TY - JOUR
T1 - In operando X-ray absorption fine structure studies of polyoxometalate molecular cluster batteries
T2 - Polyoxometalates as electron sponges
AU - Wang, Heng
AU - Hamanaka, Shun
AU - Nishimoto, Yoshio
AU - Irle, Stephan
AU - Yokoyama, Toshihiko
AU - Yoshikawa, Hirofumi
AU - Awaga, Kunio
PY - 2012/3/14
Y1 - 2012/3/14
N2 - We carried out in operando Mo K-edge X-ray absorption fine structure measurements on the rechargeable molecular cluster batteries (MCBs) of polyoxometalates (POMs), in which a Keggin-type POM, [PMo 12O 40] 3-, is utilized as a cathode active material with a lithium metal anode. The POM-MCBs exhibit a large capacity of ca. 270 (A h)/kg in a voltage range between V = 4.0 V and V = 1.5 V. X-ray absorption near-edge structure analyses demonstrate that all 12 Mo 6+ ions in [PMo 12O 40] 3- are reduced to Mo 4+ in the discharging process. This means the formation of a super-reduced state of the POM, namely, [PMo 12O 40] 27-, which stores 24 electrons, and this electron number can explain the large capacity of the POM-MCBs. Furthermore, extended X-ray absorption fine structure analyses reveal the molecular structure of [PMo 12O 40] 27-, which is slightly reduced in size compared to the original [PMo 12O 40] 3- and involves Mo 4+ metal-metal-bonded triangles. Density functional theory calculations suggest that these triangles are formed because of the large number of additional electrons in the super-reduced state.
AB - We carried out in operando Mo K-edge X-ray absorption fine structure measurements on the rechargeable molecular cluster batteries (MCBs) of polyoxometalates (POMs), in which a Keggin-type POM, [PMo 12O 40] 3-, is utilized as a cathode active material with a lithium metal anode. The POM-MCBs exhibit a large capacity of ca. 270 (A h)/kg in a voltage range between V = 4.0 V and V = 1.5 V. X-ray absorption near-edge structure analyses demonstrate that all 12 Mo 6+ ions in [PMo 12O 40] 3- are reduced to Mo 4+ in the discharging process. This means the formation of a super-reduced state of the POM, namely, [PMo 12O 40] 27-, which stores 24 electrons, and this electron number can explain the large capacity of the POM-MCBs. Furthermore, extended X-ray absorption fine structure analyses reveal the molecular structure of [PMo 12O 40] 27-, which is slightly reduced in size compared to the original [PMo 12O 40] 3- and involves Mo 4+ metal-metal-bonded triangles. Density functional theory calculations suggest that these triangles are formed because of the large number of additional electrons in the super-reduced state.
UR - http://www.scopus.com/inward/record.url?scp=84863282044&partnerID=8YFLogxK
U2 - 10.1021/ja2117206
DO - 10.1021/ja2117206
M3 - Article
AN - SCOPUS:84863282044
SN - 0002-7863
VL - 134
SP - 4918
EP - 4924
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 10
ER -