Past exam of the MPhil in micro- and nanotechnology enterprise course of the University of Cambridge / 2020 / Paper 2 / Section B / 19 / iii / c

Yes: carbon nanotubes can store lithium and form a porous, conducting anode network. Their external surfaces, defects and intertube spaces provide possible storage sites. Open ends and suitable defects may make internal surfaces accessible; a closed pristine tube should not be credited with its full internal area.

Axial conduction and an entangled mechanical scaffold can support either active storage or a composite electrode. Limitations include tube–tube contact resistance, low packing density, catalyst residues and large-area solid electrolyte interphase formation. Opening or functionalizing tubes may improve ion access while increasing defects and irreversible reactions. Compare reversible capacity, first-cycle efficiency, retention and full-cell lithium inventory under matched loading and voltage-window conditions. A high first-cycle capacity alone is insufficient evidence of a superior anode.