Aqueous zinc ion battery diaphragm based on reed membrane as well as preparation method and application of aqueous zinc ion battery diaphragm

Abstract

The invention belongs to the field of material science and batteries, and particularly discloses a water-based zinc ion battery diaphragm based on a reed membrane as well as a preparation method and application of the water-based zinc ion battery diaphragm. The practical application key of the aqueous zinc ion battery is to effectively control the interface of the zinc electrodeposition chemical process. The invention provides an innovative scheme that a biomass fiber diaphragm of reed is introduced as a tight artificial interface to serve as natural zinc ions to regulate skin so as to protect a zinc metal anode. The natural biomass fiber reed diaphragm disclosed by the invention has the following inherent characteristics: the natural biomass fiber reed diaphragm has multi-scale ion transmission channels, rich hydroxyl groups (-OH), good electrolyte wettability and excellent mechanical properties, and a firmly attached interface covering layer can be formed on the surface of a zinc anode by using the reed diaphragm, so that the dendrite-free zinc anode is finally ensured; therefore, the performance and the safety of the battery are improved. The invention provides an economical, efficient and environment-friendly strategy for realizing the stable zinc anode in the aqueous battery.

Description

Technical Field

[0001] The invention relates to the fields of material science and batteries, and in particular to a reed membrane-based aqueous zinc ion battery diaphragm and a preparation method and application thereof. Background Art

[0002] In the field of energy storage, ion batteries have been widely studied and applied due to their high energy density and long life. Among them, aqueous zinc-ion batteries are considered to be a highly promising next-generation energy storage technology due to their environmental friendliness, low cost and high safety. However, the practical application of aqueous zinc-ion batteries faces some challenges, mainly including interface control and dendrite growth problems during zinc electrodeposition. During zinc electrodeposition, the reduction of zinc ions on the electrode surface leads to the formation of zinc metal. If this process cannot be effectively controlled, it may cause uneven deposition of zinc metal on the electrode surface, forming dendrites. These dendrites may pierce the diaphragm, causing the battery to short-circuit and fail.

[0003] For the above problems, the existing solutions are mainly to control the zinc electrodeposition process by optimizing the electrolyte composition, additives and diaphragm materials. For example, some studies change the solvation structure of zinc ions by adding complexing agents or surfactants, thereby inhibiting the dendrite growth of zinc metal. In addition, some studies improve the interface stability and mechanical strength of the battery by using special diaphragm materials such as polymer membranes or ceramic membranes.

[0004] Although existing solutions can improve the performance of aqueous zinc-ion batteries to a certain extent, there are still some problems. The addition of additives to change the solvation structure of zinc ions may affect the electrochemical performance of the battery; and existing diaphragm materials, such as polymer membranes and ceramic membranes, usually have poor ionic conductivity and mechanical strength, which may limit the performance and life of the battery, and special diaphragm materials may also increase the production cost of the battery. Therefore, how to effectively control the zinc electrodeposition process, especially how to find a diaphragm material that can effectively control the zinc electrodeposition process and maintain good battery performance, is still a key issue that needs to be solved in the field of aqueous zinc-ion batteries. Summary of the invention

[0005] The purpose of the present invention is to provide a water-based zinc ion battery diaphragm based on reed film, a preparation method and application thereof, wherein the prepared reed biomass diaphragm can effectively regulate the flow of zinc ions, thereby promoting uniform zinc deposition and inhibiting the growth of zinc dendrites. Moreover, through in-situ electrochemical bonding with the zinc electrode, the reed film forms a strong protective layer on the surface of the zinc anode, enhancing the stability of the zinc metal anode and the cycle performance of the battery.

[0006] In order to achieve the above object, the specific technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a water-based zinc ion battery separator based on a reed membrane, comprising the following steps:

[0008] S1. Using biomass reed film as raw material, cutting it; the biomass reed film has multi-scale ion transport tunnels, rich OH groups, ultra-thin thickness, smooth morphology and high flatness;

[0009] S2. Dry the reed membrane obtained in step S1 to obtain a reed membrane-based aqueous zinc ion battery separator.

[0010] Further, in step S1, the thickness of the biomass reed film is 2-20 μm. The thickness of the aqueous zinc ion battery separator needs to strike a balance between ionic conductivity, mechanical strength, electrolyte retention capacity and cycle performance. Appropriate separator thickness can improve the overall performance and safety of the battery and extend the cycle life of the battery. The effects of separator thickness on the performance of aqueous zinc ion batteries are as follows: 1) Ionic conductivity: The thickness of the separator directly affects the ion transmission path; thinner separators can provide shorter ion transmission paths, thereby improving the ionic conductivity and electrochemical properties of the battery; excessive thickness will increase the resistance to ion transmission, resulting in an increase in the internal resistance of the battery, affecting the overall performance of the battery. 2) Mechanical strength and puncture resistance: The thickness of the separator also affects its mechanical strength and puncture resistance; thicker separators generally have better mechanical strength, but may affect the electrolyte retention capacity; moderate separator thickness can strike a balance between mechanical strength and electrolyte retention capacity, providing good puncture resistance and cycle stability. 3) Electrolyte retention capacity: The thickness of the diaphragm affects the electrolyte retention capacity in the battery; thicker diaphragms may reduce the amount of electrolyte absorbed and affect the battery's cycle performance; appropriate diaphragm thickness can ensure sufficient electrolyte retention, provide a good electrolyte environment, and support long-term battery cycling. 4) Cycle performance and safety: The thickness of the diaphragm also affects the battery's cycle performance and safety; appropriate diaphragm thickness can effectively inhibit the growth of zinc dendrites and improve the battery's cycle life and safety; too thin diaphragms may not be able to effectively prevent the growth of zinc dendrites, resulting in battery short circuits and performance degradation. 5) Battery self-discharge rate: The thickness of the diaphragm also affects the battery's self-discharge rate; appropriate diaphragm thickness can reduce the battery's self-discharge during storage and improve the battery's energy efficiency.

[0011] Furthermore, in step S1, the biomass reed film is cut into 18 mm round pieces.

[0012] Furthermore, in step S1, the biomass reed film is a commercial reed film.

[0013] Furthermore, in step S2, the drying method is one of sun drying, air drying, oven drying, and vacuum drying, and the drying time is 1-8 hours. The degree of dryness of the diaphragm is directly related to multiple performance indicators of the battery, such as safety, capacity, and cycle life, as follows: 1) Safety: The moisture contained in the diaphragm that is not fully dried may cause short circuits or other safety hazards in a high temperature environment. The drying process can effectively reduce the risk of internal short circuits in the battery and improve the safety performance of the battery. 2) Capacity and cycle life: The degree of dryness of the diaphragm will also affect the capacity and cycle life of the battery. Proper drying can ensure that the diaphragm has good mechanical strength and thermal stability, thereby improving the overall performance of the battery. 3) Electrolyte absorption capacity: Drying treatment can improve the diaphragm's ability to absorb electrolytes, thereby improving the ionic conductivity of the battery, which is crucial to improving the performance of the battery.

[0014] In a second aspect, the present invention provides a reed membrane-based aqueous zinc ion battery separator prepared using the above-mentioned preparation method.

[0015] In a third aspect, the present invention provides an application of the reed membrane-based aqueous zinc ion battery separator prepared by the above preparation method in the preparation of an aqueous zinc ion battery. The application method is to assemble the reed membrane and zinc sheet together into an aqueous zinc ion battery.

[0016] The present invention has the following beneficial effects:

[0017] 1. The present invention adopts natural biomass raw materials and prepares an ultra-thin reed diaphragm through an economical and convenient method. The surface of the diaphragm is rich in hydroxyl groups, has good electrolyte affinity and high mechanical strength.

[0018] 2. The rich ─OH groups and nanoscale ion regulation channels of the reed membrane prepared by the present invention promote uniform Zn 2+ flow, enhanced [Zn(H2O)6] 2+ The desolvation process of ZnO2 was accelerated and the formation of Zn dendrites was effectively suppressed.

[0019] 3. During the zinc electrode deposition process, the reed film prepared by the present invention forms a strong bond with the zinc electrode through the Zn-O bond, providing an effective protective covering layer for the zinc anode surface.

[0020] In summary, the present invention provides a bio-inspired interface membrane design concept, which provides a new idea for realizing a stable and reversible zinc anode in aqueous zinc ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The morphology of reed membrane: a is an optical photograph of reed (left) and purchased commercial reed membrane (right); b and c are SEM morphology images of the surface and cross-section of the reed membrane, respectively.

[0022] Figure 2 Optical photographs of reed membranes under different mechanical states (d) and stress-strain curves of reed membranes and commercial glass fiber diaphragms under different states (e).

[0023] Figure 3 This is the Fourier transform infrared spectrum (FTIR) of the reed film.

[0024] Figure 4 (a) and (b) are the electrochemical stability data of reed membrane and GF membrane, and the ionic conductivity data. Figure 5 Polarization characteristic impedance spectra of reed membrane (a) and GF membrane (b) assembled into Zn / / Zn symmetric battery before and after polarization.

[0025] Figure 6 Electrochemical impedance spectroscopy (EIS) spectra of reed membrane (a) and GF membrane (b) after assembly into Zn / / Zn symmetric battery.

[0026] Figure 7 Cycling performance of Zn / / Zn symmetric battery assembled with reed membrane and GF membrane under different conditions: (a) Current density of 3 mA cm -2 / 1.5mAh cm -2 , (b) current density is 5 mA cm -2 / 5mAh cm -2 .

[0027] Figure 8 Reed separator (a) and GF separator (b) after assembling into Zn / / Zn symmetric battery at a current density of 3 mA cm -2 / 1.5mAh cm -2 SEM cross-sectional image of the zinc electrode surface after cycling for 1 h.

[0028] Fig. 9 This is the O1s and Zn2p X-ray photoelectron spectroscopy (XPS) spectra of the battery after assembly into a zinc / reed separator / zinc symmetric battery. DETAILED DESCRIPTION

[0029] The present invention effectively solves the problems of interface control and dendrite growth in the zinc electrodeposition process faced by existing aqueous zinc ion batteries in practical applications through the following aspects: 1) A new type of diaphragm material, a biomass fiber reed diaphragm, is provided. The material has good ionic conductivity, sustainability and good mechanical strength, and can effectively control the zinc electrodeposition process, thereby improving the performance and life of aqueous zinc ion batteries. 2) The present invention prepares the reed diaphragm through a simple and easy process. Compared with existing polymer membranes and ceramic membranes, the process is simple, low-cost and easy to mass produce. 3) The present invention uses a series of testing and characterization methods such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), mechanical property testing, electrochemical measurement, etc., to comprehensively evaluate the performance of the diaphragm and its overall performance in the battery, as well as analyze the structure and characteristics of the membrane material, providing a basis for further optimizing the diaphragm material.

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0031] Example 1

[0032] This embodiment provides a method for preparing a water-based zinc ion battery diaphragm based on a reed membrane, and assembling the prepared diaphragm into a half-cell, as follows:

[0033] 1) First, a commercial reed membrane with a thickness of about 2 μm (appearance Figure 1 As shown in the right of a, it was purchased from Longfei Di Membrane Factory in Xinji Town, Wuhe County, with specifications of 15 cm in length and 4.5 cm in width) and cut into discs with a diameter of 18 mm. The reed membrane obtained after cutting was then placed in a vacuum oven and baked at 50°C for 8 hours to remove moisture, thereby obtaining a water-based zinc ion battery separator based on the reed membrane.

[0034] 2) The dried reed membrane was taken out and assembled together with a zinc sheet with a diameter of 12 mm and a thickness of 80 μm into a zinc / reed membrane / SS (stainless steel) half-cell. As a control, a commercial glass fiber membrane (GF) of the corresponding size was also assembled into a zinc / GF membrane zinc / (stainless steel) half-cell. The electrolyte used in both was 2 mol / L ZnSO4 solution.

[0035] Example 2

[0036] This embodiment provides a method for preparing a water-based zinc ion battery diaphragm based on a reed membrane, and assembling the prepared diaphragm into a symmetrical battery, as follows:

[0037] 1) The preparation method of the aqueous zinc ion battery separator based on reed membrane is the same as that in Example 1.

[0038] 2) The reed membrane prepared in 1) was assembled into a CR2025 button cell, i.e., a zinc / reed membrane / zinc symmetrical cell. As a control, a commercial glass fiber membrane (GF) of corresponding size was also assembled into a zinc / GF membrane / zinc symmetrical cell. The electrolyte used in both cells was a 2 mol / L ZnSO4 solution.

[0039] Characterization and Testing:

[0040] 1) Diaphragm test

[0041] The following tests were performed on the diaphragms used in Examples 1 and 2: A scanning electron microscope (SEM) TESCANMIRA3 LM instrument was used to characterize the SEM morphology of the reed membrane material, and a Fourier transform infrared spectroscopy (FTIR) Nicolet iS50 spectrometer was used to record the FTIR spectrum of the reed membrane material. A WDW-01D universal testing machine was used to measure the mechanical properties of the reed diaphragm and GF diaphragm in dry and wet states.

[0042] Test results such as Figure 1-3 The results are analyzed as follows:

[0043] like Figure 1 The surface morphology of the purchased commercial reed membrane is shown in the scanning electron microscope (SEM) image ( Figure 1 b), showing its smooth morphology and high flatness. Figure 1 c shows a side view of the reed membrane, showing that it is composed of multiple layers of cellulose sheets with tiny ion transport channels, which helps to achieve uniform Zn on the zinc electrode surface. 2+ flow.

[0044] like Figure 2 As shown in middle d, the reed membrane can maintain good mechanical properties in both the straight state and the twisted state. Figure 2 The tensile properties of the reed membrane are provided in the paper, showing that its yield strength in the dry state is about 37MPa and its strength in the wet state is 32.3MPa, which is much higher than the 0.6MPa of the dry glass fiber membrane, indicating the superiority of the reed membrane in mechanical strength and toughness. These properties enable the reed membrane to effectively resist the penetration of zinc dendrites when used as a separator for zinc electrodes.

[0045] like Figure 3 As shown, the functional groups in the reed membrane were detected by Fourier transform infrared spectroscopy (FTIR). It can be seen that at 3353 cm -1 and 1058cm -1 Represents the characteristic peaks of ─OH and C─O─C stretching vibrations of typical biomass cellulose.

[0046] 2) Half-battery test

[0047] The following tests were performed on the half-cell assembled in Example 1: The electrochemical stability of the zinc / / SS (stainless steel) half-cell prepared in Example 1 was measured by scanning voltammetry (LSV).

[0048] The results are as follows Figure 4 As shown in Figure 2, the electrochemical stability of the Zn / / SS (stainless steel) half-cell was determined by scanning voltammetry (LSV). Figure a shows the electrochemical stability of the Zn / / SS (stainless steel) half-cell at a scan rate of 0.01 V s -1 In the case of Zn / / SS half-cell, the electrochemical stability of the reed separator and the commercial GF separator was found to be similar. The ionic conductivity of the reed separator was calculated to be 14.2 mS cm -1 , compared with 15.9 mS cm of commercial GF membrane -1 The difference is small, indicating that the reed diaphragm is efficient in Zn 2+ Transmission behavior.

[0049] 3) Symmetrical battery test

[0050] The following tests were performed on the symmetrical battery assembled in Example 2: The zinc ion migration number (tZn 2+ ). The chronoamperometry (CA) method was used to measure the change of current over time, and the electrochemical impedance spectroscopy (EIS) was used to measure the ionic conductivity of the battery and the electrochemical reaction kinetics at the electrode interface to evaluate the stability of the battery. X-ray photoelectron spectroscopy (XPS) analysis was performed using a K-Alpha spectrometer.

[0051] The results are as follows Figure 5-9 The specific analysis is as follows:

[0052] like Figure 5 As shown in Figure a and b, the comparison of commercial GF separators shows that the characteristic impedance spectrum of the reed separator before and after polarization after being assembled into a zinc / / zinc symmetrical battery shows a higher Zn 2+ migration number (0.37vs 0.12), indicating that the reed film is beneficial to Zn 2+ migrate.

[0053] Figure 6 The electrochemical impedance spectroscopy (EIS) spectra of the reed separator and the GF separator after being assembled into a zinc / / zinc symmetric battery. Figure 6 As shown, compared with the commercial GF membrane, the reed membrane of the present invention has a higher Zn 2+ Conduction number, Zn 2+ The transport kinetics of ZnO2 are greatly improved, which can alleviate the concentration polarization phenomenon at the electrode interface and improve the stability and reversibility of the zinc anode.

[0054] like Figure 7 As shown in Figure a, the current density is 3 mA cm -2 / 1.5mAh cm -2 When the middle separator of the zinc / / zinc symmetric battery is a reed membrane, the battery exhibits an ultra-long cycle life of about 1450 h, which is much higher than the 114 h of the commercial GF membrane. The current density in Figure b is 5 mA cm -2 / 5mAh cm -2 When the middle separator of the Zn / / Zn symmetric battery is a reed membrane, the battery exhibits a cycle life of about 260 hours, while the commercial GF separator is only about 25 hours. This is due to the growth of Zn dendrites caused by interface instability, which eventually leads to battery short circuit.

[0055] Figure 8 To assemble a Zn / / Zn symmetric battery, the reed separator and the GF separator were subjected to a current density of 3 mA cm -2 / 1.5mAhcm -2 SEM cross-sectional image of the zinc electrode surface after 1 hour of cycling. In Figure a, the zinc electrode shows a smooth and flat surface without zinc dendrites, while in Figure b, a large number of mixed zinc dendrites appear on the zinc electrode surface under the action of the glass fiber diaphragm.

[0056] Fig. 9 The O1s and Zn2p X-ray photoelectron spectroscopy (XPS) spectra of the battery after assembling the zinc / reed separator / zinc symmetric battery. In contrast, the O1s XPS spectrum of the biomass reed membrane shows the characteristic C─O bond of cellulose at 532.5V. In addition, a new characteristic peak of the Zn─O bond was found at about 532.1V. The analysis of the Zn2p XPS spectrum results shows that the reed membrane also shows an increasing trend in the corresponding Zn─O bond content as the number of cycles increases. This shows that an electrochemical interaction occurs between the reed membrane and the zinc electrode. During the cycle process, a Zn-O bond is formed between the reed membrane and the zinc electrode, generating an effective protective covering layer to ensure the stability and reversibility of the zinc anode.

[0057] This specific implementation is only an explanation of the present invention, not a limitation of the present invention. Any changes made by those skilled in the art after reading the specification of the present invention will be protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for preparing a water-based zinc ion battery separator based on a reed membrane, characterized in that: The following steps are involved: S1. Using biomass reed film as raw material, cutting it; the biomass reed film has multi-scale ion transport tunnels, rich OH groups, ultra-thin thickness, smooth morphology and high flatness; S2. Dry the reed membrane obtained in step S1 to obtain a reed membrane-based aqueous zinc ion battery separator.

2. The method for preparing a water-based zinc ion battery separator based on a reed film according to claim 1, characterized in that: In step S1, the thickness of the biomass reed film is 2-20 μm.

3. The method for preparing a water-based zinc ion battery separator based on a reed film according to claim 1, characterized in that: In step S1, the biomass reed film is cut into 18 mm round pieces.

4. The method for preparing a water-based zinc ion battery separator based on a reed film according to claim 1, characterized in that: In step S1, the biomass reed film is a commercial reed film.

5. The method for preparing a water-based zinc ion battery separator based on a reed film according to claim 1, characterized in that: In step S2, the drying method is one of sun drying, air drying, oven drying, and vacuum drying, and the drying time is 1-8 hours.

6. A water-based zinc ion battery separator based on reed membrane prepared by the preparation method described in any one of claims 1 to 5.

7. Use of the reed membrane-based aqueous zinc ion battery separator according to claim 6 in the preparation of aqueous zinc ion batteries.

Images