Catalytic Conversion of Polysulfides on Single Atom Zinc Implanted MXene toward High‐Rate Lithium–Sulfur Batteries. (5th June 2020) - Zhang, Di
Abstract: Although lithium–sulfur (Li–S) batteries are one of the most promising energy storage devices owing to their high energy densities, the sluggish reaction kinetics and severe shuttle effect of the sulfur cathodes hinder their practical applications. Here, single atom zinc implanted MXene is introduced into a sulfur cathode, which can not only catalyze the conversion reactions of polysulfides by decreasing the energy barriers from Li2 S4 to Li2 S2 /Li2 S but also achieve strong interaction with polysulfides due to the high electronegativity of atomic zinc on MXene. Moreover, it is found that the homogenously dispersed zinc atoms can also accelerate the nucleation of Li2 S2 /Li2 S on MXene layers during the redox reactions. As a result, the sulfur cathode with single atom zinc implanted MXene exhibits a high reversible capacity of 1136 mAh g −1 . After electrode optimization, a high areal capacity of 5.3 mAh cm −2, high rate capability of 640 mAh g −1 at 6 C, and good cycle stability (80% capacity retention after 200 cycles at 4 C) can be achieved. Abstract : Single zinc atom implanted on MXene (Ti3 C2 Cl x ) layers not only possesses efficient electrocatalytic activity for polysulfides but also has a strong interaction with polysulfides owing to the high electronegativity of zinc atoms on MXene, greatly facilitating the nucleation and deposition of Li2 S2 /Li2 S on MXene layers. Thus, a stable sulfur cathode with high areal capacity and high rate capabilities is achieved.