In situ observed electrodeposition and dissolution of lithium dendrite of commercial graphite electrode.

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Using first-principles calculations, the electronic structures and electron transport properties of zigzag and armchair O-functionalized Ti2C MXene nanoribbons are examined in this work. We demonstrate that the energy gaps in patterned Ti2CO2 nanoribbons can be tuned by appropriate designs of crystallographic orientation and widths. The Ti2CO2 nanoribbons along the zigzag direction with width parameter larger than six show zero or very low band gaps, while band gaps are opened for Ti2CO2 nanoribbons with armchair-shaped edges. The electronic transport properties for the devices of Ti2CO2 nanoribbons with various widths are investigated using nonequilibrium Green’s functions, and the current–voltage characteristics of the devices are predicted. The current calculations reveal that some of these devices may have a nonlinear feature as well as negative differential resistance behaviors. The zigzag and armchair Ti2CO2 nanoribbon devices show different current–voltage curves. There are onset biases for armchair Ti2CO2 nanoribbons so that the current is generated due to the band gaps but not for most of the zigzag nanoribbons. The corresponding mechanisms for the variation of electronic band gaps and electronic transport properties are discussed. Based on their excellent carrier mobilities reported for the Ti2CO2 MXene and the negative differential resistance effect found in this work, the Ti2CO2 nanoribbon systems might find promising applications in nanoelectronic devices.

The cure kinetics of an epoxy resin used for the preparation of advanced polymeric composite structures was studied by isothermal differential scanning calorimetry (DSC). A series of isothermal DSC runs provided information about the kinetics of cure over a wide temperature range. According to the heat evolution behavior during the curing process, several influencing factors of isothermal curing reactions were evaluated. The results showed that the isothermal kinetic reaction of this epoxy resin followed an autocatalytic kinetic mechanism. In the latter reaction stage, the curing reaction became controlled mainly by diffusion. Cure rate was then modeled using a modified Kamal autocatalytic model that accounts for the shift from a chemically controlled reaction to a diffusion‐controlled reaction. The model parameters were determined by a nonlinear multiple regression method. Copyright © 2004 Society of Chemical Industry

The functionality and reliability of the current collector (CC) are crucial to design and fabricate electrodes for Li-ion batteries because the CC serves as the bridge between external electronic and internal Li-ion transports. Therefore, understanding the mechanical behavior of CCs is of great importance for battery design and manufacturing. In this paper, we report the measured values of the elastic moduli of six commercial copper current-collector (CCC) foils. Measurements were performed using three techniques: a standard microtensile testing machine equipped with a laser sensor, dynamic mechanical analysis (DMA), and nanoindentation. For electrolytic copper (E-Cu) foils, we find elastic moduli of approximately 70 GPa, and for rolled copper (R-Cu) foils, we find elastic moduli of approximately 50 GPa. Values for yield strength and fracture strength of the foils were determined from load-deflection curves; the results are consistent with values recommended by the manufacturer. Crystalline structures, which influence values for the elastic moduli of the foils, were investigated by X-ray diffraction. Surface morphologies of the foils before testing and the fracture morphologies after testing were studied by scanning electron microscopy. Figure 4 Yield strength of CCC foils as a function of thickness Figure 5 Fracture strength of CCC foils as a function of thickness. The inset is the real picture of sample after microtensile test.