Interface Engineering of Branched PdCoP <i> _x </i> Nanostructures for High‐Performance Lithium–Oxygen Batteries

Developing advanced cathode materials plays a positive role in lowering the charge/discharge overpotentials and improving the cycling performance of lithium-oxygen batteries (LOBs). Here we report a direct synthesis strategy to prepare high-dimensional branched PdCoP_x series nanostructures, in which the Pd atoms are well dispersed within cobalt phosphide, leading to rich Pd─Co─P interfaces and evoking a prominent ligand effect between the elements. The Pd₁Co₂P_x exhibits an excellent and stable activity for oxygen reduction reaction (ORR) in alkaline media, with a mass activity of 1.46 A mg_Pd ^-1, far exceeding that of commercial Pd/C (0.12 A mg_Pd ^-1) and Pt/C (0.17 A mg_Pt ^-1). Using Pd₁Co₂P_x as the cathode, the resulting LOB shows an ultralow discharge/charge overpotential of 0.40 V and could run stably for over 240 cycles, which is a significant improvement compared with the counterparts using CoP_x and Pd/C cathodes. Experimental and density functional theory (DFT) calculation results indicate that the dispersed Pd atoms could significantly enhance the ORR kinetics, and the Pd─Co─P interfaces could direct the two-dimensional growth of Li₂O₂, thereby facilitating the formation of more easily decomposable film-like Li₂O₂ products. This feature successfully elevates both the charge and discharge performances, as well as the stability of the LOB.