Device and method for recycling fluorine-containing lithium salt from waste lithium ion battery electrolyte

Abstract

The invention relates to a device and a method for recovering fluorine-containing lithium salt from waste lithium ion battery electrolyte, two waste liquid chambers are respectively arranged on two sides of a purified liquid chamber, and flow channel groups are arranged in the two waste liquid chambers; a negative electrode capable of reversibly intercalating and deintercalating lithium ions is arranged on one side in the purified liquid chamber, a graphite positive electrode capable of reversibly intercalating and deintercalating fluorine-containing acid radical anions is arranged on the other side in the purified liquid chamber, the negative electrode and the graphite positive electrode respectively cover the flow channel group in the waste liquid chamber on the corresponding side, and the flow channel group is provided with a waste liquid inlet flow channel and a waste liquid outlet flow channel; the purified liquid chamber is provided with a purified liquid inlet and a purified liquid outlet, and the negative electrode and the graphite positive electrode are respectively connected with the power supply device through lines. The method can be operated at normal temperature and normal pressure, the fluorine-containing lithium salt can be continuously recycled from the electrolyte of the waste lithium ion battery, tedious and time-consuming separation and purification operations such as crystallization and rectification are omitted, and the recycled fluorine-containing lithium salt is high in purity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of waste battery treatment, in particular to a device and method for recovering and purifying fluorine-containing lithium salt from waste lithium ion battery electrolyte. BACKGROUND

[0002] With the rapid development of electric vehicle industry in recent years, the total amount of waste lithium ion batteries has increased rapidly. If the chemical composition of waste lithium ion batteries is not recycled and utilized, it will cause great resource waste and environmental pollution. Lithium ion batteries are mainly composed of positive electrode, negative electrode, separator and electrolyte. In addition to organic solvents such as carbonate in waste lithium ion battery electrolyte, there are fluorine-containing lithium salts such as lithium hexafluorophosphate, lithium bisfluorosulfonylimide and lithium bis-trifluoromethylsulfonylimide. These lithium salts belong to fluorine chemical industry, which has strict environmental approval and long diffusion period. Therefore, it is of great significance to recover fluorine-containing lithium salt in waste lithium ion battery electrolyte.

[0003] Taking the most common lithium hexafluorophosphate as an example, the current recovery methods include the following: (1) acetonitrile assisted method. Acetonitrile is used to leach and soak the electrolyte of the broken battery, and then Li(CH3CN)4PF6 complex is obtained by freezing crystallization, and then lithium hexafluorophosphate is obtained by vacuum pyrolysis. However, this method is difficult to completely remove acetonitrile, so the purity of the obtained lithium hexafluorophosphate is not high. (2) HF (hydrofluoric acid) treatment method. The solvent in the electrolyte is recovered by distillation, and HF solution is added to recover lithium hexafluorophosphate. However, this method will decompose lithium hexafluorophosphate during distillation, so the recovery rate of lithium hexafluorophosphate is low. In addition, due to the introduction of a large amount of HF, it will cause serious environmental pollution. Therefore, it is urgent to develop a lithium hexafluorophosphate recovery equipment and process with high product purity, high efficiency and environmental friendliness. SUMMARY

[0004] The present application aims to provide a device and method for recovering and purifying fluorine-containing lithium salt from waste lithium ion battery electrolyte, which can be operated at normal temperature and pressure and can continuously recover or purify lithium salt from waste lithium ion battery electrolyte, eliminating the tedious and time-consuming separation and purification operations such as crystallization and distillation, and the recovered fluorine-containing lithium salt has high purity.

[0005] An apparatus for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte includes a waste liquid chamber, a purified liquid chamber, a negative electrode, a graphite positive electrode, and a power supply device. Two waste liquid chambers are located on opposite sides of the purified liquid chamber, and each chamber contains a flow channel assembly. One side of the purified liquid chamber contains a reversible lithium-ion intercalation / deintercalation negative electrode, and the other side contains a reversible fluorinated anion intercalation / deintercalation graphite positive electrode. The negative electrode and the graphite positive electrode respectively cover the flow channel assembly in the corresponding waste liquid chamber. The flow channel assembly includes a waste liquid inlet channel and a waste liquid outlet channel. The purified liquid chamber has a purified liquid inlet and a purified liquid outlet. The negative electrode and the graphite positive electrode are connected to the power supply device via circuits.

[0006] The flow channel assembly in the waste liquid chamber includes a main flow channel and branch flow channels. One end of the main flow channel is connected to the waste liquid inlet flow channel and the other end is connected to the waste liquid outlet flow channel. Multiple branch flow channels are provided inside the main flow channel, and the negative electrode and the graphite positive electrode are respectively in contact with the end of the corresponding side branch flow channel.

[0007] The waste liquid inlet channel is connected to the waste liquid tank via a waste liquid pipeline, and a waste liquid circulation pump is installed on the waste liquid pipeline.

[0008] The waste liquid chamber is provided with a terminal block, and the lines connecting the negative electrode and the graphite positive electrode to the power supply device pass through the terminal block on the corresponding side of the waste liquid chamber.

[0009] The purification chamber forms an inner cavity, with the negative electrode located on one side of the inner cavity and the graphite positive electrode located on the other side of the inner cavity. The purification inlet and the purification outlet are both connected to the inner cavity.

[0010] The purification solution inlet is connected to the purification solution tank via a purification solution pipeline, and a purification solution circulation pump is installed on the purification solution pipeline.

[0011] The power supply device is an electrochemical workstation, and the cutoff voltage for constant current charging of the electrochemical workstation is 3.5 to 5.0V, and the cutoff voltage for constant current discharging is 1.0 to 3.0V; the rate of constant current charging and discharging is 0.5 to 5.0C; and the number of constant current charging and discharging cycles is 100 to 10,000.

[0012] The negative electrode material is lithium titanate or graphite, and the thickness of the negative electrode is 1 to 10 mm; the active material of the graphite positive electrode includes any one or a combination of two of the following: natural graphite, expanded graphite, highly oriented pyrolytic graphite, graphitized mesophase carbon microspheres, artificial graphite, and graphitized carbon fiber, and the thickness of the graphite positive electrode is 1 to 10 mm.

[0013] The purification liquid in the purification liquid chamber is a fluorine-containing lithium salt solution, which is one of lithium hexafluorophosphate, lithium bisfluorosulfonylimide and lithium bis-trifluoromethylsulfonylimide dilute solution, the concentration is 0.01M, and the solvent is carbonic acid ester or sulfonyl organic solvent.

[0014] A recovery method according to the device for recovering fluorine-containing lithium salt from waste lithium ion battery electrolyte, specifically: the power supply device charges and discharges the negative electrode and the graphite positive electrode with constant current, wherein when charging with constant current, lithium ions in the waste lithium ion battery electrolyte occur intercalation reaction in the negative electrode which can reversibly intercalate and deintercalate lithium ions, and fluorine-containing anions in the waste lithium ion battery electrolyte occur intercalation reaction in the graphite positive electrode which can reversibly intercalate and deintercalate fluorine-containing anions, thereby realizing separation of fluorine-containing lithium salt from the waste lithium ion battery electrolyte, and when discharging, the stored lithium ions in the negative electrode and the stored fluorine-containing anions in the graphite positive electrode are released into the intermediate purification liquid chamber and recombine to form fluorine-containing lithium salt.

[0015] The advantages and positive effects of the present application are:

[0016] 1. The present application can be operated at normal temperature and pressure without the need for additional use of corrosive or highly polluting additives, realizing green and sustainable recovery of fluorine-containing lithium salt from waste lithium ion battery electrolyte.

[0017] 2. The waste liquid chamber and the purification liquid chamber of the present application are completely isolated, and the graphite positive electrode used in the present application only allows fluorine-containing anions to intercalate during charging, thereby avoiding the introduction of other impurity anions (such as carbonate, fluoride, etc.) in the waste lithium ion battery electrolyte into the purification chamber, ensuring the high purity of the recovered fluorine-containing lithium salt.

[0018] 3. The waste liquid chamber and the purification liquid chamber of the present application can be arranged in the same reactor, and the recovery and purification of fluorine-containing lithium salt from waste lithium ion battery electrolyte can be realized only by automatic switching of high and low voltage of the external circuit, saving the complicated and time-consuming separation and purification operations such as crystallization and rectification, and significantly reducing the electrolyte recovery cost.

[0019] 4. The materials (including negative electrode, graphite positive electrode and separator material) used to construct the electrolyte recovery device of the present application can all use commercialized materials, which have practical application prospect and popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of the present application,

[0021] Figure 2 is Figure 1 is a combined state sectional view of the waste liquid chamber, negative electrode, graphite positive electrode and purification liquid chamber.

[0022] Wherein, 1 is the waste liquid chamber, 101 is the waste liquid inlet channel, 102 is the waste liquid outlet channel, 103 is the branch channel, 104 is the main channel, 105 is the terminal block, 2 is the purified liquid tank, 3 is the negative electrode, 4 is the graphite positive electrode, 5 is the purified liquid chamber, 501 is the purified liquid inlet, 502 is the purified liquid outlet, 503 is the inner cavity, 6 is the waste liquid tank, and 7 is the power supply device. Detailed Implementation

[0023] The invention will now be described in further detail with reference to the accompanying drawings.

[0024] like Figures 1-2 As shown, the present invention includes a waste liquid chamber 1, a purified liquid chamber 5, a negative electrode 3, a graphite positive electrode 4, and a power supply device 7. The two waste liquid chambers 1 are respectively located on both sides of the purified liquid chamber 5, and each of the two waste liquid chambers 1 is provided with a flow channel group. The purified liquid chamber 5 has a negative electrode 3 for reversible lithium ion intercalation / deintercalation on one side and a graphite positive electrode 4 for reversible fluoride anion intercalation / deintercalation on the other side. The negative electrode 3 and the graphite positive electrode 4 respectively cover the flow channel group in the corresponding waste liquid chamber 1. One end of the flow channel group is provided with a waste liquid inlet flow channel 101 and the other end is provided with a waste liquid outlet flow channel 102. The purified liquid chamber 5 has a purified liquid inlet 501 at one end and a purified liquid outlet 502 at the other end. The negative electrode 3 and the graphite positive electrode 4 are respectively connected to the power supply device 7 through lines.

[0025] like Figures 1-2 As shown, the flow channel assembly within the waste liquid chamber 1 includes a main flow channel 104 and branch flow channels 103. One end of the main flow channel 104 is connected to the waste liquid inlet flow channel 101, and the other end is connected to the waste liquid outlet flow channel 102. Multiple branch flow channels 103 are provided inside the main flow channel 104, and the end of each branch flow channel 104 contacts the negative electrode 3 or the graphite positive electrode 4. The shape of each flow channel in the flow channel assembly can be designed according to actual needs; for example, the flow channels can be processed into serpentine, I-shaped, etc., but are not limited to these. Additionally, for example... Figure 1 As shown, the waste liquid inlet channel 101 is connected to the waste liquid tank 6 through a waste liquid pipeline, and a waste liquid circulation pump is provided on the waste liquid pipeline to realize the circulation of waste electrolyte.

[0026] like Figure 1As shown in the figure, the waste liquid chamber 1 is provided with a terminal post 105, and the negative electrode 3 and the graphite positive electrode 4 are connected with the power supply device 7 through the terminal post 105 on the corresponding side of the waste liquid chamber 1. The power supply device 7 can be an electrochemical workstation to realize constant current charging and discharging of the negative electrode 3 and the graphite positive electrode 4, which is a known technology in the art. The constant current charging cutoff voltage of the electrochemical workstation is 3.5-5.0V, and the constant current discharging cutoff voltage is 1.0-3.0V. The constant current charging and discharging rate is 0.5-5.0C, and the number of cycles is 100-10000 cycles.

[0027] As shown in the figure, the waste liquid chamber 1 is provided with a terminal post 105, and the negative electrode 3 and the graphite positive electrode 4 are connected with the power supply device 7 through the terminal post 105 on the corresponding side of the waste liquid chamber 1. The power supply device 7 can be an electrochemical workstation to realize constant current charging and discharging of the negative electrode 3 and the graphite positive electrode 4, which is a known technology in the art. The constant current charging cutoff voltage of the electrochemical workstation is 3.5-5.0V, and the constant current discharging cutoff voltage is 1.0-3.0V. The constant current charging and discharging rate is 0.5-5.0C, and the number of cycles is 100-10000 cycles. Figures 1-2 As shown in the figure, the waste liquid chamber 1 is provided with a terminal post 105, and the negative electrode 3 and the graphite positive electrode 4 are connected with the power supply device 7 through the terminal post 105 on the corresponding side of the waste liquid chamber 1. The power supply device 7 can be an electrochemical workstation to realize constant current charging and discharging of the negative electrode 3 and the graphite positive electrode 4, which is a known technology in the art. The constant current charging cutoff voltage of the electrochemical workstation is 3.5-5.0V, and the constant current discharging cutoff voltage is 1.0-3.0V. The constant current charging and discharging rate is 0.5-5.0C, and the number of cycles is 100-10000 cycles. Figure 1 As shown in the figure, the waste liquid chamber 1 is provided with a terminal post 105, and the negative electrode 3 and the graphite positive electrode 4 are connected with the power supply device 7 through the terminal post 105 on the corresponding side of the waste liquid chamber 1. The power supply device 7 can be an electrochemical workstation to realize constant current charging and discharging of the negative electrode 3 and the graphite positive electrode 4, which is a known technology in the art. The constant current charging cutoff voltage of the electrochemical workstation is 3.5-5.0V, and the constant current discharging cutoff voltage is 1.0-3.0V. The constant current charging and discharging rate is 0.5-5.0C, and the number of cycles is 100-10000 cycles.

[0028] The waste liquid chamber 1 is made of a conductive material with high mechanical strength, such as stainless steel plate, titanium plate, high-purity graphite plate, etc., but is not limited thereto. The purification liquid chamber 5 is made of an insulating material with high mechanical strength and corrosion resistance, such as one of acrylic, polytetrafluoroethylene, stainless steel, and polyether ether ketone, but is not limited thereto. Preferably, the purification liquid chamber 5 is made of polyether ether ketone material.

[0029] The negative electrode 3 capable of reversible intercalation and deintercalation of lithium ions is a material capable of electrochemical lithium ion intercalation and having a certain mechanical strength, such as lithium titanate and graphite, but is not limited thereto. The thickness of the negative electrode 3 is 1-10mm, and the area is greater than the area of the flow channel group in the corresponding side of the waste liquid chamber 1. The active material of the graphite positive electrode 4 capable of reversible intercalation and deintercalation of fluorine-containing acid root anions includes any one or a combination of two of natural graphite, expanded graphite, highly oriented pyrolytic graphite, mesocarbon microbeads, artificial graphite, and graphitized carbon fiber. The thickness of the graphite positive electrode 4 is 1-10mm, and the area is greater than the area of the flow channel group of the corresponding side of the waste liquid chamber 1 and consistent with the area of the negative electrode 3.

[0030] The waste liquid chamber 1, the purification liquid chamber 5, the negative electrode 3, the graphite positive electrode 4, and related sealing gaskets and other elements are fixed by bolts and nuts.

[0031] The working principle of the present application is as follows:

[0032] In operation, the waste lithium-ion battery electrolyte is injected into the flow channel group in the waste liquid chamber 1 through the waste liquid inlet flow channel 101, and contacts the negative electrode 3 or the graphite positive electrode 4 through the flow channel group, the purified liquid is injected into the purified liquid chamber 5 through the purified liquid inlet 501, and the power supply device 7 charges and discharges the negative electrode 3 and the graphite positive electrode 4 with constant current, wherein during constant current charging, lithium ions and fluoride-containing anions in the waste lithium-ion battery electrolyte respectively undergo intercalation reaction in the negative electrode 3 and the graphite positive electrode 4, and then realize separation of the fluoride-containing lithium salt from the waste lithium-ion battery electrolyte, and then during the discharging process, the lithium ions stored in the negative electrode 3 and the fluoride-containing anions stored in the graphite positive electrode 4 are released into the intermediate purified liquid chamber 5 and recombine to form fluoride-containing lithium salt, thereby realizing the separation and purification process of the fluoride-containing lithium salt in the waste lithium-ion battery electrolyte, and therefore, as the charging and discharging cycle continues, the concentration of the fluoride-containing lithium salt in the purified liquid chamber 5 continues to increase, and in addition, since the purified liquid chamber 5 is separated from the waste liquid chamber 1, the impurity components in the waste liquid chamber 1 cannot enter the purified liquid chamber 5, and the single selective intercalation characteristics of the graphite positive electrode 4 for fluoride-containing anions can also avoid the introduction of other impurity anions (such as carbonate, fluoride, etc.) in the waste lithium-ion battery electrolyte into the purified liquid chamber 5, thereby realizing the recovery of high-purity fluoride-containing lithium salt.

[0033] The fluoride-containing lithium salt in the waste lithium-ion battery electrolyte is one of lithium hexafluorophosphate, lithium bisfluorosulfonylimide, and lithium bis-trifluoromethylsulfonylimide, and the concentration is 1.0M-5.0M, the purified liquid is a dilute solution of fluoride-containing lithium salt, the concentration of fluoride-containing lithium salt is 0.01M, and the solvent is carbonic acid ester and sulfone organic solvent, such as methyl ethyl carbonate, dimethyl carbonate, and cyclobutane sulfone, but is not limited thereto.

[0034] Taking the graphite negative electrode 3, the graphite positive electrode 4, and the lithium hexafluorophosphate electrochemical cell as an example, the electrode reaction during the charging and discharging process of the present application is described as follows:

[0035] The intercalation reaction of lithium hexafluorophosphate during charging is: 正极 +C 负极 +xLi + +xPF6 - →Li x C 正极 +(PF6) x C 负极 ;

[0036] The release reaction of lithium hexafluorophosphate during discharging is: x C 正极 +(PF6) x C 负极 →C 正极 +C负极 +xLi + +xPF6 - .

[0037] The following examples are provided to further illustrate the present application.

[0038] Example 1

[0039] In this embodiment, the negative electrode 3 is made of lithium titanate. The preparation process is as follows: a self-supporting lithium titanate electrode film is prepared by using a dry electrode process. The mass ratio of lithium titanate, acetylene black conductive agent and PTFE binder in the mixture is 90%, 5% and 5% respectively. Then the film is cut into a square electrode sheet with a thickness of 1 mm and an area of 1.5 x 1.5 cm 2 The graphite positive electrode 4 is made of graphite. The preparation process is as follows: a self-supporting graphite electrode film is prepared by using a dry electrode process. The mass ratio of commercial graphite, acetylene black conductive agent and PTFE binder in the mixture is 90%, 5% and 5% respectively. Then the film is cut into a square electrode sheet with a thickness of 1 mm and an area of 1.5 x 1.5 cm 2

[0040] In this embodiment, the waste liquid chamber 1 is filled with waste electrolyte with a lithium hexafluorophosphate concentration of 1.0 M. The purified liquid chamber 5 is filled with methyl ethyl carbonate solution with a lithium hexafluorophosphate concentration of 0.01 M. A sealing gasket is provided between the waste liquid chamber 1 and the purified liquid chamber 5 to ensure sealing.

[0041] In operation, the waste liquid circulating pump is turned on to connect the waste liquid chamber 1 and the waste liquid tank 6, and the waste liquid is introduced into the waste liquid chamber 1. The purified liquid circulating pump is turned on to connect the purified chamber 5 and the purified tank 2. The power supply device 7 is connected to the terminal post 105, and the power switch is turned on. The constant current charging and discharging program is set. In this embodiment, the cut-off voltage of the constant current charging is 3.5 V, the cut-off voltage of the constant current discharging is 1.2 V, the rate of the constant current charging and discharging is 1 C, and the constant current charging and discharging is 1000 cycles. After the setting is completed, the charging and discharging program is executed. After the reaction is completed, the test results show that the concentration of lithium hexafluorophosphate in the purified liquid chamber 5 reaches 0.1 M.

[0042] Example 2

[0043] The device in this embodiment is obtained in the same way as in Example 1, but the difference between this embodiment and Example 1 is that the thicknesses of the negative electrode 3 and the graphite positive electrode 4 are different. In this embodiment, the thickness of the lithium titanate negative electrode is 10 mm, and the thickness of the graphite positive electrode is also 10 mm.

[0044] Specifically, the self-supporting lithium titanate electrode and the graphite electrode are both pressed into a thickness of 10 mm by adjusting the roller pressure of the roller press, and then cut into a size of 1.5 x 1.5 cm​2 The waste liquid chamber 1 is filled with waste electrolyte with a concentration of 1.0 M LiPF6, and the purified liquid chamber 5 is filled with a solution of 0.01 M LiPF6 in ethyl methyl carbonate. During the operation of this example, the waste liquid circulating pump is turned on to connect the waste liquid chamber 1 with the waste liquid tank 6, and the waste liquid is introduced into the waste liquid chamber 1. The purified liquid circulating pump is turned on to connect the purified chamber 5 with the purified tank 2. The power supply device 7 is connected to the terminal 105, and the power switch is turned on. The constant current charging and discharging program is set. In this example, the cut-off voltage of the constant current charging is 3.5 V, the cut-off voltage of the constant current discharging is 1.2 V, the rate of the constant current charging and discharging is 1 C, and the constant current charging and discharging is 1000 cycles. After the completion of the charging and discharging program, the test results show that the concentration of LiPF6 in the purified liquid chamber 5 reaches 0.8 M.

[0045] Example 3

[0046] The device of this example is obtained in the same manner as in Example 1, but the difference between this example and Example 1 is that the cut-off voltage of the charging applied in this example is different. The cut-off voltage of the charging applied in this example is 5.0 V.

[0047] Specifically, the lithium titanate is pressed into a sheet with a thickness of 1 mm using a roller press, and then cut into a piece with an area of 1.5 x 1.5 cm 2 The graphite powder is pressed into a sheet with a thickness of 1 mm using a roller press, and then cut into a piece with an area of 1.5 x 1.5 cm 2 The waste liquid chamber 1 is filled with waste electrolyte with a concentration of 1.0 M LiPF6, and the purified liquid chamber 5 is filled with a solution of 0.01 M LiPF6 in ethyl methyl carbonate. During the operation of this example, the waste liquid circulating pump is turned on to connect the waste liquid chamber 1 with the waste liquid tank 6, and the waste liquid is introduced into the waste liquid chamber 1. The purified liquid circulating pump is turned on to connect the purified chamber 5 with the purified tank 2. The power supply device 7 is connected to the terminal 105, and the power switch is turned on. The constant current charging and discharging program is set. In this example, the cut-off voltage of the constant current charging is 5 V, the cut-off voltage of the constant current discharging is 1.2 V, the rate of the constant current charging and discharging is 1 C, and the constant current charging and discharging is 1000 cycles. After the completion of the charging and discharging program, the test results show that the concentration of LiPF6 in the purified liquid chamber 5 reaches 0.9 M.

[0048] Example 4

[0049] The device of this example is obtained in the same manner as in Example 1, but the difference between this example and Example 1 is that the cut-off voltage of the discharging applied in this example is different. The cut-off voltage of the discharging applied in this example is 2.5 V.

[0050] Specifically, the lithium titanate is pressed into a sheet with a thickness of 1 mm using a roller press, and then cut into a piece with an area of 1.5 x 1.5 cm 2, the graphite powder was pressed into a sheet with a thickness of 1 mm using a roller press, and then cut into a piece with an area of 1.5 x 1.5 cm 2 The waste liquid chamber 1 was filled with waste electrolyte with a lithium hexafluorophosphate concentration of 1.0 M, and the purified liquid chamber 5 was filled with a methyl ethyl carbonate solution with a lithium hexafluorophosphate concentration of 0.01 M. During operation of this example, the waste liquid circulation pump was turned on to connect the waste liquid chamber 1 and the waste liquid tank 6, the waste liquid was introduced into the waste liquid chamber 1, the purified liquid circulation pump was turned on to connect the purified chamber 5 and the purified tank 2, the power supply device 7 was connected to the terminal 105, and the power switch was turned on. A constant current charge-discharge program was set, the cut-off voltage of the constant current charging was 3.5 V, the cut-off voltage of the constant current discharging was 2.5 V, and the rate of the constant current charge-discharge was 1C. After 1000 cycles of constant current charge-discharge, the detection results showed that the concentration of lithium hexafluorophosphate in the purified chamber reached 0.6 M.

[0051] Example 5

[0052] The device of this example was obtained in the same manner as in Example 1, but the difference between this example and Example 1 is that the number of charge-discharge cycles applied is different. In this example, the number of charge-discharge cycles applied was 10000 cycles.

[0053] Specifically, the lithium titanate was pressed into a sheet with a thickness of 1 mm using a roller press, and then cut into a piece with an area of 1.5 x 1.5 cm 2 , the graphite powder was pressed into a sheet with a thickness of 1 mm using a roller press, and then cut into a piece with an area of 1.5 x 1.5 cm 2 The waste liquid chamber 1 was filled with waste electrolyte with a lithium hexafluorophosphate concentration of 1.0 M, and the purified liquid chamber 5 was filled with a methyl ethyl carbonate solution with a lithium hexafluorophosphate concentration of 0.01 M. During operation of this example, the waste liquid circulation pump was turned on to connect the waste liquid chamber 1 and the waste liquid tank 6, the waste liquid was introduced into the waste liquid chamber 1, the purified liquid circulation pump was turned on to connect the purified chamber 5 and the purified tank 2, the power supply device 7 was connected to the terminal 105, and the power switch was turned on. A constant current charge-discharge program was set, the cut-off voltage of the constant current charging was 3.5 V, the cut-off voltage of the constant current discharging was 1.2 V, and the rate of the constant current charge-discharge was 1C. After 10000 cycles of constant current charge-discharge, the detection results showed that the concentration of lithium hexafluorophosphate in the purified chamber reached 0.95 M.

[0054] Example 6

[0055] The device of this example was obtained in the same manner as in Example 1, but the difference between this example and Example 1 is that the active material of the negative electrode 3 is different. In this example, commercial graphite was used as the active material of the negative electrode.

[0056] Specifically, a self-supporting graphite negative electrode film was prepared by using a dry electrode process, the mass ratio of commercial graphite, acetylene black conductive agent, and PTFE binder in the mixture was 90%, 5%, and 5%, respectively, and then the film was cut into a square electrode sheet with a thickness of 1 mm and an area of 1.5 x 1.5 cm 2 .

[0057] The graphite positive electrode 4, the device composition, and the electrochemical procedure were the same as in Example 1. After the charge and discharge procedure was completed, the test results showed that the concentration of lithium hexafluorophosphate in the purification chamber was 0.55 M.

[0058] Example 7

[0059] The device in this example was obtained in the same way as in Example 1, but the difference between this example and Example 1 is that the graphite-based carbon material of the graphite positive electrode 4 uses graphitized mesocarbon microbeads.

[0060] Specifically, a self-supporting graphite negative electrode film was prepared by using a dry electrode process, the mass ratio of commercial graphite, acetylene black conductive agent, and PTFE binder in the mixture was 90%, 5%, and 5%, respectively, and then the film was cut into a square electrode sheet with a thickness of 1 mm and an area of 1.5 x 1.5 cm 2 .

[0061] The negative electrode 3, the device composition, and the electrochemical procedure were the same as in Example 1. After the charge and discharge procedure was completed, the test results showed that the concentration of lithium hexafluorophosphate in the purification chamber reached 0.45 M.

[0062] Example 8

[0063] The device in this example was obtained in the same way as in Example 1, but the difference between this example and Example 1 is that the concentration of lithium hexafluorophosphate in the used waste lithium ion electrolyte is different, and the concentration of lithium hexafluorophosphate in the waste lithium ion electrolyte used in this example is 5.0 M.

[0064] Specifically, a self-supporting lithium titanate electrode film was prepared by using a dry electrode process, the mass ratio of lithium titanate, acetylene black conductive agent, and PTFE binder in the mixture was 90%, 5%, and 5%, respectively, and then the film was cut into a square electrode sheet with a thickness of 1 mm and an area of 1.5 x 1.5 cm 2 , and a self-supporting graphite electrode film was prepared by using a dry electrode process, the mass ratio of commercial graphite, acetylene black conductive agent, and PTFE binder in the mixture was 90%, 5%, and 5%, respectively, and then the film was cut into a square electrode sheet with a thickness of 1 mm and an area of 1.5 x 1.5 cm 2square electrode sheet with a thickness of 1 mm and an area of 1.5 x 1.5 cm2, the waste liquid chamber 1 is filled with waste electrolyte with a lithium hexafluorophosphate concentration of 1.0 M, and the purification chamber 5 is filled with sulfolane solution with a lithium hexafluorophosphate concentration of 0.01 M. When the device of the present embodiment is in operation, the waste liquid circulating pump is turned on to connect the waste liquid chamber 1 and the waste liquid tank 6, the waste liquid is introduced into the waste liquid chamber 1, the purification liquid circulating pump is turned on to connect the purification chamber 5 and the purification tank 2, the power supply device 7 is connected to the terminal post 105, and the power switch is turned on. A constant current charge-discharge program is set, in the present embodiment, the cut-off voltage of the constant current charging is 3.5 V, the cut-off voltage of the constant current discharging is 1.2 V, the rate of the constant current charge-discharge is 1C, and the constant current charge-discharge is 1000 cycles. After the setting is completed, the charge-discharge program is executed, and after the reaction is completed, the detection result shows that the lithium hexafluorophosphate concentration in the purification chamber 5 reaches 0.1 M.

[0065] Example 9

[0066] The device of the present embodiment is obtained in the same manner as in Example 1, but the difference between the present embodiment and Example 1 is that the type of solvent used in the purification liquid is different. The solvent used in the present embodiment is sulfolane.

[0067] Specifically, a self-supporting lithium titanate electrode film is prepared by a dry electrode process, and the mass ratio of lithium titanate, acetylene black conductive agent, and PTFE binder in the mixture is 90%, 5%, and 5%, respectively. Then, the lithium titanate electrode film is cut into a square electrode sheet with a thickness of 1 mm and an area of 1.5 x 1.5 cm 2 Specifically, a self-supporting graphite electrode film is prepared by a dry electrode process, and the mass ratio of commercial graphite, acetylene black conductive agent, and PTFE binder in the mixture is 90%, 5%, and 5%, respectively. Then, the graphite electrode film is cut into a square electrode sheet with a thickness of 1 mm and an area of 1.5 x 1.5 cm 2 square electrode sheet with a thickness of 1 mm and an area of 1.5 x 1.5 cm2, the waste liquid chamber 1 is filled with waste electrolyte with a lithium hexafluorophosphate concentration of 1.0 M, and the purification chamber 5 is filled with sulfolane solution with a lithium hexafluorophosphate concentration of 0.01 M. When the device of the present embodiment is in operation, the waste liquid circulating pump is turned on to connect the waste liquid chamber 1 and the waste liquid tank 6, the waste liquid is introduced into the waste liquid chamber 1, the purification liquid circulating pump is turned on to connect the purification chamber 5 and the purification tank 2, the power supply device 7 is connected to the terminal post 105, and the power switch is turned on. A constant current charge-discharge program is set, in the present embodiment, the cut-off voltage of the constant current charging is 3.5 V, the cut-off voltage of the constant current discharging is 1.2 V, the rate of the constant current charge-discharge is 1C, and the constant current charge-discharge is 1000 cycles. After the setting is completed, the charge-discharge program is executed, and after the reaction is completed, the detection result shows that the lithium hexafluorophosphate concentration in the purification chamber 5 reaches 0.1 M.

[0068] Example 10

[0069] The device of this example is obtained in the same way as example 1, but the difference between this example and example 1 is that the lithium salt containing fluorine used in this example is lithium bis(trifluoromethanesulfonyl)imide.

[0070] Specifically, lithium titanate is pressed into a sheet with a thickness of 1 mm using a roller press, and then cut into a piece with an area of 1.5 x 1.5 cm 2 Specifically, graphite powder is pressed into a sheet with a thickness of 1 mm using a roller press, and then cut into a piece with an area of 1.5 x 1.5 cm 2 The waste liquid chamber 1 is filled with waste electrolyte with a lithium bis(trifluoromethanesulfonyl)imide concentration of 1.0 M, and the purified liquid chamber 5 is filled with methyl ethyl carbonate solution with a lithium bis(trifluoromethanesulfonyl)imide concentration of 0.01 M. When this example is in operation, the waste liquid circulating pump is turned on to connect the waste liquid chamber 1 and the waste liquid tank 6, the waste liquid is introduced into the waste liquid chamber 1, the purified liquid circulating pump is turned on to connect the purified chamber 5 and the purification tank 2, the power supply device 7 is connected to the terminal post 105, and the power switch is turned on. Set the constant current charge and discharge program, the cut-off voltage of the constant current charge of this example is 3.5 V, the cut-off voltage of the constant current discharge is 1.2 V, the rate of the constant current charge and discharge is 1C, and the constant current charge and discharge is 1000 cycles. After the charge and discharge program is completed, the test results show that the concentration of lithium bis(trifluoromethanesulfonyl)imide in the purified liquid chamber 5 reaches 0.1 M.

[0071] Example 11

[0072] The device of this example is obtained in the same way as example 1, but the difference between this example and example 1 is that the lithium salt containing fluorine used in this example is lithium bis(trifluoromethanesulfonyl)imide.

[0073] Specifically, lithium titanate is pressed into a sheet with a thickness of 1 mm using a roller press, and then cut into a piece with an area of 1.5 x 1.5 cm 2 Specifically, graphite powder is pressed into a sheet with a thickness of 1 mm using a roller press, and then cut into a piece with an area of 1.5 x 1.5 cm 2 The waste liquid chamber 1 is filled with waste electrolyte with a lithium bis(trifluoromethanesulfonyl)imide concentration of 1.0 M, and the purified liquid chamber 5 is filled with methyl ethyl carbonate solution with a lithium bis(trifluoromethanesulfonyl)imide concentration of 0.01 M. When this example is in operation, the waste liquid circulating pump is turned on to connect the waste liquid chamber 1 and the waste liquid tank 6, the waste liquid is introduced into the waste liquid chamber 1, the purified liquid circulating pump is turned on to connect the purified chamber 5 and the purification tank 2, the power supply device 7 is connected to the terminal post 105, and the power switch is turned on. Set the constant current charge and discharge program, the cut-off voltage of the constant current charge of this example is 3.5 V, the cut-off voltage of the constant current discharge is 1.2 V, the rate of the constant current charge and discharge is 1C, and the constant current charge and discharge is 1000 cycles. After the charge and discharge program is completed, the test results show that the concentration of lithium bis(trifluoromethanesulfonyl)imide in the purified liquid chamber 5 reaches 0.1 M.

Claims

1. An apparatus for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte, characterized in that: The device includes a waste liquid chamber (1), a purified liquid chamber (5), a negative electrode (3), a graphite positive electrode (4), and a power supply device (7). The two waste liquid chambers (1) are located on both sides of the purified liquid chamber (5), and each of the two waste liquid chambers (1) is equipped with a flow channel group. The purified liquid chamber (5) is equipped with a negative electrode (3) for reversible lithium ion insertion / extraction on one side and a graphite positive electrode (4) for reversible fluorine-containing anion insertion / extraction on the other side. The negative electrode (3) and the graphite positive electrode (4) cover the flow channel group in the corresponding waste liquid chamber (1). The flow channel group is equipped with a waste liquid inlet flow channel (101) and a waste liquid outlet flow channel (102). The purified liquid chamber (5) is equipped with a purified liquid inlet (501) and a purified liquid outlet (502). The negative electrode (3) and the graphite positive electrode (4) are connected to the power supply device (7) through lines.

2. The apparatus for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte according to claim 1, characterized in that: The flow channel group in the waste liquid chamber (1) includes a main flow channel (104) and branch flow channels (103). One end of the main flow channel (104) is connected to the waste liquid inlet flow channel (101) and the other end is connected to the waste liquid outlet flow channel (102). Multiple branch flow channels (103) are provided inside the main flow channel (104), and the negative electrode (3) and the graphite positive electrode (4) are in contact with the end of the corresponding side branch flow channel (103).

3. The apparatus for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte according to claim 1 or 2, characterized in that: The waste liquid inlet channel (101) is connected to the waste liquid tank (6) through a waste liquid pipeline, and a waste liquid circulation pump is provided on the waste liquid pipeline.

4. The apparatus for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte according to claim 1, characterized in that: The waste liquid chamber (1) is provided with a terminal (105), and the lines connecting the negative electrode (3) and the graphite positive electrode (4) to the power supply device (7) pass through the terminal (105) on the corresponding side of the waste liquid chamber (1).

5. The apparatus for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte according to claim 1, characterized in that: The purification liquid chamber (5) forms an inner cavity (503), and the negative electrode (3) is located on one side of the inner cavity (503), the graphite positive electrode (4) is located on the other side of the inner cavity (503), and the purification liquid inlet (501) and the purification liquid outlet (502) are both connected to the inner cavity (503).

6. The apparatus for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte according to claim 1 or 5, characterized in that: The purification solution inlet (501) is connected to the purification solution tank (2) through a purification solution pipeline, and a purification solution circulation pump is provided on the purification solution pipeline.

7. The apparatus for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte according to claim 1, characterized in that: The power supply device (7) is an electrochemical workstation, and the cutoff voltage for constant current charging of the electrochemical workstation is 3.5 to 5.0V, and the cutoff voltage for constant current discharging is 1.0 to 3.0V; the rate of constant current charging and discharging is 0.5 to 5.0C; and the number of constant current charging and discharging cycles is 100 to 10,000.

8. The apparatus for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte according to claim 1, characterized in that: The negative electrode (3) is made of lithium titanate or graphite, and the thickness of the negative electrode (3) is 1 to 10 mm; the active material of the graphite positive electrode (4) includes any one or a combination of two of the following: natural graphite, expanded graphite, highly oriented pyrolytic graphite, graphitized mesophase carbon microspheres, artificial graphite, and graphitized carbon fiber, and the thickness of the graphite positive electrode (4) is 1 to 10 mm.

9. The apparatus for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte according to claim 1, characterized in that: The purification solution in the purification chamber (5) is a fluorinated lithium salt solution, which is one of lithium hexafluorophosphate, lithium bisfluorosulfonylimide, or lithium bistrifluoromethylsulfonylimide dilute solution, with a concentration of 0.01M, and the solvent is carbonate or sulfone organic solvent.

10. A method for recovering fluorinated lithium salts from waste lithium-ion battery electrolyte according to claim 1, characterized in that: The power supply device (7) charges and discharges the negative electrode (3) and the graphite positive electrode (4) at a constant current. During constant current charging, lithium ions in the electrolyte of the waste lithium-ion battery undergo intercalation reaction in the negative electrode (3) where lithium ions are reversibly intercalated and deintercalated, and fluorine-containing anions in the electrolyte of the waste lithium-ion battery undergo intercalation reaction in the graphite positive electrode (4) where fluorine-containing anions are reversibly intercalated and deintercalated, thereby realizing the separation of fluorine-containing lithium salts from the electrolyte of the waste lithium-ion battery. During discharge, the lithium ions stored in the negative electrode (3) and the fluorine-containing anions stored in the graphite positive electrode (4) are released into the intermediate purification liquid chamber (5) and recombine to form fluorine-containing lithium salts.

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