Abstract
This work reported a solid-state method to prepare LiFe0.5Mn0.5PO4/C (LFMP/C) composite cathode materials by using LiH2PO4, MnO2, Fe2O3, citric acid (C6H8O7), and sucrose (C12H22O11). The citric acid was used as a complex agent and C12H22O11 was used as a carbon source. Two novel hollow carbon sphere (HCS) and nanoporous graphene (NP-GNS) additives were added into the LFMP/C composite to enhance electrochemical performance. The HCS and NP-GNS were prepared via a simple hydrothermal process. The characteristic properties of the composite cathode materials were examined by micro-Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental analysis (EA), and alternating current (AC) impedance methods. The coin cell was used to investigate the electrochemical performance at various rates. It was found that the specific discharge capacities of LFMP/C + 2% NP-GNS + 2% HCS composite cathode materials were 161.18, 154.71, 148.82, and 120.00 mAh·g−1 at 0.1C, 0.2C, 1C, and 10C rates, respectively. Moreover, they all showed the coulombic efficiency ca. 97%–98%. The advantage of the one-pot solid-state method can be easily scaled up for mass-production, as compared with the sol-gel method or hydrothermal method. Apparently, the LFMP/C composite with HCS and NP-GNS conductors can be a good candidate for high-power Li-ion battery applications.
Highlights
Li-ion batteries are appropriate for use in cell phones, laptop computers, digital cameras, renewable energy storage, and smart grid applications because of their relatively high energy density, low cost, and high rate capabilities
The characteristic properties of the LiFe0.5 Mn0.5 PO4 (LFMP)/C composite cathode materials were examined by micro-Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental analysis (EA), and alternating current (AC) impedance method
154.7, 150.3, 148.8, 136.7, 130.3, and 120.0 mAhg1 at charge/discharge rates of 0.2C/0.2C, 0.2C/0.5C, 0.2C/1C, 0.2C/3C, 0.2C/5C, and 0.2C/10C, respectively. These results indicate that the LFMP/C + 2% NP-GNS + 2% hollow carbon sphere (HCS) composite exhibited excellent high-rate capability and reliable
Summary
Li-ion batteries are appropriate for use in cell phones, laptop computers, digital cameras, renewable energy storage, and smart grid applications because of their relatively high energy density, low cost, and high rate capabilities. The electrochemical performance can be improved by coating the samples’ surface with carbon, or by doping with Fe atoms or nano-sized cathode materials. The as-prepared LiMn0.7 Fe0.3 PO4 /C cathode material had a capacity of 140 mAhg ́1 and high rate performance. Zhong et al [19] most recently synthesized a carbon-coated LiFe0.5 Mn0.5 PO4 /C (LFMP/C) material by a rheological phase reaction method with stearic acid as the carbon source (i.e., a solid-state method). The LFMP/C material delivered discharge capacities of 138, 99, 80, 72, 67, and 55 mAhg ́1 at 0.1C, 1C, 5C, 10C, 15C, and 20C rates, respectively. The LFMP/C material achieved long and stable cycling performance with a capacity of 103 mAhg ́1 at 1C rate during a 100-cycle test. The characteristic properties of the LFMP/C composite cathode materials were examined by micro-Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental analysis (EA), and alternating current (AC) impedance method
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call