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

Abstract

LiFePO4 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. LiFePO4 composite cathodes with 0.1/0.5/1 wt% Au NRs are compared with a pristine LiFePO4 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 cm2 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, LiFePO4 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.