Papers by Keyword: Lithium Battery

Abstract: Synthesis of LiFe_1-xGd_xPO₄/C with (x = 0.01; 0.05; 0.07) have been carried out using a solid-state method from LiH₂PO₄, Fe₂O₃, Gd₂O₃, and Carbon. Al reactant are mixed and mashed with a ball milling for 8 hours, then heated at 80°C for 2 hours to evaporate free water. To complete the reaction, the sample then was sintered at two different temperature; first at 350°C for 6 hours and continue at 830°C for 10 hours under Argon gas (Ar) atmosphere. The sintered powder was characterized by XRD to determine the structure and phase purity. Sample LiFe_1-xGd_xPO₄/C (x = 0.01; 0.05; 0.07) was adopted orthorhombic crystal structure and pnma space group, and no impurities detected. In general, the lattice parameter decreases with increasing Fe concentration, because of the size of the Fe³⁺ ion is smaller than that Gd³⁺ ion. Conductivities of LiFe_0.93xGd_0.07PO₄/C, LiFe_0.95Gd_0.05PO₄/C and LiFe_0.99Gd_0.01PO₄/C are 2.17 x 10^-4 S/cm, 1.54 x 10^-4 S/cm, and 2.02 x 10^-4 S/cm, respectively.

Abstract: Lithium Nickel Manganese Cobalt Oxide (LiNi_0.75Mn_0.15Co_0.10O₂: NMC) is become interested materials for lithium battery applications due to high specific energy and low cost. The pure phase and well-ordered layered structure has been synthesized by co-precipitation method. In this study, the Nickel-rich LiNi_0.75Mn_0.15Co_0.10O₂ positive electrode powder was prepared using co-precipitation method. The influence of synthesis parameters such as calcination temperature, time and amount of water for rinse a NaOH and NH₄OH were studied. Then, phase formation and structure were studied by X-ray Powder Diffraction (XRD). The morphological changes is also confirmed by scanning electron microscope (SEM). A checking weight loss by thermo gravimetric Analysis (TGA). Finally, the optimum parameter to prepare highest pure NMC powder are rinse suddenly until pH 7 and calcination only single1 step.

Abstract: Chitosan has been applied widely in electrical energy storage purposes like battery and fuel cell, as in electrolyte. This research purposed on improving compatibility chitosan as material for electrical energy storage by chemical reaction. Carboxymethylation reaction performed on chitosan to add carboxymethyl groups in either hydroxyl or amine sites or both. The substitution result could effect by optimizing in the ratio of reactants and reaction condition. Carboxymethylation process on chitosan will confirm by FTIR analysis and degree of carboxymethyl substitution can be calculated from 1H NMR. Its ionic conductivity will calculate from EIS. The highest degree of substitution obtained at 64.64%. This reaction had the ratio of chitosan:monochloroacetic acid about 1:6 (m/m) and was reacted in reflux system at 65°C. EIS analysis showed improvement of carboxymethyl chitosan’s conductivity where pure chitosan had 2.7 x 10^-6 Scm^-1 and CMC-IV had 2.7 x 10^-5 Scm^-1 at room temperature.

Abstract: The hydrolytic lignin derivatives have been prepared via its physical activation (high-temperature heating in vacuum) followed by chemical modification (fluorination). The obtained products were characterized using scanning electron microscopy, X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. It was found that the graphitized product of thermal activation up to 1000 °C at a low rate of < 2 °C/min under high vacuum shows an enhanced specific surface area (215 m²/g), that makes its potentially useful as sorbent, catalytic substrate or electrode material. To clarify the potentialities of hydrolytic lignin derivatives for energy storage and conversion, the electrochemical system with metallic lithium anode was applied. The galvanostatic discharge of battery at a current density of 100 μA/cm² between 3.0 and 0.5 V shows that the specific capacity of thermally activated derivative is equal to 845 mA·h/g, while the untreated lignin yields only 190 mA·h/g. The improve of the electrochemical performance of product originates from its graphitization, increasing electronic conductivity, and, possibly, enhanced ability to adsorb of oxygen. The fluorination of both the lignin and its thermally activated form results in higher operating voltage of battery, as seems, due to the involvement of fluorine bound to carbon in electrochemical process.

Abstract: In this paper, the influence of the lignin extraction method (Klason lignin and alkaline lignin) from natural raw materials (husks of rice, buckwheat, sunflower and rice straw) on its electrochemical behavior has been studied. The chemical composition and physical features were characterized by EDX, XRD, IR, and ¹³C NMR methods. Electrochemical behavior of the lignins was investigated by galvanostatic discharge vs. Li⁺/Li. The most promising method of delignification from the point of view of practical application as lithium cell electrode was discussed. The results demonstrate the potential of lignin based battery to be used as a cathode material for a low-rate power sources.

Abstract: In situ chemical oxidation polymerization of pyrrole on the surface of sulfur/multi-walled carbon nanotube particle was carried out to synthesize a novel polypyrrole coated sulfur/multi-walled carbon nanotube (PPy@S/MWCNT) composite. The sulfur/multi-walled carbon nanotube composite (S/MWCNT) was prepared by a facile quasi-emulsion template method in an oil/water system. The ternary PPy@S/MWCNT composite was characterized by elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurements. In the composite, polypyrrole works as a conducting matrix as well as a coating agent, confining the active materials within the electrode, while the MWCNT creates a highly conductive and mechanically flexible framework, hence enhancing the electronic conductivity and the rate capability of the material. This ternary composite exhibits stable cyclability, retaining a discharge capacity of 612 mAh g^-1 at 0.1 C after 100 cycles. Furthermore, up to 1.5 C rate, the ternary composite still delivered a highly reversible discharge capacity of 463 mAh g^-1.

Abstract: A novel sulfur/polypyrrole/graphene nanosheet composite (S/PPy/GNS) was synthesized and investigated as a promising cathode material. This ternary composite was prepared via in situ polymerization of pyrrole monomer with nanosulfur and GNS aqueous suspension followed by heat-treatment. Scanning electronic microscopy observation revealed the formation of a highly porous structure consisting sulfur and polypyrrole coating on the GNS surface. In this composite, GNS works as nanocurrent collector and enhances the conductivity of the composite, and polypyrrole with its high adhesion ability to GNS could act as a binder to connect sulfur and GNS. The resulting S/PPy/GNS composite cathode exhibits high and stable specific discharge capacities of 991 mAh g^-1 after 50 cycles at 0.1 C and good rate capability.

Abstract: Lithium ion battery is composed of three main parts, i.e. cathode, anode and electrolyte. In this work, we investigated the effect of LiFePO₄ cathode composite’s thickness on performances of lithium battery. LiFePO₄ cathode was prepared in a slurry that consisted of lithium iron phosphate (LiFePO₄) powder as active material, acetylene black as conductive additive, polyvinylidene fluoride (PVDF) as binder, and N-methyl-2-pyrrolidone (NMP) as solvent. The slurry was then deposited on the aluminum substrate using doctor blade method in different thickness. The cathode layers were deposited with the thickness of 150, 200, 250 & 300 μm. The structure characterization of the material was analyzed by XRD, while the material’s morphology was analyzed by Scanning Electron Microscope (SEM). Performances of lithium ion battery with LiFePO₄ cathode were evaluated using charge-discharge cycle test. It is found that battery made of cathode layer with 250 μm thickness shows the best performances.

Abstract: A lithium battery was composed of anode, cathode, and separator. The performance of lithium battery was influenced by the thickness of film, the composition of material, and the effect of surfactant and binder. This research investigated the effect of the anode film thickness to the electrochemical performances of lithium battery. Mesocarbon microbeads (MCMB) and lithium iron phosphate (LiFePO₄) were used respectively as anode and cathode. Mesocarbon microbeads, carbon black (conductive agent), polyvinylidene fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent were mixed well to produce slurry. The slurry were then coated, dried and pressed. The anode had various thickness of 50 μm, 70 μm, 100 μm, and 150 μm. The cathode film was made with certain thickness. The performance of lithium battery was examined by Eight Channel Battery Analyzer, the composition of the anode sample was examined by XRD (X-Ray Diffraction), and the crystal structure of the anode sample was analyzed by SEM (Scanning Electron Microscope). The research showed that the thickness of anode film of 100 μm gave the best performance. The battery performance decreased if the thickness was more than 100 μm. The best performance of battery voltage were between 3649 mV and 3650 mV.

Abstract: SVPWM is widely used in power electronic transformation system for it has high voltage utilization ratio and small THD. The InfineonXMC4500 MCU is used as the control core in the lithium battery charge and discharge control system which has three-phase SVPWM rectifier/inverter circuit topology. The mathematical model of the system, the circuit structure, control strategy and software process are introduced in the paper, through the test the results verify the validity of the system.