CN113809308B

CN113809308B - P3 type manganese cobalt potassium nickelate material and preparation method and application thereof

Info

Publication number: CN113809308B
Application number: CN202111101421.XA
Authority: CN
Inventors: 周小四; 段丽平
Original assignee: Nanjing Normal University
Current assignee: Nanjing Normal University
Priority date: 2021-09-18
Filing date: 2021-09-18
Publication date: 2023-04-18
Anticipated expiration: 2041-09-18
Also published as: CN113809308A

Abstract

The invention provides a P3 type K _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ A preparation method of a porous cuboid (c-KMCNO) material, the material obtained by the preparation method and the application of the material as a potassium ion battery anode material comprise the following steps: 1) Dissolving manganese acetate, cobalt acetate, nickel acetate and potassium nitrate in a mixed solvent of deionized water and ethanol; 2) Dissolving oxalic acid dihydrate in a mixed solvent of deionized water and ethanol; 3) Adding the mixed metal acetate solution 1) into the oxalic acid solution 2) and stirring; 4) Drying the precipitate obtained in the step 3) and then carrying out primary calcination in air; 5) And (2) calcining the product obtained in the step (4) in an oxygen atmosphere again to obtain the c-KMCNO material, compared with the prior art, the method has the advantages of simple process, green and environment-friendly used raw materials, and excellent electrochemical performance of the prepared c-KMCNO material, and is a promising potassium ion battery anode material.

Description

P3 type manganese cobalt potassium nickelate material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of electrode materials, and particularly relates to a P3 type K _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ Porous cuboid (c-KMCNO) material, and preparation method and application thereof.

Background

Lithium ion batteries have high energy density, long cycle life, and high operating voltage, and have become the primary power source for recent applications in electric vehicles, portable electronics, and even stationary energy storage systems. However, the scarcity and price rise of lithium is detrimental to large-scale energy storage. In recent years, potassium ion batteries have attracted a great deal of interest as a promising alternative, which is similar to the electrochemical mechanism of lithium ion batteries, low in price, and high in natural abundance of potassium. Furthermore, the oxidation-reduction potential (K/K) of potassium ⁺ : -2.93V) to sodium (Na/Na) ⁺ : 2.71V) and thus the potassium ion battery has higher energy density and also has greater potential in practical application.

The manganese-based layered transition metal oxide is an ideal positive electrode material of the potassium ion battery due to high theoretical capacity, high oxidation-reduction potential, low toxicity and easy large-scale synthesis. However, the development of manganese-based layered transition metal oxides is limited by poor cycling stability and rate capability. This is due to the large size of the K + ions and the volume change during the intercalation/deintercalation of the K + ions. During cycling, the non-uniform volume changes create large internal strains that lead to particle breakage, one of the well-recognized mechanisms for drastically attenuating the capacity of potassium ion batteries.

For improving K of manganese-based layered transition metal oxide cathode material ⁺ Storage Properties, in recent years, researchers have tried various methods including the addition of two or more transition metals such as Ni, mn, fe, co and electrochemically inactive elements such as Mg, al, cu, etc., e.g., K _0.83 Ni _0.05 Mn _0.95 O ₂ 、K _0.54 Co _0.5 Mn _0.5 O ₂ 、K _0.75 Mn _0.8 Ni _0.1 Fe _0.1 O ₂ 、K _0.45 Mn _0.75 Co _0.1 Ni _0.1 Al _0.05 O ₂ 、K _0.7 Mn _0.7 Mg _0.3 O ₂ And K _0.3 Mn _0.9 Cu _0.1 O ₂ The doping of the elements stabilizes the crystal structure, thus ensuring the stable circulation and being easy to effectively K ⁺ And (5) storing. Another common method for improving electrochemical performance is morphological design, such as designing a porous structure, which can reduce K + diffusion distance and relieve K by enlarging the contact area between the active material and the electrolyte ⁺ The material structure collapse and cracking caused by the continuous embedding and releasing process can improve the reversible capacity and the cycling stability of the electrode.

Disclosure of Invention

In order to solve the problems, the invention discloses a c-KMCNO material as well as a preparation method and application thereof, wherein the preparation method is green and environment-friendly, the process is simple, and the obtained compound has excellent electrochemical performance.

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

first, the present invention provides a P3 type K _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ The preparation method of the porous cuboid material comprises the following steps:

(1) Dissolving manganese acetate, cobalt acetate, nickel acetate and potassium nitrate in a mixed solvent of deionized water and ethanol to obtain a mixed solution A;

(2) Dissolving oxalic acid dihydrate in a mixed solvent of deionized water and ethanol to obtain a mixed solution B;

(3) Adding the mixed solution A into the mixed solution B, and stirring to generate a precipitate;

(4) Drying the precipitate obtained in the step (3) and then carrying out primary calcination in the air;

(5) After the preliminary calcination, the mixture is calcined again in the atmosphere of high-purity oxygen to obtain the P3 type K _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ A porous cuboid material.

Further, in the step (1), the molar ratio of manganese acetate to cobalt acetate to nickel acetate to potassium nitrate is 7.6 to 8.4; the concentration of the manganese acetate in the mixed solution A is 0.070 to 0.011molL ⁻¹ 。

Further, the volume ratio of the water to the ethanol in the step (1) is 1 to 3-5.

Further, the volume ratio of water to ethanol in the step (2) is 1 to 3-5.

Further, the concentration of oxalic acid dihydrate in the mixed solution B in the step (2) is 17.3 to 24gL ⁻¹ 。

Further, the method of preliminary calcination in step (4) includes the following steps: drying the precipitate obtained in the step (3), and then placing the dried precipitate in a muffle furnace to obtain a product 5 ^o Cmin ⁻¹ At a rate of 500 deg.f ^o And keeping for 4h after C.

Further, the method of re-calcining in the step (5) comprises the following steps: putting the product obtained in the step (4) into a tube furnace for 2 times ^o Cmin ⁻¹ To a rate of 850 ^o C, keeping for 10 to 20h, and then keeping for 2 ^o Cmin ⁻¹ After cooling to 250 c, the product was quickly transferred to a glove box under argon atmosphere for storage to avoid reaction of the product with moisture and carbon dioxide in the air.

Secondly, the invention provides P3 type K prepared by the preparation method _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ A porous cuboid material.

Again, the invention provides P3 type K _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ The porous cuboid material is applied as the anode material of the potassium ion battery.

Finally, the invention also provides a composition comprising P3 type K _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ The potassium ion battery anode material is made of a porous cuboid material.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the preparation method of the c-KMCNO material provided by the invention is characterized in that metal acetate and oxalic acid are subjected to coprecipitation in a mixed solvent of ethanol and water, and then the c-KMCNO material is obtained after treatments such as drying, calcination and the like. In the traditional coprecipitation method, the obtained potassium oxalate is dissolved in water, so that potassium element cannot be effectively precipitated together with other metal elements; in addition, the process uses an ethanol-mediated coprecipitation method, avoids the use of expensive surfactants to form a unique appearance, has simple process and green and environment-friendly raw materials, and adopts 2 when the catalyst is calcined again ^o Cmin ⁻¹ The temperature rise speed of the material enables the c-KMCNO material to generate a better crystal form.

The c-KMCNO material provided by the invention is a P3 type porous cuboid structure with the width of 2-3 mu m and the length of 10-12 mu m, and the P3 type structure has a larger triangular prism space and can provide more K ⁺ Occupies the site, accelerates the ion conduction and reduces the energy barrier of the potassium ion battery in the charging and discharging process. The unique porous cuboid structure of the c-KMCNO material obviously reduces K ⁺ Diffusion distance of (2) to relieve continuous K ⁺ Internal strain caused by intercalation and deintercalation, thereby improving reaction kinetics and structural integrity, and improving cyclic stability of c-KMCNOSexual and rate capability.

The c-KMCNO material provided by the invention has excellent electrochemical performance, and can be used as a positive electrode material of a potassium ion battery, wherein the c-KMCNO content is 20mAg ⁻¹ Providing 94.5mAhg ⁻¹ Reversible capacity at 500mAg ⁻¹ Providing 49.5mAhg ⁻¹ Reversible capacity at 100mAg ⁻¹ The low-temperature-resistant and high-temperature-resistant composite material shows good cycle stability in the next 300 cycles, and the capacity retention rate is 63%. In addition, the potassium ion full cell of c-KMCNO// soft carbon is 100mAg ⁻¹ The lower panel showed a reversible capacity of 54.3mAhg ⁻¹ The capacity retention after 100 cycles was 81.1%. Therefore, the porous cuboid material has good application potential as a high-performance low-cost cathode material.

Drawings

FIG. 1 is an XRD pattern of a c-KMCNO material according to the invention;

FIG. 2 is a schematic structural diagram of the c-KMCNO material of the invention, wherein TM is elements of manganese, cobalt and nickel, K is potassium element, and O is oxygen element;

FIG. 3 is an XPS spectrum of c-KMCNO material, mn, co and Ni, wherein a is the XPS full spectrum of c-KMCNO material, b is the XPS spectrum of Mn, c is the XPS spectrum of Co, and d is the XPS spectrum of Ni;

FIG. 4 is an SEM image of a c-KMCNO material of the invention;

FIG. 5 is a TEM image and an HRTEM image of the c-KMCNO material of the present invention, wherein a is a TEM image of the c-KMCNO material, and b and c are HRTEM images of the c-KMCNO material;

FIG. 6 is a cyclic voltammogram of a c-KMCNO electrode of the present invention;

FIG. 7 is a charge/discharge curve diagram of a c-KMCNO electrode according to the present invention;

FIG. 8 is a graph of the rate capability of c-KMCNO and i-KMCNO of the present invention at different current densities;

FIG. 9 is a graph of charge and discharge curves of c-KMCNO of the present invention at different current densities;

FIG. 10 is a graph of the cycling performance of c-KMCNO and i-KMCNO of the present invention.

FIG. 11 is an XRD pattern of comparative example 2 product c-KMCNO of the present invention.

Detailed Description

The technical solutions provided by the present invention will be described in detail with reference to specific examples, which should be understood that the following specific embodiments are only illustrative and not limiting the scope of the present invention.

Example 1

Preparation of c-KMCNO material:

(1) Adding 5.25 parts of manganese acetate, cobalt acetate, nickel acetate and potassium nitrate into a mixed solvent of 20mL of deionized water and 60mL of ethanol according to a molar ratio of 8 ⁻¹ ；

(2) Dissolving oxalic acid dihydrate in a mixed solvent of 20mL of deionized water and 60mL of ethanol, wherein the concentration of the oxalic acid dihydrate in the solution is 24gL ⁻¹ ；

(3) Then adding mixed metal acetate solution into oxalic acid mixed solution, stirring for 5 hr, and mixing the obtained oxalic acid precursor MC ₂ O ₄ (M represents K, mn, co and Ni mixed metal ions) precipitation and drying;

(4) In an air atmosphere, with 5 ^o Cmin ⁻¹ At a rate of 500 deg.f ^o C, calcining for 4 hours;

(5) Again in a high purity oxygen atmosphere, with 2 ^o Cmin ⁻¹ To a rate of 850 ^o Calcining for 10 hours and then adding 2 ^o Cmin ⁻¹ After cooling to 250 c, the product was quickly transferred to a glove box under argon atmosphere for storage to avoid reaction with moisture and carbon dioxide in the air.

FIG. 2 is a schematic structural diagram of c-KMCNO material, wherein TM is manganese, cobalt and nickel, K is potassium, O is oxygen, and K occupies TMO ₂ Triangular prism positions between the slabs.

c-characterization of KMCNO materials:

FIG. 1 is an XRD pattern of the c-KMCNO material, which indicates that c-KMCNO is a P3 type structure; FIG. 3a is an XPS survey of c-KMCNO showing the presence of K, mn, co, ni and O; FIGS. 3b, 3c and 3d are XPS spectra of Mn, co and Ni, respectively, demonstrating Mn, ni and Co in c-KMCNO at +3/+4, +2 and +3 valence states.

The size, morphology and microstructure of the resulting c-KMCNO material were analyzed using SEM, TEM and HRTEM images. FIG. 4 is an SEM image of c-KMCNO material, showing that c-KMCNO is a uniform micron cuboid structure with a width of 2-3 μm and a length of 10-12 μm. FIG. 5a is a TEM image of c-KMCNO showing that c-KMCNO is a micron cuboid structure with pores, indicating that carbon dioxide released from oxalate during calcination produces a large number of pores; FIGS. 5b-c are HRTEM images of c-KMCNO showing that the lattice spacing of the (006) lattice plane of c-KMCNO is 0.32nm.

Electrochemical performance test

c-KMCNO prepared in this example was uniformly mixed with carbon black and polyvinylidene fluoride (PVDF) by grinding in a mass ratio of 75 ^o And (C) vacuum drying for 12h. Using 1mol L ⁻¹ KPF ₆ The solution of Ethylene Carbonate (EC) and Propylene Carbonate (PC) (volume ratio 1). The electrochemical performance was tested using a CR2032 cell. The cell assembly was carried out in a glove box filled with argon atmosphere. Constant current charge and discharge test of the battery at room temperature, using a blue CT2001A multi-channel battery test system, at 1.5-4.0V (vs.K) ⁺ and/K) in a fixed voltage range. Cyclic Voltammetry (CV) was tested using a PARSTAT 4000 electrochemical workstation with a CV at 0.1mVs ⁻¹ The sweep speed of (a) was used, and the specific performance was shown in fig. 6-10.

FIG. 6 shows that the c-KMCNO electrode is at 1.5-4.0V (vs. K) ⁺ /K) voltage interval, scan rate 0.1mVs ⁻¹ The cyclic voltammetry curves of the first three circles are basically overlapped, which shows that the material has good reversibility; FIG. 7 shows that c-KMCNO is at 1.5-4.0V (vs. K) ⁺ /K) charge/discharge diagram of voltage interval with current density of 20mAg ⁻¹ The first-circle discharge capacity reaches 94.5mAhg ⁻¹ (ii) a FIG. 8 shows amorphous K of c-KMCNO and comparative material _0.5 M _0.8 C _0.1 N _0.1 O ₂ (i-KMCNO) graph of rate capability at different current densities, even thoughAt 500mAg ⁻¹ The capacity of the c-KMCNO can still reach 49.5mAhg at high current density ⁻¹ (ii) a FIG. 9 is a charge-discharge curve of c-KMCNO at different current densities; FIG. 10 shows that c-KMCNO is at 100mAg ^-1 A graph of cycling performance at current density showing that the capacity retention remains 63% after 300 cycles of c-KMCNO cycling.

Example 2

(1) Adding 4.75 parts of manganese acetate, cobalt acetate, nickel acetate and potassium nitrate into a mixed solvent of 20mL of deionized water and 80mL of ethanol according to a molar ratio of 7.6 ⁻¹ ；

(2) Dissolving oxalic acid dihydrate in a mixed solvent of 20mL of deionized water and 80mL of ethanol, wherein the concentration of the oxalic acid dihydrate in the solution is 20.2gL ⁻¹ ；

(5) Again in a high purity oxygen atmosphere, with 2 ^o Cmin ⁻¹ To a rate of 850 ^o Calcining for 10 hours and then 2 ^o Cmin ⁻¹ After cooling to 250 c, the product was quickly transferred to a glove box under argon atmosphere for storage to avoid reaction with moisture and carbon dioxide in the air.

The prepared KMCNO material was subjected to structural characterization and electrochemical performance test in the same manner as in example 1, and the results were substantially the same as in example 1 and are shown in table 1.

Example 3

(1) Adding manganese acetate, cobalt acetate, nickel acetate and potassium nitrate into a mixed solvent of 20mL of deionized water and 100mL of ethanol according to a molar ratio of 8.4 ⁻¹ ；

(2) Dissolving oxalic acid dihydrate in a mixed solvent of 20mL of deionized water and 100mL of ethanol, wherein the concentration of the oxalic acid dihydrate in the solution is 17.3gL ⁻¹ ；

(3) Then adding mixed metal acetate solution into oxalic acid mixed solution, stirring for 5 hr, and mixing the synthesized oxalic acid precursor MC ₂ O ₄ (M represents K, mn, co and Ni mixed metal ions) precipitation and drying;

The KMCNO material thus obtained was subjected to structural characterization and electrochemical performance test in the same manner as in example 1, and the results were substantially the same as in example 1 and are shown in table 1.

Example 4

(1) Adding 4.75 parts of manganese acetate, cobalt acetate, nickel acetate and potassium nitrate into a mixed solvent of 20mL of deionized water and 60mL of ethanol according to a molar ratio of 7.6 ⁻¹ ；

(5) Again in a high purity oxygen atmosphere, with 2 ^o Cmin ⁻¹ To a rate of 850 ^o Calcining for 15 hours and then adding 2 ^o Cmin ⁻¹ After cooling to 250 c, the product was quickly transferred to a glove box under argon atmosphere for storage to avoid reaction with moisture and carbon dioxide in the air.

Example 5

(2) Dissolving oxalic acid dihydrate in a mixed solvent of 20mL of deionized water and 60mL of ethanol, wherein the concentration of the oxalic acid dihydrate in the solution is 22.8gL ⁻¹ ；

(5) Again in a high purity oxygen atmosphere, with 2 ^o Cmin ⁻¹ To a rate of 850 ^o Calcining for 20 hours and then adding 2 ^o Cmin ⁻¹ After cooling to 250 c, the product was quickly transferred to a glove box under argon atmosphere for storage to avoid reaction with moisture and carbon dioxide in the air.

Comparative example 1

Amorphous K _0.5 M _0.8 C _0.1 N _0.1 O ₂ Preparation of (i-KMNCO):

(1) Adding 5.25 parts of manganese acetate, cobalt acetate, nickel acetate and potassium nitrate into 20mL of deionized water according to a molar ratio of 8 ⁻¹ ；

(3) Then adding mixed metal acetate solution into oxalic acid mixed solution, stirring for 5 hr, and mixing the obtained oxalic acid precursor MC ₂ O ₄ (M represents K, mn, co, ni mixed metal ions) precipitation and drying

(4) In an air atmosphere, with 5 ^o Cmin ⁻¹ Is raised to 500 ^o Calcining for 4 hours under C;

(5) Again in a high purity oxygen atmosphere, with 2 ^o Cmin ⁻¹ To a rate of 850 ^o Calcining for 10 hours and then 2 ^o Cmin ⁻¹ After cooling to 250 ℃, the final product i-KMCNO was stored in a glove box.

Electrochemical performance test

i-KMCNO prepared in this example was uniformly mixed with carbon black and polyvinylidene fluoride (PVDF) by grinding in a mass ratio of 75 ^o And C, vacuum drying for 12 hours. Using 1mol L ⁻¹ KPF ₆ The volume ratio of Ethylene Carbonate (EC) to Propylene Carbonate (PC) (1). The electrochemical performance was tested using a CR2032 cell. The cell assembly was performed in a glove box filled with argon atmosphere. Constant current charge and discharge test of the battery at room temperature, using a blue CT2001A multi-channel battery test system at 1.5-4.0V (vs. K) ⁺ and/K) in a fixed voltage range.

FIG. 8 is a graph of multiplying power performance of c-KMCNO and i-KMCNO under different current densities, wherein the reversible capacity of c-KMNCO is higher than that of i-KMNCO; FIG. 1 shows a schematic view of a0 is c-KMCNO and i-KMCNO at 100mAg ⁻¹ A plot of cycling performance at current density showing that the cycling stability of i-KMCNO is far behind that of c-KMCNO; as can be seen from the above tests, i-KMNCO has far lower electrochemical performance than c-KMNCO.

Comparative example 2

(5) Again in a high purity oxygen atmosphere, at 5 deg.C ^o Cmin ⁻¹ To a rate of 850 ^o Calcining for 10 hours and then 5 ^o Cmin ⁻¹ After cooling to 250 ℃, the product was transferred to a glove box under argon atmosphere for storage.

The structural characterization and electrochemical performance test of the KMCNO material prepared in the same manner as in example 1 showed in table 1, and the XRD results shown in fig. 11 showed that the crystallinity was inferior to that of example 1.

TABLE 1 electrochemical Performance data

The technical means disclosed in the scheme of the invention are not limited to the technical means disclosed in the above embodiments, but also include the technical means formed by any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and such improvements and modifications are also considered to be within the scope of the present invention.

Claims

1. P3 type K _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ The preparation method of the porous cuboid material is characterized by comprising the following steps of:

(4) Drying the precipitate obtained in the step (3) and then carrying out primary calcination in air;

(5) After the preliminary calcination, the mixture is calcined again in the atmosphere of high-purity oxygen to obtain the P3 type K _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ A porous cuboid material; the P3 type K _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ The width of the porous cuboid material is 2-3 mu m, and the length of the porous cuboid material is 10-12 mu m;

the method for preliminary calcination in the step (4) comprises the following steps: drying the precipitate obtained in the step (3), and then placing the dried precipitate in a muffle furnace to obtain a product 5 ^o Cmin ⁻¹ Is raised to 500 ^o Keeping for 4h after C;

the method for calcining again in the step (5) comprises the following steps: putting the product obtained in the step (4) into a tube furnace, and feeding the product into the tube furnace by 2 ^o Cmin ⁻¹ To a rate of 850 ^o C, keeping for 10 to 20h, and then, keeping for 2 ^o Cmin ⁻¹ After cooling to 250 ℃, the product was transferred to a glove box under argon atmosphere for storage.

2. Preparation according to claim 1The method is characterized in that the molar ratio of manganese acetate to cobalt acetate to nickel acetate to potassium nitrate in the step (1) is 7.6 to 8.4; the concentration of the manganese acetate in the mixed solution A is 0.070 to 0.011molL ⁻¹ 。

3. The preparation method according to claim 1, wherein the volume ratio of water to ethanol in the step (1) is 1 to 3-5.

4. The preparation method according to claim 1, wherein the volume ratio of water to ethanol in the step (2) is 1 to 3 inclusive to 5 inclusive.

5. The method according to claim 1, wherein the concentration of oxalic acid dihydrate in the mixed solution B in the step (2) is 17.3 to 24gL ⁻¹ 。

6. P3 type K prepared by the preparation method of any one of claims 1 to 5 _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ A porous cuboid material.

7. P3 type K according to claim 6 _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ The porous cuboid material is applied as the anode material of the potassium ion battery.

8. Comprising the P3 type K of claim 6 _0.5 Mn _0.8 Co _0.1 Ni _0.1 O ₂ A potassium ion battery anode material made of a porous cuboid material.