TY - JOUR
T1 - 7Li nuclear magnetic resonance study of lithium insertion in pristine and partially oxidized graphite
AU - Wang, Y.
AU - Yufit, V.
AU - Guo, X.
AU - Peled, E.
AU - Greenbaum, S.
N1 - Funding Information:
This work was supported in part by grants from the United States Department of Energy, Division of Basic Energy Sciences, and the Israeli Ministry of Science. The authors would like to thank Kansai Coke for supplying the NG7 samples.
PY - 2001/3/1
Y1 - 2001/3/1
N2 - Pristine and partially oxidized graphite were lithiated electrochemically and investigated by solid state 7Li nuclear magnetic resonance (NMR) methods. Both untreated and partially oxidized graphite exhibit three kinds of reversible Li sites, one, at an average position of 43 ppm for both stage 1 and 2 intercalation compounds (LiC6 and LiC12) at intermediate and higher lithiation levels, a stage 4 intercalation compound at 3 ppm (LiC24), at low Li content, and Li associated with both edge sites and possibly stage 2L at intermediate Li content (at 11-13 ppm). The edge site population is enhanced in the partially oxidized graphite. Both treated and untreated graphite undergo reconstructive transitions in which the edge site lithium transforms into stage 1 intercalated lithium at higher levels of lithiation. Changes in both the NMR spectra and in the electrochemical parameters of stages 1, 2 and 4 have been noticed in the first two charge-discharge cycles. We attribute the changes in the NMR spectra and in the electrochemical parameters to graphite structural changes taking place in the first few cycles.
AB - Pristine and partially oxidized graphite were lithiated electrochemically and investigated by solid state 7Li nuclear magnetic resonance (NMR) methods. Both untreated and partially oxidized graphite exhibit three kinds of reversible Li sites, one, at an average position of 43 ppm for both stage 1 and 2 intercalation compounds (LiC6 and LiC12) at intermediate and higher lithiation levels, a stage 4 intercalation compound at 3 ppm (LiC24), at low Li content, and Li associated with both edge sites and possibly stage 2L at intermediate Li content (at 11-13 ppm). The edge site population is enhanced in the partially oxidized graphite. Both treated and untreated graphite undergo reconstructive transitions in which the edge site lithium transforms into stage 1 intercalated lithium at higher levels of lithiation. Changes in both the NMR spectra and in the electrochemical parameters of stages 1, 2 and 4 have been noticed in the first two charge-discharge cycles. We attribute the changes in the NMR spectra and in the electrochemical parameters to graphite structural changes taking place in the first few cycles.
UR - http://www.scopus.com/inward/record.url?scp=0034817966&partnerID=8YFLogxK
U2 - 10.1016/S0378-7753(00)00591-7
DO - 10.1016/S0378-7753(00)00591-7
M3 - מאמר
AN - SCOPUS:0034817966
VL - 94
SP - 230
EP - 237
JO - Journal of Power Sources
JF - Journal of Power Sources
SN - 0378-7753
IS - 2
ER -