Method for preparing vanadium-based positive electrode material through coordination of rare earth ion intercalation and oxygen vacancy regulation

Abstract

The invention discloses a method for preparing a vanadium-based positive electrode material by coordination of rare earth ion intercalation and oxygen vacancy regulation, which comprises the following steps: taking rare earth ions with larger radius, 4f orbits and variable valence as intercalation ions, and generating oxygen vacancies with proper concentration by soluble saccharides with moderate reducibility; the electrochemical performance of the vanadium oxide positive electrode material is synergistically improved; the preparation method comprises the following steps: introducing oxygen vacancies while introducing intercalation ions into vanadium pentoxide through a hydrothermal reaction at a relatively low temperature, and finally carrying out vacuum drying to obtain the vanadium-based positive electrode material with a stable structure and excellent electrochemical performance. The vanadium-based positive electrode material prepared by the invention has the characteristics of stable structure, high specific capacity, good rate capability and excellent cycling stability, and has potential application value in the fields of energy storage batteries and power batteries.

Description

Technical Field

[0001] The present invention belongs to the field of battery technology, and more specifically, the present invention relates to a method for preparing vanadium-based positive electrode materials by synergistically regulating rare earth ion intercalation and oxygen vacancy. Background Art

[0002] Among the many energy storage systems, electrochemical energy storage has the advantages of high energy density, fast response and no geographical restrictions. Compared with lithium battery energy storage, aqueous zinc ion batteries have the advantages of abundant zinc resources, low cost and high safety, and have become a research hotspot in the field of energy storage. However, it is difficult to achieve high capacity and long-term circulation during the deintercalation of zinc ions in traditional positive electrode materials. Vanadium oxides with multivalent states, layered structures and high theoretical specific capacity provide a possibility to solve this problem, but vanadium oxide positive electrode materials still have problems such as low conductivity, poor reversibility, slow diffusion kinetics and low specific capacity in practical applications. Many scientific and technological workers have conducted extensive research on improving the electrochemical performance of vanadium oxide positive electrode materials. Patent CN116282155B discloses a magnesium vanadium positive electrode material Mg with a larger interlayer spacing obtained by embedding magnesium ions and structural water between V2O5 layers. x V2O5∙H2O, but at a current density of 0.05 A∙g -1 When the specific capacity is only 250 mAh g -1 , it is difficult to meet the requirements of high current density and large specific capacity of energy storage batteries.

[0003] To improve the specific capacity, cycling stability, and rate performance of vanadium-based cathode materials, existing technologies have only enhanced the electrochemical performance of vanadium oxides by increasing interlayer spacing or manipulating oxygen vacancies through intercalation of ions. These technologies fail to combine ion intercalation and oxygen vacancy manipulation. Furthermore, the selection of intercalation ions often ignores the inherent properties of the ions, resulting in the intercalation ions failing to adequately meet the interlayer requirements of the vanadium oxide. Furthermore, the reducing agent's reducibility can be excessive or insufficient, leading to excessive or low oxygen vacancy concentrations. These factors all affect the electrochemical properties of vanadium oxides, including cycling stability, conductivity, specific capacity, and rate performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing vanadium-based positive electrode materials by synergistically regulating rare earth ion intercalation and oxygen vacancy. The vanadium-based positive electrode materials prepared by this method have the characteristics of stable structure, high specific capacity, good rate performance and excellent cycle stability, and have potential application value as positive electrode materials in the fields of energy storage batteries and power batteries.

[0005] To achieve the above-mentioned objectives and other advantages of the present invention, a method for preparing vanadium-based cathode materials by synergistically intercalating rare earth ions and regulating oxygen vacancies is provided, comprising: using rare earth ions with a large radius, 4f orbitals, and variable valence as intercalating ions; using soluble sugars with moderate reducing properties to generate oxygen vacancies at an appropriate concentration, thereby synergistically improving the electrochemical performance of the vanadium oxide cathode material; introducing oxygen vacancies simultaneously with the intercalating ions through a low-temperature hydrothermal reaction in vanadium pentoxide; and finally, vacuum drying to obtain a vanadium-based cathode material with a stable structure and excellent electrochemical performance. The specific steps are as follows: S1. Put vanadium pentoxide into deionized water and stir at a constant temperature to obtain a vanadium pentoxide aqueous solution; S2. adding rare earth chloride to the vanadium pentoxide aqueous solution, stirring at a constant temperature, and then ultrasonically treating to obtain a mixed solution; S3, adding soluble sugars to the mixed solution, stirring, and then transferring to a polytetrafluoroethylene-lined reactor, placing the reactor in an oven, and keeping it warm for a certain period of time; S4. After the temperature of the reactor drops to room temperature, the solution is taken out and centrifuged. The centrifuged product is washed alternately with deionized water and ethanol, and then vacuum-dried to obtain a vanadium-based positive electrode material prepared by synergistically controlling rare earth ion intercalation and oxygen vacancy regulation.

[0006] Preferably, in S1, the constant temperature stirring temperature is 30-50° C., the time is 0.5-2 h, and the stirring speed is 200-700 r / min; and the concentration of the obtained vanadium pentoxide aqueous solution is 0.003-0.07 mol / L.

[0007] Preferably, in S2, the rare earth chloride is a trivalent rare earth chloride with variable valence, including one or more of cerium trichloride, praseodymium trichloride, samarium trichloride, europium trichloride, terbium trichloride, thulium trichloride and ytterbium trichloride.

[0008] Preferably, in S2, the molar ratio of the rare earth element of the rare earth chloride to the vanadium element of the vanadium pentoxide in S1 is 1~14:1; the constant temperature stirring temperature is 30~50°C, the time is 0.5~2 h, and the stirring speed is 200~700 r / min; the power of the ultrasonic treatment is 360~540 W, the frequency is 20~50 kHz, and the time is 0.5~2 h.

[0009] Preferably, in S3, the soluble sugar is one or more of xylose, fructose, lactose, maltose, arabinose, glucose and galactose.

[0010] Preferably, in S3, the molar ratio of the soluble sugar to the vanadium element in the vanadium pentoxide in S1 is 0.25-5:1.

[0011] Preferably, in S3, the stirring speed is 100-300 r / min, the stirring time is 20-40 min; the oven temperature is 100-140° C., and the holding time is 12-36 h.

[0012] Preferably, in S4, the centrifugal speed is 4000-8000 r / min, the time is 2-4 h; the washing is alternately performed 2-5 times; and the vacuum drying temperature is 60-80° C., and the time is 12-24 h.

[0013] A vanadium-based cathode material is prepared by the above-mentioned method of collaboratively preparing the vanadium-based cathode material by rare earth ion intercalation and oxygen vacancy regulation.

[0014] A battery, wherein the positive electrode material of the battery is the vanadium-based positive electrode material as described above.

[0015] The present invention has at least the following beneficial effects: (1) Ion intercalation and oxygen vacancy control technologies are used simultaneously to prepare vanadium pentoxide cathode materials. While increasing the interlayer spacing, an appropriate amount of oxygen vacancies are introduced to synergistically increase the electrochemical performance of the vanadium pentoxide cathode materials.

[0016] (2) Using the larger radius of rare earth ions to significantly increase the distance between vanadium pentoxide layers, providing a wider current channel; using rare earth elements (Ce 4+ / Ce 3+ 、Pr 4+ / Pr 3+ 、Sm 3+ / Sm 2+ 、Eu 3+ / Eu 2+ 、Tb 4+ / Tb 3+ 、Tm 3+ / Tm 2+ 、Yb 3+ / Yb 2 + ) possesses a variable valence state, participates in charge compensation reactions, and contributes to additional capacity; it utilizes the coupling of the 4f orbital of rare earth ions with the conduction band of vanadium pentoxide to form a localized electron cloud, reduce the band gap, significantly improve electron mobility, reduce polarization, and thus improve charge and discharge efficiency.

[0017] (3) In the process of oxygen vacancy regulation, soluble sugars with moderate reducing properties are selected to ensure the generation of oxygen vacancies at an appropriate concentration, so as to avoid insufficient active sites caused by too few oxygen vacancies or instability of the vanadium pentoxide structure caused by excessive oxygen vacancies. In addition, the selected sugars contain only three elements: carbon, hydrogen and oxygen. The products generated after reaction with vanadium pentoxide are gas or soluble organic matter, which can be easily removed by washing, etc., or the generated conductive carbon black can be directly used as a conductive agent for assembling the positive electrode of the battery.

[0018] (4) The present invention adopts rare earth ion intercalation and oxygen vacancy regulation to prepare vanadium-based cathode materials, which can effectively reduce the vanadium content of cathode materials at 0.2 A∙g -1 At the current density, the specific capacity reaches 371 mAh∙g -1 ; The current density increases to 1 A∙g -1 , with a specific capacity of 282 mAh∙g -1 ; The current density increased to 10 A∙g -1 , with a specific capacity of 151 mAh∙g -1 ; Current density returns to 0.2 A∙g -1 The specific capacity is 367 mAh∙g -1 The capacity recovery rate is 98.9%, which has good rate performance. In addition, the positive electrode material has a long cycle life at 1.0 A∙g -1 After 2000 cycles, the capacity retention rate is 89.1% and the coulombic efficiency is stable at 100%, showing excellent electrochemical performance.

[0019] Other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 SEM images of the vanadium-based positive electrode materials of Comparative Example 1 (a) and Example 1 (b); Figure 2 EDS images of the vanadium-based positive electrode materials of Comparative Example 1 (a) and Example 1 (b); Figure 3 XRD patterns of the vanadium-based positive electrode materials of Comparative Example 1 and Example 1; Figure 4 The vanadium-based cathode materials of Comparative Example 1 (a) and Example 1 (b) were tested at a scan rate of 1.0 mV∙s -1 Cyclic voltammogram below; Figure 5 The vanadium-based cathode materials of Comparative Example 1 (a) and Example 1 (b) were tested at 0.2 A∙g -1 -10.0 A∙g -1 Constant current charge and discharge (GCD) curve under current density; Figure 6 The vanadium-based cathode materials of Comparative Example 1 (a) and Example 1 (b) were tested at 0.2 A∙g -1 -10.0 A∙g -1 Rate performance diagram under current density; Figure 7 The vanadium-based positive electrode materials of Comparative Example 1 and Example 1 were prepared at a current density of 1.0 A∙g-1 2000 charge and discharge cycle performance diagram. DETAILED DESCRIPTION

[0021] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0022] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0023] Example 1 A method for preparing a vanadium-based cathode material by synergistically controlling rare earth ion intercalation and oxygen vacancy regulation comprises the following steps: S1. Add 0.007 mol of vanadium pentoxide to 100 mL of deionized water and stir at 500 rpm in a constant temperature water bath at 45°C for 1 hour to obtain a vanadium pentoxide aqueous solution. S2. Add 0.042 mol of cerium trichloride to the vanadium pentoxide aqueous solution, stir at 500 rpm in a constant temperature water bath at 45°C for 1 hour, and then ultrasonicate the solution in an ultrasonic cleaner at a power of 540 W and a frequency of 40 kHz for 1 hour; S3. Add 0.042 mol fructose to the sonicated solution and stir at 150 r / min for 20 min. Transfer the solution to a polytetrafluoroethylene-lined reactor and place the reactor in an oven at 110°C for 24 h. S4. After the temperature of the reactor drops to room temperature, take out the solution and centrifuge it at 7000 r / min for 3 hours. Wash the centrifugal separation material alternately with deionized water and ethanol for 3 times, and then dry it in a vacuum drying oven at 80°C for 12 hours to obtain a vanadium-based positive electrode material prepared by synergistic preparation of rare earth ion intercalation and oxygen vacancy regulation.

[0024] The vanadium-based positive electrode material prepared in Example 1, the conductive agent acetylene black, and the binder polyvinylidene fluoride were ground in a mortar at a mass ratio of 8:1:1. After the mixture was ground evenly, N-methylpyrrolidone was added and grinding continued to form a uniform slurry. The slurry was then evenly coated on a carbon cloth and dried in a vacuum drying oven at 70°C for 12 hours to produce a positive electrode sheet. The loading of the vanadium-based positive electrode material was 4.83 mg / cm 2 The button cell was assembled in the order of the negative electrode shell, zinc foil, glass fiber separator, positive electrode sheet, gasket, shrapnel and positive electrode shell, with 3 mol / L zinc trifluoromethanesulfonate electrolyte between the zinc foil and the positive electrode sheet.

[0025] Example 2 A method for preparing a vanadium-based cathode material by synergistically controlling rare earth ion intercalation and oxygen vacancy regulation comprises the following steps: S1. Add 0.005 mol of vanadium pentoxide to 100 mL of deionized water and stir at 700 rpm in a constant temperature water bath at 40°C for 1 hour to obtain a vanadium pentoxide aqueous solution. S2. Add 0.035 mol of praseodymium trichloride to the above vanadium pentoxide aqueous solution, stir at 700 r / min in a constant temperature water bath at 40°C for 1 hour, and then ultrasonicate the solution in an ultrasonic cleaner at a power of 360 W and a frequency of 40 kHz for 1 hour; S3. Add 0.01 mol glucose to the sonicated solution and stir at 100 r / min for 30 min. Transfer the solution to a polytetrafluoroethylene-lined reactor and place the reactor in an oven at 130°C for 24 h. S4. After the temperature of the reactor drops to room temperature, take out the solution and centrifuge it at 8000 r / min for 2 hours. Wash the centrifuged product with deionized water and ethanol alternately for 4 times, and then dry it in a vacuum drying oven at 70°C for 12 hours to obtain a vanadium-based positive electrode material prepared by synergistic preparation of rare earth ion intercalation and oxygen vacancy regulation.

[0026] The vanadium-based positive electrode material prepared in Example 2, conductive carbon black, and polyvinylidene fluoride as a binder were ground in a mortar at a mass ratio of 8:1:1. After the mixture was evenly ground, N-methylpyrrolidone was added and grinding continued to form a uniform slurry. The slurry was then evenly coated on a carbon cloth and dried in a vacuum drying oven at 70°C for 12 hours to produce a positive electrode sheet. The loading of the vanadium-based positive electrode material was 4.52 mg / cm 2 The button cell was assembled in the order of the negative electrode shell, zinc foil, glass fiber separator, positive electrode sheet, gasket, shrapnel and positive electrode shell, with 3 mol / L zinc trifluoromethanesulfonate electrolyte between the zinc foil and the positive electrode sheet.

[0027] Example 3 A method for preparing a vanadium-based cathode material by synergistically controlling rare earth ion intercalation and oxygen vacancy regulation comprises the following steps: S1. Add 0.007 mol of vanadium pentoxide to 100 mL of deionized water and stir at 600 rpm in a constant temperature water bath at 50°C for 1 hour to obtain a vanadium pentoxide aqueous solution. S2. Add 0.07 mol of samarium trichloride to the above vanadium pentoxide aqueous solution, stir at 600 r / min in a constant temperature water bath at 50°C for 1 hour, and then ultrasonicate the solution in an ultrasonic cleaner at a power of 540 W and a frequency of 40 kHz for 1 hour; S3. Add 0.04 mol maltose to the sonicated solution and stir at 100 r / min for 20 min. Transfer the solution to a polytetrafluoroethylene-lined reactor and place the reactor in an oven at 130°C for 24 h. S4. After the temperature of the reactor drops to room temperature, take out the solution and centrifuge it at 8000 r / min for 3 hours. Wash the centrifuged product alternately with deionized water and ethanol for 3 times, and then dry it in a vacuum drying oven at 70°C for 18 hours to obtain a vanadium-based positive electrode material prepared by synergistic preparation of rare earth ion intercalation and oxygen vacancy regulation.

[0028] The vanadium-based positive electrode material prepared in Example 3, conductive carbon black, and polytetrafluoroethylene glue as a binder were ground in a mortar at a mass ratio of 8:1:1. After the mixture was evenly ground, N-methylpyrrolidone was added and grinding continued to form a uniform slurry. The slurry was then evenly coated on a carbon cloth and dried in a vacuum drying oven at 70°C for 12 hours to produce a positive electrode sheet. The loading of the vanadium-based positive electrode material was 4.95 mg / cm 2 The button cell was assembled in the order of the negative electrode shell, zinc foil, glass fiber separator, positive electrode sheet, gasket, shrapnel and positive electrode shell, with 3 mol / L zinc sulfate electrolyte between the zinc foil and the positive electrode sheet.

[0029] Example 4 A method for preparing a vanadium-based cathode material by synergistically controlling rare earth ion intercalation and oxygen vacancy regulation comprises the following steps: S1. Add 0.006 mol of vanadium pentoxide to 100 mL of deionized water and stir at 400 rpm in a constant temperature water bath at 40°C for 1 hour to obtain a vanadium pentoxide aqueous solution. S2. Add 0.07 mol of europium trichloride to the above vanadium pentoxide aqueous solution, stir at 400 r / min in a constant temperature water bath at 40°C for 1 hour, and then ultrasonicate the solution in an ultrasonic cleaner at a power of 540 W and a frequency of 40 kHz for 1 hour; S3. Add 0.03 mol xylose to the sonicated solution and stir at 150 r / min for 20 min. Transfer the solution to a polytetrafluoroethylene-lined reactor and place the reactor in an oven at 140°C for 24 h. S4. After the temperature of the reactor drops to room temperature, take out the solution and centrifuge it at 7000 r / min for 4 hours. Wash the centrifuged product with deionized water and ethanol alternately for 4 times, and then dry it in a vacuum drying oven at 70°C for 18 hours to obtain a vanadium-based positive electrode material prepared by synergistic preparation of rare earth ion intercalation and oxygen vacancy regulation.

[0030] The vanadium-based positive electrode material prepared in Example 4, conductive carbon black, and polytetrafluoroethylene glue as a binder were ground in a mortar at a mass ratio of 8:1:1. After the mixture was evenly ground, N-methylpyrrolidone was added and grinding continued to form a uniform slurry. The slurry was then evenly coated on a carbon cloth and dried in a vacuum drying oven at 70°C for 12 hours to produce a positive electrode sheet. The loading of the vanadium-based positive electrode material was 4.61 mg / cm 2 The button cell was assembled in the order of the negative electrode shell, zinc foil, glass fiber separator, positive electrode sheet, gasket, shrapnel and positive electrode shell, with 3 mol / L zinc sulfate electrolyte between the zinc foil and the positive electrode sheet.

[0031] Example 5 A method for preparing a vanadium-based cathode material by synergistically controlling rare earth ion intercalation and oxygen vacancy regulation comprises the following steps: S1. Add 0.005 mol of vanadium pentoxide to 100 mL of deionized water and stir at 700 rpm in a constant temperature water bath at 30°C for 1 hour to obtain a vanadium pentoxide aqueous solution. S2. Add 0.05 mol of terbium trichloride to the above vanadium pentoxide aqueous solution, stir at 700 r / min in a constant temperature water bath at 30°C for 1 hour, and then ultrasonicate the solution in an ultrasonic cleaner at a power of 540 W and a frequency of 40 kHz for 1 hour; S3. Add 0.03 mol lactose to the sonicated solution and stir at 200 r / min for 20 min. Transfer the solution to a polytetrafluoroethylene-lined reactor and place the reactor in an oven at 120°C for 24 h. S4. After the temperature of the reactor drops to room temperature, take out the solution and centrifuge it at 7000 r / min for 3 hours. Wash the centrifuged product alternately with deionized water and ethanol for 3 times, and then dry it in a vacuum drying oven at 70°C for 24 hours to obtain a vanadium-based positive electrode material prepared by synergistic preparation of rare earth ion intercalation and oxygen vacancy regulation.

[0032] The vanadium-based positive electrode material prepared in Example 5, conductive graphite (a conductive agent), and polyvinylidene fluoride (a binder) were ground in a mortar at a mass ratio of 8:1:1. After the mixture was evenly ground, N-methylpyrrolidone was added and grinding continued to form a uniform slurry. The slurry was then evenly coated on a carbon cloth and dried in a vacuum drying oven at 70°C for 12 hours to produce a positive electrode sheet. The loading of the vanadium-based positive electrode material was 4.76 mg / cm 2 The button cell was assembled in the order of the negative electrode shell, zinc foil, glass fiber separator, positive electrode sheet, gasket, shrapnel and positive electrode shell, with 3 mol / L zinc sulfate electrolyte between the zinc foil and the positive electrode sheet.

[0033] Example 6 A method for preparing a vanadium-based cathode material by synergistically controlling rare earth ion intercalation and oxygen vacancy regulation comprises the following steps: S1. Add 0.007 mol of vanadium pentoxide to 100 mL of deionized water and stir at 500 rpm in a constant temperature water bath at 50°C for 1 hour to obtain a vanadium pentoxide aqueous solution. S2. Add 0.08 mol of thulium trichloride to the above vanadium pentoxide aqueous solution, stir at 500 r / min in a constant temperature water bath at 50°C for 1 hour, and then ultrasonicate the solution in an ultrasonic cleaner at a power of 360 W and a frequency of 40 kHz for 1 hour; S3. Add 0.05 mol of arabinose to the sonicated solution and stir at 150 r / min for 20 min. Transfer the solution to a polytetrafluoroethylene-lined reactor and place the reactor in an oven at 110°C for 24 h. S4. After the temperature of the reactor drops to room temperature, take out the solution and centrifuge it at 7000 r / min for 3 hours. Wash the centrifuged product alternately with deionized water and ethanol for 3 times, and then dry it in a vacuum drying oven at 70°C for 24 hours to obtain a vanadium-based positive electrode material prepared by synergistic preparation of rare earth ion intercalation and oxygen vacancy regulation.

[0034] The vanadium-based positive electrode material prepared in Example 6, the conductive agent Super C65, and the binder polyvinylidene fluoride were ground in a mortar at a mass ratio of 8:1:1. After the mixture was evenly ground, N-methylpyrrolidone was added and grinding continued to form a uniform slurry. The slurry was then evenly coated on a carbon cloth and dried in a vacuum drying oven at 70°C for 12 hours to obtain a positive electrode sheet. The loading of the vanadium-based positive electrode material was 4.21 mg / cm 2 The button cell was assembled in the order of the negative electrode shell, zinc foil, glass fiber separator, positive electrode sheet, gasket, shrapnel and positive electrode shell, with 3 mol / L zinc trifluoromethanesulfonate electrolyte between the zinc foil and the positive electrode sheet.

[0035] Example 7 A method for preparing a vanadium-based cathode material by synergistically controlling rare earth ion intercalation and oxygen vacancy regulation comprises the following steps: S1. Add 0.005 mol of vanadium pentoxide to 100 mL of deionized water and stir at 600 rpm in a constant temperature water bath at 40°C for 1 hour to obtain a vanadium pentoxide aqueous solution. S2. Add 0.08 mol of ytterbium trichloride to the above vanadium pentoxide aqueous solution, stir at 600 r / min in a constant temperature water bath at 40°C for 1 hour, and then ultrasonicate the solution in an ultrasonic cleaner at a power of 540 W and a frequency of 40 kHz for 1 hour; S3. Add 0.05 mol galactose to the sonicated solution and stir at 300 r / min for 20 min. Transfer the solution to a polytetrafluoroethylene-lined reactor and place the reactor in an oven at 130°C for 24 h. S4. After the temperature of the reactor drops to room temperature, take out the solution and centrifuge it at 8000 r / min for 3 hours. Wash the centrifuged product alternately with deionized water and ethanol for 3 times, and then dry it in a vacuum drying oven at 70°C for 24 hours to obtain a vanadium-based positive electrode material prepared by synergistic preparation of rare earth ion intercalation and oxygen vacancy regulation.

[0036] The vanadium-based positive electrode material prepared in Example 7, the conductive agent Super C45, and the binder polyvinylidene fluoride were ground in a mortar at a mass ratio of 8:1:1. After the mixture was evenly ground, N-methylpyrrolidone was added and grinding continued to form a uniform slurry. The slurry was then evenly coated on a carbon cloth and dried in a vacuum drying oven at 70°C for 12 hours to produce a positive electrode sheet. The loading of the vanadium-based positive electrode material was 4.77 mg / cm 2 The button cell was assembled in the order of the negative electrode shell, zinc foil, glass fiber separator, positive electrode sheet, gasket, shrapnel and positive electrode shell, with 3 mol / L zinc trifluoromethanesulfonate electrolyte between the zinc foil and the positive electrode sheet.

[0037] Comparative Example 1 The commercial vanadium pentoxide cathode material was dried in a vacuum drying oven at 80 °C for 12 h before being used for structural and electrochemical performance tests.

[0038] The commercial vanadium pentoxide cathode material from Comparative Example 1, along with the conductive agent acetylene black and the binder polyvinylidene fluoride, were ground in a mortar at a mass ratio of 8:1:1. After the mixture was evenly ground, N-methylpyrrolidone was added and grinding continued to form a uniform slurry. The slurry was then evenly coated on a carbon cloth and dried in a vacuum oven at 70°C for 12 hours to produce a positive electrode sheet. The vanadium-based cathode material loading was 4.51 mg / cm 2 The button cell was assembled in the order of the negative electrode shell, zinc foil, glass fiber separator, positive electrode sheet, gasket, shrapnel and positive electrode shell, with 3 mol / L zinc trifluoromethanesulfonate electrolyte between the zinc foil and the positive electrode sheet.

[0039] Comparative Example 2 A method for preparing a vanadium-based positive electrode material comprises the following steps: S1. Add 0.007 mol of vanadium pentoxide to 100 mL of deionized water and stir at 500 rpm in a constant temperature water bath at 45°C for 1 hour to obtain a vanadium pentoxide aqueous solution. S2. Add 0.042 mol of cerium nitrate to the vanadium pentoxide aqueous solution, stir at 500 r / min in a constant temperature water bath at 45°C for 1 hour, and then ultrasonicate the solution in an ultrasonic cleaner at a power of 540 W and a frequency of 40 kHz for 1 hour; S3. Add 0.042 mol fructose to the sonicated solution and stir at 150 r / min for 20 min. Transfer the solution to a polytetrafluoroethylene-lined reactor and place the reactor in an oven at 110°C for 24 h. S4. After the temperature of the reactor drops to room temperature, take out the solution and centrifuge it at a speed of 7000 r / min for 3 hours. The centrifugal separator is washed alternately with deionized water and ethanol for 3 times, and then dried in a vacuum drying oven at 80°C for 12 hours to obtain a vanadium-based positive electrode material.

[0040] In this comparative example, cerium nitrate was used instead of cerium trichloride, and the remaining steps were the same as those in Example 1.

[0041] The vanadium-based positive electrode material prepared in Comparative Example 2, the conductive agent acetylene black, and the binder polyvinylidene fluoride were ground in a mortar at a mass ratio of 8:1:1. After the mixture was ground evenly, N-methylpyrrolidone was added and grinding continued to form a uniform slurry. The slurry was then evenly coated on a carbon cloth and dried in a vacuum drying oven at 70°C for 12 hours to obtain a positive electrode sheet. The loading of the vanadium-based positive electrode material was 4.83 mg / cm 2 The button cell was assembled in the order of the negative electrode shell, zinc foil, glass fiber separator, positive electrode sheet, gasket, shrapnel and positive electrode shell, with 3 mol / L zinc trifluoromethanesulfonate electrolyte between the zinc foil and the positive electrode sheet. Comparative Example 3 A method for preparing a vanadium-based positive electrode material comprises the following steps: S1. Add 0.007 mol of vanadium pentoxide to 100 mL of deionized water and stir at 500 rpm in a constant temperature water bath at 45°C for 1 hour to obtain a vanadium pentoxide aqueous solution. S2. Add 0.042 mol of cerium trichloride to the vanadium pentoxide aqueous solution, stir at 500 rpm in a constant temperature water bath at 45°C for 1 hour, and then ultrasonicate the solution in an ultrasonic cleaner at a power of 540 W and a frequency of 40 kHz for 1 hour; S3, stirring the sonicated solution at 150 r / min for 20 min, transferring the solution to a polytetrafluoroethylene-lined reactor, and placing the reactor in an oven at 110°C for 24 h; S4. After the temperature of the reactor drops to room temperature, take out the solution and centrifuge it at a speed of 7000 r / min for 3 hours. The centrifugal separator is washed alternately with deionized water and ethanol for 3 times, and then dried in a vacuum drying oven at 80°C for 12 hours to obtain a vanadium-based positive electrode material.

[0042] In this comparative example, fructose was not added, and the remaining steps were the same as those in Example 1.

[0043] The vanadium-based positive electrode material prepared in Comparative Example 3, the conductive agent acetylene black, and the binder polyvinylidene fluoride were ground in a mortar at a mass ratio of 8:1:1. After the mixture was evenly ground, N-methylpyrrolidone was added and grinding continued to form a uniform slurry. The slurry was then evenly coated on a carbon cloth and dried in a vacuum drying oven at 70°C for 12 hours to obtain a positive electrode sheet. The loading of the vanadium-based positive electrode material was 4.83 mg / cm 2 The button cell was assembled in the order of the negative electrode shell, zinc foil, glass fiber separator, positive electrode sheet, gasket, shrapnel and positive electrode shell, with 3 mol / L zinc trifluoromethanesulfonate electrolyte between the zinc foil and the positive electrode sheet.

[0044] Figure 1 The following are SEM images of the vanadium-based cathode materials of Comparative Example 1 (a) and Example 1 (b). The commercial vanadium-based cathode material in Comparative Example 1 is composed of irregularly stacked blocks with a smooth surface. The blocks form fewer channels, hindering sufficient contact between the electrolyte and the cathode material and its internal penetration. The vanadium-based cathode material in Example 1 is composed of stacked sheets with a rough surface. The sheet structure forms more channels, facilitating sufficient contact between the electrolyte and the cathode material and its internal penetration.

[0045] Figure 2 The EDS images of the vanadium-based positive electrode materials of Comparative Example 1 (a) and Example 1 (b) are shown. Due to the introduction of rare earth intercalation ions, cerium is contained in Example 1.

[0046] Figure 3 The XRD patterns of the vanadium-based cathode materials of Comparative Example 1 and Example 1 are shown below. The commercial vanadium-based cathode material of Comparative Example 1 exhibits good crystallization properties, with a spatial structure of Pmmn(59) orthorhombic crystal system characteristic peaks that match well with the pdf#97-064-7638 card. The (011) crystal plane of the vanadium-based cathode material of Example 1 shifts to the left, and the diffraction peak intensity decreases significantly, indicating that after preparation, the vanadium-based cathode material exhibits reduced crystallization strength and a wider crystal plane, providing more active sites for ion storage.

[0047] Figure 4 The vanadium-based cathode materials of Comparative Example 1 (a) and Example 1 (b) were tested at a scan rate of 1.0 mV∙s -1The CV curve area of ​​the vanadium-based cathode material of Example 1 is significantly larger than that of Comparative Example 1, indicating that the vanadium-based cathode material of Example 1 has higher charge storage energy.

[0048] Figure 5 The vanadium-based cathode materials of Comparative Example 1 (a) and Example 1 (b) were tested at 0.2 A∙g -1 -10.0 A∙g -1 GCD curves under different current densities. At different current densities, the specific capacity of the vanadium-based positive electrode material of Example 1 is significantly higher than that of Comparative Example 1.

[0049] Figure 6 The vanadium-based cathode materials of Comparative Example 1 (a) and Example 1 (b) were tested at 0.2 A∙g -1 -10.0 A∙g -1 Rate performance diagram under current density. Current density from 0.2 A∙g -1 Increase to 10 A∙g -1 Then it dropped to 0.2 A∙g -1 , the capacity recovery rate of Example 1 is 98.9%, while the capacity recovery rate of Comparative Example 1 is only 83.9%.

[0050] Figure 7 The vanadium-based positive electrode materials of Comparative Example 1 and Example 1 were prepared at a current density of 1.0 A∙g -1 The charge-discharge cycle performance diagram is shown in FIG. After 2000 cycles, the capacity retention rate of Example 1 is 89.1%, and the capacity retention rate of Comparative Example 1 is 49.8%. Moreover, the coulombic efficiency of Example 1 is always stable at about 100%.

[0051] The vanadium-based cathode material prepared in Example 1 was -1 At the current density, the specific capacity reaches 371 mAh∙g -1 ; The current density increases to 1 A∙g -1 , with a specific capacity of 282 mAh∙g -1 ; The current density increased to 10 A∙g -1 , with a specific capacity of 151 mAh∙g -1 ; Current density returns to 0.2 A∙g -1 The specific capacity is 367 mAh∙g -1 The capacity recovery rate is 98.9%, which has good rate performance. In addition, the positive electrode material has a long cycle life at 1.0 A∙g -1 The capacity retention rate after 2000 cycles is 89.1%.

[0052] The vanadium-based cathode material prepared in Comparative Example 2 was -1At the current density, the specific capacity is 346 mAh∙g -1 ; The current density increases to 1 A∙g -1 , with a specific capacity of 250 mAh∙g -1 ; The current density increased to 10 A∙g -1 , with a specific capacity of 127 mAh∙g -1 ; Current density returns to 0.2 A∙g -1 The specific capacity is 329 mAh∙g -1 , the capacity recovery rate is 95.1%; at 1.0 A∙g -1 The capacity retention rate after 2000 cycles is 82.6%.

[0053] The vanadium-based cathode material prepared in Comparative Example 3 was -1 At the current density, the specific capacity is 293 mAh∙g -1 ; The current density increases to 1 A∙g -1 , with a specific capacity of 189 mAh∙g -1 ; The current density increased to 10 A∙g -1 , with a specific capacity of 91 mAh∙g -1 ; Current density returns to 0.2 A∙g -1 The specific capacity is 275 mAh∙g -1 , the capacity recovery rate is 93.8%; at 1.0 A∙g -1 The capacity retention rate after 2000 cycles is 77.5%.

[0054] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing vanadium-based cathode materials by synergistically combining rare earth ion intercalation and oxygen vacancy regulation, characterized in that: The following steps are involved: S1. Put vanadium pentoxide into deionized water and stir at a constant temperature to obtain a vanadium pentoxide aqueous solution; S2. adding rare earth chloride to the vanadium pentoxide aqueous solution, stirring at a constant temperature, and then ultrasonically treating to obtain a mixed solution; S3, adding soluble sugars to the mixed solution, stirring, and then transferring to a polytetrafluoroethylene-lined reactor, placing the reactor in an oven, and keeping it warm for a certain period of time; S4. After the temperature of the reactor drops to room temperature, the solution is taken out and centrifuged. The centrifuged product is washed alternately with deionized water and ethanol, and then vacuum-dried to obtain a vanadium-based positive electrode material prepared by synergistically controlling rare earth ion intercalation and oxygen vacancy regulation.

2. The method for preparing vanadium-based cathode materials by synergistically regulating rare earth ion intercalation and oxygen vacancy according to claim 1, characterized in that: In S1, the constant temperature stirring temperature is 30-50° C., the time is 0.5-2 h, and the stirring speed is 200-700 r / min; the concentration of the obtained vanadium pentoxide aqueous solution is 0.003-0.07 mol / L.

3. The method for preparing vanadium-based cathode materials by synergistically regulating rare earth ion intercalation and oxygen vacancy according to claim 1, characterized in that: In S2, the rare earth chloride is one or more of cerium trichloride, praseodymium trichloride, samarium trichloride, europium trichloride, terbium trichloride, thulium trichloride and ytterbium trichloride.

4. The method for preparing vanadium-based cathode materials by synergistically regulating rare earth ion intercalation and oxygen vacancy according to claim 1, characterized in that: In S2, the molar ratio of the rare earth element of the rare earth chloride to the vanadium element of the vanadium pentoxide in S1 is 1-14:1; the constant temperature stirring temperature is 30-50°C, the time is 0.5-2 h, and the stirring speed is 200-700 r / min; the ultrasonic treatment power is 360-540 W, the frequency is 20-50 kHz, and the time is 0.5-2 h.

5. The method for preparing vanadium-based cathode materials by synergistically combining rare earth ion intercalation and oxygen vacancy regulation according to claim 1, wherein: In S3, the soluble sugar is one or more of xylose, fructose, lactose, maltose, arabinose, glucose and galactose.

6. The method for preparing vanadium-based cathode materials by synergistically combining rare earth ion intercalation and oxygen vacancy regulation according to claim 1, wherein: In the S3, the molar ratio of the soluble sugar to the vanadium element in the vanadium pentoxide in S1 is 0.25-5:

1.

7. The method for preparing vanadium-based cathode materials by synergistically combining rare earth ion intercalation and oxygen vacancy regulation according to claim 1, wherein: In the step S3, the stirring speed is 100-300 r / min, the stirring time is 20-40 min, the oven temperature is 100-140° C., and the holding time is 12-36 h.

8. The method for preparing vanadium-based cathode materials by synergistically combining rare earth ion intercalation and oxygen vacancy regulation according to claim 1, wherein: In the S4, the centrifugal speed is 4000-8000 r / min, the time is 2-4 h; the washing is alternately performed 2-5 times; and the vacuum drying temperature is 60-80° C., and the time is 12-24 h.

9. A vanadium-based cathode material prepared by the method for preparing a vanadium-based cathode material by synergistically combining rare earth ion intercalation and oxygen vacancy regulation as described in any one of claims 1 to 8.

10. A battery, characterized in that: The positive electrode material of the battery is the vanadium-based positive electrode material according to claim 9.

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