Recycling method of waste positive electrode material

Abstract

The invention belongs to the field of waste battery recovery, and particularly relates to a waste positive electrode material recovery method which comprises the following steps: mixing an additive A # imgabs 0 #, an additive B # imgabs 1 # and an additive C # imgabs 2 # to obtain a synergistic leaching agent; mixing the waste positive electrode material with the synergistic leaching agent for leaching treatment, and recovering to obtain a leaching solution enriched with metal elements in the positive electrode material; the viscosity of the synergistic leaching agent ranges from 70 mPa. S to 600 mPa. S; the molar ratio of the additive A to the additive B is (0.9-2.5): 1; in the leaching process, the weight ratio of the synergistic leaching agent to the waste positive electrode material is 6 or above, the leaching temperature is 50 DEG C or above, and the leaching time is 6 H or above. Innovative research shows that the additive A, the additive B and the additive C with the structure are synergistically combined and further matched with parameter control, so that the leaching recovery effect of the positive electrode material can be further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery recycling, and specifically to the field of treatment of waste cathode materials. Background Art

[0002] Lithium batteries are the "heart" of modern industry. As one of the core components of new energy vehicles, they are relatively advanced secondary batteries, with characteristics such as high energy density, long cycle life, low self-discharge rate, and low pollution. The wide use of lithium batteries in new electric vehicles has effectively alleviated the problems of insufficient oil and gas resources and environmental pollution.

[0003] Waste lithium batteries have significant resource attribute characteristics, rich in valuable metal elements such as lithium, nickel, cobalt, and manganese, and can be vividly compared to precious "urban mines". Compared with natural ores, the metal content and purity in waste lithium batteries are higher. Currently, China is lacking in lithium, cobalt, and nickel resources, with high prices and heavy dependence on imports, and a high degree of foreign dependence; manganese ore resources are relatively abundant, but with small scale and high mining costs. If waste batteries are not properly treated and are discarded randomly, on the one hand, it will bring about resource waste problems, and on the other hand, the large amount of electrolytes and heavy metals in waste batteries will cause a huge burden on the environment. With the approaching of the "retirement tide" of power batteries, it is urgent to develop green and environmental protection recycling technologies for waste lithium-ion batteries.

[0004] Currently, the processes for recovering valuable metals from waste lithium batteries mainly include pyrometallurgy and hydrometallurgy. Among them, pyrometallurgy does not require mechanical disassembly and physical separation steps, and directly recovers waste LIBs through high-temperature heat treatment (up to 1200°C), directly oxidizing and decomposing the organic matter in them, and converting metal elements into metal oxides for recovery by means of flotation and precipitation methods. This method has simple operation and large processing capacity, and has been industrialized, but there are problems such as high energy consumption, serious loss of metal resources, and the emission of harmful gases. Hydrometallurgy treats waste lithium-ion batteries in concentrated corrosive acids to dissolve and extract metals. Hydrometallurgy has a higher leaching efficiency than pyrometallurgy and can recover any battery material, but the steps are complex, and a large amount of waste acid will be generated, and harmful gases such as Cl2, SO3, and NO will also be released X causing an environmental burden. Therefore, in order to reduce or even avoid pollution during the recycling process, many studies are committed to developing new green leaching systems and new solvents to realize the recovery of valuable metals in waste batteries and break through the key bottleneck of existing resource reuse. Summary of the Invention

[0005] In response to the problems faced by the recycling of waste positive electrode materials, such as the need for leaching at a large dosage of reagents, large acid and alkali consumption, and large output of three wastes, the purpose of the present invention is to provide a new method for recycling waste lithium-ion battery positive electrode materials, aiming to provide a new method that is environmentally friendly and has excellent positive electrode element recovery effect.

[0006] A method for recovering waste positive electrode materials comprises mixing additives A, B and C to obtain a synergistic leaching agent; then mixing the waste positive electrode materials with the synergistic leaching agent and performing a leaching treatment to recover a leachate enriched with metal elements in the positive electrode materials;

[0007] The additive A is a compound having a structure of formula 1;

[0008]

[0009] The additive B is a compound having a structure of Formula 2 and / or Formula 3;

[0010]

[0011] Additive C is water;

[0012] The viscosity of the synergistic leaching agent is 70 to 600 mPs; and the molar ratio of additive A to additive B is 0.9 to 2.5:1;

[0013] During the leaching process, the weight ratio of the synergistic leaching agent to the waste positive electrode material is greater than 6, the leaching temperature is greater than 50° C., and the leaching time is greater than 6 hours.

[0014] The innovative research of the present invention demonstrates that the synergistic combination of Additives A, B, and C in the described structure can achieve synergy through the unique hydrogen bonding between the components. Combined with the controlled ratio of the components and viscosity, this can synergistically improve the lattice disintegration effect of the positive electrode material. Furthermore, based on the innovative use of the described synergistic leaching agent, combined with the combined control of leaching temperature, solvent dosage, and time, the leaching recovery effect of the positive electrode material can be further improved. The process of the present invention is environmentally friendly and can effectively control the output of the three wastes.

[0015] In the present invention, the waste positive electrode material is an electrode material obtained by stripping the positive electrode of a waste lithium-ion battery.

[0016] In the present invention, the waste positive electrode material can be obtained by stripping based on a known process method.

[0017] The process of the present invention has no special requirements for the metal type of the waste cathode material and has excellent universality. Considering the market application prospects, the waste cathode material may include at least one waste active material among LiXO2, LiY2O2, and LiZPO4; X and Y each independently include at least one of Ni, Co, and Mn; Z includes at least one of Fe and Mn.

[0018] The process of the present invention has excellent leaching selectivity for the metals in the waste cathode material and has a relatively loose tolerance for raw materials. For example, the waste cathode material is also allowed to contain at least one of a conductive agent, a binder, and a negative electrode material;

[0019] For the process of the present invention, there are no special requirements for the content of the waste active material in the waste cathode material. Considering the processing economy of the process, it can be above 50 wt%, and further can be 80 - 90 wt%.

[0020] In the present invention, the additive A, additive B, and water can be assisted by an external force to accelerate the uniform fusion between components, for example, mixed evenly under stirring assistance. The rotation speed of stirring is, for example, 300 - 500 rpm. The temperature of the system is controlled at 50°C - 80°C during the mixing stage, preferably 55°C - 60°C.

[0021] In the present invention, the combination of the additive A, additive B, and water components in the co - leaching agent, as well as the control of the proportion and viscosity of the components, are the key to improving the effect on the waste cathode material.

[0022] Preferably, the additive B is of formula 2, and the molar ratio of additive A to additive B is 0.9 - 1.2:1, preferably 1 - 1.1:1. Or, the additive B is of formula 3, and the molar ratio of additive A to additive B is 1.9 - 2.2:1, preferably 2 - 2.1:1. Under the preferred ratio, the combined synergistic effect of the co - leaching agent can be further improved, and the leaching effect of the waste cathode material can be further improved.

[0023] Preferably, the viscosity of the co - leaching agent is 75 - 550 mPa·s, and more preferably 440 - 460 mPa·s. Under the preferred ratio, the combined synergistic effect of the co - leaching agent can be further improved, and the leaching effect of the waste cathode material can be further improved.

[0024] In the present invention, controlling the dosage, temperature, and time of the leaching agent during the leaching process can further cooperate with the co - leaching agent, which helps to further improve the leaching effect of the waste cathode material.

[0025] Preferably, during the leaching process, the weight ratio of the co - leaching agent to the waste cathode material is above 10, preferably 10 - 25:1.

[0026] Preferably, in the leaching process, the leaching temperature is above 60°C, preferably 60 - 80°C.

[0027] Preferably, the leaching stage is carried out with the assistance of stirring;

[0028] Preferably, the stirring speed is 300 - 550 rpm;

[0029] Preferably, the leaching time is above 8 h, preferably 10 - 20 h.

[0030] In the present invention, after the leaching is completed, solid-liquid separation can be carried out by conventional processes, such as manually sucking the liquid with a syringe and obtaining the enriched leaching solution by passing through a 0.45-μm filter head made of transparent grade polymer material polypropylene (PP).

[0031] In the present invention, in order to accelerate the filtration separation efficiency, before filtration, water can be selectively added to the system to assist in the solid-liquid separation of the leaching solution. The added water is more than 2 times the volume of the co-leaching agent. Considering the cost, it can be further 2 - 10:1.

[0032] Beneficial effects

[0033] In the present invention, the additive A, additive B and water with the above structure are innovatively combined synergistically, and further combined with the control of the component ratio, viscosity, temperature, solvent dosage and time in the leaching stage, which can further improve the leaching and recovery effect of the cathode material. The process of the present invention is green and environmentally friendly, and can effectively control the output of three wastes.

[0034] The present invention has higher chemical stability, is not easy to volatilize, has weaker corrosiveness, and does not release toxic and harmful gases; Description of the drawings:

[0035] Figure 1 : XRD pattern of the used NCM ternary cathode material before leaching in Example 1;

[0036] Figure 2 : SEM images of the used NCM ternary cathode material before and after leaching in Example 1;

[0037] Figure 3 : Infrared spectrum of the co-leaching agent in Example 1. Specific embodiments:

[0038] The purpose of the present invention is to overcome the deficiencies in the prior art, and to focus on breaking through the problems of high energy consumption and high pollution brought by conventional acid leaching and alkali leaching methods. Additives A, B, and C are used together to prepare a synergistic leaching agent. The synergistic leaching agent described in the present invention, based on the hydrogen bond synergy of its components, the control of the mixing ratio and viscosity, can synergistically improve its leaching effect on the cathode. Under the condition of a high solid-liquid ratio, without the need for a reducing agent, it can achieve the efficient recovery of valuable metal elements such as nickel, cobalt, manganese, and lithium in lithium batteries, and has high economic feasibility and environmental friendliness.

[0039] In the present invention, the active material in the waste lithium battery cathode material can be one or several of lithium cobaltate, lithium nickelate, lithium manganate, and NCM ternary materials. In the following cases, the NCM ternary material is taken as an example. In addition, in the waste cathode material, components such as conductive agents and binders that are allowed in conventional cathode materials are also allowed. In the following cases, unless otherwise stated, the content of NCM in the waste cathode material is 70-90 wt.%, and the element ratio in NCM is shown in Table 1:

[0040] Table 1 Mass fractions of lithium, nickel, cobalt, and manganese in the active material of the waste NCM ternary lithium battery cathode

[0041] Metal type Li Ni Co Mn Mass fraction 3.77％ 24.37％ 5.20％ 8.01％

[0042] Note: The waste NCM ternary cathode material is completely dissolved by strong acid digestion method to obtain a digestion solution. After cooling, it is diluted and the content is tested. Measure the concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein.

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

[0044] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0045] The viscosity of the present invention can be tested based on conventional means. For example, as an example: Use an IKA viscometer model ETS-D5, drop an appropriate volume of the synergistic leaching agent into the instrument, the rotation speed is 200 rpm, and the temperature is 25 °C.

[0046] Example 1:

[0047] Step 1: Discharge the used NCM ternary lithium battery and then disassemble it. Collect the positive electrode sheet and crush it using a crusher to obtain positive electrode sheet fragments. After pretreatment such as filtering through a 100-mesh sieve and sufficient grinding, the waste lithium battery positive electrode material powder to be leached is obtained (the element content is shown in Table 1).

[0048] Step 2: Mix additive A (Formula 1, also simply referred to as chcl) and additive B (Formula 2) in a molar ratio of 1:1, and then add additive C (deionized water). Heat at a temperature of 60 °C and stir for 15 - 20 min; the stirring rate is 500 rpm; a synergistic leaching agent with a viscosity of 440 - 460 mPa·s is obtained.

[0049] Step 3: Mix the waste lithium battery positive electrode material powder obtained after the treatment in Step 1 with the synergistic leaching agent obtained in Step 2, heat and stir; the leaching temperature is 60 °C, the leaching time is 16 h, the mass ratio of the waste lithium battery positive electrode material powder to the prepared synergistic leaching agent is 1:10 g / g, and the stirring rate is 500 rpm.

[0050] Step 4: Add water (3 times the volume of the synergistic leaching agent) to the leaching system in Step 3 and perform solid-liquid separation (for example, manually suck the liquid with a 10-ml syringe and pass it through a 0.45-μm filter head made of transparent high-molecular material polypropylene (PP)). Filter the obtained clear liquid, which is the enriched liquid of valuable metals. After cooling, dilute it and perform content testing. Measure the concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained in it, and calculate the leaching rate (see Table 2).

[0051] Table 2

[0052] Metal type Li Ni Co Mn Leaching rate 98.48％ 100％ 98.93％ 99.05％

[0053] Example 2:

[0054] Compared with Example 1, the difference is only that the dosage of additive C in Step 2 is changed, and synergistic leaching agents with viscosities of 480 - 510 mPas / 80 - 90 mPas are obtained respectively and used in the subsequent leaching steps. Other operations and parameters are the same as in Example 1. Measure the concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained in it, and calculate the leaching rate (see Table 3).

[0055] Table 3

[0056]

[0057] Example 3:

[0058] Compared with Example 1, the only difference is that the leaching temperature in Step 3 is changed to 30°C, 40°C, 50°C, and 70°C respectively. Other operations and parameters are the same as those in Example 1. Measure the concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein, and calculate the leaching rate (see Table 4).

[0059] Table 4

[0060]

[0061] Example 4:

[0062] Compared with Example 1, the only difference is that the leaching time in Step 3 is changed to 4h, 8h, 12h, and 20h respectively. Other operations and parameters are the same as those in Example 1. Measure the concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein, and calculate the leaching rate (see Table 5).

[0063] Table 5

[0064]

[0065] Example 5:

[0066] Compared with Example 1, the only difference is that on the premise that the total molar amount of Formula 1 and Formula 2 remains unchanged, the molar synthesis ratio of Formula 1 to Formula 2 in Step 2 is changed to 2:1 and 3:1 respectively. Other operations and parameters are the same as those in Example 1. Measure the concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein, and calculate the leaching rate (see Table 6).

[0067] Table 6

[0068]

[0069] Example 6:

[0070] Compared with Example 1, the only difference is that the mass ratio of the waste lithium battery cathode material powder to the prepared synergistic leaching agent in Step 3 is changed to 1:3 g / g, 1:5 g / g, and 1:25 g / g respectively. Other operations and parameters are the same as those in Example 1. Measure the concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein, and calculate the leaching rate (see Table 7).

[0071] Table 7

[0072]

[0073] Example 7:

[0074] Compared with Example 1, the only difference is that when preparing the synergistic leaching agent in Step 2, additive B is replaced with an equimolar amount of Formula 3, and other components, operations, and parameters are the same as those in Example 1. Measure the concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein, and calculate the leaching rate (see Table 8).

[0075] Table 8

[0076] Metal type Li Ni Co Mn Leaching rate 88.45％ 53.13％ 74.12％ 81.71％

[0077] Comparative Example 1:

[0078] Compared with Example 1, the difference is only that when preparing the co-leaching agent in Step 2, additive C is missing, and other components, operations, and parameters are the same as in Example 1. Measure the concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein, and calculate the leaching rate (see Table 9).

[0079] Table 9

[0080] Metal type Li Ni Co Mn Leaching rate 35.19％ 13.38％ 16.84％ 23.77％

[0081] Comparative Example 2:

[0082] Compared with Example 1, the difference is only that when preparing the co-leaching agent in Step 2, ethanol or ethylene glycol with an equimolar amount is used as additive C, and other components, operations, and parameters are the same as in Example 1. Measure the concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein, and calculate the leaching rate (see Table 10).

[0083] Table 10

[0084]

[0085] Comparative Example 3

[0086] Compared with Example 1, the difference is only that additive A is missing, and the missing share is supplemented with an equimolar amount of additive B, and other operations and parameters are the same as in Example 1. The results are shown in Table 11

[0087] Table 11

[0088] Metal type Li Ni Co Mn Leaching rate 73.49％ 66.97％ 64.89％ 61.18％

[0089] Comparative Example 4

[0090] Compared with Example 1, the difference is only that additive B is missing, and the missing share is supplemented with an equimolar amount of additive A, and other operations and parameters are the same as in Example 1. The results are shown in Table 12

[0091] Table 12

[0092] Metal type Li Ni Co Mn Leaching rate 27.01％ 2.58％ 2.38％ 2.82％

[0093] In summary, the innovative research of the present invention shows that the additives A, B, and C with the described structure can achieve synergy based on the special hydrogen bond interaction between the components. Together with the component ratio and viscosity control therein, the lattice disintegration effect of the cathode material can be synergistically improved. In addition, based on the innovative use of the described synergistic leaching agent, further combined with the joint control of the leaching temperature, solvent dosage, and time, the leaching and recovery effect of the cathode material can be further improved. The process of the present invention is green and environmentally friendly, and can effectively control the generation of three wastes.

Claims

1. A method for recycling waste cathode materials, characterized in that, Mix additive A, additive B, and additive C to obtain a synergistic leaching agent; then mix the waste cathode material with the synergistic leaching agent for leaching treatment to recover a leaching solution enriched with metal elements in the cathode material. The additive A is a compound having the structure of Formula 1. The additive B is a compound having the structure of Formula 2 and / or Formula 3. Additive C is water. The viscosity of the synergistic leaching agent is 70 - 600 mPa·s; and the molar ratio of additive A to additive B therein is 0.9 - 2.5:

1. During the leaching process, the weight ratio of the synergistic leaching agent to the waste cathode material is above 6, the leaching temperature is above 50 °C, and the leaching time is above 6 h.

2. The recycling method of the cathode material of waste lithium-ion batteries according to claim 1, characterized in that, The waste cathode material is an electrode material stripped from the cathode of a waste lithium-ion battery.

3. The recycling method of the cathode material of waste lithium-ion batteries according to claim 2, wherein, The waste cathode material includes at least one waste active material among LiXO2, LiY2O2, and LiZPO4; X and Y each independently include at least one of Ni, Co, and Mn; Z includes at least one of Fe and Mn. Preferably, the waste cathode material is also allowed to contain at least one of a conductive agent, a binder, and a negative electrode material. Preferably, the content of the waste active material in the waste cathode material is above 50 wt%.

4. The recycling method of the cathode material of waste lithium-ion batteries according to any one of claims 1 to 3, characterized in that, Mix the additive A, additive B, and additive C evenly with the assistance of stirring. Preferably, the stirring speed is 300 - 500 rpm. Preferably, the temperature of the system is controlled at 50 °C - 80 °C during the mixing stage, preferably 55 °C - 60 °C. Preferably, the additive B is of Formula 2, and the molar ratio of additive A to additive B is 0.9 - 1.2:1, preferably 1 - 1.1:

1. Alternatively, additive B is of Formula 3, and the molar ratio of additive A to additive B is 1.9 - 2.2:1, preferably 2 - 2.1:

1.

5. The recycling method of the cathode material of waste lithium-ion batteries according to any one of claims 1 to 3, characterized in that, The viscosity of the synergistic leaching agent is 75 - 550 mPa·s, and more preferably 440 - 460 mPa·s.

6. The recycling method of the cathode material of waste lithium-ion batteries according to any one of claims 1 to 3, characterized in that, During the leaching process, the weight ratio of the synergistic leaching agent to the waste cathode material is above 10, preferably 10 - 25:

1.

7. The recycling method of the waste lithium ion battery cathode material according to any one of claims 1 to 3, characterized in that, During the leaching process, the leaching temperature is above 60 °C, preferably 60 - 80 °C.

8. The recycling method of the cathode material of waste lithium-ion batteries according to any one of claims 1 to 3, characterized in that, The leaching stage is carried out with the assistance of stirring. Preferably, the stirring speed is 300 - 550 rpm. Preferably, the leaching time is above 8 h, preferably 10 - 20 h.

9. The recycling method of the cathode material of waste lithium-ion batteries according to claim 1, characterized in that, After the leaching is completed, perform solid-liquid separation to obtain the leaching solution.

10. The recycling method of the cathode material of waste lithium-ion batteries according to claim 9, characterized in that, Before solid-liquid separation, add water to the system to assist in the filtration and separation of the leaching solution. Preferably, the added water is more than 2 times the volume of the synergistic leaching agent, preferably 2 - 10:1.

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