Assemblies with negatively charged ionomer membranes for aqueous rechargeable zinc metal batteries

Abstract

The present invention relates to the assembly of a negatively charged dendrite-inhibiting ionomer membrane for aqueous rechargeable zinc metal batteries (AZMB) made by crosslinking sulfonated polyvinyl alcohol (PVS) and polyvinyl alcohol (PVA).

Description

[Technical Field]

[0001] The present invention relates generally to the technical field of electrochemical energy storage / electrochemical energy conversion. Specifically, the present invention relates to an assembly having a negatively charged ionomer membrane for aqueous rechargeable zinc metal batteries. More particularly, the present invention relates to an assembly having a negatively charged dendrite-inhibiting ionomer membrane made by crosslinking sulfonated polyvinyl alcohol (PVS) and polyvinyl alcohol (PVA) for aqueous rechargeable zinc metal batteries (AZMB). [Background technology]

[0002] Aqueous rechargeable zinc metal batteries (AZMBs) have recently attracted widespread attention as a promising electrochemical energy storage technology. AZMBs contain a metallic zinc (Zn) anode and a suitable cathode bound in an aqueous electrolyte, with a Zn 2+ The ions shuttling reversibly.

[0003] The deposition of high surface area zinc (HSAZ) / growth of zinc dendrites on zinc metal anodes during cycling poses a significant problem that reduces the cycling stability of aqueous rechargeable zinc metal batteries (AZMBs). Several attempts have been made in the past to address the above challenges by tailoring the electrolyte, interfacial phase, and separator.

[0004] For example, a paper titled "Dendrite Suppression Membranes for Rechargeable Zinc Batteries.b14022" by Liu et al., published in the academic journal "ACS Applied Materials & Interfaces 2018,10(45),38928-38935,DOI:10.1021 / acsami.8," describes the use of Zn deposition on the electrode surface to suppress (or inhibit; suppress) dendritic Zn deposition. 2+The use of a polymeric cation exchange membrane based on cross-linked polyacrylonitrile, which allows for a homogeneous distribution of ion flux, was demonstrated.

[0005] Another paper by Cui et al., entitled "An Interface-Bridged Organic-Layer that Suppresses Dendrite Formation and Side Reactions for Ultra-Long-Life Aqueous Zinc Metal Anodes," published in the journal Angewandte Chemie 2020, 132(38), 16737-16744, proposes the modification of the Zn metal surface with an organic-inorganic hybrid interphase (based on negatively charged Nafion ionomer and zeolite). This hybrid interface allows the Zn 2+ It prevents all small molecules, except ions, from reaching the Zn-metal surface, avoiding possible side reactions and providing excellent interfacial stability.

[0006] Similarly, a paper by Banik et al. entitled "Suppressing dendrite growth during zinc electrodeposition by PEG-200 additive" published in the academic journal "Journal of the Electrochemical Society 2013,160(11),D519" demonstrated the positive effect of a poly(ethylene glycol) (PEG)-based sacrificial surface protection layer on Zn dendrite growth.

[0007] However, complete cell fabrication and cycling studies of AZMB are missing in all the aforementioned reports.Other methods for surface modification of Zn metal include coating with inorganic materials such as TiO2, CaCO3, carbon coating, and the use of concentrated electrolytes.

[0008] Recently, a paper titled "A universal and facile approach to suppress dendrite formation for a Zn and Li metal anode" by Cao et al. was published in the academic journal "Journal of Materials Chemistry A 2020, 8 (18), 9331-9344, DOI:10.1039 / D0TA02486D." A graphene oxide (GO)-modified glass fiber separator was used to suppress Zn dendrite formation in a MnO||Zn full cell. The GO-modified separator showed good plating / peeling profiles, but the rate-capacity and specific capacity of the cell were found to be inferior compared to previous reports.

[0009] Furthermore, another paper titled "Nafion Ionomer-Based Single Component Electrolytes for Aqueous Zn / MnO2 Batteries with Long Cycle Life" by Kurungot, S. et al. was published in the academic journal "ACS Sustainable Chemistry & Engineering 2020, 8(13), 5040-5049, DOI: 10.1021 / acssuschemeng.9b06798" and reported that conventional neutral separators such as polypropylene, glass fiber, and filter paper promote dendritic Zn deposition in AZMB. As an alternative, Zn dendrites can be suppressed. 2+ -The potential of integrated Nafion™ (sulfonated tetrafluoroethylene-based fluoropolymer-copolymer) membranes has been reported. Despite its advantages, Nafion™ has drawbacks in terms of economics. Furthermore, due to the low ionic conductivity caused by the hydrophobic nature of the PTFE backbone, Nafion™ has poor water absorption under ambient temperature conditions. Therefore, ZnO has superior electrolyte intake, electrochemical properties, and processability to Nafion™. 2+ It is essential to design a conductive ionomer membrane.

[0010] Therefore, ZnO is a superior alternative to other negatively charged ionomer membranes such as Nafion™ for improving electrolyte uptake, electrochemical properties, and processability. 2+ There is a need in the art to design conductive ionomer membranes. Object of the invention

[0011] The primary objective of the present invention is to provide an assembly with an economically viable negatively charged dendrite-inhibiting ionomer membrane for aqueous rechargeable zinc-metal batteries (AZMB).

[0012] Another object of the present invention is to provide a negatively charged dendrite-suppressing ionomer membrane for aqueous rechargeable zinc-metal batteries (AZMB).

[0013] Another object of the present invention is to provide a method for producing negatively charged dendrite-inhibiting ionomers. Summary of the Invention

[0014] Therefore, to achieve this objective, the present invention provides an assembly having an economically viable negatively charged dendrite-inhibiting ionomer membrane for an aqueous rechargeable zinc-metal battery (AZMB), which is composed of a MnO cathode, a Zn metal anode, an aqueous ZnSO electrolyte, and a negatively charged dendrite-inhibiting ionomer membrane.

[0015] In one embodiment, the present invention provides a negatively charged dendrite suppression and Zn charge carrier made by crosslinking sulfonated polyvinyl alcohol (PVS) with polyvinyl alcohol (PVA) as a potential replacement for Nafion™ and neutral separators for aqueous rechargeable zinc-metal batteries (AZMB). 2+ A conductive (or electrically conductive) ionomer membrane is provided.

[0016] In one aspect of the embodiment, a self-standing negatively charged ionomer membrane (P-AS-C) is prepared by strategically crosslinking two polymers, polyvinyl alcohol (PVA) and sulfonated polyvinyl alcohol (PVS). The resulting PVA-co-PVS copolymer membrane (P-AS-C) is composed of sulfonic acid groups (SO ) generated from PVS. 3- When swollen in an aqueous ZnSO4 solution, the P-AS-C membrane exhibits ionomeric properties due to the presence of Zn 2+ This allows the film to conduct ions. Hereafter, this film will be called P-AS-C-Zn film.

[0017] An electrochemical cell assembly for an aqueous rechargeable zinc-metal battery, the electrochemical cell assembly comprising: (a) a cathode, (b) an anode, (c) an electrolyte, and (d) a negatively charged dendrite-inhibiting ionomer membrane, wherein the negatively charged dendrite-inhibiting ionomer membrane comprises sulfonated polyvinyl alcohol (PVS) crosslinked with polyvinyl alcohol (PVA).

[0018] In another aspect of the invention, the negatively charged dendrite-inhibiting ionomer membrane of the electrochemical cell assembly is Zn 2+ Conducts ions.

[0019] In another embodiment of the invention, the cathode of the electrochemical cell is a MnO2 cathode.

[0020] In another aspect of the invention, the anode of the electrochemical cell is a zinc metal anode.

[0021] In another embodiment of the invention, the electrolyte of the electrochemical cell is aqueous ZnSO4.

[0022] In another aspect of the invention, the negatively charged dendrite-inhibiting ionomer membrane of the electrochemical cell is 100 to 500 μm thick.

[0023] In another embodiment of the invention, the electrochemical cell has a specific capacity of 330 mAh / g at a current density of 0.25 A / g.

[0024] In another aspect, the present invention relates to a negatively charged dendrite-inhibiting ionomer membrane comprising polyvinyl alcohol (PVA) and sulfonated polyvinyl alcohol (PVS) crosslinked with polyvinyl alcohol (PVA) in a ratio of 30:70 to 70:30.

[0025] In one aspect of the embodiment, there is provided a method for producing a negatively charged ionomer membrane (P-AS-C), the method comprising the steps of: Step a) dissolving 2-8 g of PVA polymer in 70-90 mL of dry DMSO solvent at 70-95°C for 30-90 minutes; Step b) adding 0.5 to 2 g of a base selected from potassium carbonate, sodium carbonate, and lithium carbonate and 1 to 2 g of propane sultone to the solution of step a) and refluxing for 10 to 20 hours; step c) dialyzing the reaction mixture obtained in step b) against distilled water on a cellulose membrane for 10-15 hours, followed by removing excess water by distillation to obtain (afford) a yellow liquid; Step d) mixing 0.1-0.5 g of PVS with 1-5 g of aqueous PVA solution and 1-5 g of water; Step e) stirring the mixture obtained in step d) for 20-30 hours and pouring it into a Petri dish; and Step f) Heating the above reaction mixture in a hot air oven at 30 to 60°C for 10 to 20 hours to obtain a P-AS-C membrane.

[0026] In another embodiment of the present invention, a method for producing a negatively charged ionomer membrane includes punching a P-AS-C membrane into small disks with a radius of 0.3 to 0.9 cm, swelling the punched membranes in a 0.5 to 2 M ZnSO4·7H2O solution for 60 to 80 hours, and then ionizing the Zn 2+ It further includes ensuring (or assuring; or guaranteeing; ensuring) the uptake of.

[0027] In yet another aspect, the present invention relates to a negatively charged dendrite-inhibiting ionomer membrane comprising a sulfonated polyvinyl alcohol (PVS) crosslinked with polyvinyl alcohol (PVA). [Brief explanation of the drawings]

[0028] [Figure 1] Figure 1: H NMR spectrum of PVS polymer with peak assignments.

[0029] [Figure 2] Figure 2: FTIR spectrum of PVS polymer with peak assignments.

[0030] [Figure 3] Figure 3: Photograph of the PVS solution after dialysis and purification.

[0031] [Figure 4] Figure 4: Scanning electron microscope (SEM) images of (a) P-AS-C membrane and (b) PVA-C membrane.

[0032] [Figure 5] Figure 5: (a) Energy dispersive spectroscopy (EDS) elemental mapping and (b) energy dispersive X-ray analysis (EDAX) of the P-AS-C film.

[0033] [Figure 6] Figure 6: Tensile strength analysis of PVA-C and P-AS-C membranes.

[0034] [Figure 7]Figure 7: Swelling test of P-AS-C and PVA-C membranes in 1 M ZnSO4 aqueous solution (collected considering the weight difference of the membranes before and after immersion in the electrolyte solution for 3 days). The P-AS-C membrane showed higher electrolyte uptake compared to the PVA-C membrane.

[0035] [Figure 8] Figure 8: Nyquist plots of (a) P-AS-C-Zn film and (b) PVA-C-Zn film (temperature range 10–50 °C).

[0036] [Figure 9] Figure 9: Various steps in the processing of Zn2+-conducting ionomer electrolyte membrane (P-AS-C-Zn). Crosslinking by crystallization of PVS and PVA polymers leads to the formation of a free-standing P-AS-C membrane. When the P-AS-C membrane is swollen in ZnSO4 solution, the P-AS-C membrane securely incorporates Zn2+ ions. Therefore, the formed P-AS-C-Zn membrane is used to fabricate MnO2|P-AS-C-Zn|Zn full cells.

[0037] [Figure 10] Figure 10: (a) ln(σ) vs. 1000 / T plot (Arrhenius plot) showing the change in ionic conductivity as a function of temperature; (b) Comparison of CV profiles associated with P-AS-C-Zn and PVA-C-Zn films in the SS||Zn cell assembly; (c) Zn plating / peeling profiles of P-AS-C-Zn and PVA-C-Zn films in the Zn||Zn symmetric cell.

[0038] [Figure 11] Figure 11: FESEM images of the Zn metal (working electrode) surface recovered from (a), (b) Zn|P-AS-C-Zn|Zn and (c), (d) Zn|PVA-C-Zn|Zn cells; (e) XRD profiles of the Zn metal (working electrode) surface recovered from the Zn|P-AS-C-Zn|Zn and Zn|PVA-C-Zn|Zn symmetric cells compared with uncycled pristine Zn.

[0039] [Figure 12] Figure 12: (a) and (b) FESEM images of the Zn (pristine) electrode at different magnifications.

[0040] [Figure 13] Figure 13: Comparison of Nyquist plots recorded at the OCV and second discharge of (a) MnO2|PVA-C-Zn|Zn and (b) MnO2|P-AS-C-Zn|Zn cells. The associated Landells equivalent circuit model and fit are also shown.

[0041] [Figure 14] Figure 14: (a) CV and (b) GCD profiles of the MnO2|P-AS-C-Zn|Zn and MnO2|PVA-C-Zn|Zn cells, recorded at a scan rate of 0.1 mV s-1 and a current density of 0.25 A g-1, respectively. (c) Rate performance and (d) cycling stability of the MnO2|P-AS-C-Zn|Zn and MnO2|PVA-C-Zn|Zn cells.

[0042] [Figure 15] Figure 15: CV profiles of (a) MnO2|P-AS-C-Zn|Zn and (b) MnO2|PVA-C-Zn|Zn recorded at different scan rates.

[0043] [Figure 16] Figure 16: GCD profiles of (a) MnO2|P-AS-C-Zn|Zn and (b) MnO2|PVA-C-Zn|Zn recorded at various current densities.

[0044] [Figure 17] Figure 17: Comparison of the specific capacity of MnO2|P-AS-C|Zn, MnO2|treated Nafion™|Zn, and MnO2|untreated Nafion™|Zn cells at a current density of 0.25 A g-1. DETAILED DESCRIPTION OF THE INVENTION

[0045] It is to be understood that the illustrations and description of the invention have been simplified to illustrate elements relevant to a clear understanding of the invention. A detailed description is set forth below with reference to the accompanying drawings.

[0046] The present invention provides an economically viable negatively charged dendrite-inhibiting ionomer membrane assembly for aqueous rechargeable zinc-metal batteries (AZMBs), which includes a MnO cathode, a Zn metal anode, an aqueous ZnSO electrolyte, and a negatively charged dendrite-inhibiting ionomer membrane.

[0047] In one embodiment, the present invention provides a negatively charged dendrite suppression and Zn charge carrier separator made by crosslinking sulfonated polyvinyl alcohol (PVS) with polyvinyl alcohol (PVA) as a potential replacement for Nafion™ and neutral separators for aqueous rechargeable zinc-metal batteries (AZMB). 2+ A conductive ionomer membrane is provided.

[0048] In one aspect of the embodiment, a free-standing negatively charged ionomer membrane (P-AS-C) is prepared by strategically crosslinking two polymers, polyvinyl alcohol (PVA) and sulfonated polyvinyl alcohol (PVS). The resulting PVA-co-PVS copolymer membrane (P-AS-C) contains sulfonic acid groups (SO ) derived from PVS. 3- When swollen in an aqueous ZnSO4 solution, the P-AS-C membrane exhibits ionomeric properties due to the presence of Zn 2+ It becomes conductive to ions.

[0049] In one aspect of the embodiment, a process for preparing a negatively charged ionomer membrane (P-AS-C) is provided, the process comprising the steps of: (a) Dissolve 2–8 g of polyvinyl alcohol (PVA) polymer in 70–90 mL of dry dimethyl sulfoxide (DMSO) solvent at 70–95°C for 30–90 min; (b) adding 0.5-2 g of a base selected from potassium carbonate, sodium carbonate, and lithium carbonate and 1-2 g of propane sultone to the solution of step a), and refluxing for 10-20 hours to obtain a reaction mixture; (c) dialyzing the reaction mixture obtained in step b) against distilled water on a cellulose membrane for 10-15 hours, and then removing excess water by distillation to obtain a yellow liquid; (d) Mix 0.1-0.5 g of sulfonated polyvinyl alcohol (PVS) with 1-5 g of aqueous PVA solution and 1-5 g of water; (e) stirring the mixture obtained in step d) for 20-30 hours and pouring it into a Petri dish; and (f) The reaction mixture is heated in a hot air oven at 30 to 60°C for 10 to 20 hours to obtain a P-AS-C membrane.

[0050] The above process is shown in Scheme-1: [ka]

[0051] The specific capacity of the MnO2||Zn cell was compared with four types of separators: (1) untreated Nafion™, (2) pretreated Nafion™, (3) P-AS-C-Zn ionomer membrane, and (4) PVA-C-Zn membrane (non-ionomer). For comparison, the specific capacity of the MnO2||Zn cell was taken at a current density of 0.25 A / g. The comparison of specific capacity values ​​is shown in Table 1 (see Figure 17 for reference).

[0052] [Table 1]

[0053] From the above data, it is clear that the P-AS-C ionomer membrane is significantly superior to untreated Nafion™ in terms of specific capacity. The hydrophilic hydrocarbon backbone of P-AS-C contributes to better ionic conduction compared to the hydrophobic fluorinated backbone of untreated Nafion™. The superior performance of pretreated Nafion™ over untreated Nafion™ is likely due to the formation of more hydrophilic clusters as a result of the pretreatment. The advantage of P-AS-C is that it can exhibit comparable performance to pretreated and untreated Nafion™ without the need for a pretreatment step. Furthermore, processing of P-AS-C films is easier and more cost-effective than processing of Nafion™.

[0054] Furthermore, unlike Nafion™'s perfluoroether chains, P-AS-C membranes have a hydrocarbon backbone. Therefore, P-AS-C membranes are more hydrophilic than Nafion™, allowing them to incorporate more electrolytes than Nafion™, which helps improve ionic conduction. Because P-AS-C membranes are hydrophilic, even in a pretreated state, P-AS-C membranes form more clusters due to hydrophilic domains. This makes P-AS-C superior to Nafion™. The cycling stability of AZMB cells using Nafion™ and P-AS-C-Zn membranes is nearly equivalent. By improving the processing of P-AS-C-Zn membranes, membrane thicknesses can be further reduced to less than 100 micrometers, further improving performance to that of Nafion™ membranes.

[0055] In one embodiment, the present invention relates to a negatively charged dendrite-inhibiting ionomer membrane comprising sulfonated polyvinyl alcohol (PVS) crosslinked with polyvinyl alcohol (PVA).

[0056] In another embodiment of the present invention, the negatively charged dendrite-suppressing ionomer membrane is hydrophilic.

[0057] In another embodiment of the present invention, the negatively charged dendrite-reducing ionomer membrane is 100 to 500 microns thick, preferably 300 microns thick.

[0058] In one embodiment of the present invention, the sulfonated polyvinyl alcohol (PVS) and polyvinyl alcohol (PVA) in the negatively charged dendrite-inhibiting ionomer membrane are preferably present in a range of 30:70 to 70:30, with the most preferred ratio being 50:50.

[0059] Tensile strength measurement The P-AS-C membranes were punched into rectangles (5 mm wide, 30 mm long), the thickness was measured, and the specimens were loaded into the tensile grips of a calibrated universal testing machine (Model: 5943, Instron, Norwood, MA, USA) equipped with a 1 kN load cell. Tensile measurements were performed in triplicate at a crosshead speed of 1 mm / min. Load and elongation were recorded and plotted using Bluehill® II software.

[0060] Zeta potential measurement Aqueous solutions of PVS and PVA (0.1% w / v) were prepared and the pH of these solutions was measured. The solutions were loaded into transparent polystyrene cuvettes, and the zeta potential was measured in triplicate using a zeta potential analyzer (Model: ZetaPALS, Brookhaven Instruments, USA).

[0061] Electrochemical characterization A BioLogic VMP3 Potentiostat was used for electrochemical analysis, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). A Neware BTS-4008-5V 10mA was used for galvanostatic cycling of the fabricated cells. All electrochemical cells were fabricated using CR2032 coin cell assemblies. For the fabrication of MnO2||Zn full cells, zinc metal foil (0.95 cm) was used. 2 The electrodeposited MnO2 was used as the positive electrode (cathode). The amount of MnO2 supported in the electrode was approximately 1 mg cm-2 The MnO2|P-AS-C-Zn|Zn and MnO2|PVA-C-Zn|Zn cells were fabricated using P-AS-C-Zn or PVA-C-Zn films (thickness ≈ 300 μm, area ≈ 1.40 cm), respectively. 2 Similarly, Zn|P-AS-C-Zn|Zn and Zn|PVA-C-Zn|Zn cells were also fabricated, and 0.1 mAh cm -2 current density of 0.1 mAhcm for 1 hour -2 ) Zn plating peeling analysis was performed.

[0062] For ionic conductivity measurements, the membrane was placed between two stainless steel (SS) spacers in a CR2032 coin cell assembly, and EIS measurements were performed with an OCV over a frequency range of 1 MHz to 1 Hz at a voltage amplitude of 10 mV. An ESPEC environmental chamber was used to control the temperature during impedance measurements, and responses were recorded every 10°C (equilibration was maintained by holding the cell at each temperature for 30 minutes during measurements). The bulk resistance obtained at each temperature was used to calculate the membrane's ionic conductivity using Equation S1. σ=lA -1 R b -1 ......(Formula S1) Here, "R b ' is the bulk resistance, 'l' is the thickness, and 'A' is the area of ​​the film.

[0063] EIS analysis of the MnO2||Zn full cell was performed with an OCV at a voltage amplitude of 10 mV between the frequencies of 1 MHz and 100 mHz, with the equilibrium potential after the second discharge cycle being ≈0.8 V. The CVs of the full cell were 1, 0.5, 0.3, and 0.1 mVs. -1 The galvanostatic charge-discharge (GCD) profiles of the full cell were recorded at scan rates of 0.25, 0.5, 1, and 3 Ag. -1 All specific capacitance values ​​for the AZMB full cells were normalized to the MnO2 loading at the cathode. The CVs for the P-AS-C-Zn and PVA-C-Zn films were measured in the potential window of -0.25 to 2 V vs. Zn|Zn in the SS||Zn cell. 2+ Between, 0.5mVs -1The oxidative and reductive stability windows were understood by recording at scan rates of 0.05 to 0.15.

[0064] Material properties

[0065] Transfer 20 mg of PVS and 0.6 ml of DO to an NMR tube and mix using a vortex mixer. 1 H NMR spectra were recorded on a 400 MHz spectrometer (Model: Avance, Bruker, Germany). A drop of PVS was placed in a KBr cell and loaded into an FTIR spectrometer (Spectron One, PerkinElmer, Waltham, MA, USA). IR spectra of PVS were recorded and background subtracted. A BioLogic VMP3 potentiostat and a Neware BTS-4008-5V 10 mA battery tester were used for electrochemical characterization. An ESPEC environmental chamber was used for temperature control during impedance measurements. SEM images were collected using a Quanta 200-3D. A Quanta 200-3D instrument equipped with an energy-dispersive X-ray spectroscopy (EDX) detector was used for energy-dispersive spectroscopy (EDS) elemental mapping and energy-dispersive X-ray analysis (EDAX). A Nova Nano SEM 450 was used for field-emission scanning electron microscopy (FESEM) analysis. X-ray diffraction (XRD) analysis was carried out on a Rigaku MicroMax-007HF instrument equipped with a high-intensity microfocus rotating anode X-ray generator (CuKα (α = 1.54 Å)). [Example]

[0066] The following examples are illustrative and should not be construed as limiting the scope of the invention.

[0067] The materials used to prepare the PVA-C and PAS-C membranes were polyvinyl alcohol (98 mol% hydrolyzed, LOBA Chemie), 1,3-propane sultone (Sigma-Aldrich), potassium carbonate (Merck), and dimethyl sulfoxide (SD Fine Chemicals). Toray carbon paper was used as the current collector for the electrodeposition of MnO, supplied by Global Nanotech (Mumbai). The salts Mn(OOCCH) and (NHOOCCH) used for the electrodeposition of MnO were purchased from Sigma-Aldrich.

[0068] Example 1: Electrolytic deposition of MnO The electrodeposition of MnO was carried out in a standard three-electrode cell assembly (ACS Sustainable Chemistry & Engineering 2020, 8(13), 5040-5049, DOI: 10.1021 / acssuschemeng.9b06798). For this purpose, a Toray carbon paper (area 1 cm) was used as the working electrode. 2 ), a platinum mesh as the counter electrode, and a platinum wire as the quasi-reference electrode. The electrolytic deposition bath contained 432 mg of Mn(OOCCH3)2 and 193 mg of (NH4OOCCH3) dissolved in 25 mL of deionized water. The working electrode was supplied with a current of 4 mA cm 2 A constant current of 1 mg was applied to deposit ≈1 mg of MnO2.

[0069] Example 2: Preparation of P-AS-C-Zn membrane Sulfopropyl polyvinyl alcohol (PVS) was synthesized by the ring-opening reaction of PVA with propane sultone to impart ionomeric properties to PVA through sulfopropylation. Equimolar ratios of PVA and propane sultone were used for the synthesis of PVS. Potassium carbonate was used to neutralize the sulfonic acid groups formed during the homogeneous reaction. In a typical procedure, 5.0 g of PVA was dissolved in 80 ml of dry DMSO solvent at 85 °C for 1 h. 1 g of K2CO3 and 1.77 g of propane sultone were added and refluxed for 16 h. After cooling, the product was dialyzed against distilled water for 12 h using a cellulose membrane and then rotoevaporated to remove excess water, yielding a golden-yellow liquid.

[0070] Approximately 0.225 g of neat PVS was mixed with 2.25 g of a 10% (w / v) aqueous PVA solution and 2.025 g of water. The mixture was stirred for 24 h, poured into a glass Petri dish (4.5 cm diameter), and heated in a hot air oven at 45 °C for 12 h to obtain a P-AS-C membrane. The peeled membrane was punched into small disks with a radius of ≈0.67 cm and swollen in a 1 M ZnSO4.7H2O solution for 3 days. Zn 2+ The tensile strength of the ionomer membrane ranges from 10 to 30 MPa, and the water absorption capacity ranges from 150 to 200% of the dry weight.

[0071] Example 3: Preparation of PVA-C-Zn film PVA-C membranes without PVS were also prepared using the same procedure as in Example 2. The peeled membranes were punched into small disks with a diameter of approximately 0.3 to 0.9 cm, and swollen in 0.5 to 2 M ZnSO4.7H2O solutions for 3 days. 2+ was sure to be captured.

[0072] Advantages of the Invention Sulfopropylated polyvinyl alcohol (PVS) based Zn 2+ Conductive ionomer membranes were first introduced as a neutral separator for AZMB, potentially replacing Nafion™.

[0073] A free-standing negatively charged ionomer membrane (P-AS-C) is prepared by strategically cross-linking two polymers, polyvinyl alcohol (PVA) and sulfopropyl polyvinyl alcohol (PVS).

[0074] The anionic nature of the membrane results in an excellent Zn plating / peeling profile (stable for over 1100 hours without failure), smooth Zn deposition, and high cycling stability (50% capacity retention over 500 cycles in a MnO2|P-AS-C-Zn|Zn full cell).

[0075] Current density 0.25Ag -1 ≒ 330mAhg -1 , which is higher than the untreated Nafion™ equivalent.

Claims

1. (a) a cathode; (b) an anode; (c) an electrolyte, and (d) a negatively charged dendrite-inhibiting ionomer membrane; 1. An electrochemical cell assembly for an aqueous rechargeable zinc metal battery, wherein the negatively charged dendrite-inhibiting ionomer membrane comprises sulfopropyl polyvinyl alcohol (PVS) crosslinked with polyvinyl alcohol (PVA).

2. The negatively charged dendrite-inhibiting ionomer membrane is ２＋ 10. The electrochemical cell assembly of claim 1, which conducts ions.

3. The cathode is MnO ２ The electrochemical cell assembly of claim 1 , wherein the cell assembly is a cathode.

4. 10. The electrochemical cell assembly of claim 1, wherein the anode is a zinc metal anode.

5. The electrolyte is aqueous ZnSO ４ 2. The electrochemical cell assembly of claim 1, wherein:

6. 10. The electrochemical cell assembly of claim 1, wherein the negatively charged dendrite-reducing ionomer membrane is 100 to 500 microns thick.

7. 10. The electrochemical cell assembly of claim 1, wherein the cell has a specific capacity of 330 mAh / g at a current density of 0.25 A / g.

8. A negatively charged dendrite-inhibiting ionomer membrane comprising sulfopropyl polyvinyl alcohol (PVS) crosslinked with polyvinyl alcohol (PVA) in a ratio of 30:70 to 70:

30.

9. Step a) dissolving 2-8 g of polyvinyl alcohol (PVA) polymer in 70-90 mL of dry dimethyl sulfoxide (DMSO) as a solvent at a temperature of 70-95° C. for 30-90 minutes; Step b) adding 0.5-2 g of a base selected from potassium carbonate, sodium carbonate, and lithium carbonate and 1-2 g of propane sultone to the solution of step a), and refluxing for 10-20 hours to obtain a reaction mixture; step c) dialyzing the reaction mixture obtained in step b) through a cellulose membrane against distilled water for 10-15 hours, followed by removing excess water by distillation to obtain a yellow liquid; Step d) mixing 0.1-0.5 g of the yellow liquid sulfopropyl polyvinyl alcohol (PVS) of step c) with 1-5 g of an aqueous polyvinyl alcohol (PVA) solution and 1-5 g of water; Step e) stirring the mixture obtained in step d) for 20-30 hours and pouring into a Petri dish; and Step f) heating the reaction mixture in a hot air oven at 30-60°C for 10-20 hours to obtain a P-AS-C membrane material.

10. The P-AS-C film was punched into small disks with a radius of 0.3 to 0.9 mm, and the punched films were then soaked in 1 M ZnSO ４ . 7H ２ ZnO solution for 72 hours. ２＋ The method of claim 9, further comprising ensuring incorporation of

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