• 한국재료학회지
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• 제29권2호
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• pp.121-128
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• 2019

Supercapacitors are attracting much attention in sensor, military and space applications due to their excellent thermal stability and non-explosion. The ionic liquid is more thermally stable than other electrolytes and can be used as a high temperature electrolyte, but it is not easy to realize a high temperature energy device because the separator shrinks at high temperature. Here, we report a study on electrochemical supercapacitors using a composite electrolyte film that does not require a separator. The composite electrolyte is composed of thermoplastic polyurethane, ionic liquid and fumed silica nanoparticles, and it acts as a separator as well as an electrolyte. The silica nanoparticles at the optimum mass concentration of 4wt% increase the ionic conductivity of the composite electrolyte and shows a low interfacial resistance. The 5 wt% polyurethane in the composite electrolyte exhibits excellent electrochemical properties. At $175^{\circ}C$, the capacitance of the supercapacitor using our free standing composite electrolyte is 220 F/g, which is 25 times higher than that at room temperature. This study has many potential applications in the electrolyte of next generation energy storage devices.

• 한국수소및신에너지학회논문집
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• 제29권5호
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• pp.442-449
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• 2018

Research on High temperature polymer electrolyte fuel cell (HT-PEMFC) has actively been conducted all over the world. Since the HT-PEMFC can be operated at a high temperature of $120-180^{\circ}C$ using phosphoric acid-doped polybenzimidazole (PBI) electrolyte membrane, it has considerable advantages over conventional PEMFC in terms of operating conditions and system efficiency. However, If the thermal distribution is not uniform in the stack unit, degradation due to local reaction and deterioration of lifetime are difficult to prevent. The thin plate separator reduces the volume of the fuel cell stack and improves heat transfer, consequently, enhancing the cooling effect. In this paper, a large area flow field of thin plate separator for HT-PEMFC is designed and sub-stack is fabricated. We have studied stack performance evaluation under various operating conditions and it has been verified that the proposed design can achieve acceptable stack performance at a wide operating range.

• 한국세라믹학회지
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• 제45권8호
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• pp.464-471
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• 2008

The electrolyte separator for thermal battery should be easily handled and loaded a large amount of the molten salt. Ceramic fibers, especially fibrous commercial glass filters were used as an electrolyte separator and the lithium based molten salts were infiltrated into the ceramic filters. The pore structures of the ceramic filter and the melting properties of the lithium salts affected to the electrolyte loading and leakage. During the infiltration, ions of $Li^+$ and $F^-$ in the molten salts were reacted with the glass fiber and caused to be weaken the fiber strength.

• 한국세라믹학회지
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• 제46권6호
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• pp.648-652
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• 2009

Ceramic fiber separator is the promising material for thermal battery system because it reduces the production cost and offers the potential to a new application compared to a pellet type electrolyte. The electrolyte separator for thermal battery should be easily handled and loaded a large amount of the molten lithium salt. Ceramic fibers were used as an electrolyte separator and the lithium based molten salts were infiltrated into the ceramic filters. Leakage of molten salt (several lithium salts) leads to short-circuit during the thermal battery operation. In this study, a uniform and fine SiOC mat with fibers ranging from 1 to 3 ${\mu}m$ was obtained by electrospinning of polycarbosilane and pyrolysis. The optimum spinning conditions for obtaining fine diameters of SiOC fiber were controlled by the solution composition and concentration, applied voltage and spinning rate, release rate by porosity. The pore structures of the ceramic filter and the melting properties of the lithium salts affected to the electrolyte loading and leakage. The importance of the fiber size and porosity and their control was discussed and the mechanical properties were also discussed.

• 한국전기전자재료학회논문지
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• 제28권7호
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• pp.467-472
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• 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.

• 전기화학회지
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• 제18권3호
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• pp.115-120
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• 2015

Rayon 분리막에 poly(ethylene oxide) (PEO)를 코팅하고 potassium polyacrylate (PAAK)-KOH 하이드로겔 전해질을 사용하여 기계적 강도 및 전기화학적 성질을 시험하였고, 이를 활성탄 수퍼커패시터에 적용하여 커패시터 특성을 조사하였다. PEO 코팅량의 증가에 따라 기계적 강도는 증가하였으며, PEO 함량을 5 wt.% 이하로 유지하면 이온전도도가 $10^{-2}S\;cm^{-1}$ 이상을 유지하여 실제 커패시터에의 활용이 가능하였다. 결과적으로 Rayon/PEO 분리막과 PAAK/KOH 전해질을 적용한 활성탄 수퍼커패시터는 $1000mV\;s^{-1}$의 높은 스캔속도에서도 비축적용량이 1000 사이클까지 안정하게 나타나는데, 이는 PEO 코팅이 Rayon의 장섬유 필라멘트간 엉킴점을 고정시켜 고출력 안정성을 얻을 수 있기 때문이다.

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.550-555
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• 2013

6M KOH 수계 전해액에 potassium poly(acrylate) (PAAK)를 3 wt% 포함시켜 제조한 하이드로겔을 poly(acrylonitrile)부직포 분리막에 코팅하고, 이를 활성탄 수퍼커패시터의 분리막 및 전해질로 사용하여 수퍼커패시터의 고율특성 향상을 시도하였다. 이 분리막 및 전해질은전자현미경 관찰 결과 PAAK 하이드로겔이 부직포의 표면기공에 균일하게 코팅되어 있으며, 24일 동안 하이드로겔의 합습도가 230% 이상으로 균일하게 유지되었고, 6 M KOH 전해액을 사용한 경우($3.6{\times}10^{-2}Scm^{-1}$)보다 약간 낮은 $2.9{\times}10^{-2}Scm^{-1}$의 이온전도도를 나타내었다. 활성탄을 활물질로 사용한 대칭형 수퍼커패시터에 이 분리막 및 전해질을 채택한 경우 사이클릭볼타메트리 시험에서 $1000mVs^{-1}$의 고속스캔 조건에서도 $27Fg^{-1}$ 이상의 높은 비축전용량과 1000 사이클 경과후에도 97% 이상의 유지율을 나타내는데, 이는 부직포 상에 코팅된 PAAK 하이드로겔 전해질이 활성탄 전극과 부직포 분리막 사이에서 강력한 계면밀착을 유지할 수 있기 때문이다.

• Journal of Advanced Marine Engineering and Technology
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• 제30권2호
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• pp.231-238
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• 2006

The performance of free-breathing polymer electrolyte membrane fuel cell (PEMFC) was studied experimentally and the effect of cathode separator structure on the cell performance was investigated. Cathode separators were used for the cell with $18cm^2$ active area. In channel type, the contact resistance is low, and the nature convection. which is strongly affected by the cross-sectional shape of cathode separator channel, is dominant in a cell performance. The maximum power density with $18cm^2$ active area is $105mW/cm^2$ using the 10mm depth and 2mm width channel. A computational analysis was optimum structure of free-breathing channel type PEMFC for robotic application.

• Korean Chemical Engineering Research
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• 제52권5호
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• pp.553-557
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• 2014

폴리프로필렌(PP) 격리막의 표면을 황산-acetone 알돌 응축반응을 통해 술폰화 폴리프로필렌(S-PP) 격리막을 제조하고 표면기 분석과 접촉각 측정을 통해 $-SO_3H$ 그룹이 다량 분포된 친수성 표면으로 전환되었음을 밝혔다. 또한 potassium polyacrylate (PAAK) 하이드로겔 고분자 전해질로 S-PP 표면을 코팅하고 이를 활성탄 수퍼커패시터에 적용하여 그 전기화학적 특성을 조사하였다. 결과적으로 S-PP 격리막은 친수성 표면으로 인하여 비록 전기화학적 안정성은 감쇠하지만, 접촉각 감소, 젖음성 향상, 전해질 함침량 증대, 이온전도도 향상, 계면저항 감소 등의 효과를 발생시켜 결국 커패시터적 특성의 향상, 즉 비축전용량과 사이클 수명의 향상을 구현할 수 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.581-584
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• 2001

For the first time, a totally solid state electric double layer capacitor has been fabricated using an alkaline polymer electrolyte and an activated carbon powder as electrode material. The polymer electrolyte serves both as separator as well as electrode binder. The capacitor has a three-layer structure; electrode-electrolyte-electrode. A cyclic voltammetry and constant current discharge have been used for the determination of the electro chemical performance of capacitors.