Method for recovering valuable metals in positive electrode material of waste lithium ion battery by ternary deep eutectic solvent

Abstract

The present application belongs to the technical field of lithium battery recycling, and particularly relates to a method for recycling valuable metals in a positive electrode material of a waste lithium ion battery by using a ternary deep eutectic solvent. The present application comprises preparation of a novel deep eutectic solvent and leaching of the positive electrode material of the waste lithium ion battery. By designing a novel deep eutectic solvent with low viscosity, the viscosity of the deep eutectic solvent is improved, thereby improving the leaching efficiency of the positive electrode material of the waste lithium ion battery. The low-viscosity ternary deep eutectic solvent system formed by guanidine hydrochloride, formic acid and L-tartaric acid can quickly and efficiently leach metal ions in the positive electrode material of the waste lithium ion battery at low temperature and in a short time. The process flow of the system has the advantages of rapid efficiency, low cost and the like.

Description

Technical Field

[0001] This invention belongs to the field of waste lithium-ion battery recycling and processing, and relates to a method for recovering valuable metals from the cathode material of waste lithium-ion batteries using a ternary deep eutectic solvent. Background Technology

[0002] Lithium-ion batteries are widely used due to their advantages, but they generate a large amount of waste batteries after reaching their lifespan. It is predicted that 11 million tons of waste will be generated by 2030. Waste lithium-ion batteries contain large amounts of metals and toxic substances, making their recycling both economically valuable and environmentally necessary. Currently, common methods for recycling waste lithium-ion batteries include pyrometallurgy and hydrometallurgy. Pyrometallurgy often uses carbothermic reduction, sulfation roasting, or chlorination roasting, which inevitably produces waste gas and pollution. Therefore, to address the shortcomings of pyrometallurgy, attention has turned to hydrometallurgy. Traditional hydrometallurgy often uses inorganic acids and reducing agents for leaching, most typically sulfuric acid to leach metals from the cathode material of waste lithium-ion batteries. While this method reduces waste gas and pollution compared to pyrometallurgy, it still generates water pollution. Therefore, researchers are considering developing a low-pollution leaching agent for hydrometallurgy. Deep eutectic solvents are a low-cost, low-pollution solvent with good solubility for metal oxides. Research on using DES leaching of cathode materials in the recycling of waste lithium-ion batteries is becoming increasingly active.

[0003] Current research on DES leaching of active materials in LIBs cathode materials reveals that different types of DES have varying abilities to leach metal elements from the cathode materials. High temperatures or prolonged heating and stirring are often required to achieve excellent leaching efficiency, increasing time costs and energy consumption. Therefore, developing novel DES for low-temperature, short-time, and efficient leaching of active materials in cathode materials is essential. Summary of the Invention

[0004] This invention aims to provide a method for recovering valuable metals from waste lithium-ion battery cathode materials using a deep eutectic solvent. This deep eutectic solvent can efficiently recover valuable metals such as lithium, nickel, cobalt, and manganese from waste lithium-ion battery cathode materials at low temperatures and in a short time.

[0005] The method for leaching waste lithium-ion battery cathode materials using a deep eutectic solvent in this invention is carried out according to the following steps: 1. Add hydrogen bond acceptor (guanidine hydrochloride), hydrogen bond donor (formic acid) and (L-tartaric acid) to a round-bottom flask in a molar ratio of 1:4:(0.1~0.9), and heat and stir at 80 °C until a homogeneous and clear deep eutectic solvent (DES) is obtained. II. In the leaching experiment, the waste positive electrode material LiNi was used. 0.5 Co0.2 Mn 0.3 O2 is added to DES and transferred to a round-bottom flask; the solid-liquid mass ratio of waste cathode material to DES is 0.5~2.5 / 50 (g / g). The round-bottom flask equipped with a condenser is placed in an oil bath and stirred at 450 rpm at 70~130 ℃ for 40~120 min to leach out the metal elements in the waste cathode material, obtaining a leachate.

[0006] 3. Filter the leachate from step 2 to obtain a filtrate containing lithium, nickel, cobalt and manganese. After dilution, determine the content of lithium, nickel, cobalt and manganese in the filtrate.

[0007] Furthermore, the molar ratio of hydrogen bond acceptor (guanidine hydrochloride), hydrogen bond donor (formic acid), and (L-tartaric acid) is 1:4:0.3-0.5; even further, the molar ratio is 1:4:0.3. Furthermore, the solid-liquid mass ratio of the waste cathode material to DES is 1 / 50.

[0008] Furthermore, the leaching temperature is 110-130℃.

[0009] Furthermore, the leaching time is 100-120 minutes.

[0010] In a specific embodiment of the present invention, under optimal conditions, LiNi 0.5 Co 0.2 Mn 0.3 The leaching efficiencies of valuable metals lithium, nickel, cobalt, and manganese in the O2 cathode active material are 98.61%, 98.21%, 98.61%, and 96.41%, respectively.

[0011] The aforementioned ternary deep eutectic solvent can also be used for the recycling of cathode materials such as lithium cobalt oxide, or other proportions of ternary cathode materials such as NCM111, NCM622, and NCM811 lithium batteries.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: the deep eutectic solvent system formed by the present invention can rapidly and efficiently leach metal ions from waste lithium-ion battery cathode materials at low temperature and in a short time. The process of this system is characterized by rapid efficiency, low cost, and rapid and efficient leaching of lithium, nickel, cobalt and manganese. Attached Figure Description

[0013] Figure 1 This is a process flow diagram of the method for recovering waste lithium-ion battery cathode materials using deep eutectic solvents according to the present invention; Figure 2 The leaching efficiency of the cathode material leached by the deep eutectic solvent in Example 1 under the condition of a molar ratio of guanidine hydrochloride:formic acid:L-tartaric acid 1:4:(0.1~0.9) was measured. Figure 3 The leaching efficiency of the cathode material was measured under different temperature (70~130 ℃) conditions using a deep eutectic solvent and cathode material in Example 2. Figure 4 The leaching efficiency of the cathode material was determined by leaching deep eutectic solvent and cathode material under different solid-liquid ratios (0.5~2.5 / 50) (g / g) in Example 3. Figure 5 The leaching efficiency of the cathode material under different time (40~120 min) conditions was measured using a deep eutectic solvent and the cathode material in Example 4. Figure 6 The leaching efficiency of the cathode material under optimal conditions is shown in Comparative Example 2. Detailed Implementation

[0014] To clarify the objectives and technical solutions of this invention, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0015] The present invention will be further illustrated below with reference to the experimental examples: In the following specific embodiments, the positive electrode material used for leaching is obtained by calcining at 500°C for 1 hour in a muffle furnace at a heating rate of 5 °C / min, resulting in a positive electrode active material, LiNi, that detaches from the current collector aluminum foil. 0.5 Co 0.2 Mn 0.3 O2. Example 1

[0016] The effects of hydrogen bond acceptors (guanidine hydrochloride) and hydrogen bond donors (formic acid and L-tartaric acid) in deep eutectic solvents on the leaching efficiency of cathode materials under different molar ratios were investigated. 1. Add guanidine hydrochloride, formic acid and L-tartaric acid to a round-bottom flask in a molar ratio of 1:4:(0.1~0.9), heat and stir at 80°C until homogeneous and clear to obtain DES; II. In the leaching experiment, the waste cathode material was added to the DES in step (I). The waste cathode material and DES were added to a round-bottom flask at a solid-liquid ratio of 1 / 50 (g / g). The round-bottom flask equipped with a condenser was placed in an oil bath and the waste cathode material was leached at a stirring speed of 450 rpm and a leaching temperature of 80 ℃ for 60 min to obtain the leachate.

[0017] 3. Filter the leachate from step 2 to obtain leachate.

[0018] IV. The content of lithium, nickel, cobalt, and manganese in the filtered leachate was tested, and the results are shown in [the table below]. Figure 2 Experimental results show that the maximum leaching efficiency is achieved under the condition of a molar ratio of guanidine hydrochloride: formic acid: L-tartaric acid = 1:4:0.3. Example 2

[0019] The effect of deep eutectic solvent and cathode material on leaching efficiency under different temperatures (70~130 ℃) was investigated. 1. Guanidine hydrochloride, formic acid and L-tartaric acid were added to a round-bottom flask in a molar ratio of 1:4:0.3, and heated and stirred at 80 °C until homogeneous and clear to obtain DES; 2. Waste cathode material and DES were added to a round-bottom flask at a solid-liquid ratio of 1 / 50 (g / g). The round-bottom flask equipped with a condenser was placed in an oil bath and stirred at a fixed speed of 450 rpm for 60 min at a temperature of 70-130 ℃ to leach the waste cathode material, obtaining a leachate. The leachate was filtered, and the metal element content in the leachate was analyzed. The experimental results showed that the maximum leaching efficiency was achieved at an oil bath temperature of 110 ℃. Figure 3 ). Example 3

[0020] The effect of deep eutectic solvent and cathode material on leaching efficiency under different solid-liquid ratios was investigated: The preparation of DES was the same as in Example 2, and the stirring speed and leaching time in the leaching experiment were also the same as in Example 2. The leaching oil bath temperature was the optimal temperature of 110℃ selected in Example 2. The solid-liquid mass ratio of cathode material to DES was (0.5~2.5) / 50 (g / g). The results of the metal element content in the leaching solution are shown below. Figure 4 In this embodiment, the optimal solid-liquid ratio was determined to be 1 / 50 (g / g). Example 4

[0021] Based on the optimal DES solvent ratio, optimal solid-liquid ratio, and leaching temperature screened in Examples 1-3 above, the effects of deep eutectic solvent and cathode material on leaching efficiency under different time conditions (40-120 min) were further investigated. The results are shown in […]. Figure 5 Experimental results show that the leaching efficiency does not change significantly after 100 min. To reduce energy consumption, 100 min is selected as the optimal leaching time. Comparative Example 1

[0022] Following the method in Example 1, L-tartaric acid was replaced with oxalic acid to prepare DES, which was then used to leach waste cathode materials. After leaching, solids were produced, but their metal content was not further determined. Comparative Example 2

[0023] In this comparative example, the deep eutectic solvent consisted of guanidine hydrochloride and L-tartaric acid, with the molar amount of hydrogen ions in L-tartaric acid being the same as the molar amount of hydrogen ions from the hydrogen bond donor under optimal conditions, which was 9.8 mol. Guanidine hydrochloride and L-tartaric acid were added to a round-bottom flask at a molar ratio of 1:1.63, and the mixture was heated and stirred at 110 °C until a homogeneous and clear deep eutectic solvent was obtained. Under the same optimal conditions (solid-liquid ratio 1 / 50 (g / g), leaching temperature 110 °C, and stirring for 100 min), the cathode material was leached. The leaching efficiencies for lithium, nickel, cobalt, and manganese were 66.38%, 58.97%, 65.52%, and 53.71%, respectively. The results are shown in [Figure number missing]. Figure 6 .

[0024] As will be readily understood by those skilled in the art, the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recovering valuable metals from waste lithium-ion battery cathode materials using a deep eutectic solvent, characterized in that, Includes the following steps: (1) Preparation of deep eutectic solvent; the deep eutectic solvent is formed by mixing guanidine hydrochloride, hydrogen bond acceptor, formic acid, and L-tartaric acid, and heating and stirring until clear; the molar ratio of guanidine hydrochloride to formic acid and L-tartaric acid is 1:4:0.3~0.5; (2) The waste positive electrode material LiNi x Co y Mn 1-x-y O2 is mixed with a deep eutectic solvent and heated and stirred in an oil bath to obtain an extract. (3) Filter the leachate from step (2) to obtain a leachate containing lithium, nickel, cobalt and manganese.

2. The method for recovering valuable metals from waste lithium-ion battery cathode materials using deep eutectic solvents according to claim 1, characterized in that, The heating temperature in step (1) is 80~90℃.

3. The method for recovering valuable metals from waste lithium-ion battery cathode materials using deep eutectic solvents according to claim 1, characterized in that, The heating and stirring temperature of the waste cathode material and the deep eutectic solvent is 70 ℃~130 ℃.

4. The method for recovering valuable metals from waste lithium-ion battery cathode materials using deep eutectic solvents according to claim 1, characterized in that, The heating and stirring time for waste cathode material and deep eutectic solvent is 40 min to 120 min.

5. The method for recovering valuable metals from waste lithium-ion battery cathode materials using deep eutectic solvents according to claim 1, characterized in that, The mass ratio of waste cathode material to deep eutectic solvent is 0.5~2.5:50.

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