Method and equipment for short-process lithium extraction based on electrochemistry

Abstract

The invention relates to the technical field of waste lithium ion battery recovery, in particular to a short-process lithium extraction method and equipment based on electrochemistry. The invention aims to provide the electrochemical-based short-process lithium extraction method and the electrochemical-based short-process lithium extraction equipment which are easy to operate, low in cost, capable of effectively preventing thermal runaway and capable of efficiently extracting lithium resources. According to the technical scheme, the short-process lithium extraction method based on electrochemistry comprises the following steps: S1, laying filter cloth; s2, arranging a cathode tank; s3, setting an anode tank; s4, electrifying to transfer lithium; s5, reacting to extract lithium; s6, filtering, concentrating, crystallizing and drying. Large-scale production is achieved by increasing the volume and number of the electrolytic cell, only the upper cover of the cathode cell needs to be sealed in the reaction process, the whole electrolytic cell does not need to be sealed, operability is easier, and cost is lower.

Description

Technical Field

[0001] The invention relates to the technical field of recycling waste lithium-ion batteries, and in particular to a method and equipment for extracting lithium in a short process based on electrochemistry. Background Art

[0002] Lithium-ion batteries are widely used in electric vehicles, mobile phones, computers and other fields due to their high specific capacity, long cycle life and low self-discharge characteristics. The positive electrode materials are diverse, including lithium iron phosphate, ternary nickel cobalt manganese, ternary nickel cobalt aluminum, lithium cobalt oxide and lithium manganese oxide. Given the current high price of lithium, its value far exceeds that of other elements in the positive electrode material. When recycling waste lithium-ion batteries, the recovery of lithium becomes the primary consideration, which not only reflects the preciousness of lithium resources, but also highlights the importance of recycling and reuse.

[0003] The lithium recovery process of waste lithium-ion batteries mainly includes the following methods: first, the waste lithium-ion batteries are disassembled and physically sorted to obtain the positive electrode materials of waste lithium-ion batteries. First, all elements are leached out by acid leaching, and the lithium element is recovered after impurities are removed and nickel and cobalt are recovered by extraction; second, nickel-cobalt-manganese alloy is obtained by reduction roasting, and lithium is recovered from the slag alone; third, biological organic acid and biological flavonoids are used for leaching to recover nickel, cobalt and lithium elements in turn. In the process of recovering lithium by the above three methods, the lithium recovery rate is low and the production cost is high; another way is to use waste lithium-ion batteries without After disassembly, it is directly fully charged, and then the negative electrode is taken out in a sealed state, and lithium is recovered by chemical electrolysis. In the process of recovering lithium by the above method, industrial operation is difficult, especially for small lithium-ion batteries, which require a large amount of charging equipment and need to be disassembled in a closed space; the general charging voltage of lithium batteries is 4.3V, and only about 70% of lithium ions are transferred to the negative electrode, and the lithium recovery rate is low; after the charging voltage of the lithium-ion battery exceeds 4.8V, the lithium-ion battery generates a lot of heat, and the positive electrode material produces a large amount of oxygen to react chemically with the organic electrolyte of the lithium-ion battery, which can easily cause thermal runaway and cause fire.

[0004] In view of the above technical problems, it is necessary to design a method and equipment for extracting lithium based on an electrochemical short process that is easy to operate, effectively prevents thermal runaway and efficiently extracts lithium resources. Summary of the invention

[0005] In order to overcome the shortcomings of high production cost, low safety and low lithium recovery rate, the technical problem is to provide a method and equipment for extracting lithium based on an electrochemical short process that is easy to operate, low-cost, effectively prevents thermal runaway and efficiently extracts lithium resources.

[0006] The technical solution is: a method for extracting lithium based on electrochemistry in a short process, comprising the following steps:

[0007] S1. Laying filter cloth

[0008] Laying filter cloths on the perforated bottom plates of the cathode tank and the anode tank of the electrolytic tank respectively;

[0009] S2. Set up cathode tank

[0010] Place nano-silicon in the cathode tank, fill it with an appropriate amount of lithium-ion battery organic electrolyte, and seal the cathode tank cover;

[0011] S3. Set up anode tank

[0012] Place the waste lithium-ion battery positive electrode material into the anode tank and add an appropriate amount of aqueous electrolyte;

[0013] S4, power transfer lithium

[0014] Direct current is passed between the anode and cathode to transfer lithium in the cathode material of the waste lithium-ion battery to the nano-silicon;

[0015] S5. Reaction to extract lithium

[0016] The nano-silicon in step S4 is taken out and placed in a closed reactor, and distilled water is added to allow the nano-silicon to fully react;

[0017] S6, filtration, concentration, crystallization and drying

[0018] The distilled water after the reaction in step S5 is filtered, and the filtered filtrate is concentrated and crystallized in a closed evaporation crystallizer, and the LiOH product is obtained after closed drying.

[0019] The invention discloses an electrochemical short-process lithium extraction device, comprising an electrolytic cell, a partition, an anode cell bottom plate with holes, a cathode cell bottom plate with holes and a cathode cell cover. The partition is connected in the middle of the electrolytic cell, and the partition separates the electrolytic cell into an anode cell and a cathode cell. The anode cell is on the left side of the partition, the anode cell bottom plate with holes is connected between the lower left side of the electrolytic cell and the lower left side of the partition, the cathode cell is on the right side of the partition, the cathode cell bottom plate with holes is connected between the lower right side of the electrolytic cell and the lower right side of the partition, and the cathode cell cover is clamped on the top right side of the electrolytic cell and the top right side of the partition.

[0020] Furthermore, the method further comprises: the filter cloth in step S1 is one of polyvinylidene fluoride filter cloth, polypropylene filter cloth, polyester filter cloth, nylon filter cloth and polypropylene filter cloth, and the pore size of the filter cloth is 200-500 meshes.

[0021] Furthermore, the method further includes: the nano-silicon in step S2 includes single-substance silicon powder with a particle size of less than 1000 nanometers.

[0022] Furthermore, the method further includes: the organic electrolyte of the lithium ion battery in step S2 contains ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and organic ether.

[0023] Furthermore, the method further comprises: in step S3, the positive electrode material of the waste lithium-ion battery is the positive electrode material powder obtained by disassembling the waste lithium-ion battery and physically sorting it.

[0024] Furthermore, the method further comprises: in step S3, the aqueous electrolyte is an aqueous solution adjusted to pH>7.5 by using LiOH.

[0025] Furthermore, the method further comprises: when direct current is applied in step S4, the electrode potential of the anode is controlled at 5.5V.

[0026] The beneficial effects are as follows: 1. The present invention achieves large-scale production by increasing the volume and number of electrolytic cells, and during the reaction process, only the cathode cell cover needs to be sealed without sealing the entire electrolytic cell, which is easier to operate and has lower costs.

[0027] 2. The present invention adds aqueous electrolyte to the anode tank. Even if the anode potential reaches 5.5V, a large amount of oxygen is generated and can overflow the open anode tank. In this process, the organic electrolyte cannot be contacted, so thermal runaway can be effectively prevented, which is safer.

[0028] 3. The present invention achieves an anode potential of 5.5V, and substantially all lithium in the cathode material of waste lithium-ion batteries is transferred to nano-silicon, so that the lithium resource recovery rate reaches more than 95%, and the purity of the recovered LiOH exceeds 99%. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the lithium extraction process of the present invention.

[0030] Figure 2 It is a schematic diagram of the three-dimensional structure of the present invention.

[0031] Figure 3 It is a schematic diagram of a first partial three-dimensional structure of the present invention.

[0032] Figure 4 It is a schematic diagram of a second partial three-dimensional structure of the present invention.

[0033] Figure numbers: 1_electrolytic cell, 2_partition plate, 3_bottom plate with holes of anode cell, 4_bottom plate with holes of cathode cell, 5_upper cover of cathode cell. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0035] Example 1

[0036] A device for extracting lithium based on electrochemical short process, such as Figure 2-Figure 4As shown, it includes an electrolytic cell 1, a partition 2, an anode cell bottom plate 3 with holes, a cathode cell bottom plate 4 with holes and a cathode cell cover 5. The partition 2 is fixedly connected in the middle of the electrolytic cell 1. The partition 2 separates the electrolytic cell 1 into an anode cell and a cathode cell for subsequent electrolysis. The left side of the partition 2 is the anode cell, and the anode cell bottom plate 3 is connected between the left side of the lower part of the electrolytic cell 1 and the left side of the lower part of the partition 2 by welding. The right side of the partition 2 is the cathode cell, and the cathode cell bottom plate 4 is connected between the right side of the lower part of the electrolytic cell 1 and the right side of the lower part of the partition 2 by welding. The cathode cell cover 5 is clamped between the top right side of the electrolytic cell 1 and the top right side of the partition 2.

[0037] A short-process method for extracting lithium based on electrochemistry, such as Figure 1 As shown, the following steps are included:

[0038] S1. Laying filter cloth

[0039] 200-mesh polypropylene filter cloths are laid on the cathode tank perforated bottom plate 4 and the anode tank perforated bottom plate 3 (aperture 1 mm) in the electrolytic cell 1 respectively;

[0040] S2. Set up cathode tank

[0041] 200 g of silicon with a particle size of 900 nm is placed in the cathode tank, and an appropriate amount of lithium-ion battery organic electrolyte is filled in, and the cathode tank upper cover 5 is sealed;

[0042] S3. Set up anode tank

[0043] 500 g of waste lithium-ion battery positive electrode material was placed in the anode tank, an appropriate amount of aqueous solution was added, and the pH of the aqueous solution was adjusted to 10.3 with LiOH;

[0044] S4, power transfer lithium

[0045] A direct current is passed between the anode and the cathode, and the anode potential is controlled to be 5.5V, so that the lithium in the positive electrode material of the waste lithium-ion battery is transferred to the nano-silicon. When the current is less than 100mA, the direct current is stopped;

[0046] S5. Reaction to extract lithium

[0047] The nano-silicon in step S4 is taken out and placed in a closed reactor, and distilled water is added to allow the nano-silicon to fully react;

[0048] S6, filtration, concentration, crystallization and drying

[0049] The distilled water after the reaction in step S5 is filtered, and the filtered filtrate is concentrated and crystallized in a closed evaporation crystallizer, and the LiOH product is obtained after closed drying.

[0050] The lithium recovery rate was 95.83% and the LiOH purity was 99.61%.

[0051] Example 2

[0052] A short-process method for extracting lithium based on electrochemistry, such as Figure 1 As shown, the following steps are included:

[0053] S1. Laying filter cloth

[0054] 300-mesh polypropylene filter cloths are laid on the cathode tank perforated bottom plate 4 and the anode tank perforated bottom plate 3 (pore size 0.5 mm) in the electrolytic cell 1 respectively;

[0055] S2. Set up cathode tank

[0056] 200 g of silicon with a particle size of 500 nm is placed in the cathode tank, and an appropriate amount of lithium-ion battery organic electrolyte is filled in, and the cathode tank upper cover 5 is sealed;

[0057] S3. Set up anode tank

[0058] 500 g of waste lithium-ion battery positive electrode material was placed in the anode tank, an appropriate amount of aqueous solution was added, and the pH of the aqueous solution was adjusted to 7.9 with LiOH;

[0059] S4, power transfer lithium

[0060] A direct current is passed between the anode and the cathode, and the anode potential is controlled to be 5.5V, so that the lithium in the positive electrode material of the waste lithium-ion battery is transferred to the nano-silicon. When the current is less than 100mA, the direct current is stopped;

[0061] S5. Reaction to extract lithium

[0062] The nano-silicon in step S4 is taken out and placed in a closed reactor, and distilled water is added to allow the nano-silicon to fully react;

[0063] S6, filtration, concentration, crystallization and drying

[0064] The distilled water after the reaction in step S5 is filtered, and the filtered filtrate is concentrated and crystallized in a closed evaporation crystallizer, and the LiOH product is obtained after closed drying.

[0065] The lithium recovery rate was 95.56% and the LiOH purity was 99.32%.

[0066] Example 3

[0067] A short-process method for extracting lithium based on electrochemistry, such as Figure 1 As shown, the following steps are included:

[0068] S1. Laying filter cloth

[0069] 500-mesh polypropylene filter cloths are laid on the cathode tank perforated bottom plate 4 and the anode tank perforated bottom plate 3 (aperture 5 mm) of the electrolytic cell 1 respectively;

[0070] S2. Set up cathode tank

[0071] 200g of silicon with a particle size of 200nm is placed in the cathode tank, and an appropriate amount of lithium-ion battery organic electrolyte is filled in, and the cathode tank upper cover 5 is sealed;

[0072] S3. Set up anode tank

[0073] 500 g of waste lithium-ion battery positive electrode material was placed in the anode tank, an appropriate amount of aqueous solution was added, and the pH of the aqueous solution was adjusted to 9.4 with LiOH;

[0074] S4, power transfer lithium

[0075] A direct current is passed between the anode and the cathode, and the anode potential is controlled to be 5.5V, so that the lithium in the positive electrode material of the waste lithium-ion battery is transferred to the nano-silicon. When the current is less than 100mA, the direct current is stopped;

[0076] S5. Reaction to extract lithium

[0077] The nano-silicon in step S4 is taken out and placed in a closed reactor, and distilled water is added to allow the nano-silicon to fully react;

[0078] S6, filtration, concentration, crystallization and drying

[0079] The distilled water after the reaction in step S5 is filtered, and the filtered filtrate is concentrated and crystallized in a closed evaporation crystallizer, and the LiOH product is obtained after closed drying.

[0080] The lithium recovery rate was 95.81% and the LiOH purity was 99.42% after analysis.

[0081] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for extracting lithium based on electrochemistry in a short process, characterized in that: The following steps are included: S1. Laying filter cloth Laying filter cloths on the perforated bottom plates of the cathode tank and the anode tank of the electrolytic tank respectively; S2. Set up cathode tank Place nano-silicon in the cathode tank, fill it with an appropriate amount of lithium-ion battery organic electrolyte, and seal the cathode tank cover; S3. Set up anode tank Place the waste lithium-ion battery positive electrode material into the anode tank and add an appropriate amount of aqueous electrolyte; S4, power transfer lithium Direct current is passed between the anode and cathode to transfer lithium in the cathode material of the waste lithium-ion battery to the nano-silicon; S5. Reaction to extract lithium The nano-silicon in step S4 is taken out and placed in a closed reactor, and distilled water is added to allow the nano-silicon to fully react; S6, filtration, concentration, crystallization and drying The distilled water after the reaction in step S5 is filtered, and the filtered filtrate is concentrated and crystallized in a closed evaporation crystallizer, and the LiOH product is obtained after closed drying.

2. A device for extracting lithium by a short process based on electrochemistry, characterized in that: The invention comprises an electrolytic cell (1), a partition (2), an anode cell bottom plate with holes (3), a cathode cell bottom plate with holes (4) and a cathode cell upper cover (5). A partition (2) is connected in the middle of the electrolytic cell (1), and a plurality of through holes are opened at the bottom of the partition (2). The partition (2) divides the electrolytic cell (1) into an anode cell and a cathode cell. The current in the cathode cell and the anode cell can flow through the through holes at the bottom of the partition (2). The left side of the partition (2) is the anode cell. An anode cell bottom plate with holes (3) is connected between the left side of the lower part of the electrolytic cell (1) and the left side of the lower part of the partition (2). The right side of the partition (2) is the cathode cell. A cathode cell bottom plate with holes (4) is connected between the right side of the lower part of the electrolytic cell (1) and the right side of the lower part of the partition (2). A cathode cell upper cover (5) is clamped between the top of the right side of the electrolytic cell (1) and the top of the right side of the partition (2).

3. The method for extracting lithium based on a short electrochemical process according to claim 1, characterized in that: The method further comprises: the filter cloth in step S1 is one of polyvinylidene fluoride filter cloth, polypropylene filter cloth, polyester filter cloth, nylon filter cloth and polypropylene filter cloth, and the pore size of the filter cloth is 200-500 meshes.

4. The method for extracting lithium based on a short electrochemical process according to claim 1, characterized in that: It also includes: the nano silicon in step S2 includes single silicon powder with a particle size below 1000 nanometers.

5. The method for extracting lithium based on a short electrochemical process according to claim 1, characterized in that: It also includes: the organic electrolyte of the lithium ion battery in step S2 contains ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and organic ether.

6. The method for extracting lithium based on a short electrochemical process according to claim 1, characterized in that: It also includes: in step S3, the positive electrode material of the waste lithium-ion battery is the positive electrode material powder obtained by disassembling the waste lithium-ion battery and physically sorting it.

7. The method for extracting lithium based on a short electrochemical process according to claim 1, characterized in that: It also includes: in step S3, the aqueous solution electrolyte is an aqueous solution adjusted to pH>7.5 using LiOH.

8. The method for extracting lithium based on a short electrochemical process according to claim 1, characterized in that: The method further comprises: when direct current is supplied in step S4, the electrode potential of the anode is controlled at 5.5V.

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