High-Rate and Long-Life Au Nanorods/LiFePO4 Composite Cathode for Lithium-Ion Batteries

LiFePO 4 is considered a promising cathode material for lithium-ion batteries for its high theoretical specific capacity and cycling stability. However, low electrical conductivity and Li-ion diffusion coefficient limit its electrochemical performances. Herein, gold nanorods (Au NRs) with a length of about 40 nm (aspect ratio of 7:1) are successfully prepared by a seed-mediated growth method. LiFePO 4 composite cathodes with 0.1/0.5/1 wt% Au NRs are compared with a pristine LiFePO 4 cathode, which shows that the addition of Au NRs can improve the electron and lithium-ion transport. Specifically, the addition of 1 wt% Au NRs increases the electrical conductivity and lithium-ion diffusion coefficient to 1.99 S cm −1 and 1.32 × 10 −14 cm 2 s −1 , respectively. The distribution of relaxation times analysis is carried out for the electrochemical impedance spectrum data to distinguish different electrochemical reactions within corresponding frequency regions. Particularly, LiFePO 4 with 0.1 wt% Au NRs exhibits a superior rate capability (133.7 mAh g −1 at 2C and 91.9 mAh g −1 at 5C) and stable cycling performance.