THIN FILM LITHIUM ION CONDUCTING LiBSO
SOLID ELECTROLYTE
a,b
Li2SO4
A. Levasseur et al.
Solid State Comm.(1971)
Terai et al.
Glasstech. Ber.(1990)
a
a
K.-H. Joo* , P. Vinatier , B. Pecquenard ,
Kamitsosi et al.
J. Non-Cryst. Solids(1996)
A. Levasseura, H.-J. Sohnb
a
ENSCPB, University Bordeaux I, 16, Avenue Pey
a
Berland, Pessac, France.
b
c
b
e
School of Materials Science and Engineering, Seoul
d
National University, 151-742, Seoul, South Korea.
Li2O
B2O3
With technological target to improve ionic
conductivity, lithium borate glasses have been intensively
Fig. 1. Vitreous domain of B2O3-Li2O-Li2SO4 ternary
studied during recent years as lithium ion conducting
system.
electrolytes for solid state lithium batteries [1-2]. In this
studies,
thin
film
(1-x)[0.5Li2O-0.5B2O3]-xLi2SO4
electrolyte (LiBSO) was fabricated by rf magnetron
a
previous study
(a) B 2O3, 0.71 Li2O, 1.1 Li2SO 4
(b) B 2O3, 0.71 Li2O, 0.42 Li2SO 4
(c) B 2O 3, 0.57 Li2O, 0.42 Li2SO 4
(d) B 2O3, 0.57 Li2O, 0.28 Li2SO 4
(e) B 2O3, 0.57 Li2O, 0.14 Li2SO 4
in this research
(A) B 2O 3, 1.00 Li2O, 1.33 Li2SO 4
(B) B 2O 3, 1.00 Li2O, 2.00 Li2SO 4
(C) B 2O 3, 1.00 Li2O, 3.00 Li2SO 4
(D) B 2O 3, 1.00 Li2O, 4.67 Li2SO 4
(E) B 2O 3, 1.00 Li2O, 8.00 Li2SO 4
-8
sputtering technique, using targets prepared from LiBO2
and Li2SO4 mixed powder of various molar ratios
-9
(x=0.4~0.8). The main objective of the study is to widen
-10
the vitreous domain (Fig. 1) to a regime containing higher
-11
amount of lithium, resulting in the enhancement of ionic
conductivity.
thermally activated behavior, as illustrated in Fig. 2. σionDC
lnσ (S/cm)
According to the frequency response analysis,
lithium ion conductivities of thin films (σionDC) show
-12
increases up to x = 0.7, due to an increase of the number
-13
-14
D
E
C
B
A
-15
of charge carriers. As x increases further (x = 0.8),
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conductivity decreases and Ea increases again. In this case,
the exponent of power law is above 1 from the AC
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conductivity plot (Fig. 3), which is not normal case for
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glassy conductors [3]. TEM observation indicates the
a
b
c
d
e
-19
different microstructure for the case of x=0.8. These facts
2.8 2.8 2.9 3.0 3.1 3.2 3.3 3.3 3.4 3.5 3.6 3.7
3
10 /T(K)
imply that lithium ion conducting mechanism is different
a
: A. Levasseur et al. Solid State Communications, vol 32, 1979
in Li2SO4 richer compositions. From FTIR results, as the
amount of lithium sulfate increases, the relative peak
Fig. 2. Arrhenius plots of LiBSO thin films of all
intensities of SO42- vibration and borate tetrahedra
compositions, compared with the previous work.
increase, which agrees with the other previous results [4].
The microstructure was investigated by NEXAFS method.
1E-4
Thin film LiBSO electrolytes have improved
are promising candidates for microbatteries.
References
[1] A. Levasseur, J.C. Brethous, J.M. Reau, P.
AC Conductivity S/cm
ionic conductivity in the extended vitreous domain and
1E-5
25
30
35
40
52
55
63
70
85
90
Hagenmuller, Mater. Res. Bull. 14 (1979) 921
[2] T. Minami, J. Non. Cyrst. Solid 95&96 (1987) 107
1E-6
1000
Ionics 51 (1992) 15
[4] G.D. Chryssikos, E.I. Kamitsos, A.P. Patsis, J. NonCrystalline Solids, 202 (1996) 222
10000
100000
1000000
1E7
Frequency Hz
[3]. B. Roling, T. Lauxtermann, F. Funke Solid State
Fig. 3. AC conductivity plots of x=0.8 at different
temperatures, fitted to single exponent power law
equation