Zinc-Air Batteries: DST’s Nanofluid Electrolyte Innovation Explained

Subject: GS 03: Science and Technology

Context: Researchers at SASTRA Deemed University, with support from the Department of Science and Technology (DST), have developed a low-cost nanofluid electrolyte that improves the efficiency, safety, and durability of rechargeable zinc-air batteries. 

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What are Zinc-Air Batteries?

• A type of battery that generates electricity through a reaction between zinc metal and oxygen from the air.
• Working Principle: Zinc-Air Batteries generate electricity using zinc as the anode and oxygen from ambient air as the cathode reactant.
• Key Components: Consist of a zinc anode, an air cathode, and an electrolyte (typically aqueous in rechargeable designs).
• Water-Based Chemistry: Use a water-based electrolyte in rechargeable designs, making them safer than many lithium-ion batteries.
• Key Advantages: Offer high energy density, use abundant and low-cost zinc, and are cheaper than lithium-ion batteries.
• Commercialisation Challenges: Rechargeable zinc-air batteries face challenges such as:
  • Zinc corrosion, which reduces battery life and efficiency.
  • Dependence on costly platinum- and ruthenium-based catalysts for oxygen reactions.

Types of Zinc-Air Batteries

• Primary (Non-Rechargeable): Single-use batteries with high energy density.
  • Used in hearing aids, medical devices, and small electronic devices.
• Secondary (Rechargeable): Rechargeable batteries suitable for electric vehicles (EVs) and grid-scale energy storage.
  • Commercialisation is limited by zinc corrosion, hydrogen evolution, and the need for efficient catalysts.

Zinc-Air Batteries vs Lithium-Ion Batteries

Key Highlights of the Technology Developed

• Nanofluid Electrolyte: Researchers developed a low-cost nanofluid electrolyte by incorporating silica (SiO₂) and zinc oxide (ZnO) nanoparticles into the battery electrolyte.
• Improved Battery Performance: The developed nanofluid electrolyte remains stable for over three months, improves the efficiency of the air cathode, and protects the zinc anode from corrosion.
• Low-Cost Corrosion Control: The nanofluid electrolyte, instead of relying on expensive corrosion inhibitors, reduces hydrogen gas formation, limits zinc corrosion, and enhances oxygen reduction and oxygen evolution reactions, addressing multiple battery performance issues through a single low-cost solution.
• Copper-Doped Catalyst: Researchers developed a copper-doped manganese dioxide catalyst that outperformed commercial platinum- and ruthenium-based catalysts in laboratory tests.
• Waste-Derived Carbon Materials: Researchers converted discarded household water-filter carbon and used surgical face masks into high-performance carbon materials for use in batteries and supercapacitors, providing a sustainable waste-to-energy solution.
• Future Applications: The developed nanofluid electrolyte and waste-derived carbon materials can also be adapted for other battery systems, supporting wider clean-energy applications.

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Significance of the Technology

• Improved Commercial Viability: Makes rechargeable zinc-air batteries more efficient, safer, cheaper, and commercially viable.
• Clean Energy Applications: Can support large-scale energy storage, electric vehicles (EVs), and other clean energy applications.
• Reduced Reliance on Precious Metals: Reduces dependence on costly platinum- and ruthenium-based catalysts.
• Sustainable Waste Utilisation: Promotes resource efficiency/circular economy by converting household water-filter carbon and used surgical face masks into advanced energy materials for batteries and supercapacitors.

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