THESIS
2021
1 online resource (xiv, 144 pages) : illustrations (some color)
Abstract
Solid-state battery is considered as one of the most promising energy storage devices that
can significantly improve the safety and environmental friendliness of batteries. However,
the large-scale application of solid-state battery is still hindered by the relatively low ionic
conductivity of electrolyte and high interfacial resistance between electrolyte and
electrode.
In this study, the major effort is made in the conductivity improvement and interfacial
modification of Li
6·
4La
3Zr
1·4Ta
0·6O
12 (LLZTO) ceramic solid electrolyte. To improve the
conductivity of the electrolyte pellet, the protocols of LLZTO powder synthesis and pellet
preparation are systematically studied. The calcination temperature of LLZTO powder is
significantly reduced to 600 ℃ and still maintain good ionic conducti...[
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Solid-state battery is considered as one of the most promising energy storage devices that
can significantly improve the safety and environmental friendliness of batteries. However,
the large-scale application of solid-state battery is still hindered by the relatively low ionic
conductivity of electrolyte and high interfacial resistance between electrolyte and
electrode.
In this study, the major effort is made in the conductivity improvement and interfacial
modification of Li
6·
4La
3Zr
1·4Ta
0·6O
12 (LLZTO) ceramic solid electrolyte. To improve the
conductivity of the electrolyte pellet, the protocols of LLZTO powder synthesis and pellet
preparation are systematically studied. The calcination temperature of LLZTO powder is
significantly reduced to 600 ℃ and still maintain good ionic conductivity (1.05 × 10
−3
S/cm at 30 °C). CO
2 is utilized for the surface treatment of LLZTO particles to in situ
generate a Li
2CO
3 layer that can serve as the sintering aid to densify LLZTO pellet. By
improving the sinterability of LLZTO powder and avoiding the contaminations during
sintering, LLZTO pellets with ideal microstructures are prepared. With interfacial
modification using low melting point glass, The LLZTO based full cell achieves a high
capacity of 144 mAh/g and high capacity retention of ~96% after 100 cycles. Effort is
also made to improve the poly(ethylene oxide) (PEO) based composite solid electrolyte
by adding H
2SO
4 treated TiO
2 nanowire in PEO matrix. The high polarity of treated TiO
2
nanowire can dissociate the lithium salt in PEO leading to improved conductivity of ~1.19
× 10
−4 S/cm at 30 °C and improved battery performance of 144 mAh/g with retention of
74.5% after 800 cycles.
This study provides new methods to improve the conductivity and reduce interfacial
resistance of solid electrolyte which adds new insights into the development of solid-state batteries.
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