An electrolyte and its preparation method and application

Abstract

The embodiments of the present application relate to an electrolyte, a preparation method and an application thereof, and belong to the technical field of aqueous zinc ion batteries. The electrolyte of the embodiments of the present application includes an aqueous electrolyte, a solvent and an additive; wherein the additive is an acidic additive, and the aqueous electrolyte includes negative electrode metal ions that can be reduced and deposited as metals at the negative electrode during the charge and discharge process and the metal can be reversibly oxidized and dissolved. The embodiments of the present application use titanyl sulfate additives, which have the advantages of low price, environmental friendliness, and a wide range of applications; and its preparation method is simple, and can be widely used in various secondary battery systems.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of aqueous zinc ion batteries, and in particular to an electrolyte and a preparation method and application thereof. Background Art

[0002] Against the backdrop of the "dual carbon" goal, the global energy landscape has changed, and reliable clean energy needs to be developed. However, renewable energy is unstable and cannot achieve a sustained balance between supply and demand. Energy storage, as a convenient means of regulation, can address the above problems. Among secondary energy storage methods, lithium-ion batteries dominate the market due to their high energy density and power density, and are widely used in mobile devices, energy vehicles and other fields. With the use of lithium-ion batteries, their limitations are constantly exposed, including the shortage and high price of lithium resources, the flammability of organic electrolytes and other issues that limit their own development. It is necessary to develop a new generation of energy storage materials as alternatives. Among the many candidates, aqueous zinc-ion batteries have attracted widespread attention for their safety, low cost and high theoretical capacity.

[0003] In recent years, aqueous zinc-ion batteries have been developing continuously, but their large-scale application is still restricted by many restrictions. There are problems such as dendrites, passivation, corrosion, hydrogen evolution, etc. in the negative electrode, as well as dissolution and poor retention of active substances in the positive electrode material. The above problems are the main factors that lead to the low coulombic efficiency and poor cyclability of zinc-ion batteries and hinder their commercial development.

[0004] In response to these problems, people have proposed different solutions, such as surface coating, three-dimensional configuration, zinc alloy and high-concentration electrolyte. Although these methods can solve some outstanding problems, they are inconvenient to operate and have high costs. Summary of the invention

[0005] In view of this, the embodiments of the present application provide an electrolyte and a preparation method and application thereof. The electrolyte uses a trace amount of titanyl sulfate, has a simple process, is environmentally friendly, and enables an aqueous zinc ion battery to obtain high stability, high rate performance and long cycle life. It can effectively overcome the problems of dendrites, passivation, corrosion, hydrogen evolution, etc. in the negative electrode of the existing zinc ion battery, as well as the dissolution and poor retention rate of the active substances of the positive electrode material.

[0006] A first aspect of an embodiment of the present application provides an electrolyte solution, including an aqueous electrolyte, a solvent, and an additive;

[0007] The additive is an acidic additive, and the aqueous electrolyte includes negative electrode metal ions that can be reduced and deposited into metals at the negative electrode during the charge and discharge process, and the metal can be reversibly oxidized and dissolved.

[0008] The electrolyte additive is not only easy to operate and has low cost and high efficiency, but can also significantly improve the cycle stability of the battery and effectively regulate the deposition behavior of zinc ions. It is one of the important methods to solve the main problems currently existing in aqueous zinc ion batteries and promote their commercialization. The titanyl sulfate added in the embodiment of the present application is uniformly dissolved and distributed in the electrolyte, which can improve the cycle stability of the aqueous zinc ion battery and reduce the generation of by-products; regulate the deposition / stripping behavior of zinc ions and maintain a stable pH environment, which helps to inhibit the dendrite growth of the negative electrode of the aqueous zinc ion battery and slow down the attenuation of the positive electrode ammonium vanadate, and helps to improve the electrochemical performance of aqueous zinc ions.

[0009] In some embodiments, which may include the above embodiments, the additive is titanyl sulfate; or

[0010] The electrolyte is an acidic solution with a pH of 1.5-1.81.

[0011] In some embodiments, which may include the above embodiments, the solvent is deionized water; or

[0012] The negative electrode metal ion is a zinc ion; or

[0013] The aqueous electrolyte is a zinc ion salt.

[0014] In some embodiments that may include the above embodiments, the zinc ion salt is at least one of zinc trifluoromethanesulfonate, zinc sulfate, and zinc chloride; or

[0015] The zinc ion salt is zinc sulfate.

[0016] In some embodiments that may include the above embodiments, the molar concentration of the additive is 1 to 70 mmol / L; or

[0017] The molar concentration of the zinc ion salt is 2 mol / L; or

[0018] The volume molar concentration of the electrolyte is 1-3 mol / L.

[0019] A second aspect of the present application also provides a method for preparing the above-mentioned electrolyte, comprising the following steps:

[0020] The aqueous electrolyte and additives are dissolved in a solvent, and then stirred and mixed to obtain an electrolyte.

[0021] Preferably, the method comprises the following steps: weighing titanyl sulfate and adding it into a beaker, adding zinc sulfate solution, and adding a stirring magnet, stirring the mixture for 30-60 minutes to form a uniform solution, thereby obtaining an electrolyte.

[0022] In some embodiments that may include the above embodiments, the molar ratio of the aqueous electrolyte to the additive is 100:(0.5-3.5); or the stirring time is 30 to 60 minutes.

[0023] The third aspect of the embodiments of the present application also provides the use of the above-mentioned electrolyte in an aqueous zinc ion battery.

[0024] In some embodiments that may include the above embodiments, the aqueous zinc ion battery includes a positive electrode, a negative electrode and an electrolyte, and the electrolyte is the above electrolyte.

[0025] In some embodiments, which may include the above embodiments, the positive electrode is ammonium vanadate and the negative electrode is zinc metal.

[0026] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0027] (1) The present application uses titanyl sulfate as an additive, which has the advantages of low price, environmental friendliness, and wide application range; and its preparation method is simple and can be widely used in various secondary battery systems;

[0028] (2) The present application introduces a titanyl sulfate additive into the electrolyte, so that the desolvation energy barrier of the zinc metal negative electrode can be reduced during the cycle process to promote the nucleation and uniform deposition of zinc, thereby inhibiting the dendrite growth of the zinc negative electrode and solving the problem of short cycle life;

[0029] (3) The present application introduces a titanyl sulfate additive into the electrolyte, wherein the TiO 2+ It is an acidic medium, making the electrolyte a strong acid environment, which can maintain the stability of the pH value at the electrode-electrolyte interface. The stable pH value at the electrode-electrolyte interface can optimize the zinc ion deposition / stripping behavior and improve the cycle stability and rate performance of the aqueous zinc ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 The Zn / / Zn symmetric battery prepared by the electrolyte of Example 1 of the present application is at a current density of 1 mA.cm -2 The dough capacity is 1mAh.cm -2 Cycle performance diagram of

[0032] Figure 2The Zn / / Cu half-cell prepared by the electrolyte of Example 1 of the present application is at a current density of 5 mA.cm -2 The dough capacity is 1mAh.cm -2 cyclic coulomb efficiency diagram;

[0033] Figure 3 The full battery prepared by the electrolyte of Example 1 of this application is at 0.5Ag -1 Charge and discharge curves under current density;

[0034] Figure 4 The rate performance diagram of the full battery prepared with the electrolyte of Example 1 of the present application at different current densities;

[0035] Figure 5 The full battery prepared by the electrolyte of Example 1 of the present application is at 5A.g -1 Charge and discharge curves under current density;

[0036] Figure 6 The Zn / / Zn symmetric battery prepared by the electrolyte of Example 1 of the present application is at a current density of 5 mA.cm -2 The dough capacity is 1mAh.cm -2 Charge and discharge curves and in-situ pH monitoring diagram. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] Unless otherwise specified, the experimental methods used in the examples of this application are all conventional methods.

[0039] In the following examples and comparative examples, unless otherwise specified, all raw materials can be obtained by commercial purchase or conventional methods.

[0040] Example 1

[0041] This embodiment provides a method for preparing an electrolyte, and the electrolyte prepared by the method and a corresponding aqueous zinc ion battery.

[0042] The preparation of the electrolyte includes the following steps: weighing 0.048 g of titanyl sulfate with a volume molar concentration of 30 mmol / L, adding it to 10 ml of zinc sulfate solution with a volume molar concentration of 2 mol / L, stirring for 30-60 minutes to obtain an electrolyte with a volume molar concentration of 2 mol / L and a pH of 1.65.

[0043] The preparation of aqueous zinc-ion batteries includes the following steps: 4 V 4 O 10 The stainless steel foil is used as the positive electrode (the steps of making the positive electrode sheet are: ammonium vanadate (NH 4 V 4 O 10 ), Ketjen black, and polyvinylidene fluoride were weighed and mixed in a mass ratio of 7:2:1, and after sufficient grinding, a small amount of N-methylpyrrolidone (NMP) was added to form a uniform black paste slurry. The slurry was coated on a stainless steel foil and vacuum dried to obtain NH 4 V 4 O 10 A zinc sheet is used as a positive electrode, a glass fiber is used as a separator, and the electrolyte is the electrolyte with a volume molar concentration of 2 mol / L prepared as above, and a button zinc ion battery is assembled.

[0044] The prepared button zinc ion battery was tested for electrochemical performance using an electrochemical workstation, and the test results are as follows:

[0045] Figure 1 The Zn / / Zn symmetric cell assembled with the electrolyte obtained in this example and containing titanyl sulfate additive was used at a current density of 1 mA.cm -2 The dough capacity is 1mAh.cm -2 The cycle performance diagram below. When the electrolyte contains titanyl sulfate additive, the zinc symmetric battery shows better stability during cycling and has a greatly improved lifespan, and can work stably for more than 3750 hours.

[0046] Figure 2 The figure shows the Zn / / Cu battery assembled with the electrolyte obtained in this example containing titanyl sulfate additive at a current density of 5 mA.cm -2 The dough capacity is 1mAh.cm -2 The cyclic coulombic efficiency diagram below. When the electrolyte contains titanyl sulfate additive, the zinc-copper asymmetric battery shows better stability and reversibility during cycling, and the average coulombic efficiency of the battery assembled with the electrolyte containing titanyl sulfate additive is as high as 99.77%.

[0047] Figure 3 The full battery assembled with the electrolyte obtained in this example containing titanyl sulfate additive is at 500mA.g-1 The discharge capacity can still be maintained at 276.4 mAh g after 100 cycles at the current density. -1 , showing good cycle stability performance.

[0048] Figure 4 The figure is a rate performance diagram of a full battery assembled with the electrolyte obtained in this example and containing titanyl sulfate additive at different current densities. It can be seen from the figure that the battery assembled with the electrolyte containing titanyl sulfate additive has excellent rate performance. -1 It can still maintain 198.3mAh.g under high current discharge conditions -1 The discharge capacity is 200 mA.g -1 After that, the discharge capacity can reach 272.2 mAh.g again. -1 .

[0049] Figure 5 The full battery assembled with the electrolyte obtained in this example containing titanyl sulfate additive is at 5000mA.g -1 The discharge capacity can still be maintained at 207.9 mAh g after 1000 cycles at the current density. -1 The capacity retention rate is 88.2%, showing good long-cycle stability. This shows that titanyl sulfate enhances the stability of the full battery and this additive has practical applicability.

[0050] Figure 6 The Zn / / Zn symmetric cell assembled with the electrolyte obtained in this example and containing titanyl sulfate additive was used at a current density of 5 mA.cm -2 The dough capacity is 1mAh.cm -2 The cycle performance diagram under the condition of 1.5 ℃ and 2.5 ℃ was obtained, and the pH change during the charge and discharge process was monitored in real time using a pH probe. After 48 hours of cycling, the pH value increased from 1.65 to 1.81, maintaining a stable pH environment. This shows that the additive is an excellent pH buffer.

[0051] Example 2

[0052] This embodiment provides a method for preparing an electrolyte, and the electrolyte prepared by the method and a corresponding aqueous zinc ion battery.

[0053] The preparation of the electrolyte includes the following steps: weighing 0.016 g of titanyl sulfate with a volume molar concentration of 10 mmol / L, adding it to 10 ml of zinc sulfate solution with a volume molar concentration of 2 mol / L, stirring for 30-60 minutes to obtain an electrolyte with a volume molar concentration of 2 mol / L and a pH of 1.81.

[0054] The preparation of aqueous zinc-ion batteries includes the following steps: 4 V 4 O 10 The stainless steel foil is used as the positive electrode (the steps of making the positive electrode sheet are: ammonium vanadate (NH 4 V 4 O 10 ), Ketjen black, and polyvinylidene fluoride were weighed and mixed in a mass ratio of 7:2:1, and after sufficient grinding, a small amount of N-methylpyrrolidone (NMP) was added to form a uniform black paste slurry. The slurry was coated on a stainless steel foil and vacuum dried to obtain NH 4 V 4 O 10 A zinc sheet is used as a positive electrode, a glass fiber is used as a separator, and the electrolyte is the electrolyte with a volume molar concentration of 2 mol / L prepared as above, and a button zinc ion battery is assembled.

[0055] The electrolyte prepared in this example was used to assemble a button-type zinc ion battery. -1 The discharge capacity can still be maintained at 270.1 mAh g after 100 cycles at the current density. -1 .

[0056] Example 3

[0057] This embodiment provides a method for preparing an electrolyte, and the electrolyte prepared by the method and the corresponding aqueous zinc ion battery.

[0058] The preparation of the electrolyte includes the following steps: weighing 0.032 g of titanyl sulfate with a volume molar concentration of 20 mmol / L, adding it to 10 ml of zinc sulfate solution with a volume molar concentration of 2 mol / L, stirring for 30-60 minutes to obtain an electrolyte with a volume molar concentration of 2 mol / L and a pH of 1.78.

[0059] The preparation of aqueous zinc-ion batteries includes the following steps: 4 V 4 O 10 The stainless steel foil is used as the positive electrode (the steps of making the positive electrode sheet are: ammonium vanadate (NH 4 V 4 O 10 ), Ketjen black, and polyvinylidene fluoride were weighed and mixed in a mass ratio of 7:2:1, and after sufficient grinding, a small amount of N-methylpyrrolidone (NMP) was added to form a uniform black paste slurry. The slurry was coated on a stainless steel foil and vacuum dried to obtain NH 4 V 4 O 10A zinc sheet is used as a positive electrode, a glass fiber is used as a separator, and the electrolyte is the electrolyte with a volume molar concentration of 2 mol / L prepared as above, and a button zinc ion battery is assembled.

[0060] The electrolyte prepared in this example was used to assemble a button-type zinc ion battery. -1 At this current density, the discharge capacity can still be maintained at 275.8 mAh g after 100 cycles. -1 .

[0061] Example 4

[0062] This embodiment provides a method for preparing an electrolyte, and the electrolyte prepared by the method and a corresponding aqueous zinc ion battery.

[0063] The preparation of the electrolyte includes the following steps: weighing 0.08 g of titanyl sulfate with a volume molar concentration of 50 mmol / L, adding it to 10 ml of zinc sulfate solution with a volume molar concentration of 2 mol / L, stirring for 30-60 minutes to obtain an electrolyte with a volume molar concentration of 2 mol / L and a pH of 1.56.

[0064] The preparation of aqueous zinc-ion batteries includes the following steps: 4 V 4 O 10 The stainless steel foil is used as the positive electrode (the steps of making the positive electrode sheet are: ammonium vanadate (NH 4 V 4 O 10 ), Ketjen black, and polyvinylidene fluoride were weighed and mixed in a mass ratio of 7:2:1, and after sufficient grinding, a small amount of N-methylpyrrolidone (NMP) was added to form a uniform black paste slurry. The slurry was coated on a stainless steel foil and vacuum dried to obtain NH 4 V 4 O 10 A zinc sheet is used as a positive electrode, a glass fiber is used as a separator, and the electrolyte is the electrolyte with a volume molar concentration of 2 mol / L prepared as above, and a button zinc ion battery is assembled.

[0065] The electrolyte prepared in this example was used to assemble a button-type zinc ion battery. -1 The discharge capacity can still be maintained at 276.4 mAh g after 100 cycles at the current density. -1 .

[0066] Example 5

[0067] This embodiment provides a method for preparing an electrolyte, and the electrolyte prepared by the method and the corresponding aqueous zinc ion battery.

[0068] The preparation of the electrolyte includes the following steps: weighing 0.112 g of titanyl sulfate with a volume molar concentration of 70 mmol / L, adding it to 10 ml of zinc sulfate solution with a volume molar concentration of 2 mol / L, stirring for 30-60 minutes to obtain an electrolyte with a volume molar concentration of 2 mol / L and a pH of 1.52.

[0069] The preparation of aqueous zinc-ion batteries includes the following steps: 4 V 4 O 10 The stainless steel foil is used as the positive electrode (the steps of making the positive electrode sheet are: ammonium vanadate (NH 4 V 4 O 10 ), Ketjen black, and polyvinylidene fluoride were weighed and mixed in a mass ratio of 7:2:1, and after sufficient grinding, a small amount of N-methylpyrrolidone (NMP) was added to form a uniform black paste slurry. The slurry was coated on a stainless steel foil and vacuum dried to obtain NH 4 V 4 O 10 A zinc sheet is used as a positive electrode, a glass fiber is used as a separator, and the electrolyte is the electrolyte with a volume molar concentration of 2 mol / L prepared as above, and a button zinc ion battery is assembled.

[0070] The electrolyte prepared in this example was used to assemble a button-type zinc ion battery. -1 The discharge capacity can still be maintained at 277.3 mAh g after 100 cycles at the current density. -1 .

[0071] Example 6

[0072] This embodiment can refer to Example 1, except that the zinc ion salt is zinc trifluoromethanesulfonate.

[0073] Example 7

[0074] This embodiment can refer to Example 1, except that the zinc ion salt is zinc chloride.

[0075] Comparative Example 1

[0076] This comparative example can refer to Example 1, except that no titanyl sulfate is added.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrolyte, characterized in that: including aqueous electrolytes, solvents and additives; Wherein, the additive is an acidic additive, and the aqueous electrolyte includes negative electrode metal ions that can be reduced and deposited into metal at the negative electrode during the charge and discharge process, and the metal can be reversibly oxidized and dissolved; The additive is titanyl sulfate; The electrolyte is an acidic solution with a pH of 1.5-1.81; The solvent is deionized water; the negative electrode metal ions are zinc ions.

2. The electrolyte according to claim 1, characterized in that The aqueous electrolyte is a zinc ion salt.

3. The electrolyte according to claim 2, characterized in that The zinc ion salt is at least one of zinc trifluoromethanesulfonate, zinc sulfate, and zinc chloride; or The zinc ion salt is zinc sulfate.

4. The electrolyte according to claim 2, characterized in that The molar concentration of the additive is 1 to 70 mmol / L; or The molar concentration of the zinc ion salt is 2 mol / L; or The volume molar concentration of the electrolyte is 1-3 mol / L.

5. A method for preparing the electrolyte according to any one of claims 1 to 4, characterized in that: The following steps are involved: The aqueous electrolyte and additives are dissolved in a solvent, and then stirred and mixed to obtain an electrolyte.

6. The method for preparing an electrolyte according to claim 5, characterized in that: The molar ratio of the aqueous electrolyte to the additive is 100:(0.5-3.5); or The stirring time is 30 to 60 minutes.

7. Use of the electrolyte as described in any one of claims 1 to 4 in an aqueous zinc ion battery.

8. The use according to claim 7, characterized in that: The aqueous zinc ion battery comprises a positive electrode, a negative electrode and an electrolyte, and the electrolyte is the electrolyte according to any one of claims 1 to 4.

9. The use according to claim 8, characterized in that: The positive electrode is ammonium vanadate, and the negative electrode is zinc metal.

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