A Bifunctional Photo-Assisted Li-O<sub>2</sub> Battery Based on a Hierarchical Heterostructured Cathode.
basic_science · Level V
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- Record sourced from PubMed, PMID 32671896.
- Also identified by DOI 10.1002/adma.201907098.
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Abstract
Photo-assisted charging is considered an effective approach to reducing the overpotential in lithium-oxygen (Li-O<sub>2</sub> ) batteries. However, the utilization of photoenergy during the discharge process in a Li-O<sub>2</sub> system has been rarely reported, and the functional mechanism of such a process remains unclear. Herein, a novel bifunctional photo-assisted Li-O<sub>2</sub> system is established by employing a hierarchical TiO<sub>2</sub> -Fe<sub>2</sub> O<sub>3</sub> heterojunction, in which the photo-generated electrons and holes play key roles in reducing the overpotential in the discharging and charging processes, respectively. Moreover, the morphology of the discharge product (Li<sub>2</sub> O<sub>2</sub> ) can be modified via the dense surface electrons of the cathode under illumination, resulting in promoted decomposition kinetics of Li<sub>2</sub> O<sub>2</sub> during the charging progress. Accordingly, the output and input energies of the battery can be tuned by illumination, giving an ultralow overpotential of 0.19 V between the charge and discharge plateaus with excellent cyclic stability (retaining a round-trip efficiency of ≈86% after 100 cycles). The investigation of the bifunctional photo-assisted process presented here provides significant insight into the mechanism of the photo-assisted Li-O<sub>2</sub> battery and addresses the overpotential bottleneck in this system.