The effects of nanostructures on lithium storage behavior in Mn_2O_3 anodes for next-generation lithium-ion batteries

摘要

Nanostructured materials for lithium-ion batteries (LIBs) have many advantages over bulk electrode materials, and therefore, such materials should be effectively utilized in next-generation batteries. Herein, we identify that the superior performances of mesoporous Mn2O3 results from the different lithium storage behaviors of mesoporous and bulk Mn2O3. X-ray absorption spectroscopy (XAS) and bond strength calculation show that mesoporous Mn2O3 has a larger capacity than bulk Mn2O3 owing to an additional oxidation of Mn2+ to a higher oxidation state during charging, as well as an additional reversible reaction during cycling because the weaker Mn-O bond strength of mesoporous Mn2O3 requires much less strength to break or form atomic bonds during the electrochemical reactions. Furthermore, the combined results of X-ray photoelectron spectroscopy and soft XAS indicate that an additional lithium storage reaction through the reversible formation-decomposition of the electrolyte-derived surface layer occurs more in mesopomus Mn2O3 than in bulk Mn2O3. Consequently, the improvement in the lithium storage behavior of mesoporous Mn2O3 due to the increasing specific surface area and decreasing particle size with the progression of cycles, also affects their cycle performances. This study provides a better understanding of the synergistic relationship between nanostructures and the electrochemical performances of anode materials for LIBs.