Browsing by Author "Jin, Yang"

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    Blade-Type Reaction Front in Micrometer-Sized Germanium Particles during Lithiation
    (ACS, 2020-09) Zhou, Xinwei; Li, Tianyi; Cui, Yi; Meyerson, Melissa L.; Weeks, Jason A.; Mullins, C. Buddie; Jin, Yang; Shin, Hosop; Liu, Yuzi; Zhu, Likun; Mechanical and Energy Engineering, School of Engineering and Technology
    To investigate the lithium transport mechanism in micrometer-sized germanium (Ge) particles, in situ focused ion beam–scanning electron microscopy was used to monitor the structural evolution of individual Ge particles during lithiation. Our results show that there are two types of reaction fronts during lithiation, representing the differences of reactions on the surface and in bulk. The cross-sectional SEM images and transmission electron microscopy characterizations show that the interface between amorphous LixGe and Ge has a wedge shape because of the higher Li transport rate on the surface of the particle. The blade-type reaction front is formed at the interface of the amorphous LixGe and crystalline Ge and is attributed to the large strain at the interface.
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    Operando study of mechanical integrity of high-volume expansion Li-ion battery anode materials coated by Al2O3
    (IOP, 2023-06) Zhou, Xinwei; Stan, Liliana; Hou, Dewen; Jin, Yang; Xiong, Hui; Zhu, Likun; Liu, Yuzi; Mechanical and Energy Engineering, Purdue School of Engineering and Technology
    Group IV elements and their oxides, such as Si, Ge, Sn and SiO have much higher theoretical capacity than commercial graphite anode. However, these materials undergo large volume change during cycling, resulting in severe structural degradation and capacity fading. Al2O3 coating is considered an approach to improve the mechanical stability of high-capacity anode materials. To understand the effect of Al2O3 coating directly, we monitored the morphology change of coated/uncoated Sn particles during cycling using operando focused ion beam–scanning electron microscopy. The results indicate that the Al2O3 coating provides local protection and reduces crack formation at the early stage of volume expansion. The 3 nm Al2O3 coating layer provides better protection than the 10 and 30 nm coating layer. Nevertheless, the Al2O3 coating is unable to prevent the pulverization at the later stage of cycling because of large volume expansion.