Preferential enhancement of high-rate performance in LiNi0.5Mn1.5O4 cathodes via improved ion transport kinetics and structural stability

Abstract

Spinel LiNi0.5Mn1.5O4 (LNMO) cathodes offer significant potential for grid-scale energy storage, combining the merits of low cost and a high voltage plateau (∼4.7 V vs Li+/Li). However, they still suffer from rapid capacity decay, especially at high C-rates, due to confined ion transport kinetics and severe structural instability upon cycling. Herein, we incorporated fluorine into LNMO and found that F− incorporation induces an increase in the Mn3+ ratio and disorder degree in the lattice, promoting the expansion of interplanar spacing for fast ion transport and the optimization of structural stability for performance improvement. The as-obtained F− incorporated cathodes exhibit preferential enhancement of high-rate performance at 2C and 5C compared to low-rate performance at 0.5C and 1C. Moreover, this work clarifies the importance of the Mn3+ coordination environment for the structural stability of LNMO and highlights the potential of LNMO cathodes for fast-charging applications.