Enhanced electrochemical performance of LiFePO4 of cathode materials for lithium-ion batteries synthesized by surfactant-assisted solvothermal method

Abstract

Lithium iron phosphate (LiFePO 4 ) cathode materials were synthesized by the solvothermal method with the assistance of different surfactants. The influences of polyethylene glycol 2000 (PEG 2000), polyvinylpyrrolidone (PVP), and cetyltrimethyl ammonium bromide (CTAB) on the microstructure and electrochemical performance of LiFePO 4 were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), electrochemical impedance spectroscopy (EIS), and charge/discharge measurements. The particle size of the LiFePO 4 synthesized with the assistance of PEG was uniform and showed a flat rhombohedron-like shape. The initial discharge specific capacity is up to 122.80 mAh/g with an initial coulombic efficiency of 95.50% at 0.1C. LiFePO 4 synthesized with PVP-assisted presents a porous structure with an initial discharge specific capacity of 91.01 mAh/g. LiFePO 4 synthesized with CTAB-assisted shows a flower-like morphology with an initial discharge specific capacity of 100.44 mAh/g. Though the initial discharge capacities of the LiFePO 4 materials prepared with the assistance of CTAB and PVP are lower than those of the LiFePO 4 prepared without the assistance of surfactant, the two materials exhibited excellent cyclic stability at 0.1C.

Green Phosphate Route of Regeneration of LiFePO4 Composite Materials from Spent Lithium-Ion Batteries

“…Apparently, the D Li + value of LEP-12 was 1.09 × 10 –11 cm 2 s –1 , which was the highest. The results clearly indicated that the small particle size and less impurity could enhance the mobility of Li + in the olivine structure and reduce the resistance of the cathode electrolyte surface and polarization reaction, which was beneficial to enhancing the electrochemical behavior of the material …”

“…The results clearly indicated that the small particle size and less impurity could enhance the mobility of Li + in the olivine structure and reduce the resistance of the cathode electrolyte surface and polarization reaction, which was beneficial to enhancing the electrochemical behavior of the material. 40 Figure 7f shows the cyclic voltammetry (CV) measurement of LFP-12 in the first three cycles. It can be seen that the redox potential of the first cycle was slightly lower than those of the second and third cycles.…”

“…After electrolytic leaching, Li 3 PO 4 and FePO 4 were recovered by step precipitation. To reduce the introduction of impurities, the pH values (1.02, 1.50, 1.99, 2.51, 2.99, 4.01, 5.00, and 6.00) and reaction temperatures(25,40, 50, 60, and 70 °C) of the precipitation process were optimized. The pH value of 50 mL of the leaching solution was adjusted by ammonia.…”

Synthesis and modification mechanism of vanadium oxide coated LiFePO4 cathode materials with excellent electrochemical performance

“…Notably, as shown in figures 6(b), (d), LFP/V/C exhibits a narrower voltage gap between the plateaus of charging and discharging compared to LFP/C, which is generally considered to be associated with better redox kinetics [30,31]. The charge/discharge curves of the LFP have become more significantly distorted and the gap widths have increased at higher current densities, indicating a more severe polarization is in the cell, which is not conducive to the long-cycle.…”

Recent Report on the Hydrothermal Growth of LiFePO4 as a Cathode Material

“…Based on the above approach, the ratio between the reactants can be varied for Li:Fe:P = 3:1:1 along with the addition of polyethylene glycol 2000 (PEG 2000), polyvinylpyrrolidone (PVP) and cetyltrimethyl ammonium bromide (CTAB) [58]. The last three reactants act as stabilizers and growth modifiers for the morphology optimization and particle refinement of LFP.…”