A method for selectively extracting lithium from spent lithium battery cathode material

Abstract

The present application relates to harmless treatment technology field of waste lithium ion battery, specifically disclose a kind of method for selectively extracting lithium from waste lithium battery positive material, comprising the following steps: waste lithium ion battery positive plate is crushed, sieved, and positive material is obtained;The obtained positive material is mixed with reducing reagent and water in proportion, and then hydrothermal reaction is carried out;The residue after hydrothermal reaction is washed and filtered, and high-purity lithium-containing aqueous solution and transition metal oxide are obtained.The present application uses reducing reagent to react with positive material, converts high-valence transition metal ions into low-valence state, and finally transition metal ions exist in the form of oxide, which is easy to be dissolved and recovered subsequently, and high-purity lithium-containing aqueous solution is obtained, which effectively avoids the risk of environmental pollution.

Description

A method for selectively extracting lithium from waste lithium battery cathode materials Technical Field

[0001] This invention relates to the field of harmless treatment technology for waste lithium-ion batteries, and in particular to a method for selectively extracting lithium from waste lithium battery cathode materials. Background Technology

[0002] Lithium-ion batteries (LIBs) hold the largest share of power supply in portable electronics, electric vehicles, and energy storage due to their high energy density, wide operating temperature range, and excellent cycle performance. However, the lifespan of lithium-ion batteries is only 3-5 years, resulting in a large amount of waste LIBs. Besides lithium (Li), waste LIBs also contain hazardous organic chemicals, plastics, and heavy metals (such as Ni, Mn, etc.). Li, a key element in LIB manufacturing, is derived from natural mineral resources, characterized by low ore grades, insufficient mineable reserves, and high extraction costs. Due to the scarcity of Li, recycling LIB batteries is urgent. The content of the key metallic element Li in LIBs is higher than in ores; recovering Li from waste lithium-ion batteries can meet the growing demand and is a means to promote the sustainable development of the lithium-ion battery new energy industry. The recovery of valuable metals from waste LIBs is receiving increasing attention due to its significant social and economic benefits and global sustainability.

[0003] Currently, recycling strategies for waste lithium-ion batteries include hydrometallurgy, pyrometallurgy, and biometallurgy. Hydrometallurgy typically involves leaching and reduction, and is further divided into acid leaching and bioleaching based on the leaching method. For acid leaching, some inorganic acids (such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid) have good extraction effects on lithium and other metal ions, but excessive acid and alkali consumption can cause secondary pollution and easily corrode equipment. Therefore, some mild organic acids (such as oxalic acid, citric acid, and tartaric acid) have been studied. Hydrometallurgy offers high recovery efficiency, good selectivity, and mild reaction conditions, but still suffers from drawbacks such as generating secondary waste and cumbersome procedures. Pyrometallurgical processes are usually carried out at temperatures above 1000℃, with fast reaction rates and good adaptability to complex compositions, and are adopted by many companies. However, they suffer from high energy consumption, emissions of harmful gases, lithium loss during the recycling process, and strict requirements on processing equipment. Recent research has focused on selectively extracting Li through reduction roasting methods, such as carbon, acid, or salt-assisted roasting, but the environmental impact and energy consumption issues of this process still need to be addressed. Therefore, there is an urgent need for a green, low-energy and sustainable technology for the selective extraction of Li. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the existing technology and provide a method for selectively extracting lithium from waste lithium battery cathode materials. The method involves separating and enriching cathode materials from waste lithium-ion battery cathode sheets through physical treatments such as crushing and sieving. Then, a reducing agent is used in a hydrothermal reaction to reduce lithium ions in the waste lithium battery cathode materials to water-soluble lithium compounds, thereby releasing lithium ions from the cathode materials and achieving selective lithium extraction, which facilitates subsequent recycling.

[0005] To achieve the above objectives, the technical solution of the present invention is: a method for selectively extracting lithium from waste lithium battery cathode materials, comprising the following steps:

[0006] (1) The waste lithium-ion battery positive electrode sheet is crushed and screened to obtain positive electrode material;

[0007] (2) The positive electrode material obtained in step (1) is mixed with the reducing agent in proportion and added to the reaction vessel, and then water is added to carry out hydrothermal reaction;

[0008] (3) The residue after the hydrothermal reaction in step (2) is washed and filtered with water to obtain a high-purity lithium-containing aqueous solution and transition metal oxides.

[0009] Specifically, at a certain temperature, a reducing agent reacts with the cathode material, converting high-valence transition metal ions into low-valence ones, accompanied by delithiation. This invention utilizes a reducing agent to reduce and separate lithium ions from waste lithium-ion battery cathode materials, effectively recovering metal ions from spent lithium-ion batteries and utilizing cathode materials as resources, while effectively avoiding the environmental pollution risks posed by cathode materials. This method relies on widely used industrial hydrothermal treatment technology, is simple to operate, easy to scale up, and has broad industrial application potential.

[0010] In a preferred embodiment of the present invention, the crushing speed in step (1) is 1000-2000 rpm and the crushing time is 5-30 min.

[0011] In a preferred embodiment of the present invention, the mesh size of the sieve in step (1) is greater than 100 mesh.

[0012] In a preferred embodiment of the present invention, the cathode material in steps (1) and (2) is one or more of lithium cobalt oxide, ternary lithium, and lithium manganese oxide.

[0013] In a preferred embodiment of the present invention, the reducing agent in step (2) is one or more of zinc powder, aluminum powder, hydrazine hydrate, and ethylene glycol.

[0014] In a preferred embodiment of the present invention, the molar ratio of the positive electrode material, reducing agent and water in step (2) is 1:(1.2-2.0):(160-180).

[0015] Since the added reducing agent is for the purpose of reducing and recovering the cathode material, if the proportion of the reducing agent added is too low, the reduction and conversion effect will be poor; if the proportion added is too high, it will affect the subsequent recovery of metal elements in the cathode material.

[0016] In a preferred embodiment of the present invention, the temperature of the hydrothermal reaction in step (2) is 250-350°C and the reaction time is 2-3 hours.

[0017] In a preferred embodiment of the present invention, the water filling rate in the reactor in step (2) is 40-60 vol%.

[0018] In a preferred embodiment of the present invention, the solid-liquid ratio (the ratio of the residue of the hydrothermal reaction to the water used for washing) in step (3) is 100-200 g / L.

[0019] In a preferred embodiment of the present invention, the water washing and filtration time in step (3) is 20-40 min.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The hydrothermal reduction treatment technology used in this invention can effectively improve the lithium extraction efficiency of cathode materials, reduce the reaction energy barrier, and release lithium ions in the cathode materials, which is conducive to recycling.

[0022] 2. This invention uses a reducing agent to react with the cathode material to convert high-valence transition metal ions into low-valence transition metal ions. The final transition metal ions exist in the form of oxides, which are easy to dissolve and recover in the future, and a high-purity lithium-containing aqueous solution is obtained, effectively avoiding the risk of environmental pollution. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships shown in the drawings in the following description are based on the direction in which the components are drawn in the figure.

[0024] Figure 1 is a process route diagram of the method for extracting lithium ions from the cathode material of the present invention;

[0025] Figure 2 shows the XRD patterns of ZnO and transition metal oxide (Mn3O4) separated in Example 1 of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0027] Example 1

[0028] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0029] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and after multi-stage sieving, obtain positive electrode material LiMn2O4 powder (>100 mesh);

[0030] 2. The obtained positive electrode material LiMn2O4, zinc powder, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 300℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0031] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 96.37 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0032] Figure 2 shows the XRD patterns of ZnO and transition metal oxide (Mn3O4) separated in Example 1 of this invention. As can be seen from the figure, after the hydrothermal reaction, lithium ions in the cathode material are released and react with mOH. - They combine to form water-soluble lithium salts.

[0033] Example 2

[0034] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0035] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and after multi-stage sieving, obtain positive electrode material LiMn2O4 powder (>100 mesh);

[0036] 2. The obtained positive electrode material LiMn2O4, aluminum powder, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 300℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0037] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 92.71 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0038] Example 3

[0039] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0040] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and after multi-stage sieving, obtain positive electrode material LiMn2O4 powder (>100 mesh);

[0041] 2. The obtained positive electrode material LiMn2O4, iron powder, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 300℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0042] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 88.02 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0043] Example 4

[0044] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0045] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and after multi-stage sieving, obtain positive electrode material LiMn2O4 powder (>100 mesh);

[0046] 2. The obtained positive electrode material LiMn2O4, N2H4, and distilled water were added to the reactor in a molar ratio of 10:15:1675. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 300℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0047] 3. The residue after the reaction was washed and filtered to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 96.59 wt%. The solid-liquid ratio used for washing and filtration was 200 g / L, and the washing and filtration time was 30 min.

[0048] Example 5

[0049] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0050] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and after multi-stage sieving, obtain positive electrode material LiMn2O4 powder (>100 mesh);

[0051] 2. The obtained positive electrode material LiMn2O4, zinc powder, and distilled water were added to the reactor in a molar ratio of 10:20:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 300℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0052] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 98.54 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0053] Example 6

[0054] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0055] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and after multi-stage sieving, obtain positive electrode material LiMn2O4 powder (>100 mesh);

[0056] 2. The obtained positive electrode material LiMn2O4, zinc powder, and distilled water were added to the reactor in a molar ratio of 10:12:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 300℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0057] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 80.07%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0058] Example 7

[0059] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0060] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and then sieve them through multiple stages to obtain positive electrode material powder (>100 mesh);

[0061] 2. The obtained positive electrode material LiMn2O4, zinc powder, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 250℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0062] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 84.80 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0063] Example 8

[0064] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0065] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and then sieve them through multiple stages to obtain positive electrode material powder (>100 mesh);

[0066] 2. The obtained positive electrode material LiMn2O4, zinc powder, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 350℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0067] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 99.08 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0068] Example 9

[0069] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0070] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and then sieve them through multiple stages to obtain positive electrode material powder (>100 mesh);

[0071] 2. The obtained positive electrode material LiCoO2, zinc powder, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After being mixed evenly, a hydrothermal reaction was carried out. The heating rate was 10℃ / min, the reaction temperature was 300℃, the reaction time was 2h, and the water filling rate in the reactor was 50 vol%.

[0072] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 92.97 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0073] Example 10

[0074] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0075] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and after multi-stage sieving, obtain positive electrode material NCM powder (>100 mesh);

[0076] 2. The obtained positive electrode material NCM, zinc powder, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After being mixed evenly, a hydrothermal reaction was carried out. The heating rate was 10℃ / min, the reaction temperature was 300℃, the reaction time was 2h, and the water filling rate in the reactor was 50 vol%.

[0077] 3. The residue after the reaction was washed and filtered to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 94.40 wt%. The solid-liquid ratio used for washing and filtration was 200 g / L, and the washing and filtration time was 30 min.

[0078] Example 11

[0079] This embodiment provides a method for selectively extracting lithium from waste lithium battery cathode materials. Referring to the process route in Figure 1, the method includes the following steps:

[0080] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and after multi-stage sieving, obtain positive electrode material LiMn2O4 powder (>100 mesh);

[0081] 2. The obtained positive electrode material LiMn2O4, zinc powder, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 300℃, a reaction time of 3h, and a water filling rate of 50 vol%.

[0082] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 98.27 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0083] Comparative Example 1

[0084] This comparative example provides a method for selectively extracting lithium from waste lithium-ion battery cathode materials, comprising the following steps:

[0085] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and then sieve them through multiple stages to obtain positive electrode material powder (>100 mesh);

[0086] 2. The obtained positive electrode material LiMn2O4, graphite, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 300℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0087] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions respectively. The final lithium extraction rate was 0.00 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0088] In this comparative example, graphite was used as a reducing agent. However, due to the stable chemical properties of graphite, it did not react with the cathode material and thus failed to effectively extract lithium.

[0089] Comparative Example 2

[0090] This comparative example provides a method for selectively extracting lithium from waste lithium-ion battery cathode materials, comprising the following steps:

[0091] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and then sieve them through multiple stages to obtain positive electrode material powder (>100 mesh);

[0092] 2. The obtained positive electrode material LiMn2O4, zinc powder, and distilled water were added to the reactor in a molar ratio of 20:10:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 300℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0093] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 37.10 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0094] In this comparative example, due to the low amount of reducing agent used, the reduction and delithiation effects with the cathode material were poor, and lithium was not effectively extracted.

[0095] Comparative Example 3

[0096] This comparative example provides a method for selectively extracting lithium from waste lithium-ion battery cathode materials, comprising the following steps:

[0097] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and then sieve them through multiple stages to obtain positive electrode material powder (>100 mesh);

[0098] 2. The obtained positive electrode material LiMn2O4, zinc powder, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 150℃, a reaction time of 2h, and a water filling rate of 50 vol%.

[0099] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions, respectively. The final lithium extraction rate was 4.06%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0100] In this comparative example, the reaction temperature was too low, resulting in poor reduction and delithiation of the cathode material, and lithium was not effectively extracted.

[0101] Comparative Example 4

[0102] This comparative example provides a method for selectively extracting lithium from waste lithium-ion battery cathode materials, comprising the following steps:

[0103] 1. Disassemble waste lithium-ion batteries to obtain positive electrode sheets, then crush the positive electrode sheets at 1500 rpm for 10 minutes, and then sieve them through multiple stages to obtain positive electrode material powder (>100 mesh);

[0104] 2. The obtained positive electrode material LiMn2O4, zinc powder, and distilled water were added to the reactor in a molar ratio of 10:15:1709. After uniform mixing, a hydrothermal reaction was carried out with a heating rate of 10℃ / min, a reaction temperature of 300℃, a reaction time of 10min, and a water filling rate of 50 vol% in the reactor.

[0105] 3. The residue after the reaction was washed and filtered with water to obtain transition metal oxides and lithium-rich solutions respectively. The final lithium extraction rate was 20.12 wt%. The solid-liquid ratio used for water washing and filtration was 200 g / L, and the water washing and filtration time was 30 min.

[0106] In this comparative example, the hydrothermal reaction time was too short, resulting in poor reduction and delithiation of the cathode material, and lithium was not effectively extracted.

[0107] In summary, this invention utilizes a reducing agent to undergo a hydrothermal reaction with the cathode material, achieving the reduction of the lithium-ion battery cathode material and the separation of lithium ions. This effectively recovers metal ions from spent lithium-ion batteries, enabling resource utilization of the cathode material, while simultaneously avoiding the environmental pollution risks associated with the cathode material. This method relies on widely used industrial hydrothermal treatment technology, is simple to operate, easily scalable, and has broad industrial application potential.

[0108] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for selectively extracting lithium from waste lithium-ion battery cathode materials, characterized in that, The process includes the following steps: (1) crushing and sieving waste lithium-ion battery positive electrode sheets to obtain positive electrode material; the crushing speed is 1000-2000 rpm, the crushing time is 5-30 min, and the sieve mesh size is greater than 100 mesh; the positive electrode material is one or more of lithium cobalt oxide, ternary lithium, and lithium manganese oxide; (2) mixing the positive electrode material obtained in step (1) with a reducing agent in a certain proportion and adding it to a reaction vessel, then adding water to carry out a hydrothermal reaction; the molar ratio of the positive electrode material, reducing agent, and water is 1:(1.2-2.0):(160-180); the water filling rate in the reaction vessel is 40-60 vol%; the reducing agent is one or more of zinc powder, aluminum powder, and hydrazine hydrate; the temperature of the hydrothermal reaction is 250-350°C. ℃, reaction time is 2-3h; (3) the residue after hydrothermal reaction in step (2) is washed and filtered with water to obtain a high-purity lithium-containing aqueous solution and transition metal oxides; the solid-liquid ratio used for water washing and filtration is 100-200 g / L, and the water washing and filtration time is 20-40 min.

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