A 3D free-standing Co doped Ni2P nanowire oxygen electrode for stable and long-life lithium–oxygen batteries

Abstract

Exploring oxygen electrodes with superior bifunctional catalytic activity and suitable architecture is an effective strategy to improve the performance of lithium–oxygen (Li–O₂) batteries. Herein, the internal electronic structure of Ni₂P is regulated by heteroatom Co doping to improve its catalytic activity for oxygen redox reactions. Meanwhile, magnetron sputtering N-doped carbon cloth (N-CC) is used as a scaffold to enhance the electrical conductivity. The deliberately designed Co-Ni₂P on N-CC (Co-Ni₂P@N-CC) with a typical 3D interconnected architecture facilitates the formation of abundant solid–liquid–gas three-phase reaction interfaces inside the architecture. Furthermore, the rational catalyst/substrate interfacial interaction is capable of inducing a solvation-mediated pathway to form toroidal-Li₂O₂. The results show that the Co-Ni₂P@N-CC based Li–O₂ battery exhibits an ultra-low overpotential (0.73 V), enhanced rate performance (4487 mA h g⁻¹ at 500 mA g⁻¹) and durability (stable operation over 671 h). The pouch-type battery based on the Co-Ni₂P@N-CC flexible electrode runs stably for 581 min in air without obvious voltage attenuation. This work verifies that heterogeneous atom doping and interface interaction can remarkably strengthen the performance of Li–O₂ cells and thus pave new avenues towards developing high-performance metal–air batteries.