KR-102961919-B1 - Method for removing and treating impurities in the recycling process of scrap cathode materials for lithium batteries

KR102961919B1KR 102961919 B1KR102961919 B1KR 102961919B1KR-102961919-B1

Abstract

The present disclosure discloses a method for removing and treating impurities in a recycling process of scrap cathode materials of lithium batteries. The method comprises the steps of: controlling the flow rates of a leaching solution of scrap cathode materials of lithium batteries and a first alkaline solution at a first temperature higher than room temperature and a constant first pH value to obtain a first filtrate by removing iron ions, aluminum ions and at least some copper ions by precipitation; controlling the flow rates of the first filtrate, a complexing agent, and a second alkaline solution within a range of a constant first pH and a second temperature higher than room temperature to obtain a target material precipitate by separating a second filtrate containing lithium ions from the first filtrate; dissolving the precipitate of the target material to obtain a first solution; and controlling the flow rates of the first solution and a fluorine-containing precipitating agent at a third temperature higher than room temperature and a constant concentration of fluoride ions to obtain a target solution by removing calcium ions, magnesium ions and at least some lead ions by precipitation. By the method of the present disclosure, a precipitate having a large particle size, high crystallinity, and low moisture content can be obtained, which facilitates washing and improves the recycling rate of nickel-cobalt-manganese from scrap cathode materials of lithium batteries.

Inventors

정, 조이 충-이엔
장, 지우쥔
다이, 린산
수이, 팡-치에
스, 이팡

Assignees

쓰추안 에너지 인터넷 리서치 인스티튜트 칭화 유니버시티

Dates

Publication Date: 20260507
Application Date: 20211108
Priority Date: 20201126

Claims (20)

As a method for removing impurities in the recycling process of scrap cathode materials of lithium batteries: A step of continuously pumping a leachate of scrap cathode materials of a lithium battery and a first alkaline solution into a first reactor to obtain a first filtrate by removing iron ions, aluminum ions and at least some copper ions, and controlling the flow rate and precipitation of the leachate of scrap cathode materials of the lithium battery and the first alkaline solution at a first temperature higher than room temperature and a constant first pH value; In order to remove lithium ions by separating a second filtrate containing lithium ions from the first filtrate and to obtain a precipitate of a target substance, the first filtrate, the complexing agent, and the second alkaline solution are continuously pumped to a second reactor, and the flow rates of the first filtrate, the complexing agent, and the second alkaline solution are controlled within a second temperature higher than room temperature and a constant first pH range; A step of dissolving a precipitate of the target substance to obtain a first solution; and To obtain a target solution by removing calcium ions, magnesium ions, and at least some lead ions, the first solution and the fluorine-containing precipitate are continuously pumped to a third reactor, and the method includes the step of controlling the flow rate and precipitation of the first solution and the fluorine-containing precipitate at a third temperature higher than room temperature and a constant concentration of fluorine ions. The above impurity removal method is performed in an overflow reactor capable of continuous operation, and A method for removing impurities characterized by measuring the hydrogen ion concentration (pH) value of the solution inside the first reactor in real time when pumping the first alkaline solution into the first reactor, and controlling the pumping speed of the first alkaline solution accordingly to keep the hydrogen ion concentration (pH) value of the solution inside the first reactor constant.
In claim 1, the leaching solution of scrap cathode materials of lithium batteries and the first alkaline solution are continuously pumped to a first reactor to obtain a first filtrate by removing iron ions, aluminum ions, and at least some copper ions by precipitation, and the step of controlling the flow rate of the leaching solution of scrap cathode materials of lithium batteries and the first alkaline solution at a first temperature higher than room temperature and a constant first pH value comprises: A method for removing impurities, comprising the steps of reacting for a first time period and then overflowing from the first reactor, followed by performing a first separation process and obtaining a precipitate containing iron ions, aluminum ions and at least some copper ions and the first filtrate; wherein the reaction is maintained to be carried out at the first temperature.
In claim 2, before performing the first separation process, the method is: A method for removing impurities, further comprising the step of aging a mixture overflowing from the first reactor for a second time period by maintaining the aging temperature at the first temperature.
In claim 1, in order to remove lithium ions by separating a second filtrate containing lithium ions from the first filtrate and to obtain a precipitate of a target substance, The first filtrate, the complexing agent, and the second alkaline solution are continuously pumped to a second reactor, and the step of controlling the flow rates of the first filtrate, the complexing agent, and the second alkaline solution within a second temperature higher than room temperature and a constant first pH range comprises: A method for removing impurities, comprising the steps of reacting for a third time period and then overflowing from the second reactor, followed by performing a second separation process and obtaining the second filtrate containing the target substance precipitate and lithium ions; wherein, during the third time period, the reaction is maintained to be carried out at the second temperature by controlling the flow rate of the second alkaline solution, and the reaction is also maintained to be carried out within the first pH range.
In claim 4, before performing the second separation process, the method is: A method for removing impurities, further comprising the step of aging a mixture overflowing from the second reactor for a fourth time period by maintaining the aging temperature at the second temperature.
In claim 1, the step of dissolving the precipitate of the target substance to obtain the first solution comprises: A step of adding a leaching agent to a precipitate of said target substance for dissolution until the pH reaches a third range in order to obtain a target substance-containing solution, wherein the leaching agent comprises at least a reducing agent, a first acid, and water; and A method for removing impurities comprising the step of adding a suitable amount of a fourth alkaline solution to the target substance-containing solution until the pH becomes within a fourth range in order to obtain the first solution.
In claim 1, in order to obtain a target solution by removing calcium ions, magnesium ions, and at least some lead ions by precipitation, the first solution and the fluorine-containing precipitate are continuously pumped to a third reactor, and the step of controlling the flow rate of the first solution and the fluorine-containing precipitate at a third temperature higher than room temperature and a constant concentration of fluorine ions comprises: A method for removing impurities, comprising the steps of: performing a third separation process to overflow from a third reactor after reacting for a fifth time period; and obtaining a target solution containing the precipitate containing calcium ions, magnesium and at least some lead ions; wherein, during the fifth time period, the reaction is maintained to be carried out at the third temperature, and by controlling the flow rate of the fluorine-containing precipitant, the fluorine ion concentration of the reactant in the third reactor is maintained within a first concentration range.
In claim 7, before performing the third separation process, the method is: A step of aging the mixture overflowing from the third reactor for a sixth time period by maintaining the aging temperature at the third temperature; and A method for removing impurities, further comprising the step of leaving the above-mentioned aged mixture for a seventh time period.
In any one of claims 1 to 8, before performing a precipitation treatment on the leaching solution of the scrap cathode material of the lithium battery, the method comprises: A method for removing impurities, further comprising the steps of adding a leaching agent to the scrap cathode material of a lithium battery to dissolve it until the pH reaches a second range, then performing a fourth separation process, and obtaining a third impurity of the scrap cathode material of the lithium battery and the leaching solution; wherein the leaching agent comprises at least a reducing agent, a first acid, and water.
In any one of claims 1 to 8, the method is: A method for removing impurities, further comprising the step of adding a third alkaline solution to the target solution to obtain a precursor precipitate.
A method for removing impurities according to any one of claims 1 to 8, wherein the first pH value is within the range of 5.5 to 6.7 or the first pH value is 10.5 to 11.8.
A method for removing impurities according to any one of claims 1 to 8, wherein the first temperature is within the range of 50℃ to 90℃, the second temperature is within the range of 40℃ to 70℃, or the third temperature is within the range of 50℃ to 90℃.
A method for removing impurities according to any one of claims 1 to 8, wherein the first alkaline solution comprises lithium hydroxide.
A method for removing impurities according to any one of claims 1 to 8, wherein the second alkaline solution comprises lithium hydroxide.
A method for removing impurities according to claim 6, wherein the third range is 0 to 4, or the fourth range is 4.5 to 6.5.
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Description

Method for removing and treating impurities in the recycling process of scrap cathode materials for lithium batteries This application claims priority to Chinese patent application No. 202011347197.8 filed on November 26, 2020, the entire contents of which are incorporated herein by reference. The present disclosure relates to the field of materials recycling technology, and in particular to a method for removing impurities and treating scrap cathode materials of lithium batteries in a recycling process. In the recycling process of scrap lithium battery cathode materials, the dissolved nickel-cobalt-manganese solution often contains various metallic impurities (e.g., Fe, Al, Cu, Ca, Mg, or Pb, etc.), and if these impurities are not removed, they will affect the quality and performance of the lithium battery cathode material synthesized after the scrap materials are recycled. In conventional technology, methods for removing metal impurities such as Fe, Al, Ca, Mg, etc. have the problem that it is difficult to filter and wash the precipitates. This results in unfilterable impurity precipitates remaining in the filtrate, causing the impurity precipitates to mix in subsequent stages, and ultimately leading to a high impurity content in the ternary precursor product. At the same time, because it is difficult to filter and wash the precipitates, the filtration process places high demands on the filtration equipment, requires more water for washing, and requires more time for filtration. Furthermore, some colloidal filter residues tend to have high liquid content and block the filter material, making washing impossible and making filtration and washing operations more difficult, which reduces the recycling rate of nickel, cobalt, and manganese metals and increases recycling costs. Furthermore, the co-precipitation process of precursors for ternary cathode materials (or ternary precursors) is a critical step in the manufacture of cathode materials for lithium batteries. The performance of the precursor product directly affects the performance of the cathode material. The equipment used for the co-precipitation of precursors is high-value equipment and is manufactured with precision. Improving the production efficiency of precursors is particularly important for the cost impact of the entire recycling process. In the general co-precipitation process of ternary precursors, online pH meters are used to ensure the quality of the precursors by precisely controlling pH values during the recycling process. FIG. 1 is a schematic flowchart of a method for removing impurities in a recycling process of scrap cathode material of a lithium battery according to some embodiments of the present disclosure. FIG. 2 is a schematic flowchart of a lithium ion recycling method in a scrap cathode material recycling process of a lithium battery according to some embodiments of the present disclosure. FIG. 3 is a schematic flowchart of a method for removing impurities in a scrap cathode material recycling process of a lithium battery according to some embodiments of the present disclosure. FIG. 4a is an SEM image of the filter residue according to Example 1 of the present disclosure. FIG. 4b is an SEM image of the filter residue according to Example 2 of the present disclosure. FIG. 5 is an XRD pattern of filter residue according to Examples 3 and 4 of the present disclosure. FIG. 6 is an SEM image of the filter residue according to Example 3 of the present disclosure. FIG. 7a is an SEM image of the filter residue according to Example 5 of the present disclosure. FIG. 7b is an SEM image of the filter residue according to Example 6 of the present disclosure. FIG. 8 is a schematic diagram of a method for removing and treating impurities according to some embodiments of the present disclosure. To more clearly explain the technical solutions in the embodiments of the present disclosure, the following is a brief introduction to the accompanying drawings necessary to describe the embodiments. By way of certainty, the accompanying drawings in the following description merely illustrate some examples or embodiments of the present disclosure, and those skilled in the art can apply the present disclosure to other similar scenarios without creative effort based on the accompanying drawings. Unless otherwise indicated or apparent in the linguistic context, the same reference numerals in the drawings indicate the same structure or operation. The terms “system,” “device,” “unit,” and/or “module” should be understood as being used in this specification as a method to distinguish different assemblies, elements, components, parts, or assemblies at different levels. Expressions used in this specification, such as “impurity removal method,” “processing method,” “impurity removal and processing method,” “lithium-ion recycling method,” or “impurity removal and processing method in the recycling process of scrap cathode materials of lithium batteries,” refer to