Intrinsic catalytic Sites-Rich Co-doped SnO2 nanoparticles enabling enhanced conversion and capture of polysulfides

Abstract

The serious shuttle effect and sluggish reaction kinetics hinder the commercialization implementation of lithium-sulfur battery, despite its ultra-high theoretical energy density and low cost outrivaling the lithium-ion battery. Regulating the electronic structure of metal oxides at the atomic level could be an effective strategy to improve the intrinsic catalytic activity for polysulfides conversion. Herein, we proposed cobalt-doped stannic oxide which was uniformly grown on carbon nanotubes (Co-SnO2@CNT) as a multifunctional sulfur host. Evidenced by experimental characterizations and theoretical simulations, it is found that due to the appropriate doping amount, this host is endowed with abundant polar sites that exhibit robust polysulfides adsorption and confinement, fast Li-ion, and electron transfer, and rapid conversion reaction kinetics of sulfur species. As a result, the Co-SnO2@CNT host exhibits high sulfur loading (∼79.3 wt%), excellent rate capability (808 mAh g−1 at 2C), and superior long-term cycle stability (0.042% per cycle degeneration for 600 cycles at 1C). Excellent performances are also obtained at practical lean electrolyte conditions (E/S ratio ∼ 5 uL mg−1). This work verifies the feasibility of cobalt-doped SnO2 as catalyst and adsorbent for polysulfide species and reveals the internal mechanism of transition metal doped metal oxides at an atomic scale. In addition, a strategy was proposed that could overcome the intrinsic drawbacks of metal oxides and open up more feasible ways for high-performance lithium-sulfur batteries.