阅读说明：本技术 一种利用废旧磷酸铁锂电池正极材料制备的碳基电催化剂及其制备方法和应用 (Carbon-based electrocatalyst prepared from waste lithium iron phosphate battery positive electrode material and preparation method and application thereof ) 是由 马兆玲 刘葵 申彦豪 李庆余 王红强 蔡业政 于 2021-08-16 设计创作，主要内容包括：本发明公开了一种利用废旧磷酸铁锂电池正极材料制备的碳基电催化剂及其制备方法和应用,所述制备方法,包括以下步骤：将废旧磷酸铁锂电池正极片于保护气氛下热处理,收集废旧磷酸铁锂电池正极材料并研磨获得废旧正极粉末,将废旧正极粉末加入碱溶液中处理,固液分离获得粉末A,将粉末A加入酸溶液中,反应,固液分离获得粉末B,再将粉末B与氮源混合,煅烧,即得碳基电催化剂。本发明采用废旧磷酸铁锂电池的正极材料为原料,使制备催化剂的成本降低,保护环境的同时提高了资源利用率,既有社会效益又有经济效益。本发明方法工艺简单,操作容易,合成的催化剂具有三维网络结构和较多的催化活性位点,可广泛应用于燃料电池领域。(The invention discloses a carbon-based electrocatalyst prepared by utilizing a waste lithium iron phosphate battery anode material, and a preparation method and application thereof, wherein the preparation method comprises the following steps: the method comprises the steps of carrying out heat treatment on the waste lithium iron phosphate battery positive plate under a protective atmosphere, collecting the waste lithium iron phosphate battery positive plate material, grinding the waste lithium iron phosphate battery positive plate material to obtain waste positive powder, adding the waste positive powder into an alkali solution for treatment, carrying out solid-liquid separation to obtain powder A, adding the powder A into an acid solution for reaction, carrying out solid-liquid separation to obtain powder B, mixing the powder B with a nitrogen source, and calcining to obtain the carbon-based electrocatalyst. The invention adopts the anode material of the waste lithium iron phosphate battery as the raw material, reduces the cost for preparing the catalyst, protects the environment, improves the resource utilization rate, and has social benefit and economic benefit. The method has simple process and easy operation, and the synthesized catalyst has a three-dimensional network structure and more catalytic active sites and can be widely applied to the field of fuel cells.)

1. A preparation method for preparing a carbon-based electrocatalyst by using a waste lithium iron phosphate battery positive electrode material is characterized by comprising the following steps of: the method comprises the following steps:

the method comprises the steps of carrying out heat treatment on the waste lithium iron phosphate battery positive plate under a protective atmosphere, collecting the waste lithium iron phosphate battery positive plate material, grinding the waste lithium iron phosphate battery positive plate material to obtain waste positive powder, adding the waste positive powder into an alkali solution for treatment, carrying out solid-liquid separation to obtain powder A, adding the powder A into an acid solution for reaction, carrying out solid-liquid separation to obtain powder B, mixing the powder B with a nitrogen source, and calcining to obtain the carbon-based electrocatalyst.

2. The preparation method of the carbon-based electrocatalyst prepared by using the anode material of the waste lithium iron phosphate battery according to claim 1, is characterized in that: the method comprises the steps of discharging the waste lithium iron phosphate batteries in a NaCl solution for 12-24 hours, taking out, cutting and disassembling to obtain the waste lithium iron phosphate battery positive plates, soaking the waste lithium iron phosphate batteries in absolute ethyl alcohol, washing and drying for later use, wherein the mass fraction of the NaCl solution is 5-10%.

3. The method for preparing the carbon-based electrocatalyst by using the anode material of the waste lithium iron phosphate battery according to claim 1, is characterized in that: the temperature of the heat treatment is 300-600 ℃.

4. The method for preparing the carbon-based electrocatalyst by using the anode material of the waste lithium iron phosphate battery according to claim 1, is characterized in that: the alkali solution is selected from one of sodium hydroxide solution or potassium hydroxide solution, and the concentration of the alkali solution is 2-6 mol/L.

5. The method for preparing the carbon-based electrocatalyst by using the anode material of the waste lithium iron phosphate battery according to claim 1, is characterized in that: the acid solution is selected from one of a sulfuric acid solution, a hydrochloric acid solution or a nitric acid solution, and the concentration of the acid solution is 2-6 mol/L.

6. The method for preparing the carbon-based electrocatalyst by using the anode material of the waste lithium iron phosphate battery according to claim 1, is characterized in that:

the reaction temperature is 50-80 ℃, the reaction time is 3-12h, the reaction is carried out under stirring, and the stirring speed is 500-3000 r/min.

7. The method for preparing the carbon-based electrocatalyst by using the anode material of the waste lithium iron phosphate battery according to claim 1, is characterized in that: the nitrogen source is at least one selected from melamine, urea, ammonia gas, polyaniline, dopamine and polypyrrole; the mass ratio of the powder B to the nitrogen source is 1: 5-7.

8. The method for preparing the carbon-based electrocatalyst by using the anode material of the waste lithium iron phosphate battery according to claim 1, is characterized in that: the calcining temperature is 600-1000 ℃, the calcining time is 1-2h, and the calcining temperature rise rate is 2-10 ℃/min.

9. The carbon-based electrocatalyst prepared according to the preparation method of any one of claims 1 to 8, wherein: the carbon-based electrocatalyst consists of a three-dimensional network carbon skeleton, nitrogen atoms and metal particles or metal oxide particles coated by carbon, wherein the metal in the metal particles is selected from at least one of Al, Fe, Ni, Co and Mn, and the metal oxide in the metal oxide particles is selected from Al₂O₃、Fe₂O₃At least one of (1).

10. Use of a carbon-based electrocatalyst prepared according to the preparation method of any one of claims 1 to 8, characterized in that: applying the carbon-based electrocatalyst to a fuel cell.

Technical Field

The invention belongs to the technical field of electrocatalyst preparation, and particularly relates to a carbon-based electrocatalyst prepared from a waste lithium iron phosphate battery positive electrode material, and a preparation method and application thereof.

Background

With the development of science and technology, lithium ion batteries are increasingly widely used in production and life due to the excellent performances of long cycle life, small volume, high energy density, wide application temperature range, good safety performance and the like, wherein lithium ion batteries using lithium iron phosphate as a positive material occupy a significant position, but inevitably generate a large amount of waste batteries, if the lithium ion batteries are randomly discarded, the environment is inestimable to be polluted, and finally the life health of the lithium ion batteries is damaged, so that the recycling of the waste lithium ion batteries is of great importance.

Waste LiFePO₄The battery is discharged and disassembled, components such as a battery shell, a negative electrode material, a positive electrode material, a diaphragm and the like are disassembled and separated, and then the components are respectively recovered. The positive electrode material is subjected to heat treatment, alkaline leaching or organic solvent method to separate active substances, and valuable metals in the positive electrode material are recovered by high-temperature direct regeneration or wet process. The wet recovery technology is mature, the pretreatment requirement on the waste battery is low, and high metal recovery rate can be realized, so that a high-purity precursor material is obtained, the equipment and the technology are easy to realize industrial application, and the method is expected to become an industrial technology for recovering the waste lithium iron phosphate battery in the future.

The platinum-based catalyst is a noble metal catalyst with the best performance in the oxygen reduction reaction, but the platinum resource is limited, the price is high, and the migration and agglomeration of platinum on the surface of a carbon carrier reduce the stability, so that the development of a non-noble metal catalyst with low cost, high catalytic activity and durability becomes a hotspot. Among the numerous non-noble metal catalysts, heteroatom-doped carbon-based catalysts are promising. Many studies have been conducted to introduce heteroatoms and defects into a specific carbon source to improve catalytic activity, but the doping position and amount are uncontrollable and the activity is uneven, so that a carbon-based material with stable doping is sought.

Disclosure of Invention

Aiming at the defects of the prior art, the first purpose of the invention is to provide a preparation method for preparing a carbon-based electrocatalyst (carbon-based oxygen reduction catalyst) by using a positive electrode material of a waste lithium iron phosphate battery, which has the advantages of simplicity, low cost and good economic benefit.

The second purpose of the invention is to provide the carbon-based electrocatalyst with excellent catalytic performance prepared by the preparation method.

The third purpose of the invention is to provide the application of the carbon-based electrocatalyst prepared by the preparation method.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention relates to a preparation method for preparing a carbon-based electrocatalyst by using a waste lithium iron phosphate battery anode material, which comprises the following steps of:

the method comprises the steps of carrying out heat treatment on the waste lithium iron phosphate battery positive plate under a protective atmosphere, collecting the waste lithium iron phosphate battery positive plate material, grinding the waste lithium iron phosphate battery positive plate material to obtain waste positive powder, adding the waste positive powder into an alkali solution for treatment, carrying out solid-liquid separation to obtain powder A, adding the powder A into an acid solution for reaction, carrying out solid-liquid separation to obtain powder B, mixing the powder B with a nitrogen source, and calcining to obtain the carbon-based electrocatalyst.

The preparation method takes the waste lithium iron phosphate battery positive plate as a raw material, and the conductive agent and the binder in the lithium ion battery are doped with metal when ions are embedded and removed through repeated charging and discharging of the lithium ion battery; in the process of recycling the waste lithium iron phosphate battery positive plate, the waste lithium iron phosphate battery positive plate is soaked in a NaCl solution to discharge, so that defects are manufactured on the surface of the positive material and hetero atoms are introduced, and the prepared defects can provide more doping sites for nitrogen doping.

In the preparation process, the waste lithium iron phosphate battery positive plate is subjected to heat treatment, on one hand, the waste lithium iron phosphate battery material is dropped from an aluminum foil, on the other hand, a binder high polymer in the waste lithium iron phosphate battery positive plate forms amorphous carbon with a three-dimensional network structure through high-temperature carbonization, wherein the binder high polymer forms a spherical chain mixed network structure with a conductive agent carbon material after being carbonized as a chain polymer, and wide doping sites are provided. And then removing some aluminum scraps introduced in the waste anode powder in the falling process through alkali treatment, removing large lithium iron phosphate particles through acid treatment, simultaneously retaining transition metal particles well coated by carbon, wherein the transition metal particles can promote the catalytic performance, and simultaneously forming a three-dimensional network structure with a richer pore structure and more doping sites through alkali treatment and acid treatment in sequence, and finally performing nitrogen-doped carbon to further improve the catalytic performance of the catalyst.

According to the preferred scheme, the process for obtaining the positive plate of the waste lithium iron phosphate battery comprises the following steps: discharging the waste lithium iron phosphate battery in a NaCl solution for 12-24h, taking out, cutting and disassembling to obtain a positive plate of the waste lithium iron phosphate battery, soaking the positive plate in absolute ethyl alcohol, washing and drying for later use, wherein the mass fraction of the NaCl solution is 5-10%.

Preferably, the protective atmosphere is selected from N₂One of an atmosphere or an Ar atmosphere.

Preferably, the temperature of the heat treatment is 300-600 ℃, preferably 500-600 ℃. In the preferred temperature range, a more desirable three-dimensional network structure can be obtained.

Preferably, the alkali solution is selected from one of sodium hydroxide solution or potassium hydroxide solution, and the concentration of the alkali solution is 2-6 mol/L.

After the waste lithium iron phosphate battery positive plate is subjected to heat treatment in a protective atmosphere, a small amount of aluminum scraps can be introduced when the waste lithium iron phosphate battery material falls off from an aluminum foil, and the aluminum scraps are amphoteric oxides and can be removed only by adopting acid solution reaction treatment.

In the actual operation, the powder a is obtained by treating with an alkali solution, removing aluminum debris, washing with deionized water to pH 7, and then filtering.

Preferably, the acid solution is one selected from a sulfuric acid solution, a hydrochloric acid solution or a nitric acid solution, and the concentration of the acid solution is 2-6mol/L, preferably 4-6 mol/L.

In the invention, by controlling the concentration of the acid solution, the large particles of the lithium iron phosphate are removed by using the acid solution, and meanwhile, the transition metal particles which are well coated by carbon are remained, so that the catalytic performance is improved.

Preferably, the reaction temperature is 50-80 ℃, the reaction time is 3-12h, the reaction is carried out under stirring, and the stirring speed is 500-3000 r/min.

In the actual operation process, after the reaction is treated by the acid solution, a solid phase obtained by solid-liquid separation is washed by deionized water until the pH value is 7, and then the powder B is obtained by suction filtration separation and vacuum drying.

In a preferred scheme, the nitrogen source is at least one of melamine, urea, ammonia gas, polyaniline, dopamine and polypyrrole.

Preferably, the mass ratio of the powder to the nitrogen source is 1: 5-7.

Preferably, the calcination is carried out in a non-oxidizing atmosphere selected from the group consisting of N₂Atmosphere, Ar and H₂(Ar/H)₂) One in the atmosphere.

In a preferable scheme, the calcining temperature is 600-1000 ℃, and the calcining time is 1-2 h.

In a preferable scheme, the temperature rise rate of the calcination is 2-10 ℃/min.

The invention also provides the carbon-based electrocatalyst prepared by the preparation method.

In a preferred embodiment, the carbon-based electrocatalyst is composed of a three-dimensional network carbon skeleton, nitrogen atoms and carbon-coated metal particles or metal oxide particles, wherein the metal in the metal particles is selected from at least one of Al, Fe, Ni, Co and Mn, and the metal oxide in the metal oxide particles is selected from Al₂O₃、Fe₂O₃At least one of (1).

The invention also provides an application of the carbon-based electrocatalyst prepared by the preparation method, and the carbon-based electrocatalyst is applied to a fuel cell.

Advantageous effects

(1) The invention adopts the positive plate of the waste lithium iron phosphate battery as the raw material, greatly reduces the cost for preparing the catalyst, protects the environment, improves the resource utilization rate, and has social benefit and economic benefit.

(2) The method has the advantages of simple process, easy operation, low requirement on experimental equipment and excellent product performance, and can be widely applied to fuel cells.

(3) The carbon-based oxygen reduction catalyst prepared by using the anode of the waste lithium iron phosphate battery has high catalytic activity. The method creatively adopts the waste positive plate as the raw material, high-temperature carbonization is carried out to enable high polymer to form amorphous carbon with a three-dimensional network structure, large particles of lithium iron phosphate are removed through acid treatment, the residual transition metal particles well coated by carbon cannot be completely removed but have a promoting effect on the catalytic performance of the catalyst, and nitrogen-doped carbon further improves the catalytic performance of the catalyst; further, the initial potential of the carbon-based oxygen reduction catalyst utilizing the anode of the waste lithium iron phosphate battery is 0.838-0.925V (vs. RHE), the half-wave potential is 0.696-0.828V (vs. RHE), and the limiting current density can reach 4.83-6.20mA/cm²The catalytic performance of the catalyst is equivalent to that of a Pt/C catalyst; the performance of the aluminum air fuel battery obtained by assembly is superior to that of Pt/C.

(4) The acid solution containing metal ions can be used as a stock solution recovered by a wet method or a stock solution for preparing a metal-based catalyst, so that green chemistry is realized.

Drawings

Fig. 1 is a graph of HAADF-STEM using a carbon-based oxygen reduction catalyst for a positive electrode of a spent lithium iron phosphate battery prepared in example 1 of the present invention.

Fig. 2 is a cyclic voltammetry curve of a carbon-based oxygen reduction catalyst using a waste lithium iron phosphate battery positive electrode prepared in example 1 of the present invention in a 0.1M KOH solution of saturated oxygen and saturated nitrogen.

Fig. 3 is a polarization curve of the carbon-based oxygen reduction catalyst using the anode of the waste lithium iron phosphate battery prepared in example 1 of the present invention in a 0.1M KOH solution of saturated oxygen at different rotation speeds.

Fig. 4 is an oxygen reduction polarization curve of a carbon-based oxygen reduction catalyst using a positive electrode of a waste lithium iron phosphate battery, a commercial Pt/C catalyst, and an NSPC catalyst in a 0.1M KOH solution of saturated oxygen, which are prepared in example 1 of the present invention.

Fig. 5 is a rate performance curve of a carbon-based oxygen reduction catalyst using a positive electrode of a waste lithium iron phosphate battery and a commercial Pt/C catalyst in an aluminum air battery, which are prepared in example 1 of the present invention.

Detailed Description

In order to make the technical solutions more apparent to those skilled in the art, the following examples are given for illustration. It should be noted that the following examples are not intended to limit the scope of the claimed invention.

The starting materials, reagents or apparatuses used in the following examples are conventionally commercially available or can be obtained by conventionally known methods, unless otherwise specified.

Example 1

The preparation method of the carbon-based oxygen reduction catalyst by using the anode of the waste lithium iron phosphate battery comprises the following specific steps:

(1) discharging the waste lithium iron phosphate battery in a 5% NaCl solution for 24 hours, taking out, cutting and disassembling, separating the positive plate from other parts, completely soaking the positive plate in absolute ethyl alcohol, washing and drying the positive plate, performing heat treatment at 600 ℃ under Ar atmosphere for 2 hours to enable the positive plate material to fall off from an aluminum foil, collecting and grinding the positive plate material into powder;

(2) adding 2mol/L sodium hydroxide solution to dissolve aluminum scraps in the powder, adding deionized water to wash until the pH value is 7, and collecting filter residues after suction filtration;

(3) adding 6mol/L hydrochloric acid solution, stirring for 3h at water bath of 60 ℃ at 3000 r/min, filtering, collecting filter residue, repeatedly adding acid, dissolving under the same condition until the filtrate is colorless, adding deionized water, washing until the pH value is 7, filtering, collecting the final filter residue, and vacuum drying for 12h at 60 ℃;

(4) and finally, uniformly mixing the filter residue and melamine according to the mass ratio of 1:6, and calcining at the high temperature of 1000 ℃ for 2h under the Ar atmosphere to obtain the carbon-based oxygen reduction catalyst utilizing the anode of the waste lithium iron phosphate battery.

And (3) performance testing:

the performance test of the carbon-based oxygen reduction catalyst prepared in example 1 by using the anode of the waste lithium iron phosphate battery was carried out according to the following method:

(1) adding 990 μ L of anhydrous ethanol and 10 μ L of 5% Nafion solution into 4mg of catalyst, ultrasonically dispersing for 1h to obtain catalyst slurry, dripping 10 μ L of the catalyst slurry on a rotating disc electrode with a diameter of 5mm, and naturally drying in the air.

(2) Electrochemical tests were performed on a CHI760E electrochemical workstation using the above electrode as the working electrode, a carbon rod as the counter electrode and a saturated calomel electrode as the reference electrode.

(3) The cyclic voltammogram of the catalyst under saturated oxygen conditions was tested at a scan rate of 50mV/s in a 0.1M KOH solution, and the polarization curve of the catalyst under saturated oxygen conditions at various rotational speeds was tested at a scan rate of 5 mV/s.

Fig. 1 is a STEM diagram of a carbon-based oxygen reduction catalyst using a positive electrode of a waste lithium iron phosphate battery prepared in example 1 of the present invention; as can be seen from figure 1, the prepared catalyst has a loose structure, rich pores and an obvious three-dimensional network structure, and the transition metal particles are well embedded by carbon.

Fig. 2 is a cyclic voltammetry curve of a carbon-based oxygen reduction catalyst using a waste lithium iron phosphate battery positive electrode prepared in example 1 of the present invention in a 0.1M KOH solution of saturated oxygen and saturated nitrogen;

from fig. 2, it can be seen that the prepared catalyst has no obvious oxygen reduction peak in saturated nitrogen, but has an obvious oxygen reduction peak at 0.72V (vs. rhe) in saturated oxygen, which indicates that the prepared carbon-based oxygen reduction catalyst using the anode of the waste lithium iron phosphate battery has good catalytic activity.

Fig. 3 is a polarization curve of a carbon-based oxygen reduction catalyst using a positive electrode of a waste lithium iron phosphate battery prepared in example 1 of the present invention in a 0.1M KOH solution of saturated oxygen at different rotation speeds;

according to the polarization curves of the catalyst in different rotating speeds in the figure 3, the catalyst is calculated by a Koutech-Levich equation to react by a four-electron transfer mechanism;

fig. 4 is an oxygen reduction polarization curve of a carbon-based oxygen reduction catalyst using a positive electrode of a spent lithium iron phosphate battery and a commercialized Pt/C catalyst in a 0.1M KOH solution of saturated oxygen prepared in example 1 of the present invention.

As can be seen from comparison of oxygen reduction polarization curves of the carbon-based catalyst prepared in fig. 4 and the commercial Pt/C catalyst, the oxygen catalytic performance of the carbon-based oxygen reduction catalyst (initial potential 0.925V (vs. rhe), half-wave potential 0.828V (vs. rhe)) prepared in example 1 using the anode of the waste lithium iron phosphate battery is equivalent to that of the commercial Pt/C catalyst (initial potential 0.975V (vs. rhe), half-wave potential 0.864V (vs. rhe)), and is significantly better than that of the NSPC catalyst (initial potential 0.820V (vs. rhe), half-wave potential 0.704V (vs. rhe)).

As can be seen from the comparison of the rate performance curves of the carbon-based catalyst prepared in fig. 5 and the commercial Pt/C catalyst in the aluminum air battery, the performance of the carbon-based oxygen reduction catalyst prepared in example 1, which uses the anode of the waste lithium iron phosphate battery, is superior to that of the commercial Pt/C catalyst when the catalyst is applied to the aluminum air battery.

Example 2

The preparation method of the carbon-based oxygen reduction catalyst by using the anode of the waste lithium iron phosphate battery comprises the following specific steps:

(1) discharging the waste lithium iron phosphate battery in a 5% NaCl solution for 24 hours, taking out, cutting and disassembling, separating the positive plate from other parts, completely soaking the positive plate in absolute ethyl alcohol, washing and drying the positive plate, performing heat treatment at 600 ℃ under Ar atmosphere for 2 hours to enable the positive plate material to fall off from an aluminum foil, collecting and grinding the positive plate material into powder;

(2) adding 2mol/L sodium hydroxide solution to dissolve aluminum scraps in the powder, adding deionized water to wash until the pH value is 7, and collecting filter residues after suction filtration;

(3) adding 6mol/L hydrochloric acid solution, stirring for 3h at water bath of 60 ℃ at 3000 r/min, filtering, collecting filter residue, repeatedly adding acid, dissolving under the same condition until the filtrate is colorless, adding deionized water, washing until the pH value is 7, filtering, collecting the final filter residue, and vacuum drying for 12h at 60 ℃;

(4) mixing the final filter residue and melamine uniformly in a mass ratio of 1:6 in Ar/H₂Calcining the mixture for 2 hours at the high temperature of 1000 ℃ in the atmosphere to obtain the carbon-based oxygen reduction catalyst utilizing the anode of the waste lithium iron phosphate battery.

The performance of the carboxy reduction catalyst obtained in example 2 was measured in the same manner as in example 1, and the results of the performance of the oxygen reduction reaction are shown in Table 1.

Example 3

The preparation method of the carbon-based oxygen reduction catalyst by using the anode of the waste lithium iron phosphate battery comprises the following specific steps:

(1) discharging the waste lithium iron phosphate battery in a 5% NaCl solution for 24 hours, taking out, cutting and disassembling, separating the positive plate from other parts, completely soaking the positive plate in absolute ethyl alcohol, washing and drying the positive plate, performing heat treatment at 600 ℃ under Ar atmosphere for 2 hours to enable the positive plate material to fall off from an aluminum foil, collecting and grinding the positive plate material into powder;

(2) adding 2mol/L sodium hydroxide solution to dissolve aluminum scraps in the powder, adding deionized water to wash until the pH value is 7, and collecting filter residues after suction filtration;

(3) adding 6mol/L hydrochloric acid solution, stirring for 3h at water bath of 60 ℃ at 3000 r/min, filtering, collecting filter residue, repeatedly adding acid, dissolving under the same condition until the filtrate is colorless, adding deionized water, washing until the pH value is 7, filtering, collecting the final filter residue, and vacuum drying for 12h at 60 ℃;

(4) and finally, uniformly mixing the filter residue and melamine according to the mass ratio of 1:6, and calcining at the high temperature of 800 ℃ for 2h under the Ar atmosphere to obtain the carbon-based oxygen reduction catalyst utilizing the anode of the waste lithium iron phosphate battery.

The performance of the carboxy reduction catalyst obtained in example 3 was measured in the same manner as in example 1, and the results of the performance of the oxygen reduction reaction are shown in Table 1.

Example 4

The preparation method of the carbon-based oxygen reduction catalyst by using the anode of the waste lithium iron phosphate battery comprises the following specific steps:

(1) discharging the waste lithium iron phosphate battery in a 5% NaCl solution for 24 hours, taking out, cutting and disassembling, separating the positive plate from other parts, completely soaking the positive plate in absolute ethyl alcohol, washing and drying the positive plate, performing heat treatment at 600 ℃ under Ar atmosphere for 2 hours to enable the positive plate material to fall off from an aluminum foil, collecting and grinding the positive plate material into powder;

(2) adding 2mol/L sodium hydroxide solution to dissolve aluminum scraps in the powder, adding deionized water to wash until the pH value is 7, and collecting filter residues after suction filtration;

(3) adding 4mol/L hydrochloric acid solution, stirring for 6h at water bath of 60 ℃ at 3000 r/min, filtering, collecting filter residue, repeatedly adding acid and dissolving under the same condition until the filtrate is colorless, adding deionized water to wash until the pH value is 7, filtering, collecting the final filter residue, and vacuum drying for 12h at 60 ℃;

(4) and finally, uniformly mixing the filter residue and melamine according to the mass ratio of 1:6, and calcining at the high temperature of 800 ℃ for 2h under the Ar atmosphere to obtain the carbon-based oxygen reduction catalyst utilizing the anode of the waste lithium iron phosphate battery.

The performance of the carboxy reduction catalyst obtained in example 4 was measured in the same manner as in example 1, and the results of the performance of the oxygen reduction reaction are shown in Table 1.

Example 5

The preparation method of the carbon-based oxygen reduction catalyst by using the anode of the waste lithium iron phosphate battery comprises the following specific steps:

(1) discharging the waste lithium iron phosphate battery in a 5% NaCl solution for 24 hours, taking out, cutting and disassembling, separating the positive plate from other parts, completely soaking the positive plate in absolute ethyl alcohol, washing and drying the positive plate, performing heat treatment at 600 ℃ under Ar atmosphere for 2 hours to enable the positive plate material to fall off from an aluminum foil, collecting and grinding the positive plate material into powder;

(2) adding 2mol/L sodium hydroxide solution to dissolve aluminum scraps in the powder, adding deionized water to wash until the pH value is 7, and collecting filter residues after suction filtration;

(3) adding 2mol/L hydrochloric acid solution, stirring at a water bath temperature of 60 ℃ for 12h at 3000 r/min, performing suction filtration, collecting filter residue, repeatedly adding acid and dissolving under the same condition until the filtrate is colorless, adding deionized water to wash until the pH value is 7, performing suction filtration, and collecting the final filter residue, and performing vacuum drying at a temperature of 60 ℃ for 12 h;

(4) and finally, uniformly mixing the filter residue and melamine according to the mass ratio of 1:6, and calcining at the high temperature of 800 ℃ for 2h under the Ar atmosphere to obtain the carbon-based oxygen reduction catalyst utilizing the anode of the waste lithium iron phosphate battery.

The performance of the carboxy reduction catalyst obtained in example 5 was measured in the same manner as in example 1, and the results of the performance of the oxygen reduction reaction are shown in Table 1.

Example 6

The preparation method of the carbon-based oxygen reduction catalyst by using the anode of the waste lithium iron phosphate battery comprises the following specific steps:

(1) discharging the waste lithium iron phosphate battery in a 5% NaCl solution for 24 hours, taking out, cutting and disassembling, separating the positive plate from other parts, completely soaking the positive plate in absolute ethyl alcohol, washing and drying the positive plate, performing heat treatment at 600 ℃ under Ar atmosphere for 2 hours to enable the positive plate material to fall off from an aluminum foil, collecting and grinding the positive plate material into powder;

(2) adding 2mol/L sodium hydroxide solution to dissolve aluminum scraps in the powder, adding deionized water to wash until the pH value is 7, and collecting filter residues after suction filtration;

(3) adding 2mol/L hydrochloric acid solution, stirring at a water bath temperature of 60 ℃ for 12h at 3000 r/min, performing suction filtration, collecting filter residue, repeatedly adding acid and dissolving under the same condition until the filtrate is colorless, adding deionized water to wash until the pH value is 7, performing suction filtration, and collecting the final filter residue, and performing vacuum drying at a temperature of 60 ℃ for 12 h;

(4) and finally, uniformly mixing the filter residue and melamine according to the mass ratio of 1:5, and calcining at the high temperature of 800 ℃ for 2h under the Ar atmosphere to obtain the carbon-based oxygen reduction catalyst utilizing the anode of the waste lithium iron phosphate battery.

The performance of the carboxy reduction catalyst obtained in example 6 was measured in the same manner as in example 1, and the results of the performance of the oxygen reduction reaction are shown in Table 1.

Example 7

The preparation method of the carbon-based oxygen reduction catalyst by using the anode of the waste lithium iron phosphate battery comprises the following specific steps:

(1) discharging the waste lithium iron phosphate battery in a 5% NaCl solution for 24 hours, taking out, cutting and disassembling, separating the positive plate from other parts, completely soaking the positive plate in absolute ethyl alcohol, washing and drying the positive plate, performing heat treatment at 600 ℃ under Ar atmosphere for 2 hours to enable the positive plate material to fall off from an aluminum foil, collecting and grinding the positive plate material into powder;

(2) adding 2mol/L sodium hydroxide solution to dissolve aluminum scraps in the powder, adding deionized water to wash until the pH value is 7, and collecting filter residues after suction filtration;

(3) adding 2mol/L hydrochloric acid solution, stirring at a water bath temperature of 60 ℃ for 12h at 3000 r/min, performing suction filtration, collecting filter residue, repeatedly adding acid and dissolving under the same condition until the filtrate is colorless, adding deionized water to wash until the pH value is 7, performing suction filtration, and collecting the final filter residue, and performing vacuum drying at a temperature of 60 ℃ for 12 h;

(4) and finally, uniformly mixing the filter residue and melamine according to the mass ratio of 1:7, and calcining at the high temperature of 800 ℃ for 2h under the Ar atmosphere to obtain the carbon-based oxygen reduction catalyst utilizing the anode of the waste lithium iron phosphate battery.

The performance of the carboxy reduction catalyst obtained in example 7 was measured in the same manner as in example 1, and the results of the performance of the oxygen reduction reaction are shown in Table 1.

Comparative example 1

The performance of the commercial Pt/C catalyst was tested in the same manner as in example 1.

Comparative example 2

(2) The PVDF is subjected to heat treatment at 600 ℃ for 2h under the Ar atmosphere, mixed with SP, added with 2mol/L hydrochloric acid solution, stirred for 12h at 3000 r/min in water bath at 60 ℃, washed by deionized water until the pH value is 7, subjected to suction filtration, dried, uniformly mixed with melamine according to the mass ratio of 1:5, calcined at 800 ℃ for 2h under the Ar atmosphere to obtain a comparison sample NSPC catalyst, and subjected to performance test by the same method as that of example 1.

TABLE 1 ORR Performance comparison

The above detailed description of the carbon-based oxygen reduction catalyst using the anode of the waste lithium iron phosphate battery and the preparation method and application thereof provided by the present invention are also applicable to the carbon-based oxygen reduction catalyst using the anode material of the waste ternary lithium ion battery, and the principle and the implementation manner thereof are described herein by applying the specific examples, and the description of the above examples is only for helping to understand the method and the core concept thereof, including the best mode, and also for enabling any scientific researchers in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and such improvements and modifications are also within the scope of the present invention as defined in the appended claims. The scope of patented protection is defined by the claims, and may include other examples that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.