Nature-inspired Three-dimensional Au/Spinach as a Binder-free and Self-standing Cathode for High-performance Li-O_(2) Batteries

Design and fabrication of functional porous air cathode materials with superior catalytic activity is still the key point for non-aqueous lithium-oxygen(Li-O2) batteries. Herein, inspired by the self-standing three-dimensional(3D) structure of the natural spinach leaves, a unique binder-free and self-standing porous Au/spinach cathode for high-performance Li-O2 batteries has been developed. The carbonized spinach leaves serve as a superconductive current collector and an ideal porous host for accommodating catalysts. The Au/spinach cathode could offer enough spaces for accommodating the discharge products, shorten the distance of the oxygen and electrolyte diffusion, and promote the oxygen reduction reaction(ORR) and oxygen evolution reaction (OER) processes. This optimized Au/spinach cathode achieved a high specific area capacity of 7.23 mA‧h/cm2 at a current density of 0.05 mA/cm2 and exhibited excellent stability(280 cycles at 0.05 mA/cm2 with a fixed capacity of 0.2 mA‧h/cm2). The superior performance encourages the construction of more advanced cathode architectures by the use of bio-composites for Li-O2 batteries.