As the size of market for electric vehicles and energy storage systems grows, the demand for lithium-ion batteries (LIBs) is increasing. Currently, commercial LIBs are fabricated with liquid electrolytes, which have some safety issues such as low chemical stability, which can cause ignition of fire. As a substitute for liquid electrolytes, solid electrolytes are now being extensively studied. However, solid electrolytes have disadvantages of low ionic conductivity and high resistance at interface between electrode and electrolyte. In this study, Li7La3Zr2O12 (LLZO), one of the best ion conducting materials among oxide based solid electrolytes, is fabricated through RF-sputtering and various electrochemical properties are analyzed. Moreover, the electrochemical properties of LLZO are found to significantly improve with co-sputtered Li2O. An all-solid thin film battery is fabricated by introducing a thin film solid electrolyte and an Li4Ti5O12 (LTO) cathode; resulting electrochemical properties are also analyzed. The LLZO/Li2O (60W) sample shows a very good performance in ionic conductivity of 7.3  108 S/cm, with improvement in c-rate and stable cycle performance.

Owing to its low cost, easy fabrication process, and good ionic properties, aqueous supercapacitors are under strong consideration as next-generation energy storage devices. However, the limitation of the current collector is its poor electrochemical stability, leading to low energy storage performance. Therefore, a reasonable design of the current collector and the acidic electrolyte is a necessary, as well as interfacial engineering to enhance the electrochemical performance. In the present study, graphite foil, with excellent electrochemical stability and good electrical properties, is suggested as a current collector of aqueous supercapacitors. This strategy results in excellent electrochemical performance, including a high specific capacitance of 215 F g−1 at a current density of 0.1 A g−1, a superior high-rate performance (104 F g−1 at a current density of 20.0 A g−1), and a remarkable cycling stability of 98 % at a current density of 10.0 A g−1 after 9,000 cycles. The superior energy storage performance is mainly ascribed to the improved ionic diffusion ability during cycling.

The pickling brine generated from the salting process of kimchi production is difficult to treat biologically due to very high content of salt. When pickling brine is treated and discharged, it cannot satisfy the criteria for effluent water quality in clean areas, while resources such as the salt to be recycled and the industrial water are wasted. However, sterilization by ozone, UV and photocatalyst is expensive installation costs and operating costs when considering the small kimchi manufacturers. Therefore there is a need to develop economical process. The study was conducted on the sterilization efficiency of the pickling brine using electrochemical processing. The electrochemical treatment of organic matters has advantages over conventional methods such as active carbon absorption process, chemical oxidation, and biological treatment because the response speed is faster and it does not require expensive, harmful oxidizing agents. This study were performed to examine the possibility of electrochemical treatment for the efficient processing of pickling brine and evaluated the performance of residual chlorine for the microbial sterilization.

Thin film electrode consisting purely of porous anodic tin oxide with well-defined nano-channeled structure was fabricated for the first time and its electrochemical properties were investigated for application to an anode in a rechargeable lithium battery. To prepare the thin film electrode, first, a bi-layer of porous anodic tin oxides with well-defined nano-channels and discrete nano-channels with lots of lateral micro-cracks was prepared by pulsed and continuous anodization processes, respectively. Subsequent to the Cu coating on the layer, well-defined nano-channeled tin oxide was mechanically separated from the specimen, leading to an electrode comprised of porous tin oxide and a Cu current collector. The porous tin oxide nearly maintained its initial nano-structured character in spite of there being a series of fabrication steps. The resulting tin oxide film electrode reacted reversibly with lithium as an anode in a rechargeable lithium battery. Moreover, the tin oxide showed far more enhanced cycling stability than that of powders obtained from anodic tin oxides, strongly indicating that this thin film electrode is mechanically more stable against cycling-induced internal stress. In spite of the enhanced cycling stability, however, the reduction in the initial irreversible capacity and additional improvement of cycling stability are still needed to allow for practical use.

폴리아닐린(polyaniline, PANI)과 도판트인 camphorsulfonic acid(CSA), dodecyl benzene sulfonic acid(DBSA)와 의몰비 변화에 따라 가상 n형 PANI을 제조하였다. FT-IR측정으로부터 도핑유무를 확인하였고, indium thin oxide(ITO)에 코팅하여 제조한 전극에 대해, 순환전압전류법과 교류임피던스법을 이용하여 도판트의 영향을 조사하였다. FT-IR과 순환전압전류법으로부터, 제조된 전극이 양이온의 도핑-탈도핑이 일어나는 가상 n형의 특성을 가짐을 확인하였다. 순환전압전류법에서 산화-환원 피크전류값은 PANI/DBSA에 비하여 PANI/CSA가 약 5 배정도 더 큰 결과를 보였다. 교류임피던스법으로부터, 두 전극 모두 이상적인 Randles의 등가회로와 유사한 거동을 보였다. 전하이동저항은 PANI/CSA에서 1.14~1.09 kΩ으로 거의 일정한 값을 보였고, PANI/DBSA는 DBSA 몰 비에 증가에 따라 27.73~8.37KΩ으로 감소하여 나타났다. 이중층용량 또한 PANI/CSA는 13.47~14.59 μF으로 거의 일정하였으나, PANI/DBSA는 DBSA 몰 비 증가에 따라 0.49~l.20 μF으로 증가를 보였다. 결과적으로 PANI/CSA의 전기적 특성이 더 좋았으나, 도판트의 몰 비 증가에 따른 특성은 PANI/CSA 전극은 거의 일정하였고, PANI/DBSA 전극은 전기적 활성이 좋아짐을 알 수 있었다.

노후화된 고온설비의 안정성 및 효율적인 운전조건을 확보하고, 고온부재의 취성파괴 방지를 위해서는 재질열화의 정량적 평가는 매우 중요하다. 그러나 현장실기에서 기계적 성질의 평가를 위한 대량의 시험편 채취는 거의 불가능하다. 따라서, 실기부재의 강도에 영향을 미치지 않는 범위에서 플랜트 구조물의 재질열화 평가를 비파괴적으로 검출 평가할 수 있는 새로운 시험방법들의 개발이 요구된다. 본 연구에서는 화력설비 부재의 다양한 탄소강을 대상으로 재질열화도 평가를 위한 전기화학적 양극분극시험법의 적용 가능성을 조사하였다. 또한 양극분극시험에 의한 재질열화평가 유효성을 조사하기 위해 전기화학적 시험결과를 입계부식시험결과와 비교.검토해 보았다.

NaCl과 LiNO2의 첨가량에 따른 콘크리트에 매립된 철근의 부식거동을 전기화학적 임피던스 분광법을 이용하여 고찰하였다. 부식 가속 방법중 하나인 건습반복법을 이용하여 단기간 내에 부식현상을 촉진하였으며, 측정된 임피던스 값을 통해 등가회로를 제안할 수 있었다. NaCl 1.2 kg/m3이 첨가된 콘크리트에 매립된 철근의 부동태 피막이 빠르게 파괴되는 것을 확인할 수 있었으며, 염화물 첨가량 대비 0.6M의 LiNO2를 첨가한 경우 부식진행속도가 크게 저하하는 것을 확인할 수 있었다. 또한 염화물 첨가량 대비 1.2M의 LiNO2를 첨가한 경우 부동태 피 막이 부식가속시간이 지나도 파괴되지 않고 성능이 유지되는 것을 확인할 수 있었다.

This study is based on the electrochemical theory which aims to get the quantitative evaluation about corrosion protection of Zn-Sn metal spray method. The various existing corrosion resistance method and various mixture ratio of Zn-Sn metal spray method is applied with structural steel which is measured change of polarization resistance and corrosion potential. So corrosion protection of Zn-Sn metal spray method is tested. Consequently, coating side of Zn-Sn metal spray method was lower than electric potential of a structural steel adhesion side. So, Galvanic Protection of Zn-Sn metal spray found that structural steel advanced system. Accordingly, Zn-Sn metal spray method is expected as corrosion protection technology excellent in corrosion prevention of structural steel.

Economic and environmental aspects of electrochemical copper recovery from LCD manufacturing process and through hole plating process for PCB circuit board wastewater were evaluated. The extraction rate of copper per unit energy was decreased as HRT increased and initial copper concentration decreased. About 65 minutes was determined as the optimal HRTs which could maximize the productivity of copper recovery on energy. The extracted mass of copper from the wastewater were 0.045 g at 50 mg Cu/L, 0.083 g at 1,000 mg Cu/L and 0.098 g at 3,000 mg Cu/L by unit energy (Wh) for 60 minutes, respectively. LCA (Life Cycle Assessment) technique determined the electrochemical recovery of copper to have more effect on global warming than other environmental impact categories.

In this study, corrosion potential (Ecorr), corrosion rate, and polarization resistance were measured aimed at inorganic inhibitors (passive film type) and organic inhibitors (absorption type). The experiment was conducted using potentiostat for the variable molar ratio and chloride ion concentration of the components of inhibitors in an aqueous solution of saturated calcium hydroxide targeting corrosion. As a result, it was possible to ensure an anticorrosive performance of at least a 1.2 molar ratio of inorganic inhibitors. Also, the organic inhibitors ensured the prevention of the anticorrosive performance of at least about a 0.3 molar ratio. It also showed the tendency that between polarization resistance and corrosion rate, Ecorr and corrosion rate is inversely proportional to the linear. Conversely, the tendency between polarization resistance and Ecorr is proportional to the linear. Also, a distinct difference in organic and inorganic inhibitors’ relationship to Ecorr, corrosion rate, and polarization resistance was not shown.

In this study, in order to comprehend performance of corrosion inhibitor, the experiment study was conducted about corrosion characteristic of 3 steps(0.0, norm 1/2, norm) compared to organic corrosion inhibitor standard use of liquid and molar 3 steps(0.0, 0.3, 0.6%) of Chloride by added amount of inorganic corrosion inhibitor by the corrosion inhibitor types about 2.4kg/m3, 4.8kg/m3 based on Chloride ion content 1.2kg/m3 for service life prediction of concrete structure by using Poteniostat.