Boosted Polysulfide Conversion by Co, Mn Bimetallic-Modulated Nitrogen–Carbon Material for Advanced Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries (LSBs) are regarded as one of the most promising future generation rechargeable battery energy storage devices due to their high theoretical specific capacity and energy density. However, the development of LSBs is largely influenced by the shuttle effect and slow kinetics of lithium polysulfides, which seriously hinder their commercial applications. Based on this, we propose a bimetallic modulating strategy to synthesize carbon tube embedded with Co and Mn bimetals anchored on a nitrogen-doped carbon nanosheet (Co/Mn-GC@N–C) function separator to catalytic polysulfide conversion and enhance the electrochemical performance. Co/Mn-GC@N–C possesses high electrical conductivity and large specific surface area, which can offer a lot of active sites for anchoring polysulfides, stimulating their redox reaction and quickening the electrode reaction kinetics. The comprehensive test results show that the cell with Co/Mn-GC@N–C exhibits a specific discharge capacity of 1215 mAh g–1 at 0.5C and a high Coulombic efficiency of 99.4% after 300 cycles; even the Co/Mn-GC@N–C cell with a high sulfur loading of 6.6 mg cm–2 shows a high area capacity of 5 mAh cm–2. Therefore, this bimetallic modulating strategy provides an option for the design of advanced high-performance lithium–sulfur battery separator materials.