Method for recycling metal in lithium ion battery by using waste photovoltaic panel

Abstract

The invention belongs to the technical field of environment, and provides a method for recycling metal in a lithium ion battery by using a waste photovoltaic panel, which comprises the following steps: placing a crystalline silicon battery piece in an HCl solution to remove Al, then placing the crystalline silicon battery piece in HNO3 to remove Ag, filtering to obtain a flaky silicon wafer, and then converting the flaky silicon wafer into powder to obtain crystalline silicon powder A; soaking the positive plate in a NaOH solution to remove the aluminum foil, and sequentially washing, filtering and drying to obtain positive powder B; fully mixing the crystalline silicon powder A and the positive electrode powder B, and heating in an inert atmosphere to obtain reacted powder; and adding water into the reacted powder, leaching for a preset time at a preset temperature under a stirring condition, and filtering to obtain a Li2SiO3 solution and Co-containing filter residues. According to the method, the crystalline silicon obtained through simple pretreatment of the photovoltaic panel is used for cooperatively treating and recycling valuable metal of the lithium ion battery, the source problem of the crystalline silicon is solved, emission of harmful gas and greenhouse gas is reduced, and precious metal Li, Co and the like in waste are recycled.

Description

Technical Field

[0001] The present invention belongs to the field of environmental technology, and particularly relates to a method for recycling metals in lithium-ion batteries by using waste photovoltaic panels. Background Art

[0002] With the rapid development of the photovoltaic industry and electric vehicles, photovoltaic cells, as an important clean energy technology, have been widely used. However, with the end of the service life of the equipment and the technological progress leading to the replacement and iteration, a large number of waste crystalline silicon photovoltaic and power batteries have flooded into the market, triggering the need for the treatment and resource recovery of waste photovoltaic and energy storage batteries.

[0003] Traditional retired photovoltaic panels are landfilled and incinerated. Moreover, currently, the number of solar photovoltaic panels is increasing geometrically every year, and improper treatment is a waste of resources. At present, the treatment technologies for the recycling of retired crystalline silicon photovoltaic modules mainly include inorganic acid dissolution method, organic solvent dissolution method, heat treatment method, mechanical separation method, chemical purification method, and combined separation method, etc. Waste photovoltaic panels contain valuable metals and silicon materials, and the existing treatment methods mainly focus on the recovery of metals and high-purity silicon. However, the process technology for recovering high-purity silicon is complex and costly.

[0004] Waste lithium-ion batteries contain a large number of metal elements with high recycling value, such as lithium, cobalt, nickel, and manganese, and also contain a large number of toxic substances, including electrolytes, diaphragms, active substances, etc. The conventional treatment of lithium-ion batteries is carbothermal reduction and sulfidation roasting, etc. During the process of extracting metals, harmful gases and a large amount of greenhouse gas emissions will be generated.

[0005] Therefore, it is urgent to develop an efficient and environmentally friendly LIB recycling technology. It is of great significance to combine the two for co-recycling.

[0006] The information disclosed in this background art section is only intended to enhance the overall understanding of the present invention and should not be regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for recycling metals in lithium-ion batteries by using waste photovoltaic panels for the collaborative treatment and resource utilization of electronic waste.

[0008] The present invention provides a method for recycling metals in lithium-ion batteries by using waste photovoltaic panels, which has the following characteristics and includes the following steps:

[0009] Step S1, placing the crystalline silicon cell obtained by pre-treating the waste photovoltaic panel in a 2 mol / L HCl solution to remove Al, and then further placing it in a 2 mol / L HNO3 solution to remove Ag, filtering to obtain a sheet-like silicon wafer, and then converting the sheet-like silicon wafer into a powder by mechanical stirring to obtain a crystalline silicon powder A;

[0010] Step S2: soaking the positive electrode sheet removed from the waste battery in a NaOH solution to remove the aluminum foil, and then washing, filtering and drying the positive electrode sheet to obtain positive electrode powder B;

[0011] Step S3, crystalline silicon powder A and positive electrode powder B are fully mixed by ball milling at a mass ratio of 1:1 to 1:10, and then heated at 400° C. to 800° C. in an inert atmosphere for a predetermined time to obtain a reacted powder;

[0012] Step S4, adding water to the reacted powder at a mass ratio of 20 g / L, leaching at a predetermined temperature for a predetermined time under stirring conditions, and then filtering to obtain a Li2SiO3 solution and a Co-containing filter residue.

[0013] The method for recovering metals in lithium-ion batteries using waste photovoltaic panels provided by the present invention may also have the following characteristics: wherein, in step S4, the Co-containing filter residue is subjected to wet magnetic separation to obtain CoO and Co.

[0014] The method for recovering metals in lithium-ion batteries using waste photovoltaic panels provided by the present invention may also have the following characteristics: wherein, in step S4, dilute H2SO4 with a mass concentration of 1 mol / L to 3 mol / L is added to the Co-containing filter residue to dissolve and obtain CoSO4.

[0015] The method for recovering metals in lithium-ion batteries using waste photovoltaic panels provided by the present invention may also have the following characteristics: wherein, in step S4, deionized water is added to the powder after the reaction, and the powder is leached at 30°C to 60°C for 5min to 60min by magnetic stirring and then filtered to obtain a Li2SiO3 solution and a Co-containing filter residue.

[0016] The method for recovering metals in lithium-ion batteries using waste photovoltaic panels provided by the present invention may also have the following characteristics: wherein, in step S1, the crystalline silicon cell is placed in a 2 mol / L HCl solution at a ratio of 100 g / L at 40°C to 70°C to remove Al, and then is further placed in a 2 mol / L HNO3 solution at a ratio of 100 g / L at 40°C to 70°C to remove Ag.

[0017] In the method for recycling metals in lithium-ion batteries using waste photovoltaic panels provided by the present invention, it may further have the following characteristics: In step S1, the positive electrode sheet removed from the waste battery is soaked in a 5% NaOH solution for 30 minutes to remove the aluminum foil, rinsed and filtered with deionized water multiple times, and dried to obtain positive electrode powder B.

[0018] In the method for recycling metals in lithium-ion batteries using waste photovoltaic panels provided by the present invention, it may further have the following characteristics: In step S4, the crystalline silicon powder A and the positive electrode powder B are ball-milled for 10 minutes to 30 minutes in a mass ratio of 1:1 to 1:10 for sufficient mixing, and then placed in an inert atmosphere and heated at 400°C to 800°C for 30 minutes to 60 minutes to obtain the reacted powder.

[0019] In the method for recycling metals in lithium-ion batteries using waste photovoltaic panels provided by the present invention, it may further have the following characteristics: In step S1, the process of pretreating the waste photovoltaic panel is specifically as follows: The waste photovoltaic panel, the aluminum frame and copper wire are removed, and then the photovoltaic panel is cut into small pieces of uniform size with a cutting tool, and placed in a muffle furnace and heated at 500°C for 1 hour to remove the EVA adhesive and the TPT backplane to obtain crystalline silicon solar cells.

[0020] In the method for recycling metals in lithium-ion batteries using waste photovoltaic panels provided by the present invention, it may further have the following characteristics: In step S2, the process of removing the positive electrode sheet from the waste battery is specifically as follows: The battery is immersed in 5% sodium chloride for 24 hours to remove the remaining charge, then rinsed with deionized water and dried for 12 hours, and then the waste battery is manually disassembled in a fume hood. The obtained crude positive electrode sheet is soaked in ethanol for 1 hour, and washed with double-distilled water to remove the residual electrolyte, and then vacuum dried to obtain the positive electrode sheet.

[0021] In the method for recycling metals in lithium-ion batteries using waste photovoltaic panels provided by the present invention, it may further have the following characteristics: The waste battery is a waste LiCoO2 battery or a waste NCM battery.

[0022] Functions and effects of the invention

[0023] A method for recovering metals in lithium-ion batteries using waste photovoltaic panels. The photovoltaic panels are simply processed and reacted with hydrochloric acid and nitric acid to obtain AlCl3 and AgNO3 solutions and crystalline silicon powder (hereinafter referred to as silicon powder). This silicon powder serves as a reducing agent and lithium carrier during the roasting process of lithium-ion batteries, converting LiCoO2 in waste batteries into Li2SiO3 solution and CoO / Co products. Without adding an additional reducing agent, it has a good reduction effect, realizing the recovery of metals in lithium-ion batteries by using waste photovoltaic panels. Since recycled silicon is used as the reducing agent, abandoning traditional carbothermal reduction or molten salt roasting, no toxic and harmful gases are generated during the roasting process, and there is basically no mass loss during the roasting process of the entire system, with a high conversion rate. Therefore, this process is simple, the conditions are good, and the recovery process cycle is short.

[0024] The present invention selects water and the reacted powder to form a leaching system. Water can selectively and efficiently leach lithium to form a Li2SiO3 solution, while CoO / Co remains as a solid called filter residue. Therefore, only water can effectively and selectively extract lithium from waste materials, ensuring a high leaching rate of metal elements, and efficient separation of cobalt and lithium products can be achieved through filtration.

[0025] Therefore, the present invention uses the crystalline silicon obtained by simply pretreating the photovoltaic panels to synergistically process and recover valuable metals in lithium-ion batteries, solves the problem of the source of crystalline silicon, reduces the emissions of harmful gases and greenhouse gases, and recovers precious metals such as Li and Co in waste materials. Since silicon does not produce toxic gases at high temperatures, and there is basically no mass loss during the roasting process of the entire system, with a high conversion rate, it is environmentally friendly while ensuring a high leaching rate of metal elements. The process of the present invention is simple and has a good recovery effect. This process has significant economic and environmental benefits in the extraction of valuable metals, contributing to the economic circular development of LIBs and photovoltaic systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the X-ray diffraction pattern after the reaction of recycled silicon and the positive electrode of waste lithium-ion batteries at different temperatures in Test Example 1 of the present invention;

[0027] Figure 2 It is the morphology structure diagram after the reaction at different temperatures in Test Example 2 of the present invention;

[0028] Figure 3 It is the leaching rate of lithium after the reaction at different temperatures in Test Example 3 of the present invention;

[0029] Figure 4 It is the XRD image of the filter residue before and after leaching in Test Example 4 of the present invention;

[0030] Figure 5 It is the XRD image of the filter residue after magnetic separation in Test Example 5 of the present invention;

[0031] Figure 6 It is the XRD pattern of the reaction between NCM and silicon medium in Test Example 6 of the present invention;

[0032] Figure 7 It is the thermogravimetric analysis chart in Test Example 7 of the present invention. Specific Embodiments

[0033] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the following specifically describes a method for recycling metals in lithium-ion batteries using waste photovoltaic panels in conjunction with embodiments and drawings.

[0034] Unless otherwise specified, the raw materials used in the present invention are all purchased through general commercial channels. All unmentioned test standards are national standards.

[0035] The source information of some materials and instruments involved in the embodiments is as follows:

[0036] Waste LiCoO2 batteries (waste lithium cobalt oxide batteries) come from the Apple batteries provided by Shanghai Lingang Machine Repair Shop;

[0037] Waste crystalline silicon photovoltaic panels come from the online shopping Alibaba platform;

[0038] The used nitric acid (HNO3) and hydrochloric acid (HCl) are obtained from Shanghai Sinopharm Chemical Reagent Co., Ltd., China, and the used absolute ethanol (C2H6O) is purchased from Aladdin Company;

[0039] The X-ray diffractometer is XRD, model Smartlab SE from Japan;

[0040] The atomic absorption spectrometer is TAS-990, Beijing Purkinje General Instrument Co., Ltd.;

[0041] The scanning electron microscope SEM, model Sigma 300 from Germany;

[0042] The thermogravimetric analyzer TG, model Jupiter STA 449F3 from Germany.

[0043] <Example 1>

[0044] A method for recycling metals in lithium-ion batteries using waste photovoltaic panels specifically includes the following steps:

[0045] Step S1: First, pre-treat the waste photovoltaic panels. Specifically, manually remove the aluminum frames, cut the photovoltaic panels into small pieces of uniform size using a cutting tool, place them in a muffle furnace and heat at 500 °C for 1 h to remove the EVA adhesive and TPT backsheet, obtaining crystalline silicon cells. Then, immerse the cells in a 2 mol / L HCl solution to remove Al. After rinsing and drying, continue to immerse them in 2 mol / L HNO3 to remove Ag. After filtration, repeatedly wash and dry. The obtained silicon wafers are mechanically stirred to convert the flakes into powder form, obtaining crystalline silicon powder A. In this step, the waste photovoltaic panels are crystalline silicon photovoltaics. The muffle furnace is heated at a rate of 5 °C / min. Heating and stirring during the inorganic acid dissolution process can accelerate the dissolution. In addition, the acid concentration affects the dissolution rate. The above-mentioned crystalline silicon photovoltaics and inorganic acid are carried out in a ratio of 100 g / L. During the reaction process, the temperature is controlled at 50 °C and the reaction time is 2 h to ensure full reaction.

[0046] Step S2: First, perform the following pre-treatment on the waste lithium cobalt oxide batteries. Specifically, immerse the batteries in a 5% (w / v) sodium chloride solution for 24 h to remove the remaining charge, rinse with deionized water and dry for 12 h. Further, manually disassemble the waste LiCoO2 batteries in a fume hood. Immerse the obtained crude positive electrode sheets in ethanol for 1 h, wash with double-distilled water to remove the residual electrolyte, and then vacuum dry to obtain the positive electrode sheets. Next, immerse the obtained positive electrode sheets in 5% NaOH to separate them from the aluminum foil, thereby realizing the stripping of the positive electrode. Then, repeatedly rinse and filter with deionized water and dry to obtain positive lithium cobalt oxide powder B.

[0047] Step S3: Mix crystalline silicon powder A and positive electrode powder B in a mass ratio of 1:4, and fully mix them by ball milling for 30 min. Place them under argon and heat at a rate of 5 °C / min to 700 °C for 60 min to obtain the calcined reaction powder.

[0048] Step S4: Place the reaction powder in deionized water according to a mass ratio of 20 g / L, and magnetically stir at 60 °C for 30 min. Through suction filtration, obtain a solution containing lithium ions, i.e., Li2SiO3 solution, and a filter residue in which CoO and Co are mixed together. The leaching rate of lithium reaches 95.54%; the filter residue can be obtained by wet magnetic separation to obtain CoO and Co.

[0049] <Example 2>

[0050] A method for recycling metals in lithium-ion batteries using waste photovoltaic panels specifically includes the following steps:

[0051] Step S1: First, pre-treat the waste photovoltaic panels as follows: Manually remove the aluminum frames, cut the photovoltaic panels into small pieces of uniform size using a cutting tool, place them in a muffle furnace and heat at 500 °C for 1 h to remove the EVA adhesive and TPT backsheet, obtaining crystalline silicon cells. Then place the cells in a 2 mol / L HCl solution to remove Al. After rinsing and drying, continue to place them in 2 mol / L HNO3 to remove Ag. After filtration, repeatedly wash and dry, and the obtained silicon wafers are mechanically stirred to convert the flakes into powder form, obtaining crystalline silicon powder A. In this step, the waste photovoltaic panels are crystalline silicon photovoltaics, the muffle furnace is heated at a rate of 5 °C / min, heating and stirring during the inorganic acid dissolution process can accelerate the dissolution, and in addition, the acid concentration affects the dissolution rate. The above-mentioned crystalline silicon photovoltaics and inorganic acid are carried out at a ratio of 100 g / L, the temperature is controlled at 50 °C during the reaction process, and the reaction time is 2 h to ensure sufficient reaction.

[0052] Step S2: First, pre-treat the waste lithium cobalt oxide batteries as follows: Immerse the batteries in a 5% (w / v) sodium chloride solution for 24 hours to remove the remaining charge, rinse with deionized water and dry for 12 hours. Further, manually disassemble the waste LiCoO2 batteries in a fume hood, soak the obtained crude positive electrode sheets in ethanol for 1 h, and wash with double-distilled water to remove the residual electrolyte, and then vacuum dry to obtain the positive electrode sheets. Next, soak the obtained positive electrode sheets in 5% NaOH to separate them from the aluminum foil to achieve the stripping of the positive electrode, and then repeatedly rinse and filter with deionized water and dry to obtain positive lithium cobalt oxide powder B.

[0053] Step S3: Mix the crystalline silicon powder A and the positive electrode powder B in a mass ratio of 1:4, and fully mix them by ball milling for 30 min. Place them under argon and heat at a rate of 5 °C / min to 800 °C for 60 min to obtain the calcined reaction powder.

[0054] Step S4: Place the reaction powder in deionized water at a mass ratio of 20 g / L, and leach at 60 °C for 30 min by magnetic stirring. After suction filtration, obtain a solution containing lithium ions, namely Li2SiO3 solution, and a filter residue containing only Co. The leaching rate of lithium reaches 92.43%; the filter residue can be obtained by wet magnetic separation of Co.

[0055] <Example 3>

[0056] A method for recycling metals in lithium-ion batteries using waste photovoltaic panels specifically includes the following steps:

[0057] Step S1: First, pre-treat the waste photovoltaic panels. Specifically, manually remove the aluminum frames, cut the photovoltaic panels into small pieces of uniform size using a cutting tool, place them in a muffle furnace and heat at 500 °C for 1 h to remove the EVA adhesive and the TPT backsheet, obtaining crystalline silicon cells. Then, immerse the cells in a 2 mol / L HCl solution to remove Al. After rinsing and drying, continue to immerse them in 2 mol / L HNO3 to remove Ag. After filtration and repeated washing and drying, the obtained silicon wafers are mechanically stirred to convert the flakes into powder form, obtaining crystalline silicon powder A. In this step, the waste photovoltaic panels are crystalline silicon photovoltaics. The muffle furnace is heated at a rate of 5 °C / min. Heating and stirring during the inorganic acid dissolution process can accelerate the dissolution. Additionally, the acid concentration affects the dissolution rate. The above-mentioned crystalline silicon photovoltaics and inorganic acid are carried out at a ratio of 100 g / L. During the reaction process, the temperature is controlled at 50 °C and the reaction time is 2 h to ensure sufficient reaction.

[0058] Step S2: First, perform the following pre-treatment on the waste lithium cobalt oxide batteries. Specifically, immerse the batteries in a 5% (w / v) sodium chloride solution for 24 h to remove the remaining charge, rinse with deionized water and dry for 12 h. Further, manually disassemble the waste LiCoO2 batteries in a fume hood. Immerse the obtained crude positive electrode sheets in ethanol for 1 h, wash with double-distilled water to remove the residual electrolyte, and then vacuum dry to obtain the positive electrode sheets. Next, immerse the obtained positive electrode sheets in 5% NaOH to separate them from the aluminum foil, thereby achieving the stripping of the positive electrode. Then, repeatedly rinse and filter with deionized water and dry to obtain positive lithium cobalt oxide powder B.

[0059] Step S3: Mix the crystalline silicon powder A and the positive electrode powder B in a mass ratio of 1:4, and perform sufficient mixing by ball milling for 30 min. Place it under argon and heat it to 700 °C at a rate of 5 °C / min for 60 min to obtain the calcined reaction powder.

[0060] Step S4: Place the reaction powder in deionized water according to a mass ratio of 20 g / L, perform magnetic stirring, and leach at 60 °C for 30 min. Through suction filtration, obtain a solution containing lithium ions, namely Li2SiO3 solution, and a filter residue in which CoO and Co are mixed together. The filter residue can be dissolved in CoO and Co by adding 2 mol / L H2SO4 to obtain CoSO4 product.

[0061] <Example 4>

[0062] A method for recycling metals in lithium-ion batteries using waste photovoltaic panels, specifically including the following steps:

[0063] Step S1: First, pre-treat the waste photovoltaic panels. Specifically, manually remove the aluminum frames, cut the photovoltaic panels into small pieces of uniform size using a cutting tool, place them in a muffle furnace and heat at 500 °C for 1 h to remove the EVA adhesive and TPT backsheet, obtaining crystalline silicon cells. Then place the cells in a 2 mol / L HCl solution to remove Al. After rinsing and drying, continue to place them in 2 mol / L HNO3 to remove Ag. After filtration, repeatedly wash and dry, and the obtained silicon wafers are mechanically stirred to convert the flakes into powder form, obtaining crystalline silicon powder A. In this step, the waste photovoltaic panels are crystalline silicon photovoltaics, the muffle furnace is heated at a rate of 5 °C / min, heating and stirring during the inorganic acid dissolution process can accelerate the dissolution, and in addition, the acid concentration affects the dissolution rate. The above-mentioned crystalline silicon photovoltaics and inorganic acid are carried out in a ratio of 100 g / L, the temperature is controlled at 50 °C during the reaction process, and the reaction time is 2 h to ensure full reaction.

[0064] Step S2: First, perform the following pre-treatment on the waste NCM batteries. Specifically, immerse the batteries in a 5% (w / v) sodium chloride solution for 24 h to remove the remaining charge, rinse with deionized water and dry for 12 h. Further, manually disassemble the waste NCM batteries in a fume hood, soak the obtained crude positive electrode sheets in ethanol for 1 h, and wash with double-distilled water to remove the residual electrolyte, then vacuum dry to obtain the positive electrode sheets. Next, soak the obtained positive electrode sheets in 5% NaOH to separate them from the aluminum foil to achieve the stripping of the positive electrode, then repeatedly rinse and filter with deionized water, and dry to obtain positive electrode NCM powder B.

[0065] Step S3: Mix crystalline silicon powder A and positive electrode powder B in a mass ratio of 1:4, fully mix them by ball milling for 30 min, place them under argon and heat at a rate of 5 °C / min to 700 °C for 60 min to obtain the calcined reaction powder.

[0066] Step S4: Place the reaction powder in deionized water according to a mass ratio of 20 g / L, stir magnetically, leach at 60 °C for 30 min, and perform suction filtration to obtain a solution containing lithium ions, namely Li2SiO3 solution, and a filter residue. The filter residue is an oxygen-containing compound of Ni, Co, and Mn.

[0067] <Comparative Example 1>

[0068] A method for recycling metals in lithium-ion batteries using waste photovoltaic panels specifically includes the following steps:

[0069] Step S1: First, pre-treat the waste photovoltaic panels as follows: Manually remove the aluminum frames, cut the photovoltaic panels into small pieces of uniform size with a cutting tool, place them in a muffle furnace and heat at 500 °C for 1 h to remove the EVA adhesive and the TPT backsheet, obtaining crystalline silicon wafers. Then place the wafers in a 2 mol / L HCl solution to remove Al. After rinsing and drying, continue to place them in 2 mol / L HNO3 to remove Ag. After filtration and repeated washing and drying, the obtained silicon wafers are mechanically stirred to convert the flakes into powder form, obtaining crystalline silicon powder A. In this step, the waste photovoltaic panels are crystalline silicon photovoltaics. The muffle furnace is heated at a rate of 5 °C / min. Heating and stirring during the inorganic acid dissolution process can accelerate the dissolution. In addition, the acid concentration affects the dissolution rate. The above-mentioned crystalline silicon photovoltaics and inorganic acid are carried out in a ratio of 100 g / L. During the reaction process, the temperature is controlled at 50 °C and the reaction time is 2 h to ensure full reaction.

[0070] Step S2: First, pre-treat the waste lithium cobalt oxide batteries as follows: Immerse the batteries in a 5% (w / v) sodium chloride solution for 24 h to remove the remaining charge, rinse with deionized water and dry for 12 h. Further, manually disassemble the waste LiCoO2 batteries in a fume hood. Soak the obtained crude positive electrode sheets in ethanol for 1 h, wash with double-distilled water to remove the residual electrolyte, and then vacuum dry to obtain the positive electrode sheets. Next, soak the obtained positive electrode sheets in 5% NaOH to separate them from the aluminum foil, thereby realizing the stripping of the positive electrode. Then, repeatedly rinse and filter with deionized water and dry to obtain positive lithium cobalt oxide powder B.

[0071] Step S3: Mix the crystalline silicon powder A and the positive electrode powder B in a mass ratio of 1:4, and perform sufficient mixing by ball milling for 30 min. Place it under argon and heat it to 500 °C at a rate of 5 °C / min for 60 min to obtain the calcined reaction powder.

[0072] Step S4: Place the reaction powder in deionized water according to a mass ratio of 20 g / L, and perform magnetic stirring. Leach at 60 °C for 30 min, and obtain a solution containing lithium ions and a filter residue through suction filtration. At this time, the leaching rate of lithium is 51.64%, which does not reach the expected effect.

[0073] <Comparative Example 2>

[0074] A method for recovering metals in lithium-ion batteries using waste photovoltaic panels specifically includes the following steps:

[0075] Step S1: First, pre-treat the waste photovoltaic panels. Specifically, manually remove the aluminum frames, cut the photovoltaic panels into small pieces of uniform size with a cutting tool, place them in a muffle furnace and heat at 500 °C for 1 h to remove the EVA adhesive and TPT backplane, obtaining crystalline silicon cells. Then, immerse the cells in a 2 mol / L HCl solution to remove Al, rinse and dry them, and then continue to immerse them in 2 mol / L HNO3 to remove Ag. After filtration, repeatedly wash and dry them. The obtained silicon wafers are mechanically stirred to convert the flakes into powder form, obtaining crystalline silicon powder A. In this step, the waste photovoltaic panels are crystalline silicon photovoltaics. The muffle furnace is heated at a rate of 5 °C / min. Heating and stirring during the inorganic acid dissolution process can accelerate the dissolution. In addition, the acid concentration affects the dissolution rate. The above-mentioned crystalline silicon photovoltaics and inorganic acid are carried out in a ratio of 100 g / L. During the reaction process, the temperature is controlled at 50 °C and the reaction time is 2 h to ensure full reaction.

[0076] Step S2: First, perform the following pre-treatment on the waste lithium cobalt oxide batteries. Specifically, immerse the batteries in a 5% (w / v) sodium chloride solution for 24 hours to remove the remaining charge, rinse with deionized water and dry for 12 hours. Further, manually disassemble the waste LiCoO2 batteries in a fume hood. Immerse the obtained crude positive electrode sheets in ethanol for 1 h, wash them with double-distilled water to remove the residual electrolyte, and then vacuum dry them to obtain the positive electrode sheets. Next, immerse the obtained positive electrode sheets in 5% NaOH to separate them from the aluminum foil, thereby realizing the stripping of the positive electrode. Then, repeatedly rinse and filter with deionized water and dry to obtain positive lithium cobalt oxide powder B.

[0077] Step S3: Mix crystalline silicon powder A and positive electrode powder B in a mass ratio of 1:4, and fully mix them by ball milling for 30 min. Place them under argon and heat at a rate of 5 °C / min to 600 °C for 60 min to obtain the calcined reaction powder.

[0078] Step S4: Place the reaction powder in deionized water according to a mass ratio of 20 g / L, stir magnetically, leach at 60 °C for 30 min, and perform suction filtration to obtain a solution containing lithium ions and filter residue. At this time, the leaching rate of lithium is 87%, and the reaction is not complete, failing to achieve the expected effect.

[0079] <Test Example 1>

[0080] Use XRD to measure the above-mentioned calcined substances, and the obtained X-ray diffraction patterns are as Figure 1 shown. Among them, Roasting-500 °C represents Comparative Example 1, Roasting-600 °C represents Comparative Example 2, Roasting-700 °C represents Example 1, and Roasting-800 °C represents Example 2.

[0081] From Figure 1It can be seen that when the calcination temperature is 500℃, due to the residual polyvinylidene fluoride and a small amount of conductive carbon in the positive electrode material, part of the structure is destroyed and a small amount of CoO (PDF-97-017-4027) is generated, but the LiCoO2 (PDF#97-004-8103) lattice structure still exists, and silicon mediation basically does not participate in the reaction. When the temperature rises to 600℃, the peak of Li2SiO3 (PDF-97-001-6626) appears. At this time, the LiCoO2 phase transforms to the Li2SiO3 phase, and the peak of CoO is stronger. At this time, the peak of LiCoO2 still exists, and it begins to react with the LiCoO2 positive electrode powder under the action of silicon-mediated reduction. When the temperature rises to 700℃, the peak of LiCoO2 completely disappears, and the peak of metal Co appears, indicating that CoO further reacts with silicon mediation to generate metal Co. At this time, the LiCoO2 positive electrode powder is completely decomposed. At this time, it mainly exists in the form of metal oxide CoO, but there is still a trace amount of Co. When the temperature rises to 800℃, the CoO peak disappears completely and is reduced to metallic element Co by silicon-mediated reduction. At this time, the peak phase mainly exists in the form of Li2SiO3, Co and a small amount of silicon powder.

[0082] <Test Example 2>

[0083] The calcined material was measured by SEM, and the obtained SEM image is as follows: Figure 2 As shown. Wherein, (a) represents comparative example 1 (500°C), (b) represents comparative example 2 (600°C), (c) represents example 1 (700°C), and (d) represents example 2 (800°C). Wherein temperature represents the calcination temperature.

[0084] from Figure 2 It can be seen that at 500°C, slight cracks appeared on the surface, but the LiCoO2 layered structure was intact. At 600°C, the surface began to break, the octahedral structure began to collapse, and lost its previous configuration. When the temperature is 700°C, the LiCoO2 structure is completely degraded from the surface to the inside, forming an irregular porous structure. In addition, a small amount of particle agglomeration will occur in the surrounding area, and a single Co with a smooth surface will be formed. When the temperature is 800°C, the structure will form a smooth, agglomerated metal Co morphology.

[0085] <Test Example 3>

[0086] The leaching solution was analyzed by atomic absorption (Beijing Puxi TAS-990AFG), such as Figure 3As shown in the figure. Among them, the vertical coordinate is the leaching rate, and the horizontal coordinate is the roasting temperature; 500°C represents Comparative Example 1, 600°C represents Comparative Example 2, 700°C represents Example 1, and 800°C represents Example 2. In addition, Cathode represents the pretreated LiCoO2 cathode powder, and Cathode+Silion represents the mixed powder after ball milling of the LiCoO2 cathode powder and the recovered Si powder.

[0087] It can be obtained from Figure 3 that the leaching rate of the leachate of the substance after the reaction at 500°C under the condition of Cathode+Silion is 51.64%, the leaching rate of the leachate of the substance after the reaction at 600°C is 87%, the leaching rate of the leachate of the substance after the reaction at 700°C is 95.54%, and the leaching rate of the leachate of the substance after the reaction at 800°C is 92.43%. However, the leaching rate under the condition of Cathode is low and cannot be leached.

[0088] <Test Example 4>

[0089] The filter residue before and after leaching in Example 1 was analyzed by XRD, as Figure 4 shown. Among them, leaching-10min represents the filter residue after leaching, and roasting-700°C represents the filter residue before leaching.

[0090] It can be known from Figure 4 that after leaching, the peak corresponding to Li2SiO3 completely disappears. At this time, lithium is preferentially selectively leached, and the remaining filter residue is mainly CoO and excess silicon powder.

[0091] <Test Example 5>

[0092] The substances before and after magnetic separation in Example 1 were analyzed by XRD, as Figure 5 shown. Among them, leaching-10min represents the powder after leaching the roasted powder with deionized water for 10 minutes, and magnetic separation represents magnetic separation of the powder after leaching-10min.

[0093] It can be known from Figure 5 that after magnetic separation, silicon can be completely classified to obtain the main product CoO.

[0094] <Test Example 6>

[0095] The product after roasting at 700°C in Example 4 was tested by XRD, as Figure 6 shown. Among them, NCM represents the pretreated NCM cathode powder, and roasting-700°C represents the powder after roasting the NCM and the recovered Si powder at a ratio of 1:1 by ball milling at 700°C.

[0096] It can be known from Figure 6It can be seen that the peaks before roasting are the corresponding XRD peaks of the original NCM. After reacting with the recycled crystalline silicon at 700 °C, it can be clearly found that the main characteristic peak at about 19 degrees disappears, that is, the NCM structure is destroyed, the peaks of NCM completely disappear, and it is in-situ transformed into Li2SiO3, and CoO, and oxygen-containing compounds such as Ni and Mn are generated. Similarly, lithium elements can be preferentially selectively leached, proving that this method is also applicable to NCM.

[0097] <Test Example 7>

[0098] The spent LiCoO2 cathode powder in Example 1 and the recycled Si were tested under argon conditions at a mixing ratio of 4:1 by a thermogravimetric analyzer (TG), as Figure 7 shown. Among them, LiCoO2 represents the pretreated LiCoO2 cathode powder, and LiCoO2+Si is the mixture of the pretreated LiCoO2 cathode powder and the recycled Si powder after ball milling.

[0099] From Figure 7 it can be seen that the mass loss of the spent LiCoO2 cathode powder during roasting at 100 °C to 900 °C is 6%, mainly the residual organic matter, while the mass loss of the mixture of the recycled Si powder and the LiCoO2 cathode powder during roasting at 100 °C to 900 °C is only 3%, which is also the loss of organic matter in the spent LiCoO2 cathode powder, that is, there is no mass loss during the roasting process.

[0100] The above embodiments are preferred cases of the present invention and are not used to limit the protection scope of the present invention.

Claims

1. A method for recycling metals in lithium-ion batteries using waste photovoltaic panels, characterized in that: The following steps are involved: Step S1, placing the crystalline silicon cell obtained by pre-treating the waste photovoltaic panel in a 2 mol / L HCl solution to remove Al, and then further placing it in a 2 mol / L HNO3 solution to remove Ag, filtering to obtain a flaky silicon wafer, and then converting the flaky wafer into a powder by mechanical stirring to obtain a crystalline silicon powder A; Step S2: soaking the positive electrode sheet removed from the waste battery in a NaOH solution to remove the aluminum foil, and then washing, filtering and drying the positive electrode sheet to obtain positive electrode powder B; Step S3, fully mixing the crystalline silicon powder A and the positive electrode powder B by ball milling at a mass ratio of 1:1 to 1:10, and then heating them at 400° C. to 800° C. in an inert atmosphere for a predetermined time to obtain a reacted powder; Step S4, adding water to the reacted powder at a mass ratio of 20 g / L, leaching at a predetermined temperature for a predetermined time under stirring conditions, and then filtering to obtain a Li2SiO3 solution and a Co-containing filter residue.

2. The method for recovering metals from lithium-ion batteries using waste photovoltaic panels according to claim 1, characterized in that: in, In step S4, the Co-containing filter residue is separated by wet magnetic separation to obtain CoO and Co.

3. The method for recovering metals from lithium-ion batteries using waste photovoltaic panels according to claim 1, characterized in that: in, In step S4, dilute H2SO4 with a mass concentration of 1 mol / L to 3 mol / L is added to the Co-containing filter residue to dissolve and obtain CoSO4.

4. The method for recovering metals from lithium-ion batteries using waste photovoltaic panels according to claim 1, characterized in that: in, In step S4, deionized water is added to the powder after the reaction, and the powder is leached at 30° C. to 60° C. for 5 min to 60 min by magnetic stirring, and then filtered to obtain the Li2SiO3 solution and the Co-containing filter residue.

5. The method for recovering metals from lithium-ion batteries using waste photovoltaic panels according to claim 1, characterized in that: in, In step S1, the crystalline silicon cell is placed in a 2 mol / L HCl solution at 40°C to 70°C to remove Al at a ratio of 100 g / L, and then further placed in a 2 mol / L HNO3 solution at 40°C to 70°C to remove Ag at a ratio of 100 g / L.

6. The method for recovering metals from lithium-ion batteries using waste photovoltaic panels according to claim 1, characterized in that: in, In step S1, the positive electrode sheet disassembled from the waste battery is soaked in a 5% NaOH solution for 30 minutes to remove the aluminum foil, and then rinsed and filtered with deionized water for multiple times, and dried to obtain the positive electrode powder B.

7. The method for recovering metals from lithium-ion batteries using waste photovoltaic panels according to claim 1, characterized in that: in, In step S4, the crystalline silicon powder A and the positive electrode powder B are ball-milled for 10 to 30 minutes at a mass ratio of 1:1 to 1:10 to be fully mixed, and then heated at 400° C. to 800° C. for 30 to 60 minutes in an inert atmosphere to obtain a reacted powder.

8. The method for recovering metals from lithium-ion batteries using waste photovoltaic panels according to claim 1, characterized in that: in, In step S1, the process of pre-treating the waste photovoltaic panels is specifically as follows: removing the waste photovoltaic panels, aluminum frames and copper wires, and then cutting the photovoltaic panels into small pieces of uniform size with a cutting tool, placing them in a muffle furnace and heating them at 500° C. for 1 hour to remove the EVA adhesive and TPT backplane, and obtaining the crystalline silicon cell sheets.

9. The method for recovering metals from lithium-ion batteries using waste photovoltaic panels according to claim 1, characterized in that: in, In step S2, the process of removing the positive electrode sheet from the waste battery is specifically as follows: immersing the battery in 5% sodium chloride for 24 hours to remove residual charge, then rinsing with deionized water and drying for 12 hours, and then manually disassembling the waste battery in a fume hood, soaking the obtained crude positive electrode sheet in ethanol for 1 hour, and washing with double distilled water to remove residual electrolyte, and then vacuum drying to obtain the positive electrode sheet.

10. The method for recovering metals from lithium-ion batteries using waste photovoltaic panels according to claim 9, characterized in that: in, The waste batteries are waste LiCoO2 batteries or waste NCM batteries.

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