Preparation method of Mn-PBA electrode material

Abstract

The application discloses a preparation method of Mn-PBA electrode material, which comprises the following steps: (1) manganese acetate and sodium citrate are dissolved in deionized water to obtain solution A; potassium ferricyanide is dissolved in deionized water to obtain solution B; solution B is added into solution A under magnetic stirring; after stirring, aging is carried out at room temperature; (2) the product after reaction is washed with deionized water and ethanol several times in sequence; then, the product is dried overnight to obtain Mn-PBA powder; (3) an acid aqueous solution is added dropwise into Mn-PBA suspension to obtain a mixed solution, and the mixed solution is heated in an oil bath; the solution after oil bath heating is centrifuged and washed, and then is placed into an oven to be dried overnight to obtain Mn-PBA electrode material. The Mn-PBA electrode material with high electrochemical performance is prepared by adopting the co-precipitation method and acid etching method, the electrode material has a core-shell structure (cubic) with a hollow cavity, and the shell has through-hole pores; on the one hand, the electrode material exposes more reaction active sites (has rich active sites), so that the reaction activity of the electrode material is improved, and the reaction specific capacity is large; on the other hand, the volume expansion can be effectively buffered, so that the electrode material has good cycle stability.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a Mn-PBA electrode material. BACKGROUND

[0002] The development and use of clean energy (solar energy, wind energy) depend on cheap and safe energy storage battery systems. At present, lithium ion batteries are widely used in relatively high-end energy storage fields such as mobile phones, notebooks and electric vehicles, but are limited in large-scale energy storage fields. Firstly, the lithium element has a very low storage in the earth's crust (about 0.00002), which is insufficient to support grid-level energy storage applications. Secondly, the use of flammable carbonate electrolyte leads to a large safety hazard of lithium ion batteries. In contrast, lead-acid batteries based on aqueous electrolyte have the advantages of high safety and low price, and have been applied in the field of large-scale energy storage.

[0003] In the secondary battery system, the electrode material often plays a dominant role, especially for the electrode material of the large-scale energy storage battery, which needs to meet the characteristics of low cost, high performance and sustainability. The current aqueous electrode material is roughly divided into four categories: oxides, phosphates, organic materials and Prussian blue. Among them, the oxide structure is compact and is limited to Li and Na battery systems. The phosphate has a high molecular weight, resulting in a low specific capacity (60-120 mAh g -1 ). Organic materials can store a variety of ion systems, but usually have low conductivity and low tap density, which limits the actual application. In contrast, Prussian blue has good application prospects, not only has an open crystal structure and reversible redox process, but also is suitable for the universal storage of a variety of ions, and is simple to synthesize, which can be prepared by a simple liquid-phase precipitation method, avoiding high-energy processes such as ball milling and high-temperature calcination, thereby reducing the preparation cost of the material. However, the capacity of Prussian blue is limited, and the conductivity and cycle life are poor, and the structure stability is reduced due to the insufficient redox sites and the existence of vacancy defects in the structure, thereby causing serious capacity decay and hindering the practical application of the electrode material. SUMMARY

[0004] The purpose of the application is to provide a preparation method of a Mn-PBA (manganese-iron-based Prussian blue) electrode material. The electrode material prepared by the method has two redox site active centers, Mn 3+ / Mn 2+ redox activity, which can provide additional capacity, thereby having good conductivity and cycle stability.

[0005] Technical scheme: The preparation method of the Mn-PBA electrode material provided by the application comprises the following steps:

[0006] (1) Mn(Ac)2 and Na3C6H5O7 are dissolved in deionized water to obtain solution A; K3Fe(CN)6 is dissolved in deionized water to obtain solution B; solution B is added to solution A under magnetic stirring; after stirring, aging is carried out at room temperature; during the aging process, the impurities entrapped in the precipitate are removed, and the particle size distribution is more uniform;

[0007] (2) the reacted product is filtered and washed with deionized water and ethanol several times in sequence; then, Mn-PBA powder is obtained after drying overnight;

[0008] (3) an acid solution is added dropwise into the Mn-PBA suspension to obtain a mixed solution, and the mixed solution is heated in an oil bath; the solution heated in the oil bath is centrifuged and washed, and then dried in an oven overnight to obtain the Mn-PBA electrode material.

[0009] In step (1), the mass concentration of Mn(Ac)2 in solution A is 3.6-3.7 mg / mL, and the mass concentration of Na3C6H5O7 is 5.5-5.6 mg / mL; the mass concentration of K3Fe(CN)6 in solution B is 2.2-2.3 mg / mL.

[0010] In step (1), the stirring time is not less than 1 min.

[0011] In step (1), the aging time is not more than 24 h.

[0012] In step (1), the drying temperature is 60-65℃.

[0013] In step (3), the acid is tannic acid, oxalic acid, glycine or tartaric acid.

[0014] In step (3), the mass concentration of the acid in the acid solution is 1.35-30 mg / mL.

[0015] In step (3), the mass concentration of the Mn-PBA powder in the Mn-PBA suspension is 0.3-0.35 mg / mL.

[0016] In step (3), the oil bath heating temperature is 85-90℃, and the oil bath heating time is 6-6.5 h. The higher the temperature, the faster the etching rate, but if the temperature is too high, the acid will be decomposed, and some unstable compounds will be produced.

[0017] In step (3), the drying temperature is 60-65℃.

[0018] The application adopts potassium ferricyanide as an electrode active material, provides rich cyan group electron-withdrawing groups, and manganese acetate provides Mn ions, so that the prepared Mn-PBA electrode material has two redox centers, greatly promoting the transmission of electrons, that is, the conductivity of the electrode material.

[0019] Beneficial effects: Compared with the prior art, the application has the following obvious advantages: the Mn-PBA electrode material with high electrochemical performance is prepared by the co-precipitation method and acid etching method, the electrode material has a core-shell structure (cubic) with a hollow cavity, and the shell has through-hole pores, on the one hand, the electrode material exposes more reaction active sites (has rich active sites), thereby improving the reaction activity and the specific capacity of the reaction; on the other hand, the volume expansion can be effectively buffered, so that the electrode material has good cycle stability; at the same time, the capacity and cycle life of the Prussian blue electrode material are improved by introducing Mn vacancies to inhibit Jahn-Teller distortion; the Mn-PBA electrode material prepared by the application can be widely applied in the fields of aqueous batteries, supercapacitors or energy storage devices. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The XRD pattern of the Mn-PBA electrode material prepared in Example 1 of the application;

[0021] Figure 2 The SEM pattern of the Mn-PBA electrode material prepared in Example 1 of the application;

[0022] Figure 3 The TEM pattern of the Mn-PBA electrode material prepared in Example 1 of the application;

[0023] Figure 4 The XPS full spectrum pattern of the Mn-PBA electrode material prepared in Example 1 of the application;

[0024] Figure 5 The cyclic voltammogram of the Mn-PBA electrode material prepared in Example 1 of the application at different scanning rates;

[0025] Figure 6 The charge-discharge curve of the Mn-PBA electrode material prepared in Example 1 of the application at a current density of 1 Ag -1

[0026] Figure 7 The rate curve of the Mn-PBA electrode material prepared in Example 1 of the application;

[0027] Figure 8 The long cycle curve of the Mn-PBA electrode material prepared in Example 1 of the application at a current density of 10 Ag -1 ​​

[0028] Figure 9 The mass specific capacity comparison chart of the Mn-PBA electrode material prepared for the present application examples 1-4 at a current density of 1 A g -1

[0029] Figure 10 The mass specific capacity comparison chart of the Mn-PBA electrode material prepared for the present application examples 1 and comparative examples 1-3 at a current density of 1 A g -1

[0030] Figure 11 The soft pack battery display chart assembled with the Mn-PBA electrode material prepared for the present application example 1 as the positive electrode. DETAILED DESCRIPTION

[0031] Example 1

[0032] The preparation method of the Mn-PBA electrode material of the present application specifically comprises the following steps:

[0033] (1) Mn-PBA powder is prepared by using co-precipitation method: 147 mg of manganese acetate and 220 mg of sodium citrate are dissolved in 40 mL of deionized water to obtain solution A; 132 mg of potassium ferricyanide is dissolved in 60 mL of deionized water to obtain solution B; solution B is added to solution A under magnetic stirring, and after stirring for 1 min, it is aged at room temperature for 24 hours; after the reaction is completed, the product is washed with deionized water and ethanol several times in turn; and finally it is placed in a 60°C oven to dry overnight to obtain Mn-PBA powder;

[0034] (2) Preparation of Mn-PBA suspension: 30 mg of Mn-PBA powder is added to 100 mL of deionized water, and the mixture is stirred to obtain Mn-PBA suspension;

[0035] (3) Preparation of tannic acid aqueous solution: 1.5 g of tannic acid powder is added to 50 mL of deionized water, and the mixture is stirred to obtain tannic acid aqueous solution;

[0036] (4) Preparation of Mn-PBA electrode material: the tannic acid aqueous solution is added dropwise to the Mn-PBA suspension to obtain a uniform Mn-PBA and tannic acid mixed solution, and the mixed solution is heated in an oil bath; then the oil bath-heated solution is centrifuged and washed, and placed in a 60°C oven to dry overnight to obtain Mn-PBA electrode material.

[0037] Figure 1 The XRD chart of the Mn-PBA electrode material can be seen to correspond to the PDF card of KMnFe(CN)6·2H2O, indicating that manganese-iron-based Prussian blue is successfully prepared. Figure 2 ​​The scanning electron microscope image of the Mn-PBA electrode material can be observed to form a cubic nanoparticle structure. Figure 3 The transmission electron microscope image of the Mn-PBA electrode material can be observed to form a cubic and hollow structure, and there is an obvious gap between the inner and outer shells. Figure 4 The full spectrum of the Mn-PBA electrode material shows that there is a manganese element in the Prussian blue material, which again proves the successful preparation of the Mn-PBA electrode material.

[0038] Figures 5 to 8 The electrochemical performance characterization diagram of the Mn-PBA electrode material of Example 1. Mn-PBA, CNT and PVDF are mixed and ground in a mass ratio of 6:3:1, and coated on carbon paper, and placed in an electrolyte composed of 1M (NH4) 2SO4+0.1M ZnSO4 for electrochemical test, and it is found that the Mn-PBA electrode has excellent electrochemical performance.

[0039] From Figure 5 The CV curve of the material can be observed to have a pair of obvious redox peaks, which corresponds to the charge and discharge platform of the GCD curve ( Figure 6 ). In addition, the electrode has an initial discharge capacity of 173mAh g -1 at a current density of 1A g -1 . Figure 7 The material shows excellent rate performance, and the discharge capacity still remains 48mAh g -1 at a current density of 20A g -1 . From Figure 8 The long cycle curve can be observed to have a capacity retention rate of 67.8% after 10000 charge and discharge cycles.

[0040] Example 2

[0041] The preparation method of the Mn-PBA electrode material of the application specifically comprises the following steps:

[0042] (1) The Mn-PBA powder is prepared by a coprecipitation method: 147mg of manganese acetate and 220mg of sodium citrate are dissolved in 40mL of deionized water to obtain solution A; 132mg of potassium ferricyanide is dissolved in 60mL of deionized water to obtain solution B; solution B is added to solution A under magnetic stirring, and after stirring for 1min, it is aged at room temperature for 24 hours; after the reaction is completed, the product is washed with deionized water and ethanol several times in turn; and finally it is placed in a 60℃ oven to dry overnight to obtain the Mn-PBA powder;

[0043] (2) Preparation of Mn-PBA suspension: 30 mg of Mn-PBA powder was added to 100 mL of deionized water, and stirred to obtain a Mn-PBA suspension;

[0044] (3) Preparation of tannic acid aqueous solution: 0.1134 g of oxalic acid powder was added to 50 mL of deionized water, and stirred to obtain an oxalic acid aqueous solution;

[0045] (4) Preparation of Mn-PBA electrode material: the oxalic acid aqueous solution was added dropwise to the Mn-PBA suspension to obtain a uniform Mn-PBA and oxalic acid mixed solution, and the mixed solution was heated in an oil bath; then the solution heated in the oil bath was centrifuged and washed, and was placed in a 60℃ oven to dry overnight to obtain the Mn-PBA electrode material.

[0046] Example 3

[0047] The preparation method of the Mn-PBA electrode material of the application specifically comprises the following steps:

[0048] (1) Preparation of Mn-PBA powder by co-precipitation method: 147 mg of manganese acetate and 220 mg of sodium citrate were dissolved in 40 mL of deionized water to obtain solution A; 132 mg of potassium ferricyanide was dissolved in 60 mL of deionized water to obtain solution B; solution B was added to solution A under magnetic stirring, and after stirring for 1 min, it was aged at room temperature for 24 hours; after the reaction was completed, the product was washed with deionized water and ethanol several times in sequence; and finally it was placed in a 60℃ oven to dry overnight to obtain the Mn-PBA powder;

[0049] (2) Preparation of Mn-PBA suspension: 30 mg of Mn-PBA powder was added to 100 mL of deionized water, and stirred to obtain a Mn-PBA suspension;

[0050] (3) Preparation of tannic acid aqueous solution: 0.0675 g of glycine powder was added to 50 mL of deionized water, and stirred to obtain a glycine aqueous solution;

[0051] (4) Preparation of Mn-PBA electrode material: the glycine aqueous solution was added dropwise to the Mn-PBA suspension to obtain a uniform Mn-PBA and glycine mixed solution, and the mixed solution was heated in an oil bath; then the solution heated in the oil bath was centrifuged and washed, and was placed in a 60℃ oven to dry overnight to obtain the Mn-PBA electrode material.

[0052] Example 4

[0053] The preparation method of the Mn-PBA electrode material of the application specifically comprises the following steps:

[0054] (1) Mn-PBA powder was prepared by co-precipitation method: 147 mg of manganese acetate and 220 mg of sodium citrate were dissolved in 40 mL of deionized water to obtain solution A; 132 mg of potassium ferricyanide was dissolved in 60 mL of deionized water to obtain solution B; solution B was added to solution A under magnetic stirring, and after stirring for 1 min, it was aged at room temperature for 24 h; after the reaction was completed, the product was washed with deionized water and ethanol several times in turn; and finally it was placed in a 60 °C oven to dry overnight to obtain Mn-PBA powder;

[0055] (2) Mn-PBA suspension was prepared: 30 mg of Mn-PBA powder was added to 100 mL of deionized water, and the mixture was stirred to obtain Mn-PBA suspension;

[0056] (3) Tannic acid aqueous solution was prepared: 0.135 g of tartaric acid powder was added to 50 mL of deionized water, and the mixture was stirred to obtain tannic acid aqueous solution;

[0057] (4) Mn-PBA electrode material was prepared: the tannic acid aqueous solution was added dropwise to the Mn-PBA suspension to obtain a uniform Mn-PBA and tannic acid mixed solution, and the mixed solution was heated in an oil bath; then the oil bath-heated solution was centrifuged and washed, and was placed in a 60 °C oven to dry overnight to obtain Mn-PBA electrode material.

[0058] Comparative Example 1

[0059] Comparative Example 1 and Example 1 were prepared by the same method, and the only difference was that the Mn-PBA suspension was not mixed with the tannic acid aqueous solution, i.e., steps (2) to (4) were not performed.

[0060] Comparative Example 2

[0061] Comparative Example 2 and Example 1 were prepared by the same method, and the only difference was that sodium citrate was not added in step (1).

[0062] Comparative Example 3

[0063] Comparative Example 3 and Example 1 were prepared by the same method, and the only difference was that 200 mg of manganese acetate was added in step (1).

[0064] To verify the technical effect, the Mn-PBA electrode materials prepared by different acid etching in Examples 1 to 4 were mixed with CNT and PVDF at a mass ratio of 6:3:1, and were coated on carbon paper, which was placed in a mixed electrolyte composed of 1 M (NH4)2SO4 and 0.1 M ZnSO4, and was subjected to electrochemical test, and the specific capacity was compared at a current density of 1 Ag -1 Figure 9 ​As can be seen, the Mn-PBA electrode material obtained by etching with tannic acid has the highest discharge specific capacity and the best electrochemical performance.

[0065] To verify the technical effect, the Mn-PBA electrode materials prepared in Example 1 and Comparative Examples 1-3 were mixed with CNT and PVDF at a mass ratio of 6:3:1, ground, and coated onto carbon paper. Electrochemical tests were then conducted in an electrolyte solution consisting of 1M (NH4)2SO4 and 0.1M ZnSO4 at a current density of 1 A g. -1 Comparison of specific capacity at different times, from Figure 10 As can be seen, the Mn-PBA electrode material prepared in Example 1 has the highest discharge specific capacity and the best electrochemical performance.

[0066] To verify the technical effect, the Mn-PBA electrode material from Example 1 was used as the positive electrode, and a soft-pack battery was prepared using 1M(NH4)2SO4 + 0.1MZnSO4 as the electrolyte. Figure 11 As shown, the pouch battery successfully lit the light bulb.

Claims

1. A method for preparing a Mn-PBA electrode material, characterized in that, Specifically comprising the following steps: (1) Preparation of Mn-PBA powder by co-precipitation method: 147 mg of manganese acetate and 220 mg of sodium citrate were dissolved in 40 mL of deionized water to obtain solution A; 132 mg of potassium ferricyanide was dissolved in 60 mL of deionized water to obtain solution B; solution B was added to solution A under magnetic stirring, and after stirring for 1 min, it was aged at room temperature for 24 hours; after the reaction was completed, the product was washed with deionized water and ethanol several times in turn; finally, it was placed in a 60°C oven to dry overnight to obtain Mn-PBA powder; (2) Preparation of Mn-PBA suspension: 30 mg of Mn-PBA powder was added to 100 mL of deionized water and stirred thoroughly to obtain a Mn-PBA suspension; (3) Preparation of tannic acid aqueous solution: 1.5 g of tannic acid powder was added to 50 mL of deionized water and stirred thoroughly to obtain a tannic acid aqueous solution; (4) Preparation of Mn-PBA electrode material: the tannic acid aqueous solution was added dropwise to the Mn-PBA suspension to obtain a uniform Mn-PBA and tannic acid mixed solution, which was heated in an oil bath; then the oil bath-heated solution was centrifuged and washed, and was placed in a 60°C oven to dry overnight to obtain Mn-PBA electrode material.

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