WO2021031218A1

WO2021031218A1 - Sodium dimolybdate and electrode material based on sodium dimolybdate, preparation method and application thereof

Info

Publication number: WO2021031218A1
Application number: PCT/CN2019/102119
Authority: WO
Inventors: 卡马里阿里-雷扎; 朱文辉
Original assignee: 东北大学
Priority date: 2019-08-20
Filing date: 2019-08-23
Publication date: 2021-02-25
Also published as: CN110498446A; CN110498446B

Abstract

Disclosed are sodium dimolybdate and an electrode material based on sodium dimolybdate, a preparation method, and an application thereof, belonging to the field of preparation and application of electrode materials for lithium-ion batteries. The sodium dimolybdate has a chemical formula represented by Na ₂Mo ₂O ₇, a microscopic morphology of rod-shaped and sheet-shaped structures, an average length of 10-20 μm, and an average diameter of 4-10 μm. The sodium dimolybdate is prepared by the molten salt method using sodium salt and molybdenum disulfide as raw materials. Based on the sodium dimolybdate material, after being compounded with conductive carbon and a binder, an electrode sheet is prepared and applied to negative electrode material of a lithium-ion battery.

Description

Sodium dimolybdate and electrode material based on sodium dimolybdate and preparation method and application thereof

Technical field

The invention belongs to the field of preparation and application of lithium ion battery electrode materials, and particularly relates to a sodium dimolybdate and an electrode material based on sodium dimolybdate, and a preparation method and application thereof.

Background technique

Secondary lithium-ion batteries are very important for the development of secondary batteries. A large part of the research on lithium-ion batteries comes from the research of battery electrodes. With the increasing rise of smart phones, computers, electric vehicles, etc., as well as power tools and other energy storage The gradual expansion of the new energy market has expanded the demand for lithium secondary batteries. At the same time, the research on lithium secondary batteries by top scientific researchers in various countries has also achieved great success. Lithium-ion secondary batteries, as an important energy storage system, are more expected to make major breakthroughs in this technology.

In order to apply lithium-ion batteries (LIBs) in the next generation of new energy electric vehicles to achieve higher energy density, power density and longer cycle life, a large number of research and production are mainly focused on exploring new electrode materials such as metal oxides . Among them, _{Mo-based materials including MoO 3} and metal molybdates have aroused great research interest. Since the valence state of molybdenum can be changed between +6 and 0, multiple electron transfer can be realized in the redox process. Therefore, a higher specific capacity can be obtained in the initial cycle. In recent years, alkali metal molybdates have been used as anode materials for LIBs.

Molybdenum disulfide is the main component of molybdenite. Its chemical formula is MoS ₂ , which is insoluble in water and has a melting point of 1185°C. The synthetic molybdenum disulfide is a black solid powder. It is diamagnetic and can be used as a semiconductor wire showing N-type and P-type conductivity. At the same time, it can also be used as a catalyst for the dehydrogenation of complex hydrocarbons. Its two-dimensional layered nanomaterial with a graphite-like structure is a very important solid lubricant and is called "the king of advanced solid lubricants."

Sodium dimolybdate (Na ₂ Mo ₂ O ₇ ) belongs to the class of molybdates, and its general composition is Na ₂ Mo _n O _3n+1 . Na ₂ Mo ₂ O ₇ has an orthorhombic structure at room temperature, which belongs to the center-based orthorhombic structure and is the space group Cmca(64). Currently, molybdate compounds have been extensively studied for solid-state lighting with light-emitting diodes. Sodium molybdate (Na ₂ Mo ₂ O ₇ ), as a semiconductor material with excellent performance, can be used as an anode material for lithium ion batteries. The conventional methods for preparing Na ₂ Mo ₂ O ₇ include: sol-gel method, chemical precipitation method, ultrasonic spray pyrolysis method, pulling synthesis method, solid state reaction method, etc. _{The Na 2} Mo ₂ O ₇ synthesized by these conventional methods are respectively 10μm±1μm polycrystalline powder (solid state reaction method), needle-like nanoparticles with needle length of 10μm (ultrasonic spray pyrolysis method), 38nm±2nm spherical particles (Sol-gel method), 100(D)×45(L)mm ³ crystals (crysynthesis method), but these methods have problems such as long preparation cycle and complicated reaction, which have caused extensive research.

Summary of the invention

technical problem

The solution to the problem

Technical solutions

In view of the problems in the prior art, the present invention provides sodium dimolybdate and an electrode material based on sodium dimolybdate as well as a preparation method and application thereof. The sodium dimolybdate electrode material is a rod-shaped and long-sheet-like structure of dimolybdenum Based on sodium salt material, after compounding with conductive carbon and binder, it is applied to the anode material of lithium ion battery. This method is a lithium ion negative electrode material prepared on the basis of sodium dimolybdate material with a rod-like or long-sheet structure. During the charge and discharge process, since the valence state of the molybdenum element can change between +6 and 0, it can be Many electrons can be transferred during the process, so high specific capacity can be obtained in the initial cycle. Because Mo ^{6+ is} reduced to Mo ⁰ (6 electron changes; 6Li/Mo), high capacity can be achieved. Compared with Li ⁺ /Li, ^{the easy reduction of Mo 6+} allows the conversion reaction to occur at a lower voltage, which makes Mo ⁶⁺ -containing oxides a potentially suitable negative electrode material for LIBs. It can greatly improve the lower theoretical specific capacity of graphite as the negative electrode material of traditional lithium-ion batteries, and solve the development obstacle of lower specific capacity of lithium-ion batteries. It is expected to provide technical support for the commercial application of anode materials for lithium-ion batteries with high specific capacity in the future.

The sodium dimolybdate of the present invention has a chemical formula of Na ₂ Mo ₂ O ₇ , and its macroscopic appearance is a rod-like and long sheet-like structure, with an average length of 10-20 μm and an average diameter of 4-10 μm.

The preparation method of sodium dimolybdate according to the present invention adopts the molten salt method and includes the following steps:

(1) Mix the sodium salt and molybdenum disulfide (MoS ₂ ) thoroughly to obtain a uniform mixture A; wherein, according to the mass ratio, sodium salt: molybdenum disulfide = (6-20):1;

(2) The mixture A is heated from room temperature to reaction temperature at a heating rate of (1-100)°C/min under air or oxygen atmosphere, and kept for 1min～2h, preferably 20min, and then cooled to room temperature with the furnace, and washed After drying, the white powder obtained is Na ₂ Mo ₂ O ₇ ; wherein, the reaction temperature T is: the melting point of the sodium salt used<T<the boiling point of the sodium salt used.

In the step (1), the sodium salt is _{one or more of sodium chloride (NaCl), sodium nitrate (NaNO 3} ), and sodium fluoride (NaF).

In the step (1), the molybdenum disulfide is commercial molybdenum disulfide or molybdenite, and its purity is ≥90wt.%.

The sodium dimolybdate of the present invention is prepared by the above preparation method.

An electrode material based on sodium dimolybdate of the present invention includes the above sodium dimolybdate.

The said electrode material based on sodium dimolybdate also includes conductive carbon, a binder and a solvent, wherein, according to the mass ratio, sodium dimolybdate: conductive carbon: binder = (5-9): (0.5-3 ): (0.5～1.5).

The conductive carbon is one or more of acetylene black, conductive graphite, nano graphite, furnace black, Ketjen carbon black, carbon nanotube, and graphene, preferably graphene.

The binder is one or more of polyvinylidene fluoride, butyl rubber, sodium carboxymethyl cellulose, polyacrylic acid, polyimide, and polytetrafluoroethylene.

The solvent is one or more of N-methylpyrrolidone, dimethylformamide, tetrahydrofuran, carbon tetrachloride, water and ethanol. Wherein, according to the mass ratio, solvent: solid matter=(4-12):1; the solid matter is sodium dimolybdate and conductive carbon.

A preparation method based on sodium dimolybdate electrode material of the present invention includes the following steps:

Step I:

According to the proportion, weigh the sodium dimolybdate and conductive carbon, mix and grind uniformly to obtain a mixture.

Step II:

According to the ratio, the binder is weighed, and the solvent is added. After stirring for 15 min to 1 h, it is put into the mixture obtained in step I and stirred for 8 to 20 h to form a uniform paste to obtain an electrode material based on sodium dimolybdate.

In the step II, the stirring is uniform, and the stirring time is preferably 10 hours.

The application of the electrode material based on sodium dimolybdate of the present invention is used as a battery negative electrode material.

An electrode pole piece prepared by using the above-mentioned electrode material based on sodium dimolybdate.

The preparation method of the electrode pole piece of the present invention includes the following steps:

Step 1: Coating the current collector

Coating the above-mentioned electrode material based on sodium dimolybdate uniformly on the current collector, drying at 50-80°C for 4 hours, and then vacuum drying for 12-20 hours to obtain a dried current collector coated with electrode material;

Step 2: Rolling treatment

The dried current collector coated with electrode material is rolled and cut to obtain electrode pole pieces.

In the step 1, the current collector is copper foil or aluminum foil.

In the step 1, the drying temperature of vacuum drying is 50-80°C.

In the step 1, wherein, on the current collector, the load per unit area of the active material is 0.8-5 mg/cm ² , and the active material is sodium dimolybdate and conductive carbon;

The electrode pole piece is prepared by the method for preparing the electrode pole piece.

A battery of the present invention uses the above-mentioned electrode pole piece as a working electrode.

The battery is one of lithium ion batteries, sodium ion batteries, and potassium ion batteries.

The method for preparing a lithium ion battery of the present invention includes the following steps:

In an argon atmosphere, the electrode pole piece is used as the negative electrode, the lithium piece is used as the positive electrode, and the electrode pole piece, lithium piece, separator, and electrolyte are assembled to form a lithium ion battery.

The lithium ion battery of the present invention has a first discharge capacity of 900 to 1400 mAhg ^-1 and a first reversible charge capacity of 700 to ^{900 mAhg -1} ^{at a current density of 100 mAg -1} , so the first coulombic efficiency reaches 40 to 80% ; Under ^{the current density of 500mAg -1} , the reversible discharge specific capacity after 500 cycles is 100-300mAhg ^-1 , and the coulombic efficiency is 95-100%.

The beneficial effects of the invention

Beneficial effect

Compared with the existing molybdenum disulfide-based lithium ion battery negative electrode materials, the sodium dimolybdate and the electrode material based on sodium dimolybdate and the preparation method and application thereof of the present invention have the following advantages and beneficial effects:

1. The present invention makes full use of the simple process of molten salt method, high efficiency and high yield. The rapid molten salt method successfully prepares Na ₂ Mo ₂ O ₇ with rod-like and long sheet-like structures, and the raw materials added in the molten salt method Sodium salt is the reactant and provides the reaction atmosphere, which not only provides the reaction material for this reaction, but also provides the reaction system for this reaction; the Na ₂ Mo ₂ O ₇ obtained by the molten salt method is used to prepare lithium ion batteries Later, in the lithium ion battery, during the charge and discharge process, lithium contains a quaternary oxide and a polyanion network phase capable of Li intercalation, wherein the intercalation reaction occurs before the conversion reaction. In addition, in Na ₂ Mo ₂ O ₇ , the presence of sodium in the main body not only leads to low irreversible capacity loss (ICL), but also produces better electrochemical performance in terms of capacity and cycle behavior. This lays the foundation for the preparation of high specific capacity anode materials.

2. The electrode material based on sodium dimolybdate of the present invention has a special morphology and composition. The preparation method of sodium dimolybdate is based on the heating rate of (1-100) ℃/min, heating from room temperature to (the sodium salt used) The melting point ~ the boiling point of the sodium salt used), and the holding time is 1 min to 2 h, preferably 20 min, which has lower energy consumption and shorter reaction time, and significantly improves production efficiency. In addition, the sodium dimolybdate of the present invention is homogeneous in phase, and its preparation method does not generate other by-products, and truly realizes the short-flow new process route of directly preparing the precursor of the negative electrode material of the lithium ion battery.

3. The rod-like or sheet-like structure Na ₂ Mo ₂ O ₇ prepared by the present invention is applied to the negative electrode material of lithium ion battery, and the lithium ion battery exhibits excellent long-cycle stability and rate performance.

Brief description of the drawings

Description of the drawings

Figure 1 is an XRD pattern, where (a) is the XRD pattern of the raw material commercial molybdenum disulfide (MoS ₂ ); (b) is the XRD pattern of the rod-shaped product sodium dimolybdate.

Figure 2 is an SEM image of sodium dimolybdate prepared by the present invention.

Fig. 3 is a charge and discharge curve diagram of a lithium ion battery prepared based on sodium dimolybdate-based lithium ion battery anode material in Example 1 of the present invention.

4 is a diagram of the cycle performance of a lithium ion battery prepared based on sodium dimolybdate-based lithium ion battery anode material in Example 1 of the present invention.

FIG. 5 is a diagram of the cycle performance of a lithium ion battery prepared based on sodium dimolybdate-based lithium ion battery anode material in Example 2 of the present invention.

Invention embodiment

Embodiments of the invention

The present invention will be further described in detail below in conjunction with the embodiments.

In the following examples, unless otherwise specified, the raw materials and equipment used are all commercially available, and the purity of the raw materials is analytically pure.

Example 1

A preparation method of sodium dimolybdate is:

Thoroughly mix sodium chloride (NaCl) with a mass ratio of 10:1 and commercial molybdenum disulfide (MoS ₂ 99.5%) to obtain a homogeneous mixture A. Place the mixture A in a 50 mL corundum crucible and place it in a muffle furnace. Heating, heating from room temperature to 1300℃ at a rate of 5℃·min ^-1 . The holding time at 1300°C is 20 min. After the heating process is completed, the muffle furnace is cooled to room temperature, and the product is directly collected from the corundum crucible and washed without further treatment. After drying, Na ₂ Mo ₂ O ₇ is obtained as a white powder. The conversion rate is 10-30%.

The prepared sodium dimolybdate was tested and analyzed by XRD and SEM. The XRD pattern is shown in Figure 1(b). The sodium dimolybdate is used as the precursor of the negative electrode material for lithium ion batteries. The XRD pattern in Figure 1 is analyzed. The chemical formula of sodium dimolybdate prepared in this embodiment is Na ₂ Mo ₂ O ₇ . It is an orthorhombic crystal system Na ₂ Mo ₂ O ₇ (JCPDS#01-073-1797; space group: Cmca), and XRD indicates that a single phase is formed. The calculated lattice parameter value is

Except for the above-mentioned _{characteristic peaks of the Na 2} Mo ₂ O ₇ sample, no other characteristic peaks are observed, indicating that only the sample Na ₂ Mo ₂ O ₇ exists under this reaction condition.

The SEM image of the sodium dimolybdate prepared in this example is shown in Fig. 2. From Fig. 2, it can be seen that the morphology of the sodium dimolybdate is a rod-like structure particle with an average length of 10-20 μm.

An electrode material based on sodium dimolybdate, including the sodium dimolybdate prepared above, as well as conductive carbon, a binder and a solvent; wherein, according to the mass ratio, sodium dimolybdate: conductive carbon: binder = 7: 2:1.

The conductive carbon is graphene, the binder is polytetrafluoroethylene, and the solvent is N-methylpyrrolidone.

A preparation method based on sodium dimolybdate electrode material includes the following steps:

Weigh 70 mg of sodium dimolybdate, 20 mg of graphene and 10 mg of polytetrafluoroethylene, mix and grind the sodium dimolybdate and conductive carbon to obtain a mixture;

Add 10 mg of polytetrafluoroethylene to 400 μL of N-methylpyrrolidone, stir for 30 minutes, put it into the mixture, and perform magnetic stirring for 10 hours to form a paste to obtain an electrode material based on sodium dimolybdate.

The electrode material based on sodium dimolybdate is used as a negative electrode material for lithium ion batteries.

The process of assembling the negative electrode material of lithium ion battery based on sodium dimolybdate electrode material into a button half-cell is:

Coat the adjusted electrode material based on sodium dimolybdate on copper foil, and dry it at 60℃ for 4h, and then vacuum dry it at 60℃ for 18h to make electrode pole piece;

After the electrode pole piece is sliced and pressed, and the lithium piece is used as a counter electrode, the button half-cell is assembled in a glove box. Among them, in the button half-cell, the separator is a Celgard 2400 polypropylene membrane, and the electrolyte is 1.0M LiPF ₆ (EC:DMC:EMC=1:1:1).

Conduct constant current charge and discharge tests on the assembled button-type half-cell to investigate its cycle stability and rate performance. The charge-discharge curve is shown in Figure 3. As can be seen from Figure 3, the specific capacity of a rod in Figure 1362.7mAhg ^-1 Na _₂ Mo ₂ O _7, in 100mAg ^-1, the initial discharge, the charge capacity was 857.2mAhg ^-1. The first Coulomb efficiency was 63%. The main reason for this phenomenon was the formation of a solid electrolyte intermediate phase (SEI film) on the electrode surface, which consumed a large amount of Li ⁺¹ .

In this example, a lithium ion battery prepared based on sodium dimolybdate as a lithium battery negative electrode material was measured at room temperature for the first discharge capacity, first coulomb efficiency, and reversible charge capacity of the coin-type half-cell produced. The cycle performance diagram is shown in Figure 4 , And the results are as follows:

At a current density of 500mAg ^-1, the ratio of capacity after 500 cycles was 200mAhg ^-1, and the battery cycle stability.

Example 2

In an electrode material based on sodium dimolybdate, the preparation method of the sodium dimolybdate is the same as in Example 1, except that the raw material of molybdenite used is molybdenite. The molybdenite contains disulfide The mass percentage of molybdenum is 96.3wt.%;

The conductive carbon is conductive graphite, the binder is sodium carboxymethyl cellulose, the solvent is a mixture of water and ethanol, the volume percentage of ethanol is 95%, and the balance is water.

Weigh 70 mg of sodium dimolybdate, 20 mg of conductive graphite and 10 mg of sodium carboxymethyl cellulose prepared in this embodiment, and mix and grind sodium dimolybdate and conductive graphite to obtain a mixture;

Add 10 mg of sodium carboxymethyl cellulose to 400 μL of solvent and stir for 1 h. After adding to the mixture, magnetically stir for 10 h and form a paste to obtain an electrode material based on sodium dimolybdate.

The process of assembling a button-type half-cell based on sodium dimolybdate electrode material is: coating the adjusted sodium dimolybdate electrode material on copper foil, and dry it at 60℃, and then dry it in vacuum at 60℃ for 20h, Make electrode pole piece;

After the electrode pole piece is sliced and pressed, it is used as the negative electrode material, and the lithium piece is used as the counter electrode, and the button half-cell is assembled in the glove box. The ^{electrochemical performance test was carried out on a constant current charging and discharging system with a current density of 100mAg -1} , and the first discharge capacity, first coulomb efficiency and reversible charging capacity of the coin-type half-cells were measured at room temperature. The cycle performance chart is shown in Figure 5, the results are as follows:

At a current density of 100mAg ^-1, the ratio of capacity after 100 cycles was 500mAhg ^-1, and the battery cycle stability.

Example 3

A preparation method of sodium dimolybdate is:

_{Mix sodium nitrate (NaNO 3} ) with a mass ratio of 15:1 and commercial molybdenum disulfide (MoS ₂ 99.5%) thoroughly to obtain a homogeneous mixture A. Place the mixture A in a 50 mL corundum crucible and place it in a muffle furnace. Heating, heating from room temperature to 340℃ at a rate of 8℃·min ^-1 . The retention time is 1h at 340°C. After the heating process is completed, the muffle furnace is cooled to room temperature, and the product is directly collected from the corundum crucible and washed without further treatment. After drying, Na ₂ Mo ₂ O ₇ is obtained as a white powder.

An electrode material based on sodium dimolybdate, comprising the sodium dimolybdate prepared above, as well as conductive carbon, a binder and a solvent; wherein, according to the mass ratio, sodium dimolybdate: conductive carbon: binder = 8: 1:1.

The conductive carbon is carbon nanotubes, the binder is butyl rubber, and the solvent is tetrahydrofuran.

Weigh 80 mg of sodium dimolybdate, 10 mg of carbon nanotubes and 10 mg of butyl rubber, and mix and grind the sodium dimolybdate and carbon nanotubes to obtain a mixture;

Add 10 mg of butyl rubber to 600 μL of tetrahydrofuran, stir for 15 minutes, put it into the mixture, and perform magnetic stirring for 10 hours to form a paste to obtain an electrode material based on sodium dimolybdate.

The electrode material based on sodium dimolybdate is used as a negative electrode material for sodium ion batteries.

The process of assembling the anode material of the sodium ion battery based on the sodium dimolybdate electrode material into a sodium ion battery is:

After the electrode pole piece is sliced and pressed, it is used as a negative electrode material to assemble a sodium ion battery.

Example 4

A preparation method of sodium dimolybdate is:

Mix sodium chloride (NaCl), sodium fluoride (NaF) and molybdenite (MoS ₂ 97%) with a mass ratio of 10:10:1 to obtain a homogeneous mixture A, which is placed in 50 mL of corundum The crucible is heated in a muffle furnace from room temperature to 1400°C at a rate of 100°C·min ^-1 . The holding time at 1400°C is 5 min. After the heating process is completed, the muffle furnace is cooled to room temperature, and the product is directly collected from the corundum crucible and washed without further treatment. After drying, Na ₂ Mo ₂ O ₇ is obtained as a white powder.

An electrode material based on sodium dimolybdate, including the sodium dimolybdate prepared above, as well as conductive carbon, a binder and a solvent; wherein, according to the mass ratio, sodium dimolybdate: conductive carbon: binder = 5: 3:2.

The conductive carbon is Ketjen carbon black, the binder is polyacrylic acid, and the solvent is dimethylformamide.

Weigh 50mg sodium dimolybdate, 30mg Ketjen carbon black and 20mg polyacrylic acid, mix and grind the sodium dimolybdate and Ketjen carbon black to obtain a mixture;

20 mg of polyacrylic acid was added to 600 μL of dimethylformamide, stirred for 15 minutes, put into the mixture, and magnetically stirred for 20 hours to form a paste to obtain an electrode material based on sodium dimolybdate.

This is based on sodium dimolybdate electrode material for potassium ion battery anode material.

The process of assembling the anode material of the potassium ion battery based on the sodium dimolybdate electrode material into a potassium ion battery is:

Coat the adjusted electrode material based on sodium dimolybdate on copper foil, and dry it at 80℃ for 4h, then vacuum dry at 80℃ for 12h to make electrode pole piece;

After the electrode pole piece is sliced and pressed, it is used as the negative electrode material to assemble the potassium ion battery.

Comparative example 1

Same as Example 1, the difference is: sodium chloride is 50g, molybdenite is 10g, XRD analysis is performed on the obtained product, and the spectrum is at 2θ=14.5°, 26.8°, 29.2°, 39.7°, 44.3°, Diffraction peaks are detected at 49.9°, 60.3°, 70.3° and 77.7°, which are _{characteristic peaks of MoS 2} , and their XRD patterns are not much different from those of molybdenite (Figure 1(a)), indicating that the product is MoS ₂ .

Comparative example 2

Same as Example 1, the difference lies in:

In the step (2), the reaction is carried out in a tube furnace without contact with air. The obtained product is subjected to XRD analysis. The spectrum is at 2θ=14.5°, 26.8°, 29.2°, 39.7°, 44.3°, 49.9 Diffraction peaks are detected at °, 60.3°, 70.3° and 77.7°, which are _{characteristic peaks of MoS 2} , and their XRD patterns are not much different from those of molybdenite (Figure 1(a)), indicating that the product is MoS ₂ .

Claims

A sodium dimolybdate, characterized in that the chemical formula of the sodium dimolybdate is Na 2 Mo 2 O 7 , and its macroscopic morphology is rod-like and long-sheet-like structure, with an average length of 10-20 μm and an average diameter of 4 10μm.
A method for preparing sodium dimolybdate, characterized in that a molten salt method is adopted, and includes the following steps:

(1) Mix the sodium salt and molybdenum disulfide thoroughly to obtain a uniform mixture A; wherein, according to the mass ratio, sodium salt: molybdenum disulfide = (6-20):1;

(2) The mixture A is heated from room temperature to reaction temperature at a heating rate of (1～100)℃/min under air or oxygen atmosphere, kept for 1min～2h, cooled to room temperature with the furnace, washed and dried , The white powder obtained is Na 2 Mo 2 O 7 ; wherein the reaction temperature T is: the melting point of the sodium salt used<T<the boiling point of the sodium salt used.
The method for preparing sodium dimolybdate according to claim 1, wherein in the step (1), the sodium salt is one or more of sodium chloride, sodium nitrate, and sodium fluoride.
The method for preparing sodium dimolybdate according to claim 1, wherein in the step (1), the molybdenum disulfide is commercial molybdenum disulfide or molybdenite, and its purity is ≥90wt.%.
A sodium dimolybdate characterized in that it is prepared by the preparation method described in claims 2-4.
An electrode material based on sodium dimolybdate, characterized in that it comprises the sodium dimolybdate according to claim 1 or 5.
The electrode material based on sodium dimolybdate according to claim 6, characterized in that the electrode material based on sodium dimolybdate further comprises conductive carbon, a binder and a solvent, wherein, according to the mass ratio, the dimolybdate Sodium: conductive carbon: binder = (5-9): (0.5-3): (0.5-1.5).
The electrode material based on sodium dimolybdate according to claim 7, wherein the conductive carbon is one of acetylene black, conductive graphite, nano graphite, furnace black, Ketjen carbon black, carbon nanotubes, and graphene. Kind or several.
The electrode material based on sodium dimolybdate according to claim 7, wherein the binder is polyvinylidene fluoride, butyl rubber, sodium carboxymethyl cellulose, polyacrylic acid, polyimide, One or more of polytetrafluoroethylene.
The electrode material based on sodium dimolybdate according to claim 7, wherein the solvent is one of N-methylpyrrolidone, dimethylformamide, tetrahydrofuran, carbon tetrachloride, water, and ethanol. One or more kinds; wherein, according to the mass ratio, solvent: solid matter=(4-12):1; the solid matter is sodium dimolybdate and conductive carbon.
The method for preparing an electrode material based on sodium dimolybdate according to any one of claims 6 to 10, characterized in that it comprises the following steps:

Step I:

According to the ratio, weigh the sodium dimolybdate and conductive carbon, mix and grind uniformly to obtain the mixture;

Step II:

According to the ratio, the binder is weighed, and the solvent is added. After stirring for 15 min to 1 h, it is put into the mixture obtained in step I and stirred for 8 to 20 h to form a uniform paste to obtain an electrode material based on sodium dimolybdate.
The application of an electrode material based on sodium dimolybdate according to any one of claims 6 to 10, characterized in that it is used as a battery negative electrode material.
An electrode pole piece, characterized in that it is prepared by using the sodium dimolybdate electrode material according to any one of claims 6-10.
The method for preparing an electrode pole piece according to claim 13, characterized in that it comprises the following steps:

Step 1: Coating the current collector

Coat the electrode material based on sodium dimolybdate uniformly on the current collector, dry it at 50-80°C for 4 hours, and then dry it in vacuum for 12-20 hours to obtain a dry current collector coated with electrode material;

Step 2: Rolling treatment

The dried current collector coated with electrode material is rolled and cut to obtain electrode pole pieces.
The method for preparing an electrode pole piece according to claim 14, characterized in that, in the step 1, the current collector is copper foil or aluminum foil.
The method for preparing an electrode pole piece according to claim 14, characterized in that, in the step 1, wherein, on the current collector, the loading amount of the active material per unit area is 0.8-5 mg/cm 2 , and the active material The substances are sodium dimolybdate and conductive carbon.
An electrode pole piece, characterized in that it is prepared by the method for preparing an electrode pole piece according to any one of claims 14-16.
A battery, characterized in that the electrode pole piece according to claim 13 or 17 is used as a working electrode.
The battery according to claim 18, wherein the battery is one of a lithium ion battery, a sodium ion battery, and a potassium ion battery.
The method for preparing a lithium ion battery according to claim 19, characterized by comprising the following steps:

In an argon atmosphere, the electrode pole piece is used as the negative electrode, the lithium piece is used as the positive electrode, and the electrode pole piece, lithium piece, separator, and electrolyte are assembled to form a lithium ion battery.
The battery according to claim 19, wherein the lithium ion battery has a first discharge capacity of 900-1400 mAhg -1 and a first reversible charge capacity of 700-900 mAhg -1 at a current density of 100 mAg -1 . Therefore, the first coulombic efficiency reaches 40-80%; at a current density of 500mAg-1 , after 500 cycles, the reversible discharge specific capacity is 100-300mAhg -1 , and the coulombic efficiency is 95-100%.