A high-performance glass-ceramic electrode material containing grid-like Fe3O4, its preparation method and application

Abstract

The present invention belongs to the technical field of electrochemical materials, and particularly relates to a high-performance glass-ceramic electrode material containing grid-like Fe3O4, a preparation method thereof, and an application thereof. The structure of the electrode material of the present invention is that grid-like Fe3O4 crystals are embedded in a glass matrix, which has high conductivity, provides more positions for the storage of Li+ ions, accelerates the movement of Li+ ions in the negative electrode, and inhibits the mechanical stress of the negative electrode material during the lithiation / delithiation process. The electrode material of the present invention can be used as a negative electrode material for lithium-ion batteries, has excellent reversible capacity and cycle stability. The present invention prepares an original glass sample by a traditional melting and cooling method, the process is simple and has no pollution to the environment, and has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical materials, and particularly relates to a high-performance glass-ceramic electrode material containing grid-like Fe3O4, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, with the aggravation of fossil fuel pollution and the rapid development of technology, people's demand for new energy storage devices has been increasing continuously. Since lithium-ion batteries have advantages such as high specific capacity and long cycle life, they have attracted people's attention since their birth. And they have been widely used in portable electronic devices such as mobile phones and laptops, especially in the field of new energy vehicles. Therefore, more and more researchers have joined the research on lithium-ion batteries, especially the research on anode materials. As the anode of lithium-ion batteries, inorganic oxide glasses have also become a research hotspot in recent years.

[0003] As the anode of lithium-ion batteries, glass materials have their unique structural advantages. First of all, the characteristics of no grain boundaries and the loose network structure make it easier for charge and lithium ions to move in amorphous materials. Secondly, the irregular network of glass materials is easy to rearrange during the process of ion insertion and extraction, which greatly improves the cycle stability of the battery. These two advantages are extremely crucial for us to prepare lithium-ion anode materials with high current density and safety and reliability. No matter what type of battery, the performance of electrode materials is of vital importance because they play a decisive role in the capacity of the battery. According to Faraday's law, the theoretical capacity of electrode materials is inversely proportional to their molecular weight. Among all known inorganic salt-based electrode materials, borates usually have much smaller molecular weights than phosphates, silicates, and sulfates because the B element is much lighter than P, Si, and S elements. Therefore, borates can provide higher capacities compared with other materials and should have strong potential as anode materials for rechargeable batteries with high energy density.

[0004] Iron oxides, such as Fe2O3 and Fe3O4, have relatively high theoretical capacities, 1007 and 925 mA h g -1 , and have the advantages of being environmentally friendly, abundant in content, and low in cost. They have been identified as one of the promising anode materials. However, due to poor conductivity, large specific volume changes, and easy particle agglomeration during the cycle, Fe2O3 and Fe3O4-based anodes have poor cycle stability, which seriously hinders their further development as anode materials for lithium-ion batteries. Summary of the Invention

[0005] To solve the problems existing in the above-mentioned prior art, the present invention provides a high-performance glass-ceramic electrode material containing grid-like Fe3O4, a preparation method thereof, and an application thereof. The present invention can greatly improve the reversible capacity and cycle stability of borate glass electrode materials.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] First, one of the objects of the present invention is to disclose a high-performance glass-ceramic electrode material containing grid-like Fe3O4, and the components are as follows:

[0008] (x)Fe2O3 - (100 - x)B2O3, x = 60, 70, 80, 90

[0009] Its structure is that Fe3O4 crystals with a grid-like structure are embedded in the glass matrix. As Figure 1 shown, it has high conductivity, provides more positions for the storage of Li+ ions, accelerates the movement of Li+ ions in the negative electrode, and inhibits the mechanical stress of the negative electrode material during the lithiation / delithiation process. The glass phase effectively buffers the volume expansion of the internal network structure of the material, and the presence of crystals provides a large number of lithium-ion energy storage sites, improving the conductivity and specific capacity of the electrode material, and effectively alleviating problems such as low specific capacity and poor cycle stability of traditional electrode materials.

[0010] Secondly, another object of the present invention is to disclose a preparation method of a high-performance glass-ceramic electrode material containing grid-like Fe3O4. Fe2O3 - B2O3 glass-ceramics are prepared by the traditional melting and cooling method, and the specific process steps are as follows:

[0011] Fully mix the raw materials, and transfer the mixture to an alumina crucible;

[0012] Then, the mixture in the alumina crucible is melted in a muffle furnace for 30 minutes at a temperature of 1473 to 1873 K (depending on the composition) to make the melt uniform;

[0013] Then pour the melt onto a preheated brass plate, and then transfer it to a muffle furnace and anneal at about 833 K for 2 hours;

[0014] Then turn off the furnace and let the sample cool naturally to room temperature, and the high-performance glass-ceramic electrode material containing grid-like Fe3O4 is obtained.

[0015] Thirdly, another object of the present invention is to disclose an electrode, which includes an active material, a conductive material, a binder, and a current collector. The binder bonds the active material and the conductive material to the current collector. The active material is the above-mentioned high-performance glass-ceramic electrode material containing grid-like Fe3O4.

[0016] Preferably, the conductive material is acetylene black and the binder is PVDF.

[0017] Preferably, the mass ratio of the active material, the conductive material, and the binder is 7:2:1.

[0018] Finally, the fourth object of the present invention is to disclose an ion battery, including the above-mentioned electrode, counter electrode, and electrolyte.

[0019] Beneficial effects

[0020] The present invention discloses a high-performance glass-ceramic electrode material containing grid-like Fe3O4, which can be used as the negative electrode material of a lithium-ion battery, has excellent reversible capacity and cycle stability, and prepares the original glass sample by the traditional melting and cooling method. The process is simple and pollution-free to the environment, and has good application prospects.

[0021] The present invention prepares a glass-ceramic containing grid-like Fe3O4 by the traditional melting and cooling method. The Fe3O4 crystals with a network structure are embedded in the glass matrix and have high conductivity, providing more positions for the storage of Li + ions, accelerating the movement of Li + ions in the negative electrode, and suppressing the mechanical stress of the negative electrode material during the lithiation / delithiation process. The glass phase effectively buffers the volume expansion of the internal network structure of the material, and the presence of crystals provides a large number of lithium-ion energy storage sites, improving the conductivity and specific capacity of the electrode material, and effectively alleviating problems such as low specific capacity and poor cycle stability of traditional electrode materials. Description of the drawings

[0022] Figure 1 It is the SEM image after acid treatment of Example 1 of the present invention;

[0023] Figure 2 It is the XRD pattern of the borate glass powder prepared in Example 1 and Example 4 of the present invention;

[0024] Figure 3 It is the electrochemical cycling performance graph of the borate glass powder prepared in Example 1 and Example 4 of the present invention as the negative electrode material of a lithium-ion battery;

[0025] Figure 4 It is the Mössbauer spectrum of the borate glass powder prepared in Example 1 of the present invention. Specific embodiments

[0026] Hereinafter, the present invention will be described in detail. Before the description, it should be understood that the terms used in this specification and the appended claims should not be construed as limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present invention on the basis of the principle that allows the inventor to appropriately define the terms for the best interpretation. Therefore, the description presented here is only a preferred example for illustrative purposes and is not intended to limit the scope of the present invention. Thus, it should be understood that other equivalent ways or improved ways can be obtained without departing from the spirit and scope of the present invention.

[0027] The following examples are only listed as examples of the implementation schemes of the present invention and do not constitute any limitation to the present invention. Those skilled in the art can understand that modifications within the scope of not deviating from the essence and concept of the present invention fall within the protection scope of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0028] Example 1

[0029] A preparation method of a high-performance glass-ceramic electrode material containing grid-like Fe3O4 includes the following steps:

[0030] Weigh appropriate amounts of iron(III) oxide (≥99%) and boric acid (≥99%) according to different molar ratios of the components. After mixing them evenly in a mortar, pour them into an alumina crucible. In a muffle furnace, under an air atmosphere, with a heating rate of 5 K per minute, melt, shape, anneal, and cool. Finally, a glass material is obtained; the melting temperature is 1923 K, the holding time is 30 min, the annealing temperature is 823 K, and the annealing time is 2 h, thus obtaining a glass-ceramic electrode material containing grid-like Fe3O4 (90FeB sample).

[0031] Detect the high-performance glass-ceramic electrode material containing grid-like Fe3O4 obtained in Example 1. The XRD pattern of the borate glass powder prepared in Example 1 is as Figure 1 shown, and the Mössbauer spectrum of the borate glass powder prepared in Example 1 is as Figure 3 shown. It can be seen from the XRD pattern and the Mössbauer spectrum that the precipitated crystal is mainly Fe3O4.

[0032] Grind the obtained glass into powder. Mix the sample powder, acetylene black, and PVDF in a mass ratio of 7:2:1 and put them into a 50 mL ball milling jar. Drop 2 ml of N-methylpyrrolidone into the mixed powder, then ball mill at a speed of 400 r / min for 4 h, and then smear the ball-milled slurry on a copper foil. Dry it under vacuum at 110 °C for 11 h, take it out after natural cooling, and use a punching machine to cut it into electrode sheets with a diameter of 12 mm. Assemble them in sequence in a glove box according to the order of positive electrode shell - electrolyte - electrode sheet - electrolyte - separator - lithium sheet - nickel mesh - electrolyte - negative electrode shell, and then seal the battery with a sealer to obtain a button half-cell. Finally, use a BlueTEC test system to test the charge-discharge performance of the lithium-ion battery.

[0033] Perform a cycling performance test on the iron borate glass (90FeB sample) at a charge-discharge voltage of 0.01 - 3.0 V and a current density of 1 A g-1. The electrochemical cycling performance diagram is as Figure 2As shown, the initial discharge specific capacity is 663 mAh g-1, and after 1000 cycles, the specific capacity is 503 mAh g-1.

[0034] Example 2

[0035] A preparation method of a high-performance glass-ceramic electrode material containing grid-like Fe3O4 includes the following steps:

[0036] Weigh appropriate amounts of iron(III) oxide (≥99%) and boric acid (≥99%) according to different molar ratios of the components. After mixing them evenly in a mortar, pour them into an alumina crucible. In a muffle furnace, under an air atmosphere, melt, shape, anneal, and cool at a heating rate of 5 K per minute. Finally, a glass material is obtained; the melting temperature is 1823 K, the holding time is 30 min, the annealing temperature is 823 K, and the annealing time is 2 h, thus obtaining the glass-ceramic electrode material containing grid-like Fe3O4 (80FeB sample).

[0037] Grind the obtained glass into powder. Mix the sample powder, acetylene black, and PVDF in a mass ratio of 7:2:1 and put them into a 50 mL ball milling jar. Drop 2 ml of N-methylpyrrolidone into the mixed powder, then ball mill at a speed of 400 r / min for 4 h, and then smear the ball-milled slurry on a copper foil. Dry it under vacuum at 110 °C for 11 h, take it out after natural cooling, and cut it into electrode sheets with a diameter of 12 mm using a punching machine. Assemble them in sequence in a glove box according to the order of positive electrode case - electrolyte - electrode sheet - electrolyte - separator - lithium sheet - nickel mesh - electrolyte - negative electrode case, and then seal the battery using a sealer to obtain a button half-cell. Finally, use a blue electrochemical workstation to test the charge-discharge performance of the lithium-ion battery. Perform a cycle performance test on the iron borate glass (80FeB sample) at a charge-discharge voltage of 0.01 - 3.0 V and a current density of 1 A g-1. Its initial discharge specific capacity is 779.5 mAh g-1, and after 1000 cycles, the specific capacity is 358.9 mAh g-1.

[0038] Example 3

[0039] A preparation method of a high-performance glass-ceramic electrode material containing grid-like Fe3O4 includes the following steps:

[0040] Weigh appropriate amounts of iron(III) oxide (≥99%) and boric acid (≥99%) according to different molar ratios of the components. After mixing them evenly in a mortar, pour them into an alumina crucible. In a muffle furnace, under an air atmosphere, melt, shape, anneal, and cool at a heating rate of 5 K per minute to finally obtain a glass material. The melting temperature is 1673 K, the holding time is 30 min, the annealing temperature is 823 K, and the annealing time is 2 h, thus obtaining a glass-ceramic electrode material (70FeB sample) containing grid-like Fe3O4.

[0041] Grind the obtained glass into powder. Mix the sample powder, acetylene black, and PVDF in a mass ratio of 7:2:1 and put them into a 50 mL ball milling jar. Drop 2 mL of N-methylpyrrolidone into the mixed powder, and then ball mill at a rotation speed of 400 r / min for 4 h. Then apply the ball milled slurry onto a copper foil. Dry it under vacuum at 110 °C for 11 h, take it out after natural cooling, and cut it into electrode sheets with a diameter of 12 mm using a punching machine. Assemble it in a glove box in the order of positive electrode shell - electrolyte - electrode sheet - electrolyte - separator - lithium sheet - nickel mesh - electrolyte - negative electrode shell, and then seal the battery using a sealing machine to obtain a button half-cell. Finally, use a BlueTEC test system to test the charge-discharge performance of the lithium-ion battery. Perform a cycling performance test on the iron borate glass (70FeB sample) at a charge-discharge voltage of 0.01 - 3.0 V and a current density of 1 A g-1. Its initial discharge specific capacity is 825.9 mAh g-1, and after 1000 cycles, the specific capacity is 311.2 mAh g-1.

[0042] Example 4

[0043] A preparation method of a high-performance glass-ceramic electrode material containing grid-like Fe3O4, comprising the following steps:

[0044] Weigh appropriate amounts of iron(III) oxide (≥99%) and boric acid (≥99%) according to different molar ratios of the components. After mixing them evenly in a mortar, pour them into an alumina crucible. In a muffle furnace, under an air atmosphere, melt, shape, anneal, and cool at a heating rate of 5 K per minute to finally obtain a glass material. The melting temperature is 1623 K, the holding time is 30 min, the annealing temperature is 823 K, and the annealing time is 2 h, thus obtaining a glass-ceramic electrode material (60FeB sample) containing grid-like Fe3O4.

[0045] Detect the high-performance glass-ceramic electrode material containing grid-like Fe3O4 obtained in Example 4. The XRD pattern of the borate glass powder prepared in Example 4 is as Figure 1 shown, and the Mössbauer spectrum of the borate glass powder prepared in Example 4 is as Figure 3As shown, it can be seen from the XRD pattern and Mössbauer spectrum that the precipitated crystals are mainly Fe2O3, but there is also a small amount of Fe3O4.

[0046] The obtained glass was ground into powder. The sample powder, acetylene black, and PVDF were mixed in a mass ratio of 7:2:1 and placed into a 50 mL ball milling jar. 2 mL of N-methylpyrrolidone was dropped into the mixed powder, and then ball milled at a rotation speed of 400 r / min for 4 h. Then the ball milled slurry was coated on a copper foil. It was dried under vacuum at 110 °C for 11 h, taken out after natural cooling, and cut into electrode sheets with a diameter of 12 mm using a punching machine. It was assembled in sequence in a glove box in the order of positive electrode case - electrolyte - electrode sheet - electrolyte - separator - lithium sheet - nickel mesh - electrolyte - negative electrode case, and then the battery was sealed using a sealing machine to obtain a button half-cell. Finally, the charge-discharge performance of the lithium-ion battery was tested using a BlueTEC test system. The cyclic performance of the iron borate glass (60FeB sample) was tested at a charge-discharge voltage of 0.01 - 3.0 V and a current density of 1 A g-1. The electrochemical cyclic performance diagram is as Figure 2 shown. The initial discharge specific capacity is 827 mAh g-1, and after 1000 cycles, the specific capacity is 287 mAh g-1.

[0047] The above results show that using the materials prepared by the present invention, it will be easy to prepare a high-performance glass-ceramic electrode material containing grid-like Fe3O4. The prepared glass-ceramic can be used as the negative electrode material for lithium-ion batteries and has excellent reversible capacity and cycle stability. The Fe3O4 crystals with a network structure are embedded in the glass matrix, having high conductivity, providing more positions for the storage of Li+ ions, accelerating the more uniform movement of Li+ ions in the anode, and suppressing the mechanical stress of the negative electrode material during the lithiation / delithiation process. The glass phase effectively buffers the volume expansion of the internal network structure of the material. The presence of crystals provides a large number of lithium-ion energy storage sites, improving the conductivity and specific capacity of the electrode material, and effectively alleviating problems such as low specific capacity and poor cycle stability of traditional electrode materials.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, for those of ordinary skill in the art, it is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent substitution on some of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions required to be protected by the present invention.

Claims

1. A glass-ceramic electrode material containing grid-like Fe3O4, characterized in that, Its components are as follows: (x)Fe2O3 - (100 - x)B2O3, where x = 60, 70, 80, 90; Fe3O4 crystals with a grid-like structure are embedded in the glass matrix.

2. A preparation method of the glass-ceramic electrode material containing grid-like Fe3O4 according to claim 1, characterized in that, Specifically, it includes the following technological steps: (1) Thoroughly mix the raw materials and transfer the mixture to an alumina crucible; (2) Then, melt the mixture in the alumina crucible in a muffle furnace to obtain a melt; (3) Then pour the melt onto a preheated brass plate and transfer it to the muffle furnace for annealing treatment; (4) Then turn off the furnace and let the sample cool naturally to room temperature to obtain the microcrystalline glass electrode material containing grid-like Fe3O4.

3. According to the preparation method of the glass-ceramic electrode material containing grid-like Fe3O4 according to claim 2, characterized in that, In step (2), the technological conditions for melting are: the temperature is 1473 to 1873 K, and melting is carried out for 30 minutes.

4. According to the preparation method of the glass-ceramic electrode material containing grid-like Fe3O4 according to claim 2, characterized in that, In step (3), the technological conditions for annealing are: annealing is carried out at 833 K for 2 hours.

5. An electrode, comprising an active material, a conductive material, a binder and a current collector, the binder bonding the active material and the conductive material to the current collector, characterized in that, The active material is the microcrystalline glass electrode material containing grid-like Fe3O4 described in claim 1.

6. According to the electrode according to claim 5, characterized in that, The conductive material is acetylene black, and the binder is PVDF.

7. According to the electrode according to claim 5, characterized in that, The mass ratio of the active material, conductive material, and binder is 7:2:

1.

8. An ion battery, characterized in that, It includes any one of the electrodes, counter electrodes, and electrolytes described in claims 5 - 7.

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