An electrolyte of a local high-concentration ionic liquid and a preparation method and an assembled high-voltage zinc-tellurium battery

Abstract

The application belongs to the technical field of batteries, and discloses a local high-concentration ionic liquid electrolyte, a preparation method thereof and an assembled high-voltage zinc-tellurium battery. The electrolyte comprises an ionic liquid, zinc bromide, zinc fluoride and an organic cosolvent; the ionic liquid is one or more of 1-vinyl-3-butyl imidazolium bromide, 1-ethyl-3-methyl imidazolium bromide, 1-propyl-3-methyl imidazolium bromide or 1-butyl-3-methyl imidazolium bromide. The local high-concentration ionic liquid electrolyte contains active species ZnBr4 2‑ , which can activate the positive-valence conversion of tellurium, play the effect of exciting and stabilizing the Te 0 / Te 4+ redox pair. The zinc-tellurium battery assembled thereby can realize the two-step conversion reaction of Te 4+ / Te and Te / Te 2‑ of the tellurium positive electrode, improve the energy output of the battery, increase the high-voltage discharge platform capacity ratio of the zinc-tellurium battery to 80.6%, and improve the rate performance of the zinc-tellurium battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrolyte, and more particularly relates to a local high-concentration ionic liquid electrolyte, a preparation method thereof and an assembled high-voltage zinc-tellurium battery. BACKGROUND

[0002] Rechargeable batteries play an indispensable role in various applications such as renewable energy, uninterruptible power supply systems, electric transportation and smart grids as high-efficiency devices with high power and energy density. As a new type of rechargeable energy storage device in recent years, zinc ion batteries have the advantages of low cost, high safety and high performance, and have great application potential in large-scale energy storage.

[0003] Currently, developing high-energy-density conversion-type cathode materials with multi-electron transfer is an important way to make up for the short energy density of zinc ion batteries. However, the current water-based zinc batteries based on sulfur group (sulfur, selenium, tellurium and their compounds) conversion-type cathode materials generally have a serious "shuttle effect", which leads to rapid loss of effective active materials in the cathode and rapid performance decay, which cannot meet the energy storage demand. In addition, in the conventional aqueous electrolyte, the zinc anode has serious problems such as hydrogen evolution, corrosion and dendrite growth, which greatly shortens the cycle life of the conversion-type zinc ion battery, which further limits the development of zinc ion batteries.

[0004] Tellurium, as a conversion-type cathode, has a good application prospect in high-energy-density zinc batteries due to its rich variable valence and high specific capacity. Since tellurium has a large atomic radius (140 pm), the chain structure of tellurium has a relatively low surface negative charge density, which enables tellurium to realize reversible conversion of positive valence in a specific electrochemical environment. However, in the traditional Te 0 / Te 4+ conversion reaction, the reaction kinetics is slow, and the positive valence conversion is incomplete, which reduces the multi-step reaction voltage and specific capacity of tellurium, and further reduces the energy efficiency of tellurium conversion. Therefore, it is particularly important to develop an electrolyte that can improve the positive valence reaction voltage of tellurium and has high ionic conductivity. SUMMARY

[0005] In order to solve the above-mentioned deficiencies and shortcomings of the prior art, the primary purpose of the present application is to provide a local high-concentration ionic liquid electrolyte, which activates the positive conversion of tellurium through ZnBr4 2- species, ZnBr4 2- plays a role in exciting and stabilizing the Te 0 / Te 4+ redox pair, so that the zinc-tellurium battery has a higher high-voltage platform discharge capacity, greatly improves the energy output of the tellurium battery cathode, and thus improves the rate performance of the zinc-tellurium battery.

[0006] Another object of the present application is to provide a preparation method of the above-mentioned local high-concentration ionic liquid electrolyte.

[0007] Still another object of the present application is to provide a high-voltage zinc tellurium battery with the above-mentioned local high-concentration ionic liquid electrolyte assembled, and a reversible electrochemical reaction of Te 2- / Te / Te 4+ occurring at the positive electrode.

[0008] The object of the present application is achieved by the following technical solutions:

[0009] A local high-concentration ionic liquid electrolyte, comprising an ionic liquid, zinc bromide, zinc fluoride and an organic co-solvent; the ionic liquid is one or more of 1-vinyl-3-butyl imidazolium bromide, 1-ethyl-3-methyl imidazolium bromide, 1-propyl-3-methyl imidazolium bromide or 1-butyl-3-methyl imidazolium bromide.

[0010] Preferably, the organic co-solvent is one or more of dichloromethane, dichloroethane, dichloropropane, trichloromethane, fluorobenzene, toluene or p-xylene.

[0011] Preferably, the molar ratio of the ionic liquid, zinc bromide, zinc fluoride and organic co-solvent is 1:(1-1.8):(0.05-0.1):(0.1-0.5).

[0012] The preparation method of the local high-concentration ionic liquid electrolyte comprises the following specific steps:

[0013] S1. mixing the ionic liquid and zinc bromide under a protective gas and stirring at 80-120°C to prepare an ionic liquid precursor;

[0014] S2. adding zinc fluoride to the ionic liquid precursor under a protective gas and stirring at 90-120°C to prepare an ionic liquid electrolyte;

[0015] S3. adding an organic co-solvent to the ionic liquid electrolyte under a protective gas and stirring at room temperature to prepare a local high-concentration ionic liquid electrolyte.

[0016] Preferably, the protective gas in steps S1-S3 is nitrogen, argon or helium.

[0017] Preferably, the stirring time in step S1 is 8-12h, the stirring time in step S2 is 10-12h, and the stirring time in step S3 is 1-5h.

[0018] A zinc tellurium battery for high voltage comprises a positive electrode, a negative electrode, a separator and the above-mentioned local high-concentration ionic liquid electrolyte.

[0019] Preferably, the positive electrode is ordered mesoporous carbon encapsulated tellurium composite material, the negative electrode is zinc sheet, and the separator is glass fiber.

[0020] More preferably, the ordered mesoporous carbon encapsulated tellurium composite material comprises mesoporous carbon and tellurium element loaded thereon.

[0021] Compared with the prior art, the above technical solution has the following beneficial effects:

[0022] 1. The local high-concentration ionic liquid electrolyte of the application is formed by adding an organic co-solvent to the ionic liquid electrolyte, and contains ionic liquid, Zn 2+ , F-, Br - and an organic co-solvent, and has high ionic conductivity (2.14 mS cm -1 ) compared with conventional ionic liquid electrolyte (<1 mS cm -1 ), which helps to further improve the reaction activity of Te 0 / Te 4+ , and improve the rate performance of zinc tellurium battery, and significantly improve the electrochemical performance.

[0023] 2. In the electrolyte of the application, the active species ZnBr4 2- can activate the positive valence conversion of tellurium, play the effect of exciting and stabilizing Te 0 / Te 4+ redox pair, so that the zinc tellurium battery has higher high-voltage platform (greater than (1.2V) and discharge capacity, and greatly improves the energy output of the tellurium positive electrode.

[0024] 3. The application improves the capacity ratio of high-voltage discharge platform of zinc tellurium battery to 80.6% by optimizing the proportion of ionic liquid, zinc bromide, zinc fluoride and organic co-solvent in the electrolyte, and improves the energy efficiency and rate performance of the zinc tellurium battery. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Raman spectrum of the electrolyte configured in Example 1 and Comparative Examples 1-3;

[0026] Figure 2 Ionic conductivity and viscosity diagram of the electrolyte configured in Example 1 and Comparative Examples 1-3;

[0027] Figure 3 Cyclic voltammetry curve diagram of the zinc tellurium battery assembled in Application Example 1 and Comparative Example 1;

[0028] Figure 4 Constant current charge-discharge curve diagram of the zinc tellurium battery assembled in Application Example 1 and Comparative Example 1;

[0029] Figure 5Charge-discharge curves and corresponding in-situ Raman spectra of the in-situ zinc telluride battery assembled for application example 1;

[0030] Figure 6 Charge-discharge curves of the zinc telluride battery assembled for application example 2;

[0031] Figure 7 Charge-discharge curves of the zinc telluride battery assembled for application example 3;

[0032] Figure 8 Cyclic voltammograms of the zinc telluride battery assembled for comparative examples 2 and 3;

[0033] Figure 9 Charge-discharge curves of the zinc telluride battery assembled for application example 1 and comparative example 3;

[0034] Figure 10 Rate performance of the zinc telluride battery assembled for application example 1 and comparative example 3. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. The embodiments described herein are only used to illustrate and explain the present application, and should not be understood as a limitation of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0036] Example 1

[0037] 1. Under argon protection, vacuum-dried pretreated 1-vinyl-3-butylimidazolium bromide (VBIMBr) and zinc bromide with a molar ratio of 1:1.2 were placed in a slurry bottle, slowly stirred at 100℃ for 12h, to prepare an ionic liquid precursor.

[0038] 2. Under argon protection, zinc fluoride with a molar ratio of 0.05:1 was added to the ionic liquid precursor, slowly stirred at 110℃ for 12h, to prepare an ionic liquid electrolyte;

[0039] 3. Under argon protection, dichloroethane with a molar ratio of 0.35:1 was added to the ionic liquid electrolyte, slowly stirred at room temperature for 4h, to prepare an electrolyte of local high-concentration ionic liquid.

[0040] Example 2

[0041] 1. Under helium protection, vacuum-dried pretreated 1-vinyl-3-butylimidazolium bromide (VBIMBr) and zinc bromide with a molar ratio of 1:1 were placed in a slurry bottle, slowly stirred at 110℃ for 12h, to prepare an ionic liquid precursor.

[0042] 2. Under the protection of helium, zinc fluoride with a molar ratio of 0.1:1 was added into the ionic liquid precursor, and slowly stirred at 110℃ for 12h to obtain an ionic liquid electrolyte;

[0043] 3. Under the protection of helium, dichloromethane with a molar ratio of 0.1:1 was added into the ionic liquid electrolyte, and slowly stirred at room temperature for 4h to obtain an electrolyte of partially high-concentration ionic liquid.

[0044] Example 3

[0045] 1. Under the protection of nitrogen, vacuum-dried pre-processed 1-vinyl-3-butyl imidazolium bromide (VBIMBr) and zinc bromide with a molar ratio of 1:1.5 were placed in a slurry bottle, and slowly stirred at 120℃ for 12h to obtain an ionic liquid precursor.

[0046] 2. Under the protection of nitrogen, zinc fluoride with a molar ratio of 0.05:1 was added into the ionic liquid precursor, and slowly stirred at 110℃ for 12h to obtain an ionic liquid electrolyte;

[0047] 3. Under the protection of nitrogen, dichloropropane with a molar ratio of 0.5:1 was added into the ionic liquid electrolyte, and slowly stirred at room temperature for 4h to obtain an electrolyte of partially high-concentration ionic liquid.

[0048] Comparative Example 1

[0049] 1. Under the protection of argon, vacuum-dried pre-processed 1-vinyl-3-butyl imidazolium bromide (VBIMBr) and zinc bromide with a molar ratio of 1:1.2 were placed in a slurry bottle, and slowly stirred at 100℃ for 12h to obtain an ionic liquid precursor.

[0050] 2. Under the protection of argon, zinc fluoride with a molar ratio of 0.05:1 was added into the ionic liquid precursor, and slowly stirred at 110℃ for 12h to obtain an ionic liquid electrolyte.

[0051] Under the protection of argon, Te@CMK-3, SuperP and PVDF with a mass ratio of 8:1:1 were coated on a titanium mesh to obtain a Te@CMK-3 electrode; under the protection of helium, the ionic liquid electrolyte obtained in Comparative Example 1 was used as an electrolyte, the Te@CMK-3 electrode was used as a cathode, and a zinc sheet was used as an anode to assemble a zinc tellurium battery, which was abbreviated as VB-Br / F.

[0052] Comparative Example 2

[0053] The difference from Comparative Example 1 is that the zinc salt in step 1 is zinc chloride, and the remaining steps are the same. A zinc tellurium battery was assembled, which was abbreviated as VB-Cl / F.

[0054] Comparative Example 3

[0055] The difference from Example 1 is that the zinc salt in Step 1 is zinc chloride, and the rest of the steps are the same, assemble zinc tellurium battery, abbreviated as VB-Cl / F-EDC.

[0056] Figure 1 The Raman spectrum of the electrolyte configured for Example 1 and Comparative Examples 1-3. It can be seen from Figure 1 that Example 1 and Comparative Example 1 provide active species ZnBr4 2- , while Comparative Examples 2-3 provide ZnCl4 2- . Since the active species ZnBr4 2- is more effective than ZnCl4 0 , the activation of Te 4+ is more effective than ZnCl4 2- . Therefore, the high-voltage discharge capacity of Example 1 and Comparative Example 1 is higher than that of Comparative Examples 2-3. Figure 2 The ion conductivity and viscosity of the electrolyte configured for Example 1 and Comparative Examples 1-3. It can be seen from Figure 2 that Example 1 has the highest ion conductivity and the lowest viscosity, indicating that the addition of the organic co-solvent dichloroethane (EDC), zinc bromide and zinc fluoride improves the ion conductivity of the electrolyte and reduces its viscosity.

[0057] Application Example 1

[0058] 1. Mix CMK-3 and Te powder in a mass ratio of 1:2 in isopropanol with a wet ball mill at 400 r / min for 10 h, evaporate the isopropanol in air at 60°C, then vacuum seal the tube under a pressure of 10 MPa, and then heat treat in a sealed quartz tube under argon at 600°C for 10 h to obtain a Te@CMK-3 composite material.

[0059] 2. Under argon protection, coat the ordered mesoporous carbon encapsulated tellurium composite material (Te@CMK-3), SuperP and PVDF on a titanium mesh in a mass ratio of 8:1:1 to obtain a Te@CMK-3 electrode sheet;

[0060] 3. Under argon protection, use the partial high-concentration ionic liquid obtained in Example 1 as the electrolyte, the Te@CMK-3 electrode sheet as the cathode, and a zinc sheet as the anode to assemble a zinc tellurium battery, abbreviated as VB-Br / F-EDC.

[0061] Figure 3 The cyclic voltammogram of the zinc tellurium battery assembled for Application Example 1 and Comparative Example 1. It can be seen from Figure 3 that the zinc tellurium battery of Application Example 1 exhibits a larger response current at 0.2 mVs -1 . Figure 4 The constant current charge-discharge curve of the zinc tellurium battery assembled for Application Example 1 and Comparative Example 1. It can be seen from Figure 4 that the zinc tellurium battery of Application Example 1 exhibits a larger response current at 0.1 Ag -1The discharge capacity of the zinc-tellurium battery in application example 1 can reach 667 mAh g -1 , and the discharge proportion of the high-voltage platform is increased to 80.6%. Figure 5 The charge-discharge curve and the corresponding in-situ Raman spectrum of the in-situ zinc-tellurium battery assembled in application example 1 are shown in Figure 6. Figure 5 It can be seen from Figure 6 that Te in the zinc-tellurium battery assembled in application example 1 is Te 4+ / Te and Te / Te 2- two-step conversion reaction.

[0062] Application Example 2

[0063] 1. Under the protection of helium, Te@CMK-3, SuperP and PVDF with a mass ratio of 8:1:1 were coated on the titanium mesh to prepare Te@CMK-3 electrode sheets;

[0064] 2. Under the protection of helium, the zinc-tellurium battery was assembled using the local high-concentration ionic liquid electrolyte obtained in example 2 as the electrolyte, the Te@CMK-3 electrode sheet as the cathode, and zinc sheet as the anode.

[0065] Figure 6 The constant current charge-discharge curve of the zinc-tellurium battery assembled in application example 2 is shown in Figure 8. Figure 6 It can be seen from Figure 8 that the zinc-tellurium battery in application example 2 has a discharge capacity of 358 mAh g -1 at 0.2 mV s -1 , and the discharge proportion of the high-voltage platform is 70.9%.

[0066] Application Example 3

[0067] 1. Under the protection of nitrogen, Te@CMK-3, SuperP and PVDF with a mass ratio of 8:1:1 were coated on the titanium mesh to prepare Te@CMK-3 electrode sheets;

[0068] 2. Under the protection of nitrogen, the zinc-tellurium battery was assembled using the local high-concentration ionic liquid electrolyte obtained in example 3 as the electrolyte, the Te@CMK-3 electrode sheet as the cathode, and zinc sheet as the anode.

[0069] Figure 7 The constant current charge-discharge curve of the zinc-tellurium battery assembled in application example 3 is shown in Figure 10. Figure 7 It can be seen from Figure 10 that the zinc-tellurium battery in application example 3 has a discharge capacity of 562 mAh g -1 at 0.2 mV s -1 , and the discharge proportion of the high-voltage platform is 80.3%. Figure 8 The cyclic voltammogram of the zinc-tellurium battery assembled in comparative examples 2 and 3 is shown in Figure 11. Figure 8 It can be seen from Figure 11 that the zinc-tellurium battery in comparative example 3 shows a larger response current at 0.2 mV s -1 .Figure 9 The constant current charge-discharge curves of the zinc-tellurium batteries assembled for application example 1 and comparative example 3 are shown in FIG. 2. It can be seen from FIG. 2 that application example 1 exhibits higher discharge capacity at a current density of 0.1 Ag-1, and the high-voltage discharge plateau of application example 1 accounts for as high as 80.6%, which is much higher than 56.4% of comparative example 3. Figure 9 -1 The rate performance of the zinc-tellurium batteries assembled for application example 1 and comparative example 3 is shown in FIG. 3. It can be seen from FIG. 3 that the rate performance of application example 1 is superior to that of comparative example 3, and the battery capacity is 563, 454, 375, 294, 187 and 102 mAh g-1 at a current density of 0.2, 0.5, 0.7, 1.0, 2.0 and 5.0 Ag-1, respectively. Figure 10 Figure 10 -1 -1 The excellent rate performance of the zinc-tellurium battery assembled for application example 1 reflects its faster kinetics.

[0070] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement modes, and all shall be included in the protection scope of the present application.​​​​

Claims

1. An electrolyte for a zinc telluride battery of localized high-concentration ionic liquid, characterized in that, The electrolyte comprises an ionic liquid, zinc bromide, zinc fluoride and an organic co-solvent; the ionic liquid is one or more of 1-vinyl-3-butyl imidazolium bromide, 1-ethyl-3-methyl imidazolium bromide, 1-propyl-3-methyl imidazolium bromide or 1-butyl-3-methyl imidazolium bromide; the molar ratio of the ionic liquid, zinc bromide, zinc fluoride and the organic co-solvent is 1:(1-1.8):(0.05-0.1):(0.1-0.5).

2. The electrolyte of partially high-concentrated ionic liquid for zinc tellurium battery according to claim 1, characterized in that, The organic co-solvent is one or more of dichloromethane, dichloroethane, dichloropropane, trichloromethane, fluorobenzene, toluene or p-xylene.

3. Process for the preparation of a local high-concentration ionic liquid electrolyte for zinc-tellurium batteries according to claim 1 or 2, characterized in that, The method comprises the following specific steps: S1. mixing the ionic liquid and zinc bromide under a protective gas and stirring at 80-120℃ to prepare an ionic liquid precursor; S2. adding zinc fluoride to the ionic liquid precursor under a protective gas and stirring at 90-120℃ to prepare an ionic liquid electrolyte; S3. adding an organic co-solvent to the ionic liquid electrolyte under a protective gas and stirring at room temperature to prepare a local high-concentration ionic liquid electrolyte for a zinc-tellurium battery.

4. The process for the preparation of a local high-concentrated ionic liquid electrolyte for zinc-tellurium batteries according to claim 3, characterized by, The protective gas in steps S1-S3 is nitrogen, argon or helium.

5. The process for the preparation of a local high-concentrated ionic liquid electrolyte for zinc-tellurium batteries according to claim 3, characterized by, The stirring time in step S1 is 8-12h, the stirring time in step S2 is 10-12h and the stirring time in step S3 is 1-5h.

6. A zinc-tellurium battery having a high voltage, characterized by The zinc-tellurium battery comprises a positive electrode, a negative electrode, a separator and the local high-concentration ionic liquid electrolyte of claim 1 or 2.

7. The zinc-tellurium cell with high voltage according to claim 6, characterized in that, The positive electrode is an ordered mesoporous carbon encapsulated tellurium composite material, the negative electrode is a zinc sheet and the separator is glass fiber.

8. The zinc-tellurium cell with high voltage according to claim 7, characterized in that, The ordered mesoporous carbon encapsulated tellurium composite material comprises mesoporous carbon and tellurium loaded thereon.

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