Abstract Li 4 Ti 5 O 12 hollow mesoporous microspheres assembled from nanoparticles are prepared by hydrothermal reaction of LiOH and TiO 2 (autoclave, 160 °C, 2 d) and subsequent calcination (400 °C, 2 h).
SnO2 is a potential anode material with high theoretical capacity for lithium-ion batteries (LIBs), however, its application has been limited by the severe volume expansion during charging-discharging process. In this work, an inverse opal TiO2/SnO2 composite with an interconnect network nanostructure was designed to confine SnO2 nanoparticles in the porous TiO2. Due to this nanoconfinement structure, the volume expansion in the process was effectively alleviated, therefore the safety performance and cycling stability of the battery were effectively improved. At the same time, with a large number of microporous structures in the framework, the appearance of pseudocapacitance improves the rate performance and reversible capacity. In terms of electrochemical kinetics, its framework provides the connected path for charge migration, effectively reducing the charge transfer impedance, meanwhile, quantities of micropores in its skeleton could provide a smoother channel for lithium ions, thus greatly improving the diffusion rate of LIBs. The design of this nanostructure provides a new idea for the research of SnO2-based anode with effectively enhanced electrochemical performance, which is promising anode for practical application.
Abstract The metal organic frameworks (MOF‐5) with nanoscale porosity and organic–inorganic heterocyclic structure were chemically grafted onto carbon fibers by solvothermal for forming high mechanical interlocking composite architectures and releasing the interfacial forces, so as to obtain carbon fiber reinforced composite with excellent mechanical and tribological properties. With the multi‐scale enhancement of MOF‐5, the optimized tensile and bending strength of the composite increased by about 177.9% and 81.3%, respectively. Moreover, the friction coefficient was higher and relatively stable under the continuous wet friction condition, as well as the wear rate was reduced by 44.4%. The work suggests that the application of MOFs can be extended to the field of structural composites.
Abstract A preform‐decomposition process is employed to prepare a composite of MoO 2 nanoparticles (≈100 nm) anchored on graphene oxide (MoO 2 /GO) for sodium‐ion battery anodes. The discharge gravimetric (volumetric) capacity of the MoO 2 /GO is 483 mAh g −1 (by active material ≈2318 mAh cm −3 ) at the current density of 100 mA g −1 after 10 cycles. After 100 cycles, the discharge gravimetric (volumetric) capacity was maintained at 345 mAh g −1 (≈1656 mAh cm −3 ) and stabilized. During the first 1000 cycles, the capacity degradation is only 1.9 % for each 100 cycles, and the electrode is still able to deliver 276 mAh g −1 after 1000 cycles. Moreover, the nanostructures are able to withstand high rate cycling, the capacity can be fully recovered after being cycled at a rate as high as 2000 mA g −1 . The promising electrochemical performance can be attributed to the high electronic conductivity of MoO 2 and the connected nanostructures, which facilitate both fast electronic and ionic transport.
The hot compressive behavior at different temperature (300℃～400℃) and strain rate (0.001s-1~0.1s-1) of Al18B4O33w/AZ91D was investigated by use of Gleeble -1500D thermal simulation testing machine and the constitutive parameters were identified through the experiments.The strain rate sensitivity exponent(m) and apparent activation energy(Q) of the selected composite were determined according to true stress-strain curves.The results show that the flow stress decrease continually after the peak stress because of strain softening caused by whisker rotation and breakage.The exponential form represents high stress regime,the power form represents the low stress regime and the hyperbolic sine form represents all stress regime.The value of m and Q of composite are both higher than the matrix alloy because of the addition of Al18B4O33 whisker.
Tin sulfide, as a promising anode material for Li-ion batteries, suffers from high-capacity loss during cycling and low initial Coulombic efficiency, which limits its further application. In order to solve these problems, Li+-intercalated SnS2 with expanded interlayer spacing (0.89 nm) was prepared by the one-step urothermal method. The successful synthesis of Li+-intercalated SnS2 is confirmed by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma emission spectrometer test, and exfoliation experiment. Compared with pure SnS2, the Li+-intercalated SnS2 electrode displays a higher initial Coulombic efficiency (79.3%) than the pure SnS2 electrode (55%). Also, Li+-intercalated SnS2 exhibits more excellent rate performance (548.4 mAh g–1 at 2 A g–1 and 216.6 mAh g–1 at 10 A g–1) and cycling performance (647.7 mAh g–1 at 0.1 A g–1 after 100 cycles).
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