Rechargeable aqueous zinc-ion batteries are considered as a promising alternative of lithium-ion batteries for stationary energy storage because of their economical and high safety quality. However, their widespread application is still impeded by the development of cathode materials with poor energy density and limited long-term stability. Herein, we report a high-performance CuV 2 O 6 cathode material for aqueous zinc-ion batteries and elucidate the zinc-storage mechanism. The reversible phase transformation between CuV 2 O 6 and ZnV 2 O 6 , accompanied by zinc ion insertion/ extraction and the reduction/oxidation of metallic Cu nanoparticles, all contribute to excellent battery performance: an impressively high specific capacity of 427 mA h g −1 at current density of 0.1 A g −1 , long-term cycling stability with minor capacity loss (0.7%) after 3000 cycles at a high current density of 5 A g −1 , and a high energy density of 317 Wh kg −1 at a power density of 210 W kg −1 . Furthermore, graphene oxide wrapped CuV 2 O 6 nanocomposites are successfully fabricated, which demonstrates the significantly enhanced specific capacity (at least 30% improvement). This work provides an intriguing cathode material and expands available options of transition metal vanadate materials for zinc-ion batteries.
Bone is a complex dynamic tissue undergoing a continuous remodeling process. Gravity is a physical force playing a role in the remodeling and contributing to the maintenance of bone integrity. This article reports an investigation on the alterations of the bone microarchitecture that occurred in wild type (Wt) and pleiotrophin-transgenic (PTN-Tg) mice exposed to a near-zero gravity on the International Space Station (ISS) during the Mice Drawer System (MDS) mission, to date, the longest mice permanence (91 days) in space. The transgenic mouse strain over-expressing pleiotrophin (PTN) in bone was selected because of the PTN positive effects on bone turnover. Wt and PTN-Tg control animals were maintained on Earth either in a MDS payload or in a standard vivarium cage. This study revealed a bone loss during spaceflight in the weight-bearing bones of both strains. For both Tg and Wt a decrease of the trabecular number as well as an increase of the mean trabecular separation was observed after flight, whereas trabecular thickness did not show any significant change. Non weight-bearing bones were not affected. The PTN-Tg mice exposed to normal gravity presented a poorer trabecular organization than Wt mice, but interestingly, the expression of the PTN transgene during the flight resulted in some protection against microgravity’s negative effects. Moreover, osteocytes of the Wt mice, but not of Tg mice, acquired a round shape, thus showing for the first time osteocyte space-related morphological alterations in vivo. The analysis of specific bone formation and resorption marker expression suggested that the microgravity-induced bone loss was due to both an increased bone resorption and a decreased bone deposition. Apparently, the PTN transgene protection was the result of a higher osteoblast activity in the flight mice.
Herein, we report a simple and quick synthetic route to prepare the pure CuFeS quantum dots (QDs) @C composites with the unique structure of CuFeS QDs encapsulated in the carbon frame. When tested as anode materials for the lithium ion battery, the CuFeS QDs @C composites based electrodes exhibit excellent electrochemical performances. When charge-discharge occurred with a current density of 0.5 A g, the electrodes exhibit a high reversible capacity (760 mA h g) for as long as 700 cycles, which indicates the superior cycling life. Detailed investigations of the morphological and structural changes of CuFeS QDs by ex situ XRD, ex situ Raman, and ex situ TEM reveal an interesting electrochemical reaction mechanism, a hybrid of a lithium-copper iron sulfide battery and lithium-sulfur battery. The direct observation of orthorhombic FeS by HRTEM and the existence of LiFeS detected by Raman support our assertion. We believe such an electrochemical mechanism would attract more attention to the CuFeS nanomaterials as lithium ion battery anode materials. The excellent electrochemical properties would be derived from the unique structure, which include CuFeS QDs encapsulated in the carbon frame.
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