• Polymer(Korea)
• /
• v.26 no.1
• /
• pp.45-52
• /
• 2002

The separator made from the blends of high density polyethylene (HDPE) and ultrahigh molecular weight polyethylene (UHMWPE) was prepared by wet processing to use as Li-ion secondary battery. We investigated effects of the blending of the polymers and the film extension on the mechanical properties of the separator. The mechanical strength of separator increased with increasing molecular weights and contents of UHMWPE, for instance about $1000 kg/\textrm{cm}^2$ with the five times extended film of 6 wt% UHMWPE. The pores of the separator were very uniform with the size of 0.1~$0.12\mu\textrm{m}$. The shut-down characteristic quickly increased at around $130^{\circ}C$ and the fusion temperature was $160^{\circ}C$, so it could be applied to the lithium ion secondary battery.

• Journal of the Korean Electrochemical Society
• /
• v.19 no.4
• /
• pp.123-128
• /
• 2016

In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based gel polymer electrolyte incorporating nano-size $Al_2O_3$ ceramic particle was prepared by electrospinning. The gel polymer electrolyte (GPE) incorporated with $Al_2O_3$ ceramic particle showed higher ionic conductivity of $9.5{\times}10^{-2}Scm^{-1}$ than pure PVdF-HFP GPE without ceramic particle and improved the electrochemical stability up to 5.2 V. The GPEs were assembled with $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ (NMC) cathode for electrochemical test. The GPE batteries at 0.1 C-rate delivered $168.2mAh\;g^{-1}$ for pure GPE and $189.6mAh\;g^{-1}$ for hybrid GPE, respectively. Therefore, the incorporation of high dielectric constant ceramic particle will be good strategy to enhance the stability and electrochemical properties of lithium ion gel polymer batteries.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.2
• /
• pp.142-147
• /
• 2005

In this work, a gel polymer electrolyte (GPE) was prepared using polyoxyalkylene glycol acrylate (POAGA) as a macromonomer LiCoO$_2$/GPE/graphite cells were prepared and their electrochemical properties were evaluated at various current densities and temperatures. The ionic conductivity of the GPE was more than 6.2${\times}$10$^{-3}$ S$.$$cm^{-1}$ / at room temperature. The GPE had good electrochemical stability up to 4.5 V vs. Li/Li$^{+}$. POAGA-based cells were showed good electrochemical performances such as rate capability, low-temperature performance, and cycleability. The cells, also, passed a safety test such as the overcharge and nail-penetration test.t.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.1
• /
• pp.36-42
• /
• 2007

In general, the battery and the(electric) condenser are pictured as electrical energy storage devices. Although there were lots of inventions and utilizations of morden conveniences according to enormous growth of the science and technologies after the Industrial Revolution, a speed of technology development on these devices being closely used in civilized human lives and many electric or electronic systems as a core component are relatively slower to the other fields of technologies. Nevertheless, based on a remarkable progress of the material science and technologies for the last ten years, a new type of electrical energy storage device so called as 'electrochemical capacitors' are being developed and used practically. The electrochemical capacitors exhibit their own characteristics of much enhanced capacitance over the conventional condensers and also distinctively exhibit a longer lift time and higher power capability that the nickel hydrogen batteries and secondary batteries such as lithium ion and polymer batteries does not show up so for. Hence, in this paper, it is intended to introduce a fundamental understanding and updated technology trends on the electrochemical capacitors.

• Polymer(Korea)
• /
• v.31 no.4
• /
• pp.297-301
• /
• 2007

In this work, polymer/(layered silicate) nanocomposites (PLSN) based on poly (ethylene oxide) (PEO), ethylene carbonate (EC) as a plasticizer, lithium salt ($LiClO_4$), and sodium montmorillonite ($Na^+-MMT$) or organic montmorillonite (organic MMT) clay were fabricated. And the effects of organic MMT on the polymer matrix were investigated as a function of ionic conductivity. For the application to electrolytes an Li batteries, polymer electrolytes containing the organic nanoclays were used in this work. As a result, the spacing between layers and hydrophobicity of the organic nanoclays were increased, affecting on the exfoliation behaviors of the MMT layers in clay/PEO nanocomposites. From ion-conductivity results, the organic-MMT showed higher values than those of $Na^+-MMT$, and the MMT-20A sample that was treated by methyl dihydrogenated tallow ammonium, showed the highest conductivity in this system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05c
• /
• pp.88-90
• /
• 2003

The purpose of this study is to research and develop tin oxide-flash 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 and charge/discharge cycling of SnO-flyash/SPE/Li cells. The first discharge capacity of SnO-flyash composite anode was 720 mAh/g. The discharge capacity of SnO-flyash composite anode 412 and 314 mAh/g at cycle 2 and 10 at room temperature, respectively. The SnO-flyash composite anode with PVDF-PMMA-PC-EC-$LiClO_4$ electrolyte showed good capacity with cycling.

• 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.

• Polymer(Korea)
• /
• v.37 no.1
• /
• pp.22-27
• /
• 2013

In this study, we prepared separators with improved thermal stability by coating microporous polyethylene (PE) film for lithium secondary battery using poly(meta-phenylene isophthalamide) (Nomex). The mechanical and thermal properties of prepared separators were evaluated by thermal stability test and TMA as a function of the Nomex concentration and coating parameters. The corresponding coated PE separator showed better thermal and mechanical properties than the original PE separator. Electrochemical properties were also assessed by ionic conductivity, cyclic voltammetry and charge/discharge cycle.

• Polymer(Korea)
• /
• v.38 no.6
• /
• pp.827-831
• /
• 2014

An organic radical polymer (ORP) was prepared by radical polymerization and following oxidation into nitroxyl radical. Two different oxidation methods were employed and their radical concentrations were measured using electroparamagnetic resonance spectroscopy (EPR) and UV-visible absorption (UV-vis) spectroscopy. From these measurements, $H_2O_2-Na_2WO_4$ oxidation method exhibited a complete oxidation, which resulted in 97.6% spin concentration. Also, it was revealed that convenient and cheap UV-vis measurement was useful for preliminary radical concentration comparison. After applied as a cathode material in lithium ion batteries, ORP electrode showed a high initial capacity ($110mAh\;g^{-1}$), a good initial efficiency (96%), a very high rate performance (70% charging during 1.2 min) and stable cycle performance.

• Polymer(Korea)
• /
• v.34 no.1
• /
• pp.74-78
• /
• 2010

In this paper, crosslinked polyethylene (PE) separators for lithium secondary batteries were prepared by an electron beam irradiation under various beam currents and dose rates. The crosslinking degree increased up to maximum 71% with an increasing absorption dose and with a decreasing beam current. The PE separators irradiated at lower beam currents showed better thermal shrinkage (51%) and mechanical properties than the original PE separator and PE separators irradiated at higher beam current. The ionic conductivity ($1.01{\times}10^{-3}\;S/cm$) and electrolyte uptake (275%) of the crosslinked PE separators were comparable to the original PE separator.