A nickel cobaltate nanoparticle-decorated hierarchical porous N-doped carbon nanofiber film as a binder-free self-supported cathode for nonaqueous Li-O-2 batteries

Rechargeable nonaqueous lithium-oxygen (Li-O-2) batteries have been considered a promising power source candidate due to their high theoretical energy densities. Here, we in situ fabricated a three-dimensional (3D) hierarchical porous hybrid film composed of NiCo2O4 nanoparticle (NP)-decorated mesoporous N-doped carbon nanofibers (NCO@NCF), using single-nozzle co-electrospinning combined with annealing treatment. This hybrid film can serve directly as a binder-free self-supported cathode for Li-O-2 batteries that exhibit high specific capacity (5304 mA h g(-1)), excellent rate capability, and outstanding cycling stability (close to 100 cycles), benefiting from its structural and material superiority. Its hierarchical porous structure not only can facilitate O-2 diffusion and enhance electrolyte infiltration but also promises abundant Li2O2 storage. In addition, crisscross N-doped carbon nanofibers with high graphitization form a perfect conductive network, which ensures the fast transmission of electrons and avoids binder-induced adverse side reactions. Moreover, the homogenously distributed NiCo2O4 NPs possess efficient contact with both Li+ and O-2 and supply numerous catalytically active sites, thus leading to high-efficiency difunctional catalytic activities for the ORR and OER. Therefore, these encouraging results suggest an effective approach to obtaining high-performance nonaqueous Li-O-2 batteries by optimizing the electrode structures and catalyst properties.