CN108217725A - A kind of hydrated basic pyrovanadic acid zinc（Zn3V2O7(OH)2·2H2O）The preparation method and application of material - Google Patents

Abstract

The invention relates to a preparation method and application of a hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material, which involves massaging vanadyl acetate VO(Ac) ₂ and zinc chloride The molar ratio is 1:1.5～1:4, dissolved in dimethylformamide solvent in turn, and after stirring evenly, a dark green solution is obtained, and then the obtained dark green solution is transferred to a stainless steel reaction kettle, and the reaction kettle is heated in an oven until After 120-180°C, constant temperature reaction for 3-36 hours, and finally cooling to room temperature, the obtained product was washed with distilled water and absolute ethanol respectively, centrifugally filtered, and vacuum-dried to obtain the product hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O). The hydrated basic zinc pyrovanadate prepared by the method of the invention has high reversible specific capacity and excellent electrochemical cycle performance, and good rate performance, and can be used as a novel negative electrode material in lithium ion battery systems.

Description

A kind of preparation method of hydrated basic zinc pyrovanadate (Zn3V2O7(OH)2·2H2O) material and applications

technical field

The invention belongs to the technical field of synthesis of micro-nano materials. More specifically, the invention relates to a preparation method and application of a hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material.

Background technique

Lithium Ion Battery (Lithium Ion Battery) is a secondary battery (rechargeable battery), which mainly relies on lithium ions to move between the positive electrode and the negative electrode to work. It has the advantages of light weight, large capacity, and no memory effect. general application. Lithium-ion batteries have been commercially available for decades and are used in a wide variety of electronic devices. Lithium-ion batteries are mainly composed of positive electrode materials, negative electrode materials, electrolytes, diaphragms, and battery casings. Among them, the physical and chemical activities of positive and negative electrode materials are the key to the performance of lithium-ion batteries. Therefore, the development of electrode materials with excellent performance, environmental friendliness and low cost has become a common research focus of researchers in the battery field. Specifically, the energy density and electrochemical performance of lithium-ion batteries depend on the physical and chemical properties of the positive and negative electrode materials. The selection of anode materials is one of the key factors to improve the energy density and safety of batteries. Compared with other components of lithium-ion batteries, the development of negative electrode materials for lithium-ion batteries is relatively mature. Many negative electrode materials for lithium-ion batteries have been disclosed in the prior art, such as carbon materials, silicon-based materials, tin-based materials, titanic acid Lithium, transition metal oxides, etc. Graphite carbon materials have relatively mature technology in commercial applications, relatively stable market prices, good performance in terms of safety and cycle life, and are cheap and non-toxic. They are relatively common negative electrode materials. But the specific capacity of commercialized graphite is only 372mAh g ^-1 , which greatly limits its application. In recent years, other scientific researchers have tried to replace traditional carbon materials with other emerging materials as negative electrode materials for lithium-ion batteries, such as zinc vanadate materials, which have much higher charge and discharge capacities than graphite carbon materials, and have special The channel structure can be used as a lithium ion intercalation/deintercalation carrier, and is expected to become a new type of high-power, high-capacity lithium-ion battery anode material. The patent application with the application number CN 103236531A discloses a lithium-ion battery zinc vanadate negative electrode material and its preparation method. A new type of lithium-ion battery negative electrode material zinc vanadate Zn ₃ with good crystallinity is prepared from zinc pyrovanadate as a precursor. (VO ₄ ) ₂ , the preparation of this material requires high-temperature treatment, complicated procedures, and high energy consumption. Moreover, the prepared negative electrode material has large particles, low electronic conductivity and ion conductivity, and poor rate performance. It is not suitable for high-power power. battery application.

Contents of the invention

For the problems existing in the prior art, the first object of the present invention is to provide a kind of preparation method of hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ 2H ₂ O) material, by the method of the present invention The prepared basic zinc pyrovanadate has a special morphology and high theoretical capacity, and the basic zinc pyrovanadate containing crystal water also contributes to its specific capacity, which breaks the traditional view and is suitable for lithium Potential ideal negative electrode material for ion batteries.

The preparation method of a hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material described above in the present invention comprises the following steps:

Dissolve vanadyl acetate VO(Ac) ₂ and zinc chloride in sequence in dimethylformamide solvent, stir evenly to obtain a dark green solution, then transfer the resulting dark green solution to a stainless steel reaction kettle, put the reaction kettle into Heat the oven to 120-180°C, then react at a constant temperature for 3-36 hours, and finally cool down to room temperature. The obtained product is washed with distilled water and absolute ethanol respectively, centrifugally filtered and then vacuum-dried to obtain the product hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material, wherein the molar ratio of vanadyl acetate VO(Ac) ₂ to zinc chloride is 1:1.5˜1:4.

Further, the heating time of the reaction kettle described in the above technical solution of the present invention in the oven is preferably 18-30 hours.

Furthermore, the heating time of the reaction kettle described in the above technical solution of the present invention in the oven is preferably 24 hours.

Further, the molar ratio of vanadyl acetate VO(Ac) ₂ and zinc chloride described in the above-mentioned technical scheme of the present invention is preferably 1:1.5 or 1:4.

Further, the heating temperature of the reaction kettle described in the above technical solution of the present invention in the oven is preferably 130-140°C.

Further, the vacuum drying temperature in the above technical solution of the present invention is preferably 60-80° C., and the drying time is preferably 8-12 hours.

Further, the product in the above technical solution of the present invention is washed alternately with distilled water and absolute ethanol, and the obtained product is preferably alternately washed with distilled water and absolute ethanol 2 to 3 times each.

In the technical scheme of the present invention, the reactor is a reactor with a polytetrafluoroethylene lining.

Further, the purity grades of the vanadyl acetate VO(Ac) ₂ and zinc chloride raw materials described in the above technical solutions of the present invention are all analytically pure or chemically pure grades.

Another object of the present invention is to provide an application of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared by the above method in lithium ion batteries.

The invention provides an electrode, wherein the raw material components of the electrode include the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared by the above method as an electrode active material.

The invention provides a lithium ion battery, the negative electrode material of the lithium ion battery comprises the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared by the above method.

Advantage of the present invention and positive effect are:

(1) The present invention adopts the solvothermal method to synthesize the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material. The method is low in cost, simple in operation, mild in reaction conditions, and does not require It is prepared by burning at high temperature, with low energy consumption, and the synthetic product has high purity and good crystallinity. The synthesized product is hydrated basic zinc pyrovanadate, and its unit cell parameters are consistent with the standard map JCPDS FileCardNo.50-0570;

(2) The hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ 2H ₂ O) material synthesized by the present invention, wherein the valence state of vanadium is pentavalent;

(3) the dimethyl formamide that the present invention adopts is not only as solvent, also plays the effect of templating agent in the present invention, is conducive to the ion in the reaction solution to carry out self-assembly, generates hydration basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) microsphere structure;

(4) The solvothermal reaction time of the present invention has an important influence on the product morphology: when the synthesis time is 3h, the product is an irregular small particle shape; when the synthesis time is 6h, the product shape is flake; when the synthesis time is 12h, Microspheres are formed in the product; when the synthesis time is 16 hours, the size distribution of the microspheres in the product is uneven; when the time is 24 hours, the size distribution of the formed microspheres is uniform, and the self-assembled structure of the microspheres is the most complete;

(5) The hydrated basic zinc pyrovanadate materials synthesized by the present invention all have good rate cycle performance, and when the current density is 100 mA g ^-1 , the specific capacity can be maintained above 500 mAh g ^-1 after 100 cycles respectively, And the product whose synthesis time is 24h has the best electrochemical performance. When the current density is 100mA g ^-1 , the product can maintain a specific capacity of 1240.76mAh g ^-1 after 100 cycles. When the current density is 1000mA g ^-1 , its specific capacity It is still 771.29mAh g ^-1 , and the charging platform of this material is about 1 volt;

(6) The hydrated basic zinc pyrovanadate material impedance synthesized by the present invention is small, the diffusion coefficient of lithium ions is large, and the product impedance obtained in 24h is the smallest in the synthesis time, and the diffusion coefficient of lithium ions is the largest. During the charge/discharge process, the battery The degree of polarization is small, and when the current density is 5Ag ^-1 , its specific capacity is 598.8mAhg ^-1 . Therefore, the hydrated basic zinc pyrovanadate material prepared by the present invention is used as the negative electrode material of the lithium-ion battery, and the entire battery system It not only has high lithium storage performance, but also has excellent cycle performance and excellent electrochemical performance. Compared with the materials in the prior art, it has great advantages and broad application prospects;

(7) The raw material source of the present invention is rich and cheap, and plays a role in promoting the development and utilization of mineral resources in southern Hubei and western Hubei.

Description of drawings

Fig. 1 is the X-ray diffraction result diagram of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Examples 1-5 of the present invention;

Fig. 2 is a scanning electron micrograph of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Examples 1-4 of the present invention;

3 is a scanning electron micrograph of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Example 5 of the present invention;

4 is a transmission electron microscope image of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Example 5 of the present invention;

5 is a thermogravimetric analysis diagram of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Example 5 of the present invention;

(a) in Fig. 6 is the XPS graph of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Example 5 of the present invention, and (b) is Zn 2p high-resolution spectrum; (c) is V 2p high-resolution spectrum; (d) is O 1s high-resolution spectrum.

Fig. 7 is a cycle performance graph of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Examples 1-5 of the present invention.

Fig. 8 is a rate cycle performance diagram of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Examples 1-5 of the present invention.

9 is a charge-discharge curve diagram of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Example 5 of the present invention;

Fig. 10 is the electrochemical impedance spectrum of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Examples 1-5 of the present invention;

Fig. 11 is a linear fitting diagram of the Warburg impedance of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Examples 1-5 of the present invention.

Detailed ways

The technical solution of the present invention will be described in further detail below through specific embodiments and accompanying drawings. The following embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to change them into equivalent embodiments with equal changes. Any simple modifications or equivalent changes made to the following embodiments according to the technical essence of the present invention without departing from the solution content of the present invention fall within the protection scope of the present invention.

Example 1

The preparation method of a hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material described in this example is prepared according to the following steps:

1mmol vanadyl acetate VO (Ac) ₂ and 1.5mmol zinc chloride are successively dissolved in 100 milliliters of dimethylformamide solvents, after stirring evenly, a dark green solution is obtained, then the gained dark green solution is transferred to a stainless steel reaction kettle, Put the reaction kettle into an oven and heat it to 120°C, then react at a constant temperature for 3 hours, and finally cool down to room temperature. The obtained product is washed alternately with distilled water and absolute ethanol for 3 times, then centrifugally filtered, and vacuum-dried to obtain the product hydrated basic zinc pyrovanadate ( Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material.

The X-ray diffraction results of the product hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared above in this embodiment are shown in (a) in Figure 1, the product The scanning electron microscopy results are shown in (a) in Figure 2.

As can be seen from the X-powder diffraction test results, the diffraction angles of the compounds prepared in this example are 12.29°, 20.95°, 30.10°, 32.06°, 34.19°, 36.46°, 42.65°, 51.63°, 52.72°, 61.24° and 62.58° corresponds to (001), (011), (012), (111), (020), (021), (022), (023), (122), (220) and (024) crystal planes respectively, The diffraction peaks are completely consistent with the standard spectrum (JCPDS File Card No.50-0570), indicating that the product synthesized in this example is Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O with a hexagonal structure.

It can be seen from the results of the product scanning electron microscope that most of the products prepared in this embodiment are irregular small particles.

Example 2

The preparation method of a hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material described in this example is prepared according to the following steps:

1mmol vanadyl acetate VO (Ac) ₂ and 2mmol zinc chloride are successively dissolved in 100 milliliters of dimethylformamide solvents, stir to obtain a dark green solution, then the gained dark green solution is transferred to a stainless steel reactor, and The reaction kettle was heated to 180°C in an oven, then reacted at a constant temperature for 6 hours, and finally cooled to room temperature. The obtained product was washed alternately with distilled water and absolute ethanol for 3 times, then centrifugally filtered, and vacuum-dried to obtain the product hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material.

The X-ray diffraction results of the product hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared above in this embodiment are shown in (b) in Figure 1, the product The scanning electron microscopy results are shown in (b) in Figure 2.

As can be seen from the X-powder diffraction test results, the diffraction angles of the compounds prepared in this example are 12.29°, 20.95°, 30.10°, 32.06°, 34.19°, 36.46°, 42.65°, 51.63°, 52.72°, 61.24° and 62.58° corresponds to (001), (011), (012), (111), (020), (021), (022), (023), (122), (220) and (024) crystal planes respectively, The diffraction peaks are completely consistent with the standard spectrum (JCPDS File Card No.50-0570), indicating that the product synthesized in this example is Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O with a hexagonal structure.

It can be seen from the scanning electron microscope results of the product that most of the products prepared in this example have a sheet-like structure.

Example 3

The preparation method of a hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material described in this example is prepared according to the following steps:

1mmol vanadyl acetate VO (Ac) ₂ and 2.5mmol zinc chloride are dissolved in 100 milliliters of dimethylformamide solvents successively, after stirring uniformly, a dark green solution is obtained, then the gained dark green solution is transferred to a stainless steel reaction kettle, Put the reaction kettle into an oven and heat it to 180°C, then react at a constant temperature for 12 hours, and finally cool down to room temperature. The obtained product is washed alternately with distilled water and absolute ethanol for 3 times, then centrifugally filtered, and vacuum-dried to obtain the product hydrated basic zinc pyrovanadate ( Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material.

The X-ray diffraction results of the product hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material obtained above in this embodiment are shown in (c) in Figure 1, the product The scanning electron microscopy results are shown in (c) in Figure 2.

As can be seen from the X-powder diffraction test results, the diffraction angles of the compounds prepared in this example are 12.29°, 20.95°, 30.10°, 32.06°, 34.19°, 36.46°, 42.65°, 51.63°, 52.72°, 61.24° and 62.58° corresponds to (001), (011), (012), (111), (020), (021), (022), (023), (122), (220) and (024) crystal planes respectively, The diffraction peaks are completely consistent with the standard spectrum (JCPDS File Card No.50-0570), indicating that the product synthesized in this example is Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O with a hexagonal structure.

It can be seen from the scanning electron microscope results of the product that the shape of the product prepared in this embodiment is mostly a microsphere structure assembled from nanosheets.

Example 4

The preparation method of a hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material described in this example is prepared according to the following steps:

1mmol vanadyl acetate VO (Ac) ₂ and 4mmol zinc chloride are successively dissolved in 100 milliliters of dimethylformamide solvents, stir to obtain a dark green solution, then the gained dark green solution is transferred to a stainless steel reactor, and The reaction kettle was heated to 160°C in an oven, then reacted at a constant temperature for 18 hours, and finally cooled to room temperature. The obtained product was washed alternately with distilled water and absolute ethanol for 3 times, then centrifugally filtered, and vacuum-dried to obtain the product hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material.

The X-ray diffraction results of the product hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared above in this embodiment are shown in (d) in Figure 1, the product The scanning electron microscopy results are shown in (d) in Figure 2.

As can be seen from the X-powder diffraction test results, the diffraction angles of the compounds prepared in this example are 12.29°, 20.95°, 30.10°, 32.06°, 34.19°, 36.46°, 42.65°, 51.63°, 52.72°, 61.24° and 62.58° corresponds to (001), (011), (012), (111), (020), (021), (022), (023), (122), (220) and (024) crystal planes respectively, The diffraction peaks are completely consistent with the standard spectrum (JCPDS File Card No.50-0570), indicating that the product synthesized in this example is Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O with a hexagonal structure.

It can be seen from the scanning electron microscope results of the product that the shape of the product prepared in this embodiment is mostly a microsphere structure assembled from nanosheets.

Example 5

The preparation method of a hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material described in this example is prepared according to the following steps:

1mmol vanadyl acetate VO (Ac) ₂ and 4mmol zinc chloride are successively dissolved in 100 milliliters of dimethylformamide solvents, stir to obtain a dark green solution, then the gained dark green solution is transferred to a stainless steel reactor, and The reaction kettle was heated to 140°C in an oven, then reacted at a constant temperature for 24 hours, and finally cooled to room temperature. The obtained product was washed alternately with distilled water and absolute ethanol for 3 times, centrifugally filtered, and vacuum-dried to obtain the product hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material.

The X-ray diffraction results of the product hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared above in this embodiment are shown in (e) in Figure 1, the product The results of scanning electron microscopy are shown in Figure 3, the results of transmission electron microscopy of the product are shown in Figure 4, and the results of thermogravimetric analysis of the product are shown in Figure 5.

As can be seen from the X-powder diffraction test results, the diffraction angles of the compounds prepared in this example are 12.29°, 20.95°, 30.10°, 32.06°, 34.19°, 36.46°, 42.65°, 51.63°, 52.72°, 61.24° and 62.58° corresponds to (001), (011), (012), (111), (020), (021), (022), (023), (122), (220) and (024) crystal planes respectively, Its diffraction peaks are completely consistent with the standard spectrum (JCPDS File Card No.50-0570), indicating that the product synthesized in this example is Zn ₃ V ₂ O ₇ (OH) ₂ 2H ₂ O with a hexagonal structure, and according to XRD It can be seen from the diffraction intensity that the crystallinity of the compound prepared in this example is better.

From the scanning electron microscope results of the product, it can be seen that the shape of the product prepared in this embodiment is a regular microsphere structure, and the microsphere structure is assembled from regular nanosheets. It can be further seen from the results of the transmission electron microscope of the product that the thickness of the nanosheets with the microsphere structure in the self-assembled embodiment is about 10 nm.

The weight loss rate of the product at different temperatures can be further confirmed by the thermogravimetric analysis in Figure 5. When the temperature rises from 100°C to 600°C, the weight loss rate reaches 12.32%, and about 1% of the adsorbed water is deducted, which is consistent with the theoretical weight loss rate of the product. 11.27% is similar.

Example 6

The electrochemical properties of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) materials obtained in the above-mentioned Examples 1 to 5 were tested respectively, and the test methods were as follows:

The products prepared in each example were prepared into electrodes (the ratio of active material to acetylene black and binder was 7:2:1), pressed on a nickel mesh, and dried in a vacuum oven at 120°C for 24 hours. The electrolyte is a mixed solution of ethylene carbonate and dimethylethylene carbonate (1:1) containing 1M LiPF ₆ , the diaphragm is Celgard 2400, and the reference electrode is a lithium sheet. Assemble the simulated battery in the glove box, charge and discharge the voltage range (0.01 ~ 3.00V), current density (100mA/g), and test the performance of the battery. Impedance was tested by Shanghai Chenhua Electrochemical Workstation (CHI 600A).

The cycle performance diagram and rate cycle performance diagram of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) prepared in Examples 1 to 5 of the present invention are shown in Figure 7 and Figure 8 respectively shown.

It can be seen from Fig. 8 that the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) prepared by the present invention has excellent excellent rate performance, and the one prepared from Example 5 From the rate cycle performance diagram of the product, it can be seen that when the current density is 100mAg ^-1 , 200mAg ^-1 , 500mAg ^-1 , 800mAg ^-1 , 1000mAg ^-1 , 2000mAg ^-1 , 5000mAg ^-1 , the discharge ratio The capacity is 1130.2mAg ^-1 , 1051.3mAg ^-1 , 885.0mAg ^-1 , 829.3mAg ^-1 , 771.3mAg ^-1 , 716.4mAg ^-1 , 598.8mAh g ^-1 , when the current density returns to 100mAg ^-1 , the discharge capacity It recovered to 1256.6mAh g ^-1 , indicating that the rate performance of the product synthesized in Example 5 was the best.

Fig. 9 is a graph showing charge and discharge curves of the product prepared in Example 5 at a voltage range of 0.01-3V when the current density is 100mAg ^-1 . It can be seen from Figure 9 that the initial charge and discharge capacities of the product are 1179.6mAh g ^-1 and 1598.7mAhg ^-1 respectively, and its coulombic efficiency is 73.8%, and the charge and discharge capacities of the second cycle are 1120.4mAh g ^-1 respectively , 1222.1mAh g ^-1 , and its Coulombic efficiency is 91.7%. The formation of a solid electrolyte membrane leads to low first-cycle Coulombic efficiency. When cycled 100 times, its discharge capacity remained at 1240.76mAh g ^-1 .

Example 7

The impedance properties of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) materials prepared in the above-mentioned Examples 1 to 5 were respectively tested, and the test method was as follows: The obtained product is made into an electrode, and the amount of active material of the control electrode is basically the same, and the area is similar, and it is assembled into a simulated battery, and its impedance is measured by Shanghai Chenhua Electrochemical Workstation (CHI 600A, test conditions: selected test frequency range 0.01 to The scan rate is 0.1mV/sec., according to the formula:

Through the determination of the Warburg coefficient A _w . To infer the changing trend of lithium ion diffusion absorption number.

The electrochemical impedance spectrum of the hydrated basic zinc pyrovanadate (Zn ₃ V ₂ O ₇ (OH) ₂ ·2H ₂ O) material prepared in Examples 1-5 of the present invention is shown in FIG. 10 . It can be seen that the impedances of the products prepared in Examples 1 to 5 are 136.5Ω, 105.1Ω, 75.48Ω, 64.47Ω, and 26.71Ω respectively, that is, the impedance of the material obtained in Example 5 is the smallest. In addition, for the linear fitting of the Warburg impedance, through the calculation of the Warburg coefficient A _w (the slope of the straight line shown in Figure 11), it is found that the A _w of the products prepared in Examples 1 to 5 are respectively 201.11Ωs ^{-1 /2} , 151.22Ωs-1/2, 98.55Ωs ^-1/2 , 76.93Ωs ^-1/2 , 49.63Ωs ^-1/2 , so as to infer their corresponding lithium ion diffusion coefficients, the test results show that the embodiment of the present invention The lithium ion diffusion coefficients of the products obtained in 1 to 5 are relatively large, and the _Aw of the product obtained in Example 5 is the smallest when used as an electrode, so the lithium ion diffusion coefficient is the largest, which further illustrates the performance of the material obtained in Example 5. more excellent electrochemical performance.

Claims (8)

1. a kind of hydrated basic pyrovanadic acid zinc (Zn₃V₂O₇(OH)₂·2H₂O) the preparation method of material, it is characterised in that：The side Method includes the following steps：

By acetic acid vanadyl VO (Ac)₂It is dissolved into solvent dimethylformamide successively with zinc chloride, bottle green is obtained after stirring evenly Then gained dark green solution is transferred in stainless steel cauldron by solution, reaction kettle is put into baking oven is heated to 120~180 3~36h of isothermal reaction after DEG C is finally cooled to room temperature, and products therefrom is washed respectively with distilled water and absolute ethyl alcohol, centrifugal filtration After be dried in vacuo, obtain product hydrated basic pyrovanadic acid zinc (Zn₃V₂O₇(OH)₂·2H₂O) material, wherein：The acetic acid vanadyl VO (Ac)₂Molar ratio with zinc chloride is 1:1.5~1:4.

2. hydrated basic pyrovanadic acid zinc (Zn according to claim 1₃V₂O₇(OH)₂·2H₂O) the preparation method of material, It is characterized in that：The heating time of the reaction kettle in an oven is 18~30h.

3. hydrated basic pyrovanadic acid zinc (Zn according to claim 2₃V₂O₇(OH)₂·2H₂O) the preparation method of material, It is characterized in that：The heating time of the reaction kettle in an oven is for 24 hours.

4. hydrated basic pyrovanadic acid zinc (Zn according to claim 1 or 2₃V₂O₇(OH)₂·2H₂O) the preparation method of material, It is characterized in that：The heating temperature of the reaction kettle in an oven is 130~140 DEG C.

5. hydrated basic pyrovanadic acid zinc (Zn according to claim 1 or 2₃V₂O₇(OH)₂·2H₂O) the preparation method of material, It is characterized in that：The acetic acid vanadyl VO (Ac)₂Molar ratio with zinc chloride is 1:1.5 or 1:4.

6. hydrated basic pyrovanadic acid zinc (Zn according to claim 1 or 2₃V₂O₇(OH)₂·2H₂O) the preparation method of material, It is characterized in that：The vacuum drying temperature is 60~80 DEG C, and drying time is 8~12h.

7. a kind of electrode, it is characterised in that：Any one of claim 1~2 the method system is included in the electrode material component The hydrated basic pyrovanadic acid zinc (Zn obtained₃V₂O₇(OH)₂·2H₂O) material is as electrode active material.

8. a kind of lithium ion battery, it is characterised in that：It is any that the negative material of the lithium ion battery includes claim 1~2 Hydrated basic pyrovanadic acid zinc (Zn made from the method on item₃V₂O₇(OH)₂·2H₂O) material.