• Journal of Electrochemical Science and Technology
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• 제6권1호
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• pp.26-33
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• 2015

In this study, cell performance and thermal stability of lithium-ion cells with a polyimide (PI) separator are investigated. In comparison to conventional polyethylene (PE) separator, the PI separator exhibits distinct advantage in microporous structure, leading to superior reliability of the cell. The cells with PI separator exhibit good cell performances as same as the cells with PE separator, but their reliability was superior to the cell with PE separator. Especially in the hot-box test at 150 and 180℃, PI separator showed a contraction percentage close to 0% at 150℃, while the PE separator showed a contraction percentage greater than 10% in both width and length. Therefore, the PI separator can be the promising candidate for separators of the next generation of lithium-ion battery.

• 멤브레인
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• 제26권4호
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• pp.310-317
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• 2016

리튬이온 이차전지는 리튬이온이 이동하면서 전기화학적 충방전사이클을 완성하는 에너지변환장치를 의미한다. 리튬이온 이차전지는 높은 에너지밀도와 낮은 자가방전률, 상대적으로 긴 수명주기 등 다양한 장점을 갖는다. 최근 전기차 수요증가는 고용량 리튬이온 이차전지 개발을 촉진하고 있으나 음극에서의 dendrite 형성으로 인한 전기적 단락 현상과 전지 폭발 문제와 같은 심각한 안전문제를 야기한다. 또한, 리튬이온 이차전지 구동시 상승된 온도에서 폴리올레핀계열(예 : 폴리에틸렌과 폴리프로필렌) 격리막의 열수축 문제가 발생한다. 이와 같이 낮은 열 안정성은 리튬이온 이차전지의 성능과 수명의 감소로 이어진다. 본 연구에서는 폴리올레핀계열 함침격리막 제조를 위한 중요한 소재로서 술폰화 폴리아릴렌에테르술폰 랜덤 공중합체를 사용하였으며, 제조된 격리막을 이용하여 dendrite 형성과 관련된 금속이온 흡착 능력과 리튬이온전도성, 열적 내구성이 평가되었다.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.308-311
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• 2012

A wide range of possible hazards existing in thermal batteries are mainly caused by thermal runaway, which results in overheating or explosion in extreme case. Battery separators ensure the separation between two electrodes and the retention of ion-conductive electrolytes. Thermal runaways in thermal batteries can be significantly reduced by the adoption of these separators. The high operating temperature and the violent reactivity in thermal batteries, however, have limited the introduction of conventional separators. As a substitute for separators, MgO powders have been mostly used as a binder to hold molten salt electrolyte. During recent decades the fabrication technology of ceramic fiber, which has excellent mechanical strength and chemical stability, has undergone significant improvement. In this study we adopted wet-laid nonwoven paper making method instead of the electrospinning method which is costly and troublesome to produce in volume. Polymeric precursor can readily be coated on the surface of wet-laid ceramic paper, and be formed into ceramic film after heat treatment. The mechanical strength and the thermo-chemical stability as well as the wetting behaviors of ceramic separators with various molten salts were investigated to be applicable to thermal batteries. Due to their excellent chemical, mechanical, and electrical properties, wet-laid nonwoven separators made from ceramic fibers have revealed positive possibility as new separators for thermal batteries which operate at high temperature with no conspicuous sign of a short circuit and corrosion.

• 방사선산업학회지
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• 제4권4호
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• pp.359-364
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• 2010

PVDF-HFP (binder)/silylated alumina (inorganic particle)-coated PE (polyethylene) separators were with various compositions of binder and inorganic particle were prepared by a dip-coating process with humidity control (R.H. 25% and 50%) using electron beam irradiation. The morphology of the coated PVDF-$HFP/Al_2O_3$ layer with various compositions of PVDF-HFP and $Al_2O_3$, and humidity condition was found to be an important factor in determining ionic conductivity of the prepared separators. The PVDF-$HFP/Al_2O_3$ (5/5)-coated PE separator prepared at R.H. 50% followed by electron beam irradiation at 200 kGy was applied for lithium-ion polymer battery and the cell test results showed improved high-rate discharge performance and better cyclic stability compared to the cells with the bare PE and the PVDF-HFP-coated PE separators.

• Journal of Electrochemical Science and Technology
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• 제2권1호
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• pp.51-56
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• 2011

We develop a new nonwoven composite separator for a safer lithium-ion battery, which is based on coating of silica ($SiO_2$) colloidal particles/styrene-butadiene rubber (SBR) binder to a poly(ethylene terephthalate) (PET) nonwoven support. The $SiO_2$ particles are interconnected by the SBR binder and closely packed in the nonwoven composite separator, which thus allows for the development of unusual porous structure, i.e. highly-connected interstitial voids formed between the $SiO_2$ particles. The PET nonwoven serves as a mechanical support that contributes to suppressing thermal shrinkage of the nonwoven composite separator. The $SiO_2$/SBR content in the nonwoven composite separators plays an important role in determining their separator properties. Porous structure, air permeability, and electrolyte wettability of the nonwoven composite separators, in comparison to a commercialized polyethylene (PE) separator, are elucidated as a function of the $SiO_2$/SBR content. Based on this understanding of the nonwoven composite separators, the effect of $SiO_2$/SBR content on the electrochemical performances such as self-discharge, discharge capacity, and discharge C-rate capability of cells assembled with the nonwoven composite separators is investigated.

• 한국표면공학회지
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• 제54권5호
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• pp.213-221
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• 2021

In order to improve the energy density and safety of Li-ion batteries, the development of a separator with high thermal stability and electrolyte wettability is an important desire. Thus, the ceramic separator to replace the polymer type is one of the most promising materials that can prevent short-circuit caused by the formation of dendrite and thermal deformation. In this study, we introduce the fabrication of various anodic aluminum oxide membranes for the application of Li-ion battery separators with the advantages of improved mechanical/thermal stability, wettability, and a high rate of Li⁺ migration through the membrane. Two different types of through-holes and branched anodic aluminum oxide membranes are well used in lithium-ion battery separators, however, branched anodic aluminum oxide membranes exhibit the most improved performance with capacity (126.0 mAh g^-1 @ 0.3C), capacity drop at the high C-rate (30.6 %), and low internal resistance (8.2 Ω).

• 한국고분자학회지:고분자과학과기술
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• 제9권2호
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• pp.131-136
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• 1998

• 한국세라믹학회지
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• 제45권7호
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• pp.423-429
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• 2008

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 molten salt electrolytes for thermal battery were prepared by the impregnation of the commercial glass filters such as GF-A, C and F (Whatman, USA) with two types of molten-lithium salts, LiCl-KCl and LiK-LiBr-LiF. The wetting properties were evaluated by wetting balance test and wetting angle measurement. The wetting behaviors were strongly affected by the composition of the molten salts and the pore structure of the glass separators. The optimum wetting conditions for maximum loading and effective retention of the molten electrolyte were also studied.

• 폴리머
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• 제37권1호
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• pp.22-27
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• 2013

본 연구에서는 기존의 이차전지용 폴리에틸렌(PE) 분리막에 poly(meta-phenylene isophthalamide) (Nomex)를 코팅함으로써 뛰어난 내열성을 가진 coated PE 분리막을 제조하였다. 다양한 Nomex 용액 조성과 PE 분리막 코팅 조건에 따라 제조한 분리막의 기계적 및 열적 특성을 열 노출 테스트와 TMA를 이용하여 측정하였고 제조된 코팅 분리막은 기존의 PE 분리막보다 향상된 열 수축률 및 기계적 성질을 보였다. 코팅 분리막의 전기화학적 성질은 이온전도도, 순환 전위-전류법, 충방전 사이클 테스트 등을 이용해 측정하였다.

• 멤브레인
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• 제24권1호
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• pp.10-19
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• 2014

본 연구에서는 아연공기전지용 분리막으로 사용하기 위한 다공성 막을 Polyethersulfone (PES) 용액의 상전이법을 이용하여 제조하였다. 캐스팅 용액은 PES/polyvinylpyrrolidone(PVP)/N-methylpyrrolidone(NMP) 용액으로 그리고, 비용매는 물을 사용하여 분리막을 제조하였다. 제조된 분리막을 이용하여 아연공기전지를 제작하였다. 분리막의 모폴로지는 캐스팅 용액 내의 PES 및 PVP의 함량을 통해 조절하였다. 제조된 분리막의 기계적 특성, 이온전도도 및 모폴로지는 인장실험, impedance 실험 및 SEM을 이용하여 측정하였다. 아연공기전지의 성능은 current interrupt method (CIM)와 정전류 방전실험을 통하여 측정하였다. 캐스팅 용액 내의 PES 함량이 증가함에 따라 기계적 강도는 증가한 반면 이온전도도는 감소하였다. 반면, 캐스팅 용액 내의 PVP 함량이 증가함에 따라 이온전도도는 증가하였지만 기계적 강도는 감소하였다. 이와 같은 이온전도도 경향의 아연공기전지 내에서의 효과는 current interrupt method와 정전류 방전실험에서 확인되었다. PES 함량이 높은 캐스팅 솔루션의 분리막으로 제조된 전지는 높은 IR 손실과 낮은 방전용량을 보였으며, PVP 함량이 높은 캐스팅 솔루션의 분리막으로 제조된 전지는 낮은 IR손실과 높은 방전용량을 보였다.