How a battery works, and the chemistries in play

Prelims and MainsCurrent affairs on this: Storage, batteries and electric mobility

A battery stores energy as chemistry and releases it as current. Every cell has two electrodes in an electrolyte, separated by a membrane that passes ions but not electrons: when the cell discharges, the anode gives up electrons that flow through the outside circuit to the cathode, while ions move through the electrolyte to balance the charge; charging drives both back. In a lithium ion cell the ions are lithium, the anode is graphite and the cathode a lithium metal oxide, shuttling between them, which is why it recharges thousands of times. What a chemistry is good for is set by four numbers: energy density (watt hours per kilogram, how far a vehicle goes), power density (how fast it can deliver), cycle life (how many charges before it fades) and cost per kilowatt hour. The cathode decides most of this, and its metals are the critical minerals in the news.

Battery chemistries compared

	NMC lithium ion	LFP lithium ion	Sodium ion	Solid state	Lead acid
Energy density	high	medium	lower	highest, in development	low
Safety	thermal runaway risk	high	high	high	high
Cycle life	medium	long	long	long, unproven	short
Critical minerals	lithium, nickel, cobalt	lithium, iron, phosphate	sodium	lithium	lead
Cost	high	lower	lowest potential	high	lowest
Used for	cars, phones	buses, three wheelers, grid	grid, cheap vehicles	future cars	backup, starting

The cathode sets the trade off between range, safety and cost; India's fleet and grid are moving to LFP because it needs no cobalt.Source: Standard electrochemistry; IEA Global EV Outlook

Lithium ion chemistries: nickel manganese cobalt (NMC) for high energy density, used in cars and phones; lithium iron phosphate (LFP) for safety, long life and no cobalt, now the choice for buses, three wheelers and grid storage; lithium cobalt oxide in older electronics.
Beyond lithium ion: sodium ion (abundant sodium, lower energy density, suited to stationary storage), solid state (a solid electrolyte, safer and denser, still scaling up), flow batteries (vanadium, energy stored in tanks of liquid, for grid scale), and lead acid, still the cheapest for backup.
Grid storage is a different job from a vehicle: the grid wants cycle life and cost, not weight, which is why LFP and pumped storage dominate and why battery energy storage systems are measured in megawatt hours.
India's instruments: the Advanced Chemistry Cell (ACC) production linked incentive (PLI) scheme of 2021 (Rs 18,100 crore for 50 GWh of cell manufacturing), Faster Adoption and Manufacturing of Electric Vehicles (FAME) II (2019 to 2024) succeeded by PM E DRIVE (October 2024, Rs 10,900 crore, to March 2026), viability gap funding for grid batteries, begun with 4,000 MWh in 2023 and since expanded (see Battery storage), and the Battery Waste Management Rules, 2022 with recycled content mandates.
Raw material: India has an inferred lithium resource of 5.9 million tonnes at Reasi in Jammu and Kashmir (2023), no producing mine, and imports its cells; recycling and the National Critical Mineral Mission are the supply answer for now.

Mains: Storage is the missing half of India's renewable build: solar peaks at noon and demand at night, and until grid batteries and pumped storage close that gap, every gigawatt of solar needs a coal plant behind it.

UPSC has asked

Prelims 2025: which elements make up the cathode of an electric vehicle battery

Further reading: Making India Aatmanirbhar in advanced battery storage (NITI Aayog)