Effectively Suppressing Dissolution of Manganese from LiMn2O4 Spinel Via a Novel Nanoscale Surface-Doping Approach

Abstract

The capacity fade of LiMn2O4-based cells is directly associated with the dissolution of Mn from the cathode/electrolyte interface due to the disproportion reaction of Mn(III), and the subsequent deposition of Mn2+ onto the anode leading to an increase in impedance of the cell. Suppressing the dissolution of Mn from the cathode is therefore critical to reducing capacity fade of LiMn2O4–based cells. In this work, we report a novel nanoscale surface-doping approach that minimizes Mn dissolution from LiMn2O4. This new approach exploits advantages of both bulk doping and surface coating methods by a) stabilizing the surface crystal structure of LiMn2O4 through cationic doping while maintaining the bulk spinel LiMn2O4 structure, and b) protecting the bulk LiMn2O4 from electrolyte corrosion while maintaining ion and charge transport channels on the surface through the electrochemically active doping layer. As a consequence, the surface-doped LiMn2O4 demonstrates significantly enhanced electrochemical performance in terms of cycleability and capacity at elevated temperature. This study provides encouraging evidence that surface doping could be a promising alternative to improve the cycling performance of lithium-ion batteries.