Plasma Surface Engineering of NiCoS@rGO Electrocatalysts Enables High-Performance Li-O Batteries.

The sluggish redox reaction kinetics for aprotic Li-O batteries (LOBs) caused by the insulating discharge product of LiO could result in the poor round-trip efficiency, low rate capability, and cyclic stability. To address these challenges, we herein fabricated NiCoS supported on reduced graphene oxide (NiCoS@rGO), the surface of which is further modified via a unique low-pressure capacitive-coupled nitrogen plasma (CCPN-NiCoS@rGO). The high ionization environment of the plasma could etch the surface of NiCoS@rGO, introducing effective nitrogen doping. The as-prepared CCPN-NiCoS@rGO has been employed as an efficient catalyst for advanced LOBs. The electrochemical analysis, combined with theoretical calculations, reveals that the N-doping can effectively improve the thermodynamics and kinetics for LiO adsorption, giving rise to a well-knit LiO formation on CCPN-NiCoS@rGO. The LOBs based on the CCPN-NiCoS@rGO oxygen electrode deliver a low overpotential of 0.75 V, a high discharge capacity of 10,490 mA h g, and an improved cyclic stability (more than 110 cycles). This contribution may pave a promising avenue for facile surface engineering of the electrocatalyst in LOBs and other energy storage systems.