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LiFePO4 is fascinating cathode active materials for Li-ion batteries application because of their high electrochemical performance such as a stable voltage at 3.45 V and high specific capacity at 170 mAh.g-1. However, their low intrinsic electronic conductivity and low ionic diffusion are still the hindrance for their further application on Li-ion...
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... Studies on LFP coating methods with graphene and rGO began to run smoothly. Ding et al. (2010), have prepared LiFePO4/graphene composites with coprecipitation method, but the electrochemical performance of the cathode material was not optimum [11]. Similarly, Arifin et al., have successfully prepared LiFePO4-based rGO composites using the hydrothermal method [12]. ...
In this study, an investigation has been conducted on the effect of reduced graphene oxide (rGO) coating on increasing the value of Lithium Ferro Phosphate (LFP) electrical conductivity. This coating process used a variation of the mass ratio of LiFePO4/rGO by 90%:10%, 70%:20%, and 67%:33%. The LiFePO4 precursor was prepared using the sol-gel route from the main commercial materials, namely Li2CO3 powder as a source of lithium ions, FeCl2.4H2O as a source of iron and NH4H2PO4 powder as a phosphate source. As for the coating, we used rGO extracted from coconut shell waste. The samples were calcined with temperature variations of 600 o C, 650 o C, and 700 o C in an argon environment for 10 hours. The phase purity and crystal structure of LiFePO4 were analyzed using X-Ray Diffraction (XRD). The analysis of data from XRD was done using the Match!, Rietica, and MAUD software. Based on the results of XRD analysis, LiFePO4 with high purity and excellent crystallinity was obtained when the sample was calcined at a temperature of 700 o C. The results of the MAUD analysis show that the best size of LiFePO4 crystal is 86.54 nm. LiFePO4/rGO nanocomposite was successfully synthesized by mechanical ultracentrifugation method. The characterization of the value of electrical conductivity was carried out using a four-point probe. The results show that the greater the percentage of rGO, the higher the value of electrical conductivity. The mass ratio of 67% LiFePO4 and 33% rGO shows an increment in good conductivity values, from the original order of 10-8 S/cm to the order of 10-4 S/cm.
... The electrical conductivity of the LiFePO 4 /Li 2 SiO 3 /rGO composites was obtained as 8.67 × 10 −9 S cm −1 , 9.35 × 10 −9 S cm −1 and 10.3 × 10 −9 S cm −1 , for 0 wt% rGO, 1 wt% rGO and 2 wt% rGO, respectively [20]. Based on these results, it confirms that the addition of rGO into LiFePO 4 /Li 2 SiO 3 composite improves the conductivity of the samples. ...
LiFePO4 is commonly used as cathode material for Li-ion batteries due to its stable operational voltage and high specific capacity. However, it suffers from certain disadvantages such as low intrinsic electronic conductivity and low ionic diffusion. This study was conducted to analyse the effect of reduced graphene oxide (rGO) on the electrochemical properties of LiFePO4/Li2SiO3 composite. This composite was synthesized by a hydrothermal method. Fourier transform infrared spectroscopy measurement identified the O-P-O, Fe-O, P-O, and O-Si-O bands in the LiFePO4/Li2SiO3 composite. X-ray diffraction measurement confirmed the formation of LiFePO4. Meanwhile, Raman spectroscopy confirmed the number of rGO layers. Further, scanning electron microscopy images showed that rGO was distributed around the LiFePO4/Li2SiO3 particles. Finally, the electrochemical impedance spectroscopy results showed that the addition of 1 wt% of rGO to the LiFePO4/Li2SiO3 composite reduced charge transfer resistance. It may be concluded that the addition of 1 wt% rGO to LiFePO4/Li2SiO3 composite can enhance its electrochemical performance as a cathode material.
Printed electronics belongs to one of the most prominent electronics technologies allowing us to manufacture electronic components and devices on different kinds of substrate materials. This manufacturing technology reveals to have significant potential to be used in Internet of Things (IoT) applications. In this paper, composite materials which are suitable for the production of a variety of IoT devices are discussed. Particular attention was focused on metal- and carbon-based composite materials allowing us to form conductive parts of the IoT devices produced. Further, sensor and encapsulation materials were reviewed as well. These conductive and sensor materials comprised of micro- and nano-particles, such as silver, copper, graphene oxide and its reduced forms, carbon nanotubes, carbon black or graphene nanoplatelets. Based on the conducted analysis, it was stated that further investigations of curing methods, fillers materials and composition of composites are recommended to be carried out in order to study mechanical, thermal and electrical properties of composite materials required for IoT applications.
