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

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.