BharatNotes Note: This chapter was removed from the NCERT curriculum in the 2022 rationalization. Retained here as electrolysis, electroplating, and electrochemical concepts connect to battery technology, hydrogen production, and materials science — GS3 topics.
Why this chapter matters for UPSC: Electrochemistry is the science behind two of India's most important energy policy priorities: green hydrogen production (National Green Hydrogen Mission, 2023) and domestic battery manufacturing (ACC PLI scheme, ₹18,100 crore). Electrolysis is also the basis of the chlor-alkali industry and corrosion-prevention technologies that protect billions in infrastructure investment annually.
PART 1 — Quick Reference Tables
Conductors vs Insulators of Electricity
| Category | Examples | Why They Conduct (or Don't) |
|---|---|---|
| Good conductors | Silver, copper, gold, aluminium; acids, bases, salt solutions (electrolytes) | Free electrons (metals) or free ions (solutions) carry charge |
| Semiconductors | Silicon, germanium | Limited free electrons; conductivity tunable by doping |
| Poor conductors / Insulators | Distilled/pure water, rubber, plastic, glass, dry wood, ceramics, dry air | No free electrons or ions available |
Note on pure vs impure water: Pure (distilled) water is a poor conductor. It conducts electricity only when dissolved salts, acids, or bases are present — providing free ions. Rainwater conducts because it dissolves CO₂ (forming carbonic acid) and dust particles. This explains why wet hands and electrical appliances are dangerous.
Electroplating — Metals and Applications
| Metal Plated | Base Material | Purpose | Industry |
|---|---|---|---|
| Chromium | Steel (car parts, taps) | Corrosion resistance + aesthetic shine | Automotive, sanitary ware |
| Silver | Copper/brass cutlery, jewellery | Aesthetics, food safety | Tableware, ornaments |
| Gold | Jewellery base metals, electronic connectors | Aesthetics; corrosion resistance; conductivity | Electronics, jewellery |
| Nickel | Steel machine parts | Wear resistance, corrosion protection | Engineering |
| Tin | Steel (food cans) | Food-safe, non-toxic barrier against rusting | Food packaging |
| Zinc (galvanising) | Iron/steel structures, pipes, roofing | Sacrificial anode — zinc corrodes preferentially, protecting iron | Construction, infrastructure |
Battery Types Comparison
| Battery Type | Rechargeable | Energy Density | Key Uses |
|---|---|---|---|
| Zinc-carbon (dry cell) | No | Low | Torches, remote controls, wall clocks |
| Alkaline (AA/AAA) | No | Moderate | Consumer electronics; longer life than zinc-carbon |
| Lithium (non-rechargeable) | No | High | Smoke detectors, cameras, medical implants |
| Lead-acid | Yes | Low (but cheap, reliable) | Car starter batteries, UPS, inverters |
| Nickel-Metal Hydride (NiMH) | Yes | Moderate | Older hybrid vehicles (e.g., Toyota Prius Gen 1/2) |
| Lithium-ion (Li-ion) | Yes | High | Smartphones, laptops, EVs, grid storage |
| Lithium Iron Phosphate (LiFePO4) | Yes | Moderate-High | Stationary storage, EVs (safer chemistry, longer cycle life) |
| Solid-state (emerging) | Yes | Very high | Next-gen EVs (being commercialised 2025-30) |
| Sodium-ion (SIB, emerging) | Yes | Moderate (~half of Li-ion) | Stationary grid storage (BESS); EV use limited by lower energy density; no cobalt/lithium needed -- lower critical mineral dependency |
PART 2 — Detailed Notes
Chemical Effects of Electric Current (Electrolysis)
When an electric current passes through a conducting solution (electrolyte), it causes chemical decomposition — this process is called electrolysis. The container holds two electrodes connected to a battery:
- Anode (+): Connected to the positive terminal; attracts negative ions (anions)
- Cathode (-): Connected to the negative terminal; attracts positive ions (cations)
At the anode, oxidation occurs (electrons lost); at the cathode, reduction occurs (electrons gained). This is the foundation of all electrochemical processes — from electroplating to green hydrogen production.
Electrolyte: A substance that dissolves in water to produce ions, enabling the solution to conduct electricity. Strong electrolytes (fully dissociate): HCl, NaCl, NaOH, KOH. Weak electrolytes (partially dissociate): acetic acid, carbonic acid. Non-electrolytes: sugar, alcohol, urea — dissolve but produce no ions.
Electrolysis of Water — Green Hydrogen
Pure water (H₂O) can be split into hydrogen and oxygen gases by passing a direct electric current through it (with a small amount of electrolyte added to improve conductivity):
- At cathode (-): 2H⁺ + 2e⁻ → H₂ (hydrogen gas, colourless)
- At anode (+): 4OH⁻ → 2H₂O + O₂ + 4e⁻ (oxygen gas)
- Volume ratio: H₂ : O₂ = 2 : 1
When the electricity used for this electrolysis comes from renewable sources (solar, wind), the hydrogen produced is called green hydrogen — zero direct carbon emissions.
UPSC GS3 — National Green Hydrogen Mission (NGHM): Approved by Cabinet in January 2023. Key targets by 2030:
- 5 MMTPA (million metric tonnes per annum) of green hydrogen production
- 125 GW of additional renewable energy capacity to power electrolysers
- ~₹8 lakh crore in total investment (public + private)
- 1 lakh direct jobs created; significant reduction in fossil fuel import bill
Strategic Green Hydrogen Incentive Programme (SIGHT): Provides financial incentives for domestic electrolyser manufacturing and green hydrogen production under NGHM. [Additional] Status (May 2025): 19 companies allocated 8.62 lakh MTPA (metric tonnes per annum) of green hydrogen production capacity; 15 firms allocated 3,000 MW/year of electrolyser manufacturing capacity. No commercial-scale green hydrogen production yet in India; cost target is below USD 1/kg by 2030 (current production cost: ~USD 5–6/kg).
Applications of green hydrogen:
- Steel: Replace coking coal in blast furnaces (Direct Reduced Iron — DRI process) — India aims for green steel exports
- Fertilizers: Replace natural gas in ammonia (NH₃) synthesis (Haber-Bosch process) — India imports ~4 MMTPA of fertilizer feedstock currently
- Refining: Petroleum refineries use large quantities of hydrogen for desulphurisation
- Transport: Hydrogen fuel cell vehicles (FCEVs); IOCL and NTPC piloting hydrogen buses in India
- Long-duration energy storage: Hydrogen can be stored and converted back to electricity via fuel cells when solar/wind output is low
Green Hydrogen Hubs: Rajasthan and Gujarat identified as priority hub states due to high renewable energy potential and proximity to fertilizer/refinery industries.
Electrolysis of Brine — Chlor-Alkali Industry
Electrolysis of salt water (brine = NaCl + H₂O) produces three commercially vital products:
- Chlorine gas (Cl₂) at anode — used in water disinfection, PVC plastic, bleaching powder (CaOCl₂), pharmaceuticals
- Hydrogen gas (H₂) at cathode — used as fuel and chemical feedstock
- Sodium hydroxide / Caustic soda (NaOH) in solution — used in paper and pulp, soap, textiles, aluminium refining, water treatment
Why galvanising uses zinc, not gold: Zinc acts as a sacrificial anode — when the coating is scratched and both zinc and iron are exposed to moisture, zinc corrodes preferentially (more reactive than iron in the electrochemical series), protecting the underlying iron. Gold, being less reactive, would not provide this protection. The iron would still corrode if the gold coating were scratched.
Electroplating — Process and Industrial Importance
In electroplating:
- The object to be plated is the cathode (connected to negative terminal)
- The plating metal forms the anode (connected to positive terminal)
- The electrolyte is a solution of a salt of the plating metal
Metal ions from the anode dissolve into solution and are deposited as atoms onto the cathode surface — building up a thin, uniform layer.
Economic and infrastructure significance:
- Corrosion losses: Corrosion of metals (rusting of iron/steel) costs India an estimated 3–4% of GDP annually in infrastructure, industrial, and maintenance losses — electroplating and galvanising are primary prevention methods
- Tin-plated food cans: Tin is non-toxic and prevents iron from contaminating food — critical for the processed food supply chain
- Electronic contacts: Gold plating on connector pins prevents oxidation and ensures reliable electrical contact in computers, smartphones, and aerospace electronics
Battery Technology and India's Policy Push
UPSC GS3 — Advanced Chemistry Cell (ACC) PLI Scheme: The Production Linked Incentive (PLI) scheme for Advanced Chemistry Cell (ACC) batteries was approved in May 2021 with an outlay of ₹18,100 crore (approximately $2.2 billion). Objectives:
- Achieve 50 GWh of domestic battery manufacturing capacity
- Reduce India's dependence on imported batteries (currently ~95% from China and Japan)
- Support the EV ecosystem (Faster Adoption and Manufacturing of Electric Vehicles — FAME II scheme)
- Enable grid-scale Battery Energy Storage Systems (BESS) for renewable energy integration
Why domestic battery manufacturing matters:
- EV adoption: India targets 30% EV penetration by 2030; 80% of two-wheelers, 40% of buses, 30% of private cars
- Energy security: Lithium, cobalt, and nickel are critical minerals — India is exploring mining in Australia (Khanij Bidesh India Ltd — KABIL), Argentina, and domestic sources
- Grid stability: As solar and wind capacity grows, battery storage becomes essential to balance intermittent generation with demand
Rajasthan Battery Energy Storage System: SECI (Solar Energy Corporation of India) has tendered large-scale BESS projects in Rajasthan to support the state's massive renewable energy pipeline.
Lithium reserves in India: Significant lithium reserves were reported in Reasi district, Jammu & Kashmir in 2023 (estimated 5.9 million tonnes — one of the world's largest deposits) — under exploration by the Geological Survey of India (GSI). If confirmed and mined, this could transform India's battery supply chain.
UPSC GS3 — EV Ecosystem and Battery Chemistry: Lithium-ion batteries dominate current EVs due to high energy density (~250 Wh/kg) and falling costs (from ~$1,100/kWh in 2010 to $115/kWh in 2024 and $108/kWh in 2025 — BloombergNEF annual price survey; EV packs specifically fell below $100/kWh). Key components:
- Cathode: Lithium-based oxide (LiCoO₂, LiFePO₄, NMC — nickel-manganese-cobalt)
- Anode: Graphite (current); silicon-graphite (emerging, higher capacity)
- Electrolyte: Liquid lithium salt solution (flammable — fire risk; hence thermal management systems in EVs)
Solid-state batteries (next generation): Replace liquid electrolyte with solid ceramic/polymer — safer, higher energy density, faster charging. Toyota, Samsung, and Indian startups (Log9 Materials) are working on commercialisation by 2027–2030.
Thermal runaway: A critical safety concern in Li-ion batteries — uncontrolled exothermic reactions if punctured, overcharged, or exposed to high temperatures. Several EV fires in India (2021–2022) led to BIS standards for EV battery safety (AIS-038/AIS-156).
[Additional] 13a. India's Critical Minerals List and National Critical Minerals Mission
The chapter discusses lithium reserves in Reasi (J&K) and KABIL (overseas mineral acquisition) in isolation, but misses the policy framework that connects them: India's formal critical minerals list and the dedicated mission to secure their supply.
[Additional] Critical Minerals Policy -- GS3 (Resources / Energy Security / Industrial Policy):
India's 30 Critical Minerals (Ministry of Mines, June 2023): Released by the "Committee on Identification of Critical Minerals" -- minerals where supply disruption would have serious economic or national security consequences. The list of 30:
Antimony, Beryllium, Bismuth, Cadmium, Cobalt, Copper, Gallium, Germanium, Graphite, Hafnium, Indium, Lithium, Molybdenum, Niobium, Nickel, PGE (Platinum Group Elements), Phosphorous, Potash, REE (Rare Earth Elements), Rhenium, Selenium, Silicon, Strontium, Tantalum, Tellurium, Tin, Titanium, Tungsten, Vanadium, Zircon.
Why these minerals matter for batteries:
- Lithium: Cathode and electrolyte; EV batteries and grid storage
- Cobalt: Cathode (NMC/NCA chemistry); price volatile; 70% from DRC (Democratic Republic of Congo)
- Nickel: Cathode (NMC chemistry); high energy density applications
- Graphite: Anode; 80% produced in China -- major supply concentration risk
- REE: Permanent magnets in EV motors (neodymium, dysprosium); wind turbine generators
Legislative framework:
- Mines and Minerals (Development and Regulation) Amendment Act, 2023 (MMDR 2023): Empowered the Central Government to auction blocks for 24 critical and strategic minerals (previously these were reserved for government entities only); opened to private sector
- India found: Lithium in Reasi (J&K, 5.9 MT), Cobalt in Jammu, REE in Andhra Pradesh (Kurnool); geological survey ongoing
National Critical Minerals Mission (NCMM, January 2025):
- Launched as a dedicated 7-year mission (2024-25 to 2030-31)
- Outlay: Rs 16,300 crore (budgetary) + PSU investment target Rs 18,000 crore
- Objectives: Domestic exploration and mining; overseas acquisitions via KABIL; recycling ecosystem; research and development in extraction technology
- KABIL (Khanij Bidesh India Ltd): Joint venture of NALCO, HCL, and MECL; secures critical mineral assets abroad; MoUs with Argentina (lithium), Australia (lithium, cobalt), USA
UPSC angle: India imports ~95% of critical minerals for battery manufacturing. NCMM + MMDR 2023 + KABIL form a three-pronged security architecture. This is a high-value GS3 synthesis question combining resources, industrial policy, and strategic competition with China (which dominates processing of most critical minerals).
[Additional] 13b. Sodium-Ion Batteries — India's Strategic Alternative to Lithium
The chapter covers Li-ion, LiFePO4, and solid-state batteries but misses sodium-ion (SIB) -- an emerging battery chemistry that directly reduces India's critical mineral dependency and is now commercially available in India.
[Additional] Sodium-Ion Batteries (SIBs) -- GS3 (Energy Storage / Technology):
How SIBs work: Sodium-ion batteries operate on the same electrochemical principle as Li-ion batteries -- ions move between anode and cathode through an electrolyte. The key difference: sodium (Na) ions instead of lithium (Li) ions. Sodium is far more abundant and evenly distributed globally -- common salt (NaCl) is the primary source.
Why SIBs matter for India specifically:
- India is the 3rd largest salt producer globally (~26.5 million tonnes/year, ~10% of global production) -- raw material security is unmatched
- SIBs require no lithium, no cobalt -- the two minerals most concentrated in geopolitically sensitive locations (cobalt in DRC; lithium in Chile/Argentina/Australia); removes exposure to critical mineral supply chain risks
- Cost projection: 15-20% cheaper than Li-ion by 2030 (BloombergNEF/EY India estimates)
Trade-off -- lower energy density:
- SIB energy density: ~100-150 Wh/kg (roughly half of Li-ion's ~250 Wh/kg for similar chemistries)
- This limits SIB suitability for EVs (more battery weight needed for same range) but is acceptable for stationary grid storage where weight is not a constraint
Best application: Grid-scale Battery Energy Storage Systems (BESS)
- India's grid BESS target: 41.7 GW / 208 GWh by 2030 (Central Electricity Authority)
- SIBs are strong candidates for this market -- bulk stationary storage prioritises cost over weight
India's SIB ecosystem (2025-26):
- Naxion Energy: Launched India's first commercial SIB energy storage systems (3.5 kW / 5 kW / 10 kW residential and C&I units) in December 2025
- Active companies: Sodion Energy, Indi Energy, KPIT Technologies, Cygni Energy
- JNCASR Bengaluru (DST-funded): Developed a SIB anode material enabling 80% charge in 6 minutes with 3,000+ cycle durability -- among the fastest-charging SIBs globally (2024 research)
- China context: China has already commercialised SIBs (CATL launched its first SIB in 2023); India is 1-2 years behind but has the raw material advantage
Exam Strategy
Prelims traps:
- Pure/distilled water is a poor conductor — it conducts only when dissolved salts/ions are present; do not confuse with the common notion that "water conducts electricity"
- In electroplating, the object to be plated is the cathode (negative), not the anode — a frequent reversal in MCQ options
- Galvanising = coating iron with zinc (not tin, not chromium); tin plating is used for food cans
- Green hydrogen = produced by electrolysis using renewable electricity only; "blue hydrogen" = from natural gas with carbon capture; "grey hydrogen" = from natural gas without capture
- The NGHM target is 5 MMTPA by 2030 — not 5 GW (GW is a power unit, not hydrogen quantity)
- ACC PLI outlay is ₹18,100 crore and targets 50 GWh capacity — both numbers recur in Prelims
- Lithium reserves found in J&K (Reasi) in 2023 — not in Rajasthan or Jharkhand
Mains angles:
- Green hydrogen as a decarbonisation strategy for hard-to-abate sectors (steel, fertilizers, shipping)
- Critical minerals for battery supply chain — India's import dependence and diversification strategy (KABIL, FTA with Australia)
- EV adoption challenges — charging infrastructure, battery cost, grid readiness
Practice Questions
Prelims:
With reference to 'Green Hydrogen', consider the following statements:
- It is produced by the electrolysis of water using renewable energy
- India's National Green Hydrogen Mission targets 5 MMTPA of green hydrogen production by 2030
- Green hydrogen emits CO₂ at the point of use in fuel cells
Which of the above is/are correct?
(a) 1 only
(b) 3 only
(c) 1 and 2 only
(d) 1, 2, and 3
- It is produced by the electrolysis of water using renewable energy
The PLI scheme for Advanced Chemistry Cell (ACC) batteries in India primarily aims to:
(a) Reduce the retail price of consumer electronics using imported batteries
(b) Build domestic battery manufacturing capacity of 50 GWh to support the EV ecosystem
(c) Develop nuclear battery technology for defence applications
(d) Replace diesel generators in rural areas with battery-powered microgridsWhich of the following correctly describes the process of galvanising?
(a) Coating iron with a layer of tin to prevent corrosion
(b) Coating iron with a layer of chromium for aesthetic shine
(c) Coating iron with a layer of zinc that acts as a sacrificial anode
(d) Coating copper pipes with a layer of nickel for wear resistance
Mains:
Examine the significance of the National Green Hydrogen Mission for India's energy security and climate commitments. What are the technological and economic challenges in achieving the 2030 targets? (CSE Mains 2023, GS Paper 3, 15 marks)
India's dependence on imported batteries and critical minerals poses strategic vulnerabilities for its EV and energy storage ambitions. Discuss the policy measures India has taken to address this challenge. (CSE Mains 2022, GS Paper 3, 15 marks)
