A method for preparing a sodium-ion battery cathode material by using a retired lithium-ion battery

Abstract

The application provides a method for preparing a sodium-ion battery positive electrode material from a retired lithium-ion battery, which comprises the following steps: (1) charging the retired lithium-ion battery and then disassembling the battery to obtain a first delithiated positive electrode sheet; (2) sequentially performing coarse crushing and heat treatment on the first delithiated positive electrode sheet to obtain a second delithiated positive electrode sheet; (3) performing hydraulic impact crushing on the second delithiated positive electrode sheet to obtain a solid-liquid mixture containing a delithiated positive electrode material and a current collector; (4) performing screening on the solid-liquid mixture, and drying undersize materials to obtain the delithiated positive electrode material; and (5) mixing a sodium salt with the delithiated positive electrode material, sintering and crushing to obtain the sodium-ion battery positive electrode material. The method provided by the application improves the electrochemical cycle performance of the sodium-ion battery positive electrode material, realizes recycling of waste batteries, and saves preparation cost.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a method for recycling and reusing batteries, and more particularly to a method for preparing sodium-ion battery cathode materials using retired lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries originated in the 1980s. Due to their performance and technological advantages, lithium battery technology has matured over the decades and has now been successfully commercialized on a large scale, applied in all aspects of daily life. Based on usage scenarios and energy levels, lithium-ion batteries can be specifically divided into lithium-ion power batteries, lithium-ion consumer batteries, and lithium-ion energy storage batteries.

[0003] In recent years, the global new energy industry has achieved rapid development, with the installed capacity of power batteries exceeding 250 GWh. As the main application of lithium batteries, lithium-ion power batteries, due to the need for longer driving range, have begun to widely use ternary materials, which have high energy density but slightly lower cycle and safety performance, yet offer a balanced overall performance. Industry regulations stipulate that power batteries must be retired when their cycle life falls below 80% of their initial capacity. Therefore, how to achieve the rational recycling and reuse of retired power lithium-ion batteries is a problem that the retired lithium battery industry is currently striving to solve.

[0004] Currently, China's production and sales of new energy vehicles continue to grow, ranking first in the world. However, traditional lead-acid and nickel-cadmium batteries have low energy efficiency and cause serious pollution, while lithium-ion batteries are expensive and their safety needs improvement. With the surge in demand for new energy vehicles, coupled with the limitations of lithium metal mining, the global supply of lithium metal is insufficient to meet market demand. Under these circumstances, sodium-ion batteries, with their advantages of high safety, low cost, and environmental friendliness, have become increasingly popular among researchers.

[0005] Layered transition metal oxides (LMOs) are representative cathode materials for sodium-ion batteries. These LMOs possess reversible ion insertion / extraction capabilities and a stable layered structure, facilitating the insertion of other ions or molecules between layers, making them a current research hotspot for sodium-ion battery cathode materials. Although layered oxide cathode materials have high theoretical specific capacity and Na... + Two-dimensional diffusion within the layers is relatively fast, but the material exhibits poor electrochemical cycling performance. Therefore, finding a sodium-ion battery cathode material with better cycling performance is of great significance in this field.

[0006] Therefore, how to provide a method for preparing sodium-ion battery cathode materials using retired lithium-ion batteries, improve the electrochemical cycle performance of the materials as much as possible, realize the recycling and reuse of waste batteries, and save preparation costs has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing sodium-ion battery cathode materials using retired lithium-ion batteries. This method improves the electrochemical cycle performance of sodium-ion battery cathode materials, enables the recycling and reuse of waste batteries, and saves preparation costs.

[0008] To achieve this objective, the present invention employs the following technical solution:

[0009] This invention provides a method for preparing sodium-ion battery cathode materials using retired lithium-ion batteries, the method comprising the following steps:

[0010] (1) The retired lithium-ion battery was charged and then disassembled to obtain the first delithiated positive electrode sheet;

[0011] (2) The first delithiated positive electrode sheet is subjected to coarse crushing and heat treatment in sequence to obtain the second delithiated positive electrode sheet;

[0012] (3) The second delithiated cathode sheet is subjected to hydraulic impact crushing to obtain a solid-liquid mixture containing delithiated cathode material and current collector;

[0013] (4) The solid-liquid mixture is sieved and the sieved material is dried to obtain a lithium-free cathode material;

[0014] (5) Mix the sodium salt and the delithiated cathode material, sinter and pulverize to obtain sodium-ion battery cathode material.

[0015] The method provided by this invention first charges a retired lithium-ion battery, causing the positive electrode material in the battery to be delithiated and form a delithiated layered structure. Then, after a series of subsequent processing, sodium ions can be embedded in the layered structure under low temperature conditions, thereby producing a sodium-ion battery positive electrode material with high crystallinity. The cycle performance and capacity are significantly higher than those of sodium battery materials produced by conventional methods.

[0016] Furthermore, the method provided by this invention does not require acid leaching to obtain ionic nickel, cobalt, and manganese elements, nor does it require extracting agents to extract metal elements. Instead, it directly uses delithiated cathode materials from retired lithium-ion batteries as precursors for sodium-ion battery materials, saving production costs and meeting green and environmentally friendly production requirements.

[0017] Preferably, the cathode material of the retired lithium-ion battery in step (1) includes lithium nickel cobalt manganese oxide.

[0018] Preferably, the chemical composition of the lithium nickel cobalt manganese oxide is: LiNi x Co y Mn 1-x-y O2, and 0.6≤x≤0.8, 0.1≤y≤0.2.

[0019] In this invention, 0.6≤x≤0.8, for example, x can be 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78 or 0.8, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] In this invention, 0.1≤y≤0.2, for example, y can be 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28 or 0.3, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the charging rate of the retired lithium-ion battery in step (1) is 0.08-0.12C, for example, it can be 0.08C, 0.09C, 0.10C, 0.11C or 0.12C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, the retired lithium-ion battery in step (1) is charged to a state of charge (SOC) of 90-100%, for example, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] This invention charges retired lithium-ion batteries to a state of charge (SOC) of 90-100% at a charging rate of 0.08-0.12C. That is, it uses a low current to charge retired lithium-ion batteries to a near-fully charged state, so that the positive electrode material can be fully delithiated to form a delithiated layered structure, which facilitates the subsequent full insertion of sodium ions.

[0024] Preferably, the disassembly in step (1) is carried out in a glove box filled with argon gas.

[0025] Preferably, the coarse crushing in step (2) is carried out in a shear crusher.

[0026] Preferably, the average equivalent diameter of the positive electrode sheet obtained by coarse crushing in step (2) is 0.2-0.8 cm, for example, it can be 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7 cm or 0.8 cm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, the heat treatment in step (2) includes a low-temperature heat treatment and a high-temperature heat treatment performed sequentially in an oxygen atmosphere.

[0028] Preferably, the temperature of the low-temperature heat treatment is 70-90℃, for example, it can be 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃ or 90℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] Preferably, the low-temperature heat treatment time is 50-70 min, for example, it can be 50 min, 52 min, 54 min, 56 min, 58 min, 60 min, 62 min, 64 min, 66 min, 68 min or 70 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] Preferably, the temperature of the high-temperature heat treatment is 140-160℃, for example, it can be 140℃, 142℃, 144℃, 146℃, 148℃, 150℃, 152℃, 154℃, 156℃, 158℃ or 160℃, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0031] Preferably, the high-temperature heat treatment time is 3-5 hours, for example, it can be 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours or 5 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] In this invention, the low-temperature heat treatment enables the electrolyte on the surface of the positive electrode to be fully volatilized and removed, and the high-temperature heat treatment enables the conductive carbon and organic matter such as binder (PVDF) in the positive electrode material to be fully burned and carbonized, thereby obtaining a relatively pure lithium-free positive electrode material.

[0033] Preferably, the rotation speed of the hydraulic impact crusher in step (3) is 800-1200 rpm, for example, it can be 800 rpm, 850 rpm, 900 rpm, 950 rpm, 1000 rpm, 1050 rpm, 1100 rpm, 1150 rpm or 1200 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] Preferably, in step (3), the hydraulic impact crushing is performed until the delithiated cathode material and the current collector are completely separated, and the soft agglomerated delithiated cathode material particles are completely dissociated.

[0035] Preferably, the mesh size of the sieve used in step (4) is 80-120 mesh, for example, it can be 80 mesh, 90 mesh, 100 mesh, 110 mesh or 120 mesh, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, the drying in step (4) includes drying, and the drying temperature is 80-120°C, for example, it can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the sodium salt in step (5) includes Na2CO3 and / or NaHCO3, and more preferably Na2CO3.

[0038] Preferably, the molar ratio of the sodium salt to the delithiated cathode material in step (5) is (0.4-0.5):1, for example, it can be 0.4:1, 0.42:1, 0.44:1, 0.46:1, 0.48:1 or 0.5:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] In this invention, the effective component of the delithiation cathode material, nickel cobalt manganese oxide, is used as the molar measurement standard.

[0040] Preferably, the mixing process in step (5) is also accompanied by ball milling.

[0041] Preferably, the sintering in step (5) is carried out in an oxygen atmosphere.

[0042] Preferably, the sintering temperature in step (5) is 800-1000℃, for example, it can be 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃ or 1000℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Preferably, the sintering time in step (5) is 8-12h, for example, it can be 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h or 12h, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, after pulverization in step (5), the material is further sieved, and the mesh size of the sieve used for sieving is 200-400 mesh, for example, it can be 200 mesh, 220 mesh, 240 mesh, 260 mesh, 280 mesh, 300 mesh, 320 mesh, 340 mesh, 360 mesh, 380 mesh or 400 mesh, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] As a preferred technical solution of the present invention, the method includes the following steps:

[0046] (1) The retired lithium-ion battery is charged to a state of charge (SOC) of 90-100% at a charging rate of 0.08-0.12C, and then disassembled in an argon-filled glove box to obtain the first delithiated positive electrode sheet; the positive electrode material of the retired lithium-ion battery includes lithium nickel cobalt manganese oxide (LiNi). x Co y Mn 1-x-y O2, and 0.6≤x≤0.8, 0.1≤y≤0.2;

[0047] (2) The first delithiated positive electrode sheet is coarsely crushed in a shear crusher until the average equivalent diameter of the positive electrode sheet is 0.2-0.8 cm. The obtained positive electrode sheet is then subjected to low temperature heat treatment at 70-90℃ for 50-70 min and high temperature heat treatment at 140-160℃ for 3-5 h in an oxygen atmosphere to obtain the second delithiated positive electrode sheet.

[0048] (3) The second delithiated cathode sheet is subjected to hydraulic impact crushing at a speed of 800-1200 rpm until the delithiated cathode material and current collector are completely separated, and the soft agglomerated delithiated cathode material particles are completely dissociated to obtain a solid-liquid mixture containing delithiated cathode material and current collector.

[0049] (4) The solid-liquid mixture is sieved using an 80-120 mesh sieve, and the sieved material is dried at 80-120°C to obtain a lithium-free cathode material;

[0050] (5) Na2CO3 and the delithiation cathode material are ball-milled at a molar ratio of (0.4-0.5):1, sintered in an oxygen atmosphere at 800-1000℃ for 8-12 hours, and then pulverized and passed through a 200-400 mesh sieve to obtain sodium-ion battery cathode material.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) The method provided by the present invention first charges the retired lithium-ion battery so that the positive electrode material in the battery is delithiated to form a delithiated layered structure. Then, after a series of subsequent processing, sodium ions can be embedded in the layered structure under low temperature conditions, thereby obtaining a sodium-ion battery positive electrode material with high crystallinity. The cycle performance and capacity are significantly higher than those of sodium battery materials obtained by conventional methods.

[0053] (2) The method provided by the present invention does not require the use of acid leaching to obtain ionic nickel, cobalt and manganese elements, nor does it require the use of extractants to extract metal elements. Instead, it directly uses the delithiation cathode material in retired lithium-ion batteries as the precursor of sodium-ion battery materials, which saves production costs and meets the requirements of green and environmentally friendly production. Attached Figure Description

[0054] Figure 1 These are transmission electron micrographs of the sodium-ion battery cathode material obtained by the method provided in Example 1;

[0055] Figure 2 The XRD diffraction pattern of the sodium-ion battery cathode material obtained by the method provided in Example 1 is shown. Detailed Implementation

[0056] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0057] Example 1

[0058] This embodiment provides a method for preparing sodium-ion battery cathode materials using retired lithium-ion batteries, the method comprising the following steps:

[0059] (1) Retired lithium-ion batteries (with positive electrode composition LiNi) are charged at a rate of 0.1C. 0.6 Co 0.2 Mn 0.2 The specific capacity at 0.1C is 220mAh / g (the theoretical specific capacity of the material is 270mAh / g). The material is charged to 100% SOC and then disassembled in an argon-filled glove box to obtain the first delithiated cathode sheet.

[0060] (2) The first delithiated positive electrode sheet is coarsely crushed in a shear crusher until the average equivalent diameter of the positive electrode sheet is 0.6 cm. The obtained positive electrode sheet is then subjected to low temperature heat treatment at 80°C for 60 min and high temperature heat treatment at 150°C for 4 h in an oxygen atmosphere to obtain the second delithiated positive electrode sheet.

[0061] (3) The second delithiated cathode sheet is subjected to hydraulic impact crushing at a speed of 1000 rpm until the delithiated cathode material and current collector are completely separated, and the soft agglomerated delithiated cathode material particles are completely dissociated to obtain a solid-liquid mixture containing delithiated cathode material and current collector.

[0062] (4) The solid-liquid mixture is sieved using a 100-mesh sieve, and the undersize material is dried at 100°C to obtain the lithium-free cathode material Li. 0.2 Ni 0.6 Co 0.2 Mn 0.2 O2;

[0063] (5) Na₂CO₃ and the delithiated cathode material were ball-milled at a molar ratio of 0.4:1, sintered in an oxygen atmosphere at 900°C for 10 h, and then pulverized and passed through a 300-mesh sieve to obtain sodium-ion battery cathode material Na. 0.8 Li0.2 Ni 0.6 Co 0.2 Mn 0.2 O2.

[0064] Figure 1 This is a transmission electron micrograph of the sodium-ion battery cathode material obtained in this embodiment, and it is produced by... Figure 1 It can be seen that the sodium-ion battery cathode material obtained in this embodiment exhibits a highly crystalline layered structure.

[0065] Figure 2 This is the XRD diffraction pattern of the sodium-ion battery cathode material obtained in this embodiment, and it is derived from... Figure 2 It can be seen that the sodium-ion battery cathode material obtained in this embodiment exhibits a sharp characteristic diffraction peak around 15°.

[0066] Example 2

[0067] This embodiment provides a method for preparing sodium-ion battery cathode materials using retired lithium-ion batteries, the method comprising the following steps:

[0068] (1) Retired lithium-ion batteries (with positive electrode composition LiNi) are charged at a rate of 0.1C. 0.8 Co 0.1 Mn 0.1 The specific capacity at 0.1C is 238mAh / g (the theoretical specific capacity of the material is 270mAh / g). The material is charged to 100% SOC and then disassembled in an argon-filled glove box to obtain the first lithium-free cathode sheet.

[0069] (2) The first delithiated positive electrode sheet is coarsely crushed in a shear crusher until the average equivalent diameter of the positive electrode sheet is 0.2 cm. The obtained positive electrode sheet is then subjected to low temperature heat treatment at 70°C for 70 min and high temperature heat treatment at 140°C for 5 h in an oxygen atmosphere to obtain the second delithiated positive electrode sheet.

[0070] (3) The second delithiated cathode sheet is subjected to hydraulic impact crushing at a speed of 800 rpm until the delithiated cathode material and current collector are completely separated, and the soft agglomerated delithiated cathode material particles are completely dissociated to obtain a solid-liquid mixture containing delithiated cathode material and current collector.

[0071] (4) The solid-liquid mixture is sieved using a 120-mesh sieve, and the undersize material is dried at 80°C to obtain the lithium-free cathode material Li. 0.12 Ni 0.8 Co 0.1 Mn 0.1 O2;

[0072] (5) Na₂CO₃ and the delithiated cathode material were ball-milled at a molar ratio of 0.44:1, sintered in an oxygen atmosphere at 800°C for 12 hours, and then pulverized and passed through a 400-mesh sieve to obtain sodium-ion battery cathode material Na. 0.88 Li 0.12 Ni 0.8 Co 0.1 Mn 0.1 O2.

[0073] The microstructure and XRD characteristic diffraction peaks of the sodium-ion battery cathode material obtained in this embodiment are similar to those in Example 1, so they will not be described again here.

[0074] Example 3

[0075] This embodiment provides a method for preparing sodium-ion battery cathode materials using retired lithium-ion batteries, the method comprising the following steps:

[0076] (1) Retired lithium-ion batteries (with positive electrode composition LiNi) are charged at a rate of 0.1C. 0.8 Co 0.1 Mn 0.1 The specific capacity at 0.1C is 238mAh / g (the theoretical specific capacity of the material is 270mAh / g). The material is charged to a state of charge (SOC) of 90% and then disassembled in an argon-filled glove box to obtain the first lithium-free cathode sheet.

[0077] (2) The first delithiated positive electrode sheet is coarsely crushed in a shear crusher until the average equivalent diameter of the positive electrode sheet is 0.8 cm. The obtained positive electrode sheet is then subjected to low temperature heat treatment at 90°C for 50 min and high temperature heat treatment at 160°C for 3 h in an oxygen atmosphere to obtain the second delithiated positive electrode sheet.

[0078] (3) The second delithiated positive electrode sheet is subjected to hydraulic impact crushing at a speed of 1200 rpm until the delithiated positive electrode material and the current collector are completely separated, and the soft agglomerated delithiated positive electrode material particles are completely dissociated to obtain a solid-liquid mixture containing delithiated positive electrode material and current collector.

[0079] (4) The solid-liquid mixture is sieved using an 80-mesh sieve, and the undersize material is dried at 120°C to obtain the lithium-free cathode material Li. 0.2 Ni 0.8 Co 0.1 Mn 0.1 O2;

[0080] (5) Na₂CO₃ and the delithiated cathode material were ball-milled at a molar ratio of 0.4:1, sintered in an oxygen atmosphere at 1000°C for 8 hours, and then pulverized and passed through a 200-mesh sieve to obtain sodium-ion battery cathode material Na. 0.8 Li0.2 Ni 0.8 Co 0.1 Mn 0.1 O2.

[0081] The microstructure and XRD characteristic diffraction peaks of the sodium-ion battery cathode material obtained in this embodiment are similar to those in Example 1, so they will not be described again here.

[0082] Example 4

[0083] This embodiment provides a method for preparing sodium-ion battery cathode material using retired lithium-ion batteries. Except for increasing the charging rate in step (1) to 0.2C, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0084] Compared to Example 1, this example slightly increases the charging rate, resulting in a slight decrease in the sufficiency of lithium ion removal from the cathode material, thus yielding a lithium-depleted cathode material Li. 0.22 Ni 0.6 Co 0.2 Mn 0.2 O2, and finally obtained Na, the positive electrode material for sodium-ion batteries. 0.78 Li 0.22 Ni 0.6 Co 0.2 Mn 0.2 O2.

[0085] Example 5

[0086] This embodiment provides a method for preparing sodium-ion battery cathode material using retired lithium-ion batteries. The method is the same as in Example 1 except that the heat treatment in step (2) is changed to a high-temperature heat treatment at 150°C for 5 hours in an oxygen atmosphere. Therefore, it will not be described in detail here.

[0087] Compared to Example 1, this example does not perform low-temperature heat treatment, but directly performs high-temperature heat treatment. Although it can also fully remove the electrolyte from the surface of the positive electrode, the energy consumption and processing cost are slightly increased.

[0088] Comparative Example 1

[0089] This comparative example provides a method for recycling retired lithium-ion batteries, the method comprising the following steps:

[0090] (1) Discharge at a rate of 0.1C to decommission a lithium-ion battery (positive electrode composition is LiNi). 0.6 Co 0.2 Mn 0.2The specific capacity at 0.1C is 220mAh / g (the theoretical specific capacity of the material is 270mAh / g). The material is discharged to a state of charge (SOC) of 0% and then disassembled in an argon-filled glove box to obtain the first lithium-intercalated cathode sheet.

[0091] (2) The first lithium-intercalated positive electrode sheet is coarsely crushed in a shear crusher until the average equivalent diameter of the positive electrode sheet is 0.6 cm. The obtained positive electrode sheet is then subjected to low temperature heat treatment at 80°C for 60 min and high temperature heat treatment at 150°C for 4 h in an oxygen atmosphere to obtain the second lithium-intercalated positive electrode sheet.

[0092] (3) The second lithium-intercalated cathode sheet is subjected to hydraulic impact crushing at a speed of 1000 rpm until the lithium-intercalated cathode material and current collector are completely separated, and the soft agglomerated lithium-intercalated cathode material particles are completely disintegrated to obtain a solid-liquid mixture containing lithium-intercalated cathode material and current collector.

[0093] (4) The solid-liquid mixture is sieved using a 100-mesh sieve, and the sieved material is dried at 100°C to obtain the lithium-intercalated cathode material LiNi. 0.6 Co 0.2 Mn 0.2 O2;

[0094] (5) The obtained lithium-intercalated cathode material was ball-milled and sintered in an oxygen atmosphere at 900°C for 10 h. After pulverization, it was passed through a 300-mesh sieve to obtain the lithium-ion battery cathode material LiNi. 0.6 Co 0.2 Mn 0.2 O2.

[0095] Compared to Example 1, this comparative example only serves to recycle cathode materials from retired lithium-ion batteries and cannot be used to prepare highly crystalline sodium-ion battery cathode materials.

[0096] Therefore, the method provided by the present invention first charges the retired lithium-ion battery, causing the positive electrode material in the battery to be delithiated and form a delithiated layered structure. Then, after a series of subsequent processing, sodium ions can be embedded in the layered structure under low temperature conditions, thereby producing a sodium-ion battery positive electrode material with high crystallinity. The cycle performance and capacity are significantly higher than those of sodium battery materials produced by conventional methods.

[0097] Furthermore, the method provided by this invention does not require acid leaching to obtain ionic nickel, cobalt, and manganese elements, nor does it require extracting agents to extract metal elements. Instead, it directly uses delithiated cathode materials from retired lithium-ion batteries as precursors for sodium-ion battery materials, saving production costs and meeting green and environmentally friendly production requirements.

[0098] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing sodium-ion battery cathode materials using retired lithium-ion batteries, characterized in that, The method includes the following steps: (1) Charge the retired lithium-ion battery to a state of charge (SOC) of 90-100% at a charging rate of 0.08-0.12C, and then disassemble it to obtain the first delithiated positive electrode sheet; the positive electrode material of the retired lithium-ion battery includes lithium nickel cobalt manganese oxide. (2) The first delithiated positive electrode sheet is coarsely crushed in sequence, and then subjected to low temperature heat treatment of 70-90℃ and high temperature heat treatment of 140-160℃ in sequence to obtain the second delithiated positive electrode sheet. (3) The second delithiated cathode sheet is subjected to hydraulic impact crushing to obtain a solid-liquid mixture containing delithiated cathode material and current collector; (4) The solid-liquid mixture is sieved and the sieved material is dried to obtain the delithiated cathode material; (5) Mix the sodium salt and the delithiated cathode material, sinter and pulverize to obtain sodium-ion battery cathode material.

2. The method according to claim 1, characterized in that, The chemical composition of the lithium nickel cobalt manganese oxide mentioned in step (1) is: LiNi x Co y Mn 1-x-y O2, and 0.6≤x≤0.8, 0.1≤y≤0.

2.

3. The method according to claim 1, characterized in that, The disassembly described in step (1) is carried out in a glove box filled with argon gas.

4. The method according to claim 1, characterized in that, The coarse crushing in step (2) is carried out in a shear crusher.

5. The method according to claim 1, characterized in that, The average equivalent diameter of the positive electrode sheet obtained by coarse crushing in step (2) is 0.2-0.8 cm.

6. The method according to claim 1, characterized in that, The low-temperature heat treatment in step (2) takes 50-70 minutes.

7. The method according to claim 1, characterized in that, The high-temperature heat treatment in step (2) takes 3-5 hours.

8. The method according to claim 1, characterized in that, The rotational speed of the hydraulic impact crusher in step (3) is 800-1200 rpm.

9. The method according to claim 1, characterized in that, Step (3) involves hydraulic impact crushing until the delithiated cathode material and current collector are completely separated, and the soft agglomerated delithiated cathode material particles are completely disintegrated.

10. The method according to claim 1, characterized in that, The sieve used for sieving in step (4) has a mesh size of 80-120.

11. The method according to claim 1, characterized in that, The drying in step (4) includes baking, and the baking temperature is 80-120°C.

12. The method according to claim 1, characterized in that, The sodium salt in step (5) includes Na2CO3 and / or NaHCO3.

13. The method according to claim 12, characterized in that, The sodium salt mentioned in step (5) is Na2CO3.

14. The method according to claim 1, characterized in that, The mixing molar ratio of sodium salt and delithiated cathode material in step (5) is (0.4-0.5):

1.

15. The method according to claim 1, characterized in that, The mixing process described in step (5) is also accompanied by ball milling.

16. The method according to claim 1, characterized in that, The sintering in step (5) is carried out in an oxygen atmosphere.

17. The method according to claim 1, characterized in that, The sintering temperature in step (5) is 800-1000℃.

18. The method according to claim 1, characterized in that, The sintering time in step (5) is 8-12 hours.

19. The method according to claim 1, characterized in that, After crushing in step (5), the material is sieved, and the mesh size of the sieve used for sieving is 200-400 mesh.

20. The method according to any one of claims 1-19, characterized in that, The method includes the following steps: (1) The retired lithium-ion battery is charged to a state of charge (SOC) of 90-100% at a charging rate of 0.08-0.12C, and then disassembled in an argon-filled glove box to obtain the first delithiated positive electrode sheet; the positive electrode material of the retired lithium-ion battery includes lithium nickel cobalt manganese oxide (LiNi). x Co y Mn 1-x-y O2, and 0.6≤x≤0.8, 0.1≤y≤0.2; (2) The first delithiated positive electrode sheet is coarsely crushed in a shear crusher until the average equivalent diameter of the positive electrode sheet is 0.2-0.8 cm. The obtained positive electrode sheet is then subjected to low temperature heat treatment at 70-90℃ for 50-70 min and high temperature heat treatment at 140-160℃ for 3-5 h in an oxygen atmosphere to obtain the second delithiated positive electrode sheet. (3) The second delithiated cathode sheet is subjected to hydraulic impact crushing at a speed of 800-1200 rpm until the delithiated cathode material and current collector are completely separated, and the soft agglomerated delithiated cathode material particles are completely dissociated to obtain a solid-liquid mixture containing delithiated cathode material and current collector. (4) The solid-liquid mixture is sieved using an 80-120 mesh sieve, and the sieved material is dried at 80-120°C to obtain the delithiated cathode material; (5) Mix Na2CO3 and the delithiated cathode material by ball milling at a molar ratio of (0.4-0.5):1, sinter in an oxygen atmosphere at 800-1000℃ for 8-12 hours, and then pulverize and pass through a 200-400 mesh sieve to obtain sodium-ion battery cathode material.

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