Stabilization of spinel-like phase transformation of o-LiMnO2 during 55 degrees C cycling by sol-gel coating of CoO

Abstract

Low-temperature sol-gel coating of CoO on orthorhombic LiMnO2 (o-LiMnO2) particles greatly stabilizes spinel-like phase transformation during electrochemical cycling at 55 degreesC. Enhanced structural stability of the coated o-LiMnO2 is because discretely higher Co concentration at the surface than in the bulk improves the structural stability of cycling-induced LiMn2O4 and Li2Mn2O4 phases. The coated o-LiMnO2 shows increased discharge capacity to 185 from 170 mAh/g at 0.2 C rate (=36 mA/g) cycled between 4.5 and 2 V. In addition, the coated o-LiMnO2 exhibits smaller capacity fading than the bare one (35%), showing only 12% capacity loss of the discharge capacity after 50 cycles.