High-entropy alloy nanoparticles functionalized with reduced graphene oxide as a high-performance cathode for lithium–oxygen batteries

Abstract

One of the cruxes of developing high-performance lithium–oxygen batteries (LOBs) is the rational design and controllable synthesis of a promising cathode catalyst. High-entropy alloys (HEAs) have been considered as prospective catalytic materials for LOBs due to their adjustable composition and excellent catalytic performance. Herein, ∼50 nm PtFeCoNiCu HEA NPs with uniformly distributed elements embedded on few-layer reduced graphene oxide (PtFeCoNiCu@rGO) were successfully synthesized via a high-temperature annealing route. The LOBs with the PtFeCoNiCu@rGO cathode exhibited a high initial discharge capacity of 13 949 mA h g⁻¹, a low overpotential of 0.77 V, and remarkable cycling stability over 148 cycles with a limited capacity of 500 mA h g⁻¹ at 100 mA g⁻¹. The dominant discharge product was Li₂O₂, and no by-products were detected. These excellent electrochemical performances arose from the combined effects of reduced graphene oxide (rGO) and HEA NPs. Reduced graphene oxide, with a large specific surface area and omnipresent pores with diverse size distribution, provided sufficient storage space for Li₂O₂ and facilitated transport channels for Li⁺ and O₂, while the highly conductive HEA NPs, with optimized catalytic efficiency, further accelerated the kinetics of ORR/OER. This work presents a feasible alternative HEA-based catalyst design strategy for applicable LOBs.