Jun Yeol Paek

Fabrication of low-temperature solid oxide fuel cells with a nanothin protective layer by atomic layer deposition

Anode aluminum oxide-supported thin-film fuel cells having a sub-500-nm-thick bilayered electrolyte comprising a gadolinium-doped ceria (GDC) layer and an yttria-stabilized zirconia (YSZ) layer were fabricated and electrochemically characterized in order to investigate the effect of the YSZ protective layer. The highly dense and thin YSZ layer acted as a blockage against electron and oxygen permeation between the anode and GDC electrolyte. Dense GDC and YSZ thin films were fabricated using radio frequency sputtering and atomic layer deposition techniques, respectively. The resulting bilayered thin-film fuel cell generated a significantly higher open circuit voltage of approximately 1.07 V compared with a thin-film fuel cell with a single-layered GDC electrolyte (approximately 0.3 V).

Parametric study of Y-doped BaZrO3 thin film deposited via pulsed laser deposition

This study investigates the microstructure morphologies of Y-doped barium zirconate (BZY) thin films via a pulsed laser deposition (PLD) process. BZY thin film crystallinity was investigated at different substrate temperatures in a PLD chamber. BZY thin films deposited under 0.013 mbar of oxygen pressure are highly dense regardless of the substrate temperature (25 °C ≤ T ≤ 600 °C), while those deposited at low temperature (T ≤ 200 °C) have porous structures at an oxygen partial pressure of 0.13 mbar. In addition, BZY thin films deposited at 0.26 mbar in low/intermediate temperature ranges (25 °C ≤ T ≤ 400 °C) have porous and columnar structures. Regardless of the chamber pressures, BZY thin films with dense structures can be obtained when the substrate temperature exceeds 500 °C.

Study on Ohmic Resistance of Polymer Electrolyte Fuel Cells Using Current Interruption Method

최근 전인류가 당면한 화석에너지 고갈문제는 신∙재생에너지 연구개발의 필요성을 높이고 있다. 이들 중 고효율이며 친환경적 특성을 모두 갖춘 연료전지는 넓은 적용 범위를 가지며 현재의 화석에너지 체계를 대신할 만한 유력한 후보 군으로 각광 받고 있다. 이들 연료전지 중 작동 온도가 비교적 상온에 가깝고, 시동 시간이 짧은 고분자전해질 연료전지는 활발한 물리화학적 실험 및 시뮬레이션 연구들을 바탕으로 최근 상용화를 앞두고 (있다.1~3) 이와 관련하여 연료전지의 저항을 측정하기 위한 대표적인 방법으로는 교류 임피던스 측정법과 전류차단법이 있다.

Study of Air-Breathing Polymer Electrolyte Membrane Fuel Cell Using Metal-Coated Polycarbonate as a Material for Bipolar Plates

In this study, a metal-plated polycarbonate was adopted as a material for bipolar plates in a polymer electrolyte membrane fuel cell (PEMFC). The coated layers included 40--thick copper, 10--thick nickel, and 0.3--thick gold that respectively played the roles of current conduction, adhesion between copper and gold, and minimization of surface corrosion. The maximum power of the air-breathing PEMFC with polycarbonate bipolar plates was , which was similar to that of graphite bipolar plates. Finally, the maximum power of a 12-cell stack of polycarbonate bipolar plates was , and it had an operating time of 12 h. Therefore, this was considered a suitable material for bipolar plates in PEMFCs.

Study on Low-Temperature Solid Oxide Fuel Cells Using Y-Doped BaZrO3

In this study, we fabricate and investigate low-temperature solid oxide fuel cells with a ceramic substrate/porous metal/ceramic/porous metal structure. To realize low-temperature operation in solid oxide fuel cells, the membrane should be fabricated to have a thickness of the order of a few hundreds nanometers to minimize IR loss. Yttrium-doped barium zirconate (BYZ), a proton conductor, was used as the electrolyte. We deposited a 350-nm-thick Pt (anode) layer on a porous substrate by sputter deposition. We also deposited a 1--thick BYZ layer on the Pt anode using pulsed laser deposition (PLD). Finally, we deposited a 200-nm-thick Pt (cathode) layer on the BYZ electrolyte by sputter deposition. The open circuit voltage (OCV) is 0.806 V, and the maximum power density is 11.9 mW/ at . Even though a fully dense electrolyte is deposited via PLD, a cross-sectional transmission electron microscopy (TEM) image reveals many voids and defects.