High-performance lithium−sulfur batteries fabricated from a three-dimensional porous reduced graphene oxide/La2O3 microboards/sulfur aerogel

Abstract

Rechargeable lithium–sulfur (Li–S) batteries are a promising energy storage device because of their high energy density, but the poor electrical conductivity of the sulfur cathode and the polysulfide-shuttle effect still hinder the application of Li-S batteries. Herein, with the aid of compositional and structural design and the use of a controllable one-pot hydrothermal method, a three-dimensional (3D) porous reduced graphene oxide@La2O3@S (r-GO@La2O3@S) composite is fabricated for use as the cathode material of Li–S batteries. In this 3D porous structure, the effective adsorption ability of the La2O3 microboards toward the polysulfides, based on strong chemical binding, and the conductivity of r-GO provide pathways to facilitate electron and ion transport while being able to accommodate the volume expansion/contraction of the sulfur cathode during the discharge-recharge processes. The r-GO@La2O3@S cathode delivers an initial reversible capacity of 1227.4 mAh g−1 and remains 668.3 mAh g−1 at 0.2 C after 200 cycles. At a higher current of 1 C, the capacity retention remains higher than 73% of the initial capacity after 100 cycles, indicating the excellent electrochemical properties of the cathode. The exceptional performance is attributed to the synergistic effects of the conductive r-GO and La2O3 microboards with the active sulfur.