Nanoscale α-MnS crystallites grown on N-S co-doped rGO as a long-life and high-capacity anode material of Li-ion batteries

The rock-salt structural manganous sulfide (alpha-MnS) is of higher lithium storage capacity. To improve the cyclability of alpha-MnS anode in lithium-ion batteries, we prepared a composite of alpha-MnS nanocrystallites grown on nitrogen and sulfur co-doped reduced graphene oxide (rGO) honeycomb framework. N and S atoms have been co-doped into rGO along with the growth of the alpha-MnS nanocystallites by a one-pot hydrothermal synthesis using thiourea as dopant and reactant. The typical alpha-MnS/Nsingle bondS co-doped rGO (NSG) composite electrode exhibits a reversible capacity as high as 763.5 mAh g(-1) after 100 cycles at 100 mA g(-1), and a reversible capacity of 576.7 mAh g(-1) even after 2000 cycles at 1000 mA g(-1). More importantly, the alpha-MnS/NSG composite electrodes show superior cycle performance at asymmetric discharge/charge current densities. The excellent electrochemical performance can be attributed to that the alpha-MnS nanocrystallites shorten lithium ion transmission distance, N-S co-doping improves the electronic conductivity of rGO, and the formation of chemical bonds combination between alpha-MnS and NSG enhances the electrode structural stability and the electron transport. In addition, more stable architecture of NSG-supported ultrafine alpha-MnS particles is formed upon cycling, which greatly enhances the electrical contact and further improves the electrochemical performance. (C) 2017 Elsevier B.V. All rights reserved.