Highly performing free standing cathodic electrocatalysts for Li-O2 batteries: CoNiO2 nanoneedle arrays supported on N-doped carbon nanonet

[Display omitted] •A novel 3D free-standing air cathode was fabricated via a simple method.•Biomass derived N-doped carbon nanonet was used as the support and CoNiO2 nanoneedles as the catalyst.•Li-O2 batteries with CoNiO2/SCC-N cathodes deliver superior capacity and cycle performance.•Growth of CoNiO2 nanoneedles in N-doped carbon fibers remarkably decrease overpotential during discharge-charge process. Lithium-oxygen (Li-O2) batteries are considered as promising candidates for future energy storage systems due to their super-high theoretical energy densities. However, the poor cyclic stability and low efficiency still hinder their commercialization, which is mainly attributed to the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) processes. In the present work, we fabricated a three-dimensional (3D) air cathode composed of CoNiO2 nanoneedles decorated N-doped porous carbon nanonet (CoNiO2/SCC-N), using silkworm cocoons as the raw materials and following the carbonization-hydrothermal route. The as fabricated batteries, with CoNiO2/SCC-N air cathode, are exhibited a very good discharge capacity of 1654 mAh g−1cathode at a current density of 0.05 mA cm-2, presenting a stability of over 147 cycles. The observed electrochemical performance is attributed to the synergistic effect of the enhanced ORR/OER activity after the introduction of CoNiO2 and the efficient mass transport characteristics of SCC-N.