Preparation method of multi-channel asymmetric diaphragm for aqueous zinc ion battery

Abstract

The application discloses a preparation method of a multichannel asymmetric diaphragm for an aqueous zinc ion battery, and comprises the following steps: (1) dissolving PHEMA and PAN in a solvent to prepare PHEMA / PAN spinning liquid; (2) spinning the PHEMA / PAN spinning liquid into a PHEMA / PAN nanofiber membrane by using an electrostatic spinning technology; (3) dissolving PVP in water or ethanol or a mixture of the two, then adding MMT nanosheets and uniformly dispersing to prepare printing ink; (4) printing the printing ink prepared in the step (3) on the surface of one side of the PHEMA / PAN nanofiber membrane prepared in the step (2) by using an aerosol jet printing technology to form a functional layer, and thus the multichannel asymmetric diaphragm for the aqueous zinc ion battery is prepared. The multistage pore structure is constructed, electrolyte storage is assisted, efficient ion transmission and hydrogen evolution reaction inhibition are simultaneously realized, and technical support is provided for promoting the practical application of the aqueous zinc ion battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of high polymer materials and electrochemistry, and particularly relates to a preparation method of a multi-channel asymmetric diaphragm for water-based zinc ion batteries. BACKGROUND

[0002] With the transformation of global energy structure to clean and low-carbon, secondary batteries as the core carrier of electrochemical energy storage technology play an increasingly important role in the fields of smart grid, electric vehicles, portable electronic devices, etc. Among many secondary battery systems, although lithium ion batteries occupy a dominant position, their high cost, limited resources and flammable organic electrolyte limit their application in large-scale energy storage. Water-based zinc ion batteries (AZIBs) are considered as an ideal choice for the next generation of large-scale energy storage and flexible electronic devices due to their high safety, environmental friendliness, low cost and high theoretical capacity of zinc metal (819 mAh / g). However, their commercial application is still limited by the interface stability problem of zinc negative electrode, mainly manifested as zinc dendrite growth, hydrogen evolution reaction (HER), corrosion passivation and other side reactions. These phenomena not only lead to battery capacity attenuation, but also may cause diaphragm puncture and short circuit and other safety hazards.

[0003] The formation of zinc dendrites is closely related to the unevenness of Zn 2+ transport in the electrolyte. The single pore structure or insufficient wettability of traditional diaphragms (such as glass fiber, polyolefin) leads to excessive local current density, which exacerbates the uneven deposition of zinc. In addition, the presence of active water molecules in the water-based electrolyte will participate in the side reaction, further accelerating the corrosion of the zinc negative electrode and the formation of the passivation layer. Therefore, developing a diaphragm that can regulate ion flux, inhibit side reactions and have mechanical stability is the key to improving the performance of water-based zinc ion batteries.

[0004] The performance defects of traditional diaphragms are: (1) glass fiber diaphragm: although it has high porosity and good electrolyte wettability, its thickness is large (usually more than 300 μm), mechanical strength is low and cost is high, which is difficult to meet the demand of high energy density batteries; (2) Nafion membrane: high Zn 2+ migration number is realized through sulfonic acid groups, but its price is expensive (about 500 dollars / m 2(2) the production process is complex and difficult to scale up; (3) cellulose-based separators: low cost and rich in oxygen-containing groups, but uneven pore distribution and lack of functional design, cannot long-term stable control of interface ion behavior. In recent years, researchers have optimized the performance of the separator through surface coating, composite modification and other means, for example: with polyacrylic acid coating, a functional layer is formed on the surface of glass fibers by chemical bonding to suppress dendrite growth, but its preparation requires high temperature treatment (above 150℃), and the coating is easy to fall off due to cyclic stress. The composite film of boron inorganic particles (boron nitride) and polymer can improve the heat resistance and ionic conductivity, but the inorganic particles are easy to block the pores, affecting the ion transmission efficiency. SUMMARY

[0005] In view of the shortcomings of the prior art, the application provides a preparation method of a multi-channel asymmetric separator for aqueous zinc ion batteries.

[0006] The technical scheme for solving the technical problem of the application is to provide a preparation method of a multi-channel asymmetric separator for aqueous zinc ion batteries, characterized in that the method comprises the following steps:

[0007] (1) Preparation of PHEMA / PAN spinning solution: dissolve PHEMA and PAN in a solvent to prepare PHEMA / PAN spinning solution;

[0008] (2) Preparation of PHEMA / PAN nanofiber membrane: electrospinning technology is used to spin PHEMA / PAN spinning solution into PHEMA / PAN nanofiber membrane;

[0009] (3) Preparation of printing ink: dissolve PVP in water or ethanol or a mixture of the two, then add MMT nanosheets and disperse uniformly to prepare printing ink;

[0010] (4) Preparation of asymmetric separator: printing ink prepared in step (3) is printed on the surface of one side of the PHEMA / PAN nanofiber membrane prepared in step (2) by aerosol jet printing technology to form a functional layer, thereby obtaining a multi-channel asymmetric separator for aqueous zinc ion batteries.

[0011] Compared with the prior art, the application has the following advantages:

[0012] (1) Construction of multi-level pore structure to help electrolyte storage:

[0013] The present application has a special microstructure (for example, a porous structure similar to a sponge) caused by the phase separation of PHEMA and PAN during the spinning process and the difference in solvent evaporation speed. 1) PHEMA has a higher viscosity, while the viscosity of PAN is relatively low. During the spinning process, the viscosity of the mixed solution gradually increases as the solvent evaporates. When the viscosity increases to a certain extent, the viscosity difference between PHEMA and PAN becomes more obvious. This viscosity difference causes the high-viscosity and low-viscosity regions in the spinning jet to separate or separate, thereby forming a phase separation structure. 2) PHEMA is a polar functional group-containing polymer. The strong electronegativity of -C=O and -OH in the molecular chain makes the intermolecular force and polarity much greater than PAN, so its interaction with polar solvents is stronger than PAN. This causes the crystallization of PHEMA to be slower than that of PAN during the crystallization orientation process, thus forming a pore structure. 3) Based on the aerosol jet printing technology, a mixed solution containing a small amount of PVP and MMT is printed on the surface of the fiber membrane to construct a fast lane for zinc ion unidirectional channels.

[0014] (2) Synergistic realization of efficient ion transmission and inhibition of hydrogen evolution reaction:

[0015] In the present application, the multistage pore structure of the nanofiber membrane containing PHEMA and PAN can effectively improve the ion conductivity, and the PVP and MMT printed on the surface of the fiber membrane can selectively adsorb water molecules and form a local water-poor area by interacting with water molecules in the electrolyte, thereby reducing the solvation phenomenon of zinc ions during transmission and accelerating the transmission rate of zinc ions. At the same time, the reduction of active water can inhibit the hydrogen evolution reaction on the surface of the zinc negative electrode. This dual-effect mechanism of "fast ion channel + corrosion isolation" significantly reduces the electrolyte consumption rate during the cycle. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 SEM image of the PHEMA / PAN nanofiber membrane prepared in Example 1 of the present application;

[0017] Figure 2 SEM image of the functional layer of the asymmetric separator prepared in Example 1 of the present application;

[0018] Figure 3 Coulomb efficiency graph of the battery assembled in Example 1 of the present application;

[0019] Figure 4 Specific capacity change graph of the battery assembled in Example 1 of the present application;

[0020] Figure 5 Electrochemical impedance spectrum of the battery assembled in Example 1 of the present application;

[0021] Figure 6Electrochemical impedance spectrogram of the battery assembled in Inventive Example 1;

[0022] Figure 7 Coulomb efficiency graph of the battery assembled in Inventive Example 1;

[0023] Figure 8 Specific capacity change graph of the battery assembled in Inventive Example 1. DETAILED DESCRIPTION

[0024] The following gives specific embodiments of the present application. The specific embodiments are only for further detailed description of the present application, and do not limit the protection scope of the present application.

[0025] The present application provides a preparation method of a multi-channel asymmetric separator for aqueous zinc ion batteries (referred to as method), which comprises the following steps:

[0026] (1) Preparation of PHEMA / PAN spinning solution: PHEMA (polyhydroxyethyl methacrylate) and PAN (polyacrylonitrile) are dissolved in a solvent (preferably a polar solvent) to prepare a PHEMA / PAN spinning solution;

[0027] Preferably, in step (1), the molecular weight of PHEMA is 150000-200000; the molecular weight of PAN is 100000-150000.

[0028] Preferably, in step (1), the solvent is DMF (N,N-dimethylformamide) or DMSO (dimethyl sulfoxide).

[0029] Preferably, in step (1), the mass of PHEMA is 10-20% of the mass of PAN, and the mass fraction of the polymer (i.e. the solute, i.e. PHEMA and PAN) in the PHEMA / PAN spinning solution is 10-15wt%.

[0030] Preferably, in step (1), the dissolving process is: using stirring until all components are completely dissolved in the solvent, the stirring speed is 500-700 rpm, the stirring time is 3-5 h, and the stirring temperature is room temperature (i.e. 20-30℃). Preferably, it is carried out in a magnetic stirrer.

[0031] (2) Preparation of PHEMA / PAN nanofiber membrane: the PHEMA / PAN spinning solution is spun into a PHEMA / PAN nanofiber membrane by electrospinning technology;

[0032] Preferably, in step (2), the process parameters of electrospinning are: the spinning voltage is 30-40 kV, the spinning speed is 1-3 ml / h, the receiving distance is 15-25 cm, the environmental humidity is 30-50%, the environmental temperature is 20-50℃, and the collection speed is 200-500 rpm.

[0033] Preferably, in step (2), the thickness of the PHEMA / PAN nanofiber membrane is 20-80 μm.

[0034] (3) Preparation of printing ink: PVP (polyvinylpyrrolidone) is dissolved in water or ethanol or a mixture of the two, then MMT nanosheets (nanomontmorillonite nanosheets) are added and uniformly dispersed to prepare the printing ink required for the functional layer;

[0035] Preferably, in step (3), the molecular weight of PVP is 30000-80000.

[0036] Preferably, in step (3), the dissolving process is: using stirring to completely dissolve PVP in the solvent, the stirring speed is 600-800 rpm, the stirring time is 3-5 h, and the stirring temperature is room temperature (i.e. 20-30℃). Preferably, it is carried out in a magnetic stirrer.

[0037] Preferably, in step (3), in the mixture of water and ethanol, the volume ratio of water to ethanol is 1-2:1-2.

[0038] Preferably, in step (3), the thickness of the MMT nanosheet is 20-50 nm.

[0039] Preferably, in step (3), the uniform dispersion process is: using ultrasonic to completely disperse each component in the solvent, the ultrasonic power is 360-540 W, the ultrasonic frequency is 20-40 KHz, the ultrasonic time is 0.5-2 h, and the ultrasonic temperature is room temperature (i.e. 20-30℃).

[0040] Preferably, in step (3), in the printing ink, the mass fraction of PVP is 3-6 wt% (preferably 3-5 wt%), and the mass fraction of MMT nanosheet is 3-7 wt% (preferably 3-6 wt%).

[0041] (4) Preparation of asymmetric separator: the printing ink prepared in step (3) is printed on the surface of one side of the PHEMA / PAN nanofiber membrane prepared in step (2) by aerosol jet printing technology to form a functional layer, thereby obtaining a multi-channel asymmetric separator (hereinafter referred to as asymmetric separator) for water-based zinc ion batteries.

[0042] Preferably, in step (4), the aerosol jet printing technology is as follows: the PHEMA / PAN nanofiber membrane prepared in step (2) is used as a substrate and fixed on a printing table of an aerosol jet printing device; the printing ink prepared in step (3) is pneumatically atomized to form droplets, which are introduced into the aerosol jet printing device through a gas conveying pipe; the size of the jet droplets is adjusted by adjusting the focusing ratio of the carrier gas and the binding gas; the binding gas compresses the carrier gas carrying the droplets into a focused jet stream which is sprayed from the printing head to the substrate for aerosol jet printing to form a functional layer, thereby preparing a multi-channel asymmetric separator for aqueous zinc ion batteries.

[0043] Preferably, in step (4), the parameters of the aerosol jet printing are as follows: the pressure of the pneumatic atomization is 0.3-0.7 MPa, the flow rate of the binding gas is 60-200 sccm, the focusing ratio of the carrier gas to the binding gas is 1-5:1, the printing speed is 20-50 mm / s, the printing height is 5-15 mm, the number of printing layers is 10-20 layers, and the temperature of the printing table is 25-60°C.

[0044] Preferably, in step (4), the carrier gas and the binding gas are nitrogen, carbon dioxide or inert gas, and the inert gas is argon, helium, neon or krypton.

[0045] Example 1:

[0046] (1) Preparation of PHEMA / PAN spinning solution: 0.5 g of PHEMA with a molecular weight of 150000 and 5 g of PAN with a molecular weight of 100000 were added to 49.5 g of DMF, and stirred at 20°C with a magnetic stirrer at a speed of 500 rpm for 3 h until all components were completely dissolved to prepare a PHEMA / PAN spinning solution;

[0047] (2) Preparation of PHEMA / PAN nanofiber membrane: the PHEMA / PAN spinning solution was spun into a PHEMA / PAN nanofiber membrane with a thickness of 20 μm by electrospinning technology; the spinning voltage was 30 kV, the spinning speed was 1 ml / h, the receiving distance was 15 cm, the environmental humidity was 30%, the environmental temperature was 20°C, and the collection speed was 200 rpm;

[0048] (3) Preparation of printing ink: 0.3 g of PVP with a molecular weight of 30000 was added to 9.4 g of water, and stirred at 20°C with a magnetic stirrer at a speed of 800 rpm for 3 h until the PVP was completely dissolved; then 0.3 g of MMT nanosheet with a thickness of 20 nm was added, and ultrasonically dispersed at 20°C, an ultrasonic power of 360 W and an ultrasonic frequency of 40 KHz for 0.5 h to prepare a printing ink;

[0049] (4) Preparation of asymmetric separator: printing ink is printed on the surface of one side of the PHEMA / PAN nanofiber membrane by aerosol jet printing technology to form a functional layer, thereby preparing an asymmetric separator; the carrier gas and the binding gas are both nitrogen, the pressure of pneumatic atomization is 0.3 MPa, the flow rate of the binding gas is 60 sccm, the focusing ratio of the carrier gas to the binding gas is 1:1, the printing speed is 20 mm / s, the printing height is 5 mm, the printing layer number is 10, and the temperature of the printing table is 25°C.

[0050] Assembling a zinc ion battery using the asymmetric separator: a compound of vanadium pentoxide, carbon and adhesive PVDF with a mass ratio of 7:2:1 is used as a positive electrode material, zinc foil is used as a negative electrode material, 2M zinc sulfate is used as an electrolyte, and the asymmetric separator is used as a separator; in the assembling process, the functional layer is in contact with the negative electrode, and the electrochemical test results show good cycle stability.

[0051] From Figure 1 It can be seen that the fiber diameter in the PHEMA / PAN nanofiber membrane prepared in Example 1 is 500-700 nm, and shows good continuity, and the surface of the fiber has obvious pore structure.

[0052] From Figure 2 It can be seen that the sheet-shaped MMT is dispersed on the surface of the PHEMA / PAN nanofiber membrane.

[0053] From Figure 3 and Figure 4 It can be seen that the battery composed of the asymmetric separator has an initial specific capacity of 292 mAh / g at a current density of 0.3 A / g, the capacity retention rate is 89% after 100 cycles, and the coulombic efficiency is about 100%.

[0054] From Figure 5 It can be seen that the battery shows only an interface impedance of about 175Ω, which proves that the prepared asymmetric separator helps the transmission and interface transfer of zinc ions.

[0055] The above results prove that the prepared asymmetric separator endows the battery with good electrochemical performance.

[0056] Example 2:

[0057] (1) Preparation of PHEMA / PAN spinning solution: 1 g of PHEMA with a molecular weight of 200000 and 5 g of PAN with a molecular weight of 150000 are added to 34 g of DMSO, and stirred at 25°C with a magnetic stirrer at a speed of 700 rpm for 4 h until the components are completely dissolved, thereby preparing a PHEMA / PAN spinning solution;

[0058] (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution was spun into PHEMA / PAN nanofiber membrane with a thickness of 80 μm by electrospinning technology; the spinning voltage was 40 kV, the spinning speed was 3 ml / h, the receiving distance was 25 cm, the environmental humidity was 50%, the environmental temperature was 50°C, and the collection rotation speed was 500 rpm;

[0059] (3) Preparation of printing ink: 0.5 g of PVP with a molecular weight of 80000 was added to 8.9 g of a mixture of water and ethanol (volume ratio of water to ethanol = 2:1), and stirred at 30°C with a magnetic stirrer at a rotation speed of 600 rpm for 5 h until the PVP was completely dissolved; then 0.6 g of MMT nanosheet with a thickness of 50 nm was added, and ultrasonic dispersion was carried out at 25°C, an ultrasonic power of 400 W, and an ultrasonic frequency of 40 KHz for 1 h to completely disperse, to prepare the printing ink;

[0060] (4) Preparation of asymmetric separator: the printing ink was printed on the surface of one side of the PHEMA / PAN nanofiber membrane by aerosol jet printing technology to form a functional layer, and an asymmetric separator was prepared; the carrier gas and the binding gas were both argon, the pressure of pneumatic atomization was 0.7 MPa, the flow rate of the binding gas was 200 sccm, the focusing ratio of the carrier gas to the binding gas was 5:1, the printing speed was 50 mm / s, the printing height was 15 mm, the printing layer number was 20 layers, and the temperature of the printing platform was 60°C.

[0061] The zinc ion battery assembled with the asymmetric separator had a capacity retention rate of 91% after 100 cycles at a current density of 0.5 A / g.

[0062] Example 3

[0063] (1) Preparation of PHEMA / PAN spinning solution: 0.75 g of PHEMA with a molecular weight of 150000 and 5 g of PAN with a molecular weight of 150000 were added to 34.25 g of DMF, and stirred at 30°C with a magnetic stirrer at a rotation speed of 600 rpm for 4 h until the components were completely dissolved to prepare PHEMA / PAN spinning solution;

[0064] (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution was spun into PHEMA / PAN nanofiber membrane with a thickness of 80 μm by electrospinning technology; the spinning voltage was 30 kV, the spinning speed was 2 ml / h, the receiving distance was 25 cm, the environmental humidity was 40%, the environmental temperature was 35°C, and the collection rotation speed was 300 rpm;

[0065] (3) Preparation of printing ink: 0.4 g of PVP with a molecular weight of 80000 was added to a mixture of 7.6 g of water and ethanol (volume ratio of water to ethanol = 1:2), and stirred at 25°C with a magnetic stirrer at a speed of 700 rpm for 4 h until the PVP was completely dissolved; then 0.3 g of MMT nanosheets with a thickness of 20 nm was added, and ultrasonic dispersion was carried out at 25°C, an ultrasonic power of 360 W, and an ultrasonic frequency of 30 KHz for 1 h until complete dispersion, to prepare the printing ink;

[0066] (4) Preparation of asymmetric separator: the printing ink was printed on one side of the surface of the PHEMA / PAN nanofiber membrane by aerosol jet printing technology to form a functional layer, thereby preparing the asymmetric separator; the carrier gas and the binding gas were both helium, the pressure of pneumatic atomization was 0.3 MPa, the flow rate of the binding gas was 200 sccm, the focusing ratio of the carrier gas to the binding gas was 3:1, the printing speed was 35 mm / s, the printing height was 10 mm, the printing layer number was 15, and the temperature of the printing platform was 40°C.

[0067] The zinc ion battery assembled with the asymmetric separator had a capacity retention rate of 87% after 300 cycles at a current density of 1 A / g.

[0068] Example 4:

[0069] (1) Preparation of PHEMA / PAN spinning solution: 1 g of PHEMA with a molecular weight of 200000 and 5 g of PAN with a molecular weight of 100000 were added to 34 g of DMSO, and stirred at 30°C with a magnetic stirrer at a speed of 550 rpm for 5 h until the components were completely dissolved, to prepare the PHEMA / PAN spinning solution;

[0070] (2) Preparation of PHEMA / PAN nanofiber membrane: the PHEMA / PAN spinning solution was spun into a PHEMA / PAN nanofiber membrane with a thickness of 50 μm by electrospinning technology; the spinning voltage was 40 kV, the spinning speed was 1 ml / h, the receiving distance was 20 cm, the environmental humidity was 30%, the environmental temperature was 25°C, and the collection speed was 400 rpm;

[0071] (3) Preparation of printing ink: 0.3 g of PVP with a molecular weight of 30000 was added to 8.7 g of ethanol, and stirred at 25°C with a magnetic stirrer at a speed of 650 rpm for 4.5 h until the PVP was completely dissolved; then 0.6 g of MMT nanosheets with a thickness of 50 nm was added, and ultrasonic dispersion was carried out at 25°C, an ultrasonic power of 540 W, and an ultrasonic frequency of 20 KHz for 2 h until complete dispersion, to prepare the printing ink;

[0072] (4) Preparation of the asymmetric separator: the printing ink is printed on the surface of one side of the PHEMA / PAN nanofiber membrane by aerosol jet printing technology to form a functional layer, thereby preparing the asymmetric separator; the carrier gas and the binding gas are both carbon dioxide, the pressure of pneumatic atomization is 0.7 MPa, the flow rate of the binding gas is 60 sccm, the focusing ratio of the carrier gas to the binding gas is 2:1, the printing speed is 25 mm / s, the printing height is 8 mm, the number of printing layers is 12, and the temperature of the printing table is 50 DEG C.

[0073] The zinc ion battery assembled by using the asymmetric separator has a capacity retention rate of 86% after 500 cycles at a current density of 1 A / g.

[0074] Example 5

[0075] (1) Preparation of the PHEMA / PAN spinning solution: 0.5 g of PHEMA with a molecular weight of 150000 and 5 g of PAN with a molecular weight of 150000 are added to 44.5 g of DMF, and the mixture is stirred at 25 DEG C by using a magnetic stirrer at a rotating speed of 700 rpm for 3 h until the components are completely dissolved, thereby preparing the PHEMA / PAN spinning solution;

[0076] (2) Preparation of the PHEMA / PAN nanofiber membrane: the PHEMA / PAN spinning solution is spun into a PHEMA / PAN nanofiber membrane with a thickness of 30 μm by using electrospinning technology; the spinning voltage is 35 kV, the spinning speed is 3 ml / h, the receiving distance is 15 cm, the environmental humidity is 50%, the environmental temperature is 20 DEG C, and the collection rotating speed is 250 rpm;

[0077] (3) Preparation of the printing ink: 0.5 g of PVP with a molecular weight of 50000 is added to 8.5 g of a mixture of water and ethanol (the volume ratio of water to ethanol is 1:1), and the mixture is stirred at 25 DEG C by using a magnetic stirrer at a rotating speed of 700 rpm for 4 h until the PVP is completely dissolved; then, 0.4 g of MMT nanosheets with a thickness of 30 nm is added, and the mixture is ultrasonically treated at 25 DEG C, an ultrasonic power of 400 W and an ultrasonic frequency of 30 KHz for 1 h until the MMT nanosheets are completely dispersed, thereby preparing the printing ink;

[0078] (4) Preparation of the asymmetric separator: the printing ink is printed on the surface of one side of the PHEMA / PAN nanofiber membrane by aerosol jet printing technology to form a functional layer, thereby preparing the asymmetric separator; the carrier gas and the binding gas are both nitrogen, the pressure of pneumatic atomization is 0.5 MPa, the flow rate of the binding gas is 100 sccm, the focusing ratio of the carrier gas to the binding gas is 4:1, the printing speed is 45 mm / s, the printing height is 15 mm, the number of printing layers is 10, and the temperature of the printing table is 60 DEG C.

[0079] The zinc ion battery assembled by using the asymmetric separator has a capacity retention rate of 88% after 300 cycles at a current density of 0.5 A / g.

[0080] Comparative Example 1

[0081] The zinc ion battery assembled by using the commercial separator: a composite of vanadium pentoxide, carbon and adhesive PVDF with a mass ratio of 7:2:1 is used as the positive electrode material, zinc foil is used as the negative electrode material, 2M zinc sulfate is used as the electrolyte, and a commercial separator (glass fiber membrane, whatman CF / D 1823-025 type) is used as the separator.

[0082] From Figure 6 It can be seen that the interface impedance of the battery using the commercial separator is 270Ω, which is much larger than the interface impedance of 175Ω of the battery of Example 1. The larger interface impedance is easy to cause the formation of zinc dendrites on the surface of the zinc negative electrode, and then finally affects the electrochemical stability of the battery.

[0083] From Figure 7 and Figure 8 It can be seen that the zinc ion battery assembled by using the commercial separator has an initial specific capacity of 303 mAh / g at a current density of 0.3 A / g, and the capacity retention rate is 68.7% after 100 cycles. Therefore, the zinc ion battery assembled by using the asymmetric separator of the present application has good cycle stability.

[0084] The unmentioned parts of the present application apply to the prior art.

Claims

1. A method for preparing a multi-channel asymmetric separator for aqueous zinc-ion batteries, characterized in that, The method comprises the following steps: (1) Preparation of PHEMA / PAN spinning solution: PHEMA and PAN are dissolved in a solvent to prepare PHEMA / PAN spinning solution; (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution is spun into PHEMA / PAN nanofiber membrane by electrospinning technology; The process parameters of electrospinning are as follows: spinning voltage is 30-40 kV, spinning speed is 1-3 ml / h, receiving distance is 15-25 cm, environmental humidity is 30-50%, environmental temperature is 20-50 DEG C, and collection rotation speed is 200-500 rpm; The thickness of the PHEMA / PAN nanofiber membrane is 20-80 microns; (3) Preparation of printing ink: PVP is dissolved in water or ethanol or a mixture of the two, then MMT nanosheets are added and uniformly dispersed to prepare printing ink; (4) Preparation of asymmetric diaphragm: the printing ink prepared in step (3) is printed on the surface of one side of the PHEMA / PAN nanofiber membrane prepared in step (2) by aerosol jet printing technology to form a functional layer, thereby obtaining a multi-channel asymmetric diaphragm for water-based zinc ion battery.

2. The method of producing a multi-channel asymmetric separator for aqueous zinc-ion batteries according to claim 1, characterized in that, In step (1), the molecular weight of PHEMA is 150000-200000; the molecular weight of PAN is 100000-150000; In step (1), the solvent is DMF or DMSO.

3. The method of producing a multi-channel asymmetric separator for aqueous zinc-ion batteries according to claim 1, characterized in that, In step (1), the mass of PHEMA is 10-20% of the mass of PAN, and the mass fraction of polymer in PHEMA / PAN spinning solution is 10-15 wt%; In step (1), the dissolution process is as follows: stirring is used, the stirring speed is 500-700 rpm, the stirring time is 3-5 h, and the stirring temperature is room temperature.

4. The method of making a multi-channel asymmetric separator for aqueous zinc ion batteries according to claim 1, characterized in that, In step (3), the molecular weight of PVP is 30000-80000; In step (3), the dissolution process is as follows: stirring is used, the stirring speed is 600-800 rpm, the stirring time is 3-5 h, and the stirring temperature is room temperature; In step (3), in the mixture of water and ethanol, the volume ratio of water to ethanol is 1-2:1-2.

5. The method of making a multi-channel asymmetric separator for aqueous zinc ion batteries according to claim 1, characterized in that, In step (3), the thickness of MMT nanosheets is 20-50 nm; In step (3), the uniform dispersion process is as follows: ultrasonic is used, the ultrasonic power is 360-540 W, the ultrasonic frequency is 20-40 KHz, the ultrasonic time is 0.5-2 h, and the ultrasonic temperature is room temperature.

6. The method of producing a multi-channel asymmetric separator for aqueous zinc-ion batteries according to claim 1, characterized in that, In step (3), in the printing ink, the mass fraction of PVP is 3-6 wt%, and the mass fraction of MMT nanosheets is 3-7 wt%.

7. The method of producing a multi-channel asymmetric separator for aqueous zinc-ion batteries according to claim 1, characterized in that, In step (4), the aerosol jet printing technology is as follows: taking the PHEMA / PAN nanofiber membrane prepared in step (2) as a substrate, and fixing the substrate on a printing table of an aerosol jet printing device; performing pneumatic atomization on the printing ink prepared in step (3) to form droplets, and introducing the droplets into the aerosol jet printing device through a gas conveying pipe; adjusting the focusing ratio of the carrier gas and the binding gas to adjust the size of the jet droplets; the binding gas compresses the carrier gas carrying the droplets into a focused jet to be sprayed from a printing head, and the aerosol jet printing is performed on the substrate to form a functional layer, thereby obtaining a multi-channel asymmetric separator for a water-based zinc ion battery.

8. The method of producing a multi-channel asymmetric separator for aqueous zinc-ion batteries according to claim 1 or 7, characterized in that, In step (4), the parameters of the aerosol jet printing are as follows: the pressure of pneumatic atomization is 0.3-0.7 MPa, the flow rate of the binding gas is 60-200 sccm, the focusing ratio of the carrier gas and the binding gas is 1-5:1, the printing speed is 20-50 mm / s, the printing height is 5-15 mm, the number of printing layers is 10-20 layers, and the temperature of the printing table is 25-60℃.

9. The method of producing a multi-channel asymmetric separator for aqueous zinc ion batteries according to claim 1, characterized by, In step (4), the carrier gas and the binding gas are nitrogen, carbon dioxide or inert gas.

10. The method of producing a multi-channel asymmetric separator for aqueous zinc-ion batteries according to claim 9, characterized in that, In step (4), the inert gas is argon, helium, neon or krypton.

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