Synergistically homogeneous and heterogeneous catalytic strategy enables fast sulfur electrochemical conversion kinetics

Key Words:REDOX KINETICS; LITHIUM; BATTERIES; COMPOSITE; CATHODES

Abstract:Heterostructures composing of two coupling components are of significance for the kinetic improvements of sulfur electrochemistry. However, they encounter a challenge of being incompetent to simultanesouly catalyze the soluble lithium polysulfides via both homogeneous and heterogeneous ways. In this work, a synergistic homogeneous and heterogeneous catalytic process has been implemented in a delicately designed CoTe/Te heterostructure, which is evenly distributed on a densifying carbon framework. The highly conductive CoTe component can efficiently immobilize lithium polysulfides and heterogeneously catalyze their conversion, while the Te component can homogenously catalyze the lithium polysulfides conversion in a way of forming the electrochemically active soluble polytellurosulfide species with intrinsically accelerated redox kinetics. Besides, the densified carbon framework makes a good balance between macropores and mesopores, guaranteeing the electron conduction and alleviating the electrode volume changes. Benefited from these structural merits, the LiS batteries based on CoTe/Te heterostructure host exhibit superior rate capability (778.6 mAh/g at 4C, 1.4 times higher than sulfur cathodes without heterostructures) and cycle stability (536.7 mAh/g after 1000 cycles at 2C, 1.6 times than sulfur cathodes without heterostructures).

Volume:476

Issue:

Translation or Not:no