Aqueous zinc-ion batteries are emerging as a credible alternative to lithium-ion for grid storage. Discuss the techno-economic case and the R&D challenges India is addressing.

Q. Aqueous zinc-ion batteries are emerging as a credible alternative to lithium-ion for grid storage. Discuss the techno-economic case and the R&D challenges India is addressing. (15 marks, 250-350 words)

Aqueous zinc-ion batteries (AZIBs) store energy by shuttling Zn²⁺ ions through a water-based electrolyte, replacing the flammable organic solvents of lithium-ion cells [1]. For a country targeting 500 GW non-fossil capacity and net-zero by 2070, they offer a safer, indigenously feasible route to stationary storage — though commercial viability still hinges on unresolved materials science.

The techno-economic case - Safety: the non-flammable, non-toxic aqueous electrolyte removes thermal-runaway risk, a decisive advantage for large stationary grid installations [1]. - Cost and abundance: zinc is cheap and widely available, unlike lithium, cobalt and nickel; aqueous assembly also avoids the dry-room manufacturing that raises lithium-ion capital costs [1][2]. - Strategic autonomy: it reduces exposure to critical-mineral value chains concentrated in a few countries, complementing the National Critical Mineral Mission and Atmanirbhar Bharat [2]. - Grid fit: high-cycle, non-mobile applications — firming solar and wind — suit zinc chemistry's strengths rather than its weaknesses in energy density [2].

R&D challenges India is addressing - Zinc dendrites and corrosion: uneven zinc deposition grows needle-like dendrites that short-circuit cells; scientists at INST Mohali (DST) developed an electrolyte additive that adsorbs on the zinc surface and steers uniform deposition [1]. - Hydrogen evolution: water reduction at the anode is a parasitic reaction causing electrolyte loss; the same interface engineering approach suppresses it without costly bulk-material redesign, making the fix scalable and affordable [1]. - Cycle life and cathodes: CeNS Bengaluru engineered a sulfur-vacancy 1T-MoS₂ cathode retaining 97.91% capacity after 500 cycles at 99.7% coulombic efficiency [2]. - Translation gap: laboratory cells must still scale to megawatt-hour modules with standards and manufacturing support.

AZIBs thus combine a favourable cost-safety profile with challenges that Indian laboratories are tackling through frugal, scalable chemistry rather than expensive redesign. Sustained ANRF funding, pilot deployments and extension of ACC-battery incentives to zinc chemistries can convert this research strength into energy security aligned with SDG-7.

(~330 words)

Sources: 1. Advancing electrolyte engineering for durable and affordable aqueous batteries — PIB, Ministry of Science & Technology — aqueous non-flammable electrolyte, dendrite/HER/corrosion failure modes, INST Mohali electrolyte additive and interface engineering 2. Scientists unlock new cathode material enabling Zinc-Ion Batteries for grid storage — Department of Science & Technology — zinc abundance and low cost, grid-storage application, CeNS 1T-MoS₂ cathode with 97.91% retention over 500 cycles and 99.7% coulombic efficiency