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Sodium-ion batteries are emerging as a strategic alternative to lithium-ion technology, offering India a safer, resource-secure and cost-effective pathway for energy storage and electric mobility.

Context

Batteries are a critical backbone of modern infrastructure-supporting electric vehicles (EVs), renewable energy integration, and grid stability. India’s current dependence on lithium-ion batteries exposes it to import dependence, supply-chain vulnerabilities, and geopolitical risks, as key minerals like lithium, cobalt, nickel and graphite are scarce domestically and globally concentrated. This has prompted India to re-evaluate its battery strategy, with sodium-ion batteries (SiBs) gaining attention.

What are Sodium-ion Batteries?

• Sodium-ion batteries (SiBs) are rechargeable batteries that use sodium ions (Na?) as charge carriers instead of lithium ions.
• They belong to the same “rocking-chair” battery family as lithium-ion cells.

Working Principle

• Charging: Sodium ions move from cathode to anode through the electrolyte.
• Discharging: Sodium ions migrate back to the cathode, releasing electrical energy.
• Current collectors: Aluminium is used on both electrodes (unlike lithium-ion, which uses copper on the anode).

Key Features and Advantages

1. Resource Abundance and Security

• Sodium is abundantly available from sea salt and soda ash.
• Reduces reliance on imported critical minerals.
• Enhances energy security and strategic autonomy.

2. Safety Profile

• Intrinsically safer than lithium-ion batteries.
• Lower thermal runaway risk and lower peak temperatures during failure.
• Can be stored and transported at 0% state of charge, unlike lithium-ion batteries (classified as dangerous goods).

3. Cost Potential

• Use of aluminium instead of copper lowers material cost.
• Simplified logistics reduce transportation and insurance costs.
• Cost projections indicate SiBs could become cheaper than lithium-ion batteries by the mid-2030s.

4. Manufacturing Compatibility

• Can be produced using existing lithium-ion manufacturing lines with minor modifications.
• Aligns well with PLI-incentivised battery infrastructure in India.

Energy Density Comparison

• Historically, SiBs had lower energy density due to heavier sodium ions.
• Recent advances using layered transition-metal oxide cathodes have brought SiBs close to Lithium Iron Phosphate (LFP) batteries.
• Suitable for applications where ultra-high energy density is not critical.

Significance for India

• Reduced Import Dependence: Insulates India from global supply shocks and price volatility.
• Mass-market suitability: Ideal for electric two-wheelers, three-wheelers, buses, and grid storage.
• Grid-scale storage: Well-suited for renewable energy integration.
• Geopolitical resilience: Less exposure to mineral supply chains dominated by a few countries.

India’s Policy and Institutional Initiatives

• PLI Scheme for Advanced Chemistry Cell (ACC):
  • Target: 50 GWh domestic capacity.
  • 40 GWh awarded, but only ~1 GWh commissioned so far, indicating slow progress.
• National Critical Minerals Mission: Focus on exploration, mining, processing, recycling and overseas sourcing.
• Overseas mineral acquisition via Khanij Bidesh India Limited.
• Battery Waste Management Rules, 2022: Extended Producer Responsibility (EPR) for recycling and refurbishment.

Challenges in Scaling Sodium-ion Batteries

• Lower energy density limits use in long-range and premium EVs.
• Weight penalty compared to lithium-ion batteries.
• Moisture sensitivity requires deeper vacuum drying and tighter process control.
• Underdeveloped supply chain for sodium-specific cathodes, anodes and electrolytes.
• Policy gaps: Incentives and safety standards remain lithium-centric.
• Low market confidence due to limited real-world deployments.

Measures Suggested to Scale SiBs in India

• Farm-to-Battery Strategy:
  • Use agricultural waste to produce hard carbon anodes.
  • Convert stubble-burning problem into a resource solution.
• Desert-centric Manufacturing Clusters: Locate plants in low-humidity regions (Rajasthan, Kutch) to reduce energy costs.
• Standardisation for Early Markets: Focus on buses and three-wheelers where size and weight constraints are lower.
• Hybrid Battery Packs: Combine sodium-ion (cost efficiency) with lithium-ion (performance).
• Chemical Upgradation Support: Upgrade industrial soda ash to battery-grade sodium carbonate domestically.