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Nascent SEI-Surface Films on Single Crystalline Silicon Investigated by Scanning Electrochemical Microscopy
摘要： Silicon is a promising high capacity host material for negative electrodes in lithium-ion batteries with low potential for the lithiation/delithiation reaction that is outside the stability window of organic carbonate electrolytes. Thus, the use of such electrodes critically depends on the formation of a protective solid electrolyte interphase (SEI) from the decomposition products of electrolyte components. Due to the large volume change upon charging, exposure of the electrode material to the electrolyte must be expected, and facile re-formation of SEI is a scope for improving the stabilities of such electrodes. Here, we report the formation of incipient SEI layers on monocrystalline silicon by in-situ imaging of their passivating properties using scanning electrochemical microscopy after potentiodynamic charging to different final potentials. The images show a local initiation of the SEI growth at potentials of around 1.0 V vs. Li/Li+ in 1 M LiClO4 in propylene carbonate.
关键词： silicon electrode,single crystalline electrode,solid electrolyte interphase,scanning electrochemical microscopy,incremental charging
更新于2025-09-19 17:15:36
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Impact of Plasmonic Photothermal Effects on the Reactivity of Au Nanoparticle Modified Graphene Electrodes Visualized Using Scanning Electrochemical Microscopy
摘要： Atomically-thin graphene electrodes enable the modulation of interfacial reactivity by means of underlying substrate effects. Here we show that plasmonic excitation of microscopic arrays composed of 50 nm Au nanoparticles situated underneath a graphene interface results in localized enhancements on the electrochemical readout. We used scanning electrochemical microscopy (SECM) in the feedback and H2O2 collection modes to identify the role of the generated plasmons on the electrochemical response. Using electrochemical imaging, supported by finite-element method simulations, we confirmed that a temperature rise of up to ~30 K was responsible for current enhancements observed for mass transfer-limited reactions. On single-layer graphene (SLG) we observed a shift in the onset of H2O2 generation which we traced back to photothermal induced kinetic changes, raising ko’ from 1.1 x 10-8 m/s to 2.2 x 10-7 m/s. Thicker 10-layer graphene electrodes displayed only a small kinetic difference with respect to SLG, suggesting that photothermal processes, in contrast to hot carriers, are the main contributor to the observed changes in interfacial reactivity upon illumination. SECM is demonstrated to be a powerful technique for elucidating thermal contributions to reactive enhancements, and presents a convenient platform for studying temperature-dependent phenomena over individual sites on electrodes.
关键词： scanning electrochemical microscopy,graphene electrodes,plasmonic photothermal effects,Au nanoparticle,electrochemical reactivity
更新于2025-09-19 17:13:59