Carbon- and binder-free 3D porous perovskite oxide air electrode for rechargeable lithium–oxygen batteries.

Transition-metal-doped perovskite oxide LaNi_0.9M_0.1O₃ (M = Cu, Co) nanosheets were grown on nickel foam to serve as a complete carbon- and binder-free three-dimensional (3D) porous air electrode for lithium–oxygen batteries. The design of this porous air electrode can facilitate rapid gas and electrolyte diffusion, as well as form a continuous electronic conductive network throughout the whole energy conversion process. Because of a combination of abundant lattice strain and the oxygen vacancy effect caused by substitution of an element with a different valence state in Ni sites, LaNi_0.9Cu_0.1O₃ exhibits a significant oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), showing improvement in both aqueous and non-aqueous systems compared with pure LaNiO₃ and LaNi_0.9Co_0.1O₃. Especially with the redox mediator additive tetrathiafulvalene (TTF) in the electrolyte, this LaNi_0.9Cu_0.1O₃ perovskite oxide nanosheet catalyst grown on 3D microporous nickel foam exhibits excellent bifunctional catalytic activities in the lithium–oxygen battery, showing the same highly active catalytic kinetics and high round-trip efficiency as those of reported precious metal catalysts. The overpotential remains at 0.72 V, and the round-trip efficiency is up to 80% under a current density of 0.1 mA cm⁻², with capacity limited to 1000 mA h g⁻¹. [ABSTRACT FROM AUTHOR]