Ambient synthesis, characterization, and electrochemical activity of LiFePO4 nanomaterials derived from iron phosphate intermediates
ambient synthesis, template synthesis, cathode material, lithium iron phosphate, nanostructures
LiFePO4 materials have become increasingly popular as a cathode material due to the many benefits they possess including thermal stability, durability, low cost, and long life span. Nevertheless, to broaden the general appeal of this material for practical electrochemical applications, it would be useful to develop a relatively mild, reasonably simple synthesis method of this cathode material. Herein, we describe a generalizable, 2-step methodology of sustainably synthesizing LiFePO4 by incorporating a template-based, ambient, surfactantless, seedless, U-tube proto- col in order to generate size and morphologically tailored, crystalline, phase-pure nanowires. The purity, composition, crystallinity, and intrinsic quality of these wires were systematically assessed using transmission electron microscopy (TEM), high-resolution TEM (HRTEM), scanning electron microscopy (SEM), X-ray diffrac- tion (XRD), selected area electron diffraction (SAED), energy dispersive analysis of X-rays (EDAX), and high-resolution synchrotron XRD. From these techniques, we were able to determine that there is an absence of any obvious defects present in our wires, supporting the viability of our synthetic approach. Electrochemical analysis was also employed to assess their electrochemical activity. Although our nanowires do not contain any noticeable impurities, we attribute their less than optimal electrochemical rigor to differences in the chemical bondingbetween our LiFePO4 nanowires and their bulk-like counterparts. Specifically, we demonstrate for the first time experimentally that the Fe–O3 chemical bond plays an important role in determining the overall conductivity of the material, an assertion which is further supported by recent “first-principles”calculations. Nonetheless, our ambient, solution-based synthesis technique is capable of generating highly crystalline and phase-pure energy-storage-relevant nanowires that can be tailored so as to fabricate different sized materials of reproducible, reliable morphology.
Tsinghua University Press
Jonathan M. Patete,Megan E. Scofield,Vyacheslav Volkov,Christopher Koenigsmann,Yiman Zhang,Amy C. Marschilok,Xiaoya Wang,Jianming Bai,Jinkyu Han,Lei Wang,Feng Wang,Yimei Zhu,Jason A. Graetz,Stanislaus S. Wong, Ambient synthesis, characterization, and electrochemical activity of LiFePO4 nanomaterials derived from iron phosphate intermediates. NanoRes.2015, 8(8): 2573–2594