Insights into the sandwich-like ultrathin Ni-doped MoS2/rGO hybrid as effective sulfur hosts with excellent adsorption and electrocatalysis effects for lithium-sulfur batteries

Abstract

Dual redox mediator based on a novel ultrathin sandwich-type Ni-doped MoS 2 /rGO with rich MoS 2 -defect accelerate the electrochemical kinetics for high performance lithium-sulfur batteries. • The sandwich-type Ni-MoS 2 /rGO is developed as sulfur host via hydrothermal method. • The rich MoS 2 -defect plays key role in adsorption and redox kinetics of LiPSs. • Adsorption-electrocatalysis synergy enhances the electrochemical properties. • The S@Ni-MoS 2 /rGO cathode has high specific capacity and long cycle stability. The design of sulfur hosts with high conductivity, large specific surface area, strong adsorption and electrocatalytic ability is crucial to advance high performance lithium-sulfur batteries. Herein, a novel ultrathin sandwich-type Ni-doped MoS 2 /reduced graphene oxide (denote as Ni-doped MoS 2 /rGO) hybrid is developed as a sulfur host through a simple one-step hydrothermal route. The two-dimensional layered structure Ni-doped MoS 2 /rGO hybrid with heterostructure and heteroatom architecture defects not only plays a key role in adsorption of lithium polysulfide but also catalyzes on redox kinetics of sulfur and polysulfide species. Meanwhile, it can contribute to the large specific surface area for Li 2 S/S 8 deposition, fast Li-ion and electron transportation, thus enhancing the electrocatalytic properties, as confirmed firstly by cyclic voltammetry (CV) results. Due to the adsorption-catalytic synergistic effect, the Ni-doped MoS 2 /rGO cathode exhibits high specific capacity (1343.6 mA h g −1 at 0.2 C, 921.6 mA h g −1 at 1 C), high coulombic efficiency and an outstanding cycle stability (with the low attenuation rate of 0.077% per cycle over 140 cycles at 0.5 C and 0.11% per cycle over 400 cycles at 1 C, respectively). This work proposes some inspiration for exploring the construction of advanced lithium-sulfur batteries through the rational design defects of atomic structure and electronic states of MoS 2 as sulfur host.