Porous Mn2O3 cathode for highly durable Li–CO2 batteries

Abstract

Rechargeable Li–CO₂ batteries are gaining increasing popularity for reversible electrochemical energy conversion and storage by utilization of the reactions between CO₂ and Li metal. However, a high charging voltage (>4.0 V) should be applied to drive the electrochemical decomposition of the discharged products Li₂CO₃ and C, which results in a high charge overpotential and electrolyte decomposition. Therefore, low-cost and highly effective cathode catalysts are particularly desirable. Herein, porous-structured Mn₂O₃ was prepared via a facile sol–gel method and carefully characterized by SEM, TEM, XPS and Raman spectroscopy. As a cathode for Li–CO₂ batteries, Mn₂O₃ shows superior catalytic activity and durable cycling stability (2000 h) at a current density of 50 mA g⁻¹. Furthermore, the discharge products, Li₂CO₃ and C, were obtained and systematically studied using several experimental techniques. The C products obtained on the discharged Mn₂O₃ cathode exhibit highly graphitized features, as revealed by Raman spectroscopy and XPS. We believe that this study will promote the understanding of the Li–CO₂ battery reaction mechanism and the development of highly effective low-cost cathode catalysts for Li–CO₂ batteries.