas, and the preset temperature condition may include a temperature condition in which the temperature corresponding to the heat treatment is at least 760°C or more and at most less than 1000°C.

[0010] In an alternative embodiment, the step of performing a heat treatment on the object is characterized in that the heat treatment is performed in the functional gas atmosphere, and the heat treatment is performed based on a preset hydrogen content condition and a preset temperature condition, wherein the preset hydrogen content condition is a condition in which the hydrogen is at least 50 parts by weight or more with respect to 100 parts by weight of the total functional gas, and the preset temperature condition may include a temperature condition in which a temperature corresponding to the heat treatment is at least 900°C or more.

[0011] In an alternative embodiment, the heating device includes a work section that performs a heat treatment operation on the object, wherein the work section is characterized by having a vertical kiln structure that vertically moves each of one or more storage sections, and the object is heat treated while sequentially passing through each of the one or more storage sections, and can be heat treated in the nitrous gas atmosphere supplied into the work section.

[0012] In an alternative embodiment, when the object is an LFP battery, the heat-treated object is characterized in that it is separated into lithium phosphate (Li3PO4) and a reduction byproduct (Fe2P), and the method may include a step of performing a leaching process for the lithium phosphate and a step of performing a magnetic separation process for the reduction byproduct.

[0013] A lithium-ion battery recycling device utilizing a dry heat treatment method based on a hydrogen-containing gas according to another embodiment of the present invention is disclosed. The lithium-ion battery recycling device may include an input unit into which a storage unit containing an object is input, a heating unit for heating the object, an exhaust unit for discharging the heated object, a gas supply unit for supplying a hydrogen-containing hydrogen gas into a space where the object is heated, and a control unit for controlling the heating unit.

[0014] In an alternative embodiment, the functional gas is configured through a combination of the hydrogen and the inert gas, and the control unit is characterized in that it controls the heating unit so that heat treatment is performed on the object based on a preset hydrogen content condition and a preset temperature condition, wherein the preset hydrogen content condition is a condition in which the hydrogen is at least 30 parts by weight or more with respect to 100 parts by weight of the total functional gas, and the preset temperature condition may include a temperature condition in which the temperature corresponding to the heat treatment is at least 760°C or more and at most less than 1000°C.

[0015] In an alternative embodiment, the present invention further comprises a work section that performs a heat treatment operation on the object, wherein the work section is characterized by having a vertical kiln structure that vertically moves each of one or more storage sections, and the object is heat treated while sequentially passing through each of the one or more storage sections, and can be heat treated in the nitrous oxide gas atmosphere supplied into the work section.

[0016] In an alternative embodiment, when the object is an LFP battery, the heat-treated object is characterized in that it is separated into lithium phosphate and a reduction by-product, and the lithium ion battery recycling device may further include a leaching device that performs a leaching process for the lithium phosphate and a magnetic separation device that performs a magnetic separation process for the reduction by-product.

[0017] Other specific details of the present invention are included in the detailed description and drawings.

[0018] According to an embodiment of the present invention, the reduction reaction of an LFP battery, which is a reducing material, can be effectively performed, and the overall efficiency of the valuable metal recovery process is improved.

[0019] Furthermore, the present invention minimizes the loss of valuable metals during the recycling process of used batteries, thereby maximizing the recovery rate. This not only contributes to the efficient use of resources but also increases economic value.

[0020] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

[0021] Various aspects are described with reference to the drawings, wherein like reference numerals are used to refer to similar components generally. In the following examples, for purposes of explanation, numerous specific details are set forth to provide a comprehensive understanding of one or more aspects. However, it will be apparent that such aspects may be practiced without these specific details.

[0022] FIG. 1 illustrates an exemplary flowchart of a lithium ion battery recycling method utilizing a dry heat treatment method based on a functional gas according to one embodiment of the present invention.

[0023] Figure 2 illustrates an exemplary cross-sectional view of a heating device related to one embodiment of the present invention.

[0024] FIG. 3 illustrates a cross-sectional view of a working section and a discharge section according to one embodiment of the present invention.

[0025] Figure 4 illustrates experimental results showing that a reduction reaction is not sufficiently performed in a conventional heat treatment method related to one embodiment of the present invention.

[0026] FIG. 5 illustrates experimental results for explaining the reduction efficiency according to temperature during heat treatment of a functional element-based LFP cathode active material according to one embodiment of the present invention.

[0027] FIG. 6 and FIG. 7 illustrate experimental results for explaining reduction efficiency according to hydrogen concentration at a temperature of 800°C during heat treatment of a functional element-based LFP cathode active material. FIG. 8 illustrates experimental results for explaining reduction efficiency according to hydrogen concentration at a temperature of 800°C during heat treatment of a functional element-based LFP cathode active material related to one embodiment of the present invention.

[0028] FIG. 9 shows experimental results for explaining the reduction efficiency according to hydrogen concentration at a temperature of 760°C during heat treatment of a functional element-based LFP cathode active material according to one embodiment of the present invention.

[0029] Figures 10 and 11 illustrate experimental results for explaining the reduction efficiency according to hydrogen concentration at a temperature of 700°C during heat treatment of a functional-based LFP cathode active material. Figure 12 illustrates experimental results for explaining the optimal heating conditions of an LFP cathode active material related to one embodiment of the present invention.

[0030] Figure 12 shows the experimental results to explain the mass change process according to hydrogen concentration.

[0031] Figure 13 shows the experimental results for explaining the reduction efficiency according to hydrogen concentration at a temperature of 900°C during heat treatment of a functional element-based LFP cathode active material related to one embodiment of the present invention.

[0032] FIG. 14 illustrates a flowchart exemplarily showing a process for obtaining valuable metals from waste batteries related to LFP according to one embodiment of the present invention.

[0033]

[0034] Various embodiments and / or aspects are now disclosed with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of one or more aspects. However, it will be apparent to one skilled in the art that the aspect(s) may be practiced without these specific details. The following description and the accompanying drawings detail specific exemplary aspects of one or more aspects. However, these aspects are exemplary, and any of the various methods within the principles of the various aspects may be utilized, and the description is intended to encompass all such aspects and their equivalents. Specifically, the terms "embodiment," "example," "aspect," and "example" as used herein are not intended to imply that any aspect or design described therein is preferred or advantageous over other aspects or designs.

[0035] Hereinafter, regardless of the drawing numbers, identical or similar components are assigned the same reference numerals, and redundant descriptions thereof are omitted. Furthermore, when describing the embodiments disclosed in this specification, if a detailed description of a related known technology is judged to obscure the gist of the embodiments disclosed in this specification, the detailed description thereof will be omitted. Furthermore, the attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in this specification, and the technical concepts disclosed in this specification are not limited by the attached drawings.

[0036] Although the terms "first," "second," etc. are used to describe various elements or components, these elements or components are not limited by these terms. These terms are merely used to distinguish one element or component from another. Accordingly, it should be understood that a "first element or component" referred to below may also be a "second element or component" within the technical scope of the present invention.

[0037] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used in their common sense to those of ordinary skill in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0038] Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless otherwise specified or clear from context, "X employs A or B" is intended to mean either of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, "X employs A or B" can apply to any of these cases. Furthermore, the term "and / or" as used herein should be understood to refer to and include all possible combinations of one or more of the associated items listed.

[0039] Additionally, it should be understood that the terms "comprises" and / or "comprising" imply the presence of a given feature and / or component, but do not preclude the presence or addition of one or more other features, components, and / or groups thereof. Furthermore, unless otherwise specified or clear from context to refer to the singular form, the singular form in the specification and claims should generally be construed to mean "one or more."

[0040] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0041] When an element or layer is referred to as being "on" or "on" another element or layer, this includes not only directly on the other element or layer, but also whether or not there are other intervening elements or layers. Conversely, when an element is referred to as being "directly on" or "directly on" the other element or layer, this means that there are no intervening elements or layers.

[0042] Spatially relative terms such as "below," "beneath," "lower," "above," and "upper" may be used to easily describe the relationship between one component or another as depicted in the drawings. Spatially relative terms should be understood to include different orientations of the component during use or operation in addition to the orientation depicted in the drawings.

[0043] The purposes and effects of the present invention, as well as the technical configurations for achieving them, will become clearer with reference to the embodiments described in detail below, along with the accompanying drawings. In describing the present invention, detailed descriptions of known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the invention. Furthermore, the terms described below are defined based on their functions in the present invention and may vary depending on the intentions or practices of the user or operator.

[0044] However, the present invention is not limited to the embodiments disclosed below and can be implemented in various other forms. These embodiments are provided solely to ensure the completeness of the present invention and to fully inform those skilled in the art of the scope of the disclosure. The present invention is defined solely by the scope of the claims. Therefore, such definitions should be based on the contents of this specification.

[0045]

[0046] FIG. 1 is a flowchart illustrating an exemplary method for recycling lithium-ion batteries using a dry heat treatment method based on a functional gas according to one embodiment of the present invention. According to one embodiment of the present invention, the method for recycling lithium-ion batteries using a dry heat treatment method based on a functional gas may include the steps illustrated in FIG. 1. The order of the steps illustrated in FIG. 1 may be changed as needed, and at least one step may be omitted or added. In other words, the following steps are merely an embodiment of the present invention, and the scope of the rights of the present invention is not limited thereto.

[0047] According to one embodiment of the present invention, a method for recycling a lithium ion battery using a dry heat treatment method based on a functional gas may include a step (S100) of introducing a storage unit containing an object into a heating device.

[0048] In the present invention, the target object is a used lithium-ion battery that has been discarded, and may include, but is not limited to, a battery pack for an electric vehicle or a battery used in a portable electronic device. In an embodiment, batteries from large-scale energy storage systems (ESS) used for industrial or commercial purposes may also be included as a target object in the recycling process of the present invention. In other words, the present invention can be applied to lithium-ion batteries of various types and sizes, and thus can be widely utilized in various applications. These used batteries can contain various valuable metals such as cobalt, nickel, manganese, and lithium, along with high energy density.

[0049] In one embodiment, the storage unit may be structured to safely and efficiently accommodate a spent lithium-ion battery and facilitate its introduction into the heating device. The storage unit may ensure sufficient strength and flexibility to accommodate expansion or other physical changes that may occur during the heat treatment process, while still allowing the object to be safely moved within the heating device.

[0050] In one embodiment, the storage unit is configured to form an internal storage space for receiving the object, and the internal storage space can be formed into various compartments that can be adjusted to suit the shape and size of the battery. This compartmentalization can enhance safety and improve the efficiency of the recycling process by preventing physical damage or chemical reactions that may occur when individual batteries come into contact with each other during the heat treatment process. In addition, the storage unit is constructed of a heat-resistant material that can withstand high temperatures, thereby withstanding the high temperatures generated during the heat treatment process and protecting the batteries within. The structure of the storage unit also optimizes the flow of the mixed gas during the heat treatment process, ensuring that the gas uniformly contacts all batteries within the internal storage space, thereby enhancing the efficiency and uniformity of the heat treatment.

[0051] In addition, in an embodiment, a lithium-ion battery recycling method utilizing a dry heat treatment method based on a functional gas may include a step (S200) of performing heat treatment on an object by controlling a heating unit provided in a heating device (100).

[0052] According to an embodiment, the heating device (100) may include a work section that performs a heat treatment operation on an object. The work section may be characterized by having a vertical kiln structure in which each of one or more storage sections moves vertically. According to an embodiment, a heating section may be provided inside the work section, and heating or heat treatment may be performed on the object through a temperature change of the heating section. In an embodiment, the object may be characterized by being heat treated while sequentially passing through each of one or more storage sections, and being heat treated in a hydrated gas atmosphere supplied into the work section.

[0053] The heating device (100) of the present invention has a vertical kiln structure, and can enable a continuous and uniform heat treatment process by vertically moving one or more storage sections containing the object. The storage sections are sequentially heated by the heating section of the heating device, and during this process, a mixed gas containing hydrogen (e.g., hydrogen gas) is supplied into the working section. This configuration ensures even and efficient heat transfer to the object, and provides essential conditions for effectively reducing valuable metals in lithium-ion batteries. The vertical kiln structure also optimizes the flow of gases that may be generated during the heat treatment process, thereby helping to uniformly heat the object and maximizing the heat treatment efficiency. A more specific description of the process of performing heat treatment on the object using the heating device (100) will be described below with reference to FIGS. 2 and 3 .

[0054] Referring to FIG. 2, the heating device (100) may include an object input port (110) into which a storage unit containing an object is input, a work unit connected to the object input port (110) and moving the storage unit in a vertical direction, a heating unit (130) provided inside the work unit to heat the object, an object discharge unit (150) located at the bottom of the work unit to discharge the heated object, and a control unit that controls the heating unit (130).

[0055] A heating device (100) according to the present invention is for heating a storage unit containing an object corresponding to a waste lithium ion battery to obtain necessary raw materials (i.e., valuable metals), and includes an object input port (110) for waiting to input the storage unit into a work unit, a work unit for positioning the storage unit and performing a heating operation, and an object discharge unit (150) for withdrawing the storage unit, for which a firing operation has been completed, from the work unit.

[0056] The target object insertion port (110) includes an insertion section for inserting the storage section into the interior and a waiting section for the storage section inserted into the interior to wait before being inserted into the work section.

[0057] In an embodiment, the work unit (120) may be composed of a first work unit (121), a second work unit (122), and a third work unit (123) arranged in the vertical direction.

[0058] The storage unit (20) containing the object is fed into the working unit through the object input port (110), and in this process, a fixed position arrangement and exhaust process for easier firing can be performed.

[0059] The storage section is moved from the object input port (110) to the work section, and a vertical heating process is applied while passing through the first work section (121), the second work section (122), and the third work section (123) sequentially.

[0060] The heated storage section is moved from the work section to the object discharge section (150), refined through the injection of a designated gas, cooled through the injection of a cooling gas, and discharged to the outside.

[0061] In the process of processing an object loaded into a storage unit through the above configurations, the control unit controls the operation of the object inlet (110) and the work unit, and this can be implemented in various ways, such as adjusting the temperature increase speed within the work unit, adjusting the gas partial pressure, and operating the components within the object inlet (110) and the object discharge unit (150). Here, the control unit can control at least one of the temperature increase speed and the temperature increase time targeting the heating unit.

[0062] The target object input port (110) is connected to the work section and is configured to supply the storage section, and includes an insertion section, a waiting section, and a first opening / closing section.

[0063] Referring to FIGS. 2 and 3, the working section is configured to provide a space for heating an object while the storage section is positioned inside. To this end, the working section is formed in a cylindrical shape with vertical openings, and a heating section, a refractory section, and a temperature measuring section (124) are positioned inside, thereby inducing the object and the storage section to be heated simultaneously. In addition, the working section is composed of a first working section (121), a second working section (122), and a third working section (123), which are arranged vertically.

[0064] The first working section (121) provides a space for performing an initial heating process on a storage section introduced from the waiting section. To this end, the first working section (121) is provided with a first internal temperature, and a second working section (122) is provided at a lower side thereof, and the first working section (121) and the second working section (122) are connected to each other. The second working section (122) is located below the first working section (121) and has a second internal temperature, thereby performing a process of secondary heating of the storage section. The second working section (122) is connected to the first working section (121) and the third working section (123), respectively. The third working section (123) is provided at a lower side of the second working section (122), and a process of secondary heating of the storage section with the third internal temperature is performed.

[0065] As another embodiment of the present invention, a mooring unit positioned downward of the third working section (123) may be further included. The mooring unit is configured to temporarily moor the heated object and storage section through the first working section (121) to the third working section (123) to prevent unintended thermal deformation. To this end, the mooring unit is configured in the same form as the first working section (121) to the third working section (123), but does not include a heating section, which will be described later. Therefore, natural cooling can be induced without additional heating of the object and storage section.

[0066] The heating unit is a means installed in the work section to heat the object and the storage section, and more specifically, it is a configuration for melting the object. To this end, the heating unit may be configured with a SIC heater capable of generating heat at a high temperature, but is not limited thereto. The heating unit may be an induction heating device supplied with high and low frequency power. For example, the heating unit may be configured with an induction heating device using a metal coil such as copper. However, the heating unit is not limited thereto, and may include a suitable heating device (e.g., a furnace or an electric furnace capable of mass processing) capable of stably increasing the temperature and maintaining the temperature.

[0067] According to one embodiment, the heating unit may be provided with a plurality of heating units that perform different temperature controls according to the height of the working unit. The heating unit is composed of a first heating unit (131), a second heating unit (132), and a third heating unit (133), and is respectively disposed inside the first working unit (121), the second working unit (122), and the third working unit (123). Here, the first heating unit (131), the second heating unit (132), and the third heating unit (133) can be independently or integrally driven by a control unit to be described later to heat the object and the storage unit to the first internal temperature, the second internal temperature, and the third internal temperature.

[0068] As another embodiment of the present invention, at least one of the first heating unit (131), the second heating unit (132), and the third heating unit (133) may be configured in multiple units and arranged in a circular arrangement centered on a central axis in the vertical direction of the working unit. Accordingly, it is possible to reduce the amount of heating units used and at the same time create a uniform first internal temperature, a second internal temperature, and a third internal temperature. In addition, the first heating unit (131), the second heating unit (132), and the third heating unit (133) may be driven independently or integrally by the control unit.

[0069] The refractory portion is configured to prevent the heating portion from being deteriorated by the object being heated within the working portion and to prevent rapid changes in internal temperature. To this end, the refractory portion is arranged to surround or be close to the heating portion, as illustrated in Fig. 3. The refractory portion is provided for the first heating portion (131), the second heating portion (132), and the third heating portion (133), and is configured as the first refractory portion (141), the second refractory portion (142), and the third refractory portion (143) depending on the arrangement position.

[0070] The first refractory section (141) is configured to protect the inner direction of the heating section, which is provided in multiple units. Specifically, the first refractory section (141) is positioned in the inner direction toward the central axis of the first working section (121), the second working section (122), and the third working section (123) with respect to the first heating section (131), the second heating section (132), and the third heating section (133). That is, the first refractory section (141) is positioned to correspond to the portions facing inward of the first heating section (131), the second heating section (132), and the third heating section (133), thereby preventing the heating section from being deteriorated by foreign substances during the heating process of the object.

[0071] The second refractory section (142) performs the same role as the first refractory section (141) described above, but is provided to surround the first heating section (131), the second heating section (132), and the third heating section (133). For example, when the first heating section (131) to the third heating section (133) have an arc cross-section, the cross-section of the second refractory section (142) has a shape that accommodates the arc cross-section to surround it. Accordingly, the second refractory section (142) can not only prevent deterioration from foreign substances entering from all directions, but also prevent deterioration due to radiant heat.

[0072] The third refractory section (143) performs the same role as the first refractory section (141) and the second refractory section (142) described above, but is arranged in the outer direction of the first heating section (131), the second heating section (132), and the third heating section (133). Accordingly, it has a horizontal cross-sectional arrangement structure in which the first refractory section (141), the heating section, the second refractory section (142), and the third refractory section (143) are sequentially arranged in order of proximity from the central axis of the working section.

[0073] The temperature measuring unit (124) measures the temperature of the working unit or heating unit, and based on this, the control unit, which will be described later, controls the internal temperature of the working unit. To this end, the temperature measuring unit (124) may be located within the working unit. Here, the temperature measuring unit (124) may be installed in combination with a separate deterioration prevention means that is not damaged by high temperatures as a separate temperature sensing means.

[0074] The temperature measuring unit (124) is provided between the first working unit (121) and the second working unit (122), between the second working unit (122) and the third working unit (123), and in the lower direction of the third working unit (123). Accordingly, each temperature measuring unit (124) can measure the internal temperature of the first working unit (121), the second working unit (122), and the third working unit (123).

[0075] As another embodiment of the present invention, the temperature measuring units (124) may be installed in the first working unit (121) to the third working unit (123), and may all have the same installation location. That is, the temperature measuring units (124) installed in the first working unit (121) to the third working unit (123) respectively have the same horizontal distance from the central axis of the working unit and the same vertical separation distance from each other. Accordingly, the occurrence of thermal measurement errors can be minimized when each temperature measuring unit (124) measures the internal temperature of the working unit.

[0076] The object discharge unit (150) is a configuration for discharging the object from the work unit and is located in the lower direction of the work unit. Accordingly, the object input port (110), the work unit, and the object discharge unit (150) are connected to each other and have a vertical heating structure, which has the effect of facilitating the movement of the object and the gas required to heat the object, compared to a conventional horizontal heating structure.

[0077] In addition, in the object discharge unit (150), gas for heating the object is initially injected, and the gas (previously designated gas) moves upward to induce plasticity of the object, and then moves to the object injection port (110) and is discharged.

[0078] The object discharge unit (150) includes a vertical moving unit (151) for taking out the object, a second pressurized moving unit (152) for moving the object under pressure, a gas supply unit (153) for injecting a designated gas (e.g., a hydrocarbon gas), a second opening / closing unit (154) for partitioning an internal space, a second gas discharge unit (155) for ventilating the space partitioned by the second opening / closing unit (154), and a cooling unit (156) for cooling the object.

[0079] The vertical movement unit (151) is configured to move the position of the object from the inside of the work section to the inside of the object discharge section (150), and moves the storage section containing the object and the object in the vertical direction while supporting it. To this end, the vertical movement unit (151) may be configured as a multi-stage support means whose length in the vertical direction can be adjusted using electricity or hydraulic pressure, and the upper end may be configured in the shape of a plate for more solid contact with the storage section. After the storage section with the object placed inside is heated by the heating section inside the work section, the storage section moves downward as one unit with the vertical movement unit (151).

[0080] The second pressurized moving unit (152) is configured to pressurize and move an object placed in the internal space of the object discharge unit (150) and a storage unit containing the object by moving in a lateral direction, and is provided in the same manner as the first pressurized moving unit (111a).

[0081] The gas supply unit (153) is configured to inject a predetermined gas for the purpose of sintering the object into the object discharge unit (150), and is configured as a separate injection means including a pump that induces the movement of a fluid such as a gas, but is not limited thereto. Here, the predetermined gas is provided as at least one of carbon monoxide, carbon dioxide, and argon that can induce heat treatment of the object while creating an inert gas atmosphere.

[0082] The second opening / closing section (154) is configured to divide the internal space of the object discharge section (150) into two or more, and to use each internal space for the purpose of holding the storage section and cooling the storage section, and has the same configuration as the first opening / closing section (113) described above.

[0083] By closing the second opening and closing section (154), the interior space of the work section can be divided into a holding space connected to the working section and a post-processing space disconnected from the working section. The gas supply section (153) described above is formed corresponding to the holding space, and the post-processing space can be equipped with a second gas target discharge section (150) and a cooling section (156).

[0084] The second gas discharge unit (155) is configured to ventilate at least one of the partitioned internal spaces of the object discharge unit (150), and may be configured as a discharge module including a discharge pump, but is not limited thereto. When the second opening / closing unit (154) described above is opened, the second gas discharge unit (155) can ventilate all internal spaces of the object discharge unit (150). Additionally, when the second opening / closing unit (154) is closed, the second gas discharge unit (155) can ventilate only the internal air of the post-processing space.

[0085] The cooling unit is configured to cool the object and storage unit placed in the post-processing space, and is configured with a spraying means capable of spraying a gas having a predetermined temperature. The object and storage unit are cooled by air cooling, thereby preventing damage such as unintended cracks. Here, the predetermined temperature is configured to be 50 to 100 degrees Celsius or lower, but may be configured to be a temperature that decreases by 10 degrees Celsius per hour, but is not limited thereto.

[0086] A space is secured between the upper and lower storage sections into which a fixing member (160) can be inserted. The fixing member (160) prevents unintentional movement of the vertical position of the storage section containing the object and being heated as a whole. To this end, the fixing member (160) is configured in the form of a plate located in the lower direction of the storage section within the working section and having a structure in which the upper surface contacts the lower surface of the storage section. In addition, in order to more firmly fix the height of the storage section, the fixing members (160) may be provided in multiple pieces and arranged in a circular arrangement centered on the central axis of the working section.

[0087] The fixing member (160) is additionally provided and positioned in the upper direction of the storage unit, thereby enabling height fixation with respect to another storage unit located in the upper direction.

[0088] The control unit controls the operation of the heating unit, and can control the internal temperature of the working unit while connected to a temperature measuring unit (124) that measures the temperature of the heating unit.

[0089] The temperature measuring unit (124) located inside the working unit measures the first temperature, the second temperature and the third temperature corresponding to the first working unit (121), the second working unit (122) and the second working unit (122), respectively, and the control unit compares the measured first temperature, the second temperature and the third temperature with the first internal temperature, the second internal temperature and the third internal temperature specified in advance.

[0090] First, the control unit compares the second temperature and the second internal temperature, and controls the operation of the second heating unit (132) based on the comparison result.

[0091] When the second temperature is greater than the second internal temperature, the control unit calculates the heating rate of the second heating unit (132) and controls the operation of the heating unit to heat the object according to the predetermined optimal heating rate.

[0092] When the second temperature is the same as the second internal temperature, the control unit controls the second heating unit (132) to continuously heat the object at the optimal heating rate.

[0093] When the second temperature is lower than the second internal temperature, the control unit calculates the heating rate of the second heating unit (132) and controls the operation of the second heating unit (132) so that the calculated heating rate matches the optimal heating rate. Here, after the second heating unit (132) is operated so that the heating rate of the second heating unit (132) is greater than the optimal heating rate for a predetermined time (e.g., 10 seconds), the heating rate of the second heating unit (132) is controlled so that the heating rate matches the optimal heating rate, thereby making it easier to induce cracking and reduction of the object.

[0094] After the operation control of the second heating unit (132) based on the comparison of the second temperature and the second internal temperature as described above, the control unit controls the operation of the first heating unit (131) in the same manner based on the result of comparing the first temperature and the first internal temperature, and can then control the operation of the third heating unit (133) in the same manner based on the result of comparing the third temperature and the third internal temperature.

[0095] The reason for controlling the internal temperature of the second working section (122) among the first working section (121) to the third working section (123) first is to maximize the thermal efficiency of the second working section (122) where the object is heated and reduced first.

[0096] When the need for preheating of the object is high, the control of the first heating unit (131) is performed after adjusting the internal temperature of the second working unit (122), and when the need for reduction of the object is higher, the control of the third heating unit (133) may be performed first after the control of the second heating unit (132). In various embodiments, the first heating unit (131) may perform temperature control for preheating, and the third heating unit (133) may perform temperature control for reduction. That is, the order of the control of the first heating unit (131) or the control of the third heating unit (133) may vary depending on the input amount and input type of the object.

[0097] By controlling the operation of each heating unit based on the temperature measured for each of the first working unit (121), the second working unit (122), and the third working unit (123), it is possible to prevent the thermal efficiency of the target object from being reduced in advance.

[0098] The control unit creates and controls the working environment of the work unit during the process of recovering valuable metals composed of at least one of cobalt (Co), nickel (Ni), manganese (Mn), and lithium (Li) by heating the object. Specifically, the control unit controls the operation of the gas supply unit (153) described above to induce a predetermined gas to be injected into the interior of the object discharge unit (150). Thereafter, the predetermined gas moves along the work unit located upward from the object discharge unit (150), and during the movement process, it comes into contact with the object to create a reducing gas atmosphere.

[0099] The working unit, which is composed of the first working unit (121) to the third working unit (123), may be characterized in that it performs heat treatment in a hydrogen-containing gas atmosphere. That is, the heating device (100) of the present invention can heat-treat an object through a hydrogen-containing gas-based heat treatment method.

[0100] In one embodiment, the functional gas may be composed of a combination of hydrogen and an inert gas. An inert gas is a gas that is chemically stable due to low or no reactivity, and may include, but is not limited to, helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).

[0101] In a specific embodiment, the present invention utilizes argon as an inert gas included in the functional gas. Argon has the advantages of being cost-effective and offering excellent thermal stability. That is, the present invention forms a functional gas by combining hydrogen and argon gases, and can perform a heat treatment based on the functional gas.

[0102] The control unit can supply the hydrogen gas through the gas supply unit (153) and exhaust the hydrogen gas through the first gas discharge unit (112c).

[0103] For example, representative cathode materials for lithium-ion batteries include lithium iron phosphate (LFP; LiFePO₄) and lithium nickel manganese cobalt oxide (NMC; LiNiMnCoO₂). These two materials are widely used due to their unique advantages and can provide properties suitable for various applications. LFP boasts excellent safety, long life, and high thermal stability, making it primarily used in electric vehicles and large-scale energy storage systems. Meanwhile, NMC offers high energy density and excellent electrochemical performance, making it widely used as batteries for portable electronic devices and electric vehicles.

[0104] According to an embodiment, heat treatment of lithium-ion batteries can be performed using various gases. For example, heat treatment of lithium-ion batteries can be performed in a gas atmosphere composed of carbon monoxide (CO) and carbon dioxide (CO2), which can react with valuable metals within the battery to promote reduction reactions. While carbon monoxide, a strong reducing agent, can be used for reduction in lithium-ion batteries, excessively strong reduction can produce unintended byproducts. Therefore, carbon dioxide can be combined to control the reaction environment, allowing for more precise control of the desired degree of reduction. Furthermore, heat treatment temperature can be controlled by performing heat treatment in a gas atmosphere combining carbon monoxide and carbon dioxide. For example, adding carbon dioxide can lower the reaction temperature compared to using carbon monoxide alone. For example, high temperatures can increase side reactions or promote the formation of undesirable compounds. However, adding CO2 to lower the reaction temperature can alleviate the problem of unintended compound formation and more effectively induce the desired chemical reduction. This has the advantage of improving the efficiency of the overall heat treatment process.

[0105] However, heat treatment under a gaseous atmosphere composed of carbon dioxide and carbon dioxide has limitations for some types of cathode materials used in lithium-ion batteries. Specifically, some cathode materials, such as LFP (lithium iron phosphate), may experience insufficient reduction or very slow reduction during heat treatment in a CO and CO2 atmosphere. For LFP cathode materials, the low reactivity with reducing agents such as CO and CO2 can mean that the reduction reaction is difficult to effectively promote in such a gaseous atmosphere. This can reduce the recovery efficiency of valuable metals, particularly during the recycling and reprocessing of batteries containing LFP.

[0106] More specifically, referring to FIG. 4, when heat treatment is performed on an LFP cathode active material at a temperature of 700 to 850°C in a gas atmosphere in which carbon monoxide and carbon dioxide are combined in a 5:5 ratio (i.e., 50% carbon monoxide and 50% carbon dioxide) or a 7.5:2.5 ratio (i.e., 75% carbon monoxide and 25% carbon dioxide), it can be confirmed that the LFP structure is not decomposed. This means that the chemical stability of LFP is maintained under the conditions, and the valuable metal iron and phosphate structure are stably preserved even at high temperatures.

[0107] Fig. 4 is a diagram showing XRD patterns according to the results of heat treatment performed on LFP cathode active materials under various gas atmospheres. In the embodiment, XRD means X-ray Diffraction, and may mean analyzing a sample using characteristic x-rays generated when high-speed electrons collide with target atoms. XRD may mean an analysis method that diffracts x-rays into a desired specimen to represent the internal information of the specimen in a graph. In other words, it may be an analysis method that can confirm which phase is composed of which in the specimen by showing peak values ​​at unique angles of various phases.

[0108] More specifically, XRD can work by striking x-rays against a crystal, causing some of them to diffract. In a specific embodiment, as the x-ray tube and detector move, the degree to which the x-rays are diffracted by the sample can be recorded and graphed.

[0109] As shown in (b) of Fig. 4, it can be confirmed that the LFP structure is not decomposed in a mixed gas atmosphere of carbon monoxide and carbon dioxide, but remains in the form of LiFePO4.

[0110] Meanwhile, referring to (a) of Fig. 4, it can be confirmed that the LFP structure is decomposed and Li3PO4 and Fe2P are generated under a 100% carbon monoxide gas atmosphere or an argon gas atmosphere.

[0111] In summary, heat treatment under a 100% carbon monoxide or argon gas atmosphere may cause decomposition of the LFP structure, but may also cause the generation of unintended by-products and may involve higher temperature heat treatment conditions, which may increase energy consumption and reduce the efficiency of the recycling process.

[0112] Accordingly, using a combination of carbon monoxide and carbon dioxide in an appropriate ratio may be advantageous in the process of recycling LFP batteries; however, as shown in the experimental results described above, using a combination of carbon monoxide and carbon dioxide has the disadvantage of not being able to decompose the LFP cathode material.

[0113] To overcome these limitations, the present invention may be characterized by performing heat treatment on an LFP cathode active material using a functional gas.

[0114] According to one embodiment of the present invention, heat treatment using a heating device (100) may be characterized in that it is performed in a hydrogen-containing gas atmosphere. In an embodiment, the hydrogen-containing gas may be composed of a combination of hydrogen and an inert gas (e.g., argon gas).

[0115] In some embodiments, hydrogen (H2) gas can be a powerful reducing agent that can address problems that can arise when using carbon monoxide or carbon dioxide alone. In particular, hydrogen has the advantage of a stronger reducing driving force and faster reaction rate than carbon monoxide, allowing it to effectively reduce targets even at low temperatures.

[0116] In this embodiment, the heat treatment process using hydrogen gas has the advantage of enabling effective reduction and separation of not only LFP but also various types of lithium-ion battery cathode materials, thereby expanding the scope of lithium-ion battery recycling. In other words, heat treatment using hydrogen gas can minimize the environmental impact of lithium-ion battery recycling and maximize the recovery rate of valuable metals.

[0117] In one embodiment, the use of 100% hydrogen gas may be difficult due to its low price competitiveness and uncertain supply stability. Therefore, it may be desirable to utilize hydrogen-containing hydrous gas for battery recycling dry heat treatment. For example, hydrogen-containing hydrous gas, which is widely used as a reducing gas in the steelmaking process, can be utilized for battery recycling dry heat treatment.

[0118] In one embodiment, due to the low price competitiveness of hydrogen and the unstable stability of its supply, using 100% hydrogen gas may be economically and practically difficult. Therefore, it may be desirable to utilize a hydrous gas containing some hydrogen in the dry heat treatment process for battery recycling. For example, a gas mixture of hydrogen and argon (or another inert gas), widely used as a reducing gas in steel manufacturing processes, can be useful for dry heat treatment for battery recycling. This mixed gas, called "hydrous" gas, can maintain the high reducing capacity of hydrogen while reducing overall gas costs and improving the safety of the process.

[0119] In this embodiment, the use of a hydrogen gas can be particularly effective in efficiently reducing and separating valuable metals from lithium-ion batteries. The high reducing capacity of hydrogen enables the effective separation of valuable metals from battery active materials, and the addition of an inert gas can ensure the stability of the overall process. Therefore, heat treatment using a hydrogen gas can simultaneously improve the economic efficiency and environmental friendliness of the lithium-ion battery recycling process.

[0120] Such a functional gas (i.e., a combination of hydrogen and an inert gas) can be supplied to the working section through the gas supply section (153) as described above. The functional gas supplied to the working section can promote the reduction reaction of the cathode material during the heat treatment process within the working section and contribute to maintaining the stability of the battery material.

[0121] Additionally, in the embodiment, after the reduction reaction is promoted in the working section, the used gas is exhausted through the first gas exhaust section (112c). That is, the reaction gas and byproduct gas generated during the heat treatment process are safely removed, allowing the environment within the working section to be maintained at an optimal level. Appropriate exhaust of the used gas also prevents excessive pressure build-up that may occur during the heat treatment process and minimizes the risk of fire or explosion that may occur during the recycling process.

[0122] In a specific embodiment, the strong reducing ability of hydrogen gas and the stable chemical properties of argon gas are combined to ensure the stability of battery materials even at high temperatures and minimize the formation of byproducts.

[0123] The reduction mechanism of LFP cathode active material during heat treatment based on the function element can be expressed by the following chemical reaction formula.

[0124]

[0125] The above reaction may represent a process in which hydrogen reacts with LFP cathode material to produce lithium phosphate (Li₃PO₄), iron phosphide (Fe₂P, FeP₄) (or iron phosphide), and water (H₂O). In this process, hydrogen reduces iron (Fe) in LFP to produce iron phosphide (Fe₂P, FeP₄), and the water produced in this process may be discharged as a byproduct. The heat treatment process using hydrogen can effectively separate and recover iron (Fe), a valuable metal, from LFP.

[0126] According to one embodiment, when heat treatment of a product is performed using 100% hydrogen gas, the minimum temperature condition may be characterized as being 800°C.

[0127] More specifically, Fig. 5 visually presents the results of heat treatment experiments on lithium iron phosphate (LFP) cathode materials under various temperature conditions in a pure hydrogen environment (i.e., 100% hydrogen). In this experiment, heat treatments using hydrogen gas were performed over the temperature ranges of 700°C, 800°C, and 900°C. Analysis of the results in Fig. 5 shows that the heat treatment performed at 700°C revealed instability in the mass change, and the XRD analysis results under that condition showed that complete reduction of the LFP cathode material was not achieved. On the other hand, heat treatments at 800°C and 900°C showed clear changes in the XRD patterns, indicating successful reduction of the LFP cathode material, which is also consistent with the stabilization of the mass loss.

[0128] Therefore, a temperature of at least 800°C may be essential for the heat treatment process under a pure hydrogen atmosphere (i.e., 100% hydrogen atmosphere), which may serve as an important criterion for an efficient reduction and recovery process of LFP cathode materials.

[0129] Referring to FIGS. 6 and 7, it can be confirmed that reduction occurs when heat treatment is performed at a temperature of 800°C in a 100% hydrogen atmosphere. FIGS. 6 and 7 show the temperature-dependent mass change and XRD analysis results in 100%, 50%, 30%, and 10% hydrogen atmospheres, respectively, at a temperature of 800°C.

[0130] Through the analysis of the results of Figs. 6 and 7, it can be confirmed that the LFP unreduced peak disappears under the condition of 100% hydrogen partial pressure at a temperature of 800℃. Meanwhile, at a temperature of 800℃, the hydrogen partial pressures of 50%, 30%, and 10%, respectively, reveal instability in mass change, and the XRD analysis results under these conditions show that complete reduction of the LFP cathode material did not occur. In other words, when the hydrogen partial pressure is not 100%, the LFP unreduced peak exists, and through this, it can be confirmed that at a temperature of 800℃, when the hydrogen partial pressure is 100%, it is an appropriate temperature for heat treatment for reduction.

[0131] In other words, it can be confirmed that efficient reduction is successfully carried out only when the hydrogen partial pressure is 100% at a temperature of 800℃.

[0132] These experimental results can also be confirmed by the theory described in Li-Fe-P-O2 Phase Diagram from First Principles Calculations (2008) (Shyue Ping Ong, Lei Wang, Byoungwoo Kang, and Gerbrand Ceder). Specifically, Gibbs Free Energy (G) is a thermodynamic function used to evaluate the probability that a chemical reaction or physical change will occur spontaneously. If the Gibbs Free Energy change (ΔG) of a process is negative, the process can occur spontaneously. On the other hand, if ΔG is positive, the process can be non-spontaneous. If ΔG is 0, the system is in equilibrium.

[0133] Hydrogen acts as a highly effective reducing agent in high-temperature reduction reactions. When heat treatment is performed in a pure hydrogen atmosphere, the oxygen within the compound reacts with the hydrogen and converts to water, reducing the compound in this process. In particular, heat treatment in a hydrogen atmosphere at temperatures exceeding 800°C effectively removes oxygen and allows the separation of iron, phosphorus, and lithium in their reduced forms. The key to this reduction process may be satisfying the conditions for spontaneous occurrence, such as a negative change in Gibbs free energy (ΔG).

[0134] This is consistent with the principles of Gibbs free energy calculations presented in the paper "Li-Fe-P-O2 Phase Diagram from First Principles Calculations." In that paper, various chemical reactions and material stabilities were predicted based on Gibbs free energy changes through first-principles calculations. Similarly, high-temperature heat treatment under a hydrogen atmosphere can serve as an important criterion for defining the temperature and environmental conditions that can satisfy the spontaneous reaction condition, which requires a negative ΔG, during the process of separating and recovering chemical components of LFP cathode materials.

[0135] Therefore, heat treatment in a pure hydrogen atmosphere plays a crucial role in the efficient reduction and recovery of LFP cathode materials. The minimum temperature required during this process (over 800°C) is essential for the effective separation and recovery of lithium, iron, and phosphorus. This can contribute to the efficient recovery of important resources and minimizing environmental impact during lithium-ion battery recycling.

[0136] According to one embodiment of the present invention, when the heat treatment temperature is 1000°C, the minimum hydrogen concentration during the heat treatment of the LFP cathode active material may be characterized as being 10% or more. That is, when the heat treatment temperature is 1000°C, at least 10 parts by weight of hydrogen must be included relative to 100 parts by weight of the total functional gas.

[0137] More specifically, Fig. 8 visually presents the results of an experimental investigation into the influence of heat treatment according to changes in hydrogen gas concentration (10%, 30%, 50%, 100%) at 1000°C. The experimental results show that even when the hydrogen concentration is 10%, the change in mass is stable, and XRD analysis confirms that the reduction reaction of the LFP cathode material proceeds effectively. These experimental results indicate that even under high-temperature heat treatment conditions of 1000°C, a hydrogen concentration of at least 10% is sufficient for the reduction and recycling process of the LFP cathode material.

[0138] According to one embodiment of the present invention, the step of performing heat treatment on the object may be characterized by performing the heat treatment in a hydrogen gas atmosphere, and performing the heat treatment based on preset hydrogen content conditions and preset temperature conditions. Here, the preset hydrogen content condition may include a condition in which hydrogen is at least 30 parts by weight or more with respect to 100 parts by weight of the total hydrogen gas, and the preset temperature condition may include a temperature condition in which the temperature corresponding to the heat treatment is 760°C or more and less than 1000°C at most.

[0139] In a specific embodiment, the control unit of the heating device (100) may be characterized by controlling the heating unit so that heat treatment is performed on the object based on preset hydrogen content conditions and preset temperature conditions.

[0140] That is, the present invention can perform heat treatment on a target object at a temperature of 760°C or higher in a hydrogen gas atmosphere containing at least 30% hydrogen relative to the total hydrogen gas. These hydrogen content and temperature conditions may be minimum conditions or initiation conditions for inducing a reaction in the target object. For example, if the aforementioned hydrogen content conditions and preset temperature conditions are not met, a reaction in the target object may not occur.

[0141] Specifically, the mass change process according to hydrogen concentration at 760°C can be confirmed through Fig. 9. Referring to Fig. 9, it can be confirmed that no mass change occurs when heat treatment is performed at 760°C in a hydrogen gas atmosphere with a hydrogen content of 10%. This lack of mass change may indicate that a reduction reaction of the LFP cathode material does not occur.

[0142] Meanwhile, it can be confirmed that a mass change occurs when the hydrogen content of the hydrogen-containing gas is 30%. That is, through the analysis of Fig. 9, it can be confirmed that a temperature of at least 760°C and a hydrogen concentration of 30% are the conditions for initiating the reduction of the LFP cathode material. As described above, the minimum conditions for initiating the reduction reaction of the object of the present invention may be a condition for performing heat treatment at a temperature of at least 760°C in a hydrogen-containing gas atmosphere with a hydrogen content of at least 30%.

[0143] Referring to FIGS. 10 and 11, it can be confirmed that no reduction reaction of the target object occurs at a temperature of 700°C, which is outside the aforementioned temperature range. FIGS. 10 and 11 show the temperature-dependent mass change and XRD analysis results in 100% and 50% hydrogen atmospheres, respectively, at a temperature of 700°C.

[0144] Through the analysis of the results of Figs. 10 and 11, the heat treatment performed at 700°C reveals instability in mass change, and the XRD analysis results under these conditions confirm that complete reduction of the LFP cathode material did not occur. That is, the unreduced LFP peak exists even in a 100% hydrogen atmosphere, which confirms that the temperature of 700°C is an inappropriate temperature for heat treatment for reduction. In addition, if the heat treatment temperature is 1000°C or higher, reduction may not occur smoothly. This is because excessive temperature may deteriorate the structural stability of the LFP cathode material, which may result in unwanted side reactions or thermal damage to the material. These side effects may cause performance degradation and shortened life of the cathode material. Therefore, it can be seen that the heat treatment conditions of the present invention are in the temperature range of 760°C or higher and lower than 1000°C, and it can be confirmed that within this range, heat treatment in a hydrous gas atmosphere with a hydrogen content of at least 30% is a condition that can effectively perform reduction of the LFP cathode material. When these conditions are met, the reduction reaction of the LFP cathode material can be performed stably and efficiently.

[0145] In addition, according to one embodiment, the hydrogen content conditions and temperature conditions that maximize the reduction reaction efficiency of the target object may be as follows. That is, the optimal heat treatment conditions for maximizing the reduction reaction efficiency of the target object and ultimately increasing the recovery rate of valuable metals are as follows.

[0146] More specifically, the step of performing heat treatment on the target object may be characterized by performing the heat treatment in a hydrogen gas atmosphere, and performing the heat treatment based on preset hydrogen content conditions and preset temperature conditions. Here, the preset hydrogen content condition may include a condition in which hydrogen is at least 50 parts by weight or more with respect to 100 parts by weight of the total hydrogen gas, and the preset temperature condition may include a temperature condition in which the temperature corresponding to the heat treatment is 900°C or higher.

[0147] In a specific embodiment, the control unit of the heating device (100) may be characterized by controlling the heating unit so that heat treatment is performed on the target object based on preset hydrogen content conditions (hydrogen content of 50% or more) and preset temperature conditions (900°C or more).

[0148] That is, when heat treatment is performed under conditions of a temperature of at least 900°C in an environment where the hydrogen concentration is 50% or more of the total gas, effective reduction of the LFP cathode material can be promoted.

[0149] More specifically, the mass change process according to hydrogen concentration can be confirmed through Fig. 12. Referring to Fig. 12, it can be confirmed that the convergence section of each graph related to the end of the reaction is an important point. As the hydrogen concentration decreases, the graph shows a downward trend rather than convergence. This may mean that when the hydrogen concentration is low, the oxygen partial pressure increases, forming an oxidizing atmosphere, and as a result, carbon is continuously oxidized, resulting in weight loss. In particular, the point where rapid weight loss begins and the slope of the weight loss may be important points in the experimental results. It can be confirmed that the weight loss slope for each hydrogen concentration is generally similar.

[0150] Referring to Figure 12, when the hydrogen concentration is 100%, a weight loss of approximately 13% occurs, confirming the complete completion of the reaction. This means that a weight loss of approximately 13% occurs when the reduction reaction of the cathode material is completed. Furthermore, the inflection point tends to begin at a similar point even under different hydrogen partial pressures. This confirms that there is no significant difference in the reaction completion time of the cathode material depending on the hydrogen concentration.

[0151] Meanwhile, a point of note for each hydrogen concentration may be the temperature at which rapid reaction begins. At 100% hydrogen, rapid weight loss begins at approximately 760 degrees. However, as hydrogen concentration decreases to 50%, 30%, and 10%, the reaction initiation temperature rises to 850, 900, and 940 degrees, respectively.

[0152] In particular, through the analysis of Fig. 12, it can be confirmed that a temperature of at least 900°C and a hydrogen concentration of 50% are the optimal conditions for the reduction of LFP cathode material.

[0153] More specifically, Fig. 13 shows the mass change process according to hydrogen concentration at 900°C. Referring to Fig. 13, when heat-treated at 900°C in a hydrous gas atmosphere with a hydrogen content of 30%, a downward trend is observed rather than convergence. This may be because when the hydrogen content is low, the oxygen partial pressure is relatively high, making the oxidation reaction dominant. Under these conditions, the reduction of the LFP cathode material becomes difficult, and as a result, the mass loss tends to increase. This is confirmed by experimental data, suggesting that the reduction reaction can occur more effectively at a high hydrogen concentration. Therefore, maintaining a higher hydrogen concentration may be important for efficient reduction, and it can be confirmed that a steep slope of weight loss is observed, especially in a hydrous gas atmosphere with a hydrogen content of 50%. That is, it can be confirmed through Fig. 13 that when the hydrogen content is 50% or more at a temperature of 900℃, the reaction rate becomes faster and the reduction efficiency is improved, and these data clearly show that the heat treatment under the set conditions plays a role in maximizing the reduction reaction efficiency of the LFP cathode material.

[0154] That is, under the conditions described above (i.e., heat treatment at a temperature of 900°C or higher in a hydrogen gas atmosphere having a hydrogen content of 50% or higher), it is possible to promote an efficient reduction reaction while minimizing the increase in the reaction initiation temperature, and to provide ideal results in terms of weight loss rate and reaction end point. Therefore, the present invention promotes effective reduction of LFP cathode materials by controlling the hydrogen concentration and heat treatment temperature based on these optimal conditions, thereby maximizing the recovery rate of cathode materials. That is, the conditions set by the present invention can optimize the reduction reaction of LFP cathode materials. According to one embodiment, when the amount of the specified gas introduced is excessive, the control unit can open the first gas discharge port (112c) formed in the object inlet port (110) to exhaust it. In order to minimize the pressure gradient that may occur during the exhaust process of the designated gas in the internal space of the object injection port (110) before that, the exhaust process inside the object injection port (110) by the pressure maintenance unit (112d) may be performed in advance or in parallel.

[0155] In addition, the present invention may include a method of pretreating an object equipped with a waste lithium ion battery, performing a first heat treatment, separating a valuable metal, and performing a second heat treatment.

[0156] Pretreatment of waste batteries is performed for the purpose of preventing explosion or rendering them harmless, removing foreign substances such as outer cans, etc. For example, used waste batteries are stored in a sealed system and contain substances such as electrolytes inside, so there is a risk of explosion during crushing. Accordingly, process safety can be enhanced and the recovery rate of valuable metals such as copper, nickel, and cobalt can be increased by discharging waste batteries and removing electrolytes. Discharging waste batteries can be performed by immersing the waste batteries in an aqueous solution containing alkali metal or alkaline earth metal ions, but the type of the aqueous solution is not limited thereto.

[0157] Thereafter, the object can be subjected to the first heat treatment by being placed in a storage unit to be described later and then fed into the working unit (120) through the object feeding port (110). If the working unit (120) has an input port formed on one side and an exhaust port provided on the other side, it can be used without any special restrictions, and it can be configured as a vertical working unit (120) that allows for vertical feeding and exhaust, or it can be configured as a working unit of another connected type. The heat source may include, but is not limited to, a gas burner, a coal burner, a resistance heater, or an IR lamp.

[0158] After the first and second heat treatments as described above are completed, the valuable metal can be recovered according to the physical properties of the target object. In one embodiment, the target object made of a magnetic metal is subjected to selective separation using a magnetic field, and in the case of ash, it is classified by particle size by sieving using an airflow classifier, a centrifugal principle, vibration, etc. In addition, Li2CO3 and LiAlO2, which are Li-rich phases, can be recovered by a leaching process using water or acid, and the separation process can be performed before or after the second heat treatment according to the purpose. That is, the valuable metal can be separated and obtained through at least one of a separation process using classification, a separation process using magnetism, and a separation process using leaching using acid or water.

[0159] Through a series of methods as described above, valuable metals can be recovered in four groups: alloy-type metals containing at least one of nickel, cobalt, and manganese that are magnetic; non-magnetic Al-dross when the outer can (case) of a spent battery is made of aluminum; lithium carbonate recovered using the water leaching method; MnO and LiAlO2; and residual carbon that is not oxidized in the second heat treatment process.

[0160] In a more specific embodiment, referring to FIG. 14, a lithium ion battery recycling method using a dry heat treatment method based on a functional gas may include a step (S300) of performing a heat treatment on a target object to obtain lithium phosphate (Li3PO4) and a reduction byproduct (Fe2P), a step (S400) of performing a leaching process on the lithium phosphate, and a step (S500) of performing a magnetic separation process on the reduction byproduct.

[0161] According to an embodiment, the step of performing heat treatment on the target object to obtain lithium phosphate and a reduction by-product may mean performing heat treatment on a spent battery including an LFP cathode material at 900°C or higher in a hydrous hydrogen atmosphere containing at least 50 parts by weight of hydrogen relative to 100 parts by weight of the total hydrous hydrogen gas, as described above. That is, lithium phosphate and a reduction by-product can be effectively obtained through optimal conditions (temperature conditions of at least 900°C or higher in an environment in which the hydrogen concentration is at least 50% of the total gas). In particular, when heat treatment is performed under temperature conditions of at least 900°C or higher in an environment in which the hydrogen concentration is at least 50% of the total gas, the recovery rate of lithium phosphate is maximized, and consequently, the yield of obtaining valuable metals can be maximized.

[0162] In one embodiment, a method for recycling lithium-ion batteries utilizing a dry heat treatment method based on a functional gas may include a step of performing a leaching process on lithium phosphate using a leaching device. In one embodiment, lithium phosphate obtained through the heat treatment may be introduced into the leaching device, and lithium may be dissolved using an appropriate leaching agent (e.g., an acidic or basic solution). Through this process, a lithium-containing solution may be obtained, and an additional purification process may be performed to recover lithium from the solution. For example, the process of extracting and purifying lithium from the leached lithium-containing solution may be performed through methods such as electrolysis, evaporation, or crystallization. Through this process, high-purity lithium is obtained. The lithium obtained through the purification process can be used as a high-purity raw material that can be reused in the battery manufacturing process, and can be utilized to establish a sustainable production and recycling system for lithium-ion batteries.

[0163] According to one embodiment of the present invention, a lithium-ion battery recycling method utilizing a dry heat treatment method based on a functional gas may be characterized by performing a magnetic separation process on a reduction by-product using a magnetic separation device. The magnetic separation process may be for separating and recovering iron from the reduction by-product, Fe2P. In an embodiment, Fe2P, a reduction by-product, among solid residues separated in a leaching process, may be separated using a magnetic separator. Since Fe2P is magnetic, it can be separated into iron powder form through the magnetic separation process. The iron powder separated through this process can be recycled as a high-purity iron resource.

[0164] Through this process, lithium, iron, and phosphorus can be effectively separated and recovered from LFP batteries, which can contribute to promoting resource recycling and minimizing environmental impact.

[0165]

[0166] The description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments disclosed herein, but is to be construed in the broadest scope consistent with the principles and novel features disclosed herein.

[0167] (Explanation of symbols)

[0168] 100: Heating device 110: Inlet

[0169] 120: Working section 130: Heating section

[0170] 140: Refractory section 150: Discharge section

[0171] 160: Fixed part

[0172]

[0173]

[0174] This invention is based on a project carried out with support from the Small and Medium Business Technology Innovation Development Project (Scale-up Tips) of the Ministry of SMEs and Startups.

[0175]

[0176] The best mode for carrying out the invention as described above has been described.

Claims

1. A step of inserting a storage unit that accommodates the object into a heating device; and A step of performing heat treatment on the object by controlling the heating unit provided in the heating device; The above heat treatment is characterized in that it is performed in a hydrogen-containing functional gas atmosphere. A method for recycling lithium-ion batteries using a dry heat treatment method based on a gaseous function.

2. In paragraph 1, The above functional gas is composed of a combination of hydrogen and an inert gas, The step of performing heat treatment on the above object is: The heat treatment is performed in the above-mentioned functional gas atmosphere, and is characterized in that the heat treatment is performed based on preset hydrogen content conditions and preset temperature conditions. The above preset hydrogen content condition is a condition in which the hydrogen is at least 30 parts by weight or more based on 100 parts by weight of the total functional gas, and the above preset temperature condition includes a temperature condition in which the temperature corresponding to the heat treatment is at least 760°C or more and at most less than 1000°C. A method for recycling lithium-ion batteries using a dry heat treatment method based on a gaseous function.

3. In paragraph 1, The step of performing heat treatment on the above object is: The heat treatment is performed in the above-mentioned functional gas atmosphere, and is characterized in that the heat treatment is performed based on preset hydrogen content conditions and preset temperature conditions. The above preset hydrogen content condition is a condition in which the hydrogen is at least 50 parts by weight or more based on 100 parts by weight of the total functional gas, and the above preset temperature condition includes a temperature condition in which the temperature corresponding to the heat treatment is at least 900°C or more. A method for recycling lithium-ion batteries using a dry heat treatment method based on a gaseous function.

4. In paragraph 1, The above heating device includes a work section that performs a heat treatment operation on the object, The above working section is characterized in that it has a vertical kiln structure that moves each of one or more storage sections in a vertical direction, The above object is sequentially passed through each of the one or more storage sections and is heated, but is heated in the atmosphere of the functional gas supplied into the working section. A method for recycling lithium-ion batteries using a dry heat treatment method based on a gaseous function.

5. In paragraph 1, If the above target is an LFP battery, the heat-treated target is characterized in that it is separated into lithium phosphate (Li3PO4) and a reduction byproduct (Fe2P). The above method, A step of performing a leaching process for the above lithium phosphate; and A step of performing a magnetic separation process for the above reduction byproduct; including; A method for recycling lithium-ion batteries using a dry heat treatment method based on a gaseous function.

6. The input section into which the storage section containing the object is inserted; A heating unit that heats the above object; A discharge section for discharging a heated object; A gas supply unit that supplies a hydrogen-containing functional gas to a space where the above object is heated; and A control unit for controlling the above heating unit; including; A lithium-ion battery recycling device utilizing a dry heat treatment method based on a gaseous function.

7. In paragraph 6, The above functional gas is composed of a combination of hydrogen and an inert gas, The above control unit, It is characterized in that the heating unit is controlled so that heat treatment is performed on the target object based on preset hydrogen content conditions and preset temperature conditions. The above preset hydrogen content condition is a condition in which the hydrogen is at least 30 parts by weight or more based on 100 parts by weight of the total functional gas, and the above preset temperature condition includes a temperature condition in which the temperature corresponding to the heat treatment is at least 760°C or more and at most less than 1000°C. A lithium-ion battery recycling device utilizing a dry heat treatment method based on a gaseous function.

8. In paragraph 7, The above control unit, It is characterized in that the heating unit is controlled so that heat treatment is performed on the target object based on preset hydrogen content conditions and preset temperature conditions. The above preset hydrogen content condition is a condition in which the hydrogen is at least 50 parts by weight or more based on 100 parts by weight of the total functional gas, and the above preset temperature condition includes a temperature condition in which the temperature corresponding to the heat treatment is at least 900°C or more. A lithium-ion battery recycling device utilizing a dry heat treatment method based on a gaseous function.

9. In paragraph 6, It further includes a work section that performs a heat treatment operation on the above object, The above working section is characterized in that it has a vertical kiln structure that moves each of one or more storage sections in a vertical direction, The above object is sequentially passed through each of the one or more storage sections and is heated, but is heated in the atmosphere of the functional gas supplied into the working section. A lithium-ion battery recycling device utilizing a dry heat treatment method based on a gaseous function.

10. In paragraph 6, If the above object is an LFP battery, the heat-treated object is characterized in that it is separated into lithium phosphate and a reduction byproduct. The above lithium ion battery recycling device, A leaching device for performing a leaching process for the above lithium phosphate; and A magnetic separation device that further comprises a magnetic separation process for the above reduction byproduct; A lithium-ion battery recycling device utilizing a dry heat treatment method based on a gaseous function.

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