Ultrahigh sulfur content up to 93 wt% encapsulated in multilayer nanoshell of V/V2O5 composite to suppress shuttle effect of lithium-sulfur battery with high-performance

Renowned for its high theoretical specific energy, lithium-sulfur (Li-S) batteries still suffer from the shuttle effect of polysulfides, the insulating nature of sulfur and severe volumetric variations, especially for cathodes with high sulfur contents. Herein, S microsphere encapsulated within a thickness-tunable multilayered thin V/V2O5 nanoshell (S@V/V2O5) was explored as a high-sulfur-content cathode (up to 93 wt%) for Li-S batteries. With a polar V2O5 moiety the nanoshell could physically block and chemically adsorb polysulfides, while the metallic V could assure efficient electron transfer; this multilayered and porous nanoshell could also buffer the volumetric variations of the sulfur core and facilitate Li+ transportation. Such S@V/V2O5 electrode with a 87 wt% sulfur content delivers high specific capacity (1403 mAh g(-1)) and remarkable areal initial capacity (4.4 mAh cm(-2)) at 0.2 C, excellent cycling stability (819 mAh g(-1) at 0.5 C after 300 cycles), superior high-rate capacity (804 mAh g(-1) at 4 C), low self-discharge (759 mAh g(-1) after resting 50 days) and a high coulombic efficiency above 90% in a LiNO3 free electrolyte. A current collector-free S@V/V(2)O(5 )cathode with sulfur content of 93 wt% is also achieved, which yields stable discharge capacity of 1000 mAh g(-1) at 0.2 C after 100 cycles. (C) 2019 Elsevier Ltd. All rights reserved.