Leaching, leaching agents and methods for recycling spent ternary cathode materials

Abstract

The application belongs to the field of leaching of waste positive electrode material, and particularly relates to a leaching agent for leaching waste ternary cathode material, which is composed of a hydrogen bond complex and a viscosity regulator; the hydrogen bond complex is composed of formula A and formula B; the viscosity regulator is water; the molar ratio of the formula A, the formula B and the viscosity regulator is 1-3:1-3:6-16. In the application, the waste cathode material does not need to be activated too much and can be directly leached due to the use of the leaching agent, in addition, the leaching agent can be recycled.

Description

Technical Field

[0001] The present invention belongs to the field of recycling and processing of waste lithium-ion batteries, and in particular relates to the field of leaching of waste cathode materials. Background Art

[0002] Recovering metals from cathode and cathode materials is particularly important. Hydrometallurgy offers advantages such as excellent metal separation and high-purity recovered products, giving it a competitive edge in the market. However, this process faces challenges in application, including complex procedures, high energy consumption, large reagent volumes, and significant secondary pollution.

[0003] For waste cathodes, the existing method is mainly acid leaching. For example, the Chinese patent document with publication number CN116162785A discloses a full-chain integrated leaching method for high-grade nickel matte, which specifically includes mixing high-grade nickel matte powder with an oxidant and performing a first-stage roasting and a second-stage roasting, followed by an acid leaching treatment. For another example, the Chinese patent document with publication number CN117947274A discloses a method for full extraction and separation of metal elements in the sulfuric acid leachate of waste ternary lithium batteries, specifically recording a scheme for leaching waste ternary lithium batteries with sulfuric acid. The Chinese patent document with publication number CN115141933A discloses a method for purifying the leachate recovered from ternary lithium batteries, specifically recording a scheme for heating the waste positive electrode material and leaching and removing impurities at pH 5.0-6.5. For another example, the Chinese patent document with publication number CN114657380A discloses a step-by-step selective impurity removal method from the acidic leachate of waste ternary lithium-ion batteries.

[0004] In summary, existing leaching processes for waste cathode materials mostly require enhanced leaching using auxiliary methods such as high temperature or ball milling. Even so, the leaching temperature and liquid-to-solid ratio are relatively high. The industry needs a high-performance leaching recovery process that does not require extensive pretreatment, operates at a mild temperature, and uses low solvent dosage. Summary of the Invention

[0005] In response to the problems faced by the existing leaching of waste ternary cathode materials, the first purpose of the present invention is to provide a leaching agent for leaching waste ternary cathode materials, aiming to improve the leaching effect of waste ternary materials under low temperature and low leaching liquid-to-solid ratio.

[0006] The second purpose of the present invention is to provide a method for leaching and recovering metal elements in waste ternary cathode materials, aiming to innovatively utilize the leaching agent to improve the leaching effect of metals in waste cathode materials at a lower temperature and a lower liquid-to-solid ratio.

[0007] Most existing leaching processes for waste ternary cathode materials require activation leaching by means of high temperature or mechanical activation. Moreover, higher leaching temperatures and higher leaching liquid-solid ratios are still required to achieve ideal leaching effects. This approach has a high process cost. In addition, the leaching agent is difficult to recycle and reuse, resulting in a large output of three wastes. To address this problem, the present invention provides the following solutions:

[0008] A leaching agent for leaching waste ternary cathode materials, comprising a hydrogen bond complex and a viscosity regulator;

[0009] The hydrogen bond complex is composed of formula A and formula B;

[0010] Formula A

[0011] Formula B

[0012] The viscosity modifier is water;

[0013] The molar ratio of formula A, formula B and viscosity regulator is 1-3:1-3:6-16.

[0014] The present invention's innovative research demonstrates that the innovative hydrogen bonding of Formulas A and B to form a eutectic, combined with the viscosity modifier and controlled ratios of the components, unexpectedly achieves synergy, resulting in excellent critical metal leaching kinetics at low leaching solvent dosages and low temperatures, enabling superior leaching results at even milder temperatures and lower solvent volumes. The present invention utilizes the leaching agent, eliminating the need for extensive activation of the waste cathode material, enabling direct leaching. Furthermore, the leaching agent is used sparingly and can be recycled.

[0015] In the present invention, the joint control of the components A, B and viscosity modifier and their proportions is the key to synergistically improving the leaching kinetics of waste ternary cathode materials and improving the leaching effect at low temperature and low leaching agent dosage.

[0016] In the present invention, the molar ratio of Formula A, Formula B, and viscosity modifier is 1:0.5-1.5:6-10, and more preferably 1:0.9-1.1:7.5-8.5. Studies in the present invention have shown that the combined control of the above components and preferred ratios helps further improve the leaching efficiency of waste ternary cathode materials and the leaching effect under mild conditions.

[0017] In the present invention, the viscosity of the leaching agent is 25-60 mPs, preferably 35-45 mPs. Studies have shown that at an optimal viscosity, the combined synergy between the components can be further improved, which helps to further improve the mild leaching effect of the leaching agent.

[0018] The present invention also provides a method for leaching waste ternary cathode materials, wherein the waste ternary cathode materials and the leaching agent of the present invention are mixed and leached to obtain a leachate.

[0019] The present invention innovatively uses the leaching agent for leaching waste ternary cathode materials. Based on the combined control of components and proportions, excellent leaching effects can be achieved at lower leaching agent dosage and lower temperature.

[0020] In the present invention, the waste ternary cathode material is waste lithium-containing nickel-cobalt-manganese oxide obtained by stripping from the positive electrode of waste lithium-ion batteries.

[0021] In the present invention, the waste ternary cathode material can be a composite ternary cathode material of any ternary crystal on the market. In addition, it can also be a ternary cathode waste with low metal content that is difficult to leach gently in the industry. For example, the waste ternary cathode material can be waste of various crystals such as NCM111, NCM523, and NCM622. Taking into account the maximization of recycling value, the waste ternary cathode material can further be a mixed crystal waste ternary cathode material with low metal content, for example, its lithium content can be 3~4wt.%, nickel content is 18~22wt.%, cobalt content is 4~5wt.%, and manganese content is 7.5~8.5wt.%.

[0022] In the present invention, the temperature during the leaching process is above 15°C, and can be further adjusted to 20-35°C in consideration of the effect, operation, and cost. In the present invention, thanks to the innovative use of the leaching agent, excellent leaching effects can be achieved even under low-temperature conditions, which are difficult to achieve effective leaching in the industry. However, it should be noted that the leaching agent of the present invention can also be used at high temperatures, but at low temperatures, it has more advantages in operation and cost, and has higher recovery value than existing solutions.

[0023] In the present invention, during the leaching stage, the weight ratio of the waste ternary cathode material to the leaching agent is 1:1 to 5, preferably 1:2.5 to 3.5. The leaching agent of the present invention can achieve excellent leaching activity at a low leaching agent dosage.

[0024] In the present invention, the leaching time is 2 hours or more, preferably 8 to 15 hours, and further can be 9 to 11 hours.

[0025] In the present invention, the target metal can be recovered from the leachate obtained by leaching based on existing conventional means.

[0026] For example, the application also provides a method for recycling leaching elements in waste ternary cathode material, for example, the leaching method described in the application can be used to obtain a leaching solution, a transition metal precipitant is added to the leaching agent, solid-liquid separation is performed to obtain a transition metal precipitate and a lithium solution; then the lithium solution is subjected to lithium precipitation treatment to obtain a lithium residue.

[0027] In the application, the leaching solution is added with a transition metal precipitant after being subjected to impurity removal treatment.

[0028] Preferably, the impurity removal treatment comprises the step of controlling the pH of the leaching solution to be 3.8-7.5 and then performing solid-liquid separation.

[0029] Preferably, the transition metal precipitant is oxalic acid or a water-soluble salt thereof.

[0030] Preferably, the lithium precipitation means is a process of adding a water-soluble carbonate to precipitate or a process of introducing carbon dioxide to precipitate.

[0031] Beneficial effects:

[0032] Innovative researches of the application show that, the hydrogen bond complex of formula A and formula B is formed, and the viscosity regulator and the combined control of the component ratio are combined, so that the synergistic effect can be unexpectedly achieved, excellent critical metal leaching kinetics can be obtained at low leaching solvent dosage and low temperature, and excellent leaching effect can be obtained at a more moderate temperature and a lower solvent capacity. In the application, thanks to the use of the leaching agent, the waste cathode material does not need to be activated too much before leaching, in addition, the leaching agent dosage is saved and can be recycled. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The infrared spectrum of each component and the mixed leaching agent of Example 1;

[0034] Figure 2 The nuclear magnetic spectrum of each component and the mixed leaching agent of Example 1;

[0035] Figure 3 The Raman spectrum of each component and the mixed leaching agent of Example 1;

[0036] Figure 4 The XRD and Raman graph of the positive electrode material before and after leaching of Example 1;

[0037] Figure 5 The SEM graph of the positive electrode material before leaching of Example 1;

[0038] Figure 6 The SEM graph of the positive electrode material precursor prepared by co-precipitation of Example 1; DETAILED DESCRIPTION

[0039] The present invention will be described in further detail below with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.

[0040] The waste positive electrode material of the present invention is waste ternary lithium ion battery positive electrode material (LiNi x Co y Mn 1-x-y O2) as an example, which specifically includes LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, and the actual positive electrode powder obtained by disassembling ternary lithium-ion batteries, etc.

[0041]

[0042] The actual positive electrode powder is a mixed crystal of ternary crystals such as NCM111, NCM523, and NCM622. Considering the limitation of stripping technology, a binder, a conductive agent, and an anode material are also allowed to be present.

[0043] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0044] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0045] Example 1:

[0046] Step 1. Preparation of leaching agent:

[0047] Additive A (Formula A), additive B (Formula B) and additive C (water) were mixed in a molar ratio of 1:1:8 and heated at 60-65° C. under stirring until a transparent liquid was formed to prepare an extractant (viscosity of 39.7 mps).

[0048] Step 2. Leaching experiment: The actual cathode powder (composition content see Table 1) was mixed with the leaching agent of step 1 at a mass ratio of 1:3, and heated and stirred at 30°C for 10 hours for leaching;

[0049] Step 3. Separation experiment: After the leaching in step (2) is completed, the initial pH value of 3.8 is adjusted to 7.5 using 2M NaOH solution. Then, the solution is filtered through a filter with a pore size of 0.22 μm to remove graphite and precipitated Cu. 2+ ions. The resulting solution was mixed with an aqueous oxalic acid solution and stirred at 70°C for 2 hours to co-precipitate the cathode material precursor. Finally, a 2M Na2CO3 solution was used to completely precipitate the remaining Li⁺ to produce the Li2CO3 product.

[0050] Step 4. Measure the concentration of the remaining metals in the filtrate after each step and calculate their mass fractions.

[0051] The concentrations of lithium, manganese, cobalt and nickel were measured using an inductively coupled plasma emission spectrometer, and the leaching rates of lithium, manganese, cobalt and nickel were calculated using the leaching rate calculation formula for valuable metals. The results are shown in Table 2.

[0052]

[0053] Note: The leaching rates mentioned above refer to the leaching rates of the metals in step 2.

[0054] It can be seen from Example 1 that the leaching agent with the composition and proportion described in the present invention can be adapted to the leaching effect of waste ternary cathode materials, and excellent leaching effect can be obtained at low temperature and low leaching agent dosage.

[0055] Example 2:

[0056] Compared with Example 1, the only difference is that the heating temperature in step 1 is changed, and the temperature in the leaching stage is 20°C. The leaching results are shown in Table 3.

[0057]

[0058] It can be seen from Examples 1 and 2 that the leaching method of the present invention, thanks to the use of the leaching agent, can achieve excellent leaching effect at low temperature.

[0059] Example 3:

[0060] Compared with Example 1, the only difference is that the leaching time in step 2 is changed. The results are shown in Table 4.

[0061]

[0062] Example 4:

[0063] Compared with Example 1, the only difference is that the cathode material waste to be leached was changed in step 2 (content shown in Table 1). The leaching results are shown in Table 5.

[0064]

[0065] As shown in Examples 1 and 4, the method of the present invention can achieve good synchronous and gentle leaching effects for different ternary materials. Even for low-metal-content positive electrode powders, ideal leaching effects can be achieved at low temperatures and low leaching agent dosages.

[0066] Example 5:

[0067] Compared with Example 1, the only difference is that step 2 is changed to change the solid-liquid weight ratio in the leaching stage to 1:5. The results are shown in Table 6.

[0068]

[0069] It can be seen from Examples 1 and 5 that by adopting the method of the present invention, good leaching effect can be obtained at a low leaching agent dosage.

[0070] Example 6:

[0071] Compared with Example 1, the only difference is that the viscosity of the leaching agent is regulated by the additive C, and the other operations and parameters are the same as those of Example 1. The results are shown in Table 7.

[0072]

[0073] It can be seen from Examples 1 and 6 that under the viscosity described in the present invention, especially when the molar ratio of Formula A, Formula B, and viscosity regulator is 1:0.9~1.1:7.5~8.5, and the viscosity is controlled at 35~45mPs, better adaptability and synergy can be obtained, and a better mild leaching effect can be obtained.

[0074] Example 7:

[0075] Compared to Example 1, the only difference is that the solvent after leaching is recovered and recycled. The composition of the leaching agent and other conditions in the cyclic leaching stage are the same as those in the first leaching. The results are shown in Table 8. The leaching efficiency remains high in the second cycle. After three cycles, the solvent is consumed and the leaching performance decreases.

[0076]

[0077] It can be seen from Examples 1 and 7 that the system of the present invention not only has the advantage of good mild leaching, but also has good cyclic leaching stability.

[0078] Example 8:

[0079] The difference between Example 1 and this example is that the ratio of additive A and additive B is changed. Other operations and parameters are the same as those in Example 1. The concentrations of lithium ions, nickel ions, cobalt ions and manganese ions contained in the leaching agent are measured, and the leaching rate is calculated (see Table 9).

[0080]

[0081] From Examples 1 and 8, it can be seen that the leaching agent in the preferred ratio of the present application can achieve a better leaching effect.

[0082] Comparative Example 1

[0083] The difference between Example 1 and this example is that the viscosity modifier (additive C) is absent in the leaching agent. Other operations and parameters are the same as those in Example 1. The concentrations of lithium ions, nickel ions, cobalt ions and manganese ions contained in the leaching agent are measured, and the leaching rate is calculated (see Table 10).

[0084]

[0085] Comparative Example 2

[0086] The difference between Example 1 and this example is that the additive B is replaced by the additive C in the preparation of the leaching agent solvent in step 1. Other operations and parameters are the same as those in Example 1. The concentrations of lithium ions, nickel ions, cobalt ions and manganese ions contained in the leaching agent are measured, and the leaching rate is calculated (see Table 11).

[0087]

[0088] Comparative Example 3

[0089] The difference between Example 1 and this example is that the following combined components are used as the leaching agent (the molar ratio of the leaching agent in the comparison is the same as that in Example 1) in the preparation of the leaching agent solvent in step 1.

[0090] Group A: the leaching agent is formula D + formula B + water;

[0091] Group B: the leaching agent is formula E + formula B + water;

[0092] Group C: the leaching agent is formula D + formula C + water;

[0093] Group D: the leaching agent is formula E + formula C + water;

[0094] Formula D

[0095] Formula E

[0096] Other operations and parameters were the same as those in Example 1. The concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein were measured, and the leaching rate was calculated (see Table 12).

[0097]

[0098] In summary, the innovative research of the present invention shows that the leaching agent of the invention can achieve efficient leaching of valuable metals in waste ternary lithium-ion batteries under mild conditions of low temperature and high solid-liquid ratio. In addition, the leaching system also takes into account excellent cyclic leaching activity and stability.

[0099] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A leaching agent for leaching waste ternary cathode materials, characterized in that: It is composed of a hydrogen bonding complex and a viscosity modifier; The hydrogen bond complex is composed of formula A and formula B; Formula A Formula B The viscosity modifier is water; The molar ratio of formula A, formula B and viscosity regulator is 1-3:1-3:6-16.

2. The leaching agent for leaching waste ternary cathode materials according to claim 1, characterized in that: The molar ratio of formula A, formula B and viscosity regulator is 1:0.9-1.1:7.5-8.

5.

3. The leaching agent for leaching waste ternary cathode materials according to claim 1 or 2, characterized in that: The viscosity of the leaching agent is 25-60 mPs.

4. The leaching agent for leaching waste ternary cathode materials according to claim 3, characterized in that: The viscosity of the leaching agent is 35-45 mPs.

5. A method for leaching waste ternary cathode materials, characterized in that: The waste ternary cathode material is mixed with the leaching agent according to any one of claims 1 to 4 and subjected to leaching treatment to obtain a leachate.

6. The method for leaching waste ternary cathode materials according to claim 5, characterized in that: The waste ternary cathode material is waste lithium-containing nickel-cobalt-manganese oxide obtained by stripping from the positive electrode of waste lithium-ion batteries.

7. The method for leaching waste ternary cathode materials according to claim 5, characterized in that: The temperature during the leaching process is above 15°C.

8. The method for leaching waste ternary cathode materials according to claim 7, wherein: The temperature during the leaching process is 20~35℃.

9. The method for leaching waste ternary cathode materials according to claim 5, characterized in that: During the leaching stage, the weight ratio of waste ternary cathode material and leaching agent is 1:1~5.

10. The method for leaching waste ternary cathode materials according to claim 9, characterized in that: During the leaching stage, the weight ratio of waste ternary cathode material and leaching agent is 1:2.5~3.

5.

11. The method for leaching waste ternary cathode materials according to claim 5, characterized in that: The leaching time is more than 2 hours.

12. The method for leaching waste ternary cathode materials according to claim 11, characterized in that: The leaching time is 8~15h.

13. A method for recovering leached elements from waste ternary cathode materials, characterized in that: The method according to any one of claims 5 to 12 is used to obtain a leachate, and a transition metal precipitant is added to the leaching agent to separate the solid and the liquid to obtain a transition metal precipitate residue and a lithium solution. The lithium liquid is then subjected to lithium precipitation treatment to obtain lithium slag.

14. The method for recovering leached elements from waste ternary cathode materials according to claim 13, wherein: The leachate is pre-treated to remove impurities and then a transition metal precipitant is added.

15. The method for recovering leached elements from waste ternary cathode materials according to claim 14, characterized in that: The impurity removal treatment includes the steps of controlling the pH of the leaching solution to 3.8-7.5 and then performing solid-liquid separation.

16. The method for recovering leached elements from waste ternary cathode materials according to claim 13, wherein: The transition metal precipitant is oxalic acid and its water-soluble salt.

17. The method for recovering leached elements from waste ternary cathode materials according to claim 13, wherein: The lithium precipitation method is a process of adding water-soluble carbonate for precipitation, or a process of introducing carbon dioxide for precipitation.

Images