Multidimensional Ordered Bifunctional Air Electrode Enables Flash Reactants Shuttling for High-Energy Flexible Zn-Air Batteries

摘要

Direct growth of electrocatalysts on conductive substrates is an emerging strategy to prepare air electrodes for flexible Zn-air batteries (FZABs). However, electrocatalysts grown on conductive substrates usually suffer from disorder and are densely packed with "prohibited zones", in which internal blockages shut off the active sites from catalyzing the oxygen reaction. Herein, to minimize the "prohibited zones", an ordered multidimensional array assembled by 1D carbon nanotubes and 2D carbon nanoridges decorated with 0D cobalt nanoparticles (referred as MPZ-CC@CNT) is constructed on nickel foam. When the MPZ-CC@CNT is directly applied as a self-supported electrode for FZAB, it delivers a marginal voltage fading rate of 0.006 mV cycle(-1) over 1800 cycles (600 h) at a current density of 50 mA cm(-2) and an impressive energy density of 946 Wh kg(-1). Electrochemical impedance spectroscopy reveals that minimal internal resistance and electrochemical polarization, which is beneficial for the flash reactant shuttling among the triphase (i.e., oxygen, electrolyte, and catalyst) are offered by the open and ordered architecture. This advanced electrode design provides great potential to boost the electrochemical performance of other rechargeable battery systems.