Investigation of structural and electrochemical performance of Ru-substituted LiFePO4 cathode material: an improvement of the capacity and rate performance

LiRuxFe1-xPO4 (where x = 0.01-0.12) samples are successfully fabricated by conventional solid-state reaction technique and the structural properties are analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and fourier transform infrared spectroscopy (FTIR) measurements. The XRD analysis shows that the minor impurity phases of RuO2 and LiRuO2 are observed for x >= 0.05 samples. Furthermore, the lattice volume is decreased with increasing Ru-content in the structure. The Ru-substituted battery cells exhibit similar cycling voltammetry (CV) data with the unsubstituted LiFePO4 battery cells. According to the charging/discharging cycles measurements for C/3-rate, the best capacity (147.58 mAh g(-1)) is obtained for LiFe0.93Ru0.07PO4 with a capacity fade of 0.0084 per cycle. It is found that Ru-substituted LiFePO4 has maximum C-rate when we analogize with the pristine LiFePO4 and the battery cycling performance is investigated for 4 C-rate up to 100 cycles and 3 and 4 C-rate up to 1000 cycles and it is found that Ru-substituted LiFePO4 exhibits excellent electrochemical performance such as 122, 84.5, and 53.1 mAh g(-1) for 1st, 500th, and 1000th cycles at 4 C-rate.

Automated summary

In this study, Ru-substituted LiFePO4 battery materials were successfully fabricated and their structural properties were analyzed. It was found that Ru substitution affected the lattice volume and impurity phases of the material. The Ru-substituted LiFePO4 batteries exhibited excellent electrochemical performance, with higher capacity and cycling stability.