Search

Zr-modified LiNi1/3Co1/3Mn1/3− xZr xO2 samples were prepared through a rheological-phase method. The results indicate that there is only partial Zr doping into the bulk phase of the LiNi1/3Co1/3Mn1/3O2 particles, whereas the rest of the Zr remained on the surface to form a Li2ZrO3 coating layer during the Zr-modification process. The Zr-modified LiNi1/3Co1/3Mn1/3− xZr xO2 samples show lower discharge specific capacities at low rates, however, which exhibit clearly improved rate capabilities than that of pristine LiNi1/3Co1/3Mn1/3O2. Among the Zr-modified LiNi1/3Co1/3Mn1/3− xZr xO2 samples, LiNi1/3Co1/3Mn1/3−0.01Zr0.01O2 ( x=0.01) shows the best rate capability, which exhibts158, 142, and 132 mAh g−1 at 1.0, 2.0, and 3.0 C, respectively. The related results indicate that the doped Zr in pristine LiNi1/3Co1/3Mn1/3O2 could improve the structure stability and the formation of an inactive Li2ZrO3 coating layer which could suppress the interfacial side reaction of LiNi1/3Co1/3Mn1/3O2. [ABSTRACT FROM AUTHOR]

Abstract: Binary conductive additives (BCA), formed by sonication of mesoporous carbon (MC) and acetylene black (AB), were used as conductive additives to improve the electrochemical performance of a LiCoO2 composite cathode. The electrochemical performance of the LiCoO2 composite cathode dispersed with BCA was investigated. The results showed that the electrochemical performance (including the discharge capacity, the discharge voltage and the total internal resistance) of a BCA loaded LiCoO2 composite cathode was better than that of a cathode loaded with AB. The possible mechanism is that the MC in BCA can adsorb and retain electrolyte solution, which allows an intimate contact between the lithium ions and the cathode active material LiCoO2 due to its large mesopore specific surface area. A simplified model was also proposed. [Copyright &y& Elsevier]

Abstract: Silicon/graphite/disordered carbon (Si/G/DC) is coated by Li2ZrO3 using Zr(NO3)4·5H2O and CH3COOLi·2H2O as coating reagents. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize Li2ZrO3-coated Si/G/DC composite. The Li2ZrO3-coated Si/G/DC composite exhibits a high reversible capacity with no capacity fading from 2nd to 70th cycle, indicating its excellent cycleability when used as anode materials for lithium ion batteries. A compact and stable solid-electrolyte interphase (SEI) layer is formed on the surface of Li2ZrO3-coated Si/G/DC electrode. Analysis of electrochemical impedance spectra (EIS) shows that the resistance of the coated material exhibits less variation during cycling, which indicates the integrity of electrode structure is kept during cycling. XPS shows that F and P elements do not appear in the SEI layers of Li2ZrO3-coated Si/G/DC electrode, while they have a relatively high content in SEI layers of Si/G/DC electrode. The improvement of Li2ZrO3-coated Si/G/DC is attributed to the decrease of lithium insertion depth and the formation of stable SEI film. [Copyright &y& Elsevier]

Abstract: Thin carbon nanotubes were synthesized by catalytic decomposition of CH4 over MoCoMgO catalyst. We obtained bundles of ordered nanotubes under hydrogen gas and disordered nanotubes under nitrogen gas over the same catalyst. The formation mechanism of nanotube bundles was discussed. The number of the tube walls was 2–5 with the corresponding diameters of 3–6 nm. We obtained a high production yield of 500 wt.% for the thin carbon nanotubes compared to the weight of the supplied catalyst. Moreover the duration of the hydrogen pretreatment was also found to have different effects on the yield of nanotubes under different carrier gases. [Copyright &y& Elsevier]

Abstract: Carbon nanotubes-based TiO2 composites were fabricated by hydrolysis, and the transmission electron microscopy(TEM) results showed that carbon nanotubes were partly coated with TiO2. X-ray photoelectron spectroscopy (XPS) results of purified carbon nanotubes indicated that there were some polar oxygenated groups such as C–O, C=O and O–C=O which might stimulate formation of the composites, and enhance the interfacial combination of TiO2 with carbon nanotubes. The formation of TiO2 and its compounding with CNTs happened almost simultaneously in this process. The method is a convenient route to fabricate CNTs-based TiO2 composites with different ratios. [Copyright &y& Elsevier]