Novel and highly efficient cathodes for Li-O2 batteries: 3D self-standing NiFe@NC-functionalized N-doped carbon nanonet derived from Prussian blue analogues/biomass composites

Abstract Traditional 3D self-standing electrodes for lithium-oxygen (Li-O2) batteries require a high cost and complex preparation process that restrict their development. Herein, discarded biomass (pomelo peel, PP) is used as raw material and in-situ grew NiFe-Prussian blue analogues on its surface. Then a novel 3D binder-free and self-standing NiFe@NC/PPC electrode is obtained through the carbonization process and directly used as a cathode in Li-O2 batteries. Compared with PPC (carbonized pomelo peel) and NiFe@NC/CP (NiFe@NC catalysts coated on carbon paper), NiFe@NC/PPC gathered the advantageous characteristics of i) efficient diffusion rates for O2/electrolyte and ii) good catalytic activity for oxygen reduction reaction/oxygen evolution reaction (ORR/OER). The as fabricated Li-O2 batteries, with NiFe@NC/PPC as cathode, are performed a relatively high specific capacity (13.79 mAh cm−2), a long cycle life (290 cycles) at a current density of 0.1 mA cm−2. Therefore, considering the convenience of synthesis method and the inexpensive raw materials, this is a feasible way to prepare high performance and low cost cathodes for Li-O2 batteries.