Manufacturing apparatus and manufacturing method for lithium hexafluorophosphate

Abstract

Disclosed are a manufacturing apparatus and manufacturing method for lithium hexafluorophosphate. The disclosed manufacturing apparatus for lithium hexafluorophosphate is configured to synthesize lithium hexafluorophosphate by reacting phosphorus pentafluoride with lithium fluoride and liquid anhydrous hydrogen fluoride, and comprises: a plurality of reactors connected to each other in series; and a plurality of recrystallizers connected to each other in series and installed downstream of the plurality of reactors so as to recrystallize the lithium hexafluorophosphate synthesized in the presence of phosphorus pentafluoride.

Description

Manufacturing device and manufacturing method of lithium hexafluorophosphate

[0001] A manufacturing device and method for lithium hexafluorophosphate are disclosed. More specifically, a manufacturing device and method for lithium hexafluorophosphate are disclosed, which can mass-produce high-purity lithium hexafluorophosphate having a small average particle size and a uniform particle size distribution.

[0002] Lithium hexafluorophosphate (LiPF6) is the most common electrolyte salt used in commercial lithium-ion batteries. Lithium-ion batteries are secondary batteries in which lithium ions intercalate and deintercalate between the positive and negative electrodes through an electrolyte solution prepared by dissolving the electrolyte salt in a non-aqueous organic solvent. Lithium hexafluorophosphate (LiPF6) is used as an electrolyte salt. It boasts excellent applicability and environmental friendliness, and is currently an essential electrolyte salt that cannot be replaced by other electrolytes in lithium-ion battery manufacturing.

[0003] There are many patents and literature on methods for manufacturing lithium hexafluorophosphate (LiPF6), but most of them only report on methods for manufacturing lithium hexafluorophosphate (LiPF6) and purification of intermediates, and there are almost no reports on methods for directly purifying lithium hexafluorophosphate (LiPF6).

[0004] For example, U.S. Patent No. 6,500,399 proposes a method for obtaining high-purity lithium hexafluorophosphate (LiPF6) by using starting materials with low impurity content and reacting at low temperatures to reduce the introduction of impurities. JP 4175216 et al. propose a method for purifying PF5, an intermediate for the synthesis of lithium hexafluorophosphate.

[0005] U.S. Patent No. 3,594,402 describes a method for producing and purifying lithium hexafluorophosphate (LiPF6) in acetonitrile. However, this method is difficult to implement on a commercial scale and involves numerous steps, making it difficult to commercialize.

[0006] The currently known purification methods of lithium hexafluorophosphate require high temperatures and pressures, have high requirements for equipment and materials, and may introduce metal impurity ions when the equipment corrodes. In addition, impurities (LiPO) generated by unreacted substances and moisture during the reaction process of phosphorus pentafluoride (PF5) x F y ) There is a problem with this product that affects the quality of the product.

[0007] There have been various methods proposed in the past for manufacturing lithium hexafluorophosphate (LiPF6). A method of reacting phosphorus pentafluoride (PF5), which can be obtained by reacting anhydrous hydrogen fluoride (HF) and phosphorus pentafluoride (PCl5), with liquid lithium fluoride (LiF) dissolved in anhydrous hydrogen fluoride (HF) (Japanese Patent Application Publication No. Hei 4-175216) relates to a method of manufacturing LiPF6 by reacting phosphorus pentafluoride (PCl5, solid) and anhydrous HF to synthesize PF5, and introducing phosphorus pentafluoride (PF5) into a solution prepared by dissolving LiF in anhydrous liquid anhydrous hydrogen fluoride. The problem with this method is that the phosphorus pentafluoride (PCl5) and anhydrous hydrogen fluoride (HF) used react to produce PF5 and HCl, but in the process of removing HCl, a lot of PF5, which has a boiling point (-84.6℃) similar to that of HCl (-85.05℃), is lost, resulting in a low product yield. In addition, it is necessary to additionally use phosphorus pentafluoride (PF5) to complete the reaction with unreacted lithium fluoride (LiF). In reality, since the reaction efficiency gradually decreases as the reaction progresses, in the above method, unreacted lithium fluoride (LiF) remains as an impurity after the reaction is completed (US 3,654,330). In addition, when the reaction system contains moisture during the production and reaction of phosphorus pentafluoride (PF5), phosphorus pentafluoride (PF5) is hydrolyzed to produce phosphoryl fluoride (POF3), and POF3 reacts with additional moisture to produce lithium oxyfluorophosphate (LiPO). x F y) is produced as a by-product. Therefore, when producing high-purity lithium hexafluorophosphate, unreacted lithium fluoride (LiF) and moisture are thoroughly removed to produce lithium oxyfluorophosphate (LiPO). x F y ) It is desirable to fundamentally block the generation of byproducts.

[0008] CN 110683564 B discloses a method for producing high-purity lithium hexafluorophosphate crystals for research purposes by directly using ultrasound in a microchannel reactor, CN 106745096 A discloses a method for producing lithium hexafluorophosphate by injecting phosphorus pentafluoride (PF5) gas and lithium fluoride (LiF) solution into a microchannel reactor, and CN 115784264 A discloses a method for inducing nucleation of crystals by ultrasonic vibration (50-500 kHz, 50-300 W, 2.5 hr) in a 1 L reactor and improving the quality of the product by irradiating a freeze-drying integrated device with microwaves (300-1000 W), but the above methods are not applicable to mass production.

[0009] CN 105600809 B induces nucleation by directly using ultrasound (power: 200 to 400 W, frequency: 20 to 40 KHz) in a lithium hexafluorophosphate solution reactor, and causes uniform nucleation of lithium hexafluorophosphate in a metastable region of supersaturation. However, the method of directly using ultrasound in a reactor has limitations in application to mass production.

[0010] The synthesis of lithium hexafluorophosphate (LiPF6), which is generally known, can be carried out using anhydrous hydrogen fluoride as a solvent through the following two-step process.

[0011] PCl5(s)+ 5 anhydrous HF(l) → PF5(g)+ 5HCl(g)

[0012] PF5(g) + LiF(s) + anhydrous HF(l) → LiPF6(s) + anhydrous HF(l)

[0013] Currently, the most widely used method for commercial synthesis of lithium hexafluorophosphate (LiPF6) is the hydrogen fluoride (HF) solvent method as shown in the above reaction scheme, that is, dissolving lithium fluoride (LiF) in phosphorus pentafluoride (PF5) and anhydrous hydrogen fluoride (HF) liquid, and then reacting lithium fluoride (LiF) with phosphorus pentafluoride (PF5) to obtain lithium hexafluorophosphate solution. However, if the reaction system contains even a little moisture in this reaction, lithium oxyfluorophosphate (LiPO) x F y ) is produced. Additionally, unreacted LiF may remain as an impurity (see US 3,654,330).

[0014] Therefore, lithium hexafluorophosphate containing impurities during the synthesis process can significantly reduce battery performance, and the particle size and uniformity of lithium hexafluorophosphate crystals can affect the dissolution and heat dissipation characteristics in secondary battery electrolytes. Accordingly, extensive research has been conducted to obtain high-purity LiPF6.

[0015] One embodiment of the present invention provides a device for producing lithium hexafluorophosphate, which can mass-produce high-purity lithium hexafluorophosphate having a small average particle size and a uniform particle size distribution.

[0016] Another embodiment of the present invention provides a method for producing lithium hexafluorophosphate, which can produce lithium hexafluorophosphate in large quantities with high purity and a small average particle size and uniform particle size distribution.

[0017] One aspect of the present invention is:

[0018] A plurality of reactors connected in series to synthesize lithium hexafluorophosphate by reacting phosphorus pentafluoride with lithium fluoride and liquid anhydrous hydrogen fluoride; and

[0019] A device for producing lithium hexafluorophosphate is provided, which includes a plurality of recrystallizers connected in series to each other, and is installed at the rear end of the plurality of reactors so as to recrystallize the synthesized lithium hexafluorophosphate in the presence of phosphorus pentafluoride.

[0020] The above lithium hexafluorophosphate manufacturing device may further include a lithium fluoride mixing reactor installed at a front end of the plurality of reactors, configured to mix lithium fluoride and liquid anhydrous hydrogen fluoride.

[0021] The above lithium hexafluorophosphate manufacturing device may further include a phosphorus pentafluoride manufacturing reactor configured to manufacture phosphorus pentafluoride and hydrogen chloride by reacting phosphorus pentafluoride and liquid anhydrous hydrogen fluoride.

[0022] The above lithium hexafluorophosphate manufacturing device can be configured to supply phosphorus pentafluoride and hydrogen chloride manufactured in the phosphorus pentafluoride manufacturing reactor to the plurality of reactors and the plurality of recrystallizers, respectively.

[0023] The above lithium hexafluorophosphate manufacturing device may further include a dual drying device configured to dry phosphorus pentafluoride and hydrogen chloride manufactured in the phosphorus pentafluoride manufacturing reactor.

[0024] The above lithium hexafluorophosphate manufacturing device can be configured to supply phosphorus pentafluoride and hydrogen chloride dried in the double drying device to the plurality of reactors and the plurality of recrystallizers, respectively.

[0025] The above-mentioned double drying device may include a primary drying device configured to remove impurities and moisture by adsorbing them with an adsorbent, and a secondary drying device configured to remove moisture using a semi-permeable membrane.

[0026] The above lithium hexafluorophosphate manufacturing device may be configured such that the liquid reactor effluent from the front reactor among the plurality of reactors flows into the rear reactor, and the gaseous reactor effluent from the rear reactor flows into the front reactor.

[0027] The liquid reactor effluent may comprise lithium fluoride, liquid anhydrous hydrogen fluoride, lithium hexafluorophosphate, or a combination thereof, and the gaseous reactor effluent may comprise gaseous anhydrous hydrogen fluoride, phosphorus pentafluoride, hydrogen chloride, or a combination thereof.

[0028] The above lithium hexafluorophosphate manufacturing device may be configured such that the liquid recrystallization effluent from the front recrystallizer among the plurality of recrystallizers flows into the rear recrystallizer, and the gaseous recrystallization effluent from the rear recrystallizer flows into the front recrystallizer.

[0029] The liquid recrystallizer effluent may comprise lithium fluoride, liquid anhydrous hydrogen fluoride, lithium hexafluorophosphate, or a combination thereof, and the gaseous recrystallizer effluent may comprise gaseous anhydrous hydrogen fluoride, phosphorus pentafluoride, hydrogen chloride, or a combination thereof.

[0030] The above lithium hexafluorophosphate manufacturing device may further include a microfilter arranged between the plurality of reactors and the plurality of recrystallizers.

[0031] The above lithium hexafluorophosphate manufacturing device may further include an ultrasonic generator disposed between the microfilter and the plurality of recrystallizers.

[0032] The above lithium hexafluorophosphate manufacturing device may further include a dynamic filter arranged at the rear end of the plurality of recrystallizers.

[0033] The above lithium hexafluorophosphate manufacturing device may further include a vibration dryer arranged at the rear end of the dynamic filter.

[0034] The above lithium hexafluorophosphate manufacturing apparatus may further include a separation and purification tower configured to separate hydrogen chloride and liquid anhydrous hydrogen fluoride from a gas phase reactor effluent from the plurality of reactors, a gas phase recrystallizer effluent from the plurality of recrystallizers, a gas phase vibration dryer effluent from the vibration dryer, or a combination thereof.

[0035] Another aspect of the present invention is:

[0036] A step (S10) of synthesizing lithium hexafluorophosphate by reacting phosphorus pentafluoride with lithium fluoride and liquid anhydrous hydrogen fluoride using multiple reactors connected in series; and

[0037] A method for producing lithium hexafluorophosphate is provided, including a step (S20) of recrystallizing the synthesized lithium hexafluorophosphate in the presence of phosphorus pentafluoride using a plurality of recrystallizers connected in series.

[0038] The above method for producing lithium hexafluorophosphate may further include, prior to the step (S10), a step (S5) of removing impurities and moisture from phosphorus pentafluoride and supplying the removed impurities and moisture to the step (S10) and the step (S20), respectively.

[0039] In the above step (S10), the flow directions of lithium fluoride and liquid anhydrous hydrogen fluoride and phosphorus pentafluoride may be opposite to each other, and in the above step (S20), the flow directions of lithium hexafluorophosphate and phosphorus pentafluoride may be opposite to each other.

[0040] The above method for producing lithium hexafluorophosphate may further include a step (S15) of irradiating the synthesized lithium hexafluorophosphate with ultrasound between the steps (S10) and (S20).

[0041] The above method for producing lithium hexafluorophosphate may further include, after the step (S20), a step (S30) of dynamically filtering the lithium hexafluorophosphate recrystallized in the step (S20) and a step (S40) of vibratingly drying the dynamically filtered lithium hexafluorophosphate, in this order.

[0042] The above method for producing lithium hexafluorophosphate may further include a step (S50) of separating hydrogen chloride and liquid anhydrous hydrogen fluoride from the gas phase reactor effluent of the step (S10), the gas phase recrystallizer effluent of the step (S20), the gas phase vibration dryer effluent of the step (S40), or a combination thereof.

[0043] The apparatus and method for manufacturing lithium hexafluorophosphate according to one embodiment of the present invention can produce a large quantity of high-purity lithium hexafluorophosphate having a small average particle size and a uniform particle size distribution.

[0044] FIG. 1 is a schematic drawing of a device for manufacturing lithium hexafluorophosphate according to one embodiment of the present invention.

[0045] Figure 2 is an enlarged drawing of the double drying device among the lithium hexafluorophosphate manufacturing devices of Figure 1.

[0046] Figure 3 is an enlarged drawing of the microfilter, ultrasonic generator, and surrounding parts of the lithium hexafluorophosphate manufacturing device of Figure 1.

[0047] Hereinafter, a manufacturing device and manufacturing method of lithium hexafluorophosphate according to one embodiment of the present invention will be described in detail.

[0048] In this specification, “front stage” means a reactor or recrystallizer located relatively to the left in FIG. 1, and “back stage” means a reactor or recrystallizer located relatively to the right in FIG. 1.

[0049] FIG. 1 is a schematic drawing of a device for manufacturing lithium hexafluorophosphate according to one embodiment of the present invention.

[0050] Referring to FIG. 1, an apparatus for manufacturing lithium hexafluorophosphate according to one embodiment of the present invention includes a plurality of reactors connected in series with each other and a plurality of recrystallizers connected in series with each other.

[0051] The above-mentioned plurality of reactors may be configured to synthesize lithium hexafluorophosphate (LiPF6) by reacting phosphorus pentafluoride (PF5) with lithium fluoride (LiF) and liquid anhydrous hydrogen fluoride (AHF) as in the following reaction scheme 1.

[0052] [Reaction Formula 1]

[0053] PF5(g) + LiF(l) + anhydrous HF(l) → LiPF6(l) + anhydrous HF(l)

[0054] Additionally, the plurality of reactors may include a primary reactor, a secondary reactor, and a tertiary reactor, but the present invention is not limited thereto.

[0055] Additionally, each of the plurality of reactors may be a CSTR (continuous stirred tank reactor), but the present invention is not limited thereto.

[0056] Additionally, each of the plurality of reactors can be maintained at a reaction temperature of 10 to 20°C.

[0057] In addition, the above lithium hexafluorophosphate manufacturing device may be configured such that the liquid reactor effluent from the front reactor among the plurality of reactors flows into the rear reactor, and the gaseous reactor effluent from the rear reactor flows into the front reactor. Accordingly, unreacted lithium fluoride (LiF) in the liquid reactor effluent and phosphorus pentafluoride (PF5) in the gaseous reactor effluent can react with each other, so that the unreacted lithium fluoride can be almost completely consumed. That is, phosphorus pentafluoride (PF5) is injected into the continuous overflow reactor at the bottom of the cascade reactors (third reactor → second reactor → first reactor) to react and remove the remaining lithium fluoride, and phosphorus pentafluoride (PF5) is economically consumed in the first reactor without using additional phosphorus pentafluoride (PF5), thereby reducing the loss cost due to the remaining phosphorus pentafluoride (PF5).

[0058] Additionally, phosphorus pentafluoride (PF5) can be supplied alone or together with nitrogen gas to the plurality of reactors (specifically, 3rd reactor → 2nd reactor → 1st reactor).

[0059] The liquid reactor effluent may comprise lithium fluoride, liquid anhydrous hydrogen fluoride, lithium hexafluorophosphate, or a combination thereof.

[0060] The above-described gaseous reactor effluent may comprise gaseous anhydrous hydrogen fluoride, phosphorus pentafluoride, hydrogen chloride, or a combination thereof.

[0061] The reaction proceeding according to the above reaction formula 1 is an exothermic reaction (ΔH = -85 kJ / mole), and in the step-by-step reaction (3rd reactor → 2nd reactor → 1st reactor in Fig. 1) through control of the reaction temperature, phosphorus pentafluoride (PF5) gas is exhausted, and unreacted HCl gas and some liquid anhydrous hydrogen fluoride gas can be transferred from the 1st reactor to a separation and purification tower and separated and purified.

[0062] In the above reaction formula 1, HCl(g) acts as an inert substance and is not indicated. It can be collected from the top of the separation and purification tower, packaged, and sold as a by-product.

[0063] The anhydrous liquid hydrogen fluoride (AHF) solvent can be condensed in the separation and purification tower and recycled.

[0064] The gas transferred from the primary reactor to the separation and purification tower may contain PF5 gas in a content of 1,000 ppm or less, preferably 250±50 ppm.

[0065] When the liquid reactor effluent from the third reactor is transferred to the first recrystallizer in an overflow manner, the liquid reactor effluent from the third reactor may contain 20±5 wt% of LiPF6 and 80±5 wt% of liquid anhydrous hydrogen fluoride.

[0066] The above plurality of recrystallizers may be configured to recrystallize the synthesized lithium hexafluorophosphate in the presence of phosphorus pentafluoride.

[0067] Additionally, the plurality of recrystallizers may be installed at the rear end of the plurality of reactors (specifically, the third reactor).

[0068] Additionally, the plurality of recrystallizers may include a primary recrystallizer, a secondary recrystallizer, and a tertiary recrystallizer, but the present invention is not limited thereto.

[0069] Additionally, each of the plurality of recrystallizers may be a CSTR (continuous stirred tank reactor), but the present invention is not limited thereto.

[0070] In addition, the above lithium hexafluorophosphate manufacturing device may be configured such that the liquid recrystallization effluent from the front recrystallizer among the plurality of recrystallizers flows into the rear recrystallizer, and the gaseous recrystallization effluent from the rear recrystallizer flows into the front recrystallizer.

[0071] Additionally, phosphorus pentafluoride (PF5) can be supplied alone or together with nitrogen gas to the plurality of recrystallizers (specifically, 3rd recrystallizer → 2nd recrystallizer → 1st recrystallizer).

[0072] The liquid recrystallizer effluent may comprise lithium fluoride, liquid anhydrous hydrogen fluoride, lithium hexafluorophosphate, or a combination thereof.

[0073] The above-described gas phase recrystallizer effluent may comprise gas phase anhydrous hydrogen fluoride, phosphorus pentafluoride, hydrogen chloride or a combination thereof.

[0074] The crystallization reaction of lithium hexafluorophosphate (LiPF6) can be carried out sequentially in the first recrystallizer, the second recrystallizer, and the third recrystallizer using a stepwise overflow dynamic continuous process method. Specifically, the temperature of the crystallization reactor is gradually lowered to -10±5℃, -20±5℃, and -30±5℃ by stepwise bubbling in the first, second, and third recrystallizers, and the average particle size of lithium hexafluorophosphate (LiPF6) can be controlled by performing the crystallization process through the stirring speed and temperature change. As a result, the liquid reactor effluent from the third reactor can be crystallized while cooling at a cooling rate of 2 to 3℃ / hr while passing through the first, second, and third recrystallizers in sequence.

[0075] The above lithium hexafluorophosphate manufacturing device may further include a lithium fluoride (LiF) mixing reactor.

[0076] The above lithium fluoride mixing reactor can be configured to mix lithium fluoride and liquid anhydrous hydrogen fluoride.

[0077] In addition, the lithium fluoride mixed reactor may be installed at the front end of the plurality of reactors (specifically, the first reactor).

[0078] In addition, the above lithium hexafluorophosphate manufacturing device may further include a phosphorus pentafluoride (PF5) manufacturing reactor.

[0079] The above phosphorus pentafluoride manufacturing reactor can be configured to manufacture phosphorus pentafluoride (PF5) and hydrogen chloride (HCl) by reacting phosphorus pentafluoride (PCl5) and liquid anhydrous hydrogen fluoride (HF) as shown in the following reaction scheme 2.

[0080] [Reaction Formula 2]

[0081] PCl5(s)+ 5 anhydrous HF(l) → PF5(g) + 5HCl(g)

[0082]

[0083] In addition, the above lithium hexafluorophosphate manufacturing device may be configured to supply phosphorus pentafluoride (PF5) and hydrogen chloride (HCl) manufactured in the phosphorus pentafluoride manufacturing reactor to the plurality of reactors and the plurality of recrystallizers, respectively.

[0084] In addition, the above lithium hexafluorophosphate manufacturing device may further include a double drying device.

[0085] The above-mentioned double drying device can be configured to dry phosphorus pentafluoride and hydrogen chloride produced in the above-mentioned pentafluoride production reactor.

[0086] In addition, the above lithium hexafluorophosphate manufacturing device can be configured to supply phosphorus pentafluoride and hydrogen chloride dried in the double drying device to the plurality of reactors and the plurality of recrystallizers, respectively.

[0087] Figure 2 is an enlarged drawing of the double drying device among the lithium hexafluorophosphate manufacturing devices of Figure 1.

[0088] Referring to FIG. 2, the double drying device may include a primary drying device and a secondary drying device.

[0089] The above primary drying device can be configured to remove impurities and moisture by adsorbing them with an adsorbent.

[0090] The above adsorbent may include molecular sieve 3A, molecular sieve 13X, or a combination thereof, which are types of zeolite, but the present invention is not limited thereto.

[0091] The secondary drying device may be configured to remove moisture using a semipermeable membrane. For example, the secondary drying device may be configured to remove moisture by passing a mixed gas of PF5 and HCl through the inside of a cylindrical semipermeable membrane and passing a drying gas, such as nitrogen, through the outer periphery surrounding the semipermeable membrane in a direction opposite to the flow direction of the mixed gas. Through this, lithium oxyfluorophosphate (LiPO) that may be generated during the reaction in the future x F y ) can be minimized.

[0092] The semipermeable membrane may be configured to allow dry gases such as water vapor and nitrogen to pass through, but not a mixed gas of PF5 and HCl. For example, the semipermeable membrane may be a Nafion membrane, but the present invention is not limited thereto.

[0093] Additionally, the above lithium hexafluorophosphate manufacturing device may further include a microfilter.

[0094] The above microfilter may be configured to remove impurities from the liquid reactor effluent (specifically, the liquid reactor effluent from the third reactor).

[0095] Figure 3 is an enlarged drawing of the microfilter, ultrasonic generator, and surrounding parts of the lithium hexafluorophosphate manufacturing device of Figure 1.

[0096] Referring to FIG. 3, the microfilter may be disposed between the plurality of reactors (specifically, a third reactor) and the plurality of recrystallizers (specifically, a first recrystallizer).

[0097] In addition, the above lithium hexafluorophosphate manufacturing device may further include an ultrasonic generator.

[0098] The above ultrasonic generator plays a role of inducing nucleation in the liquid reactor effluent (specifically, the liquid reactor effluent from the third reactor). Specifically, the ultrasonic generator plays a role of reducing the metastable zone width (MZW) of the liquid reactor effluent from the third reactor, and the 'liquid reactor effluent from the third reactor' with the reduced metastable zone width is injected into a recrystallizer to produce high-purity lithium hexafluorophosphate crystals. If the recrystallization process of lithium hexafluorophosphate is carried out in the unstable zone, the nucleation and crystallization occur simultaneously, which makes it very difficult to control the particle size distribution of lithium hexafluorophosphate. Therefore, the lithium hexafluorophosphate manufacturing device of the present invention can form nuclei in the metastable region, maintain the particle size distribution, and increase only the average particle size, and produce a high-purity product with a uniform particle size distribution in a stepwise manner during the recrystallization process. Therefore, during mass production, the metastable region is very important for controlling product quality and achieving optimization of the production process.

[0099] The above ultrasonic generator generates ultrasonic vibration, which is helpful for obtaining fine particle LiPF6 crystals, and the frequency band for inducing ultrasonic vibration is 10 to 50 KHz, and the power range of ultrasonic vibration can be 500 to 16000 W. The preferred frequency band for inducing ultrasonic vibration is 20 to 30 KHz, and the power range of ultrasonic vibration can be 1000 to 4000 W. An industrial ultrasonic vibration reactor chamber can be used, and the moving speed of the liquid in the flow mode is 1.0 to 8.0 L / min, and it can operate for 24 hours, and can realize continuous flow through the ultrasonic system with a capacity of about 2 to 10 m³ / day.

[0100] Referring to FIG. 3, the ultrasonic generator may be disposed between the microfilter and the plurality of recrystallizers (specifically, primary recrystallizers). By disposing the ultrasonic generator between the microfilter and the plurality of recrystallizers in this way, ultrasonic waves are not directly irradiated into the plurality of recrystallizers, but only to the liquid reactor effluent before being introduced into the plurality of recrystallizers. Therefore, even if the capacity of the ultrasonic generator is small, crystal nucleation can be induced for a large amount of the liquid reactor effluent, thereby enabling mass production of lithium hexafluorophosphate.

[0101] In addition, the above lithium hexafluorophosphate manufacturing device may further include a dynamic filtering device.

[0102] The above dynamic filter may be configured to filter the recrystallized lithium hexafluorophosphate in the presence of phosphorus pentafluoride.

[0103] Additionally, phosphorus pentafluoride (PF5) can be supplied to the dynamic filter alone or together with nitrogen gas.

[0104] The above dynamic filter may be placed at the rear end of the plurality of recrystallizers (specifically, a third recrystallizer).

[0105] The above dynamic filter may be configured in a cone shape and may include a double-walled container having a cavity, a conical stainless steel filter (pore size: 10 to 20 μm) mounted between the double walls, and a spiral impeller mounted within the cavity, and during dynamic filtration, the speed of the spiral impeller and the nitrogen gas pressure may be controlled to filter the liquid anhydrous hydrogen fluoride (AHF) solvent through the conical stainless steel filter, and the filtered liquid anhydrous hydrogen fluoride solvent may be reused.

[0106] In addition, the above lithium hexafluorophosphate manufacturing device may further include a vibration dryer.

[0107] The above vibration dryer may be placed at the rear end of the above dynamic filter.

[0108] The above vibration dryer can prevent solids from accumulating and improve the particle size and filtration effect of lithium hexafluorophosphate by including a vibrator using variable magnetic flux.

[0109] In addition, the above lithium hexafluorophosphate manufacturing device may further include a separation and purification tower.

[0110] The above separation and purification tower may be configured to separate hydrogen chloride and liquid anhydrous hydrogen fluoride from the gas phase reactor effluent from the plurality of reactors, the gas phase recrystallizer effluent from the plurality of recrystallizers, the gas phase vibration dryer effluent from the vibration dryer, or a combination thereof.

[0111] An apparatus for manufacturing lithium hexafluorophosphate according to one embodiment of the present invention having the above configuration can manufacture lithium hexafluorophosphate having a purity of 99.9% or higher and an average particle size of 400㎛ or less.

[0112] Hereinafter, a method for manufacturing lithium hexafluorophosphate according to one embodiment of the present invention will be described in detail.

[0113] A method for producing lithium hexafluorophosphate according to one embodiment of the present invention can be performed using the above-described apparatus for producing lithium hexafluorophosphate.

[0114] A method for producing lithium hexafluorophosphate according to one embodiment of the present invention includes a step (S10) of synthesizing lithium hexafluorophosphate by reacting phosphorus pentafluoride with lithium fluoride and liquid anhydrous hydrogen fluoride using a plurality of reactors connected in series with each other, and a step (S20) of recrystallizing the synthesized lithium hexafluorophosphate in the presence of phosphorus pentafluoride using a plurality of recrystallizers connected in series with each other.

[0115] The above method for producing lithium hexafluorophosphate may further include, prior to the step (S10), a step (S5) of removing impurities and moisture from phosphorus pentafluoride and supplying the removed impurities and moisture to the step (S10) and the step (S20), respectively.

[0116] In the above step (S10), the flow direction of lithium fluoride and liquid anhydrous hydrogen fluoride and the flow direction of phosphorus pentafluoride may be opposite to each other.

[0117] Similarly, in the above step (S20), the flow direction of lithium hexafluorophosphate and the flow direction of phosphorus pentafluoride may be opposite to each other.

[0118] In addition, the method for producing lithium hexafluorophosphate may further include a step (S15) of irradiating the synthesized lithium hexafluorophosphate with ultrasound between the step (S10) and the step (S20).

[0119] In addition, the method for manufacturing lithium hexafluorophosphate may further include, after the step (S20), a step (S30) of dynamically filtering the lithium hexafluorophosphate recrystallized in the step (S20) and a step (S40) of vibratingly drying the dynamically filtered lithium hexafluorophosphate, in this order.

[0120] In addition, the method for producing lithium hexafluorophosphate may further include a step (S50) of separating hydrogen chloride and liquid anhydrous hydrogen fluoride from the gas phase reactor effluent of the step (S10), the gas phase recrystallizer effluent of the step (S20), the gas phase vibration dryer effluent of the step (S40), or a combination thereof.

[0121] Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited to the following examples.

[0122] Manufacturing Example 1: Manufacturing of a device for manufacturing lithium hexafluorophosphate

[0123] A lithium hexafluorophosphate manufacturing device having a configuration similar to the lithium hexafluorophosphate manufacturing device illustrated in FIGS. 1 to 3 was manufactured. A Hielscher Ultrasonics UIP2000hdT (20 kHz, 2 kW) ultrasonic generator was introduced and installed.

[0124] Manufacturing Example 2: Manufacturing of a device for manufacturing lithium hexafluorophosphate

[0125] An apparatus for producing lithium hexafluorophosphate was manufactured in the same manner as in Manufacturing Example 1, except that the three reactors were replaced with one reactor having the same volume as the total volume thereof, and the three recrystallizers were replaced with one recrystallizer having the same volume as the total volume thereof.

[0126] Manufacturing Example 3: Manufacturing of a device for manufacturing lithium hexafluorophosphate

[0127] A device for producing lithium hexafluorophosphate was manufactured in the same manner as in Manufacturing Example 1, except that the three reactors above were replaced with one reactor having the same volume as the total volume of these reactors.

[0128] Manufacturing Example 4: Manufacturing of a device for manufacturing lithium hexafluorophosphate

[0129] A device for producing lithium hexafluorophosphate was manufactured in the same manner as in Manufacturing Example 1, except that the three recrystallizers were replaced with one recrystallizer having the same volume as the total volume of the three recrystallizers.

[0130] Manufacturing Example 5: Manufacturing of a device for manufacturing lithium hexafluorophosphate

[0131] A device for manufacturing lithium hexafluorophosphate was manufactured using the same method as in Manufacturing Example 1, except that the double drying device was replaced with a molecular sieve filter.

[0132] Manufacturing Example 6: Manufacturing of a device for manufacturing lithium hexafluorophosphate

[0133] A device for manufacturing lithium hexafluorophosphate was manufactured using the same method as Manufacturing Example 1, except that the ultrasonic generator was omitted.

[0134] Example 1: Preparation of lithium hexafluorophosphate

[0135] Lithium hexafluorophosphate was manufactured by going through the following steps using the manufacturing device for lithium hexafluorophosphate manufactured in Manufacturing Example 1 above.

[0136] First, 0.18 tons of lithium fluoride (LiF) and anhydrous hydrogen fluoride (AHF) were injected into a LiF mixing reactor and mixed well to produce a mixture, which was then injected in a cascade manner into three reactors connected in series (reaction temperature: 15°C). In addition, 1.45 tons of phosphorus pentafluoride (PCl5) and 0.75 tons of anhydrous hydrogen fluoride (AHF) were injected into a PF5 production reactor to produce a mixed gas of phosphorus pentafluoride (PF5) and hydrogen chloride (HCl).

[0137] Next, the mixed gas of phosphorus pentafluoride (PF5) and hydrogen chloride (HCl) generated in the PF5 production reactor was passed through a double filter to remove impurities and vapor moisture, and then passed through the three reactors in the reverse direction in a bubbling manner to produce lithium hexafluorophosphate. The three reactors were stirred at a constant stirring speed, and as the gas passed through the three reactors, lithium fluoride (LiF) and phosphorus pentafluoride (PF5) reacted with each other and were consumed, so that the concentration of phosphorus pentafluoride (PF5) in the mixed gas flowing into the separation and purification tower was maintained at 300±100 ppm. Meanwhile, the hydrogen chloride (HCl) flowing into the separation and purification tower can be separated into a hydrochloric acid solution as a by-product in the separation and purification tower and reused.

[0138] Next, the lithium hexafluorophosphate produced in the three reactors was passed through a microfilter to remove impurities (metal ions Fe, Ni, Mn, Al, etc.) before being injected into the three recrystallizers, and the lithium hexafluorophosphate passing through the microfilter was irradiated with ultrasonic waves by an ultrasonic generator (frequency band: 25 kHz, ultrasonic vibration power range: 2500 W) installed in the transfer pipe to induce the creation of crystal nuclei. At this time, the movement speed of the 'liquid reactor effluent from the third reactor' passing through the ultrasonic generator was 4.5 L / min.

[0139] Next, the lithium hexafluorophosphate that had undergone the above ultrasonic irradiation was injected into three recrystallizers to carry out the crystallization reaction stepwise. At this time, the first recrystallizer was maintained at -10±5℃, the second recrystallizer was maintained at -20±5℃, and the third recrystallizer was maintained at -30±5℃, so that the recrystallization temperature was gradually lowered stepwise to carry out the recrystallization.

[0140] Next, the liquid effluent discharged from the third recrystallizer was injected into a cone type filtering device and subjected to pressure filtration using nitrogen (N2).

[0141] Next, the liquid effluent discharged from the dynamic cone filter was injected into a vibration dryer and vacuum dried. As a result, lithium hexafluorophosphate was obtained.

[0142] Comparative Example 1: Preparation of lithium hexafluorophosphate

[0143] Lithium hexafluorophosphate was manufactured in the same manner as in Example 1, except that the lithium hexafluorophosphate manufacturing apparatus manufactured in Manufacturing Example 2 was used instead of the lithium hexafluorophosphate manufacturing apparatus manufactured in Manufacturing Example 1.

[0144] Comparative Example 2: Preparation of lithium hexafluorophosphate

[0145] Lithium hexafluorophosphate was manufactured in the same manner as in Example 1, except that the lithium hexafluorophosphate manufacturing apparatus manufactured in Manufacturing Example 3 was used instead of the lithium hexafluorophosphate manufacturing apparatus manufactured in Manufacturing Example 1.

[0146] Comparative Example 3: Preparation of lithium hexafluorophosphate

[0147] Lithium hexafluorophosphate was manufactured in the same manner as in Example 1, except that the lithium hexafluorophosphate manufacturing apparatus manufactured in Manufacturing Example 4 was used instead of the lithium hexafluorophosphate manufacturing apparatus manufactured in Manufacturing Example 1.

[0148] Comparative Example 4: Preparation of lithium hexafluorophosphate

[0149] Lithium hexafluorophosphate was manufactured in the same manner as in Example 1, except that the lithium hexafluorophosphate manufacturing apparatus manufactured in Manufacturing Example 5 was used instead of the lithium hexafluorophosphate manufacturing apparatus manufactured in Manufacturing Example 1.

[0150] Comparative Example 5: Preparation of lithium hexafluorophosphate

[0151] Lithium hexafluorophosphate was manufactured in the same manner as in Example 1, except that the lithium hexafluorophosphate manufacturing apparatus manufactured in Manufacturing Example 6 was used instead of the lithium hexafluorophosphate manufacturing apparatus manufactured in Manufacturing Example 1.

[0152]

[0153] Evaluation Example 1: Evaluation of insoluble matter content, impurity content, and purity of lithium hexafluorophosphate

[0154] The insoluble matter content, impurity content, and purity of lithium hexafluorophosphate manufactured in Example 1 and Comparative Examples 1 to 5 were evaluated, and the results are shown in Table 1 below. Here, insoluble matter (LiF) refers to a substance that does not dissolve in dimethyl ether (DME). Among the impurities, the moisture content was measured using a Karl-Fisher Coulometer, the HF content was measured using a Coulometric titration method, the Cl content was measured using an AgNO3 titration method, and the SO4 content was measured using a BaCl2 turbidimetric method. The purity of lithium hexafluorophosphate refers to the content of a substance that dissolves in dimethyl ether (DME).

[0155] Evaluation Example 2: Evaluation of the average particle size of lithium hexafluorophosphate

[0156] The average particle size of lithium hexafluorophosphate manufactured in Example 1 and Comparative Examples 1 to 5 was measured using a scanning electron microscope (SEM), and the results are shown in Table 1 below.

[0157] Evaluation Example 3: Yield Evaluation of Lithium Hexafluorophosphate

[0158] The yield of lithium hexafluorophosphate manufactured in Example 1 and Comparative Examples 1 to 5 was evaluated, and the results are shown in Table 1 below.

[0159] Number of double filtration reactorsNumber of ultrasonic irradiation recrystallizersInsolubles (ppm)HF (ppm)Moisture (ppm)Average particle size (㎛)Yield (%)Example 1Y3Y38158618083.9Comparative Example 1Y1Y1180951024070.2Comparative Example 2Y1Y3150851222074.4Comparative Example 3Y3Y18790923070.8Comparative Example 4N3Y3120901925076.5Comparative Example 5Y3N38570821080.2* Y / N: Yes / No Use*Product purity: Purity of all lithium hexafluorophosphates manufactured in Example 1 and Comparative Examples 1 to 5: > 99.9%

[0160]

[0161] Referring to Table 1 above, the lithium hexafluorophosphate manufactured in Example 1 had lower insoluble matter content, HF content, and moisture content, a smaller average particle size, and a higher yield than the lithium hexafluorophosphate manufactured in Comparative Examples 1 to 5.

[0162] While preferred embodiments of the present invention have been described above with reference to the drawings and examples, these are merely exemplary, and those skilled in the art will appreciate that various modifications and equivalent other embodiments are possible. Accordingly, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A plurality of reactors connected in series to synthesize lithium hexafluorophosphate by reacting phosphorus pentafluoride with lithium fluoride and liquid anhydrous hydrogen fluoride; and A device for producing lithium hexafluorophosphate, comprising a plurality of recrystallizers connected in series to each other, and installed at the rear end of the plurality of reactors to recrystallize the synthesized lithium hexafluorophosphate in the presence of phosphorus pentafluoride.

2. In paragraph 1, A device for producing lithium hexafluorophosphate, further comprising a lithium fluoride mixing reactor installed at a front end of the plurality of reactors, configured to mix lithium fluoride and liquid anhydrous hydrogen fluoride.

3. In paragraph 1, A device for producing lithium hexafluorophosphate, further comprising a phosphorus pentafluoride production reactor configured to produce phosphorus pentafluoride and hydrogen chloride by reacting phosphorus pentafluoride and liquid anhydrous hydrogen fluoride.

4. In paragraph 3, A device for manufacturing lithium hexafluorophosphate configured to supply phosphorus pentafluoride and hydrogen chloride manufactured in the above-mentioned pentafluoride manufacturing reactor to the plurality of reactors and the plurality of recrystallizers, respectively.

5. In paragraph 3, A device for manufacturing lithium hexafluorophosphate, further comprising a dual drying device configured to dry phosphorus pentafluoride and hydrogen chloride manufactured in the above-mentioned phosphorus pentafluoride manufacturing reactor.

6. In paragraph 5, A device for manufacturing lithium hexafluorophosphate configured to supply phosphorus pentafluoride and hydrogen chloride dried in the above double drying device to the plurality of reactors and the plurality of recrystallizers, respectively.

7. In paragraph 5, The above double drying device is a device for manufacturing lithium hexafluorophosphate, including a primary drying device configured to remove impurities and moisture by adsorbing them with an adsorbent, and a secondary drying device configured to remove moisture using a semipermeable membrane.

8. In paragraph 1, A device for producing lithium hexafluorophosphate, wherein the liquid reactor effluent from the front reactor among the plurality of reactors is configured to flow into the rear reactor, and the gaseous reactor effluent from the rear reactor is configured to flow into the front reactor.

9. In paragraph 1, A device for producing lithium hexafluorophosphate, wherein the liquid reactor effluent comprises lithium fluoride, liquid anhydrous hydrogen fluoride, lithium hexafluorophosphate, or a combination thereof, and the gaseous reactor effluent comprises gaseous anhydrous hydrogen fluoride, phosphorus pentafluoride, hydrogen chloride, or a combination thereof.

10. In paragraph 1, A device for manufacturing lithium hexafluorophosphate, wherein the liquid recrystallization effluent from the front recrystallizer among the plurality of recrystallizers is configured to flow into the rear recrystallizer, and the gaseous recrystallization effluent from the rear recrystallizer is configured to flow into the front recrystallizer.

11. In paragraph 10, A device for producing lithium hexafluorophosphate, wherein the liquid recrystallizer effluent comprises lithium fluoride, liquid anhydrous hydrogen fluoride, lithium hexafluorophosphate, or a combination thereof, and the gaseous recrystallizer effluent comprises gaseous anhydrous hydrogen fluoride, phosphorus pentafluoride, hydrogen chloride, or a combination thereof.

12. In paragraph 1, A device for producing lithium hexafluorophosphate, further comprising a microfilter disposed between the plurality of reactors and the plurality of recrystallizers.

13. In paragraph 12, A device for manufacturing lithium hexafluorophosphate, further comprising an ultrasonic generator disposed between the microfilter and the plurality of recrystallizers.

14. In paragraph 1, A device for manufacturing lithium hexafluorophosphate, further comprising a dynamic filter disposed at a rear end of the plurality of recrystallizers.

15. In paragraph 14, A device for manufacturing lithium hexafluorophosphate, further comprising a vibration dryer disposed at a rear end of the above dynamic filter.

16. In paragraph 15, A device for producing lithium hexafluorophosphate, further comprising a separation and purification tower configured to separate hydrogen chloride and liquid anhydrous hydrogen fluoride from a gas phase reactor effluent from the plurality of reactors, a gas phase recrystallizer effluent from the plurality of recrystallizers, a gas phase vibration dryer effluent from the vibration dryer, or a combination thereof.

17. A step (S10) of synthesizing lithium hexafluorophosphate by reacting phosphorus pentafluoride with lithium fluoride and liquid anhydrous hydrogen fluoride using multiple reactors connected in series; and A method for producing lithium hexafluorophosphate, comprising a step (S20) of recrystallizing the synthesized lithium hexafluorophosphate in the presence of phosphorus pentafluoride using a plurality of recrystallizers connected in series.

18. In paragraph 17, A method for producing lithium hexafluorophosphate, further comprising a step (S5) of removing impurities and moisture from pentafluoride and supplying the removed impurities and moisture to the step (S10) and the step (S20), respectively, prior to the above step (S10).

19. In paragraph 17, A method for producing lithium hexafluorophosphate, wherein the flow directions of lithium fluoride and liquid anhydrous hydrogen fluoride and phosphorus pentafluoride in the above step (S10) are opposite to each other, and the flow directions of lithium hexafluorophosphate and phosphorus pentafluoride in the above step (S20) are opposite to each other.

20. In paragraph 17, A method for producing lithium hexafluorophosphate, further comprising a step (S15) of irradiating the synthesized lithium hexafluorophosphate with ultrasound between the above steps (S10) and (S20).

21. In paragraph 17, A method for producing lithium hexafluorophosphate, which further comprises, in this order, a step (S30) of dynamically filtering the lithium hexafluorophosphate recrystallized in the step (S20) and a step (S40) of vibratingly drying the dynamically filtered lithium hexafluorophosphate, after the above step (S20).

22. In paragraph 17, A method for producing lithium hexafluorophosphate, further comprising a step (S50) of separating hydrogen chloride and liquid anhydrous hydrogen fluoride from the gas phase reactor effluent of the step (S10), the gas phase recrystallizer effluent of the step (S20), the gas phase vibration dryer effluent of the step (S40), or a combination thereof.

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