Method for re-synthesizing ternary lithium battery positive electrode material from retired ternary battery

Abstract

The invention discloses a method for re-synthesizing a ternary lithium battery positive electrode material from a decommissioned ternary battery, which comprises the following steps: (1) discharging, roasting, disassembling and grinding the decommissioned ternary battery to obtain the required positive electrode material; (2) mixing the positive electrode material with ammonium bisulfate, grinding, calcining at high temperature, leaching with pure water to obtain a material, and heating the material in a water bath; (3) carrying out suction filtration on the material heated in the water bath to obtain a stock solution, adding an oxalic acid solution into the stock solution, mixing and stirring, adding ammonia water, regulating the pH value, preserving heat, standing, and carrying out suction filtration on the solution to obtain an oxalate precipitate; and (4) drying the oxalate precipitate, performing high-temperature calcination to obtain a (Ni0. 5Co0. 2Mn0. 3) 3O4 precursor, and adding lithium carbonate into the obtained precursor to supplement lithium to obtain the ternary lithium battery positive electrode material. According to the preparation method of the positive electrode material, metal elements can be uniformly mixed on the atomic level, and the ternary positive electrode material with excellent performance is synthesized.

Description

Technical Field

[0001] The present invention relates to the technical field of battery recycling and reuse, and in particular to a method for re-synthesizing ternary lithium battery positive electrode materials from retired ternary batteries. Background Art

[0002] The recycling and reuse of retired ternary lithium battery cathode materials is an important direction in the current new energy industry. With the rapid development of new energy vehicles and portable electronic devices, ternary lithium batteries have been widely used due to their high energy density and long cycle life. However, their large-scale use has also brought about the problem of waste battery disposal. Retired ternary lithium batteries are rich in valuable metals such as lithium (Li), nickel (Ni), cobalt (Co), and manganese (Mn). The recycling and reuse of these metal resources can not only reduce environmental pollution, but also alleviate the pressure of scarce rare metal resources, and has significant economic, environmental, and social value.

[0003] In the existing technology, traditional solid-phase synthesis technology is mostly used to recycle and reuse retired ternary lithium battery positive electrode materials. The calcination temperature of the solid-phase synthesis method is generally 700℃-1000℃. The electrochemical performance of the ternary positive electrode material is affected by the uniformity of metal ion distribution. The metal distribution uniformity in the positive electrode material obtained by traditional solid-phase sintering is poor. Therefore, a positive electrode material preparation method is needed that can evenly mix metal elements at the atomic level to synthesize a ternary positive electrode material with excellent performance. Summary of the Invention

[0004] The main purpose of the present invention is to provide a method for re-synthesizing ternary lithium battery positive electrode materials from retired ternary batteries, which at least solves the problem of poor metal uniformity in the positive electrode materials obtained by traditional solid-phase sintering in the prior art.

[0005] According to one aspect of the present invention, a method for re-synthesizing a ternary lithium battery positive electrode material from a retired ternary battery is provided, comprising:

[0006] Step 1, (Ni 0.5 Co 0.2 Mn 0.3 ) Leaching of 3O4 precursor: After discharging, roasting, disassembling and grinding retired ternary batteries, the required positive electrode material raw material is obtained, and the raw material is mixed with ammonium bisulfate to obtain a mixture. After grinding, high-temperature roasting and pure water leaching, the obtained material is heated and stirred in a water bath, and filtered to obtain a leachate;

[0007] Step 2, adjustment and precipitation of the leachate: add oxalic acid solution to the leachate obtained in step 1, mix and stir, add ammonia water, adjust the pH value, keep warm and let it stand, filter the solution to obtain oxalate precipitate; Step 3, calcination of the precipitate and lithium supplementation regeneration: dry the oxalate precipitate and then calcine it at high temperature to obtain (Ni0.5 Co 0.2 Mn 0.3 )3O4 precursor, the obtained (Ni 0.5 Co 0.2 Mn 0.3 )3O4 precursor is added with lithium carbonate and then regenerated by lithium supplementation to obtain regenerated Li(Ni 0.5 Co 0.2 Mn 0.3 )O2 ternary positive electrode material.

[0008] In a possible design, in step 1, the mixing ratio of ammonium bisulfate and the positive electrode material is 3-5:1 by mass.

[0009] In a possible design, in step 1, the ratio of pure water to ammonium bisulfate added is 100:3 by mass fraction, the water bath heating temperature after pure water leaching is 80° C., and the water bath time is 1 h.

[0010] In a possible design, in step 2, when preparing the oxalate precipitate, aqueous ammonia is added to the filtrate to adjust the pH value to 1.5-2.5.

[0011] In a possible design, in step 3, the calcination temperature of the oxalate sediment is 500° C. and the calcination time is 5 h.

[0012] In a possible design, in step 1, the mixture is calcined at a temperature of 400° C. and for a time of 2 h.

[0013] In a possible design, the molar amount of oxalic acid solution added in step 2 is (Ni 0.5 Co 0.2 Mn 0.3 )1-1.2 times of 3O4.

[0014] In a possible design, in step 3, when lithium is replenished and regenerated, the (

[0015] Ni 0.5 Co 0.2 Mn 0.3 The )3O4 precursor is placed in a calcination device and the temperature is set to rise by 5°C per minute to 800-900°C and kept at this temperature for 12 hours.

[0016] In a possible design, the addition of lithium carbonate (Ni 0.5 Co 0.2 Mn 0.3 The )3O4 precursor was placed in a calcination device and the temperature was raised to 850°C at 5°C per minute and kept at this temperature for 12 hours.

[0017] In one possible design, in step 3, (Ni 0.5 Co 0.2 Mn 0.3 )The ratio of 3O4 precursor to lithium carbonate is 1:1 or 1:1.05 or 1:1.1 or 1:1.15.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] Compared with traditional solid-phase synthesis technology, the co-precipitation method of the present invention has a lower calcination temperature. The lower calcination temperature can reduce energy consumption and production costs, and also help reduce structural changes and impurity generation of materials at high temperatures. The electrochemical performance of ternary positive electrode materials is affected by the uniformity of metal ion distribution, and the metal distribution uniformity in the positive electrode materials obtained by traditional solid-phase sintering is poor. The present invention provides a method for preparing positive electrode materials that can evenly mix metal elements at the atomic level. By treating the metal-rich solution or leachate, the metal elements are evenly precipitated to obtain a positive electrode material precursor. By heat treating the obtained precursor, the positive electrode material can be obtained. The co-precipitation method of the present invention, which is mainly based on solution reaction, can achieve atomic-scale mixing of metal ions and synthesize a ternary positive electrode material with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 A process flow chart of a method for resynthesizing a ternary lithium battery positive electrode material from retired ternary batteries disclosed in an embodiment of the present invention;

[0022] Figure 2 Li(Ni prepared at different calcination temperatures 0.5 Co 0.2 Mn 0.3 ) O2 rate performance curve;

[0023] Figure 3 Li(Ni 0.5 Co 0.2 Mn 0.3 ) O2 first charge and discharge curve;

[0024] Figure 4 Li(Ni prepared at different calcination temperatures 0.5 Co 0.2 Mn 0.3 ) O2 cycle performance curve;

[0025] Figure 5 The overall morphological characteristics of the two materials under SEM scanning mirror images, where (a) is retired battery powder and (b) is recycled synthetic ternary lithium battery;

[0026] Figure 6 These are SEM characterization images of regenerated ternary lithium battery powder at different calcination temperatures under the condition of a lithium ratio of 1:1.05, where (a) is 800℃, (b) is 900℃, and (c) is 850℃.

[0027] Figure 7 The regenerated Li(Ni) with different lithium ratios from Example 1 to Example 4 0.5 Co 0.2 Mn 0.3 )O2XRD pattern.

[0028] Figure 8 Li(Ni 0.5 Co 0.2 Mn 0.3 ) SEM morphology of cathode material;

[0029] Figure 9 Li(Ni 0.5 Co 0.2 Mn 0.3 ) SEM morphology of cathode material;

[0030] Figure 10 Li(Ni 0.5 Co 0.2 Mn 0.3 ) SEM morphology of cathode material;

[0031] Figure 11 Li(Ni 0.5 Co 0.2 Mn 0.3 ) SEM morphology of cathode material;

[0032] Figure 12 Regenerated Li(Ni 0.5 Co 0.2 Mn 0.3 ) The first charge and discharge curve of O2 cathode material;

[0033] Figure 13 LiNi prepared under different lithium ratios 0.5 Co 0.2 Mn 0.3 O2 cycle performance curve;

[0034] Figure 14LiNi prepared with different lithium ratios 0.5 Co 0.2 Mn 0.3 O2 positive electrode material rate curve. DETAILED DESCRIPTION

[0035] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0036] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0037] The method for re-synthesizing the positive electrode material of a ternary lithium battery from retired ternary batteries of the present invention will be described in detail below with reference to the accompanying drawings.

[0038] Example 1: See Figure 1 As shown, according to an embodiment of the present invention, a method for re-synthesizing a ternary lithium battery positive electrode material from a retired ternary battery is provided. The method for re-synthesizing a ternary lithium battery positive electrode material from a retired ternary battery comprises:

[0039] Step 1, (Ni 0.5 Co 0.2 Mn 0.3 ) Leaching of 3O4 precursor: After the retired ternary battery is discharged, roasted, disassembled and ground, the required positive electrode material raw material is obtained, and the raw material is mixed with ammonium bisulfate to obtain a mixture. The material obtained after grinding, high-temperature roasting and pure water leaching is heated in a water bath and stirred, and filtered to obtain a leachate; specifically, the mixture is mixed evenly with a mortar, transferred to a crucible and set to a muffle furnace temperature of 400°C and calcined for 2h. When it is cooled to 100°C, it is taken out and immersed in a beaker with 100ml of pure water to ensure that there is no residue and no loss in the crucible. The beaker is placed in a water bath at 80°C, heated in a water bath and stirred for 1h, and filtered to obtain a leachate. In terms of mass fraction, the mixing ratio of ammonium bisulfate and positive electrode material is 3:1, and in terms of mass fraction, the ratio of pure water to ammonium bisulfate addition is 100:3.

[0040] Step 2, adjustment and precipitation of the leachate: 100 ml of the leachate was mixed with 150 ml of 0.8 mol / L oxalic acid solution, stirred evenly for 10 min, and then ammonia water was added to adjust the pH to 1.98. The mixture was stirred evenly in a water bath and then kept at 50 ° C for 24 h. The solution after standing was filtered to obtain an oxalate precipitate and a filtrate (the filtrate was saved and the volume was recorded). The oxalate precipitate was placed in an oven to dry to obtain 236 ml of filtrate. The molar amount of the oxalic acid solution added was (Ni 0.5 Co 0.2 Mn 0.3 )3O4 times,

[0041] Step 3, calcination of precipitate and lithium regeneration: drying the oxalate precipitate and calcining it at high temperature to obtain (Ni 0.5 Co 0.2 Mn 0.3 )3O4 precursor, the obtained (Ni 0.5 Co 0.2 Mn 0.3 )3O4 precursor is added with lithium carbonate and then regenerated by lithium supplementation to obtain regenerated Li(Ni 0.5 Co 0.2 Mn 0.3 )O2 ternary positive electrode material, the calcination temperature of oxalate sediment is 500℃ and the calcination time is 5h. When lithium is added for regeneration, the (Ni 0.5 Co 0.2 Mn 0.3 )3O4 precursor was placed in a calcination device and heated to 850℃ at 5℃ per minute and kept at this temperature for 12h. 0.5 Co 0.2 Mn 0.3 )The ratio of 3O4 precursor and lithium carbonate is 1:1.

[0042] Example 2:

[0043] The only difference from Example 1 is that in step 3, (Ni 0.5 Co 0.2 Mn 0.3 )The ratio of 3O4 precursor and lithium carbonate is 1:1.05.

[0044] Example 3:

[0045] The only difference from Example 1 is that in step 3, (Ni 0.5 Co 0.2 Mn 0.3 )The ratio of 3O4 precursor and lithium carbonate is 1:1.1.

[0046] Example 4:

[0047] The only difference from Example 1 is that in step 3, (Ni 0.5 Co 0.2 Mn 0.3 )The ratio of 3O4 precursor and lithium carbonate is 1:1.15.

[0048] Embodiment 5:

[0049] The only difference from Example 2 is that in step 3, when lithium is replenished and regenerated, the (Ni 0.5 Co 0.2 Mn 0.3 The 3O4 precursor was placed in a muffle furnace and heated at 5°C per minute to 800°C, and then calcined at 800°C for 12 hours.

[0050] Example 6:

[0051] The only difference from Example 2 is that in step 3, when lithium is replenished and regenerated, the (Ni 0.5 Co 0.2 Mn 0.3 The 3O4 precursor was placed in a muffle furnace and heated at 5°C per minute to 900°C, and then calcined at 900°C for 12 hours.

[0052] Comparative analysis and conclusions of Example 1 to Example 4:

[0053] The oxalate precursor was heated at 500℃ in air for 5 hours to obtain (Ni 0.5 Co 0.2 Mn 0.3 )3O4 intermediate, as shown in formula (1). Lithium carbonate is used as a lithium source to replenish lithium to the intermediate, and the principle is shown in formula (2).

[0054] 6(Ni 0.5 Co 0.2 Mn 0.3 )C2O4+4O2→2(Ni 0.5 Co 0.2 Mn 0.3 )3O4+12CO2(1) 4(Ni 0.5 Co 0.2 Mn 0.3 )3O4+6Li2CO3+O2→12Li(Ni 0.5 Co 0.2 Mn 0.3 )O2+6CO (2) Figure 7 The lithium ratio is 1:1, 1:1.05, 1:1.1, 1:1.15 regeneration Li (Ni 0.5 Co0.2 Mn 0.3 )O2XRD pattern, Li(Ni 0.5 Co 0.2 Mn 0.3 )O2 has an ordered layered structure, and it can be seen from the figure that it has clear diffraction peaks and back peaks.

[0055] The present invention observed the morphology of four groups of samples with lithium ratios of 1:1, 1:1.05, 1:1.1, and 1:1.05 by SEM. Figure 8-11 The lithium ratio is 1:1 and 1:1.05 at 850℃ calcination temperature and 12h.

[0056] , 1:1.1, 1:1.15 regenerated Li(Ni 0.5 Co 0.2 Mn 0.3 )O2 cathode material SEM morphology. From the above four groups of pictures, we can see that in the 5k low magnification electron microscope, the four ratios of recycled Li (Ni 0.5 Co 0.2 Mn 0.3 )O2 positive electrode material particles are all spherical, lithium ratio of 1:1, 1:1.1, 1:1.05 when Li (Ni 0.5 Co 0.2 Mn 0.3 ) The particles of the O2 positive electrode material are stacked on each other and have good agglomeration; while the lithium ratio is 1:

[0057] At 1.15, the particle size of the positive electrode material is uneven in some areas. It can be seen from the electron microscope at a high magnification of 20k that the regenerated Li(Ni 0.5 Co 0.2 Mn 0.3 )O2 positive electrode materials are all irregular in shape, with many small protrusions on the surface.

[0058] Conduct electrochemical performance test and place the assembled button cell in the glove box with H2O and O2 less than 0.1

[0059] After 12 hours of standing at room temperature, the battery was first charged to 4.5V at a constant current, then charged at a constant voltage, and finally subjected to a constant current charge and discharge test. Following these steps, the charge and discharge current was set at 0.2C for the first two cycles to achieve activation, and at 1C for the last 100 cycles. The charge and discharge voltage range was 3-4.5V.

[0060] When the charge and discharge voltage range is 3.0~4.5V and the charge and discharge rate is 1C, the first charge and discharge curves of the positive electrode materials prepared under different lithium ratio conditions are as follows: Figure 12 shown.

[0061] Table 1 shows the LiNi regenerated under different lithium ratios. 0.5 Co 0.2 Mn 0.3 The first charge and discharge capacity and coulomb efficiency data of O2 cathode material under 1C rate condition. As can be seen from Table 1, when the lithium ratio is 1:1, 1:1.05, 1:1, 1:1.15, the regenerated LiNi 0.5 Co 0.2 Mn 0.3 The first charge specific capacity of the O2 cathode material is 58.52 mAh g -1 , 125.19mAh·g -1 , 105.19mAh·g -1 、81.86mAh·g -1 , the discharge capacity is 57.16 mAh g -1 , 122.78mAh·g -1 、103.86mAh·g -1 , 79.96mAh·g -1 The coulombic efficiencies are 97.68%, 99.07%, 98.74%, and 98.89%.

[0062] When the lithium ratio is 1:1.05, the coulombic efficiency of the positive electrode material is the highest, reaching 99.07%. Figure 12 It can be seen that when the lithium ratio is 1:1, 1:1.15, 1:1.1, and 1:1.05, the first charge and discharge platform of the regenerated ternary positive electrode material is relatively flat, indicating that the ternary material prepared at a calcination temperature of 850°C for 12 hours has better cycle stability.

[0063] Taking all factors into consideration, it is believed that the first charge and discharge performance of the regenerated positive electrode material is best when the lithium ratio is 1:1.05.

[0064]

[0065] Figure 13 This graph shows the cycling performance of recycled cathode materials prepared with different lithium ratios at a charge-discharge rate of 1C, measured in a voltage range of 3.0 to 4.5V. As can be seen, the charge-discharge capacity of the cathode material over the first 50 cycles decreases with increasing charge-discharge cycles at different lithium ratios. The highest charge capacity and capacity retention are achieved when the lithium ratio is 1:1.05.

[0066] Table 2 shows the LiNi prepared under different lithium ratios 0.5 Co 0.2 Mn 0.3Cycling performance data of O2 positive electrode materials at 1C rate. From Table 3-2, it can be concluded that when the calcination time of the positive electrode material is 1:1, 1:1.1, 1:1.05, and 1:1.15, the charging capacity of the positive electrode material after the first 50 cycles is 48.33 mAh g -1 , 120.32mAh·g -1 , 122.38mAh·g -1 、85.93mAh·g -1 、83.2mAh·g -1 , the capacity retention rates were 37.15%, 74.63%, 70.65%, and 58.61%, respectively. Experiments have shown that as the lithium ratio of the recycled cathode material increases, its capacity retention after 50 cycles first increases and then decreases. When the lithium ratio reaches 1:1.05, the capacity retention rate reaches 74.63% after the first 50 cycles, indicating relatively good cycle performance.

[0067]

[0068] Figure 14 The Li(Ni) prepared under different lithium ratios were tested at a voltage range of 3.0 to 4.5 V at charge and discharge rates of 0.2C, 0.5C, 1C, 2C, 5C, and 1C. 0.5 Co 0.2 Mn 0.3 ) Rate performance curve of O2 positive electrode material. It can be clearly seen from the figure that when the charge and discharge rate gradually increases, the charge capacity of the positive electrode material shows a significant downward trend. When the lithium ratio is 1:1.05, the regenerated LiNi 0.5 Co 0.2 Mn 0.3 The discharge capacity of the O2 cathode material is 159.00 mAh g after 5 cycles at 0.2C rate. -1 When the discharge rate increases from 0.2C to 5C and then returns to 1C, the specific capacity of the positive electrode material is 120.26mAh·g -1 It was observed that with the gradual increase of lithium ratio, the rate performance of the positive electrode material showed a trend of first increasing and then decreasing, and when the lithium ratio was 1; 1.05, Li(Ni 0.5 Co 0.2 Mn 0.3 )O2 positive electrode material has the best rate performance.

[0069] The following conclusions were obtained through experiments in Examples 1 to 4 of the present invention:

[0070] Regeneration of LiNi by co-precipitation 0.5 Co 0.2 Mn 0.3The optimal synthesis conditions of O2 cathode material are calcination time 12h, calcination temperature 850℃, and lithium ratio 1:1.05. 0.5 Co 0.2 Mn 0.3 The O2 cathode material achieved good electrochemical performance, with a first charge-discharge capacity of 125.19 mAh g at a 1C rate. -1 , the discharge capacity is 122.78 mAh g -1 , the coulombic efficiency is 99.07%,

[0071] This experiment not only optimizes the traditional lithium-ion recovery process, improving efficiency and shortening the entire experimental cycle, but also achieves efficient energy utilization, significantly reducing overall energy consumption compared to traditional methods, which also reduces production costs. The regenerated cathode material was prepared using a co-precipitation method. Under the synthesis conditions of a calcination temperature of 850°C, a calcination time of 12 hours, and a lithium ratio of 1:1.05, the prepared cathode material exhibited excellent electrochemical performance.

[0072] Comparative analysis and conclusions of Example 2, Example 5 and Example 6:

[0073] In order to analyze the difference in surface morphology between the prepared recycled ternary lithium battery positive electrode material and the waste ternary positive electrode material, SEM characterization of the two materials was performed. Figure 5 As shown, the overall morphology of the two materials shows different characteristics. It can be seen that the surface of the recycled ternary lithium battery powder (b) is spinel-shaped and accompanied by layered distribution, while the overall surface of the retired ternary lithium battery powder (a) is spherical particles formed by the accumulation of small crystal particles.

[0074] In order to observe the differences in microstructure of recycled ternary lithium battery powder under different calcination temperatures, SEM characterization and analysis of these three types of battery powders were carried out. Figure 6 As shown in (a), it can be seen that when the calcination temperature is 800℃, there are some fine particles attached to the surface of the material, and the surface particles are unevenly distributed, the particle shape is irregular, and the particle size distribution is uneven. In comparison, the recycled ternary lithium battery powder material prepared by calcining at 850℃ (c) and 900℃ (b) has no obvious impurity particles attached, and the particle distribution is uniform and the particle morphology is regular. It can be seen that the recycled Li(Ni) 0.5 Co 0.2 Mn 0.3 )O2 powder particles have a better morphology.

[0075] Figure 3 LiNi 0.5 C0 0.2 Mn0.3 When the voltage of O2 positive electrode material is in the range of 3-4.5V and the charge-discharge rate is 1C, the LiNi prepared at different calcination temperatures 0.5 C0 0.2 Mn 0.3 The first charge and discharge curve of O2 cathode material. Figure 3 It can be seen that when the calcination temperature is 800℃, 850℃ and 900℃, the obtained ternary cathode material Li Ni 0.5 C0 0.2 Mn 0.3 The first charge and discharge platform of O2 is longer when compared with the calcination temperature of 850℃, which shows that the LiNi obtained by re-sintering at 850℃ 0.5 C0 0.2 Mn 0.3 The O2 ternary positive electrode material has a higher specific capacity, and its specific capacity is lower when sintered at 800℃ and 900℃.

[0076] Table 3 shows the LiNi prepared at different calcination temperatures. 0.5 C0 0.2 Mn 0.3 The capacity and coulombic efficiency data of the first charge and discharge of O2 positive electrode materials at a rate of 0.2C. As shown in Table 3.1, when the calcination temperature is 800℃, 850℃ and 900℃, the prepared LiNi 0.5 C0 0.2 Mn 0.3 The first charge and discharge capacities of the O2 material were 0.2885mAh, 0.3676mAh, and 0.1303mAh, respectively, and the coulombic efficiencies were 95.4%, 96.7%, and 94.9%, respectively. 0.5 C0 0.2 Mn 0.3 The coulombic efficiency of the O2 ternary cathode material is the highest, reaching 96.7%, and its charge capacity and discharge capacity are relatively high. Comprehensive analysis shows that when the sintering temperature is 850℃, the obtained ternary cathode material LiNi 0.5 C0 0.2 Mn 0.3 O2 has the best first charge and discharge performance.

[0077] Table 3 LiNi prepared at different calcination temperatures 0.5 Co 0.2 Mn 0.3 O2 cathode material first charge and discharge capacity and coulombic efficiency data table

[0078]

[0079] Figure 4The LiNi prepared at different sintering temperatures is shown in Figure 2. The voltage during the test is in the range of 3 to 4.5 V at a charge and discharge rate of 1C. 0.5 Co 0.2 Mn 0.3 Cycling performance curve of O2 ternary cathode material. Figure 4 As shown in the figure, at different sintering temperatures, LiN i 0.5 Co 0.2 Mn 0.3 The charge-discharge capacity of the first 50 cycles of the O2 cathode material decreases with the increase of the number of charge-discharge cycles. It can be seen that when the calcination temperature is 850℃, the LiNi 0.5 Co 0.2 Mn 0.3 O2 ternary positive electrode material has the highest charging capacity and capacity retention rate.

[0080] Table 4 is the LiNi prepared at different calcination temperatures 0.5 Co 0.2 Mn 0.3 O2 ternary positive electrode material cycle performance table at 1C rate. As shown in Table 4, when the calcination temperature of the positive electrode material is 800℃, 850℃, and 900℃, the charge capacity of the positive electrode material after the first 50 cycles is 0.2034mAh, 0.2734mAh, and 0.0472mAh, respectively, and the capacity retention rate is 70.5%, 74.4%, and 36.2%, respectively. The experiment found that the LiNi prepared under the calcination temperature of 850℃ 0.5 Co 0.2 Mn 0.3 After 50 cycles, the capacity retention rate of the O2 ternary positive electrode material is the highest, reaching 74.4%, and its cycle performance is the best in comparison.

[0081] Table 4 Lini prepared at different calcination temperatures 0.5 Co 0.2 Mn 0.3 O2 cycle performance data table

[0082]

[0083] like Figure 2 As shown, the charge and discharge rates are 0.2C, 0.5C, 1C, 2C, 5C, and 1C, respectively, and the test voltage is in the range of 3 to 4.5V. The Li(Ni 0.5 Co 0.2 Mn 0.3 ) Rate performance curve of O2 ternary cathode material. Figure 2 It can be clearly seen that when the charge and discharge rate increases, the charging capacity of the positive electrode material shows a clear downward trend.

[0084] When the calcination temperature is 850℃, the regenerated Li(Ni 0.5 Co 0.2 Mn 0.3 ) The specific capacity of the O2 cathode material is 159.00 mAh g after 5 discharge cycles at 0.2C rate. -1 When the discharge rate increases from 0.1C to 5C, the specific capacity of the positive electrode material is 82.35mAhg after 25 cycles. -1 When the discharge rate drops to 1C, the specific capacity of the positive electrode material after 30 cycles is 120.26 mAh g -1 ,The specific capacity of the positive electrode material tends to increase as the rate decreases.

[0085] The results show that:

[0086] (1) Changes in calcination temperature can affect the regeneration of LiNi 0.5 Co 0.2 Mn 0.3 The electrochemical performance of the O2 ternary cathode material. When the temperature is too high or too low, the electrochemical performance of the ternary cathode material will deteriorate accordingly.

[0087] (2) Regeneration of LiNi by indirect coprecipitation 0.5 Co 0.2 Mn 0.3 The optimal synthesis conditions of O2 cathode material are calcination temperature of 850℃, lithium ratio of 1:1.05, and calcination time of 12h. Under the optimal synthesis conditions, the prepared Li Ni 0.5 Co 0.2 Mn 0.3 The O2 cathode material has good electrochemical performance, with a specific capacity of 159.001 mAh g after 5 discharges at a 1C rate. -1 .

[0088] The indirect coprecipitation method studied in the present invention is used to prepare the regenerated ternary positive electrode material, when the lithium ratio is 1:

[0089] Under the optimal conditions of 1.05, calcination temperature of 850℃, and calcination time of 12h, the regenerated positive electrode material prepared has better electrochemical performance than that under other conditions.

[0090] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of the present invention.

Claims

1. A method for re-synthesizing ternary lithium battery positive electrode materials from retired ternary batteries, characterized in that: include, Step 1, (Ni 0.5 Co 0.2 Mn 0.3 ) Leaching of 3O4 precursor: The retired ternary battery is discharged, roasted, disassembled and ground to obtain the required positive electrode material raw material, which is then mixed with ammonium bisulfate to obtain a mixture. The mixture is then ground, roasted at high temperature, and leached with pure water, heated in a water bath and stirred, and filtered to obtain a leachate; Step 2, adjustment and precipitation of the leachate: Add oxalic acid solution to the leachate obtained in step 1, mix and stir, add ammonia water, adjust the pH value, keep warm and let stand, and filter the solution to obtain oxalate precipitate; Step 3, calcination of the precipitate and lithium regeneration: The oxalate precipitate is dried and calcined at high temperature to obtain (Ni 0.5 Co 0.2 Mn 0.3 )3O4 precursor, the obtained (Ni 0.5 Co 0.2 Mn 0.3 )3O4 precursor is added with lithium carbonate and then regenerated by lithium supplementation to obtain regenerated Li(Ni 0.5 Co 0.2 Mn 0.3 )O2 ternary positive electrode material.

2. The method for re-synthesizing a ternary lithium battery positive electrode material from retired ternary batteries according to claim 1, characterized in that: In step 1, the mixing ratio of ammonium bisulfate and the positive electrode material is 3-5:1 by mass.

3. The method for re-synthesizing a ternary lithium battery positive electrode material from retired ternary batteries according to claim 2, characterized in that: In step 1, the ratio of pure water to ammonium bisulfate added is 100:3 by mass fraction. After the pure water is leached, the water bath heating temperature is 80° C. and the water bath time is 1 h.

4. The method for re-synthesizing a ternary lithium battery positive electrode material from retired ternary batteries according to claim 3, characterized in that: In step 2, when preparing the oxalate precipitate, aqueous ammonia is added to the filtrate to adjust the pH value to 1.5-2.

5.

5. The method for re-synthesizing a ternary lithium battery positive electrode material from a retired ternary battery according to any one of claims 1 to 4, characterized in that: In step 3, the calcination temperature of the oxalate sediment is 500° C. and the calcination time is 5 h.

6. The method for re-synthesizing a ternary lithium battery positive electrode material from retired ternary batteries according to claim 5, characterized in that: In step 1, the mixture is calcined at a temperature of 400° C. and a calcination time of 2 h.

7. The method for re-synthesizing a ternary lithium battery positive electrode material from a retired ternary battery according to any one of claims 1 to 4 or 6, characterized in that: The molar amount of oxalic acid solution added in step 2 is ( Ni 0.5 Co 0.2 Mn 0.3 )1-1.2 times of 3O4.

8. The method for re-synthesizing a ternary lithium battery positive electrode material from retired ternary batteries according to any one of claims 1 to 4 or 6, characterized in that: In step 3, when lithium is added for regeneration, the (Ni 0.5 Co 0.2 Mn 0.3 The )3O4 precursor is placed in a calcination device and the temperature is set to rise by 5°C per minute to 800-900°C and kept at this temperature for 12 hours.

9. The method for re-synthesizing a ternary lithium battery positive electrode material from retired ternary batteries according to claim 8, characterized in that: After adding lithium carbonate (Ni 0.5 Co 0.2 Mn 0.3 The )3O4 precursor was placed in a calcination device and the temperature was raised to 850°C at 5°C per minute and kept at this temperature for 12 hours.

10. The method for re-synthesizing anode materials of ternary lithium batteries from retired ternary batteries according to any one of claims 1 to 4 or 6, characterized in that: In step 3, in parts by mass, (Ni 0.5 Co 0.2 Mn 0.3 )The ratio of 3O4 precursor to lithium carbonate is 1:1 or 1:1.05 or 1:1.1 or 1:1.15.

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