High-capacity high-entropy oxyfluoride material as well as preparation method and application thereof

Abstract

The invention relates to a high-capacity and high-entropy oxyfluoride material as well as a preparation method and application thereof, and relates to the field of structural energy storage composite materials. Comprising the following steps: dissolving a nickel source, an M source, an iron source, a manganese source and a magnesium source in an alcohol solvent, and then adding a fluorine substitution agent and lithium carbonate to form slurry; carrying out primary ball milling on the slurry, and then drying to obtain a fluorine-oxygen compound material precursor; and taking the oxyfluoride material precursor, calcining in an inert atmosphere, naturally cooling, and carrying out secondary ball milling to obtain the oxyfluoride material. Through chemical and physical mixing, high-temperature pyrolysis and other processes, different types of metal oxides and fluorine substitution agents are prepared into the layered oxyfluoride which is small in particle size, stable in structure, high in capacity and high in entropy; the oxyfluoride material is stable in circulation, high in capacity and good in energy storage density, and can meet the requirements of electrode materials of structural lithium ions.

Description

Technical Field

[0001] The present invention relates to the field of structural energy storage composite materials, and particularly to a fluorine oxide material with high capacity and high entropy, and a preparation method and application thereof. Background Art

[0002] The electrification of transportation is one of the key technologies for reducing carbon dioxide emissions. At present, lithium-ion batteries (LIBs) are widely used in energy storage devices in daily life due to their excellent energy storage effect, especially in new energy electric vehicles and electric aircraft that have become increasingly popular in recent years. However, the energy density of the most advanced LIBs is still not satisfactory, which greatly hinders the endurance of electric transportation. To solve this problem, researchers have developed structural energy storage composite devices (SESCDs), which include two aspects: storing energy and bearing loads. Therefore, an excellent structural energy storage composite device must have two functions at the same time: (1) having excellent energy storage effect; (2) being able to be used as a component for bearing loads. That is to say, SESCDs can be used as structural components to withstand mechanical loads, and at the same time can provide sufficient energy storage capacity; therefore, in the future, it will be attractive not only for electric vehicles, but also for the structural and energy requirements in many fields such as building materials.

[0003] At present, the limited theoretical capacity and energy storage density of common commercial electrode materials have greatly hindered the development of structural energy storage composites. The lithium cobalt oxide and ternary materials with high specific capacity and energy storage density are greatly restricted in their application production and development due to resource shortage and high price. Therefore, it is very necessary and extremely challenging to develop electrode materials for structural energy storage composites with low cost, cobalt-free or less cobalt, high capacity and excellent energy storage density. In view of this, the present invention provides a fluorine oxide material with high capacity and high entropy, and a preparation method and application thereof. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a fluorine oxide material with high capacity and high entropy, and a preparation method and application thereof. The purpose is to solve the problems such as insufficient capacity, unstable structure and low energy storage density of cobalt-containing materials.

[0005] The technical solution of the present invention for solving the above technical problems is as follows:

[0006] In the first aspect, a preparation method of a fluorine oxide material with high capacity and high entropy includes the following steps:

[0007] Dissolve a nickel source, an M source, an iron source, a manganese source, and a magnesium source in an alcohol solvent, and then add a fluorine substitute and lithium carbonate to form a slurry; the M source is at least one of cobalt oxide, copper oxide, and chromium trioxide; perform first ball milling on the slurry, and then dry it to obtain a fluorine oxide material precursor;

[0008] Take the precursor of the fluorine oxide compound material, calcine it in an inert atmosphere (such as Ar), and perform secondary ball milling after natural cooling to obtain the fluorine oxide compound material.

[0009] Based on the above technical solutions, the present invention can also be improved as follows.

[0010] Furthermore, the nickel source includes nickel oxide; the iron source includes iron(III) oxide; the manganese source includes manganese monoxide; the magnesium source includes magnesium oxide; the alcohol solvent includes ethanol; the fluorine substitute includes lithium fluoride. Among them, the amount of the alcohol can be added as needed.

[0011] Furthermore, the molar ratio of nickel ions in the nickel source, M ions in the M source, iron ions in the iron source, manganese ions in the manganese source, and magnesium ions in the magnesium source is 1-2:1-2:1-2:1-2:1-2;

[0012] The ratio of the fluorine substitute to the total mass of the nickel source, the M source, the iron source, the manganese source, and the magnesium source is 1:0.5-1; lithium carbonate accounts for 8%-10% of the total mass of the nickel source, the M source, the iron source, the manganese source, and the magnesium source;

[0013] The parameters of the first ball milling are: 300-400 rmp / min, and the time is 8-12 h;

[0014] The parameters of the drying are: the temperature is 60-80 °C, and the time is 12-24 h; vacuum drying is used for drying;

[0015] The parameters of the calcination are: the heating rate is 3-8 °C / min, the temperature is 800-900 °C, and the treatment time is 2-5 h; for example, place it in a porcelain boat and transfer it to a tube furnace for calcination;

[0016] The parameters of the second ball milling are: 300-500 rmp / min, and the time is 5-8 h.

[0017] In the second aspect, a high-capacity and high-entropy fluorine oxide compound material, and the fluorine oxide compound material is prepared by the preparation method described above.

[0018] In the third aspect, an application of a high-capacity and high-entropy fluorine oxide compound material, and the high-capacity and high-entropy fluorine oxide compound material is used to prepare a structural energy storage composite device.

[0019] Furthermore, the preparation of the structural energy storage composite device includes any one of a structural lithium-ion battery and a structural capacitor.

[0020] In the fourth aspect, a positive electrode, and the positive electrode includes the high-capacity and high-entropy fluorine oxide compound material described above.

[0021] In a fifth aspect, a method for preparing a positive electrode includes the following steps:

[0022] Adding an active material, a binder, and a conductive agent to a solvent to obtain an electrode slurry, wherein the active material is a high-capacity high-entropy fluorine oxide material as described above; coating the electrode slurry on carbon fiber, and after drying, obtaining a positive electrode. The solvent can be N-methylpyrrolidone or the like.

[0023] Furthermore, the mass ratio of the active material, the binder, and the conductive agent is 6-8:1-2:1-2; the total mass ratio of the active material, the binder, and the conductive agent to the mass of the N-methylpyrrolidone solvent is 2-3:1;

[0024] The thickness of the electrode slurry coated on the carbon fiber is 40-60 μm.

[0025] The binder can be polyvinylidene fluoride (PVDF); the conductive agent can be conductive carbon black (Super P).

[0026] In a sixth aspect, a structural lithium-ion battery includes the positive electrode as described above. The structural lithium-ion battery is a layered porous structure material.

[0027] Among them, the method for preparing the battery cell of the structural lithium-ion battery includes the following steps:

[0028] Stirring epoxy resin and a pore-forming agent at a mass ratio of 1:2-4 for 20-40 min, then adding a curing agent (the mass ratio of resin to curing agent is 100:57.5) and stirring again for 20-30 min, filtering to remove bubbles, and then introducing the above mixture into a vacuum bag by vacuum infusion; curing in two steps, first heating to 130 °C for 60 min, then heating to 180 °C and holding for 30 min, with a heating rate of 5 °C / min for both, and then naturally cooling to room temperature; obtaining a cured material, removing the cured material, soaking it in water for 24-48 h (changing water every 3-5 h); finally injecting a lithium-ion secondary electrolyte (LB-266), assembling and sealing it with the positive and negative electrodes, standing for 24-36 h to obtain a battery cell, and then performing electrochemical tests.

[0029] The epoxy resin can be 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (TETRAD-C), the pore-forming agent can be polyethylene glycol 200 (PEG200), and the curing agent can be 4,4'-diaminodicyclohexylmethane.

[0030] The present invention has the following beneficial effects:

[0031] (1) The present invention uses a nickel source, an M source, an iron source, a manganese source, and a magnesium source as raw materials, and combines a fluorine substitute. Through processes such as chemical and physical mixing and high-temperature pyrolysis, different types of metal oxide salts and the fluorine substitute are prepared to form a layered fluorine oxide compound with small particle size, stable structure, high capacity, and high entropy.

[0032] (2) The reaction system of the present invention contains a fluorine substitute, which replaces part of the oxygen to play a role in stabilizing the lattice structure, improves the battery cycle performance, and realizes the stability of the structure during the charge and discharge process. Therefore, through the optimization of the substitute and process parameters, a layered structure with sufficient interfacial bonding and stable structure is achieved, which is beneficial to the stability of the structure during the charge and discharge process, the formation of the interfacial film at the interface, and the intercalation of lithium ions, improving the capacity and cycle stability.

[0033] (3) The process of the present invention is simple, has a short cycle, is easy to control, has a low synthesis temperature and low cost, and is easy to promote and use.

[0034] (4) The present invention applies the prepared fluorine oxide compound material to the electrode material of the structural lithium ion. This electrode material can achieve stable cycling, high capacity, and good energy storage density, meeting the requirements of the electrode material for structural lithium ions.

[0035] (5) The present invention coats the high-capacity and high-entropy fluorine oxide compound electrode active material on carbon fibers to form a positive electrode of a lithium ion structural energy storage composite material with sufficient interfacial bonding, a small interlayer thickness in the structure battery, stable structure, and high capacity. This not only expands the types of positive electrode active materials for structural lithium ions and develops new positive electrode materials with excellent performance, but also can achieve controllable fluorine substitution amount, sufficient interfacial bonding, and stable structure, effectively overcoming the problems of insufficient capacity, unstable structure, and low energy storage density of existing cobalt-containing materials. Description of the Drawings

[0036] Figure 1 is the scanning electron microscope image of the high-capacity and high-entropy fluorine oxide compound material prepared in Example 1 of the present invention;

[0037] Figure 2 is the charge-discharge capacity diagram of the high-capacity and high-entropy fluorine oxide compound materials and high-entropy oxide electrode materials prepared in Example 1, Example 2, Example 3, and Example 4 of the present invention.

[0038] Figure 3 is the capacity retention curve diagram of the high-capacity and high-entropy fluorine oxide compound material prepared in Example 1 and the high-capacity and high-entropy oxide compound material prepared in Example 2 of the present invention. Detailed Embodiments

[0039] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. For those without specific technologies or conditions indicated in the examples, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product specifications. For reagents or instruments without the manufacturer indicated, they are all conventional products that can be purchased through regular channels.

[0040] Example 1:

[0041] This example relates to a preparation method of a structured lithium-ion battery, and the steps are as follows:

[0042] (1) Preparation of high-entropy fluorine oxide active material

[0043] Nickel oxide, cobalt oxide, iron(III) oxide, manganese(II) oxide, and magnesium oxide in equimolar ratio are dissolved in 10 mL of ethanol. Additionally, LiF with a mass ratio of 1:1 (the mass sum of nickel oxide, cobalt oxide, iron(III) oxide, manganese(II) oxide, and magnesium oxide to the mass of LiF) and lithium carbonate accounting for 8% of the total mass of nickel oxide, cobalt oxide, iron(III) oxide, manganese(II) oxide, and magnesium oxide are added. The above slurry is put into a ball mill for the first ball milling at 350 rmp / min for 10 h (ethanol will volatilize during this process, and attention should be paid to sealing), vacuum-dried overnight at 70 °C to obtain a fluorine oxide material precursor. Take the above fluorine oxide material precursor and place it in a porcelain boat and transfer it to a tube furnace. Under an Ar atmosphere, it is heat-treated at 900 °C for 2 h with a heating rate of 5 °C / min. After natural cooling, it is put into a ball mill for the second ball milling at 500 rmp / min for 8 h to obtain a high-capacity and high-entropy fluorine oxide material.

[0044] (2) Preparation of positive / negative structure electrodes

[0045] The positive and negative active materials, binder (PVDF), and conductive agent (carbon black) are added in sequence in an N-methylpyrrolidone solvent according to a mass ratio of 8:1:1. The weight ratio of the solvent to the sum of the binder (PVDF), conductive agent (carbon black), and active materials is 2.6:1. The positive active material is the high-capacity and high-entropy fluorine oxide material prepared by the present invention, and the negative active material is an energy-type graphite material. Then, the stirred slurry is coated on carbon fiber by a blade coating method with a thickness of 40 μm and dried at 90 °C until all the solvent volatilizes; finally, it is cut according to the required size to obtain the positive and negative electrodes.

[0046] (3) Preparation of a structured lithium-ion battery (i.e., a lithium-ion structured energy storage composite structure battery)

[0047] The tetra-functional epoxy resin and the pore-forming agent PEG200 were fully stirred for 20 min at a mass ratio of 1:3. Then, the curing agent PACM was added (the mass ratio of the resin to the curing agent was 100:57.5), and stirring was continued for 20 min. The mixture was filtered to remove air bubbles, and then the above mixture was introduced into a vacuum bag by vacuum infusion. Two-step curing was carried out. First, the temperature was raised to 130 °C for 60 min, and then the temperature was raised to 180 °C and maintained for 30 min. The heating rate was 5 °C / min in both cases. Subsequently, it was naturally cooled to room temperature. The cured battery cell was taken off and soaked in water for 24 h (changing water every 5 h). Finally, a lithium-ion secondary electrolyte (LB-266) was injected, assembled with the positive and negative electrodes, sealed, and left standing for 24 h for electrochemical testing. Its discharge capacity at a current density of 10 mA / g was 259.48 mAh / g, the Coulomb efficiency was greater than 99%, and the capacity remained 59.34% after 275 cycles. (Table 1, Figure 1 , Figure 2 , Figure 3 ).

[0048] Example 2: Control Example

[0049] This example relates to a preparation method of a structural lithium-ion battery, and the steps are as follows:

[0050] (1) Preparation of high-entropy oxide active material

[0051] Nickel oxide, cobalt oxide, iron(III) oxide, manganese(II) oxide, and magnesium oxide in equimolar ratio were dissolved in 10 mL of ethanol, and 8% lithium carbonate by mass of the sum of the masses of nickel oxide, cobalt oxide, iron(III) oxide, manganese(II) oxide, and magnesium oxide was additionally added. The above slurry was put into a ball mill for the first ball milling at 350 rmp / min for 10 h (it should be noted that ethanol will volatilize during this process, and sealing is required). The obtained slurry was vacuum-dried at 70 °C overnight to obtain a precursor of the oxide material. The precursor of the oxide material was placed in a porcelain boat and transferred to a tubular furnace. Under an Ar atmosphere, it was heat-treated at 900 °C for 2 h with a heating rate of 5 °C / min. After natural cooling, it was put into a ball mill for grinding at 500 rmp / min for 8 h to obtain the oxide material.

[0052] (2) Preparation of positive / negative structure electrodes

[0053] The positive and negative active materials, binder (PVDF), and conductive agent (carbon black) were added in sequence in an N-methylpyrrolidone solvent at a mass ratio of 8:1:1, where the weight ratio of the solvent to the materials was 2.6:1. The positive active material was the oxide material, and the negative active material was an energy-type graphite material. Then, the stirred slurry was coated on carbon fiber with a thickness of 40 μm by blade coating and dried at 90 °C until all the solvent evaporated. Finally, it was cut to the required size to obtain the positive and negative electrodes.

[0054] (3) Preparation of lithium-ion structure energy storage composite structure battery

[0055] The tetrafunctional epoxy resin and pore-forming agent PEG200 were fully stirred at a mass ratio of 1:3 for 20 minutes, and then the curing agent PACM (mass ratio of resin to curing agent is 100:57.5) was added and stirred again for 20 minutes, and the bubbles were removed by filtration, and then the above mixture was introduced into a vacuum bag by vacuum infusion. Two-step curing, first heated to 130°C for 60 minutes, and then heated to 180°C for 30 minutes, the heating rate was 5°C / min, and then naturally cooled to room temperature. Remove the cured battery cell and soak it in water for 24 hours (change the water every 5 hours). Finally, inject lithium ion secondary electrolyte (LB-266), assemble with positive and negative electrodes, seal, and stand for 24 hours for electrochemical testing. The discharge capacity of the battery at a current density of 10mA / g is 183.52mAh / g, the coulomb efficiency is greater than 98%, and the capacity is retained at 45.06% after 275 cycles. (Table 1, Figure 2 , Figure 3 ).

[0056] Embodiment three:

[0057] This embodiment relates to a method for preparing a structured lithium-ion battery, and the steps are as follows:

[0058] (1) Preparation of Cobalt-free High Entropy Oxyfluoride Active Materials

[0059] Replace the cobalt oxide in Example 1 with copper oxide or chromium trioxide, and the other steps are as follows:

[0060] Dissolve nickel oxide, copper oxide, manganese oxide, and magnesium oxide in 10 mL of ethanol in an equal molar ratio, and add LiF with a mass ratio of 1:1 (the mass of nickel oxide, copper oxide, iron oxide, manganese oxide, and magnesium oxide) and 8% of lithium carbonate. Put the above slurry into a ball mill for the first ball milling, 350 rpm, and run for 10 hours (ethanol will volatilize during this process, so be careful to seal it), and vacuum dry it at 70°C overnight to obtain a fluorine oxide material precursor. Take the above fluorine oxide material precursor and place it in a porcelain boat and transfer it to a tube furnace. Heat treat it at 900°C for 2 hours under an Ar atmosphere, with a heating rate of 5°C / min. After natural cooling, put it into a ball mill for the second ball milling, 500 rpm, and run for 8 hours to obtain a high-capacity and high-entropy fluorine oxide material.

[0061] (2) Preparation of positive / negative electrode structure

[0062] The positive and negative active materials, binder (PVDF), and conductive agent (carbon black) are added to N-methylpyrrolidone solvent in a mass ratio of 8:1:1. The weight ratio of the solvent to the sum of the binder (PVDF), conductive agent (carbon black), and active materials is 2.6:1. The positive active material is a high-capacity and high-entropy fluorine oxide material, and the negative active material is a lithium metal sheet composite material. Then, the well-stirred slurry is coated on carbon fiber with a blade at a thickness of 40 μm and dried at 90 °C until all the solvent evaporates. Finally, it is cut to the required size to obtain the positive and negative electrodes.

[0063] (3) Preparation of a structural lithium-ion battery (i.e., a lithium-ion structural energy storage composite structure battery)

[0064] The tetrafunctional epoxy resin and the pore-forming agent PEG200 are fully stirred for 20 min in a mass ratio of 1:3. Then, the curing agent PACM is added (the mass ratio of the resin to the curing agent is 100:57.5), and stirring is continued for 20 min. Bubbles are removed by filtration, and then the above mixture is introduced into a vacuum bag by vacuum infusion. Two-step curing is carried out. First, the temperature is raised to 130 °C for 60 min, and then it is raised to 180 °C and maintained for 30 min. The heating rate is 5 °C / min in both cases. Subsequently, it is naturally cooled to room temperature. The cured battery cell is taken down and soaked in water for 24 h (changing water every 5 h). Finally, a lithium-ion secondary electrolyte (LB-266) is injected, assembled with the positive and negative electrodes, sealed, and left standing for 24 h for electrochemical testing. Its discharge capacity at a current density of 10 mA / g is 196.61 mAh / g (Table 1 and Figure 2 ).

[0065] Example 4:

[0066] Compared with Example 3, copper oxide is replaced with chromium trioxide, and the rest is the same as in Example 3. Its discharge capacity at a current density of 10 mA / g is 234.47 mAh / g (Table 1 and Figure 2 ).

[0067] Table 1 Discharge specific capacities of Examples 1 to 4 of the present invention

[0068]

[0069] In summary, the fluorine substitute contained in the reaction system of the present invention replaces part of the oxygen to play a role in stabilizing the lattice structure, improving the battery cycle performance, and realizing the stability of the structure during the charge and discharge process. Therefore, through the optimization of the substitute and process parameters, a layered structure with sufficient interfacial bonding and stable structure is achieved, which is beneficial to the stability of the structure during the charge and discharge process, the formation of the interfacial film at the interface, and the intercalation of lithium ions, improving the capacity and cycle stability.

[0070] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A preparation method of a high-capacity and high-entropy fluorine oxide material, characterized in that, It includes the following steps: Dissolve a nickel source, an M source, an iron source, a manganese source, and a magnesium source in an alcohol solvent, and then add a fluorine substitute and lithium carbonate to form a slurry; the M source is at least one of cobalt oxide, copper oxide, and chromium trioxide; subject the slurry to the first ball milling, and then dry it to obtain a precursor of the fluorine oxide compound material; Take the precursor of the fluorine oxide compound material, calcine it in an inert atmosphere, and perform the second ball milling after natural cooling to obtain the fluorine oxide compound material.

2. The preparation method of a high-capacity and high-entropy fluorine oxide material according to claim 1, characterized in that, The nickel source includes nickel oxide; the iron source includes iron(III) oxide; the manganese source includes manganese(II) oxide; the magnesium source includes magnesium oxide; the alcohol solvent includes ethanol; the fluorine substitute includes lithium fluoride.

3. The preparation method of a high-capacity and high-entropy fluorine oxide material according to claim 1, characterized in that, The molar ratio of nickel ions in the nickel source, M ions in the M source, iron ions in the iron source, manganese ions in the manganese source, and magnesium ions in the magnesium source is 1-2:1-2:1-2:1-2:1-2; The ratio of the fluorine substitute to the total mass of the nickel source, the M source, the iron source, the manganese source, and the magnesium source is 1:0.5-1; lithium carbonate accounts for 8%-10% of the total mass of the nickel source, the M source, the iron source, the manganese source, and the magnesium source; The parameters of the first ball milling are: 300-400 rmp / min, and the time is 8-12 h; The parameters of the drying are: the temperature is 60-80 °C, and the time is 12-24 h; The parameters of the calcination are: the heating rate is 3-8 °C / min, the temperature is 800-900 °C, and the treatment time is 2-5 h; The parameters of the second ball milling are: 300-500 rmp / min, and the time is 5-8 h.

4. A high-capacity and high-entropy fluorine oxide material, characterized in that, The fluorine oxide compound material is prepared by the preparation method according to any one of claims 1 to 3.

5. Application of a high-capacity and high-entropy fluorine oxide material, characterized in that, Use the high-capacity high-entropy fluorine oxide compound material according to claim 4 to prepare a structural energy storage composite device.

6. The application of a high-capacity and high-entropy fluorine oxide material according to claim 5, characterized in that, The preparation of the structural energy storage composite device includes any one of a structural lithium-ion battery and a structural capacitor.

7. A positive electrode, characterized in that, The positive electrode includes a high-capacity high-entropy fluorine oxide compound material according to claim 4.

8. The preparation method of a positive electrode according to claim 7, wherein It includes the following steps: Add an active material, a binder, and a conductive agent to a solvent to obtain an electrode slurry, and the active material is a high-capacity high-entropy fluorine oxide compound material according to claim 4; coat the electrode slurry on carbon fiber, and after drying, obtain a positive electrode.

9. The method for preparing a positive electrode according to claim 8, wherein The mass ratio of the active material, the binder, and the conductive agent is 6-8:1-2:1-2; the total mass of the active material, the binder, and the conductive agent and the mass ratio of the solvent are 2-3:1; The thickness of the electrode slurry coated on the carbon fiber is 40-60 μm.

10. A structural lithium-ion battery, characterized in that, The structural lithium-ion battery includes a positive electrode according to claim 7.

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