Preparation method of cubic sulfide composite positive electrode material for sodium-magnesium hybrid battery
By preparing a cubic nitrogen-doped carbon layer CoS2 composite cathode material, the problems of slow diffusion and structural instability of magnesium-ion battery cathode materials were solved, and battery performance with high energy density and long cycle life was achieved.
Patent Information
- Application Number
- CN202511565882.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-30
- Publication Date
- 2026-01-23
AI Technical Summary
Existing magnesium-ion battery cathode materials suffer from high diffusion barriers and slow migration kinetics, resulting in low discharge voltage and poor rate performance. Furthermore, sulfide cathode materials are prone to pulverization and structural instability during charge and discharge, leading to short cycle life.
A cubic CoS2 composite cathode material with uniform particles and high electronic conductivity was prepared by first constructing a cubic structure of polydopamine-coated Prussian blue analogue, and then carbonizing it in situ to form a nitrogen-doped carbon layer. By controlling the reaction conditions and process parameters, a cubic CoS2 composite material was prepared.
It significantly improves the electrochemical performance of magnesium-ion batteries, enhances cycle stability and rate performance, extends the lifespan of electrode materials, and provides high energy density and structural stability.
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Figure CN121394358A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of sodium-magnesium hybrid ion batteries, and particularly relates to a preparation method of a cubic sulfide composite cathode material for a sodium-magnesium hybrid battery. BACKGROUND
[0002] In recent years, with the continuous growth of human society's demand for energy, environmental problems and energy crisis are becoming increasingly serious. Although lithium-ion batteries dominate the secondary battery market, their further development is facing multiple bottlenecks such as resource scarcity, cost escalation and safety performance. Under this background, the development of magnesium-ion batteries as a highly potential alternative technology is increasingly necessary. First, the crustal reserves of magnesium are much higher than that of lithium, and the raw material sources are extensive and low-cost, which can effectively alleviate the strategic dependence on lithium resources. Second, the theoretical volume capacity of magnesium metal negative electrode is twice that of lithium metal, and it is not easy to form dendrites during the deposition-dissolution process, thereby significantly improving the safety and cycle life of the battery, providing a fundamental path to solve the safety problems of high-energy-density batteries. Third, magnesium is a divalent ion, and based on double-electron transfer reaction, it is expected to achieve higher energy density. Therefore, the development of high-performance magnesium-ion battery technology is of great significance to promote the innovation of the next generation of energy storage systems and meet the urgent needs of high-safety, low-cost and high-energy-density energy storage solutions in the fields of large-scale energy storage and electric vehicles.
[0003] Although magnesium-ion batteries have a broad prospect, their commercialization process is mainly limited by the lack of high-performance cathode materials. Magnesium ions have two positive charges, strong polarization, and strong coulomb interaction between anions and host material atoms in the lattice, resulting in a very high diffusion energy barrier in conventional intercalation cathodes, slow migration kinetics, and thus low discharge voltage and rate performance. In order to improve the diffusion rate of magnesium ions, sodium salt is introduced into the electrolyte to build a sodium-magnesium hybrid battery, which takes advantage of the mature sodium ion fast transmission in the material, effectively avoiding the slow diffusion of magnesium ions in the solid phase, and thus achieving high power output and long cycle life. In addition, in order to alleviate the structural deformation of the intercalation cathode material caused by the slow diffusion of divalent magnesium ions in the solid phase, the development of sulfide cathode materials based on conversion reaction has become an important way. Sulfur ions have larger ionic radius and stronger polarizability, which can effectively weaken the strong coulomb force between magnesium ions, significantly reduce the ion diffusion barrier, and improve the migration rate of magnesium ions. At the same time, the sulfide system usually provides higher theoretical specific capacity and better structural stability, providing a key material basis for realizing high energy density and long cycle life of magnesium-ion batteries. However, the practical application of sulfides still faces several severe challenges. First, during charging and discharging, sulfides will undergo significant volume expansion and contraction, which can easily cause active material powdering and peeling from the current collector, resulting in rapid capacity decay and shortening of cycle life. Second, the intrinsic electronic and ionic conductivity of sulfur and its discharge products is low, which limits the rate performance and requires a complex conductive network structure. SUMMARY
[0004] The technical problem to be solved by the present application is to provide a preparation method of a cubic sulfide composite cathode material for a sodium-magnesium hybrid battery, which solves the problems of poor electrochemical performance, easy decay and short cycle life of existing sulfide cathode materials.
[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a preparation method of a cubic sulfide composite cathode material for a sodium-magnesium hybrid battery, characterized in that the method comprises the following steps: Step one, the cobalt source is dissolved in a mixed solution of ethanol and water and stirred for 3-5 hours to obtain solution A, and the potassium cobalt cyanide is dissolved in a mixed solution of ethanol and water and stirred for 1-2 hours to obtain solution B, then solution A is added dropwise to solution B and stirred constantly, after the addition is completed, the mixed solution is left to stand for 8-12 hours, then washed with ethanol for 3-5 times and the precipitate is collected and dried in a vacuum drying oven at 80-120°C for 12-24 hours to obtain Co-PBA; Step two, the Co-PBA in step one is added to a tris-hydroxymethyl aminomethane buffer solution, a surfactant is added and ultrasonic is applied for 20-40 minutes, after stirring for 2-3 hours, dopamine hydrochloride is added and stirred at room temperature for 12-16 hours, then washed with ethanol for 3-5 times and dried in a vacuum drying oven at 90-120°C for 8-12 hours to obtain Co-PBA@PDA composite material. Step three, the Co-PBA@PDA composite material in step two is ground and subjected to in-situ carbonization sintering under argon atmosphere, then the black powder obtained is mixed with sulfur powder and subjected to secondary sintering under argon atmosphere to obtain a cubic sulfide composite positive electrode material.
[0006] The preparation method of the cubic sulfide composite positive electrode material for sodium-magnesium hybrid batteries, wherein in step one, the cobalt source is cobalt nitrate or cobalt sulfate, and the volume ratio of deionized water to ethanol in the mixed solution of ethanol and water is 1-4:1, and the molar ratio of the cobalt source to potassium cobalt cyanide is 1:2-1:4. By controlling the composition of the mixed solution, the morphology of the product material can be controlled.
[0007] The preparation method of the cubic sulfide composite positive electrode material for sodium-magnesium hybrid batteries, wherein in step one, the complexing agent is polyvinylpyrrolidone PVP or sodium oxalate, and the molar ratio of the complexing agent to potassium cobalt cyanide is 2-6:1. This kind and amount of complexing agent can combine with Co2⁺ to obtain Co-PBA, and slowly release free Co2⁺ during the subsequent polydopamine coating process, greatly reducing the nucleation and crystal nucleus growth rate of Prussian blue analogues, thereby facilitating the formation of Co-PBA@PDA composite material with high crystallinity, few defects and regular microcrystalline structure.
[0008] The preparation method of the cubic sulfide composite positive electrode material for sodium-magnesium hybrid batteries, wherein in step one, the rate of dropwise addition is 800-1000 μL / min, and the rate of constant stirring is 600-1000 rpm. By controlling the rate of dropwise addition and the rate of constant stirring, the reaction rate can be controlled.
[0009] The preparation method of the cubic sulfide composite positive electrode material for sodium-magnesium hybrid batteries has the following characteristics: in step two, the surface active agent is polyvinyl alcohol, and the mass ratio of the surface active agent to Co-PBA is 1:10-15. The surface active agent is conducive to the smooth progress of the polymerization reaction of polydopamine.
[0010] The preparation method of the cubic sulfide composite positive electrode material for sodium-magnesium hybrid batteries has the following characteristics: in step three, the in-situ carbonization sintering process is to sinter at a rate of 2℃ / min to 500-800℃ for 3-6h.
[0011] The preparation method of the cubic sulfide composite positive electrode material for sodium-magnesium hybrid batteries has the following characteristics: in step three, the mass ratio of the black powder to sulfur powder is 1:2-5, and the secondary sintering process is to sinter at a rate of 1℃ / min to 300-500℃ for 1-3h.
[0012] The preparation method of the cubic sulfide composite positive electrode material for sodium-magnesium hybrid batteries has the following characteristics: the positive electrode sheet prepared from the cubic sulfide composite positive electrode material in step three is applied to a sodium-magnesium hybrid battery.
[0013] Compared with the prior art, the present application has the following advantages: 1. The present application first constructs a cubic structure of polydopamine-coated Prussian blue analog, then converts it into a nitrogen-doped carbon layer by in-situ carbonization of polydopamine, and then obtains a cubic structure of CoS2 composite positive electrode material by sulfidation. The composite positive electrode material has a small particle size, a uniform distribution, a high electronic conductivity, and can effectively improve the electrochemical performance of the CoS2 composite positive electrode material, and is suitable for sodium-magnesium hybrid batteries.
[0014] 2. The sulfide composite positive electrode material prepared by the present application has a complete cubic structure, effectively increases the specific surface area of the material, provides more active sites, is conducive to the transmission of ions and electrons in the electrochemical reaction process, effectively improves the cycle stability and rate performance of the positive electrode material, and the cubic structure effectively relieves the structural stress in the electrochemical reaction process and maintains the stability of the electrode structure.
[0015] 3. The sulfide composite positive electrode material prepared by the present application has a stable structure, the nitrogen-doped carbon layer effectively improves the electronic conductivity of the positive electrode material, promotes the transmission of active ions, and its excellent mechanical toughness can effectively buffer the huge volume change of sulfide in the cycle process, inhibit the pulverization and structure collapse of the electrode material, thereby significantly improving the cycle stability and life; at the same time, the positive electrode material particles are uniform and consistent, have good dispersibility and high crystallinity, and have a nanoscale particle size, which is conducive to improving the electrochemical performance of the positive electrode material.
[0016] 4、The cubic sulfide composite positive electrode material prepared by the method has stable cycle life and excellent rate performance when used in a sodium-magnesium hybrid battery, the preparation process is simple and relatively mature, and the material has high practical application value.
[0017] The technical solutions of the present application are described in further detail below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 The XRD pattern of the cubic sulfide composite positive electrode material prepared in Example 1 of the present application.
[0019] Figure 2 The SEM image of the cubic sulfide composite positive electrode material prepared in Example 1 of the present application.
[0020] Figure 3 The cycle performance graph of the cubic sulfide composite positive electrode material prepared in Example 1 of the present application.
[0021] Figure 4 The rate performance graph of the cubic sulfide composite positive electrode material prepared in Example 1 of the present application.
[0022] Figure 5 The SEM image of the sulfide composite positive electrode material prepared in Comparative Example 1 of the present application. DETAILED DESCRIPTION
[0023] Example 1 This example includes the following steps: Step one, 0.01 mol of cobalt sulfate is dissolved in a mixed solution of ethanol and deionized water with a volume ratio of 1:1 and stirred for 4 h to obtain solution A, 0.02 mol of potassium cobalt cyanide is dissolved in a mixed solution of ethanol and water with a volume ratio of 1:1 and 0.06 mol of sodium oxalate is added and stirred for 1.5 h to obtain solution B, then solution A is added dropwise to solution B at a rate of 900 μL / min and continuously stirred at a rate of 800 rpm, after the addition is completed, the mixed solution is left to stand for 10 h, then washed with ethanol 4 times and the precipitate is collected and placed in a vacuum drying oven at 100℃ for 10 h to obtain Co-PBA; Step two, 500 mg of Co-PBA in step one is added to 150 mL of tris-hydroxymethyl aminomethane buffer, 50 mg of polyvinyl alcohol is added and ultrasonicated for 20 min, 100 mg of dopamine hydrochloride is added after stirring for 2.5 h and stirring at room temperature for 12 h, then washed with ethanol 4 times and placed in a vacuum drying oven at 100℃ for 8 h to obtain Co-PBA@PDA composite material; Step three, 300 mg of Co-PBA@PDA composite material in step two was ground, and then in-situ carbonized and sintered at 600℃ for 4h under argon atmosphere at a rate of 2℃ / min, then the obtained black powder was mixed with sulfur powder at a mass ratio of 1:2, and then secondarily sintered at 400℃ for 2h under argon atmosphere at a rate of 1℃ / min, to obtain a cubic sulfide composite positive electrode material.
[0024] Figure 1 The XRD pattern of the cubic sulfide composite positive electrode material prepared in this example is shown in Figure 1 It can be seen that the particle morphology of the composite positive electrode material is cubic structure, and the particle size is 100 nm.
[0025] Figure 2 The SEM image of the cubic sulfide composite positive electrode material prepared in this example is shown in Figure 2 It can be seen that the composition of the composite positive electrode material is CoS2, and the nitrogen-doped carbon layer has no obvious effect on the structure of the sulfide.
[0026] The cubic sulfide composite positive electrode material prepared in this example was used as the positive electrode material of a sodium-magnesium hybrid battery, and a magnesium metal sheet was used as the counter electrode. A battery button cell was assembled in an argon-filled glove box, and the charge-discharge cycle was carried out at a current density of 200mA·g-1 in the voltage range of 0.01V~1.8V. The cycle performance and rate performance are shown in Figure 3 and Figure 4 .
[0027] It can be seen from Figure 3 that the initial discharge capacity of the cubic sulfide composite positive electrode material is 660mAh·g-1, and the capacity after 80 cycles is 920mAh·g-1, showing excellent cycle stability; from Figure 3 it can be seen that the cubic sulfide composite positive electrode material still has a reversible capacity of 130mAh·g-1 at a current density of 2000mA·g-1, showing a fast charge-discharge capacity.
[0028] The cobalt source in this example can also be replaced by cobalt nitrate.
[0029] Comparative Example 1 The difference between this comparative example and Example 1 is that sodium oxalate in step one is replaced by sodium citrate, and a sulfide composite positive electrode material is obtained in step three.
[0030] Figure 5 The SEM image of the sulfide composite positive electrode material prepared in this comparative example is shown in Figure 5It can be seen that the sulfide composite positive electrode material is aggregated into large particles, and the cubic nanostructure disappears, which is mainly due to the fact that the complexing ability of citric acid with metal ions is relatively weak compared with oxalate ions in Example 1, and the reaction rate control effect on metal ions is poor, so the precipitation reaction rate is fast, resulting in large and uneven particles.
[0031] Example 2 This example includes the following steps: Step one, 0.01 mol of cobalt sulfate is dissolved in a mixed solution of ethanol and deionized water with a volume ratio of 4:1 and stirred for 5h to obtain solution A, 0.02 mol of potassium cobalt cyanide is dissolved in a mixed solution of ethanol and water with a volume ratio of 4:1 and 0.12 mol of polyvinylpyrrolidone is added and stirred for 2h to obtain solution B, then solution A is added dropwise to solution B at a rate of 1000μL / min and continuously stirred at a rate of 1000rpm, after the addition is completed, the mixed solution is left to stand for 12h, then washed with ethanol for 5 times and the precipitate is collected and placed in a vacuum drying oven at 120℃ for 24h to obtain Co-PBA; Step two, 500mg of Co-PBA in step one is added to 200mL of tris-hydroxymethyl aminomethane buffer, 35mg of polyvinyl alcohol is added and ultrasonicated for 20min, 200mg of dopamine hydrochloride is added after stirring for 3h and stirred at room temperature for 16h, then washed with ethanol for 5 times and placed in a vacuum drying oven at 120℃ for 12h to obtain Co-PBA@PDA composite material; Step three, 300mg of Co-PBA@PDA composite material in step two is ground and heated to 800℃ at a rate of 2℃ / min under argon atmosphere for in-situ carbonization sintering for 6h, then the obtained black powder is mixed with sulfur powder at a mass ratio of 1:5 and heated to 500℃ at a rate of 1℃ / min under argon atmosphere for secondary sintering for 3h to obtain cubic sulfide composite positive electrode material.
[0032] According to the method in Example 1, the cubic sulfide composite positive electrode material prepared in this example is used as the positive electrode material of sodium-magnesium hybrid battery for cycle performance test, and the results show that the initial discharge capacity of the cubic sulfide composite positive electrode material is 650mAh•g-1, and the capacity after 80 cycles is 910mAh•g-1, showing excellent cycle stability.
[0033] Example 3 This example includes the following steps: Step one, 0.01 mol of cobalt sulfate was dissolved in a mixed solution of ethanol and deionized water with a volume ratio of 2:1 and stirred for 3 h to obtain solution A, 0.02 mol of potassium cobalt cyanide was dissolved in a mixed solution of ethanol and water with a volume ratio of 2:1 and 0.04 mol of sodium oxalate was added and stirred for 1 h to obtain solution B, then solution A was added dropwise to solution B at a rate of 800 μL / min and continuously stirred at a rate of 600 rpm, after the addition was completed, the mixed solution was left to stand for 8 h, then washed with ethanol for 3 times and the precipitate was collected and placed in a vacuum drying oven at 80℃ for 12 h to obtain Co-PBA; Step two, 500 mg of Co-PBA in step one was added to 100 mL of tris-hydroxymethyl aminomethane buffer, 40 mg of polyvinyl alcohol was added and ultrasonic was applied for 20 min, 50 mg of dopamine hydrochloride was added after stirring for 2 h and stirred at room temperature for 12 h, then washed with ethanol for 3 times and placed in a vacuum drying oven at 90℃ for 8 h to obtain Co-PBA@PDA composite material; Step three, 300 mg of Co-PBA@PDA composite material in step two was ground and heated to 500℃ at a rate of 2℃ / min under argon atmosphere for in-situ carbonization sintering for 3 h, then the obtained black powder was mixed with sulfur powder at a mass ratio of 1:2 and heated to 300℃ at a rate of 1℃ / min under argon atmosphere for secondary sintering for 1 h to obtain cubic sulfide composite cathode material.
[0034] According to the method in example 1, the cubic sulfide composite cathode material prepared in this example was used as the positive electrode material of sodium-magnesium hybrid battery for cycle performance test, the results showed that the initial discharge capacity of the cubic sulfide composite cathode material was 665 mAh·g-1, and the capacity after 80 cycles was 925 mAh·g-1, showing excellent cycle stability.
[0035] Example 4 This example includes the following steps: Step one, 0.01 mol of cobalt sulfate was dissolved in a mixed solution of ethanol and deionized water with a volume ratio of 3:1 and stirred for 3 h to obtain solution A, 0.02 mol of potassium cobalt cyanide was dissolved in a mixed solution of ethanol and water with a volume ratio of 3:1 and 0.10 mol of sodium oxalate was added and stirred for 2 h to obtain solution B, then solution A was added dropwise to solution B at a rate of 850 μL / min and continuously stirred at a rate of 700 rpm, after the addition was completed, the mixed solution was left to stand for 9 h, then washed with ethanol for 4 times and the precipitate was collected and placed in a vacuum drying oven at 100℃ for 16 h to obtain Co-PBA; Step two, take 500 mg of Co-PBA in step one into 150 mL of Tris buffer, add 50 mg of polyvinyl alcohol and ultrasonic for 20 min, after stirring for 2.5 h, add 150 mg of dopamine hydrochloride, stir at room temperature for 14 h, then wash with ethanol for 4 times, and put into a vacuum drying oven at 110℃ for 10 h to obtain Co-PBA@PDA composite material; Step three, take 300 mg of Co-PBA@PDA composite material in step two after grinding, heat to 600℃ at a rate of 2℃ / min under argon atmosphere for in-situ carbonization sintering for 3.5 h, then mix the obtained black powder with sulfur powder according to a mass ratio of 1:3, heat to 350℃ at a rate of 1℃ / min under argon atmosphere for secondary sintering for 1.5 h to obtain a cubic sulfide composite positive electrode material.
[0036] According to the method in Example 1, the cubic sulfide composite positive electrode material prepared in this example was used as the positive electrode material of the sodium-magnesium hybrid battery for cycle performance test, and the results showed that the initial discharge capacity of the cubic sulfide composite positive electrode material was 640 mAh·g-1, and the capacity after 80 cycles was 910 mAh·g-1, showing excellent cycle stability.
[0037] Example 5 This example includes the following steps: Step one, dissolve 0.01 mol of cobalt sulfate in a mixed solution of ethanol and deionized water with a volume ratio of 4:1 and stir for 3 h to obtain solution A, dissolve 0.04 mol of potassium cobalt cyanide in a mixed solution of ethanol and water with a volume ratio of 4:1 and add 0.08 mol of sodium oxalate and stir for 1.5 h to obtain solution B, then add solution A dropwise to solution B at a rate of 900 μL / min and continuously stir at a rate of 950 rpm, after the addition is completed, the mixed solution is left to stand for 10 h, then washed with ethanol for 3 times and collect the precipitate, and put into a vacuum drying oven at 105℃ for 18 h to obtain Co-PBA; Step two, take 500 mg of Co-PBA in step one into 150 mL of Tris buffer, add 50 mg of polyvinyl alcohol and ultrasonic for 20 min, after stirring for 2.5 h, add 150 mg of dopamine hydrochloride, stir at room temperature for 14 h, then wash with ethanol for 4 times, and put into a vacuum drying oven at 110℃ for 10 h to obtain Co-PBA@PDA composite material; Step three, take 300 mg of Co-PBA@PDA composite material in step two after grinding, in argon atmosphere, with a rate of 2 ℃ / min to 550 ℃ for in-situ carbonization sintering 5.5 h, then the obtained black powder and sulfur powder are mixed according to the mass ratio of 1:4, in argon atmosphere, with a rate of 1 ℃ / min to 450 ℃ for secondary sintering 2 h, to obtain a cubic sulfide composite positive electrode material.
[0038] According to the method in example 1, the cubic sulfide composite positive electrode material prepared in this example is used as the positive electrode material of the sodium-magnesium hybrid battery for cycle performance test, and the results show that the first discharge capacity of the cubic sulfide composite positive electrode material is 665 mAh·g-1, and the capacity after 80 cycles is 923 mAh·g-1, showing excellent cycle stability.
[0039] Example 6 This example includes the following steps: Step one, 0.01 mol of cobalt sulfate is dissolved in a mixed solution of ethanol and deionized water with a volume ratio of 1:1 and stirred for 4 h to obtain solution A, 0.02 mol of potassium cobalt cyanide is dissolved in a mixed solution of ethanol and water with a volume ratio of 2:1 and 0.08 mol of polyvinylpyrrolidone PVP is added and stirred for 2 h to obtain solution B, then solution A is added dropwise to solution B at a rate of 900 μL / min and continuously stirred at a rate of 850 rpm, after the addition is completed, the mixed solution is left to stand for 10 h, then washed with ethanol for 3 times and the precipitate is collected and placed in a vacuum drying oven at 95 ℃ for 15 h to obtain Co-PBA; Step two, take 500 mg of Co-PBA in step one and add 120 mL of tris-hydroxymethyl aminomethane buffer, add 4 mg of polyvinyl alcohol and ultrasonic for 20 min, after stirring for 2 h, add 120 mg of dopamine hydrochloride and stir at room temperature for 15 h, then wash with ethanol for 3 times and put into a vacuum drying oven at 100 ℃ for 8 h to obtain Co-PBA@PDA composite material; Step three, take 300 mg of Co-PBA@PDA composite material in step two after grinding, in argon atmosphere, with a rate of 2 ℃ / min to 550 ℃ for in-situ carbonization sintering 4 h, then the obtained black powder and sulfur powder are mixed according to the mass ratio of 1:4, in argon atmosphere, with a rate of 1 ℃ / min to 450 ℃ for secondary sintering 2.5 h, to obtain a cubic sulfide composite positive electrode material.
[0040] According to the method in Example 1, the cubic sulfide composite positive electrode material prepared in this example was used as the positive electrode material of the sodium-magnesium hybrid battery for cycle performance test, and the results showed that the initial discharge capacity of the cubic sulfide composite positive electrode material was 640 mAh·g-1, and the capacity after 80 cycles was 915 mAh·g-1, showing excellent cycle stability.
[0041] Example 7 This example includes the following steps: Step one, 0.01 mol of cobalt sulfate was dissolved in a mixed solution of ethanol and deionized water with a volume ratio of 2.5:1 and stirred for 4 h to obtain solution A, 0.02 mol of potassium cobalt cyanide was dissolved in a mixed solution of ethanol and water with a volume ratio of 2.5:1 and 0.07 mol of sodium oxalate was added and stirred for 2 h to obtain solution B, then solution A was added dropwise to solution B at a rate of 800 μL / min and continuously stirred at a rate of 750 rpm, after the addition was completed, the mixed solution was left to stand for 10 h, then washed with ethanol 4 times and the precipitate was collected and placed in a vacuum drying oven at 105℃ for 12 h to obtain Co-PBA; Step two, 500 mg of Co-PBA in step one was added to 160 mL of tris-hydroxymethyl aminomethane buffer, 34 mg of polyvinyl alcohol was added and ultrasonicated for 40 min, 100 mg of dopamine hydrochloride was added after stirring for 2 h and stirred at room temperature for 15 h, then washed with ethanol 3 times and placed in a vacuum drying oven at 100℃ for 10 h to obtain Co-PBA@PDA composite material; Step three, 300 mg of Co-PBA@PDA composite material in step two was ground and carbonized and sintered in situ at a rate of 2℃ / min to 750℃ under argon atmosphere for 4 h, then the obtained black powder was mixed with sulfur powder at a mass ratio of 1:5 and sintered again at a rate of 1℃ / min to 400℃ under argon atmosphere for 2.5 h to obtain the cubic sulfide composite positive electrode material.
[0042] According to the method in Example 1, the cubic sulfide composite positive electrode material prepared in this example was used as the positive electrode material of the sodium-magnesium hybrid battery for cycle performance test, and the results showed that the initial discharge capacity of the cubic sulfide composite positive electrode material was 620 mAh·g-1, and the capacity after 80 cycles was 915 mAh·g-1, showing excellent cycle stability.
[0043] The above is only a preferred embodiment of the present application, and does not limit the present application in any way. Any simple modification, change and equivalent change made according to the technical essence of the present application to the above embodiment are still within the protection scope of the technical solution of the present application.
Claims
1. A method for preparing a cubic sulfide composite cathode material for sodium-magnesium hybrid batteries, characterized in that, The method includes the following steps: Step 1: Dissolve the cobalt source in a mixed solution of ethanol and water and stir for 3-5 hours to obtain solution A. Dissolve potassium cobalt cyanide in a mixed solution of ethanol and water and add a complexing agent and stir for 1-2 hours to obtain solution B. Then, add solution A dropwise to solution B while stirring continuously. After the addition is complete, let the resulting mixed solution stand for 8-12 hours. Then wash with ethanol 3-5 times and collect the precipitate. Place it in a vacuum drying oven and dry at 80-120℃ for 12-24 hours to obtain Co-PBA. Step 2: Take the Co-PBA from Step 1 and add it to tris(hydroxymethyl)aminomethane buffer. Add a surfactant and sonicate for 20-40 minutes. Stir for 2-3 hours and then add dopamine hydrochloride. Stir at room temperature for 12-16 hours. Then wash with ethanol 3-5 times and place in a vacuum drying oven at 90-120℃ for 8-12 hours to obtain the Co-PBA@PDA composite material. Step 3: After grinding the Co-PBA@PDA composite material from Step 2, perform in-situ carbonization sintering under an argon atmosphere. Then, mix the resulting black powder with sulfur powder and perform secondary sintering under an argon atmosphere to obtain a cubic sulfide composite cathode material.
2. The method for preparing a cubic sulfide composite cathode material for a sodium-magnesium hybrid battery according to claim 1, characterized in that, The cobalt source mentioned in step one is cobalt nitrate or cobalt sulfate, and the volume ratio of deionized water to ethanol in the mixed solution of ethanol and water is 1~4:1, and the molar ratio of cobalt source to potassium cobalt cyanide is 1:2~1:
4.
3. The method for preparing a cubic sulfide composite cathode material for a sodium-magnesium hybrid battery according to claim 1, characterized in that, The complexing agent mentioned in step one is polyvinylpyrrolidone (PVP) or sodium oxalate, and the molar ratio of the complexing agent to potassium cobalt cyanide is 2~6:
1.
4. The method for preparing a cubic sulfide composite cathode material for a sodium-magnesium hybrid battery according to claim 1, characterized in that, The rate of dropwise addition in step one is 800 μL / min to 1000 μL / min, and the stirring rate is 600 rpm to 1000 rpm.
5. The method for preparing a cubic sulfide composite cathode material for a sodium-magnesium hybrid battery according to claim 1, characterized in that, The surfactant mentioned in step two is polyvinyl alcohol, and the mass ratio of the surfactant to Co-PBA is 1:10~15.
6. The method for preparing a cubic sulfide composite cathode material for a sodium-magnesium hybrid battery according to claim 1, characterized in that, The in-situ carbonization sintering process described in step three is as follows: heating to 500℃~800℃ at a rate of 2℃ / min and sintering for 3h~6h.
7. The method for preparing a cubic sulfide composite cathode material for a sodium-magnesium hybrid battery according to claim 1, characterized in that, In step three, the mass ratio of black powder to sulfur powder is 1:2~5, and the secondary sintering process is as follows: heat to 300℃~500℃ at a rate of 1℃ / min and sinter for 1h~3h.
8. The method for preparing a cubic sulfide composite cathode material for a sodium-magnesium hybrid battery according to claim 1, characterized in that, The positive electrode sheet prepared from the cubic sulfide composite positive electrode material described in step three is applied to a sodium-magnesium hybrid battery.