Slew of technologies developed to enable electrically rechargeable Zinc-air batteries

Key Highlights:

• Scientists from SASTRA Deemed University, supported by the Department of Science and Technology (DST), developed new technologies for electrically rechargeable Zinc-air batteries.
• A novel nanofluid electrolyte, stable for over three months, enhances cathode efficiency and addresses zinc corrosion and hydrogen evolution.
• The technology, protected by Indian patent IN570691, offers potential for safer, cheaper, and greener batteries for grid-scale storage and electric mobility.
• Earth-abundant α-MnO2 (copper-doped) was identified as a high-performing bifunctional catalyst, outperforming platinum and ruthenium-based standards.
• Waste-derived materials, including spent activated carbon from water filters and surgical masks, are upcycled for catalysts and electrodes.

Detailed Insights:

• The innovation aims to resolve issues like unwanted hydrogen gas evolution at the zinc anode and sluggish oxygen reactions at the air-cathode.
• The nanofluid electrolyte incorporates inexpensive silica and zinc oxide nanoparticles to simultaneously suppress hydrogen reaction and inhibit corrosion.
• Copper doping at a low 2 wt% significantly boosts the performance of the α-MnO2 catalyst beyond commercial benchmarks.
• Spent activated carbon from household water filters was hydrothermally converted into MnO2/C nanocomposites, a process also patented (Application No. 202441032753).
• Post-pandemic surgical face masks were chemically upcycled into activated carbon with a record-high surface area, rivalling platinum in oxygen reduction activity.
• The developed approaches have broader applicability to other aqueous battery systems and various waste carbon sources beyond Zinc-air batteries.

Scientific/Technical Concepts Involved:

• Zinc-air batteries (ZABs): Aqueous batteries known for high theoretical energy density, low cost, and water-based chemistry, using zinc as anode and air as cathode.
• Nanofluid electrolyte: An electrolyte containing dispersed nanoparticles, designed to enhance properties like stability and reaction kinetics.
• α-MnO2: A specific crystalline form of manganese dioxide, identified as an efficient bifunctional electrocatalyst due to its open tunnel-like architecture.
• Bifunctional catalysts: Materials capable of catalyzing two different electrochemical reactions, such as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).