phase formation in alloy-type lithium storage anode ... filesi and sn can take up much more li,...
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![Page 1: Phase formation in alloy-type lithium storage anode ... fileSi and Sn can take up much more Li, different Li insertion mechanism volume expansion up to 300% still graphite used battery-related](https://reader033.vdocuments.us/reader033/viewer/2022041415/5e1b37003b114e653168d18e/html5/thumbnails/1.jpg)
TU Clausthal FSU Jena Beijing UT
TU Clausthal FSU Jena Beijing UT
M. Drüe1, A. Kozlov2, M. Seyring1, X. Song3, R. Schmid-Fetzer2, M. Rettenmayr1
JP09: Phase stability of alloy-type lithium storage anode materials
Phase formation in alloy-type lithium storage
anode materials with C, Si and Sn
1Otto-Schott-Institut für Materialforschung, Friedrich-Schiller-Universität Jena
2Institut für Metallurgie, Technische Universität Clausthal
3School of Materials Science and Engineering, Beijing University of Technology
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TU Clausthal FSU Jena Beijing UT
electrode materials must be able to take up lithium
anode: graphite LiC6
improvement of capacity, charging time etc. needed
Motivation: Lithium Ion Battery
2
M. Winter et al., Adv. Mat. 10 (1998)
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TU Clausthal FSU Jena Beijing UT
Si and Sn can take up much more Li, different Li insertion mechanism
volume expansion up to 300% still graphite used
battery-related properties strongly depend on thermodynamic data phase diagram
Anode Materials: Alternatives
3
M.N. Obrovac et al., J. Eletrochem. Soc. 154 (2007)
Sn
C
Si
Li JP 09:
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TU Clausthal FSU Jena Beijing UT
combined approach of DSC, long-term annealing and XRD
Li2C2 is the only stable phase in the Li-C phase diagram, LiC6 decomposes during annealing
re-assessment of the Li-C phase diagram (TUC)
Anode Materials: Alternatives
4
Sn
C
Si
Li
JP 09:
M. Drüe et al., J. All. Comp. 575 (2013)
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TU Clausthal FSU Jena Beijing UT
Si-C
Binary phase diagrams
5
Li1
7Si
4
good assessment of binary systems
investigation of the ternary phase diagram needed
Li-C Li-Si
A. Kozlov et al. Int. J. Mat Res. 101 (2013) P. Wang et al. Intermetallics 42 (2013) S. Kawanishi et al. Mat. Trans. 50 (2009)
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TU Clausthal FSU Jena Beijing UT
two key compositions chosen, according to preliminary calculations 1: LiSiC 2: Li68Si25C7
DSC and long-term annealing experiments
adjustment of compositions is complicated starting materials: binary compounds
Selection of alloy compositions
6
Li13Si4+SiC+Li2C2
25°C SiC Li2C2
Li12Si7
Li17Si4
Li13Si4+SiC
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TU Clausthal FSU Jena Beijing UT
Ar-filled Glovebox (O2, H2O<2ppm)
compressing of pure elements to pellets, subsequent annealing • Li+C or Li+Si Li2C2, Li12Si7, Li17Si4
XRD analysis air-tight capsule
Synthesis and characterization of Li-alloys
7
Li2C2
Li12Si7
Li17Si4
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TU Clausthal FSU Jena Beijing UT
binary pre-alloys for adjustment of ternary compositions: Li2C2, Li12Si7, Li17Si4
Synthesis and characterization of Li-alloys
8
mixed in the chosen compositions for DSC and compressed to pellets for long-term annealing
subsequent XRD analysis
Li2C2
Li12Si7
Li17Si4
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TU Clausthal FSU Jena Beijing UT
DSC measurements
Composition 1: LiSiC
9
α-SiC + Li12Si7 + Li2C2
fabrication of pellets
annealing: 650°C, 96h Li7Si3?
Li13Si4+SiC+Li2C2?
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TU Clausthal FSU Jena Beijing UT
Composition 1: LiSiC
10
α-SiC + Li12Si7 + Li2C2
α-SiC + Li17Si4 + Li2C2
fabrication of pellets
annealing: 650°C, 96h
annealing: 630°C, 96h
Li7Si3, Li2C2 and SiC can be identified no Li13Si4?
Li13Si4+SiC+Li2C2?
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TU Clausthal FSU Jena Beijing UT
Composition 2: Li68Si25C7
11
Li2C2 + Li12Si7 + Li17Si4
DSC measurements
Li7Si3
Li13Si4+SiC?
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TU Clausthal FSU Jena Beijing UT
fabrication of pellets
annealing: 630°C, 96h
Composition 2: Li68Si25C7
12
Li2C2 + Li12Si7 + Li17Si4
phases identified: Li7Si3, Li2C2, little SiC (?) no Li13Si4!
Li13Si4+SiC?
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TU Clausthal FSU Jena Beijing UT
first approach to investigate ternary system Li-Si-C
no ternary phases
three-phase equilibrium identified
Li7Si3 has formed during all experiments equilibrium at the studied compositions contains Li7Si3 instead of Li13Si4
Conclusion
13
Li7Si3+SiC+Li2C2
25°C Li13Si4+SiC+Li2C2?
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TU Clausthal FSU Jena Beijing UT
Joint project JP 09
information about phase stabilities insufficient
sensitive Li-alloys have to be handled under protective gas (no H2O, O2, N2)
C
Sn
Si
Li
alloy fabrication
FSU Jena TU Clausthal Beijing UT
annealing experiments
microstructure characterization (XRD, LM, SEM, TEM)
thermodynamic data (DSC) nanostructuring (SPS)
phase diagrams (CALPHAD) modeling of nc-Li-alloys
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TU Clausthal FSU Jena Beijing UT
Li-C: pure samples of LiC6 and Li2C2, DSC (TUC) and long-term annealing
Li2C2 is the only stable phase in the Li-C phase diagram, LiC6 decomposes during annealing
Synthesis and phase diagram: Li-C
[Kozlov2013]
re-assessment of the Li-C phase diagram (TUC)
[Okamoto1989]