Three-Dimensional Interconnected Network Architecture with Homogeneously Dispersed Carbon Nanotubes and Layered MoS2 as a Highly Efficient Cathode Catalyst for Lithium-Oxygen Battery.

Abstract

The structure and catalytic activity of the oxygen electrode determine the overall electrochemical performance of lithium-oxygen (Li-O2) batteries. Here, a three-dimensional (3D) porous interconnected network structure combined with ultrathin MoS2 nanosheets with homogeneously dispersed CNTs (MoS2/CNTs) was synthesized via a one-step hydrothermal reaction. The 3D interconnected architecture can efficiently promote the diffusion of O2 and Li ions as well as impregnation of electrolyte and provide more abundant storage space for the accommodation of discharge products, while the incorporation of uniformly dispersed CNTs improves the electronic conductivity and maintains the integrity of the cathode structure. Therefore, the Li-O2 battery based on MoS2/CNTs achieves improved performance with the low overpotentials (discharge/charge overpotentials of approximately 0.29 and 1.05 V), a high discharge specific capacity of 6904 mA h g-1 at a rate of 200 mA g-1, and excellent cycling stability (132 cycles). Experimental studies reveal that the improved electrochemical performance can be ascribed to the synergistic advantages of electronic conductive CNTs and excellent catalytic activity of the MoS2 nanosheets. Moreover, the unique 3D interconnected network structure can effectively facilitate fast charge transfer kinetics and a facile mass transport pathway. These encouraging performances demonstrate the metal sulfide catalyst as a promising catalytic material of oxygen electrodes for Li-O2 batteries.