Leaching agent and method for selective leaching of metal elements from spent nickel-containing lithium-ion battery cathode materials

Abstract

The present application belongs to the field of waste battery positive material recycling, and particularly relates to a leaching agent for selectively leaching metal elements of waste nickel-containing lithium ion battery positive material and a method thereof. The leaching agent is a mixed solution composed of component A and component B with a molar ratio of 1-2:1, wherein component A is a compound of formula 1 ( ), and component B is formula 2 ( ) and formula 3 ( ) with a molar ratio of 0.4-3.5:1. The present application shows that, through the combination of components of formula 1 to formula 3 and the joint control of the ratio of the three, the synergistic effect can be unexpectedly achieved, the leaching effect of lithium and other metals can be optimized based on the interaction of the three, in addition, the accompanying leaching of nickel can be selectively reduced, and thus the efficient and selective leaching separation of nickel and other metals in waste battery material can be achieved.

Description

Technical Field

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

[0002] The main methods for recovering metal elements from waste battery positive electrode materials are acid leaching and alkaline leaching. Among them, acid leaching can achieve full leaching of metals, but the selectivity is not ideal. The alkaline leaching process mainly involves pre-extraction of lithium, and transition metals are difficult to leach and recover. In addition, with the continuous development of technology, the prior art also has some schemes for leaching using hydrogen bond system solvents. For example, the Chinese patent document with publication number CN113871744A discloses a method for recovering waste lithium ion battery positive electrode active materials, specifically reporting the use of a leaching system containing ethylene glycol and a solution formed by dihydrate formula 2, which can achieve co-leaching of lithium and nickel, cobalt and manganese. For another example, the Chinese patent document with publication number CN115692908A discloses a method for recovering waste lithium battery positive electrode active materials, specifically disclosing a method using formula 1 and ethylene glycol as a leaching system, under an ozone atmosphere, to obtain a leaching solution containing only lithium, which also achieves full leaching of metal elements.

[0003] In summary, although there are some improved waste battery metal processes in the existing technology, the existing process uses a high amount of leaching agent, and it is difficult to reasonably balance the selectivity and leaching rate between metals, especially transition metals, in the leaching stage. For example, for waste nickel-containing lithium-ion battery positive electrode materials, the existing technology still finds it difficult to achieve efficient and selective leaching of nickel and other metal elements therein. Summary of the Invention

[0004] In view of the problem that the existing leaching process of waste nickel-containing lithium-ion battery positive electrode materials is difficult to achieve selective leaching of Ni and other elements, the first purpose of the present invention is to provide a leaching agent for selectively leaching metal elements in waste nickel-containing lithium-ion battery positive electrode materials, aiming to achieve efficient selective leaching and separation of nickel and other metals in waste nickel-containing lithium-ion battery positive electrode materials based on the combination of components.

[0005] The second object of the present invention is to provide a method for selectively leaching metal elements from waste nickel-containing lithium-ion battery positive electrode materials, aiming to achieve efficient separation of nickel and other metals with high efficiency and high selectivity.

[0006] A leaching agent for selectively leaching metal elements from waste nickel-containing lithium-ion battery cathode materials, comprising a mixed solution consisting of component A and component B in a molar ratio of 1 to 2:1, wherein component A is a compound of formula 1; and component B is a compound of formula 2 and formula 3 in a molar ratio of 0.4 to 3.5:1.

[0007] Formula 1

[0008] Formula 2

[0009] Formula 3

[0010] The R is H or a C1~C3 alkyl group.

[0011] Due to long-term cycling, spent positive electrodes from used batteries develop a dense SEI component on their surfaces, and the intercalation of metal elements within them makes leaching difficult. This is particularly challenging for transition metals, which are difficult to selectively leach, and even more challenging to achieve highly selective leaching and separation of nickel from other components while maintaining a mild, low-leaching agent dosage. To address this issue, the present invention innovatively demonstrates that combining the components of Formulas 1 through 3, coupled with the coordinated control of their ratios, can unexpectedly achieve synergy. This interaction optimizes the leaching of lithium and other metals, and also selectively reduces the concomitant leaching of nickel, enabling highly efficient and selective leaching and separation of nickel from used battery materials.

[0012] The present invention's research shows that the combination of Formulas 1 to 3 and the joint control of the component ratios are the key to synergistically adapting the physical and chemical characteristics of waste battery materials and achieving selective separation of nickel and other metal elements therein.

[0013] Furthermore, in Formula 3 of the present invention, R may be a methyl group or an ethyl group, and the position of R may be the para position of the sulfonic acid group.

[0014] Further preferably, in component B, the molar ratio of Formula 2 to Formula 3 is 1 to 3:1, preferably 1.5 to 2.5:1. Research in the present invention also shows that jointly controlling the ratio of Formula 2 to Formula 3 in component B can further optimize the compatibility of the prepared leaching agent with the lattice of the waste battery positive electrode material, helping to further improve the leaching efficiency and selectivity of nickel and other metal elements.

[0015] Preferably, the molar ratio of component A to component B is 1.4-1.6:1.

[0016] The leaching agent of the present invention is a uniform clear solution formed by hydrogen bonding between Formulas 1 to 3, and can be prepared by heating and stirring the components A and B at 50 to 90°C.

[0017] The present invention also provides a method for selectively leaching metal elements from waste nickel-containing lithium-ion battery positive electrode materials, comprising mixing the waste nickel-containing lithium-ion battery positive electrode materials and the leaching agent for leaching treatment, followed by solid-liquid separation; obtaining leaching residue enriched with nickel elements in the waste nickel-containing lithium-ion battery positive electrode materials and a leachate of other metal elements; the other metal elements at least comprising lithium.

[0018] The research of the present invention shows that the leaching agent can adapt to the lattice characteristics of the waste positive electrode material, and can achieve highly selective separation of nickel and other metals with high efficiency and high selectivity. In particular, it can take into account the leaching efficiency and selectivity of nickel and other metal components at a low leaching solvent dosage.

[0019] In the present invention, the waste nickel-containing lithium ion battery positive electrode material can be a material obtained by stripping the positive electrode of any waste lithium ion battery containing nickel; it contains waste positive electrode active material and is also allowed to contain components such as a binder, a conductive agent, and a binder.

[0020] In the present invention, the other metal elements in the waste nickel-containing lithium-ion battery positive electrode material may further include at least one of cobalt and manganese. For example, the positive electrode active material contained in the waste nickel-containing lithium-ion battery positive electrode material may be at least one of a nickel-cobalt binary material, a nickel-manganese binary material, or a nickel-cobalt-manganese ternary material.

[0021] In the present invention, the liquid-to-solid ratio in the leaching stage is 5-20 g / g, preferably 8-12 g / g.

[0022] In the present invention, the temperature in the leaching stage is 20°C or higher, preferably 70-90°C.

[0023] In the present invention, the leaching time is 0.5 h or longer, preferably 1 to 10 h, and further preferably 4 to 6 h.

[0024] In the present invention, solid-liquid separation is performed directly after leaching or after dilution with a polar aprotic solvent. Studies in the present invention have shown that the use of a polar aprotic solvent can cooperate with the leaching agent to further optimize the leaching selectivity of nickel and other components.

[0025] In the present invention, the polar aprotic solvent includes at least one of dimethyl sulfoxide and N,N-dimethylacetamide.

[0026] In the present invention, based on the waste nickel-containing lithium ion battery positive electrode material, the amount of the polar aprotic solvent is 8-20 mL / g.

[0027] In the present invention, the solid-liquid separation method may be known methods, such as filtration or centrifugation.

[0028] Beneficial effects:

[0029] The innovative research of the present invention shows that by combining the components of formula 1 to formula 3, and further coordinating the joint control of the proportions of the three, it is possible to unexpectedly achieve synergy, and based on the interaction of the three, optimize the leaching effect of lithium and other metals. Specifically, formula 3 will exclude formula 2 from the nanostructure in the formation of the solvent to reduce the consumption of formula 2 during the leaching process, ensuring a stronger ability to selectively precipitate nickel. In addition, formula 3 can bring more hydrogen bonds to the nanostructure and improve the reducibility of the ternary leaching agent solvent by providing a dominant reduction site, thereby achieving a stronger metal leaching ability. In short, the leaching agent described in the present invention can adapt to the physicochemical characteristics of the positive electrode of waste batteries, and can also achieve selective leaching and separation of nickel and other metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The infrared spectra of the components of Example 1 and the mixed extractant are shown in FIG.

[0031] Figure 2 The leaching effect diagram of different temperatures in Example 3, wherein a is the leaching rate of lithium, nickel, cobalt, and manganese of the leaching agent at different temperatures; b is the purity of the nickel slag precipitated at different temperatures;

[0032] Figure 3 The figure is a leaching effect diagram of different leaching liquid-solid ratios in Example 4, wherein a is the leaching rate of lithium, nickel, cobalt, and manganese of the leaching agent at different mass ratios; b is the purity of the precipitated nickel slag at different mass ratios;

[0033] Figure 4 This is a graph of the leaching rate at different times in Example 5;

[0034] Figure 5 This is the leaching rate diagram of different components B in comparative example 3; Specific implementation plan

[0035] 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.

[0036] 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, LiNi0.8 Co 0.1 Mn 0.1 O2, and the actual cathode powder obtained by disassembling the ternary lithium-ion battery, etc. In the following cases, unless otherwise stated, LiNi 0.8 Co 0.1 Mn 0.1 O2 ternary active materials are a typical example.

[0037]

[0038] 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.

[0039] 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.

[0040] Example 1:

[0041] Step 1. Preparation of leaching agent:

[0042] Formula 2 and Formula 3 (R is a methyl group and is located in the para position of the sulfonic acid group) are mixed in a molar ratio of 7:3 to obtain component B. Component A and component B are mixed in a molar ratio of 3:2 in a flask and heated with stirring at 60-70°C until clarified to form a leachate.

[0043] like Figure 1 As shown, the hydroxyl stretching vibration peaks of Formula 1, Formula 2, and Formula 3A are located at 3225 cm -1 , 3486cm -1 ,3426 cm -1 The synthetic leachate has only one ion at 3330 cm -1 The large stretching vibration peak of the hydroxyl group at , which means that Formula 1, Formula 2, and Formula 3A synthesized deep eutectic leachants under the action of hydrogen bonds.

[0044] Step 2. Leaching experiment: waste ternary lithium-ion battery cathode material (LiNi 0.8 Co 0.1 Mn 0.1 O2) was mixed with the leaching agent in a mass ratio of 1:10, and heated and stirred in a water bath at 70°C for 6 h for leaching;

[0045] Step 3. Separation experiment: After the leaching in step (2) is completed, a non-polar solvent (dimethyl sulfoxide, the liquid-to-solid ratio of which to the waste cathode material is 10-12 mL / g) is added for dilution and then centrifuged to obtain a valuable metal leachate containing lithium, manganese, cobalt, etc. and a nickel slag precipitate.

[0046] Step 4. After diluting the valuable metal leachate with water, the concentrations of lithium, manganese, cobalt, and nickel were measured using an inductively coupled plasma optical emission spectrometer. The leaching rates of lithium, manganese, cobalt, and nickel were calculated using the formula for calculating the leaching rate of valuable metals. The results are shown in Table 2. The nickel slag precipitate was digested and the lithium, manganese, cobalt, and nickel contents in the precipitate were measured and recorded as the purity of the nickel slag. The results are shown in Table 3.

[0047] Example 2:

[0048] Compared with Example 1, the only difference is that the molar ratio of Formula 2 and Formula 3A in Component B is changed. The experimental groups are:

[0049] Group A: The molar ratio of Formula 2: Formula 3A is 5:5;

[0050] Group B: The molar ratio of Formula 2: Formula 3A is 3:7;

[0051] The total molar amount of additive B is the same as in Example 1, and other operations and parameters are the same as in Example 1;

[0052] The leaching effects of each group are shown in Table 4:

[0053] It can be seen from Examples 1 and 2 that the combined control of the ratio of Formula 2 and Formula 3 in component B can optimize the adaptability of the leaching agent to the waste positive electrode material, and can further improve the leaching selectivity of nickel and other elements at a low leaching liquid-to-solid ratio.

[0054] Example 3:

[0055] Compared with Example 1, the only difference is that the leaching temperature in step 2 is changed to 20°C, 30°C, 50°C, 70°C, 80°C, and 90°C. The leaching results are shown in FIG. Figure 2 As shown in the figure, at a leaching temperature of 70°C, the leaching efficiencies of lithium, manganese, and cobalt reached 97.59%, 95.84%, and 96.77%, respectively, and the purity of the resulting nickel slag was 95.7%. When the temperature was further increased to 90°C, the leaching efficiencies of lithium, manganese, and cobalt reached 99.12%, 98.44%, and 98.11%, respectively, and the purity of the resulting nickel slag was as high as 97.4%.

[0056] Example 4:

[0057] Compared with Example 1, the only difference is that the waste ternary lithium ion battery positive electrode material (LiNi x Co y Mn 1-x-y The mass ratios of O2) to leaching agent are 1:5, 1:8, 1:10, 1:12 and 1:15 respectively.

[0058] like Figure 3 As shown in the figure, even at a mass ratio of 1:8, the leaching efficiencies of lithium, manganese, and cobalt can still reach 82.98%, 79.23%, and 91.72%, respectively, and the purity of the resulting nickel slag is 90.13%. With the increase of the solid-liquid ratio, the leaching efficiency and the purity of the nickel slag are greatly improved.

[0059] Example 5:

[0060] Compared with Example 1, the only difference is that the leaching time of step 2 is changed to 10 min, 30 min, 1 h, 2 h, 4 h, and 6 h respectively. Figure 4 As shown, the leaching efficiencies of lithium, manganese and cobalt can reach 81.42%, 72.46% and 78.54% within one hour.

[0061] Example 6:

[0062] Compared with Example 1, the only difference is that the positive electrode materials and conditions used in step 2 are changed, including LiNi 1 / 3Co 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, as well as actual cathode powder obtained by disassembling ternary lithium-ion batteries. The results are shown in Tables 5 and 6. The synthesized new leaching agent has a good treatment effect on different types of battery materials, with the leaching rates of lithium, manganese, and cobalt all close to 90%.

[0063] Example 7:

[0064] Compared with Example 1, the only difference is that the diluent in step 3 is changed to dimethyl sulfoxide and N,N-dimethylacetamide. The results are shown in Table 4. When and only when the diluent is a polar aprotic solvent, it can act as a good diluent without affecting the separation effect of the leachate and the precipitated nickel slag.

[0065]

[0066] Comparative Example 1:

[0067] Compared to Example 1, the only difference is that in step 1, when preparing the leaching agent solvent, component B is simply Formula 2, component A is Formula 1, and the molar ratio of component A to component B is 3:2. All other operations and parameters are the same as in Example 11. The concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein are measured, and the leaching rate is calculated (see Table 8). The leaching performance of this leaching agent is significantly inferior to that of our invented novel leaching agent.

[0068] Comparative Example 2:

[0069] Compared with Example 1, the only difference is that in step 1, when preparing the leaching agent solvent, component B is only Formula 3A, component A is Formula 1, and the molar ratio of component A to component B is 3:2. Other operations and parameters are the same as in Example 11. The concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein are measured, and the leaching rate is calculated (see Table 9). Although this example shows a significant breakthrough in leaching performance, it cannot achieve the selective precipitation of nickel of the leaching agent invented by us.

[0070]

[0071] Comparative Example 3:

[0072] Compared with Example 1, the only difference is that the following components (Formulas 4-8) are used to replace the formula 3A described in the component B in equal molar amounts to obtain comparative components B (specific groups are component B groups of Formula 2 + Formula 4, component B groups of Formula 2 + Formula 5, component B groups of Formula 2 + Formula 6, component B groups of Formula 2 + Formula 7, and component B groups of Formula 2 + Formula 8), and then the comparative components B and component A are fused to obtain comparative leaching agents. Other operations and parameters are the same as in Example 1. The results are shown in FIG. Figure 5 If and only if Formula 3A can efficiently leach lithium, manganese, and cobalt at a high solid-to-liquid ratio and low temperature, and selectively precipitate nickel.

[0073] Formula 4

[0074] Formula 5

[0075] Formula 6

[0076] Formula 7

[0077] Formula 8

[0078] In summary, the innovative research of the present invention demonstrates that the inventive leaching agent can efficiently leach valuable metals from spent ternary lithium-ion batteries under mild conditions of low temperature and high solid-to-liquid ratio, while also selectively precipitating nickel. Furthermore, the present invention has excellent applicability to a variety of non-ternary lithium-ion batteries.

[0079] 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 selectively leaching metal elements from waste nickel-containing lithium-ion battery cathode materials, characterized in that: A mixed solution composed of component A and component B in a molar ratio of 1 to 2:1, wherein component A is a compound of formula 1; component B is a compound of formula 2 and formula 3 in a molar ratio of 1 to 3:1; Formula 1 Formula 2 Formula 3 The R is H or a C1~C3 alkyl group.

2. The leaching agent according to claim 1, wherein In the component B, the molar ratio of formula 2 to formula 3 is 1.5-2.5:

1.

3. The leaching agent according to claim 1 or 2, characterized in that The molar ratio of component A to component B is 1.4 to 1.6:

1.

4. A method for selectively leaching metal elements from waste nickel-containing lithium-ion battery cathode materials, characterized in that: The waste nickel-containing lithium-ion battery positive electrode material and the leaching agent according to any one of claims 1 to 3 are mixed and subjected to leaching treatment, followed by solid-liquid separation; a leaching residue enriched with nickel in the waste nickel-containing lithium-ion battery positive electrode material and a leaching solution of other metal elements are obtained; the other metal elements include at least lithium.

5. The method according to claim 4, wherein The other metal elements further include at least one of cobalt and manganese.

6. The method according to claim 5, wherein The positive electrode active material contained in the waste nickel-containing lithium ion battery positive electrode material is at least one of a nickel-cobalt binary material, a nickel-manganese binary material, and a nickel-cobalt-manganese ternary material.

7. The method according to claim 4, wherein The liquid-to-solid ratio in the leaching stage is 5~20g / g.

8. The method according to claim 7, wherein The liquid-to-solid ratio in the leaching stage is 8~12g / g.

9. The method according to claim 4, wherein The temperature during the leaching stage is above 20°C.

10. The method according to claim 9, wherein The temperature in the leaching stage is 70~90℃.

11. The method according to claim 4, wherein After leaching is completed, solid-liquid separation is performed directly or after dilution with a polar aprotic solvent.

12. The method according to claim 11, wherein The polar aprotic solvent includes at least one of dimethyl sulfoxide and N,N-dimethylacetamide.

13. The method according to claim 12, wherein: Based on the waste nickel-containing lithium-ion battery positive electrode material, the amount of polar aprotic solvent used is 8-20 mL / g.

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