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Reversible Lithium Storage with High Mobility at Structural Defects in Amorphous Molybdenum Dioxide Electrode
Author(s) -
Ku Jun H.,
Ryu Ji Heon,
Kim Sun Ha,
Han Oc Hee,
Oh Seung M.
Publication year - 2012
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201102669
Subject(s) - materials science , electrode , lithium (medication) , amorphous solid , molybdenum , formula unit , oxide , chemical engineering , crystal structure , crystallography , metallurgy , chemistry , medicine , endocrinology , engineering
Abstract This work demonstrates that structural defects in amorphous metal oxide electrodes can serve as a reversible Li + storage site for lithium secondary batteries. For instance, molybdenum dioxide electrode in amorphous form ( a ‐MoO 2 ) exhibits an unexpectedly high Li + storage capacity (up to four Li per MoO 2 unit), which is larger by a factor of four than that for the crystalline counterpart. The conversion‐type lithiation is discarded for this electrode from the absence of Mo metal and lithium oxide (Li 2 O) in the lithiated a ‐MoO 2 electrode and the retention of local structural framework. The sloping voltage profile in a wide potential range suggests that Li + ions are inserted into the structural defects that are electrochemically nonequivalent. This electrode also shows an excellent cycle stability and rate capability. The latter feature is seemingly due to a rather opened Li + diffusion pathway provided by the structural defects. A high Li + mobility is confirmed from nuclear magnetic resonance study.