Synergistic constraint and conversion of lithium polysulfide using a 3D hollow carbon interlayer in ultrahigh sulfur content Li-S batteries

Abstract

Low sulfur content and inevitable polysulfide shuttle effect have always been the critical obstacle of the practical application of high-energy–density lithium sulfur batteries. Herein, a waste passiflora edulis peel derived in-situ N-doping porous carbon (PINPC) combined with three-dimensional hollow carbon cloth interlayer (3DHCI) was designed and constructed by facile simultaneous activation/carbonization. The abundant porous structure and nitrogen heteroatom doping of the PINPC not only significantly confine the soluble polysulfides through the physical and chemical adsorption, but also the high conductivity of the 3DHCI effectively accelerate the conversion reaction of polysulfides encapsulated in the unique hollow carbon skeletons. Owing to the synergetic enhancement of the PINPC and 3DHCI, the sulfur contents of the corresponding sulfur cathode composites are easily regulated from 70 wt% to 95 wt%, whilst exhibiting excellent electrochemical performances. The PINPC/S with a sulfur content of 70 wt% and 3DHCI interlayer obtains a high initial discharge capacity of 1032 mAh·g−1 and then retains 954 mAh·g−1 at 0.2 C after 200 cycles. At 2 C, a durable cycle life with capacity retention of 86% can be achieved up to 500 cycles. Even with an ultrahigh sulfur content of 95 wt%, the relatively high initial discharge capacity of 692 mAh·g−1 and capacity retention of 96 % are also achieved at 0.2 C after 200 cycles. This work offers a potential design for high-performance lithium sulfur batteries simultaneously with a high sulfur content.