Engineering of MnTe/MnO Heterostructures with Interfacial Electric Field Modulation for Efficient and Durable Li-O2 Batteries.

ABSTRACT

Design and synthesis of highly active and robust bifunctional cathode catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are of vital significance for practical applications of lithium-oxygen (Li-O2) batteries. Herein, a built-in electric field (BIEF) strategy is reported to fabricate MnTe/MnO heterostructures with a large work function difference (ΔΦ) as a bifunctional cathode catalyst in Li-O2 batteries. The MnTe/MnO heterostructures with nanosheets and microporous structures result in an abundance of exposed active sites and facilitate mass transfer. More importantly, the heterogeneous MnTe/MnO nano-interface region provides a BIEF that can trigger interfacial charge redistribution, fine-tune the adsorption energy of oxygen intermediates, and alter the morphology of discharge products to accelerate ORR/OER kinetics. Impressively, the fabricated Li-O2 batteries with MnTe/MnO cathode showcases exhibit excellent electrochemical performances, including low charging overpotential, a high specific capacity of 11930 mA h g-1, and good cycle stability over 350 cycles even with a fixed specific capacity of 500 mA h g-1 at a current density of 500 mA g-1. This work provides an avenue for the rational design of high performance heterostructure electrocatalysts toward practical applications for rechargeable Li-O2 batteries.