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Abstract: The effectiveness of silicon carbide (SiC) nanowires (NW) as electrode material for micro-supercapacitors has been investigated. SiC NWs are grown on a SiC thin film coated with a thin Ni catalyst layer via a chemical vapor deposition route at 950 °C. A specific capacitance in the range of ∼240 μF cm−2 is demonstrated, which is comparable to the values recently reported for planar micro-supercapacitor electrodes. Charge–discharge studies demonstrate the SiC nanowires exhibit exceptional stability, with 95% capacitance retention after 2 × 105 charge/discharge cycles in an environmentally benign, aqueous electrolyte. [Copyright &y& Elsevier]

The development of passivated silicon nanowire (SiNW) based micro-supercapacitor electrodes for on-chip applications using an environmentally benign aqueous electrolyte is reported. The SiNWs, produced by low-temperature (50 °C) electrochemical etching, corrode during charge/discharge cycling in the aqueous environment, but upon coating with a silicon carbide passivation layer, the corrosion is mitigated. The as-formed materials are in electrical contact with the substrate, requiring no additional current collector. The passivated NWs achieve capacitance values up to ∼1.7 mF/cm2 projected area (comparable to state-of-the art carbon based micro-supercapacitor electrodes), exhibit robust cycling stability, and maintain capacitive behavior over a wide range of charge/discharge rates. [ABSTRACT FROM AUTHOR]

Silicon is a promising material for high-energy anode materials for the next generation of lithium-ion batteries. The gain in specific capacity depends highly on the quality of the Si dispersion and on the size and shape of the nano-silicon. The aim of this study is to investigate the impact of the size/shape of Si on the electrochemical performance of conventional Li-ion batteries. The scalable synthesis processes of both nanoparticles and nanowires in the 10–100 nm size range are discussed. In cycling lithium batteries, the initial specific capacity is significantly higher for nanoparticles than for nanowires. We demonstrate a linear correlation of the first Coulombic efficiency with the specific area of the Si materials. In long-term cycling tests, the electrochemical performance of the nanoparticles fades faster due to an increased internal resistance, whereas the smallest nanowires show an impressive cycling stability. Finally, the reversibility of the electrochemical processes is found to be highly dependent on the size/shape of the Si particles and its impact on lithiation depth, formation of crystalline Li15Si4 in cycling, and Li transport pathways. [ABSTRACT FROM AUTHOR]