An inorganic-organic gel electrolyte and its preparation method and application in aqueous zinc-iodine battery

Abstract

The invention discloses an inorganic-organic gel electrolyte and a preparation method thereof and an application thereof in an aqueous zinc-iodine battery, which belongs to the preparation and application field of inorganic-organic gel electrolytes of aqueous zinc-ion batteries, including preparing a solution of zinc salt and deionized water, then adding an inorganic porous material, a hydrogel monomer, a crosslinking agent and an initiator according to a percentage of the mass of the zinc salt, and then preparing a gel electrolyte by heating or ultraviolet irradiation. The addition of the inorganic porous material enables the gel electrolyte to have higher mechanical properties, can achieve high ionic conductivity, ion migration number, and the porous gel structure promotes uniform deposition of zinc ions, thereby extending the cycle life of the battery, and can also achieve stable four-electron transfer of zinc-iodine batteries under low-concentration zinc salts and high-load positive electrodes.

Description

Technical Field

[0001] The invention relates to an inorganic-organic gel electrolyte and a preparation method thereof and application in an aqueous zinc-iodine battery, belonging to the technical field of hydrogel electrolyte preparation. Background Art

[0002] Aqueous zinc rechargeable batteries are considered to be one of the most promising next-generation energy storage devices in terms of intrinsic safety and ecology. Iodine-based cathode materials are attractive due to their potential in constructing multi-electron transfer redox pairs for high-energy-density batteries. 2 The battery (ZIB) uses only I / I with a 2e transfer process 2 Redox couple (0.54 V vs. standard hydrogen electrode (SHE), 211 mAh g -1 ), and the 4e transfer process of iodine in continuous I / I 2 / I + The redox couple can provide a higher redox potential (0.54 / 1.07 V vs. SHE) and 422 mAh g -1 However, four-electron zinc-iodine aqueous batteries (4eZIBs) have encountered major challenges that affect their stability and performance. One of the main obstacles is the positive-valent I + Substances (such as ICl or ICl 2 – ) in aqueous electrolytes. Although the formation of ICl interhalogen compounds during the electrooxidation of iodine is thermodynamically favored by the presence of nucleophiles such as halides, cyanides, and amines, it is easily hydrolyzed due to the attack of the OH moiety from water. The hydrolysis leads to low Coulombic efficiency, voltage decay, and poor cycling performance. Previous reports on the realization of 4eZIBs mainly rely on superconcentrated aqueous electrolytes or non-aqueous electrolytes. The latter approach is plagued by the dissolution of active materials because iodine and ICl interhalogen compounds are highly soluble in organic solvents. Although superconcentrated aqueous electrolytes effectively suppress the free water activity, the high viscosity of such highly concentrated electrolytes hinders ion transport and leads to sluggish electrode kinetics. Further progress in the development of 4eZIBs requires the exploration of lower concentration electrolytes to enhance the feasibility and practicality of the battery system. The introduction of inorganic porous materials in hydrogel electrolytes can achieve four-electron transfer in zinc-iodine batteries at high loads and high currents under low electrolyte concentrations. Summary of the invention

[0003] The use of inorganic-organic gel electrolyte can inhibit the side reactions of the zinc negative electrode, promote the uniform deposition of zinc ions, and inhibit the I +The hydrolysis of ZnO can improve the cycle life and coulombic efficiency of the battery. The addition of inorganic porous materials can increase the ion migration number and ion conductivity of the gel electrolyte, improve the mechanical strength of the gel electrolyte, and the porous structure can regulate the zinc ion flux and promote uniform deposition. In this process, the type of inorganic porous material is extremely important for improving the cycle life.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] The invention provides a method for preparing an inorganic-organic gel electrolyte, comprising: preparing an inorganic porous material, a hydrogel monomer, a zinc salt and deionized water into a solution, then adding a crosslinking agent and an initiator, stirring until completely dissolved, and obtaining a hydrogel electrolyte for an aqueous zinc ion battery by heating or ultraviolet irradiation.

[0006] The component contents of the inorganic-organic gel electrolyte are as follows: the weight percentage of the inorganic porous material is 1% to 5%, the zinc salt concentration is 1 M to 3 M; the weight percentage of the hydrogel monomer is 20% to 50%; the weight percentage of the initiator is 0.01% to 0.05%; the weight percentage of the cross-linking agent is 0.01% to 0.05%, and the rest is deionized water.

[0007] Furthermore, in the hydrogel electrolyte, the inorganic porous material includes one or more of microporous molecular sieve material, mesoporous molecular sieve material, ceramic, diatomaceous earth, silicon oxide, aluminum oxide, and hybrid metal organic framework. Preferably, the weight percentage of the inorganic porous material is 2.95% to 3.05%.

[0008] Furthermore, the microporous molecular sieve material includes one or more of aluminosilicate, phosphate, and germanate.

[0009] Furthermore, in the hydrogel electrolyte, the zinc salt includes zinc sulfate (ZnSO 4 ), zinc tetrafluoroborate (Zn(BF 4 ) 2 ), zinc trifluoromethanesulfonate (Zn(OTf) 2 ), zinc bis(trifluoromethylsulfonyl)imide (ZnTFSI), zinc chloride (ZnCl 2 ), zinc perchlorate (ClH 3 O 5 Zn), zinc acetate (C 4 H 6 O 4 Preferably, the zinc salt concentration is 1.95 M to 2.05 M.

[0010] Furthermore, in the hydrogel electrolyte, the hydrogel monomers are one or more of acrylamide (AM), 2-hydroxypropyl acrylic acid, hydroxyalkyl methacrylate, N-vinyl pyrrolidone, and acrylate derivatives. Preferably, the weight percentage of the hydrogel monomers is 29.5% to 30.5%.

[0011] Further, in the hydrogel electrolyte, the hydrogel initiator includes one or more of potassium persulfate, sodium perbromide, benzoyl peroxide, ammonium persulfate, lauroyl peroxide, azobisdimethylvaleronitrile, sodium azobiscyanovalerate, benzoyl (BPO), azobisisopropylimidazoline hydrochloride, azobiscyanovaleric acid, and azobisisobutylamidine hydrochloride. Preferably, the weight percentage of the initiator is 0.25% to 0.35%.

[0012] Further, in the hydrogel electrolyte, the hydrogel crosslinker is one or more of N, N'-methylene acrylamide (MBA), N, N'-methylene bisacrylamide (BIS), epichlorohydrin (ECH), diisopropyl peroxide (DCP), benzoyl peroxide (BPO), di-tert-butyl peroxide (DTBP), diisopropyl hydroperoxide (DBCP), propylbenzene divinyl benzene, diisocyanate, and acrylic acid. Preferably, the weight percentage of the crosslinker is 0.25% to 0.35%.

[0013] Furthermore, during the preparation process, the heating temperature ranges from 80°C to 85°C, and the heating time ranges from 1.5 h to 2 h.

[0014] The present invention provides an inorganic-organic gel electrolyte obtained by the above preparation method.

[0015] The present invention provides application of the electrolyte in aqueous zinc-iodine batteries.

[0016] The raw materials involved in the above-mentioned method for preparing aqueous zinc ion electrolyte are all commercially available, and the equipment and processes used are well known to those skilled in the art.

[0017] The advantages and positive effects of the present invention are:

[0018] 1. The method of the present invention has low cost, simple operation, environmental friendliness and can be mass-produced.

[0019] 2. The present invention introduces inorganic porous materials into the hydrogel electrolyte to inhibit the side reaction of the zinc negative electrode, promote the uniform deposition of zinc ions, and inhibit I + The hydrolysis of Zn can improve the cycle life and coulombic efficiency of the battery. The addition of inorganic porous materials can increase the ion migration number and ion conductivity of the gel electrolyte, improve the mechanical strength of the gel electrolyte, and the porous structure can regulate the zinc ion flux and promote uniform deposition. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 1 is the strain-stress curve of the gel electrolyte of Example 1 and the comparative sample;

[0021] Figure 2 The charge and discharge curves of the zinc-iodine full battery of Example 1 and the comparative sample;

[0022] Figure 3 1 is the strain-stress curve of the gel electrolyte of Example 2 and the comparative sample;

[0023] Figure 4 The charge and discharge curves of the zinc-iodine full battery of Example 2 and the comparative sample are shown. DETAILED DESCRIPTION

[0024] The following is further described in conjunction with specific examples. It should be understood that these examples are used to illustrate the present invention but not to limit the scope of the present invention. The implementation conditions used in the examples can be further adjusted according to specific construction conditions, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0025] Example 1

[0026] A method for preparing an inorganic-organic gel electrolyte comprises: weighing 0.3 g of a silicon oxide inorganic porous material, 8.6 g of a hydrogel monomer, and 28.756 g of zinc sulfate heptahydrate (ZnSO 4 7 H 2 O), 0.057 g of cross-linking agent and 0.057 g of initiator were added into a beaker and dissolved with deionized water, and then the volume was fixed with a 100 mL volumetric flask. Then 20 mL was poured into a 10 cm × 10 cm glass mold and heated at 85 °C for 120 min to obtain an inorganic-organic gel electrolyte.

[0027] Preparation method of comparative sample (the difference from Example 1 is that no silicon oxide inorganic porous material is added): weigh 28.756 g zinc sulfate heptahydrate (ZnSO 4 7 H 2 O), 8.6 g hydrogel monomer, 0.057 g initiator and 0.057 g cross-linking agent were added into a beaker and dissolved with deionized water, then fixed to volume with a 100 mL volumetric flask, and then 20 mL was poured into a 10 cm × 10 cm glass mold and heated at 85 ° C for 120 min to obtain a pure organic gel electrolyte.

[0028] Tensile performance test: The test was conducted using a universal material testing machine. The test specimens were uniformly dumbbell-shaped, with effective length, width, and thickness of 25.0 mm, 5.0 mm, and 1.0 mm, respectively. During the tensile test, the range was 1 kN and the tensile rate was uniformly 10 mm min. -1 。 The strain-stress curve obtained from the test is shown in Figure 1 As shown, it can be seen that the addition of inorganic porous materials greatly improves the mechanical properties of the gel.

[0029] Preparation method of positive electrode material: According to the weight ratio of 3:7, 180 mg of iodine and 420 mg of Ketjen black were weighed on a balance, ground in a mortar for 30 min, transferred to a glass bottle and then placed in a hydrothermal reactor, heated at 80 ° C for 4 h, and iodine was immersed in Ketjen black by sublimation, called I 2 @C. Then weigh 280 mg I in a ratio of 7:2:1. 2 @C, 80 mg Ketjen black and 40 mg PTFE emulsion were ground in a mortar for 30 min and then rolled into iodine positive electrode discs with a glass rod and a sheet cutter to obtain 14 mm diameter iodine positive electrode discs. After drying, the iodine positive electrode was pressed onto the titanium mesh current collector using a tablet press, with a loading of about 10 mg cm -2 .

[0030] Full battery assembly method: Use an iodine positive electrode with a diameter of 14 mm as the positive electrode material, a zinc plate with a diameter of 14 mm and a thickness of 0.1 mm as the negative electrode material, and a gel electrolyte with a diameter of 16 mm and a thickness of 1 mm as the separator and electrolyte, and package under a pressure of 1.0T.

[0031] The cycling stability of the assembled aqueous zinc-ion full battery was tested at 10 C. Figure 2 As shown in the figure, under 10 C conditions, the zinc-iodine full battery corresponding to the inorganic-organic gel electrolyte can be stably cycled for 3000 cycles, and the specific capacity is maintained at 270 mAh g -1 , and the coulombic efficiency is 99.7%. However, the zinc-iodine full battery corresponding to the organic gel electrolyte cycled 250 times, and the capacity and coulombic efficiency were much lower than those of the inorganic-organic gel electrolyte. This shows that the gel electrolyte has excellent cycle stability in the full battery.

[0032] Example 2

[0033] A method for preparing an inorganic-organic gel electrolyte comprises: weighing 0.3 g of a molecular sieve porous material, 8.6 g of a hydrogel monomer, and 28.756 g of zinc sulfate heptahydrate (ZnSO4·7 H 2O), 0.057 g of cross-linking agent and 0.057 g of initiator were added into a beaker and dissolved with deionized water, and then the volume was fixed with a 100 mL volumetric flask. Then 20 mL was poured into a 10 cm × 10 cm glass mold and heated at 85 °C for 120 min to obtain an inorganic-organic gel electrolyte.

[0034] Preparation method of comparative sample: weigh 28.756 g zinc sulfate heptahydrate (ZnSO 4 7 H 2 O), 8.6 g hydrogel monomer, 0.057 g initiator and 0.057 g cross-linking agent were added into a beaker and dissolved with deionized water, then fixed to volume with a 100 mL volumetric flask, and then 20 mL was poured into a 10 cm × 10 cm glass mold and heated at 85 ° C for 120 min to obtain a pure organic gel electrolyte.

[0035] Tensile performance test: The test was conducted using a universal material testing machine. The test specimens were uniformly dumbbell-shaped, with effective length, width, and thickness of 25.0 mm, 5.0 mm, and 1.0 mm, respectively. During the tensile test, the range was 1 kN and the tensile rate was uniformly 10 mm min. -1 。 The strain-stress curve obtained from the test is shown in Figure 3 As shown, it can be seen that the addition of inorganic porous materials greatly improves the mechanical properties of the gel.

[0036] Preparation method of positive electrode material: According to the ratio of 3:7, 180 mg of iodine and 420 mg of Ketjen black were weighed on a balance, ground in a mortar for 30 min, transferred to a glass bottle and then placed in a hydrothermal reactor, heated at 80 ° C for 4 h, and iodine was immersed in Ketjen black by sublimation, called I 2 @C. Then weigh 280 mg I in a ratio of 7:2:1. 2 @C, 80 mg Ketjen black and 40 mg PTFE emulsion were ground in a mortar for 30 min and then rolled into iodine positive electrode discs with a glass rod and a sheet cutter to obtain 14 mm diameter iodine positive electrode discs. After drying, the iodine positive electrode was pressed onto the titanium mesh current collector using a tablet press, with a loading of about 10 mg cm -2 .

[0037] Full battery assembly method: Use an iodine positive electrode with a diameter of 14 mm as the positive electrode material, a zinc plate with a diameter of 14 mm and a thickness of 0.1 mm as the negative electrode material, and a gel electrolyte with a diameter of 16 mm and a thickness of 1 mm as the separator and electrolyte, and package under a pressure of 1.0T.

[0038] The cycling stability of the assembled aqueous zinc-ion full battery was tested at 10 C. Figure 4 As shown in the figure, under 10 C conditions, the zinc-iodine full battery corresponding to the inorganic-organic gel electrolyte can be stably cycled for 3000 cycles, and the specific capacity is maintained at 232 mAh g -1 , with a coulombic efficiency of 99.7%. However, the zinc-iodine full battery corresponding to the organic gel electrolyte cycled 242 times, and its capacity and coulombic efficiency were much lower than those of the inorganic-organic gel electrolyte. This shows that the gel electrolyte has excellent cycle stability in the full battery.

[0039] The above contents are further detailed descriptions of the invention in combination with specific embodiments, and it cannot be determined that the specific implementation of the invention is limited to these descriptions. For those skilled in the art of the present invention, any obvious simple deduction or replacement without departing from the concept of the present invention is within the scope of protection of the present invention.

Claims

1. An application of an inorganic-organic gel electrolyte in an aqueous zinc-iodine battery, wherein the preparation method of the inorganic-organic gel electrolyte comprises: The inorganic porous material, the hydrogel monomer, the zinc salt and the deionized water are prepared into a solution, and then a cross-linking agent and an initiator are added, and then an inorganic-organic gel electrolyte is prepared by heating; The inorganic porous material is selected from mesoporous molecular sieve materials or silicon oxide; The component contents of the inorganic-organic gel electrolyte are as follows: the weight percentage of the inorganic porous material is 1% to 5%, the zinc salt concentration is 1 M to 3 M; the weight percentage of the hydrogel monomer is 20% to 50%; the weight percentage of the initiator is 0.01% to 0.05%; the weight percentage of the cross-linking agent is 0.01% to 0.05%, and the rest is deionized water.

2. The use according to claim 1, characterized in that: The zinc salt includes one or more of zinc sulfate, zinc tetrafluoroborate, zinc trifluoromethanesulfonate, zinc bis(trifluoromethylsulfonyl)imide, zinc chloride, zinc perchlorate, and zinc acetate.

3. The use according to claim 1, characterized in that: The hydrogel monomers include one or more of acrylamide, hydroxyalkyl methacrylate, and N-vinyl pyrrolidone.

4. The use according to claim 1, characterized in that: The initiator includes one or more of potassium persulfate, sodium perbromide, benzoyl peroxide, ammonium persulfate, lauroyl peroxide, azobisdimethylvaleronitrile, sodium azobiscyanovalerate, azobisisopropylimidazoline hydrochloride, azobiscyanovaleric acid, and azobisisobutylamidine hydrochloride.

5. The use according to claim 1, characterized in that: The crosslinking agent is one or more of N,N'-methylenebisacrylamide, epichlorohydrin, and diisocyanate.

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