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  • Küçük Resim
    Öğe
    Engineering self-standing Si-Mo-O based nanostructure arrays as anodes for new era lithium-ion batteries
    (Springer, 2019) Karahan, Billur Deniz; Amine, Khalil
    For the first time, Si-Mo-O helices have been produced by the ion-assisted glancing angle electron beam co-evaporation of molybdenum oxide and silicon. Since the electron beam evaporation process forms metastable particles through the dissociation of the source material, a film that contains compounds of different combinations of molybdenum, silicon, and oxygen atoms is produced. This complex structure's lithiation mechanism is different from that of the traditional electrodes in lithium-ion batteries. In the paper, the nanostructured Si-Mo-O anode was cycled in different potential windows (0.2-1.2V, 0.2-3.0V, 5mV-3.0V vs. lithium) at different rates. The anode remained cycling even at 0.7mAcm (-2), which makes it practical for micro- and solid-state battery applications. This research reveals that by adjusting the cutoff voltages, different particles could be activated in the anode structure to react with lithium, resulting in different performances. The electrode delivers higher capacity when cycled between 5mV and 3.0V windows and keeps cycling for 200 cycles under the load of 5 mu Acm(-2). This performance is believed to be related to the structural, morphological, and the compositional properties of the coating. [GRAPHICS].
  • Küçük Resim
    Öğe
    Superlattice-structured films by magnetron sputtering as new era electrodes for advanced lithium-ion batteries
    (Elsevier, 2020) Keleş, Özgül; Karahan, Billur Deniz; Eryılmaz, Levent; Amine, Rachid; Abouimrane, Ali; Chen, Zonghai; Zuo, Xiaobing; Zhu, Zihua; Al-Hallaj, Said; Amine, Khalil
    Sustaining a sound structure in Si-based anodes is extremely challenging because of the high volumetric expansion that occurs upon cycling. To maintain capacity retention during the cycling, there is a need for new designs that rely on engineering-specific hierarchical geometries and/or optimized composite compositions such that at least one of the multiple elements serves as buffer and/or electron conductive pathway in the electrodes. Here, we report an innovative design in which alternate layers of atomic structures involving multiple elements form a new anode material for lithium-ion batteries.In this work, a superlattice-structured film containing Si, Mo, and Cu is fabricated by a simple and scalable magnetron sputtering process for the first time. With the help of the formation of a continuous and repetitive superlattice along the film thickness, a homogeneous stress-strain distribution is attained. In our superlattice thin film, the Si atoms are distributed along the film thickness within the alternate Mo-Cu layers, which act as inactive-conductive layers and as a backbone web to handle the volume expansion of active Si while restricting electrochemical agglomeration. This nano-functional superlattice approach enables harnessing the high energy density of Si while maintaining its structural stability. As a result, the electrode exhibits high energy density and capacity retention even at high cycling rates. The possible use of the film in a full cell is also evaluated using LiMn1.5Ni0.5O4 cathodes. The full cell maintained a stable capacity of about 900 mAh g(anode)(-1) (similar to 93 mA g(cathode)(-1)) over 150 cycles at the similar to 600 mA g(-1) rate.The remarkable performance of this nanostructured, multifunctional superlattice film is found to be promising for applications that require high energy, long calendar life, and excellent abuse tolerance, such as electric vehicle batteries.