Silicon-graphite composites were prepared by mechanical ball milling for 20 h under argon protection. The microstructure and
electrochemical performance of the composites were characterized by X-ray diffraction (XRD), scanning electron microscopy,
and electrochemical experiments. XRD showed that the materials prepared by ball milling were composites consisting of Si and
graphite powders. The composite electrode showed the best performance, especially when annealed at 200 °C for 2 h, which had
a reversible capacity of 595 mAh g−1 and an initial coulombic efficiency of 66%, and still retained 469 mAh g−1 after 40 cycles with about 0.6% capacity loss per cycle. 相似文献
Solid state battery (SSB) performance is largely governed by processes occurring at electrolyte–electrode interfaces. At the Li metal anode, where the overwhelming majority of solid electrolyte (SE) are unstable against Li metal, the interface can readily react to form emergent Li-solid electrolyte interphases (SEI) with ionic, electronic, chemical, mechanical, and electrochemical properties substantially distinct from the parent phase. Facing similar challenges with liquid electrolytes, the Li battery community underwent a half century-long effort, still in progress, to illuminate fundamental properties of the Li SEI—including chemistry, morphology, transport, and sources of Li loss upon cycling—from which guiding principles have emerged to drive improvement in electrolyte and interface design. The Li metal SEI with solid electrolytes presents both similarities and differences to that in liquid electrolytes, with differences defining unique research needs. Here, we examine current understanding of the Li-SE interface as well as learnings from the liquid electrolyte community that we propose might be adopted to help rationalize and improve SE integration with Li anodes. Through this lens, we inspect current state-of-understanding of Li SEI composition, structure, and properties, along with Coulombic efficiency values reported so far for Li cycling with SE. We also highlight potential Li modification strategies for SSB, which are informed by and exploit understanding of the ionic SEI phases; in some instances, engineering strategies utilize a liquid electrolyte SEI directly, making liquid-derived SEI knowledge of immediate relevance. 相似文献
P25/graphene nanocomposites were successful synthesized in a water-ethanol solvent under hydrothermal conditions. During the process of the reduction of GO into graphene (GR), the P25 nanoparticles were decorated on graphene sheets simultaneously. Moreover, the GR content in the as-synthesized nanocomposites can be easily adjusted by changing the dosage of P25. The interesting P25/GR nanocomposites were found to be a promising anode material for lithium-ion batteries and showed significantly enhanced Li-ion insertion/extraction performance. The optimal weight percentage of GR was found to be 29.9%, which resulted in a high capacity of 282.8 mAh g−1 after 50 cycles at a current rate of 0.5 C. The improved capacity may be attributed to the synergetic effect between graphene sheets and P25 nanoparticles. 相似文献
A new microporous carbon, prepared from pinecone hull, exhibits high charge/discharge capacity when used as anode material for lithium secondary batteries. After 6 cycling tests, the microporous carbon retains a discharge capacity of 357 mAh g− 1, and a coulombic efficiency of 98.9% is achieved at a higher current density of 10 mA g− 1. After the microporous carbon is charged and discharged at a lower current density of 7 mA g− 1 for 8 cycles, a capacity of 394 mAh g− 1 and a coulombic efficiency of 99.0% are achieved. Element analysis indicates that a certain amount of H and N exist in this microporous carbon. 相似文献
Current research on vanadium oxides in lithium ion batteries (LIBs) considers them as cathode materials, whereas they are rarely studied for use as anodes in LIBs because of their low electrical conductivity and rapid capacity fading. In this work, hydrogenated vanadium oxide nanoneedles were prepared and incorporated into freeze-dried graphene foam. The hydrogenated vanadium oxides show greatly improved charge-transfer kinetics, which lead to excellent electrochemical properties. When tested as anode materials (0.005–3.0 V vs. Li/Li+) in LIBs, the sample activated at 600 °C exhibits high specific capacity (～941 mA·h·g?1 at 100 mA·g?1) and high-rate capability (～504 mA·h·g?1 at 5 A·g?1), as well as excellent cycling performance (～285 mA·h·g?1 in the 1,000th cycle at 5 A·g?1). These results demonstrate the promising application of vanadium oxides as anodes in LIBs.
