Method for selectively leaching lithium from waste lithium battery positive electrode powder by using pure water

Abstract

The invention belongs to the technical field of materials, and particularly relates to a method for selectively leaching lithium from waste lithium battery positive electrode powder by utilizing pure water, which comprises the following steps: filling waste ternary lithium battery (sNCM) positive electrode powder and water into a closed container, introducing oxygen with certain pressure intensity, and heating for a preset time at the temperature of 190-210 DEG C under a stirring condition to obtain a leaching mixture; the leaching mixture is filtered, and leaching liquid containing Li is obtained; carrying out evaporative crystallization on the leachate, and reacting for a preset time to obtain lithium hydroxide powder; adding a certain amount of manganese carbonate, nickel carbonate and cobalt carbonate into the leaching residues, and calcining together to prepare an NCM523 ternary precursor; the technological process is simple, no chemical reagent is used, no impurity is introduced in the leaching process, high-selectivity and high-leaching-rate lithium recovery can be achieved, no impurity is introduced in the process, no chemical reagent is used in the whole experiment process, no waste gas, waste water and waste are generated, and environment-friendly, pollution-free, short-process and green leaching can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, specifically relating to a method for selectively leaching lithium from waste lithium battery cathode powder using pure water. Background Technology

[0002] With the development of the global economy, the demand for petrochemical energy is increasing daily, while petrochemical resources are becoming increasingly depleted, and the environmental pollution caused by petrochemical energy is becoming increasingly serious. This makes the replacement of traditional vehicles with new energy electric vehicles an inevitable trend in historical development. The core of new energy vehicles is the power battery. Depending on the usage scenario, the battery life is 3-5 years. Therefore, a large number of power batteries will be scrapped in the future. Recycling and reusing power batteries not only aligns with the green and environmentally friendly positioning of new energy vehicles, but also facilitates the recycling of resources such as lithium and cobalt, reducing dependence on natural resources, which is of great significance. Currently, recycling technologies for waste lithium-ion batteries include pyrometallurgy, direct recycling, and hydrochemical extraction. Although pyrometallurgy is suitable for large-scale production due to its durability against complex chemical compositions, its low recovery rate and large gas emissions remain challenging. Direct recycling, aided by high-temperature calcination, retains the original structure and repairs damaged crystal lattices by replenishing the lithium source. However, persistent impurities and low-uniformity retired cathodes limit its application. In contrast, wet chemical extraction, a highly efficient method for directly recovering desired elements from spent lithium-ion batteries, is widely used in the metallurgical industry. However, these chemicals are often wasted and generate significant secondary pollution.

[0003] Furthermore, the large-scale consumption of chemicals reduces the circular economy. In traditional acid leaching processes, several inorganic acids (H2SO4, H3PO4, or HNO3) are often used to decompose spent ternary lithium batteries (sNCM) and promote efficient metal extraction. To ensure high leaching efficiency of Li, the acid supplied must be in large excess, which increases the recycling cost of sNCM. Compared to inorganic acid leaching processes, a leaching strategy combining a reducing agent with weak organic acids such as formic acid, acetic acid, or citric acid can achieve selective and efficient lithium extraction. This acid / reduction synergistic leaching system significantly reduces acid consumption while improving the selectivity of the leaching process. However, the organic wastewater generated after treatment may pose more complex follow-up treatment challenges than traditional methods. Therefore, to achieve sustainable and waste-free sNCM material recycling, the industry still needs to focus on developing green, efficient, and atom-economically sound next-generation recycling technologies.

[0004] Current research largely focuses on treating sNCM materials using a single leaching agent (such as ammonium sulfite or ammonium bicarbonate). Although high lithium leaching efficiency is achieved under low solid-liquid ratio conditions, the oxidizing power of SO3... 2-The inability to directly convert these into final lithium products results in low atom economy for the overall process. Furthermore, the introduction of soluble cations (such as NH4+) during the leaching process... + This can lead to the co-leaching of transition metals such as nickel, cobalt, and manganese in sNCM, thereby increasing the complexity of subsequent separation and purification.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of long leaching time, low efficiency, excessive use of chemical reagents, and polluting wastewater generation in the recovery of precious metals from lithium-ion battery cathode powder. It provides a method for selectively leaching lithium from waste lithium-ion battery cathode powder using pure water. This method achieves precise recovery of lithium metal from lithium-ion battery cathode powder through highly selective leaching of lithium metal from the battery cathode black powder. Pure water and oxygen can replace chemical reagents as effective leaching and reducing agents, enabling efficient leaching of lithium from NCM within a short time (120 minutes) and with a simple process flow. This eliminates the need for chemicals and processes, achieving precise extraction of lithium metal. It also avoids extraction and multi-stage separation processes, reducing wastewater discharge.

[0007] This invention provides a method for selectively leaching lithium from waste lithium battery cathode powder using pure water, characterized by the following steps: Step S1: Put the waste ternary battery positive electrode powder and water into a sealed container, introduce oxygen at a certain pressure, and heat for a predetermined time at a temperature of 190℃-210℃ with stirring to obtain a leaching mixture. Step S2: Filter the leaching mixture to obtain a leaching solution containing Li; Step S3: Evaporate the leachate to crystallize it, and react for a predetermined time to obtain lithium hydroxide powder. The method for highly selectively leaching lithium metal from battery cathode powder using pure water provided by the present invention may also have the following feature: wherein the solid-liquid ratio of pure water to waste ternary battery cathode powder is 30g / L~35g / L.

[0008] The method for highly selectively leaching lithium metal from battery cathode powder using pure water provided by the present invention may also have the following feature: in step S1, waste ternary battery cathode powder and water are placed into a sealed container and heated for 120 min to 360 min under stirring conditions of 210°C, oxygen pressure of 0.2 MPa to 0.5 MPa, and rotation speed of 300 r / min to 400 r / min to obtain a leaching mixture.

[0009] The method for highly selectively leaching lithium metal from battery cathode powder using pure water provided by the present invention may also include the following feature: Step S4: Add a certain amount of nickel carbonate, cobalt carbonate, and manganese carbonate to the leaching residue and calcine them together to produce NCM. 523 Ternary precursor; The method for highly selectively leaching lithium metal from battery cathode powder using pure water provided by the present invention may also have the following feature: the mass ratio of the dried filter residue, nickel carbonate, cobalt carbonate, and manganese carbonate is 1:0.5:0.3:0.5.

[0010] The role and effect of invention This invention provides a method for selectively leaching lithium from waste lithium battery cathode powder using pure water. This method recovers precious metals from ternary lithium battery cathode powder using pure water, abandoning the traditional method of using strong acids and reducing agents to dissolve and recover precious metals. No acid or reducing agent is used in the leaching process, and the layered structure of the leaching residue is well preserved. If unused lithium-ion batteries are used, the leaching residue can be directly used as a ternary precursor. The leachate can be evaporated and crystallized to obtain pure lithium hydroxide powder. The preparation cycle is short and suitable for industrial production.

[0011] Furthermore, this invention avoids the problems of polluting wastewater caused by traditional methods of recovering precious metals using pure water directly from the cathode powder, as it does not introduce other elements during the leaching process, which is beneficial for improving the overall recovery of subsequent parts.

[0012] Furthermore, this invention uses heating and applying oxygen pressure to fuse oxygen with water, causing water to ionize into hydrogen ions and hydroxide ions. The hydrogen ions enter the layered structure of the ternary cathode material, displacing lithium ions and replacing lithium sites. The ternary structure is still preserved after leaching.

[0013] Furthermore, this invention utilizes the property that transition metals (nickel, cobalt, manganese) are not easily soluble in water due to their high valence. By using the oxidizing properties of pure water to inhibit the transition metals from changing from high valence to low valence and thus entering the solution, lithium is separated from other metals, resulting in a good selective leaching effect.

[0014] To achieve high atom economy, high selectivity, and zero-waste recycling in sNCM, this invention designs a "built-in anion" strategy. The core of this strategy lies in enabling reducing anions (such as OH⁻, CO₃²⁻, etc.) to precisely match the leached Li⁺ in the oxidative leaching environment, directly forming the final lithium products (such as Li₂CO₃ or LiOH). Simultaneously, it inhibits the dissolution of transition metals to lower valence states, thereby avoiding co-leaching of impurity metals, simplifying subsequent processes, and significantly improving atom utilization efficiency.

[0015] Therefore, the preparation method of the present invention uses pure water to selectively leach lithium metal from battery cathode powder. It can also selectively leach lithium metal using oxygen and water, without introducing impurities. The entire experimental process does not use chemical reagents and generates no waste gas, wastewater or waste, achieving environmentally friendly, pollution-free, short-process green leaching. Attached Figure Description

[0016] Figure 1 This is a statistical chart showing the leaching effect at different temperatures in the embodiments of the present invention; Figure 2 This is a statistical chart of the leaching effect at different times in the embodiments of the present invention; Figure 3 This is an XRD pattern of the waste cathode material used in the embodiments of the present invention; Figure 4 These are XRD patterns of filter residue after leaching at different temperatures in embodiments of the present invention; Figure 5 This is the XRD pattern of the regenerated precursor in Embodiment 1 of the present invention. Detailed Implementation

[0017] To make the technical means, creative features, objectives and effects of this invention easy to understand, the following describes in detail the method of highly selectively leaching lithium metal from battery cathode powder with pure water, in conjunction with embodiments and accompanying drawings.

[0018] Unless otherwise specified, all raw materials used in this invention were purchased through normal commercial channels. All unmentioned testing standards are national standards.

[0019] The source information for some materials and instruments involved in the examples is as follows: Waste ternary lithium battery cathode powder was provided by Shandong Linyi Shengfeng Renewable Resources Co., Ltd. The metal ion standard solution (1000 mg / L) was from National Standard Testing & Certification Co., Ltd. The X-ray diffractometer (model D / Max−2550PC, manufactured by RIGAKU, Japan) and atomic absorption spectrometer (CW-1Y / 2F, Beijing Purkinje General Instrument Co., Ltd.) were also mentioned.

[0020] This invention provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, comprising the following steps: Step S1: Place the waste ternary battery positive electrode powder and water into a sealed container, introduce oxygen at a pressure of 0.5 MPa, and heat for 120 min to 360 min under stirring conditions at a temperature of 190℃~210℃ and a rotation speed of 400 r / min to obtain a leaching mixture.

[0021] In step S2, the leaching mixture is filtered to remove the filter residue, resulting in a leachate containing Li. The concentration of metal ions in the leachate obtained in step S2 is measured using flame atomic absorption spectrometry, and the calculated leaching efficiency is over 99%.

[0022] Step S3: Evaporate and crystallize the leachate to obtain lithium hydroxide powder; Step S4: Add a certain amount of manganese carbonate, nickel carbonate, and cobalt carbonate to the dried filter residue (leaching residue) obtained in step S2 and calcine them together to produce NCM. 523 Ternary precursors.

[0023] In step S1 above, the solid-liquid ratio of pure water to waste ternary battery cathode powder is 30 g / L.

[0024] In step S2 above, the filter residue containing Ni, Co, and Mn can be used as a precursor for regenerating new cathode materials.

[0025] In step S4 above, the mass ratio of the dried filter residue, nickel carbonate, cobalt carbonate, and manganese carbonate is 1:0.5:0.3:0.5.

[0026] <Example 1> This embodiment provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, the specific process of which is as follows: 4g of waste ternary cathode powder and 100mL of deionized water were mixed and added to a high-temperature and high-pressure reactor. The mixture was heated and stirred for 360min at 210℃, 400rpm, and 0.5MPa to obtain a black leaching mixture. The leaching mixture was then filtered using a vacuum filter to obtain a light yellow leachate and filter residue. The filter residue was dried in an oven. The filter residue mainly contained Ni, Co, and Mn.

[0027] By adding manganese carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate to the dried filter residue in a mass ratio of 1:0.5:0.3:0.5 and calcining at 500℃ for 2 h, oxides of Ni, Co, and Mn can be obtained, which can be used as precursors for regenerating new cathode materials. The resulting Li solution is then evaporated and crystallized to obtain LiOH powder.

[0028] The leaching rates of Li, Ni, Co, and Mn were calculated to be 94.36%, 0.13%, 0.05%, and 0.12%, respectively.

[0029] <Example 2> This embodiment provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, the specific process of which is as follows: Take 4g of waste ternary cathode powder and 100mL of deionized water and add them to a high-temperature and high-pressure reactor. Heat and stir for 240min at 210℃, 400rpm and 0.5Mpa to obtain a black leaching mixture. Filter the leaching mixture using a vacuum filter to obtain a light yellow leachate. Place the filter residue in an oven to dry.

[0030] By adding manganese carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate to Ni, Co, and Mn filter residue in a mass ratio of 1:0.5:0.3:0.5 and calcining at 500℃ for 2 h, oxides of Ni, Co, and Mn can be obtained, which can be used as precursors for regenerating new cathode materials. The resulting Li solution can be evaporated and crystallized to obtain LiOH powder.

[0031] The leaching rates of Li, Ni, Co, and Mn were calculated to be 99.78%, 0.001%, 0.01%, and 0.002%, respectively.

[0032] <Example 3> This embodiment provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, the specific process of which is as follows: Take 4g of waste ternary cathode powder and 100mL of deionized water and add them to a high-temperature and high-pressure reactor. Heat and stir for 120min at 170℃, 400rpm and 0.5Mpa to obtain a black leaching mixture. Filter the leaching mixture using a vacuum filter to obtain a light yellow leachate. Place the filter residue in an oven to dry.

[0033] By adding manganese carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate to Ni, Co, and Mn filter residue in a mass ratio of 1:0.5:0.3:0.5 and calcining at 500℃ for 2 h, oxides of Ni, Co, and Mn can be obtained, which can be used as precursors for regenerating new cathode materials. The resulting Li solution can be evaporated and crystallized to obtain LiOH powder.

[0034] Calculations show that the leaching rate of Li is 76.75%, while the leaching rates of Ni, Co, and Mn are all below 0.01% and can be ignored.

[0035] <Example 4> This embodiment provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, the specific process of which is as follows: Take 4g of waste ternary cathode powder and 100mL of deionized water and add them to a high-temperature and high-pressure reactor. Heat and stir for 240min at 170℃, 400rpm and 0.5Mpa to obtain a black leaching mixture. Filter the leaching mixture using a vacuum filter to obtain a light yellow leachate. Place the filter residue in an oven to dry.

[0036] By adding manganese carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate to a Ni, Co, and Mn filter residue in a mass ratio of 1:0.5:0.3:0.5 and calcining at 500℃ for 2 h, Ni, Co, and Mn oxides can be obtained, which can be used as precursors for regenerating new cathode materials. The resulting Li solution can be evaporated and crystallized to obtain LiOH powder.

[0037] Calculations show that the leaching rate of Li is 83.37%, while the leaching rates of Ni, Co, and Mn are all below 0.01% and can be ignored.

[0038] <Example 5> This embodiment provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, the specific process of which is as follows: Take 4g of waste ternary cathode powder and 100mL of deionized water and add them to a high-temperature and high-pressure reactor. Heat and stir for 360min at 170℃, 400rpm and 0.5Mpa to obtain a black leaching mixture. Filter the leaching mixture using a vacuum filter to obtain a light yellow leachate. Place the filter residue in an oven to dry.

[0039] By adding manganese carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate to Ni, Co, and Mn filter residue in a mass ratio of 1:0.5:0.3:0.5 and calcining at 500℃ for 2 h, oxides of Ni, Co, and Mn can be obtained, which can be used as precursors for regenerating new cathode materials. The resulting Li solution can be evaporated and crystallized to obtain LiOH powder.

[0040] Calculations show that the leaching rate of Li is 97.18%, while the leaching rates of Ni, Co, and Mn are all below 0.01% and can be ignored.

[0041] <Example 6> This embodiment provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, the specific process of which is as follows: Take 4g of waste ternary cathode powder and 100mL of deionized water and add them to a high-temperature and high-pressure reactor. Heat and stir for 480min at 170℃, 400rpm and 0.5Mpa to obtain a black leaching mixture. Filter the leaching mixture using a vacuum filter to obtain a light yellow leachate. Place the filter residue in an oven to dry.

[0042] By adding manganese carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate to Ni, Co, and Mn filter residue in a mass ratio of 1:0.5:0.3:0.5 and calcining at 500℃ for 2 h, oxides of Ni, Co, and Mn can be obtained, which can be used as precursors for regenerating new cathode materials. The resulting Li solution can be evaporated and crystallized to obtain LiOH powder.

[0043] Calculations show that the leaching rate of Li is 99.65%, while the leaching rates of Ni, Co, and Mn are all below 0.01% and can be ignored.

[0044] <Example 7> This embodiment provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, the specific process of which is as follows: Take 4g of waste ternary cathode powder and 100mL of deionized water and add them to a high-temperature and high-pressure reactor. Heat and stir for 360min at 190℃, 400rpm and 0.5Mpa to obtain a black leaching mixture. Filter the leaching mixture using a vacuum filter to obtain a light yellow leachate. Place the filter residue in an oven to dry.

[0045] By adding manganese carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate to Ni, Co, and Mn filter residue in a mass ratio of 1:0.5:0.3:0.5 and calcining at 500℃ for 2 h, oxides of Ni, Co, and Mn can be obtained, which can be used as precursors for regenerating new cathode materials. The resulting Li solution can be evaporated and crystallized to obtain LiOH powder.

[0046] Calculations show that the leaching rate of Li is 91.62%, while the leaching rates of Ni, Co, and Mn are all below 0.01% and can be ignored.

[0047] <Example 8> This embodiment provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, the specific process of which is as follows: Take 4g of waste ternary cathode powder and 100mL of deionized water and add them to a high-temperature and high-pressure reactor. Heat and stir for 360min at 230℃, 400rpm and 0.5Mpa to obtain a black leaching mixture. Filter the leaching mixture using a vacuum filter to obtain a light yellow leachate. Place the filter residue in an oven to dry.

[0048] By adding manganese carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate to Ni, Co, and Mn filter residue in a mass ratio of 1:0.5:0.3:0.5 and calcining at 500℃ for 2 h, oxides of Ni, Co, and Mn can be obtained, which can be used as precursors for regenerating new cathode materials. The resulting Li solution can be evaporated and crystallized to obtain LiOH powder.

[0049] Calculations show that the leaching rate of Li is 70.04%, while the leaching rates of Ni, Co, and Mn are all below 0.01% and can be ignored.

[0050] <Example 9> This embodiment provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, the specific process of which is as follows: Take 4g of waste ternary cathode powder and 100mL of deionized water and add them to a high-temperature and high-pressure reactor. Heat and stir for 360min at 250℃, 400rpm and 0.5Mpa to obtain a black leaching mixture. Filter the leaching mixture using a vacuum filter to obtain a light yellow leachate. Place the filter residue in an oven to dry.

[0051] By adding manganese carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate to Ni, Co, and Mn filter residue in a mass ratio of 1:0.5:0.3:0.5 and calcining at 500℃ for 2 h, oxides of Ni, Co, and Mn can be obtained, which can be used as precursors for regenerating new cathode materials. The resulting Li solution can be evaporated and crystallized to obtain LiOH powder.

[0052] Calculations show that the leaching rate of Li is 72.25%, while the leaching rates of Ni, Co, and Mn are all below 0.01% and can be ignored.

[0053] <Example 10> This embodiment provides a method for highly selectively leaching lithium metal from battery cathode powder using pure water, the specific process of which is as follows: Take 4g of waste ternary cathode powder and 100mL of deionized water and add them to a high-temperature and high-pressure reactor. Heat and stir for 360min at 150℃, 400rpm and 0.5Mpa to obtain a black leaching mixture. Filter the leaching mixture using a vacuum filter to obtain a light yellow leachate. Place the filter residue in an oven to dry.

[0054] By adding manganese carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate to Ni, Co, and Mn filter residue in a mass ratio of 1:0.5:0.3:0.5 and calcining at 500℃ for 2 h, oxides of Ni, Co, and Mn can be obtained, which can be used as precursors for regenerating new cathode materials. The resulting Li solution can be evaporated and crystallized to obtain LiOH powder.

[0055] Calculations show that the leaching rate of Li is 40.41%, while the leaching rates of Ni, Co, and Mn are all below 0.01% and can be ignored.

[0056] <Test Example 1> The concentrations of metal ions in the leachate obtained in step S2 of Examples 1-10, and the contents of Li, Ni, Co, and Mn in 5 mg of pre-prepared waste ternary cathode powder digested with 7 ml of concentrated nitric acid were measured using flame atomic absorption spectrometry. These measurements were then compared to calculate the leaching rate. The results are shown below. Figure 1-2 , Figure 1 , 2 The leaching efficiency of the cathode material under different leaching conditions is shown.

[0057] <Test Example 2> The original ternary cathode powder was analyzed using an X-ray diffractometer (RIGAKU D / Max−2550PC, Japan). The X-ray diffraction pattern of the original ternary cathode powder is shown below. Figure 3 As shown, from Figure 3 The peaks at 18.29°, 37.01°, 44.60°, 58.11°, 63.86°, and 66.07° represent NCM. 622 Crystalline peaks of ternary lithium batteries.

[0058] <Test Example 3> The black powder (black mixed extract) obtained after high-selective leaching with pure water was analyzed using an X-ray diffractometer (RIGAKU D / Max−2550PC, Japan). The X-ray diffraction pattern of the black powder obtained after high-selective leaching with pure water is shown below. Figure 4 As shown. Figure 4 In the image, the four lines from bottom to top represent: the original ternary cathode powder; the filter residue after leaching at 170℃, 400rpm, 0.5Mp, and 360min (Example 5); the filter residue after leaching at 190℃, 400rpm, 0.5Mp, and 360min (Example 7); the filter residue after leaching at 210℃, 400rpm, 0.5Mp, and 360min (Example 1); and the filter residue after leaching at 230℃, 400rpm, 0.5Mp, and 360min (Example 8).

[0059] from Figure 4 The data shows that 18.29 degrees, 37.01 degrees, 44.60 degrees, 58.11 degrees, and 63.86 degrees represent NCM. 622 The crystal peaks of the ternary battery indicate that the contents of Ni, Co and Mn in the leached sample remain basically unchanged and the structure is preserved.

[0060] <Test Example 4> The precursor of the regenerated cathode material from Example 1 was further characterized using an X-ray diffractometer (RIGAKU D / Max-2550PC, Japan). Figure 5 As shown, it was found that Ni 0.5 Co 0.2 Mn 0.3 The standard cards for (OH)2 are consistent, confirming that the precipitate is Ni, a precursor of Ni, Co, and Mn. 0.5 Co 0.2 Mn 0.3 (OH)2, i.e., NCM 523 Precursor.

[0061] Depend on Figure 4 and Figure 5 It can be seen that the filter residue after filtration in step S2 is NCM in which Li has been leached but its structure has been preserved. 622 However, it is not pure, containing certain organic impurities and byproducts of structural collapse. After calcination, it forms NCM. 523 The precursor is relatively pure.

[0062] The above are merely examples of embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for selectively leaching lithium from waste lithium battery cathode powder using pure water, characterized in that, Includes the following steps: Step S1: Put the waste ternary battery positive electrode powder and pure water into a sealed container, introduce oxygen at a certain pressure, and heat for a predetermined time at a temperature of 190℃~210℃ with stirring to obtain a leaching mixture. Step S2: Filter the leaching mixture to obtain a leaching solution containing Li; Step S3: Evaporate the leachate to crystallize it, and react for a predetermined time to obtain lithium hydroxide powder.

2. The method for selectively leaching lithium from waste lithium battery cathode powder using pure water according to claim 1, characterized in that: in, In step S1, the solid-liquid ratio of the pure water to the waste ternary battery cathode powder is 30g / L~35g / L.

3. The method for selectively leaching lithium from waste lithium battery cathode powder using pure water according to claim 1, characterized in that: in, In step S1, waste ternary battery positive electrode powder and pure water are placed into a sealed container and heated for 120 min to 360 min under stirring conditions of 210℃, oxygen pressure of 0.2MPa~0.5MPa, and rotation speed of 300r / min~400r / min to obtain a leaching mixture.

4. The method for selectively leaching lithium from waste lithium battery cathode powder using pure water according to claim 1, characterized in that, Also includes: Step S4: Add a certain amount of nickel carbonate, cobalt carbonate, and manganese carbonate to the dried filter residue obtained in step S2 and calcine them together to produce NCM. 523 Ternary precursors.

5. The method for selectively leaching lithium from waste lithium battery cathode powder using pure water according to claim 4, characterized in that: in, The mass ratio of the dried filter residue, nickel carbonate, cobalt carbonate, and manganese carbonate is 1:0.5:0.3:0.5.

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