CN108807961A - A kind of zinc-base cell negative electrode material and preparation method thereof - Google Patents

Abstract

The invention relates to a negative electrode material for a zinc-based battery and a preparation method thereof. The negative electrode material includes a zinc base and graphene loaded on the surface of the zinc base. The preparation includes the following steps: (1) after surface treatment of the zinc base, place the zinc base on (2) place graphene oxide in water, and ultrasonically disperse to obtain a graphene oxide solution; (3) place the treated zinc base in the graphene oxide solution for reaction, and then Soak in deionized water and electrolyte respectively to obtain the zinc-based battery negative electrode material. Compared with the prior art, the negative electrode material of the present invention circulates stably for 150 cycles in a zinc sulfate electrolyte with a current density of 0.2 milliamperes per square centimeter and 0.5 moles per liter, effectively inhibiting the growth of dendrites from piercing the separator during the cycle Phenomenon; and the preparation method is simple, suitable for large-scale application.

Description

A kind of negative electrode material of zinc-based battery and preparation method thereof

technical field

The invention relates to the field of energy storage materials, in particular to a zinc-based battery negative electrode material and a preparation method thereof.

Background technique

Due to environmental pollution and energy shortage, new energy secondary batteries have become a focus of attention and research. Zinc-based battery is a very important energy storage device, because of the abundant reserves and high energy density of metal zinc, it occupies a large market share in traditional primary batteries. Aqueous zinc-ion batteries, zinc-air batteries and other secondary batteries have high energy density, less environmental pollution, and the battery technology is simpler than organic battery systems, and the price is low. At the same time, it can effectively avoid thermal runaway in existing commercial lithium batteries, etc. Security issues have received widespread attention. At present, aqueous zinc-ion batteries still have problems such as dendrites, self-discharge, volume expansion, and coulombic efficiency, especially because the dendrites growing during the cycle puncture the separator and cause a short circuit of the battery, which limits the further development of aqueous zinc-ion batteries. Therefore, it is particularly important to solve the problem of dendrite growth of negative electrode materials. It can be said that negative electrode materials determine whether zinc-ion batteries can be commercialized. Therefore, the development of negative electrode materials with excellent performance is one of the most critical issues in the study of zinc-based batteries.

Contents of the invention

The object of the present invention is to provide a zinc-based battery negative electrode material and a preparation method thereof that can effectively solve the dendrite growth problem of the negative electrode material in order to overcome the above-mentioned defects in the prior art.

The object of the present invention can be achieved through the following technical solutions: a zinc-based battery negative electrode material, the negative electrode material includes a zinc base and graphene loaded on the surface of the zinc base, wherein the thickness of the graphene is 0.1-100 μm. The present invention loads graphene on the zinc-based surface to form a single-layer or few-layer layer, which not only effectively increases the contact area between the zinc negative electrode and the electrolyte, but also these single-layer or few-layer and uniformly dispersed graphene is A physical buffer layer is formed on the surface of the sheet, which reduces the volume change of the negative electrode material during the cycle. After 300 hours of cycling, the battery can still be charged and discharged normally, while the zinc sheet before modification is cycled for about 100 hours. It was unstable at the beginning, and the battery was completely short-circuited after cycling for about 140 hours. The modified zinc anode effectively solved the problem of dendrites piercing the separator.

The zinc base is zinc plate, zinc sheet or zinc foil.

A preparation method of the zinc-based battery negative electrode material as described above, comprising the following steps:

(1) After the surface treatment of the zinc base, place it in dilute acid to remove the surface oxide layer, and set it aside;

(2) graphene oxide is placed in water, and ultrasonically dispersed to obtain a graphene oxide solution;

(3) Put the treated zinc-based battery in a graphene oxide solution for reaction, and then soak it in deionized water and electrolyte solution respectively to obtain the negative electrode material of the zinc-based battery.

The metal zinc sheet is placed in the graphene aqueous solution. Due to the potential difference between the two, the graphene oxide is electrostatically adsorbed on the surface of the zinc sheet, and electron exchange occurs, that is, a redox reaction occurs, so that the metal zinc loses electrons and becomes zinc ions. The surface functional groups on the alkene get electrons so that the graphene oxide is reduced.

The surface treatment comprises the following steps: placing the zinc base in an acetone solution, ultrasonic cleaning, and then sequentially washing the surface with absolute ethanol and deionized water. The above operations can remove organic pollutants on the zinc-based surface.

The dilute acid includes dilute hydrochloric acid, dilute sulfuric acid, hydrofluoric acid or acetic acid, and the mass concentration of the dilute acid is 1%-3%. Soaking in dilute acid can remove the oxide layer on the zinc-based surface, making the zinc-based surface show strong reducibility.

The residence time of the zinc group in dilute acid is 1-10s.

The concentration of the graphene oxide solution is 0.01-3 g/L. The graphene oxide of the present invention can be prepared by multi-step oxidation of graphite using the hummers method, or can be prepared by activation of commercial graphene oxide. details as follows:

1. Preparation of intercalated graphite: Put flake graphite (32 mesh) into a mixed solution of concentrated sulfuric acid and concentrated nitric acid (volume ratio 3/1), let it stand for about 12 hours, wash and filter with deionized water, wash thoroughly, and dry at 120°C About 12 hours.

2 Preparation of heat-expandable graphite: raise the temperature of the tube furnace to 1050°C, place the intercalated graphite in the magnetic boat and send it into the tube furnace to expand for about 10 seconds (until the volume of the black solid in the magnetic boat stops expanding).

3 Preparation of pre-oxidized graphite: Add 3 grams of intercalated graphite, 3 grams of potassium persulfate, 3 grams of phosphorus pentoxide, and 250 milliliters of concentrated sulfuric acid into a three-necked flask, stir well and then slowly heat up to 80°C, keep warm for 5 hours, and cool After reaching room temperature, slowly pour into the ice-water mixture, stir until the exotherm is complete, filter, and fully wash with deionized water. Dry at 120°C for 12 hours.

4 Preparation of graphite oxide: Add 3 grams of pre-oxidized graphite and 250 ml of concentrated sulfuric acid to the three-necked flask, stir well at room temperature, place the three-necked flask in an ice-water bath, and then slowly add 15 grams of potassium permanganate to the three-necked flask After the potassium permanganate is completely added, remove the ice-water bath, stir at room temperature for one hour, then slowly raise the temperature to 35°C, and react for 2 hours. After the reaction, the reaction solution was poured into a large amount of ice-water mixture, stirred until the solution was completely exothermic, and then 40 ml of hydrogen peroxide was added. Collect the precipitate by centrifugation, wash the precipitate several times with 10% dilute hydrochloric acid (use saturated barium chloride to detect the absence of sulfate ions in the solution), and then wash with deionized water until the solution is neutral. The bottom graphite oxide was collected.

The reaction time is 0.1-10 hours.

The electrolyte is 0.5-3M zinc sulfate aqueous solution. After the zinc sheet was left standing in the graphene solution for a period of time, a layer of reduced graphene oxide was adsorbed on its surface. After the reaction was completed, the zinc sheet with the reduced graphene oxide adsorbed on the surface was soaked in water to remove the unreduced graphene oxide on the surface, and then Soak in the electrolyte to allow the electrolyte to fully infiltrate the graphene film on the surface of the zinc sheet to prevent the concentration of the electrolyte from decreasing due to the water present between the graphene film layers during the subsequent assembly of the battery.

Compared with the prior art, the beneficial effects of the present invention are reflected in the following aspects:

(1) The negative electrode material of the present invention circulates stably for 150 circles in a zinc sulfate electrolyte with a current density of 0.2 milliamperes per square centimeter and 0.5 moles per liter, effectively suppressing the phenomenon of dendrite growth piercing the diaphragm during the circulation process;

(2) The preparation method of the present invention is simple and suitable for large-scale application.

Description of drawings

Fig. 1 is the infrared spectrogram before and after graphene oxide reduction;

Fig. 2 is the cross-sectional scanning electron microscope picture of graphene after zinc surface adsorption;

Fig. 3 is a scanning electron microscope image of a graphene membrane cross-section after ten cycles;

Fig. 4 is a charge-discharge-discharge cycle curve with a current density of 0.2mA/cm ² and a charge-discharge capacity of 0.2mAh/cm ² .

Detailed ways

The following is a detailed description of the embodiments of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

Example 1

A preparation method for a zinc ion secondary battery negative electrode material, comprising the steps of:

(1) Pretreatment of metal zinc: Cut a zinc sheet with a thickness of 0.3 mm into a disc with a diameter of 16 mm, place it in acetone, ultrasonically clean it for 30 minutes, and then wash it with absolute ethanol and deionized water in order to remove zinc Oil stains on the surface of the zinc sheet, then soaked in 1% hydrochloric acid for 10 seconds to remove the oxide layer on the surface of the zinc sheet, then rinsed with deionized water, and dried for later use;

(2) Preparation of graphene oxide solution: use 32-mesh flake graphite as raw material, use hummers to prepare graphite oxide, after centrifugal cleaning, collect graphite oxide in the centrifuge tube and freeze-dry, weigh 0.1g of graphite oxide after drying and add 1L to remove Ionized water, after stirring and ultrasonic stripping, a graphene oxide aqueous solution with uniform color is obtained.

(3) Graphene oxide is reduced and adsorbed on the surface of the zinc sheet: put the pretreated zinc sheet into the graphene oxide solution, let it stand for 30 minutes, and then take it out.

(4) Electrode pretreatment: Take out the reacted zinc flakes, soak them in deionized water for 5 seconds, then soak them in 0.5M/L zinc sulfate spot solution for 5 seconds, and then directly pack them into button cells for charging. chemical test.

Figure 1 is the infrared absorption spectrum of the zinc sheet in Example 1 placed in the graphene oxide aqueous solution to absorb and reduce the graphene oxide film, and graphene oxide. I can see from the figure that the absorption peak between carbon and oxygen becomes weaker after reduction, indicating that The oxygen-containing functional groups on the surface of the reduced graphene oxide on the surface of the zinc sheet are reduced, and the graphene oxide is reduced.

2 is a scanning electron microscope cross-sectional view of the reduced graphene oxide on the surface of the zinc sheet in Example 1 after natural drying. From the figure, it can be seen that the graphene sheets are stacked uniformly and orderly in layers.

Fig. 3 is embodiment 1, is modified with the zinc flake of reduced graphene oxide film after passing through 10 circles of circulations cross-sectional view, can find that there is evenly distributed metal zinc in the middle of graphene film through 10 circles of circulations from figure, illustrates in Metal gold deposits and dissolves between graphene layers during cyclic charging and discharging.

Fig. 4 is a charge-discharge cycle curve of the negative electrode obtained in Example 1 at a current density of 0.2 mA/cm ² and a charge-discharge capacity of 0.2 mAh/cm ² . It can be seen from the above that the performance of the negative electrode material prepared in this example remains basically unchanged after 300 times of charging and discharging, which is far superior to the pure Zn negative electrode material.

Implementation column 2

(1) Pretreatment of metal zinc: Cut a zinc sheet with a thickness of 0.2 mm into a disc with a diameter of 15 mm, place it in acetone, ultrasonically clean it for 30 minutes, and then wash it with absolute ethanol and deionized water in order to remove zinc Oil stains on the surface of the zinc sheet, then soaked in 1% hydrochloric acid for 10 seconds to remove the oxide layer on the surface of the zinc sheet, then rinsed with deionized water, and dried for later use

(2) Preparation of graphene oxide solution: use 64-mesh flake graphite as raw material, use hummers to prepare graphite oxide, after centrifugal cleaning, collect graphite oxide in the centrifuge tube and freeze-dry, weigh 0.5g of dried graphite oxide and add 1L to remove Ionized water, after stirring and ultrasonic stripping, a graphene oxide aqueous solution with uniform color is obtained.

(3) Graphene oxide is reduced and adsorbed on the surface of the zinc sheet: put the pretreated zinc sheet into the graphene oxide solution, let it stand for 50 minutes, and then take it out.

(4) Electrode pretreatment: Take out the reacted zinc flakes, first soak them in deionized water for 10 seconds, then soak them in 0.5M/L zinc sulfate spot solution for 5 seconds, and then directly pack them into button cells for charging. chemical test.

It has been verified that the anode material prepared in this embodiment effectively inhibits the phenomenon of dendrite growth piercing the separator during the cycle, and has a long service life.

Example 3

(1) Pretreatment of metal zinc: Cut a zinc sheet with a thickness of 0.1 mm into a disc with a diameter of 15 mm, place it in acetone, ultrasonically clean it for 50 minutes, and then wash it with absolute ethanol and deionized water in order to remove zinc Oil stains on the surface of the zinc sheet, then soaked in 3% hydrochloric acid for 5 seconds to remove the oxide layer on the surface of the zinc sheet, then rinsed with deionized water, and dried for later use

(2) Preparation of graphene oxide solution: use 128-mesh flake graphite as raw material, use hummers to prepare graphite oxide, after centrifugal cleaning, collect graphite oxide in the centrifuge tube and freeze-dry, weigh 2 g of dried graphite oxide and add 1 L of deionized water, a graphene oxide aqueous solution with uniform color was obtained after stirring and ultrasonic stripping.

(3) Graphene oxide is reduced and adsorbed on the surface of the zinc sheet: put the pretreated zinc sheet into the graphene oxide solution, let it stand for 20 minutes, and then take it out.

(4) Electrode pretreatment: Take out the reacted zinc flakes, soak them in deionized water for 10 seconds, then soak them in 1M/L zinc sulfate spot solution for 5 seconds, and then directly pack them into button cells for electrochemical test.

It has been verified that the anode material prepared in this embodiment effectively inhibits the phenomenon of dendrite growth piercing the separator during the cycle, and has a long service life.

Example 4

(1) Pretreatment of metal zinc: Cut a zinc sheet with a thickness of 0.1 mm into a disc with a diameter of 15 mm, place it in acetone, clean it ultrasonically for 30 minutes, and then wash it with absolute ethanol and deionized water in order to remove zinc Oil stains on the surface of the zinc sheet, then soaked in 2% hydrochloric acid for 5 seconds to remove the oxide layer on the surface of the zinc sheet, then rinsed with deionized water, and dried for use

(2) Preparation of graphene oxide solution: use 128-mesh flake graphite as raw material, use hummers to prepare graphite oxide, after centrifugal cleaning, collect graphite oxide in the centrifuge tube and freeze-dry, weigh 3g of dried graphite oxide and add 1L deionized water, a graphene oxide aqueous solution with uniform color was obtained after stirring and ultrasonic stripping.

(3) Graphene oxide is reduced and adsorbed on the surface of the zinc sheet: put the pretreated zinc sheet into the graphene oxide solution, let it stand for 20 minutes, and then take it out.

(4) Electrode pretreatment: Take out the reacted zinc flakes, soak them in deionized water for 10 seconds, then soak them in 1M/L zinc sulfate spot solution for 5 seconds, and then directly pack them into button cells for electrochemical test.

It has been verified that the anode material prepared in this embodiment effectively inhibits the phenomenon of dendrite growth piercing the separator during the cycle, and has a long service life.

Example 5

(1) Pretreatment of metal zinc: Cut a zinc sheet with a thickness of 0.1 mm into a disc with a diameter of 15 mm, place it in acetone, clean it ultrasonically for 30 minutes, and then wash it with absolute ethanol and deionized water in order to remove zinc Oil stains on the surface of the zinc sheet, then soaked in 2% hydrochloric acid for 5 seconds to remove the oxide layer on the surface of the zinc sheet, then rinsed with deionized water, and dried for use

(2) Preparation of graphene oxide solution: Mix and grind commercial graphene and potassium hydroxide at a ratio of 1:2 to 1:5, then put the mixture in a nitrogen atmosphere at 600 to 900 degrees for 3 hours, and then use 1M graphene Wash with hydrochloric acid until neutral, and after drying, weigh 1 g of graphene and disperse it in 1 L of water. After stirring and ultrasonic stripping, an aqueous solution of graphene oxide with uniform color is obtained.

(3) Graphene oxide is reduced and adsorbed on the surface of the zinc sheet: put the pretreated zinc sheet into the graphene oxide solution, let it stand for 20 minutes, and then take it out.

(4) Electrode pretreatment: Take out the reacted zinc flakes, soak them in deionized water for 10 seconds, then soak them in 1M/L zinc sulfate spot solution for 5 seconds, and then directly pack them into button cells for electrochemical test.

It has been verified that the anode material prepared in this embodiment effectively inhibits the phenomenon of dendrite growth piercing the separator during the cycle, and has a long service life.

Example 6

(1) Pretreatment of metal zinc: Cut a zinc sheet with a thickness of 0.2 mm into a disc with a diameter of 15 mm, place it in acetone, clean it ultrasonically for 40 minutes, and then wash it with absolute ethanol and deionized water in order to remove zinc Oil stains on the surface of the zinc sheet, then soaked in 2% hydrochloric acid for 5 seconds to remove the oxide layer on the surface of the zinc sheet, then rinsed with deionized water, and dried for use

(2) Preparation of graphene oxide solution: Mix and grind commercial graphene and potassium hydroxide at a ratio of 1:2 to 1:5, then put the mixture in a nitrogen atmosphere at 600 to 900 degrees for 3 hours, and then use 1M graphene Wash with hydrochloric acid until neutral, and after drying, weigh 0.5 g of graphene and disperse it in 1 L of water. After stirring and ultrasonic stripping, an aqueous solution of graphene oxide with uniform color is obtained.

(3) Graphene oxide is reduced and adsorbed on the surface of the zinc sheet: put the pretreated zinc sheet into the graphene oxide solution, let it stand for 10 minutes, and then take it out.

(4) Electrode pretreatment: Take out the reacted zinc flakes, soak them in deionized water for 10 seconds, then soak them in 1M/L zinc sulfate spot solution for 5 seconds, and then directly pack them into button cells for electrochemical test.

It has been verified that the anode material prepared in this embodiment effectively inhibits the phenomenon of dendrite growth piercing the separator during the cycle, and has a long service life.

Claims (9)

1. A negative electrode material for a zinc-based battery, characterized in that the negative electrode material comprises a zinc base and graphene loaded on the surface of the zinc base, wherein the thickness of the graphene is 0.1-100 μm. 2. A negative electrode material for a zinc-based battery according to claim 1, wherein the zinc-based material is a zinc plate, zinc sheet or zinc foil. 3. a preparation method of zinc-based battery negative electrode material as claimed in claim 1 or 2, is characterized in that, comprises the following steps: (1) After the surface treatment of the zinc base, place it in dilute acid to remove the surface oxide layer, and set it aside; (2) graphene oxide is placed in water, and ultrasonically dispersed to obtain a graphene oxide solution; (3) Put the treated zinc-based battery in a graphene oxide solution for reaction, and then soak it in deionized water and electrolyte solution respectively to obtain the negative electrode material of the zinc-based battery. 4. The preparation method of a negative electrode material for a zinc-based battery according to claim 3, wherein said surface treatment comprises the following steps: placing the zinc-based battery in an acetone solution, ultrasonically cleaning, and then successively washing with absolute ethanol Rinse the surface with deionized water. 5. the preparation method of a kind of zinc-based battery negative electrode material according to claim 3 is characterized in that, described dilute acid comprises dilute hydrochloric acid, dilute sulfuric acid, hydrofluoric acid or acetic acid, and the mass concentration of described dilute acid is 1 %~3%. 6 . The preparation method of a negative electrode material for a zinc-based battery according to claim 5 , wherein the residence time of the zinc-based battery in dilute acid is 1-10 s. 7 . The preparation method of a negative electrode material for a zinc-based battery according to claim 3 , wherein the concentration of the graphene oxide solution is 0.01˜3 g/L. 8 . The preparation method of a zinc-based battery negative electrode material according to claim 3 , wherein the reaction time is 0.1-10 h. 9 . The preparation method of a zinc-based battery negative electrode material according to claim 3 , wherein the electrolyte is a 0.5-3M zinc sulfate aqueous solution.