Method for recovering valuable metal from waste lithium ion battery positive electrode material

Abstract

The invention belongs to the technical field of battery waste recovery, and particularly discloses a method for recovering valuable metals from a positive electrode material of a waste lithium ion battery. The method provided by the invention comprises the following steps: mixing the positive electrode material of the waste lithium battery with potassium permanganate, potassium hydroxide and water, carrying out a leaching reaction, carrying out solid-liquid separation after the reaction is completed, adding potassium carbonate into filtrate to carry out a precipitation reaction, carrying out solid-liquid separation to obtain filtrate and lithium carbonate precipitate, adjusting the pH value of the filtrate to 6.5-7.5, and carrying out solid-liquid separation to obtain a potassium manganate solution. According to the method, the valuable metals in the positive electrode material of the waste lithium battery can be selectively recycled under the normal-pressure mild condition, and the chemical reagent is recycled by utilizing the disproportionation reaction, so that the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery waste recycling, in particular to a method for recovering valuable metals from waste lithium ion battery positive electrode materials. BACKGROUND

[0002] Lithium ion batteries (LIBs) have become the dominant technology for electric vehicle power systems due to their high energy density, safety, low cost, long cycle life, and excellent environmental adaptability. In recent years, with the rapid development of global electric vehicles and renewable energy storage systems, the demand for LIBs has grown exponentially. According to the International Energy Agency (IEA) statistics (https: / / www.iea.org / reports / global-ev-outlook-2024), global demand for power batteries exceeded 750 GWh in 2023, up 40% year-on-year. Specifically, China's demand was 415 GWh, Europe's demand was 185 GWh, and the United States' demand was about 100 GWh. This trend has led to a significant increase in demand for key metal raw materials such as lithium (Li), cobalt (Co), nickel (Ni), and manganese (Mn).

[0003] Currently, the main methods for recycling and utilizing waste lithium batteries include hydrometallurgy and pyrometallurgy. As traditional recycling methods, hydrometallurgy and pyrometallurgy are relatively mature in technology and have achieved certain scale of industrial application, but also have some significant drawbacks, such as the need to add a large amount of reagents and high production costs. How to realize the recycling of chemical reagents and the selective extraction of valuable metals is crucial.

[0004] Therefore, it is urgent to further improve the method for recycling waste lithium batteries to efficiently and selectively recover valuable metals therein with higher efficiency and lower cost. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a method for processing waste lithium secondary battery positive electrode materials, aiming to efficiently and selectively recover valuable metals from waste positive electrode materials. The present application uses potassium permanganate and potassium hydroxide as additives in a normal pressure environment, which can realize the selective extraction of manganese and lithium by using its centralizing reaction, and realize the recycling of chemical reagents by using its disproportionation reaction, thereby reducing production costs and improving the selectivity of valuable metal recovery.

[0006] The present application provides a method for recovering valuable metals from waste lithium battery positive electrode materials, comprising the following steps:

[0007] S1, mixing the waste lithium battery positive electrode material with potassium permanganate, potassium hydroxide and water, and leaching at a temperature of 70-85℃ for 0.5-5h, and after the reaction is completed, solid-liquid separation is performed to obtain a filtrate 1;

[0008] S2, adding potassium carbonate into the filtrate 1, and reacting at a temperature of 90-100℃ for 1-5h, and then solid-liquid separation to obtain filtrate 2 and lithium carbonate precipitate;

[0009] S3, adjusting the pH of the filtrate 2 to 6.5-7.5, and standing for 1-5h, and then solid-liquid separation to obtain a residue and a potassium manganate solution.

[0010] According to some embodiments of the present application, the method further comprises the following steps:

[0011] S4, adding potassium manganate into the potassium manganate solution to obtain a leaching agent, and mixing the leaching agent with the waste lithium battery cathode material in step S1, and then passing carbon dioxide gas to perform leaching reaction under the temperature and time conditions of step S1, and then performing reaction according to the conditions of steps S2 and S3 in sequence.

[0012] According to some embodiments of the present application, the amount of potassium manganate in the leaching agent is 1.1-1.5 times the amount of potassium permanganate and potassium hydroxide in step S1 according to the molar coefficient of the following disproportionation reaction formula:

[0013] 3K2MnO4 + 2CO2 → 2KMnO4 + MnO2 + 2K2CO3;

[0014] 2K2MnO4 + 2H2O → 2MnO2 + 4KOH + O2.

[0015] According to some embodiments of the present application, the method further comprises the following steps:

[0016] S5, recycling the waste lithium battery cathode material in step S4 for 2-6 times.

[0017] According to some embodiments of the present application, the waste lithium battery cathode material is a cathode material powder, which is obtained by disassembling a cathode sheet from a discharged waste nickel-cobalt-lithium manganate battery or a discharged waste lithium manganate battery, soaking the cathode sheet in an organic solvent, separating the current collector in the cathode sheet, and then filtering, washing with water, and drying the remaining material to obtain the cathode material powder.

[0018] In the present application, the content of the waste cathode material is not particularly limited, and considering the economy of the process, the content of the active material is preferably above 50wt.%, further preferably above 80wt.%, and more preferably 80-95wt.%.

[0019] According to some embodiments of the present application, the organic solvent comprises N-methyl pyrrolidone.

[0020] According to some embodiments of the present application, the mass ratio of the waste lithium battery positive electrode material to potassium permanganate in step S1 is 1: (1-5).

[0021] According to some preferred embodiments of the present application, the mass ratio of the waste lithium battery positive electrode material to potassium permanganate in step S1 is 1: (2-4).

[0022] According to some embodiments of the present application, the water is added in step S1 according to a liquid-solid mass ratio of (6-30): 1.

[0023] According to some preferred embodiments of the present application, the water is added in step S1 according to a liquid-solid mass ratio of (8-20): 1.

[0024] According to some embodiments of the present application, the concentration of potassium hydroxide in the reaction system in step S1 is 1-4 mol / L.

[0025] According to some preferred embodiments of the present application, the concentration of potassium hydroxide in the reaction system in step S1 is 1-3 mol / L.

[0026] The beneficial effects of the present application are as follows:

[0027] The present application develops a new method for selectively recovering valuable metals in waste lithium battery positive electrode materials. Potassium permanganate and potassium hydroxide are used as additives to leach the battery positive electrode material in a normal pressure environment, which can effectively destroy the crystal lattice structure of the waste positive electrode material, and can realize high selectivity and high recovery rate of manganese and lithium by using the disproportionation reaction, and can realize the recycling of chemical reagents by using the disproportionation reaction, thereby reducing the production cost and improving the selectivity of valuable metal recovery.

[0028] Other features and advantages of the present application will be described in the subsequent description, and some will become apparent from the description, or will be understood by those skilled in the art. DETAILED DESCRIPTION

[0029] The concept and technical effects of the present application will be described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0030] The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not marked with the manufacturer, which are conventional products that can be purchased on the market.

[0031] Example 1

[0032] This embodiment provides a method for recovering valuable metals from waste nickel-cobalt-manganese lithium-ion battery cathode materials. The specific steps are as follows:

[0033] 1) The waste nickel-cobalt-manganese lithium oxide batteries were placed in 2 mol / L salt water for 30 h discharge treatment. The discharged batteries were placed in a forced-air drying oven and dried at 85℃. The positive electrode and negative electrode were separated. The positive electrode was soaked in N-methylpyrrolidone. The current collector in the electrode was separated. The battery was filtered, washed with water and dried to obtain waste positive electrode material powder.

[0034] 2) Grind the waste cathode material powder with potassium permanganate and potassium hydroxide in a mortar until fully mixed, then place the mixture in a beaker and put it in a water bath. Add deionized water with a liquid-to-solid mass ratio of 10:1. The mass ratio of potassium permanganate to waste cathode material powder is 3:1, the concentration of potassium hydroxide is 2 mol / L, the stirring speed is set to 300 rpm, the reaction temperature is 80℃, and the reaction is continued for 1 hour.

[0035] 3) Filter the mixed solution from step 2) while it is still hot, and use atomic absorption spectroscopy to test the Li in the filtrate. + After concentration, Li was added to the filtered solution. + Add 0.51 times the amount of potassium carbonate and heat at 90℃ for 2 hours. Filter while hot to obtain lithium carbonate precipitate.

[0036] 4) Add an appropriate amount of weakly acidic water to the filtrate in step 3), monitor the pH of the solution in real time, adjust the pH to 7, let stand for 2 hours, and filter to obtain a potassium manganate solution and filter residue.

[0037] 5) Add an appropriate amount of potassium manganate to the potassium manganate solution filtered in step 4) to obtain a leaching agent, which is then added to the waste positive electrode material powder for a second round of leaching. The amount of potassium manganate in the leaching agent is 1.2 times the amount of potassium permanganate and potassium hydroxide used in step 2) according to the stoichiometric coefficients of the following disproportionation reaction equation (considering the reaction limit, an excess of reagent is added to participate in the reaction):

[0038] 3K2MnO4 + 2CO2 → 2KMnO4 + MnO2 + 2K2CO3;

[0039] 2K2MnO4 + 2H2O → 2MnO2 + 4KOH + O2;

[0040] During the second round of leaching, CO2 gas needs to be introduced into the intermediate reaction system;

[0041] 6) Repeat steps 3), 4), and 5) of the leaching reaction for a total of five rounds to obtain potassium carbonate precipitate and potassium manganate solution.

[0042] The leaching recovery rates of Ni, Co, Mn, and Li elements after the above five cycles of leaching were detected, as shown in Table 1:

[0043] Example 2

[0044] The present example provides a method for recovering valuable metals from waste lithium manganate battery positive electrode materials, and the specific steps are basically the same as those of Example 1, except that the waste lithium manganate battery is used to replace the waste lithium nickel cobalt manganate battery of Example 1.

[0045] After five cycles of leaching and precipitation reaction, the recovery rates of Mn and Li elements were detected, wherein the recovery rate of Mn in the first leaching reached 99.4%, the recovery rate of Li reached 99.6%, and other metals were basically not leached. The recovery rate of Mn in the second leaching reached 99.3%, the recovery rate of Li reached 99.5%, and other metals were basically not leached. After five cycles of leaching, the leaching rates of Mn and Li were both more than 98.8%.

[0046] Example 3

[0047] The present example provides a method for recovering valuable metals from waste lithium nickel cobalt manganate battery positive electrode materials, and the specific steps are basically the same as those of Example 1, except that the mass ratio of potassium permanganate to waste positive electrode material powder in step 2) of the present example is 3:1.

[0048] After five cycles of leaching and precipitation reaction, the recovery rates of Mn and Li elements were detected, wherein the recovery rate of Mn in the first leaching reached 99.4%, the recovery rate of Li reached 99.4%, and other metals were basically not leached. The recovery rate of Mn in the second leaching reached 99.1%, the recovery rate of Li reached 99.2%, and other metals were basically not leached. After five cycles of leaching, the leaching rates of Mn and Li were both more than 98.9%.

[0049] Comparative Example 1

[0050] The present comparative example provides a method for recovering valuable metals from waste lithium nickel cobalt manganate battery positive electrode materials, and the specific steps are basically the same as those of Example 1, except that no potassium hydroxide is added in step 2) of the present comparative example.

[0051] After leaching and precipitation reaction, it was calculated that the leaching rate of Mn was only 28.7%, and the leaching rate of Li was only 43.7%. Analysis showed that the reason for the low leaching recovery rate was that the reaction 3KMnO4 + MnO2 + 4KOH→ 3K2MnO4 + 2H2O could not occur due to the lack of alkaline environment, which could not destroy the stable manganese dioxide skeleton of the ternary material, resulting in the escape of Li.

[0052] Comparative Example 2

[0053] This comparative example provides a method for recovering valuable metals from the positive electrode material of a waste nickel-cobalt-manganese lithium battery, and the specific steps are basically the same as those of Example 1, except that the temperature of the leaching reaction in step 2) of this comparative example is room temperature.

[0054] After leaching and precipitation reactions, it is calculated that the leaching rate of Mn is only 58.2%, and the leaching rate of Li is only 72.7%. Analysis shows that the reason for this phenomenon is that temperature can increase the activation energy of the reactants, thereby reducing the energy barrier for the reaction to occur. At room temperature, the driving force of the reaction 3KMnO4 + MnO2 + 4KOH → 3K2MnO4 + 2H2O is not enough, resulting in incomplete reaction.

[0055] Comparative Example 3

[0056] This comparative example provides a method for recovering valuable metals from the positive electrode material of a waste nickel-cobalt-manganese lithium battery, and the specific steps are basically the same as those of Example 1, except that potassium permanganate is used instead of potassium permanganate in step 2) of this comparative example.

[0057] After leaching and precipitation reactions, it is calculated that the leaching rate of Mn and Li is less than 10%. Analysis shows that the reason for this phenomenon is that the reaction 3KMnO4 + MnO2 + 4KOH → 3K2MnO4 + 2H2O requires a strong oxidizing agent, potassium permanganate, to occur completely.

[0058] Comparative Example 4

[0059] This comparative example provides a method for recovering valuable metals from the positive electrode material of a waste nickel-cobalt-manganese lithium battery, and the specific steps are basically the same as those of Example 1, except that the concentration of potassium hydroxide in step 2) of this comparative example is 8 mol / L.

[0060] After leaching and precipitation reactions, it is found that Co is also leached, with a leaching rate of 23%, thus reducing the selectivity of the method for recovering valuable metals from the positive electrode material. Analysis shows that Co is in a higher oxidation state, and after the reaction 3KMnO4 + MnO2 + 4KOH → 3K2MnO4 + 2H2O occurs completely, it will continue to react with a small amount of Co oxide, reducing the selectivity of Mn and Li, resulting in a decrease in product purity.

[0061] Comparative Example 5

[0062] This comparative example provides a method for recovering valuable metals from the positive electrode material of a waste nickel-cobalt-manganese lithium battery, and the specific steps are basically the same as those of Example 1, except that the concentration of potassium hydroxide in step 2) of this comparative example is 5 mol / L.

[0063] After leaching and precipitation reaction, it is found that Co can also be leached, and the leaching rate is calculated to be 12%, and this method also reduces the selectivity of recovering valuable metals from the positive electrode material.

[0064] The above has made a detailed description on the embodiments of the present application, but the present application is not limited to the above-mentioned embodiments, and various changes can be made within the knowledge range possessed by those skilled in the art without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for recovering valuable metals from spent lithium battery cathode material, characterized in that, The method comprises the following steps: S1, mixing the waste lithium battery positive material with potassium permanganate, potassium hydroxide and water, leaching at 70-85℃ for 0.5-5h, and then separating the solid and liquid to obtain filtrate 1; S2, adding potassium carbonate to the filtrate 1 and reacting at 90-100℃ for 1-5h, and then separating the solid and liquid to obtain filtrate 2 and lithium carbonate precipitate; S3, adjusting the pH of the filtrate 2 to 6.5-7.5, and then standing for 1-5h, and then separating the solid and liquid to obtain filter residue and potassium manganate solution.

2. The method of claim 1, wherein, The method further comprises the following steps: S4, adding potassium permanganate to the potassium manganate solution to obtain a leaching agent, mixing the leaching agent with the waste lithium battery positive material in step S1, and then passing carbon dioxide gas to perform leaching reaction under the temperature and time conditions of step S1, and then sequentially performing reactions according to the conditions of steps S2 and S3.

3. The method of claim 2, wherein, The method further comprises the following steps: S5, recycling the waste lithium battery positive material in step S4 for 2-6 times.

4. The method according to any one of claims 1 to 3, characterized in that, The waste lithium battery positive material is a positive material powder, which is obtained by disassembling the positive pole piece from a discharged waste nickel-cobalt-lithium manganate battery or a discharged waste lithium manganate battery, soaking the positive pole piece in an organic solvent, separating the current collector in the positive pole piece, and then filtering, washing and drying the remaining material to obtain the positive material powder.

5. The method according to any one of claims 1 to 3, characterized in that, The mass ratio of the waste lithium battery positive material to potassium permanganate in step S1 is 1:(1-5).

6. The method according to any one of claims 1 to 3, characterized in that, The water in step S1 is added in an amount of (6-30):1 of liquid to solid mass ratio.

7. The method of any one of claims 1-3, wherein, The concentration of potassium hydroxide in the reaction system in step S1 is 1-4 mol / L.

8. The method of claim 4, wherein, The organic solvent comprises N-methyl pyrrolidone.

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