Phosphonoglyceride-based polymers, methods for their preparation and use

Abstract

The application discloses a glycerophosphonate-based polymer and a preparation method and application thereof. The glycerophosphonate-based polymer has the following structural formula: wherein R1, R2, R3, R4, R5 and R6 are independently selected from H or C 1‑ alkyl, m and n are positive integers greater than or equal to 1. The glycerophosphonate-based polymer of the application uses glyceride as a hydrophobic functional group, can prevent water molecules in an electrolyte from contacting a zinc anode interface, inhibit a hydrogen evolution reaction in a zinc ion deposition process, and also prevent zinc metal from self-corrosion. The phosphonic acid group has a strong bonding effect with zinc metal, stabilizes the zinc metal and the polymer interface, and prevents the polymer from falling off during zinc ion deposition and dissolution in a charging and discharging process. The polymer polymer as an electrolyte additive can induce uniform zinc ion deposition, stabilize the zinc / electrolyte interface, improve interface mass exchange, and finally realize long cycle life and excellent electrochemical performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of zinc ion batteries, in particular to a glycerol phosphonate-based polymer and a preparation method and application thereof. BACKGROUND

[0002] For decades, the main electrochemical energy storage system for large-scale production is organic alkali lithium ion battery. However, due to uneven distribution of lithium reserves, toxic organic electrolyte, insufficient battery safety and high price, etc., it is not conducive to large-scale grid energy storage. In recent years, batteries with metal iron, aluminum, zinc, lithium, sodium and other aqueous electrolytes have attracted widespread attention due to their high safety, low price and environmental friendliness. Among these alternative batteries, aqueous zinc ion batteries have received high attention because metal zinc has a suitable electrochemical potential (relative to hydrogen potential -0.76 V, does not react directly with water and has a high active theoretical specific capacity (820 mAh g -1 ), is environmentally friendly, has abundant reserves and low cost, and is considered as one of the powerful candidate technologies to achieve large-scale grid energy storage.

[0003] There are still some problems in the zinc anode of high-performance aqueous zinc ion batteries during the cycle process. First, the low redox potential of zinc metal leads to its thermodynamic instability in aqueous electrolyte, which is prone to hydrogen evolution (HER) and other side reactions. At the same time, the highly active zinc metal is prone to react with weak acid electrolyte to form Zn(OH)2·ZnSO4·nH2O byproduct, which hinders the electrode surface redox kinetics and increases the battery polarization. Second, the uneven deposition behavior of zinc ions during the cycle process is prone to lead to excessive growth of zinc dendrites, which reduces the cycle life and safety of the battery, and seriously hinders the practical application of aqueous zinc ion batteries. Improving the stability of zinc metal, inhibiting the side reactions of zinc anode, and promoting the uniform deposition and stripping of zinc are the key technical bottlenecks to promote the practical application of aqueous zinc ion batteries. SUMMARY

[0004] The purpose of the present application is to overcome the above technical deficiencies, and to provide a glycerol phosphonate-based polymer and a preparation method and application thereof, which solve the technical problems in the prior art that the poor stability of zinc metal, the easy occurrence of side reactions and the uneven deposition of zinc ions hinder the practical application of aqueous zinc ion batteries.

[0005] In a first aspect, the present application provides a glycerol phosphonate-based polymer having the following structural formula:

[0006] ;

[0007] wherein R1, R2, R3, R4, R5 and R6 are independently selected from H or C 1-alkyl of C3, m and n are positive integers ≥1.

[0008] In a second aspect, the present application provides a method for preparing a glycerophosphonate-based polymer, comprising the following steps:

[0009] polymerizing the phosphonic acid-based monomer and the glyceride-based monomer to obtain the glycerophosphonate-based polymer.

[0010] In a third aspect, the present application provides the use of the glycerophosphonate-based polymer as an electrolyte additive.

[0011] In a fourth aspect, the present application provides a zinc ion battery electrolyte, which comprises the glycerophosphonate-based polymer provided in the first aspect of the present application.

[0012] In a fifth aspect, the present application provides a water-based zinc ion battery, which comprises the zinc ion battery electrolyte provided in the fourth aspect of the present application.

[0013] Compared with the prior art, the present application has the following beneficial effects:

[0014] The glycerophosphonate-based polymer of the present application is a high-molecular polymer formed by phosphonic acid-based monomers and glyceride-based monomers as basic units. Glyceride, as a hydrophobic functional group, can prevent water molecules in the electrolyte from contacting the zinc anode interface, inhibit the hydrogen evolution reaction during zinc ion deposition, and also prevent zinc metal from self-corrosion. The phosphonic acid group has a strong bonding effect with zinc metal, stabilizing the zinc metal and high-molecular interface and preventing the high-molecular from falling off during zinc ion deposition and dissolution in the charging and discharging process. As an electrolyte additive, the high-molecular polymer can induce uniform zinc ion deposition, stabilize the zinc / electrolyte interface, improve the interface mass exchange, and ultimately realize a zinc ion battery with long cycle life and excellent electrochemical performance. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the SEM image of the zinc sheet after deposition in the pure ZnSO4 electrolyte (a) and the PPGAM+ZnSO4 electrolyte (b) in Example 2;

[0016] Figure 2 is the performance diagram of the half-cell cycle of the pure ZnSO4 electrolyte and the PPGAM+ZnSO4 electrolyte under different current densities in Example 3; -2 , (b) 10 mA cm -2 ;

[0017] Figure 3 is the performance diagram of the half-cell cycle of the pure ZnSO4 electrolyte and the PPGAM+ZnSO4 electrolyte under different current densities in Example 3;

[0018] Figure 4 is the half-cell charge-discharge curve of Example 3 using pure ZnSO4 electrolyte and PPGAM+ZnSO4 electrolyte;

[0019] Figure 5 is the full-cell cycle performance graph of Example 4 using pure ZnSO4 electrolyte and PPGAM+ZnSO4 electrolyte;

[0020] Figure 6 is the full-cell CV performance graph of Example 4 using pure ZnSO4 electrolyte and PPGAM+ZnSO4 electrolyte. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0022] The phosphonoglyceride-based polymer of the present application is a high molecular polymer formed by phosphonic acid-based monomers and glyceride-based monomers as basic units. Glyceride as a hydrophobic functional group can prevent water molecules in the electrolyte from contacting the zinc anode interface, inhibit the hydrogen evolution reaction during zinc ion deposition, and also prevent zinc metal from self-corrosion. The phosphonic acid group has a strong bonding effect with zinc metal, stabilizing the zinc metal and high molecular interface, preventing the high molecular from falling off during zinc ion deposition and dissolution in the charging and discharging process. As an electrolyte additive, the high molecular polymer can induce uniform zinc ion deposition, stabilize the zinc / electrolyte interface, improve the interface mass exchange, and ultimately realize long cycle life and excellent electrochemical performance of the zinc ion battery. This method has not been reported in the literature and patents. Based on this, the present application is proposed.

[0023] In a first aspect, the present application provides a phosphonoglyceride-based polymer having the following structural formula:

[0024]

[0025] wherein R1, R2, R3, R4, R5, R6 are independently selected from H or C 1- alkyl, m and n are both positive integers ≥1.

[0026] In a second aspect, the present application provides a preparation method of a phosphonoglyceride-based polymer, comprising the following steps:

[0027] The phosphonic acid-based monomers and glyceride-based monomers are subjected to a polymerization reaction to obtain the phosphonoglyceride-based polymer. The specific reaction formula is as follows:

[0028]

[0029] ​​The phosphonate glyceride-based high molecular polymer is successfully synthesized through a polymerization reaction.

[0030] In the embodiment, the phosphonic acid group monomer is a monomer and derivative containing a phosphonic acid group. The present application does not limit the type of phosphonic acid group monomer, and those skilled in the art can select according to the actual situation. For example, the phosphonic acid group monomer can be vinyl phosphonic acid, cis-propylene phosphonic acid, etc.

[0031] In the embodiment, the glyceride group monomer is a monomer and derivative containing a glyceride group. The present application does not limit the type of glyceride group monomer, and those skilled in the art can select according to the actual situation. For example, the glyceride group monomer can be glycidyl methacrylate, etc. The present application has high flexibility by selecting glycidyl methacrylate as the glyceride group monomer, which can better alleviate the stress in the dendrite growth process and prevent dendrite from piercing the SEI film.

[0032] In the embodiment, the molar ratio of the phosphonic acid group monomer to the glyceride group monomer is 1:(0.1-10), including but not limited to 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, 1:5, 1:10, etc.

[0033] In the embodiment, an initiator is also added during the polymerization reaction. The present application does not limit the type of initiator, and those skilled in the art can select according to the actual situation. For example, the initiator can be ammonium persulfate, sodium persulfate, etc.

[0034] Further, the amount of initiator added is 0.1-3% of the total mass of the phosphonic acid group monomer and the glyceride group monomer, including but not limited to 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc.

[0035] In the embodiment, the solvent used for the polymerization reaction is a mixed solvent of water and propylene glycol methyl ether. By using the above mixed solvent, the raw materials can be fully dissolved, and the reaction can proceed smoothly.

[0036] Further, in the mixed solvent, the volume ratio of water to propylene glycol methyl ether is (1-5):1, including but not limited to 1:1, 2:1, 3:1, 4:1, 5:1, etc.

[0037] Further, the ratio of the total mass of the phosphonic acid group monomer and the glyceride group monomer to the amount of the mixed solvent is 1g:(15-25)mL, including but not limited to 1g:15mL, 1g:18mL, 1g:20mL, 1g:22mL, 1g:25mL, etc.

[0038] In the embodiment, the temperature of the polymerization reaction is 40-180 DEG C, including but not limited to 40 DEG C, 60 DEG C, 80 DEG C, 100 DEG C, 120 DEG C, 140 DEG C, 160 DEG C, 180 DEG C; if the temperature of the polymerization reaction is too low, the reaction cannot proceed smoothly; if the temperature of the polymerization reaction is too high, the reaction is too rapid, and a supermolecule insoluble in water is easily formed; the time of the polymerization reaction is 0.5 h-10 h, including but not limited to 0.5 h, 2 h, 4 h, 6 h, 8 h, 10 h. If the time of the polymerization reaction is too short, the reaction is incomplete; if the time of the polymerization reaction is too long, the production cost increases.

[0039] In a third aspect, the application provides a use of the above-mentioned glycerophosphonate-based polymer as an electrolyte additive.

[0040] In a fourth aspect, the application provides a zinc ion battery electrolyte, which comprises the glycerophosphonate-based polymer provided in the first aspect.

[0041] By using the glycerophosphonate-based polymer as an electrolyte additive of a zinc ion battery, a polymer solid electrolyte membrane can be formed on the surface of a zinc anode in a cycle process, zinc ions are induced to be uniformly deposited, a zinc / electrolyte interface is stabilized, and ion exchange at the interface is improved, so that the zinc ion battery finally exhibits a long cycle life and excellent electrochemical performance.

[0042] In the embodiment, the mass fraction of the glycerophosphonate-based polymer in the zinc ion battery electrolyte is 0.0001%-10%, including but not limited to 0.0001%, 0.001%, 0.01%, 0.1%, etc. If the amount of the glycerophosphonate-based polymer added is too much, organic matter will be broken and precipitated; if the amount of the glycerophosphonate-based polymer added is too little, the thickness of the formed protective layer is too small, and the protective effect cannot be achieved.

[0043] In the embodiment, the zinc ion battery electrolyte is a zinc salt solution. The application does not limit the type and concentration of the zinc salt, and a person skilled in the art can select them according to actual conditions. For example, the zinc salt includes but is not limited to zinc sulfate, zinc acetate, zinc nitrate, etc.; the concentration of the zinc salt is 0.5-3 mol / L, including but not limited to 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, etc. -1 -1 -1 -1 -1

[0044] In a fifth aspect, the application provides a water-based zinc ion battery, which comprises the zinc ion battery electrolyte provided in the fourth aspect.

[0045] ​​​​​The aqueous zinc ion battery of the application further comprises: a positive electrode, a negative electrode and a separator; wherein the negative electrode is zinc metal. The application does not limit the specific types of the positive electrode and the separator, and a person skilled in the art can select them according to the actual situation. For example, the positive electrode can be (NH4)2V 10 O 25 ·8H2O, etc.; the separator can be glass fiber, etc.

[0046] Example 1

[0047] Ethylene phosphonic acid (2.5 g), glycidyl methacrylate (2.5 g), water (65 g), propylene glycol methyl ether (30 mL) and ammonium persulfate (0.1 g) were uniformly mixed, and then reacted in an 80℃ oil bath for 4h to obtain a phosphonic acid glycerol-based electrolyte additive, denoted as PPGAM. The specific reaction formula is as follows:

[0048] .

[0049] Example 2

[0050] High-performance phosphonic acid glycerol-based zinc ion battery electrolyte additive battery performance test:

[0051] 1 / 10000 of the polymer prepared in Example 1 was added to 2 mol L -1 ZnSO4 electrolyte, and the obtained electrolyte was a phosphonic acid glycerol-based zinc ion battery electrolyte, denoted as PPGAM+ZnSO4 electrolyte. The pure Zn electrolyte as a control sample was 2 mol L -1 ZnSO4.

[0052] A Zn / / Zn symmetric battery was directly assembled, the electrode sheet was 1 cm 2 , and the separator was glass fiber. When the battery was assembled, the mass of the electrolyte dropped on the separator was 0.01g~0.03g.

[0053] Please refer to Figure 1 , Figure 1 is the SEM image of the zinc sheet after deposition in the pure 2 mol L -1 ZnSO4 electrolyte (a) and the PPGAM+2 mol L -1 ZnSO4 electrolyte (b) in Example 2, wherein the deposition current density is 5 mA cm -2 , and the time is 30 min. It can be seen from Figure 1 that in the pure ZnSO4 electrolyte, the deposited zinc metal has a chaotic, loose and irregular sheet structure, showing uneven deposition, and is easy to generate dendrites after long-term cycling. In the PPGAM+2 mol L -1The zinc metal deposited in the ZnSO4 electrolyte presents an array, compact and uniform round sheet structure, which is conducive to the uniform deposition of zinc metal, thereby realizing long cycle life of zinc ion battery.

[0054] Please refer to Figure 2 , Figure 2 is the cycle performance diagram of the half battery using pure ZnSO4 electrolyte and PPGAM+ZnSO4 electrolyte under different current densities in Example 3. By Figure 2 It can be seen that in the PPGAM+ZnSO4 electrolyte system, the electrode can be stably cycled for 800 hours at a current density of 5 mA cm -2 and a surface capacity of 2.5 mAh cm -2 , while the electrode of the pure zinc electrolyte system as a control sample can only be cycled for 98 h; in the PPGAM+ZnSO4 electrolyte system, the electrode can be stably cycled for 730 hours at a current density of 10 mA cm -2 and a surface capacity of 5 mAh cm -2 , while the electrode of the pure zinc electrolyte system as a control sample can only be cycled for 82 h. It can be seen that the half battery of the application still has excellent cycle performance at high current by using the above-mentioned electrolyte additive. This is because the glycerol ester as a hydrophobic functional group can prevent water molecules in the electrolyte from contacting the zinc anode interface, and at the same time, induce uniform deposition of zinc ions, thereby obtaining longer cycle life.

[0055] Example 3

[0056] High-performance phosphonate glycerol ester-based zinc ion battery electrolyte additive half-cell performance test:

[0057] The electrolyte in Example 2 was directly assembled into a Zn / / Cu half-symmetrical battery, and the electrode was 1 cm 2 , and the separator was glass fiber. When assembling the battery, the mass of the electrolyte dropped on the separator was 0.01g~0.03g.

[0058] Please refer to Figure 3 , Figure 3 is the cycle performance diagram of the half battery using pure ZnSO4 electrolyte and PPGAM+ZnSO4 electrolyte in Example 3. By Figure 3 It can be seen that in the PPGAM+ZnSO4 electrolyte system, the electrode can be stably cycled for 800 hours at a current density of 5 mA cm -2 and a surface capacity of 2.5 mAh cm -2The battery with the phosphonate glycerol-based electrolyte achieved a stable cycle life of 250 hours, while the control sample only cycled for 60 hours. This is because the phosphonate glycerol-based electrolyte additive induces uniform zinc ion deposition, stabilizes the zinc / electrolyte interface, and improves interfacial mass exchange, thus achieving a longer cycle life. Furthermore, the cycle efficiency during cycling shows that the battery using the phosphonate glycerol-based electrolyte has an average cycle efficiency as high as 99.79%, while the control sample only has an average cycle efficiency of 99.2%.

[0059] Please see Figure 4 , Figure 4 This is a charge-discharge curve diagram of a half-cell using pure ZnSO4 electrolyte and PPGAM+ZnSO4 electrolyte in Example 3. (The diagram is presented in the original text.) Figure 4 It can be seen that the overpotential of the battery using phosphonic acid glyceride-based additives is 54 mV, while the overpotential of the control sample is as high as 109 mV. This proves that phosphonic acid glyceride-based zinc-ion battery electrolyte additives can increase the nucleation sites on the zinc surface, reduce the overpotential of zinc, and help to achieve uniform zinc ion deposition. In addition, it can also improve the reversibility of the zinc metal redox process.

[0060] Example 4

[0061] High-performance phosphonic acid glyceride-based zinc-ion battery electrolyte additives: Full cell performance:

[0062] Using the electrolyte from Example 2, Zn / / (NH4)2V was directly assembled. 10 O 25 • 8H2O full cell, electrode size 1 cm 2 The separator is made of glass fiber. The mass of electrolyte added to the separator during battery assembly is 0.01g~0.03g.

[0063] Please see Figure 5 , Figure 5 This is a full-cell cycle performance graph using pure ZnSO4 electrolyte and PPGAM+ZnSO4 electrolyte in Example 4. Figure 5 It can be seen that in the PPGAM+ZnSO4 electrolyte system, the zinc metal electrode reacts with (NH4)2V 10 O 25 The 8H2O-assembled full battery still has 300 mAh g remaining after 800 cycles. -1 The above-mentioned high specific capacity is far higher than that of the pure zinc electrolyte system (100 mAh g). -1 This indicates that high-performance phosphonic acid glyceride-based zinc-ion battery electrolyte additives can improve the electrochemical performance of the entire battery.

[0064] Please see Figure 6 , Figure 6are full cell CV performance plots for Example 4 using pure ZnS04electrolyte and PPGAM + ZnS04electrolyte. By Figure 6 It can be seen that the corresponding redox peak current of the full cell assembled from the high-performance glycerol phosphonate-based zinc ion battery electrolyte additive is larger than that of the bare Zn battery, indicating that there are more active sites on the electrode in the glycerol phosphonate-based zinc ion battery electrolyte system, and the electrochemical reaction rate is faster.

[0065] The specific embodiments of the application described above do not constitute a limitation on the protection scope of the application. Any various other corresponding changes and modifications made according to the technical concept of the application should be included in the protection scope of the claims of the application.

Claims

1. The application of a phosphonic acid glyceride-based polymer as an additive in zinc-ion battery electrolytes, characterized in that, The phosphonic acid glyceride-based polymer has a mass percentage of 0.0001% to 0.1% in the zinc-ion battery electrolyte; The preparation method of the phosphonic acid glyceride-based polymer includes the following steps: A phosphonic acid monomer and a glycerol ester monomer are polymerized to obtain a phosphonic acid glycerol ester polymer; wherein the phosphonic acid monomer is ethylenephosphonic acid or cis-propenyphosphonic acid; wherein the glycerol ester monomer is glycidyl methacrylate; and the molar ratio of the phosphonic acid monomer to the glycerol ester monomer is 1:(0.1-10).

2. The application according to claim 1, characterized in that, An initiator is also added during the polymerization reaction; wherein, The initiator is at least one of ammonium persulfate and sodium persulfate; and / or, The amount of initiator added is 0.1-3% of the total mass of the phosphonic acid group monomer and the glycerol ester group monomer.

3. The application according to claim 1, characterized in that, The solvent used in the polymerization reaction is a mixture of water and propylene glycol methyl ether, and the volume ratio of water to propylene glycol methyl ether is (1~5):1; the total mass ratio of the phosphonic acid group monomer and the glycerol ester group monomer to the mixed solvent is 1g:(15~25)mL.

4. The application according to claim 1, characterized in that, The polymerization reaction is carried out at a temperature of 40~180 ℃ and for a time of 0.5 h~10 h.

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