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Silicon (Si) is known as an advanced anode material in the application of high-energy lithium-ion batteries (LIBs). However, Si-based anodes still face many challenges in practical applications, su...

Silicon (Si) has been considered as the most promising anode material for the next generation lithium ion batteries (LIBs) due to its ultrahigh theoretical specific capacity (4,200 mAh g-1 and volu...

SiOx has aroused great attractions as a promising substitute for the anode materials of high-performance lithium-ion batteries (LIBs) because of the high specific capacity and the longer cycle life as well as relatively low volume expansion compared to Si. However, the unstable structure and poor conductivity of the SiOx lead to unideal electrochemical properties in LIBs, and thus hindering the widespread application of the SiOx anode. Herein, a facile approach has been put forward to prepare the high-performance mesoporous structure SiOx/carbon (m-SiOx/C) composites by electrospinning technique and sintering processes. The spherical SiOx nanoparticles are well anchored on the carbon fibers, and the reserved space can accommodate large volume expansion of the SiOx materials. Besides, the fibrous carbon materials can significantly enhance the conductivity for the SiOx anodes. Therefore, the resultant m-SiOx/C composites exhibit high discharge specific capacity of 1434 mAh g−1 at 500 mA g−1 with 67.5% capacity retention after 500 cycles and the good rate properties of 410 mAh g−1 at 2000 mA g−1. In consequence, the reasonable structural design and innovative fabrication technique can facilitate the practical application for the m-SiOx/C composites and further promote the comprehensive electrochemical performance of LIBs.

Oriented construction of high-performance mesoporous TiNb2O7 (m-TNO) is important to the design innovation of anode material for next-generation lithium-ion batteries (LIBs) due to the high capacity and long cyclic life of m-TNO. However, the conductivity enhancement of m-TNO and thus accelerating Li+ transfer is still the key point to realize its practical application in LIBs. In this work, a synergistic strategy based on the single-core/dual-shell m-TNO@TiC@NC hierarchical structure is put forward, which is achieved by using m-TNO as host architecture as well as TiC and N-doped carbon layer (NC) as dual-shell layers. The results show that the m-TNO@TiC@NC hierarchical structure can not only provide an integrated conductive network to improve the conductivity of m-TNO, but also can establish a reinforced structure to maintain the anode stability. Besides, it is found that the m-TNO@TiC@NC composite has a high capacity of 328.6 mAh g−1 at 0.5 C after 200 cycles and a high-rate capacity of 186.4 mAh g−1 at 5 C by galvanostatic discharge-charge tests. Therefore, this kind of special single-core/dual-shell structure design can convincingly enhance the conductivity of m-TNO and facilitate the Li+ transfer rate, thus promoting electrochemical performances of LIBs due to the synergistic effect of dual-shell layers.

The activated carbon cloth (ACC@TNO) with flexible self-support structure, which is decorated by TiNb2O7 (TNO) nanoparticle, is successfully obtained through hydrothermal reaction and calcination process in high temperature, and is used as the binder-free anode material of lithium ion batteries (LIBs). The morphology characteristic, pore structure properties and the phase structure of the ACC@TNO composites are detailedly studied by the scanning electron microscopy (SEM), Brunauer–Emmett–Teller adsorption/desorption measurement (BET) and X-ray diffraction (XRD). Meanwhile, the electrochemical properties of ACC@TNO composite are further tested by cyclic voltammetry and galvanostatic charge-discharge tests. As a result, the LIBs with ACC@TNO as anode material shows an initial discharge capacity of 356 mAh g−1 and an initial coulombic efficiency (ICE) of 87% at the current density of 0.5 C with the voltage window of 1.0–3.0 V. It also has been found that the reversible capacity can still keep as 290 mAh g−1 with the capacity retention of 81% after 500 cycles. Besides, when the cutoff voltage range is set to 0.01–3.0 V, the reversible capacity can reach 340 mAh g−1. Apparently, this work is of great significance for the exploration of the new anode materials with high performance and long cyclic life in next-generation LIBs.

The cornlike ordered mesoporous silicon (OM-Si) particles modified by the nitrogen-doped carbon layer (OM-Si@NC) are successfully fabricated and used as the anode of lithium-ion battery (LIBs). The influences of the N-doped carbon layer on the structure and electrochemical properties of the OM-Si@NC composite are detailedly investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectrum, X-ray photoelectron spectroscopy (XPS), and charge/discharge tests. The results reveal that the amorphous N-doped carbon layer can offer the abundant conductive pathways for fast lithium ion transportation and electron transfer, which not only leads to a high specific capacity under high ampere density but also serves as a structural barrier maintaining the whole integrity and settling the mechanical breaking due to the huge volume changes of Si host. Therefore, the as-synthesized OM-Si@NC composite exhibits a high original discharge capacity of 2548 mA h g–1 under 0.2 A g–1 as well as a la...

The hardness and electronic work function (EWF) of a bulk metallic glass, namely Zr41.2Ti13.8Cu12.5Ni10Be22.5, have been studied experimentally, with an emphasis on the effect of heat treatments. The glass was annealed at different time and temperatures, and its hardness and EWF measured using the Rockwell indentation technique and a scanning Kelvin probe system, respectively. It is found that the EWF decreases with annealing time and temperature, whereas the hardness increases. This study shows a close relationship between hardness and EWF, indicating that the EWF could be a sensitive parameter for characterising and investigating the mechanical behaviour of BMG at the electronic level.

In spite of many superior high-temperature properties of intermetallics, it has been difficult to understand their intrinsic brittleness. To eliminate or improve the embrittlement, the conventional alloying technique based on the trial-and-error method is still the most effective and practical. However, it remains a main challenge for both physicists and materials scientists to provide either an alloying principle or a deep insight into its toughening mechanism at an atomic or electronic level. This letter reports a simple experimental approach that uses work function (WF) as a sensitive indicator of the role of alloying in changing mechanical behavior. NiAl is chosen as a typical example. It is found that with the addition of Cr and Ce, the ductility of NiAl increases significantly. Such an increase in ductility corresponds to a concomitant decrease in the WF, which is attributed to a change in the nature of the atomic bonding or in the electronic structure induced by the alloying. This fundamental under...

Surface electronic behavior of metallic materials induced by mechanical action or loading has been investigated experimentally, but the role of the deformation mode and further stress/strain state in such behavior has hardly been revealed theoretically. In this letter, we present a systematic study of the strain-dependent work function (WF) on the Cu (100) surface using first-principles calculations. We employ four deformation modes, namely, uniaxial, biaxial and triaxial as well as perpendicular, to demonstrate the strong dependence of the WF on strain states. We find that the compressive state makes the WF increase but the tensile state makes the WF decrease, whereas the lateral strain state can affect strongly the WF but the perpendicular state can hardly do so. Furthermore, both the bi- and triaxial strain states lead to a larger WF change than other two states. The mechanism responsible for the above changes in WF can be related to the effects of strain states on the bulk cell volume and redistributed charge density and the resultant bulk electronic structures and surface dipoles.