• Bulletin of the Korean Chemical Society
• /
• v.35 no.2
• /
• pp.357-364
• /
• 2014

Size controlled, $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ cathode powders were prepared by co-precipitation method followed by heat treatment at temperatures between 750 and $850^{\circ}C$. The synthesized samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance. The synthesized $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ after calcined at $750^{\circ}C$ has a good electrochemical performance with an initial discharge capacity of $190mAhg^{-1}$ and good capacity retention of 100% after 30 cycles at 0.1C ($17mAg^{-1}$). The capacity retention of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ after calcined at $750^{\circ}C$ is better than that at 800 and $850^{\circ}C$ without capacity loss at various high C rates. This is ascribed to the minimized cation disorder, a higher conductivity, and higher lithium ion diffusion coefficient ($D_{Li}$) observed in this material. In the differential scanning calorimetry DSC profile of the charged sample, the generation of heat by exothermic reaction was decreased by calcined at high temperature, and this decrease is especially at $850^{\circ}C$. This behavior implies that the high temperature calcinations of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ prevent phase transitions with the release of oxygen.

• Fire Science and Engineering
• /
• v.30 no.2
• /
• pp.114-122
• /
• 2016

This study is to analyze the explosion and fire risks due to high temperature and short circuit current of Lithium batteries. This study selected the typical types of Li-polymer batteries and Li-ion batteries as the test samples. The result of explosion risk assessment due to the high temperature showed that, while a Li-polymer battery had $170^{\circ}C$ explosion on average, a Li-ion battery had $187^{\circ}C$ explosion. The measurement result of temperature increase due to short circuit current revealed that, in case that protection circuit module (PCM) was normally working, there was little of temperature increase due to over-current limitation. However, in case that PCM was out of order, the temperature of a Li-polymer battery increased up to an average of $115.7^{\circ}C$ and the temperature of a Li-ion battery increased up to an average of $80.5^{\circ}C$, which showed the higher risks of fire and burn.

• Polymer(Korea)
• /
• v.34 no.6
• /
• pp.517-521
• /
• 2010

Microprous polyethylene (PE) membranes are widely used as lithium-ion battery separators. A separator having higher meltdown temperature than PE separator is still required for useful safety feature at a high temperature. To enhance meltdown temperature of PE separator, it was coated with polymers synthesized from bis-GMA derivatives by radical polymerization. Polymer was not formed when bis-GMA monomer having a high viscosity was used, while polymers were formed when bis-GMA derivatives having a low viscosity were used. When the separator was coated with polymer synthesized from reaction mixture containing proper amount of bis-GMA derivative, its meltdown temperature were increased up to $160^{\circ}C$ without reduction in the air permeability.

• Korean Chemical Engineering Research
• /
• v.47 no.3
• /
• pp.344-348
• /
• 2009

One-dimensional modeling was carried-out to predict the capacity loss of a lithium-ion polymer battery during cycling. The model not only accounted for electrochemical kinetics and ionic mass transfer in a battery cell, but also considered the parasitic reaction inducing the capacity loss. In order to validate the modeling, modeling results were compared with the measurement data of the cycling behaviors of the lithium-ion polymer batteries having nominal capacity of 5Ah from LG Chem. The cycling was performed under the protocol of the constant current discharge and the constant current and constant voltage charge. The discharge rate of 1C was used. The range of state of charge was between 1 and 0.2. The voltage was kept constant at 4.2 V until the charge current tapered to 50 mA. The retention capacity of the battery was measured with 1C and 5C discharge rates before the beginning of cycling and after every 100 cycles of cycling. The modeling results were in good agreement with the measurement data.

• Proceedings of the KIPE Conference
• /
• 2014.11a
• /
• pp.70-71
• /
• 2014

In this paper, an advanced charging strategy for improving the charging performance of the Li-ion polymer battery is proposed, which is based on the battery characteristic. Simulation results show that the proposed charging current pattern can improve the charging speed of battery in comparison with the standard CC-CV (constant current - constant voltage) charging strategy and the pulse-charging strategy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.362-365
• /
• 1999

The electrochemical properties of flyash obtained from combustion of fuel in fossil power plants and their performance as anode material of secondary battery have been investigated Various flysh pellets molded at various molding pressure have been used as anode lithium secondary battery. The best Performance was achieved when flyash pellet molded at pressure of 400kgf/$\textrm{cm}^2$ is utilized, that is, charge capacity of 300kgf/$\textrm{cm}^2$ and Coulombic efficiency of larger than 95% have been achieved. In addition, this battery exhibited good cycling performance. Considering these results, we predicted that utilization of the flyash as anode material and polyaniline conducting polymer as cathode material in a secondary will show capacity of 300mAh/g and Coulombic efficiency of higher than 95%.

• 한국전기화학회:학술대회논문집
• /
• 2001.04a
• /
• pp.41-41
• /
• 2001

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.11
• /
• pp.1224-1229
• /
• 2004

The purpose of this study is to research and develop tin oxide-flyash composite for lithium Ion polymer battery. Tin oxide is one of the promising material as a electrode active material for lithium Ion polymer battery (LIPB). Tin-based oxides have theoretical volumetric and gravimetric capacities that are four and two times that of carbon, respectively. We investigated cyclic voltammetry, AC impedance and charge/discharge cycling of SnO$_2$-flyash/SPE/Li cells. The first discharge capacity of SnO$_2$-flyash composite anode was 639 mAh/g. The discharge capacity of SnO$_2$-flyash composite anode was 563 and 472 mAh/g at 6th and 15th cycle, respectively. The SnO$_2$-flyash composite anode with PVDF-PMMA-PC-EC-LiClO$_4$ electrolyte showed good capacity with cycling.

• 한국전기화학회:학술대회논문집
• /
• 1999.10a
• /
• pp.62-62
• /
• 1999

• 한국전기화학회:학술대회논문집
• /
• 1999.10a
• /
• pp.67-67
• /
• 1999