7Li MAS NMR studies of layered LixCoO2 prepared using eutectic self-mixing technique for a cathode material

Abstract

Layered LixCoO2 (x=1.0, 1.05, and 1.1) samples prepared by eutectic self-mixing technique were characterized by solid-state 7Li MAS NMR. Simulations of 7Li NMR spectra were performed to identify the lithium sites. For Li1.0CoO2, a unique lithium site was observed at about 0 ppm, which was assigned as octahedral site having CQ=0.92 MHz and η=0. By increasing content of lithium in LixCoO2, additional lithium sites having larger quadrupolar interaction were observed. For Li 1.05CoO2, an additional site including octahedral site was observed and determined as CQ=3.0 MHz and η=0. A resonance at about -15 ppm was also detected. For Li1.1CoO2, a lithium site having CQ=3.77 MHz and η=0.1 was additionally observed. The electrochemical property of LixCoO2 was extremely related with local environment of lithium sites. © 2004 Elsevier B.V. All rights reserved. Lithium rechargeable battery; LiCoO2;.