A method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries

Abstract

The present invention relates to the technical field of hydrogen fuel cell anodes, and specifically to a method for preparing hydrogen fuel cell anodes using waste manganese-based sodium ion batteries. The preparation method comprises the following steps: discharging the waste manganese-based sodium ion batteries in a NaCl solution to obtain electroless manganese-based sodium ion batteries, crushing the batteries to obtain manganese-based sodium ion battery slag, blowing the slag to obtain a manganese-based sodium ion battery slag free of diaphragms and plastic coatings, and immersing the slag in an organic solvent; completely separating the negative electrode waste carbon from the current collector under ultrasound assistance to obtain a clarified solution; preparing graphene oxide from the negative electrode waste carbon using the Hummers method; adjusting the pH value of the clarified solution, filtering to obtain a sodium carbonate residue and a manganese ion-containing filtrate; mixing the graphene oxide with the filtrate, stirring, heating, and drying to obtain a manganese-doped graphene catalyst, which is then used as a hydrogen fuel cell anode. The present invention enables controlled and complete recovery of positive and negative electrode waste; uses inexpensive and easily controlled materials; and produces a manganese-doped graphene catalyst with excellent application effects.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen fuel cell positive electrodes, and in particular to a method for preparing a hydrogen fuel cell positive electrode by utilizing waste manganese-based sodium ion batteries. Background Art

[0002] Sodium-ion batteries offer distinct advantages, including high sodium abundance, uniform distribution, and low cost. Furthermore, due to their high specific capacity and exceptional safety, and their structural similarity to lithium-ion batteries, their production can largely follow the established manufacturing routes for lithium-ion batteries, effectively reducing production costs. Their replacement of lead-acid batteries and low-end lithium-ion batteries for powering low-speed mobile vehicles has become a major trend. However, this also means that a large number of retired sodium-ion batteries will be produced in the near future. Sodium-ion batteries are rich in carbon materials and heavy metals. For example, the most typical Prussian white sodium-ion battery contains a large amount of heavy metal manganese in its positive electrode. Improper handling can lead to serious environmental pollution and resource waste. Therefore, the development of technical solutions for the recycling and functional utilization of sodium-ion batteries is extremely urgent.

[0003] In addition, the value of manganese-containing waste in the positive electrode and carbon waste in the negative electrode of sodium-ion batteries is relatively low, resulting in low recycling cost-effectiveness and weak corporate willingness to recycle. If these materials are not handled properly, it will lead to resource waste and environmental pollution. Therefore, using waste manganese-based sodium-ion batteries as raw materials, the development of universal and reliable recycling and resource utilization technologies can bring rich economic benefits while alleviating and avoiding environmental pollution problems. As a new type of high-performance energy storage device, the smooth operation of hydrogen fuel cells is inseparable from the role of efficient catalytic positive electrodes. Properly treated Mn-doped graphene is an ideal positive electrode catalyst that can effectively promote the oxygen reduction process in fuel cells, thereby promoting the improvement of fuel cell performance.

[0004] In view of the above situation, using waste manganese-based sodium ion batteries as raw materials, developing universal and reliable recycling and resource utilization technologies to prepare low-value and toxic waste into Mn-doped graphene for hydrogen fuel cells can bring economic benefits while alleviating and avoiding the environmental pollution caused by waste sodium ion batteries. Summary of the Invention

[0005] To address the above problems, a method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries is provided. Through the preparation method, the toxic heavy metal ions Mn contained in the sodium ion battery cathode and the negative electrode waste carbon are prepared into Mn-doped graphene, and the graphene is applied in the hydrogen fuel cell cathode.

[0006] To solve the problems of the prior art, the present invention provides a method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries, the preparation method comprising the following steps:

[0007] Step S1: placing a waste manganese-based sodium ion battery in a NaCl solution for discharge to obtain an electroless manganese-based sodium ion battery; Step S2: crushing the electroless manganese-based sodium ion battery to obtain a manganese-based sodium ion battery slag; Step S3: blowing the manganese-based sodium ion battery slag to obtain a manganese-based sodium ion battery slag free of a diaphragm and a plastic skin; Step S4: immersing the manganese-based sodium ion battery slag free of a diaphragm and a plastic skin in an organic solvent, and completely separating the negative electrode waste carbon from the current collector under the assistance of ultrasound. , obtaining a clear solution; step S5: preparing graphene oxide from the negative electrode waste carbon in step S4 by using the Hummers method; step S6: adjusting the pH value of the clear solution in step S4, filtering to obtain sodium carbonate residue and a filtrate containing manganese ions; step S7: mixing the graphene oxide in step S5 and the filtrate in step S6 under stirring conditions, heating and drying to obtain a manganese-doped graphene catalyst; step S8: using the manganese-doped graphene catalyst in step S7 for the positive electrode of a hydrogen fuel cell.

[0008] Preferably, the concentration of the NaCl solution in step S1 is 1M, 1.25M or 1.5M.

[0009] Preferably, the crushing process in step S2 is crushing by a crusher, manual crushing or frozen crushing.

[0010] Preferably, the blowing process in step S3 is a high-speed airflow field, a medium-speed airflow field, or a low-speed airflow field.

[0011] Preferably, the organic solvent in step S4 is N-methylpyrrolidone (NMP) or dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF).

[0012] Preferably, the waste carbon concentration used in the Hummers method in step S5 is 1.0 g / L, 1.5 g / L, or 2.0 g / L.

[0013] Preferably, the pH value in step S6 is in the range of 11±0.5.

[0014] Preferably, in step S6, the pH value of the clarified solution is adjusted using concentrated ammonia water, sodium hydroxide, or sodium bicarbonate.

[0015] Preferably, the concentration of graphene oxide in the filtrate in step S7 is 1.2 g / L or 1.4 g / L or 1.6 g / L.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention fully utilizes the positive and negative electrode waste materials of waste sodium ion batteries and converts them into high-efficiency catalysts as a whole, thereby achieving controllable and full recovery of the positive and negative electrode waste materials.

[0018] 2. The solvents, dispersants and precipitants used in the preparation of the present invention are cheap and readily available, the processing conditions are easy to control, the equipment is simple and easy to operate, and the preparation process has good continuity, which makes it possible to achieve large-scale production.

[0019] 3. The manganese-doped graphene catalyst prepared by the present invention has high discharge voltage, high discharge capacity and good cycle performance when applied to hydrogen fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a preparation flow chart of a method for preparing a positive electrode of a hydrogen fuel cell using waste manganese-based sodium ion batteries.

[0021] Figure 2 This is a scanning electron microscope image of a manganese-doped graphene catalyst.

[0022] Figure 3 This is a transmission electron microscopy image of a manganese-doped graphene catalyst.

[0023] Figure 4 This is the X-ray diffraction pattern of manganese-doped graphene catalyst. DETAILED DESCRIPTION

[0024] In order to further understand the features, technical means, specific objectives and functions achieved by the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Reference Figure 1-Figure 4 A method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries, the preparation method comprising the following steps:

[0026] Step S1: placing the waste manganese-based sodium ion battery in a NaCl solution for discharge to obtain an electroless manganese-based sodium ion battery;

[0027] Step S2: crushing the electroless manganese-based sodium ion battery to obtain manganese-based sodium ion battery slag;

[0028] Step S3: blowing the manganese-based sodium ion battery slag to obtain a manganese-based sodium ion battery slag free of a diaphragm and a plastic skin;

[0029] Step S4: soaking the manganese-based sodium ion battery slag without the separator and the plastic skin in an organic solvent, and completely separating the negative electrode waste carbon from the current collector under the assistance of ultrasound to obtain a clarified solution;

[0030] Step S5: preparing graphene oxide from the negative electrode waste carbon in step S4 using the Hummers method;

[0031] Step S6: adjusting the pH value of the clarified solution in step S4, and filtering to obtain a sodium carbonate residue and a filtrate containing manganese ions;

[0032] Step S7: mixing the graphene oxide in step S5 and the filtrate in step S6 with stirring, heating and drying to obtain a manganese-doped graphene catalyst;

[0033] Step S8: Using the manganese-doped graphene catalyst in step S7 as a hydrogen fuel cell cathode.

[0034] Reference Figure 1 : The concentration of the NaCl solution in step S1 is 1M, 1.25M or 1.5M.

[0035] Reference Figure 1 : The crushing process in step S2 is crusher crushing, manual crushing or frozen crushing.

[0036] Reference Figure 1 : The blowing process in step S3 is a high-speed airflow field, a medium-speed airflow field, or a low-speed airflow field.

[0037] Reference Figure 1 : The organic solvent in step S4 is N-methylpyrrolidone (NMP) or dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF).

[0038] Reference Figure 1 : The waste carbon concentration used in the Hummers method in step S5 is 1.0 g / L, 1.5 g / L, or 2.0 g / L.

[0039] Reference Figure 1 : The range of the pH value in step S6 is 11±0.5.

[0040] Reference Figure 1 : In step S6, the pH value of the clarified solution is adjusted using concentrated ammonia, sodium hydroxide, or sodium bicarbonate.

[0041] Reference Figure 1 : The concentration of graphene oxide in the filtrate in step S7 is 1.2 g / L, 1.4 g / L, or 1.6 g / L.

[0042] Working Principle: Used manganese-based sodium-ion batteries are physically crushed into powdery residue. Leveraging the mass differences among internal components—the positive electrode active material, negative electrode waste carbon, separator, plastic coating, current collector, and steel casing—the light-weight separator and plastic coating are separated from the heavier components—the positive and negative electrode materials, current collector, and steel casing—in an airflow field. Furthermore, the solubility differences between inorganic and organic compounds in organic solutions separate the solid and liquid components. Simultaneously, utilizing the density differences among these components, buoyancy separates the low-density waste carbon, medium-density active material, high-density steel casing, and aluminum current collector. Sodium and manganese are then separated using a precipitant. The Hummers method converts the waste carbon into graphene, significantly increasing its specific surface area. Graphene's large surface area allows for electrostatic adsorption of metal ions, allowing heavy metal manganese to be adsorbed onto the graphene surface. At high temperatures, manganese is intercalated into and within the graphene carbon layer, forming a manganese-doped graphene catalyst.

[0043] Example 1:

[0044] A method for preparing a fuel cell cathode using waste manganese-based sodium ion batteries comprises the following steps:

[0045] (1) Soak the used manganese-based sodium ion batteries in 1.0 M NaCl saline, and then dry the batteries for later use;

[0046] (2) Using a crusher to crush the waste manganese-based sodium ion battery into powder residue, separating the diaphragm and the plastic skin in a high-speed air flow field, and immersing the resulting waste in N,N-dimethylformamide, filtering the mixed waste after ultrasonic treatment for 30 minutes to separate the upper waste carbon, the middle positive electrode active material and the lower steel shell and current collector, and preparing the upper waste carbon into graphene using the 1.0 g / L Hummers method; immersing the positive electrode active material in malic acid and stirring for 12 hours, adjusting the pH value to 11.0 using concentrated ammonia water, and filtering and separating the filtrate and manganese ion-containing residue; stirring the graphene and manganese ion-containing filtrate to a concentration of 5 mg / mL, and heating and drying at 100°C for 18 hours;

[0047] (3) Assembling manganese-doped graphene as a catalytic material to form a hydrogen fuel cell;

[0048] Comparative Example 1:

[0049] (1) Soak the used manganese-based sodium ion batteries in 1.0 M NaCl saline, and then dry the batteries for later use;

[0050] (2) Using a crusher to crush the waste manganese-based sodium ion battery into powder residue, separating the diaphragm and the plastic skin in a high-speed air flow field, and immersing the resulting waste in N-methylpyrrolidone, filtering the mixed waste after ultrasonic treatment for 30 minutes to separate the upper waste carbon, the middle positive electrode active material and the lower steel shell and current collector, and preparing the upper waste carbon into graphene using the 1.0 g / L Hummers method; immersing the positive electrode active material in citric acid and stirring for 12 hours, adjusting the pH value to 11.0 using concentrated ammonia water, filtering and separating the filtrate and the manganese ion-containing residue; stirring the graphene and the manganese ion-containing filtrate to a concentration of 5 mg / mL, and heating and drying at 100°C for 18 hours;

[0051] (3) Assembling manganese-doped graphene as a catalytic material to form a hydrogen fuel cell;

[0052] The comparison results show that due to the better solubility of N-methylpyrrolidone in the electrolyte, the purity of the active material and waste carbon in the subsequent waste is higher. The manganese-doped graphene prepared in Comparative Example 1 has higher purity; a larger specific surface area of ​​287m2 / g; better migration and anchoring effects of Mn atoms; and assembled into a fuel cell with a higher discharge capacity at a current density of 100mA / g.

[0053] Example 2:

[0054] (1) Soak the used manganese-based sodium ion batteries in 1.25M NaCl saline, and then dry the batteries for later use;

[0055] (2) Using freeze crushing to crush the waste manganese-based sodium ion battery into powder residue, separating the diaphragm and the plastic skin in a high-speed air flow field, and immersing the resulting waste in N-methylpyrrolidone. After ultrasonic treatment for 30 minutes, the mixed waste was filtered to separate the upper waste carbon, the middle positive electrode active material, and the lower steel shell and current collector. The upper waste carbon was prepared into graphene using the 1.5 g / L Hummers method; the positive electrode active material was immersed in malic acid and stirred for 12 hours, and the pH value was adjusted to 11.0 using concentrated ammonia water. The filtrate and the manganese ion-containing residue were filtered and separated; the graphene and the manganese ion-containing filtrate were evenly stirred at a concentration of 5 mg / mL and heated and dried at 100°C for 18 hours;

[0056] (3) Assembling manganese-doped graphene as a catalytic material to form a hydrogen fuel cell;

[0057] Comparative Example 2:

[0058] (1) Soak the used manganese-based sodium ion batteries in 1.25M NaCl saline, and then dry the batteries for later use;

[0059] (2) Using freeze crushing to crush the waste manganese-based sodium ion battery into powder residue, separating the diaphragm and the plastic skin in a medium-speed air flow field, and immersing the obtained waste in N-methylpyrrolidone. After ultrasonic treatment for 60 minutes, the mixed waste is filtered to separate the upper waste carbon, the middle positive electrode active material and the lower steel shell and the current collector. The upper waste carbon is prepared into graphene using the 1.5 g / L Hummers method; the positive electrode active material is immersed in malic acid and stirred for 12 hours, and the pH value is adjusted to 11.0 using concentrated ammonia water. The filtrate and the manganese ion-containing residue are filtered and separated; the graphene and the manganese ion-containing filtrate are evenly stirred at a concentration of 5 mg / mL and heated and dried at 100°C for 18 hours;

[0060] (3) Assembling manganese-doped graphene as a catalytic material to form a hydrogen fuel cell;

[0061] The comparison results show that the medium-speed air flow field can meet the separation of different components in the waste and reduce the loss of powder residue; at the same time, due to the increase in ultrasonic time, the positive and negative electrode materials are more completely detached from the collector. The waste prepared in Comparative Example 1 is of higher quality and more manganese-doped graphene can be prepared; the assembled fuel cell has a higher discharge capacity at a current density of 100 mA / g.

[0062] Example 3:

[0063] (1) Soak the used manganese-based sodium ion batteries in 1.5M NaCl saline, and then dry the batteries for later use;

[0064] (2) Mechanically crushing the waste manganese-based sodium ion battery into powder residue, separating the diaphragm and the plastic skin in a medium-speed air flow field, and immersing the resulting waste in N,N-dimethylformamide. After ultrasonic treatment for 60 minutes, the mixed waste was filtered to separate the upper waste carbon, the middle positive electrode active material, and the lower steel shell and current collector. The upper waste carbon was prepared into graphene using a 2.0 g / L Hummers method; the positive electrode active material was immersed in citric acid and stirred for 12 hours, and the pH value was adjusted to 11.5 using concentrated ammonia water. The filtrate and the manganese ion-containing residue were filtered and separated; the graphene and the manganese ion-containing filtrate were evenly stirred at a concentration of 5 mg / mL, and heated and dried at 120°C for 24 hours;

[0065] (3) Assembling manganese-doped graphene as a catalytic material to form a hydrogen fuel cell;

[0066] Comparative Example 3:

[0067] (1) Soak the used manganese-based sodium ion batteries in 1.5M NaCl saline, and then dry the batteries for later use;

[0068] (2) Mechanically crushing the waste manganese-based sodium ion battery into powder residue, separating the diaphragm and the plastic skin in a low-speed air flow field, and immersing the resulting waste in dimethyl sulfoxide. After ultrasonic treatment for 60 minutes, the mixed waste was filtered to separate the upper waste carbon, the middle positive electrode active material, and the lower steel shell and current collector. The upper waste carbon was prepared into graphene using the 2.0 g / L Hummers method; the positive electrode active material was immersed in citric acid and stirred for 12 hours, and the pH value was adjusted to 11.5 using ammonium bicarbonate. The filtrate and the manganese ion-containing residue were filtered and separated; the graphene and the manganese ion-containing filtrate were evenly stirred at a concentration of 5 mg / mL, and heated and dried at 120°C for 24 hours;

[0069] (3) Assembling manganese-doped graphene as a catalytic material to form a hydrogen fuel cell;

[0070] The comparison results show that the low-speed airflow field is not enough to provide sufficient power to separate the lightweight diaphragm and plastic skin from the mixed powder residue, and dimethyl sulfoxide has a better solubility in the electrolyte.

[0071] The above embodiments merely represent one or more embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries, characterized in that: The preparation method comprises the following steps: Step S1: placing the waste manganese-based sodium ion battery in a NaCl solution for discharge to obtain an electroless manganese-based sodium ion battery; Step S2: crushing the electroless manganese-based sodium ion battery to obtain manganese-based sodium ion battery slag; Step S3: blowing the manganese-based sodium ion battery slag to obtain a manganese-based sodium ion battery slag free of a diaphragm and a plastic skin; Step S4: soaking the manganese-based sodium ion battery slag without the separator and the plastic skin in an organic solvent, and completely separating the negative electrode waste carbon from the current collector under the assistance of ultrasound to obtain a clarified solution; Step S5: preparing graphene oxide from the negative electrode waste carbon in step S4 using the Hummers method; Step S6: adjusting the pH value of the clarified solution in step S4, and filtering to obtain a sodium carbonate residue and a filtrate containing manganese ions; Step S7: mixing the graphene oxide in step S5 and the filtrate in step S6 with stirring, heating and drying to obtain a manganese-doped graphene catalyst; Step S8: Using the manganese-doped graphene catalyst in step S7 as a hydrogen fuel cell cathode.

2. The method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries according to claim 1, characterized in that: The concentration of the NaCl solution in step S1 is 1M, 1.25M or 1.5M.

3. The method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries according to claim 1, characterized in that: The crushing process in step S2 is crusher crushing, manual crushing or freeze crushing.

4. The method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries according to claim 1, characterized in that: The blowing process in step S3 is a high-speed airflow field, a medium-speed airflow field, or a low-speed airflow field.

5. The method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries according to claim 1, characterized in that: The organic solvent in step S4 is N-methylpyrrolidone (NMP) or dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF).

6. The method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries according to claim 1, characterized in that: The waste carbon concentration used in the Hummers method in step S5 is 1.0 g / L, 1.5 g / L, or 2.0 g / L.

7. The method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries according to claim 1, characterized in that: The pH value in step S6 is in the range of 11±0.

5.

8. The method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries according to claim 1, characterized in that: In step S6, the pH value of the clarified solution is adjusted using concentrated ammonia water, sodium hydroxide, or sodium bicarbonate.

9. The method for preparing a hydrogen fuel cell cathode using waste manganese-based sodium ion batteries according to claim 1, characterized in that: The concentration of graphene oxide in the filtrate in step S7 is 1.2 g / L, 1.4 g / L, or 1.6 g / L.

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