Artificial graphite production system

Abstract

The present invention relates to an artificial graphite production system comprising a conveying unit including a sagger containing artificial graphite as a raw material, a calcining unit calcining the sagger containing the artificial graphite, an artificial graphite hardness measuring unit measuring the hardness of the artificial graphite in the sagger, and a disintegrating unit disintegrating the artificial graphite recovered from the artificial graphite hardness measuring unit, wherein the artificial graphite hardness measuring unit determines whether the hardness of the artificial graphite satisfies a predetermined range and transfers the artificial graphite satisfying the predetermined range to the disintegrating unit.

Description

Technology Field

[0001] The present invention relates to a cathode active material production system, and more specifically, to an artificial graphite production system. Background Technology

[0002] A lithium secondary battery generally consists of a positive electrode containing a positive active material, a negative electrode containing a negative active material, a separator, and an electrolyte, and charging and discharging are performed through the intercalation and decalation of lithium ions. Since the lithium secondary battery possesses the advantages of high energy density, high electromotive force, and the ability to exhibit high capacity, it is being applied in various fields.

[0003] Furthermore, improving high-temperature performance, such as high-temperature storage and cycling characteristics, in lithium secondary batteries is a critical challenge. For example, there is a significant problem where the high-temperature performance of the anode is likely to deteriorate if the total internal pore volume is high after the anode active material is coated onto a current collector and rolled. Therefore, it is necessary to improve high-temperature characteristics when developing anode active materials for lithium secondary batteries, such as rapid-charge batteries, by minimizing changes in electrode structure and total internal pore volume that occur during electrode rolling.

[0004] Furthermore, as technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly rising. Among secondary batteries, lithium secondary batteries, which exhibit high energy density and operating potential, long cycle life, and low self-discharge rate, have been commercialized and are widely used.

[0005] Furthermore, as interest in environmental issues grows, there is increasing interest in electric vehicles and hybrid electric vehicles that can replace fossil fuel-using vehicles, such as gasoline and diesel vehicles, which are one of the major causes of air pollution; consequently, research is actively underway to use lithium-ion batteries as a power source for the aforementioned electric vehicles and hybrid electric vehicles.

[0006] As such, as expectations for lithium secondary batteries grow, the role of the negative electrode active material responsible for storing lithium ions in the aforementioned lithium secondary battery is becoming important. As the aforementioned negative electrode active material, metallic lithium negative electrode active materials, carbon-based negative electrode active materials, or silicon oxide (SiO₂) x Materials such as ) are used. The above carbon-based negative electrode active material exhibits excellent capacity retention characteristics and efficiency. Since the carbon-based negative electrode active material used as the negative electrode of a lithium secondary battery has a potential close to the electrode potential of lithium metal, the change in crystal structure is small during the insertion and extraction processes of ionic lithium. In addition, the above carbon-based negative electrode active material enables continuous and repetitive oxidation and reduction reactions at the electrode, allowing the lithium secondary battery to exhibit high capacity and excellent lifespan.

[0007] Various types of materials are used as the carbon-based negative electrode active materials, such as crystalline carbon-based materials like natural graphite and artificial graphite, or amorphous carbon-based materials like hard carbon and soft carbon. Among the carbon-based negative electrode active materials, graphite-based negative electrode active materials are the most widely used because they have excellent reversibility and can improve the lifespan characteristics of lithium secondary batteries. Since the discharge voltage of the graphite-based negative electrode active material is low at -0.2 V compared to lithium, a battery using the graphite-based active material can exhibit a high discharge voltage of 3.6 V, which has an excellent advantage in terms of energy density of lithium secondary batteries.

[0008] The artificial graphite, which is a crystalline carbon-based material, has a more stable crystal structure than the natural graphite because it is formed by applying high thermal energy of 2,700°C or higher. Since the change in the crystal structure is small even with repeated charging and discharging of lithium ions, the artificial graphite has the advantage of having a lifespan that is 2 to 3 times longer than that of the natural graphite, so there is growing interest in the method of producing artificial graphite.

[0009] In the manufacturing process of the aforementioned artificial graphite, a mixture of the artificial graphite and pitch is heat-treated in a kiln to coat the surface with an amorphous carbon layer, thereby utilizing the coating material as a cathode material. However, in the process of manufacturing the coating material, there is a problem in which the hardness of the sintered product inside the kiln increases due to an excessive amount of pitch or because the physical properties of the coating material deviate from their upper or lower limits. When the sintered product is retrieved, the artificial graphite with increased hardness causes the drill in the automated system to stop or remains excessively in the kiln, halting the operation of the kiln. Since the aforementioned problems must be resolved through manual operation by a worker, there is a problem of excessively increased process time. The problem to be solved

[0010] The technical problem that the present invention aims to solve is to provide an artificial graphite production system that resolves the problem of reduced productivity of the automated line due to the problem of increased hardness of the artificial graphite product during the recovery process, and resolves the problem of reduced process time. means of solving the problem

[0011] According to one embodiment of the present invention, an artificial graphite production system comprises a conveying unit including a sagger containing artificial graphite as a raw material, a calcining unit calcining the sagger containing the artificial graphite, an artificial graphite hardness measuring unit measuring the hardness of the artificial graphite in the sagger, and a disintegrating unit disintegrating the artificial graphite recovered from the artificial graphite hardness measuring unit, wherein the artificial graphite hardness measuring unit determines whether the hardness of the artificial graphite satisfies a predetermined range and can transfer the artificial graphite satisfying the predetermined range to the disintegrating unit.

[0012] In one embodiment, the artificial graphite hardness measuring unit measures the hardness of the artificial graphite calcined within the sand, determines whether the hardness of the calcined artificial graphite satisfies the predetermined range, and if the predetermined range is satisfied, the sand is moved to the disintegration unit, and if the predetermined range is not satisfied, the sand containing the calcined artificial graphite can be recovered to the recovery unit. In one embodiment, the artificial graphite hardness measuring unit may be any one of a soil hardness tester, a Vickers hardness tester, a Rockwell hardness tester, and a nanoindenter.

[0013] In one embodiment, when the artificial graphite hardness measuring unit is a soil hardness meter, the measurement can be taken by pressing the needle of the soil hardness meter to a certain depth from the surface of the artificial graphite powder placed within the slat. In one embodiment, the calcination unit can calcine the artificial graphite and the coating material by mixing them.

[0014] In one embodiment, a post-processing unit for recovering the artificial graphite that has passed through the crushing unit may be included. In one embodiment, the post-processing unit may include a dumping unit for dumping the saga and a roll-milling unit for roll-milling the artificial graphite that has passed through the dumping unit.

[0015] In one embodiment, the post-processing unit may include a storage unit that recovers and stores the artificial graphite that has passed through the roll mill unit. In one embodiment, the post-processing unit may further include an inspection unit that inspects hollow sand from the collection of artificial graphite and a raw material charging unit that charges raw materials into the sand that has passed through the inspection unit.

[0016] In one embodiment, a cooling unit for cooling the saga that has passed through the calcination unit may be further included. In one embodiment, the artificial graphite hardness measuring unit includes a control unit, and the control unit determines whether the hardness of the artificial graphite satisfies a predetermined range, and transfers the artificial graphite that satisfies the predetermined range to a disintegration unit, and transfers the artificial graphite that does not satisfies the predetermined range to a recovery unit. Effects of the invention

[0017] According to one embodiment of the present invention, an artificial graphite production system includes an artificial graphite hardness measuring unit, thereby solving the problem of reduced productivity of the automated line due to the problem of increased hardness of the sintered product during the recovery process of the artificial graphite sintered product, and solving the problem of reduced process time. Brief explanation of the drawing

[0018] FIG. 1 is a schematic diagram of an artificial graphite production system according to one embodiment of the present invention. Specific details for implementing the invention

[0019] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention.

[0020] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0021] When it is stated that one part is "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly on" another part, no other part is interposed in between.

[0022] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0023] FIG. 1 is a schematic diagram of an artificial graphite production system (100) according to one embodiment of the present invention.

[0024] Referring to FIG. 1, an artificial graphite production system (100) according to one embodiment includes a conveying unit (110), a calcination unit (120), an artificial graphite hardness measuring unit (130), and a crushing unit (140). The artificial graphite production system (100) of the present invention calcines artificial graphite and measures the hardness of the artificial graphite that is the calcined product to classify good products and defective products of the calcined product. By measuring the hardness of the artificial graphite that is the calcined product in advance, the artificial graphite production system (100) can solve the problem of the artificial graphite production system (100) stopping and can track quality issues of the artificial graphite.

[0025] The conveying unit (110) may be a member that conveys the artificial graphite, which is a raw material. Specifically, the artificial graphite may be conveyed by the conveying unit (110) while loaded into a sagger, which is a refractory container. More specifically, the artificial graphite may be conveyed by the sagger to perform subsequent processes such as firing and hardness measurement.

[0026] The firing section (120) may be a member that fires the artificial graphite. Specifically, the firing section (120) may be a member that carbonizes the artificial graphite to produce a fired artificial graphite.

[0027] In one embodiment, the firing section (120) may be a member that mixes a coating material with the artificial graphite and fires it. The coating material may be a material such as pitch, as a non-limiting example. The firing section (120) may be a step of mixing a coating material with the artificial graphite to produce a fired product in which the coating material is coated on the artificial graphite.

[0028] In one embodiment, the artificial graphite hardness measuring unit (130) can measure the hardness of the sintered artificial graphite, specifically, the sintered product. More specifically, the artificial graphite hardness measuring unit (130) can measure whether the sintered product satisfies a hardness value within a predetermined range. The artificial graphite hardness measuring unit (130) can measure the hardness of the sintered product in advance before feeding it into the disintegration unit (140) to prevent the problem of the sintered product having excessively high hardness causing the artificial graphite production system (100) to stop, and can track quality issues by checking the physical properties of the artificial graphite in advance.

[0029] In one embodiment, the artificial graphite production system (100) may further include a cooling unit for cooling the sago that has passed through the firing unit (120). The cooling unit may be positioned at the outlet side of the firing unit (120) to cool the sago containing artificial graphite, or may be positioned in a predetermined area within the firing unit (120) to cool the sago containing artificial graphite.

[0030] The cooling unit may include a slow cooling unit and a rapid cooling unit. Specifically, the slow cooling unit and the rapid cooling unit may be arranged sequentially from the outlet side of the firing unit (120) to cool the artificial graphite. The slow cooling unit may be arranged before the rapid cooling unit to gradually lower the temperature of the sac, and the rapid cooling unit may be a member that rapidly lowers the temperature of the sac after the temperature has been lowered. By including the slow cooling unit and the rapid cooling unit simultaneously, problems such as the quality of the artificial graphite deteriorating or the crucible deteriorating during rapid cooling can be prevented.

[0031] In one embodiment, the cooling unit may include a gas injection unit. The gas injection unit may be a component that injects an inert gas, such as argon or nitrogen, into the cooling unit. Specifically, the gas injection unit may supply the aforementioned gas to the saga to prevent the artificial graphite from easily deteriorating or oxidizing when in contact with air.

[0032] In one embodiment, the artificial graphite hardness measuring unit (130) can transfer the artificial graphite to the disintegration unit (140) when the hardness of the artificial graphite fired in the sintering unit satisfies a predetermined range. Specifically, the artificial graphite hardness measuring unit (130) can measure the hardness value of the artificial graphite that has changed due to factors such as the residence time in the firing unit (120) or the content of the coating material. At this time, if the artificial graphite hardness measuring unit (130) reaches the target hardness range of the artificial graphite fired, the artificial graphite fired can be transferred to the disintegration unit (140), which is a subsequent process, to perform the subsequent process.

[0033] For example, calcined synthetic graphite is 7.5 kg / cm³ when the furnace residence time is long. 2 Hardness index (kg / cm²) 2 ) and in the case of a short residence time, 6.5 kg / cm² 2 It may have a hardness index of the following. In the case of a carbonized product in which the calcined artificial graphite is mixed with pitch, which is a coating material, the hardness index value may increase as the content of pitch increases. As described above, the hardness index of the calcined artificial graphite may vary depending on the residence time in the calcination section or the amount of coating material input, and this can be measured by the artificial graphite hardness measuring section (130) to determine whether a subsequent process can proceed.

[0034] At this time, the hardness index is calculated based on the value measured by the hardness meter of the artificial graphite hardness measuring unit (130). Specifically, the hardness meter is defined as the value obtained by dividing the force required to penetrate the needle of the hardness meter into the artificial graphite placed within the wire by the cross-sectional area of ​​the needle of the hardness meter. In this way, the hardness index can be calculated by measuring the resistance force when the needle of the hardness meter penetrates to a certain depth into the artificial graphite and dividing this by the cross-sectional area of ​​the needle of the hardness meter.

[0035] In one embodiment, if the hardness of the calcined artificial graphite does not satisfy the above predetermined range, the saga containing the calcined artificial graphite can be recovered to a separate recovery unit. Specifically, the recovery unit may be a component that recovers the saga when the hardness of the calcined artificial graphite is excessively low or high, making it difficult to proceed with a subsequent process.

[0036] In one embodiment, the recovery unit may further include a recovery transfer unit that transfers the sintered artificial graphite back to the sintering unit (120) when the hardness of the sintered artificial graphite is excessively low and additional heat treatment is required. Specifically, when the hardness of the sintered artificial graphite is excessively low, additional sintering may be required, so a sintering step may be further performed to supply additional heat to the sintered artificial graphite by transferring the sintered artificial graphite to the sintering unit (120) through the recovery transfer unit.

[0037] At this time, the recovery transfer unit may be a member connected to the transfer unit (110) and may be a transfer member separately arranged in addition to the supply line that transfers the saga to the crushing unit (140). By connecting the recovery transfer unit to the transfer unit (110), the saga that is not determined to be artificial graphite having an appropriate range of hardness by the artificial graphite hardness measuring unit (130) can be efficiently re-supplied to the firing unit (120) to improve process efficiency.

[0038] In one embodiment, the recovery unit may further include a discharge unit for discharging a sac containing the calcined artificial graphite to the outside when the hardness of the calcined artificial graphite is excessively high and cannot be fed into a subsequent process. Specifically, when the hardness of the calcined artificial graphite is excessively high, it may be a case where a subsequent process cannot be performed, and thus it can be discharged to the outside of the artificial graphite production system (100) through the discharge unit.

[0039] At this time, the discharge unit is connected to the transfer unit (110) to transfer saga containing artificial graphite to the outside, and may be a transfer member separately arranged in addition to the supply line that transfers the saga to the crushing unit (140).

[0040] In one embodiment, the artificial graphite hardness measuring unit (130) may include a control unit that measures the hardness of the artificial graphite and selects the artificial graphite having a hardness value within a predetermined range. Specifically, the control unit may determine whether the artificial graphite that has passed through the calcination unit (120) has a hardness within a predetermined range. More specifically, if the hardness of the artificial graphite satisfies the predetermined range, the control unit may transfer the saga containing the artificial graphite to the disintegration unit (140), and if the hardness of the artificial graphite does not satisfy the predetermined range, the artificial graphite may be transferred to the recovery unit.

[0041] In one embodiment, the control unit may perform the process of sorting according to the hardness of the artificial graphite using an automated system. As described above, the artificial graphite hardness measuring unit (130) may measure the hardness of the calcined artificial graphite in advance before a subsequent process step, and a series of processes in which the artificial graphite is supplied to a subsequent process or recovered may be performed automatically by the control unit. In this way, the process may be performed by the artificial graphite hardness measuring unit (130).

[0042] In one embodiment, the artificial graphite hardness measuring unit (130) may be any one of a soil hardness meter, a Vickers hardness meter, a Rockwell hardness meter, and a nanoindenter. Specifically, the artificial graphite hardness measuring unit (130) may include a hardness meter capable of measuring the hardness of artificial graphite, which is a sintered product placed in a saga.

[0043] In one embodiment, the artificial graphite hardness measuring unit (130) may be a soil hardness meter, and the soil hardness meter may be a hardness meter such as a handheld penetrometer, a cone penetrometer, a digital penetrometer, or an automatic penetrometer.

[0044] The above-mentioned portable soil hardness meter may be a hardness meter that is portable and can be introduced into a process for measurement. The above-mentioned cone-type hardness meter may be a hardness meter that measures penetration resistance using a conical needle. The above-mentioned digital soil hardness meter may be a hardness meter that provides precise electronic data and can automatically measure hardness. The above-mentioned automatic penetration hardness meter may be a hardness meter that automatically penetrates a needle at a constant speed.

[0045] In one embodiment, when the artificial graphite hardness measuring unit (130) is a soil hardness meter, the soil hardness meter may be pressed into the surface of the artificial graphite powder placed in the sand at a certain depth in the direction of the ground. The soil hardness meter may be capable of pressing the soil hardness meter at a certain depth into the artificial graphite powder to measure the force with which the artificial graphite powder resists the soil hardness meter's needle. In this way, the artificial graphite hardness measuring unit (130) can measure the hardness of the artificial graphite placed in the sand in a simple manner by using a soil hardness meter.

[0046] The disintegration unit (140) can disintegrate the artificial graphite recovered from the artificial graphite hardness measuring unit (130). Specifically, the disintegration unit (140) is a component that crushes the artificial graphite. More specifically, the disintegration unit (140) may be a component for crushing the artificial graphite into fine particles to ensure uniform mixing of the artificial graphite and control of particle size. In this way, the disintegration unit (140) can disintegrate the artificial graphite delivered from the artificial graphite hardness measuring unit (130) that satisfies a hardness within a predetermined range, thereby inducing uniform mixing of the artificial graphite.

[0047] In one embodiment, the artificial graphite production system (100) may include a post-processing unit (150) for recovering artificial graphite that has passed through a crushing unit (140). The post-processing unit (150) may be a component for recovering artificial graphite having a predetermined hardness after firing.

[0048] In one embodiment, the post-processing unit (150) may include a dumping unit for dumping a saga in which artificial graphite is loaded, and a roll-mill unit for roll-milling the artificial graphite that has passed through the dumping unit.

[0049] The dumping section may be a member that discharges the crushed artificial graphite from the saga. Specifically, the dumping section may be a member that pours the artificial graphite into the roll mill section.

[0050] The roll mill part may be a component that compresses or rolls the dumped artificial graphite to make the particles uniform. For example, the roll mill part may be one in which two or more rollers rotate to compress the material and control the density and particle size.

[0051] In one embodiment, the post-processing unit (150) may further include a storage unit for recovering and storing the artificial graphite that has passed through the roll mill unit. Specifically, the storage unit may be a component that stores the artificial graphite, for which the hardness of the sintered product satisfies a predetermined range, in a separate storage space after completing a subsequent process.

[0052] In one embodiment, the post-processing unit (150) may further include an inspection unit for inspecting hollow sands from the artificial graphite collection and a raw material loading unit for loading raw materials into sands that have passed through the inspection unit.

[0053] The inspection unit may be a component for determining the condition of the saga in which artificial graphite has been collected. Specifically, the inspection unit may determine the condition of the saga by performing non-destructive testing on the saga, such as visual inspection, an ultrasonic flaw detector, positive pressure, or a vacuum head, as a non-limiting example. By performing the non-destructive testing, it is possible to prevent damage, such as cracks, from occurring in the saga.

[0054] The inspection unit determines whether the saga can be reused by the method described above, and if it can be reused, proceeds with a subsequent process for loading artificial graphite, and if it cannot be reused, it can be collected by discharging it separately to the outside. A transfer unit capable of bidirectional transfer of the inspection unit may be additionally connected, and the transfer unit may discharge the contaminated saga or supply new saga. At this time, the transfer unit capable of transfer may be connected to the aforementioned transfer unit (120) so that a series of processes can be performed continuously.

[0055] In one embodiment, the sago that has passed through the inspection unit may have residual dust removed by a dust removal unit when reused. Specifically, the dust removal unit may remove the adhering residual dust using a component such as a blower.

[0056] In one embodiment, the sand that has passed through the inspection unit may be filled with artificial graphite, which is a raw material, by the filling unit. Specifically, the artificial graphite is filled into the sand that is determined to be reusable through the inspection unit or into newly supplied sand, and the sand filled with artificial graphite may be supplied to the calcination unit (120) by the aforementioned transfer unit (110).

[0058] The present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

Claim 1 An artificial graphite production system comprising: a conveying unit including a sagger containing artificial graphite as a raw material; a calcining unit calcining the sagger containing the artificial graphite; an artificial graphite hardness measuring unit measuring the hardness of the artificial graphite within the sagger; and a disintegration unit disintegrating the artificial graphite recovered from the artificial graphite hardness measuring unit, wherein the artificial graphite hardness measuring unit determines whether the hardness of the artificial graphite satisfies a target hardness range and transfers the artificial graphite satisfying the target hardness range to the disintegration unit. Claim 2 An artificial graphite production system according to claim 1, wherein the artificial graphite hardness measuring unit measures the hardness of the artificial graphite calcined in the slag, determines whether the hardness of the calcined artificial graphite satisfies the target hardness range, and if the target hardness range is satisfied, the slag is moved to the disintegration unit, and if the target hardness range is not satisfied, the slag containing the calcined artificial graphite is recovered to the recovery unit. Claim 3 In claim 2, the artificial graphite hardness measuring unit is an artificial graphite production system that is any one of a soil hardness tester, a Vickers hardness tester, a Rockwell hardness tester, and a nanoindenter. Claim 4 In claim 3, when the artificial graphite hardness measuring unit is a soil hardness meter, an artificial graphite production system that measures by pressing the needle of the soil hardness meter to a certain depth from the surface of the artificial graphite powder placed within the above-mentioned structure. Claim 5 In claim 1, the calcination unit is an artificial graphite production system that mixes the artificial graphite and a coating material and calcines them. Claim 6 An artificial graphite production system according to claim 1, comprising a post-processing unit for recovering the artificial graphite that has passed through the crushing unit. Claim 7 In claim 6, the post-processing unit comprises: a dumping unit for dumping the saga; and a roll-mill unit for roll-milling the artificial graphite that has passed through the dumping unit, forming an artificial graphite production system. Claim 8 In claim 7, the post-processing unit comprises a storage unit that recovers and stores the artificial graphite that has passed through the roll mill unit, in an artificial graphite production system. Claim 9 In claim 6, the post-processing unit further comprises an inspection unit for inspecting hollow saga collected from the artificial graphite; and a raw material charging unit for charging raw materials into the saga that has passed through the inspection unit, thereby forming an artificial graphite production system. Claim 10 An artificial graphite production system according to claim 1, further comprising a cooling unit for cooling the saga that has passed through the calcination unit. Claim 11 An artificial graphite production system according to claim 1, wherein the artificial graphite hardness measuring unit includes a control unit, and the control unit determines whether the hardness of the artificial graphite satisfies a target hardness range, delivers the artificial graphite that satisfies the target hardness range to a disintegration unit, and delivers the artificial graphite that does not satisfies the target hardness range to a recovery unit.

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