Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Anion Redox Chemistry in the Cobalt Free 3d Transition Metal Oxide Intercalation Electrode Li[Li 0.2 Ni 0.2 Mn 0.6 ]O 2
AU - Luo, Kun
AU - Roberts, Matthew R.
AU - Guerrini, Niccoló
AU - Tapia-Ruiz, Nuria
AU - Hao, Rong
AU - Massel, Felix
AU - Pickup, David M
AU - Ramos, Silvia
AU - Liu, Yi-Sheng
AU - Guo, Jinghua
AU - Chadwick, Alan V.
AU - Duda, Laurent C.
AU - Bruce, Peter G.
PY - 2016/9/7
Y1 - 2016/9/7
N2 - Conventional intercalation cathodes for lithium batteries store charge in redox reactions associated with the transition metal cations, e.g. Mn 3+/4+ in LiMn 2 O 4 , and this limits the energy storage of Li-ion batteries. Compounds such as Li[Li 0.2 Ni 0.2 Mn 0.6 ]O 2 exhibit a capacity to store charge in excess of the transition metal redox reactions. The additional capacity occurs at and above 4.5 V vs. Li + /Li. The capacity at 4.5 V is dominated by oxidation of the O 2-anions accounting for ~0.43 e -/formula unit, with an additional 0.06 e -/formula unit being associated with O loss from the lattice. In contrast, the capacity above 4.5 V, is mainly O loss, ~ 0.08 e -/formula. The O redox reaction involves the formation of localized hole states on O during charge, which are located on O coordinated by (Mn 4+ /Li +). The results have been obtained by combining operando electrochemical mass spec on 18 O labelled Li[Li 0.2 Ni 0.2 Mn 0.6 ]O 2 with XANES, soft X-ray spectroscopy, Resonant Inelastic X-ray spectroscopy and Raman spectroscopy. Finally the general features of O-redox are described with discussion about the role of comparatively ionic (less covalent) 3d metal-oxygen interaction on anion redox in lithium rich cathode materials.
AB - Conventional intercalation cathodes for lithium batteries store charge in redox reactions associated with the transition metal cations, e.g. Mn 3+/4+ in LiMn 2 O 4 , and this limits the energy storage of Li-ion batteries. Compounds such as Li[Li 0.2 Ni 0.2 Mn 0.6 ]O 2 exhibit a capacity to store charge in excess of the transition metal redox reactions. The additional capacity occurs at and above 4.5 V vs. Li + /Li. The capacity at 4.5 V is dominated by oxidation of the O 2-anions accounting for ~0.43 e -/formula unit, with an additional 0.06 e -/formula unit being associated with O loss from the lattice. In contrast, the capacity above 4.5 V, is mainly O loss, ~ 0.08 e -/formula. The O redox reaction involves the formation of localized hole states on O during charge, which are located on O coordinated by (Mn 4+ /Li +). The results have been obtained by combining operando electrochemical mass spec on 18 O labelled Li[Li 0.2 Ni 0.2 Mn 0.6 ]O 2 with XANES, soft X-ray spectroscopy, Resonant Inelastic X-ray spectroscopy and Raman spectroscopy. Finally the general features of O-redox are described with discussion about the role of comparatively ionic (less covalent) 3d metal-oxygen interaction on anion redox in lithium rich cathode materials.
U2 - 10.1021/jacs.6b05111
DO - 10.1021/jacs.6b05111
M3 - Journal article
C2 - 27498756
VL - 138
SP - 11211
EP - 11218
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 35
ER -