Papers by Keyword: Secondary Lithium Battery

Abstract: Modified membrane separators with lower cost using non-woven Polypropylene (PP) were widely used in the field of the secondary lithium batteries. Sulfonation is one of the most commonly modified methods for the surface modification of polymers. In order to make it effective in industry production, plasma surface treatment is applied to one, and it is an effective surface activation technology without changing its original properties. The characteristic properties of modified PP membrane separators have been studied by Alkali Absorption property Test, Tensile Strength Test, Fourier-Transform Infrared Measurements (FTIR), Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS). Sulfonic acid groups in the polymer membranes were evidenced by the FTIR and the XPS spectroscopy. The results showed that the plasma sulfonation treatment reaction was very effective to improve the surface hydrophilicity of the non-woven membranes. The suitable sulfonation process could keep the lower cost in industry production.

Abstract: Lithium sulfide (Li2S)-carbon composite positive electrodes were prepared by the spark-plasma-sintering (SPS) process for use in rechargeable lithium batteries. By the SPS treatment of Li2S and acetylene black (AB) blended powder, the strong binding between the active materials and the carbon powders were formed. Such contact effect improved the electrochemical performance of the cells with liquid electrolytes (1M LiFP6/(EC+DMC)), probably due to the increase in conductivity of the positive electrodes, though the samples prepared by the ball-milling process showed no significant capacity in the electrochemical tests.

Abstract: The porous TiO2 layer on the silicon surface not only acts as a buffer layer to relieve the strain associated with the volume expansion but also prevents the aggregation of the particles upon normal cycles of charging and discharging. The control of the optimum amount of catalyst has led to enhance the cycle performance of TiO2 coated silicon anode.

Abstract: Spherical Li[Ni(1/3-x)Mn(1/3-x)Co(1/3-x)Mx]O2 (M=Fe, Mg, Al) precursor powders were synthesized by ultrasonic spray pyrolysis using aqueous solution of metal nitrate. X-ray diffraction (XRD), scanning electron microscope (SEM), BET method using N2 adsorption analysis and Battery tester were used for determination of the composition, morphology, particle size, surface area and electrochemical properties. SEM observation showed that the size of as-prepared particles were about 0.9 μ with narrow size distribution. The crystal phase of Li[Ni(1/3-x)Mn(1/3-x)Co(1/3-x)Mx]O2 (M=Fe, Mg, Al) was resulted in layered rock salt structure with R3m space group by calcinations at 1023 K for 10 h. No impurity-related peaks are observed from the XRD pattern with various doping metals. Mg and Al doped Li(Ni1/3Co1/3Mn1/3)O2 showed very good cycling stability. The Mg substitution for Ni led to the most excellent. On the other hand, the capacity degradation during cycling was observed by Fe substitution for Mn doped Li(Ni1/3Co1/3Mn1/3)O2.

Abstract: Spherical LiNi0.5Mn1.5O4 powders were prepared by internal combustion type spray pyrolysis apparatus using gas burner. The powder production capacity was 1 kg/h by this equipment. After calcinations of as-prepared powders contained Ni at different temperatures from 800 to 1200 °C in air for 10h, LiNi0.5Mn1.5O4 powders were obtained. As-prepared particles have a porous microstructure with an average diameter of about 5 μm with narrow size distribution. XRD showed that LiNi0.5Mn1.5O4 powders were well crystallized to a spinel structure with Fd3m space group. LiNi0.5Mn1.5O4 powders calcined at 1000°C show good cycle performance with after 30 cycles discharge capacity of 112mAh/g and 95% retention after 400 cycles between 3.5 V and 5 V.

Abstract: The series of partially Al-substituted lithium manganese oxides were prepared by spray pyrolysis process from spray solutions with citric acid and ethylene glycol. The as-prepared particles obtained from spray solution with citric acid and ethylene glycol turned to fine-sized LiMn(12- x)/6Alx/6O4(0.05≤x≤2) particles with regular morphology after post-annealing. The discharge capacities of the particles post-annealed at temperature of 800oC changed from 128 to 84 mAh/g when the x of the LiMn(12-x)/6Alx/6O4 particles was changed from 0 to 2. The Al-doped LiMn2O4 fine particles prepared by spray pyrolysis from spray solution with citric acid and ethylene glycol had good cycle properties.

Abstract: Carbonaceous material has been used as an anode in lithium-ion secondary batteries due to their good stability during charging and discharging. But this material has the problems like irreversible capacity and low specific capacity that is about 372mAh/g. Because of the problems as stated above, silicon-based materials have been reported as possible anode materials to replace carbon. But they have high electrical resistivity and large volume changes associated with alloying and dealloying of lithium during electrochemical cycling. This study is performed to obtain higher capacity of anode material with a good cycle performance and to reduce electrical resistivity. It is expected that phosphor doping silicon and graphite mixture exhibit higher capacity than that of raw graphite and the doping of phosphorous will be able to decrease electrical resistivity of anode materials.

Abstract: Electrochemical properties and microstructure evolution during lithiation and delithiation of Ni3Sn2 single crystals with the hexagonal B82-type related ordered structure have been studied as a function of the crystal orientation by charge/discharge tests, powder X-ray diffraction and transmission electron microscopy. Charge and discharge capacities are strongly dependent on the crystal orientation. When the surface of the thin plate anode is perpendicular to the basal plane of the parent B82 unit cell, the capacities are approximately twice as high as those for the sample whose surface is parallel to the basal plane, which is considered to be related to the difference in the diffusion behavior of lithium with respect to the crystal orientation.

Abstract: In order to enhance the electrochemical performance of lithium metal as an anode of lithium secondary battery, we prepared DLC film coating with various morphologies using a radio-frequency chemical vapor deposition method. Raman spectroscopy and FT-IR analyses revealed that the DLC film consists of mixture of graphitic sp2 and aliphatic sp3 hybridized bonds. DLC coating on lithium metal electrode play an important role as a passive layer during electrochemical reaction. Based on experimental results, we expected that the well dispersed DLC film coating sector as small as possible on the lithium metal electrode exhibits excellent electrochemical performance such as irreversible capacity and cycling performance.

Abstract: Spherical Li
Ni1/3Mn1/3Co1/3O2 precursor powders were synthesized by aerosol plasma pyrolysis using aqueous solution of metal nitrate. XRD, SEM, TEM and BET analysis were used for determi- nation of the composition, morphology, particle size and surface area. SEM observation showed that the size of as-prepared particles were about 200 nm. The value of geometrical standard deviation (σg) calculated from the particle size distribution was 1.20, suggesting that the particle size distribution was narrow. The crystal phase of Li
Ni1/3Mn1/3Co1/3O2 was resulted in layered rock salt structure with R3m space group. The rechargeable capacity of Li
Ni1/3Mn1/3Co1/3O2 was about 142-175 mAh/g. The discharge capacity of Li
Ni1/3Mn1/3Co1/3O2 decreased with increasing cycle number. However, the cycling stability of Li(Ni1/3Mn1/3Co1/3)O2 powders that aerosol plasma pyrolysis process offered superior performance to ultrasonic spray pyrolysis process.