A slurry-type manganese positive electrode electrolyte for liquid flow battery

Abstract

The present invention provides a slurry-type manganese positive electrode electrolyte for a liquid flow battery, which belongs to the field of electrochemical energy storage technology. The slurry-type manganese positive electrode electrolyte for a liquid flow battery includes a manganese salt, an additive and an acid; the additive is a tetravalent zirconium salt. In the present invention, zirconium ions are added to the electrolyte. In the process of oxidizing divalent manganese ions to form manganese dioxide, the zirconium ions can improve the morphology and surface state of manganese dioxide deposited particles, so that they will not adhere to the current collector or the inner wall of the circulation pipe, improve their reaction activity, and thus significantly increase the discharge capacity, cycle stability and coulomb efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical energy storage, and in particular to a slurry-type manganese positive electrode electrolyte for a liquid flow battery. Background Art

[0002] Aqueous flow batteries have the advantages of high safety, structural flexibility (energy and power can be designed separately), and long design life. They are one of the most promising technologies for large-scale energy storage. The systems that are currently widely studied are all-vanadium flow batteries and zinc-bromine flow batteries. However, the positive electrode reaction of all-vanadium flow batteries is a redox reaction of tetravalent vanadium to pentavalent vanadium, and this type of high-valent vanadium is highly toxic. The positive electrode reaction of zinc-bromine batteries is a redox reaction of bromine element and bromine anions. Bromine is volatile and corrosive, and is very harmful to the human body. In addition, the high cost of the above two types of batteries also hinders their further development. Therefore, there is an urgent need to develop high-safety and low-cost positive electrode electrolyte materials for flow batteries.

[0003] Manganese-based electrode materials are low-cost, non-toxic and safe, and are ideal positive electrode materials. At present, the manganese positive electrode reaction in liquid flow batteries mainly involves the electrochemical oxidation of divalent manganese to trivalent manganese. Trivalent manganese is very unstable and further undergoes a disproportionate reaction to produce manganese dioxide. The manganese dioxide produced has poor activity and will adhere firmly to the inner wall of the current collector and the flow pipe, which not only limits the deposition capacity, but also forms dead manganese, consumes active manganese ions, and causes the capacity to decay rapidly. In order to reduce dead manganese, researchers have developed titanium ions as a stabilizer for trivalent manganese to inhibit its disproportionate reaction. On the other hand, some redox media have also been found to dissolve dead manganese, such as Fe 2+ ,Br - , I - However, the reaction between the manganese dioxide and the residual manganese dioxide is incomplete, and the problems of low deposition capacity, low coulombic efficiency and poor cycle life cannot be effectively solved. Therefore, it is necessary to develop a new type of manganese positive electrode for liquid flow batteries, so that the manganese dioxide formed during the oxidation process will not adhere to the current collector and the inner wall of the flow pipe, but flow with the liquid to increase the deposition capacity and discharge capacity, cycle stability and coulombic efficiency. Summary of the invention

[0004] In order to solve the problems that the manganese dioxide generated by the current manganese dioxide deposition / dissolution positive electrode electrolyte during the charging process is poorly active, adheres to the inner wall of the current collector and the flow pipe, reduces the deposition capacity while consuming active manganese ions, causing the capacity to decay rapidly, etc., the purpose of the present invention is to provide a mud-type manganese positive electrode electrolyte for liquid flow batteries.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is a slurry-type manganese positive electrode electrolyte for a liquid flow battery, wherein the electrolyte comprises a manganese salt, an additive and an acid; the additive is a tetravalent zirconium salt.

[0007] The second technical solution of the present invention is a liquid flow battery, comprising a manganese positive electrode and the above-mentioned mud-type manganese positive electrode electrolyte.

[0008] The present invention discloses the following technical effects:

[0009] The present invention adds zirconium ions to the manganese positive electrode electrolyte. The tetravalent zirconium ions can improve the morphology and surface state of the generated manganese dioxide particles during the oxidation process of the divalent manganese ions (i.e., the charging process), so that the particles exist in a stable suspended slurry state and will not adhere to the collector or the inner wall of the circulation pipe. At the same time, during the discharge process, the zirconium ions can promote the reduction and dissolution process of manganese dioxide, so that it is fully dissolved. The manganese positive electrode electrolyte containing zirconium ions significantly improves the cycle stability and reversibility of the manganese liquid flow positive electrode.

[0010] The slurry-type manganese positive electrode electrolyte provided by the present invention has high stability and high reversibility, the coulomb efficiency can reach 99%, and the number of cycles is greater than 1000. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 This is a discharge state diagram of the manganese positive electrode electrolyte in Example 1 of the present invention after 100 cycles.

[0013] Figure 2 The manganese positive electrode electrolyte and the tin negative electrode electrolyte in Example 1 of the present invention are matched to form a charge and discharge curve of a manganese-tin liquid flow battery after 100 cycles.

[0014] Figure 3 The manganese positive electrode electrolyte and the tin negative electrode electrolyte in Example 1 of the present invention are matched to form the cycle performance of the manganese-tin liquid flow battery.

[0015] Figure 4 This is a discharge state diagram of the manganese positive electrode electrolyte in Comparative Example 1 of the present invention after 90 cycles.

[0016] Figure 5 The manganese positive electrode electrolyte and the tin negative electrode electrolyte in Comparative Example 1 of the present invention are matched to form a charge and discharge curve of a manganese-tin liquid flow battery after 90 cycles.

[0017] Figure 6 The manganese positive electrode electrolyte and the tin negative electrode electrolyte obtained in Comparative Example 1 of the present invention are matched to form the cycle performance of the manganese-tin liquid flow battery. DETAILED DESCRIPTION

[0018] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0019] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0020] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0021] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0022] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0023] A first aspect of the present invention provides a slurry-type manganese positive electrode electrolyte for a liquid flow battery, wherein the electrolyte comprises a manganese salt, an additive and an acid; and the additive is a tetravalent zirconium salt.

[0024] The reaction of the conventional manganese positive electrode electrolyte during the charging process is an oxidation process of divalent manganese ions, generating manganese dioxide and trivalent manganese ions, in which the electrolyte gradually changes from a transparent solution state to a slurry state; the reaction during the discharge process is an electroreduction process of manganese dioxide and trivalent manganese ions, generating divalent manganese ions, but because the generated manganese dioxide will adhere to the inner wall of the current collector and the circulation pipe, and the reaction activity is low, the electrolyte cannot change from the slurry state back to a transparent state during the discharge process. The additive in the present invention can improve the morphology and surface state of the manganese dioxide particles, so that it exists in a stable suspended slurry state, and will not adhere to the current collector or the inner wall of the circulation pipe, so that the electrolyte can gradually change from a slurry state to a transparent state during the discharge process, improve its reaction activity, and then increase the reversible charge and discharge capacity, cycle stability and coulomb efficiency.

[0025] In some embodiments of the present invention, the tetravalent zirconium salt is at least one of zirconium sulfate, zirconium acetate, zirconium propionate, zirconium chloride, zirconium oxychloride, zirconium nitrate, zirconium citrate, potassium fluorozirconate, sodium fluorozirconate, zirconium methacrylate and zirconium isooctanoate.

[0026] In some embodiments of the present invention, the concentration of the additive in the electrolyte is 0.01-2 M.

[0027] In some embodiments of the present invention, the concentration of the additive in the electrolyte is 0.2-0.5 M.

[0028] In some embodiments of the present invention, the manganese salt includes at least one of manganese sulfate, manganese chloride, manganese nitrate, manganese acetate, manganese methanesulfonate and manganese oxalate.

[0029] In some embodiments of the present invention, the concentration of manganese salt in the electrolyte is 0.1-2 M.

[0030] In some embodiments of the present invention, the concentration of manganese salt in the electrolyte is 0.2-0.5 M.

[0031] In some embodiments of the present invention, the acid is an organic acid or an inorganic acid; and the concentration of the acid in the electrolyte is 0.5-6 M.

[0032] In some embodiments of the present invention, the inorganic acid is at least one of sulfuric acid, hydrochloric acid and nitric acid; the organic acid is at least one of methanesulfonic acid, aminosulfonic acid, benzenesulfonic acid and phenolsulfonic acid.

[0033] In some embodiments of the present invention, the electrolyte further includes a solvent.

[0034] In some embodiments of the present invention, the solvent is water.

[0035] A second aspect of the present invention provides a liquid flow battery comprising a manganese positive electrode and the above-mentioned mud-type manganese positive electrode electrolyte.

[0036] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0037] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0038] The solvent of the electrolyte in the embodiments is water.

[0039] The test method involved in the embodiment of the present invention is: the charge and discharge current density is 40 mA cm -2 , constant current charging to 43mAh cut off, and discharge to 0V cut off.

[0040] Example 1

[0041] This embodiment provides a flow battery, the positive electrode current collector is carbon felt, the electrolyte is 0.2M manganese sulfate + 3M sulfuric acid + 0.2M zirconium sulfate; the negative electrode current collector is carbon felt, the electrolyte is 3M sulfuric acid + 0.2M tin sulfate; the separator is a proton exchange membrane. The voltage of the manganese-tin full battery is about 1.6V. The discharge state of the manganese positive electrolyte after 100 cycles is as follows Figure 1 As shown in Figure 2, the positive electrode electrolyte is a clear solution after discharge. The charge and discharge curves and cycle performance are shown in Figure 2. Figure 2-Figure 3 As shown, the Coulomb efficiency can reach 99% and the number of cycles is greater than 1000.

[0042] Example 2

[0043] This embodiment provides a flow battery, wherein the positive electrode current collector is carbon felt, the electrolyte is 0.2 M manganese sulfate + 4 M sulfuric acid + 0.1 M zirconium sulfate + 0.1 M zirconium acetate; the negative electrode current collector is carbon felt, the electrolyte is 5 M sulfuric acid + 0.2 M tin sulfate; the diaphragm is a proton exchange membrane. The voltage of the manganese-tin full battery is about 1.6V, the efficiency can reach 99%, and the number of cycles is greater than 1000.

[0044] Example 3

[0045] This embodiment provides a flow battery, wherein the positive electrode current collector is carbon felt, the electrolyte is 0.3M manganese sulfate + 5M sulfuric acid + 0.3M zirconium chloride; the negative electrode current collector is carbon felt, the electrolyte is 0.5M copper sulfate + 5M sulfuric acid; and the diaphragm is a proton exchange membrane. The voltage of the manganese-copper full battery is about 1V, the coulomb efficiency can reach 99%, and the number of cycles is greater than 1000.

[0046] Example 4

[0047] This embodiment provides a flow battery, wherein the positive electrode current collector is carbon felt, the electrolyte is 0.2M manganese sulfate + 4M sulfuric acid + 0.2M zirconium nitrate; the negative electrode current collector is carbon felt, the electrolyte is 5M sulfuric acid + 0.5M silicotungstic acid; the diaphragm is a proton exchange membrane. The voltage of the manganese-silicotungstic acid full battery is about 1.2V, the coulomb efficiency can reach 99%, and the number of cycles is greater than 1000.

[0048] Comparative Example 1

[0049] This comparative example provides a flow battery, wherein the positive electrode current collector is carbon felt, the electrolyte is 0.2M manganese sulfate + 3M sulfuric acid; the negative electrode current collector is carbon felt, the electrolyte is 3M sulfuric acid + 0.2M tin sulfate; and the separator is a proton exchange membrane. The voltage of the manganese-tin full battery composed is about 1.5V. The discharge state of the manganese positive electrode electrolyte after 90 cycles is as follows Figure 4 As shown in Figure 2, there is a lot of manganese dioxide in the positive electrode electrolyte after discharge, indicating that manganese dioxide cannot be fully utilized. The charge and discharge curves and cycle performance are shown in Figure 2. Figure 5-Figure 6 As shown, the Coulomb efficiency is only 85% and decays rapidly after 70 cycles.

[0050] The above-described embodiments of the present invention mainly take manganese-tin, manganese-copper, and manganese-silicotungstate liquid flow batteries composed of tin, copper, silicotungstate negative electrodes and manganese positive electrodes as examples, and do not constitute a limitation on the protection scope of the present invention. Other liquid flow negative electrodes, such as vanadium negative electrodes, lead negative electrodes, etc., can be used to form corresponding liquid flow full batteries with the manganese positive electrode in the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A slurry-type manganese cathode electrolyte for a flow battery, characterized in that: The electrolyte includes a manganese salt, an additive and an acid; the additive is a tetravalent zirconium salt; The manganese salt includes at least one of manganese sulfate, manganese chloride, manganese nitrate, manganese acetate, manganese methanesulfonate and manganese oxalate; The concentration of the additive in the electrolyte is 0.01-2 M; The concentration of manganese salt in the electrolyte is 0.1-2 M.

2. The slurry-type manganese positive electrode electrolyte for a flow battery according to claim 1, characterized in that: The tetravalent zirconium salt is at least one of zirconium sulfate, zirconium acetate, zirconium propionate, zirconium chloride, zirconium oxychloride, zirconium nitrate, zirconium citrate, potassium fluorozirconate, sodium fluorozirconate, zirconium methacrylate and zirconium isooctanoate.

3. The slurry-type manganese positive electrode electrolyte for a flow battery according to claim 1, characterized in that: The acid is an organic acid or an inorganic acid; the concentration of the acid in the electrolyte is 0.5-6 M.

4. The slurry-type manganese positive electrode electrolyte for a flow battery according to claim 3, characterized in that: The inorganic acid is at least one of sulfuric acid, hydrochloric acid and nitric acid; the organic acid is at least one of methanesulfonic acid, aminosulfonic acid, benzenesulfonic acid and phenolsulfonic acid.

5. The slurry-type manganese positive electrode electrolyte for a flow battery according to claim 1, characterized in that: The electrolyte also includes a solvent.

6. The slurry-type manganese positive electrode electrolyte for a flow battery according to claim 5, characterized in that: The solvent is water.

7. A liquid flow battery, characterized in that: A manganese positive electrode and a slurry-type manganese positive electrode electrolyte for a flow battery according to any one of claims 1 to 6.

Images