Manganese positive electrode electrolyte and application thereof

Abstract

The invention relates to the technical field of electrochemical energy storage, in particular to a manganese positive electrode electrolyte and application thereof. The manganese positive electrode electrolyte comprises a divalent manganese salt, a solvent and a water-soluble small organic molecule redox reaction medium; the water-soluble small organic molecule redox reaction medium is at least one of hydroquinone, resorcinol and catechol. The manganese positive electrode electrolyte adopts water-soluble organic matter micromolecular benzenediol (hydroquinone, resorcinol or catechol) as a redox reaction medium, has the advantages of simple structure and low cost, not only has high reversibility, but also promotes the dissolution of manganese dioxide in the dissolution process, and the benzenediol structure carries protons, so that the manganese dioxide can be effectively dissolved in the electrolyte. The electrode can rapidly react with residual manganese dioxide, the reaction speed is high, the reaction is complete, and the coulombic efficiency and the cycle life of the manganese dioxide deposition / dissolution electrode are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical energy storage, and in particular to a manganese positive electrode electrolyte and application thereof. Background Art

[0002] Aqueous batteries are suitable for large-scale energy storage due to their high safety. Among them, manganese cathode has the advantages of large reserves, high potential, no pollution, and low cost, making it a very suitable cathode material for aqueous batteries. However, the traditional manganese oxide cathode material is an ion insertion and extraction mechanism, and the valence state change of manganese involves the single electron Mn 4+ / Mn 3+ The redox reaction not only has a low theoretical capacity, but also the manganese oxide is affected by the Jahn-Teller effect during the charge and discharge process, resulting in an unstable structure and rapid capacity decay. In recent years, the deposition / dissolution reaction of manganese dioxide has gradually attracted attention, but the deposition / dissolution reaction has the problems of low coulombic efficiency and poor cycle life. Although researchers have developed some redox mediators to promote the deposition / dissolution reaction of manganese dioxide, such as Fe 2+ ,Br - , I - However, the reaction rate with residual manganese dioxide is slow and the reaction is incomplete, which makes it unable to effectively solve the problem of low coulombic efficiency in the process of manganese dioxide deposition / dissolution. Therefore, it is necessary to develop a new redox reaction medium to effectively dissolve residual manganese dioxide and improve the electrochemical performance of manganese dioxide deposition / dissolution positive electrode electrolyte. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a manganese positive electrode electrolyte containing a water-soluble organic small molecule redox reaction medium and applications thereof.

[0004] To achieve the above object, the present invention provides the following solutions: One of the technical solutions of the present invention is a manganese positive electrode electrolyte, comprising a divalent manganese salt, an acid, a solvent and a water-soluble organic small molecule redox reaction medium; The water-soluble organic small molecule redox reaction medium is at least one of hydroquinone, resorcinol and catechol.

[0005] A second technical solution of the present invention is an aqueous battery, comprising a positive electrode current collector, a negative electrode current collector, a positive electrode electrolyte, a negative electrode electrolyte and a separator; The positive electrode electrolyte is the above-mentioned manganese positive electrode electrolyte.

[0006] The present invention discloses the following technical effects: The manganese positive electrode electrolyte uses water-soluble organic small molecule catechol (hydroquinone, resorcinol or catechol) as the redox reaction medium, which has the advantages of simple structure, low cost, and high reversibility. At the same time, it promotes the dissolution of manganese dioxide during its dissolution process. The protons in the catechol structure can react quickly with the residual manganese dioxide. The reaction speed is fast and the reaction is complete, which significantly improves the coulombic efficiency and cycle life of the manganese dioxide deposition / dissolution electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] 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.

[0008] Figure 1 The charge and discharge curve and cycle performance of the manganese-tin static battery in Example 1 of the present invention; wherein a is the charge and discharge curve after 100 cycles of the battery, and b is the cycle stability of the battery.

[0009] Figure 2 This is a SEM image of the positive electrode current collector of the manganese-tin static battery in Example 1 of the present invention after 100 cycles.

[0010] Figure 3 The charge and discharge curves and cycle performance of the manganese-tin liquid flow battery in Example 2 of the present invention; wherein a is the charge and discharge curve after 100 cycles of the battery, and b is the cycle stability of the battery.

[0011] Figure 4 The charge and discharge curves and cycle performance of the manganese-tin static battery in Comparative Example 1 of the present invention; a is the charge and discharge curve after the battery is cycled 70 times, and b is the cycle stability of the battery.

[0012] Figure 5 This is a SEM image of the positive electrode current collector of the manganese-tin static battery in Comparative Example 1 of the present invention after 70 cycles.

[0013] Figure 6 The charge and discharge curves and cycle performance of the manganese-tin liquid flow battery in Comparative Example 2 of the present invention; a is the charge and discharge curve after 70 cycles of the battery, and b is the cycle stability of the battery. DETAILED DESCRIPTION

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0019] The first aspect of the present invention provides a manganese positive electrode electrolyte, comprising a divalent manganese salt, an acid, a solvent and a water-soluble organic small molecule redox reaction medium; The water-soluble organic small molecule redox reaction medium is at least one of hydroquinone, resorcinol and catechol.

[0020] The water-soluble organic small molecule redox reaction medium has protons in its structure and can react quickly with residual manganese dioxide. The reaction speed is fast and the reaction is complete, which solves the problem of slow reaction between the current redox medium and residual manganese dioxide and low coulombic efficiency and poor cycle stability caused by incomplete reaction.

[0021] The manganese positive electrode electrolyte of the present invention can improve the manganese positive electrode (involving Mn 2+ / MnO 2 The water-soluble organic small molecule redox reaction medium has high reversibility and electrochemical reaction kinetics. At the same time, during the dissolution of manganese dioxide, hydroquinone can quickly and effectively reduce the residual manganese dioxide particles and increase the discharge capacity.

[0022] In some embodiments of the present invention, the concentration of the water-soluble organic small molecule redox reaction medium in the manganese positive electrode electrolyte is 0.01-0.5M.

[0023] In some embodiments of the present invention, the divalent manganese salt is at least one of manganese sulfate, manganese chloride, manganese nitrate, manganese acetate, manganese methanesulfonate, and manganese oxalate.

[0024] In some embodiments of the present invention, the concentration of the divalent manganese salt in the manganese positive electrode electrolyte is 0.1-3 M.

[0025] In some embodiments of the invention, the solvent is water.

[0026] In some embodiments of the present invention, the concentration of the acid in the manganese positive electrolyte is 0.5-5M.

[0027] In some embodiments of the present invention, the acid may be at least one of sulfuric acid, hydrochloric acid, nitric acid, methanesulfonic acid, acetic acid, and oxalic acid.

[0028] A second aspect of the present invention provides an aqueous battery, comprising a positive electrode current collector, a negative electrode current collector, a positive electrode electrolyte, a negative electrode electrolyte and a separator; The positive electrode electrolyte is the above-mentioned manganese positive electrode electrolyte.

[0029] In some embodiments of the present invention, the positive electrode current collector is carbon felt, carbon cloth, carbon paper, activated carbon electrode or mesh glassy carbon; the negative electrode current collector is carbon felt, carbon cloth, carbon paper or mesh glassy carbon, tin foil, tin mesh, tin-plated carbon felt, copper foil, copper mesh, foam copper, lead foil, lead mesh or lead-based alloy; In some embodiments of the present invention, when the aqueous battery is a manganese-tin battery, the negative electrode electrolyte is an electrolyte containing divalent tin ions; when the aqueous battery is a manganese-copper battery, the negative electrode electrolyte is an electrolyte containing divalent copper ions; when the aqueous battery is a manganese-lead battery, the negative electrode electrolyte is an electrolyte containing divalent lead ions.

[0030] When the aqueous battery is a manganese-tin battery, the manganese positive electrode reaction is Mn 2+ / MnO 2 Deposition / dissolution reaction, the tin cathode reaction is Sn 2+ / Sn deposition / dissolution reaction.

[0031] In some embodiments of the present invention, the aqueous battery is an electrolyte static battery (referred to as a static battery) or an electrolyte flow battery (ie, a flow battery).

[0032] In some embodiments of the present invention, the aqueous battery can be a manganese-tin static battery, a manganese-tin flow battery, a manganese-copper static battery, a manganese-copper flow battery, a manganese-lead static battery or a manganese-lead flow battery.

[0033] In the present invention, the membrane is an ion selective membrane, specifically, a proton exchange membrane such as a perfluorosulfonic acid membrane, a non-fluorinated polymer membrane or a polybenzimidazole membrane.

[0034] The present invention does not impose any particular limitation on the sources of the positive electrode current collector, the negative electrode current collector, the separator and the components in the electrolyte, and commercially available products known to those skilled in the art may be used.

[0035] 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.

[0036] The solvent of the electrolyte used in the examples of the present invention and the comparative examples is water.

[0037] The proton exchange membrane used in the examples and comparative examples of the present invention is a polybenzimidazole membrane.

[0038] The test method involved in the present invention is as follows: for a stationary battery, the charge and discharge current is 10 mA, the charge capacity is 0.5 mAh, the electrolyte utilization rate is 18%, and the discharge cut-off voltage is 0 V. For a flow battery, the charge and discharge current is 200 mA, the charge capacity is 63 mAh, the electrolyte utilization rate is 60%, and the discharge cut-off voltage is 0.25 V.

[0039] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention. Example 1

[0040] Static battery: The positive electrode current collector is carbon cloth, and the electrolyte is 1M manganese sulfate + 1M sulfuric acid + 0.2M hydroquinone; the negative electrode current collector is tin foil, and the electrolyte is 2M sulfuric acid + 0.2M tin sulfate; the separator is a proton exchange membrane. The charge and discharge curves and cycle performance are shown in Figure 2. Figure 1 As shown, a is the charge and discharge curve of the full battery, and b is the cycle stability of the battery. Figure 1 As can be seen in a, the full battery has small polarization and high cycle reversibility. Figure 1 As can be seen in Figure b, the coulombic efficiency can reach 99.9%, the number of cycles is greater than 2000, and the discharge capacity is very stable at ~0.5 mAh. After charging and discharging, the battery is disassembled and the carbon cloth is characterized by morphology, such as Figure 2 As shown, there is no residual manganese dioxide on the carbon cloth, indicating that hydroquinone significantly improves the reversibility and stability of the manganese dioxide deposition / dissolution reaction. Example 2

[0041] Liquid flow battery: The positive electrode current collector is carbon felt, and the electrolyte is 0.2M manganese sulfate + 3M sulfuric acid + 0.02M hydroquinone; the negative electrode current collector is carbon felt deposited with tin, and the electrolyte is 3M sulfuric acid + 0.2M tin sulfate; the separator is a proton exchange membrane. The charge and discharge curves and cycle performance are shown in Figure 2. Figure 3 As shown, a is the charge and discharge curve of the battery after 100 cycles, and b is the cycle stability of the battery. Figure 3 As can be seen in a, the polarization of the whole battery is small, the charge and discharge curve is stable, and the cycle reversibility of the battery is very high. Figure 3 As can be seen in figure b, the coulombic efficiency can reach 99%, the number of cycles is greater than 1000, and the discharge capacity can be stably maintained at >62mAh.

[0042] Comparative Example 1 Static battery: the positive electrode current collector is carbon cloth, the electrolyte is 1M manganese sulfate + 1M sulfuric acid; the negative electrode current collector is tin foil, the electrolyte is 2M sulfuric acid + 0.2M tin sulfate; the separator is a proton exchange membrane. (That is, the only difference from Example 1 is that the addition of 0.2M hydroquinone in the manganese positive electrode electrolyte is omitted) The charge and discharge curves and cycle performance are shown in Figure 4 As shown in the figure, the coulombic efficiency is less than 95% and decays rapidly after 70 cycles. After charging and discharging, the battery is disassembled and the carbon cloth is characterized. The SEM image is shown in the figure. Figure 5 As shown, a large amount of residual manganese dioxide was found.

[0043] Comparative Example 2 Liquid flow battery: The positive electrode current collector is carbon felt, and the electrolyte is 0.2M manganese sulfate + 3M sulfuric acid; the negative electrode current collector is carbon felt deposited with tin, and the electrolyte is 3M sulfuric acid + 0.2M tin sulfate (that is, the only difference from Example 2 is that the addition of 0.02M hydroquinone in the manganese positive electrode electrolyte is omitted); the diaphragm is a proton exchange membrane. The charge and discharge curves and cycle performance are shown in Figure 6 As shown, a is the charge and discharge curve of the battery after 70 cycles, and b is the cycle stability of the battery. Figure 6 As can be seen in a, the residual manganese dioxide gradually increases with the cycle, resulting in increased polarization and decreased reversibility. Figure 6 As can be seen in figure b, the coulombic efficiency is less than 97%, decays rapidly after 60 cycles, and the discharge capacity is < 40 mAh at 70 cycles.

[0044] Comparative Example 3 The only difference from Example 2 is that 0.02 M hydroquinone in the manganese positive electrode electrolyte is replaced by 0.02 M phenol.

[0045] The same effect verification as in Example 2 was carried out, and the results showed that the coulomb efficiency was 97%, which decayed rapidly after 90 cycles.

[0046] Comparative Example 4 The only difference from Example 2 is that 0.02 M hydroquinone in the manganese positive electrode electrolyte is replaced by 0.02 M 1,2,3-pyrogallol (pyrogallol).

[0047] The same effect verification as in Example 2 was carried out, and the results showed that the coulombic efficiency was 96%, and it decayed rapidly after 70 cycles.

[0048] Comparative Example 5 The only difference from Example 2 is that 0.02 M hydroquinone in the manganese positive electrode electrolyte is replaced by 0.02 M 1,2,4-pyrogallol (pyrogallol).

[0049] The same effect verification as in Example 2 was carried out, and the results showed that the coulombic efficiency was 97%, and it decayed rapidly after 70 cycles.

[0050] Comparative Example 6 The only difference from Example 2 is that 0.02 M hydroquinone in the manganese positive electrode electrolyte is replaced by 0.02 M 1,3,5-benzenetriol (phloroglucinol).

[0051] The same effect verification as in Example 2 was carried out, and the results showed that the coulomb efficiency was 97%, which decayed rapidly after 50 cycles.

[0052] Comparative Example 7 The only difference from Example 2 is that 0.02 M hydroquinone is replaced by 0.02 M 2,5-dihydroxybenzenesulfonic acid.

[0053] The same effect as in Example 2 was verified, and the results showed that the coulombic efficiency was 95%, and it decayed rapidly after 90 cycles. Example 3

[0054] The only difference from Example 2 is that the concentration of hydroquinone in the manganese positive electrode electrolyte is 0.5M and the concentration of sulfuric acid is 0.5M.

[0055] The same effect verification as in Example 2 was carried out, and the results showed that the coulomb efficiency was 98% and the number of cycles was 800. Example 4

[0056] The only difference from Example 2 is that the concentration of hydroquinone in the manganese positive electrode electrolyte is 0.01M.

[0057] The same effect verification as in Example 2 was carried out, and the results showed that the coulomb efficiency was 99% and the number of cycles was 800. Example 5

[0058] The only difference from Example 2 is that the concentration of manganese sulfate in the manganese positive electrode electrolyte is 0.1M, the concentration of hydroquinone is 0.1M, and the concentration of sulfuric acid is 5M.

[0059] The same effect verification as in Example 2 was carried out, and the results showed that the coulomb efficiency was 98% and the number of cycles was 800. Example 6

[0060] The only difference from Example 2 is that 0.02 M hydroquinone in the manganese positive electrode electrolyte is replaced by 0.02 M resorcinol.

[0061] The same effect verification as in Example 2 was carried out, and the results showed that the coulomb efficiency was 99% and the number of cycles was 900. Example 7

[0062] The only difference from Example 2 is that 0.02 M hydroquinone in the manganese positive electrode electrolyte is replaced by 0.02 M catechol.

[0063] The same effect verification as in Example 2 was carried out, and the results showed that the coulomb efficiency was 99% and the number of cycles was 900.

[0064] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A manganese positive electrode electrolyte, characterized in that: It includes a divalent manganese salt, an acid, a solvent and a water-soluble organic small molecule redox reaction medium; The water-soluble organic small molecule redox reaction medium is at least one of hydroquinone, resorcinol and catechol.

2. The manganese positive electrolyte according to claim 1, characterized in that The concentration of the water-soluble organic small molecule redox reaction medium in the manganese positive electrode electrolyte is 0.01-0.5M.

3. The manganese positive electrolyte according to claim 1, characterized in that The divalent manganese salt is at least one of manganese sulfate, manganese chloride, manganese nitrate, manganese acetate, manganese methanesulfonate, and manganese oxalate.

4. The manganese positive electrolyte according to claim 1, characterized in that The concentration of the divalent manganese salt in the manganese positive electrode electrolyte is 0.1-3M.

5. The manganese positive electrolyte according to claim 1, characterized in that The solvent is water.

6. The manganese positive electrode electrolyte according to claim 1, characterized in that: The acid concentration in the manganese positive electrode electrolyte is 0.5-5M.

7. An aqueous battery, characterized in that: It includes a positive electrode current collector, a negative electrode current collector, a positive electrode electrolyte, a negative electrode electrolyte and a separator; The positive electrode electrolyte is the manganese positive electrode electrolyte according to any one of claims 1 to 6.

8. The aqueous battery according to claim 7, characterized in that: The positive electrode current collector is carbon felt, carbon cloth, carbon paper, activated carbon electrode or meshed glassy carbon; the negative electrode current collector is carbon felt, carbon cloth, carbon paper, meshed glassy carbon, tin foil, tin mesh, tin-plated carbon felt, copper foil, copper mesh, foam copper, lead foil, lead mesh or lead-based alloy.

9. The aqueous battery according to claim 7, characterized in that: When the aqueous battery is a manganese-tin battery, the negative electrode electrolyte is an electrolyte containing divalent tin ions; when the aqueous battery is a manganese-copper battery, the negative electrode electrolyte is an electrolyte containing divalent copper ions; when the aqueous battery is a manganese-lead battery, the negative electrode electrolyte is an electrolyte containing divalent lead ions.

10. The aqueous battery according to claim 7, characterized in that: The aqueous battery is an electrolyte static battery or an electrolyte flow battery.

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