Morphological solution for enhancement of electrochemical kinetic performance of LiFePO4

LiFePO4/Cnanosheet composite has been prepared via a low-temperature solvothermal reaction followed by high-temperature treatment. The as-prepared sample is characterized by XRD, FDR, Raman, SEM, and TEM. It is confirmed that the nanosheets are composed of ca. 50 nm thickness of crystalline LiFePO4-core coated with ca. 10 nm thickness of carbon-shell. The charge-discharge tests show that the as-fabricated LiFePO4/C nanosheet cathode in lithium-ion cell demonstrates high reversible capacity (164 mAh g(-1) at 0.1 C) and good cycle stability (columbic efficiency 100% during 100 cycles). The cyclic voltammetric analysis indicates Li+ diffusion determines the whole electrode reaction kinetics, and the diffusion coefficient estimated by EIS is comparable to the reported data. The enhanced kinetic behavior of the as-fabricated cathode is actually originated from the nano-dimensional sheet-like morphology, which facilitates Li+ migration due to the shortened diffusion distance, and simultaneously increased exchangeable Li+ amount considering more accessible active surface. In addition, the uniformly coated thin conductive carbons contribute a lot for this enhancement because of considerably improved electronic conductivity. (C) 2010 Elsevier Ltd. All rights reserved.