Highly efficient two-dimensional Ag2Te cathode catalyst featuring a layer structure derived catalytic anisotropy in lithium-oxygen batteries

Abstract

Two-dimensional (2D) materials have recently become one of the most suitable candidates as cathode catalysts for lithium-oxygen batteries (LOBs) due to their unique electronic properties and good stability. However, the variation of the layer structures will trigger catalytic anisotropy leading to different performance in LOBs. In this work, narrow gap telluride Ag2Te with a chemical bonded 2D layer structure composed by Ag-Te tetrahedral stacking layer was applied as the highly efficient catalyst for LOBs. Ag2Te nanowires (NWs) were synthesized and exhibited superior specific capacity over 15,000 mAh g−1, outstanding rate capabilities, and ultralong high-rate cycle stability over 300 cycles at 500 mA g−1 and 220 cycles at 1000 mA g−1 with the fixed capacity of 1000 mAh g−1 when used as the cathode catalyst in LOBs. Experimental studies and DFT calculations reveal that Ag2Te with a chemical bonded 2D layer structure exhibited outstanding catalytic capability and weak structure derived catalytic anisotropy in LOBs, in which the 2D stacking surface (200) plane and side edge planes both exhibit superior catalytic activity. For comparison, the Ag-terminated 2D stacking surface (200) plane exhibits high active catalytic capability with low overpotentials during ORR/OER process derived from the appropriate adsorption energy for the adsorbates, stable surface, and highly efficient charge transfer during the growth of discharge products. The current contribution provides an in-depth insight to understanding the 2D structure derived elusive catalytic mechanism in LOBs.