• Korean Membrane Journal
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• 제4권1호
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• pp.36-40
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• 2002

The diffusion coefficients of ions in the reverse transport system using the carrier mediated membrane were estimated from the diffusional membrane permeabilities and the ion activity in membrane system. In the aqueous alkali metal ions-membrane system diffusional flux of alkali metal ions driven by coupled proton was analyzed. The aqueous phase I contained NaOH solution and the aqueous phase II also contained NaCl and HCl mixed solution. The concentration of Na ions of both phases were $10^{0},\;10^{-1},\;10^{-2},\;5{\times}10^{-1}\;and\;5{\times}10^{-2}\;mol{\cdot}dm^{-3}$ and the concentration of HCI in aqueous phase II was always kept at $1{\times}10^{-1}\;mol{\cdot}dm^{-3}$. Moreover, the carrier concentration in liquid membrane was $10^{-2}\;mol{\cdot}dm^{-3}$. The results indicated that the diffusion coefficients depend strongly on the concentration of both phases electrolyte solution equilibriated with the membrane. The points were interpreted in terms of the energy barrier theory. Furthermore, eliminating the potential terms from the membrane equation was derived.

• 전자통신동향분석
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• 제39권1호
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• pp.83-94
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• 2024

There have been continuous requirements for developing more reliable energy storage systems that could address unsolved problems in conventional lithium-ion batteries (LIBs) and thus be a proper option for large-scale applications like energy storage system (ESS). As a promising solution, aqueous metal-ion batteries (AMIBs) where water is used as a primary electrolyte solvent, have been emerging owing to excellent safety, cost-effectiveness, and eco-friendly feature. Particularly, AMIBs adopting mutivalence metal ions (Ca²⁺, Mg²⁺, Zn²⁺, and Al³⁺) as mobile charge carriers has been paid much attention because of their abundance on globe and high volumetric capacity. In this research trend review, one of the most popular AMIBs, zinc-ion batteries (ZIBs), will be discussed. Since it is well-known that ZIBs suffer from various (electro) chemical/physical side reactions, we introduce the challenges and recent advances in the study of ZIBs mainly focusing on widening the electrochemical window of aqueous electrolytes as well as improving electrochemical properties of cathode, and anode materials.

• 전기화학회지
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• 제25권1호
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• pp.22-31
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• 2022

Carbon nanomaterials are considered to be the materials of choice for the fabrication of electrochemical energy storage devices due to their stability, cost-effectiveness, well-established processing techniques, and superior performance compared to other active materials. In the present work, reduced graphene oxide (rGO) has been synthesized and used for the fabrication of a symmetric supercapacitor. The electrochemical performance of the fabricated supercapacitors with three different aqueous electrolytes namely 0.5 M H₂SO₄, 0.5 M H₃PO₄, and 1.0M Na₂SO₄ have been compared and analyzed. Among the three electrolytes, the highest areal specific capacitance of 14 mF/cm² was calculated at a scan rate of 5 mV/s observed with 0.5M H₃PO₄ electrolyte. The results were also confirmed from the charge/discharge results where the supercapacitor with 0.5M H₃PO₄ electrolyte delivered a specific capacitance of 11 mF/cm² at a current density of 0.16 mA/cm². In order to assess the stability of the supercapacitor with different electrolytes, the cells were subjected to continuous charge/discharge cycling and it was observed that acidic electrolytes showed excellent cyclic stability with no appreciable drop in specific capacitance as compared to the neutral electrolyte.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2002년도 추계총회 및 학술발표회
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• pp.37-37
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• 2002

• Bulletin of the Korean Chemical Society
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• 제17권11호
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• pp.975-977
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• 1996

• 멤브레인
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• 제32권1호
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• pp.43-49
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• 2022

높은 안전성과 견고한 기계적 특성을 가진 고체상 슈퍼커패시터는 차세대 에너지 저장 장치로서 세계적 관심을 끌고 있다. 슈퍼커패시터의 전극으로서 경제적인 탄소 기반 전극이 많이 사용되는데 수계 전해질을 도입하는 경우 소수성 표면을 가진 탄소 기반 전극과의 계면 상호성이 좋지 않아 저항이 증가한다. 이와 관련하여 본 연구에서는 전극 표면에 산소 플라즈마 처리를 하여 친수화된 전극과 수계 전해질 사이의 향상된 계면 성질을 기반으로 더 높은 전기화학적 성능을 얻는 방법을 제시한다. 풍부해진 산소 작용기들로 인한 표면 친수화 효과는 접촉각 측정을 통해 확인하였으며, 전력과 지속시간을 조절함으로써 친수화 정도를 손쉽게 조절할 수 있음을 확인하였다. 수계 전해질로 PVA/H₃PO₄ 고체상 고분자 전해질막을 사용하였으며 프레싱하여 전극에 도입하였다. 15 W의 낮은 전력으로 5초간 산소 플라즈마 처리를 시행하는 것이 최적 조건이었으며 슈퍼커패시터의 에너지 밀도가 약 8% 증가하였다.

• 전기학회논문지
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• 제59권11호
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• pp.2026-2031
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• 2010

The electrical characteristics of galvanic cell which is composed of the cathode electrode(graphite, carbon and copper) and the anode electrode(Zn and Mg) were investigated. For this research as electrolyte 2~12 wt% NaCl aqueous solution were used. At graphite cathode electrodes which use Zn and Mg with the anode electrode, the open circuit voltage was 1.3V most highly. The maximum output power increased as the electrolyte concentration increased, due to a increase in ion density. When Zn and Mg with the anode electrode, the maximum output power respectively was evaluated as 2.2mW and 5.5mW about the graphite cathode electrode in the NaCl 4wt%. The research results indicated that the output power of cell which is composed with graphite with the cathode and Mg with the anode was most excellent and the efficiency of the cell could be enhanced by increasing the electrolyte concentration.

• Macromolecular Research
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• 제15권5호
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• pp.403-411
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• 2007

Monodisperse micron-sized polystyrene (PS) spheres were successfully obtained using a single stage soap-free emulsion method in aqueous media mixed with ethanol (co-solvent) containing NaCI as the electrolyte. The optimum conditions for preparing the monodisperse PS microspheres, using soap-free emulsion polymerization in a water/ethanol mixture with an electrolyte, were studied. The presence of the co-solvent and electrolyte controlled the particle dispersion stability during the polymerization. The microspheres formed using PS, with a weight-average diameter of $2.6{\mu}m$, coefficient of variation of 5.3% and zeta potential of -15.1 eV, were successfully obtained in the presence of 0.1 wt% NaCI, 10 wt% monomer, 0.1 wt% initiator and 95/5 (g/g) of a water/ethanol mixture reacted at $70^{\circ}C$ for 24 h.

• Korean Chemical Engineering Research
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• 제48권4호
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• pp.519-533
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• 2010

본 연구에서는 L-형 아미노산인 L-Alanine과 무기염인 NaCl, KCl, $NaNO_3$ 및 $KNO_3$의 각 전해질로 이루어진 L-Alanine/전해질 수용액 계에서 L-Alanine의 활동도계수와 용해도를 298.15 K에서 측정하였다. L-Alanine의 활동도계수는 양이온 및 음이온의 선택성 전극으로 이루어진 화학전지에서 두 전극간의 기전력을 측정하는 전기화학 법으로 측정하였으며, 용해도는 L-Alanine의 고체상과 상평형을 이루고 있는 포화용액을 중량 분석하여 측정하였다. 한편 본 연구에서는 아미노산(L-Alanine)/전해질 수용액 계의 잔류(residual) Helmholtz 자유에너지를 섭동사슬-통계역학적 회합성유체이론(perturbed chain-statistical associating fluid theory)과 단순-평균구근사(primitive-mean spherical approximation)이론을 결합한 관계로 모델링 하였으며, 이로부터 아미노산의 활동도계수 및 용해도에 대한 열역학적 관계식을 얻었다. Helmholtz 자유에너지를 모델링 하는 과정에서는 아미노산은 양쪽성 이온(zwitterion) 형태로 존재하며 아미노산의 양쪽성 이온은 같은 이온끼리 자기-회합(self-association)하며 동시에 물분자와 교차-회합(cross-association)하는 회합체로 가정하였으며, 또한 아미노산의 양쪽성 이온이 전해질(무기염)로부터 해리된 양이온 및 음이온과 상호작용하여 이온복합체(ion complex)를 형성하는 과정을 회합현상으로 가정하였다. 본 연구에서 제안된 이론적 모델로부터 L-Alanine/전해질 수용액 계에서 계산되는 L-Alanine의 활동도계수 및 용해도 값은 본 연구의 실험값과 일치하는 경향을 보였다.

• 한국재료학회지
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• 제31권5호
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• pp.272-277
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• 2021

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.