Preparation method of lanthanum-doped copper-based Prussian blue zinc ion battery positive electrode material

Abstract

The invention discloses a preparation method of a lanthanum-doped copper-based Prussian blue zinc ion battery positive electrode material. The preparation method comprises the following steps: dropwise adding a mixed solution containing potassium ferricyanide and a surfactant into a mixed solution containing a copper salt, a lanthanum salt and a complexing agent at a constant speed in a co-precipitation manner; and the lanthanum-doped copper-based Prussian blue compound is obtained by regulating and controlling parameters such as types of complexing agents, concentration of the complexing agents, material proportion, temperature and the like. According to the method, the surfactant and the complexing agent are added under synthesis conditions, so that vacancies and crystal water are reduced, and the stability of the material is improved. In addition, by utilizing the characteristics of the lanthanum rare earth element, the structural stability of the copper-based Prussian blue material is further enhanced, and the initial capacity liquid is improved while the cycle performance and the rate capability are improved. The bimetallic material has the advantages of relatively simple preparation process, low manufacturing cost and the like, and has relatively great advantages in the field of positive electrode materials of zinc ion batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of secondary power battery materials, and specifically relates to a preparation method of a lanthanum-doped copper-based Prussian blue-like zinc ion battery cathode material. Background Art

[0002] Prussian blue-like materials have an open face-centered cubic structure, a porous three-dimensional framework with large open vacant sites, and can allow multiple ions to reversibly embed / extract, showing certain development potential in the energy storage field. Copper-based Prussian blue-like materials have been widely studied by scientific researchers due to their high potential advantages. However, they still have common problems such as multiple vacancies and multiple coordinated waters in Prussian blue materials, resulting in poor electrochemical performance and poor intrinsic conductivity.

[0003] To solve the above problems, a large amount of work has been done by scientific researchers at home and abroad. For example, structural design of materials, element doping, or adding complexing agents during synthesis, etc. The preparation of Prussian blue-like materials reported in patent literature mainly includes: Zhejiang University's "A Prussian blue material and its preparation method and application" (CN114715917A); Anhui University's "A Prussian blue analogue and its preparation method and application" (CN110060880A); and Wuhan University's "A class of sodium ion battery cathode materials" (CN102522553A), etc. However, these preparation methods reported currently either improve the crystallinity by adding complexing agents. Although they can show good performance in the initial stage, they still cannot meet the requirements for stability during long cycles. Or they adopt relatively complex processes, with high costs and are not conducive to large-scale development. In addition, most of the reported Prussian blue materials are selected for sodium ion battery cathode materials, and there are few cases where they are successfully applied to zinc ion battery cathode materials.

[0004] Therefore, it is of great significance to develop a preparation method for a copper-based Prussian blue-like zinc ion battery cathode material with simple operation, good electrochemical performance, and good conductivity. Summary of the Invention

[0005] The present invention overcomes the defects of existing copper-based Prussian blue-like materials as zinc ion battery cathode materials, such as low specific capacity, poor rate performance, poor cycle performance, and poor conductivity, and provides a preparation method for a lanthanum-doped copper-based Prussian blue-like zinc ion battery cathode material with stable structure, excellent rate performance, and excellent cycle performance.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A preparation method of a lanthanum-doped copper-based Prussian blue-like zinc ion battery cathode material, and its specific steps are:

[0008] (1) Add K3Fe(CN)6 and surfactant into an aqueous solution, stir until completely dissolved and name it as solution A. The concentration of K3Fe(CN)6 in solution A is 0.025 - 0.1 mol / L, and the mass ratio of surfactant to K3Fe(CN)6 is 0.5 - 1.25;

[0009] (2) Add copper sulfate pentahydrate, lanthanum nitrate and complexing agent into an aqueous solution, stir until completely dissolved and name it as solution B. The total molar amount of copper sulfate and lanthanum nitrate in solution B is 2 mmol, and the molar ratio of complexing agent to metal salt is 0.75 - 1.75;

[0010] (3) Slowly drip solution B in step (2) into solution A in step (1) at a certain temperature, and stir it with a magnetic stirrer. After continuously heating for a certain time, let it stand, centrifuge, wash, and vacuum dry to obtain the lanthanum-doped copper-based Prussian blue-like material;

[0011] (4) Mix the obtained lanthanum-doped copper-based Prussian blue-like material, carbon black and binder in a mass ratio of 80:10:10 to form a slurry, evenly coat it on carbon paper, and dry it to obtain the positive electrode material for zinc ion batteries.

[0012] Preferably in step (1), the concentration of K3Fe(CN)6 is 0.04 mol / L, and the mass ratio of surfactant to K3Fe(CN)6 is 0.75:1.

[0013] The preferably used surfactant in step (1) is polyvinylpyrrolidone.

[0014] In step (2), the complexing agent is one of sodium pyrophosphate, sodium citrate, and disodium ethylenediaminetetraacetate.

[0015] Preferably in step (2), the ratio of copper sulfate to lanthanum nitrate is 95:05, and the molar ratio of complexing agent to metal salt is 1.5:1.

[0016] In step (3), the heating temperature is 80 °C, and the continuous stirring time is 10 h.

[0017] The polypyrrole-coated copper-based Prussian blue-like material obtained according to the above preparation method can be expressed as K x Cu y La 1-y [Fe(CN)6], where the value range of x is 1 - 2, the value range of y is 0.01 - 0.99, and the morphology presents a cubic shape.

[0018] The polypyrrole-coated Prussian blue-like material prepared by the above preparation method is used as the positive electrode material for zinc ion batteries.

[0019] The advantages of the present invention are as follows:

[0020] The lanthanum-doped copper-based Prussian blue-like cathode material for zinc-ion batteries of the present invention, through the co-doping of two elements Cu and La, utilizes the large radius characteristic of rare earth elements to increase the initial specific capacity of the copper-based Prussian blue-like material; and surfactant and complexing agent are jointly used to reduce the reaction rate, improve the crystallinity of the copper-based Prussian blue-like material, and enhance the rate performance and cycling performance of the material. In addition, rare earth lanthanum element has good electronic properties, which can improve the conductivity of the copper-based Prussian blue-like material. Moreover, the preparation process of this material is simple, the manufacturing cost is low, it is green and environmentally friendly, and it has great advantages in the field of cathode materials for zinc-ion batteries. Detailed implementation manners

[0021] Example 1: A preparation method of a lanthanum-doped copper-based Prussian blue zinc-ion battery cathode material, and its specific steps are as follows:

[0022] (1) Add 0.66 g of K3Fe(CN)6 and 0.45 g of polyvinylpyrrolidone to 50 mL of aqueous solution, stir until completely dissolved and name it solution A;

[0023] (2) Add 0.475 g of copper sulfate pentahydrate, 0.040 g of lanthanum nitrate and 1.32 g of sodium pyrophosphate to and stir until completely dissolved and name it solution B;

[0024] (3) Slowly add the solution B in step (2) to the solution A in step (1) at 80 °C, and stir with a magnetic stirrer, continuously heat for 10 h. Then let it stand for 24 h, centrifuge and wash 3 times, and vacuum dry at 80 °C for 24 h. Obtain the K 1.37 Cu 95 La 05 [Fe(CN)6] material;

[0025] (4) Take the K 1.37 Cu 95 La 05 [Fe(CN)6] material, mix it with carbon black and binder in a mass ratio of 80:10:10 to form a slurry, uniformly coat it on the current collector, and dry to obtain the battery cathode material.

[0026] Then assemble it into a button battery and conduct constant current charge and discharge tests (current density 50 mA·g -1 ) and rate performance tests. The initial specific capacity of the K 1.37 Cu 95 La 05 [Fe(CN)6] material is 68.20 mAh g-1, and the capacity after 200 cycles is 62.59 mAhg -1, the capacity retention rate is 91.77%. Compared with pure-phase CuHCF, the capacity in the first cycle is increased by 24.73%. When the current density is increased to 300 mA·g -1 , the discharge capacity in its first cycle is about 54.5 mAh·g -1 , while the capacity of pure-phase CuHCF drops rapidly, only being 39.78 mAh·g -1 , indicating that K 1.37 Cu 95 La 05 [Fe(CN)6] has better rate performance and good electrical conductivity.

[0027] Example 2: A preparation method of a lanthanum-doped copper-based Prussian blue zinc ion battery cathode material, and its specific steps are as follows:

[0028] (1) Add 0.66 g of K3Fe(CN)6 and 0.45 g of polyvinylpyrrolidone to 50 mL of aqueous solution, and stir until completely dissolved, named solution A;

[0029] (2) Add 0.485 g of copper sulfate pentahydrate, 0.025 g of lanthanum nitrate, and 1.32 g of sodium pyrophosphate to it, stir until completely dissolved, and name it solution B;

[0030] (3) Slowly add the solution B in step (2) to the solution A in step (1) at 80 °C, and stir with a magnetic stirrer, continuously heat for 10 h. Then let it stand for 24 h, centrifuge and wash 3 times, and vacuum dry at 80 °C for 24 h. Obtain K 1.2 cu 97 La 03 [Fe(CN)6] material;

[0031] (5) Take the K 1.2 cu 97 La 03 [Fe(CN)6] material, mix it with carbon black and binder in a mass ratio of 80:10:10 to form a slurry, evenly coat it on the current collector, and dry to obtain the battery cathode material.

[0032] Then assemble it into a button battery and conduct constant current charge and discharge tests (current density 50 mA·g -1 ) and rate performance tests. K 1.2 Cu 97 La 03 [Fe(CN)6] provides a reversible discharge capacity of 60.13 mAh·g -1 in the first cycle. After 50 cycles, the reversible capacity remains at 52.48 mAh·g -1 , and the capacity retention rate is 85.84%. When the current density is increased to 300 mAg -1When it is at this time, its initial cycle discharge capacity is about 49.76 mAh·g -1 , showing excellent rate performance and good electrical conductivity.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A preparation method of a lanthanum-doped copper-based Prussian blue zinc ion battery cathode material, characterized in that, It includes the following steps: (1) Add K3Fe(CN)6 and surfactant into an aqueous solution, stir until completely dissolved and name it solution A. The concentration of K3Fe(CN)6 in solution A is 0.025 - 0.1 mol / L, and the mass ratio of surfactant to K3Fe(CN)6 is 0.5 - 1.25; (2) Add copper sulfate pentahydrate, lanthanum nitrate and complexing agent into an aqueous solution, stir until completely dissolved and name it solution B. The total molar amount of copper sulfate and lanthanum nitrate in solution B is 2 mmol, and the molar ratio of complexing agent to metal salt is 0.75 - 1.75; (3) Slowly drip the solution B in step (2) into the solution A in step (1) at a certain temperature, and stir it with a magnetic stirrer. After continuously heating for a certain time, let it stand, centrifuge, wash, and vacuum dry to obtain the lanthanum-doped copper-based Prussian blue-like material; (4) Mix the lanthanum-doped copper-based Prussian blue-like material obtained above, carbon black and binder in a mass ratio of 80:10:10 to form a slurry, uniformly coat it on carbon paper, and dry it to obtain the positive electrode material for zinc ion battery.

2. The preparation method of the lanthanum-doped copper-based Prussian blue-like material as the cathode material for a zinc-ion battery according to claim 1, characterized in that, In step (1), the concentration of K3Fe(CN)6 is preferably 0.04 mol / L, and the mass ratio of surfactant to K3Fe(CN)6 is preferably 0.75:

1.

3. The preparation method of the cathode material for a zinc ion battery using a lanthanum-doped copper-based Prussian blue material as claimed in claim 1, wherein The surfactant is polyvinylpyrrolidone.

4. The preparation method of the cathode material for a zinc-ion battery using a lanthanum-doped copper-based Prussian blue material as claimed in claim 1, wherein In step (2), the total molar amount of copper sulfate and lanthanum nitrate is 2 mmol, and the ratio of copper sulfate to manganese salt is preferably 95:

05.

5. The preparation method of the cathode material for a zinc ion battery using a lanthanum-doped copper-based Prussian blue material as claimed in claim 1, wherein In step (2), the complexing agent is sodium citrate, sodium pyrophosphate and disodium ethylenediaminetetraacetate, and the molar ratio of complexing agent to metal salt is 1.5:

1.

6. The preparation method of the cathode material for a zinc ion battery using a lanthanum-doped copper-based Prussian blue material as claimed in claim 1, characterized in that, In step (3), the heating temperature is 80 °C, and the continuous stirring time is 10 h.

7. The preparation method of the lanthanum-doped copper-based Prussian blue-like cathode material for zinc ion batteries according to claim 1, characterized in that, The lanthanum-doped copper-based Prussian blue material can be expressed as K x Cu y La 1-y [Fe(CN)6], where the value range of x is 1 to 2, the value range of y is 0.01 - 0.99, and the morphology is cubic.