Aqueous zinc ion battery secondary battery electrolyte additive and preparation method thereof

Abstract

The invention belongs to the technical field of energy storage of aqueous zinc ion batteries, and provides an aqueous zinc ion battery secondary battery electrolyte additive and a preparation method thereof.The additive is prepared from, by mass, 0.1-1 part of 2, 3-dimethyl hydroquinone, 0.5-2 parts of manganese sulfate, 1-5 parts of zinc sulfate and 0.05-0.5 part of ethylene diamine tetraacetic acid; by introducing the additive, the surface uniformity of the zinc negative electrode is effectively improved, dendritic crystal growth is inhibited, dead zinc formed by dendritic crystal fracture is reduced, so that the cycling stability and safety of the battery are remarkably improved, the service life of the battery is prolonged, the additive can adjust ion transport kinetics of the electrolyte, and the service life of the battery is prolonged. According to the additive, the conductivity and the thermal stability of the electrolyte are improved, the battery still keeps excellent performance under the high-temperature or high-load condition, the application scene of the battery is expanded, and the preparation method of the additive is simple, easy to implement, low in cost, suitable for large-scale industrial production and high in market popularization value.

Description

Technical Field

[0001] This invention belongs to the field of aqueous zinc-ion battery energy storage technology, specifically an additive for aqueous zinc-ion battery secondary electrolyte and its preparation method. Background Technology

[0002] Aqueous zinc-ion batteries (AZ IB) stand out for their cost-effectiveness, enhanced safety, extended lifespan, and simplified packaging process, making them ideal for large-scale energy storage deployments. AZ IB demonstrates significant potential, particularly in addressing the volatility and intermittency of renewable energy. Its stable chemistry and efficient charge-discharge cycle capability effectively balance grid load and improve energy efficiency. Furthermore, its use of an aqueous electrolyte avoids the flammability and explosiveness issues associated with traditional organic electrolytes, further enhancing operational safety. This technology not only meets the energy storage needs of homes and industries but also provides a viable solution for energy supply in remote areas or special scenarios.

[0003] However, many problems still need to be solved in the charging and discharging process of AZI Bs. Due to the uneven electric field on the zinc negative electrode surface, zinc deposition is uneven, which leads to dendrite growth and the formation of "dead zinc" due to dendrite fracture during the stripping process. During the Zn deposition process, the electron competition between Zn2+ and H+ triggers the hydrogen evolution reaction. Zinc metal in aqueous environment is corroded and passivated due to thermodynamic activity. These problems are complex and form a vicious cycle, which reduces battery performance and life and hinders the large-scale energy storage application of the battery.

[0004] To address the problems raised in the background art, those skilled in the art have proposed an aqueous zinc-ion battery secondary electrolyte additive and its preparation method.

[0005] The information disclosed above in this background section is only for enhancing the understanding of the background technology of this invention, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an additive for the electrolyte of an aqueous zinc-ion battery and its preparation method, thereby resolving issues such as uneven zinc deposition, dendrite growth, hydrogen evolution reaction, and zinc metal corrosion in existing aqueous zinc-ion batteries during charging and discharging.

[0007] To achieve the above objectives, the present invention provides an additive for an aqueous zinc-ion battery secondary electrolyte, the additive comprising the following raw materials in parts by weight: 0.1-1 parts of 2,3-dimethylhydroquinone, 0.5-2 parts of manganese sulfate, 1-5 parts of zinc sulfate, and 0.05-0.5 parts of disodium ethylenediaminetetraacetate.

[0008] Preferably, the additive comprises the following raw materials in parts by weight: 0.5 parts of 2,3-dimethylhydroquinone, 1 part of manganese sulfate, 3 parts of zinc sulfate, and 0.2 parts of disodium ethylenediaminetetraacetate.

[0009] A method for preparing an additive for an aqueous zinc-ion battery secondary electrolyte includes the following steps:

[0010] S1. Accurately weigh 2,3-dimethylhydroquinone, manganese sulfate, zinc sulfate, and disodium ethylenediaminetetraacetate, and mix them according to the mass ratio described in claim 1 or 2.

[0011] S2. Add 2,3-dimethylhydroquinone, manganese sulfate, zinc sulfate, and disodium ethylenediaminetetraacetate sequentially to an appropriate amount of deionized water and stir until completely dissolved to obtain a mixed solution.

[0012] S3. Filter the mixed solution through a microporous membrane to remove insoluble impurities and obtain a pure additive solution.

[0013] S4. Concentrate the filtered additive solution under reduced pressure to the required volume to obtain concentrated electrolyte additive.

[0014] S5. Conduct quality testing on the prepared additives, including indicators such as appearance, purity, and stability, to ensure compliance with relevant quality standards. After passing the test, use aseptic filling equipment to fill the additives into sterilized containers and seal them for storage.

[0015] Preferably, the pore size of the microporous filter membrane is 0.22 to 0.45 μm.

[0016] Preferably, the temperature for vacuum concentration is 55–60°C.

[0017] An aqueous zinc-ion secondary battery includes a positive current collector, a negative electrode, and an electrolyte.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention effectively improves the surface uniformity of the zinc anode by introducing additives, inhibits dendrite growth, and reduces the formation of "dead zinc" due to dendrite fracture, thereby significantly improving the cycle stability and safety of the battery and extending its service life. Secondly, the additive can regulate the ion transport kinetics of the electrolyte, improve the conductivity and thermal stability of the electrolyte, and enable the battery to maintain excellent performance under high temperature or high load conditions, further expanding the application scenarios of the battery. In addition, the preparation method of the additive is simple, easy to implement, and inexpensive, making it suitable for large-scale industrial production and possessing high market promotion value.

[0020] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0021] Figure 1 This is a diagram illustrating the reaction mechanism of an aqueous zinc-ion battery electrolyte additive in an aqueous zinc-ion battery for zinc deposition and dissolution, as described in an embodiment of the present invention.

[0022] Figure 2 The images shown are scanning electron microscope (SEM) and atomic force microscope (AFM) images of the copper sheet after cycling with standard electrolyte and TDHQ electrolyte in this embodiment.

[0023] Figure 3 This is a graph showing the hydrogen evolution capacity test of the zinc-zinc symmetric battery under different electrolyte systems in this embodiment;

[0024] Figure 4 This is a performance comparison chart of the zinc-copper half-cell and the zinc-zinc symmetric cell in this embodiment;

[0025] Figure 5 The above shows the charge-discharge curves and efficiency graphs of the MnO2 / / Zn battery in this embodiment from low to high areal capacity. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be noted that the drawings are schematic and not illustrated to scale. For clarity and convenience, the relative sizes and proportions of the parts shown in the drawings have been exaggerated or reduced in size. Any size is only illustrative and not limiting.

[0027] Example 1:

[0028] Please see Figure 1 - Figure 5 As shown, the preparation method of the electrolyte additive for aqueous zinc-ion batteries includes the following steps:

[0029] Materials preparation: Accurately weigh the following raw materials: 0.5g of 2,3-dimethylhydroquinone (TDHQ), 1.0g of manganese sulfate (MnSO4), 3.0g of zinc sulfate (ZnSO4), and 0.2g of disodium ethylenediaminetetraacetate (EDTA);

[0030] Dissolving and mixing: Add the above raw materials to 100 mL of deionized water in sequence, and stir with a magnetic stirrer at 60 r / min for 30 minutes until all raw materials are completely dissolved to obtain a homogeneous mixed solution;

[0031] Filtration and impurity removal: The mixed solution is filtered through a microporous membrane with a pore size of 0.22 μm to remove insoluble impurities and obtain a pure additive solution.

[0032] Concentration and volume adjustment: The filtered additive solution was placed in a rotary evaporator and concentrated under reduced pressure at 55°C to 50 mL to obtain concentrated electrolyte additive.

[0033] Quality inspection and packaging: The prepared additives are subjected to quality inspection, including indicators such as appearance, purity, and stability. After passing the inspection, the additives are filled into sterilized 50mL glass bottles using aseptic filling equipment and sealed for storage.

[0034] Example 2:

[0035] Specifically, zinc foil is used as the negative electrode and carbon felt is used as the positive electrode current collector. The electrolyte additive prepared in Example 1 is added to 2 mol / L ZnSO4 electrolyte at a ratio of 1:100 to prepare an electrolyte containing additives. The positive and negative electrodes are placed opposite each other and separated by two layers of glass fiber. The prepared electrolyte is injected and assembled into a zinc-copper asymmetric battery.

[0036] like Figure 1 As shown, the battery exhibits highly synergistic and efficient working mechanism during charging and discharging. The core secret to its superior performance lies in the unique role of the TDHQ additive. In the battery's electrolyte system, TDHQ molecules can cleverly embed themselves into the solvation structure of zinc ions, forming a special composite structure. Specifically, each TDHQ molecule can interact with two zinc ions and participate in the construction of their solvation shell. This unique coordination relationship lays a key foundation for subsequent electrochemical reactions.

[0037] During battery charging, an external power source applies an electric field, causing zinc ions in the solution (existing in the form of [Zn6H2O~TDHQ] complex) to migrate towards the positive electrode. At this time, TDHQ acts as a precise "ion carrier," carrying the solvation structure of two zinc ions and shuttling efficiently in the electrolyte solution. Due to the participation of TDHQ, the electron cloud distribution and spatial configuration of the traditional zinc ion solvation structure are changed, which significantly reduces the migration resistance of ions in the solution and thus greatly accelerates the ion transport rate. This rapid ion transport not only improves the charging and discharging efficiency of the battery, but also creates favorable conditions for the uniform deposition of zinc ions on the positive electrode surface.

[0038] When the battery discharges, the process is reversed. The zinc originally deposited on the positive electrode surface begins to dissolve, reforming the [Zn6H2O~TDHQ] complex and entering the solution. TDHQ once again plays its role as an "ion carrier," assisting zinc ions to quickly return to the negative electrode region. Throughout the entire charge-discharge cycle, TDHQ consistently participates in the solvation structure of zinc ions, continuously promoting the deposition and dissolution reactions of zinc ions, ensuring the efficient conduct of the electrochemical reaction.

[0039] More importantly, the addition of TDHQ played a crucial role in reducing side reactions and inhibiting zinc dendrite growth, such as... Figure 2 As shown, in traditional additive-free battery systems, zinc ions are prone to uneven deposition during the deposition process, leading to the rampant growth of zinc dendrites. These disorderly zinc dendrites not only consume a large amount of active zinc, reducing battery capacity and cycle life, but more seriously, as the dendrites continue to grow, they are very likely to puncture the separator inside the battery, causing an internal short circuit, ultimately leading to battery failure and even safety issues.

[0040] However, in this battery system, due to the presence of TDHQ, it can guide zinc ions to be uniformly deposited on the positive electrode surface. This is because TDHQ changes the interfacial properties of zinc ion deposition, reduces the deposition overpotential, and makes zinc ions more inclined to grow uniformly on existing deposition sites rather than forming sharp dendrites. With the significant reduction of zinc dendrites, the zinc layer deposited on the positive electrode surface becomes more flat and dense. This flat zinc deposition layer not only improves the positive electrode utilization rate of the battery, but more importantly, it effectively prevents battery death caused by zinc dendrites piercing the separator, thereby greatly improving the safety and cycle stability of the battery.

[0041] The assembled battery was subjected to cycle testing at a 1C discharge rate, and its coulombic efficiency, cycle performance, and impedance were recorded. The electrochemical testing of the battery was as follows: Figure 3 As shown, the coulombic efficiency of the assembled zinc-copper battery was tested under the condition of 1 mAh cm⁻². Figure 3 As shown in Figure a, it can be seen that after 250 cycles, the zinc-copper battery in the TDHQ electrolyte environment remains stable, with an average coulombic efficiency of 99.76%, while the zinc-copper battery in the standard electrolyte environment shows degradation after 50 cycles, with an average coulombic efficiency of 99.26%. This may be because zinc dendrites pierced the separator, causing the battery to fail. Impedance testing was performed on assembled zinc-zinc symmetric batteries, as shown in Figure a. Figure 3 As shown in b, the battery using TDHQ additive has lower internal resistance and charge transfer resistance compared to the battery with standard electrolyte. TDHQ electrolyte exhibits higher electron mobility and electrochemical activity, improving battery performance. The cycle life of the zinc-zinc symmetric battery was tested at a 1C discharge rate, as shown in [example data]. Figure 3As shown in c, the addition of TDHQ inhibits the growth of zinc dendrites and the occurrence of side reactions, thereby increasing the cycle life of the zinc-zinc symmetric battery to 2000 hours, while the battery without the additive only has a cycle life of 300 hours.

[0042] Example 3:

[0043] Battery assembly: Take two 1cm wide zinc sheets and place them in a cuvette and fix them in place. Inject standard zinc sulfate electrolyte and TDHQ-containing electrolyte prepared in Example 1 into the cuvette respectively. Use electrode clamps to hold the zinc sheets that are exposed in the cuvette to prepare a battery whose internal structure can be observed.

[0044] Test conditions: Hydrogen evolution was observed in batteries with two different electrolyte systems under a discharge rate of 4C.

[0045] Test Results: After 6 hours of continuous charging and discharging, no obvious bubbles were observed on the surface of the zinc plate in the standard electrolyte. As the charging and discharging time was extended to 12 hours, a small number of bubbles began to appear on the surface of the zinc plate in the standard electrolyte, while the surface of the zinc plate in the TDHQ-containing electrolyte remained bubble-free. When the charging and discharging process lasted for 24 hours, a large number of bubbles appeared on the surface of the zinc plate in the standard electrolyte, and the hydrogen evolution reaction was extremely obvious. However, no bubbles were generated on the surface of the zinc plate in the TDHQ-containing electrolyte. This fully demonstrates that TDHQ can effectively suppress the hydrogen evolution reaction, reduce the occurrence of side reactions during charging and discharging, and provide a strong guarantee for the stable operation of the battery.

[0046] Example 4:

[0047] Battery Assembly: Carbon felt was used as the positive electrode current collector, and zinc foil as the negative electrode. 200 mL of electrolyte was prepared as a mixed solution of 1 mol / L MnSO4 + 2 mol / L ZnSO4 and 1 mol / L MnSO4 + 2 mol / L ZnSO4 + 0.136 mol / L TDHQ. 20 mL of the prepared electrolyte was injected into the electrolytic cell. A 1.6 cm² piece of carbon felt was placed in the electrolyte, ensuring it was completely submerged. The carbon felt was then removed with tweezers and held in place with platinum electrode clips. A 1.6 cm² zinc plate was then placed in the platinum electrode clips. These clips were then inserted into the electrolytic cell lid and tightened. The height of the platinum clips on the lid was adjusted so that the area of ​​the carbon felt and zinc foil submerged in the electrolyte was 1 cm². This completed the assembly of the aqueous zinc-manganese secondary battery (MnO2 / / Zn battery). The main electrode reactions of this battery are as follows:

[0048] Positive electrode: Mn 2+ +2H₂O–2e - →MnO2+4H + ;

[0049] Negative electrode: Zn 2+ +2e - →Zn;

[0050] Overall: Mn 2+ +2H2O+Zn 2+ →MnO2+4H + +Zn;

[0051] Performance testing: such as Figure 5 As shown in a, at a low discharge rate (1C, discharge surface capacity of 1mAh / cm²), 2 The discharge performance of TDHQ-ZM and ZM full cells was studied. Test results showed that the discharge curve of the TDHQ-ZM full cell exhibited a gentle plateau region at approximately 1.2V, indicating that a relatively stable and reversible electrochemical reaction occurred within the cell at this potential. While the ZM full cell also exhibited a discharge plateau, its slope gradually increased with increasing cycle number until the plateau completely disappeared. This change reflects that the reversibility of the electrode reactions in the ZM full cell gradually decreased during cycling, and the polarization phenomenon became increasingly severe. Further analysis of the cell's coulombic efficiency, such as... Figure 5 As shown in b, the TDHQ-ZM full cell not only maintained a high discharge plateau throughout the entire cycle but also exhibited excellent coulombic efficiency characteristics, with an average coulombic efficiency as high as 97.47%. This fully demonstrates that the battery exhibits good reversibility of charge transfer, effective suppression of side reactions, and minimal energy loss during charge and discharge. To more comprehensively evaluate the performance of the TDHQ-ZM full cell... Figure 5 c shows the charge-discharge curves from low to high areal capacity. It can be seen that as the areal capacity increases, the capacity of the TDHQ-ZM full cell is always significantly higher than that of the full cell under standard conditions, highlighting the huge advantages of this aqueous battery in the field of large-scale energy storage and providing a potential effective solution for solving the needs of large-scale energy storage.

[0052] All standard parts used in this invention can be purchased commercially, and irregularly shaped parts can be customized according to the description and drawings. The specific connection methods for each part all employ conventional methods such as bolts, rivets, and welding, which are mature technologies in the prior art. The machinery, parts, and equipment all use conventional models in the prior art, and the circuit connections also use conventional connection methods in the prior art, which will not be detailed here. Any content not described in detail in this specification belongs to the prior art known to those skilled in the art.

[0053] The accompanying drawings of the embodiments disclosed in this invention only involve structures related to the embodiments disclosed in this invention. Other structures can refer to general designs. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.

[0054] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An additive for an aqueous zinc-ion battery secondary electrolyte, characterized in that, The additive comprises the following raw materials in parts by weight: 0.1-1 parts of 2,3-dimethylhydroquinone, 0.5-2 parts of manganese sulfate, 1-5 parts of zinc sulfate, and 0.05-0.5 parts of disodium ethylenediaminetetraacetate.

2. The aqueous zinc-ion battery secondary battery electrolyte additive according to claim 1, characterized in that: The additive comprises the following raw materials in parts by weight: 0.5 parts of 2,3-dimethylhydroquinone, 1 part of manganese sulfate, 3 parts of zinc sulfate, and 0.2 parts of disodium ethylenediaminetetraacetate.

3. A method for preparing an additive for an aqueous zinc-ion battery secondary electrolyte, characterized in that: Includes the following steps: S1. Accurately weigh 2,3-dimethylhydroquinone, manganese sulfate, zinc sulfate, and disodium ethylenediaminetetraacetate, and mix them according to the mass ratio described in claim 1 or 2. S2. Add 2,3-dimethylhydroquinone, manganese sulfate, zinc sulfate, and disodium ethylenediaminetetraacetate sequentially to an appropriate amount of deionized water and stir until completely dissolved to obtain a mixed solution. S3. Filter the mixed solution through a microporous membrane to remove insoluble impurities and obtain a pure additive solution. S4. Concentrate the filtered additive solution under reduced pressure to the required volume to obtain concentrated electrolyte additive. S5. Conduct quality testing on the prepared additives, including indicators such as appearance, purity, and stability, to ensure compliance with relevant quality standards. After passing the test, use aseptic filling equipment to fill the additives into sterilized containers and seal them for storage.

4. The preparation method of an additive for an aqueous zinc-ion battery secondary electrolyte according to claim 3, characterized in that: The pore size of the microporous filter membrane is 0.22–0.45 μm.

5. The method for preparing an additive for an aqueous zinc-ion battery secondary electrolyte according to claim 4, characterized in that: The temperature for vacuum concentration is 55–60°C.

6. The aqueous zinc-ion battery electrolyte additive according to any one of claims 1 to 2 is applied to an aqueous zinc-ion battery secondary battery.

7. A water-based zinc-ion secondary battery, characterized in that, It includes a positive current collector, a negative electrode, and an electrolyte.

Images