LiFePO4/C with high capacity synthesized by carbothermal reduction method

Abstract

The olivine-type LiFePO 4 /C cathode materials were prepared via carbothermal reduction method using cheap Fe 2 O 3 as raw material and different contents of glucose as the reducing agent and carbon source. Their structural and morphological properties were investigated by X-ray diffraction, scanning electron microscope, transmission electron microscope, and particle size distribution analysis. The results demonstrated that when the content of the carbon precursor of glucose was 16 wt.%, the synthesized powder had good crystalline and exhibited homogeneous and narrow particle size distribution. Even and thin coating carbon film was formed on the surface of LiFePO 4 particles during the pyrolysis of glucose, resulting in the enhancement of the electronic conductivity. Electrochemical tests showed that the discharge capacity first increased and then decreased with the increase of glucose content. The optimal sample synthesized using 16 wt.% glucose as carbon source exhibited the highest discharge capacity of 142 mAh g −1 at 0.1C rate with the capacity retention rate of 90.4% and 118 mAh g −1 at 0.5C rate.

Polyvinylpyrrolidone assisted sol–gel route LiCo1/3Mn1/3Ni1/3PO4 composite cathode for aqueous rechargeable battery

“…The TG curves clearly show that in SG only a trace amount of weight loss (due to slow decomposition of carbon and nitrogen) was found beyond 450°C, however, in SS weight loss was extended till 650°C. In SS, the broad exothermic peak found at 801°C has no significant weight loss evidenced in the curve TG, which is just ascribed to reorganization of the crystal lattice [12]. Although TG-DSC analysis showed 650°C (SS) and 450°C (SG) are suitable enough for the formation of the solid olivine phase LiCo 1/3 Mn 1/3 Ni 1/3 PO 4 , we have extended until 800°C (SS) and 600°C (SG) in order to achieve better crystallization.…”

“…These were focused on the electrochemical performance of lithium insertion/extraction into an olivine cathode in aqueous LiOH electrolyte. One of the main drawbacks with using these olivines is their poor electronic conductivity, [2,12] and this limitation had to be overcome through materials processing 3 mixed metal atom dopants in the olivine structure [12]. The olivines have been generally synthesized by conventional solid state (SS) reaction involving prolonged heat treatment at high temperature to attain phase pure compound.…”

Olivine-type cathode for rechargeable batteries: Role of chelating agents

“…A sharp exothermic peak observed at 310°C is due to decomposition of acetate precursor and a broad exothermic peak at 450°C is due to the decomposition of carbon atom and combustion of nitrogen atoms in chelating agents. However, this exothermic peak at 450°C is broad and extends up to 600°C, but no significant weight loss was found in TGA curve beyond 410°C, and this is ascribed to a reorganization of the crystal lattice [5]. The flattening of the DSC curve indicates the thermal reaction was completed after the formation of olivine phase compounds.…”

“…Recently, we showed [3][4] LiOH aqueous electrolyte found to be an alternate to perform the electrochemical behavior of olivine cathodes. It was reported [5] that the electrical conductivity of the olivine can be improved and is strongly dependent on the synthetic method of the materials that influences superior physical properties i.e. smaller particle size, conductive coatings and transition-metal ion doping.…”

Research Progress in Improving the Rate Performance of LiFePO4 Cathode Materials

“…Carbon coating is an efficient way to enhance the conductivity between particles [33,36,43]. However, this method obviously has little effect on the chemical diffusion coefficient or lattice electronic conductivity of lithium within the LiFePO 4 crystal [44].…”