Preparation method of new energy battery negative electrode material

Abstract

The application relates to the technical field of nickel-hydrogen secondary batteries, in particular to a preparation method of a new energy battery negative electrode material. 10 Ce5Fe5Ni 70 Mn6B2Al2 alloy, the pure metals are placed into a smelting furnace to be smelted according to a conventional method, the alloy ingot is mechanically broken and ground into a powder below 200 meshes; ZIF-67 and the alloy powder of step (1) are ball milled at a mass ratio of 1-5:95-99 for 0.5-1.5 h to prepare ZIF-67 / La 10 Ce5Fe5Ni 70 Mn6B2Al2 alloy powder, the ZIF-67 and the alloy powder of step (1) are ball milled at a mass ratio of 1-5:95-99 for 0.5-1.5 h to prepare ZIF-67 / La 10 Ce5Fe5Ni 70 Mn6B2Al2 composite hydrogen storage alloy material. The method is simple, and can better improve the comprehensive electrochemical performance of the battery.

Description

Technical Field

[0001] This application relates to the field of nickel-metal hydride secondary battery technology, and more specifically, it relates to a method for preparing a negative electrode material for new energy batteries. Background Technology

[0002] To maintain sustainable development, it is essential to adjust the energy structure and actively develop various new energy sources, especially renewable and pollution-free "green energy." Among these, green chemical power sources, represented by hydride / nickel (MH / Ni) secondary batteries, have been or will soon be widely used in transportation, scientific research, industrial and agricultural production, and people's daily lives, becoming substitutes for various polluting traditional power sources.

[0003] Hydrogen storage materials, as anode materials, have a significant impact on the performance of nickel-metal hydride (NiMH) batteries. Currently, developing hydrogen storage alloys with high stability, high power, and low cost is an important direction to meet the development needs of NiMH batteries for electric vehicles. Although hydrogen storage alloys with high hydrogen storage capacity and efficient battery discharge have been developed both domestically and internationally, most of the hydrogen storage alloys currently used as anode materials contain expensive alloying elements such as Co, which cause serious environmental pollution. There is an urgent need to develop a Co-free hydrogen storage alloy that is low-cost, has low environmental pollution, and exhibits good electrochemical performance.

[0004] ZIF-67 is a metal-organic framework material composed of cobalt ions and 2-methylimidazolium ions, possessing high specific surface area, tunable porosity, and excellent thermal and chemical stability. ZIF-67 and its derivatives exhibit good performance in adsorption, separation, electrochemistry, and catalysis. By improving ball milling time and dosage, the electrochemical performance of existing systems, such as cycle life, can be enhanced. The advantages of the original system can be maintained while further modifications are made to address its shortcomings. ZIF-67 exhibits superior electrochemical performance, and its preparation process is easy to master, with low production costs and virtually zero environmental pollution. Summary of the Invention

[0005] This disclosure provides a method for preparing a negative electrode material for new energy batteries. The method involves batching, smelting, and compounding to prepare a hydrogen storage alloy. The steps are simple and easy to control, and can effectively improve the electrochemical performance of the battery material.

[0006] In a first aspect, this disclosure provides a negative electrode material for a new energy battery, wherein the negative electrode material is a solid-state hydrogen storage alloy composite material, and the chemical formula of the composite material is ZIF-67 / La. 10 Ce5Fe5Ni 70 Mn6B2Al2.

[0007] Secondly, this disclosure provides a method for preparing a negative electrode material for new energy batteries, comprising the following steps:

[0008] (1) Preparation of La 10 Ce5Fe5Ni 70 Mn6B2Al2 alloy powder: according to La 10 Ce5Fe5Ni 70 The mass ratio of Mn6B2Al2 alloy is determined by placing each pure metal in a melting furnace for melting, melting into alloy ingots with uniform composition, and then mechanically crushing and grinding the alloy ingots into powder with a mesh size of less than 200.

[0009] (2) Preparation of carbonized ZIF-67 (metal-organic framework material): weigh cobalt nitrate and 2-methylimidazolium, and prepare ZIF-67 by processing. Place dicyandiamine and ZIF-67 according to the gas flow direction of the tube furnace. Both crucibles are open and N2 is introduced as a protective gas. After high temperature treatment, carbonized ZIF-67 is prepared.

[0010] (3) Preparation of ZIF-67 / La 10 Ce5Fe5Ni 70 Mn6B2Al2 composite hydrogen storage alloy material: ZIF-67 and La... 10 Ce5Fe5Ni 70 The mass ratio of Mn6B2Al2 alloy powder is 1-5:99-95. The ZIF-67 and the alloy powder from step (1) are simultaneously placed in a mortar and ground thoroughly to produce the ZIF-67 / La alloy. 10 Ce5Fe5Ni 70 Mn6B2Al2 composite hydrogen storage alloy material.

[0011] Preferably, in step (1), the pure metals are placed into the smelting furnace in order of increasing melting point from bottom to top and smelted using conventional methods.

[0012] Preferably, in step (2), the treatment method for cobalt nitrate and 2-methylimidazolium is as follows: after sonication for 15 to 25 minutes, the mixture is stirred and allowed to stand at room temperature for 12 to 24 hours. The settled solution is then washed with methanol by vacuum filtration and finally dried.

[0013] Preferably, in step (2), the high-temperature treatment includes raising the temperature to 550-600°C at a rate of 2-5°C / min and holding it at that temperature for 1-4 hours.

[0014] Preferably, in step (2), the preparation method of ZIF-67 specifically includes the following steps: weighing cobalt nitrate and 2-methylimidazole in a molar ratio of 1:4 to 10, placing the cobalt nitrate and 2-methylimidazole into a beaker containing 25 ml of methanol and ultrasonically stirring for 15 to 25 min; slowly pouring the ultrasonically treated cobalt nitrate solution into the 2-methylimidazole solution, continuing to stir for 10 to 20 min, allowing it to stand at room temperature for 12 to 24 h, washing the solution after standing with methanol by suction filtration, and finally drying at 40 to 60 °C to prepare ZIF-67.

[0015] Preferably, in step (2), the preparation method of the carbonized ZIF-67 specifically includes the following steps: prepare two crucibles, place the crucible containing 2g of dicyandiamide first, and then place the crucible containing 0.1g of ZIF-67 in the crucible according to the gas flow direction of the tube furnace. Both crucibles are open, and N2 is introduced as a protective gas. The temperature is raised to 550-600℃ at a rate of 2-5℃ / min and held for 1-4h to prepare carbonized ZIF-67.

[0016] Preferably, the ZIF-67 and the alloy powder from step (1) are placed in a ball mill jar, filled with argon gas for protection, and ball milled for 0.5 to 1.5 hours.

[0017] Preferably, after thorough grinding in the mortar, the material is placed in a ball mill jar, and ball milling is carried out in an argon atmosphere with a pressure of 0.05-0.15 MPa, a ball-to-material mass ratio of (25-40):1, a ball milling speed of 300-500 r / min, a ball milling time of 0.5-1.5 h, and intermittent ball milling with a 10-20 min interval between each ball milling session.

[0018] Thirdly, this disclosure provides an application of a negative electrode material for new energy batteries. The alloy powder is pressed into sheets and applied to the battery, specifically including the following steps: The electrochemical performance test of the hydrogen storage alloy electrode is carried out on a LAND battery testing system in constant current charge-discharge mode, with a current density of 60 mA / g and a cutoff voltage of 0.8 V; The battery is placed in a 6 mol / L KOH solution and left to stand for 12-24 h, then placed in a water bath (30°C), charged for 4-6 h, discharged, and cycled at 10-min intervals until 100 cycles are completed, and the discharge capacity is recorded; For rate performance, the battery is first activated at a charge and discharge current density of 60 mA / g, then charged at a charge density of 60 mA / g, left to stand for 10 min, and then discharged sequentially to 0.8 V at a discharge current density of 60-600 mA / g, and the rate performance is determined by comparing the obtained discharge capacity.

[0019] In summary, this application has the following beneficial effects:

[0020] 1. Compared with ordinary hydrogen storage materials, the hydrogen storage composite material with added organometallic framework in this application has better performance than other hydrogen storage materials. At room temperature, the maximum discharge capacity can still reach more than 200mAh / g at a current density of 60mA / g.

[0021] 2. The negative electrode material prepared in this application has a lifespan of more than 100 cycles at room temperature;

[0022] 3. The negative electrode material prepared in this application can still maintain a rate performance of over 80% at a discharge current density of 600 mA / g at room temperature.

[0023] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of protection of this disclosure. Attached Figure Description

[0024] 1. Figure 1 ZIF-67 / La is obtained through Embodiment 1 of this application. 10 Ce5Fe5Ni 70 XRD pattern of Mn6B2Al2 composite material;

[0025] 2. Figure 2 ZIF-67 / La is obtained through Embodiment 1 of this application. 10 Ce5Fe5Ni 70 Cyclic curves of Mn6B2Al2 composite material at 303K;

[0026] 3. Figure 3 ZIF-67 / La is obtained through Embodiment 1 of this application. 10 Ce5Fe5Ni 70 Rate discharge curve of Mn6B2Al2 composite material at 303K. Detailed Implementation

[0027] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.

[0028] Example

[0029] Example 1

[0030] (1) Preparation of alloy powder

[0031] Metals such as La, Ce, B, Fe, and Ni, in appropriate proportions, are placed in the melting furnace in ascending order of melting point. Boron is added as an intermediate alloy, FeB, to ensure uniform alloy composition during melting. The metal is then melted and turned twice at high temperature to produce La.10 Ce5Fe5Ni 70 Mn6B2Al2 alloy ingots. The smelted alloy ingots are mechanically crushed and ground into alloy powder using an agate mortar and pestle.

[0032] (2) Preparation of ZIF-67 carbonized material (metal-organic framework material)

[0033] (i) First, weigh 4 mmol of cobalt nitrate and 16 mmol of 2-methylimidazole, and place them separately in beakers containing 25 ml of methanol. Stir and sonicate for 15 min. Slowly pour the sonicated cobalt nitrate solution into the 2-methylimidazole solution, continue stirring for 10 min, and let stand at 25 °C for 24 h. After standing, wash the solution with methanol by vacuum filtration, and finally dry it at 50 °C to prepare ZIF-67.

[0034] (ii) Prepare two crucibles. According to the gas flow direction of the tube furnace, first place the crucible containing 2g of dicyandiamide, and then place the crucible containing 0.1g of ZIF-67. Both crucibles are open, and N2 is introduced as a protective gas. The temperature is raised to 600℃ at 2℃ / min and held for 1h to prepare carbonized ZIF-67.

[0035] (3)ZIF-67 / La 10 Ce5Fe5Ni 70 Preparation of Mn6B2Al2 composite material

[0036] A certain amount of ZIF-67 and alloy powder (ZIF-67 mass: alloy mass = 1:95) were placed in a ball mill jar and ball-milled for 0.5 hours, with argon gas filling for protection, thus obtaining a composite hydrogen storage material.

[0037] (4) Test methods

[0038] The degradation and rate performance of the materials were tested using a LAND battery tester. 0.15g of the composite hydrogen storage material was uniformly mixed with 0.75g of carbonyl nickel, placed in a 10mm diameter mold, and pressed into small circular sheets with a thickness of 1-2mm under high pressure. These sheets were then welded onto a nickel rod to serve as the negative electrode. Sintered Ni(OH)₂ / NiOOH was used as the positive electrode material. KOH solution was used as the electrolyte. The electrochemical performance of the prepared simulated battery was tested using a battery tester.

[0039] Example 2

[0040] (1) Preparation of alloy powder

[0041] According to the stoichiometric ratio of the alloy formula, La, Fe, and B metals (all with purities higher than 99.9%) were placed in the melting furnace from bottom to top in order of increasing melting point. Boron was added as an intermediate alloy FeB to ensure uniform alloy composition. The alloy was melted in an argon atmosphere in a copper crucible cooled by circulating water. To ensure uniformity, the alloy was turned over three times during melting. The melted alloy was allowed to cool naturally, removed, and then mechanically crushed and ground, and sieved through a 200-mesh sieve to prepare La-Fe-B alloy powder.

[0042] (2) Preparation of ZIF-67 carbonized material (metal-organic framework material)

[0043] (i) First, weigh 4 mmol of cobalt nitrate and 20 mmol of 2-methylimidazole, and place them separately in beakers containing 25 ml of methanol. Stir and sonicate for 15 min. Slowly pour the sonicated cobalt nitrate solution into the 2-methylimidazole solution, continue stirring for 10 min, and let stand at 25 °C for 24 h. After standing, wash the solution with methanol by vacuum filtration, and finally dry at 60 °C to prepare ZIF-67.

[0044] (ii) Prepare two crucibles. According to the gas flow direction of the tube furnace, first place the crucible containing 2g of dicyandiamide, and then place the crucible containing 0.1g of ZIF-67. Both crucibles are open, and N2 is introduced as a protective gas. The temperature is raised to 500℃ at 2℃ / min and held for 1h to prepare carbonized ZIF-67.

[0045] (3)ZIF-67 / La 10 Ce5Fe5Ni 70 Preparation of Mn6B2Al2 composite material

[0046] ZIF-67 and La-Fe-B alloy powders were placed in a ball mill jar at a mass ratio of 3:97, and ball milled for 1 hour under inert gas protection to ensure uniform mixing, thus preparing ZIF-67 / La alloy powder. 10 Ce5Fe5Ni 70 Mn6B2Al2 composite hydrogen storage alloy material.

[0047] (4) Test methods

[0048] The degradation and rate performance of the materials were tested using a LAND battery tester. 0.15g of the composite hydrogen storage material was uniformly mixed with 0.75g of carbonyl nickel, placed in a 10mm diameter mold, and pressed into small circular sheets with a thickness of 1-2mm under high pressure. These sheets were then welded onto a nickel rod to serve as the negative electrode. Sintered Ni(OH)₂ / NiOOH was used as the positive electrode material. KOH solution was used as the electrolyte. The electrochemical performance of the prepared simulated battery was tested using a battery tester.

[0049] Combined with the appendix of the present invention Figure 2 As can be seen, the hydrogen storage alloy of the composite material exhibits excellent electrochemical performance, with improved activation performance, discharge capacity and cycle stability.

[0050] Example 3

[0051] (1) Preparation of alloy powder

[0052] According to the stoichiometric ratio of the alloy formula, La, Fe, and B metals (all with purities higher than 99.9%) were placed in the melting furnace from bottom to top in order of increasing melting point. Boron was added as an intermediate alloy FeB to ensure uniform alloy composition. The alloy was melted in an argon atmosphere in a copper crucible cooled by circulating water. To ensure uniformity, the alloy was turned over three times during melting. The melted alloy was allowed to cool naturally, removed, and then mechanically crushed and ground, and sieved through a 200-mesh sieve to prepare La-Fe-B alloy powder.

[0053] (2) Preparation of ZIF-67 carbonized material (metal-organic framework material)

[0054] (i) First, weigh 4 mmol of cobalt nitrate and 25 mmol of 2-methylimidazole, and place them separately in beakers containing 25 ml of methanol. Stir and sonicate for 15 min. Slowly pour the sonicated cobalt nitrate solution into the 2-methylimidazole solution, continue stirring for 10 min, and let stand at 25 °C for 24 h. After standing, wash the solution with methanol by vacuum filtration, and finally dry at 55 °C to prepare ZIF-67.

[0055] (ii) Prepare two crucibles. According to the gas flow direction of the tube furnace, first place the crucible containing 2g of dicyandiamide, and then place the crucible containing 0.1g of ZIF-67. Both crucibles are open, and N2 is introduced as a protective gas. The temperature is raised to 400℃ at 2℃ / min and held for 1h to prepare carbonized ZIF-67.

[0056] (3)ZIF-67 / La 10 Ce5Fe5Ni 70 Preparation of Mn6B2Al2 composite material

[0057] ZIF-67 and La-Fe-B alloy powders were mixed at a mass ratio of 1:99 in a ball mill jar, under inert gas protection, and ball-milled for 1.5 hours to ensure uniform mixing, thus producing ZIF-67 / La alloy powder. 10 Ce5Fe5Ni 70 Mn6B2Al2 composite hydrogen storage alloy material.

[0058] (4) Test methods

[0059] The degradation and rate performance of the materials were tested using a LAND battery tester. 0.15g of the composite hydrogen storage material was uniformly mixed with 0.75g of carbonyl nickel, placed in a 10mm diameter mold, and pressed into small circular sheets with a thickness of 1-2mm under high pressure. These sheets were then welded onto a nickel rod to serve as the negative electrode. Sintered Ni(OH)₂ / NiOOH was used as the positive electrode material. KOH solution was used as the electrolyte. The electrochemical performance of the prepared simulated battery was tested using a battery tester.

[0060] Combined with the appendix of the present invention Figure 2 As can be seen, the hydrogen storage alloy with added ZIF-67 composite material exhibits excellent electrochemical performance, and the activation performance, discharge capacity and cycle stability of the composite material are all improved.

[0061] The above description is merely an exemplary embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A negative electrode material for new energy batteries, characterized in that, The negative electrode material is a solid-state hydrogen storage alloy composite material, and the chemical formula of the composite material is ZIF-67 / La. 10 Ce5Fe5Ni 70 Mn6B2Al2.

2. The method for preparing a new energy battery anode material according to claim 1, characterized in that, Includes the following steps: (1) Preparation of La 10 Ce5Fe5Ni 70 Mn6B2Al2 alloy powder: according to La 10 Ce5Fe5Ni 70 The mass ratio of Mn6B2Al2 alloy is determined by placing each pure metal into a melting furnace for melting, melting into alloy ingots with uniform composition, and then mechanically crushing and grinding the alloy ingots into powder with a mesh size of less than 200. (2) Preparation of carbonized ZIF-67 metal-organic framework material: weigh cobalt nitrate and 2-methylimidazole, and prepare ZIF-67 after treatment. Place dicyandiamine and ZIF-67 according to the gas flow direction of the tube furnace. Both crucibles are open and N2 is introduced as a protective gas. After high temperature treatment, carbonized ZIF-67 is prepared. (3) Preparation of ZIF-67 / La 10 Ce5Fe5Ni 70 Mn6B2Al2 composite hydrogen storage alloy material: The carbonized ZIF-67 and the La... 10 Ce5Fe5Ni 70 The mass ratio of Mn6B2Al2 alloy powder is 1~5:99~95. The ZIF-67 and the alloy powder from step (1) are simultaneously placed in a mortar and ground thoroughly to produce the ZIF-67 / La alloy. 10 Ce5Fe5Ni 70 Mn6B2Al2 composite hydrogen storage alloy material.

3. The method for preparing a new energy battery anode material according to claim 2, characterized in that, In step (1), the pure metals are placed into the smelting furnace in order of increasing melting point from bottom to top and smelted using conventional methods.

4. The method for preparing a new energy battery anode material according to claim 2, characterized in that, In step (2), the treatment method for cobalt nitrate and 2-methylimidazole is as follows: after sonication for 15-25 minutes, they are mixed and stirred, left to stand at room temperature for 12-24 hours, the settled solution is washed with methanol by vacuum filtration, and finally dried.

5. The method for preparing a new energy battery anode material according to claim 2, characterized in that, In step (2), the high-temperature treatment includes raising the temperature to 550-600℃ at a rate of 2-5℃ / min and holding it at that temperature for 1-4 hours.

6. The method for preparing a new energy battery anode material according to claim 2, characterized in that, In step (2), the preparation method of ZIF-67 is specifically... The process includes the following steps: Weigh cobalt nitrate and 2-methylimidazole in a molar ratio of 1:4~10, and place the cobalt nitrate and 2-methylimidazole into a beaker containing 25 ml of methanol and sonicate for 15~25 min; Slowly pour the sonicated cobalt nitrate solution into the 2-methylimidazole solution, continue stirring for 10~20 min, let it stand at room temperature for 12~24 h, wash the solution after standing with methanol by suction filtration, and finally dry it at 40~60℃ to prepare ZIF-67.

7. The method for preparing a new energy battery negative electrode material according to claim 2, characterized in that, In step (2), the preparation method of the carbonized ZIF-67 specifically includes the following steps: Prepare two crucibles, and according to the gas flow direction of the tube furnace, first place the crucible containing 2g of dicyandiamide, and then place the crucible containing 0.08~0.16g of ZIF-67. Both crucibles are open, and N2 is introduced as a protective gas. The temperature is raised to 550~600℃ at a rate of 2~5℃ / min, and held for 1~4 h to prepare carbonized ZIF-67.

8. The method for preparing a new energy battery negative electrode material according to claim 2, characterized in that, After grinding, the carbonized ZIF-67 and the alloy powder from step (1) are placed in a ball mill jar, filled with argon gas for protection, and ball milled for 0.5~1.5h.

9. The method for preparing a new energy battery anode material according to claim 8, characterized in that, After thorough grinding in the mortar, the material is placed in a ball mill jar. The ball milling is carried out in an argon atmosphere with a pressure of 0.05–0.15 MPa, a ball-to-material mass ratio of (25–40):1, a milling speed of 300–500 r / min, and a milling time of 0.5–1.5 h. For intermittent ball milling, each milling session lasts 10–20 min, followed by an interval of 10–20 min.

10. The application of the new energy battery anode material obtained by any one of claims 2-9, characterized in that, The alloy powder is pressed into sheets and applied to the battery, specifically including the following steps: The electrochemical performance of the hydrogen storage alloy electrode is tested on a LAND battery testing system in constant current charge-discharge mode, with a charging current density of 60 mA / g and a discharge cutoff voltage of 0.8~1.0 V; The battery is placed in a 6 mol / L KOH solution and left to stand for 12~24 h, then placed in a water bath at 30℃, charged for 4-6 h, discharged, and cycled at 10 min intervals until 100 cycles are completed, and the discharge capacity is recorded; For rate performance, the battery is first activated at a charge and discharge current density of 60 mA / g, then charged at a charging current density of 60 mA / g, left to stand for 10 min, and then discharged sequentially to 0.8 V at a discharge current density of 60~600 mA / g, and the rate performance is determined by comparing the obtained discharge capacity.

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