WO2017190584A1 - Secondary battery of zinc-lithium-manganese water system and preparation method therefor - Google Patents

Abstract

Disclosed are a secondary battery of a zinc-lithium-manganese water system and a preparation method therefor, wherein same fall within the battery manufacturing field. The secondary battery of a zinc-lithium-manganese water system comprises a positive electrode, a negative electrode, an electrolyte and a separator between the positive electrode and the negative electrode. An active material of the positive electrode is a manganese lithium oxide material; an active material of the negative electrode is zinc or a zinc compound; and the electrolyte is a neutral aqueous solution containing a lithium salt and a zinc salt. The secondary battery is characterized in: the separator being an ionic polymer membrane composed of acrylate polymer colloidal particles with sulfonate groups on the surface. The secondary battery of a zinc-lithium-manganese water system has a stable performance and a long cycle life, can be industrially produced, and has a uniform electric field inside the battery. The secondary battery of a zinc-lithium-manganese water system solves the problem that the dendrite growth and the side reactions related thereto result in non-practicability of a battery, such that the zinc-lithium-manganese battery has the characteristics of a high energy density, long cycle life, high safety and low cost; and the scale industrialization of a secondary battery of a zinc-lithium-manganese water system can be realized, and the development of same in fields such as electric vehicles and power energy storage can be promoted.

Description

Zinc lithium manganese water system secondary battery and preparation method thereof Technical field

The invention relates to a zinc lithium manganese water system secondary battery and a preparation method thereof, and belongs to the field of electrochemistry, in particular to the field of battery manufacturing.

Background technique

With the increasingly important influence of energy and environment on human beings, clean energy storage technology has developed rapidly, especially the rapid development of electric vehicles and energy storage power stations, which has led to rapid progress in rechargeable battery technology, and rechargeable batteries have emerged one after another. Such as lithium ion batteries, lead acid batteries, nickel hydrogen batteries, fuel cells, metal air batteries, zinc manganese batteries, lithium sulfur batteries, sodium sulfur batteries and so on. However, due to the comprehensive requirements of technical requirements, maturity and cost of the application field, lithium-ion batteries are mainly used in electric vehicles, and most of the energy storage power stations use lead-acid batteries. Lithium-ion batteries have the danger of poor safety performance and even explosion due to the use of organic electrolytes. At the same time, high production requirements result in high product cost. Lead-acid batteries, although high in safety and low in price, have great environmental impact due to their use of lead materials. Hazard of pollution. Therefore, it is necessary to develop a battery with high safety, low cost and long cycle life.

Zinc-based batteries are an important branch of chemical batteries. Zinc is abundant in storage, cheap in price, high in specific capacity, and the production and use of zinc-based batteries does not pollute the environment. It is a true green battery anode material.

Chinese patent application CN105070901A (publication number) and CN204793097 (authorization number) disclose a microporous separator such as a lithium-rich manganese oxide cathode material, a neutral brine-based electrolyte, a poly(oxygen, chlorine) olefin or a nylon, and a zinc anode. The secondary battery (zinc lithium manganese secondary battery), which is expected to ensure high energy density while maintaining safety and low cost. According to the above-mentioned zinc-manganese-based secondary battery patent applicant, Zhang Jiagang, Zhidian Fanghua Storage Research Institute, the chief scientist Yang Yusheng, at the 7th member representative conference of China Battery Industry Association, from the current basic experiment Data calculation The battery system can achieve 60-80Wh/kg, which is about 1.5 times that of lead-acid batteries, and the energy density of the battery system is optimized with the total proportion of battery active materials in the battery (as shown in the following table). There is a large space for improvement, and it has broad application prospects in terms of power and energy storage.

Table 1

Serial number	Fill ratio %	Specific energy Wh/kg
1	17.4	80
2	21.9	100
3	26.3	120
4	35.0	160

Note: Fill rate refers to the weight percentage of active material in the battery in the battery.

At present, although the battery system has proved the theoretical feasibility of the battery system from the basic research, in the actual battery production, there are still problems such as dendrite growth of the zinc electrode in the electrochemical process and passivation of the metal negative electrode, resulting in the problem. The secondary battery of the system has defects such as short cycle life, serious self-discharge, and rapid decline in cycle capacity.

For the secondary battery of the existing zinc negative electrode, there are many ways for those skilled in the art to eliminate or improve the above defects, such as adding a zinc crystal inhibitor to the negative electrode material, replacing the zinc as a negative electrode material with a zinc phosphate salt, or improving the performance of the separator. Wait.

Patent CN1412879A discloses a zinc oxide control agent for a secondary battery using zinc as a negative electrode, a zinc crystal inhibitor composed of dichromate, molybdate or the like, which inhibits zinc dendrite formation and growth during the process, and achieves some effects. However, the introduction of a strong oxidation group such as dichromic acid causes corrosion of other materials, degrading battery performance or even failing to work properly.

Patent CN105140498A discloses that zinc phosphate is used instead of zinc as a negative electrode material, which solves the problem that dendrite may be formed. However, due to problems such as conductivity and ion exchange efficiency of the negative electrode, it is not possible to meet the application requirements as a negative electrode material. .

As the heart part of the secondary zinc battery, the separator isolates the positive and negative electrodes, so that the electrons in the battery cannot pass freely, allowing the ions in the electrolyte to pass freely between the positive and negative electrodes. The ion conductivity of the battery separator is directly related to the overall performance of the battery. Therefore, the quality and performance of the zinc electrode secondary battery separator will directly affect the high performance and popularization of the zinc electrode secondary battery.

U.S. Patent No. 4,652, 504 discloses a membrane having a dispersed channel and a plurality of raised particles. It has been reported that this membrane can disperse the zinc ion stream by the convex particles and the dispersion channel to delay the penetration of the zinc dendrite into the membrane, thereby prolonging the service life of the membrane. The disadvantage of such a film is that the manufacturing process is complicated, the precision of the process is high, and it is difficult to mass-produce.

U.S. Patent 4,279,978 describes a membrane comprising a polyamide, a hydrophilic polymer and a filler material. It has been reported that the filler material in this membrane can react with zinc metal to achieve the purpose of eliminating zinc dendrite, thereby prolonging the service life of the membrane. The filler used in the patent is a metal oxide, and the metal oxide is used in the separator. Falling off the diaphragm is a fatal shortcoming of this diaphragm.

U.S. Patent 4,192,908 describes the application of a composite film having a lower hydrogen potential material than a zinc oxide electrode on the surface of a microporous membrane. It has been reported that the low hydrogen potential material in the coating of the separator can react with the metal zinc to eliminate the dendrites, thereby prolonging the service life of the separator. Such a separator needs to be sandwiched between two layers of microporous polyolefin membranes during use, and hydrogen gas is generated during the electrochemical reaction, which is disadvantageous for the development of sealed zinc electrode secondary batteries.

Therefore, there is an urgent need in the art for an effective retardation or prevention of dendrite growth, a simple preparation process, stable performance during use, and favorable for forming a separator for a zinc-lithium manganese electrode secondary battery.

Summary of the invention

The object of the present invention is to provide a secondary battery of zinc lithium manganese water system which has stable performance, long cycle life and can be industrially produced.

The technical solution of the invention:

a secondary battery of a zinc-lithium-manganese water system, comprising a positive electrode, a negative electrode, an electrolyte and a separator between the negative electrode and the positive electrode, the positive active material being a lithium manganese oxide material, the negative active material being a zinc or zinc compound, and the electrolysis The liquid contains a neutral aqueous solution of a lithium salt and a zinc salt; and the separator is an ionic polymer film composed of acrylate-based polymer colloidal particles having a sulfonate group on the surface.

The theoretically feasible secondary battery of zinc-lithium-manganese water system has been difficult to be industrialized in the research stage. The problems of poor cycle life and self-discharge are mainly the formation growth and dendrite growth of the battery during the charge-discharge cycle. Caused by side effects of other component components.

The inventors of the present invention have found that dendrite formation and growth are caused by the non-uniformity of the electric field in which it is located, and in the zinc-manganese-manganese battery of the prior research, the electric field non-uniformity is mainly caused by the porous film currently used. of. The inventors of the present invention have studied together with the academician Yang Yusheng, such as the inventor of the patent application CN105070901A, and the porous film of polyethylene, polypropylene, etc., which the researcher Yang Yusheng has studied, has poor cycle performance.

It can be seen from the analysis that in the electric field inside the battery, the current forms a loop by ion conduction. However, the microporous membrane has a porosity of only 30% to 70% in the microstructure and 70 to 30% of a region in which ions cannot be conducted. The corresponding electrode in this part needs to balance ion conduction and electron conduction (zinc deposition) during charge and discharge. When the ion conduction current in this region is greater than that during electrodeposition, the electric field in the negative electrode region corresponding to the porous region and the non-porous region of the diaphragm will appear. Equilibrium, which in turn forms dendrites or even dead zinc deposits.

Based on the above findings, the inventors of the present invention prepared a zinc-lithium manganese water system secondary battery by using a non-porous dense ionic polymer membrane having a colloidal particle structure, thereby ensuring that the ionic polymer membrane material and the electrolyte are better. The compatibility, which not only ensures the basic performance of the battery, but also ensures the internal electric field of the battery is homogenized and inhibits the zinc dendrite.

The ionic polymer film material used in the present invention is an ionic polymer film composed of acrylate-based polymer colloidal particles having a sulfonate group on the surface. Specifically, in the polymerization process, a reactive sulfonate surfactant is used as an emulsifier to synthesize an acrylate polymer colloidal emulsion having a sulfonate group on the surface. The emulsion is cast into a film to form a polymer film that maintains the structure of the colloidal particles.

Since the polymer film forms a penetrating ion conduction path between the colloidal particles and the colloidal particles after absorbing the electrolyte, and the electrolyte solution or solvent is absorbed, the ionic polymer film material can maintain the colloidal particle structure and the colloidal particle sphere structure is densely packed. The tortuosity of the ion conduction path is increased, and the electronic insulation performance of the polyanion electrolyte membrane is improved.

As a preferred embodiment of the present invention, the sulfonate group is a vinyl sulfonate, an allyl sulfonate, a methallyl sulfonate, an allyloxy hydroxypropyl sulfonate, a methyl group. One or more of hydroxypropyl sulfonate acrylate, 2-acrylamido-2-methylpropane sulfonate, and styrene sulfonate.

The particle diameter range of the colloidal particles in the separator is preferably from 10 nm to 1.0 μm, and more preferably from 20 to 200 nm.

The ionic polymer film may have a thickness of 10 to 100 μm.

As a specific embodiment of the present invention, the acrylate-based polymer colloidal particles are polymethyl acrylate colloidal particles, which are obtained by emulsion polymerization of a methyl acrylate monomer.

As another embodiment of the present invention, the acrylate-based polymer colloidal particles may further be formed by emulsion polymerization of a methyl acrylate monomer and a second monomer, and the second monomer CH ₂ =CR ₁ R Any one or more of ₂ in combination; wherein R ₁ = -H or -CH ₃ ; R ₂ = -C ₆ H ₅ , -OCOCH ₃ , -CN, -C ₄ H ₆ ON, -C ₂ H ₃ CO ₃ , ─COO(CH ₂ ) _n CH ₃ , n is 0-14.

In still another embodiment of the present invention, the acrylate-based polymer colloidal particles are composed of acrylate-based polymer colloidal particles having a sulfonate group on the surface and an inorganic ceramic filler.

The ceramic filler is a metal oxide and a metal composite oxide, and has the general formula NzMxOy, wherein N is an alkali metal or an alkaline earth metal element, M is a metal element or a transition metal, Z is 0-5, and x is 1-6. , y is 1 to 15.

The ceramic filler is preferably one or any combination of Al ₂ O ₃ , SiO ₂ , Li ₄ Ti ₅ O ₁₂ , more preferably SiO ₂ or Al ₂ O ₃ .

The ceramic filler preferably has an average particle diameter of 10 nm to 5.0 μm, preferably 20 nm to 0.5 μm; and most preferably an average particle diameter of 20 nm to 200 nm Al ₂ O ₃ .

Advantageous effects of the present invention

The present invention provides a zinc-lithium manganese secondary battery comprising a water-electrolyte-containing ion-containing polymer separator having a long cycle life. The internal electric field of the battery is uniform, which solves the problem that the dendrite growth and the associated side reaction cause the battery to be unutilized, so that the zinc lithium manganese battery has the characteristics of high energy density, long cycle life, high safety and low cost, and can perform zinc lithium. The industrialization of the scale of the secondary battery of the manganese water system can promote the development of electric vehicles and power storage.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a comparison of cycle life tests of Comparative Examples 1 to 3 and the ionic polymer film of Example 1 of the present invention.

The abscissa is the battery cycle test (unit: time), and the ordinate is the unit capacity of the positive active material in the battery (unit: mAh/g). Test conditions: voltage test range 1V--2.02V, charge/discharge current is 0.1 C/0.1C, temperature: 25 ± 3 °C. The curves marked with numbers 1-4 in the figure represent the following meanings:

1. Single-layer polypropylene microporous membrane (40μm) battery cycle curve;

2, double-layer polypropylene microporous membrane (80μm) battery cycle curve;

3, three-layer polypropylene microporous membrane (120μm) battery cycle curve;

4. The cycle curve of a 40 μm ionic polymer film battery was synthesized in Example 1 of the present invention.

Figure 2 is a graph showing the cycle life test of a microporous film of Comparative Examples 1 to 10.

The abscissa is the battery cycle test (unit: time), and the ordinate is the unit capacity of the positive active material in the battery (unit: mAh/g). Test conditions: voltage test range 1V--2.02V, charge/discharge current is 0.1 C/0.1C, temperature: 25 ± 3 °C. The curves marked by numbers 5 to 11 in the figure represent the following meanings:

1. Same as above, the cycle curve of single-layer polypropylene microporous membrane (40μm) battery;

2, the same as above, double-layer polypropylene microporous membrane (80μm) battery cycle curve;

3. Same as above, three-layer polypropylene microporous membrane (120μm) battery cycle curve;

5. Single-layer polyvinyl chloride microporous membrane (40μm) battery cycle curve;

6. Single-layer polyoxyethylene microporous membrane (40μm) battery cycle curve;

7. Single-layer nylon microporous membrane (40μm) battery cycle curve;

8. Single-layer glass fiber membrane (60μm) battery cycle curve;

9. Single-layer asbestos paper (50μm) battery cycle curve;

10, polyethylene microporous membrane (20μm) + nylon composite membrane (40μm) battery cycle curve;

11. Polyethylene microporous membrane (20 μm) + non-woven fabric (20 μm) battery cycle curve.

Figure 3 is a graph showing the cycle life of the ionic polymer film in Examples 1 to 4 of the present invention.

The abscissa is the battery cycle test (unit: time), and the ordinate is the unit capacity of the positive active material in the battery (unit: mAh/g). Test conditions: voltage test range 1V--2.02V, charge/discharge current is 0.1 C/0.1C, temperature: 25 ± 3 °C. The curves marked by numbers 4, 12 to 14 in the figure represent the following meanings:

4. The cycle curve of the synthesized ionic polymer film (40 μm) in the first embodiment of the present invention;

12. The cycle curve of the synthetic ionic polymer film (40 μm) battery of Example 2 of the present invention;

13. The cycle curve of the synthetic ionic polymer film (40 μm) battery of Example 3 of the present invention;

14. Inventive Example 4 Synthesis of an ionic polymer film (40 μm) battery cycle curve.

detailed description

The zinc-lithium manganese water system secondary battery of the present invention comprises a positive electrode, a negative electrode, an electrolyte and a separator between the negative electrode and the positive electrode, the positive active material is a lithium manganese oxide material, and the negative active material is a zinc or zinc compound, The electrolyte solution contains a neutral aqueous solution of a lithium salt and a zinc salt; and the separator is an ionic polymer film composed of acrylate-based polymer colloidal particles having a sulfonate group on the surface.

The problems of poor cycle life and poor self-discharge of zinc-based secondary batteries are mainly caused by the formation and growth of dendrites during the charge-discharge cycle and the side effects of dendrite growth on other component components.

The inventors of the present invention have found that dendrite formation and growth are caused by the non-uniformity of the electric field in which it is located, and in the zinc-manganese-manganese battery of the prior research, the electric field non-uniformity is mainly caused by the porous film currently used. of. For example, Academician Yang Yusheng used porous membranes such as polyethylene and polypropylene in their research.

In the electric field inside the battery, current is formed by ion conduction to form a loop. However, the microporous membrane has a porosity of only 30% to 70% in the microstructure and 70 to 30% of a region in which ions cannot be conducted. And this part corresponds to the electricity It is necessary to balance ion conduction and electron conduction (zinc deposition) during charge and discharge. When the ion conduction current in this region is smaller than that in the electrodeposition, the electric field imbalance occurs in the negative electrode region corresponding to the porous region and the non-porous region of the separator, thereby forming dendrites or even dead zinc deposits.

The inventors of the present invention prepared a zinc-lithium manganese water system secondary battery by using a non-porous dense ionic polymer membrane having a colloidal particle structure, thereby ensuring good compatibility of the ionic polymer membrane material with the electrolyte. In addition, it not only ensures the basic performance of the battery, but also ensures the electric field homogenization of the battery and inhibits the zinc dendrite.

The ionic polymer film material used in the present invention is an ionic polymer film composed of acrylate-based polymer colloidal particles having a sulfonate group on the surface. Specifically, in the polymerization process, a reactive sulfonate surfactant is used as an emulsifier to synthesize an acrylate polymer colloidal emulsion having a sulfonate group on the surface. The emulsion is cast into a film to form a polymer film that maintains the structure of the colloidal particles.

Since the polymer film forms a penetrating ion conduction path between the colloidal particles and the colloidal particles after absorbing the electrolyte, and the electrolyte solution or solvent is absorbed, the ionic polymer film material can maintain the colloidal particle structure and the colloidal particle sphere structure is densely packed. The tortuosity of the ion conduction path is increased, and the electronic insulation performance of the polyanion electrolyte membrane is improved.

As a preferred embodiment of the present invention, after forming a film of a polymer colloidal emulsion having a sulfonate group on the surface, the average particle diameter of the colloidal particles is observed by scanning electron microscopy to be in the range of 10 nm to 1.0 μm, preferably 20 to 200 nm. The ionic polymer film has a thickness of 10 to 100 μm.

The reactive sulfonate surfactant is vinyl sulfonate, allyl sulfonate, methallyl sulfonate, allyloxy hydroxypropyl sulfonate, hydroxypropyl methacrylate One or more of a sulfonate, 2-acrylamido-2-methylpropanesulfonate, and a styrenesulfonate are used in combination; wherein the cation is a lithium ion, a sodium ion or a potassium ion.

The ionic polymer film of the present invention is prepared by the following method:

a. Synthesis of polymer colloidal emulsion: adding colloidal protective agent and distilled water to the reaction flask, heating and stirring until completely dissolved, adding reactive sulfonate surfactant, polymerization monomer and crosslinker (in any order) Uniform, then adding initiator polymerization to obtain a polymer colloidal emulsion;

b. Polymer colloidal emulsion, coated on a plastic base tape, peeled off after drying.

The polymerization monomer is a combination of a methyl acrylate monomer or a methyl acrylate monomer and a second monomer.

The second monomer is for adjusting the heat shrinkability of the film material, the liquid absorbing ability of the electrolyte, and the flexibility of the polymer.

The second monomer is CH ₂ =CR ₁ R ₂ ; wherein R ₁ =-H or -CH ₃ ; R ₂ =-C ₆ H ₅ , -OCOCH ₃ , -CN, -C ₄ H ₆ ON - C ₂ H ₃ CO ₃ , ─COO(CH ₂ ) _n CH ₃ , n is 0-14.

The second monomer is used in combination of any one or more of the above monomers in an amount of from 2 to 10% by weight based on the total weight of the polymerized monomers. As a preferred embodiment of the present invention, the starting materials for the polymerization: the reactive sulfonate surfactant, the polymerization monomer and the crosslinking agent are added in one portion, dropwise or stepwise.

Further preferably, 1/5 to 1/3 of the raw material (by weight) of the polymerization reaction is first added, and after the polymerization reaction for a certain period of time, the raw materials of the remaining polymerization reaction are added dropwise or stepwise.

The polymerization reaction time is preferably completed to complete the polymerization reaction. Usually 4-36 hours, preferably 8-24 hours.

The polymerization temperature is 50 to 90 ° C, preferably 55 to 70 ° C.

The colloidal protective agent of the present invention is one of polyvinyl alcohol, polyethylene oxide, polyacrylate, and polyvinylpyrrolidone, and is preferably polyvinyl alcohol. The amount of the colloidal protective agent is from 5 to 30%, preferably from 10 to 25%, based on the total mass of the polymerization monomer.

The initiator is a commonly used initiator for polymerization, such as ammonium persulfate, potassium persulfate, hydrogen peroxide, azobisisobutyl hydrazine and the like, and the amount thereof is 0.1 to 2.0% of the total weight of the polymerization monomer. It is preferably 0.5 to 1.0%.

The ionic polymer separator may also be composed of acrylate-based polymer colloidal particles having a sulfonate group on the surface and an inorganic ceramic powder.

The ceramic filler is a metal oxide and a metal composite oxide, and has the general formula NzMxOy, wherein N is an alkali metal or an alkaline earth metal element, M is a metal element or a transition metal, Z is 0-5, and x is 1-6. , y is 1 to 15. For example, one or any combination of Al ₂ O ₃ , SiO ₂ , Li ₄ Ti ₅ O ₁₂ is preferably SiO ₂ and Al ₂ O ₃ . The inorganic ceramic powder powder is used in an amount of 5 to 30%, preferably 10 to 20%, based on the total mass of the polymer colloidal emulsion solids.

The ceramic filler has an average particle diameter (D50) of preferably 10 nm to 5.0 μm, more preferably 20 nm to 0.5 μm, and a preferred ceramic filler is Al ₂ O ₃ and an average particle diameter (D50) of 20 nm to 200 nm.

The ionic polymer/ceramic filler composite membrane is prepared by the following method:

a. Synthesis of polymer colloidal emulsion: adding colloidal protective agent and distilled water to the reaction flask, heating and stirring until completely dissolved, adding reactive sulfonate surfactant, polymerization monomer and crosslinker (in any order) Uniform, then adding initiator polymerization to obtain a polymer colloidal emulsion;

b. Preparation of ceramic filler slurry: ceramic filler and plasticizer are added in distilled water, stirred and dispersed uniformly, and then further milled and dispersed by agitating ball mill.

c. Add the ceramic filler slurry prepared in step a to the ceramic filler slurry prepared in step b, stir evenly, coat on a plastic base tape, and peel off after drying.

Wherein, the plasticizer in the step b is one of triethyl phosphate, tributyl phosphate and propylene carbonate, and preferably triethyl phosphate. The plasticizer is used in an amount of from 75 to 150%, preferably from 90 to 100%, based on the total mass of the polymeric colloidal emulsion solids.

The electrolyte consists of a lithium salt, a zinc salt, a cationic salt type additive and a solvent, and the lithium salt, the zinc salt and the cationic salt type additive are dissolved in the solvent, wherein The concentration of the lithium salt is 0.2 to 12 mol/liter, the concentration of the zinc salt is 0.2 to 6 mol/liter, and the concentration of the cationic salt additive is 0.01 to 20% of the concentration of the lithium salt. The cationic salt type additive is selected from the group consisting of magnesium salt, calcium salt, barium salt, sodium salt, potassium salt, barium salt, barium salt, manganese salt, cobalt salt, nickel salt, copper salt, aluminum salt, gallium salt and One or more of the indium salts; the solvent is one or more of water, N-methylformamide, N,N-dimethylformamide, and acetonitrile; the lithium salt is sulfuric acid One or more of lithium, lithium chloride, lithium nitrate, lithium acetate, lithium perchlorate, lithium tetrafluoroborate, lithium borate; the zinc salt is zinc sulfate, zinc chloride, zinc fluoride, nitric acid One or more of zinc, zinc acetate, zinc perchlorate, zinc tetrafluoroborate, and Zn(CF ₃ SO ₃ ) ₂ .

The positive electrode is a lithium manganese oxide material having a specific capacity of more than 400 mAh/g.

The current collector of the positive electrode is a titanium mesh, a carbon coated titanium mesh, a stainless steel mesh, a carbon coated stainless steel mesh, a conductive plastic stainless steel mesh, a conductive plastic titanium mesh, a punched stainless steel foil or a cut titanium mesh.

The active material of the negative electrode is a zinc alloy selected from the group consisting of zinc foil, zinc ribbon, zinc powder, and ruthenium, indium, lead, cadmium, ruthenium, osmium, and the like added, for example, in several additives.

The current collector of the negative electrode is a stainless steel mesh, a punched stainless steel foil, a tinned stainless steel mesh, a tin plated punched stainless steel foil, a tin-zinc alloy stainless steel mesh, a tin-zinc alloy punched stainless steel foil, a tin-zinc alloy iron mesh. Or tin-plated zinc alloy iron foil.

The battery preparation process may be fabricated by a laminated or wound lithium battery process, or may be fabricated by using a lead-acid or nickel-hydrogen battery.

The following are specific examples:

Example 1 Preparation of Ionic Polymer Membrane

In a four-port reaction vessel with condensed water, 1000 g of distilled water and 122 g of polyvinyl alcohol were added, and then the temperature was raised to 92 ° C, stirred and dissolved. After the polyvinyl alcohol was completely dissolved, it was cooled to 60 ° C, and 385 g of methyl acrylate (MA) was added. The mixture, 29 g of sodium allyl sulfonate (SAS) and 210 g of acrylonitrile (AN) were stirred for 1 h, and 2 g of ammonium persulfate was added to initiate polymerization. After the reaction was carried out for 3 hours, 100 g (MA) was further added, and 1.5 g of persulfuric acid was added. The ammonium was further polymerized for 8 hours to give a white polymer colloidal emulsion.

A 75% by weight ceramic filler slurry was added dropwise to the prepared polymer colloidal emulsion, and the mixture was uniformly stirred at a slow speed, then filtered through a 200-mesh filter cloth, coated on a PET base tape, and dried to obtain a thickness of 40 μm. Ionic polymer membrane.

Example 2 Preparation of Ionic Polymer Membrane

In a four-port reaction vessel with condensed water, 1000 g of distilled water and 110 g of polyethylene oxide were added, and then the temperature was raised to 62 ° C, stirred and dissolved. After the polyoxyethylene alcohol was completely dissolved, it was cooled to 60 ° C, and 385 g of methyl acrylate (MA) was added. The monomer, 29 g of sodium allyloxyhydroxypropyl sulfonate (AHPS) and 210 g of acrylonitrile (AN) were stirred for 1 h, and 2 g of ammonium persulfate was added to initiate polymerization. After the reaction was carried out for 3 hours, 100 g (MA) was further added, and the solution was supplemented. Add 1.5g ammonium persulfate to continue polymerization After 8 hours, a white polymer colloidal emulsion was obtained.

The prepared polymer colloidal emulsion was coated on a PET base tape, and after drying the moisture, an ionic polymer film having a thickness of 40 μm was obtained.

Example 3 Preparation of Ionic Polymer Membrane

In a four-port reaction vessel with condensed water, 1000 g of distilled water and 122 g of polyvinyl alcohol were added, and then the temperature was raised to 92 ° C, stirred and dissolved. After the polyvinyl alcohol was completely dissolved, it was cooled to 60 ° C, and 500 g of ethyl acrylate (EA) was added. , 29 g of sodium allyl sulfonate (SAS) and 210 g of acrylonitrile (AN) were stirred for 1 h, and 2 g of ammonium persulfate was added to initiate polymerization. After the reaction was carried out for 6 hours, 100 g (MA) was further added, and 1.5 g of persulfuric acid was added. The ammonium was further polymerized for 10 hours to give a white polymer colloidal emulsion.

A 200% by weight ceramic filler slurry was added dropwise to the prepared polymer colloidal emulsion, and the mixture was uniformly stirred at a slow speed, then filtered through a 200-mesh filter cloth, coated on a PET base tape, and dried to obtain a thickness of 40 μm. Ionic polymer membrane.

Example 4 Preparation of Ionic Polymer Membrane

In a four-port reaction vessel with condensed water, 1000 g of distilled water and 122 g of polyvinyl alcohol were added, and then the temperature was raised to 92 ° C, stirred and dissolved. After the polyvinyl alcohol was completely dissolved, it was cooled to 60 ° C, and 500 g of methyl acrylate (MA) was added. , 29 g of sodium allyl sulfonate (SAS) and 210 g of acrylonitrile (AN) were stirred for 1 h, and 2 g of ammonium persulfate was added to initiate polymerization. After the reaction was carried out for 6 hours, 100 g (MA) was further added, and 1.5 g of persulfuric acid was added. The ammonium was further polymerized for 10 hours to give a white polymer colloidal emulsion.

In the prepared polymer colloidal emulsion, 200% by weight of the ceramic filler slurry was added dropwise, and after stirring at a slow speed, a mixture of 5% lithium sulfate and zinc sulfate mixed salt solution (salt concentration of 40%) was added dropwise. The mixture was filtered through a 200-mesh filter cloth, coated on a PET base tape, and dried to obtain an ionic polymer film having a thickness of 40 μm.

Comparative example:

1. Single-layer polypropylene microporous membrane (40μm)

2, double-layer polypropylene composite film (80μm)

3, three-layer polypropylene composite film (120μm)

4, single-layer polyvinyl chloride microporous membrane (40μm)

5, single layer polyoxyethylene microporous membrane (40μm)

6, single layer nylon microporous membrane (40μm)

7. Single-layer fiberglass membrane (60μm)

8, single-layer asbestos paper (50μm)

9, polyethylene microporous membrane (20μm) + nylon composite membrane (40μm)

10, polyethylene microporous membrane (20μm) + non-woven fabric (20μm)

Performance Testing

In the examples and comparative examples of the present invention, the separator and its battery performance were tested in accordance with the following standard methods.

a, diaphragm conductivity test

The separator (Example membrane, comparative membrane) was air-dried, and then immersed in 1 mol/L lithium sulfate and 0.5 mol/L zinc sulfate mixed salt solution for 24 hours, and double-sided stainless steel sheets were assembled into 2032 button cells. The bulk resistance (Rb) was measured by electrochemical impedance spectroscopy; the ionic conductivity of the polymer separator was calculated according to the formula.

b, diaphragm suction test

The diaphragm was cut into a disc having a diameter of Ф80 mm using a standard die-cutting method, and baked in a blast oven at 90 ° C for 2 hours, and then the membrane sample was immersed in a 1 mol/L lithium sulfate and a 0.5 mol/L zinc sulfate mixed salt in a constant temperature environment. After 24 h in the solution, the surface was wiped off with a filter paper until no liquid beads were weighed. The difference between the wet weight and the dry weight divided by the dry weight is the unit liquid absorption of the diaphragm.

c. Preparation and performance test of ionic polymer zinc-lithium manganese secondary battery

1. Preparation of negative electrode piece: The negative electrode was made of a commercially available 50 μm thick zinc foil as a negative electrode, and was cut into 7 cm * 7 cm at the time of use and the electrode terminal was taken out at the edge.

2. Preparation of positive electrode tab: 85% by weight of lithium manganese oxide Li ₂ MnO ₃ used as a positive electrode active material, 5% of carbon black (super-p) used as a conductive material, and used as a binder A polytetrafluoroethylene (PTFE) 10% (solids weight) was prepared by stirring to prepare a positive electrode mixture slurry. The positive electrode mixture slurry was hot-pressed onto a stainless steel mesh current collector having a thickness of 40 μm, dried, and rolled to form a positive electrode tab having an areal density of 100 mg/cm 2 , and terminals were taken out from the current collector.

3. Diaphragm and electrolyte: The ion-ion polymer membrane and the polypropylene microporous membrane were respectively cut into 9cm*9cm membranes, and immersed in 1mol/L lithium sulfate and 0.5mol/L zinc sulfate mixed salt solution for 24h. In the present patent embodiment, in order to more clearly verify the effect of the separator on the dendrites in the zinc-lithium-manganese battery, in addition to testing the ionic polymer separator in the embodiment of the present invention to produce a battery of 40 μm, the method is also in a comparative manner. The diaphragms currently used in the market have been tested.

4. Battery fabrication: The positive/immersed separator/negative electrode is aligned and taped, and packaged using an aluminum-plastic composite film. To the assembled battery, 5 ml of 1 mol/L lithium sulfate and 0.5 mol/L zinc sulfate mixed salt solution were injected.

5. Battery test: The voltage test range is 1V--2.02V, the charge/discharge current is 0.1C/0.1C, and the temperature is 25±5°C.

Performance test result

The polymer membranes of Examples 1 to 4 were respectively immersed in a 1 mol/L lithium sulfate and 0.5 mol/L zinc sulfate mixed salt solution for 24 hours, and assembled into a 2032 button cell to measure the conductivity:

Table 2. Absorption of various diaphragm electrolytes and ionic conductivity

sample	Electrolyte absorption %	Conductivity S cm -1
Comparative example 1	125	8.81*10 -2
Comparative example 2	189	6.11*10 -2
Comparative example 3	265	1.31*10 -2
Comparative example 4	182	7.68*10 -2
Comparative example 5	201	7.21*10 -2
Comparative example 6	204	5.16*10 -2
Comparative example 7	281	4.42*10 -2
Comparative example 8	384	6.77*10 -2
Comparative example 9	217	5.34*10 -2
Comparative example 10	184	8.93*10 -2
Example 1	232	9.38*10 -4
Example 2	204	8.80*10 -4
Example 3	288	1.42*10 -3
Example 4	290	7.11*10 -3

As shown in the data in Table 2, since the single-layer microporous membrane or composite membrane used in Comparative Examples 1 to 10 only adsorbs the electrolyte by the pores of the separator, the present invention employs an ionic polymer membrane, which contains an anion and a cation such as a sulfonate. It has good affinity and wettability with the electrolyte, so it has good electrolyte retention ability.

In terms of electrical conductivity, ordinary polyolefin microporous membranes are based on ion transport that retains electrolyte in the pores, while ionic polymerization The film is the ion exchange conduction between the sulfonate in the colloidal surface formed by the separator and the electrolyte. The conductivity of the upper ionic polymer is lower, indicating that the ion conduction modes of the two membranes are different.

1 is a cycle life test chart of the ionic polymer film of Example 1 and Comparative Example 1 to 3 polypropylene microporous membrane. As shown in the figure, after two cycles of the single-layer polypropylene microporous membrane, the capacity is significantly decreased until The battery was short-circuited in 5 cycles, and even if the separator was increased to 3 layers of 120 μm thickness, it was only increased by 10 cycles. The reason is as before analysis, the separator makes the electrode ion deintercalation uneven during the charging and discharging process of the battery, that is, the microscopic battery is not uniform, thereby forming dendrites or even "dead" zinc, causing the electrode to collapse or even the dendrite piercing the diaphragm, so that The battery is short-circuited and scrapped. The ionic polymer membrane has a significant improvement in the cycle performance compared with the polypropylene microporous membrane, and its ion conduction homogenization cell has obvious effect on inhibiting dendrites.

2 is a cycle life graph of a zinc-lithium manganese secondary battery of a commercially available separator in Comparative Examples 1 to 10, as shown in the figure, whether it is a single-layer microporous membrane of various materials or a multilayer composite membrane, The cycle life of zinc-lithium-manganese secondary batteries is poor, mainly because the microporous membranes cannot inhibit the formation and growth of dendrites intrinsically, and thus cause the growth of dendrites to pierce the separator and cause short-circuit failure of the cells.

3 is a graph showing the cycle life of an ionic polymer film used in a zinc lithium manganese secondary battery in Examples 1 to 4 (but not limited to the examples) of the present invention, as shown in the figure, although the conductivity of the separator prepared by the material is different, There are some differences in capacity and the like, but the prepared zinc-lithium manganese secondary battery has a good cycle life, indicating that the ionic polymer film of the present invention has a significant effect on suppressing zinc dendrite.

Claims (10)

1. a secondary battery of a zinc-lithium-manganese water system, comprising a positive electrode, a negative electrode, an electrolyte, a separator between the positive electrode and the negative electrode; the active material of the positive electrode is a lithium manganese oxide material, and the active material of the negative electrode is a zinc or zinc compound. The electrolyte solution is a neutral aqueous solution containing a lithium salt and a zinc salt; and the separator is an ionic polymer film composed of acrylate polymer colloid particles having a sulfonate group on the surface.
2. The zinc-lithium manganese water system secondary battery according to claim 1, wherein the sulfonate group is a vinyl sulfonate, an allyl sulfonate or a methallyl sulfonate. One or more of allyloxyhydroxypropyl sulfonate, hydroxypropyl sulfonate methacrylate, 2-acrylamido-2-methylpropane sulfonate, and styrene sulfonate.
3. The zinc-lithium manganese water system secondary battery according to claim 2, wherein the colloidal particles in the separator have a particle diameter ranging from 10 nm to 1.0 μm, preferably from 20 to 200 nm.
4. The zinc-lithium manganese water system secondary battery according to claim 3, wherein the separator has a thickness of 10 to 100 μm.
5. The zinc-lithium manganese water system secondary battery according to any one of claims 1 to 4, wherein the acrylate-based polymer colloidal particles are polymethyl acrylates obtained by emulsion polymerization of methyl acrylate monomers. Colloidal particles.
6. The zinc-lithium manganese water system secondary battery according to any one of claims 1 to 4, wherein the acrylate-based polymer colloidal particles are obtained by emulsion polymerization of a methyl acrylate monomer and a second monomer. And the second monomer is used in combination of any one or more of CH ₂ =CR ₁ R ₂ ; wherein R ₁ =-H or -CH ₃ ; R ₂ =-C ₆ H ₅ , -OCOCH ₃ , -CN, -C ₄ H ₆ ON, -C ₂ H ₃ CO ₃ , -COO(CH ₂ ) _n CH ₃ , n is 0-14.
7. The zinc-lithium manganese water system secondary battery according to any one of claims 1 to 6, wherein the acrylate-based polymer colloidal particles are acrylate-based polymers having a sulfonate group on the surface thereof. The colloidal particles are combined with the ceramic filler.
8. The zinc-lithium manganese water system secondary battery according to claim 7, wherein the ceramic filler is a metal oxide or a metal composite oxide, and the general formula is NzMxOy, wherein N is an alkali metal or an alkaline earth metal element. M is a metal element or a transition metal, Z is 0 to 5, x is 1 to 6, and y is 1 to 15.
9. The zinc-lithium manganese water system secondary battery according to claim 7, wherein the ceramic filler is one or any combination of Al ₂ O ₃ , SiO ₂ and Li ₄ Ti ₅ O ₁₂ , preferably It is SiO ₂ or Al ₂ O ₃ .
10. The zinc-lithium manganese water system secondary battery according to claim 8 or 9, wherein the ceramic filler has an average particle diameter of 10 nm to 5.0 μm, preferably 20 nm to 0.5 μm; and most preferably, the average particle diameter is 20 nm to 200 nm.

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