Sun Fu-Hua,Dong Jinfeng,Dey Shaugath,Asfandiyar,Wu Chao-Feng,Pan Yu,Tang Huaichao,Li Jing-Feng
Cu 12 Sb 4 S 13 tetrahedrite has received great attention as an earth-abundant and environmental-friendly thermoelectric material. This work aims to uncover the thermoelectric performance-enhancing effect and the mechanism of nickel doping on tetrahedrite. A series of Cu 12− x Ni x Sb 4 S 13− δ ( x = 0.5, 0.7, 1.0, 1.5 and 2.0) compounds were synthesized by mechanical alloying combined with spark plasma sintering. It is found that the thermal conductivity sharply reduces with increasing Ni content over the entire temperature range, < 0.9 W m −1 K −1 , accompanied with an enhanced thermoelectric power factor. The model predicted that the reduced lattice thermal conductivity is attributed to mid-frequency phonon scattering, caused by precipitates and dislocations resulting from Ni doping. Consequently, a high ZT value up to 0.95 at 723 K was achieved for Cu 11 NiSb 4 S 13− δ , corresponding to a ∼46% increase over non-doped Cu 12 Sb 4 S 13− δ . Furthermore, the cyclic measurement showed that the Ni-doped tetrahedrites displayed high chemical stability.
As a promising anode material for next-generation high-energy density lithium-ion batteries (LIBs), one of the main technical issues for silicon (Si) electrodes is the low initial Coulombic efficiency (ICE). By a pre-lithiation process, preparation of lithium–silicon (Li–Si) alloy electrodes can efficiently improve the ICE, thus leading to excellent electrochemical performance. Herein, with solid wastes as precursors, we report a cost-efficient approach for the fabrication of Li3.25Si anode materials via simple magnesiothermic reduction and then mechanical alloy reaction methods, combining the advantages of low-cost and high ICE. The prepared Li3.25Si@acetylene black (Li3.25Si@A) electrode exhibits excellent electrochemical performance with a high reversible capacity of 1138.9 mA h g−1 over 90 cycles at a current density of 100 mA g−1 and its ICE is as high as 107.7%, which is superior to that of the commercial Li3.25Si@A electrode. With a simple and low-cost manufacturing process and high ICE, the fabrication process will be definitely meaningful in achieving low-cost and high-capacity anode materials with a prolonged cycle life.
We reported an investigation of the influence of length scale on stabilization of boron carbide (B 4 C) during plasma activated sintering. In the current work, AA7075/B 4 C powders containing two types of B 4 C particles (Micro-B 4 C and Nano-B 4 C) were cryomilled for 8 h in liquid nitrogen, respectively. The characterization of as-cryomilled powders indicated that both Micro-B 4 C particles and Nano-B 4 C particles could distribute homogeneously in the matrix. AA7075/Nano-B 4 C powder have a finer particle size and grain size relative to that of the AA7075/Micro-B 4 C powder. The influence of length scale on stabilization of B 4 C particles during plasma activated sintering was investigated in details. The statistical grain diameter analysis from transmission electron microscopy observation revealed that the grain size of AA7075/Nano-B 4 C bulk (~77.4 nm) is finer relative to those of the AA7075 bulk (~193.5 nm) and AA7075/Micro-B 4 C bulk (~184.7 nm). The coupling effect of ex-situ Nano-B 4 C particles and in-situ dispersion particles contribute to the enhancement of the stabilization of the AA7075/Nano-B 4 C bulk.
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