Flame-retardant organic ionic liquid proton electrolyte, preparation method thereof and proton half-cell

Abstract

The invention relates to the technical field of battery flame retardance, and discloses a flame-retardant organic ionic liquid proton electrolyte, a preparation method thereof and a proton half-battery. The flame-retardant organic ionic liquid proton electrolyte comprises an organic ionic liquid proton electrolyte and an organic phosphorus-based flame retardant, the organic ionic liquid proton electrolyte contains sulfolane, bis (trifluoromethylsulfonyl) imide and 1-methyl-1, 2, 4-triazole, and the molar ratio of the bis (trifluoromethylsulfonyl) imide to the 1-methyl-1, 2, 4-triazole is (0.2-0.4): 1. The flame-retardant organic ionic liquid proton electrolyte disclosed by the invention has a good flame-retardant characteristic, and the prepared molybdenum trioxide proton half-cell has the characteristics of high electrochemical stability, good conductivity, strong electrochemical storage capacity and the like, so that the safety of the proton cell under the condition of high temperature or open fire can be greatly improved; and safety accidents are prevented, and the method plays an important role in practical application of the proton battery.

Description

Technical Field

[0001] The present invention relates to the technical field of battery flame retardancy, and particularly relates to a flame-retardant organic ionic liquid proton electrolyte, a preparation method thereof, and a proton half-cell. Background Art

[0002] Proton batteries have received extensive attention from researchers in the battery field due to their characteristics such as fast charge and discharge speed, high energy density, and long cycle life. As an important component of proton batteries, the proton electrolyte transports charges between the positive and negative electrodes of the battery, and has a crucial impact on the specific capacity, operating temperature range, cycle efficiency, and safety performance of the battery. Among them, the electrolyte is the main combustible substance that causes battery safety accidents. Once the battery encounters extreme situations such as short circuit and high heat, the electrolyte is extremely easy to catch fire, thereby triggering safety accidents. Although the battery is equipped with a safety valve and various protection measures, it is still impossible to completely avoid the leakage, combustion, or even explosion of the electrolyte. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problem that the existing organic ionic liquid proton electrolyte is prone to thermal runaway under high temperature or open flame conditions, thereby triggering a series of safety accidents, and to provide a flame-retardant organic ionic liquid proton electrolyte, a preparation method thereof, and a proton half-cell. The flame-retardant organic ionic liquid proton electrolyte described in the present invention has good flame retardant properties, does not affect the normal operation of the proton half-cell, and the prepared proton half-cell has characteristics such as high electrochemical stability, good conductivity, and strong electrochemical storage capacity, which can greatly improve the safety of proton batteries under high temperature or open flame conditions and has an important role in the practical application of proton batteries.

[0004] In order to achieve the above purpose, on the one hand, the present invention provides a flame-retardant organic ionic liquid proton electrolyte, which comprises an organic ionic liquid proton electrolyte and an organophosphorus-based flame retardant. The organic ionic liquid proton electrolyte contains sulfolane, bis(trifluoromethylsulfonyl)imide, and 1-methyl-1,2,4-triazole. Among them, the molar ratio of bis(trifluoromethylsulfonyl)imide to 1-methyl-1,2,4-triazole is 0.2-0.4:1.

[0005] Preferably, the molar ratio of bis(trifluoromethylsulfonyl)imide to 1-methyl-1,2,4-triazole is 0.22-0.38:1.

[0006] Preferably, the volume ratio of the sum of the volumes of sulfolane, bis(trifluoromethylsulfonyl)imide, and 1-methyl-1,2,4-triazole to the organophosphorus-based flame retardant is 5-15:1.

[0007] Preferably, the volume ratio of the sum of the volumes of sulfolane, bis(trifluoromethylsulfonyl)imide, and 1-methyl-1,2,4-triazole to the volume of the organophosphorus-based flame retardant is 8-10:1.

[0008] Preferably, the organophosphorus-based flame retardant is at least one of trimethyl phosphate, triethyl phosphate, ethoxy(pentafluoro)cyclotriphosphazene, hexafluorocyclotriphosphazene, and phosphite.

[0009] Preferably, the molar volume ratio of bis(trifluoromethylsulfonyl)imide to sulfolane is 0.75-3 mol:1 L.

[0010] Preferably, the molar volume ratio of bis(trifluoromethylsulfonyl)imide to sulfolane is 1-2 mol:1 L.

[0011] The second aspect of the present invention provides a method for preparing the above-mentioned flame-retardant organic ionic liquid proton electrolyte, and the method includes the following steps:

[0012] (1) Heat sulfolane to 50-70 °C, and then, under an inert atmosphere, sequentially add bis(trifluoromethylsulfonyl)imide and 1-methyl-1,2,4-triazole and mix and dissolve them to obtain an organic ionic liquid proton electrolyte;

[0013] (2) Mix the organic ionic liquid proton electrolyte with the organophosphorus-based flame retardant and ultrasonicate, and then let it stand.

[0014] The third aspect of the present invention provides a proton half-cell, which includes a working electrode, a counter electrode, a reference electrode, a separator, and the above-mentioned flame-retardant organic ionic liquid proton electrolyte.

[0015] Preferably, the working electrode is a molybdenum trioxide electrode.

[0016] Preferably, the counter electrode is an activated carbon electrode.

[0017] Preferably, the reference electrode is a silver / silver ion electrode.

[0018] Preferably, the separator is a glass fiber membrane.

[0019] According to the technical solution of the present invention, by introducing an organophosphorus-based flame retardant into the organic ionic liquid proton electrolyte, the organic ionic liquid proton electrolyte has strong flame retardant properties, and the prepared proton half-cell has characteristics such as high electrochemical stability, good electrical conductivity, and strong electrochemical storage capacity. The flame retardant mechanism of the organophosphorus-based flame retardant is mainly that the flame retardant releases phosphorus-containing oxyacids when heated. On the one hand, these phosphorus-containing oxyacids can capture hydrogen radicals or hydroxyl radicals decomposed from the electrolyte when heated, preventing the chain reaction of these radicals, so that the organic electrolyte is difficult to continue burning, achieving the flame retardant effect; on the other hand, it can promote the coke layer formed by the dehydration and carbonization of the electrolyte and diaphragm material to be graphite-like, which can block the contact between the internal electrolyte and diaphragm material and oxygen. The formed coke layer has poor thermal conductivity, isolates the polymer from the heat source, and slows down the thermal decomposition, thus playing a flame retardant role. The flame retardant organic ionic liquid proton electrolyte of the present invention can greatly improve the safety of proton batteries under high temperature or open flame conditions, prevent the occurrence of safety accidents, and has an important role in the practical application of proton half-cells. Description of the Drawings

[0020] Figure 1 It is a combustion state diagram of the original glass fiber diaphragm when ignited by an open flame;

[0021] Figure 2 It is a combustion state diagram of the glass fiber diaphragm after being infiltrated with the electrolyte prepared in Comparative Example 4 and then removing the ignition source when ignited by an open flame;

[0022] Figure 3 It is a combustion state diagram of the glass fiber diaphragm after being infiltrated with the flame retardant organic ionic liquid proton electrolytes prepared in Example 1, Example 6, and Comparative Example 1 and then removing the ignition source when ignited by an open flame;

[0023] Figure 4 It is an electrochemical window diagram of the flame retardant organic ionic liquid proton electrolytes prepared in Example 1, Example 6, and Comparative Example 1;

[0024] Figure 5 It is a cyclic voltammogram of the molybdenum trioxide proton half-cell prepared in Example 1;

[0025] Figure 6 It is a cyclic voltammogram of the molybdenum trioxide proton half-cell prepared in Example 6;

[0026] Figure 7 It is a cyclic voltammogram of the molybdenum trioxide proton half-cell prepared in Comparative Example 1;

[0027] Figure 8 It is an electrochemical impedance spectrum of the molybdenum trioxide proton half-cells prepared in Example 1, Example 6, and Comparative Example 1;

[0028] Figure 9The long - cycle specific capacity performance graph of the molybdenum trioxide proton half - cell prepared in Example 1 at a current density of 1 Ag -1 ;

[0029] Figure 10 The long - cycle specific capacity performance graph of the molybdenum trioxide proton half - cell prepared in Example 6 at a current density of 1 Ag -1 ;

[0030] Figure 11 The long - cycle specific capacity performance graph of the molybdenum trioxide proton half - cell prepared in Comparative Example 1 at a current density of 1 Ag -1 ; Detailed Embodiments

[0031] The following details the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for the purpose of illustrating and explaining the present invention and are not intended to limit the present invention.

[0032] The endpoints and any values disclosed in the ranges herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered specifically disclosed herein.

[0033] The flame - retardant organic ionic liquid proton electrolyte described in the present invention comprises an organic ionic liquid proton electrolyte and an organic phosphorus - based flame retardant. The organic ionic liquid proton electrolyte contains sulfolane, bis(trifluoromethylsulfonyl)imide, and 1 - methyl - 1,2,4 - triazole. Among them, the molar ratio of bis(trifluoromethylsulfonyl)imide to 1 - methyl - 1,2,4 - triazole is 0.2 - 0.4:1.

[0034] In a preferred case, the molar ratio of bis(trifluoromethylsulfonyl)imide to 1 - methyl - 1,2,4 - triazole is 0.22 - 0.38:1; further preferably, the molar ratio of bis(trifluoromethylsulfonyl)imide to 1 - methyl - 1,2,4 - triazole is 0.25 - 0.35:1. Specifically, the molar ratio of bis(trifluoromethylsulfonyl)imide to 1 - methyl - 1,2,4 - triazole can be 0.25:1, 0.26:1, 0.27:1, 0.28:1, 0.29:1, 0.3:1, 0.31:1, 0.32:1, 0.33:1, 0.34:1, or 0.35:1.

[0035] In the flame-retardant organic ionic liquid proton electrolyte, the molar volume ratio of bis(trifluoromethylsulfonyl)imide to sulfolane can be 0.75 - 3 mol : 1 L, preferably 1 - 2 mol : 1 L, and more preferably 1.3 - 1.7 mol : 1 L. Specifically, the molar volume ratio of bis(trifluoromethylsulfonyl)imide to sulfolane can be 1.3 mol : 1 L, 1.4 mol : 1 L, 1.5 mol : 1 L, 1.6 mol : 1 L, or 1.7 mol : 1 L.

[0036] In the flame-retardant organic ionic liquid proton electrolyte, the volume ratio of the sum of the volumes of sulfolane, bis(trifluoromethylsulfonyl)imide, and 1-methyl-1,2,4-triazole to the volume of the organophosphorus-based flame retardant can be 5 - 15 : 1, preferably 8 - 10 : 1, and more preferably 8.5 - 9.5 : 1. When the volume ratio of the sum of the volumes of sulfolane, bis(trifluoromethylsulfonyl)imide, and 1-methyl-1,2,4-triazole to the volume of the organophosphorus-based flame retardant is within the above preferred range, the prepared flame-retardant organic ionic liquid proton electrolyte has strong flame-retardant properties.

[0037] In the present invention, sulfolane, bis(trifluoromethylsulfonyl)imide, and 1-methyl-1,2,4-triazole can each be commercially available products or prepared by conventional methods in the art.

[0038] In the flame-retardant organic ionic liquid proton electrolyte, there is no particular limitation on the type of the organophosphorus-based flame retardant, and various organophosphorus-based flame retardants commonly used in the art can be used. Preferably, the organophosphorus-based flame retardant is at least one of trimethyl phosphate, triethyl phosphate, ethoxy(pentafluoro)cyclotriphosphazene, hexafluorocyclotriphosphazene, and phosphite. In the most preferred embodiment, the organophosphorus-based flame retardant is trimethyl phosphate. When the organophosphorus-based flame retardant is trimethyl phosphate, the prepared proton half-cell has good comprehensive performance.

[0039] In a more preferred embodiment, the flame-retardant organic ionic liquid proton electrolyte contains sulfolane, bis(trifluoromethylsulfonyl)imide, 1-methyl-1,2,4-triazole, and an organophosphorus-based flame retardant; wherein, the molar ratio of bis(trifluoromethylsulfonyl)imide to 1-methyl-1,2,4-triazole is 0.25 - 0.35 : 1; the molar volume ratio of bis(trifluoromethylsulfonyl)imide to sulfolane is 1.3 - 1.7 mol : 1 L; the volume ratio of the sum of the volumes of sulfolane, bis(trifluoromethylsulfonyl)imide, and 1-methyl-1,2,4-triazole to the volume of the organophosphorus-based flame retardant is 8.5 - 9.5 : 1; and the organophosphorus-based flame retardant is trimethyl phosphate. According to this preferred embodiment, the flame-retardant organic ionic liquid proton electrolyte has good comprehensive performance.

[0040] The second aspect of the present invention provides a method for preparing the above-mentioned flame-retardant organic ionic liquid proton electrolyte, and this method includes the following steps:

[0041] (1) Heat sulfolane to 50 - 70 °C, and then, under an inert atmosphere, successively add bis(trifluoromethylsulfonyl)imide and 1-methyl-1,2,4-triazole for mixing and dissolving to obtain an organic ionic liquid proton electrolyte;

[0042] (2) Mix the organic ionic liquid proton electrolyte with an organic phosphorus-based flame retardant and ultrasonicate, and then let it stand.

[0043] In step (1), the preheating process of the sulfolane may include: preheating sulfolane to 50 - 70 °C and maintaining it at 50 - 70 °C for 10 - 30 min to ensure that the sulfolane is in a liquid state.

[0044] In step (1), the inert atmosphere can be provided by a conventional inert gas (such as argon) or nitrogen. In a specific embodiment, bis(trifluoromethylsulfonyl)imide and 1-methyl-1,2,4-triazole are successively added to the preheated sulfolane for mixing and dissolving, and the entire preparation process is carried out in a glove box filled with nitrogen.

[0045] In a more preferred embodiment, the method for preparing the flame-retardant organic ionic liquid proton electrolyte includes:

[0046] (1) First, preheat sulfolane to 50 - 70 °C and maintain it for 10 - 30 min to ensure that the sulfolane is in a liquid state. Then, under an inert atmosphere, add bis(trifluoromethylsulfonyl)imide and continuously stir until it is completely dissolved and forms a light brown transparent solution. Finally, add 1-methyl-1,2,4-triazole and continuously stir until the above solution completely turns into a colorless transparent solution to obtain an organic ionic liquid proton electrolyte; wherein, the molar volume ratio of bis(trifluoromethylsulfonyl)imide to sulfolane can be 1.3 - 1.7 mol : 1 L, and the molar ratio of bis(trifluoromethylsulfonyl)imide to 1-methyl-1,2,4-triazole is 0.25 - 0.35 : 1;

[0047] (2) Mix the organic ionic liquid proton electrolyte with trimethyl phosphate and ultrasonicate, and then let it stand to obtain a flame-retardant organic ionic liquid proton electrolyte; wherein the volume ratio of the sum of the volumes of sulfolane, bis(trifluoromethylsulfonyl)imide, and 1-methyl-1,2,4-triazole to trimethyl phosphate is 8.5 - 9.5 : 1.

[0048] The third aspect of the present invention provides a proton half-cell, which includes a working electrode, a counter electrode, a reference electrode, a separator, and the above-mentioned flame-retardant organic ionic liquid proton electrolyte.

[0049] In a preferred case, the working electrode is a molybdenum trioxide electrode, the counter electrode is an activated carbon electrode, the reference electrode is a silver / silver ion electrode, and the separator is a glass fiber membrane.

[0050] In some specific embodiments, the preparation method of the proton half-cell includes the following processes:

[0051] a1. Mix molybdenum trioxide with graphene nanosheets to obtain a composite active material, and dissolve the composite active material, a conductive agent (such as Ketjenblack) and a binder (such as polyvinylidene fluoride) in an organic solvent (such as N-methylpyrrolidone) to obtain a slurry. Then coat the slurry on a current collector (such as hydrophilic carbon paper or hydrophilic carbon cloth), and after drying and cutting, obtain a molybdenum trioxide working electrode;

[0052] a2. Dissolve activated carbon and a binder (such as polyvinylidene fluoride) in an organic solvent (N-methylpyrrolidone) to obtain a slurry. Then coat the slurry on a current collector (hydrophilic carbon paper), and after drying and cutting, obtain an activated carbon counter electrode;

[0053] a3. Insert a silver wire electrode into an acetonitrile solution of silver nitrate to obtain a silver / silver ion reference electrode;

[0054] a4. Assemble the molybdenum trioxide electrode, the activated carbon electrode, the silver / silver ion reference electrode, the cut glass fiber separator and the flame-retardant organic ionic liquid proton electrolyte in a Swagelok cell housing to obtain a proton half-cell.

[0055] In process a1, the mass ratio of molybdenum trioxide to graphene nanosheets can be 3 - 5:1, preferably 3.2 - 4.8:1, and more preferably 3.5 - 4.5:1.

[0056] In process a2, the mass ratio of the activated carbon to polyvinylidene fluoride can be 8 - 10:1, preferably 8.2 - 9.8:1, and more preferably 8.5 - 9.5:1.

[0057] In the present invention, molybdenum trioxide, graphene nanosheets, Ketjenblack, polyvinylidene fluoride, N-methylpyrrolidone and activated carbon can each be commercially available products or prepared by conventional methods in the art.

[0058] The following examples are used to further illustrate the flame-retardant organic ionic liquid proton electrolyte, its preparation method and the proton half-cell of the present invention. The examples are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0059] In the experimental methods of the following examples, unless otherwise specified, they are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0060] In the following examples and comparative examples, sulfolane (purchased from Shanghai Macklin Biochemical Co., Ltd., the same below);

[0061] Bis(trifluoromethyl)sulfonimide (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., the same below);

[0062] 1-Methyl-1,2,4-triazole (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., the same below);

[0063] Trimethyl phosphate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., the same below);

[0064] Molybdenum trioxide (purchased from Shanghai Macklin Biochemical Co., Ltd., the same below);

[0065] Graphene nanosheets (purchased from Nanosianfeng Materials Technology Co., Ltd., the same below);

[0066] Ketjenblack (purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd., the same below);

[0067] Polyvinylidene fluoride (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., the same below);

[0068] N-Methylpyrrolidone (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., the same below);

[0069] Glass fiber (purchased from Beijing Woge Oriental Technology Co., Ltd., model Whatman GF / D, the same below);

[0070] Silver wire electrode (purchased from Tianjin Aida Hengsheng Technology Development Co., Ltd., the same below);

[0071] Swagelok three-electrode battery test device (purchased from Tianjin Aida Hengsheng Technology Development Co., Ltd., the same below).

[0072] Example 1

[0073] (1) Preparation of a flame-retardant organic ionic liquid proton electrolyte

[0074] Heat sulfolane to 60 °C and maintain for 15 min to ensure it is in a liquid state.

[0075] In a glove box filled with nitrogen, 4.215 g (0.015 mol) of bis(trifluoromethylsulfonyl)imide was dissolved in 0.01 L of the above-mentioned sulfolane, and stirred for 10 min to form a brown transparent solution. 4.155 g (0.05 mol) of 1-methyl-1,2,4-triazole was added to the above brown transparent solution, and stirring was continued until the brown transparent solution gradually changed into an almost colorless transparent solution, obtaining an organic ionic liquid proton electrolyte.

[0076] The organic ionic liquid proton electrolyte was mixed with trimethyl phosphate at a volume ratio of 9:1 and ultrasonicated for 30 min, and then allowed to stand for 10 min to obtain a flame-retardant organic ionic liquid proton electrolyte A1.

[0077] (2) Preparation of molybdenum trioxide proton half-cell

[0078] The active material molybdenum trioxide and graphene nanosheets were uniformly ground in an agate mortar at a mass ratio of 4:1 to obtain a composite active substance. The composite active substance, Ketjen black, and polyvinylidene fluoride were dissolved in N-methylpyrrolidone at a mass ratio of 7:2:1, ground into a uniform slurry, and then the slurry was uniformly coated on a hydrophilic carbon paper current collector, dried in a vacuum oven at 60 °C for 12 h, and then cut into circular molybdenum trioxide electrode sheets with a diameter of 12 mm.

[0079] Activated carbon and polyvinylidene fluoride were dissolved in N-methylpyrrolidone at a mass ratio of 9:1, ground into a uniform slurry, and then the slurry was coated on a hydrophilic carbon paper current collector, dried in a vacuum oven at 60 °C for 12 h, and then cut into circular activated carbon electrode sheets with a diameter of 12 mm.

[0080] A silver wire electrode was inserted into an acetonitrile solution of 10 mmol L -1 silver nitrate to obtain a silver / silver ion electrode.

[0081] A glass fiber diaphragm of type Whatman GF / D was cut into circular diaphragms with a diameter of 13 mm to obtain a glass fiber diaphragm.

[0082] The molybdenum trioxide electrode, the activated carbon electrode, the silver / silver ion electrode, the cut glass fiber diaphragm, and the flame-retardant organic ionic liquid proton electrolyte A1 were assembled in a Swagelok three-electrode cell system to obtain a molybdenum trioxide proton half-cell S1.

[0083] Example 2

[0084] (1) Preparation of flame-retardant organic ionic liquid proton electrolyte

[0085] Sulfolane was heated to 50 °C and maintained for 20 min to ensure a liquid state.

[0086] In a glove box filled with nitrogen, 3.655 g (0.013 mol) of bis(trifluoromethylsulfonyl)imide was dissolved in 0.01 L of the above-mentioned sulfolane, and stirred for 10 min to form a brown transparent solution. 4.3212 g (0.052 mol) of 1-methyl-1,2,4-triazole was added to the above brown transparent solution, and stirring was continued until the brown transparent solution gradually changed into an almost colorless transparent solution, obtaining an organic ionic liquid proton electrolyte.

[0087] The organic ionic liquid proton electrolyte was mixed with trimethyl phosphate at a volume ratio of 8.5:1 and ultrasonicated for 30 min, and then left standing for 10 min to obtain a flame-retardant organic ionic liquid proton electrolyte A2.

[0088] (2) Preparation of molybdenum trioxide proton half-cell

[0089] The active material molybdenum trioxide and graphene nanosheets were uniformly mixed in an agate mortar at a mass ratio of 3.5:1 to obtain a composite active substance. The composite active substance, Ketjen black and polyvinylidene fluoride were dissolved in N-methylpyrrolidone at a mass ratio of 7:2:1, ground into a uniform slurry, and then the slurry was uniformly coated on a hydrophilic carbon paper current collector and dried in a vacuum oven at 60 °C for 12 h and then cut into circular molybdenum trioxide electrode sheets with a diameter of 12 mm.

[0090] Activated carbon and polyvinylidene fluoride were dissolved in N-methylpyrrolidone at a mass ratio of 8.5:1, ground into a uniform slurry, and then the slurry was coated on a hydrophilic carbon paper current collector and dried in a vacuum oven at 60 °C for 12 h and then cut into circular activated carbon electrode sheets with a diameter of 12 mm.

[0091] A silver wire electrode was inserted into an acetonitrile solution of silver nitrate at 10 mmol L -1 to obtain a silver / silver ion electrode.

[0092] A glass fiber diaphragm of type Whatman GF / D was cut into circular diaphragms with a diameter of 13 mm to obtain a glass fiber diaphragm.

[0093] The molybdenum trioxide electrode, the activated carbon electrode, the silver / silver ion electrode, the cut glass fiber diaphragm and the flame-retardant organic ionic liquid proton electrolyte A2 were assembled in a Swagelok three-electrode cell system to obtain a molybdenum trioxide proton half-cell S2.

[0094] Example 3

[0095] (1) Preparation of flame-retardant organic ionic liquid proton electrolyte

[0096] Preheat sulfolane to 70 °C and keep it for 5 min to ensure it is in a liquid state.

[0097] In a glove box filled with nitrogen, 4.78 g (0.017 mol) of bis(trifluoromethylsulfonyl)imide was dissolved in 0.01 L of the above-mentioned sulfolane, and stirred for 10 min to form a brown transparent solution. 4.0719 g (0.049 mol) of 1-methyl-1,2,4-triazole was added to the above-mentioned brown transparent solution, and stirring was continued until the brown transparent solution gradually changed into an almost colorless transparent solution, obtaining an organic ionic liquid proton electrolyte.

[0098] The organic ionic liquid proton electrolyte was mixed with trimethyl phosphate at a volume ratio of 9.5:1 and ultrasonicated for 30 min, and then allowed to stand for 10 min to obtain a flame-retardant organic ionic liquid proton electrolyte A3.

[0099] (2) Preparation of molybdenum trioxide proton half-cell

[0100] The active material molybdenum trioxide and graphene nanosheets were uniformly mixed in a mass ratio of 4.5:1 in an agate mortar to obtain a composite active substance, and the composite active substance, Ketjen black and polyvinylidene fluoride were dissolved in N-methylpyrrolidone in a mass ratio of 7:2:1, ground into a uniform slurry, and then the slurry was uniformly coated on a hydrophilic carbon paper current collector and dried in a vacuum oven at 60 °C for 12 h and then cut into circular molybdenum trioxide electrode sheets with a diameter of 12 mm.

[0101] Activated carbon and polyvinylidene fluoride were dissolved in N-methylpyrrolidone in a mass ratio of 9.5:1, ground into a uniform slurry, and then the slurry was coated on a hydrophilic carbon paper current collector and dried in a vacuum oven at 60 °C for 12 h and then cut into circular activated carbon electrode sheets with a diameter of 12 mm.

[0102] A silver wire electrode was inserted into an acetonitrile solution of silver nitrate at 10 mmol L -1 to obtain a silver / silver ion electrode.

[0103] A glass fiber diaphragm of Whatman GF / D type was cut into circular diaphragms with a diameter of 13 mm to obtain a glass fiber diaphragm.

[0104] The molybdenum trioxide electrode, the activated carbon electrode, the silver / silver ion electrode, the cut glass fiber diaphragm and the flame-retardant organic ionic liquid proton electrolyte A3 were assembled in a Swagelok three-electrode cell system to obtain a molybdenum trioxide proton half-cell S3.

[0105] Example 4

[0106] Prepare a flame-retardant organic ionic liquid proton electrolyte and a molybdenum trioxide proton half-cell according to the method of Example 1, except that during the preparation of the flame-retardant organic ionic liquid proton electrolyte, the organic ionic liquid proton electrolyte is mixed with trimethyl phosphate at a volume ratio of 5:1 and sonicated for 30 min, then left standing for 10 min, and then the molybdenum trioxide proton half-cell is prepared. Finally, a flame-retardant organic ionic liquid proton electrolyte A4 and a molybdenum trioxide proton half-cell S4 are obtained.

[0107] Example 5

[0108] Prepare a flame-retardant organic ionic liquid proton electrolyte and a molybdenum trioxide proton half-cell according to the method of Example 1, except that during the preparation of the flame-retardant organic ionic liquid proton electrolyte, the organic ionic liquid proton electrolyte is mixed with trimethyl phosphate at a volume ratio of 15:1 and sonicated for 30 min, then left standing for 10 min, and then the molybdenum trioxide proton half-cell is prepared. Finally, a flame-retardant organic ionic liquid proton electrolyte A5 and a molybdenum trioxide proton half-cell S5 are obtained.

[0109] Example 6

[0110] Prepare a flame-retardant organic ionic liquid proton electrolyte and a molybdenum trioxide proton half-cell according to the method of Example 1, except that during the preparation of the flame-retardant organic ionic liquid proton electrolyte, the organophosphorus-based flame retardant is ethoxy(pentafluoro)cyclophosphazene. Finally, a flame-retardant organic ionic liquid proton electrolyte A6 and a molybdenum trioxide proton half-cell S6 are obtained.

[0111] Comparative Example 1

[0112] Prepare a flame-retardant organic ionic liquid proton electrolyte and a molybdenum trioxide proton half-cell according to the method of Example 1, except that during the preparation of the flame-retardant organic ionic liquid proton electrolyte, deionized water is used to replace the organophosphorus-based flame retardant trimethyl phosphate. Finally, a flame-retardant organic ionic liquid proton electrolyte D1 and a molybdenum trioxide proton half-cell M1 are obtained.

[0113] Comparative Example 2

[0114] Prepare a flame-retardant organic ionic liquid proton electrolyte and a molybdenum trioxide proton half-cell according to the method of Example 1, except that during the preparation of the flame-retardant organic ionic liquid proton electrolyte, the organic ionic liquid proton electrolyte is mixed with trimethyl phosphate at a volume ratio of 20:1 and sonicated for 30 min, then left standing for 10 min, and then the molybdenum trioxide proton half-cell is prepared. Finally, a flame-retardant organic ionic liquid proton electrolyte D2 and a molybdenum trioxide proton half-cell M2 are obtained.

[0115] Comparative Example 3

[0116] The flame-retardant organic ionic liquid proton electrolyte and molybdenum trioxide proton half-cell were prepared according to the method of Example 1, except that during the preparation of the flame-retardant organic ionic liquid proton electrolyte, the organic ionic liquid proton electrolyte was mixed with trimethyl phosphate at a volume ratio of 4:1 and sonicated for 30 min, then allowed to stand for 10 min, and then the molybdenum trioxide proton half-cell was prepared, and finally the flame-retardant organic ionic liquid proton electrolyte D3 and molybdenum trioxide proton half-cell M3 were obtained.

[0117] Comparative Example 4

[0118] The organic ionic liquid proton electrolyte and molybdenum trioxide proton half-cell were prepared according to the method of Example 1, except that during the preparation of the electrolyte, no flame retardant was added, and finally the organic ionic liquid proton electrolyte D4 and molybdenum trioxide proton half-cell M4 were obtained.

[0119] Test Example

[0120] (1) The combustion states of the original circular glass fiber separator and the flame-retardant organic ionic liquid proton electrolytes prepared in Example 1 and 6 and Comparative Example 1 and 4 were tested by the combustion method. The specific process was as follows: The circular glass fiber separator was soaked in A1, A6, D1, and D4 respectively and then ignited, and the combustion states of the circular glass fiber separator before and after soaking were observed. The results showed that when the original glass fiber separator was ignited by an open flame, no flame was generated, but obvious melting occurred, making the glass fiber separator unable to maintain its original shape (as Figure 1 shown), which indicated that the melting process of the original glass fiber separator under an open flame would damage the basic structure of the glass fiber separator and was not conducive to the safe operation of the battery; when the glass fiber separator soaked in D4 was ignited by an open flame, a bright combustion flame would be generated, and this combustion state would continue until the electrolyte components were completely burned out (as Figure 2 shown); when the glass fiber separators soaked in A1, A6, and D1 were ignited by an open flame, bright combustion flames would also be generated, but when the open flame was removed, the combustion flames would quickly go out, and the original state of the glass fiber separator could be well retained (as shown in Figure 3 b, 3a, and 3c respectively), which indicated that the flame-retardant organic ionic liquid proton electrolytes prepared in Example 1 and 6 and Comparative Example 1 all had good flame retardant properties.

[0121] (2) The electrochemical windows of the flame-retardant organic ionic liquid proton electrolytes prepared in Example 1 and Example 6 and Comparative Example 1 were tested by linear voltammetry, and the results were as Figure 4 shown.

[0122] (3) The cyclic voltammograms of the molybdenum trioxide proton half-cells prepared in Example 1 and Example 6 and Comparative Example 1 were tested by cyclic voltammetry, and the results were asFigures 5 - 7 as shown

[0123] (4) The electrochemical impedance of the molybdenum trioxide proton half-cells prepared in Example 1, Example 6, and Comparative Example 1 was tested using the alternating current impedance method, and the results are as Figure 8 shown

[0124] (5) The specific capacity of the molybdenum trioxide proton half-cells prepared in the examples and comparative examples was tested using the constant current discharge test method at current densities of 0.1 Ag -1 and 1 Ag -1 , and the results are shown in Table 1

[0125] (6) The battery cycle stability of the molybdenum trioxide proton half-cells prepared in the examples and comparative examples after 1000 cycles at a current density of 1 Ag -1 was tested using the constant current cyclic charge-discharge test method. The calculation method of the capacity retention rate is as follows: Capacity retention rate = (ending capacity / initial capacity) × 100%, and the results are as Figures 9 - 11 and shown in Table 1

[0126] Table 1

[0127]

[0128] It can be seen from Figures 1 - 11 the results in and Table 1 that the molybdenum trioxide proton half-cells prepared in the flame-retardant organic ionic liquid proton electrolyte of the present invention have the characteristics of high electrochemical stability, good electrical conductivity, and strong electrochemical storage capacity. By observing the combustion state of the ionic liquid electrolyte, it can be found that the organic ionic liquid proton electrolyte after adding the flame retardant can exhibit good flame retardant performance, which can greatly improve the safety of the proton battery under high temperature or open flame conditions, prevent the occurrence of safety accidents, and has an important role in the practical application of the proton battery

[0129] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention

Claims

1. A flame retardant organic ionic liquid proton electrolyte, characterized in that: The flame-retardant organic ionic liquid proton electrolyte comprises an organic ionic liquid proton electrolyte and an organic phosphorus-based flame retardant, wherein the organic ionic liquid proton electrolyte contains cyclopentane sulfone, bistrifluoromethylsulfonyl imide and 1-methyl-1,2,4-triazole, wherein the molar ratio of bistrifluoromethylsulfonyl imide to 1-methyl-1,2,4-triazole is 0.2-0.4:

1.

2. The flame-retardant organic ionic liquid proton electrolyte according to claim 1, characterized in that: The molar ratio of bistrifluoromethylsulfonyl imide to 1-methyl-1,2,4-triazole is 0.22-0.38:

1.

3. The flame-retardant organic ionic liquid proton electrolyte according to claim 1 or 2, characterized in that: The volume ratio of the sum of the volumes of sulfolane, bistrifluoromethylsulfonyl imide and 1-methyl-1,2,4-triazole to the organic phosphorus-based flame retardant is 5-15:

1.

4. The flame-retardant organic ionic liquid proton electrolyte according to claim 3, characterized in that: The volume ratio of the sum of the volumes of sulfolane, bistrifluoromethylsulfonyl imide and 1-methyl-1,2,4-triazole to the organic phosphorus-based flame retardant is 8-10:

1.

5. The flame-retardant organic ionic liquid proton electrolyte according to any one of claims 1 to 4, characterized in that: The organic phosphorus-based flame retardant is at least one of trimethyl phosphate, triethyl phosphate, ethoxy (pentafluoro) cyclotriphosphazene, hexafluorocyclotriphosphazene and phosphite.

6. The flame-retardant organic ionic liquid proton electrolyte according to any one of claims 1 to 5, characterized in that: The molar volume ratio of bistrifluoromethylsulfonyl imide to cyclopentane sulfone is 0.75-3 mol:1L.

7. The flame-retardant organic ionic liquid proton electrolyte according to claim 6, characterized in that: The molar volume ratio of bistrifluoromethylsulfonyl imide to cyclopentane sulfone is 1-2 mol:1L.

8. A method for preparing the flame-retardant organic ionic liquid proton electrolyte according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: (1) heating sulfolane to 50-70° C., and then adding bistrifluoromethylsulfonyl imide and 1-methyl-1,2,4-triazole in sequence under an inert atmosphere for mixed dissolution to obtain an organic ionic liquid proton electrolyte; (2) The organic ionic liquid proton electrolyte and the organic phosphorus-based flame retardant are mixed and ultrasonicated, and then allowed to stand.

9. A proton half-cell, characterized in that: The proton half-cell comprises a working electrode, a counter electrode, a reference electrode, a diaphragm and the flame-retardant organic ionic liquid proton electrolyte according to any one of claims 1 to 7.

10. The proton half-cell according to claim 9, characterized in that: The working electrode is a molybdenum trioxide electrode; and / or The counter electrode is an activated carbon electrode; and / or The reference electrode is a silver / silver ion electrode; and / or The diaphragm is a glass fiber membrane.

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