High-value selection method for negative pole piece of lithium ion battery

Abstract

The invention discloses a high-value fine selection method for a lithium ion battery negative pole piece, which belongs to the field of lithium ion battery recovery and comprises the following steps: firstly, transferring a lithium ion battery negative pole piece material into a shredder for shredding; transferring the mixture into an ultrasonic wet-process powder removing device, and separating the graphite powder from the Cu foil; transferring the Cu foil and graphite powder mixed solution into a centrifugal machine, and removing part of water; transferring the mixed wet material into a drying device for drying; and transferring the dried material into a vortex sorting device to sort out high-purity Cu foil and graphite powder. In the preparation process, ultrasound and vortex are added as core technologies, and the separated and purified Cu foil and graphite powder are high in purity, high in additional value and suitable for industrialization. In the preparation process, ultrasound and vortex are added as core technologies, and the separated and purified Cu foil and graphite powder are high in purity, high in additional value, suitable for industrialization, low in metal loss, high in process additional value and suitable for industrialization.

Description

Technical Field

[0001] The invention relates to the field of lithium ion battery recycling, and in particular to a high-value selection method for negative electrode sheets of lithium ion batteries. Background Art

[0002] With the widespread use of electronic products, the number of waste lithium-ion batteries has increased dramatically. These waste batteries contain a large amount of valuable metals, such as copper, cobalt, lithium, etc. Among them, the negative electrode sheet is usually composed of materials such as copper foil and graphite. Copper foil, as a current collector, has a high recycling value. However, miscellaneous materials such as binders and conductive agents will adhere to the current collector, affecting the metal recovery efficiency. Therefore, it is of great economic and environmental significance to develop an efficient and environmentally friendly recycling method to recover copper from the negative electrode sheets of waste lithium-ion batteries. The negative electrode sheet material of lithium-ion batteries is an important component of lithium-ion batteries, and its high-value separation and utilization have certain economic and social value. The method currently used in the market is the method of using physical equipment to pulverize. The processing process is seriously polluted by dust, and there is a lot of metal loss, and the purity of the negative electrode powder is low.

[0003] Chinese patent CN115632182A discloses a method for separating and recovering negative electrode sheets of lithium-ion batteries, including: adding negative electrode sheets of lithium-ion batteries to water, ultrasonically vibrating until carbon negative electrode materials are peeled off from copper foil current collectors, and obtaining a suspension of copper foil and carbon-containing negative electrode materials; after solid-liquid separation of the suspension of carbon-containing negative electrode materials, heating and baking to obtain carbon negative electrode materials. However, the vibration in the ultrasonic process of this invention patent makes the separation process of copper foil and carbon materials not thorough enough, which has a great impact on the purity of the prepared carbon negative electrode materials. Therefore, a high-value selection method for negative electrode sheets of lithium-ion batteries is needed to improve the separation degree of copper foil and carbon materials. Summary of the invention

[0004] With regard to the above-mentioned problems existing in the prior art, the object of the present invention is to provide a high-value selection method for negative electrode plates of lithium-ion batteries to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A high-value selection method for negative electrode sheets of lithium-ion batteries, the method steps are as follows:

[0007] S1. Put the negative electrode sheet material of the lithium-ion battery into a shredder, and shred the sheet into a mixture of small pieces of the same specification according to certain specifications;

[0008] S2, the shredded mixture in step S1 is put into an ultrasonic wet de-powdering device, a corresponding proportion of water is added as a solvent, and the corresponding ultrasonic power of the ultrasonic transducer in the ultrasonic vibration box is turned on for ultrasonic separation, so as to separate the graphite powder from the Cu foil to form a mixed solution of Cu foil and graphite powder;

[0009] S3, transferring the mixed solution of Cu foil and graphite powder in step S2 into a centrifuge, setting the corresponding speed of the centrifuge to remove part of the water to obtain a mixed wet material of Cu foil and graphite powder;

[0010] S4, transferring the wet mixed material of Cu foil and graphite powder in step S3 into a dryer, setting corresponding temperature and time, and drying to obtain a mixed dry material;

[0011] S5. Transfer the mixed dry material in step S4 into an eddy current separator, set the corresponding magnetic induction intensity, and separate the high-purity Cu foil and graphite powder.

[0012] As a further solution of the present invention: in step S1, the negative electrode plate of the lithium-ion battery is one or more of natural graphite and artificial graphite.

[0013] As a further solution of the present invention: the diameter of the small pieces after being shredded in step S1 is 0.2-2.5 cm.

[0014] As a further solution of the present invention: in the ultrasonic separation process in step S2, the material-liquid ratio of the mixture to water is 1:1-1:5.

[0015] As a further solution of the present invention: the ultrasonic wet de-powdering device in step S3 comprises a rotating drum, a water tank and an ultrasonic vibration box, a water tank is arranged under the rotating drum, the water tank is arranged in a slope, and a plurality of groups of ultrasonic vibration boxes are arranged on the side wall of the water tank.

[0016] As a further solution of the present invention: a plurality of ultrasonic transducers are arranged in the ultrasonic vibration box, and the plurality of ultrasonic transducers are arranged in a matrix.

[0017] As a further solution of the present invention: the ultrasonic frequency of the ultrasonic transducer in the ultrasonic vibration box in step S2 is 20kHz-80kHz.

[0018] As a further solution of the present invention: the rotation speed of the centrifuge in step S3 is 200-1200 rpm.

[0019] As a further solution of the present invention: the drying temperature of the dryer in step S4 is 60-600°C.

[0020] As a further solution of the present invention: the magnetic induction intensity of the eddy current separation device in step S5 is 0.1-0.8T.

[0021] As a further solution of the present invention:

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Ultrasound and eddy current are added as core technologies in the preparation process of the present invention, and the separated and purified Cu foil and graphite powder have high purity, high added value, and are suitable for industrialization. The beneficial effects of the present invention are that the high-value selected metal Cu and graphite powder have high purity, low metal loss, high process added value, and are suitable for industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a process flow chart of a high-value selection method for negative electrode plates of lithium-ion batteries disclosed in an embodiment. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that 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 creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", and "connected" should be understood in a broad sense; for example, it can be a fixed connection, a detachable connection, or an integral connection, a mechanical connection, or an electrical connection, a direct connection, or an indirect connection through an intermediate medium, or the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] See also Figure 1 , a high-value selection method for negative electrode sheets of lithium-ion batteries, the method steps are as follows:

[0028] S1. Put the negative electrode sheet material of the lithium-ion battery into a shredder, and shred the sheet into a mixture of small pieces of the same specification according to certain specifications;

[0029] S2, the shredded mixture in step S1 is put into an ultrasonic wet de-powdering device, a corresponding proportion of water is added as a solvent, and the corresponding ultrasonic power of the ultrasonic transducer in the ultrasonic vibration box is turned on for ultrasonic separation, so as to separate the graphite powder from the Cu foil to form a mixed solution of Cu foil and graphite powder;

[0030] S3, transferring the mixed solution of Cu foil and graphite powder in step S2 into a centrifuge, setting the corresponding speed of the centrifuge to remove part of the water to obtain a mixed wet material of Cu foil and graphite powder;

[0031] S4, transferring the wet mixed material of Cu foil and graphite powder in step S3 into a dryer, setting corresponding temperature and time, and drying to obtain a mixed dry material;

[0032] S5. Transfer the mixed dry material in step S4 into an eddy current separator, set the corresponding magnetic induction intensity, and separate the high-purity Cu foil and graphite powder.

[0033] Preferably, the negative electrode plate of the lithium-ion battery is one or more of natural graphite and artificial graphite.

[0034] Preferably, the diameter of the small pieces after being shredded in step S1 is 0.2-2.5 cm.

[0035] Preferably, the material-liquid ratio of the mixture to water during the ultrasonic separation process in step S2 is 1:1-1:5.

[0036] Preferably, the ultrasonic wet de-powdering device in step S3 comprises a rotating drum, a water tank and an ultrasonic vibration box. A water tank is provided below the rotating drum. The water tank is arranged in a slope and a plurality of groups of ultrasonic vibration boxes are provided on the side wall of the water tank.

[0037] Preferably, a plurality of ultrasonic transducers are provided in the ultrasonic vibration box, and the plurality of ultrasonic transducers are arranged in a matrix.

[0038] Preferably, the ultrasonic frequency of the ultrasonic transducer in the ultrasonic vibration box in step S2 is 20kHz-80kHz.

[0039] Preferably, the rotation speed of the centrifuge in step S3 is 200-1200 rpm.

[0040] Preferably, the drying temperature of the dryer in step S4 is 60-600°C.

[0041] Preferably, the magnetic induction intensity of the eddy current separation device in step S5 is 0.1-0.8T.

[0042] Example 1: A high-value selection method for a negative electrode sheet of a lithium-ion battery of the present invention takes Cu foil and natural graphite powder negative electrode as an example. Figure 1 As shown, the specific steps include:

[0043] Step 1, weigh 1 ton of lithium-ion battery negative electrode sheet material, transfer it to a shredder using a conveying device, and shred it into a mixture of negative electrode small sheets with a diameter of 0.2 cm;

[0044] Step 2: Add 1 t of water as a solvent to the ultrasonic wet separation device, so that the material-liquid ratio of the mixture to water is 1:1, transfer the shredded negative electrode small pieces into the device, set the ultrasonic frequency to 20 kHz, and keep the negative electrode small pieces in the ultrasonic separation device for 10 minutes. Use the conveying device to discharge the mixed solution of Cu foil and graphite powder;

[0045] Step 3, transfer the mixed solution into a centrifuge using a conveying device, set the speed to 200 rpm, remove most of the water, and obtain a mixed wet material of Cu foil and graphite powder;

[0046] Step 4, transferring the mixed wet material solution into a drying device, setting the drying temperature to 60° C., to obtain a dry material of a mixture of Cu foil and graphite powder;

[0047] Step 5: Transfer the mixed dry materials into the eddy current separator, set the corresponding magnetic induction intensity, and separate 321 kg of high-purity Cu foil and 689 kg of graphite powder. The purity of Cu foil is 96.2%; the purity of graphite powder is 97.3%.

[0048] Example 2, a high value selection method for a lithium ion battery negative electrode of the present invention takes Cu foil and natural graphite powder negative electrode as an example, Figure 1 As shown, the specific steps include:

[0049] Step 1, weigh 1 ton of lithium-ion battery negative electrode sheet material, transfer it to a shredder using a conveying device, and shred it into a mixture of negative electrode small sheets with a diameter of 1 cm;

[0050] Step 2: Add 2t of water as a solvent to the ultrasonic wet separation device, so that the material-liquid ratio of the mixture to water is 1:2, transfer the shredded negative electrode small pole pieces into the device, set the ultrasonic frequency to 40kHz, and keep the negative electrode small pole pieces in the ultrasonic separation device for 10min. Use the conveying device to discharge the Cu foil and graphite powder mixed solution;

[0051] Step 3, transferring the mixed solution into a centrifuge using a conveying device, setting the rotation speed to 800 rpm, removing most of the water, and obtaining a wet mixed material of Cu foil and graphite powder;

[0052] Step 4, transferring the mixed wet material solution into a drying device, setting the drying temperature to 150° C., and obtaining a dry material of a mixture of Cu foil and graphite powder;

[0053] Step 5: Transfer the mixed dry materials into the eddy current separator, set the corresponding magnetic induction intensity, and separate 305 kg of high-purity Cu foil and 695 kg of graphite powder. The purity of Cu foil is 97.3%; the purity of graphite powder is 98.2%.

[0054] Example 3, a high value selection method for a lithium ion battery negative electrode of the present invention takes Cu foil and natural graphite powder negative electrode as an example, Figure 1 As shown, the specific steps include:

[0055] Step 1, weigh 1 ton of lithium-ion battery negative electrode sheet material, transfer it to a shredder using a conveying device, and shred it into small negative electrode sheets with a diameter of 2 cm;

[0056] Step 2: Add 3t of water as a solvent to the ultrasonic wet separation device, so that the material-liquid ratio of the mixture to water is 1:3, transfer the shredded negative electrode small pole pieces into the device, set the ultrasonic frequency to 70kHz, and keep the negative electrode small pole pieces in the ultrasonic separation device for 10min. Use the conveying device to discharge the mixed solution of Cu foil and graphite powder;

[0057] Step 3, transferring the mixed solution into a centrifuge using a conveying device, setting the speed to 1000 rpm, removing most of the water, and obtaining a wet mixed material of Cu foil and graphite powder;

[0058] Step 4, transferring the mixed wet material solution into a drying device, setting the drying temperature to 160° C., to obtain a dry material of a mixture of Cu foil and graphite powder;

[0059] Step 5: Transfer the mixed dry materials into the eddy current separator, set the corresponding magnetic induction intensity, and separate 296 kg of high-purity Cu foil and 704 kg of graphite powder. The purity of Cu foil is 99.3%; the purity of graphite powder is 99.7%.

[0060] Example 4: A high value selection method for a negative electrode sheet of a lithium ion battery of the present invention takes Cu foil and natural graphite powder negative electrode as an example. Figure 1 As shown, the specific steps include:

[0061] Step 1, weigh 1 ton of lithium-ion battery negative electrode sheet material, transfer it to a shredder using a conveying device, and shred it into small negative electrode sheets with a diameter of 2.5 cm;

[0062] Step 2: Add 5t of water as a solvent to the ultrasonic wet separation device, so that the material-liquid ratio of the mixture to water is 1:5, transfer the shredded negative electrode small pieces into the device, set the ultrasonic frequency to 80kHz, and keep the negative electrode small pieces in the ultrasonic separation device for 10min. Use the conveying device to discharge the mixed solution of Cu foil and graphite powder;

[0063] Step 3, transferring the mixed solution into a centrifuge using a conveying device, setting the speed to 1200 rpm, removing most of the water, and obtaining a wet mixed material of Cu foil and graphite powder;

[0064] Step 4, transferring the mixed wet material solution into a drying device, setting the drying temperature to 600° C., to obtain a dry material of a mixture of Cu foil and graphite powder;

[0065] Step 5: Transfer the above mixed dry materials into an eddy current separator, set the corresponding magnetic induction intensity, and separate 286 kg of high-purity Cu foil and 714 kg of graphite powder. The purity of Cu foil is 99.5%; the purity of graphite powder is 99.8%.

[0066] The present invention discloses a high-value selection method for negative electrode sheets of lithium-ion batteries, which belongs to the field of lithium battery materials. The preparation method comprises the following steps. First, the negative electrode sheet material of the lithium-ion battery is transferred to a shredder and shredded; the mixed material is transferred to an ultrasonic wet de-powdering device to separate the graphite powder from the Cu foil; the mixed solution of Cu foil and graphite powder is transferred to a centrifuge to remove part of the water; the mixed wet material is transferred to a drying device for drying; the dried material is transferred to an eddy current sorting device to sort out high-purity Cu foil and graphite powder. Ultrasound and eddy current are added as core technologies in the preparation process of the present invention, and the separated and purified Cu foil and graphite powder have high purity and high added value, which are suitable for industrialization. The beneficial effect of the present invention is that the high-value selected metal Cu and graphite powder have high purity, less metal loss, high process added value, and are suitable for industrialization.

[0067] 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 present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive from any point of view. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention, and any reference numerals in the claims should not be considered as limiting the claims involved.

[0068] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description 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 may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A high-value selection method for negative electrode sheets of lithium-ion batteries, characterized in that: The method steps are as follows: S1. Put the negative electrode sheet material of the lithium-ion battery into a shredder, and shred the sheet into a mixture of small pieces of the same specifications according to certain specifications; S2, the shredded mixture in step S1 is put into an ultrasonic wet de-powdering device, a corresponding proportion of water is added as a solvent, and the corresponding ultrasonic power of the ultrasonic transducer in the ultrasonic vibration box is turned on for ultrasonic separation, so as to separate the graphite powder from the Cu foil to form a mixed solution of Cu foil and graphite powder; S3, transferring the mixed solution of Cu foil and graphite powder in step S2 into a centrifuge, setting the corresponding speed of the centrifuge to remove part of the water to obtain a mixed wet material of Cu foil and graphite powder; S4, transferring the wet mixed material of Cu foil and graphite powder in step S3 into a dryer, setting corresponding temperature and time, and drying to obtain a mixed dry material; S5. Transfer the mixed dry material in step S4 into an eddy current separator, set the corresponding magnetic induction intensity, and separate the high-purity Cu foil and graphite powder.

2. A high-value selection method for negative electrode sheets of lithium-ion batteries according to claim 1, characterized in that: In step S1, the negative electrode plate of the lithium-ion battery is one or more of natural graphite and artificial graphite.

3. A high-value selection method for negative electrode sheets of lithium-ion batteries according to claim 2, characterized in that: The diameter of the small pieces after being shredded in step S1 is 0.2-2.5 cm.

4. A high-value selection method for negative electrode sheets of lithium-ion batteries according to claim 3, characterized in that: In the ultrasonic separation process in step S2, the material-liquid ratio of the mixture to water is 1:1-1:

5.

5. A high-value selection method for negative electrode sheets of lithium-ion batteries according to claim 4, characterized in that: The ultrasonic wet de-powdering device in step S3 comprises a rotating drum, a water tank and an ultrasonic vibration box. A water tank is arranged below the rotating drum. The water tank is arranged in a slope and a plurality of groups of ultrasonic vibration boxes are arranged on the side wall of the water tank.

6. A high-value selection method for negative electrode sheets of lithium-ion batteries according to claim 5, characterized in that: The ultrasonic vibration box is provided with a plurality of ultrasonic transducers, which are arranged in a matrix.

7. A high-value selection method for negative electrode sheets of lithium-ion batteries according to claim 6, characterized in that: The ultrasonic frequency of the ultrasonic transducer in the ultrasonic vibration box in step S2 is 20kHz-80kHz.

8. A high-value selection method for negative electrode sheets of lithium-ion batteries according to claim 7, characterized in that: The rotation speed of the centrifuge in step S3 is 200-1200 rpm.

9. A high-value selection method for negative electrode sheets of lithium-ion batteries according to claim 8, characterized in that: The drying temperature of the drying machine in step S4 is 60-600°C.

10. A high-value selection method for negative electrode sheets of lithium-ion batteries according to claim 9, characterized in that: The magnetic induction intensity of the eddy current separation device in step S5 is 0.1-0.8T.

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