Enhanced electrochemical performance of LiFePO4/C wrapped with sulfur-modified reduced graphene oxide for Li-ion batteries

Although researchers have previously examined whether graphene modified by sulfur can improve the electrochemical performance of LiFePO4/C composites, they have rarely examined whether it can do so during the synchronous synthesis of LiFePO4/C and sulfur-modified reduced graphene oxide (SG) via a one-step hydrothermal method. To answer this question, a series of olivine structure LiFePO4/C composites wrapped with SG were investigated. Subsequently, we found that SG can form a three-dimensional conductive network on the surface of the LiFePO4/C sample. In the process, XRD and HRTEM tests were undertaken as well. From the XRD test, the results show that SG does not affect the olivine structure of LiFePO4/C. In the HRTEM experiment, clear lattice fringes and a uniformly coated carbon layer on the sample surface were observed. Alongside these results, there were 4 others. First, the charge-discharge data showed that the electrochemical performance of the samples could be increased by SG modification. Second, sample S2 with a mass ratio of Na2S to rGO of 1:10 shows the best specific discharge capacity and stability. Third, the specific capacity of S2 is 163 mAhg(-1) at 0.2 C, and the capacity retention is 108.23% even after 200 cycles at a magnification of 10 C. Fourth, according to EIS, the charge migrating resistance of S2 is 226.4 omega, and the lithium-ion diffusion coefficient is 2.41 x 10(-14) cm(2)center dot S-1. The significance of these results is that they indicate that wrapping LiFePO4/C with SG significantly contributed to the improvement of its electrochemical performance.

Automated summary

The study investigated the simultaneous synthesis of LiFePO4/C and sulfur-modified reduced graphene oxide (SG) through a one-step hydrothermal method. It was found that SG significantly improved the electrochemical performance of the samples, with sample S2 showing the best specific discharge capacity and stability. The results indicate that wrapping LiFePO4/C with SG contributes to enhancing its electrochemical performance.