• Journal of the Korean Electrochemical Society
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• v.25 no.3
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• pp.105-112
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• 2022

For the commercialization of all-solid-state batteries, it is essential to develop a solid electrolyte that can be operable at room temperature, and it is necessary to manufacture all-solid-state batteries by adopting materials with high ionic conductivity. Therefore, in order to increase the ionic conductivity of the existing oxide-based solid, Li₇La₃Zr₂O₁₂ (LLZO) doped with heterogeneous elements was used as a filler material (Al and Nb-LLZO). An electrolyte with garnet-type inorganic filler doped was prepared. The binary metal element and the polymer mixture of poly(ethylene oxide)/poly(propylene carbonate) (PEO/PPC) (1:1) are uniformly manufactured at a ratio of 1:2.4, The electrochemical performance was tested at room temperature and 60 ℃ to verify room temperature operability of the all-solid-state battery. The prepared composite electrolyte shows improved ionic conductivity derived from co-doping of the binary elements, and the PPC helps to improve the ionic conductivity, thereby increasing the capacity of all-solid-state batteries at room temperature as well as 60 ℃. It was confirmed that the capacity retention rate was improved.

• Proceedings of the Korean Society of Rheology Conference
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• 2003.05a
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• pp.69-72
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• 2003

No Abstract, See Full Text

• Polymer(Korea)
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• v.29 no.4
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• pp.403-407
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• 2005

In this work, the solid polymer electrolyte (SPE) composites, which are composed of poly(ethylene oxide) (PEO), mesoporous mobil crystalline material-41 (MCM-41), and lithium salt, are prepared in order to investigate the influence of MCM-41 contents on the ionic conductivity of the composites. The crystallinity of the SPE composites was evaluated using differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The ionic conductivity of the SPE composites was measured by the frequency response analyzer (FRA). As a result, the addition of MCM-41 into the polymeric mixture prohibited the growth of PEO crystalline domain due to the mesoporous structures of the MCM-41. The $P(EO)_{16}LiClO_4$/MCM-41 electrolytes show an increased ion conductivity as a function of MCM-41 content up to 8 $wt\%$ and a slightly decreased conductivity over 8 $wt\%$. These ion conductivity characteristics are dependent on a change of polymer crystallinity in the presence of MCM-41 system.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.758-763
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• 2011

In this work, polymer composite electrolytes were prepared by a blend of poly(methyl methacrylate) (PMMA) and poly(ethylene oxide) (PEO) as a polymer matrix, propylene carbonate as a plasticizer, $LiClO_4$ as a salt, and by containing a different content of $TiO_2$, by using the solution casting method. The crystallinity and ionic conductivity of the polymer electrolytes was evaluated using X-ray diffraction(XRD) and AC impedance method, respectively. The morphology of composite electrolyte film was analyzed by SEM method. From the experimental results, by increasing the $TiO_2$ content, crystallinity of PEO was reduced, and ionic conductivity was increased. In particular, the ionic conductivity was dependent on the content of $TiO_2$ and showed the highest value 15 wt%. However, when $TiO_2$ content exceeds 15 wt%, the ionic conductivity was decreased. According to the surface morphology, the ionic conductivity was decreased because the polymer composite electrolytes showed a heterogenous morphology of fillers due to immiscibility or aggregation of the filler within the polymer matrix.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.04a
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• pp.28-30
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• 2008

Poly(ethylene oxide)(PEO) of molecular weight of 300,000 was crosslinked by exposure to UV irradiation. Photochemical crosslinking of PEO occurred by UV irradiation and the presence of benzophenone in the film which acts as a hydrogen-abstracting agent. Percent conversion of the polymer into gel as well as water absorbency were investigated gravimetrically. Gel fraction and water absorbency of PEO films increased with increasing UV energy. In case of photocrosslinked PEO films with benzophenone, gel fraction increased up to about 90%. The thermal behavior of crosslinked PEO films was studied by thermogravimetric analysis. The maximum decomposition temperature increased with increasing UV energy and benzophenone concentration.

• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1194-1198
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• 1998

The density and the viscosity of aqueous PEO solutions are observed with the several concentrations of PEO at 20 ℃. The effects of urea on them are also observed. The apparent and the partial specific volumes of PEO are calculated from the density data, which result that the polymer-polymer interaction is dominating in the binary aqueous PEO solutions, while the polymer-solvent interaction is dominating in the ternary aqueous urea-PEO solutions. It is explained by the urea induced breakage of the structured water originated from the hydrophobic interactions and the binding of the urea to the PEO chain. The concentration dependence of relative viscosity and the density dependence of fluidity is also discussed with the concept of the polymersolvent and the polymer-polymer interactions of aqueous urea-PEO solutions.

• Polymer(Korea)
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• v.33 no.5
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• pp.485-489
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• 2009

The temperature dependence of the structure of micelles formed by a deuterated polystyrene-poly(ethylene oxide) diblock copolymer (dPS-PEO) in heavy water were investigated with small-angle neutron scattering (SANS). SANS data were analyzed using the hard-sphere structure factor in combination with the form factor of a core-shell model. The micelle aggregation number and corona radius were obtained from the fits to the SANS data. The micelle aggregation numbers varied with temperature from 229 at $25^{\circ}C$ to 240 at $45^{\circ}C$, with a corresponding increase in the core radius. However, the shell thickness of micelles decreased with increasing temperature from 6.2 to 5.8 nm. These structural changes of micelles might be ascribed to the decrease in the hydration volume per hydrophilic group in the corona because of the increase in hydrophobicity of the PEO block with increasing temperature.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.144-150
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• 2004

Various experimental factors that affect the separation of bacteria were investigated using capillary electrophoresis. At different buffer concentrations, gram-positive bacteria and gram-negative bacteria showed somewhat different migration behavior under high electric filed. The separation efficiency was also investigated as a function of concentration of bacterium injected into the capillary. In order to separate bacteria as the difference of size and shape, water soluble polymers such as poly(ethylene)oxide (PEO), polyvinylpyirrolidone (PVP), and dextran were studied. PEO, which is more flexible and has lower steric hinderance, showed the best separation efficiency. The mixed bacteria sample of Micrococcus lysodeikticus as gram-positive bacteria and Aerobacter aerogenes as gram-negative bacteria were successfully analyzed with PEO.

• Polymer(Korea)
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• v.26 no.6
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• pp.785-791
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• 2002

The effect of the supercritical carbon dioxide (sc$CO_2$) on ion-conductive behaviors for polyether electrolytes based on, both poly (ethylene oxide) (PEO) and poly [oligo (oxyethylene glycol) methacrylate] (PMEO) with lithium triflate, LiCF$_3$SO$_3$, has been investigated. In particular, the present research is a new concept for improving the ionic conductivity of polyether electrolytes. The maximum ionic conductivity ($\sigma$$_{max}$) at room temperature of the PEO electrolyte was more than 100 times higher, and the $\sigma$$_{max}$ at 9$0^{\circ}C$ of the PMEO electrolyte was 30 times improved by the se$CO_2$ treatment, respectively. It was revealed that the penetration of $CO_2$ molecules into the polymer matrix causes the increase of carrier ions by ion-dispersion effect and the decrease of glass transition temperature (T$_{g}$) by plasticizing effect that results in the improvement of the ion transport behaviors.viors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.471-475
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• 2006

Filling the microchannels is very important in designing micro-injection molding, microdevices, etc. In this paper, flow dynamics was studied in injection molding with microchannels. A transparent PMMA mold was designed and the flow dynamics was observed. The experiment was performed using poly (ethylene oxide) (PEO) and polyacrylamide (PA) aqueous solutions. The transignt dynamic flow and flow competition between the base plate and the microchannels were observed. The flow observation was used to explain previous filling length results in microchannels during micro-injection molding.