Transport Properties of the Intercalated Layered Cathode Materials: Li X Mo 2 O 4 .
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TRANSPORT
PROPERTIES OF THE INTERCALATED CATHODE MATERIALS : LIxMO204.
LAYERED
KLEIN* SZU* AND L.C. TARASCON**; S. S. COLSON*; J.M. *Rutgers Univ., Ceramics Department, Piscataway, NJ 08855. **Bellcore,331 Newman Springs Rd., Red Bank, NJ 07701.
ABSTRACT The mixed conducting Li.M020 4 system was shown to (530Wh/kg) and average exhibit a high energy density voltage (3.1V), suggesting that it would be a good in a Li-anode secondary candidate for a cathode of these oxide properties The transport battery. 7 materials were then investigated by solid state Li NMR, dc and ac electrical measurements. The following phases are emphasized in this study: Li 1 . 3 MO20 4 , Li 2MO20 4 , and the hydrated phase Li 0 . 5 (H 2 0) 1 . 3 M02O 4 .
INTRODUCTION Electrochemical studies have demonstrated the existence of four single phases in the LixM020 4 system for 0.35x52 as well as their efficiency as a cathode material in room temperature secondary batteries [1]. Furthermore, it has been shown that the intercalation process is not only specific to cations, but can also be extended to water [1,2]. X-ray diffraction studies [3,4] showed that these compounds crystallize to form a monoclinic unit cell. Their structure consists of MoO 2 layers (where distorted MoO 6 octahedra form infinite double chains along the b-axis), between which the lithium ions occupy octahedral sites. The uptake of lithium atoms between the MoO 2 layers was postulated to depend essentially of electronic factors [1]. Herein, we report physical measurements on the transport properties of the Li 1 . 3 Mo 2 0 4 , Li 2 Mo204, and Li0.5(H 2 0) 1 . 3 Mo 2 0 4 phases.
EXPERIMENTAL The Lij. 3 Mo20 4 phase was prepared by ionic exchange of Na by Li in Nal. 3 Mo 2 0 4 and Li 2 Mo 2 0 4 was obtained by reaction of Lij. 3 M020 4 in a solution composed of an excess of 1.6M n-butyl lithium in hexane, as described previously [1]. The hydrated phase Li 0 . 5 (H 2 0)1. 3 Mo 2 O4 was obtained by immersing the Li.. 3 M020 4 phase into distilled water, and held in it for about two weeks [1,4]. All the phases were Mat. Res. Soc. Symp. Proc. Vol. 210. @1991 Materials Research Society
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identified and NMR elsewhere
by x-ray electrical [5].
The diffraction. will measurements
7
Li
state solid described be
I I
p.
A I.
20
10
0
-10
-20
V (kM)
-20
0
-10 V
Figure
1:
(a) (b)
RESULTS
AND
10
20
(kHz)
7
Li NMR spectra of the Lithium phases. Temperature dependance of the width of 7 Li NMR signal for the lithium the hydrated phase.
DISCUSSION
7 NMR for the Li solid state we present the First, (Figure Li 1 . 3 Mo20 4 , Li 2 Mo20 4 and lithium hydrated phases similar the spectrum is la). For the Lij. 3 Mo20 4 phase, to a standard quadrupole spectrum for a nucleus with suggests line The symmetry of the central spin 3/2. for the Li ions the existence of only one type of site the narrowness of addition, In composition. for this line indicates rapid motion for the central transition spectrum broad the In contrast, ions. the lithium not allow the phase does Li 2 MO20
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