Degassing device and method for liquid lithium hexafluorophosphate

Abstract

A degassing device and method for liquid lithium hexafluorophosphate, the degassing device comprising: a scraper evaporator (E201), a post-degassing concentration and collection tank (V301), a condenser (E202), a solvent collection tank (V303) and a vacuum pump (P103), wherein the scraper evaporator (E201) is connected to a conveying line for raw liquid lithium hexafluorophosphate. The raw liquid lithium hexafluorophosphate is heated by the scraper evaporator (E201) and undergoes a rotational centrifugal force of same; thus, part of the liquid is vaporized, and the vaporized material is conveyed into the condenser (E202). The unvaporized liquid is conveyed to the post-degassing concentration and collection tank (V301). An output end of the condenser (E202) is connected to the solvent collection tank (V303), and a gas-phase output end of the solvent collection tank (V303) is connected to the vacuum pump (P103). Thus, an efficient and excellent degassing effect is achieved, it is ultimately ensured that the content of hydrogen chloride in liquid lithium hexafluorophosphate after a degassing treatment is less than 10 ppm, and the performance of the liquid lithium hexafluorophosphate when used as a component of an electrolyte in lithium ion batteries is also ensured.

Description

A degassing device and degassing method for liquid lithium hexafluorophosphate

[0001] This application claims priority to a Chinese patent application filed with the Patent Office of the State Intellectual Property Office of China on November 28, 2023, with application number 202311604494X and invention name “A degassing device for liquid lithium hexafluorophosphate and its degassing method”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention belongs to the field of lithium ion battery electrolyte, and in particular relates to a degassing device and a degassing method for liquid lithium hexafluorophosphate. Background Art

[0003] Liquid lithium hexafluorophosphate is typically synthesized by reacting lithium fluoride suspended in a carbonate with phosphorus pentafluoride / hydrogen chloride gas. Consequently, a certain proportion of hydrogen chloride gas is dissolved in the resulting liquid lithium hexafluorophosphate. This hydrogen chloride gas, an impurity in the liquid lithium salt, needs to be removed to purify and remove impurities from the liquid lithium hexafluorophosphate material system. The purified and impurity-free liquid lithium hexafluorophosphate is then used in lithium-ion battery electrolyte formulations to replace solid lithium hexafluorophosphate.

[0004] Furthermore, due to the polarization effect of lithium hexafluorophosphate in the solvent, the solubility of gaseous hydrogen chloride in the solvent increases. The applicant has tested that the lithium hexafluorophosphate content in liquid lithium hexafluorophosphate is 28-30%, the hydrogen chloride content is 5-6%, and the remaining components are trace amounts of hydrogen fluoride and solvent. When it is used as an electrolyte for lithium-ion batteries, it will obviously affect the working performance of the lithium-ion battery. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a degassing device and a degassing method for liquid lithium hexafluorophosphate, which achieves efficient and excellent degassing effect, and ultimately ensures that the hydrogen chloride content of the liquid lithium hexafluorophosphate after degassing treatment of the present application is less than 10ppm, thereby reliably ensuring its performance when used as an electrolyte in lithium-ion batteries.

[0006] The technical solution adopted in the present invention is as follows:

[0007] A degassing device for liquid lithium hexafluorophosphate comprises a scraper evaporator, a post-degassing concentration collection tank, a condenser, a solvent collection tank and a vacuum pump, wherein:

[0008] The scraper evaporator is connected to a delivery pipeline of liquid lithium hexafluorophosphate raw material. Under the heating and rotating centrifugal force of the scraper evaporator, part of the liquid of the liquid lithium hexafluorophosphate raw material is vaporized, and the vaporized material is transported to the condenser, and the unvaporized liquid is transported to the degassing concentration collection tank;

[0009] The output end of the condenser is connected to the solvent collecting tank, and the gas phase output end of the solvent collecting tank is connected to the vacuum pump.

[0010] Preferably, the outer wall of the scraper evaporator is provided with a heat medium jacket for providing heat, and the inner wall is provided with a scraper. At the same time, the interior of the scraper evaporator is provided with a stirring shaft that can be driven to rotate. The stirring shaft is connected to the scraper link to enable the scraper to rotate along the inner wall of the scraper evaporator.

[0011] Preferably, a stirring frame is provided between the stirring shaft and the scraper, and a movable hinge is provided on the stirring frame.

[0012] Preferably, heat medium is introduced into the heat medium jacket to provide heat to the interior of the scraper evaporator through the heat medium; the liquid lithium hexafluorophosphate raw material liquid inside the scraper evaporator is subjected to the centrifugal force of the rotating scraper, causing part of the liquid to vaporize.

[0013] Preferably, the temperature of the heat medium in the heat medium jacket is in the range of 20-90°C, preferably 30-60°C.

[0014] Preferably, the rotation speed range of the stirring shaft is 30-200 rpm, preferably 50-100 rpm; and / or the feed operating flow rate of the liquid lithium hexafluorophosphate raw material to the scraper evaporator is 1.8-2.2 kg / h, preferably 1.9-2.1 kg / h; and / or the operating pressure range of the scraper evaporator is set at -0.8 to 0.1 MPaG, preferably -0.092 to -0.099 MPaG.

[0015] Preferably, a metering pump and a first mass flow meter are installed on the delivery pipeline of the liquid lithium hexafluorophosphate raw material liquid; a second mass flow meter is installed on the delivery pipeline between the unvaporized liquid and the degassed concentration collection tank; the output end of the degassed concentration collection tank is connected to a delivery pump, and the liquid is delivered to the deacidification section through the delivery pump.

[0016] Preferably, a demister and a third mass flow meter are respectively installed on the conveying pipeline between the vaporized material and the condenser.

[0017] Preferably, the vaporized material enters the heat exchange tube of the condenser, and is cooled by a refrigerant located outside the heat exchange tube to form liquid carbonate and hydrogen chloride gas, which enter the interior of the solvent collection tank together; wherein the liquid carbonate is delivered to the solvent refining section by a delivery pump; and the hydrogen chloride gas is delivered to the tail gas treatment section by the vacuum pump.

[0018] Preferably, a method for degassing liquid lithium hexafluorophosphate adopts the above-mentioned degassing device for liquid lithium hexafluorophosphate; the liquid lithium hexafluorophosphate raw material is heated and subjected to the centrifugal force of rotation in the scraper evaporator (E201), so that part of the liquid is vaporized; the vaporized material is conveyed to the condenser (E202), and the unvaporized liquid is conveyed to the degassing concentration collection tank (V301); the degassed liquid lithium hexafluorophosphate is output from the degassed concentration collection tank (V301), and the hydrogen chloride content in the degassed liquid lithium hexafluorophosphate is less than 10 ppm as determined by ion chromatography.

[0019] The present invention provides a dedicated degassing device for liquid lithium hexafluorophosphate raw material liquid, and in particular, degassing the liquid lithium hexafluorophosphate raw material liquid through a scraper evaporator. During operation, the liquid lithium hexafluorophosphate raw material is heated and subjected to the centrifugal force of rotation by the scraper evaporator, causing a portion of the liquid (i.e., the liquid carbonate and dissolved hydrogen chloride in the liquid lithium hexafluorophosphate raw material liquid) to be vaporized, thereby achieving an efficient and excellent degassing effect. Ultimately, it is ensured that the hydrogen chloride content of the liquid lithium hexafluorophosphate after the degassing treatment of the present invention is less than 10 ppm, thereby reliably ensuring its performance when used as an electrolyte in lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a schematic structural diagram of a degassing device for liquid lithium hexafluorophosphate according to a specific embodiment of the present invention;

[0021] FIG2 is a schematic structural diagram of a scraper evaporator E201 according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0022] 1 and 2 , this embodiment provides a degassing device for liquid lithium hexafluorophosphate, comprising a scraper evaporator E201, a post-degassed concentration collection tank V301, a condenser E202, a solvent collection tank V303, and a vacuum pump P103. The scraper evaporator E201 is connected to a delivery pipeline for a liquid lithium hexafluorophosphate raw material. Under the action of heating and rotating centrifugal force of the scraper evaporator E201, part of the liquid of the liquid lithium hexafluorophosphate raw material is vaporized, and the vaporized material is transported to the condenser E202, while the unvaporized liquid is transported to the post-degassed concentration collection tank V301. The output end of the condenser E202 is connected to the solvent collection tank V303, and the gas phase output end of the solvent collection tank V303 is connected to the vacuum pump P103.

[0023] Preferably, in this embodiment, the outer wall E21a of the scraper evaporator E201 is provided with a heat medium jacket 22 for providing heat, and its inner wall is provided with a scraper 23. At the same time, the interior of the scraper evaporator E201 is provided with a stirring shaft 24 that can be driven to rotate (driven to rotate by a stirring motor M), and the stirring shaft 24 is linked to the scraper 23 to enable the scraper 23 to rotate along the inner wall E21b of the scraper evaporator E201; further preferably, in order to facilitate installation, in this embodiment, a stirring frame 25 is provided between the stirring shaft 24 and the scraper 23, and a movable hinge 26 is provided on the stirring frame 25.

[0024] Preferably, in this embodiment, heat medium is introduced into the heat medium jacket 22, and heat is provided to the interior of the scraper evaporator through the heat medium; the liquid lithium hexafluorophosphate raw material liquid located inside the scraper evaporator E201 is subjected to the centrifugal force of the scraper in a rotating state, so that part of the liquid is vaporized; further preferably, in this embodiment, the temperature range of the heat medium in the heat medium jacket 22 is 20-90°C, preferably 30-60°C; the rotation speed range of the stirring shaft 24 is 30-200rpm, preferably 50-100rpm; and / or preferably, in this embodiment, the feed operating flow rate of the liquid lithium hexafluorophosphate raw material liquid to the scraper evaporator E201 is 1.8-2.2kg / h, preferably 1.9-2.1kg / h; and / or preferably, in this embodiment, the operating pressure range of the scraper evaporator E201 is set at -0.8 to 0.1MpaG, preferably -0.092 to -0.099MpaG; Note: MpaG involved in this application refers to gauge pressure.

[0025] Preferably, in this embodiment, a metering pump P100 and a first mass flow meter M401 are installed in sequence on the delivery pipelines S501, S502, and S503 of the liquid lithium hexafluorophosphate raw material liquid; a second mass flow meter M402 is installed on the delivery pipeline S504 between the unvaporized liquid and the degassed concentration collection tank V301; the output end of the degassed concentration collection tank V301 is connected to the delivery pump P101 through the delivery pipeline S505, and is delivered to the deacidification section through the delivery pump P101 and the delivery pipeline S506.

[0026] Preferably, in order to further ensure the degassing efficiency, in this embodiment, a demister V302 and a third mass flowmeter M403 are respectively installed on the conveying pipelines S507 and S508 between the vaporized material and the condenser E202; the vaporized material enters the heat exchange tube of the condenser E202, and is cooled by the refrigerant located outside the heat exchange tube to form liquid carbonate and hydrogen chloride gas, which enter the interior of the solvent collection tank V303 together; wherein, the liquid carbonate is delivered to the solvent refining section through the conveying pipeline S510, the conveying pump P102 and the conveying pipeline S511; the hydrogen chloride gas is delivered to the exhaust gas treatment section through the conveying pipeline S512, the vacuum pump P103 and the conveying pipeline S513.

[0027] Preferably, this embodiment further provides a method for degassing liquid lithium hexafluorophosphate, using the above-mentioned degassing device for liquid lithium hexafluorophosphate to implement degassing; the liquid lithium hexafluorophosphate raw material is heated and subjected to the centrifugal force of rotation in the scraper evaporator E201, so that part of the liquid is vaporized; the vaporized material is conveyed to the condenser E202, and the unvaporized liquid is conveyed to the degassed concentration collection tank V301; the degassed concentration collection tank V301 outputs the degassed liquid lithium hexafluorophosphate, and ion chromatography detection shows that the hydrogen chloride content in the degassed liquid lithium hexafluorophosphate is less than 10 ppm.

[0028] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0029] Based on the above-described implementation scheme, this application further proposes the following specific examples 1 and 2: Example

[0030] The synthesized liquid lithium hexafluorophosphate raw material liquid was subjected to ion chromatography detection, and after conversion, it was found that the lithium hexafluorophosphate content in the liquid lithium hexafluorophosphate raw material liquid was 28.5%, the hydrogen chloride content was 4.5%, and the hydrogen fluoride content was 0.08%; and gas chromatography detection was performed to determine that the ethyl methyl carbonate content in the liquid lithium hexafluorophosphate raw material liquid was 99.92%.

[0031] In this embodiment 1, the above-mentioned liquid lithium hexafluorophosphate raw material solution is subjected to the following degassing operation using the degassing device provided in this embodiment:

[0032] The heat medium enters the heat medium jacket 22 of the scraper evaporator E201 through the regulating valve FV601 and its pipeline. The first thermometer T801 displays the jacket temperature, which is specifically 52°C. The second thermometer T802 displays the jacket temperature, which is specifically 48°C.

[0033] Step 2: Start the vacuum pump P103 to evacuate the system. The pressure gauge P701 of the scraper evaporator E201 shows that the operating pressure of the scraper evaporator E201 is -0.098MpaG;

[0034] Step 3: Start the stirring motor M of the scraper evaporator E201 and adjust the speed of the stirring shaft 24 to 85 rpm;

[0035] Step 4: Introduce refrigerant into the refrigerant side of condenser E202. The incoming refrigerant temperature is -15°C.

[0036] Step 5: The feed flow rate of the liquid lithium hexafluorophosphate raw material is adjusted by the metering pump P100 and the first mass flowmeter M401, and the feed operating flow rate is set to 2 kg / h. After the liquid lithium hexafluorophosphate raw material enters the scraper evaporator E201, the liquid is evenly scraped by the scraper 23 to form a film on the inner wall E21b of the scraper evaporator E201. The film exchanges heat with the heat medium located in the heat medium jacket 22 to obtain heat. The hydrogen chloride and ethyl methyl carbonate in the liquid are rapidly vaporized and escape from the liquid. The liquid rises through the conveying pipeline S507 and enters the demister V302. The function of the demister V302 is to capture liquid droplets in the gas and cause them to coalesce so as to prevent them from entering the gas phase pipeline, thereby reducing the entrainment of solute lithium hexafluorophosphate.

[0037] Step 6: Adjust the gas flow rate by interlocking the automatic control valve FV601 with the third mass flow meter M403. The third mass flow meter M403 displays a mass flow rate of 0.16 kg / h (i.e., the mass flow rate of vaporized material). At the same time, the liquid product flow rate (i.e., the mass flow rate of unvaporized material) is displayed on the second mass flow meter M402 as 1.84 kg / h. The degassed liquid lithium hexafluorophosphate enters the post-degassing concentration collection tank V301 through the conveying pipeline S504 and the second mass flow meter M402, and is then delivered to the deacidification section through the conveying pump P101.

[0038] Ion chromatography analysis of the degassed liquid lithium hexafluorophosphate (i.e., degassed liquid lithium hexafluorophosphate) revealed that the degassed liquid lithium hexafluorophosphate obtained in this embodiment had a lithium hexafluorophosphate content of 30.97%, a hydrogen fluoride content of 0.06%, and a hydrogen chloride content of 0.0008% (less than 10 ppm).

[0039] The gaseous product (that is, the vaporized material) of the scraper evaporator E201 is cooled by the condenser E202 (which is equipped with a third thermometer T803 and a fourth thermometer T804). The fourth thermometer T804 shows 2.5°C. The non-condensable hydrogen chloride gas is sent to the tail gas treatment section through the outlet of the vacuum pump P103; ethyl methyl carbonate is collected in the solvent collection tank V303 and sent to the solvent refining section through the transfer pump P102 for refining and reuse. Example

[0040] The synthesized liquid lithium hexafluorophosphate raw material liquid was subjected to ion chromatography detection, and after conversion, it was found that the lithium hexafluorophosphate content in the liquid lithium hexafluorophosphate raw material liquid was 28.8%, the hydrogen chloride content was 4.3%, and the hydrogen fluoride content was 0.078%; and gas chromatography detection was performed to determine that the ethyl methyl carbonate content in the liquid lithium hexafluorophosphate raw material liquid was 99.91%.

[0041] In Example 2, the above-mentioned liquid lithium hexafluorophosphate raw material solution is subjected to the following degassing operation using the degassing device provided in this example:

[0042] The heat medium enters the heat medium jacket 22 of the scraper evaporator E201 through the regulating valve FV601 and its pipeline. The first thermometer T801 displays the jacket temperature, which is specifically 51°C. The second thermometer T802 displays the jacket temperature, which is specifically 46°C.

[0043] Step 2: Start the vacuum pump P103 to evacuate the system. The pressure gauge P701 of the scraper evaporator E201 shows that the operating pressure of the scraper evaporator E201 is -0.094MpaG;

[0044] Step 3: Start the stirring motor M of the scraper evaporator E201 and adjust the speed of the stirring shaft 24 to 90 rpm;

[0045] Step 4: Introduce refrigerant into the refrigerant side of condenser E202. The refrigerant feed temperature is 5°C.

[0046] Step 5: The feed flow rate of the liquid lithium hexafluorophosphate raw material is adjusted by the metering pump P100 and the first mass flowmeter M401, and the feed operating flow rate is set to 2.2 kg / h. After the liquid lithium hexafluorophosphate raw material enters the scraper evaporator E201, the liquid is evenly scraped by the scraper 23 to form a film on the inner wall E21b of the scraper evaporator E201. The film exchanges heat with the heat medium located in the heat medium jacket 22 to obtain heat. The hydrogen chloride and ethyl methyl carbonate in the liquid are rapidly vaporized and escape from the liquid. The liquid rises through the conveying pipeline S507 and enters the demister V302. The function of the demister V302 is to capture liquid droplets in the gas and cause them to coalesce so as to prevent them from entering the gas phase pipeline, thereby reducing the entrainment of solute lithium hexafluorophosphate.

[0047] Step 6: Adjust the gas flow rate by interlocking the automatic control valve FV601 with the third mass flow meter M403. The third mass flow meter M403 displays a mass flow rate of 0.17 kg / h (i.e., the mass flow rate of vaporized material). At the same time, the liquid product flow rate (i.e., the mass flow rate of unvaporized material) is displayed on the second mass flow meter M402 as 1.85 kg / h. The degassed liquid lithium hexafluorophosphate enters the post-degassing concentration collection tank V301 through the conveying pipeline S504 and the second mass flow meter M402, and is then delivered to the deacidification section through the conveying pump P101.

[0048] Ion chromatography analysis of the degassed liquid lithium hexafluorophosphate (i.e., degassed liquid lithium hexafluorophosphate) revealed that the degassed liquid lithium hexafluorophosphate obtained in this embodiment had a lithium hexafluorophosphate content of 30.97%, a hydrogen fluoride content of 0.054%, and a hydrogen chloride content of 0.0006% (less than 10 ppm).

[0049] The gaseous product (that is, the vaporized material) of the scraper evaporator E201 is cooled by the condenser E202 (which is equipped with a third thermometer T803 and a fourth thermometer T804). The fourth thermometer T804 shows 2.5°C. The non-condensable hydrogen chloride gas is sent to the tail gas treatment section through the outlet of the vacuum pump P103; ethyl methyl carbonate is collected in the solvent collection tank V303 and sent to the solvent refining section through the transfer pump P102 for refining and reuse.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0051] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A degassing device for liquid lithium hexafluorophosphate, characterized in that: It includes a scraper evaporator (E201), a degassing concentrated collection tank (V301), a condenser (E202), a solvent collection tank (V303) and a vacuum pump (P103), among which: The scraper evaporator (E201) is connected to a conveying pipeline of liquid lithium hexafluorophosphate raw material liquid. Under the heating and rotating centrifugal force of the scraper evaporator (E201), part of the liquid of the liquid lithium hexafluorophosphate raw material is vaporized, and the vaporized material is conveyed to the condenser (E202), and the unvaporized liquid is conveyed to the degassing concentrated collection tank (V301); The output end of the condenser (E202) is connected to the solvent collecting tank (V303), and the gas phase output end of the solvent collecting tank (V303) is connected to the vacuum pump (P103).

2. The degassing device for liquid lithium hexafluorophosphate according to claim 1, characterized in that: The outer wall (E21a) of the scraper evaporator (E201) is provided with a heat medium jacket (22) for providing heat, and the inner wall thereof is provided with a scraper (23). At the same time, a stirring shaft (24) that can be driven to rotate is provided inside the scraper evaporator (E201), and the stirring shaft (24) is linked to the scraper (23) to enable the scraper (23) to rotate along the inner wall (E21b) of the scraper evaporator (E201).

3. The degassing device for liquid lithium hexafluorophosphate according to claim 2, characterized in that: A stirring frame (25) is provided between the stirring shaft (24) and the scraper (23), and a movable hinge (26) is provided on the stirring frame (25).

4. The degassing device for liquid lithium hexafluorophosphate according to claim 2, characterized in that: A heat medium is introduced into the heat medium jacket (22), and heat is provided to the interior of the scraper evaporator through the heat medium; the liquid lithium hexafluorophosphate raw material liquid in the scraper evaporator (E201) is partially vaporized by the centrifugal force of the rotating scraper.

5. The degassing device for liquid lithium hexafluorophosphate according to claim 2, characterized in that: The temperature of the heat medium in the heat medium jacket (22) is in the range of 20-90°C, preferably 30-60°C.

6. The degassing device for liquid lithium hexafluorophosphate according to claim 2, characterized in that: The rotation speed range of the stirring shaft (24) is 30-200 rpm, preferably 50-100 rpm; and / or the feed operating flow rate of the liquid lithium hexafluorophosphate raw material to the scraper evaporator (E201) is 1.8-2.2 kg / h, preferably 1.9-2.1 kg / h; and / or the operating pressure range of the scraper evaporator (E201) is set to -0.8 to 0.1 MPaG, preferably -0.092 to -0.099 MPaG.

7. The degassing device for liquid lithium hexafluorophosphate according to claim 1, characterized in that: A metering pump (P100) and a first mass flow meter (M401) are installed on the delivery pipeline of the liquid lithium hexafluorophosphate raw material liquid; a second mass flow meter (M402) is installed on the delivery pipeline between the unvaporized liquid and the degassed concentrated collection tank (V301); the output end of the degassed concentrated collection tank (V301) is connected to a delivery pump (P101), and is delivered to the deacidification section through the delivery pump (P101).

8. The degassing device for liquid lithium hexafluorophosphate according to claim 1, characterized in that: A demister (V302) and a third mass flow meter (M403) are respectively installed on the conveying pipeline between the vaporized material and the condenser (E202).

9. The degassing device for liquid lithium hexafluorophosphate according to claim 1, characterized in that: The vaporized material enters the heat exchange tube of the condenser (E202), and is cooled by the refrigerant outside the heat exchange tube to form liquid carbonate and hydrogen chloride gas, which enter the interior of the solvent collection tank (V303) together; wherein the liquid carbonate is delivered to the solvent refining section through the delivery pump (P102); and the hydrogen chloride gas is delivered to the tail gas treatment section through the vacuum pump (P103).

10. A method for degassing liquid lithium hexafluorophosphate, characterized in that: A degassing device for liquid lithium hexafluorophosphate as claimed in any one of claims 1 to 9 is used; the liquid lithium hexafluorophosphate raw material is heated and subjected to the rotating centrifugal force of the scraper evaporator (E201), so that part of the liquid is vaporized; the vaporized material is transported to the condenser (E202), and the unvaporized liquid is transported to the degassing concentration collection tank (V301); the degassing concentration collection tank (V301) outputs degassed liquid lithium hexafluorophosphate, and according to ion chromatography, the hydrogen chloride content in the degassed liquid lithium hexafluorophosphate is less than 10 ppm.

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