Method for recycling and selectively extracting metals from electrolyte of retired lithium battery

Abstract

The application discloses a kind of retired lithium battery electrolyte recycling and metal selective extraction method, it is related to the field of retired lithium battery comprehensive recycling, specifically: after retired lithium battery is sheared and broken after discharging, low-temperature evaporation is carried out under inert gas protection, electrolyte escaped in evaporation process is first absorbed by calcium oxide solution phosphorus, fluorine, then carbonic acid solution is added to absorption liquid to carry out neutralization treatment, after filtration separation, the aqueous solution of electrolyte is obtained.Lithium-rich solution and leaching residue are obtained after the positive electrode material obtained from the retired lithium battery after low-temperature evaporation treatment is immersed in the aqueous solution of electrolyte and filtered.The application uses retired lithium battery electrolyte as leaching solvent to selectively extract lithium element in positive electrode material, and the electrolyte in leaching solvent can be recycled, which avoids the harm of electrolyte components in retired lithium battery to the environment, and is suitable for treating various retired lithium batteries such as nickel-cobalt-manganese lithium, nickel-cobalt-aluminum lithium, lithium cobaltate and lithium manganate, and has strong applicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of comprehensive recycling of retired lithium batteries, in particular to a method for recycling electrolyte of retired lithium batteries and selectively extracting metals. BACKGROUND

[0002] Lithium batteries have the advantages of high energy density, long service life, environmental friendliness, etc., and are the most promising new energy to replace traditional energy. At present, lithium ion batteries have been widely used in new energy vehicles, energy storage, medical treatment and other fields, especially the power batteries of new energy vehicles have developed rapidly. However, the service life of lithium ion batteries is about 3-5 years, and a large number of retired lithium batteries have been generated. Lithium batteries contain not only strategic metal resources such as lithium and cobalt, but also harmful components such as lithium hexafluorophosphate and organic electrolyte solvents. Recycling of retired lithium batteries is beneficial to environmental protection and resource conservation.

[0003] The weight ratio of electrolyte in lithium battery is more than 10%, and the electrolyte in retired lithium battery is difficult to recycle because the composition of electrolyte changes during the operation of the battery. The existing electrolyte treatment technology mainly includes wet process and heat treatment. The wet process mainly transfers the electrolyte to liquid by crushing, cleaning and other steps, and then recovers lithium elements in the electrolyte by precipitation, and the remaining waste liquid is further disposed of. The heat treatment process is to directly pyrolyze or incinerate the retired lithium battery. The pyrolysis process consists of pyrolysis, condensation collection, tail gas treatment and other steps. The incineration process consists of incineration, tail gas treatment and other steps. Whether it is wet process or heat treatment, the current treatment method of electrolyte in retired lithium battery has problems such as release of dioxin, complex harmless disposal process and resource waste.

[0004] At present, the main method for recovering lithium from the positive electrode material of retired lithium battery is acid leaching process. The basic process is to dissolve the positive electrode material of retired lithium battery in inorganic acid, and then adjust the leaching solution to alkaline to form a precipitate of lithium ions in the leaching solution. However, in addition to lithium elements, the positive electrode material of retired lithium battery also contains nickel, cobalt, manganese, aluminum and other elements, and because the selectivity of inorganic acid leaching is weak, the nickel, cobalt, manganese and aluminum metals in the positive electrode material will be leached out at the same time. Therefore, before the recovery of lithium ions in the leaching solution, complex processes such as impurity removal and multi-stage extraction are needed to separate the nickel, cobalt, manganese and aluminum ions, resulting in complex recovery process and low lithium recovery rate. SUMMARY

[0005] The present application aims to at least solve one of the problems in the prior art, and provides a method for recycling electrolyte of retired lithium batteries and selectively extracting metals.

[0006] The technical solution of the present application is as follows:

[0007] The application discloses a method for recycling and selectively extracting metals from electrolyte of retired lithium battery.

[0008] As a preferred scheme of the application, the retired lithium battery is any one or a combination of at least two of lithium nickel cobalt manganese oxide ternary battery, lithium nickel cobalt aluminate battery, lithium manganate battery or lithium cobaltate battery.

[0009] As a preferred scheme of the application, the evaporation temperature is 105-165 DEG C, and the evaporation time is 0.5-3h.

[0010] As a preferred scheme of the application, the positive electrode material is any one or a combination of at least two of lithium nickel cobalt manganese oxide ternary positive electrode material, lithium nickel cobalt aluminate positive electrode material, lithium manganate positive electrode material or lithium cobaltate positive electrode material.

[0011] As a preferred scheme of the application, the method for obtaining the positive electrode material is specifically as follows: the retired lithium battery after low-temperature evaporation treatment is disassembled to collect positive electrode sheets, and the positive electrode sheets are crushed and sorted to obtain the positive electrode material.

[0012] As a preferred scheme of the application, the leaching condition is that the electrolyte concentration in the aqueous solution is 10-70wt%.

[0013] As a preferred scheme of the application, the leaching condition is that the solid-liquid ratio of the positive electrode material to the aqueous electrolyte solution is 5-125g / L.

[0014] As a preferred scheme of the application, the leaching condition is that the leaching temperature is 160-270 DEG C, and the leaching time is 3-10h.

[0015] The application can realize harmless conversion of electrolyte and metal leaching from positive electrode material in one step by putting the positive electrode material into the subcritical aqueous solution of electrolyte based on the principle that organic matters (carbonate solvents, organic additives, etc.) in the electrolyte are first converted into weak acid and carbonate and then into harmless substances (carbon dioxide, water, etc.) in the subcritical water system.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] (1) The method for recycling and selectively extracting metals from the electrolyte of a retired lithium battery can safely and environmentally recycle the electrolyte of a retired lithium battery, and at the same time, the recycled electrolyte is used for selectively extracting lithium from the positive electrode material, thereby realizing efficient utilization of the electrolyte.

[0018] (2) The method for recycling and selectively extracting metals from the electrolyte of a retired lithium battery can process different types of retired lithium batteries, and the method for selectively recycling lithium from the positive electrode material of a retired lithium battery has the advantages of short process, easy industrial process implementation, and strong technical applicability.

[0019] (3) The method for recycling and selectively extracting metals from the electrolyte of a retired lithium battery has a high extraction rate of lithium (more than 97%) and a low impurity content (the leaching rate of metal elements such as nickel, cobalt, manganese, and aluminum in the positive electrode material is less than 0.5%), and the lithium-rich solution obtained by the method is easy to prepare battery-grade lithium carbonate.

[0020] (4) The method for recycling and selectively extracting metals from the electrolyte of a retired lithium battery provides a method for selectively recycling lithium from the positive electrode material using the recycled electrolyte as the leaching medium, which is clean in process, has no wastewater and waste gas emissions, and the lithium ions in the leaching solution can be precipitated and recycled, the leaching medium can be recycled, and the environmental hazards of the electrolyte components in the retired lithium battery are avoided. DETAILED DESCRIPTION

[0021] A method for recycling and selectively extracting metals from the electrolyte of a retired lithium battery, comprising the following steps:

[0022] Step 1: After the retired lithium battery is cut and broken after discharging, low-temperature evaporation is carried out under the protection of inert gas, the gas substances escaped during the evaporation process are absorbed by the calcium oxide solution, phosphorus and fluorine are added to the absorption liquid, and the electrolyte aqueous solution is obtained after neutralization treatment and filtration separation, the obtained electrolyte aqueous solution is used as a selective extraction solvent for lithium in the positive electrode material; the retired lithium battery after low-temperature evaporation treatment is disassembled to collect the positive electrode sheet, and the positive electrode material is obtained by breaking and sorting.

[0023] Step 2: The positive electrode material obtained in step 1 is put into the obtained aqueous solution for leaching, and a lithium-rich solution and leaching residue are obtained after filtration.

[0024] As a preferred technical solution of the present application, the retired lithium battery in step 1 is any one or a combination of at least two of the following: nickel-cobalt-manganese lithium ternary battery, nickel-cobalt-aluminum lithium battery, lithium manganese battery, or lithium cobalt battery.

[0025] As a preferred technical solution of the present application, the evaporation temperature in step 1 is 105-165℃, for example 105℃, 115℃, 130℃, 145℃ or 165℃, but not limited to the listed values, other values not listed in the range are also applicable, preferably 110-160℃.

[0026] As a preferred technical solution of the present application, the evaporation time in step 1 is 0.5-3h, for example 0.5h, 1h, 2h, 2.5h or 3h, but not limited to the listed values, other values not listed in the range are also applicable, preferably 1-2.5h.

[0027] As a preferred technical solution of the present application, the retired lithium battery positive electrode material in step 1 is any one or a combination of at least two of lithium nickel cobalt manganese oxide ternary material, lithium nickel cobalt aluminum oxide ternary material, lithium manganese oxide material or lithium cobalt oxide material.

[0028] As a preferred technical solution of the present application, the leaching temperature in step 2 is 160-270℃, for example 160℃, 180℃, 210℃, 230℃ or 270℃, but not limited to the listed values, other values not listed in the range are also applicable, preferably 170-260℃.

[0029] As a preferred technical solution of the present application, the leaching time in step 2 is 3-10h, for example 3h, 5h, 7h, 9h or 10h, but not limited to the listed values, other values not listed in the range are also applicable, preferably 4-10h.

[0030] As a preferred technical solution of the present application, the electrolyte concentration in the aqueous solution of electrolyte in the leaching process in step 2 is 10-70wt%, for example 10wt%, 25wt%, 35wt%, 50wt%, 60wt% or 70wt%, but not limited to the listed values, other values not listed in the range are also applicable, preferably 15-65wt%.

[0031] As a preferred technical solution of the present application, the solid-liquid ratio of the positive electrode material to the aqueous solution of electrolyte in the leaching process in step 2 is 5-125g / L, for example 5g / L, 25g / L, 40g / L, 80g / L, 100g / L, 125g / L, but not limited to the listed values, other values not listed in the range are also applicable, preferably 10-100g / L.

[0032] The technical solutions of the present application are further described in the following specific examples.

[0033] It should be noted that the calculation formula of the leaching rate involved below is as follows:

[0034] Leaching rate calculation formula = (concentration of certain element in leaching solution x volume of leaching solution) / total mass of certain element in raw material.

[0035] Example 1

[0036] After the retired lithium nickel cobalt manganese oxide battery after discharge was sheared and broken, it was low-temperature evaporated at 110°C for 2.5h under nitrogen protection. The gas substances escaped during the evaporation process were absorbed by a 20wt% calcium oxide solution to remove phosphorus and fluorine. A 15wt% carbonic acid solution was added to the absorption liquid for neutralization treatment, and then the electrolyte aqueous solution was obtained by filtration separation. The electrolyte concentration of the obtained aqueous solution was diluted to 15wt%, which was used as a selective extraction solvent for lithium in the positive electrode material. The positive electrode sheet was collected by disassembling the low-temperature evaporated retired lithium battery, and the positive electrode material was obtained by breaking and sorting. The obtained positive electrode material was put into the obtained electrolyte 15wt% aqueous solution at a solid-liquid ratio of 10g / L, and was leached at a temperature of 170°C for 10h. After filtration, a lithium-rich solution and a leaching residue were obtained. It was detected and calculated that the leaching rate of lithium element in this example was 98.3%, and the leaching rates of nickel, cobalt and manganese were 0.15%, 0.02% and 0.18% respectively.

[0037] Example 2

[0038] After the retired lithium nickel cobalt manganese oxide battery after discharge was sheared and broken, it was low-temperature evaporated at 160°C for 1h under nitrogen protection. The gas substances escaped during the evaporation process were absorbed by a 20wt% calcium oxide solution to remove phosphorus and fluorine. A 15wt% carbonic acid solution was added to the absorption liquid for neutralization treatment, and then the electrolyte aqueous solution was obtained by filtration separation. The electrolyte concentration of the obtained aqueous solution was diluted to 65wt%, which was used as a selective extraction solvent for lithium in the positive electrode material. The positive electrode sheet was collected by disassembling the low-temperature evaporated retired lithium battery, and the positive electrode material was obtained by breaking and sorting. The obtained positive electrode material was put into the obtained electrolyte 65wt% aqueous solution at a solid-liquid ratio of 100g / L, and was leached at a temperature of 260°C for 4h. After filtration, a lithium-rich solution and a leaching residue were obtained. It was detected and calculated that the leaching rate of lithium element in this example was 97.5%, and the leaching rates of nickel, cobalt and manganese were 0.17%, 0.05% and 0.21% respectively.

[0039] Example 3

[0040] The retired lithium battery after low-temperature evaporation treatment is disassembled to collect the positive plate, and the positive material is obtained by crushing and sorting. The obtained positive material is put into the obtained electrolyte 50wt% aqueous solution according to the solid-liquid ratio of 40g / L, and is leached at a temperature of 200℃ for 5h. After filtration, a lithium-rich solution and a leaching residue are obtained. It is detected and calculated that the leaching rate of lithium element obtained in the embodiment is 98.9%, and the leaching rates of nickel, cobalt and manganese are 0.13%, 0.01% and 0.16% respectively.

[0041] Example 4

[0042] The retired lithium battery after low-temperature evaporation treatment is disassembled to collect the positive plate, and the positive material is obtained by crushing and sorting. The obtained positive material is put into the obtained electrolyte 50wt% aqueous solution according to the solid-liquid ratio of 40g / L, and is leached at a temperature of 200℃ for 5h. After filtration, a lithium-rich solution and a leaching residue are obtained. It is detected and calculated that the leaching rate of lithium element obtained in the embodiment is 98.9%, and the leaching rates of nickel, cobalt and manganese are 0.13%, 0.01% and 0.16% respectively.

[0043] Example 5

[0044] The retired lithium cobalt oxide battery after discharge is sheared and broken, and then evaporated at 130 DEG C for 2.0 hours under the protection of inert gas. The gas material escaped in the evaporation process is absorbed by 20wt% calcium oxide solution to remove phosphorus and fluorine. A 15wt% carbonic acid solution is added to the absorption liquid for neutralization treatment. The electrolyte aqueous solution is obtained by filtration separation. The electrolyte concentration in the obtained aqueous solution is diluted to 35wt%, which is used as a selective extraction solvent of lithium in the positive electrode material. The positive electrode material is obtained by disassembling and collecting the positive electrode sheet of the retired lithium battery after low-temperature evaporation treatment and breaking and sorting. The obtained positive electrode material is put into the obtained electrolyte aqueous solution with 35wt% according to a solid-liquid ratio of 30g / L, and then leached at 190 DEG C for 8 hours. The lithium-rich solution and leaching residue are obtained by filtration. It is detected and calculated that the leaching rate of lithium element in the embodiment is 99.1%, and the leaching rate of cobalt is 0.13%.

[0045] Embodiment 6

[0046] The retired lithium cobalt oxide battery after discharge is sheared and broken, and then evaporated at 130 DEG C for 2.0 hours under the protection of inert gas. The gas material escaped in the evaporation process is absorbed by 20wt% calcium oxide solution to remove phosphorus and fluorine. A 15wt% carbonic acid solution is added to the absorption liquid for neutralization treatment. The electrolyte aqueous solution is obtained by filtration separation. The electrolyte concentration in the obtained aqueous solution is diluted to 35wt%, which is used as a selective extraction solvent of lithium in the positive electrode material. The positive electrode material is obtained by disassembling and collecting the positive electrode sheet of the retired lithium battery after low-temperature evaporation treatment and breaking and sorting. The obtained positive electrode material is put into the obtained electrolyte aqueous solution with 35wt% according to a solid-liquid ratio of 30g / L, and then leached at 190 DEG C for 8 hours. The lithium-rich solution and leaching residue are obtained by filtration. It is detected and calculated that the leaching rate of lithium element in the embodiment is 99.1%, and the leaching rate of cobalt is 0.13%.

[0047] As can be seen from the above, the extraction rate of lithium in the embodiments is high, and is greater than 97%. The leaching rate of metal elements such as nickel, cobalt, manganese and / or aluminum in the positive electrode material is less than 0.5%, which indicates that the impurities are low. The lithium-rich solution obtained by the present application is easier to prepare battery-grade lithium carbonate.

[0048] The present application uses the recovered electrolyte as the leaching medium to selectively recover lithium in the positive electrode material. The process is clean, and there is no waste water and waste gas emission. The lithium ions in the leaching solution can be precipitated and recovered, and the leaching medium can be recycled, thereby avoiding the environmental hazards of electrolyte components in the retired lithium battery.

[0049] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for recycling and selectively extracting metals from retired lithium battery electrolyte, characterized in that, The retired lithium battery after discharge is cut and broken, and then low-temperature evaporation is carried out under inert gas protection. The gas substances escaped in the evaporation process are absorbed by a calcium oxide solution to remove phosphorus and fluorine. After adding a carbonic acid solution to the absorption liquid for neutralization treatment, the water solution of electrolyte is obtained by filtration separation. The positive electrode material obtained from the retired lithium battery after low-temperature evaporation treatment is immersed in the water solution of electrolyte obtained by filtration separation, and then a lithium-rich solution and an immersion residue are obtained by filtration. The concentration of the electrolyte in the water solution is 10-70wt%; The solid-liquid ratio of the positive electrode material to the water solution of electrolyte is 5-125g / L; The immersion temperature is 160-270℃, and the immersion time is 3-10h.

2. The method for recycling and selectively extracting metals from the electrolyte of decommissioned lithium batteries according to claim 1, characterized in that, The retired lithium battery is any one or a combination of at least two of a nickel-cobalt-manganese lithium ternary battery, a nickel-cobalt-aluminum lithium battery, a lithium manganate battery or a lithium cobaltate battery.

3. The method for recycling and selectively extracting metals from the electrolyte of decommissioned lithium batteries according to claim 1, characterized in that, The evaporation temperature is 105-165℃, and the evaporation time is 0.5-3h.

4. The method for recycling and selectively extracting metals from the electrolyte of decommissioned lithium batteries according to claim 1, characterized in that, The positive electrode material is any one or a combination of at least two of a nickel-cobalt-manganese lithium ternary positive electrode material, a nickel-cobalt-aluminum lithium positive electrode material, a lithium manganate positive electrode material or a lithium cobaltate positive electrode material.

5. The method for recycling and selectively extracting metals from the electrolyte of decommissioned lithium batteries according to claim 1, characterized in that, The positive electrode material is obtained by disassembling and collecting the positive electrode sheet from the retired lithium battery after low-temperature evaporation treatment, breaking and sorting the positive electrode sheet, and then obtaining the positive electrode material.