The construction of lightweight, flexible and stretchable power systems for modern electronic devices without using elastic polymer substrates is critical but remains challenging. We have developed a new and general s...
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The construction of lightweight, flexible and stretchable power systems for modern electronic devices without using elastic polymer substrates is critical but remains challenging. We have developed a new and general strategy to produce both freestanding, stretchable, and flexible supercapacitors and lithium‐ion batteries with remarkable electrochemical properties by designing novel carbon nanotube fiber springs as electrodes. These springlike electrodes can be stretched by over 300 %. In addition, the supercapacitors and lithium‐ion batteries have a flexible fiber shape that enables promising applications in electronic textiles.
Electrically conducting wires play a critical role in the advancement of modern electronics and in particular are an important key to the development of next‐generation wearable microelectronics. However, the thin co...
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Electrically conducting wires play a critical role in the advancement of modern electronics and in particular are an important key to the development of next‐generation wearable microelectronics. However, the thin conducting wires can easily break during use, and the whole device fails to function as a result. Herein, a new family of high‐performance conducting wires that can self‐heal after breaking has been developed by wrapping sheets of aligned carbon nanotubes around polymer fibers. The aligned carbon nanotubes offer an effective strategy for the self‐healing of the electric conductivity, whereas the polymer fiber recovers its mechanical strength. A self‐healable wire‐shaped supercapacitor fabricated from a wire electrode of this type maintained a high capacitance after breaking and self‐healing.
The nature of ordering in dilute dipolar interacting systems dates back to the work of Debye and is one of the most basic, oldest and as-of-yet unsettled problems in magnetism. While spin-glass order is readily observ...
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The nature of ordering in dilute dipolar interacting systems dates back to the work of Debye and is one of the most basic, oldest and as-of-yet unsettled problems in magnetism. While spin-glass order is readily observed in several RKKY-interacting systems, dipolar spin glasses are the subject of controversy and ongoing scrutiny, e.g., in LiHoxY1−xF4, a rare-earth randomly diluted uniaxial (Ising) dipolar system. In particular, it is unclear if the spin-glass phase in these paradigmatic materials persists in the limit of zero concentration or not. We study an effective model of LiHoxY1−xF4 using large-scale Monte Carlo simulations that combine parallel tempering with a special cluster algorithm tailored to overcome the numerical difficulties that occur at extreme dilutions. We find a paramagnetic to spin-glass phase transition for all Ho+ ion concentrations down to the smallest concentration numerically accessible, 0.1%, and including Ho+ ion concentrations that coincide with those studied experimentally up to 16.7%. Our results suggest that randomly diluted dipolar Ising systems have a spin-glass phase in the limit of vanishing dipole concentration, with a critical temperature vanishing linearly with concentration. The agreement of our results with mean-field theory testifies to the irrelevance of fluctuations in interactions strengths, albeit being strong at small concentrations, to the nature of the low-temperature phase and the functional form of the critical temperature of dilute anisotropic dipolar systems. Deviations from linearity in experimental results at the lowest concentrations are discussed.
Complex oxides such as transition metal perovskites, particularly ABO 3 perovskites of the type ABO3 (A=La, B= transition metal, O=oxygen) are promising catalysts for the aqueous oxygen reduction reaction (ORR), with ...
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A model is implemented that captures the dynamic nanoindentation response of a viscoelastic material. Indenter tip-sample contact forces are modeled using a generalized Maxwell model. Further, this model is used to de...
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ISBN:
(纸本)9781482205848
A model is implemented that captures the dynamic nanoindentation response of a viscoelastic material. Indenter tip-sample contact forces are modeled using a generalized Maxwell model. Further, this model is used to derive empirical formulas to fit experimental dynamic nanoindentation data. Using natural latex rubber as a test sample, dynamic nanoindentation experiments were performed with a 108 urn diamond cono-spherical tip at ambient conditions. The results were analyzed using conventional Voigt model and contrasted with analysis done using the Maxwell-standard linear solid model. The results show that conventional Voigt model overestimates the storage modulus of the latex sample by ~ 37 percent. The analysis will prove useful for quantitative nanoindentation property measurements of viscoelastic materials such as rubbery polymers and soft biological materials.
Higher energy density and cycling efficiency are required for the next generation of batteries. Iodine is an attractive material towards the high energy density battery thanks to its high theoretical energy density of...
Higher energy density and cycling efficiency are required for the next generation of batteries. Iodine is an attractive material towards the high energy density battery thanks to its high theoretical energy density of ~0.74 kWh kg–1 and 3.7 kWh L–1. However, due to the nature of low ionic conductivity of solid lithium iodide, the primary lithium-iodine (Li–I2) batteries can only support for extremely low current rate applications such as a pacemaker. To improve rechargeability and rate capability, we have proposed aqueous cathode with a triiodide/iodide (I3 –/I–) redox couple to construct a low-cost, non-flammable, and environmentally friendly Li–I2 battery.[1-4] The aqueous cathode can contain high concentration of I3 –/I– redox couple using I2 and I– ion, which are transformed to I3 – in an aqueous medium (I2(s) + I– ↔ I3 –, K (equilibrium constant) = 723). The electrochemical reaction of this I3 –/I– redox couple in the aqueous cathode leads the total cell reaction of Li–I2 battery: 2Li + I3 – ↔ 2Li+ + 3I–. This aqueous Li–I2 battery demonstrates high storage capacity (~98% of the theoretical capacity), Coulombic efficiency (>99.5%) and cycling performance (>99.5% capacity retention for 100 cycles), which are thus far one of the highest performance among current Li–I2 batteries, aqueous cathode batteries, and lithium-ion batteries using aqueous electrolyte. In addition, high solubility of the I3 –/I– redox couple and appropriate operating potential (~3.5 V vs. Li+/Li and ~0.5 V vs. SHE) but avoiding the electrolysis of water offer a high energy density of ~0.33 kWh kg–1. This energy density can be further improved when equipped with a flow device and aqueous electrolyte reservoir, which allows the aqueous Li–I2 battery to be grid-scale flow battery applications. References [1] Zhao, Y; Wang, L.; Byon, H. R. Nature Communications 2013, 4,1896. [2] Zhao, Y; Byon, H. R. Adv. Energy Mater. 2013, 3, 1630-1635. [3] Zhao, Y.; Hong, M.; Mercier, N. B.; Yu, G.; Choi, H. C
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