CN104505522B - Hydrothermal preparation method of lanthanum-nickel composite oxide catalyst for lithium-air battery - Google Patents

Abstract

The invention relates to the technical field of catalysts for lithium air batteries, in particular to a hydrothermal preparation method of a lanthanum-nickel composite oxide catalyst for a lithium air battery, which comprises the steps of weighing lanthanum salt and nickel salt according to a stoichiometric ratio of 2:1, and dissolving the lanthanum salt and the nickel salt in deionized water; dripping 0.002-0.004mol of glycine; adding a pH value regulator and stirring; heating for 10-14h under the conditions of 175-185 ℃ in a sealed way, and washing and drying the obtained product; and sintering at high temperature in an oxygen-rich atmosphere to obtain the lanthanum-nickel composite oxide catalyst for the lithium-air battery. The catalyst prepared by the invention is a La2NiO4 material with a cubic crystal structure, the size of the catalyst is uniform, the relative support property of the cubic crystal structure is strong, and the loss is not easy to occur, so that the unit active area and the service life of the catalyst are improved; electrochemical tests also show that the catalyst has excellent cycle life and higher practical value, and can meet the industrialization requirement of high-performance ether lithium-air batteries.

Description

A kind of hydrothermal preparation method of lanthanum-nickel composite oxide catalyst for lithium-air battery

technical field

The invention relates to the technical field of catalysts for lithium-air batteries, in particular to a hydrothermal preparation method for a lanthanum-nickel composite oxide catalyst for lithium-air batteries.

Background technique

Lithium-air batteries have attracted extensive attention due to their high theoretical energy density. The advantage of the battery is that the active material oxygen of the positive electrode comes directly from the air and does not need to be stored inside the battery, which not only reduces the cost but also reduces the weight of the battery. However, in order to realize its application, a series of problems need to be solved, such as low electrolyte stability, poor rate performance, poor cycle stability, etc., and the catalysts used in lithium-air batteries directly affect these properties.

The currently reported catalysts with catalytic activity in ether electrolytes mainly include noble metals, pyrochlore oxides, and Co3O4, etc. However, these catalysts are accumulated in the air electrode in the form of particles, which is not conducive to their catalytic activity. Playing with the mass transfer of the air electrode in the battery reaction leads to a decrease in the performance of the ether lithium-air battery. Among them, noble metal catalysts also have the disadvantage of high cost. Therefore, none of the above-mentioned existing catalysts can meet the requirements for the industrialization of high-performance ether-based lithium-air batteries.

Contents of the invention

The object of the present invention is to provide a low-cost, high-performance hydrothermal preparation method of a lanthanum-nickel composite oxide catalyst for lithium-air batteries that can meet the requirements of the industrialization of high-performance ether-based lithium-air batteries.

The object of the present invention is achieved through the following technical solutions: a hydrothermal preparation method for a lithium-air battery lanthanum-nickel composite oxide catalyst, comprising the following steps:

A hydrothermal preparation method of a lanthanum-nickel composite oxide catalyst for a lithium-air battery, comprising the following steps:

A, weigh lanthanum salt and nickel salt respectively according to stoichiometric ratio 2:1, dissolve in 60-80mL deionized water, stir to form a mixed solution, control the concentration of nickel salt in the mixed solution to be 0.0005-0.0015mol/L;

B, in the mixed solution of step A, dropwise add 0.002-0.004mol glycine, glycine is made gelling agent and pH buffering agent;

C. Add a pH adjuster to the mixed solution in which glycine was added dropwise in step B and stir to adjust the pH to 7.6-7.8;

D. Airtightly heat the mixed solution of step C at 175-185° C. for 10-14 hours to obtain the product;

E, washing and drying the product of step D;

F. Sinter the product treated in step E at high temperature in an oxygen-enriched atmosphere to form a nanostructure, first raise the temperature to 600-700°C at a heating rate of 2-4°C/min, and then keep it warm for 2-4 hours to obtain lithium air Lanthanum nickel composite oxide catalyst for batteries.

Preferably, in the step A, the lanthanum salt is lanthanum nitrate hexahydrate, and the nickel salt is nickel nitrate. Nitrate can be decomposed at high temperature, avoiding the introduction of non-catalyst residues.

Preferably, in the step A, the stirring speed is 150 rpm, and the stirring time is 0.5 hour.

Preferably, in the step C, the stirring speed is 150 rpm.

Preferably, the pH adjusting agent in step C is ammonia water, which can escape after pH adjustment to avoid introducing non-catalyst residues.

Preferably, the closed heating in the step D is carried out in a hydrothermal reactor.

Preferably, the drying in step E is carried out at a temperature of 80°C.

Preferably, the high-temperature oxygen-enriched atmosphere in step F is carried out in a tube furnace.

A lithium-air battery cathode prepared by using a lanthanum-nickel composite oxide catalyst for lithium-air batteries.

A lithium-ion battery prepared by using the positive electrode of a lithium-air battery.

The beneficial effect of the present invention is that: the lanthanum _- nickel composite oxide catalyst for lithium-air batteries prepared by the preparation method provided by the present invention is a _La2NiO4 material with a cubic crystal structure, and its size is uniform, and the cubic crystal structure is relatively strong in support , is not easy to be lost, thereby improving the unit active area and life of the catalyst; electrochemical tests also show that the lanthanum-nickel composite oxide catalyst for lithium-air batteries prepared by this method has excellent cycle life, has high practical value, and can meet high performance requirements. Ether-based lithium-air battery industrialization requirements; the cost of raw materials adopted in the present invention is low, the preparation process is easy and simple, and it is easy for industrial production.

Description of drawings

Fig. 1 is the life curve of the lithium-ion battery prepared by the lithium-air battery of the present invention using a lanthanum-nickel composite oxide catalyst.

Fig. 2 is the first charge and discharge curve of the lithium-ion battery prepared by using the lanthanum-nickel composite oxide catalyst for the lithium-air battery of the present invention.

Fig. 3 is an SEM image prepared by using a lanthanum-nickel composite oxide catalyst for a lithium-air battery of the present invention.

Fig. 4 is an XRD pattern prepared by the lanthanum-nickel composite oxide catalyst used in the lithium-air battery of the present invention.

detailed description

In order to facilitate the understanding of those skilled in the art, the present invention will be further described below in conjunction with the embodiments and accompanying drawings 1-4, and the contents mentioned in the implementation modes are not intended to limit the present invention.

Example 1

A hydrothermal preparation method of a lanthanum-nickel composite oxide catalyst for a lithium-air battery, comprising the following steps:

A, take by weighing lanthanum salt and nickel salt respectively according to stoichiometric ratio 2:1, be dissolved in 60mL deionized water, stir to form mixed solution, control the nickel salt concentration in the mixed solution to be 0.0005mol/L;

B, in the mixed solution of step A, dropwise add 0.002mol glycine;

C. Add a pH adjuster to the mixed solution in which glycine was added dropwise in step B and stir to adjust the pH to 7.6;

D. Heat the mixed solution in step C under airtight conditions at 175° C. for 14 hours to obtain the product;

E, washing and drying the product of step D;

F. Sinter the product treated in step E at high temperature in an oxygen-enriched atmosphere, first raise the temperature to 600°C at a heating rate of 2°C/min, and then keep it warm for 4 hours to obtain a lanthanum-nickel composite oxide catalyst for lithium-air batteries.

In the step A, the lanthanum salt is lanthanum nitrate hexahydrate, and the nickel salt is nickel nitrate.

In the step A, the stirring speed is 150 rpm, and the stirring time is 0.5 hour.

In the step C, the stirring speed is 150 rpm.

In the step C, the pH regulator is ammonia water.

The airtight heating in the step D is carried out in a hydrothermal reactor.

The drying in step E is carried out at a temperature of 80°C.

The high-temperature oxygen-enriched atmosphere in the step F is carried out in a tube furnace.

A lithium-air battery cathode prepared by using the above-mentioned lanthanum-nickel composite oxide catalyst for lithium-air batteries. A lithium-ion battery prepared by using the positive electrode of the above-mentioned lithium-air battery.

Specifically, the lanthanum-nickel composite oxide catalyst La ₂ NiO ₄ for lithium-air batteries prepared in this example, the conductive agent Ketjen black, and the binder PTFE were mixed uniformly according to the mass ratio of 3.5:4.5:1, and N-formazol Base pyrrolidone NMP to prepare this mixture into a slurry, evenly coat it on the copper foil, put it in an oven and dry it at 90°C for 2 hours, take it out and punch it into a pole piece, dry it in vacuum at 120°C for 12 hours, roll it, and dry it in vacuum at 85°C for 12 hours , to make pole pieces for laboratory batteries. The lithium sheet is used as the counter electrode, the electrolyte is TEGDME (triethylene glycol dimethyl ether) solution of 1mol/LLiTFSI (lithium bistrifluoromethanesulfonylimide), and the separator is glass fiber, in a glove box filled with argon atmosphere Assembled into a CR2025 special button battery for charging and discharging in the air, the charge cut-off voltage is 4.4V, the discharge cut-off voltage is 2.1V, the charge and discharge current density is set to 51mA/g, and the mass in the current density unit is the positive electrode catalyst and the conductive material. carbon mass and . The first discharge specific capacity of the battery was measured to be 3750mAh/g.

Example 2

A hydrothermal preparation method of a lanthanum-nickel composite oxide catalyst for a lithium-air battery, comprising the following steps:

A, take by weighing lanthanum salt and nickel salt respectively according to stoichiometric ratio 2:1, be dissolved in 70mL deionized water, stir to form mixed solution, control the nickel salt concentration in the mixed solution to be 0.001mol/L;

B, in the mixed solution of step A, dropwise add 0.003mol glycine;

C. Add a pH adjuster to the mixed solution in which glycine was added dropwise in step B and stir to adjust the pH to 7.7;

D. Heat the mixed solution in step C under airtight conditions at 180° C. for 12 hours to obtain the product;

E, washing and drying the product of step D;

F. Sinter the product treated in step E at high temperature in an oxygen-enriched atmosphere, first raise the temperature to 650°C at a heating rate of 3°C/min, and then keep it warm for 3 hours to obtain a lanthanum-nickel composite oxide catalyst for lithium-air batteries.

In the step A, the lanthanum salt is lanthanum nitrate hexahydrate, and the nickel salt is nickel nitrate.

In the step A, the stirring speed is 150 rpm, and the stirring time is 0.5 hour.

In the step C, the stirring speed is 150 rpm.

In the step C, the pH regulator is ammonia water.

The airtight heating in the step D is carried out in a hydrothermal reactor.

The drying in step E is carried out at a temperature of 80°C.

The high-temperature oxygen-enriched atmosphere in the step F is carried out in a tube furnace.

A lithium-air battery cathode prepared by using the above-mentioned lanthanum-nickel composite oxide catalyst for lithium-air batteries. A lithium-ion battery prepared by using the positive electrode of the above-mentioned lithium-air battery.

Specifically, the lanthanum-nickel composite oxide catalyst La ₂ NiO ₄ for lithium-air batteries prepared in this example, the conductive agent Ketjen black, and the binder PTFE were mixed uniformly according to the mass ratio of 3.5:4.5:1, and N-formazol Base pyrrolidone NMP to prepare this mixture into a slurry, evenly coat it on the copper foil, put it in an oven and dry it at 90°C for 2 hours, take it out and punch it into a pole piece, dry it in vacuum at 120°C for 12 hours, roll it, and dry it in vacuum at 85°C for 12 hours , to make pole pieces for laboratory batteries. The lithium sheet is used as the counter electrode, the electrolyte is TEGDME (triethylene glycol dimethyl ether) solution of 1mol/LLiTFSI (lithium bistrifluoromethanesulfonylimide), and the separator is glass fiber, in a glove box filled with argon atmosphere Assemble it into a CR2025 special button battery, charge and discharge in the air, the charge cut-off voltage is 4.5V, the discharge cut-off voltage is 2.0V, the charge and discharge current density is set to 50mA/g, the mass in the current density unit is the positive electrode catalyst and Conductive carbon mass and . The first discharge specific capacity of the battery was measured to be 3751mAh/g.

Example 3

A hydrothermal preparation method of a lanthanum-nickel composite oxide catalyst for a lithium-air battery, comprising the following steps:

A, take by weighing lanthanum salt and nickel salt respectively according to stoichiometric ratio 2:1, be dissolved in 70mL deionized water, stir to form mixed solution, control the nickel salt concentration in the mixed solution to be 0.0011mol/L;

B, in the mixed solution of step A, dropwise add 0.003mol glycine;

C. Add a pH adjuster to the mixed solution in which glycine was added dropwise in step B and stir to adjust the pH to 7.8;

D. Heat the mixed solution in step C under airtight conditions at 179°C for 13 hours to obtain the product;

E, washing and drying the product of step D;

F. Sinter the product treated in step E at high temperature in an oxygen-enriched atmosphere, first raise the temperature to 680°C at a heating rate of 3°C/min, and then keep it warm for 3 hours to obtain a lanthanum-nickel composite oxide catalyst for lithium-air batteries.

In the step A, the lanthanum salt is lanthanum nitrate hexahydrate, and the nickel salt is nickel nitrate.

In the step A, the stirring speed is 150 rpm, and the stirring time is 0.5 hour.

In the step C, the stirring speed is 150 rpm.

In the step C, the pH regulator is ammonia water.

The airtight heating in the step D is carried out in a hydrothermal reactor.

The drying in step E is carried out at a temperature of 80°C.

The high-temperature oxygen-enriched atmosphere in the step F is carried out in a tube furnace.

A lithium-air battery cathode prepared by using the above-mentioned lanthanum-nickel composite oxide catalyst for lithium-air batteries. A lithium-ion battery prepared by using the positive electrode of the above-mentioned lithium-air battery.

Specifically, the lanthanum-nickel composite oxide catalyst La ₂ NiO ₄ for lithium-air batteries prepared in this example, the conductive agent Ketjen black, and the binder PTFE were mixed uniformly according to the mass ratio of 3.5:4.5:1, and N-formazol Base pyrrolidone NMP to prepare the mixture into a slurry, evenly coat it on the copper foil, put it in an oven and dry it at 90°C for 2 hours, take it out and punch it into a pole piece, dry it in vacuum at 120°C for 12 hours, roll it, and dry it in vacuum at 85°C for 12 hours , to make pole pieces for laboratory batteries. The lithium sheet is used as the counter electrode, the electrolyte is TEGDME (triethylene glycol dimethyl ether) solution of 1mol/LLiTFSI (lithium bistrifluoromethanesulfonylimide), and the separator is glass fiber. Assemble it into a CR2025 special button battery, charge and discharge in the air, the charge cut-off voltage is 4.4V, the discharge cut-off voltage is 2.0V, the charge and discharge current density is set to 50mA/g, the mass in the current density unit is the positive electrode catalyst and Conductive carbon mass and . The first discharge specific capacity of the battery was measured to be 3750mAh/g.

Example 4

A hydrothermal preparation method of a lanthanum-nickel composite oxide catalyst for a lithium-air battery, comprising the following steps:

A, take by weighing lanthanum salt and nickel salt respectively according to stoichiometric ratio 2:1, be dissolved in 80mL deionized water, stir to form mixed solution, control the nickel salt concentration in the mixed solution to be 0.0015mol/L;

B, in the mixed solution of step A, dropwise add 0.004mol glycine;

C. Add a pH adjuster to the mixed solution in which glycine was added dropwise in step B and stir to adjust the pH to 7.8;

D. Heat the mixed solution in step C under airtight conditions at 185° C. for 10 h to obtain the product;

E, washing and drying the product of step D;

F. Sinter the product treated in step E at high temperature in an oxygen-enriched atmosphere, first raise the temperature to 700°C at a heating rate of 4°C/min, and then keep it warm for 2 hours to obtain a lanthanum-nickel composite oxide catalyst for lithium-air batteries.

In the step A, the lanthanum salt is lanthanum nitrate hexahydrate, and the nickel salt is nickel nitrate.

In the step A, the stirring speed is 150 rpm, and the stirring time is 0.5 hour.

In the step C, the stirring speed is 150 rpm.

In the step C, the pH regulator is ammonia water.

The airtight heating in the step D is carried out in a hydrothermal reactor.

The drying in step E is carried out at a temperature of 80°C.

The high-temperature oxygen-enriched atmosphere in the step F is carried out in a tube furnace.

A lithium-air battery cathode prepared by using the above-mentioned lanthanum-nickel composite oxide catalyst for lithium-air batteries. A lithium-ion battery prepared by using the positive electrode of the above-mentioned lithium-air battery.

Specifically, the lanthanum-nickel composite oxide catalyst La ₂ NiO ₄ for lithium-air batteries prepared in this example, the conductive agent Ketjen black, and the binder PTFE were mixed uniformly according to the mass ratio of 3.5:4.5:1, and N-formazol Base pyrrolidone NMP to prepare this mixture into a slurry, evenly coat it on the copper foil, put it in an oven and dry it at 90°C for 2 hours, take it out and punch it into a pole piece, dry it in vacuum at 120°C for 12 hours, roll it, and dry it in vacuum at 85°C for 12 hours , to make pole pieces for laboratory batteries. The lithium sheet is used as the counter electrode, the electrolyte is TEGDME (triethylene glycol dimethyl ether) solution of 1mol/LLiTFSI (lithium bistrifluoromethanesulfonylimide), and the separator is glass fiber, in a glove box filled with argon atmosphere Assemble it into a CR2025 special button battery, charge and discharge in the air, the charge cut-off voltage is 4.5V, the discharge cut-off voltage is 2.0V, the charge and discharge current density is set to 50mA/g, the mass in the current density unit is the positive electrode catalyst and Conductive carbon mass and . The first discharge specific capacity of the battery was measured to be 3751mAh/g.

It can be seen from Fig. 1 that the cycle life of the application battery of the present invention can reach 50 times, indicating that the life of the lithium-air battery of the present invention is higher than the average life of the current lithium-air battery.

It can be seen from Fig. 2 that the applied battery capacity of the present invention can reach 3751mAh, indicating that the battery capacity of the present invention has reached 1.3 times of the current average level of lithium-air batteries.

It can be seen from FIG. 3 that the particle size of the catalyst of the present invention is about 100 nm, indicating that the size of the catalyst of the present invention has reached the nanometer level and the particle size distribution is uniform.

As can be seen from Figure 4, the marked peak represents the characteristic peak of lanthanum nickelate, indicating that the prepared catalyst is lanthanum nickelate.

The above-mentioned embodiments are preferred implementation solutions of the present invention. In addition, the present invention can also be realized in other ways, and any obvious replacements are within the protection scope of the present invention without departing from the concept of the present invention.

Claims (10)

1. a kind of hydrothermal preparing process of lithium-air battery La-Ni mixed oxides catalyst, it is characterised in that：Including following Step：

A, according to stoichiometric proportion 2:1 weighs respectively lanthanum salt and nickel salt, and in being dissolved in 60-80mL deionized waters, stirring forms mixed Solution is closed, it is 0.0005-0.0015mol/L to control nickel salt concentration in mixed solution；

B, to the mixed solution and dripping 0.002-0.004mol glycine of step A；

C, will be added dropwise to be added in the mixed solution of glycine in step B and pH value regulator and stirred, regulations pH value has been 7.6- 7.8；

D, by the mixed solution of step C under the conditions of 175-185 DEG C airtight heating 10-14h, obtain product；

E, by the product washing and drying of step D；

F, the product after the process of step E is sintered in oxygen-enriched atmosphere high temperature, first with the heating rate liter of 2-4 DEG C/min Temperature is incubated 2-4 hours to 600-700 DEG C, then, obtains lithium-air battery La-Ni mixed oxides catalyst.

2. the hydrothermal preparing process of a kind of lithium-air battery La-Ni mixed oxides catalyst according to claim 1, It is characterized in that：In step A, lanthanum salt is lanthanum nitrate hexahydrate, and the nickel salt is nickel nitrate.

3. the hydrothermal preparing process of a kind of lithium-air battery La-Ni mixed oxides catalyst according to claim 1, It is characterized in that：In step A, the rotating speed of stirring is 150 revs/min, and the time of stirring is 0.5 hour.

4. the hydrothermal preparing process of a kind of lithium-air battery La-Ni mixed oxides catalyst according to claim 1, It is characterized in that：In step C, the rotating speed of stirring is 150 revs/min.

5. the hydrothermal preparing process of a kind of lithium-air battery La-Ni mixed oxides catalyst according to claim 1, It is characterized in that：PH value regulator is ammoniacal liquor in step C.

6. the hydrothermal preparing process of a kind of lithium-air battery La-Ni mixed oxides catalyst according to claim 1, It is characterized in that：Airtight heating is carried out in hydrothermal reaction kettle in step D.

7. the hydrothermal preparing process of a kind of lithium-air battery La-Ni mixed oxides catalyst according to claim 1, It is characterized in that：Drying in step E is carried out at 80 DEG C.

8. the hydrothermal preparing process of a kind of lithium-air battery La-Ni mixed oxides catalyst according to claim 1, It is characterized in that：The step F high temperature oxygen-enriched atmosphere is carried out in tube furnace.

9. a kind of a kind of lithium of the preparation of the lithium-air battery La-Ni mixed oxides catalyst described in utilization claim 1- O for cathode of air battery.

10. the lithium ion battery that prepared by the lithium-air battery positive pole described in a kind of utilization claim 9.