In the context of electric vehicle batteries, consider the following elements : I. Cobalt II. Graphite III. Lithium IV. Nickel How many of the above usually make up battery cathodes?
- (a) Only one
- (b) Only two
- (c) Only three ✓ UPSC's answer
- (d) All the four
Why the answer is (c)
• A lithium-ion cell has a cathode (positive electrode), an anode (negative electrode), an electrolyte and a separator; lithium ions shuttle between the two electrodes.
• Cathodes are lithium metal oxides: lithium nickel-manganese-cobalt oxide (NMC), lithium nickel-cobalt-aluminium oxide (NCA), lithium cobalt oxide (LCO) or lithium iron phosphate (LFP). So lithium, nickel and cobalt (I, III, IV) are cathode elements.
• Graphite (II) is the standard anode material, into which lithium ions intercalate during charging; it is not part of the cathode.
• Hence three of the four elements make up battery cathodes, option (c).
• Cobalt's cost and ethical sourcing concerns are why makers are shifting to high-nickel and LFP chemistries.
Why the other options are wrong
- (a) Only one
- Lithium, nickel and cobalt are all cathode constituents.
- (b) Only two
- Three elements, not two, are used in cathodes.
- (d) All the four
- Graphite is the anode material, not a cathode constituent.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2025, held on 25 May 2025. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.