The composite LiFePO 4 /polyaniline was prepared by chemical synthesis to promote the intensification of the electrochemical properties for use as cathodes in lithium ion batteries. The X-ray diffraction (XRD) of LiFePO 4 synthesized by solvothermal method were indexed to the orthorhombic structure, according to the JCPDS 40-1499. The spectra Raman and FTIR showed a high degree of ordering of LiFePO 4 with interaction between LiFePO 4 surface with structure conjugate of conducting polymers. The cyclic voltammogram of the composite synthesized chemically showed a significant reduction in the value of ΔE p (ΔE p = 0.20 V) when compared to LiFePO 4 (ΔE p = 0.41 V), with lower charge transfer resistance values, indicating favoring electron transfer rate in the composite. Thus, the alternative synthesis route of the LiFePO 4 / PAni composite was easy to handle and allowed an increase in the electrochemical properties of the LiFePO 4 , compared to the traditional methods that require additional thermal treatments.

Polypyrrole (PPy) is one of the most studied conducting polymers and a very promising material for various applications such as lithium-ion secondary batteries, light-emitting devices, capacitors, and supercapacitors, owing to its many advantages, including good processability, easy handling, and high electronic conductivity. In this work, PPy films were chemically and electrochemically synthesized, both in and around carbon nanotubes (CNTs). The cyclic voltammograms of the device, composed of the electrochemically synthesized PPy/CNT composites as working and counter electrodes (Type I supercapacitor with p-type doping), showed a predominantly capacitive profile with low impedance values and good electrochemical stability, with the anodic charge remaining almost constant (11.38 mC), a specific capacitance value of 530 F g−1after 50 charge and discharge cycles, and a coulombic efficiency of 99.2%. The electrochemically synthesized PPy/CNT composite exhibited better electrochemical properties compared to those obtained for the chemically synthesized composite. Thus, the electrochemically synthesized PPy/CNT composite is a promising material to be used as electrodes in Type I supercapacitors.

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) were prepared by Pechini synthesis using lithium and manganese acetates, citric acid, ethylene glycol, and the respective oxide or acetate of the doping ions in molar ratios of 2.00 (Mn 1.98 + M 0.02 ) to 1.05 Li. The TGA/DTA of the precursor gels showed weight loss/energy relative to crystallization below 450 ºC. From the XRD, a single cubic phase (F D3M ) was identified for the all-doped or undoped oxides after only 2 h calcination. The unit cell parameters a for both aluminum-and gallium-doped oxides calcined at 750 °C for 2 h (8.212 Å and 8.210 Å, respectively) were higher than that for the undoped oxide (8.199 Å). The crystallite sizes ranged from ~ 20 nm to 70 nm, conferring nanometric character. The specific capacities decreased in order: C discharge (Li