Micro-sized Sb/SnSb composite synthesized by carbothermal reduction shows a high-specific capacity (ca. 650 mAh/g), a low initial irreversible capacity loss (14%) and a good cycling stability, which are ascribed to the lower specific surface area and the polycrystalline feature of the synthesized Sb/SnSb particles. The large amount of grain-boundaries inside the Sb/SnSb particles can relieve the mechanical stress, originated from the big volume changes upon lithiation and delithiation, by grain-boundary slipping, and thus maintain the structure stability of electrode. The electrode reaction process was characterized by cycling voltammetry and AC impedance techniques. The results indicate that some local cracking of the SEI film may occur due to the large volume changes of active materials and the new film formation takes place. This will not only consume some lithium and thus produce the irreversible capacity loss during cycling process, but also result in decreased SEI film resistance and charge transfer resistance. 相似文献
Novel ultrathin Li(2)MnSiO(4) nanosheets have been prepared in a rapid one pot supercritical fluid synthesis method. Nanosheets structured cathode material exhibits a discharge capacity of ~340 mAh/g at 45 ± 5 °C. This result shows two lithium extraction/insertion performances with good cycle ability without any structural instability up to 20 cycles. The two-dimensional nanosheets structure enables us to overcome structural instability problem in the lithium metal silicate based cathode materials and allows successful insertion/extraction of two complete lithium ions. 相似文献
Magnesium ion batteries are emerging as promising alternatives to lithium ion batteries because of their advantages including high energy density, dendrite-free features and low cost. Nevertheless, one of the major challenges for magnesium ion batteries is the kinetically sluggish magnesium insertion/extraction and diffusion in electrode materials. Aiming at this issue, biphase eutectic-like bismuth-tin film is designed herein to construct a self-supporting anode with interdigitated phase distribution and hierarchically porous structure, and further fabricated by a facile one-step magnetron cosputtering route. As benchmarked with single-phase bismuth or tin film, the biphase bismuth-tin film delivers high specific capacity (538 mAh/g at 50 mA/g), excellent rate performance (417 mAh/g at 1,000 mA/g) and good cycling stability (233 mAh/g at the 200th cycle). The superior magnesium storage performance of the sputtered bismuth-tin film could be attributed to the synergetic effect of the interdigitated bismuth/tin phase distribution, hierarchically porous structure and biphase buffering matrices, which could increase ionic transport channels, shorten diffusion lengths and reduce total volume changes.