Si anodes for Li-ion batteries are notorious for their
large volume
expansion during lithiation and the corresponding detrimental effects
on cycle life. However, calendar life is the primary roadblock for
widespread adoption. During calendar life aging, the main origin of
impedance increase and capacity fade is attributed to the instability
of the solid electrolyte interphase (SEI). In this work, we use ex
situ nano-Fourier transform infrared spectroscopy and X-ray photoelectron
spectroscopy to characterize the structure and composition of the
SEI layer on amorphous Si thin films after an accelerated calendar
aging protocol. The characterization of the SEI on non-washed and
washed electrodes shows that brief washing in dimethyl carbonate results
in large changes to the film chemistry and topography. Detailed examination
of the non-washed electrodes during the first lithiation and after
an accelerated calendar aging protocol reveals that PF6
– and its decomposition products tend to accumulate
in the SEI due to the preferential transport of PF6
– ions through polyethylene oxide-like species in the
organic part of the SEI layer. This work demonstrates the importance
of evaluating the SEI layer in its intrinsic, undisturbed form and
new strategies to improve the passivation of the SEI layer are proposed.
Financial decisions play a critical role in today's enterprise financial management activities. Therefore, the study of financial decision support system (FDSS) is of great significance since the right business decisions can greatly improve the enterprise decision effects. Considering the above issue, we present a framework for the financial decision support system in this paper.
In this work, we study the ablation dynamics of copper (Cu) induced by single fs pulse and fs GHz bursts using in situ multimodal diagnostics; time-resolved scattering imaging, emission imaging, and optical emission spectroscopy. Multimodal probing techniques reveal that fs GHz bursts rapidly remove molten liquid Cu from the irradiated spot due to the recoil pressure exerted by following fs pulses. Material ejection stops after burst irradiation due to the limited amount of remnant matter, combined with the suppressed heat conduction into the target material. Our work provides insights into the complex ablation mechanisms of GHz fs bursts, which are critical in selecting optimal laser conditions in cross-cutting processing and micro/nano-fabrication applications.
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