Highly Dispersed Ultrafine Ruthenium Nanocrystals Anchored on Metal Oxides as Efficient Hybrid Catalysts for Li–O2 Batteries

The practical application of Li–O2 batteries is severely hindered by parasitic reactions on the cathode side, which generally lead to large charging over-potentials and degraded cyclic performance. To address this issue, it is essential to integrate high-efficiency catalysts into conventional carbon-based electrodes. Herein, we report a novel La0.85Ca0.15Cr0.85O3@Ru (LCC@R) hybrid catalyst with an ultralow Ru loading (6.55 wt.%), synthesized via a facile sol-gel combined with in-situ reduction-exsolution method. Mono-dispersed and ultrafine Ru nanocrystals (2–5 nm) are uniformly anchored on the LCC substrate and serve as the catalytically active sites. The Li–O2 battery with the LCC@R catalyst exhibits a low charge potential of 3.75 V at a current density of 50 mAg−1 with limited capacity of 500 mAhg−1. Impressive cyclic stabilities of up to 80 cycles (at 1000 mAhg−1) and 15 cycles (at 2000 mAhg−1) are achieved. Moreover, a large specific capacity of 8630 mAhg−1 is delivered at 50 mAg−1. Mechanistic studies reveal that the intermediate discharge product LiO2 can be absorbed on LCC@R, thereby inhibiting the parasitic reactions induced by LiO2 attack on carbon. The as-prepared LCC@R hybrid material is a promising cathode catalyst for constructing long-cycle-life and low-over-potential Li–O2 batteries.