CN108288695B - Zinc-based secondary battery negative electrode material and preparation method thereof - Google Patents

Abstract

The invention relates to a negative electrode material for a zinc-based secondary battery and a preparation method thereof. The modification reagent is added to make the surface of zinc oxide evenly distributed with positive charges, and the cationic resin is uniformly coated on the surface of zinc oxide through electrostatic adsorption, with a thickness of 5 nm. ~50nm. The zinc oxide coated with the cation resin is put into the mixed metal salt solution and stirred, the metal ions are uniformly adsorbed in the coating layer of the cation resin, and a reducing agent is added to reduce the metal ions to 3nm-7nm metal element. The cationic resin coated on the surface of zinc oxide can effectively inhibit the diffusion of Zn(OH) ₄ ^2- into the electrolyte, prevent or slow down the deformation of the zinc anode and the growth of dendrites during the charge-discharge cycle, and adsorbed in the cationic resin layer. High-grade metal particles can improve hydrogen evolution overpotential and Coulomb efficiency, and reduce hydrogen evolution corrosion and dendrite growth. The invention can improve the cycle performance of the zinc negative electrode, which is beneficial to the marketization of the zinc-based secondary battery.

Description

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

technical field

The invention relates to the field of preparation of negative electrode materials for alkaline secondary batteries, in particular to a negative electrode material for zinc-based secondary batteries and a preparation method thereof.

technical background

With the improvement of people's awareness of environmental protection, the development of new secondary power batteries with green environmental protection, long cycle life, safety and reliability has become a hot research topic in various countries. Zinc-based secondary batteries have the advantages of high operating voltage, high energy density and power density, and no memory effect. Compared with lithium-ion batteries, zinc-based secondary batteries are water-based batteries, which will not pollute the environment in the process of production and use. Moreover, zinc-based secondary batteries are rich in reserves and low in cost, making zinc-based secondary batteries a broad market. application prospects.

However, the current bottleneck hindering the market application of zinc-based secondary batteries is that the zinc anode has serious deformation, zinc dendrite growth, hydrogen evolution corrosion and other problems during the charge-discharge cycle, resulting in rapid battery capacity decay and short cycle life. The root cause of the deformation and dendrite growth of the zinc anode is that zinc oxide is easily dissolved in the alkaline electrolyte to form Zn(OH) ₄ ^2- . During the repeated charging process, the uneven deposition of Zn(OH) ₄ ^2- in the electrolyte It will cause the deformation of the electrode and the growth of dendrites. At present, there are two main methods for inhibiting the dissolution of zinc oxide into the electrolyte: (1) adding some additives to the electrode or electrolyte; (2) coating the surface of zinc oxide particles with a layer of organic or inorganic substances. The method of coating is a way to effectively inhibit the dissolution of zinc oxide, but the coating material currently used only reduces the contact area between zinc oxide and electrolyte, and cannot prevent Zn(OH) ₄ ^2- to electrolysis. There are still problems of zinc electrode deformation and dendrite growth due to liquid diffusion, and the currently used coating materials cannot effectively suppress the generation of hydrogen. Therefore, it is necessary to find a coating material that can effectively inhibit the diffusion of Zn(OH) ₄ ^2- into the electrolyte, and at the same time can effectively inhibit the hydrogen evolution corrosion.

SUMMARY OF THE INVENTION

None of the current coating materials can effectively inhibit the diffusion of Zn(OH) ₄ ^2- into the electrolyte and the hydrogen evolution corrosion. The present invention provides a method for coating zinc oxide with metal-adsorbed cation resin, and prepares a new negative electrode material of zinc-based secondary battery. The cationic resin coated on the surface of zinc oxide has a strong electrostatic repulsion effect on Zn(OH) ₄ ^2- , which can effectively prevent the diffusion of Zn(OH) ₄ ^2- generated during the discharge process into the electrolyte and reduce oxidation The amount of zinc dissolved in the electrolyte can effectively inhibit the deformation and dendrite growth of the zinc anode during charging and discharging. At the same time, the nano metal particles adsorbed in the cation resin can improve the hydrogen evolution overpotential and Coulomb efficiency, and reduce the hydrogen evolution corrosion.

A negative electrode material for a zinc-based secondary battery of the present invention comprises the following components by weight percentage:

Zinc oxide is 85% to 95%, and the particle size distribution of the zinc oxide is between 50nm and 950nm;

The cation resin is 2% to 12%; in the cation resin, the perfluorosulfonic acid resin accounts for 75% to 95% of the cation resin, and the rest of the cation resin accounts for 5% to 25%; the cation resin is evenly coated on the surface of the zinc oxide, and the thickness is Between 5nm and 50nm,

1% to 3% of metals, the metals include non-rare earth metals and rare earth metals, wherein the mass ratio of non-rare earth metals and rare earth metals is between (1 to 5): 1; the metals are uniformly distributed in the cationic resin, and The particle size of a single metal is 3 nm to 7 nm. In the present invention, the thickness of the cationic resin is larger than the particle size of a single metal.

The present invention is a negative electrode material for a zinc-based secondary battery, wherein the zinc oxide is composed of zinc oxide with different particle sizes; the mass percentages between the zinc oxides with different particle sizes are:

Zinc oxide with a particle size of 50nm to 199.99nm is 60 to 70%;

20-30% of zinc oxide with a particle size of 200nm-499.99nm;

Zinc oxide with a particle size of 500 nm to 950 nm is 1 to 10%.

The present invention relates to a negative electrode material for a zinc-based secondary battery, wherein the zinc oxide is modified zinc oxide; the modified zinc oxide is zinc oxide that has been soaked in a solution containing a modifier. The modifier-containing solution includes one or more of ammonia water, ammonium acetate solution, ammonium nitrate solution, ammonium sulfate solution, ammonium carbonate solution, and cetylammonium bromide solution.

The invention relates to a negative electrode material for a zinc-based secondary battery, wherein the remaining cationic resin is at least one of fluorine-containing polyurethane resin, fluorine-containing acrylic resin, and polystyrene-divinylbenzenesulfonic acid resin.

The present invention is a negative electrode material for a zinc-based secondary battery, wherein the non-rare earth metal includes at least one of tin, bismuth, indium, silver, gallium, cadmium, lead, and thallium, and the rare earth metal includes lanthanum, cerium, praseodymium, at least one of neodymium.

The preparation method of a zinc-based secondary battery negative electrode material of the present invention comprises the following steps:

step one

Weigh the zinc oxide powder in proportion, add it to the dispersant and stir evenly to obtain a zinc oxide dispersion liquid; then add a modifier to the zinc oxide dispersion liquid, stir and adjust the pH value of the system to 8-11; continue stirring and then filter, The modified zinc oxide powder is obtained, which is denoted as solid A;

Step 2

Add the solid A into the solution containing the cationic resin, keep the temperature of the mixed solution at -10°C to 90°C and ultrasonicate for 60 to 400 min, filter, separate and wash to obtain the zinc oxide powder coated with the cationic resin, which is denoted as solid B;

Step 3

The solid B is added to the mixed metal salt solution, the pH value of the solution is adjusted to 2-6, after stirring, a reducing agent is added to reduce the metal ions in the cation resin to metal elements, and the cations with metal adsorption are obtained by filtration and washing. Resin-coated zinc oxide, denoted as solid C; the mixed metal salt is composed of salts containing non-rare earth metal elements and salts containing rare earth metal elements;

Step 4

The solid C is vacuum-dried and kept at a temperature of 100-220° C. to obtain the negative electrode material for the zinc-based secondary battery.

The present invention is a method for preparing a negative electrode material for a zinc-based secondary battery, wherein the dispersant used in step 1 is one or more of water, methanol, ethanol, acetone, ethylene glycol, and polyethylene glycol 200. The liquid-solid ratio of the agent to zinc oxide is (2～10):1.

The present invention is a method for preparing a negative electrode material for a zinc-based secondary battery. The modifiers used in step 1 include ammonia water, ammonium acetate solution, ammonium nitrate solution, ammonium sulfate solution, ammonium carbonate solution, and cetylammonium bromide. In one or more of the solutions, the mass percentage concentration of the modifier is 2% to 8%. Preferably, the modifier used in the first step of the present invention is selected from at least one of ammonia water, ammonium acetate solution, and ammonium sulfate solution, and the mass percentage concentration of the modifier is 3% to 6%. In the present invention, the mass ratio of zinc oxide to modifier is (10-50):1.

The present invention is a method for preparing a negative electrode material for a zinc-based secondary battery. The cationic resin used in the second step includes perfluorosulfonic acid resin, fluorine-containing polyurethane resin, fluorine-containing acrylic resin, and polystyrene-divinylbenzenesulfonic acid resin. In one, the mass fraction of the cationic resin in the solution containing the cationic resin is 5% to 25%, and the solvent in the solution containing the cationic resin is a mixed solution composed of water and an organic solvent, wherein the organic solvent and water The volume ratio is (1～5): 1; the organic solvent includes at least one of methanol, ethanol, propanol, acetone, ether, ethylene glycol, the solution containing the cationic resin and the modified oxidized The liquid-solid ratio of zinc is (1～10):1. After the cation resin used in the present invention coats zinc oxide, a film with appropriate pore size and porosity can be formed; when it is placed in a solution of mixed metal salts, it is convenient for the immersion of rare earth elements and non-rare earth metal elements; after immersion, the rare earth elements and non-rare earth metal elements are uniformly adsorbed in the cationic resin film; this provides the necessary conditions for the later reduction to obtain metal particles with uniform distribution and particle size of 3-7nm.

The present invention is a method for preparing a negative electrode material for a zinc-based secondary battery. In step 1, zinc oxide powder is weighed in proportion, added to a dispersant and stirred for 10-20 minutes to form a suspension solution of zinc oxide, and ultrasonicated for 30-120 minutes to obtain zinc oxide. Dispersion; add modifying reagent dropwise to the dispersion and stir for 5-10min, add buffer to adjust the pH value of the solution between 8-11, continue stirring for 100-300min, filter to obtain modified zinc oxide powder, Denoted as solid A; the buffers used are ammonia water-ammonium chloride buffer, sodium dihydrogen phosphate-potassium dihydrogen phosphate, borax-boric acid buffer, borax-sodium hydroxide, borax-sodium carbonate buffer, sodium carbonate - One of the sodium bicarbonate buffers. Preferably, in step 1 of the present invention, the buffer solution is selected from ammonia water-ammonium chloride buffer, sodium carbonate-sodium bicarbonate buffer, and borax-sodium carbonate buffer.

The present invention is a method for preparing a negative electrode material for a zinc-based secondary battery. In step 2, solid A is added to a solution containing a cationic resin, and the temperature of the mixed solution is kept at 40°C to 90°C and ultrasonicated for 60 to 400 minutes, and the mixture is filtered and separated. After washing several times, zinc oxide powder coated with cation resin was obtained, which was recorded as solid B. In the present invention, the coating thickness of the cationic resin on the zinc oxide powder is controlled by controlling the concentration and dosage of the resin, the temperature and time of immersion.

Preferably, in the second step of the present invention, the cationic resin is preferably a perfluorosulfonic acid resin and a fluorine-containing polyurethane resin, and the mass percentage concentration of the solution containing the cationic resin is 10% to 20%.

Preferably, in the second step of the present invention, the solvent in the solution containing the cationic resin is a mixed solution composed of water and an organic solvent, wherein the volume ratio of the organic solvent and water is (2-3.8):1.

Preferably, in the second step of the present invention, the liquid-solid ratio of the solution containing the cationic resin to the modified zinc oxide is (3-8):1.

The present invention is a method for preparing a negative electrode material for a zinc-based secondary battery. In step 3, the solid B is added to the mixed metal salt solution, and the pH value of the mixed metal salt solution adjusted with the No. 1 buffer solution is 2-6 , keep the solution temperature at 25 ℃ ~ 50 ℃ and stir for 5h ~ 12h, add a reducing agent dropwise to reduce the metal ions adsorbed in the cation resin to metal element, filter and wash to obtain a cation resin coating with metal adsorption Zinc oxide, denoted as solid C; the No. 1 buffer solution is selected from disodium hydrogen phosphate-citric acid buffer, phthalic acid-hydrochloric acid buffer, citric acid-sodium citrate buffer, acetic acid-sodium acetate buffer , a glycine-hydrochloric acid buffer.

The present invention is a method for preparing a negative electrode material for a zinc-based secondary battery. In step 3, the mixed metal salt is a water-soluble salt; in the mixed metal salt, the anion is selected from the group consisting of chloride ion, nitrate group, sulfate group, and acetate group. at least one; salts containing non-rare earth metal elements are selected from at least one of tin salts, bismuth salts, indium salts, silver salts, gallium salts, cadmium salts, lead salts, and thallium salts; the salts containing rare earth metal elements At least one selected from lanthanum salt, cerium salt, praseodymium salt, and neodymium salt; in the solution of the mixed metal salt; the concentration of the metal element is 0.1 mol/L to 1.0 mol/L; the solution of the mixed metal salt Among them, the molar ratio of non-rare earth metal elements to rare earth elements is (1-5):1. Preferably, in the third step of the present invention, in the mixed metal salt solution, the concentration of the metal element is preferably 0.2 mol/L to 0.7 mol/L. Preferably, the salt containing a non-rare earth metal element is selected from at least one of tin salt, bismuth salt, indium salt and cadmium salt. Preferably, the salt containing rare earth metal element is selected from at least one of lanthanum salt and cerium salt. Preferably, the molar ratio of the non-rare earth metal element to the rare earth element is (2-4):1.

The present invention is a method for preparing a negative electrode material for a zinc-based secondary battery. In step 3, the reducing agent includes at least one of formamide, sodium borohydride, potassium borohydride, lithium aluminum hydride, ascorbic acid, sodium nitrite, and hydrazine hydrate. A sort of.

In a method for preparing a negative electrode material for a zinc-based secondary battery of the present invention, in step 4, during vacuum drying, the air pressure in the furnace is controlled to be 10Pa-100Pa, and the holding time is 120min-400min. Preferably, in step 4, during vacuum drying, the pressure in the furnace is 30Pa-70Pa, and the holding time is 150min-300min.

The advantages of the present invention:

1. The preparation method of a zinc-based secondary battery negative electrode material of the present invention, by changing the distribution of positive charges on the surface of zinc oxide by modifying reagents, can realize that the cationic resin is evenly coated on the surface of zinc oxide, and the addition of cationic resin can be changed. Depending on the concentration of the resin, cladding layers with different thicknesses (thickness between 5nm and 50nm) can be obtained.

2. In the method for preparing a negative electrode material for a zinc-based secondary battery according to the present invention, metal ions are uniformly adsorbed on the cationic resin coating layer through ion exchange and reduction in turn. Compared with the traditional method, the metal ions on the surface of zinc oxide are The distribution is more uniform and the decoration effect of the metal is improved.

3. The method for preparing a negative electrode material for a zinc-based secondary battery according to the present invention, which is kept warm in an inert atmosphere, which can improve the tightness of the bond between the cationic resin and the zinc oxide, so that the cationic resin is not easy to fall off during the charging and discharging process. . 4. The negative electrode material of a zinc-based secondary battery according to the present invention can not only inhibit the diffusion of Zn(OH) ₄ ^2- into the electrolyte, but also reduce the hydrogen evolution corrosion. The cationic resin coated on the surface of ZnO can effectively hinder the diffusion of Zn(OH) ₄ ^2- into the electrolyte and reduce the dissolution of zinc oxide in the electrolyte, thereby effectively inhibiting the deformation of the zinc anode and the growth of dendrites, improving the Cycling stability of zinc-nickel secondary batteries. At the same time, the metal adsorbed in the cation resin can reduce the internal resistance of the battery, the hydrogen evolution overpotential is increased by 20-60 mV, and the coulombic efficiency remains above 70% after 300 cycles of charge and discharge.

5. The negative electrode material of a zinc-based secondary battery of the present invention uses zinc oxide with different particle sizes to reduce the voids inside the electrode and realize the densification of the electrode, which is 10-20% higher than the volume specific capacity of ordinary zinc oxide. .

The specific embodiment of the present invention is as follows:

Example 1

(1) Weigh 5g of zinc oxide powder in proportion and add it to 50ml of deionized water, stir for 10min to form a zinc oxide suspension solution of zinc oxide, and then ultrasonicate for 40min to form a zinc oxide dispersion. To the dispersion liquid, 5 ml of 3% ammonia water was added dropwise and stirred for 5 minutes, sodium carbonate-sodium bicarbonate buffer was added to adjust the pH value of the solution to 8.5, the stirring was continued for 120 minutes, and then the modified zinc oxide powder was obtained by filtration.

(2) The modified zinc oxide powder was added to 30 ml of a mixed solution containing 7 wt % of perfluorosulfonic acid resin and 1 wt % of fluorine-containing acrylic resin, and the temperature of the mixed solution was kept at 50° C. and sonicated for 100 min, and then filtered through Separated to obtain cation resin-coated zinc oxide powder.

(3) measure 50ml of _SnCl with a concentration of 0.4mol/L and a LaCl with a concentration of 0.1mol/L _The methanol mixed solution is put into the beaker, then the zinc oxide powder coated with the cationic resin is added, and dihydrogen phosphate is added dropwise Sodium-citric acid buffer solution, adjust the pH value of the solution to 4, keep the solution temperature at 30 ° C and stir for 6 h, finally add ascorbic acid solution and stir for 0.5 h, filter and wash to obtain Sn and La adsorption cation resin package coated zinc oxide.

(4) then put the obtained product into a vacuum drying oven, control the temperature to be 120 ° C, keep the temperature for 200 min, remove the residual organic solvent, obtain the negative electrode material of a described zinc-based secondary battery, and detect the surface of the zinc oxide. The thickness of the cationic resin layer is about 5nm-7nm, and the mass fraction is 4.1%. Metal tin and lanthanum are uniformly distributed in the coating layer of the cationic resin, and the mass fraction is 1.4%.

(5) The material was made into a 1×1cm, 0.3mm thick zinc electrode, with NiOOH as the counter electrode and 6mol/LKOH aqueous solution as the electrolyte for cyclic testing, after 100, 200, 300 cycles of charge and discharge After cycling, the concentrations of Zn(OH) ₄ ^2- in the electrolyte were measured to be 0.1 mmol/L, 0.2 mmol/L, and 0.5 mmol/L, respectively, and the hydrogen evolution overpotential of the zinc anode increased by 20 mV. After 300 cycles of charging and discharging, the Coulombic efficiency remained at 71%, and the capacity of the battery remained at 73% of the theoretical capacity.

Example 2

(1) Weigh 5g of zinc oxide powder in proportion to 60ml of methanol, stir for 15min to form a suspension solution of zinc oxide, and then ultrasonicate for 60min to form a zinc oxide dispersion. Add 3 ml of 5% ammonium chloride solution dropwise to the dispersion and stir for 5 minutes, add ammonia water-ammonium chloride buffer to adjust the pH of the solution to 9.4, continue stirring for 150 minutes, and then filter to obtain modified zinc oxide powder.

(2) The modified zinc oxide powder was added to 35 ml of a mixed solution containing 10 wt % of perfluorosulfonic acid resin and 1.5 wt % of fluorine-containing polyurethane resin, and the temperature of the mixed solution was kept at 60° C. and sonicated for 150 min, and then passed through Filtration and separation to obtain cation resin-coated zinc oxide powder.

(3) Measure 40ml of the mixed solution of 0.3mol/LBi(NO ₃ ) ₃ and 0.1mol/LCe(NO ₃ ) ₃ ethylene glycol into a beaker, then add zinc oxide powder coated with cation resin, Add citric acid-sodium citrate buffer solution dropwise, adjust the pH of the solution to 3.5, keep the solution temperature at 35°C and stir for 8h, and finally add sodium borohydride solution and stir for 0.5h. The cation resin-coated zinc oxide with Bi and Ce adsorption was obtained by filtering and washing.

(4) then put the obtained product into the vacuum drying oven, control the temperature to be 150 ° C, keep the temperature for 250 min, remove the residual organic solvent, obtain the negative electrode material of a described zinc-based secondary battery, and detect the surface of the zinc oxide. The thickness of the cationic resin layer is about 10nm-12nm, and the mass fraction is 5.8%. Metal bismuth and cerium are uniformly distributed in the coating layer of the cationic resin, and the mass fraction is 2.4%.

(5) The material was made into a zinc electrode sheet with a size of 1 × 1 cm and a thickness of 0.3 mm. NiOOH was used as the counter electrode, and 6 mol/L KOH aqueous solution was used as the electrolyte for cyclic testing. After 100, 200, and 300 cycles of charging During the discharge cycle, the measured concentrations of Zn(OH) ₄ ^2- in the electrolyte were 0.08 mmol/L, 0.18 mmol/L and 0.45 mmol/L, respectively, and the hydrogen evolution overpotential of the zinc anode increased by 30 mV. After 300 cycles of charging and discharging, the Coulombic efficiency was 72%, and the capacity of the battery remained at 74.5% of the theoretical capacity.

Example 3

(1) Weigh 5g of zinc oxide powder and add it to 70ml of ethanol, stir for 20min to form a suspension solution of zinc oxide, then ultrasonically 90min to form zinc oxide dispersion, dropwise add 6ml mass fraction to this dispersion to be 5% ammonium carbonate The solution was stirred continuously, borax-sodium carbonate buffer was added to adjust the pH value of the solution to 10, the stirring was continued for 200 min, and then the modified zinc oxide powder was obtained by filtration.

(2) Add the modified zinc oxide powder to 30 ml of a mixed solution containing 15 wt % of perfluorosulfonic acid resin and 2 wt % of polystyrene-divinylbenzene sulfonic acid resin, and keep the temperature of the mixed solution at 80° C. Ultrasonic for 100 min, and then separated by filtration to obtain cation resin-coated zinc oxide powder.

(3) Measure 50ml of aqueous solution with a concentration of 0.6mol/LIn(NO ₃ ) ₃ and a concentration of 0.2mol/L Pr(NO ₃ ) ₃ into a beaker, then add the zinc oxide powder coated with cation resin, and add dropwise Acetic acid-sodium acetate buffer solution, adjust the pH value of the solution to 6.5, keep the solution temperature at 45 °C and stir for 10 h, finally add the formamide solution and stir for 0.5 h, filter and wash to obtain In and Pr adsorption cation resin

Coated zinc oxide.

(4) then the product obtained is put into a vacuum drying oven, the control temperature is 180 ° C, and the temperature is kept for 300 min, and the residual organic solvent is removed to obtain the negative electrode material for a described zinc-based secondary battery. After detecting the cations on the surface of zinc oxide The thickness of the resin layer is about 15nm-17nm, and the mass fraction is 8.3%. The metal is uniformly distributed in the coating layer of the cationic resin, and the mass fraction is 2.6%.

(5) The material was made into a zinc electrode sheet with a size of 1 × 1 cm and a thickness of 0.3 mm. NiOOH was used as the counter electrode, and 6 mol/L KOH aqueous solution was used as the electrolyte for cyclic testing. After 100, 200, and 300 cycles of charging During the discharge cycle, the measured concentrations of Zn(OH) ₄ ^2- in the electrolyte were 0.06 mmol/L, 0.15 mmol/L, and 0.35 mmol/L, respectively, and the hydrogen evolution overpotential of the zinc anode increased by 40 mV. After 300 cycles of charge-discharge cycles, the Coulombic efficiency remained at 72.5%, and the capacity of the battery remained at 75.5% of the theoretical capacity.

Comparative Example 1

As a comparative test, the surface modification reagent without adding zinc oxide was compared with Example 1.

(1) After testing, if no modification reagent is added, the cationic resin cannot evenly coat the surface of zinc oxide, the thickness is about 0-30nm, the mass fraction is 3.5%, and the metal tin and lanthanum are evenly distributed in the cationic resin. In the coating layer, the mass fraction is 1.1%.

(2) The material was made into a zinc electrode sheet with a size of 1 × 1 cm and a thickness of 0.3 mm. NiOOH was used as the counter electrode, and 6 mol/L KOH aqueous solution was used as the electrolyte for cyclic testing. After 100, 200, and 300 cycles of charging During the discharge cycle, the measured Zn(OH) ₄ ^2- concentrations in the electrolyte were 0.36mmol/L, 0.92mmol/L, and 2.1mmol/L, respectively, and the Coulomb efficiency was maintained at 61%. After 300 cycles of charge and discharge, the battery capacity was maintained at 63% of theoretical capacity.

If the modification reagent is not used, the cationic resin cannot evenly coat the surface of zinc oxide, and some Zn(OH) ₄ ^2- will diffuse into the electrolyte, which reduces the cation resin and prevents Zn(OH) ₄ ² from entering the electrolyte. The effect of diffusion leads to the increase of Zn(OH) ₄ ^2- in the electrolyte and the decrease of the cycle performance of the battery.

Comparative Example 2

As a comparative test, in contrast to Example 2, the incubation was not carried out under an inert atmosphere.

The material was made into a 1×1cm, 0.3mm thick zinc electrode, with NiOOH as the counter electrode and 6mol/L KOH aqueous solution as the electrolyte for cyclic testing, after 100, 200, and 300 cycles of charge-discharge cycles , the measured concentrations of Zn(OH) ₄ ^2- in the electrolyte were 2.5 mmol/L, 5.2 mmol/L and 10.6 mmol/L, respectively. The Coulombic efficiency was 50%, and the capacity of the battery remained at 52% of the theoretical capacity after 300 cycles of charge and discharge.

If the zinc oxide coated with the cationic resin is not kept warm, the tightness of the bond between the cationic resin layer and the zinc oxide will be reduced, which will cause the cationic resin layer to fall off easily, and the Zn(OH) ₄ ² generated during the discharge process will be released to the electrolytic Diffusion in the liquid leads to a sharp increase of Zn(OH) ₄ ² in the electrolyte, and the battery capacity decays rapidly.

Comparative Example 3

As a comparative test, compared with Example 3, metal ion adsorption was not performed.

(1) The thickness of the cationic resin layer on the surface of the zinc oxide has not changed, about 15nm to 17nm, and the mass fraction is 8.5% without metal ion adsorption.

(2) The material was made into a 1×1cm, 0.3mm thick zinc electrode, with NiOOH as the counter electrode and 6mol/L KOH aqueous solution as the electrolyte for cyclic testing, after 100, 200, 300 cycles of charging The discharge cycle was cycled, and the measured Zn(OH) ₄ ^2- concentrations in the electrolyte were 0.07 mmol/L, 0.17 mmol/L, and 0.38 mmol/L, respectively. The Coulombic efficiency remained at 65.5%, and the capacity of the battery remained at 63.5% of the theoretical capacity after 300 cycles of charge and discharge.

If metal ion adsorption is not carried out, the cycle performance of the battery will not be significantly affected, but it will cause severe hydrogen evolution corrosion, resulting in low Coulombic efficiency.

Series Example 4

As a pair of experiments, the effect of different cation resin concentrations was compared.

(1) Add 5g of modified zinc oxide powder to 30ml of mixed solution containing 1wt%, 15wt%, 35wt% of perfluorosulfonic acid resin and 1.5wt% fluorine-containing acrylic resin respectively, keeping the temperature of the mixed solution at 50°C And respectively 100min, and then separated by filtration to obtain zinc oxide powders with different coating amounts of cation resin, which are respectively denoted as S ₁ , S ₂ , and S ₃ .

(2) Measure three 50ml SnCl ₂ with a concentration of 0.4mol/L and a LaCl ₃ methanol mixed solution with a concentration of 0.1 mol/L into a beaker, add S ₁ , S ₂ , S ₃ respectively, and add phosphoric acid dropwise Disodium hydrogen-citric acid buffer solution, adjust the pH value of the solution to 4, keep the solution temperature at 30 ° C and stir for 8 h, finally add ascorbic acid solution and stir for 0.5 h, filter and wash to obtain Sn and La adsorption cations Resin coated zinc oxide. Then put the obtained product into an oven filled with N ₂ protection, control the temperature to be 120 ° C, keep the temperature for 200 min, remove the residual organic solvent, and obtain the zinc oxide with different coating amounts of the cationic resin. The cationic resin layer has different thicknesses: S ₁ is 1-2 nm thick, the mass fraction of cationic resin is 0.5%, and the mass fraction of metal is 0.4%; S2 is about ₁₃ nm-15 nm thick, the mass fraction of cationic resin is 7.5%, and the mass fraction of metal is 7.5%. The mass fraction of S is 2.5%; the thickness of S ₃ is about 55nm-65nm, the mass fraction of cationic resin is 17.5%, and the mass fraction of metal is 4.7%.

(3) S ₁ , S ₂ , and S ₃ were respectively made into 1×1 cm and 0.3 mm thick zinc electrode pieces, NiOOH was used as the counter electrode, and 6 mol/L KOH was used as the electrolyte for the cycle test. After 100, The Zn(OH) ₄ ^2- concentration in the electrolyte, the Coulomb efficiency and the capacity of the battery were measured respectively after 200 and 300 cycles of charge and discharge. The measurement results are shown in Table 1 below.

Table 1 Various indexes of zinc oxide coated with different cation resins as anode material

It can be concluded from the table that when 15wt% perfluorosulfonic acid resin and 1.5wt% fluorine-containing acrylic resin are used to coat zinc oxide, the obtained cationic resin layer is about 13nm-15nm, with good cycle stability; using 1 % perfluorosulfonic acid resin, the coating layer of the cationic resin is too thin, and the effect of inhibiting the diffusion of Zn(OH) ₄ ^2- is not obvious, and some Zn(OH) ₄ ^2- will enter the electrolyte, so that When the concentration of Zn(OH) ₄ ^2- in the electrolyte is relatively high, the cycle performance of the battery will be low; when 35% perfluorosulfonic acid resin is used, the coating layer of the cationic resin is too thick, although the inhibition of Zn(OH) ₄ ^2- The effect of diffusion to the electrolyte is better, but it will also increase the reaction resistance of OH ^- and zinc oxide, the electrode will be passivated, and the capacity will decay rapidly.

Claims (9)

1. A zinc-based secondary battery negative electrode material is characterized in that; comprises the following components in percentage by weight:

85-95% of zinc oxide, wherein the particle size of the zinc oxide is 50-950 nm;

2% -12% of cationic resin; in the cation resin, perfluorinated sulfonic acid resin accounts for 75-95% of the cation resin, and the rest of the cation resin accounts for 5-25%; the cationic resin is uniformly coated on the surface of the zinc oxide, the thickness is between 5nm and 50nm,

1-3% of metal, wherein the metal comprises non-rare earth metal and rare earth metal, and the mass ratio of the non-rare earth metal to the rare earth metal is (1-5): 1; the metal is uniformly distributed in the cationic resin, and the particle size of a single metal is 3 nm-7 nm.

2. A zinc-based secondary battery negative electrode material according to claim 1, characterized in that: the rest cation resin is at least one of fluorine-containing polyurethane resin, fluorine-containing acrylic resin and polystyrene-divinylbenzene sulfonic acid resin.

3. A zinc-based secondary battery negative electrode material according to claim 1, characterized in that: the non-rare earth metal comprises at least one of tin, bismuth, indium, silver, gallium, cadmium, lead and thallium, and the rare earth metal comprises at least one of lanthanum, cerium, praseodymium and neodymium.

4. A method for preparing the negative electrode material for the zinc-based secondary battery as defined in any one of claims 1 to 3, characterized by comprising the steps of:

step one

Weighing zinc oxide powder according to a proportion, adding the zinc oxide powder into a dispersing agent, and uniformly stirring to obtain a zinc oxide dispersion liquid; then adding a modifier into the zinc oxide dispersion liquid, stirring and adjusting the pH value of the system to 8-11; continuously stirring and filtering to obtain modified zinc oxide powder marked as solid A;

step two

Adding the solid A into a solution containing cationic resin, keeping the temperature of the mixed solution at-10-90 ℃, carrying out ultrasonic treatment for 60-400 min, filtering, separating and washing to obtain cationic resin coated zinc oxide powder, and marking as solid B;

step three

Adding the solid B into a solution mixed with metal salt, adjusting the pH value of the solution to 2-6, stirring, adding a reducing agent, reducing metal ions absorbed in the cationic resin into a metal simple substance, filtering and washing to obtain cationic resin coated zinc oxide with metal absorption, and marking as solid C; the mixed metal salt is composed of a non-rare earth metal element-containing salt and a rare earth metal element-containing salt;

step four

And (3) carrying out vacuum drying on the solid C, and carrying out heat preservation at the temperature of 100-220 ℃ to obtain the zinc-based secondary battery negative electrode material.

5. The method of claim 4, wherein the method comprises the steps of: the dispersant used in the first step is one or more of water, methanol, ethanol, acetone, glycol and polyethylene glycol 200, and the liquid-solid ratio of the dispersant to zinc oxide is (2-10): 1;

the modifier used in the first step comprises one or more of ammonia water, an ammonium acetate solution, an ammonium nitrate solution, an ammonium sulfate solution, an ammonium carbonate solution and a hexadecyl ammonium bromide solution, and the mass percentage concentration of the modifier is 2-8%.

6. The method of claim 4, wherein the method comprises the steps of: the cationic resin used in the second step comprises one of perfluorinated sulfonic acid resin, fluorine-containing polyurethane resin, fluorine-containing acrylic resin and polystyrene-divinylbenzene sulfonic acid resin, the mass fraction of the cationic resin in the solution containing the cationic resin is 5-25%, the solvent in the solution containing the cationic resin is a mixed solution consisting of water and an organic solvent, and the volume ratio of the organic solvent to the water is (1-5): 1; the organic solvent comprises at least one of methanol, ethanol, propanol, acetone, diethyl ether and glycol, and the liquid-solid ratio of the solution containing the cationic resin to the modified zinc oxide is (1-10): 1.

7. The method of claim 4, wherein the method comprises the steps of:

in the first step, zinc oxide powder is weighed according to a proportion, added into a dispersing agent and stirred for 10-20 min to form a zinc oxide suspension, and the suspension is subjected to ultrasonic treatment for 30-120 min to obtain a zinc oxide dispersion; dropwise adding a modifying reagent into the dispersion liquid, stirring for 5-10 min, adding a buffer solution to adjust the pH value of the solution to 8-11, continuously stirring for 100-300 min, and filtering to obtain modified zinc oxide powder, wherein the modified zinc oxide powder is marked as solid A; the buffer solution is one of ammonia water-ammonium chloride buffer solution, sodium dihydrogen phosphate-potassium dihydrogen phosphate, borax-boric acid buffer solution, borax-sodium hydroxide, borax-sodium carbonate buffer solution and sodium carbonate-sodium bicarbonate buffer solution;

adding the solid A into a solution containing cationic resin, keeping the temperature of the mixed solution at 40-90 ℃, carrying out ultrasonic treatment for 60-400 min, filtering, separating and washing for several times to obtain cationic resin coated zinc oxide powder, and marking as solid B;

adding the solid B into the solution of the mixed metal salt, adjusting the pH value of the solution of the mixed metal salt to 2-6 by using a No. 1 buffer solution, stirring for 5-12 h under the condition of keeping the temperature of the solution at 25-50 ℃, dropwise adding a reducing agent to reduce metal ions absorbed in the cationic resin into a metal simple substance, filtering and washing to obtain cationic resin coated zinc oxide with metal absorption, and marking as solid C; the No. 1 buffer solution is selected from one of disodium hydrogen phosphate-citric acid buffer solution, phthalic acid-hydrochloric acid buffer solution, citric acid-sodium citrate buffer solution, acetic acid-sodium acetate buffer solution and glycine-hydrochloric acid buffer solution.

8. The method of claim 4, wherein the method comprises the steps of:

in the third step, the mixed metal salt is water-soluble salt; in the mixed metal salt, the anion is selected from at least one of chloride, nitrate, sulfate and acetate;

the salt containing non-rare earth metal elements is at least one of tin salt, bismuth salt, indium salt, silver salt, gallium salt, cadmium salt, lead salt and thallium salt;

the salt containing rare earth metal elements is selected from at least one of lanthanum salt, cerium salt, praseodymium salt and neodymium salt;

a solution of the mixed metal salt; the concentration of the metal ions is 0.1 mol/L-1.0 mol/L; in the solution of the mixed metal salt, the molar ratio of non-rare earth metal elements to rare earth elements is (1-5): 1;

in the third step, the reducing agent comprises at least one of formamide, sodium borohydride, potassium borohydride, lithium aluminum hydride, ascorbic acid, sodium nitrite and hydrazine hydrate.

9. The method of claim 4, wherein the method comprises the steps of: in the fourth step, during vacuum drying, the air pressure in the furnace is controlled to be 10Pa to 100Pa, and the heat preservation time is controlled to be 120min to 400 min.