Alkaline secondary battery positive electrode material based on waste lithium cobalt oxide material as well as preparation method and application of alkaline secondary battery positive electrode material

Abstract

The invention discloses an alkaline secondary battery positive electrode material based on a waste lithium cobalt oxide material and a preparation method and application thereof, the alkaline secondary battery positive electrode material comprises a positive electrode active material and a cobalt-based additive, the cobalt-based additive is a compound of lithium-deficient lithium cobalt oxide and carbon, the chemical general formula of the cobalt-based additive is Li1-xCoO2 / C, 0.2 < = xlt; 1, the cobalt-based additive is derived from a lithium cobalt oxide positive electrode material of a waste lithium ion battery, and the cobalt-based additive and a positive electrode active material are mixed to prepare a high-performance alkaline secondary battery positive electrode material; according to the invention, an expensive traditional cobalt additive is replaced with extremely low cost, so that the production cost of the alkaline battery is remarkably reduced, meanwhile, the conductivity, cycling stability and rate capability of the electrode are effectively improved by utilizing the network structure of residual carbon in the compound, and an efficient and green new way is provided for recycling of waste lithium batteries.

Description

Technical Field

[0001] This invention belongs to the field of resource utilization technology of alkaline secondary battery cathode materials and waste lithium cobalt oxide cathode materials of lithium-ion batteries, specifically involving an alkaline secondary battery cathode material based on waste lithium cobalt oxide materials, its preparation method and application. Background Technology

[0002] Alkaline secondary batteries, such as nickel-metal hydride (Ni-MH) and nickel-cadmium (Ni-Cd) batteries, still hold a significant market share in power tools, backup power supplies, and some consumer electronics due to their advantages of good safety, high rate performance, and relatively low cost. Their positive electrode active materials are primarily nickel hydroxide (Ni(OH)2) or modified nickel-based materials (such as nickel-based hydrotalcite). To improve the conductivity of the positive electrode material, suppress the expansion of the active material, and improve the oxygen evolution overpotential, small amounts of cobalt-based additives, such as CoO, Co(OH)2, or metallic cobalt, are usually added. However, these cobalt-based additives are expensive, significantly increasing the production cost of the batteries. For example, patent document CN200810135390.8 discloses an alkaline secondary battery positive electrode material, a positive electrode, and an alkaline secondary battery. The alkaline secondary battery positive electrode material contains a positive electrode active material, a binder, and a cobalt additive, which is one or more of Co, Co(OH)2, Co2O3, Co3O4, and CoO. Patent document CN200510126001.1 discloses an alkaline secondary battery positive electrode material and an alkaline secondary battery. The alkaline secondary battery positive electrode material contains nickel hydroxide powder, a cobalt additive, and a binder. This positive electrode material also contains metal powder, with the metal selected from one or more of vanadium, titanium, molybdenum, manganese, niobium, hafnium, zirconium, yttrium, and tantalum. The cobalt additive is one or more of Co, Co(OH)2, Co2O3, Co3O4, and CoO. The performance improvement of alkaline secondary batteries in the above patented technologies is highly dependent on metallic cobalt, which severely restricts the further promotion and application of alkaline secondary batteries in cost-sensitive markets.

[0003] On the other hand, with the widespread application and large-scale retirement of lithium-ion batteries, how to environmentally and economically recycle and dispose of waste lithium-ion batteries, especially the valuable cathode materials (such as lithium cobalt oxide), has become a global issue. Traditional recycling methods for waste lithium-ion batteries mainly focus on hydrometallurgical or pyrometallurgical extraction of valuable metals such as cobalt and lithium. These recycling processes are complex, energy-intensive, and may generate secondary pollution. Their economic viability is also greatly affected by fluctuations in metal market prices. For example, patent document CN201410366935.1 discloses a method for recovering cobalt, lithium, and aluminum from waste lithium-ion battery cathode sheets. The waste lithium-ion batteries are discharged and disassembled. The waste cathode sheets are calcined and dissolved in water, then filtered to obtain waste lithium cobalt oxide powder and aluminum foil. The waste lithium cobalt oxide powder is mixed with sodium bisulfate or sodium pyrosulfate and ball-milled, then calcined at a low temperature. The calcined product is leached with water, and the leachate is subjected to cobalt precipitation and lithium precipitation to obtain cobalt oxalate and lithium carbonate. Patent document CN201611114126.7 discloses a method for recovering and preparing new electrodes from waste lithium-ion batteries. The discharge process of lithium-ion batteries involves manual disassembly to obtain the positive electrode material. After calcination, the material is added to water and stirred, then sieved and dried to obtain lithium cobalt oxide powder. This powder is then ball-milled and mixed with a solution of natural organic acid and hydrogen peroxide. After the reaction is complete, ammonium oxalate solution is added to precipitate cobalt oxalate. Lithium salt powder is then added, ground evenly, and calcined to obtain lithium cobalt oxide powder that can be directly used as an electrode material. Waste lithium-ion batteries are recycled, and new lithium cobalt oxide electrodes are synthesized from the recycled lithium cobalt oxide material. The preparation uses natural organic acid raw materials to avoid secondary pollution caused by waste liquid treatment. None of the above patented technologies mention using recycled waste lithium cobalt oxide positive electrode material as an additive for alkaline secondary battery positive electrode materials.

[0004] In conclusion, finding a way to directly utilize the high-value and resource-based lithium cobalt oxide cathode material from waste lithium-ion batteries and replace traditional expensive cobalt-based additives is of great significance for reducing the cost of alkaline secondary batteries and promoting the sustainable development of the lithium battery recycling industry. Summary of the Invention

[0005] The technical problem solved by this invention is to provide an alkaline secondary battery cathode material based on waste lithium cobalt oxide and its preparation method. The method uses lithium cobalt oxide recycled from waste lithium-ion batteries as a cobalt-based functional additive to further prepare alkaline secondary battery cathode material. The process is simple and suitable for large-scale production. It also provides a cathode plate containing the above-mentioned cathode material and an alkaline secondary battery, aiming to reduce raw material costs, realize high-value utilization of waste, and ultimately obtain an alkaline secondary battery with excellent electrochemical performance.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] An alkaline secondary battery cathode material based on waste lithium cobalt oxide material is disclosed. This alkaline secondary battery cathode material comprises a cathode active material and a cobalt-based additive. The cathode active material is one or more of nickel hydroxide, nickel-based hydrotalcite, and manganese dioxide. The cobalt-based additive is a complex of lithium cobalt oxide lacking lithium and carbon, with the general chemical formula Li. 1-x CoO2 / C, where 0.2≤x<1, and the carbon in the complex of lithium cobalt oxide and carbon with lithium deficiency is a conductive carbon material. This cobalt-based additive is derived from the lithium cobalt oxide cathode material of waste lithium-ion batteries.

[0008] Further specifying, the mass percentage of cobalt-based additives in the alkaline secondary battery cathode material is 0.5% to 20%, and the mass percentage of carbon in the lithium-deficient lithium cobalt oxide and carbon complex is 1% to 10%. The cobalt-based additives are either lithium-deficient lithium cobalt oxide and carbon complexes obtained directly from pretreated waste lithium-ion batteries, or lithium-deficient lithium cobalt oxide and carbon complexes obtained by chemically or electrochemically delithitoylating the pretreated waste lithium-ion battery material.

[0009] Further specifying, the general chemical formula of the nickel-based hydrotalcite is [Ni x M 1-x [(OH)2]·[(A a- ) n ·mH2O], where M is one or more of Al, Zn, Mg, Ce, Y, and Er, and A a- CO3 2- BO2 - OH - Cl - and F - One or more of the following, and 0.5≤x<1; the nickel hydroxide is spherical β-Ni(OH)2 or non-spherical β-Ni(OH)2; the manganese dioxide is α-MnO2, β-MnO2, γ-MnO2, δ-MnO2 or ε-MnO2.

[0010] A method for preparing an alkaline secondary battery cathode material based on waste lithium cobalt oxide material, the specific preparation steps of which are as follows:

[0011] Step S1: The lithium-deficient lithium cobalt oxide and carbon complex after pretreatment of waste lithium-ion batteries or the lithium-deficient lithium cobalt oxide and carbon complex after chemical or electrochemical delithiation of materials after pretreatment of waste lithium-ion batteries is used as a cobalt-based additive.

[0012] Step S2: Mix the cobalt-based additive with the positive electrode active material to obtain the alkaline secondary battery positive electrode material. The mixing ratio should be such that the mass percentage of the cobalt-based additive in the final mixture is 0.5% to 20%.

[0013] Further specifying, in step S1, the lithium content of the pretreated waste lithium-ion battery material is determined. If its stoichiometry satisfies the general chemical formula of lithium cobalt oxide and carbon complex Li 1-x If 0.2 ≤ x < 1 in CoO2, the pretreated material can be directly used as a cobalt-based additive for further preparation of alkaline secondary battery cathode materials; if its stoichiometry does not satisfy the general chemical formula of lithium cobalt oxide and carbon complex Li 1-x If 0.2 ≤ x < 1 in CoO2, the pretreated material can be processed by chemical or electrochemical delithiation processes and then used as a cobalt-based additive for further preparation of alkaline secondary battery cathode materials.

[0014] Further specifying, the specific process of chemical delithiation is as follows: the waste lithium-ion battery cathode material pretreated by ball milling is added to a potassium persulfate solution with a concentration of 0.5-2M, and stirred at 50-80°C for 2-24 hours. After separation, washing and drying, a complex of lithium cobalt oxide and carbon is obtained.

[0015] Further specifying, the specific process of electrochemical delithiation is as follows: using a titanium-based lead dioxide electrode as the anode, a nickel sheet or stainless steel electrode as the cathode, and an alkaline solution with a pH of 10-14 as the electrolyte, the waste lithium-ion battery cathode material pretreated by ball milling is placed in the anode chamber and electrolyzed at a constant voltage of 1.5-10V for 2-24 hours, and then separated, washed and dried to obtain a complex of lithium cobalt oxide and carbon.

[0016] An alkaline secondary battery positive electrode plate is prepared from the above-mentioned alkaline secondary battery positive electrode material based on waste lithium cobalt oxide material.

[0017] An alkaline secondary battery includes a battery casing, an electrode assembly sealed in the battery casing, and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The positive electrode plate is the alkaline secondary battery positive electrode plate described above.

[0018] Compared with the prior art, the technical solution of the present invention has the following significant advantages:

[0019] 1. This invention directly utilizes the extremely low-cost lithium cobalt oxide cathode material from waste lithium-ion batteries as a high-performance cobalt-based additive, replacing expensive traditional cobalt salts or metallic cobalt additives. This significantly reduces the production cost of alkaline batteries and opens up a new high-value outlet for the resource utilization of waste lithium batteries, realizing the direct and high-value reuse of lithium cobalt oxide cathode materials from waste lithium-ion batteries in alkaline battery systems.

[0020] 2. The lithium cobalt oxide cathode material from spent lithium-ion batteries possesses a regular layered crystal structure and good residual lithium-ion conductivity. The residual carbon on its surface (carbonization products from the conductive agents and binders of the primary battery) is tightly bonded to the lithium cobalt oxide, forming a natural Li₂O₃ layer.1-x The CoO2 / C composite, as a cobalt-based additive, can effectively improve the electronic conductivity network of the positive electrode matrix, suppress the expansion of Ni(OH)2 during charging and discharging, stabilize the structure, and thus improve the battery's discharge capacity, rate performance and cycle life.

[0021] 3. The method of the present invention avoids complex wet extraction or high-temperature reduction processes, and can achieve functional compounding through simple physical mixing. The process is short, energy consumption is low, and it is environmentally friendly.

[0022] 4. The additive provided by this invention is applicable to a variety of mainstream alkaline battery positive electrode active materials (nickel hydroxide, nickel-based hydrotalcite, manganese dioxide), and has wide applicability. Attached Figure Description

[0023] Figure 1 The waste lithium cobalt oxide material Li in Example 2 of this invention 0.70 Scanning electron microscope (SEM) image of CoO2 / C (x=0.30) shows a small amount of conductive carbon mixed around it. Detailed Implementation

[0024] The following examples further illustrate the above-described content of the present invention, but it should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention.

[0025] Example 1

[0026] Lithium cobalt oxide cathode material from spent lithium-ion batteries is directly applied as an additive to spherical β-Ni(OH)2 cathodes:

[0027] Completely discharged commercially used lithium cobalt oxide batteries from mobile phones were selected. The batteries were manually disassembled in a fume hood, and the positive electrode was removed. The positive electrode was placed in a tube furnace and calcined at 550°C for 4 hours under nitrogen protection, with a heating rate of 5°C / min, to completely remove the organic binder (PVDF) and carbonize it. After natural cooling, the electrode was ultrasonically treated in deionized water for 30 minutes to allow the active material layer to detach from the aluminum foil. After filtration and drying, a black powder was obtained, which is Li. 1-x CoO2 / C complex. Its composition, determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), is Li. 0.78 CoO2 / C, carbon content approximately 5 wt%. The Li prepared above... 0.78The CoO2 / C composite was mixed with commercially available high-density spherical β-Ni(OH)2 at a mass ratio of 10:90. The mixture was then ball-milled at 300 rpm for 2 hours. Afterward, the mixture was sieved through a 200-mesh sieve to obtain the final cathode material. The obtained cathode material, polytetrafluoroethylene (PTFE) suspension, and polyhydroxymethyl cellulose (HPMC) solution were mixed at a mass ratio of 80:10:5:5 and stirred until homogeneous. A certain amount of deionized water was then added to form a paste. This paste was then coated onto 2cm × 2cm nickel foam using a scraper, and after drying, rolling, and cutting, it was formed into a cathode plate. The prepared cathode plate, commercially available negative electrode plate, and alkaline battery separator were then assembled into a special simulated battery casing. A saturated ZnO solution of 6 MkOH was injected as the electrolyte to form a semi-sealed zinc-nickel secondary battery.

[0028] Example 2

[0029] Li after chemical delithiation treatment 0.70 CoO2 / C (x = 0.30) is used as an additive for non-spherical Ni(OH)2 cathodes:

[0030] Lithium cobalt oxide cathode material powder from waste lithium-ion batteries was obtained using the same method as in Example 1 and then subjected to chemical delithiation treatment: 5g of the powder was ball-milled and dispersed in 100mL of 1M ammonium persulfate alkaline solution (pH=10, adjusted with sodium hydroxide), and the mixture was stirred and reacted in a 50℃ water bath for 4 hours. After the reaction was completed, the mixture was filtered, repeatedly washed with deionized water until the filtrate was neutral, and then dried. The treated material was determined to have a composition of Li. 0.70 CoO2 / C. The Li prepared above... 0.70 The CoO2 / C composite was mixed with α-MnO2 and high-density non-spherical β-Ni(OH)2 at a mass ratio of 10:10:80. The mixture was placed in a planetary ball mill and ball-milled at 300 rpm for 2 hours. The mixture was then sieved through a 200-mesh sieve to obtain the final positive electrode material. Following the process in Example 1, this material was fabricated into a positive electrode plate. Subsequently, the prepared positive electrode plate, a commercially available negative electrode plate, and an alkaline battery separator were packed into a special simulated battery casing, and a 6M KOH saturated ZnO solution was injected as the electrolyte to assemble a semi-sealed zinc-nickel alkaline secondary battery.

[0031] Example 3

[0032] Chemically delithiated Li 0.44 CoO2 / C (x = 0.56) is used as an additive in the Ni(OH)2 cathode:

[0033] Lithium cobalt oxide cathode material powder from waste lithium-ion batteries was obtained using the same method as in Example 1 and then subjected to chemical delithiation treatment: 5g of the powder was ball-milled and dispersed in 100mL of 1.5M potassium persulfate alkaline solution (pH=10, adjusted with potassium hydroxide), and the mixture was stirred and reacted in a 50℃ water bath for 7 hours. After the reaction was completed, the mixture was filtered, repeatedly washed with deionized water until the filtrate was neutral, and then dried. The treated material was determined to have a composition of Li. 0.44 CoO2 / C. The Li prepared above... 0.44 CoO2 / C and Ni 0.7 Ce 0.3 LDH nanosheets and high-density spherical β-Ni(OH)₂ were mixed at a mass ratio of 10:50:50. The mixture was placed in a planetary ball mill and ball-milled at 300 rpm for 2 hours. Afterwards, it was sieved through a 200-mesh sieve to obtain the final cathode material. Following the process of Example 1, a zinc-nickel alkaline secondary battery was fabricated using this material as the cathode material according to the same process.

[0034] Example 4

[0035] Chemically delithiated Li 0.23 CoO2 / C (x = 0.77) is used as an additive in spherical Ni(OH)2 cathodes:

[0036] Lithium cobalt oxide cathode material powder from waste lithium-ion batteries was obtained using the same method as in Example 1 and then subjected to chemical delithiation treatment: 5g of the powder was ball-milled and dispersed in 100mL of 1.0M sodium persulfate solution (pH=9, adjusted with sodium hydroxide), and the mixture was stirred and reacted in a 50℃ water bath for 14 hours. After the reaction was completed, the mixture was filtered, repeatedly washed with deionized water until the filtrate was neutral, and then dried. The treated material was determined to have a composition of Li. 0.23 CoO2 / C. The Li prepared above... 0.23 The CoO2 / C composite was mixed with commercially available high-density spherical β-Ni(OH)2 at a mass ratio of 10:90. The mixture was then placed in a planetary ball mill and milled at 300 rpm for 2 hours. Afterwards, it was sieved through a 200-mesh sieve to obtain the final positive electrode material. This material was then used to prepare a positive electrode plate according to Example 1. The prepared positive electrode plate, a commercial AB5 type hydrogen storage alloy as the negative electrode, and a polypropylene nonwoven fabric as the separator were then assembled into a special simulated battery casing. An electrolyte solution with a mass concentration of 30% KOH and a mass concentration of 2% LiOH was injected to form a semi-sealed nickel-hydrogen alkaline secondary battery.

[0037] Example 5

[0038] Li after chemical delithiation treatment 0.44 CoO2 / C (x = 0.56) is used as an additive in Ni-Al LDH cathodes:

[0039] The Li after delithiation treatment in Example 3 0.44 CoO2 / C materials and Ni 0.8 Al 0.2 LDH was mixed at a mass ratio of 10:90, ball-milled, and sieved to obtain the positive electrode material. Following the process in Example 1, this positive electrode material was fabricated into a positive electrode plate. Subsequently, the prepared positive electrode plate, a commercial AB5 type hydrogen storage alloy as the negative electrode, and a polypropylene nonwoven fabric as the separator were packed into a special simulated battery casing. Electrolytes with a mass concentration of 30% KOH and 2% LiOH were injected to assemble a semi-sealed nickel-hydrogen alkaline secondary battery.

[0040] Example 6

[0041] Li after chemical delithiation treatment 0.23 CoO2 / C (x = 0.77) is used as an additive in the manganese dioxide (γ-MnO2) cathode:

[0042] The Li prepared in Example 4 0.23 CoO2 / C was mixed with electrolytic manganese dioxide (γ-MnO2) and β-Ni(OH)2 at a mass ratio of 10:60:30, and the mixture was ball-milled and sieved to prepare a positive electrode material. Following the process in Example 1, a positive electrode plate was fabricated using this material. The prepared positive electrode plate, zinc negative electrode, and alkaline battery separator were then packed into a special simulated battery casing. A 30% KOH electrolyte and a 2% ZnO electrolyte were injected to assemble a semi-sealed zinc-manganese alkaline secondary battery.

[0043] Example 7

[0044] Electrochemical delithiation treatment of Li 0.62 Preparation and application of CoO2 / C (x=0.38) additives:

[0045] The same method as in Example 1 was used to obtain pretreated lithium cobalt oxide cathode material powder from waste lithium-ion batteries for electrochemical delithiation. A titanium-based lead dioxide electrode was selected as the anode, a nickel sheet as the cathode, and a 2MKCl solution with a pH of 12 as the electrolyte. The pretreated waste lithium cobalt oxide material was placed in the anode chamber and electrolyzed at a constant voltage of 5V for 6 hours. After separation, washing, and drying, Li₂ was obtained. 0.62 CoO2 / C material. The prepared Li 0.62 CoO2 / C additives and β-Ni(OH)2 were mixed at a mass ratio of 10:90, and the positive electrode material was prepared by ball milling and sieving. Following the electrode preparation process of Example 1, a positive electrode plate was fabricated using this material. Subsequently, the prepared positive electrode plate, zinc negative electrode, and alkaline battery separator were packed into a special simulated battery casing, and a 30% (w / w) saturated ZnO-KOH electrolyte was injected to assemble a semi-sealed zinc-nickel alkaline secondary battery.

[0046] Example 8

[0047] Electrochemical delithiation treatment of Li 0.37 Preparation and application of CoO2 / C (x=0.63) additives:

[0048] The same method as in Example 1 was used to obtain pretreated lithium cobalt oxide cathode material powder from waste lithium-ion batteries for electrochemical delithiation. A titanium-based lead dioxide electrode was selected as the anode, stainless steel as the cathode, and a 1M KCl alkaline solution with a pH of 10 as the electrolyte. The pretreated waste lithium cobalt oxide material was placed in the anode chamber and electrolyzed at a constant voltage of 7V for 16 hours. After separation, washing, and drying, Li₂ was obtained. 0.37 CoO2 / C material. The prepared Li 0.37 CoO2 / C additives, γ-MnO2, and β-Ni(OH)2 were mixed in a mass ratio of 10:20:70 and then ball-milled and sieved to prepare a positive electrode material. Following the electrode fabrication process of Example 1, a positive electrode plate was fabricated using this material. Subsequently, the prepared positive electrode plate, zinc negative electrode, and alkaline battery separator were packed into a simulated battery casing, and a 30% (w / w) saturated ZnO-KOH electrolyte was injected to assemble a semi-sealed zinc-nickel alkaline secondary battery.

[0049] Comparative Example 1

[0050] A semi-sealed zinc-nickel secondary battery was fabricated using spherical Ni(OH)2 and 10 wt% conductive graphite as the positive electrode material, following the same process as in Example 1.

[0051] Comparative Example 2

[0052] Spherical Ni(OH)2 was mechanically mixed with 10 wt% CoO (analytical grade) as the positive electrode material, and it was fabricated into a semi-sealed zinc-nickel secondary battery using the same process as in Example 1.

[0053] For the aforementioned zinc-nickel simulated batteries, they were charged at 0.2C (nominal capacity) with constant current and constant voltage for 6 hours at 25°C, allowed to stand for 10 minutes, and then discharged at 0.2C with constant current to 1.2V. After activation, rate performance and cycle performance were tested. For the aforementioned nickel-hydrogen batteries and zinc-manganese batteries, they were charged at 0.2C (nominal capacity) with constant current for 6 hours at 25°C, allowed to stand for 10 minutes, and then discharged at 0.2C with constant current to 1.0V. After activation, rate performance and cycle performance were tested.

[0054] Performance test results and analysis:

[0055] Table 1 Charge and discharge performance of each battery

[0056]

[0057] The results in the table above show that the waste lithium cobalt oxide additive of the present invention is superior to traditional CoO additives in improving cycle life, which is attributed to Li 1-x The CoO2 / C composite material exhibits both good conductivity and structural stability. The test results above show that batteries assembled using the alkaline secondary battery cathode material prepared according to this invention possess high specific capacity, excellent rate performance, and cycle stability, meeting the requirements of commercial batteries, especially high-capacity, high-power batteries. These performance improvements are mainly attributed to the enhancement of the cathode material's conductivity by the addition of delithiated lithium cobalt oxide material, significantly optimizing the charge transport path within the electrode. This structure effectively reduces interfacial contact resistance and overall electrochemical impedance, effectively increases the oxygen evolution overpotential on the electrode surface, suppresses side reactions under high voltage, ensures a significant increase in the battery's reversible capacity, and enhances the structural and electrochemical stability of the cathode material during long-term cycling. Simultaneously, it promotes the high-value and resource utilization of waste lithium cobalt oxide materials, replacing traditional expensive cobalt additives, reducing the cost of alkaline batteries, and promoting the sustainable development of the lithium battery recycling industry.

[0058] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. An alkaline secondary battery cathode material based on waste lithium cobalt oxide material, characterized in that: The alkaline secondary battery cathode material comprises a cathode active material and a cobalt-based additive. The cathode active material is one or more of nickel hydroxide, nickel-based hydrotalcite, and manganese dioxide. The cobalt-based additive is a complex of lithium cobalt oxide (lithium-deficient) and carbon, with the general chemical formula Li. 1-x CoO2 / C, where 0.2≤x<1, and the carbon in the complex of lithium cobalt oxide and carbon with lithium deficiency is a conductive carbon material. This cobalt-based additive is derived from the lithium cobalt oxide cathode material of waste lithium-ion batteries.

2. The alkaline secondary battery cathode material based on waste lithium cobalt oxide material according to claim 1, characterized in that: The mass percentage of cobalt-based additives in the alkaline secondary battery cathode material is 0.5% to 20%; the mass percentage of carbon in the lithium-deficient lithium cobalt oxide and carbon complex is 1% to 10%; the cobalt-based additives are either lithium-deficient lithium cobalt oxide and carbon complexes obtained by pre-treating waste lithium-ion batteries, or lithium-deficient lithium cobalt oxide and carbon complexes obtained by chemically or electrochemically delithiating the pre-treated waste lithium-ion battery material.

3. The alkaline secondary battery cathode material based on waste lithium cobalt oxide material according to claim 1, characterized in that: The general chemical formula of the nickel-based hydrotalcite is [Ni x M 1-x [(OH)2]·[(A a- ) n ·mH2O], where M is one or more of Al, Zn, Mg, Ce, Y, and Er, and A a- CO3 2- BO2 - OH - Cl - and F - One or more of the following, and 0.5≤x<1; the nickel hydroxide is spherical β-Ni(OH)2 or non-spherical β-Ni(OH)2; the manganese dioxide is α-MnO2, β-MnO2, γ-MnO2, δ-MnO2 or ε-MnO2.

4. A method for preparing an alkaline secondary battery cathode material based on waste lithium cobalt oxide material as described in any one of claims 1 to 3, characterized in that... The specific preparation steps are as follows: Step S1: The lithium-deficient lithium cobalt oxide and carbon complex after pretreatment of waste lithium-ion batteries or the lithium-deficient lithium cobalt oxide and carbon complex after chemical or electrochemical delithiation of materials after pretreatment of waste lithium-ion batteries is used as a cobalt-based additive. Step S2: Mix the cobalt-based additive with the positive electrode active material to obtain the alkaline secondary battery positive electrode material. The mixing ratio should be such that the mass percentage of the cobalt-based additive in the final mixture is 0.5% to 20%.

5. The method for preparing alkaline secondary battery cathode material based on waste lithium cobalt oxide material according to claim 4, characterized in that: In step S1, the lithium content of the pretreated waste lithium-ion battery material is determined. If its stoichiometry satisfies the general chemical formula of lithium cobalt oxide and carbon complex Li 1-x If 0.2 ≤ x < 1 in CoO2, the pretreated material can be directly used as a cobalt-based additive for further preparation of alkaline secondary battery cathode materials; if its stoichiometry does not satisfy the general chemical formula of lithium cobalt oxide and carbon complex Li 1-x If 0.2 ≤ x < 1 in CoO2, the pretreated material can be processed by chemical or electrochemical delithiation processes and then used as a cobalt-based additive for further preparation of alkaline secondary battery cathode materials.

6. The method for preparing alkaline secondary battery cathode material based on waste lithium cobalt oxide material according to claim 4, characterized in that... The specific process of chemical delithiation is as follows: waste lithium-ion battery cathode material pretreated by ball milling is added to a potassium persulfate solution with a concentration of 0.5-2M, and stirred at 50-80°C for 2-24 hours. After separation, washing and drying, a complex of lithium cobalt oxide and carbon is obtained.

7. The method for preparing alkaline secondary battery cathode material based on waste lithium cobalt oxide material according to claim 4, characterized in that... The specific process for electrochemical delithiation is as follows: using a titanium-based lead dioxide electrode as the anode, a nickel sheet or stainless steel electrode as the cathode, and an alkaline solution with a pH of 10-14 as the electrolyte, the waste lithium-ion battery cathode material that has undergone ball milling pretreatment is placed in the anode chamber and electrolyzed at a constant voltage of 1.5-10V for 2-24 hours. After separation, washing, and drying, a complex of lithium cobalt oxide and carbon is obtained.

8. A positive electrode plate for an alkaline secondary battery, characterized in that: The alkaline secondary battery positive electrode plate is prepared from the alkaline secondary battery positive electrode material based on waste lithium cobalt oxide material as described in any one of claims 1 to 3.

9. An alkaline secondary battery, comprising a battery casing, an electrode assembly sealed within the battery casing, and an electrolyte, wherein the electrode assembly comprises a positive electrode, a negative electrode, and a separator, characterized in that: The positive electrode plate is the alkaline secondary battery positive electrode plate as described in claim 8.

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