This study employs density functional theory (DFT) in order to investigate the fluorine doping effects on the structural, electrochemical and electrical, properties of LiCoO2 cathode materials for LIBs. The research reveals that fluorine substitution with oxygen can significantly enhance the performance and stability of LiCoO2 in multiple aspects. Investigation show that the fluorine doping results in n-type doping and Fermi level increases in electron density of states, which may enhance the electrical conduction. The substitution of fluorine modifying the cycling life of battery and improves the structural stability by suppressing the expansion rate of volume and increasing the lattice parameter along the c-axis during full delithiation. The findings demonstrate that the fluorine doping improves the structural stability of LiCoO2 by decreasing volume shrinkage during the delithiation. Accordingly, the study identifies the most stable fluorine substitution site, located furthest from the lithium layer. Consistent results from calculations using different approaches (internal and Fermi energy) and methods (GGA and GGA+U) confirm that LiCoO2-xFx exhibits lower voltage compared to LiCoO2, making it desirable for electrolyte tolerance and prolonged battery lifetime. Evaluation of electrical properties demonstrates that the fluorine doping enhances the electrical conductivity of LiCoO2 by reducing the band gap and charge carrier transfer barrier (CCTB). The examination of intrinsic and extrinsic band gaps, as well as Delta and CCTB approaches, consistently reveals that LiCoO2-xFx exhibits a lower band gap and CCTB, indicating improved rate-capability and electrical conductivity.

LiMn2O4 spinel cathode materials have been successfully synthesized by solid-state reaction. Surface of these particles were modified by nanostructured LiFePO4 via sol gel dip coating method. Synthesized products were characterized by thermally analyzed by Thermo gravimetric and Differential Thermal Analysis (TG/DTA), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) spectroscopy. The results of electrochemical tests showed that the charge/discharge capacities improved up to 120 mAh/g and charge retention of battery enhanced over %95. This improved electrochemical performance is caused by LiFePO4 phosphate layer on surfaces of LiMn2O4cathode particles.

LiCoPO4 has been recognized as a promising cathode material for lithium batteries due to its high stability and high operation voltage. However, poor electronic conductivity of LiCoPO4 prohibits its practical use. A carbon coating can improve electronic conductivity of LiCoPO4. A hydrothermal synthesis is a very convenient method because it allows us easy preparation of small particles of carbon-coated LiCoPO4; however, an effect of precursor for LiCoPO4 preparation on the performance of the synthesized LiCoPO4 has yet to be cleared. In this paper, the effect of Co source for carbon-coated LiCoPO4 (LiCoPO4/C) preparation on performance as a cathode material for Li-ion battery is investigated. The Co source strongly affects the pH value in the starting solution and final products.The single-phase LiCoPO4 is obtained only when CoSO4 or CoCl2 are used as the Co sources. A quality of carbon layer on the LiCoPO4 is also affected by the Co source. The carbon layer on the LiCoPO4 synthesized from CoSO4 contains graphite carbon with high concentration which provides high electronic conductivity compared with that from CoCl2. Accordingly, the LiCoPO4/C synthesized from CoSO4 shows a superior performance than that from CoCl2 due to high-quality carbon layer.

In this study, the spinel compound LiMn2O4 was manufactured as the cathode active material for Li-ion batteries via the sol–gel process. The field-emission scanning electron microscope (FESEM) was employed for an evaluative analysis of the external surface morphology of the synthesized material. The crystal structure of the spinel material was confirmed using X-ray diffractometry (XRD). The XRD graph exhibited no signs of impurity peaks, confirming a singular crystal structure phase. As per the Scherrer equation, the crystal size was estimated at 31.98 nm. The energy-dispersive X-ray spectroscopy (EDX) spectra for the equipped sample showed the existence of manganese and oxygen, and the concentrations were very close to the elemental composition used. Electrochemical attributes were investigated through galvanostatic charge–discharge (GCD) cycling and cyclic voltammetry (CV) in a voltage range of 2.5 to 4.8 V. The LiMn2O4sample displayed a charge capacity of 116.5 mAhg-1 and a discharge capacity of 114.3 mAhg-1. The Coulombic efficiency exhibited by this electrode was 98.1%. After 100 cycles, the capacity retention was as high as 75.8%. The electrochemical impedance spectroscopy (EIS) measurements of the LiMn2O4 electrode, including the electrolyte bulk resistance (Rs), charge transfer resistance (Rct), and Warburg Impedance (Wo), were 13.3 ohms, 118.7 ohms, and 0.61 ohms, respectively.

Recently, Metal Organic Frameworks (MOFs) have been widely applied due to their high energy storage capacitance, customizable pore sizes, and open metal sites; however, their application in the form of electrode materials has been restricted due to their poor electrical conductivity. The present study reports the fast synthesis of MIL-53(Fe) and Pd/MIL-53(Fe) using the solvothermal method. To assess the electrochemical potential of materials and better understand the role of palladium in the presence of MOF, the electrodes of materials were constructed and electrochemical performances of both samples were investigated based on cyclic voltammetry in 6 M KOH electrolyte. Due to the existence of Pd in redox reaction and larger surface area, the Pd/MIL-53(Fe) showed greater electrochemical efficiency and higher specific capacitance than MIL-53(Fe). The obtained results also indicated that designing MOF via decoration of noble metal nanoparticle (MOF/noble metal) would find potential applications in the field of supercapacitors and catalysis.