Facile Fabrication of Ag Nanocrystals Encapsulated in Nitrogen-doped Fibrous Carbon as an Efficient Catalyst for Lithium Oxygen Batteries

A facile synthesis of Ag nanocrystals encapsulated in nitrogen-doped carbon fiber(NCF)is proposed,based on the simultaneous reaction between pyrrole and Ag^(+)ions in an aqueous solvent followed by a heat treatment.The as-prepared Ag/NCF demonstrated superior catalytic behavior toward ORR and OER.Besides improved cycling stability,a much lower discharge/charge gap of 0.89 V(vs Li/Li^(+))compared with 1.38 V for NCF cathode with a fixed capacity of 500 m Ah g^(-1)was obtained in lithium oxygen batteries.The introduction of Ag crystals into NCF facilitates the oxygen reduction reaction/oxygen evolution reaction kinetics.X-ray diffraction analysis coupled with Raman spectroscopy confirmed that Ag/NCF cathode could reversibly catalyze Li_(2)O_(2)formation and decomposition.The NCF matrix offers a conductive network to realize rapid mass transfer and the encapsulated Ag nanocrystals supplied effective catalytic active sites.The combined action between both contributes to the superior electrocatalytic performance.