Combined leaching agent and application thereof in leaching of positive electrode material of waste lithium ion battery

Abstract

The invention belongs to the field of waste battery positive electrode recovery, and particularly relates to a combined leaching agent which comprises a formula 1 # imgabs 0 # component and a formula 2 # imgabs 1 # catalyst. The invention also comprises application of the combined leaching agent in recovery of the positive electrode material of the waste battery. The combined leaching agent disclosed by the invention can synergistically improve the leaching effect and selectivity, and is beneficial to improving the electrochemical performance of a regenerated material of a leaching solution.

Description

Technical Field

[0001] The invention belongs to the field of battery waste recycling, and specifically relates to the field of waste lithium battery material recycling. Background Art

[0002] Lithium-ion batteries are widely used in mobile electronic devices and electric vehicles due to their high energy density, good cycle performance and low memory effect. As the battery's service life increases, the performance of the positive electrode material of the battery gradually declines until it is retired. Retired positive electrode materials contain a large amount of valuable metals. Recovering valuable metals from them helps to achieve metal recycling.

[0003] Acid leaching is a commonly used method for recovering valuable elements from waste positive electrode materials. For example, Chinese patent document with publication number CN116495787A discloses an acid leaching method, which specifically records that an acid solution and hydrogen peroxide are used to acid-leach the positive electrode active material after heat treatment to obtain a positive electrode leaching solution; the acid solution is, for example, a sulfuric acid solution. For another example, Chinese patent document with publication number CN113300019A discloses a step of dissolving and leaching the positive electrode powder using an acid leaching agent, wherein the acid leaching agent is a mixture of one or more of hydrochloric acid, sulfuric acid, and nitric acid.

[0004] In summary, the existing acid leaching method is a relatively common leaching method, and with the continuous evolution of technology, it can also achieve good technical results. However, the existing leaching stage is prone to produce three difficult-to-treat wastes. In addition, it is also difficult to optimize the leaching behavior of impurities in the leaching stage. Summary of the invention

[0005] In view of the problems faced by the existing recycling of waste lithium-ion battery positive electrodes, the present invention aims to provide a combined leaching agent to achieve efficient, mild and selective leaching of valuable metal elements in waste lithium-ion battery positive electrode materials.

[0006] The second object of the present invention is to provide a method for leaching valuable elements from waste lithium-ion battery positive electrode materials using the combined leaching agent, aiming to improve the efficient, mild and selective leaching effect of valuable metal elements in waste positive electrode materials.

[0007] In order to simplify the leaching process of waste lithium-ion batteries, many processes will crush the waste lithium-ion batteries with shells, which can reduce the disassembly process, but will also add more iron impurities to the waste positive electrode materials. The addition of more iron components is easy to accompany the leaching in the acid leaching stage, which is easy to interfere with the acid leaching of valuable elements in the positive electrode material, affecting the quality of the leachate and the subsequent regeneration electrochemical performance. In view of this problem, the present invention has been studied in depth and provides the following improvement scheme:

[0008] A combined leaching agent comprising a component of formula 1 and a catalyst of formula 2;

[0009]

[0010] The present invention shows that the combined use of Formula 1 and Formula 2 for the leaching of waste positive electrode materials can improve the mild and efficient leaching of valuable metal elements in waste lithium-ion battery positive electrode materials based on the combined synergy of the structures of the two, especially for shelled and crushed iron-containing waste positive electrode materials, which can achieve high selective leaching of iron and valuable elements in the positive electrode materials during the leaching stage.

[0011] In the present invention, in the combined leaching agent, the molar ratio of the component of formula 1 to the catalyst of formula 2 is 1-3:0.005-0.05; further 2-2.5:0.01-0.02.

[0012] The present invention also provides a method for leaching valuable elements from waste lithium-ion battery positive electrode materials. The combined leaching agent of the present invention is dispersed with water to obtain a leaching agent, which is then mixed with waste positive electrode materials recovered from waste lithium-ion batteries for leaching treatment, followed by solid-liquid separation to obtain a leachate enriched with valuable elements in the waste positive electrode materials.

[0013] The present invention is applicable to the leaching and recovery of valuable metals of any waste positive electrode materials in the industry, but considering the advantages of the technical solution, the waste positive electrode materials described in the present invention are particularly suitable for components containing iron and waste positive electrode active materials. In the present invention, for the treatment of the waste positive electrode materials containing iron, it can achieve efficient selective separation of iron and valuable metals in the waste positive electrode materials in the leaching stage, which can simplify the crushing behavior of waste lithium-ion batteries. In addition, it can also reduce the selective separation process of iron and valuable elements in the leachate.

[0014] In the present invention, the content of the waste positive electrode material in the waste positive electrode active material is above 50wt.%, and considering the value of the process, its content can be further above 80wt.%, and further 80-95wt.%; the iron content therein is below 5wt.%, and can further be 0.5-5wt.%, in order to further reduce the restriction on the iron content of the raw material, its range can be further relaxed to 2-4wt.%.

[0015] In the present invention, the waste positive electrode material is also allowed to contain at least one of a binder, a conductive agent, a negative electrode material, an electrolyte, and a current collector.

[0016] In the present invention, the waste positive electrode material can be the waste positive electrode material obtained by crushing and separating the waste lithium-ion battery shells.

[0017] In the present invention, the valuable elements in the waste positive electrode material can be at least one of lithium, nickel, cobalt and manganese. For example, when the waste battery is a waste NCM battery, the valuable elements therein can be lithium, nickel, cobalt and manganese. The valuable elements in the waste cobalt oxide lithium battery can be lithium and cobalt. The valuable elements in the waste nickel oxide lithium battery can be lithium and nickel. The valuable elements in the waste manganese oxide lithium battery can be lithium and manganese.

[0018] In the present invention, in the leaching agent, the concentration of Formula 1 is 1 to 3M, and can further be 2 to 2.5M.

[0019] In the present invention, the leaching agent can be stirred and aged at a temperature of 40 to 45° C. before leaching. The present invention shows that the aging treatment can strengthen the interaction between Formula 1 and Formula 2 to a certain extent, and can further strengthen the leaching effect and the leaching selectivity of iron and valuable metals.

[0020] Preferably, there is no particular requirement for the aging time. Considering the processing efficiency, it can be 20 to 60 minutes, and further can be 25 to 45 minutes.

[0021] In the present invention, the liquid-to-solid ratio in the leaching stage is 10 to 50 mL / g, further 10 to 25 mL / g, and further 15 to 20 mL / g.

[0022] In the present invention, the temperature in the leaching stage is 15 to 80°C, preferably 20 to 45°C, and further can be 20 to 40°C.

[0023] In the present invention, the leaching time is 0.5 h or longer, preferably 1 to 4 h, and further preferably 1 to 2 h.

[0024] Beneficial Effects

[0025] The present invention combines Formula 1 and Formula 2 for the recovery and treatment of waste positive electrode materials, which can achieve synergy and improve the gentle and efficient leaching of valuable metal elements in waste lithium-ion battery positive electrode materials, especially for shelled and crushed iron-containing waste positive electrode materials, which can achieve high selective leaching of iron and valuable elements in the positive electrode materials during the leaching stage. DETAILED DESCRIPTION

[0026] The waste lithium-ion battery positive electrode material can be recovered by conventional means, but in order to further highlight the advantages of the technical solution of the present invention, the waste lithium-ion battery materials used in the following cases are all materials containing waste positive electrode active materials and iron obtained by directly crushing and recovering waste lithium-ion batteries with shells, wherein the presence of unavoidable binders, conductive agents and other components is also allowed. There is no special requirement for the content of waste positive electrode active materials. Considering the economic efficiency of the process, its content is preferably above 50wt.%. In the following cases, unless otherwise stated, its active content is 85-90wt.%, and the iron content is 2-3wt.%.

[0027] Example 1

[0028] Waste positive electrode materials are materials separated from waste nickel-cobalt-manganese ternary materials, in which the valuable metal elements include lithium, nickel, manganese and cobalt. The leaching steps are:

[0029] Formula 1 and Formula 2 are dissolved in water at room temperature to obtain a leaching agent containing 2M of Formula 1 compound and 0.018M of Formula 2; the waste positive electrode material and the leaching agent are mixed and processed in and out, wherein the liquid-solid ratio in the leaching stage is 20mL / g, the temperature in the leaching stage is 40°C, and the leaching time is 2h; after the leaching is completed, solid-liquid separation is performed to obtain a leaching solution enriched with lithium, nickel, cobalt and manganese. Tests have found that the metal leaching rates are Ni99.2%, Co99.3%, Mn99.5%, and Li99.7%. The iron content in the leaching solution is 2.1mg / L.

[0030] Example 2

[0031] Compared with Example 1, the only difference is that the waste positive electrode material is a material recovered from waste lithium cobalt oxide batteries, and the valuable elements therein include lithium and cobalt; other operations and parameters are the same as in Example 1.

[0032] The test found that the leaching rates of valuable metals were Co99.3%, Li99.5%, and the iron content in the leachate was 2.5 mg / L.

[0033] Example 3

[0034] Compared with Example 1, the only difference is that the waste positive electrode material is a material recovered from waste lithium manganese oxide batteries, and the valuable elements therein include lithium and manganese; other operations and parameters are the same as in Example 1.

[0035] The leaching rates of each valuable metal are Mn 99.2%, Li 99.4%, and the iron content in the leaching solution is 2.3 mg / L.

[0036] Example 4

[0037] Compared with Example 1, the only difference is that in the leaching agent, the concentration of Formula 1 is 2.5M, the concentration of Formula 2 is 0.01M, the temperature of the leaching stage is 25°C, the leaching time is 1.5h, the liquid-to-solid ratio of the leaching stage is 15ml / g, and other operations and parameters are the same as in Example 1.

[0038] The leaching rates of each valuable metal are Ni 99.3%, Co 99.5%, Mn 99.7%, Li 99.9%, and the iron content in the leaching solution is 2.9 mg / L.

[0039] Studies have shown that the scheme described in the present invention can still achieve excellent leaching selectivity of iron and beneficial elements under mild conditions.

[0040] Example 5

[0041] Compared with Example 1, the only difference is that Formula 1 and Formula 2 are dissolved in water in advance to obtain 2M of Formula 1 and 0.018M of Formula 2, which are then stirred and aged at 40°C for 30 minutes, and then cooled to 30°C and participate in subsequent leaching treatment at this temperature, wherein the leaching agent in the leaching stage is reduced to 15 ml / g, and the leaching time is reduced to 1.5 h, and other operations and parameters are the same as in Example 1.

[0042] The leaching rates of each valuable metal are Ni 99.9%, Co 99.8%, Mn 99.9%, Li 99.9%, and the iron content in the leaching solution is 0.5 mg / L.

[0043] It can be seen from Examples 1 and 2 that subjecting the leaching agent to subsequent low-temperature aging treatment in advance can further enhance the physical and chemical characteristics of the two, which can further help improve their synergy in the leaching stage, and can enable them to obtain excellent leaching selectivity of iron and beneficial elements under milder conditions.

[0044] In summary, the above process has a high leaching rate of valuable metals, and the accompanying leaching rate of iron can be controlled within 1%, and the iron content in the leachate can be controlled within 3 mg / L, with excellent leaching selectivity.

[0045] Comparative Example 1

[0046] Compared with Example 1, the only difference is that Formula 2 is not added to the leaching agent. Other operations and parameters are the same as in Example 1.

[0047] The leaching rates of each valuable metal are Ni 32.4%, Co 35.4%, Mn 41.5%, Li 45.7%, Fe 55%, and the iron content in the leaching solution is 8 mg / L.

[0048] Comparative Example 2

[0049] Compared with Example 1, the only difference is that ferrous sulfate is used in the leaching agent to replace the formula 2 (the weight of the ferrous element is the same), and other operations and parameters are the same as those in Example 1.

[0050] The results were as follows: the leaching rates of each valuable metal were Ni87.3%, Co85.4%, Mn90.7%, Li92.1%, and Fe88.9%, and the iron content in the leaching solution was 5.2 mg / L.

[0051] Comparative Example 3

[0052] Compared with Example 1, the only difference is that Formula 1 is not added, and other operations and parameters are the same as Example 1.

[0053] The leaching rates of each valuable metal are Ni 35.8%, Co 37.8%, Mn 47.2%, Li 50.5%, and Fe 20.4%. The iron content in the leaching solution is 8.2 mg / L.

[0054] Comparative Example 4

[0055] Compared with Example 1, the only difference is that The above formula 1 is replaced by equimolar substitution, and the other operations and parameters are the same as those in Example 1.

[0056] The leaching rates of each valuable metal are Ni 67.2%, Co 70.5%, Mn 71.7%, Li 86.9%, and Fe 62.7%. The iron content in the leaching solution is 7.6 mg / L.

[0057] It can be seen from the comparative examples that the iron content in the leaching solution is above 5 mg / L, and it is difficult to achieve the selective separation of iron and valuable metal elements in the leaching stage.

[0058] Electrochemical performance test:

[0059] Recycled positive electrode assembly: The leachate of Example 1, Comparative Example 2 and Comparative Example 4 is adjusted to nickel, cobalt and manganese at 1:1:1, and then sodium hydroxide-ammonia water is added to adjust the pH to 13 for coprecipitation to obtain a precursor, and then lithium is added for calcination (lithium is 1.05 times the molar amount of the transition metal element in the precursor, the calcination temperature is 900°C, and the calcination time is 6h) to obtain a regenerated active material. The regenerated active material (active material), PVDF, and conductive carbon black are mixed in a weight ratio of 9:0.5:0.5 and slurried and coated on the positive electrode current collector, and then dried to obtain the positive electrode to be tested;

[0060] In a glove box, 1M LiPF6 was used as the electrolyte (EC:DEC:EMC=1:1:1), and the diaphragm was Celgard2400 polypropylene film. Lithium was used as the counter electrode, and the above-mentioned positive electrode was used as the electrode to be tested, and a CR2025 battery was assembled. The materials in Example 1, Comparative Example 2 and Comparative Example 4 showed a reversible capacity of 188 mAh / g, 137 mAh / g and 101 mAh / g at a rate of 1C at room temperature, respectively. This shows that the process described in the present invention can optimize the selectivity of impurities and improve the electrochemical properties of the obtained regenerated materials.

Claims

1. A combined leaching agent, characterized in that: Comprising a component of formula 1 and a catalyst of formula 2; 2. The combined leaching agent according to claim 1, characterized in that In the combined leaching agent, the molar ratio of the component of formula 1 to the catalyst of formula 2 is 1-3:0.005-0.

05.

3. A method for leaching valuable elements from waste lithium-ion battery positive electrode materials, characterized in that: The combined leaching agent according to any one of claims 1 to 2 is dispersed with water to obtain a leaching agent, which is then mixed with waste positive electrode materials recovered from waste lithium-ion batteries for leaching treatment, followed by solid-liquid separation to obtain a leachate enriched with valuable elements in the waste positive electrode materials.

4. The method for leaching valuable elements from waste lithium-ion battery positive electrode materials as claimed in claim 3, characterized in that: The waste positive electrode material is a component containing iron and waste positive electrode active material; Preferably, in the waste positive electrode material, the content of the waste positive electrode active material is above 50wt.%, and the content of iron is below 5wt.%.

5. The method for leaching valuable elements from the cathode material of waste lithium-ion batteries as claimed in claim 4, characterized in that: The waste positive electrode material is also allowed to contain at least one of a binder, a conductive agent, a negative electrode material, an electrolyte, and a current collector.

6. The method for leaching valuable elements from the cathode material of waste lithium-ion batteries as claimed in claim 5, characterized in that: The waste positive electrode material is the waste positive electrode material obtained by crushing and separating the waste lithium ion battery shells.

7. The method for leaching valuable elements from the cathode material of waste lithium-ion batteries as claimed in claim 3, characterized in that: In the leaching agent, the concentration of Formula 1 is 1 to 3 M; Preferably, the leaching agent is subjected to a stirring and aging treatment at a temperature of 40 to 45° C. before leaching.

8. The method for leaching valuable elements from waste lithium-ion battery positive electrode materials according to any one of claims 3 to 7, characterized in that: The liquid-to-solid ratio in the leaching stage is 10-50 mL / g.

9. The method for leaching valuable elements from waste lithium-ion battery positive electrode materials according to any one of claims 3 to 7, characterized in that: The temperature in the leaching stage is 15-80°C; preferably 20-45°C.

10. The method for leaching valuable elements from waste lithium-ion battery positive electrode materials according to any one of claims 3 to 7, characterized in that: The leaching time is more than 0.5 h, preferably 1 to 4 h.

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