A high-rate lithium–sulfur battery assisted by nitrogen-enriched mesoporous carbons decorated with ultrafine La2O3 nanoparticles

Abstract

Nitrogen-enriched mesoporous carbons (NMCs) were decorated with ultrafine La₂O₃ nanoparticles via a simple wet impregnation method. The resulting composites with well developed mesoporous structures, high nitrogen content and uniform dispersions of La₂O₃ nanoparticles served as scaffolds to house sulfur for high rate lithium–sulfur batteries. Apart from their on-site trapping of polysulfides, the La₂O₃ nanoparticles decorated on the mesoporous carbon framework were also found to have a strong catalytic effect on sulfur reduction, offering high discharge voltages and fast electrochemical reaction kinetics. Combining the multiple effects of the well developed mesopores, nitrogen doping and La₂O₃ nanoparticles, the resulting ternary NMC/La₂O₃/S nanocomposites can deliver an initial capacity of 1043 mA h g⁻¹ at 1 C, which remains at 799 mA h g⁻¹ after 100 cycles. Moreover, they still maintain ultra-high rate capacities of 579 and 475 mA h g⁻¹ at 3 C and 5 C, respectively, after 100 cycles. These encouraging results suggest that other metal oxides with suitable adsorption and catalytic abilities can be widely applied to decorate carbon frameworks for use in high rate lithium–sulfur systems.