Mn3(PO4)2/rGO as dual-function polysulfide inhibitor through oxygen deficiencies and polar sites for lithium sulfur batteries

Abstract

The development of Lithium surfur batteries (LSBs) are beset with tenacious issues including the insulating property of the sulfur element and the dissolution of the reaction intermediate products into electrolyte, which result in low S utilization and poor battery cycling performances. In this work, we exploit metal phosphate as the S host for suppressing the sulfur dissolving and accelerating the polysulfide conversion, and firstly construct the S@Mn3(PO4)2/rGO composites through an in-situ solution growth followed by S impregnation route. More importantly, the geometric compatibility of Mn3(PO4)2 nanoflakes and rGO nanosheet endows such S@Mn3(PO4)2/rGO composites with high electrical conductivity and excellent mechanical durability. As evidenced by the electrochemical performances in LSB, the S@Mn3(PO4)2/rGO cathode shows discharge capacities of 863 mA g−1 at 0.2 C after 100 cycles and 658 mAh g−1 after 470 cycles at 1.0 C with high Coulumbic efficiency of nearly 100%; more impressively, it delivers a high capacity of 407 mAh g−1 ever at 5.0 C rate during rate capability testing. Our research on the construction of S@Mn3(PO4)2/rGO composites provides new insight and opportunitie to develop advanced LSBs with highly efficient inhibitors for trapping polysulfides and accelerating their conversion.