Lattice contraction tailoring in perovskite oxides towards improvement of oxygen electrode catalytic activity

The battery is composed of a negative Zn disc electrode and a positive La0.7Ce0.3CoO3 catalyst as air electrode assembled together in 6 M KOH with 0.2 M Zn(Ac)2. The La0.7Ce0.3CoO3 catalyst shows a peak power density of ~160 mW cm−2, superior to that of LaCoO3 catalyst. [Display omitted] •Tailoring charge density distribution can enhance oxygen electrode performance.•Lattice contraction is an optimal way to modulate charge density distribution.•Lattice contraction can decrease reaction free energy of rate-determined step. Tailoring the charge density of active metal center is one effective approach to improve the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance by accelerating the rate-determining step. Herein, we propose a novel strategy, that is, lattice contraction tailoring to modulate the charge density of active Co atom in LaCoO3 by doping Ce ions into the host lattice. The introduction of Ce can boost the bifunctional oxygen electrode activity (0.81 V) with better durability, surpassing the pure LaCoO3 (1.00 V) catalyst. Due to the improved catalysis performance, the Zn-air battery based on lattice constrain tailoring strategy has demonstrated the 1.2- and 2.0-fold enhancement for current and power densities, respectively. The theoretical calculation reveals that the lattice contraction tailoring in LaCoO3 can effectively increase the electrical conductivity, decrease the reaction free energy and enhance the rate-determining step rate, which causes the accelerated ORR and OER rates. This study provides a novel insight into designing high-performance oxygen electrocatalyst through engineering the crystal parameters of catalysts.