Defect-rich boron doped carbon nanotubes as an electrocatalyst for hybrid Li–air batteries

Abstract

Carbon nanotubes (CNTs) have been used as a cathode material for hybrid Li–air batteries (HLABs); however, their catalytic abilities for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are relatively limited. Herein, to improve their catalytic performance, we have synthesized a boron-doped CNT (BC₃NT) with varying boron contents. The Raman spectrum proves that the more defects are due to the higher boron content. And HLABs based on BC₃NT show great cyclability and catalytic performance in air, with an overpotential value of 0.3 V for 200 hours at a current density of 0.05 mA cm⁻². Furthermore, theoretical calculations with density functional theory (DFT) confirm the effects of topological defects of BC₃NT on the ORR and OER. Since boron is doped into the CNT, BC₃NT containing a large amount of defect rings is obtained. And the generation of defects was conducive to the battery reaction. Accordingly, as a positive electrode material for HLABs, BC₃NT is more conducive to the ORR and OER, and the topological defect ring generated by it improved the ORR and OER performance.