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

Abstract

The invention discloses a preparation method of a multichannel asymmetric diaphragm for an aqueous zinc ion battery, which comprises the following steps: (1) dissolving PHEMA and PAN in a solvent to prepare a PHEMA / PAN spinning solution; (2) spinning the PHEMA / PAN spinning solution into a PHEMA / PAN nanofiber membrane by adopting an electrostatic spinning technology; (3) dissolving PVP in water or ethanol or a mixed solution of the water and the ethanol, then adding the MMT nanosheets, and uniformly dispersing to prepare printing ink; and (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) through an aerosol jet printing technology to form a functional layer so as to prepare the multichannel asymmetric diaphragm for the aqueous zinc ion battery. According to the invention, a hierarchical pore structure is constructed, electrolyte storage is assisted, efficient ion transmission and hydrogen evolution reaction inhibition are cooperatively realized, and technical support is provided for promoting practical application of the aqueous zinc ion battery.

Description

Technical Field

[0001] The invention belongs to the fields of polymer materials and electrochemistry, and in particular relates to a method for preparing a multi-channel asymmetric diaphragm for an aqueous zinc ion battery. Background Art

[0002] As the global energy mix shifts toward cleaner, lower-carbon energy, secondary batteries, as the core of electrochemical energy storage technology, are playing an increasingly important role in smart grids, electric vehicles, portable electronic devices, and other fields. While lithium-ion batteries (LIBs) dominate the field, their high cost, limited resources, and flammable organic electrolytes restrict their application in large-scale energy storage. Aqueous zinc-ion batteries (AZIBs) are considered an ideal choice for next-generation large-scale energy storage and flexible electronics due to their safety, environmental friendliness, low cost, and high theoretical capacity of zinc metal (819 mAh / g). However, their commercial application is hampered by interfacial stability issues at the Zn anode, primarily manifested by side reactions such as Zn dendrite growth, hydrogen evolution reaction (HER), and corrosion-induced passivation. These phenomena not only lead to capacity degradation but also pose safety risks such as separator puncture and short circuits.

[0003] The formation of zinc dendrites and the relationship between Zn 2+ The transport heterogeneity of zinc is closely related to the ion flux. Traditional separators (such as glass fiber and polyolefin) have a single pore structure or insufficient wettability, resulting in excessively high local current density, which exacerbates the uneven deposition of zinc. In addition, the presence of active water molecules in the aqueous electrolyte will participate in side reactions, further accelerating the corrosion of the zinc negative electrode and the formation of a passivation layer. Therefore, the development of a separator that can regulate ion flux, inhibit side reactions, and has mechanical stability has become the key to improving the performance of aqueous zinc-ion batteries.

[0004] The performance defects of traditional diaphragms are: (1) Glass fiber diaphragm: Although it has high porosity and good electrolyte wettability, it is thick (usually more than 300 μm), has low mechanical strength and is expensive, making it difficult to meet the needs of high energy density batteries; (2) Nafion membrane: It achieves high Zn 2+ Migration number, but its price is expensive (about $500 / m 2) and the production process is complex, making it difficult to apply on a large scale; (3) Cellulose-based membranes: using plant fibers as raw materials, they are low-cost and rich in oxygen-containing groups, but the pore distribution is uneven and lacks functional design, making it impossible to stably regulate the interfacial ion behavior in the long term. In recent years, researchers have optimized the performance of membranes through surface coatings, composite modifications, and other means. For example, with the help of polyacrylic acid for coating, a functional layer is formed on the surface of glass fiber through chemical bonding to inhibit dendrite growth, but its preparation requires high-temperature treatment (above 150°C), and the coating is prone to falling off due to cyclic stress. The composite membrane of boron inorganic particles (boron nitride) and polymers can improve heat resistance and ionic conductivity, but inorganic particles tend to block pores, affecting ion transmission efficiency. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries.

[0006] The technical solution of the present invention to solve the technical problem is to provide a method for preparing a multi-channel asymmetric diaphragm for an aqueous zinc ion battery, characterized in that the method comprises the following steps: (1) Preparation of PHEMA / PAN spinning solution: PHEMA and PAN were dissolved in a solvent to prepare PHEMA / PAN spinning solution; (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution was spun into PHEMA / PAN nanofiber membrane using electrospinning technology; (3) Preparation of printing ink: PVP is dissolved in water or ethanol or a mixture of the two, and then MMT nanosheets are added and dispersed evenly to prepare printing ink; (4) Preparation of an 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 preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries.

[0007] Compared with the prior art, the present invention has the following beneficial effects: (1) Construction of multi-level pore structure to facilitate electrolyte storage: The present invention creates a special microstructure (e.g., a sponge-like porous structure) through phase separation and solvent evaporation rate differences between PHEMA and PAN during the spinning process. 1) PHEMA has a higher viscosity, while PAN has a relatively lower viscosity. During the spinning process, the viscosity of the mixed solution gradually increases as the solvent evaporates. When the viscosity increases to a certain level, the viscosity difference between PHEMA and PAN becomes more pronounced. This viscosity difference causes stratification or separation of high-viscosity and low-viscosity regions in the spinning jet, thereby forming a phase-separated structure. 2) PHEMA is a polymer containing polar functional groups. The strong electronegativity of -C=O and -OH in its molecular chain makes the intermolecular forces and polarity much greater than PAN. Therefore, its interaction with polar solvents is stronger than PAN. This results in PHEMA crystallizing slower than PAN during the crystallization orientation process, thus forming a porous structure. 3) Based on 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 path for the one-way channel of zinc ions.

[0008] (2) Synergistic realization of efficient ion transport and hydrogen evolution reaction suppression: In this invention, the multi-level pore structure of the nanofiber membrane containing PHEMA and PAN effectively improves ionic conductivity. The PVP and MMT printed on the membrane surface interact with water molecules in the electrolyte to selectively adsorb water molecules and form localized water-depleted zones, thereby reducing the solvation of zinc ions during transport and accelerating their transport rate. Furthermore, the reduction in active water inhibits the hydrogen evolution reaction on the zinc negative electrode surface. This dual-action mechanism of "fast ion channel + corrosion isolation" significantly reduces the electrolyte consumption rate during cycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a scanning electron microscope image of the PHEMA / PAN nanofiber membrane prepared in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the functional layer of the asymmetric diaphragm prepared in Example 1 of the present invention; Figure 3 This is a coulombic efficiency diagram of the battery assembled in Example 1 of the present invention; Figure 4 Graph showing the change in specific capacity of the battery assembled in Example 1 of the present invention; Figure 5 The electrochemical impedance spectroscopy of the battery assembled in Example 1 of the present invention is shown; Figure 6 This is the electrochemical impedance spectroscopy of the battery assembled in Comparative Example 1 of the present invention; Figure 7 This is a coulombic efficiency diagram of the battery assembled in Comparative Example 1 of the present invention; Figure 8 This is a graph showing the change in specific capacity of the battery assembled in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0010] The specific embodiments of the present invention are given below. The specific embodiments are only used to further illustrate the present invention and do not limit the scope of protection of the present invention.

[0011] The present invention provides a method for preparing a multi-channel asymmetric diaphragm for an aqueous zinc ion battery (hereinafter referred to as the method), the method comprising the following steps: (1) Preparation of PHEMA / PAN spinning solution: PHEMA (poly(hydroxyethyl methacrylate)) and PAN (polyacrylonitrile) are dissolved in a solvent (preferably a polar solvent) to prepare a PHEMA / PAN spinning solution; Preferably, in step (1), the molecular weight of PHEMA is 150,000-200,000; the molecular weight of PAN is 100,000-150,000.

[0012] Preferably, in step (1), the solvent is DMF (N,N-dimethylformamide) or DMSO (dimethyl sulfoxide).

[0013] 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., solute, i.e., PHEMA and PAN) in the PHEMA / PAN spinning solution is 10-15 wt%.

[0014] Preferably, in step (1), the dissolution process is: stirring until all components are completely dissolved in the solvent, with a stirring speed of 500-700 rpm, a stirring time of 3-5 hours, and a stirring temperature of room temperature (i.e., 20-30°C). Preferably, the process is carried out in a magnetic stirrer.

[0015] (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution was spun into PHEMA / PAN nanofiber membrane using electrospinning technology; Preferably, in step (2), the process parameters of electrospinning are: spinning voltage of 30-40 kV, spinning speed of 1-3 ml / h, receiving distance of 15-25 cm, ambient humidity of 30-50%, ambient temperature of 20-50°C, and collection speed of 200-500 rpm.

[0016] Preferably, in step (2), the thickness of the PHEMA / PAN nanofiber membrane is 20-80 μm.

[0017] (3) Preparation of printing ink: PVP (polyvinyl pyrrolidone) is dissolved in water or ethanol or a mixture of the two, and then MMT nanosheets (nano-montmorillonite nanosheets) are added and dispersed evenly to prepare the printing ink required for the functional layer; Preferably, in step (3), the molecular weight of PVP is 30,000-80,000.

[0018] Preferably, in step (3), the dissolution process is: stirring until the PVP is completely dissolved in the solvent, with a stirring speed of 600-800 rpm, a stirring time of 3-5 hours, and a stirring temperature of room temperature (i.e., 20-30°C). Preferably, the process is carried out in a magnetic stirrer.

[0019] Preferably, in step (3), the volume ratio of water to ethanol in the mixture of water and ethanol is 1-2:1-2.

[0020] Preferably, in step (3), the thickness of the MMT nanosheet is 20-50 nm.

[0021] Preferably, in step (3), the process for uniform dispersion is: using ultrasound to completely disperse the components in the solvent, the ultrasound power is 360-540 W, the ultrasound frequency is 20-40 kHz, the ultrasound time is 0.5-2 h, and the ultrasound temperature is room temperature (i.e., 20-30°C).

[0022] 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 nanosheets is 3-7 wt% (preferably 3-6 wt%).

[0023] (4) Preparation of an 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 preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries (hereinafter referred to as an asymmetric diaphragm).

[0024] 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, and the droplets are introduced into the aerosol jet printing device through an air pipe; the focusing ratio of the carrier gas and the bound gas is adjusted to adjust the size of the sprayed droplets, and the bound gas compresses the carrier gas carrying the droplets into a focused jet, which is ejected from the print head and sprayed onto the substrate for aerosol jet printing to form a functional layer, thereby preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries.

[0025] Preferably, in step (4), the parameters of aerosol jet printing are: the pressure of pneumatic atomization is 0.3-0.7 MPa, the flow rate of the bound gas is 60-200 sccm, the focusing ratio of the carrier gas to the bound 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.

[0026] Preferably, in step (4), the carrier gas and the binding gas are nitrogen, carbon dioxide or an inert gas, and the inert gas is argon, helium, neon or krypton.

[0027] Example 1: (1) Preparation of PHEMA / PAN spinning solution: 0.5 g of PHEMA (molecular weight: 150,000) and 5 g of PAN (molecular weight: 100,000) were added to 49.5 g of DMF and stirred at 500 rpm with a magnetic stirrer at 20 °C for 3 h until all components were completely dissolved to prepare the PHEMA / PAN spinning solution. (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution was spun into 20 μm thick PHEMA / PAN nanofiber membrane using electrospinning technology; the spinning voltage was 30 kV, the spinning speed was 1 ml / h, the receiving distance was 15 cm, the ambient humidity was 30%, the ambient temperature was 20 °C, and the collection speed was 200 rpm; (3) Preparation of printing ink: 0.3 g of PVP with a molecular weight of 30,000 was added to 9.4 g of water and stirred at 800 rpm with a magnetic stirrer at 20°C for 3 h until the PVP was completely dissolved; then 0.3 g of MMT nanosheets with a thickness of 20 nm were added and ultrasonicated at 20°C, an ultrasonic power of 360 W, and an ultrasonic frequency of 40 kHz for 0.5 h until the PVP was completely dispersed to prepare the printing ink; (4) Preparation of asymmetric diaphragm: 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 to prepare an asymmetric diaphragm; the carrier gas and the bound gas were both nitrogen, the pressure of the pneumatic atomization was 0.3 MPa, the flow rate of the bound gas was 60 sccm, the focusing ratio of the carrier gas to the bound gas was 1:1, the printing speed was 20 mm / s, the printing height was 5 mm, the number of printing layers was 10, and the temperature of the printing table was 25 °C.

[0028] A zinc-ion battery was assembled using an asymmetric diaphragm: a composite of vanadium pentoxide, carbon, and adhesive PVDF in a mass ratio of 7:2:1 was used as the positive electrode material, zinc foil was used as the negative electrode material, 2M zinc sulfate was used as the electrolyte, and the asymmetric diaphragm was used as the diaphragm. During the assembly process, the functional layer was in contact with the negative electrode, and the electrochemical test results showed good cycle stability.

[0029] Depend on Figure 1 It can be seen that the fiber diameter of the PHEMA / PAN nanofiber membrane prepared in Example 1 is 500-700 nm and exhibits good continuity. At the same time, the surface of the fiber has an obvious porous structure.

[0030] Depend on Figure 2 It can be seen that the flake-like MMT is dispersed on the surface of the PHEMA / PAN nanofiber membrane.

[0031] Depend on Figure 3 and Figure 4 It can be seen that the battery composed of asymmetric diaphragm has an initial specific capacity of 292mAh / g at a current density of 0.3A / g, a capacity retention rate of 89% after 100 cycles, and a coulombic efficiency of about 100%.

[0032] Depend on Figure 5 It can be seen that the battery exhibits an interfacial impedance of only about 175Ω, proving that the prepared asymmetric separator facilitates the transport and interfacial transfer of zinc ions.

[0033] The above results prove that the prepared asymmetric membrane gives the battery better electrochemical performance.

[0034] Example 2: (1) Preparation of PHEMA / PAN spinning solution: 1 g of PHEMA (molecular weight: 200,000) and 5 g of PAN (molecular weight: 150,000) were added to 34 g of DMSO and stirred at 700 rpm with a magnetic stirrer at 25 °C for 4 h until all components were completely dissolved to prepare the PHEMA / PAN spinning solution. (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution was spun into PHEMA / PAN nanofiber membrane with a thickness of 80 μm using electrospinning technology; the spinning voltage was 40 kV, the spinning speed was 3 ml / h, the receiving distance was 25 cm, the ambient humidity was 50%, the ambient temperature was 50 °C, and the collection speed was 500 rpm; (3) Preparation of printing ink: 0.5 g of PVP with a molecular weight of 80,000 was added to 8.9 g of a mixture of water and ethanol (volume ratio of water:ethanol = 2:1), and stirred at 30 °C with a magnetic stirrer at 600 rpm for 5 h until the PVP was completely dissolved; then 0.6 g of MMT nanosheets with a thickness of 50 nm was added, and ultrasonicated at 25 °C, an ultrasonic power of 400 W, and an ultrasonic frequency of 40 kHz for 1 h until the PVP was completely dispersed to prepare the printing ink; (4) Preparation of asymmetric diaphragm: 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 to prepare an asymmetric diaphragm; the carrier gas and the bound gas were both argon, the pressure of the pneumatic atomization was 0.7 MPa, the flow rate of the bound gas was 200 sccm, the focusing ratio of the carrier gas to the bound gas was 5:1, the printing speed was 50 mm / s, the printing height was 15 mm, the number of printing layers was 20, and the temperature of the printing table was 60 °C.

[0035] The zinc-ion battery assembled with an asymmetric diaphragm has a capacity retention rate of 91% after 100 cycles at a current density of 0.5A / g.

[0036] Example 3: (1) Preparation of PHEMA / PAN spinning solution: 0.75 g of PHEMA (molecular weight: 150,000) and 5 g of PAN (molecular weight: 150,000) were added to 34.25 g of DMF and stirred at 600 rpm with a magnetic stirrer at 30 °C for 4 h until all components were completely dissolved to prepare the PHEMA / PAN spinning solution. (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution was spun into PHEMA / PAN nanofiber membrane with a thickness of 80 μm using electrospinning technology; the spinning voltage was 30 kV, the spinning speed was 2 ml / h, the receiving distance was 25 cm, the ambient humidity was 40%, the ambient temperature was 35 °C, and the collection speed was 300 rpm; (3) Preparation of printing ink: 0.4 g of PVP with a molecular weight of 80,000 was added to a mixture of 7.6 g of water and ethanol (volume ratio of water:ethanol = 1:2), and stirred at 700 rpm with a magnetic stirrer at 25 °C 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 ultrasonicated at 25 °C, an ultrasonic power of 360 W, and an ultrasonic frequency of 30 kHz for 1 h until the PVP was completely dispersed to prepare the printing ink; (4) Preparation of asymmetric membrane: 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 to prepare an asymmetric membrane; the carrier gas and the bound gas were both helium, the pressure of the pneumatic atomization was 0.3 MPa, the flow rate of the bound gas was 200 sccm, the focusing ratio of the carrier gas to the bound gas was 3:1, the printing speed was 35 mm / s, the printing height was 10 mm, the number of printing layers was 15, and the temperature of the printing table was 40 °C.

[0037] The zinc-ion battery assembled with an asymmetric diaphragm has a capacity retention rate of 87% after 300 cycles at a current density of 1A / g.

[0038] Example 4: (1) Preparation of PHEMA / PAN spinning solution: 1 g of PHEMA (molecular weight: 200,000) and 5 g of PAN (molecular weight: 100,000) were added to 34 g of DMSO and stirred at 550 rpm with a magnetic stirrer at 30 °C for 5 h until all components were completely dissolved to prepare the PHEMA / PAN spinning solution. (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution was spun into PHEMA / PAN nanofiber membrane with a thickness of 50 μm using electrospinning technology; the spinning voltage was 40 kV, the spinning speed was 1 ml / h, the receiving distance was 20 cm, the ambient humidity was 30%, the ambient temperature was 25 °C, and the collection speed was 400 rpm; (3) Preparation of printing ink: 0.3 g of PVP with a molecular weight of 30,000 was added to 8.7 g of ethanol and stirred at 650 rpm with a magnetic stirrer at 25 °C 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 ultrasonicated at 25 °C, an ultrasonic power of 540 W, and an ultrasonic frequency of 20 kHz for 2 h until the PVP was completely dispersed to prepare the printing ink; (4) Preparation of asymmetric membrane: 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 to prepare an asymmetric membrane; the carrier gas and the bound gas were both carbon dioxide, the pressure of the pneumatic atomization was 0.7 MPa, the flow rate of the bound gas was 60 sccm, the focusing ratio of the carrier gas to the bound gas was 2:1, the printing speed was 25 mm / s, the printing height was 8 mm, the number of printing layers was 12, and the temperature of the printing table was 50 °C.

[0039] The zinc-ion battery assembled with an asymmetric diaphragm has a capacity retention rate of 86% after 500 cycles at a current density of 1A / g.

[0040] Example 5: (1) Preparation of PHEMA / PAN spinning solution: 0.5 g of PHEMA (molecular weight: 150,000) and 5 g of PAN (molecular weight: 150,000) were added to 44.5 g of DMF and stirred at 700 rpm with a magnetic stirrer at 25 °C for 3 h until all components were completely dissolved to prepare the PHEMA / PAN spinning solution. (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution was spun into PHEMA / PAN nanofiber membrane with a thickness of 30 μm using electrospinning technology; the spinning voltage was 35 kV, the spinning speed was 3 ml / h, the receiving distance was 15 cm, the ambient humidity was 50%, the ambient temperature was 20 °C, and the collection speed was 250 rpm; (3) Preparation of printing ink: 0.5 g of PVP with a molecular weight of 50,000 was added to 8.5 g of a mixture of water and ethanol (volume ratio of water:ethanol = 1:1), and stirred at 700 rpm with a magnetic stirrer at 25 °C for 4 h until the PVP was completely dissolved; then 0.4 g of MMT nanosheets with a thickness of 30 nm was added, and ultrasonicated at 25 °C, an ultrasonic power of 400 W, and an ultrasonic frequency of 30 kHz for 1 h until the PVP was completely dispersed to prepare the printing ink; (4) Preparation of asymmetric diaphragm: 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 to prepare an asymmetric diaphragm; the carrier gas and the bound gas were both nitrogen, the pressure of the pneumatic atomization was 0.5 MPa, the flow rate of the bound gas was 100 sccm, the focusing ratio of the carrier gas to the bound gas was 4:1, the printing speed was 45 mm / s, the printing height was 15 mm, the number of printing layers was 10, and the temperature of the printing table was 60 °C.

[0041] The zinc-ion battery assembled with an asymmetric diaphragm has a capacity retention rate of 88% after 300 cycles at a current density of 0.5A / g.

[0042] Comparative Example 1: A zinc-ion battery was assembled using a commercial separator: a composite of vanadium pentoxide, carbon, and binder PVDF in a mass ratio of 7:2:1 was used as the positive electrode material, zinc foil was used as the negative electrode material, 2M zinc sulfate was used as the electrolyte, and a commercial separator (glass fiber membrane, model CF / D 1823-025 from Whatman) was used as the separator.

[0043] Depend on Figure 6 It can be seen that the interfacial impedance of the battery with the commercial separator is 270Ω, which is much larger than the interfacial impedance of 175Ω in Example 1. A larger interfacial impedance easily causes the formation of zinc dendrites on the surface of the zinc negative electrode, which ultimately affects the electrochemical stability of the battery.

[0044] Depend on Figure 7 and Figure 8 It can be seen that the zinc ion battery assembled with the commercial separator has an initial specific capacity of 303 mAh / g at a current density of 0.3 A / g, and a capacity retention rate of 68.7% after 100 cycles. Therefore, the zinc ion battery assembled with the asymmetric separator of the present invention has good cycle stability.

[0045] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A method for preparing a multi-channel asymmetric diaphragm for an aqueous zinc ion battery, characterized in that: The method comprises the following steps: (1) Preparation of PHEMA / PAN spinning solution: PHEMA and PAN were dissolved in a solvent to prepare PHEMA / PAN spinning solution; (2) Preparation of PHEMA / PAN nanofiber membrane: PHEMA / PAN spinning solution was spun into PHEMA / PAN nanofiber membrane using electrospinning technology; (3) Preparation of printing ink: PVP is dissolved in water or ethanol or a mixture of the two, and then MMT nanosheets are added and dispersed evenly to prepare printing ink; (4) Preparation of an 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 preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries.

2. The method for preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries according to claim 1, wherein In step (1), the molecular weight of PHEMA is 150,000-200,000; the molecular weight of PAN is 100,000-150,000; In step (1), the solvent is DMF or DMSO.

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

4. The method for preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries according to claim 1, wherein In step (2), the electrospinning process parameters are: spinning voltage of 30-40 kV, spinning speed of 1-3 ml / h, receiving distance of 15-25 cm, ambient humidity of 30-50%, ambient temperature of 20-50 °C, and collection speed of 200-500 rpm; In step (2), the thickness of the PHEMA / PAN nanofiber membrane is 20~80μm.

5. The method for preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries according to claim 1, wherein In step (3), the molecular weight of PVP is 30,000 to 80,000; In step (3), the dissolution process is: using a stirring method, the stirring speed is 600-800 rpm, the stirring time is 3-5 hours, and the stirring temperature is room temperature; In step (3), the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1-2:1-2.

6. The method for preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries according to claim 1, wherein: In step (3), the thickness of the MMT nanosheet is 20-50 nm; In step (3), the process for uniform dispersion is: using ultrasound, with an ultrasound power of 360~540W, an ultrasound frequency of 20~40KHz, an ultrasound time of 0.5~2h, and an ultrasound temperature of room temperature.

7. The method for preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries according to claim 1, wherein: 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%.

8. The method for preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries according to claim 1, wherein: 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, and the droplets are introduced into the aerosol jet printing device through an air pipe; the focusing ratio of the carrier gas and the bound gas is adjusted to adjust the size of the sprayed droplets, and the bound gas compresses the carrier gas carrying the droplets into a focused jet, which is ejected from the print head and sprayed onto the substrate for aerosol jet printing to form a functional layer, thereby preparing a multi-channel asymmetric diaphragm for aqueous zinc ion batteries.

9. The method for preparing a multi-channel asymmetric diaphragm for an aqueous zinc ion battery according to claim 1 or 8, wherein: In step (4), the parameters of aerosol jet printing are as follows: the pressure of pneumatic atomization is 0.3-0.7 MPa, the flow rate of the bound gas is 60-200 sccm, the focusing ratio of the carrier gas to the bound 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.

10. The method for preparing a multi-channel asymmetric diaphragm for an aqueous zinc ion battery according to claim 1, wherein: In step (4), the carrier gas and the binding gas are nitrogen, carbon dioxide or an inert gas, and the inert gas is argon, helium, neon or krypton.

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