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

[Display omitted] • Photocatalytic WSe 2 nanofibers were fabricated by combining multivariate electrospinning and chemical vapor deposition. • The photocathode under illumination enables to lower the polarization, enhance the capacity and extend the stability concertedly. • Flexible Li-O 2 pouch cells with transparent casing are demonstrated. • The enhanced performance is attributed to light-ameliorated electrochemical microenvironment on both the cathode and anode. Solar-assisted Li-O 2 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 WSe 2 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 Li 2 O 2 conversion catalyzed by WSe 2 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-O 2 batteries in flexible electronics and wearable gadgets. [ABSTRACT FROM AUTHOR]