Aqueous zinc-manganese battery, electrolyte, preparation and application

Abstract

The invention belongs to the field of aqueous zinc batteries, and particularly relates to an aqueous zinc-manganese battery, an electrolyte, preparation and application, the electrolyte is an aqueous solution containing modified montmorillonite, a water-soluble zinc salt and a water-soluble manganese salt; wherein the modified montmorillonite is montmorillonite modified by a compound with the formula of 1 # imgabs0 #; r is an alkyl group of C8 to C16, an alkoxy group of C8 to C16, a phenyl group, an alkoxy substituted phenyl group of C1 to C6 or an alkyl substituted phenyl group of C1 to C6; m is H, Na, K or NH4; the modified montmorillonoid is obtained by modifying montmorillonoid in a modification solution containing a compound shown in a formula 1, and the weight ratio of the montmorillonoid to the compound shown in the formula 1 is (1.5-3.5): 1; the content of the modified montmorillonite in the electrolyte is 14 to 18 weight percent. The electrolyte provided by the invention has excellent performance and can have the advantages of large current and long cycle.

Description

Technical Field

[0001] The invention belongs to the technical field of aqueous zinc ion batteries, and in particular relates to an electrolyte for an aqueous zinc-manganese battery. Background Art

[0002] Rechargeable aqueous zinc-ion batteries (AZIBs) have attracted widespread attention due to their low cost, high safety, and environmental friendliness, and have become one of the most promising secondary batteries for large-scale energy storage systems.

[0003] There are three types of electrolytes for AZIBs: solid electrolytes, quasi-solid electrolytes, and liquid electrolytes (also known as electrolytes). Compared with solid electrolytes, liquid electrolytes and quasi-solid electrolytes (such as gel electrolytes) have very excellent ionic conductivity, which makes Zn 2+ The migration rate is fast, the rate performance is good, the battery polarization is small, and its preparation process is simple and the cost is low. However, for aqueous zinc-manganese batteries, the use of commonly used aqueous electrolytes such as ZnSO4 or Zn(CF3SO3)2, etc., due to their high content of active water, leads to greater corrosion to the zinc negative electrode, and problems such as deformation of the zinc negative electrode, dendrites, and hydrogen evolution often occur, which leads to rapid capacity decay and reduced cycle life of the zinc-manganese battery, causing it to fail quickly and cannot be used on a large scale. For positive electrode materials, the dissolution of manganese-based positive electrode materials leads to rapid decay of battery capacity, resulting in poor cycle performance and short battery life of aqueous zinc-manganese batteries. Existing improvement schemes mostly suppress side reactions through high-concentration electrolytes (such as "salt-in-water" systems) or organic additives, but there are problems such as high cost and poor low-temperature performance.

[0004] Montmorillonite (MMT) is used to regulate ion transport due to its layered structure and cation exchange capacity. Several prior art solutions incorporate MMT into electrolytes. For example, patent publication CN119518130A discloses an aqueous rechargeable zinc-manganese dioxide battery containing a quasi-solid-state electrolyte containing montmorillonite, and a method for preparing the battery. The electrolyte is a quasi-solid-state montmorillonite electrolyte, comprising a gel-like electrolyte formed by dispersing montmorillonite powder in a zinc salt aqueous solution and stirring the mixture. Furthermore, Chinese patent publication CN109980302A discloses a colloidal electrolyte for an aqueous zinc-ion battery. The colloidal electrolyte comprises a clay material and a conventional electrolyte, and the colloidal electrolyte is in a stable colloidal state. The colloidal electrolyte is obtained by adding the clay material to the conventional electrolyte, stirring and dispersing the electrolyte, and aging the electrolyte for 0.1 to 1 hour. The clay material comprises a composite of one or more of kaolin, illite, chlorite, lithophyllite, attapulgite, vermiculite, and allophane.

[0005] In summary, although there are some MMT addition schemes in the existing technology, the traditional montmorillonite interlayer spacing is small (1.2-1.5nm), which makes it difficult to optimize Zn2+ Transmission and Mn 2+ Constraints make it difficult to adapt to high current and long cycle application requirements. Summary of the Invention

[0006] In view of the defects of existing aqueous zinc-manganese battery in which the water activity in the aqueous electrolyte is high and it is easy to cause negative electrode corrosion, side reactions, positive electrode dissolution and other characteristics, resulting in insufficient capacity and cycle stability, the present invention provides an electrolyte for an aqueous zinc-manganese battery, aiming to provide an electrolyte that can improve battery capacity and cycle stability.

[0007] The second object of the present invention is to provide the preparation and application of the electrolyte of the aqueous zinc-manganese battery.

[0008] A third object of the present invention is to provide an aqueous zinc-manganese battery comprising the electrolyte.

[0009] Unlike solid and semi-solid electrolytes, the water in the electrolyte of aqueous zinc-manganese batteries is more active, which will increase the risk of zinc negative electrode corrosion and positive electrode material dissolution, thereby affecting the battery's capacity and cycle stability. To address this problem, the inventors have previously tried to directly add montmorillonite to the electrolyte to prepare the electrolyte. However, early studies have shown that inappropriate addition of montmorillonite is difficult to achieve the desired effect. The main reason is that the structural characteristics of montmorillonite are difficult to naturally adapt to the requirements of aqueous electrolyte use. In response to the problems faced by montmorillonite in the process of adding aqueous electrolytes, the present inventors have conducted in-depth research and developed the following improvement schemes:

[0010] An electrolyte for an aqueous zinc-manganese battery, comprising an aqueous solution of modified montmorillonite, a water-soluble zinc salt, and a water-soluble manganese salt;

[0011] Wherein, the modified montmorillonite is montmorillonite modified by the compound of formula 1;

[0012]

[0013] The R is C8~C 16 Alkyl, C8~C 16 alkoxy, phenyl, C1-C6 alkoxy substituted phenyl or C1-C6 alkyl substituted phenyl; wherein M is H, Na, K or NH4;

[0014] The modified montmorillonite is obtained by modifying montmorillonite in a modifying solution containing the compound of formula 1, wherein the weight ratio of montmorillonite to the compound of formula 1 is 1.5 to 3.5:1;

[0015] The content of modified montmorillonite in the electrolyte is 14-18 wt.%.

[0016] The innovative research of the present invention shows that the montmorillonite is modified in advance using Formula 1. In this way, based on the combined synergy of Formula 1 and the physicochemical structure of montmorillonite, the combined control of the Formula 1 / MMT ratio and the modified montmorillonite ratio can be further coordinated. In this way, its microstructure can be effectively regulated, the hydrogen bond network of water can be destroyed, the activity of water can be suppressed, the corrosion effect of the aqueous electrolyte on the electrode can be reduced, the occurrence of hydrogen evolution and side reactions in the solution can be significantly reduced, and the desolvation process of hydrated zinc ions can be accelerated, the rapid deposition of zinc ions can be promoted, and the dissolution of the positive electrode material can be alleviated. In addition, the zinc ions can be confined and bound, the electric field around the electrode can be changed, the "tip effect" can be suppressed, and the formation of zinc dendrites at the zinc negative electrode interface can be prevented. The electrolyte described in the present invention can effectively improve the long-cycle stability of the electrolyte under high current.

[0017] In the present invention, the combination of the R hydrophobic chain -SO3- targeting group in Formula 1 is the key to synergistically improving the electrochemical performance of aqueous zinc-manganese batteries with the physicochemical structure of montmorillonite. Research in the present invention also shows that the combination of Formula 1 and MMT, compared to other amine-based modification methods and clay components with other physicochemical structures, can unexpectedly achieve synergy and unexpectedly improve the long-term cycling stability of aqueous zinc-manganese batteries at high currents.

[0018] Preferably, the modified montmorillonite is obtained by modifying montmorillonite in a modifying solution containing the compound of formula 1.

[0019] In the modified solution, the concentration of the compound of formula 1 is not particularly required, and can be, for example, 0.5 to 5 wt.%, or further 2 to 3 wt.%;

[0020] The weight ratio of montmorillonite to the compound of formula 1 is 1.5 to 2.5:1, preferably 1.9 to 2.1:1. Studies have shown that under the preferred modification conditions, the high current and long cycle stability of the electrolyte prepared therefrom can be further improved.

[0021] The temperature during the modification process may be 50-90°C; preferably 60-80°C;

[0022] Preferably, the modification time is 3 to 18 hours, more preferably 8 to 12 hours.

[0023] In the present invention, after modification and stirring, solid-liquid separation, water washing, drying and grinding are carried out to obtain the modified montmorillonite.

[0024] In the present invention, the zinc salt and manganese salt can be any water-soluble electrolyte containing zinc or manganese in the industry.

[0025] For example, in the present invention, the water-soluble zinc salt is selected from one or more of zinc sulfate, zinc chloride, zinc trifluoromethanesulfonate, zinc nitrate, and zinc perchlorate. The water-soluble manganese salt is one or more of manganese sulfate and manganese chloride.

[0026] In the present invention, in the electrolyte, the concentration of the zinc salt is 1 mol / L to 3 mol / L, preferably 1.5 mol / L to 2.5 mol / L. The concentration of the manganese salt is 0.05 mol / L to 1 mol / L, more preferably 0.075 mol / L to 0.125 mol / L.

[0027] The content of modified montmorillonite in the electrolyte is 15-17%. Studies have shown that the optimal content can further improve the large current and long cycle stability of the electrolyte prepared therefrom.

[0028] The present invention also provides a method for preparing the electrolyte, comprising uniformly mixing modified montmorillonite, a water-soluble zinc salt, a water-soluble manganese salt, and water. During the preparation process, existing methods can be used to accelerate system mixing, for example, by stirring and / or ultrasound-assisted mixing.

[0029] The present invention also includes the application of the electrolyte as an electrolyte for preparing an aqueous zinc-manganese battery.

[0030] The present invention also provides an aqueous zinc-manganese battery, which comprises the electrolyte of the present invention.

[0031] The aqueous zinc-manganese battery of the present invention has conventional components, principles and operations except that the electrolyte of the present invention is added to the electrolyte.

[0032] Beneficial effects

[0033] The electrolyte of the present invention is based on the combination of the modified montmorillonite, zinc salt, and manganese salt, and further controls the modification method and content of the modified montmorillonite, thereby achieving synergy, reducing the activity of water in the aqueous electrolyte, reducing the occurrence of side reactions in the solution, inhibiting the corrosion of the zinc negative electrode, and alleviating the dissolution of the positive electrode material, thereby enabling the electrolyte to obtain more stable cycle performance and a greater number of cycles, thereby increasing the service life of the aqueous zinc-manganese battery. In addition, the preparation method is simple, the cost is low, the raw materials are abundant, and the electrolyte has broad industrial prospects.

[0034] The research of the present invention also shows that the innovative use of modified montmorillonite for modification treatment and the control of the amount of introduced montmorillonite can further synergistically improve the capacity and cycle stability of the obtained aqueous zinc-manganese battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The cycling performance diagram of the aqueous zinc-manganese battery assembled in Example 1 at 500 mA / g and 1000 mA / g;

[0036] Figure 2The XRD patterns of montmorillonite before and after modification in Example 1 are shown;

[0037] Figure 3 This is the EIS test graph of the zinc symmetrical battery assembled in Example 1;

[0038] Figure 4 This is the Tafel plot of the zinc symmetric battery assembled in Example 1;

[0039] Figure 5 1 is a cycling performance diagram of the aqueous zinc-manganese battery assembled in Example 2 at 500 mA / g;

[0040] Figure 6 1 is a cycle performance diagram of the aqueous zinc-manganese battery assembled in Example 2 at 1000 mA / g;

[0041] Figure 7 1 is a cycling performance diagram of the aqueous zinc-manganese battery assembled in Example 3 at 500 mA / g;

[0042] Figure 8 This is a cycle performance diagram of the aqueous zinc-manganese battery assembled in Example 3 at 1000 mA / g. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments further describe the content of the present invention in detail, but the scope of protection of the claims of the present invention is not limited by the embodiments.

[0044] In the present invention, the performance test method of the aqueous zinc-manganese battery is as follows: manganese dioxide active material, conductive agent Ketjen black, and binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 7:2:1, and after being fully ground, N-methyl-2-pyrrolidone (NMP) is added to form a uniform black paste slurry, which is then coated on a stainless steel mesh and dried for 12 hours to be used as the positive electrode, wherein the active material loading is 0.8 to 1.0 mg / cm 2 , using zinc sheet as the negative electrode, the electrolyte prepared in the following cases (also called colloidal electrolyte) as the electrolyte, and the separator to assemble into a CR2016 button battery. The charge and discharge current density used to test the cycle performance was 500mA / g~1000mA / g, and the test temperature was room temperature.

[0045] Aqueous zinc-zinc symmetrical battery performance test method: Use zinc sheets as positive and negative electrodes, use the electrolyte (colloidal electrolyte) prepared in the following cases as the electrolyte, and assemble the separator into a CR2016 button battery. The test temperature is room temperature.

[0046] Example 1

[0047]

[0048] Modified montmorillonite:

[0049] First, untreated montmorillonite was dissolved in deionized water and stirred continuously for 2 h under magnetic stirring conditions. Formula 1A with a mass concentration of 2.5% was dissolved in deionized water and stirred continuously for 1 h under magnetic stirring conditions. The two were mixed (the weight ratio of montmorillonite to formula 1A was 2:1) and stirred at a constant temperature of 70±10℃ for 8-9 h. The montmorillonite was then centrifuged and washed with water. The montmorillonite was then vacuum dried at 80℃ for 12 h to obtain modified montmorillonite (XRD before and after modification is shown in FIG. 2 ). Figure 2 ).

[0050] Mixed electrolyte: Modified montmorillonite, zinc sulfate, and manganese sulfate are uniformly dispersed in water to obtain a mixed electrolyte (the dispersion process is, for example, ultrasonically treating the solution for 10 minutes, continuously stirring under magnetic stirring for 12 hours, and then ultrasonically treating the solution for another 10 minutes).

[0051] In the mixed electrolyte, the concentration of zinc sulfate is 2 mol / L, the concentration of manganese sulfate is 0.1 mol / L, and the content of modified montmorillonite in the mixed electrolyte is 16.7 wt.%.

[0052] test:

[0053] The charge and discharge current density used for testing the cycle performance was 500 mA / g, 200 cycles, and the test temperature was room temperature.

[0054] In addition, the charge and discharge current density used to test the cycle performance was 1000 mA / g, 200 cycles, and the test temperature was room temperature.

[0055] Example 2

[0056] Compared with Example 1, the only difference is that the weight ratio of montmorillonite and Formula 1A is adjusted. The experimental groups are:

[0057] Group A: The weight ratio of montmorillonite and formula 1A was adjusted to 3:1;

[0058] Group B: The weight ratio of montmorillonite and Formula 1A was adjusted to 1:1.

[0059] Group C: The weight ratio of montmorillonite and Formula 1A was adjusted to 3:2.

[0060] Other operations and parameters are the same as in Example 1.

[0061] Example 3

[0062] Compared with Example 1, the only difference is that the content of modified montmorillonite in the mixed electrolyte is adjusted. The experimental groups are:

[0063] Group A: The content of modified montmorillonite in the mixed electrolyte is 14.3 wt%;

[0064] Group B: the content of modified montmorillonite in the mixed electrolyte is 20 wt%;

[0065] Group C: The content of modified montmorillonite in the mixed electrolyte was 15.4 wt%.

[0066] Other operations and parameters are the same as in Example 1.

[0067] Example 4

[0068] Compared with Example 1, the only difference is that the concentration of Formula 1A in the montmorillonite modification process is 3%. In addition, the zinc sulfate concentration in the mixed electrolyte is adjusted from 2 mol / L to 2.5 mol / L, and the manganese sulfate concentration ratio is adjusted from 0.1 mol / L to 0.12 mol / L. Other operations and parameters are the same as in Example 1.

[0069] Comparative Example 1

[0070] Compared with Example 1, the only difference is that the modified montmorillonite is replaced by the unmodified montmorillonite in the mixed electrolyte, and the other operations and parameters are the same as those in Example 1.

[0071] Comparative Example 2

[0072] Compared with Example 1, the only difference is that the mixed electrolyte lacks modified montmorillonite, and the other operations and parameters are the same as Example 1.

[0073] Comparative Example 3

[0074] Compared with Example 1, the only difference is that the modified montmorillonite adopts the comparative formula A The formula 1A is replaced by the same amount, and the other operations and parameters are the same as those in Example 1.

[0075] Comparative Example 4

[0076] Compared with Example 1, the only difference is that in the modified montmorillonite, an equal amount of polyvinyl alcohol is used to replace the formula 1, and other operations and parameters are the same as those in Example 1.

[0077] Comparative Example 5

[0078] Compared with Example 1, the only difference is that the montmorillonite before modification is replaced by kaolinite in equal amount, and the other modification processes, operations and parameters are the same as those in Example 1.

[0079] Comparative Example 6

[0080] Compared with Example 1, the only difference is that the montmorillonite before modification is replaced by sepiolite in equal amount, and the other modification processes, operations and parameters are the same as those in Example 1.

[0081] The battery performance of each case is shown in Table 1:

[0082] Table 1

[0083]

[0084] As can be seen from Table 1, montmorillonite is modified in advance using Formula 1. In this way, based on the combined synergy of Formula 1 and the physicochemical structure of montmorillonite, the combined control of the Formula 1 / MMT ratio and the modified montmorillonite ratio can be further coordinated. In this way, synergy can be achieved and the high-current long-cycle stability of aqueous zinc batteries can be enhanced.

Claims

1. An electrolyte for an aqueous zinc-manganese battery, characterized in that: An aqueous solution comprising modified montmorillonite, a water-soluble zinc salt, and a water-soluble manganese salt; Wherein, the modified montmorillonite is montmorillonite modified by the compound of formula 1; The R is C8~C 16 Alkyl, C8~C 16 alkoxy, phenyl, C1-C6 alkoxy substituted phenyl or C1-C6 alkyl substituted phenyl; wherein M is H, Na, K or NH4; The modified montmorillonite is obtained by modifying montmorillonite in a modifying solution containing the compound of formula 1, wherein the weight ratio of montmorillonite to the compound of formula 1 is 1.5 to 3.5:1; The content of modified montmorillonite in the electrolyte is 14-18 wt.%.

2. The electrolyte according to claim 1, wherein The concentration of the compound of formula 1 is 0.5 to 5 wt.%.

3. The electrolyte according to claim 2, wherein In the modified liquid, the weight ratio of montmorillonite to the compound of formula 1 is 1.5-2.5:

1.

4. The electrolyte according to claim 2 or 3, wherein The temperature during the modification process is 50-90°C; preferably 60-80°C; Preferably, the modification time is 3 to 18 hours, more preferably 8 to 12 hours.

5. The electrolyte according to claim 1, wherein The water-soluble zinc salt is selected from one or more of zinc sulfate, zinc chloride, zinc trifluoromethanesulfonate, zinc nitrate and zinc perchlorate.

6. The electrolyte according to claim 1, wherein The water-soluble manganese salt is one or more of manganese sulfate and manganese chloride.

7. The electrolyte according to any one of claims 1 to 6, wherein In the electrolyte, the concentration of the water-soluble zinc salt is 1 mol / L to 10 mol / L, preferably 1.5 mol / L to 2.5 mol / L; The concentration of the water-soluble manganese salt is 0.05 mol / L to 0.5 mol / L, more preferably 0.075 mol / L to 0.125 mol / L; The content of the modified montmorillonite is 16-17 wt%.

8. A method for preparing the electrolyte according to any one of claims 1 to 7, characterized in that: The modified montmorillonite, water-soluble zinc salt, water-soluble manganese salt and water are mixed evenly to obtain the product; Preferably, the mixing process is carried out with the aid of stirring and / or ultrasound.

9. Use of the electrolyte according to any one of claims 1 to 7, characterized in that: It is used as an electrolyte to prepare aqueous zinc-manganese batteries.

10. An aqueous zinc-manganese battery, characterized in that: It comprises the electrolyte according to any one of claims 1 to 7.

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