Hierarchical meso-macroporous LaMnO3 electrode material for rechargeable zinc–air batteries

Abstract

Cubic-phase LaMnO3 with hierarchical meso-macroporous structures was prepared via a surfactant-templating method with the assistance of Pluronic P-123 surfactant. The sample prepared without the surfactant contained La2O3 and an unknown phase with microparticles, whereas the P-123-assisted samples were nanocrystalline perovskite LaMnO3, with a voluminous and porous microstructure. With the addition of P-123, bimodal macropores interconnected by mesostructured walls can be fabricated. The mesopore size can be regulated by adjusting the P-123 content. The electrochemical performance of the as-prepared LaMnO3 as the cathode electrode for rechargeable zinc–air batteries was evaluated using galvanostatic charge and discharge cycling measurements in a solution of 6M KOH. The sample without surfactant exhibited poor cycling stability and a relatively low discharge voltage of 1.090V, whereas the nanocrystalline and porous LaMnO3 prepared with a P-123/La molar ratio of 10 exhibited excellent cycling stability, with a maximum discharge voltage of 1.158V. The excellent performance of hierarchical meso-macroporous LaMnO3 in terms of stability and discharge voltage might be due to its single phase, large surface area, and high pore volume.