CN113104899B - Application of K2Fe2(MoO4)3 in Lithium Ion Battery Anode - Google Patents

Abstract

The invention relates to the application of K ₂ Fe ₂ (MoO ₄ ) ₃ in the negative electrode of lithium ion battery. The K ₂ Fe ₂ (MoO ₄ ) ₃ compound is used as an active material in a negative electrode of a lithium ion battery, has good charge-discharge performance of a lithium ion battery, good cycle stability, and a suitable working voltage, and can be used as a negative electrode of a lithium ion battery Material.

Description

Application of K2Fe2(MoO4)3 in Lithium Ion Battery Anode

technical field

The invention relates to a lithium ion battery negative electrode material with a chemical formula of K ₂ Fe ₂ (MoO ₄ ) ₃ , a preparation method and a lithium ion battery made by using the material.

Background technique

With the increasingly severe energy problem, the increasing scarcity of non-renewable resources, and the increasing awareness of the importance of environmental protection, the society's demand for new energy is increasing, and energy storage is playing an increasingly important role in the energy system. Previously, lithium-ion batteries, as important energy storage devices in new energy sources, attracted numerous research resources.

At present, the anode materials used in lithium-ion batteries mainly include graphite, carbon and lithium titanate. However, these materials still have many problems: poor specific capacity, poor cycling stability, and difficult preparation, which severely limit the practical application of these materials. Therefore, exploring new anode materials for lithium-ion batteries is still a hot and difficult point in lithium-ion battery research. Among polyanion-based anode materials, molybdate has attracted more and more attention due to its high specific capacity.

SUMMARY OF THE INVENTION

In view of the technical problem proposed above, the present invention aims to provide a kind of K ₂ Fe ₂ (MoO ₄ ) ₃ as a negative electrode material for use in a lithium ion battery;

The specific technical solutions are as follows:

An application of K ₂ Fe ₂ (MoO ₄ ) ₃ in a lithium ion battery negative electrode, the K ₂ Fe ₂ (MoO ₄ ) ₃ compound is used as an active material in a lithium ion battery negative electrode.

The negative electrode active material of the lithium ion battery is K ₂ Fe ₂ (MoO ₄ ) ₃ material.

The K ₂ Fe ₂ (MoO ₄ ) ₃ lithium ion battery negative electrode material provided by the invention.

K ₂ Fe ₂ (MoO ₄ ) ₃ is prepared by solid-phase reaction method, and the steps are as follows:

1) Batching: Mix the K-containing compound, Fe-containing compound and Mo-containing compound according to the molar ratio of K:Fe:Mo (2-2.1):2:3, and carry out pretreatment;

The pretreatment is to mix the prepared raw materials evenly, pour them into a crucible, heat them in a muffle furnace from room temperature to 200-500° C. for 2-10 hours, and then cool them to room temperature;

2) Control various parameters for material synthesis: place the crucible containing the above ingredients in a muffle furnace; raise the temperature from room temperature to 600-1000°C at a rate of 1-10°C; keep the temperature for 10-40 hours; , at a rate of 1-50°C/h to room temperature to obtain K ₂ Fe ₂ (MoO ₄ ) ₃ material;

The K-containing compound is one or more of K oxide, K carbonate, K borate, K nitrate or K oxalate;

The Fe-containing compound is one or more of Fe oxide and Fe oxalate;

The Mo-containing compound is one or both of MoO ₂ or MoO ₃ .

A K ₂ Fe ₂ (MoO ₄ ) ₃ lithium ion battery anode material was prepared by a sol-gel method, and the steps were as follows:

1) Ingredients: add K-containing compound, divalent Fe-containing compound and Mo-containing compound into deionized water at 50-100°C in a molar ratio of K:Fe:Mo:oxalic acid (2-2.1):2:3:3 Stir until a uniform light green solution is formed, and continue stirring until a sol is formed; the molar concentration of the K-containing compound in deionized water is 0.1-0.5 mol/L.

2) Transfer the sol to an oven at 100-150°C, dry it to a gel, grind the gel into powder and transfer it to a porcelain boat for pretreatment;

The pretreatment is to heat the raw materials in the porcelain boat from room temperature to 200-500 DEG C for more than 2-10 hours in a muffle furnace, and then cool to room temperature;

3) Control various parameters for material synthesis: place the porcelain boat containing the above ingredients in a muffle furnace; raise the temperature to 600-1000°C at a rate of 1-10°C; keep the temperature for 10-40 hours; The rate of 1-50℃/h is lowered to room temperature to obtain K ₂ Fe ₂ (MoO ₄ ) ₃ material;

The K-containing compound is one or more of K oxide, K carbonate, K borate, K nitrate or K oxalate;

The Fe-containing compound is one or more of Fe oxide and Fe oxalate;

The Mo-containing compound is one or both of MoO ₂ or MoO ₃ .

Several typical chemical reaction formulas for obtaining K ₂ Fe ₂ (MoO ₄ ) ₃ compounds are listed below:

(1) K ₂ CO ₃ +2FeO+3MoO ₃ =K ₂ Fe ₂ (MoO ₄ ) ₃ +CO ₂

(2) 4KNO ₃ +4FeO+6MoO ₃ =2K ₂ Fe ₂ (MoO ₄ ) ₃ +4NO ₂ +O ₂

(3) K ₂ CO ₃ +2FeC ₂ O ₄ +3MoO ₃ =2K ₂ Fe ₂ (MoO ₄ ) ₃ +3CO ₂ +2CO

The advantages of the present invention lie in that the obtained K ₂ Fe ₂ (MoO ₄ ) ₃ negative electrode material has higher specific capacity, rate capability and cycle stability. K ₂ Fe ₂ (MoO ₄ ) ₃ lithium ion battery anode material has a high specific capacity of 800mAh/g; its operating voltage is between 0.05-3.0V, and the specific capacity can still maintain more than 90% after 100 cycles.

Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the description, claims and drawings.

Description of drawings

The accompanying drawings are used to provide a further understanding of the technical solutions of the present invention, and constitute a part of the specification. They are used to explain the technical solutions of the present invention together with the specific embodiments of the present application, and do not limit the technical solutions of the present invention.

FIG. 1 is a SEM picture of the negative electrode material of the K ₂ Fe ₂ (MoO ₄ ) ₃ lithium ion battery of the present invention.

FIG. 2 is a polycrystalline powder X-ray diffraction pattern of K ₂ Fe ₂ (MoO ₄ ) ₃ of the present invention.

FIG. 3 is a crystal structure diagram of K ₂ Fe ₂ (MoO ₄ ) ₃ lithium in the present invention.

FIG. 4 is a charge-discharge curve of the K ₂ Fe ₂ (MoO ₄ ) ₃ lithium negative electrode material of the present invention at a rate of 0.1C and 0.05-3.0V.

FIG. 5 is a rate performance curve of the K ₂ Fe ₂ (MoO ₄ ) ₃ lithium negative electrode material of the present invention.

Detailed ways

The present invention will be described in more detail below with reference to the accompanying drawings, in which preferred embodiments of the invention are shown, it should be understood that those skilled in the art can modify the invention described herein and still achieve the beneficial effects of the invention. Therefore, the following description should be construed as widely known to those skilled in the art and not as a limitation of the present invention.

Example 1 High-temperature solid-phase preparation of K ₂ Fe ₂ (MoO ₄ ) ₃ negative electrode material

Put 0.01 mol of K ₂ CO ₃ , 0.02 mol of FeO and 0.03 mol of MoO ₃ into an agate mortar and grind for half an hour. Transfer to the crucible and place the crucible into the muffle furnace. The furnace was raised to 300°C at a heating rate of 5°C/min, held for 5 hours, and finally lowered to room temperature at a rate of 20°C/min. The synthesized material was taken out, ground into powder, and then transferred to the crucible again and put into the muffle furnace. The furnace was raised to 800°C at a heating rate of 5°C/min, held for 20 hours, and finally lowered to room temperature at a rate of 20°C/min. The obtained product is taken out of the grinding components to obtain the K ₂ Fe ₂ (MoO ₄ ) ₃ compound.

As shown in Fig. 1, it is a gray-green powder with a tap density of 2.0 g/cm ³ and a melting point of 840°C. Its X-ray diffraction pattern is shown in Figure 2, and its crystal structure is shown in Figure 3. It can be seen from Fig. 3 that the basic structural units are CrO ₆ and MoO ₄ polyhedrons, and the MoO ₄ polyhedrons are connected to each other to form a three-dimensional network structure.

Example 2 Sol-gel preparation of K ₂ Fe ₂ (MoO ₄ ) ₃ negative electrode material

Dissolve 0.03 mol of oxalic acid in a beaker filled with 100 ml of deionized water, then add 0.02 mol of Fe(NO ₃ ) ₂ , stir in a constant temperature water bath at 70-80 °C until it becomes a light green solution, and then add 0.03 mol of Fe(NO 3 ) 2 . MoO ₃ , 0.01 mol of K ₂ CO ₃ , and continued stirring to form a green sol. The sol was dried in an oven at 80° C. for about 10 hours to obtain a green fluffy precursor. The precursor was ground into powder and placed in a crucible, and the crucible was placed in a muffle furnace. The furnace was raised to 300°C at a heating rate of 5°C/min, held for 5 hours, and finally lowered to room temperature at a rate of 20°C/min. The synthesized material was taken out, ground into powder, and then transferred to the crucible again and put into the muffle furnace. The furnace was raised to 800°C at a heating rate of 5°C/min, held for 20 hours, and finally lowered to room temperature at a rate of 20°C/min. The obtained product is taken out of the grinding components to obtain the K ₂ Fe ₂ (MoO ₄ ) ₃ compound.

The materials obtained in Examples 1 and 2 are dissolved in an appropriate amount of N-methylpyrrolidone according to the mass ratio of the active material, conductive carbon black and binder as 8:1:1, and mixed evenly, and coated with a wet film preparer. An electrode film with a thickness of 0.15 mm was formed, and after being vacuum-dried, it was cut into electrode sheets with a diameter of 12 mm with a microtome, weighed and the mass of the active material was calculated. At the same time, the lithium sheet was used as the negative electrode, Celgard 2500 was used as the separator, and 1 mol/L LiPF ₆ EC+DMC (volume ratio of 1:1) solution was used as the electrolyte, and a button battery was installed in an argon-filled glove box. The assembled cells were then electrochemically tested under constant current conditions of 0.05-3V, respectively. The test results are shown in Figures 4 and 5, it can be seen that K ₂ Fe ₂ (MoO ₄ ) ₃ has a high discharge specific capacity, reaching 800mAhg ^-1 , and has a good cycle rate performance, still 450mAhg ^{- 1} specific capacity.

The K ₂ Fe ₂ (MoO ₄ ) ₃ compound is used as an active material in a negative electrode of a lithium ion battery, has good charge-discharge performance of the lithium ion battery, good cycle stability and suitable working voltage, and can be used as a negative electrode of a lithium ion battery Material.

The above are only preferred embodiments of the present invention and do not limit the present invention. Any simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical essence of the present invention still belong to the technology of the present invention. within the scope of the program.

Claims (2)

1. the application of K ₂ Fe ₂ (MoO ₄ ) ₃ in the negative electrode of lithium ion battery, it is characterized in that: described K ₂ Fe ₂ (MoO ₄ ) ₃ compound is applied in the negative electrode of lithium ion battery as active material; And, the preparation method of the K ₂ Fe ₂ (MoO ₄ ) ₃ compound is as follows: The K ₂ Fe ₂ (MoO ₄ ) ₃ compound is prepared by the solid-phase reaction method, and the steps are as follows: 1) Batching: Mix the K-containing compound, Fe-containing compound and Mo-containing compound according to the molar ratio of K:Fe:Mo of 2-2.1:2:3 and carry out pretreatment; The pretreatment is to mix the prepared raw materials evenly, and then heat up from room temperature to 200-500° C. for 2-10 hours, and then cool to room temperature; 2) Control various parameters for material synthesis: the pretreated ingredients are raised from room temperature to 600-1000°C at a rate of 1-10°C/min; kept for 10-40 hours; The rate of /h is reduced to room temperature to obtain K ₂ Fe ₂ (MoO ₄ ) ₃ material; The K-containing compound is one or more of K oxide, K carbonate, K borate, K nitrate or K oxalate; The Fe-containing compound is one or more of Fe oxide and Fe oxalate; The Mo-containing compound is one or both of MoO ₂ or MoO ₃ ; Alternatively, the K ₂ Fe ₂ (MoO ₄ ) ₃ compound is prepared by a sol-gel method, and the steps are as follows: 1) Ingredients: Add K-containing compound, divalent Fe-containing compound, Mo-containing compound and oxalic acid into deionized water at 50-100 °C in a molar ratio of K:Fe:Mo:oxalic acid of 2-2.1:2:3:3 Stir until a uniform light green solution is formed, and continue stirring until a sol is formed; 2) Dry the sol at 100-200°C until it becomes a gel, and grind the gel into powder for pretreatment; The pretreatment is to heat up from room temperature to 200-500 DEG C for more than 2-10 hours, and then cool to room temperature; 3) Control various parameters for material synthesis: the pretreated material in step 2); rise to 600-1000°C at a rate of 1-10°C/min; keep the temperature for 10-40 hours; The rate of ℃/h is reduced to room temperature to obtain K ₂ Fe ₂ (MoO ₄ ) ₃ material; The K-containing compound is one or more of K oxide, K carbonate, K borate, K nitrate or K oxalate; The divalent Fe-containing compound is one or more of Fe oxide and Fe oxalate; The Mo-containing compound is one or both of MoO ₂ or MoO ₃ . 2. according to the described application of claim 1, it is characterized in that: The molar concentration of K-containing compound in deionized water in step 1) of preparing K ₂ Fe ₂ (MoO ₄ ) ₃ compound by sol-gel method is 0.1-0.5 mol/L.

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