What happened

SASTRA Deemed University (Thanjavur) developed a nanofluid electrolyte for electrically rechargeable zinc–air batteries. The nanofluid electrolyte is reported to be made by dispersing small amounts of inexpensive silica and zinc oxide nanoparticles into a standard electrolyte. The reported outcome includes improved cathode oxygen-reaction performance alongside suppression of parasitic hydrogen-related reactions and zinc corrosion. The Department of Science and Technology (DST) supported the work through its Nano and Advanced Materials Division.

Background and earlier position

Electrically rechargeable zinc–air batteries face two electrode bottlenecks: parasitic hydrogen gas evolution at the zinc anode wastes charge and corrodes the metal, and oxygen reduction/oxygen evolution at the air cathode can be sluggish and may require expensive noble-metal catalysts. Corrosion inhibitors can also hinder oxygen-reaction kinetics, creating a materials-design trade-off.

What changed now

SASTRA reports that dispersing silica and zinc oxide nanoparticles in the electrolyte suppresses parasitic hydrogen evolution, inhibits zinc corrosion, and enhances cathode oxygen reaction performance. For oxygen catalysis, SASTRA reports earth-abundant bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), with α-MnO2 highlighted for its reported open tunnel-like architecture and copper doping at low loading (2 wt%) for improved performance versus Pt- and Ru-based standards. SASTRA also reports waste-derived carbon routes, including hydrothermal conversion of spent activated carbon from household water filters into MnO2/C nanocomposites, and chemical upcycling of post-pandemic surgical face masks into activated carbon with oxygen reduction activity reported to rival platinum. SASTRA reports intellectual property coverage including a granted Indian patent for the electrolyte technology (IN570691) and patent application coverage for the waste-derived carbon approach (Application No. 202441032753).

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