Zinc-Assisted Cobalt Ditelluride Polyhedra Inducing Lattice Strain to Endow Efficient Adsorption-Catalysis for High-Energy Lithium-Sulfur Batteries.

Abstract

Developing a conductive catalyst with high catalytic activity is considered to be an effective strategy for improving cathode kinetics of lithium-sulfur batteries, especially at large current density and with lean electrolytes. Lattice-strain engineering has been a strategy to tune the local structure of catalysts and to help understand the structure-activity relationship between strain and catalyst performance. Here, Co0.9 Zn0.1 Te2 @NC is constructed after zinc atoms are uniformly doped into the CoTe2 lattice. The experimental/theoretical results indicate that a change of the coordination environment for the cobalt atom by the lattice strain modulates the d-band center with more electrons occupied in antibonding orbitals, thus balancing the adsorption of polysulfides and the intrinsic catalytic effect, thereby activating the intrinsic activity of the catalyst. Benefiting from the merits, with only 4 wt% dosages of catalyst in the cathode, an initial discharge capacity of 1030 mAh g-1 can be achieved at 1 C and stable cycling performances are achieved for 1500/2500 cycles at 1 C/2 C. Upon sulfur loading of 7.7mg cm-2 , the areal capacity can reach 12.8 mAh cm-2 . This work provides a guiding methodology for the design of catalytic materials and refinement of adsorption-catalysis strategies for the rational design of cathode in lithium-sulfur batteries.