The Alkynyl π\nBond\nof sp‑C Enhanced Rapid, Reversible Li–C Coupling to\nAccelerate Reaction Kinetics of Lithium Ions

Graphdiyne (GDY) is a promising anode for rechargeable\nbatteries\nwith high capacity, outstanding cyclic stability, and low diffusion\nenergy. The unique structure of GDY endows distinctive mechanisms\nfor metal-ion storage, and it is of great significance to further\nvisualize the complex reaction kinetics of the redox process. Here,\nwe systematically tracked the reaction kinetics and provided mechanistic\ninsights into the lithium ions in the GDY to reveal the feature of\nthe cation-π effect. It has been demonstrated that, unlike only\none π bond in sp<sup>2</sup>-C, π electrons provided by\none of the two alkynyl π bonds in sp-C can achieve proper interaction\nand speedy capture of lithium ions; thus, reversible Li–C coupling\ncan be formed between electron-rich sp-C and lithium ions. In addition\nto interlayer intercalation in sp<sup>2</sup>-C regions, nanopores\nfilling triangular-like cavities composed of highly conjugated sp-C\ncontribute to the major capacity in flat voltage plateau regions.\nTherefore, a capture/pores filling-intercalation hybrid mechanism\ncan be found in GDY. The coexistence of sp and sp<sup>2</sup> carbon\nenables GDY electrodes with rapid Li<sup>+</sup> diffusion, high capacity\nof over 1435 mAh g<sup>–1</sup>, extraordinary rate capability,\nand cyclic stability for more than 10000 cycles at 10A g<sup>–1</sup>. These results provide guidance for developing advanced carbon electrodes\nwith optimized reaction kinetics for rechargeable batteries.