A single-ion conductor gel polymer electrolyte and its preparation method and application

Abstract

The present invention relates to the technical field of magnesium battery, and particularly relates to a single-ion conductor gel polymer electrolyte, a preparation method thereof, and an application thereof in a magnesium battery. The composition of the single-ion conductor gel polymer electrolyte is a single-ion conductor polymer, a plasticizer, and an activator; wherein, the single-ion conductor polymer is one or several of polymers in which at least one H in the polymer main chain is replaced by a -MgX group, a -OMgX group, or a -R1MgX group; wherein, X is a halogen atom; R1 is selected from C1-C14 alkyl, C1-C14 alkoxy, C6-C18 aryl, or aryloxy. Compared with the prior art, the magnesium battery gel polymer electrolyte prepared by the present invention has the characteristics of high ion transference number, high ionic conductivity, wide electrochemical window, good compatibility with magnesium negative electrode, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium batteries, and specifically relates to a single-ion conductor gel polymer electrolyte, a preparation method thereof, and an application thereof in magnesium batteries. Background Art

[0002] Under the development requirements of global carbon peak and carbon neutrality, electrochemical energy storage technology has developed rapidly. Energy storage devices represented by lithium-ion batteries have been widely used in the fields of power batteries and large-scale energy storage. However, the current battery technology is far from perfect, and there are still problems such as high cost, low energy density, and poor safety. Magnesium-ion batteries have become an important choice for the next-generation batteries due to their high safety, low cost, and high volumetric energy density.

[0003] In the past ten-odd years, the liquid electrolytes used in magnesium batteries have developed rapidly. Grignard reagent electrolytes, organic boron-centered electrolytes, magnesium aluminum chloride complex electrolytes (MACC), and Mg(TFSI)2-based electrolytes have been developed, and they all have good compatibility with magnesium anodes. However, most of the solvents used in the above liquid electrolytes are ether solvents such as tetrahydrofuran and ethylene glycol dimethyl ether, which have safety hazards such as easy leakage, flammability, and explosiveness. Polymer electrolytes have received extensive attention due to their higher safety and excellent flexibility. However, the room-temperature ionic conductivities of current all-solid polymer electrolytes are all relatively low, far from reaching the application level. Gel polymer electrolytes are an effective way to commercialize magnesium-ion batteries because they combine high safety and high room-temperature ionic conductivity.

[0004] Currently, gel polymer electrolytes such as polyvinylidene fluoride (PVDF), polyethylene oxide (PEO), poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), and polytetrahydrofuran (PTHF) have been reported. However, due to problems such as poor compatibility with magnesium anodes, only a small part of them can perform reversible magnesium deposition and stripping. At the same time, most of the above gel polymer electrolyte systems are simple mixtures of linear polymers and magnesium salts, and anions and cations will move simultaneously under an electric field, resulting in a low transference number of magnesium ions, which is not conducive to the uniform deposition and extraction of magnesium. Therefore, there is an urgent need to develop a gel polymer electrolyte with good compatibility with magnesium anodes and a high transference number of magnesium ions in the current field of magnesium battery electrolytes. Summary of the Invention

[0005] In view of this, the present invention provides a single-ion conductor gel polymer electrolyte, a preparation method thereof, and an application thereof in magnesium batteries.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A single-ion conductor gel polymer electrolyte, which is composed of a single-ion conductor polymer, a plasticizer, and an activator. Among them, the single-ion conductor polymer is one or more of the polymers in which at least one H in the polymer backbone is replaced by a -MgX group, -OMgX group, or -R1MgX group. Among them, X is a halogen atom; R1 is selected from C1-C14 alkyl, C1-C14 alkoxy, C6-C18 aryl, or aryloxy.

[0008] The aryl includes phenyl, naphthyl, and anthracenyl, and the aryl can be substituted or unsubstituted; the aryloxy refers to the aryl as defined above bonded through an oxygen atom.

[0009] Preferably, the single-ion conductor polymer is one or more of the polymers in which at least one H in the polymer backbone is replaced by a -MgX group, -OMgX group, or -R1MgX group. Among them, X is a halogen atom; R1 is selected from C1-C6 alkyl, C1-C6 alkoxy, C6-C14 aryl, or aryloxy. The polymer backbone is one or a combination of polyether, polyolefin, polyester, polysiloxane, or polyamide; and the relative molecular mass of the polymer is 500-5,000,000. Preferably, the main chain of the polymer is polyether, polyolefin, and polysiloxane.

[0010] More preferably, the single-ion conductor polymer is preferably one or more of the following structures;

[0011]

[0012] In the above structures, n = 10-10,000.

[0013] The plasticizer is one or more of ether compounds, aromatic compounds, and ionic liquids. Among them, the plasticizer is 10%-500% relative to the polymer by mass percentage, preferably 50%-200%.

[0014] Among them, the ether compounds are selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, 1,4-dioxane, and polyethylene glycol dimethyl ether. Preferably, it is one or a mixture of tetrahydrofuran, ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, or tetraethylene glycol dimethyl ether.

[0015] The aromatic compounds are selected from one or more of toluene, pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2,6-dichloropyridine, 2-aminopyridine, and N-methylimidazole. Preferably, it is one or a mixture of toluene, pyridine, or 2-methylpyridine.

[0016] The ionic liquid includes one or more of imidazole-based ionic liquids, piperidine-based ionic liquids, and pyrrole-based ionic liquids. The imidazole-based ionic liquid is selected from one or more of 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; the piperidine-based ionic liquid is selected from N-butyl-N-methylpiperidinium bis(trifluoromethanesulfonyl)imide; the pyrrole-based ionic liquid is selected from N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide. It is preferably an imidazole-based ionic liquid or a piperidine-based ionic liquid.

[0017] The activator is a Lewis acid; wherein, the molar ratio of the activator to the magnesium atoms in the polymer is 0.2 - 3, preferably 0.5 - 1.

[0018] The Lewis acid is an anhydrous aluminum salt composed of aluminum and a coordination group.

[0019] The coordination group is selected from halogen, alkyl, alkoxy, phenyl, etc., preferably halogen or alkyl.

[0020] A preparation method of a single-ion conductor polymer electrolyte: dissolving one or several single-ion conductor polymers in a low-boiling solvent to form a homogeneous solution; adding the activator to the above solution, and obtaining an intermediate solution after reaction; processing the intermediate solution by solution casting, and obtaining a polymer electrolyte membrane after drying; uniformly infiltrating the above polymer electrolyte membrane with a certain amount of plasticizer to obtain the single-ion conductor gel polymer electrolyte.

[0021] Preferably, the entire preparation process is carried out in a glove box with less than 0.1 ppm of water and oxygen during the above preparation process.

[0022] The low-boiling solvent is one or a mixture of several of tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dichloromethane, or acetonitrile. It is preferably a mixture of one or two of tetrahydrofuran or ethylene glycol dimethyl ether.

[0023] An application of an electrolyte, the application of the electrolyte in the preparation of a magnesium battery.

[0024] A magnesium battery includes the single-ion conductor gel polymer electrolyte described above.

[0025] The magnesium battery is a primary magnesium battery or a secondary magnesium battery.

[0026] The beneficial effects of the present invention are as follows:

[0027] The single-ion conductor gel polymer electrolyte prepared by the present invention is added with a specific single-ion conductor polymer, making it have the characteristics of high magnesium ion transference number, high ionic conductivity, wide electrochemical window, and good compatibility with magnesium negative electrode. In addition, compared with traditional liquid electrolytes, this gel polymer electrolyte can effectively reduce the use of low-boiling-point solvents, avoid the leakage of electrolytes, and has good mechanical properties, greatly improving the safety of the battery. Description of the Drawings

[0028] Figure 1 is the optical photograph of the gel polymer electrolyte membrane in Example 1 provided by the embodiment of the present invention;

[0029] Figure 2 is the impedance spectrum of the gel polymer electrolyte membrane in Example 1 provided by the embodiment of the present invention;

[0030] Figure 3 is the LSV curve of the Ti / / Mg battery assembled with the gel polymer electrolyte membrane in Example 1 provided by the embodiment of the present invention;

[0031] Figure 4 is the polarization curve of the Mg / / Mg symmetric battery assembled with the gel polymer electrolyte membrane in Example 1 provided by the embodiment of the present invention;

[0032] Figure 5 is the morphology of the magnesium sheet surface after long-cycle polarization of the Mg / / Mg symmetric battery assembled with the gel polymer electrolyte membrane in Example 1 provided by the embodiment of the present invention;

[0033] Figure 6 is the transference number test result of the gel polymer electrolyte in Example 2 provided by the embodiment of the present invention;

[0034] Figure 7 is the LSV curve of the Ti / / Mg battery assembled with the gel polymer electrolyte in Example 3 provided by the embodiment of the present invention;

[0035] Figure 8 is the CV curve of the ss / / Mg battery assembled with the gel polymer electrolyte in Example 3 provided by the embodiment of the present invention;

[0036] Figure 9 is the long-cycle curve of the Mo6S8 / / Mg battery assembled with the gel polymer electrolyte in Example 3 provided by the embodiment of the present invention at 30 °C;

[0037] Figure 10 is the charge-discharge curve of the Mo6S8 / / Mg battery assembled with the gel polymer electrolyte in Example 3 provided by the embodiment of the present invention at 30 °C with different cycles;

[0038] Figure 11It is the long - cycle curve of the Mo6S8 / / Mg battery assembled with the gel polymer electrolyte in Example 3 provided by the embodiments of the present invention at 80 °C;

[0039] Figure 12 It is the LSV curve of the Ti / / Mg battery assembled with 0.4 mol / L APC electrolyte in Comparative Example 1 provided by the embodiments of the present invention;

[0040] Figure 13 It is the test result of the transference number of the Mg / / Mg battery assembled with 0.4 mol / L APC electrolyte in Comparative Example 1 provided by the embodiments of the present invention;

[0041] Figure 14 It is the first charge - discharge curve of the Mo6S8 / / Mg battery assembled with 0.4 mol / L APC electrolyte in Comparative Example 1 provided by the embodiments of the present invention at 60 °C. Detailed implementation manners

[0042] The following further elaborates on the present invention through specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0043] In order to solve the problems that the existing magnesium battery system uses liquid electrolytes, which are prone to volatilization, leakage, and have safety hazards such as flammability and explosiveness, the present invention uses a polymer containing a magnesium source to obtain a single - ion conductor gel polymer electrolyte through a solution casting method to improve the electrochemical and safety performance of the existing magnesium battery. 1) The test method for the ionic conductivity of the gel polymer electrolyte is as follows:

[0044] Using a single - ion conductor gel polymer membrane as the electrolyte, stainless - steel sheets are used for both the positive and negative electrodes to assemble a 2032 coin - type battery. The electrochemical impedance spectroscopy (EIS) is tested on an electrochemical workstation with an amplitude of 10 mV and a frequency range of 7 MHz - 0.1 Hz. The ionic conductivity can be calculated through formula 1.

[0045]

[0046] σ is the required ionic conductivity, d is the thickness of the electrolyte between the two steel sheets, S is the area of the stainless - steel electrode, and R is the impedance value obtained from the Nyquist plot of the impedance spectrum.

[0047] 2) The test method for the electrochemical window is as follows:

[0048] Using a single-ion conductor gel polymer membrane as the electrolyte, a titanium foil as the working electrode, and a polished magnesium sheet as the counter electrode and reference electrode, a 2032 button cell was assembled and linear sweep voltammetry (LSV) tests were carried out at a scan rate of 1 mV / s and a voltage range of 0 to 5 V.

[0049] 3) The method for testing the magnesium ion transference number is as follows:

[0050] A Mg / / Mg symmetric cell was assembled using a polished magnesium sheet and a gel electrolyte membrane, and the impedance of the cell before and after polarization at a given bias voltage (50 mV) was tested. The test frequency was 7 MHz - 0.1 Hz, and the magnesium ion transference number could be calculated by Equation 2.

[0051]

[0052] Where is the magnesium ion transference number, I0 and I s are the initial current and the current at equilibrium, respectively, R0 and R s are the impedances before and after polarization, respectively, and V is the applied polarization voltage (50 mV).

[0053] The magnesium-containing polymers in the following examples can be obtained either by modifying existing polymers (J. Org. Chem. 1987, 52, 4644 - 4645) or by polymerizing magnesium-containing monomers.

[0054] Example 1

[0055] In a glove box filled with argon, 10 g of Polymer I was dissolved in 100 mL of anhydrous tetrahydrofuran and stirred at room temperature until completely dissolved. Then, 1 mL of 0.5 mol / L AlCl3 solution was added dropwise thereto, and the reaction was continued by stirring at room temperature for 2 h. Then, the reaction solution was cast into a film and dried on a hot stage in the glove box to obtain a single-ion conductor polymer electrolyte membrane. The membrane was cut into discs with a diameter of 16.5 mm, weighed, and then 100 wt% of triethylene glycol dimethyl ether based on the mass of Polymer I was added and thoroughly infiltrated to obtain a single-ion conductor gel polymer electrolyte membrane ( Figure 1 ). As Figure 1 shown, the gel polymer electrolyte membrane can be self-supporting and has high transparency. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 button cell was assembled to measure its electrochemical performance.

[0056] The thickness of the gel polymer electrolyte membrane was measured to be 100 μm, and the impedance spectrum at 25 °C is as Figure 2 shown. The room-temperature ionic conductivity was calculated to be 2.5×10 -4 S / cm, and the electrochemical oxidation window was 3.0 V ( Figure 3), the magnesium ion transference number is 0.80. In addition, the assembled magnesium-magnesium symmetric battery has excellent long-cycle polarization performance at a current density of 0.2 mA / cm 2 , with a polarization voltage of about 0.2 V, which is comparable to that of traditional liquid batteries ( Figure 4 ). After disassembling the cycled battery, the surface of the magnesium sheet is relatively uniform and dense, and no obvious magnesium dendrites are formed (see Figure 5 ).

[0057]

[0058] Polymer I, n is 1000

[0059] Example 2

[0060] In a glove box filled with argon, 10 g of Polymer II was dissolved in 100 mL of anhydrous tetrahydrofuran, stirred at room temperature until completely dissolved, then 1 mL of 0.5 mol / L AlCl3 solution was added dropwise thereto, and the reaction was continued to stir at room temperature for 2 h. Then the reaction solution was cast into a film and dried on the hot stage of the glove box to obtain a single-ion conductor polymer electrolyte membrane. The membrane was cut into circular pieces with a diameter of 16.5 mm, weighed, and 100 wt% of triethylene glycol dimethyl ether based on the mass of Polymer II was added and fully infiltrated to obtain a single-ion conductor gel polymer electrolyte. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 coin cell was assembled to measure its electrochemical performance.

[0061] The measured thickness of the gel polymer electrolyte membrane is 100 μm, the room-temperature ionic conductivity at 25 °C is 3.0×10 - 4 S / cm, the electrochemical oxidation window is 3.2 V, and the magnesium ion transference number is 0.85 ( Figure 6 ).

[0062]

[0063] Polymer II, n is 1000

[0064] Example 3

[0065] In a glove box filled with argon, 10 g of Polymer III was dissolved in 100 mL of anhydrous tetrahydrofuran and stirred at room temperature until completely dissolved. Then, 1 mL of 0.5 mol / L AlCl3 solution was added dropwise thereto, and the reaction was continued by stirring for 2 h at room temperature. Subsequently, the reaction solution was cast into a film and dried on the hot stage in the glove box to obtain a single-ion conductor polymer electrolyte membrane. The membrane was cut into circular pieces with a diameter of 16.5 mm, weighed, and then added with triethylene glycol dimethyl ether at 100 wt% of the mass of Polymer III and fully infiltrated to obtain a single-ion conductor gel polymer electrolyte. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 coin cell was assembled to measure its electrochemical performance.

[0066] The thickness of the gel polymer electrolyte membrane measured with a micrometer was 100 μm, and the room-temperature ionic conductivity at 25 °C was 2.8×10 -4 S / cm, the electrochemical oxidation window was 4.0 V ( Figure 7 ), and the magnesium ion transference number was 0.82. As Figure 8 shown, the gel electrolyte membrane exhibited good ability for reversible deposition / dissolution of magnesium. A battery assembled with Mo6S8 as the battery positive electrode, the single-ion conductor gel polymer membrane as the electrolyte, and a magnesium sheet as the negative electrode had excellent charge-discharge performance. As Figure 9 shown, the battery could be stably charged and discharged more than 200 cycles at 30 °C, and the capacity retention rate was 92%. Figure 10 The charge-discharge curves corresponding to different cycles were shown in Figure 11 . From the curves, we found that the curves at different cycles maintained a stable charge-discharge plateau, indicating the excellent cycle performance of the battery. In addition, we also investigated the cycle performance of the battery at a high temperature of 80 °C. As Figure 11 shown, the battery could still be cycled more than 100 times at a high temperature of 80 °C, and the capacity retention rate was 78%.

[0067]

[0068] Polymer III, n = 1000

[0069] Example 4

[0070] In a glove box filled with argon, 10 g of Polymer IV was dissolved in 100 mL of anhydrous ethylene glycol dimethyl ether and stirred at room temperature until completely dissolved. Then, 1 mL of 0.5 mol / L AlCl3 solution was added dropwise thereto, and the reaction was continued by stirring at room temperature for 2 h. Subsequently, the reaction solution was cast into a film and dried on the hot stage of the glove box to obtain a single-ion conductor polymer electrolyte membrane. The membrane was cut into discs with a diameter of 16.5 mm, weighed, and 100 wt% of triethylene glycol dimethyl ether based on the mass of Polymer IV was added and fully infiltrated to obtain a single-ion conductor gel polymer electrolyte. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 coin cell was assembled to measure its electrochemical performance.

[0071] The thickness of the gel polymer electrolyte membrane was measured to be 80 μm, and the room temperature ionic conductivity at 25 °C was 3.5×10 -4 S / cm, the electrochemical oxidation window was 3.2 V, and the magnesium ion transference number was 0.86.

[0072]

[0073] Polymer IV, n = 1000

[0074] Example 5

[0075] In a glove box filled with argon, 10 g of Polymer V was dissolved in 100 mL of anhydrous ethylene glycol dimethyl ether and stirred at room temperature until completely dissolved. Then, 1 mL of 0.5 mol / L AlCl3 solution was added dropwise thereto, and the reaction was continued by stirring at room temperature for 2 h. Subsequently, the reaction solution was cast into a film and dried on the hot stage of the glove box to obtain a single-ion conductor polymer electrolyte membrane. The membrane was cut into discs with a diameter of 16.5 mm, weighed, and 100 wt% of triethylene glycol dimethyl ether based on the mass of Polymer V was added and fully infiltrated to obtain a single-ion conductor gel polymer electrolyte. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 coin cell was assembled to measure its electrochemical performance.

[0076] The thickness of the gel polymer electrolyte membrane was measured to be 80 μm, and the room temperature ionic conductivity at 25 °C was 3.3×10 -4 S / cm, the electrochemical oxidation window was 4.4 V, and the magnesium ion transference number was 0.88.

[0077]

[0078] Polymer V, n = 1000

[0079] Example 6

[0080] In a glove box filled with argon, 10 g of polymer VI was dissolved in 100 mL of anhydrous ethylene glycol dimethyl ether, stirred at room temperature until completely dissolved, then 1 mL of 0.5 mol / L AlCl3 solution was added dropwise thereto, and the reaction was continued by stirring at room temperature for 2 h. Then the reaction solution was cast into a film and dried on a hot stage in the glove box to obtain a single-ion conductor polymer electrolyte membrane. The membrane was cut into discs with a diameter of 16.5 mm, weighed, and 100 wt% of triethylene glycol dimethyl ether based on the mass of polymer VI was added and fully infiltrated to obtain a single-ion conductor gel polymer electrolyte. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 button cell was assembled to measure its electrochemical performance.

[0081] The thickness of the gel polymer electrolyte membrane was measured to be 120 μm, and the room temperature ionic conductivity at 25 °C was 2.1×10 - 4 S / cm, the electrochemical oxidation window was 3.0 V, and the magnesium ion transference number was 0.70.

[0082]

[0083] Polymer VI, n = 2000

[0084] Example 7

[0085] In a glove box filled with argon, 10 g of polymer VII was dissolved in 100 mL of anhydrous tetrahydrofuran, stirred at room temperature until completely dissolved, then 1 mL of 0.5 mol / L AlCl3 solution was added dropwise thereto, and the reaction was continued by stirring at room temperature for 2 h. Then the reaction solution was cast into a film and dried on a hot stage in the glove box to obtain a single-ion conductor polymer electrolyte membrane. The membrane was cut into discs with a diameter of 16.5 mm, weighed, and 100 wt% of triethylene glycol dimethyl ether based on the mass of polymer VII was added and fully infiltrated to obtain a single-ion conductor gel polymer electrolyte. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 button cell was assembled to measure its electrochemical performance.

[0086] The thickness of the gel polymer electrolyte membrane was measured to be 100 μm, and the room temperature ionic conductivity at 25 °C was 2.5×10 - 4 S / cm, the electrochemical oxidation window was 3.5 V, and the magnesium ion transference number was 0.75.

[0087]

[0088] Polymer VII, n = 1000

[0089] Example 8

[0090] In a glove box filled with argon, 10 g of Polymer VIII was dissolved in 100 mL of anhydrous tetrahydrofuran, and stirred at room temperature until completely dissolved. Then, 1 mL of 0.5 mol / L AlCl3 solution was added dropwise thereto, and the reaction was continued by stirring at room temperature for 2 h. Then, the reaction solution was cast into a film, and after drying on the hot stage of the glove box, a single-ion conductor polymer electrolyte membrane was obtained. The membrane was cut into circular pieces with a diameter of 16.5 mm, weighed, and 100 wt% of triethylene glycol dimethyl ether based on the mass of Polymer VIII was added and fully infiltrated to obtain a single-ion conductor gel polymer electrolyte. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 button battery was assembled to measure its electrochemical performance.

[0091] The measured thickness of the gel polymer electrolyte membrane was 80 μm, the room-temperature ionic conductivity at 25 °C was 2.0×10 -4 S / cm, the electrochemical oxidation window was 3.8 V, and the magnesium ion transference number was 0.77.

[0092]

[0093] Polymer VIII, m is 500, n is 500

[0094] Example 9

[0095] In a glove box filled with argon, 10 g of Polymer IX was dissolved in 100 mL of anhydrous tetrahydrofuran, and stirred at room temperature until completely dissolved. Then, 1 mL of 0.5 mol / L AlCl3 solution was added dropwise thereto, and the reaction was continued by stirring at room temperature for 2 h. Then, the reaction solution was cast into a film, and after drying on the hot stage of the glove box, a single-ion conductor polymer electrolyte membrane was obtained. The membrane was cut into circular pieces with a diameter of 16.5 mm, weighed, and 100 wt% of triethylene glycol dimethyl ether based on the mass of Polymer IX was added and fully infiltrated to obtain a single-ion conductor gel polymer electrolyte. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 button battery was assembled to measure its electrochemical performance.

[0096] The measured thickness of the gel polymer electrolyte membrane was 100 μm, the room-temperature ionic conductivity at 25 °C was 2.3×10 - 4 S / cm, the electrochemical oxidation window was 2.8 V, and the magnesium ion transference number was 0.81.

[0097]

[0098] Polymer IX, n is 1000

[0099] Example 10

[0100] In a glove box filled with argon, 10 g of polymer X was dissolved in 100 mL of anhydrous tetrahydrofuran and stirred at room temperature until completely dissolved. Then, 1 mL of 0.5 mol / L AlCl3 solution was added dropwise thereto, and the reaction was continued by stirring at room temperature for 2 h. Subsequently, the reaction solution was cast into a film and dried on a hot stage in the glove box to obtain a single-ion conductor polymer electrolyte membrane. The membrane was cut into circular pieces with a diameter of 16.5 mm, weighed, and then 100 wt% of tetraethylene glycol dimethyl ether based on the mass of polymer X was added and fully infiltrated to obtain a single-ion conductor gel polymer electrolyte. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 coin cell was assembled to measure its electrochemical performance.

[0101] The measured thickness of the gel polymer electrolyte membrane was 100 μm, the room-temperature ionic conductivity at 25 °C was 1.5×10 - 4 S / cm, the electrochemical oxidation window was 3.0 V, and the magnesium ion transference number was 0.82.

[0102]

[0103] Polymer X, n is 1000

[0104] Example 11

[0105] In a glove box filled with argon, 10 g of polymer XI was dissolved in 100 mL of anhydrous tetrahydrofuran and stirred at room temperature until completely dissolved. Then, 1 mL of 0.5 mol / L triethylaluminum solution was added dropwise thereto, and the reaction was continued by stirring at room temperature for 2 h. Subsequently, the reaction solution was cast into a film and dried on a hot stage in the glove box to obtain a single-ion conductor polymer electrolyte membrane. The membrane was cut into circular pieces with a diameter of 16.5 mm, weighed, and then 100 wt% of tetraethylene glycol dimethyl ether based on the mass of polymer XI was added and fully infiltrated to obtain a single-ion conductor gel polymer electrolyte. The thickness of the gel electrolyte was measured with a micrometer, and then a 2032 coin cell was assembled to measure its electrochemical performance.

[0106] The measured thickness of the gel polymer electrolyte membrane was 100 μm, the room-temperature ionic conductivity at 25 °C was 2.4×10 - 4 S / cm, the electrochemical oxidation window was 3.2 V, and the magnesium ion transference number was 0.85.

[0107]

[0108] Polymer XI, n is 1000

[0109] As can be seen from the above Examples 1-11, the present invention uses a magnesium source-containing polymer, which fixes most anions on the polymer backbone, restricts their movement, and thus has a high magnesium ion transference number. In addition, due to the addition of a plasticizer, the obtained gel polymer electrolyte has a high ionic conductivity. Compared with traditional liquid magnesium electrolytes, since the amount of solvent is reduced and its activity is restricted, this gel polymer electrolyte also has advantages such as a wide electrochemical window and good compatibility with magnesium anodes.

[0110] Comparative Example 1

[0111] In a glove box filled with argon, a 0.4 mol / L APC solution (containing 0.4 mol / L phenylmagnesium chloride and 0.2 mol / L AlCl3, with anhydrous tetrahydrofuran as the solvent) was prepared. Then, glass fiber (GF / A, 180 μm) was used as the separator, 100 μL of 0.4 mol / L APC was added as the electrolyte, and the corresponding 2032 button battery was assembled to measure its electrochemical performance.

[0112] The room temperature ionic conductivity measured at 25 °C was 5.2×10 -4 S / cm, the electrochemical oxidation window was 2.3 V( Figure 12 ), and the magnesium ion transference number was 0.32( Figure 13 ). We assembled a magnesium metal battery with Mo6S8 as the positive electrode and 0.4 mol / L APC as the electrolyte and investigated its charge-discharge performance at 60 °C. As Figure 14 shown, overcharging occurred in the first cycle of the battery, and charge-discharge cycling could not be carried out.

[0113] Table 1

[0114]

[0115] As can be seen from the performance comparison between the examples of the present invention and the comparative examples in Table 1, this gel polymer electrolyte has an ionic conductivity comparable to that of traditional liquid electrolytes, but has a higher magnesium ion transference number and a wider electrochemical window, which is beneficial to the uniform deposition and extraction of magnesium, inhibits the formation of magnesium dendrites, and improves the cycle stability of the battery.

Claims

1. A single-ion conductor gel polymer electrolyte, characterized in that: The single-ion conductor gel polymer electrolyte is composed of a single-ion conductor polymer, a plasticizer, and an activator; wherein, the single-ion conductor polymer is one or more of polymers in which at least one H in the polymer main chain is replaced by a -MgX group, -OMgX group, or -R1MgX group; wherein, X is a halogen atom; R1 is selected from C1-C14 alkyl, C1-C14 alkoxy, C6-C18 aryl, or aryloxy.

2. The single-ion conductor gel polymer electrolyte according to claim 1, characterized in that: The single-ion conductor polymer is one or more of polymers in which at least one H in the polymer main chain is replaced by a -MgX group, -OMgX group, or -R1MgX group; wherein, X is a halogen atom; R1 is selected from C1-C6 alkyl, C1-C6 alkoxy, C6-C14 aryl, or aryloxy.

3. The single-ion conductor gel polymer electrolyte according to claim 1, characterized in that: The polymer main chain is one or a combination of several of polyethers, polyolefins, polyesters, polysiloxanes, or polyamides; and, the relative molecular mass of the polymer is 500 - 5 million.

4. The single-ion conductor gel polymer electrolyte according to claim 1, characterized in that: The plasticizer is one or more of ether compounds, aromatic compounds, and ionic liquids; wherein, the plasticizer is 10% - 500% relative to the polymer by mass percentage.

5. The single-ion conductor gel polymer electrolyte according to claim 1, characterized in that: The activator is a Lewis acid; wherein, the molar ratio of the activator to the magnesium atoms in the polymer is 0.2 - 3.

6. The single-ion conductor gel polymer electrolyte according to claim 5, characterized in that: The Lewis acid is an anhydrous aluminum salt composed of aluminum and a coordination group.

7. A method for preparing the single-ion conductor gel polymer electrolyte according to claim 1, characterized in that: Dissolve one or more single-ion conductor polymers in a low-boiling solvent to form a homogeneous solution; add the activator to the above solution, and obtain an intermediate solution after reaction; process the intermediate solution by solution casting, and obtain a polymer electrolyte membrane after drying; uniformly infiltrate the above polymer electrolyte membrane with the plasticizer to obtain the single-ion conductor gel polymer electrolyte.

8. Use of the electrolyte according to claim 1, characterized in that: Application of the electrolyte in the preparation of magnesium batteries.

9. A magnesium battery, characterized in that: Comprising the single-ion conductor polymer electrolyte described in Claim 1.

Images