• Carbon letters
• /
• v.16 no.1
• /
• pp.51-56
• /
• 2015

Carbonate-type organic electrolytes were prepared using propylene carbonate (PC) and dimethyl carbonate (DMC) as a solvent, quaternary ammonium salts, and by adding different contents of 1-ethyl-3-methyl imidazolium tetrafluoroborate ($EMImBF_4$). Cyclic voltammetry and linear sweep voltammetry were performed to analyze conducting behaviors. The surface characterizations were analyzed by scanning electron microscopy method and X-ray photoelectron spectroscopy. From the experimental results, increasing the $EMImBF_4$ content increased the ionic conductivity and reduced bulk resistance and interfacial resistance. In particular, after adding 15 vol% $EMImBF_4$ in 0.2 M $SBPBF_4$ PC/DMC electrolyte, the organic electrolyte showed superior capacitance and interfacial resistance. However, when $EMImBF_4$ content exceeded 15 vol%, the capacitance was saturated and the voltage range decreased.

• Carbon letters
• /
• v.17 no.1
• /
• pp.70-73
• /
• 2016

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.5
• /
• pp.331-337
• /
• 2017

Thermal batteries, reserve power source, is activated by melting of molten salt at the temperature range of $350{\sim}550^{\circ}C$. To immobile the molten state electrolyte when the thermal battery is activated, the binder must be added in electrolyte. Usually, molten salts include 30~40 wt% of MgO binder to ensure electrical insulation as well as safety. However, the conventional MgO binder tends to increase ionic conductive resistance and thus the inclusion of the binder increases the total impedance of the battery. This paper mainly focused on the study of yttria stabilized zirconia (YSZ) as an alternative binder for molten salt. The chemical stability between the molten salt and YSZ is measured by XRD and DSC. And the sufficient path for ionic conduction on molten salt could be confirmed by the enhanced wetting behavior and the enlarged pore size of YSZ. The electrochemical properties were analyzed using single cell tests so that it showed the outstanding performance than that using MgO binder.

• Journal of the Korean Ceramic Society
• /
• v.49 no.3
• /
• pp.241-246
• /
• 2012

Physical properties of plasma electrolytic oxidized layers of 8 different kinds of Al alloys, A-1100, A-2024, A-5052, A-6061, A-6063, A-7075, ACD-7B and ACD-12 were investigated. The electrolyte for plasma electrolytic oxidation was mixture of distilled water, $Na_2P_2O_7$, KOH and some metal salts. Growth rate of oxide layer was slower in $Na_2P_2O_7$ electrolyte system than in $Na_2SiO_3$ system, and Ra50 surface roughness of oxidized layer was below $1.2{\mu}m$. Surface hardness in $Na_2P_2O_7$ electrolyte system is higher than in $Na_2SiO_3$ system, and roughness was lower in $Na_2P_2O_7$ electrolyte system than in $Na_2SiO_3$ system.

• Korean Journal of Materials Research
• /
• v.25 no.12
• /
• pp.694-702
• /
• 2015

Nd-Fe-B permanent magnets have been used in a wide variety of applications because of their high magnetic flux density. So, demand for neodymium has been increasing in worldwide. In this study, an electrowinning process was performed in $LiF-NdF_3-Nd_2O_3$ high temperature molten salts. However, a corrosion resistant material for use in the molten salt must be found for stable operation because of the harsh corrosion environment of the electrowinning process. Therefore, for this paper, boron nitride(BN), aluminum nitride(AlN), and silicon nitride($Si_3N_4$) were selected as protective and structural materials in the high temperature electrolyte. To investigate the characteristics of BN, AlN, and $Si_3N_4$, in molten salts, materials were immersed in the molten salts for 24, 72, 120, and 192 hours. Also, surface condition and stability were investigated by SEM and EDS and corrosion products were calculated by HSC chemistry. As a result, among BN, AlN, and $Si_3N_4$, AlN was found to show the best protective material properties.

• Applied Chemistry for Engineering
• /
• v.22 no.3
• /
• pp.255-260
• /
• 2011

$NH_4{^+}-{\beta}^{{\prime}{\prime}}$-alumina which is expected to an inorganic solid electrolyte of high temperature polymer electrolyte membrane fuel cells (PEMFC) was prepared by ion-exchange reaction of $K^{+}-{\beta}^{{\prime}{\prime}}$-alumina pellet with $NH_4NO_3$ aqueous solution and molten $NH_4NO_3$ salts as an ion-exchange medium in the autoclave and the heating mentle reaction. In the autoclave reaction, the concentrations of $NH_4NO_3$ solution was chosen at 5 and 10 M. Each ion-exchange reaction was carried out at 130, 150, 170, and $200^{\circ}C$ for 2, 4, 6 and 8 h. In the heating mentle reaction, ion-exchange was performed at $200^{\circ}C$ for 2, 4, 6 and 8 h with molten $NH_4NO_3$ salts. In order to determine the effect of reaction times, each ion-exchange reaction was repeated 3 times. The phase stability and the ion-exchange rate of $NH_4{^+}-{\beta}^{{\prime}{\prime}}$-alumina were analyzed by XRD and ICP.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.7
• /
• pp.467-472
• /
• 2015

Thermal batteries are primary power sources for military applications requiring high reliability, robustness and long storage life. Conventional electrodes for thermal batteries are prepared by compacting powder mixtures into pellets. Separator is composed of halide mixture, such as LiCl-KCl eutectic salt, blended with MgO to immobilize the molten salt. In order to increase the power density and energy density, the resistance of electrolyte should be reduced because the resistance of electrolyte is predominant in thermal batteries. In this study, wetting behaviors and impregnation weight of molten salts as well as the micro structures of ceramic felt were investigated to be applicable to thin electrolyte. Discharge performances of single cell with the ceramic separator impregnated by molten salt were evaluated also. Zirconia felt with high porosity and large pore outperformed alumina felt in wetting characteristics and molten salt impregnation as well as discharge performances. Based on the results of this study, ceramic felt separator impregnated with molten salt have revealed as an alternative of conventional thick MgO based separator with no conspicuous sign of thermal runaway by short circuit.

• Journal of the Korean Ceramic Society
• /
• v.42 no.12 s.283
• /
• pp.827-832
• /
• 2005

In this study, thin electrolyte layer was prepared by 8YSZ ($8mol\%$ Yttria-Stabilized Zirconia) slurry dip and sol coating onto the porous anode support in order to reduce ohmic resistance. 8YSZ polymeric sol was prepared from inorganic salt of nitrate and XRF results of xerogel powder exhibited similar results $(99.2\pm1wt\%)$ compared with standard sample (TZ-8YS, Tosoh Co.). The dense and thin YSZ film with $1{\mu}m$ thickness was synthesized by coating of 0.7M YSZ sol followed by heat-treatment at $600^{\circ}C$ for 1 h. Thin film electrolyte sintered at $1400^{\circ}C$ showed no gas leakage at the differential pressure condition of 3 atm.

• Analytical Science and Technology
• /
• v.8 no.4
• /
• pp.675-682
• /
• 1995

Thin films of buckminsterfullerene($C_{60}$) formed by solution drop casting on Pt foil electrode surfaces were studied by cyclic voltammetry(CV) in acetonitrile(MeCN) containing quaternary ammonium or alkali-metal salts as supporting electrolyte. The electrochemical behaviors of $C_{60}$ films are found to be strongly dependent on the nature of the supporting electrolytes, especially with tetrabutyl ammonium perchlorate (TBAP, $NBu_4ClO_4$), and tetrabutyl ammonium tetrafluoroborate ($TBABF_4$, $NBu_4BF_4$). Reasonably stable films are formed into which electrons can be injected. The interaction of $C_{60}$ film with the quaternary ammonium cation may produce the fulleride salts $(TBA^+)(C{_{60}}^-)$ and $(TBA^+)_2(C{_{60}}^{2-})$. The bulk electroreduction with a controlled potential to generate the soluble $C{_{60}}^{3-}$ anions(dark red-brown color) is followed by electrooxidative deposition to produce a neutral $C_{60}$ film on the surface. The peak currents($I_{pc}$ and $I_{pa}$) of these thin film were dramatically decreased with repetitive potential scanning. These results could be explained by the adsorption-desorption phenomena and ion pairing interaction of reduced species($C{_{60}}^-$, and $C{_{60}}^{2-}$) onto the electrode surface. The peak current changes and peak potential shifts of the thin $C_{60}$ film in cyclic voltammograms formed from solution were observed by varying scan rates.

• 한국전기화학회:학술대회논문집
• /
• 1998.12a
• /
• pp.153-166
• /
• 1998

Lithium ion Batteries commercially available since the early nineties in Japan are going to be more and more important for portable electronic devices and even EV applications. Today several companies around the world are working hard to join to market for Lithium secondary batteries. Based on the growing interest for commercial use of batteries also the materials have to be reviewed in order to meet large scale production needs. The requirements especially for electrolytes for lithium batteries are extremely high. The solvents and the lithium salts should be of highest purity. So the supply of these chemicals including packaging, transportation and storage but also the handling in production are critical items in this field. Frolic impurities are very critical for LiPF6 based electrolytes. The influence of water is tremendous. But also the other protic impurities like alcoholes are playing an Important role for the electrolyte quality. The reaction of these species with LiPF6 leads to formation of HF which further reacts with cathode materials (spinel) and anode. To understand the role of the protic impurities more clearly the electrolyte was doped with such compounds and was analyzed for protic impurities and HF. These results which directly show the relation between impurities and quality will be presented and discussed. In addition several investigations on different packaging materials as well as methods to analyze and handle the sensititive material will be addressed. These questions which are only partly discussed in literature so far and never been investigated systematically cover some of the key parameters for understanding of the battery chemicals. This investigation and understanding however is of major importance for scientist and engineers in the field of Lithium ion and Lithium polymer batteries.