Semin
nar in thee University of E
Edinburgh
Date: 112 pm on 29th2Sept. 2014
Title: Novel reechargeab
ble batteeries usinng molec
cularclusterrs as cathode active
e materialls
Hirofum
mi Yoshikawa
Deparrtment of Chemistry, Naggoya Univers
sity, Furo-choo, Chikusa, NNagoya
Em
mail: yoshika
awah@chem.nagoya-u.acc.jp
Soolid-state elecctrochemistry is a wide research areea covering various topiics from fundamental
sciencess to applicatiions. At pressent, one of the most important goals is to devellop high-perfformancerecharge
eable batteries due to the ever-inccreasing energy demannds and preessing environmental
concernss. We have recently pro
oposed a neew type of liithium batterry, “the moleecular cluste
er battery(MCB)”, in which thee cathode ac
ctive materia
als are polyn
nuclear meta
al complexess (molecular clusters)such as Mn12 clusteers ([Mn12O12(RCOO)16(HH2O)4], R = CH3, C6H5, etcc.) and polyooxometalatess (POMs),
in order to achieve bothb
high batttery capacityy and fast chharging/dischharging. It iss expected thhat MCBs
would shhow a high capacitycand a rapid cha
arging/discha
arging due to multi-electroon redox rea
actions of
the moleecular clusterrs and quick lithium-ion ddiffusion, resp
pectively (thee left of Fig. 1).
In tthis seminarr, I talk aboutt the perform
mance of the MCBs based on “solid-sstate electroc
chemistry
3of moleccular clusterss”. Actually, using
ua Kegg
gin-type POM
M, [PMo12O40
ell known
4 ] (KPOM),, which is we
as catalyysts, as a ca
athode-active material, w
we achievedd a higher ba
attery capaccity of ca. 27
70 Ah/kg,
which w
was larger tha
an those of the lithium iion batteriess (ca. 148Ah/kg), and a more rapid charging.
Operanddo Mo K-ed
dge X-ray absorption
affine structure (XAFS) analyses oon the KPO
OM-MCBs
demonsttrated that KPOM
K
underw
went twenty ffour electron
ns reduction in the dischaarging processs, whichindicatedd that all ofo Mo6+ ionss in KPOM changed into Mo4+. ThisT
means the formattion of a2
super-reeduced state,, [PMo12O40]27, and the ssuper-reduction electron number
nof tw
wenty four ca
an explain
the largee capacity ofo the KPOM
M-MCBs. Th
his electron sponge behaviour indiccates that molecularmclusters are promissing cathod
de active mmaterials forr high-performance recchargeable batteries.
Furtherm
more, we exh
hibited nano-hybrid materrials between
n KPOMs and single-wallled carbon nanotubes(SWNTss), in which KPOMs are individually adsorbed ono the SWNT surfaces ffor applicatio
on to thecathode active materials of MCBs (the right oof Fig. 1). Th
he charging/ddischarging mmeasuremen
nts for theKPOM-S
SWNT hybridd MCBs ind
dicated a higgher battery capacity annd a faster charging/disscharging
compareed with thosee of the initiall KPOM MCB
Bs.

FFig.1. Schem
matic View of MCBs (Left)) and TEM Im
mages of Nan
nohybrid Matterials (Rightt).
Referencces
1) H. Yosshikawa et al., Chem. Commun. 2007,, 3169-3170. 2) H. Yoshikawa et al., Innorg. Chem. 2009, 48,9057-905
59. 3) H. Yoshikawa et al., Chem.
CAsian JJ. 2011, 6, 107
74-1079. 4) H. Yoshikawa ett al., J. Am. Chem.
CSoc.
2012, 134
4, 4918-4924. 5) H. Yoshika
awa et al., Ang
gew. Chem. In
nt. Ed. 2011, 50,5 3471-34744. 6) H. Yoshikawa et al.,Dalton Trrans. 2012, 4, 9863-9866. 7)
7 H. Yoshikaw
wa et al., Chemm. Eur. J. 2013, 19, 11235- 11240. 8) H. Yoshikawa
Yet al., J. M
Mater. Chem. A 2014, 2, 38001-3807. 9) H . Yoshikawa ete al., Chem. Lett, in press. 110) H. Yoshika
awa, S. Irleet al., J. AAm. Chem. Sooc. in press.