(1-10) Facet-Dominated TiB₂ Nanosheets with High Exposure of Dual-Atom-Sites for Enhanced Polysulfide Conversion in Li-S Batteries

Elaborate modulation of the highly active crystal facet emerges as an efficient strategy for enhancing the nanocrystalline catalytic activity. Herein, ultrathin TiB2 nanosheets with preferentially exposed (1-10) facets are developed as highly efficient catalyst with enriched bonding and electrocatalytic sites in Li-S batteries. Attributed to the highly equivalent exposure of Ti and B active sites on the (1-10) surface, the (1-10) facet-dominated TiB2 nanosheets maximize the binding effect via Ti and B dual-atom-sites adsorption through TiS and BS bonds. More importantly, experiments and theoretical calculations confirm the superb catalytic activity of (1-10)TiB2 in facilitating the polysulfide conversion and Li2S decomposition, thereby markedly suppressing the shuttling effect and improving the redox kinetics. Consequently, excellent electrochemical properties are achieved in Li-S batteries, which demonstrate a high discharge capacity of 1469 mAh g(-1) at 0.2 C and maintain high capacity reversibility at 1 C with a low capacity decay rate of 0.048% over 500 cycles. Even under a sulfur loading of 5 mg cm(-2), a prominent areal capacity of 4.86 mAh cm(-2) is still attained. It is proposed that the crystal surface engineering provides a new path for the structure optimization of sulfur catalysts in Li-S batteries.