Facet-engineered photoelectrochemical nanocatalysts toward fast kinetic lithium–air batteries

Abstract

Despite lithium–air batteries having unprecedented theoretical energy supremacy, rambling Li₂O₂ growth typically impedes O₂ diffusion and electron transfer, causing low capacity, poor charging kinetics and short cycle life. Herein, we propose synergistic catalysis in the cathode by engineering the crystal facet of Fe₂O₃ nanoplates and introducing a visible light-excited photochemical effect. The growth of Li₂O₂ is regulated with a uniform distribution, mitigating local product aggregation and thus reducing the barriers of O₂ diffusion and electron transfer. The improved reaction kinetics lead to ∼420% capacity improvement, low charge potential, superior rate performance, and long-term stability (300 cycles) in actual air. We reveal a mechanism that photoelectrons around each catalyst node and the resultant homogeneous internal electric field increase charge transfer, decrease soluble intermediates, and enable high electrochemical reversibility of amorphous Li₂O₂ with an ordered process. This study provides inspiring insights for future research into controlling product ordering in Li–air batteries.