화학공학소재연구정보센터
Journal of the Electrochemical Society, Vol.164, No.12, A2348-A2354, 2017
Role of L-Ascorbic Acid-Based Treatment toward Improving the Electrochemical Performance of Li-Rich Layered Oxide
In this work, the effect of an L-ascorbic acid-based treatment on the physicochemical and electrochemical properties of a Li-rich oxide has been studied. Clear corrosion cavities with spinel coating layers were observed over the majority of the particle's surface, and these have been ascribed to the Li+-H+ exchange and reduction of Mn4+ to Mn2+, which is more soluble in the L-ascorbic acid solution. Furthermore, a special region without obvious traces of etching is observed over a small part of the surface of the L-ascorbic acid-treated sample, which arises from the enrichment of Ni2+ at the rim of the particle. Compared to the pristine oxide, the modified samples exhibit significantly higher initial discharge capacity/Columbic efficiency, remarkably enhanced rate performance, and considerably retarded voltage decay. The specific energy density and energy retention after 100 cycles of usage, increases from 497.6 Wh kg(-1) and 63.4% for the pristine oxide to 640.8 Wh kg(-1) and 68.9% for the modified sample. This enhancement in the electrochemical performance of the modified samples can be attributed to the synchronous formation of the spinel coating layer and modification of the bulk microstructure of the Li-rich layered oxide. (C) 2017 The Electrochemical Society. All rights reserved.