Synthetic or natural graphite (and some silicon) that stores lithium on charge, plus the conductive carbon added to both electrodes.
Needle coke or natural graphite is milled, shaped into spheres, coated and graphitised at ~3,000°C to make anode powder, which is coated onto copper foil. Conductive carbons such as acetylene black are mixed into both electrode slurries to carry current.
China processes the vast majority of the world's battery graphite and put graphite under export licensing in 2023. India's graphite-electrode makers already run graphitisation furnaces, which gives them a head start. Epsilon's 2,000 t plant (enough for ~2 GWh) is the only sizeable one running; HEG's TACC is building 20,000 t.
Energy-intensive and capex-heavy, but a natural extension for Indian graphite-electrode makers. Margins depend on power cost and needle-coke supply; customer qualification is the gate.