All-vanadium redox flow battery, electrolyte and preparation method thereof

Abstract

The invention relates to the field of redox flow batteries, and discloses an electrolyte of an all-vanadium redox flow battery and a preparation method of the electrolyte. The all-vanadium redox flow battery electrolyte comprises VOSO4 and V2 (SO4) 3 with the total concentration of [VO < 2 + >] and [V < 3 + >] being 0.5-2.0 M, H2SO4 with the total concentration of 3.0-4.6 M and bismuth sulfate with the total concentration of 2-20 mM. The bismuth sulfate is added into the electrolyte component, so that the thermal stability of the basic electrolyte is improved.

Description

Technical Field

[0001] The present application relates to the field of liquid flow batteries, and in particular to electrolyte configuration and optimization technology for all-vanadium liquid flow batteries. Background Art

[0002] This section is intended to provide a background or context to the embodiments of the present application as recited in the claims. The description herein is not admitted to be prior art as disclosed by virtue of its inclusion in this section.

[0003] All-vanadium redox flow battery is the most mature type of flow battery in the field of flow battery. The reactions at the positive and negative electrodes are VO2 + / VO 2+ 、V 3+ / V 2+ Redox reaction. For liquid flow batteries, the solubility of the electrolyte active material and the number of electrons gained and lost determine the capacity of the liquid flow battery, and the electrolyte ion conductivity also affects the power and efficiency of the battery.

[0004] The earliest all-vanadium flow batteries used high-conductivity sulfuric acid solution as the supporting electrolyte. In order to improve the thermal stability of the vanadium electrolyte and prevent the precipitation of V2O5 during battery operation, researchers conducted a lot of research on the concentration ratio of vanadium and sulfuric acid in the electrolyte and the optimization of the supporting electrolyte. They also introduced a mixed acid system all-vanadium flow battery, which uses hydrochloric acid and sulfuric acid as the supporting electrolyte and obtains better cycle stability than sulfuric acid alone. However, in the existing technology, all-vanadium flow batteries still have the problem of poor thermal stability. Summary of the invention

[0005] The purpose of the present application is to provide an electrolyte for an all-vanadium liquid flow battery and a preparation method thereof, so as to solve the problem of poor thermal stability of the all-vanadium liquid flow battery.

[0006] The present application discloses an all-vanadium liquid flow battery electrolyte, comprising:

[0007] In the mixed solution of VOSO4 and V2(SO4)3 [VO 2+ ] and [V 3+ ] The total concentration is 0.5-2.0 M, 3.0-4.6 M H2SO4 and 2 to 20 mM bismuth sulfate.

[0008] In a preferred embodiment, it includes:

[0009] 1.7M VOSO4, 0.15M V2(SO4)3, 3M H2SO4 and 5mM bismuth sulfate.

[0010] In a preferred embodiment, it includes:

[0011] 0.5M VOSO4, 0.6M V2(SO4)3, 3.5M H2SO4 and 5mM bismuth sulfate.

[0012] The present application also discloses a method for preparing an electrolyte for an all-vanadium liquid flow battery, comprising:

[0013] Vanadyl sulfate is dissolved in sulfuric acid to obtain a basic electrolyte, in which a mixed solution of VOSO4 and V2(SO4)3 [VO 2+ ] and [V 3+ ] is 0.5-2.0M in total concentration, and H2SO4 is 3.0-4.6M;

[0014] The bismuth sulfate powder is dissolved in the basic electrolyte, and the content of bismuth sulfate in the obtained electrolyte is 2 to 20 mM.

[0015] The present application also discloses an all-vanadium liquid flow battery, wherein the electrolyte of the battery comprises a mixed solution of VOSO4 and V2(SO4)3 [VO 2+ ] and [V 3+ ] The total concentration is 0.5-2.0 M, 3.0-4.6 M H2SO4 and 2 to 20 mM bismuth sulfate.

[0016] In a preferred embodiment, the separator of the battery is a Nafion series proton exchange membrane or ion exchange membrane.

[0017] In the embodiment of the present application, by adding bismuth sulfate to the electrolyte components, the thermal stability and high capacity retention rate of the basic electrolyte are improved. This modification method has the following advantages:

[0018] (1) The electrolyte preparation process is simple, and bismuth sulfate can be directly dissolved in the electrolyte.

[0019] (2) The addition of bismuth ions will not participate in the electrode reaction as an active substance. At the same time, at a high potential of 1.0-1.4V, the addition of bismuth ions can slightly inhibit the oxygen evolution reaction.

[0020] (3) Reduced the operation and maintenance costs of all-vanadium liquid flow batteries and improved economic benefits.

[0021] Each technical feature disclosed in the above invention content, each technical feature disclosed in each implementation mode and example below, and each technical feature disclosed in the drawings can be freely combined with each other to form various new technical solutions (these technical solutions should be deemed to have been recorded in this specification), unless such combination of technical features is technically infeasible. For example, in one example, feature A+B+C is disclosed, and in another example, feature A+B+D+E is disclosed, and features C and D are equivalent technical means that play the same role. Technically, only one of them can be used, and it is impossible to use them at the same time. Feature E can be combined with feature C technically. Then, the solution of A+B+C+D should not be deemed to have been recorded because it is technically infeasible, while the solution of A+B+C+E should be deemed to have been recorded. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a method for preparing an electrolyte for an all-vanadium liquid flow battery and a schematic diagram of an all-vanadium liquid flow battery according to an embodiment of the present application. DETAILED DESCRIPTION

[0023] In the following description, many technical details are provided to help readers better understand the present application. However, those skilled in the art can understand that the technical solution claimed in the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0024] Some embodiments of the present application relate to an all-vanadium liquid flow battery electrolyte, comprising:

[0025] In the mixed solution of VOSO4 and V2(SO4)3 [VO 2+ ] and [V 3+ ] The total concentration is 0.5-2.0 M, 3.0-4.6 M H2SO4 and 2 to 20 mM bismuth sulfate.

[0026] In some embodiments, the electrolyte is a mixed solution of VOSO4 and V2(SO4)3 [VO 2+ ] and [V 3+ ] The total concentration is 0.5-2.0 M, 3.0-4.6 M H2SO4 and 2 to 20 mM bismuth sulfate.

[0027] In a preferred example, it includes: 1.7M VOSO4, 0.15M V2(SO4)3, 3M H2SO4 and 5mM bismuth sulfate.

[0028] In a preferred example, it includes: 0.5M VOSO4, 0.6M V2(SO4)3, 3.5M H2SO4 and 5mM bismuth sulfate.

[0029] Some embodiments of the present application relate to an all-vanadium liquid flow battery, wherein the electrolyte of the battery comprises a mixed solution of VOSO4 and V2(SO4)3 [VO 2+ ] and [V 3+ ] The total concentration is 0.5-2.0 M, 0.5-2.0 M VOSO4, 3.0-4.6 M H2SO4 and 2 to 20 mM bismuth sulfate.

[0030] In a preferred embodiment, the separator of the battery is a Nafion series proton exchange membrane.

[0031] In a preferred example, it includes: 1.7M VOSO4, 0.15M V2(SO4)3, 3M H2SO4 and 5mM bismuth sulfate.

[0032] In a preferred example, it includes: 0.5M VOSO4, 0.6M V2(SO4)3, 3.5M H2SO4 and 5mM bismuth sulfate.

[0033] In some embodiments of the present application, Figure 1 As shown, the method for preparing the electrolyte of the all-vanadium liquid flow battery comprises the following steps:

[0034] In step 101, vanadyl sulfate is dissolved in sulfuric acid to obtain a basic electrolyte, wherein the mixed solution of VOSO4 and V2(SO4)3 in the basic electrolyte has a concentration of [VO 2+ ] and [V 3+ The total concentration of ] is 0.5-2.0 M, and that of H2SO4 is 3.0-4.6 M. Optionally, the vanadyl sulfate can be fully dissolved in an ultrasonic disperser.

[0035] In step 102, bismuth sulfate powder is added to the prepared basic electrolyte so that the concentration of bismuth sulfate in the electrolyte is 2 to 20 mM. The bismuth sulfate powder must be fully mixed with the basic electrolyte to obtain a mixed electrolyte.

[0036] The mixed electrolyte can be directly assembled into a battery for electrochemical performance testing. Optionally, the battery separator is a Nafion series proton exchange membrane or ion exchange membrane.

[0037] The ingredients of some specific embodiments are as follows:

[0038]

[0039] For the specific embodiments in the above table, the battery was assembled and tested, and the selected diaphragm was Nafion212 proton exchange membrane. The test temperature was 25°C to 50°C. When the basic electrolyte without bismuth sulfate (1.7M VOSO4+0.15M V2(SO4)3+3M H2SO4 and 0.5M VOSO4+0.6M V2(SO4)3+3.5M H2SO4) was tested at room temperature, the capacity decayed to 75% after 100 charge and discharge cycles. The capacity decayed to 82% after 100 charge and discharge cycles for the 1.7M VOSO4+0.15M V2(SO4)3+3M H2SO4 and 0.5M VOSO4+0.6M V2(SO4)3+3.5M H2SO4 electrolytes with 5mM bismuth sulfate added. When tested at 45°C, the capacity decayed to 82% for the 1.7M VOSO4+0.15M V2(SO4)3+3M H2SO4 and 0.5M The capacity of VOSO4+0.6MV2(SO4)3+3.5M H2SO4 electrolyte decays to 70% after 100 charge and discharge cycles, and the capacity of 1.7M VOSO4+0.15M V2(SO4)3+3M H2SO4 and 0.5M VOSO4+0.6MV2(SO4)3+3.5M H2SO4 electrolytes with 5mM bismuth sulfate added decays to 76% after 100 charge and discharge cycles.

[0040] This specification includes combinations of the various embodiments described herein. Individual references to an embodiment (e.g., "one embodiment" or "some embodiments" or "preferred embodiments") do not necessarily refer to the same embodiment; however, these embodiments are not mutually exclusive unless indicated as mutually exclusive or it is clear to a person skilled in the art that they are mutually exclusive. It should be noted that the word "or" is used in this specification in a non-exclusive sense unless the context clearly indicates or requires otherwise.

[0041] All documents mentioned in this application are considered to be included in the disclosure of this application as a whole, so that they can be used as the basis for modification when necessary. In addition, it should be understood that after reading the content of this application, those skilled in the art can make various changes or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. An electrolyte for an all-vanadium redox flow battery, characterized in that: include: [VO 2+ ] and [V 3+ ] The total concentration is 0.5-2.0 M of VOSO4 and V2(SO4)3 mixed solution, 3.0-4.6 M of H2SO4 and 2 to 20 mM of bismuth sulfate.

2. The electrolyte of the all-vanadium redox flow battery according to claim 1, characterized in that: include: 1.7M VOSO4 and 0.15M V2(SO4)3, 3M H2SO4 and 5mM bismuth sulfate.

3. The electrolyte of the all-vanadium redox flow battery according to claim 1, characterized in that: include: 0.5M VOSO4 and 0.6M V2(SO4)3, 3.5M H2SO4 and 5mM bismuth sulfate.

4. A method for preparing an all-vanadium redox flow battery electrolyte, characterized in that: include: Vanadyl sulfate is dissolved in sulfuric acid to obtain a basic electrolyte, in which [VO 2+ ] and [V 3+ ]The total concentration is 0.5-2.0M, which is a mixed solution of VOSO4 and V2(SO4)3; The bismuth sulfate powder is dissolved in the basic electrolyte, and the content of bismuth sulfate in the obtained electrolyte is 2 to 20 mM.

5. The method for preparing an all-vanadium redox flow battery electrolyte according to claim 4, characterized in that: In the electrolyte, VOSO4 is 1.7M, V2(SO4)3 is 0.15M, H2SO4 is 3M, and bismuth sulfate is 5mM.

6. The method for preparing an all-vanadium redox flow battery electrolyte according to claim 4, characterized in that: In the electrolyte, VOSO4 is 0.5M, V2(SO4)3 is 0.6M, H2SO4 is 3.5M, and bismuth sulfate is 5mM.

7. An all-vanadium liquid flow battery, characterized in that: The electrolyte of the battery includes [VO 2+ ] and [V 3+ ] The total concentration is 0.5-2.0 M VOSO4 and V2(SO4)3, 3.0-4.6 M H2SO4 and 2 to 20 mM bismuth sulfate.

8. The all-vanadium redox flow battery according to claim 7, characterized in that: The separator of the battery is a Nafion series proton exchange membrane or ion exchange membrane.

9. The all-vanadium redox flow battery according to claim 7 or 8, characterized in that: In the electrolyte, VOSO4 is 1.7M, V2(SO4)3 is 0.15M, H2SO4 is 3M, and bismuth sulfate is 5mM.

10. The all-vanadium redox flow battery according to claim 7 or 8, characterized in that: In the electrolyte, VOSO4 is 0.5M, V2(SO4)3 is 0.6M, and bismuth sulfate is 5mM.

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