Scholarly Works, Academy of Integrated Science

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Browsing Scholarly Works, Academy of Integrated Science by Author "Academy of Integrated Science"

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    The origin of impedance rise in Ni-Rich positive electrodes for lithium-ion batteries
    Lee, Rung-Chuan; Franklin, Joseph; Tian, Chixia; Nordlund, Dennis; Doeff, Marca M.; Kostecki, Robert (2021-06-30)
    The cycling performance of nickel-rich lithium nickel cobalt manganese oxide (NMC) electrodes in Li-ion batteries (LIBs) partially depends on the control of the kinetics of degradation processes that result in impedance rise. The impedance contribution from surface film formation at the NMC/electrolyte interfaces is highly dependent on the initial chemical composition and the structure of the NMC surfaces. Through comparison of film quantity and electrochemical performance of composite electrodes made of pristine- and surface treated-NMC materials, we are able to demonstrate that a simple surface treatment suppressed the subsequent film formation and reduced impedance rise of the Li/NMC half-cells during cycling. Detailed modelling of factors affecting cell impedance provide further insights to index individual interphase resistance, highlighting the underlying positive effects of the proposed surface treatment, and demonstrating the importance of homogeneous, electronically conducting matrices throughout the composite electrode.
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    Structure-preserving interpolation of bilinear control systems
    Benner, Peter; Gugercin, Serkan; Werner, Steffen W. R. (2021-06)
    In this paper, we extend the structure-preserving interpolatory model reduction framework, originally developed for linear systems, to structured bilinear control systems. Specifically, we give explicit construction formulae for the model reduction bases to satisfy different types of interpolation conditions. First, we establish the analysis for transfer function interpolation for single-input single-output structured bilinear systems. Then, we extend these results to the case of multi-input multi-output structured bilinear systems by matrix interpolation. The effectiveness of our structure-preserving approach is illustrated by means of various numerical examples.