Impact-resistant flexible aqueous zinc ion battery electrolyte as well as preparation method and application thereof

Abstract

The invention relates to an impact-resistant flexible water-based zinc ion battery electrolyte as well as a preparation method and application thereof, and belongs to the technical field of flexible water-based zinc ion battery electrolytes. The preparation method of the impact-resistant flexible aqueous zinc ion battery electrolyte comprises the following steps: mixing starch and a Zn (CF3SO3) 2 liquid electrolyte, and uniformly stirring to obtain the impact-resistant flexible aqueous zinc ion battery electrolyte. The invention provides the electrolyte which is simple to prepare and excellent in impact resistance and has dynamic responsiveness to improve the impact resistance, safety and stability of the flexible aqueous zinc ion battery.

Description

Technical Field

[0001] This application relates to the field of flexible aqueous zinc-ion battery electrolyte technology, and in particular to an impact-resistant flexible aqueous zinc-ion battery electrolyte, its preparation method, and its application. Background Technology

[0002] With the overexploitation and use of non-renewable energy sources, problems such as resource depletion and environmental pollution are intensifying globally, making the effective development of green and renewable energy crucial. The efficient utilization of renewable energy requires continuous updates and development of energy storage technologies. Rechargeable batteries, due to their high flexibility and high conversion efficiency, have become a mainstream energy storage medium. Among various rechargeable batteries, aqueous zinc-ion batteries have attracted significant attention in the energy storage field due to their advantages such as low cost, high theoretical capacity, and high safety.

[0003] In recent years, flexible electronics technology has continued to develop, and flexible wearable electronic devices have gradually become more widespread. These flexible wearable electronic devices are inevitably subjected to impacts or compression in daily use, leading to performance degradation. Therefore, it is crucial to develop flexible energy storage devices with impact resistance.

[0004] Flexible aqueous zinc-ion batteries use water-based electrolytes, which are non-toxic and harmless, and can be directly exposed to the human body, making them ideal energy storage devices for flexible wearable electronic devices. In recent years, much research has focused on improving the electrochemical stability of water-based electrolytes through electrolyte modification. For example, some researchers have used phosphate buffer solution and MnSO4 as electrolyte additives, effectively suppressing side reactions and the decomposition of the cathode material VOPO4. However, besides improving the intrinsic electrochemical stability of the battery system, the macroscopic mechanical stability of flexible batteries is another crucial prerequisite for the reliable operation of flexible wearable electronic devices. Currently, to improve the impact resistance of flexible battery systems, packaging materials with superior impact resistance or solid or quasi-solid (gel) electrolytes with better mechanical properties are generally used to replace traditional liquid electrolytes. However, using packaging materials with superior impact resistance increases manufacturing costs and reduces the theoretical specific capacity of the full battery; using solid or quasi-solid (gel) electrolytes reduces ionic conductivity and affects electrolyte-electrode interface compatibility, leading to a decline in battery electrochemical performance. In the preparation of solid-state or quasi-solid-state (gel) electrolytes, researchers often add polymer molecular chains to liquid electrolytes to obtain gel electrolytes, which can enhance mechanical properties while maintaining sufficient ion transport channels. For example, mixing polyvinyl alcohol (PVA) with an electrolyte to prepare a gel electrolyte can improve the mechanical properties of flexible zinc-ion micro batteries. However, such gel electrolytes typically exhibit a static, stable network structure and lack the ability to dynamically recognize and respond to external shocks. In particular, when subjected to external impact, their internal structure does not undergo significant and reversible phase transitions, leading to mechanical property failure under impact loads. Therefore, developing a novel shock-resistant electrolyte with dynamic responsiveness is of great significance. Summary of the Invention

[0005] In view of this, this application provides an impact-resistant flexible aqueous zinc-ion battery electrolyte, its preparation method and application. When the battery is subjected to a large external impact, the electrolyte becomes a solid-like substance due to the shear thickening effect to resist the external force, which is beneficial to improving the impact resistance and safety of the flexible battery and can effectively overcome the defects of the prior art.

[0006] The first aspect of this application provides a method for preparing an impact-resistant flexible aqueous zinc-ion battery electrolyte, comprising the following steps:

[0007] By mixing starch and Zn(CF3SO3)2 liquid electrolyte and stirring until homogeneous, an impact-resistant flexible aqueous zinc-ion battery electrolyte can be obtained.

[0008] To address the shortcomings of existing technologies, this application proposes an electrolyte that is simple to prepare, exhibits excellent impact resistance, and possesses dynamic responsiveness to improve the impact resistance and safety stability of flexible aqueous zinc-ion batteries. Specifically, this application adds starch to a Zn(CF3SO3)2 electrolyte and mixes it uniformly to form an electrolyte with a shear-thickening effect. On one hand, the strong interaction between starch and zinc ions reduces the amount of coordinated water around the cations, regulates the solvation structure of zinc ions, and weakens the corrosive effect of water molecules on the zinc electrode; the strong bonding force between starch and the Zn(002) crystal plane can induce zinc epitaxial growth and inhibit zinc dendrite formation. On the other hand, when the battery is subjected to a large external impact, the electrolyte becomes a near-solid state due to the shear-thickening effect, improving mechanical properties and ensuring battery safety. When the external force is removed, the electrolyte quickly returns to a fluid state. This dynamic responsiveness of "stronger when encountering strong forces and weaker when encountering weak forces" is not possessed by traditional hydrogel electrolytes (taking PVA electrolyte as an example). Thanks to this, the Zn / / AlVO battery prepared in this application based on the shock-resistant electrolyte exhibits superior cycle stability, rate capability, and shock resistance.

[0009] Preferably, the preparation process of the Zn(CF3SO3)2 liquid electrolyte is as follows: zinc trifluoromethanesulfonate salt is dissolved in deionized water and stirred evenly to obtain 1 M Zn(CF3SO3)2 liquid electrolyte.

[0010] Preferably, the mass ratio of starch to Zn(CF3SO3)2 liquid electrolyte is (3~6):(4~7).

[0011] Preferably, the mass ratio of starch to Zn(CF3SO3)2 liquid electrolyte is 3:7, 3.5:6.5, 4:6, 4.5:5.5, 5:5, 5.5:4.5, or 6:4. The starch constitutes 30%, 35%, 40%, 45%, 50%, 55%, and 60% of the impact-resistant flexible aqueous zinc-ion battery electrolyte, respectively.

[0012] A second aspect of this application also provides an impact-resistant flexible aqueous zinc-ion battery, comprising the aforementioned impact-resistant flexible aqueous zinc-ion battery electrolyte.

[0013] Preferably, it also includes a positive electrode, a negative electrode, and a separator.

[0014] Preferably, the preparation process of the positive electrode is as follows: the positive electrode active material AlV3O9 (AlVO for short), binder PVDF, and conductive agent Super P are mixed, and an appropriate amount of NMP solvent is added. After grinding evenly, the mixture is coated onto a titanium sheet and dried to serve as the positive electrode of an impact-resistant flexible aqueous zinc-ion battery.

[0015] Preferably, the negative electrode is zinc foil.

[0016] Compared with the prior art, this application has the following advantages:

[0017] (1) This application provides a method for preparing an impact-resistant flexible aqueous zinc-ion battery electrolyte. By mixing starch with Zn(CF3SO3)2 electrolyte, an impact-resistant flexible aqueous zinc-ion battery electrolyte can be prepared simply and on a large scale, which is beneficial for industrial expansion.

[0018] (2) Starch is inexpensive, widely available, and abundant, which helps reduce the production cost of impact-resistant flexible aqueous zinc-ion batteries.

[0019] (3) The impact-resistant flexible aqueous zinc-ion battery electrolyte prepared in this application has a shear thickening effect. When subjected to a large external force impact, the viscosity of the electrolyte increases rapidly and becomes a solid-like substance, which effectively resists external force, protects the battery, and improves safety.

[0020] (4) The impact-resistant flexible aqueous zinc-ion battery electrolyte prepared in this application has good fluidity under normal conditions and exhibits excellent ionic conductivity.

[0021] (5) The strong binding force between starch molecules and zinc ions causes starch to replace water molecules in the solvation structure, weakening the solvation effect, inhibiting the occurrence of hydrogen evolution side reaction, and improving the cycle life of zinc anode.

[0022] (6) The strong interaction between starch molecules and Zn(002) crystal plane induces zinc epitaxial deposition, which can inhibit the formation of zinc dendrites from the source. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 A schematic diagram illustrating the impact resistance of the electrolyte in a flexible aqueous zinc-ion battery.

[0025] Figure 2 The graph shows a comparison of the open-circuit voltage changes of the flexible Zn / / AlVO batteries obtained in Comparative Example 1 and Example 1 under impact energies of 0.26 J and 0.52 J, respectively.

[0026] Figure 3 The graph shows the current variation of the flexible Zn / / AlVO battery obtained in Comparative Example 2 under an impact energy of 1.96 J.

[0027] Figure 4In the figures, a~d represent the current changes of the flexible Zn / / AlVO battery obtained in Example 2 under impact energies of 1.96 J, 2.94 J, 3.92 J, and 4.9 J, respectively.

[0028] Figure 5 The image shows the SEM images of the AlVO cathode and zinc anode of the flexible Zn / / AlVO battery obtained in Comparative Example 2 after being subjected to an impact energy of 1.96 J.

[0029] Figure 6 The images show SEM images of the AlVO positive electrode (a~d) and zinc negative electrode (e~h) of the flexible Zn / / AlVO battery obtained in Example 2 after being subjected to impact energies of 1.96 J, 2.94 J, 3.92 J and 4.9 J, respectively.

[0030] Figure 7 This is a comparison chart of the cycle performance of the symmetrical batteries obtained in Comparative Example 3 and Example 3. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] Unless otherwise specified, the experimental methods used in the embodiments of this application are all conventional methods.

[0033] In the following examples and comparative examples, unless otherwise specified, all raw materials can be prepared by commercial purchase or conventional methods.

[0034] Zinc trifluoromethanesulfonate salt was mixed with deionized water to prepare a 1 M Zn(CF3SO3)2 electrolyte. Starch and Zn(CF3SO3)2 electrolyte were mixed evenly in different mass ratios to prepare an impact-resistant flexible aqueous zinc-ion battery electrolyte.

[0035] AlVO, a positive electrode active material, PVDF, a binder, and Super P, a conductive agent, were mixed and a suitable amount of NMP solvent was added. After grinding and homogenization, the mixture was coated onto a titanium sheet and dried to serve as the positive electrode for a shock-resistant flexible aqueous zinc-ion battery. Zinc foil was used as the negative electrode and co-assembled with the positive electrode and separator to form a flexible Zn / / AlVO battery. Zn(CF3SO3)2 solution and shock-resistant flexible aqueous zinc-ion battery electrolyte were used as the ion conduction medium, respectively. Based on this, the difference in shock resistance of the flexible Zn / / AlVO battery under the Zn(CF3SO3)2 electrolyte system and the shock-resistant electrolyte system was compared. Simultaneously, CR2032 coin cell symmetric batteries were assembled using zinc foil as both positive and negative electrodes to evaluate the stability of the zinc electrode under the Zn(CF3SO3)2 electrolyte system and the shock-resistant electrolyte system.

[0036] Example 1

[0037] 3 g of starch was mixed with 3 g of Zn(CF3SO3)2 electrolyte and stirred until homogeneous to obtain an impact-resistant flexible aqueous zinc-ion battery electrolyte with a starch mass ratio of 50%. Impact energies of 0.26 J and 0.52 J were applied to a flexible Zn / / AlVO battery using this impact-resistant flexible aqueous zinc-ion battery electrolyte, and the changes in open-circuit voltage were recorded.

[0038] Comparative Example 1

[0039] Impact energies of 0.26 J and 0.52 J were applied to flexible Zn / / AlVO cells using Zn(CF3SO3)2 electrolyte, and the changes in open-circuit voltage were recorded.

[0040] Example 2

[0041] 3 g of starch was mixed with 3 g of Zn(CF3SO3)2 electrolyte and stirred until homogeneous to obtain an impact-resistant flexible aqueous zinc-ion battery electrolyte with a starch mass ratio of 50%. Impact energies of 1.96 J, 2.94 J, 3.92 J, and 4.9 J were applied to a flexible Zn / / AlVO battery using this impact-resistant flexible aqueous zinc-ion battery electrolyte, and the current changes were recorded. The AlVO positive electrode and Zn negative electrode were characterized by SEM.

[0042] Comparative Example 2

[0043] A 1.96 J impact energy was applied to a flexible Zn / / AlVO cell using Zn(CF3SO3)2 electrolyte, the current change was recorded, and the AlVO positive electrode and Zn negative electrode were characterized by SEM.

[0044] Example 3

[0045] 3 g of starch was mixed with 3 g of Zn(CF3SO3)2 electrolyte and stirred evenly to obtain an impact-resistant flexible aqueous zinc-ion battery electrolyte with a starch mass ratio of 50%. The cycle stability of a Zn / / Zn symmetric battery using this impact-resistant flexible aqueous zinc-ion battery electrolyte was tested.

[0046] Comparative Example 3

[0047] Cyclic stability tests were conducted on Zn / / Zn symmetric cells using Zn(CF3SO3)2 electrolyte.

[0048] Figure 1 This is a schematic diagram illustrating the principle behind the shock-resistant flexible aqueous zinc-ion battery electrolyte. The electrolyte contains a large number of starch molecules, each containing abundant polymer chains. Under normal conditions, these polymer chains slide freely with the lubrication of water molecules, exhibiting excellent fluidity. However, under significant external impact, the lubricating water between the polymer chains is squeezed out, causing the chains to aggregate and entangle, forming clusters. This rapidly increases the viscosity of the electrolyte, transforming it into a near-solid state to resist the force. Once the external force is removed, the electrolyte instantly returns to its liquid state.

[0049] Figure 2 The graph shows a comparison of the open-circuit voltage changes of Comparative Example 1 and Example 1 under impact energies of 0.26 J and 0.52 J. Under the same impact energy, the open-circuit voltage change of the flexible Zn / / AlVO battery using Zn(CF3SO3)2 electrolyte is very significant, while the open-circuit voltage change of the flexible Zn / / AlVO battery using an impact-resistant flexible aqueous zinc-ion battery electrolyte is very small.

[0050] Figure 3 The graph shows the current change in Comparative Example 2 under an impact energy of 1.96 J. Figure 4 The graph shows the current changes in Example 2 under impact energies of 1.96 J, 2.94 J, 3.92 J, and 4.9 J. In Comparative Example 2, the battery failed after experiencing an impact energy of 1.96 J. However, in Example 2, the battery remained in normal condition after experiencing impact energies of 1.96 J, 2.94 J, and 3.92 J; it only failed after the impact energy increased to 4.9 J.

[0051] Figure 5 The image shows SEM images of the AlVO positive electrode and Zn negative electrode after being subjected to an impact energy of 1.96 J, as shown in Comparative Example 2. It can be seen that the surfaces of both the AlVO positive electrode and the Zn negative electrode have obvious cracks, indicating that the electrode structure has been damaged. Figure 6The images show SEM images of the AlVO positive and Zn negative electrodes after being subjected to impact energies of 1.96 J, 2.94 J, 3.92 J, and 4.9 J, respectively, in Example 2. As can be seen from the images, the AlVO positive and Zn negative electrodes remained smooth and flat under the impact energies of 1.96 J, 2.94 J, and 3.92 J, exhibiting structural stability. Damage to the electrode structure, with noticeable cracks appearing, only occurred after the impact energy increased to 4.9 J.

[0052] Figure 7 The cycling stability of Comparative Example 3 and Example 3 is compared. The cycling stability of the symmetrical battery in the example system is effectively improved, and it can cycle stably for 600 h with almost no significant change in polarization voltage. However, the polarization voltage of the symmetrical battery based on the comparative example begins to gradually increase after 380 h of cycling, and a short circuit occurs at 440 h.

[0053] In summary, under significant external impact, the viscosity of the electrolyte in a shock-resistant flexible aqueous zinc-ion battery rapidly increases, becoming almost solid to resist external stress and improve battery safety. Under the same impact energy, the open-circuit voltage and current changes of flexible batteries using this shock-resistant flexible aqueous zinc-ion battery electrolyte are much smaller than those using Zn(CF3SO3)2 liquid electrolyte, reducing the risk of electrochemical performance degradation or short circuits caused by impact stress. Furthermore, the strong binding force between starch molecules and zinc ions reduces the number of water molecules around the zinc ions, weakening solvation and inhibiting hydrogen evolution side reactions; the strong interaction between starch molecules and the Zn(002) crystal plane effectively induces zinc epitaxial deposition and inhibits zinc dendrite growth. Therefore, the starch electrolyte can protect the zinc anode. Based on the excellent electrochemical and shock resistance properties of the impact-resistant flexible aqueous zinc-ion battery electrolyte, the flexible battery exhibits excellent cycle stability and macroscopic structural stability, providing a new feasible approach for the preparation of impact-resistant flexible batteries. The impact-resistant flexible aqueous zinc-ion battery electrolyte prepared in this application can significantly improve the impact resistance, safety, and electrochemical stability of flexible aqueous zinc-ion batteries, and has high practical value.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing an impact-resistant flexible aqueous zinc-ion battery electrolyte, characterized in that, Includes the following steps: By mixing starch and Zn(CF3SO3)2 liquid electrolyte and stirring until homogeneous, an impact-resistant flexible aqueous zinc-ion battery electrolyte can be obtained.

2. The method for preparing the impact-resistant flexible aqueous zinc-ion battery electrolyte according to claim 1, characterized in that, The preparation process of the Zn(CF3SO3)2 liquid electrolyte is as follows: zinc trifluoromethanesulfonate salt is dissolved in deionized water and stirred evenly to obtain 1 M Zn(CF3SO3)2 liquid electrolyte.

3. The method for preparing the impact-resistant flexible aqueous zinc-ion battery electrolyte according to claim 1, characterized in that, The mass ratio of starch to Zn(CF3SO3)2 liquid electrolyte is (3~6):(4~7).

4. The method for preparing the impact-resistant flexible aqueous zinc-ion battery electrolyte according to claim 3, characterized in that, The mass ratio of starch to Zn(CF3SO3)2 liquid electrolyte is 3:7, 3.5:6.5, 4:6, 4.5:5.5, 5:5, 5.5:4.5 or 6:

4.

5. An impact-resistant flexible aqueous zinc-ion battery, characterized in that, It includes the impact-resistant flexible aqueous zinc-ion battery electrolyte as described in any one of claims 1 to 4.

6. The impact-resistant flexible aqueous zinc-ion battery according to claim 5, characterized in that, It also includes the positive electrode, negative electrode, and diaphragm.

7. The impact-resistant flexible aqueous zinc-ion battery according to claim 6, characterized in that, The preparation process of the positive electrode is as follows: the positive electrode active material AlV3O9, binder PVDF, and conductive agent Super P are mixed, and an appropriate amount of NMP solvent is added. After grinding evenly, the mixture is coated onto a titanium sheet and dried to serve as the positive electrode of an impact-resistant flexible aqueous zinc-ion battery.

8. The impact-resistant flexible aqueous zinc-ion battery according to claim 6, characterized in that, The negative electrode is zinc foil.

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