Hollow MnO2 spheres/porous reduced graphene oxide as a cathode host for high-performance lithium-sulfur batteries

Abstract

Rechargeable lithium-sulfur (Li-S) batteries, with a theoretical specific energy (2600 ​Wh kg-1) and theoretical specific capacity (1675 ​mAh g-1), are superior to current commercial lithium ion batteries. However, severe capacity fading due to volume breath and polysulfide dissolution greatly hinders the commercialization of Li-S battery. As an attempt to solve the problem, a hollow MnO2 spheres/porous reduced graphene oxide/S (MnO2/RGO/S) composite was synthesized by an one-step hydrothermal method, of which the hollow MnO2 spheres can effectively restrains the volume expansion/contraction of S8 and the dissolution of polysulfides during the charge-discharge processes. Furthermore, 3D RGO with high electronic conductivity can facilitates a fast electronic transfer. The initial specific capacity of the MnO2/RGO/S composite is 1202.0 ​mAh g-1 and remains 577.0 ​mAh g-1 with the coulombic efficiency of 93.2% at 0.2C after 200 cycles, and the capacity retention remains higher than 61.4% of the initial capacity after 100 cycles at 1C, indicating a synergistic effect of hollow MnO2 spheres and conductive 3D RGO.