Real-time impedance behaviors of LiFePO4 nanoparticles of two different structures have been investigated as cathode materials for lithium ion batteries using real time Fourier transform electrochemical impedance spectroscopy (FTEIS) techniques during potentiodynamic charging and discharging cycles. The effects of their nanostructures were examined employing hollow sphere secondary structured LiFePO4 particles prepared by sequential precipitations and commercially available non-hollow structured LiFePO4 particles. The battery constructed with the hollow sphere secondary structured LiFePO4 cathode material exhibited improved performances during charging and discharging processes as judged from various impedance parameters compared to those observed for the cell using its non-hollow counterpart. These results appear to have resulted from the enhancement of intrinsic capabilities for electron and charge transport characteristics of LiFePO4 by modifying its secondary structures. The real time impedance measurements were shown to be powerful in studying behaviors of battery electrodes during charging and discharging processes. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.013112jes] All rights reserved.