A zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation and its preparation method
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI UNIV
- Filing Date
- 2026-05-18
- Publication Date
- 2026-06-30
AI Technical Summary
Existing gel polymer electrolytes suffer from problems such as excessively strong initiator activation leading to uncontrolled polymerization, uneven polymer chain length, wide molecular weight distribution, and strong interaction between Zn2+ and water molecules in the hydrogel system, which hinders zinc ion migration, resulting in decreased ion transport rate and interface stability.
Using Zn(TFSI)2 as a zinc salt and initiator, a polyoxymethylene (POM) matrix was prepared by ring-opening polymerization. Dimethyl carbonate (DMC) was used as a plasticizer to construct a non-aqueous organic gel electrolyte, which avoids strong interactions and promotes uniform ion transport channels.
It achieves continuous and uniform ion transport channels, improves ion conductivity and uniform zinc ion deposition, and significantly enhances the cyclic stability and interfacial stability of the electrolyte.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of zinc-ion battery electrolyte technology, specifically to a zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation and its preparation method. Background Technology
[0002] Rechargeable zinc-ion batteries are characterized by high safety, low cost, and environmental friendliness. When polymer electrolytes are used, they also offer advantages such as flexibility, light weight, and high interfacial stability. Currently, polymer electrolytes are mainly classified into two categories: solid-state polymer electrolytes and gel polymer electrolytes.
[0003] Among them, solid polymer electrolytes suffer from the technical problem of low ionic conductivity. For example, existing literature 1 (Conformational Regulation of Dielectric Poly(Vinylidene Fluoride)-BasedSolid-State Electrolytes for Efficient Lithium Salt Dissociation and Lithium-Ion Transportation, Advanced Energy Materials, 2023, 13(15): 2203888.) obtained a TC polymer matrix with both high dielectric constant and all-trans conformation through a blending strategy, achieving an ionic conductivity of 0.24 mS·cm at room temperature. -1 The technology achieves a lithium-ion transference number of 0.61. While this solution improves electrolyte performance through a blending strategy, the inherent tendency of solid polymer electrolytes to crystallize at room temperature results in ionic conductivity that fails to meet application requirements. The principle is that the crystalline regions of the solid polymer electrolyte restrict the movement of polymer chain segments, thus preventing the formation of continuous ion transport channels.
[0004] Gel polymer electrolytes, by introducing plasticizers, effectively reduce the crystallinity of the polymer matrix, thereby significantly improving ionic conductivity. Therefore, their intrinsic ionic conductivity is significantly higher than that of solid polymer electrolytes. For example, existing literature 2 (Gradient fluoride, Zn-salt-rich hydrophobic interphase enabled by Zn-philic, H2O-phobic, anion-philic polymer "skin" for anode-free solid Zn battery, Energy & Environmental Science, 2024, 17(23): 9244-9254.) obtained a zinc-affinity, hydrophobic polymer electrolyte by in-situ polymerization of 3-methacryloyloxypropyltrimethoxysilane monomer, achieving a room-temperature ionic conductivity of 10.6 mS·cm. -1 The zinc ion transport number is 0.33, and the symmetric cell operates at 1 mA·cm⁻¹. -2 The technology achieves stable cycling for over 7000 hours under certain conditions. This solution effectively reduces polymer crystallinity by introducing a plasticizer into the gel polymer electrolyte, thereby further improving ionic conductivity. However, existing gel polymer electrolyte systems still have the following technical problems:
[0005] 1. To initiate monomer polymerization, an initiator needs to be added. However, current initiators are characterized by excessively strong activation capabilities. This directly leads to an excessively fast polymerization rate, making it impossible to effectively control the reaction and ultimately resulting in polymers with uneven chain lengths and wide molecular weight distributions.
[0006] This technical problem can be confirmed by existing literature 3 (Solvent-coordination-regulated gelpolymer electrolyte for stable high-voltage lithium metal batteries JournalPre-proof, 2026, 100568.). Specifically, when In(OTf)3 with strong activation ability is used as an initiator, there is a phenomenon of uncontrolled polymerization reaction, which makes it impossible to form a continuous ion transport path, ultimately leading to a decrease in ionic conductivity.
[0007] Furthermore, such technical solutions inevitably suffer from initiator residue problems—the residual In(OTf)3 can corrode the metal anode, leading to a significant reduction in interface stability.
[0008] 2. Currently, the gel polymer electrolyte in zinc-ion batteries is mainly a hydrogel system. This type of hydrogel-based technology has limitations regarding Zn... 2+ It forms [Zn(H2O)6] with water molecules. 2+ The solvated structure leads to a strong interaction between the hydrophilic gel framework and water molecules in the solvated structure—this strong interaction hinders the growth of Zn. 2+ Migration and the resulting steric hindrance effect ultimately lead to a significant decrease in ion transport rate and ion conductivity.
[0009] This technical problem can be confirmed by existing literature 4 (Lean-water hydrogel electrolyte for zincion batteries, Nature Communications, 2023, 14 (1), 3890.). Specifically, even when the zwitterionic polymer PZI is designed to control the state of water molecules, there is still a strong interaction between water molecules and sulfonic acid groups (-SO3⁻) on the polymer backbone, thus binding Zn. 2+ Transport. This technical solution demonstrates that the strong interaction between water molecules and the gel framework is a key factor affecting ion transport;
[0010] Furthermore, the solvation-based technical solutions also suffer from the problem of easy hydrolysis that triggers hydrogen evolution reactions, which in turn leads to severe side reactions at the electrode / electrolyte interface. Summary of the Invention
[0011] The purpose of this invention is to provide a zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation and its preparation method.
[0012] To address the technical problems existing in the current technology, the following methods are adopted to solve the above problems: 1. Zn(TFSI)2 is used as both a zinc salt and an initiator to initiate the ring-opening polymerization of TXE to prepare polyoxymethylene (POM) matrix. Furthermore, Zn(TFSI)2 has moderate activation ability, enabling controlled polymerization. The resulting POM has uniform chain length and narrow molecular weight distribution, which helps to construct continuous and uniform ion transport channels, thereby improving ionic conductivity. At the same time, no external initiator is required, avoiding the corrosion problem of initiator residue on the zinc anode and improving interfacial stability. 2. Dimethyl carbonate (DMC), which has a weak interaction with POM chains, was selected as a plasticizer to construct a non-aqueous organic gel electrolyte system. This utilizes the weak interaction between DMC and POM chains to avoid the negative impact of strong interactions on Zn. 2+The steric hindrance effect of migration promotes the uniform distribution of DMC in the gel electrolyte, constructing a continuous and uniform ion transport channel, thereby improving ionic conductivity and promoting uniform deposition of zinc ions, significantly enhancing cycling stability.
[0013] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:
[0014] A zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation is prepared by ring-opening polymerization of zinc bis(trifluoromethanesulfonyl)imide (Zn(TFSI)2), dimethyl carbonate (DMC), and 1,3,5-trioxane monomer (TXE) as raw materials to obtain DMC-POM-Zn(TFSI)2; wherein, Zn(TFSI)2 serves as the zinc salt and initiator, DMC serves as the solvent and plasticizer, and a weak interaction is formed between DMC and the polyoxymethylene matrix (POM).
[0015] The obtained DMC-POM-Zn(TFSI)2 had an electrochemical impedance of 7.0–8.0 Ω and an ionic conductivity of 0.55–0.70 mS·cm. -1 It can cycle stably for more than 3000 hours, and the polarization voltage remains at 80-90 mV during the cycle.
[0016] A method for preparing zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation is disclosed. The method employs ring-opening polymerization under argon conditions. First, bis(trifluoromethanesulfonyl)imide zinc Zn(TFSI)2 is used as the zinc salt and initiator, and dimethyl carbonate (DMC) is used as the solvent and plasticizer. Zn(TFSI)2 is dissolved in DMC to obtain a DMC-Zn(TFSI)2 solution. Then, 1,3,5-trioxane monomer TXE is dissolved in the DMC-Zn(TFSI)2 solution to obtain a clear and transparent precursor solution. Finally, the precursor solution is dropped onto a supporting membrane and heated to achieve the ring-opening polymerization reaction, yielding the zinc-based polyoxymethylene gel electrolyte, abbreviated as DMC-POM-Zn(TFSI)2.
[0017] The volume ratio of TXE to DMC is (4-5):5; The ring-opening polymerization reaction is heated at a temperature of 60-80 ℃ for a time of 60-120 min. The supporting membrane is a glass fiber membrane.
[0018] The beneficial technical effects obtained by this invention have been tested and confirmed to be: Macroscopic and NMR tests showed that Zn(TFSI)2 has an initiator effect, and a gel-like zinc-based polyoxymethylene gel electrolyte was successfully prepared.
[0019] FTIR testing showed that there is a weak interaction between DMC and POM.
[0020] SEM testing showed that the zinc anode surface after cycling with DMC-POM-Zn(TFSI)2 exhibited a dense and uniform zinc deposition morphology, with no obvious zinc dendrites or by-products.
[0021] EIS testing showed that the electrochemical impedance spectroscopy (EIS) of DMC-POM-Zn(TFSI)2 was 7.38 Ω and the ionic conductivity was 0.62 mS·cm. -1 .
[0022] Constant current charge-discharge tests showed that the Zn||Zn symmetric cell assembled with DMC-POM-Zn(TFSI)2 can achieve a current density of 0.5 mA·cm⁻¹. -2 Area capacity 0.5 mAh·cm -2 Under these conditions, it can cycle stably for more than 3000 hours, with the polarization voltage remaining stable at 85mV.
[0023] Therefore, the present invention has the following advantages over the prior art: 1. By using Zn(TFSI)2, which functions as both an initiator and a zinc salt, the necessary technical features of the original technology were successfully reduced, resulting in reduced raw material costs and process complexity. 2. When Zn(TFSI)2 is used as an initiator, it has moderate activation ability for TXE, which can effectively control the ring-opening polymerization. The resulting POM has uniform chain length and narrow molecular weight distribution, which helps to build continuous and uniform ion transport channels, thereby obtaining higher ionic conductivity. 3. DMC, which has a weak interaction with POM chains, was selected as a plasticizer to construct a non-aqueous organic gel system. The weak interaction between DMC and POM chains promoted the uniform distribution of DMC in DMC-POM-Zn(TFSI)2, forming continuous ion transport channels, improving ionic conductivity, and promoting the uniform deposition of zinc ions, thereby significantly improving the cycling stability of DMC-POM-Zn(TFSI)2. Attached Figure Description
[0024] Figure 1 Macroscopic test diagrams of the electrolyte state after heating DMC-POM-Zn(TFSI)2 in Example 1, DMC-Zn(OTf)2 in Comparative Example 1, and DMC-POM-Sn(OTf)2 in Comparative Example 2; Figure 2 The NMR spectrum of DMC-POM-Zn(TFSI)2 in Example 1; Figure 3 The FTIR plot of DMC-POM-Zn(TFSI)2 in Example 1; Figure 4 This is a SEM image of the zinc anode surface after cycling with DMC-POM-Zn(TFSI)2 in Example 1; Figure 5 EIS diagram of DMC-POM-Zn(TFSI)2 in Example 1; Figure 6 The graph shows the cycle performance of the Zn||Zn symmetric battery assembled with DMC-POM-Zn(TFSI)2 in Example 1. Figure 7 The NMR spectrum of DMC-POM-Sn(OTf)2 in Comparative Example 2; Figure 8 EIS plot of DMC-POM-Sn(OTf)2 in Comparative Example 2; Figure 9 The FTIR plot of VEC-POM-Zn(TFSI)2 in Comparative Example 3; Figure 10 This is a SEM image of the zinc anode surface after VEC-POM-Zn(TFSI)2 cycling in Comparative Example 3; Figure 11 EIS plot of VEC-POM-Zn(TFSI)2 in Comparative Example 3; Figure 12 The FTIR plot of FEC-POM-Zn(TFSI)2 in Comparative Example 4; Figure 13 This is a SEM image of the zinc anode surface after cycling in Comparative Example 4 (FEC-POM-Zn(TFSI)2). Figure 14 EIS plot of FEC-POM-Zn(TFSI)2 in Comparative Example 4; Figure 15 EIS plot of DMC-POM-Zn(TFSI)2-4 / 5 in Example 2; Figure 16 EIS plot of DMC-POM-Zn(TFSI)2-5 / 4 in Comparative Example 5. Detailed Implementation
[0025] The present invention will be further described in detail through embodiments and with reference to the accompanying drawings, but this is not intended to limit the scope of the invention.
[0026] Example 1
[0027] A method for preparing zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation is disclosed. The method employs ring-opening polymerization under argon atmosphere. First, using bis(trifluoromethanesulfonyl)imide zinc Zn(TFSI)2 as the zinc salt and initiator, and dimethyl carbonate (DMC) as the solvent and plasticizer, 0.2873 g of Zn(TFSI)2 is dissolved in 1 mL of DMC to obtain a DMC-Zn(TFSI)2 solution. Then, with a volume ratio of 1,3,5-trioxane monomer TXE to DMC of 5:5, 1 mL of TXE is dissolved in the DMC-Zn(TFSI)2 solution to obtain a clear and transparent precursor solution. Finally, 60 μL of the precursor solution is dropped onto a glass fiber support membrane and heated at 80 °C for 60 min to achieve the ring-opening polymerization reaction, yielding the zinc-based polyoxymethylene gel electrolyte, abbreviated as DMC-POM-Zn(TFSI)2.
[0028] To verify the macroscopic morphology of DMC-POM-Zn(TFSI)2, macroscopic tests were performed. The macroscopic test results are as follows: Figure 1 As shown, DMC-POM-Zn(TFSI)2 exists as a non-flowing white gel, i.e., a gel polymer. Test results indicate that Zn(TFSI)2, as an initiator, can achieve TXE ring-opening polymerization, successfully preparing zinc-based polyoxymethylene gel electrolyte.
[0029] To further demonstrate that Zn(TFSI)₂ acts as an initiator in the ring-opening polymerization of TXE, NMR testing was performed. The test results are as follows: Figure 2 As shown, in DMC-POM-Zn(TFSI)2, the proton signal belonging to the repeating unit CH2-O-CH2 is located at 4.38 ppm. Comparing this to the proton signal in the TXE monomer, where the O-CH2-O group is located at 5.18 ppm, the proton signal has shifted from 5.18 ppm to 4.38 ppm. The test results indicate that the transformation of the TXE monomer into a linear POM structure was successfully achieved, meaning that Zn(TFSI)2 acts as an initiator.
[0030] To demonstrate the interaction between DMC and the polyoxymethylene (POM) matrix in DMC-POM-Zn(TFSI)2, FTIR tests were performed on both POM and DMC-POM-Zn(TFSI)2. The test results are as follows: Figure 3 As shown, due to the introduction of DMC, the characteristic absorption peak of -CH2- of POM in DMC-POM-Zn(TFSI)2 changes from 2930.7 cm⁻¹. -1 Moved to 2923.16 cm -1 This indicates a redshift phenomenon. Test results show that there is a weak interaction between DMC and POM.
[0031] To demonstrate the effect of DMC-POM-Zn(TFSI)2 on the deposition morphology of the zinc anode, SEM analysis was performed on the zinc anode after cycling. The cycling conditions were a current density of 0.5 mA·cm⁻¹. -2 The surface area capacity is 0.5 mAh·cm³. -2 The loop was repeated 50 times. The test results are as follows: Figure 4 As shown, the zinc anode surface after cycling with DMC-POM-Zn(TFSI)2 exhibits a dense and uniform zinc deposition morphology, with no obvious zinc dendrites or by-products.
[0032] To demonstrate the ionic conductivity of DMC-POM-Zn(TFSI)2, an electrochemical conductivity (EIS) test was performed. The specific method for the EIS test was as follows: a coin cell was constructed using DMC-POM-Zn(TFSI)2 as the electrolyte and stainless steel foil as the positive and negative electrodes. The test was conducted at room temperature, with a frequency range of 0.1 Hz to 1 MHz and an amplitude of 10 mV. The test results are as follows. Figure 5 As shown, the electrochemical impedance spectroscopy of DMC-POM-Zn(TFSI)2 is 7.38 Ω, and the ionic conductivity is 0.62 mS·cm. -1 .
[0033] To demonstrate the cycle stability of DMC-POM-Zn(TFSI)2, a symmetrical constant current charge-discharge test was conducted. The specific method for the constant current charge-discharge test was as follows: a coin cell was constructed using DMC-POM-Zn(TFSI)2 as the electrolyte and zinc foil as both the positive and negative electrodes. The test temperature was room temperature, and the current density was 0.5 mA·cm². -2 The surface area capacity is 0.5 mAh·cm³. -2 Constant current charge-discharge tests were performed under the specified conditions. The constant current charge-discharge test results for DMC-POM-Zn(TFSI)2 are as follows: Figure 6 As shown, DMC-POM-Zn(TFSI)2 can be stably cycled for more than 3000 h, and the polarization voltage remains at 85 mV during the cycle.
[0034] To demonstrate that the initiator function of Zn(TFSI)2 is a unique property, Comparative Example 1 is provided, in which zinc trifluoromethanesulfonate zinc (Zn(OTf)2) is used as the zinc salt to replace the zinc-based electrolyte prepared by Zn(TFSI)2.
[0035] Comparative Example 1
[0036] A method for preparing a zinc-based electrolyte based on Zn(OTf)2, the steps of which are the same as those in Example 1 unless otherwise specified, except that Zn(OTf)2 is used as the zinc salt to replace Zn(TFSI)2, and the resulting material is referred to as DMC-Zn(OTf)2.
[0037] To verify the macroscopic morphology of DMC-Zn(OTf)2, macroscopic tests were performed. The macroscopic test results are as follows: Figure 1 As shown, DMC-Zn(OTf)2 remained a clear, transparent liquid, meaning it did not form a gel-like polymer. The test results indicate that Zn(OTf)2 cannot initiate the ring-opening polymerization of TXE, thus failing to prepare zinc-based polyoxymethylene gel electrolytes.
[0038] To further demonstrate the initiator effect of Zn(TFSI)2 and simultaneously demonstrate the influence of different initiators on the electrochemical performance of polymer electrolytes, Comparative Example 2 is provided, which uses tin trifluoromethanesulfonate Sn(OTf)2 as an initiator to prepare a zinc-based polyoxymethylene gel electrolyte.
[0039] Comparative Example 2
[0040] A method for preparing zinc-based polyoxymethylene gel electrolyte using Sn(OTf)2 as an initiator. The steps not specifically described are the same as those in Comparative Example 1, except that 0.014 g of Sn(OTf)2 is added as an initiator. The resulting material is referred to as DMC-POM-Sn(OTf)2.
[0041] To verify the macroscopic morphology of DMC-POM-Sn(OTf)2, macroscopic tests were performed. The macroscopic test results are as follows: Figure 1 As shown, DMC-POM-Sn(OTf)2 exists as a non-flowing white gel, i.e., a gel polymer. Test results indicate that Sn(OTf)2, as an initiator, can achieve TXE ring-opening polymerization, successfully preparing zinc-based polyoxymethylene gel electrolyte.
[0042] To demonstrate that Sn(OTf)₂ acts as an initiator in the ring-opening polymerization of TXE, NMR spectroscopy was performed. The test results are as follows: Figure 7As shown, in DMC-POM-Sn(OTf)2, the proton signal belonging to the repeating unit CH2-O-CH2 is located at 4.4 ppm. Compared with the O-CH2-O group in the TXE monomer, where the proton signal is located at 5.18 ppm, the proton signal has shifted from 5.18 ppm to 4.4 ppm. The test results indicate that although Sn(OTf)2 acts as an initiator and can initiate the ring-opening polymerization of TXE, the proton signal in DMC-POM-Sn(OTf)2 exhibits multiple peaks with a significantly increased peak width. This phenomenon suggests that the resulting polymer has characteristics of non-uniform chain length and a wide molecular weight distribution.
[0043] To demonstrate the ionic conductivity of DMC-POM-Sn(OTf)2, an EIS test was performed. The test results are as follows: Figure 8 As shown, the electrochemical impedance of DMC-POM-Sn(OTf)2 is 63.7 Ω, and the ionic conductivity is 0.072 mS·cm. -1 Compared with Example 1, it can be seen that using Zn(TFSI)2 as an initiator can increase the ionic conductivity by one order of magnitude. The reason, combined with the NMR test results, is that using Zn(TFSI)2 as an initiator can improve the uniformity of the polymer chains, thereby improving ion transport efficiency.
[0044] To demonstrate the effect of the weak interaction between DMC and POM on the electrochemical performance of polyoxymethylene gel electrolytes, i.e. the effect of plasticizer type, Comparative Examples 3 and 4 are provided, which are zinc-based polyoxymethylene gel electrolytes prepared with ethylene ethylene carbonate (VEC) and fluoroethylene carbonate (FEC) as plasticizers, respectively.
[0045] Comparative Example 3
[0046] A method for preparing zinc-based polyoxymethylene gel electrolyte using VEC as a plasticizer. The steps not specifically described are the same as in Example 1, except that VEC is used as the plasticizer instead of DMC. The resulting material is referred to as VEC-POM-Zn(TFSI)2.
[0047] To demonstrate the interaction between VEC and POM, FTIR tests were performed. The test results are as follows: Figure 9 As shown, although both exhibit a redshift, due to the introduction of VEC, the characteristic absorption peak of -CH2- of POM in VEC-POM-Zn(TFSI)2 shifts from 2930.7 cm⁻¹. -1 Displaced to 2922.42 cm -1 This indicates that there is a strong interaction between VEC and POM.
[0048] To demonstrate the effect of VEC-POM-Zn(TFSI)2 on the deposition morphology of the zinc anode, SEM analysis was performed on the cycled zinc anode. The test results are as follows: Figure 10 As shown, the zinc anode surface after VEC-POM-Zn(TFSI)2 cycling exhibits a clear aggregation state.
[0049] To demonstrate the ionic conductivity of VEC-POM-Zn(TFSI)2, an EIS test was performed. The test results are as follows: Figure 11 As shown, the electrochemical impedance of VEC-POM-Zn(TFSI)2 is 40.60 Ω, and the ionic conductivity is 0.11 mS·cm. -1 .
[0050] Comparative Example 4
[0051] A method for preparing zinc-based polyoxymethylene gel electrolyte using FEC as plasticizer. The steps not specifically described are the same as in Example 1, except that FEC is used as plasticizer instead of DMC. The resulting material is referred to as FEC-POM-Zn(TFSI)2.
[0052] To demonstrate the interaction between FEC and POM, FTIR tests were performed. The test results are as follows: Figure 12 As shown, although both exhibit a redshift, due to the introduction of FEC, the characteristic absorption peak of -CH2- of POM in FEC-POM-Zn(TFSI)2 shifts from 2930.7 cm⁻¹. -1 Displaced to 2921.13 cm -1 This indicates that there is a strong interaction between FEC and POM.
[0053] To demonstrate the effect of FEC-POM-Zn(TFSI)2 on the deposition morphology of the zinc anode, SEM analysis was performed on the cycled zinc anode. The test results are as follows: Figure 13 As shown, the zinc anode surface after cycling with FEC-POM-Zn(TFSI)2 exhibits a distinctly uneven state.
[0054] To demonstrate the ionic conductivity of FEC-POM-Zn(TFSI)2, an EIS test was performed. The test results are as follows: Figure 14 As shown, the electrochemical impedance of FEC-POM-Zn(TFSI)2 is 98.6 Ω, and the ionic conductivity is 0.046 mS·cm. -1 .
[0055] By comparing Example 1 with Comparative Examples 3 and 4, the following conclusions can be drawn: Since the interaction between DMC and POM is a weak interaction, while the interaction between VEC and FEC and POM is a strong interaction, using DMC as a plasticizer can promote the uniform distribution of DMC in DMC-POM-Zn(TFSI)2, thereby constructing a uniform ion transport channel, improving ion conductivity, and ultimately promoting the uniform deposition of zinc ions.
[0056] To demonstrate the effect of the volume ratio of TXE to DMC on the ionic conductivity of polyoxymethylene gel electrolyte, Examples 2 and 5 are provided, in which zinc-based polyoxymethylene gel electrolytes were prepared with volume ratios of TXE to DMC of 4:5 and 5:4, respectively.
[0057] Example 2
[0058] A method for preparing zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation. The steps not specifically described are the same as in Example 1, except that the volume ratio of TXE and DMC is replaced by 4:5 instead of 5:5. The resulting zinc-based polyoxymethylene gel electrolyte is referred to as DMC-POM-Zn(TFSI)2-4 / 5.
[0059] To demonstrate the ionic conductivity of DMC-POM-Zn(TFSI)2-4 / 5, EIS testing was performed. The test results are as follows: Figure 15 As shown, the electrochemical impedance of DMC-POM-Zn(TFSI)2-4 / 5 is 5.53 Ω, and the ionic conductivity is 0.83 mS·cm. -1 .
[0060] As can be seen from Examples 1 and 2, although increasing the volume ratio of DMC can slightly improve the ionic conductivity, an excessively high volume ratio of DMC will cause interfacial corrosion of the zinc anode.
[0061] Comparative Example 5
[0062] A method for preparing zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation. The steps not specifically described are the same as in Example 1, except that the volume ratio of TXE and DMC is replaced by 5:4 instead of 5:5. The resulting zinc-based polyoxymethylene gel electrolyte is referred to as DMC-POM-Zn(TFSI)2-5 / 4.
[0063] To demonstrate the ionic conductivity of DMC-POM-Zn(TFSI)2-5 / 4, EIS testing was performed. The test results are as follows... Figure 16 As shown, the electrochemical impedance of DMC-POM-Zn(TFSI)2-5 / 4 is 16.86 Ω, and the ionic conductivity is 0.27 mS·cm. -1 .
[0064] As can be seen from Example 1 and Comparative Example 5, reducing the volume ratio of DMC leads to a significant decrease in ionic conductivity. This is because an excessively low volume ratio of DMC results in a reduction in continuous ion transport channels, thereby causing a decrease in ion mobility.
[0065] As can be seen from Examples 1, 2 and Comparative Example 5, when the volume ratio of TXE to DMC is 5:5, not only can high ionic conductivity be obtained, but the adverse effects of excessive plasticizer on interface stability can also be avoided, that is, interface stability and high ionic conductivity can be balanced.
Claims
1. A zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation, characterized in that: DMC-POM-Zn(TFSI)2 was synthesized via ring-opening polymerization using bis(trifluoromethanesulfonyl)imide zinc Zn(TFSI)2, dimethyl carbonate (DMC), and 1,3,5-trioxane monomer (TXE) as raw materials; wherein, The Zn(TFSI)2 is used as both a zinc salt and an initiator. The DMC is used as a solvent and plasticizer. The DMC forms a weak interaction with the polyoxymethylene matrix POM.
2. The zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation according to claim 1, characterized in that: The obtained DMC-POM-Zn(TFSI)2 had an electrochemical impedance of 7.0–8.0 Ω and an ionic conductivity of 0.55–0.70 mS·cm. -1 .
3. The zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation according to claim 1, characterized in that: The obtained DMC-POM-Zn(TFSI)2 can be stably cycled for more than 3000 h, and the polarization voltage remains at 80-90mV during the cycle.
4. A method for preparing zinc-based polyoxymethylene gel electrolyte based on weak interaction regulation, characterized in that: Using a ring-opening polymerization method under argon conditions, firstly, bis(trifluoromethanesulfonyl)imide zinc Zn(TFSI)2 is dissolved in DMC as a zinc salt and initiator, and dimethyl carbonate (DMC) is dissolved as a solvent and plasticizer to obtain a DMC-Zn(TFSI)2 solution. Then, 1,3,5-trioxane monomer TXE is dissolved in the DMC-Zn(TFSI)2 solution to obtain a clear and transparent precursor solution. Finally, the precursor solution is dropped onto a supporting membrane and heated to achieve the ring-opening polymerization reaction, resulting in a zinc-based polyoxymethylene gel electrolyte, abbreviated as DMC-POM-Zn(TFSI)2.
5. The preparation method according to claim 4, characterized in that: The volume ratio of TXE to DMC is (4-5):
5.
6. The preparation method according to claim 4, characterized in that: The ring-opening polymerization reaction is heated at a temperature of 60-80 ℃ for a duration of 60-120 min.
7. The preparation method according to claim 4, characterized in that: The supporting membrane is a glass fiber membrane.