AUTHOR=Wei Zhaohuan , Zhang Zhiyuan , Ren Yaqi , Zhao Hong 

TITLE=A Novel Cr2O3/MnO2-x Electrode for Lithium-Oxygen Batteries with Low Charge Voltage and High Energy Efficiency

JOURNAL=Frontiers in Chemistry

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2021.646218

DOI=10.3389/fchem.2021.646218

ISSN=2296-2646

ABSTRACT=<p>A high energy efficiency, low charging voltage cathode is of great significance for the development of non-aqueous lithium-oxygen batteries. Non-stoichiometric manganese dioxide (MnO<sub>2-x</sub>) and chromium trioxide (Cr<sub>2</sub>O<sub>3</sub>) are known to have good catalytic activities for the discharging and charging processes, respectively. In this work, we prepared a cathode based on Cr<sub>2</sub>O<sub>3</sub> decorated MnO<sub>2-x</sub> nanosheets via a simple anodic electrodeposition-electrostatic adsorption-calcination process. This combined fabrication process allowed the simultaneous introduction of abundant oxygen vacancies and trivalent manganese into the MnO<sub>2-x</sub> nanosheets, with a uniform load of a small amount of Cr<sub>2</sub>O<sub>3</sub> on the surface of the MnO<sub>2-x</sub> nanosheets. Therefore, the Cr<sub>2</sub>O<sub>3</sub>/MnO<sub>2-x</sub> electrode exhibited a high catalytic effect for both discharging and charging, while providing high energy efficiency and low charge voltage. Experimental results show that the as-prepared Cr<sub>2</sub>O<sub>3</sub>/MnO<sub>2-x</sub> cathode could provide a specific capacity of 6,779 mA·h·g<sup>−1</sup> with a terminal charge voltage of 3.84 V, and energy efficiency of 78%, at a current density of 200 mA·g<sup>−1</sup>. The Cr<sub>2</sub>O<sub>3</sub>/MnO<sub>2-x</sub> electrode also showed good rate capability and cycle stability. All the results suggest that the as-prepared Cr<sub>2</sub>O<sub>3</sub>/MnO<sub>2-x</sub> nanosheet electrode has great prospects in non-aqueous lithium-oxygen batteries.</p>