Preparation and application of a firm, biodegradable and recyclable straw protection film
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING INST OF TECH
- Filing Date
- 2025-09-12
- Publication Date
- 2026-06-30
AI Technical Summary
The thermodynamic instability of zinc metal anodes in aqueous electrolytes leads to hydrogen evolution reaction and dendrite growth, resulting in irreversible battery failure. Existing interface modification methods are complex and costly, making them difficult to commercialize.
A biomass interface layer was prepared by using straw protective film through hydrothermal pretreatment, alkali treatment and sulfonation treatment. This layer was then coated on the surface of zinc metal electrodes and diaphragms. The deposition of zinc ions was regulated by cellulose and sulfonate groups, thereby improving mechanical strength and water stability.
It achieves stable cycling performance of zinc metal electrodes, inhibits corrosion, promotes uniform zinc ion deposition, extends battery life and supports multiple reuses, and has good degradability.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the manufacture and application of a robust, biodegradable, and recyclable straw protective film, belonging to the field of zinc-ion battery technology. Background Technology
[0002] Due to the energy crisis and environmental pollution caused by fossil fuel combustion, lithium-ion batteries emerged. As a stable and efficient electrochemical energy storage device, lithium-ion batteries are widely used in various fields such as new energy vehicles, mobile devices, and intelligent robots. However, with increasing attention to environmental issues and battery safety, exploring new green, safe, and stable rechargeable battery systems is crucial. Therefore, zinc-ion batteries have gradually gained attention. Zinc-ion batteries have the following advantages: 1. Low cost and environmentally friendly, with inexpensive raw materials and manufacturing processes; 2. High volumetric capacity (5885 mAh cm⁻¹). −3 The zinc-ion battery possesses a moderate redox potential (−0.763 V vs. standard potential SHE); hydrated zinc ions exhibit a smaller radius and faster conductivity; and it has the potential for large-scale energy storage. Furthermore, aqueous zinc-ion batteries can, to some extent, fill the industry gaps in lithium-ion batteries and supercapacitors. The world's first zinc-ion battery factory has been built in Sweden and is expected to be operational in 2026. Domestic energy storage companies are also actively deploying pilot production lines for zinc-ion batteries to further promote their industrial application.
[0003] Despite the numerous advantages of zinc metal anodes, their application faces significant challenges. The main issues related to zinc metal anodes are as follows: 1. Zn / Zn 2+ The standard electrode potential is lower than H2 / H + The thermodynamic instability of zinc in aqueous electrolytes leads to hydrogen evolution reaction (HER) and chemical corrosion. Due to the uneven distribution of zinc ion flux and electric field at the electrode-electrolyte interface, zinc ions form rough and uneven deposits, promoting dendrite growth. Zn has a high Young's modulus (EZn≈108 GPa), making Zn dendrites more prone to proliferation. This means that once Zn dendrites form, they grow rapidly, leading to irreversible failure or even battery short circuits caused by separator breakdown.
[0004] Interface engineering is a common and effective strategy for regulating zinc ion deposition behavior and water molecule interaction, which can effectively mitigate zinc dendrite growth and side reactions at the zinc anode. Cellulose can rapidly conduct ions and uniformly increase the zinc ion flux at the anode interface; lignin coating the cellulose surface effectively isolates water molecules, improving the water stability of the cellulose membrane and the mechanical strength of the biomembrane; and sulfonic acid groups interact with Zn... 2+ Tight coordination and increased nucleation sites allow sulfonate groups to effectively guide the planar deposition of Zn(002) dominant crystal faces and promote the formation of Zn(H2O)6.2+ Desolvation can significantly improve the electrochemical performance of layered materials. However, most current interface modification methods are complex and costly, making them difficult to commercialize. Summary of the Invention
[0005] In view of this, the purpose of this invention is to provide a robust, biodegradable, and recyclable straw protective film and its application in aqueous zinc batteries.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows:
[0007] A robust, biodegradable, and recyclable straw protective film is prepared by the following method, the steps of which are as follows:
[0008] (1) The straw raw material was pretreated in a hydrothermal environment at a temperature of 145℃ for 1.5 h;
[0009] (2) The alkali treatment temperature was 95℃, the time was 60 min, and the alkali dosage was 4%. The chemically pretreated straw raw material was then milled in a disc mill under the following conditions: pulp consistency 20%, disc mill gap 0.075 mm, to prepare straw chemimechanical pulp fiber. During this process, most of the lignin, hemicellulose, and cellulose remained in the straw fiber.
[0010] (3) The straw mechanical pulp is redispersed in water, and a sulfonating agent is added and stirred at room temperature for 24 hours. The sulfonated straw mechanical pulp is obtained after the reaction is complete. 20 g of ionic liquid is slowly added to the sulfonated straw mechanical pulp and dissolved for 1.5-2.5 hours (90℃). The mixture is then transferred to a glass plate and coated into a film using a film scraper.
[0011] The mass ratio of alkali to straw slurry is 1:2.5, the mass ratio of sulfonating agent to straw mechanical pulp is 1:2, and the preferred concentration of both straw slurry and straw mechanical pulp is 1%.
[0012] 15 g of cellulose fiber, 72.25 g of NMMO, and 12.75 g of water were placed in a three-necked flask equipped with a mechanical stirrer. The mixture was stirred continuously at 110°C for one hour to ensure complete dissolution of the bamboo cellulose. The resulting cellulose solution was poured onto a glass plate and then washed with deionized water (10 L) to remove NMMO. Finally, the cellulose membrane was dried at room temperature.
[0013] In a first aspect, the present invention provides a method for preparing a biomass interface layer solution, comprising the following steps:
[0014] Straw raw materials are dispersed in deionized water and subjected to hydrothermal pretreatment to obtain straw slurry;
[0015] Add alkali to the mixed solution and treat it under dark conditions to obtain straw mechanical pulp;
[0016] The straw mechanical paddles were redispersed in water, and a sulfonating agent was added and stirred at room temperature to react.
[0017] The sulfonated cellulose mechanical pulp, ionic liquid, and deionized water are uniformly mixed.
[0018] Secondly, the present invention also provides a method for preparing a polymer interface layer modified zinc metal electrode, comprising the following steps:
[0019] The polymer interface layer solution prepared by the above preparation method is coated onto the surface of the zinc metal electrode. After the solvent evaporates, a biofilm interface layer modified zinc metal electrode is obtained.
[0020] Preferably, the method for preparing the polymer interface layer modified zinc metal electrode involves coating 100-500 μL of biofilm solution onto the surface of the zinc metal electrode.
[0021] And / or, the coating method includes any one of the following: casting, spin coating, and pressing.
[0022] Thirdly, the present invention also provides a method for preparing a biomembrane-modified diaphragm, comprising the following steps:
[0023] The biofilm solution prepared by the above method is coated onto the surface of the diaphragm, and after the solvent evaporates, a biofilm-modified diaphragm is obtained.
[0024] Preferably, the method for preparing the biomembrane-modified diaphragm involves coating 5 ml of biomembrane solution onto the diaphragm surface.
[0025] And / or, the diaphragm includes any one of glass fiber or PP diaphragm;
[0026] And / or, the biofilm solution is coated onto the membrane surface, and the solvent is evaporated at room temperature to obtain a biofilm-modified membrane;
[0027] And / or, the coating method includes any one of the following: casting, spin coating, and blade coating.
[0028] Beneficial effects
[0029] 1. The biomass solution of the present invention effectively utilizes agricultural waste and retains lignin to improve the mechanical strength of the biofilm; the biomass interface layer solution of the present invention is coated on the surface of zinc metal electrode and solid electrolyte to obtain a polymer interface layer. This interface layer has advantages such as good mechanical properties, low cost and high water stability, and can better solve the reaction between zinc metal electrode and electrolyte and the formation of passivation layer, thereby inhibiting the corrosion of zinc negative electrode.
[0030] 2. The biofilm interface layer formed by the biofilm solution of the present invention has high hydrophilicity and can selectively promote Zn 2+ The migration of zinc ions is controlled to achieve uniform deposition of zinc metal.
[0031] 3. The preparation method of the biofilm solution of the present invention selects sulfonate groups, which not only ensures the stability of the interface layer's own structure during battery cycling, but also effectively guides the flat deposition of Zn(002) crystal planes.
[0032] 4. This invention applies the designed biomembrane to zinc metal anodes and zinc-ion batteries, achieving ultra-long and stable cycle performance. It can be reused multiple times and is easily degraded, showing broad application prospects in energy storage. Attached Figure Description
[0033] Figure 1 The image shows the X-ray photoelectron spectroscopy (XPS) spectrum of the biomass membrane prepared in Example 1.
[0034] Figure 2 The diagram shows the tensile properties of the biomembranes prepared in Example 1 and Comparative Example 1.
[0035] Figure 3 The graph shows the electrochemical cycling performance of the symmetrical cells assembled in Example 1 and Comparative Example 2.
[0036] Figure 4 The graph shows the electrochemical cycling performance of the asymmetric battery assembled in Example 1.
[0037] Figure 5 The graph shows the electrochemical cycling performance of the symmetrical cells assembled in Example 1 and Comparative Example 2. Detailed Implementation
[0038] The present invention will be further described in detail below with reference to specific embodiments.
[0039] Example 1
[0040] 0.2g of sulfonated wheat straw fiber was slowly added to 20g of ionic liquid and dissolved at 90℃ for 1.5-2.5h. The mixture was then transferred to a glass plate and coated into a film using a film scraper. The film was then quickly immersed in deionized water for 24h, during which time the deionized water was replaced 3-4 times. The film was then dried at room temperature.
[0041] XPS test results of the biofilm show that the composite layered cathode material has successfully linked sulfonate groups compared to the bulk fiber material of Comparative Example 1.
[0042] Example 2
[0043] The biofilm applied above was cut into pieces with a length of 30 mm and a width of 10 mm.
[0044] The cut biofilm was placed in a tensile testing fixture and the test was started at a loading speed of 1 mm / min to test its mechanical strength in the dry state. The cut biofilm was placed in deionized water and left to stand for 12 h. After soaking, the biofilm was wiped dry and placed in a tensile testing fixture and the test was started at a loading speed of 1 mm / min to test its mechanical strength in the wet state.
[0045] The tensile test results of the biomembrane show that, compared with the bulk fiber material of Comparative Example 1, the composite layered cathode material has increased dry tensile strength and wet tensile strength, which are 75 MPa and 28.75 MPa, respectively.
[0046] Example 3
[0047] The biofilm coated above was cut into Φ11.3 mm pieces. The surface of commercial zinc foil (100 μm) was cleaned and cut into Φ11.3 mm round pieces to make zinc electrodes.
[0048] The positive electrode shell was placed on the experimental platform with its inner surface facing upwards. The zinc electrode, biomembrane, separator, biomembrane, zinc electrode, and gasket were then placed in sequence. The electrolyte was then dripped in to completely wet the separator. The negative electrode shell was then placed on top, and the battery was packaged using a button cell packaging machine to obtain a zinc-symmetric battery. The cycle life of the zinc-symmetric battery is as follows: Figure 3 As shown, at 2 mA·cm -2 The current density and 2 mAh·cm -2 At the area capacity, it can cycle stably for more than 700 hours.
[0049] Example 4
[0050] The biofilm coated above was cut into Φ11.3 mm discs to form a zinc electrode protective layer; the surface of commercial zinc foil (100 μm) was cleaned and cut into Φ11.3 mm discs to form a zinc electrode; the surface of commercial copper foil was cleaned and cut into Φ20.1 mm discs to form a copper electrode.
[0051] The positive electrode shell was placed on the experimental platform with its inner surface facing upwards. A copper electrode, separator, biofilm, zinc electrode, and gasket were then placed in sequence. The electrolyte solution was then added to completely wet the separator. The negative electrode shell was then placed on top, and the zinc-copper asymmetric battery was obtained by encapsulation using a button cell packaging machine. The cycle life of the zinc symmetric battery is as follows: Figure 4 As shown, at 5 mA·cm -2 Current density and 1 mAh·cm -2 With a given area capacity, it can stably cycle for more than 3,000 times, achieving a coulomb efficiency of 99.8%.
[0052] Example 5
[0053] The coated biofilm was cut into Φ11.3 mm pieces, and the surface of commercial zinc foil (100 μm) was cleaned and cut into Φ11.3 mm round pieces to make zinc electrodes.
[0054] The positive electrode shell was placed on the experimental platform with its inner surface facing upwards. The zinc electrode, biomembrane, separator, biomembrane, zinc electrode, and gasket were then placed in sequence. The electrolyte was then dripped in to completely wet the separator. The negative electrode shell was then placed on top, and the battery was packaged using a button cell packaging machine to obtain a zinc-symmetric battery. The cycle life of the zinc-symmetric battery is as follows: Figure 5 As shown, at 10 mA·cm -2 Current density and 1 mAh·cm -2 At the area capacity, it can cycle stably for more than 550 hours.
[0055] Comparative Example 1
[0056] 0.2 g of fiber was slowly added to 20 g of ionic liquid and dissolved at 90 °C for 1.5-2.5 h. The mixture was then transferred to a glass plate and coated into a film using a film scraper. The film was then quickly immersed in deionized water for 24 h, during which time the deionized water was replaced 3-4 times. The film was then dried at room temperature.
[0057] The biofilm applied above was cut into pieces with a length of 30 mm and a width of 10 mm.
[0058] The cut biofilm was placed in a tensile testing fixture and the test was started at a loading speed of 1 mm / min to test its mechanical strength in the dry state. The cut biofilm was placed in deionized water and left to stand for 12 h. After soaking, the biofilm was wiped dry and placed in a tensile testing fixture and the test was started at a loading speed of 1 mm / min to test its mechanical strength in the wet state.
[0059] The tensile test results of the biomembrane show that, compared with the bulk fiber material of Comparative Example 1, the composite layered cathode material has increased dry tensile strength and wet tensile strength, which are 61.25 MPa and 17.5 MPa, respectively.
[0060] Comparative Example 2
[0061] 0.2 g of raw wheat straw fiber was slowly added to 20 g of ionic liquid and dissolved at 90 °C for 1.5-2.5 h. The mixture was then transferred to a glass plate and coated into a film using a film scraper. The film was then quickly immersed in deionized water for 24 h, during which time the deionized water was replaced 3-4 times. The film was then dried at room temperature.
[0062] Comparative Example 3
[0063] The biofilm coated above was cut into Φ11.3 mm pieces. The surface of commercial zinc foil (100 μm) was cleaned and cut into Φ11.3 mm round pieces to make zinc electrodes.
[0064] The positive electrode shell was placed on the experimental platform with its inner surface facing upwards. The zinc electrode, biomembrane, separator, biomembrane, zinc electrode, and gasket were then placed in sequence. The electrolyte was then dripped in to completely wet the separator. The negative electrode shell was then placed on top, and the battery was packaged using a button cell packaging machine to obtain a zinc-symmetric battery. The cycle life of the zinc-symmetric battery is as follows: Figure 4 As shown, at 2 mA·cm -2 The current density and 2 mAh·cm -2 At the area capacity, it only cycled stably for 280 hours.
[0065] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.
Claims
1. A method for manufacturing and applying a robust, biodegradable, and recyclable straw protective film, characterized in that, Agricultural residues are used to form a uniform functional layer on the surface of the zinc metal anode or diaphragm. The straw mentioned mainly includes straw from grasses and legumes. Among them, straw from grasses mainly includes wheat straw, rice straw, corn straw, sorghum straw, buckwheat straw, millet straw, and rice straw; straw from legumes mainly includes any one of soybean straw, broad bean straw, pea straw, and peanut vines.
2. The robust, biodegradable, and recyclable straw protective film according to claim 1, characterized in that, It is simple and easy to implement, and can be readily applied on a large scale for commercial use.
3. The robust, biodegradable, and recyclable straw protection as described in claim 2, characterized in that, It has high hydrophilicity and can selectively promote Zn 2+ The migration of zinc ions is controlled to achieve uniform deposition of zinc metal.
4. A robust, biodegradable, and recyclable straw protection system according to claim 4, characterized in that, The specific steps include: S1. The glass is cleaned by physical methods, and / or the coating method includes any one of casting, spin coating, and pressing, and the resulting SLC biofilm is cut into a suitable size. S2. The metal / diaphragm negative electrode is cleaned by physical methods, and / or the coating method includes any one of casting, spin coating, and pressing, and the resulting SLC biofilm coated component is cut to an appropriate size. S3. Dry the material after the above treatment at room temperature to obtain a negative electrode or membrane with a biomass interface on the surface.
5. The fabrication of a biomass-derived, scalable protective film according to claim 4, characterized in that, The processing methods and parameters need to be adjusted depending on the different specifications and sizes used in steps S1-2.