Defect mechanism of the BixSb2−xTe3 alloy catalyst for lithium–oxygen battery applications

Abstract

Non-aqueous lithium–oxygen batteries (LOBs) have received considerable attention because of their ultrahigh theoretical energy density, but they are severely hindered by sluggish reaction kinetics, strong redox reaction intermediates, and side reactions between carbon and electrolyte/solid products. Herein, Bi_xSb_2−xTe₃ ternary alloy materials with different contents of Bi and Sb were designed as LOB cathode catalysts by a one-step hydrothermal method. The introduction of Sb leads to an increase in the carrier concentration and improvement in the conductivity of the catalyst, owing to the formation of defects. It also favors the exposure of effective active sites. Bi_0.6Sb_1.4Te₃ with a stacked-layer (0 0 1) crystal surface has the smallest grain size and the largest specific surface area, which can effectively promote the formation and decomposition of Li₂O₂ when used as the cathode material. It exhibits a superior specific capacity of over 21 194.67 mA h g⁻¹ and ultralong cycling stability over 240 cycles at 200 mA g⁻¹ in LOBs. This study provides an important reference for the electrocatalytic mechanism of two-dimensional main-group metal materials in LOBs.