Effect of nitrogen-doped carbon/Ketjenblack composite on the morphology of Li2O2 for high-energy-density Li–air batteries

Abstract

A series of nitrogen-doped carbon/Ketjenblack (KB) composites is synthesized by pyrolyzing nitrogen-containing ionic liquid (IL) on KB. The obtained composites have a significant effect on the morphology of Li2O2 in nonaqueous Li–air batteries. As the surface catalytic layer, the nitrogen-doped carbon significantly enhances the discharge capacity to >9905 mAh g−1 in artificial dry air, comparable to the performance of air-cathodes with precious metal catalysts under pure oxygen environment. This increase in the accommodating capacity of Li2O2 could be attributed to the high utilization ratio of air-cathode's porosity, resulting from the domination of solvent pathway during the growth of Li2O2, which is probably preferred around the pyridinic-N sites of the nitrogen-doped carbon layer. The results of this study demonstrate that the proposed carbonaceous materials could produce high-energy-density Li–air batteries without the use of precious metal catalysts.