Browsing by Author "Ren, Yang"

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    In Situ and Operando Investigation of the Dynamic Morphological and Phase Changes of Selenium-doped Germanium Electrode during (De)Lithiation Processes
    (RSC, 2020-01) Li, Tianyi; Lim, Cheolwoong; Cui, Yi; Zhou, Xinwei; Kang, Huixiao; Yan, Bo; Meyerson, Melissa L.; Weeks, Jason A.; Liu, Qi; Guo, Fangmin; Kou, Ronghui; Liu, Yuzi; De Andrade, Vincent; De Carlo, Francesco; Ren, Yang; Sun, Cheng-Jun; Mullins, C. Buddie; Chen, Lei; Fu, Yongzhu; Zhu, Likun; Mechanical and Energy Engineering, School of Engineering and Technology
    To understand the effect of selenium doping on the good cycling performance and rate capability of a Ge0.9Se0.1 electrode, the dynamic morphological and phase changes of the Ge0.9Se0.1 electrode were investigated by synchrotron-based operando transmission X-ray microscopy (TXM) imaging, X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The TXM results show that the Ge0.9Se0.1 particle retains its original shape after a large volume change induced by (de)lithiation and undergoes a more sudden morphological and optical density change than pure Ge. The difference between Ge0.9Se0.1 and Ge is attributed to a super-ionically conductive Li–Se–Ge network formed inside Ge0.9Se0.1 particles, which contributes to fast Li-ion pathways into the particle and nano-structuring of Ge as well as buffering the volume change of Ge. The XRD and XAS results confirm the formation of a Li–Se–Ge network and reveal that the Li–Se–Ge phase forms during the early stages of lithiation and is an inactive phase. The Li–Se–Ge network also can suppress the formation of the crystalline Li15Ge4 phase. These in situ and operando results reveal the effect of the in situ formed, super-ionically conductive, and inactive network on the cycling performance of Li-ion batteries and shed light on the design of high capacity electrode materials.
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    A practical phosphorus-based anode material for high-energy lithium-ion batteries
    (Elsevier, 2020-08) Amine, Rachid; Daali, Amine; Zhou, Xinwei; Liu, Xiang; Liu, Yuzi; Ren, Yang; Zhang, Xiaoyi; Zhu, Likun; Al-Hallaj, Said; Chen, Zonghai; Xu, Gui-Liang; Amine, Khalil; Mechanical and Energy Engineering, School of Engineering and Technology
    State-of-the-art lithium-ion batteries cannot satisfy the increasing energy demand worldwide because of the low specific capacity of the graphite anode. Silicon and phosphorus both show much higher specific capacity; however, their practical use is significantly hindered by their large volume changes during charge/discharge. Although significant efforts have been made to improve their cycle life, the initial coulombic efficiencies of the reported Si-based and P-based anodes are still unsatisfactory (<90%). Here, by using a scalable high-energy ball milling approach, we report a practical hierarchical micro/nanostructured P-based anode material for high-energy lithium-ion batteries, which possesses a high initial coulombic efficiency of 91% and high specific capacity of ~2500 mAh g−1 together with long cycle life and fast charging capability. In situ high-energy X-ray diffraction and in situ single-particle charging/discharging were used to understand its superior lithium storage performance. Moreover, proof-of-concept full-cell lithium-ion batteries using such an anode and a LiNi0.6Co0.2Mn0.2O2 cathode were assembled to show their practical use. The findings presented here can serve as a good guideline for the future design of high-performance anode materials for lithium-ion batteries.
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    A Self-Healing Liquid Metal Anode with PEO-Based Polymer Electrolytes for Rechargeable Lithium Batteries
    (Elsevier, 2020-12) Li, Tianyi; Cui, Yi; Fan, Longlong; Zhou, Xinwei; Ren, Yang; De Andrade, Vincent; De Carlo, Francesco; Zhu, Likun; Mechanical and Energy Engineering, School of Engineering and Technology
    Ga-Sn liquid metal material is demonstrated as a self-healing anode system due to its fluidity via operando synchrotron-based transmission X-ray microscopy and X-ray diffraction experiments. Cracks formed due to volume expansions can be recovered by the fluidity of the liquid metals. By incorporating with a poly(ethylene oxide) (PEO)-based electrolyte at 60 °C, the Ga-Sn anode shows a reversible lithium insertion and extraction process with a high initial discharge specific capacity of 682 mAh g − 1, followed by delivering a capacity of 462 mAh g − 1 in the second cycle at C/20 rate. Compared with its solid counterparts, the Ga-Sn liquid metal anode demonstrates a better capability to maintain its mechanical integrity and better contact with PEO solid electrolytes due to its advantageous features of the liquid. This study suggests a potential strategy to use liquid metal alloys with polymer solid electrolyte to solve the challenges in rechargeable lithium batteries.