Biogenic conductive biosponge device for flexible zinc-air batteries

Abstract

A conductive biosponge device consisting of a porous nanocomposite structure of Plantago ovata shells, activated Saccharomyces cerevisiae, graphite, graphene, borax and glycerin, configured to provide electrical conductivity, flexibility and biodegradability, and is therefore suitable for energy storage applications.

Description

Application area of ​​the invention:

[0001] The invention relates to bio-based energy storage systems and materials, in particular an environmentally friendly, conductive nanocomposite biosponge made from Plantago ovata for use as an air electrode in flexible and portable zinc-air batteries. Background of the invention:

[0002] The rapid growth of wearable electronics, flexible sensors, and portable power systems has increased the demand for sustainable, lightweight, and biodegradable energy storage. Zinc-air batteries (ZABs) are considered one of the most promising energy storage technologies due to their high theoretical energy density, safety, and low cost. However, conventional air electrodes in ZABs are typically made from toxic chemicals, synthetic polymers, and expensive catalysts, limiting their environmental friendliness and scalability.

[0003] To overcome these limitations, biogenic and plant-based materials are gaining prominence as sustainable alternatives. The shells of Plantago ovata, which contain natural mucilage, offer excellent gelling properties, flexibility, and biodegradability. Microorganisms such as Saccharomyces cerevisiae can be used to create porosity and enhance conductivity during material formation. Combining these biological and carbon-based materials with conductive additives such as graphite and graphene can lead to a new class of bio-based, conductive sponges. Therefore, there is an urgent need for a bio-based, conductive, and flexible electrode system suitable for integration into portable and environmentally friendly zinc-air batteries. Summary of the invention:

[0004] The invention relates to a biogenic, conductive sponge component made from Plantago ovata and yeast, which serves as a flexible air electrode for zinc-air batteries. The component consists of a porous nanocomposite structure made from a mixture of Plantago ovata shells, activated Saccharomyces cerevisiae, graphite, graphene, borax, and glycerol. The interaction of the biological and conductive components results in a flexible, conductive, and highly porous material that enables efficient oxygen diffusion and charge transfer.

[0005] The conductive biosponge forms the core component of a zinc-air battery, which also includes a zinc anode, a hydrogel electrolyte made from Plantago ovata gel and saturated with potassium hydroxide and zinc acetate, and a manganese dioxide catalyst (MnO2) applied to the air electrode surface. The resulting device is characterized by high electrochemical efficiency, mechanical flexibility, and biodegradability, making it ideal for portable and mobile electronic systems. This invention thus offers a sustainable and cost-effective alternative to conventional synthetic electrodes. Detailed description:

[0006] The invention describes a biogenic, conductive sponge system that serves as the air electrode of a zinc-air battery. The system is made from Plantago ovata shells as a biopolymer matrix, Saccharomyces cerevisiae yeast as a biological porosity agent, and conductive fillers such as graphite and graphene. Borax serves as a crosslinking agent and glycerin as a plasticizer to improve elasticity and flexibility.

[0007] First, Saccharomyces cerevisiae is activated in a nutrient medium under controlled conditions to promote biological activity. Simultaneously, the husks of Plantago ovata are hydrated with distilled water to form a viscous hydrogel. The activated yeast culture is then mixed with the Plantago ovata hydrogel, graphite, graphene, borax, and glycerin to create a homogeneous composite mixture.

[0008] The mixture is poured into molds and subjected to mild heat treatment, which causes the structure to solidify into a three-dimensional, sponge-like matrix. During this process, yeast cells create micro- and nanopores that significantly increase the material's surface area and conductivity. The semi-solid composite is then carbonized at controlled temperatures to improve its electrical properties while maintaining its mechanical flexibility.

[0009] After carbonization, the resulting biosponge is washed, dried, and cut into electrode foils of the desired size and thickness. These foils form the air electrode layer of the zinc-air battery. The electrode surface is then coated with a manganese dioxide catalyst layer (MnO2) to improve the efficiency of the oxygen reduction reaction (ORR).

[0010] The zinc-air battery system produced according to the invention comprises the following main components: Zinc anode: A metallic zinc sheet that serves as a negative electrode. Plantago ovata-based hydrogel electrolyte: Produced by immersing Plantago ovata gel in an aqueous solution of potassium hydroxide (KOH) and zinc acetate to ensure ionic conductivity and flexibility. Conductive bio-sponge air electrode: A porous, biogenic nanocomposite that serves as a cathode.

[0011] The device operates in its assembled state through electrochemical reactions in which oxygen from the ambient air reacts with the biosponge cathode, generating a high discharge capacity and a stable voltage. The porosity of the biosponge ensures effective gas diffusion, and the flexible matrix allows the device to be bent, folded, or integrated into portable substrates without compromising performance.

[0012] The device is characterized by higher specific capacity, long-term stability, and superior flexibility compared to conventional electrodes. The biogenic components ensure low costs, environmental compatibility, and easy disposal at the end of its service life. The system can be manufactured using simple laboratory or industrial equipment without the use of toxic chemicals, thus enabling sustainable energy solutions on a large scale.

Claims

[1] A conductive biosponge device consisting of a porous nanocomposite structure of Plantago ovata shells, activated Saccharomyces cerevisiae, graphite, graphene, borax and glycerin, configured to provide electrical conductivity, flexibility and biodegradability, and is therefore suitable for energy storage applications. [2] A zinc-air battery system comprising a zinc anode, a hydrogel electrolyte formed from Plantago ovata saturated with potassium hydroxide and zinc acetate, and the conductive biosponge device according to claim 1, which serves as an air electrode. [3] Device according to claim 2, wherein the air electrode is coated with a manganese dioxide catalyst layer to improve the efficiency of the oxygen reduction reaction and the electrochemical performance. [4] A flexible and portable energy storage device comprising the zinc-air battery system according to claim 2, wherein the conductive biosponge electrode has a high specific capacity, a stable discharge potential and mechanical strength suitable for integration into portable and biodegradable electronic devices.