Photo-assisted charge/discharge Li-organic battery with a charge-separated and redox-active C60@porous organic cage cathode

Abstract

Photo-assisted Li-ion batteries provide an attractive approach for solar energy conversion and storage, while the challenge lies in the design of high-efficiency cathodes. Herein, a charge-separated and redox-active C₆₀@porous organic cage (C₆₀@POC) was synthesized to serve as a dual-functional cathode for high-efficiency photo-assisted Li-organic batteries. The designed C₆₀@POC material not only possesses enhanced charge separation efficiency (τ_CS/CR = 20.83/171.17 ps for C₆₀@POC vs. τ_CS/CR = 178.49/3.95 ps for POC) to benefit solar conversion, but also contains reversible redox-active sites to achieve energy storage. By assembling C₆₀@POC as the cathode, a photo-assisted Li-organic battery is realized with an extra 24.2% of round-trip efficiency, 81.4% increase of output power, 13.2% decrease of input power, and a high solar energy conversion efficiency of ∼1%, demonstrating an efficient solar energy conversion and storage during charge/discharge processes. Our findings reveal a qualitative correlation between charge separation and solar energy utilization efficiencies in photo-assisted Li-organic batteries, which contributes to the rational development of dual-functional organic cathodes for highly-efficient solar energy conversion and storage.