Li Hongqin, Ye Haijun, Xu Zheng, Wang Chuanyi, Yin Jiao, Zhu Hui
College of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031, China.
Key Laboratory of Functional Materials and Devices for Special Environments, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, 40-1 South Beijing Road, Urumqi, Xinjiang 830011, China.
Phys Chem Chem Phys. 2017 Jan 25;19(4):2908-2914. doi: 10.1039/c6cp07569j.
Flexible and freestanding MoO/MoC imbedded carbon fibers (MoO/MoC ICFs) have been successfully synthesized via an integrated procedure including electrospinning, thermo-plastication in air and reduction/carbonization at high temperature. A series of techniques such as SEM, TEM, N adsorption-desorption analysis, XRD, TGA, IR and XPS have been employed to systemically characterize the MoO/MoC ICFs. In particular, it is observed that the MoO/MoC ICFs derived from phosphomolybdic acid have more highly porous structures than those derived from molybdic acid. Most impressively, the obtained MoO/MoC ICFs are directly used as binder- and current collector-free anode materials for LIBs, which exhibit desirable rate capability and satisfactory cycling performance. The electrochemical investigations illustrated that the MoO/MoC ICFs could deliver an initial discharging capacity of 1422.0 mA h g with an original coulombic efficiency of 63.3%, and the subsequent reversible capacity could reach as high as 1103.6 mA h g even after 70 cycles at a current density of 0.1 A g. Such a capacity is larger than the theoretical capacity of MoO (838 mA h g) and pure carbon fibers (460.5 mA h g). More importantly, the MoO/MoC ICFs exhibited an excellent rate performance with a capacity of 445.4 mA h g even at a charging current density of 1.6 A g. The remarkable enhancement in rate capability and long cycling performance resulted from a synergistic effect between the MoO nanoparticles and porous carbon fiber matrix. This methodology can be widely extended to fabricate other metal oxide/carbon composites for significant energy storage and conversion applications.
通过包括静电纺丝、空气中热塑化以及高温还原/碳化的集成程序，成功合成了柔性且独立的MoO/MoC嵌入碳纤维（MoO/MoC ICFs）。采用了一系列技术，如扫描电子显微镜（SEM）、透射电子显微镜（TEM）、N吸附-脱附分析、X射线衍射（XRD）、热重分析（TGA）、红外光谱（IR）和X射线光电子能谱（XPS）对MoO/MoC ICFs进行系统表征。特别地，观察到由磷钼酸衍生的MoO/MoC ICFs比由钼酸衍生的具有更高的多孔结构。最令人印象深刻的是，所获得的MoO/MoC ICFs直接用作锂离子电池（LIBs）的无粘结剂和无集流体阳极材料，表现出理想的倍率性能和令人满意的循环性能。电化学研究表明，MoO/MoC ICFs的初始放电容量为1422.0 mA h g，初始库仑效率为63.3%，即使在0.1 A g的电流密度下循环70次后，随后的可逆容量仍可高达1103.6 mA h g。这样的容量大于MoO的理论容量（838 mA h g）和纯碳纤维的理论容量（460.5 mA h g）。更重要的是，即使在1.6 A g的充电电流密度下，MoO/MoC ICFs仍表现出优异的倍率性能，容量为445.4 mA h g。倍率性能和长循环性能的显著提高源于MoO纳米颗粒与多孔碳纤维基体之间的协同效应。这种方法可以广泛扩展到制备其他金属氧化物/碳复合材料，用于重要的能量存储和转换应用。
