A high-energy-density lithium-oxygen battery based on a reversible four-electron conversion to lithium oxide.
basic_science · Level V
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- Record sourced from PubMed, PMID 30139868.
- Also identified by DOI 10.1126/science.aas9343.
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Abstract
Lithium-oxygen (Li-O<sub>2</sub>) batteries have attracted much attention owing to the high theoretical energy density afforded by the two-electron reduction of O<sub>2</sub> to lithium peroxide (Li<sub>2</sub>O<sub>2</sub>). We report an inorganic-electrolyte Li-O<sub>2</sub> cell that cycles at an elevated temperature via highly reversible four-electron redox to form crystalline lithium oxide (Li<sub>2</sub>O). It relies on a bifunctional metal oxide host that catalyzes O-O bond cleavage on discharge, yielding a high capacity of 11 milliampere-hours per square centimeter, and O<sub>2</sub> evolution on charge with very low overpotential. Online mass spectrometry and chemical quantification confirm that oxidation of Li<sub>2</sub>O involves transfer of exactly 4 <i>e</i><sup>-</sup>/O<sub>2</sub> This work shows that Li-O<sub>2</sub> electrochemistry is not intrinsically limited once problems of electrolyte, superoxide, and cathode host are overcome and that coulombic efficiency close to 100% can be achieved.