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

Abstract

AbstractElaborate 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 Ti─S and B─S 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.