Bi2S3/Ketjen Black as a Highly Efficient Bifunctional Catalyst for Long‐Cycle Lithium‐Oxygen Batteries

Abstract A catalyst that possesses an efficient bifunctional catalytic activity is vital to achieve long‐life lithium‐oxygen (Li−O 2 ) batteries. Herein, a bismuth sulfide/Ketjen black (Bi 2 S 3 /KB) hybrid is synthesized through a one‐step hydrothermal method and used as a bifunctional catalyst in Li−O 2 batteries. The results demonstrate that Li−O 2 batteries with the Bi 2 S 3 /KB hybrid exhibit both a higher capacity and a lower overpotential than those with the bare bismuth sulfide (Bi 2 S 3 ) and KB catalysts. A Li−O 2 battery with the Bi 2 S 3 /KB catalyst shows an excellent cycle life of 391 cycles at 1000 mA h g −1 , which is one of the best results for batteries with sulfide catalysts. The excellent electrochemical performance of the batteries originates from the synergistic catalytic effect between Bi 2 S 3 and KB. It is found that the Li 2 O 2 is deposited on Bi 2 S 3 nanorods prior to on KB upon discharge, which can defer the deactivation of the cathode and inhibit the side reactions.