CN113206224B - Core-shell structure Prussian blue potassium ion battery positive electrode material modified by polymeric organic matters and preparation method thereof - Google Patents

Abstract

The invention discloses a core-shell Prussian blue potassium ion battery anode material modified by a polymeric organic substance and a preparation method thereof. The preparation method comprises the following steps: firstly preparing an iron-based Prussian blue core by a coprecipitation method, then adding a transition metal salt and potassium ferrocyanide into the suspension in an in-situ growth mode, mixing and stirring, growing another iron-based Prussian blue on the particle surface, and obtaining the K with a core-shell structure after aging, centrifuging, washing and drying processes_xM₁Fe(CN)₆@K_yM₂Fe(CN)₆And (3) powder. And dispersing the powder in an organic monomer salt solution, mixing and stirring for a certain time, and centrifuging, drying, washing and collecting to obtain the core-shell Prussian blue cathode material modified by the polymeric organic substance. The potassium ion battery positive electrode material has excellent rate capability and cycle performance. Meanwhile, the preparation method of the material is simple and easy to operate, low in production cost and beneficial to large-scale production.

Description

A kind of polyorganic modified core-shell structure Prussian blue potassium ion battery cathode material and preparation method thereof

technical field

The invention relates to a positive electrode material for a potassium ion battery and a preparation method thereof, in particular to a positive electrode material for a core-shell Prussian blue potassium ion battery modified by a polymer organic matter and a preparation method thereof.

Background technique

In the past two decades, with its excellent characteristics such as high capacity and good cycle stability, lithium-ion batteries have achieved large-scale commercial applications around the world, and have become the most important and widely used type of secondary batteries. . However, the extensive use of lithium-ion batteries in electric vehicles and energy storage equipment and the limited lithium resources have led to a sharp rise in the price of lithium salts, which has brought enormous pressure to the development and cost control of lithium-ion batteries. In this context, people began to look for low-cost, raw material-rich alternatives to replace lithium-ion batteries. Among a variety of emerging battery technologies, potassium-ion batteries are an ideal choice.

Prussian blue materials, as a class of positive electrode materials for potassium ion batteries, have an open frame structure with large ion channels and voids in the lattice, so they are one of the few hosts that can accommodate larger alkali metal ions such as sodium ions and potassium ions. One of the materials, it is very beneficial to the rapid intercalation and deintercalation of potassium ions. Benefiting from this structural feature, Prussian blue-like materials have been widely studied as one of the ideal cathode materials for potassium-ion batteries in the past period of time.

Chinese invention patent application CN 107226475 A proposes a potassium-ion battery cathode material based on Prussian blue, although its capacity can reach 90.7mAh/g, cycle 400 times, and the capacity retention rate is 90.37%; however, this material has poor rate performance. question.

SUMMARY OF THE INVENTION

In view of the deficiencies of existing materials, the present invention provides a novel high rate performance, high cycle performance polymer organic modified core-shell Prussian blue potassium ion battery positive electrode material and a preparation method thereof.

The technical solution of the present invention is as follows.

A polyorganic modified core-shell structure Prussian blue potassium ion battery cathode material, the expression is: K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ @polyorganic; where 0≤x ≤2, 0≤y≤2; the M ₁ and M ₂ are one or more of Fe, Mn, Co, Ni, Cu, and Zn, respectively, and the polymeric organic matter includes polydopamine, polypyrrole or polyaniline.

A method for preparing a positive electrode material for a core-shell structure Prussian blue potassium ion battery modified by a polymeric organic matter, comprising the following steps:

1. Preparation of K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ cathode material for potassium ion battery;

2. Ultrasonic dispersion of the K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ powder prepared in step 1 in deionized water to obtain suspension E;

3. Add the organic monomer salt into the suspension E, stir to dissolve and react to obtain the suspension F;

4. Ageing, centrifuging and drying the suspension F to obtain K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ @Polymeric organic cathode material powder, wherein 0≤x≤2,0 ≤y≤2; the M ₁ and M ₂ are one or more of Fe, Mn, Co, Ni, Cu, and Zn, respectively.

In the above method, the specific steps of step 1 are as follows:

(1) potassium ferrocyanide, potassium salt are dissolved in deionized water to be made into solution A;

(2) dissolving transition metal salt, reducing agent and complexing agent in deionized water to prepare solution B;

(3) solution B is added dropwise to solution A, and after stirring reaction, suspension C is obtained;

(4) adding transition metal salt, complexing agent, potassium ferrocyanide into suspension C simultaneously, stirring and reacting for a certain time to obtain suspension D;

(5) Ageing, centrifuging and drying the suspension D to obtain K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ positive electrode material powder (0≤x≤2, 0≤y≤2 ; The M ₁ and M ₂ are respectively one or more of Fe, Mn, Co, Ni, Cu, and Zn).

In the above method, in step (1), the potassium salt is one or more of potassium chloride, potassium acetate and potassium citrate; the mol ratio of the potassium ferrocyanide to the potassium salt is 1:10～ 200; the concentration of the potassium ferrocyanide in the A solution is 0.01-0.05M; the concentration of the potassium salt in the A solution is 0.1-10M.

In the above method, in step (2) and step (4), the transition metal salt is ferrous chloride, ferric chloride, ferrous sulfate, ferrous nitrate, manganese chloride, manganese sulfate, cobalt chloride, chlorine more than one of nickel chloride, nickel nitrate, nickel sulfate, copper chloride, copper nitrate, copper sulfate, zinc nitrate; the reducing agent is more than one of ascorbic acid, citric acid, iron powder; the complexing agent The concentration of one or more transition metal salts in potassium citrate, sodium citrate and potassium pyrophosphate in solution B is 0.01-0.05M; the concentration of the reducing agent in solution B is 0.01-0.05M; The concentration of the complexing agent in solution B is 0.02-0.5M; the concentration of the transition metal salt and potassium ferrocyanide in the suspension D is 0.001-0.1M; The concentration in liquid D is 0.001 to 0.1M.

In the above method, the dropwise addition rate in step (3) is 3-6 ml/min; the stirring time is 4-12 h; the reaction temperature is 0-75°C; the volume of solution A and solution B is The ratio is 1:1 to 1.5.

In the above method, the aging time in step (5) is 6-24 hours; the drying temperature is 60-120°C.

In the above method, the molar ratio of the transition metal salt in step (4) to the transition metal salt in step (2) is 1:1-20.

In the above method, the concentration of the organic monomer salt in the suspension F in step 3 is 0.0001-0.015M; the organic monomer salt includes dopamine hydrochloride, pyrrole or aniline.

In the above method, in step 4, the aging time is 6-24 hours; the drying temperature is 60-120°C.

Compared with the prior art, the advantages of the present invention are:

(1) The material K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ @Polymer organics prepared by the present invention is improved by using the stable K _y M ₂ Fe(CN) ₆ Prussian blue material The overall cycle stability of the material, and the use of polyorganic modification to improve the conductivity of the material, while taking into account the cycle performance and rate performance, is a new type of potassium-ion battery cathode material with application value and prospects.

(2) The method of the present invention has wide raw material sources, low price, simple synthesis process, low equipment requirements, and easy control and mastery of reaction conditions.

Description of drawings

Fig. 1 is the XRD spectrum of the material prepared in Example 1 of the present invention;

Fig. 2 is the rate performance diagram of the material prepared in Example 1 of the present invention;

3 is a cycle diagram of discharge specific capacity of the material prepared in Example 1 of the present invention at a current density of 200 mA/g.

Detailed ways

The present invention will be further described in detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto. For process parameters that are not particularly noted, reference may be made to conventional techniques.

Example 1

(1) dissolve 0.003mol potassium ferrocyanide and 0.3mol potassium chloride in 200mL deionized water to make solution A;

(2) 0.003mol ferrous chloride, 0.2g ascorbic acid, 0.006mol potassium citrate are dissolved in 200mL deionized water to make solution B;

(3) adding solution B to solution A at a rate of 3 to 6 ml/min under stirring, and stirring for 6 h to obtain suspension C;

(4) 0.0015mol nickel chloride, 0.0015mol potassium citrate, 0.0015mol potassium ferrocyanide were added to suspension C simultaneously, mixed uniformly and continuously stirred for 24h to obtain suspension D;

(5) The suspension D is aged, centrifuged and dried to obtain K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ powder (0≤x≤2, 0≤y≤2).

(6) take 1g of K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ powder prepared in step (5) and ultrasonically disperse it in 200 mL of deionized water to obtain suspension E;

(7) dissolving dopamine hydrochloride in suspension E, mixing well and stirring continuously for 24h to obtain suspension F, the concentration of dopamine hydrochloride is 0.015M;

(8) ageing, centrifuging and drying the suspension E to obtain K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ @polydopamine positive electrode material powder (0≤x≤2, 0≤y≤2);

(9) The above-obtained K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ @Polydopamine potassium ion battery positive electrode material is made into a battery according to the following method:

Mix the positive electrode material with the binder polyvinylidene fluoride (PVDF) and the conductive agent acetylene black according to the mass ratio of 7:2:1, add the solvent N-methylpyrrolidone (NMP), stir for 4-6h, and smear the slurry On a clean aluminum foil, put it in a vacuum oven at 80 °C to dry before use; use K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ @polydopamine pole piece as the positive electrode, potassium piece as the negative electrode, and Whatman GF /D was used as the separator, and 0.8 mol/L potassium hexafluorophosphate (KPF ₆ )/ethylene carbonate (EC): dimethyl carbonate (DEC) was used as the electrolyte to assemble a button battery.

Electrochemical performance test: The assembled button battery is tested for constant current charge and discharge to test the rate performance and cycle performance of the battery. The test voltage range is 2-4.5V.

Figure 1 is the XRD pattern of the material; its discharge specific capacity is 115mAh/g at a current density of 50mA/g, and its discharge specific capacity is 94mAh/g at a current density of 500mA/g, as shown in Figure 2; its discharge capacity at 200mA/g The capacity retention rate was 88.7% after 250 cycles at g current density, as shown in Figure 3.

The main electrochemical properties of the materials are shown in Table 1.

Example 2

(1) dissolve 0.003mol potassium ferrocyanide and 0.3mol potassium chloride in 200mL deionized water to make solution A;

(2) 0.003mol ferrous chloride, 0.2g ascorbic acid, 0.006mol potassium citrate are dissolved in 200mL deionized water to make solution B;

(3) adding solution B to solution A at a rate of 3 to 6 ml/min under stirring, and stirring for 6 h to obtain suspension C;

(4) 0.0015mol nickel chloride, 0.0015mol potassium citrate, 0.0015mol potassium ferrocyanide were added to suspension C simultaneously, mixed uniformly and continuously stirred for 24h to obtain suspension D;

(5) The suspension D is aged, centrifuged and dried to obtain K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ powder (0≤x≤2, 0≤y≤2).

(6) take 1g of K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ powder prepared in step (5) and ultrasonically disperse it in 200 mL of deionized water to obtain suspension E;

(7) dissolving dopamine hydrochloride in suspension E, mixing uniformly and stirring continuously for 24h to obtain suspension F, the concentration of dopamine hydrochloride is 0.0001M;

(8) ageing, centrifuging and drying the suspension E to obtain K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ @polydopamine positive electrode material powder (0≤x≤2, 0≤y≤2);

(9) The above-obtained K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ @polydopamine potassium ion battery positive electrode material is made into a battery.

The basic properties of the materials are shown in Table 1.

Example 3

(1) dissolve 0.003mol potassium ferrocyanide and 0.3mol potassium chloride in 200mL deionized water to make solution A;

(2) 0.003mol ferrous chloride, 0.2g ascorbic acid, 0.006mol potassium citrate are dissolved in 200mL deionized water to make solution B;

(3) adding solution B to solution A at a rate of 3 to 6 ml/min under stirring, and stirring for 6 h to obtain suspension C;

(4) 0.003mol nickel chloride, 0.003mol potassium citrate, 0.003mol potassium ferrocyanide were added to suspension C simultaneously, mixed uniformly and continuously stirred for 24h to obtain suspension D;

(5) The suspension D is aged, centrifuged and dried to obtain K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ powder (0≤x≤2, 0≤y≤2).

(6) take 1g of K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ powder prepared in step (5) and ultrasonically disperse it in 200 mL of deionized water to obtain suspension E;

(7) dissolving dopamine hydrochloride in suspension E, mixing well and stirring continuously for 24h to obtain suspension F, the concentration of dopamine hydrochloride is 0.015M;

(8) ageing, centrifuging and drying the suspension E to obtain K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ @polydopamine positive electrode material powder (0≤x≤2, 0≤y≤2);

(9) The above-obtained K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ @polydopamine potassium ion battery positive electrode material is made into a battery.

The basic properties of the materials are shown in Table 1.

Example 4

(1) dissolve 0.003mol potassium ferrocyanide and 0.3mol potassium chloride in 200mL deionized water to make solution A;

(2) dissolve 0.003mol ferrous chloride, 0.2g ascorbic acid, 0.006mol potassium citrate in 200mL deionized water to make solution B;

(3) adding solution B to solution A at a rate of 3 to 6 ml/min under stirring, and stirring for 6 h to obtain suspension C;

(4) 0.003mol nickel chloride, 0.003mol potassium citrate, 0.003mol potassium ferrocyanide were added to suspension C simultaneously, mixed uniformly and continuously stirred for 24h to obtain suspension D;

(5) Centrifuge and dry the suspension D to obtain K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ positive electrode material powder (0≤x≤2, 0≤y≤2);

(6) The above-obtained K _x FeFe(CN) ₆ @K _y NiFe(CN) ₆ potassium ion battery positive electrode material is made into a battery.

The basic properties of the materials are shown in Table 1.

Table 1 is the main performance table of each embodiment

The above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (8)

1. a kind of preparation method of the core-shell structure Prussian blue potassium ion battery positive electrode material modified by polymeric organic matter, is characterized in that, comprises the steps: 1. Preparation of K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ cathode material for potassium ion battery; 2. Ultrasonic dispersion of the K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ powder prepared in step 1 in deionized water to obtain suspension E; 3. Add the organic monomer salt into the suspension E, stir to dissolve and react to obtain the suspension F; 4. Ageing, centrifuging and drying the suspension F to obtain K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ @Polymeric organic cathode material powder, wherein 0≤x≤2,0 ≤y≤2; the M ₁ and M ₂ are respectively one or more of Fe, Mn, Co, Ni, Cu, and Zn; The specific steps of step 1 are as follows: (1) Dissolve potassium ferrocyanide and potassium salt in deionized water to prepare solution A; (2) Dissolve the transition metal salt, reducing agent and complexing agent in deionized water to prepare solution B; (3) Add solution B dropwise to solution A, and after stirring and reacting, obtain suspension C; (4) adding the transition metal salt, complexing agent and potassium ferrocyanide into suspension C at the same time, and stirring and reacting for a certain period of time to obtain suspension D; (5) Ageing, centrifuging and drying the suspension D to obtain K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ cathode material powder, where 0≤x≤2, 0≤y≤ 2; the M ₁ and M ₂ are respectively one or more of Fe, Mn, Co, Ni, Cu, and Zn; The expression of the polyorganic modified core-shell structure Prussian blue potassium ion battery cathode material is: K _x M ₁ Fe(CN) ₆ @K _y M ₂ Fe(CN) ₆ @polyorganic; where 0≤x ≤2, 0≤y≤2; the M ₁ and M ₂ are one or more of Fe, Mn, Co, Ni, Cu, and Zn, respectively, and the polymeric organic matter includes polydopamine, polypyrrole or polyaniline. 2. The method for preparing a positive electrode material for a core-shell structure Prussian blue potassium ion battery modified by a polymeric organic matter according to claim 1, wherein in step (1), the potassium salt is potassium chloride, potassium acetate, lemon One and more in potassium acid; The mol ratio of described potassium ferrocyanide and potassium salt is 1:10～200; The concentration of described potassium ferrocyanide in A solution is 0.01～0.05M; The concentration of potassium salt in solution A is 0.1~10 M. 3 . The method for preparing a positive electrode material for a core-shell structure Prussian blue potassium ion battery modified by a polymeric organic matter according to claim 1 , wherein in step (2) and step (4), the transition metal salt is chlorinated Ferrous iron, ferric chloride, ferrous sulfate, ferrous nitrate, manganese chloride, manganese sulfate, cobalt chloride, nickel chloride, nickel nitrate, nickel sulfate, copper chloride, copper nitrate, copper sulfate, zinc nitrate more than one kind; the reducing agent is more than one kind of ascorbic acid, citric acid, iron powder; the complexing agent is more than one kind of potassium citrate, sodium citrate, potassium pyrophosphate; the transition metal salt The concentration in solution B is 0.01~0.05M; the concentration of the reducing agent in solution B is 0.01~0.05M; the concentration of the complexing agent in solution B is 0.02~0.5M; the transition metal salt The concentration of potassium ferrocyanide and potassium ferrocyanide in the suspension D is 0.001~0.1 M; the concentration of the complexing agent in the suspension D is 0.001~0.1 M. 4. The method for preparing a positive electrode material for a core-shell structure Prussian blue potassium ion battery modified by a polymeric organic matter according to claim 1, wherein the dripping rate in step (3) is 3-6 ml/min; The stirring time is 4-12 h; the reaction temperature is 0-75° C.; the volume ratio of the solution A and the solution B is 1:1-1.5. 5 . The method for preparing a positive electrode material for a core-shell structure Prussian blue potassium ion battery modified by a polymeric organic matter according to claim 1 , wherein the aging time in step (5) is 6 to 24 hours; the drying The temperature is 60~120℃. 6 . The method for preparing a positive electrode material for a Prussian blue potassium ion battery with a core-shell structure modified by a polymeric organic matter according to claim 1 , wherein the transition metal salt in step (4) is the same as the transition metal salt in step (2) The molar ratio of the metal salt is 1:1~20. 7. the preparation method of the core-shell structure Prussian blue potassium ion battery positive electrode material modified according to claim 1, is characterized in that, in step 3, the concentration of organic monomer salt in suspension F is 0.0001～0.015 M ; The organic monomer salt includes dopamine hydrochloride, pyrrole or aniline. 8. the preparation method of the core-shell structure Prussian blue potassium ion battery positive electrode material modified by the polymeric organic matter according to claim 1, is characterized in that, in step 4, described ageing time is 6～24 hours; 60~120℃.

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