A method for regenerating a positive electrode material of a retired nickel-zinc battery and a regenerated positive electrode material obtained thereby

Abstract

The present application belongs to the technical field of nickel-zinc battery, and particularly relates to a regeneration method of positive electrode material of retired nickel-zinc battery and regenerated positive electrode material obtained by the method. The present application provides a method for leaching and directly regenerating the positive electrode material of the retired nickel-zinc battery by using organic acid. The positive electrode material is leached by using organic acid and without using reducing agent. The organic acid is superior to inorganic acid in safety and environmental protection. In the regeneration process, stirring and hydrothermal reaction are combined to realize the regeneration preparation of the nickel hydroxide composite material. The regeneration method is safe, simple and easy to operate, and has small environmental hazards.

Description

A method for regenerating cathode materials from retired nickel-zinc batteries and the resulting regenerated cathode materials. Technical Field

[0001] This invention belongs to the field of nickel-zinc battery technology, specifically relating to a method for regenerating cathode materials from retired nickel-zinc batteries and the resulting regenerated cathode materials. Background Technology

[0002] Aqueous nickel-zinc batteries, due to their high operating voltage, high energy density, high power density, long cycle life, and advantages such as being green, pollution-free, and safe, have gradually replaced some lithium-ion batteries as next-generation energy storage devices, showing great application potential in high-power demand equipment, new energy storage, and special equipment. With technological breakthroughs and industrialization of nickel-zinc batteries, the disposal of retired nickel-zinc batteries is imminent. Retired nickel-zinc battery materials contain high-value metals such as nickel, cobalt, and zinc, possessing significant recycling value. Their green recycling can effectively improve resource utilization, reduce dependence on primary resource extraction, and effectively alleviate the increasing resource shortage caused by rapid productivity growth.

[0003] Currently, the main method for nickel recovery is inorganic acid leaching, followed by impurity removal and extraction, and finally, concentration and crystallization of the nickel-containing solution to obtain inorganic nickel salts. This recovery method is similar to the nickel recovery approach in lithium-ion battery ternary materials, and the process is relatively mature, but it suffers from difficulties in separation and impurity removal, as well as the environmental hazards of the extractant.

[0004] Furthermore, based on recycling, there have been studies on regenerating cathode materials. However, existing regeneration methods mainly use ammonia as a complexing agent, while ammonia has strong volatility and an irritating odor, which imposes a certain burden on the environment. Summary of the Invention

[0005] The purpose of this invention is to provide a method for regenerating retired nickel-zinc battery cathode materials and the resulting regenerated cathode materials.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for regenerating cathode materials from retired nickel-zinc batteries, comprising the following steps:

[0008] The cathode material of retired nickel-zinc batteries is leached with organic acid to obtain a leachate; the leachate contains nickel ions and cobalt ions.

[0009] The molar ratio of nickel ions to cobalt ions in the leachate is adjusted so that the molar ratio of nickel ions to cobalt ions is y, wherein y satisfies: y = 15 (1-x) / 11.5x, then mixed with alkaline solution, and subjected to hydrothermal reaction to obtain regenerated cathode material;

[0010] The regenerated cathode material comprises nickel-cobalt hydroxide and carbon doped in the nickel-cobalt hydroxide; the chemical composition of the nickel-cobalt hydroxide is Ni. 1-x Co x (OH)2;

[0011] The value of x ranges from 0.01 to 0.3.

[0012] Preferably, the organic acid includes at least one selected from oxalic acid, acetic acid, citric acid, and malic acid.

[0013] Preferably, the concentration of the organic acid is 1~4 mol / L.

[0014] Preferably, the solid-liquid ratio of the leaching is 10~80g / L.

[0015] Preferably, the leaching temperature is 25~105℃ and the leaching time is 30~300min;

[0016] The leaching process is as follows: the retired nickel-zinc battery cathode material is placed in an organic acid for ultrasonic dispersion and heated to the leaching temperature, and then leached by stirring at the leaching temperature; the stirring speed is preferably 100~1000 rpm.

[0017] Preferably, the alkaline solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, urea solution and sodium carbonate solution; the concentration of the alkaline solution is 2~5 mol / L.

[0018] Preferably, the mixing method is as follows: the leachate is added dropwise to the alkaline solution under stirring conditions; during the dropwise addition process, the pH value of the system is controlled to be ≥11.

[0019] Preferably, after the dropwise addition, the system is further subjected to stirring and mixing for 30 to 360 minutes.

[0020] Preferably, the hydrothermal reaction is carried out at a temperature of 100-180°C for 6-12 hours.

[0021] The present invention also provides a regenerated cathode material obtained by the regeneration method described above, wherein the regenerated cathode material comprises nickel cobalt hydroxide and carbon doped in the nickel cobalt hydroxide;

[0022] The chemical composition of the nickel-cobalt hydroxide is Ni 1-x Co x (OH)2;

[0023] The value of x ranges from 0.01 to 0.3.

[0024] This invention provides a method for regenerating retired nickel-zinc battery cathode materials, comprising the following steps: leaching the retired nickel-zinc battery cathode materials using an organic acid to obtain a leachate; the leachate comprising nickel ions and cobalt ions; adjusting the molar ratio of nickel ions to cobalt ions in the leachate to a value of y, wherein y satisfies: y = 15 (1-x) / 11.5x, then mixed with alkaline solution, undergoes a hydrothermal reaction to obtain a regenerated cathode material; the regenerated cathode material comprises nickel-cobalt hydroxide and carbon doped in the nickel-cobalt hydroxide; the chemical composition of the nickel-cobalt hydroxide is Ni 1-x Co x (OH)2; the value of x ranges from 0.01 to 0.3.

[0025] This invention provides a method for leaching and directly regenerating retired nickel-zinc battery cathode materials using organic acids. The leaching of the cathode material with organic acids eliminates the need for reducing agents, and organic acids are superior to inorganic acids in terms of safety and environmental friendliness. The regeneration process combines stirring and hydrothermal reaction to achieve the regeneration of nickel hydroxide composite materials. This regeneration method is safe, simple, easy to implement, and has minimal environmental impact. Attached Figure Description

[0026] Figure 1 is a schematic flowchart of the regeneration method provided by the present invention;

[0027] Figure 2 shows the XRD pattern of the recycled composite material obtained in Example 4;

[0028] Figure 3 is a SEM image of the recycled composite material obtained in Example 4;

[0029] Figure 4 is an XPS image of the recycled composite material obtained in Example 4;

[0030] Figure 5 shows the XRD patterns of the recycled composite materials obtained in Comparative Examples 1-4. Detailed Implementation

[0031] Figure 1 is a schematic flowchart of the regeneration method provided by the present invention. The technical solution will be described in detail below with reference to Figure 1.

[0032] This invention provides a method for regenerating cathode materials from retired nickel-zinc batteries, comprising the following steps:

[0033] The cathode material of retired nickel-zinc batteries is leached with organic acid to obtain a leachate; the leachate contains nickel ions and cobalt ions.

[0034] The molar ratio of nickel ions to cobalt ions in the leachate is adjusted so that the molar ratio of nickel ions to cobalt ions is y, wherein y satisfies: y = 15 (1-x) / 11.5x, then mixed with alkaline solution, and subjected to hydrothermal reaction to obtain regenerated cathode material;

[0035] The regenerated cathode material comprises nickel-cobalt hydroxide and carbon doped in the nickel-cobalt hydroxide; the chemical composition of the nickel-cobalt hydroxide is Ni. 1-x Co x (OH)2;

[0036] The value of x ranges from 0.01 to 0.3.

[0037] This invention involves leaching retired nickel-zinc battery cathode materials using organic acids to obtain a leachate.

[0038] This invention does not impose any particular limitation on the origin of the retired nickel-zinc battery positive electrode material; it can be obtained using methods well-known to those skilled in the art. In this invention, the preparation of the retired nickel-zinc battery positive electrode material preferably includes: dismantling a waste nickel-zinc battery to obtain a positive electrode sheet; and calcining the positive electrode sheet to obtain the retired nickel-zinc battery positive electrode material. In this invention, the calcination temperature is preferably 500°C, the holding time is preferably 2 hours, the heating rate is preferably 10°C / min, and the calcination atmosphere is preferably air; calcination can remove the binder and conductive agent.

[0039] In this invention, the organic acid preferably includes at least one selected from oxalic acid, acetic acid, citric acid, and malic acid; the concentration of the organic acid is preferably 1-4 mol / L, specifically 1 mol / L, 2 mol / L, 3 mol / L, or 4 mol / L; the solid-liquid ratio of the leaching is preferably 10-80 g / L, specifically 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, or 80 g / L; the leaching temperature is preferably 25-105℃, specifically 25℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, or 105℃; and the leaching time is preferably 30-300 min, specifically 30 min, 60 min, 90 min, 120 min, 150 min, 180 min, 210 min, 240 min, 270 min, or 300 min. In this invention, the leaching process is preferably as follows: the retired nickel-zinc battery cathode material is placed in an organic acid for ultrasonic dispersion and heated to the leaching temperature, and then stirred and leached at the leaching temperature; the stirring speed is preferably 100~1000 rpm, specifically 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, or 1000 rpm.

[0040] After leaching, the present invention preferably further includes filtering the obtained system to obtain a leachate.

[0041] After obtaining the leachate, the present invention adjusts the molar ratio of nickel ions to cobalt ions in the leachate so that the molar ratio of nickel ions to cobalt ions is y, wherein y satisfies: y = 15 (1-x) / 11.5x, then mixed with alkaline solution, and subjected to hydrothermal reaction to obtain regenerated cathode material.

[0042] The present invention does not impose any special limitations on the adjustment process, and any process known to those skilled in the art can be used.

[0043] In this invention, the alkaline solution preferably includes at least one selected from sodium hydroxide solution, potassium hydroxide solution, ammonia water, urea solution, and sodium carbonate solution; the concentration of the alkaline solution is preferably 2-5 mol / L, specifically 2 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L. In this invention, the mixing method is preferably as follows: the leachate is added dropwise to the alkaline solution under stirring conditions; the stirring speed is preferably 100-1000 rpm, specifically 100 rpm, 300 rpm, 500 rpm, 800 rpm, or 1000 rpm; the dropping rate is preferably 0.1-1 mL / min, specifically 0.1 mL / min, 0.5 mL / min, or 1 mL / min; the pH value of the system is preferably controlled to be ≥11 during the dropping process; the dropping temperature is preferably 25-85℃, specifically 25℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, or 85℃.

[0044] In this invention, after the dropwise addition, it is preferable to further include stirring and mixing the obtained system. The stirring and mixing temperature is preferably 25~85℃, specifically 25℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, or 85℃; the stirring time is preferably 30~360min, specifically 30min, 60min, 90min, 120min, 180min, 240min, 300min, or 360min; and the stirring speed is preferably 100~1000rpm, specifically 100rpm, 300rpm, 500rpm, 800rpm, or 1000rpm.

[0045] In this invention, the preferred temperature for the hydrothermal reaction is 100~180℃, specifically 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, or 180℃; the preferred time is 6~12h, specifically 6h, 7h, 8h, 9h, 10h, 11h, or 12h. In this invention, after the hydrothermal reaction, it is also preferable to filter the obtained system, wash the obtained precipitate until neutral, and then dry and grind it.

[0046] In this invention, the regenerated cathode material comprises nickel-cobalt hydroxide and carbon doped in the nickel-cobalt hydroxide; the chemical composition of the nickel-cobalt hydroxide is Ni. 1-x Co x (OH)₂; the value of x ranges from 0.01 to 0.3, specifically 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3. In this invention, the Ni 1-x Co x (OH)2 and y=15 The value of x in (1-x) / 11.5x is the same.

[0047] This invention also provides a regenerated cathode material obtained by the regeneration method described above, wherein the regenerated cathode material comprises nickel cobalt hydroxide and carbon doped in the nickel cobalt hydroxide; the chemical composition of the nickel cobalt hydroxide is Ni. 1-x Co x (OH)₂; the value of x ranges from 0.01 to 0.3. In this invention, the percentage of carbon doping atoms in the recycled cathode material is preferably 10% to 30%.

[0048] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0049] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0050] In the following embodiments, the preparation of the retired nickel-zinc battery positive electrode material includes: disassembling the waste nickel-zinc battery to obtain a positive electrode sheet; calcining the positive electrode sheet in air at a heating rate of 10°C / min to 500°C and holding it at that temperature for 2 hours to obtain the retired nickel-zinc battery positive electrode material.

[0051] Example 1

[0052] Retired nickel-zinc battery cathode material was placed in a 1 mol / L citric acid solution (solid-liquid ratio 50 g / L), ultrasonically dispersed, and then heated to 95°C. The mixture was stirred at 500 rpm for 1 hour at this temperature. After filtration, a leachate was obtained. ICP-OES testing showed that the leaching rate of nickel ions was 90.8%, and the leaching rate of cobalt ions was 90.5%.

[0053] The molar ratio of nickel ions to cobalt ions in the leachate was adjusted to 63.9:1. The leachate was added dropwise to a 4 mol / L sodium hydroxide solution at a dropping rate of 0.5 mL / min at 25°C and 500 rpm, maintaining the pH of the reaction system at ≥11. After the addition was complete, the mixture was stirred at 500 rpm for 4 hours at 25°C, then transferred to a hydrothermal reactor and reacted at 150°C for 8 hours. After the reaction, the mixture was filtered, and the resulting precipitate was washed until neutral, dried, and ground to obtain regenerated Ni. 1-x Co x (OH)2 / C, where x is 0.02 and the atomic percentage of carbon is 11.5%.

[0054] Example 2

[0055] Retired nickel-zinc battery cathode materials were placed in a 3 mol / L citric acid solution (solid-liquid ratio 50 g / L), ultrasonically dispersed, and then heated to 95°C. The mixture was stirred at 500 rpm for 1 hour at this temperature. After filtration, a leachate was obtained. ICP-OES testing showed that the leaching rate of nickel ions in the leachate was 95.9%, and the leaching rate of cobalt ions was 92.4%.

[0056] The molar ratio of nickel ions to cobalt ions in the leachate was adjusted to 31.3:1. The leachate was added dropwise to a 4 mol / L sodium hydroxide solution at a dropping rate of 0.5 mL / min at 25°C and 500 rpm, maintaining the pH of the reaction system at ≥11. After the addition was complete, the mixture was stirred at 500 rpm for 4 hours at 25°C, then transferred to a hydrothermal reactor and reacted at 150°C for 8 hours. After the reaction, the mixture was filtered, and the resulting precipitate was washed until neutral, dried, and ground to obtain regenerated Ni. 1-x Co x (OH)2 / C, where x is 0.04 and the atomic percentage of carbon is 14.8%.

[0057] Example 3

[0058] Retired nickel-zinc battery cathode materials were placed in a 4 mol / L citric acid solution (solid-liquid ratio 50 g / L), ultrasonically dispersed, and then heated to 75°C. The mixture was stirred at 500 rpm for 3 hours at this temperature. After filtration, a leachate was obtained. ICP-OES testing showed that the leaching rate of nickel ions in the leachate was 93.5%, and the leaching rate of cobalt ions was 94.2%.

[0059] The molar ratio of nickel ions to cobalt ions in the leachate was adjusted to 15:1. The leachate was added dropwise to a 4 mol / L sodium hydroxide solution at a dropping rate of 0.5 mL / min at 25°C and 500 rpm, maintaining the pH of the reaction system at ≥11. After the addition was complete, the mixture was stirred at 500 rpm for 4 hours at 25°C, then transferred to a hydrothermal reactor and reacted at 150°C for 8 hours. After the reaction, the mixture was filtered, and the resulting precipitate was washed until neutral, dried, and ground to obtain regenerated Ni. 1-x Co x (OH)2 / C, where x is 0.08 and the atomic percentage of carbon is 15.2%.

[0060] Example 4

[0061] Retired nickel-zinc battery cathode materials were placed in a 3 mol / L citric acid solution (solid-liquid ratio 50 g / L), ultrasonically dispersed, and then heated to 95°C. The mixture was stirred at 500 rpm for 3 hours at this temperature. After filtration, a leachate was obtained. ICP-OES testing showed that the leaching rate of nickel ions was 98.9%, and the leaching rate of cobalt ions was 99%.

[0062] The molar ratio of nickel ions to cobalt ions in the leachate was adjusted to 6.8:1. The leachate was added dropwise to a 4 mol / L sodium hydroxide solution at a dropping rate of 0.5 mL / min at 25°C and 500 rpm, maintaining the pH of the reaction system at ≥11. After the addition was complete, the mixture was stirred at 500 rpm for 4 hours at 25°C, then transferred to a hydrothermal reactor and reacted at 150°C for 8 hours. After the reaction, the mixture was filtered, and the resulting precipitate was washed until neutral, dried, and ground to obtain regenerated Ni. 1-x Co x (OH)2 / C, where x is 0.16 and the atomic percentage of carbon is 14.6%.

[0063] Example 5

[0064] The leachate was obtained according to the method described in Example 4;

[0065] The molar ratio of nickel ions to cobalt ions in the leachate was adjusted to 5.2:1 to obtain regenerated Ni. 1-x Co x(OH)2 / C, where x is 0.2 and the atomic percentage of carbon is 14.7%.

[0066] Example 6

[0067] The leachate was obtained according to the method described in Example 4;

[0068] The molar ratio of nickel ions to cobalt ions in the leachate was adjusted to 3.9:1 to obtain regenerated Ni. 1-x Co x (OH)2 / C, where x is 0.25 and the atomic percentage of carbon is 14.8%.

[0069] Comparative Example 1

[0070] The leachate was obtained according to the method described in Example 4;

[0071] The molar ratio of nickel ions to cobalt ions in the leachate was adjusted to 6.8:1. At 25°C and 500 rpm, 5 mL of 4 mol / L sodium hydroxide solution was repeatedly added to the leachate until the system became turbid, resulting in a green gel-like filtrate. The filtrate was washed until neutral, dried, and ground to obtain a regenerated nickel hydroxide composite material.

[0072] Comparative Example 2

[0073] Leachate obtained according to the method in Example 4;

[0074] The molar ratio of nickel ions to cobalt ions in the leachate was adjusted to 6.8:1. The leachate obtained above was added dropwise to a 4 mol / L sodium hydroxide solution at a dropping rate of 0.5 mL / min at 25 °C and 500 rpm, maintaining the pH of the reaction system at ≥11. After the addition was completed, the mixture was stirred at 25 °C and 500 rpm for 24 h and then filtered (i.e., without hydrothermal treatment). The precipitate was washed until neutral, dried, and ground to obtain the regenerated nickel hydroxide composite material.

[0075] Comparative Example 3

[0076] Leachate obtained according to the method in Example 4;

[0077] The molar ratio of nickel ions to cobalt ions in the leachate was adjusted to 6.8:1. The leachate obtained above was added dropwise to a 4 mol / L sodium hydroxide solution at a dropping rate of 0.5 mL / min at 25 °C and 500 rpm, maintaining the pH of the reaction system at ≥11. After the addition was completed, the mixture was stirred at 500 rpm for 4 h at 25 °C and then transferred to a hydrothermal reactor. The mixture was reacted at 150 °C for 4 h. After the reaction was completed, the mixture was filtered, and the resulting precipitate was washed until neutral, dried, and ground to obtain the regenerated nickel hydroxide composite material.

[0078] Comparative Example 4

[0079] Leachate obtained according to the method in Example 4;

[0080] The molar ratio of nickel ions to cobalt ions in the leachate was adjusted to 6.8:1. The leachate obtained above was added dropwise to a 6 mol / L sodium hydroxide solution at a dropping rate of 0.5 mL / min at 25 °C and 500 rpm, maintaining the pH of the reaction system at ≥11. After the addition was completed, the mixture was stirred at 500 rpm for 4 h at 25 °C and then transferred to a hydrothermal reactor. The reaction was carried out at 150 °C for 8 h. After the reaction was completed, the mixture was filtered, and the resulting precipitate was washed until neutral, dried, and ground to obtain the regenerated nickel hydroxide composite material.

[0081] Performance testing

[0082] Test Example 1

[0083] Figure 2 shows the XRD pattern of the recycled composite material obtained in Example 4. As can be seen from Figure 2, the recycled Ni obtained in this invention... 1-x Co x The (OH)2 / C composite material has a good crystal structure and perfectly matches the β-nickel hydroxide standard card, with no impurity peaks;

[0084] Figure 3 is a SEM image of the recycled composite material obtained in Example 4. As can be seen from Figure 3, the recycled product has an obvious lamellar structure.

[0085] Figure 4 shows the XPS image of the recycled composite material obtained in Example 4. As can be seen from Figure 4: Ni 2p 2 / 3 and Ni 2p 1 / 2 The fitting peaks at 855.6 eV and 873.4 eV in the photoelectron spectrum both originate from divalent Ni. 2+ The photoelectrons revealed spin-orbit splitting in the Ni 2p energy level. This spin energy separation difference of approximately 17.6 eV provides conclusive evidence for the presence of nickel hydroxide. In the fine spectrum of O 1s, the characteristic peaks at 530.8 eV and 533.5 eV belong to OH, respectively. - The presence of metal hydroxides further confirmed the successful preparation of nickel hydroxide. XPS full spectrum and fine Co 2p spectrum demonstrated the presence of a small amount of Co(OH)2 in the regenerated product. The carbon in the regenerated product originated from organic acids, as evidenced by CO and C=O in C 1s.

[0086] Figure 5 shows the XRD patterns of the recycled composite materials obtained in Comparative Examples 1-4. It can be seen that: Comparative Example 1, by introducing sodium hydroxide solution into the leachate in portions, yielded a green gel-like product. No characteristic peaks were observed in its XRD pattern, indicating that a faster mixing rate is not conducive to the nucleation and growth of nickel hydroxide crystals. Comparative Example 2, based on the preparation method of the examples, removed the hydrothermal reaction and extended the stirring time. Its XRD pattern showed a wide band at the characteristic peak position, indicating that the crystal growth driving force under stirring alone was insufficient. Comparative Example 3, based on the preparation method of the examples, shortened the hydrothermal time (from 8h to 4h). Its XRD pattern corresponded to the characteristic peak, but the intensity was weak, indicating the importance of hydrothermal reaction parameters for crystal growth. Comparative Example 4, based on the preparation method of the examples, increased the concentration of sodium hydroxide (from 4mol / L to 6mol / L). Its XRD pattern corresponded to the characteristic peak, but obvious impurity peaks were present, indicating the importance of sodium hydroxide concentration for crystal growth and product purity.

[0087] Test Example 2

[0088] The electrochemical performance of the recycled materials obtained in the test examples and comparative examples was tested.

[0089] The recycled materials are assembled into batteries. The specific assembly process is as follows: A positive electrode slurry is prepared by mixing recycled materials, Super P, zinc powder, carboxymethyl cellulose, and polytetrafluoroethylene (60wt% PTFE aqueous solution) in a mass ratio of 80:10:3:2:5. This slurry is then coated onto nickel foam and dried to serve as the positive electrode. A negative electrode slurry is prepared by mixing commercial ZnO, Zn, Al2O3, Bi2O3, and polytetrafluoroethylene (60wt% PTFE aqueous solution) in a mass ratio of 70:20:3:2:5. This slurry is then coated onto a tin-plated copper mesh and dried to serve as the negative electrode. A soft-pack NiZn battery is assembled and its electrical performance is tested. The separator is a hydrophilic PP membrane, and the electrolyte is a 30wt% KOH aqueous solution of saturated ZnO with LiOH as an additive. The mass ratio of electrolyte to electrode in the battery is approximately 1:3.

[0090] Battery performance test parameters: 2.5A constant current and constant voltage charging to 1.9V (cutoff current is 0.05A), after standing for 2 minutes, 5A constant current discharging to 1.2V; the performance test results of the assembled battery are shown in Table 1.

[0091] Table 1. Performance test results of batteries assembled from recycled materials obtained in the examples and comparative examples.

[0092]

[0093] Table 1 shows that the battery prepared from the recycled product obtained in Example 4 has the highest specific capacity and the longest cycle count with 60% capacity retention. When the cobalt content in the recycled product is low (x < 0.16, Examples 1-3), its specific capacity and cycle performance are lower than those of Example 4, indicating that the bimetallic synergistic effect in the recycled product can improve the specific capacity and cycle performance of the battery to a certain extent. When the cobalt content in the recycled product is high (x > 0.16, Examples 5-6), its specific capacity and cycle performance are also lower than those of Example 4, but significantly better than those of Examples 1-3, indicating that the relationship between cobalt content and electrical performance is not completely linear, and optimal performance can only be achieved with appropriate cobalt doping.

[0094] Comparative Example 1 exhibited lower specific capacity and faster capacity decay in battery tests due to incomplete formation of nickel hydroxide and poor crystal structure. Comparative Example 2 also had poor crystal structure, but it showed peak signals at the characteristic peak positions of the β-nickel hydroxide standard card, resulting in poorer specific capacity and cycle performance, though still better than Comparative Example 1. Comparative Example 3 showed significantly enhanced XRD characteristic peak signals after hydrothermal treatment, resulting in better specific capacity and cycle performance than Comparative Examples 1 and 2 in electrical performance tests. However, its battery performance was significantly worse than Example 4 due to insufficient hydrothermal treatment time, indicating that hydrothermal treatment not only promotes crystal growth but also enhances the electrical performance of the material. Comparative Example 4 showed a very high match with the β-nickel hydroxide standard card and strong peak shape, but contained a small number of impurity peaks. Its battery performance was significantly better than Comparative Examples 1-3.

[0095] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for regenerating cathode material from retired nickel-zinc batteries, characterized in that, The steps are as follows: The retired nickel-zinc battery cathode material is leached with organic acid to obtain a leachate; the leachate includes nickel ions and cobalt ions; the molar ratio of nickel ions to cobalt ions in the leachate is adjusted to y, where y satisfies: y = 15*(1-x) / 11.5x, and then mixed with an alkaline solution for a hydrothermal reaction to obtain a regenerated cathode material; the hydrothermal reaction temperature is 100~180℃, and the time is 6~12h; the alkaline solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia, urea solution, and sodium carbonate solution; the concentration of the alkaline solution is 2~5 mol / L; the mixing method is as follows: the leachate is added dropwise to the alkaline solution under stirring; the pH value of the system is controlled to be ≥11 during the dropwise addition; the regenerated cathode material includes nickel-cobalt hydroxide and carbon doped in the nickel-cobalt hydroxide; the chemical composition of the nickel-cobalt hydroxide is Ni 1-x Co x (OH)2; the value of x ranges from 0.01 to 0.3; the Ni 1-x Co x The value of x in (OH)2 and y=15*(1-x) / 11.5x is the same.

2. The regeneration method according to claim 1, characterized in that, The organic acid includes at least one of oxalic acid, acetic acid, citric acid, and malic acid.

3. The regeneration method according to claim 1 or 2, characterized in that, The concentration of the organic acid is 1~4 mol / L.

4. The regeneration method according to claim 3, characterized in that, The solid-liquid ratio of the cathode material and organic acid in the retired nickel-zinc battery is 10~80g / L.

5. The regeneration method according to claim 3, characterized in that, The leaching temperature is 25~105℃, and the time is 30~300min; the leaching process is as follows: the retired nickel-zinc battery cathode material is placed in organic acid for ultrasonic dispersion and heated to the leaching temperature, and then stirred and leached at the leaching temperature; the stirring speed is 100~1000rpm.

6. The regeneration method according to claim 1, characterized in that, After the droplet addition, the system is further subjected to stirring and mixing for 30 to 360 minutes.

7. The regenerated cathode material obtained by the regeneration method according to any one of claims 1 to 6, characterized in that, The regenerated cathode material comprises nickel-cobalt hydroxide and carbon doped in the nickel-cobalt hydroxide; the chemical composition of the nickel-cobalt hydroxide is Ni. 1-x Co x (OH)2; the value of x ranges from 0.01 to 0.3.

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