Photoluminescent WSe2 nanofibers as freestanding cathode for Solar-assisted Li-O2 battery with ultrahigh capacity and transparent casing

Abstract

Solar-assisted Li-O2 battery has elicited tremendous interests owing to its greatly elevated round-trip energy efficiency, but challenges remain to synergize the photovoltaic effect with catalytic activity of the active material. Herein, through a novel synthetic tactic of combining multivariate electrospinning with chemical vapor deposition, we fabricate a freestanding and photoluminescent oxygen cathode comprising WSe2 embedded into CNT-reinforced carbon nanofibers for the first time. The optimal photocathode delivers an ultrahigh discharge capacity of 57.17 mAh cm−2 in dark, and triples the capacity under illumination with a narrowed discharge/charge voltage gap as low as 0.49 V. Comprehensive mechanistic investigations attribute the superb battery performance to the reversible Li2O2 conversion catalyzed by WSe2 and the photo-ameliorated electrochemical microenvironment on both the cathode and anode. By demonstrating pouch cells with transparent casing, this study paves the way for the real-world application of solar-assisted Li-O2 batteries in flexible electronics and wearable gadgets.