Kinetic insight into perovskite La0.8Sr0.2VO3 nanofibers as an efficient electrocatalytic cathode for high-rate Li-O-2 batteries

초록

Efficient electrocatalysis at the cathode is essential for overcoming the limitations of Li-O-2 batteries such as poor stability and low rate capability. Herein, we systematically studied the kinetic behavior of a Li-O-2 battery comprising perovskite La0.8Sr0.2VO3 nanofibers formed by partial Sr-cation doping and V cations with multiple oxidation states. Compared with undoped LaVO3 and La0.8Sr0.2VO4 nanofibers, perovskite La0.8Sr0.2VO3 nanofibers exhibited an improved capacity of 2000 mA g(-1), and a 20-times-longer cycle life in Li-O-2 batteries. X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, and photoluminescence analyses revealed that the performance variations mainly originated from crystal defects, which modulate oxygen reduction/evolution kinetics. Through in situ Raman analysis, we showed that these structural defects are closely related to the oxygen reduction/evolution behavior of La0.8Sr0.2VO3 nanofibers and result in fewer parasitic reactions. This study offers insights into the potential rate capability of Li-O-2 batteries and related devices.

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