• 전기화학회지
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• 제17권3호
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• pp.156-163
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• 2014

본 연구에서는 불소계 실란을 첨가제로 사용하여 전해액의 열화 반응을 억제함으로써 리튬이온전지의 싸이클 특성을 향상시키고자 하였다. 첨가제로 사용된 trifluoropropyltrimethoxysilane은 리튬염과 카보네이트계 유기 용매로 이루어진 액체 전해질보다 전기화학적 산화, 환원 분해반응이 먼저 일어나 음극 및 양극 표면에서 안정적인 고체전해질계면 (solid electrolyte interphase, SEI) 막을 형성하며, 5 wt.%의 첨가제를 포함하는 경우 가장 우수한 전기화학적 특성을 나타내었다. SEM 및 XPS 분석을 통해 전극 표면에 생성된 피막의 화학 성분을 분석하였으며, 이들 결과로부터 새로운 SEI 형성 첨가제로서 불소계 실란의 가능성을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.822-824
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• 1998

The lithium polymer battery with polymer electrolyte is expected as a safe and long cycle life battery. This paper reports primarily the recent development results of a solid polymer electrolyte, which is a key point of the secondary battery system. The new type of polymer electrolyte was prepared under a dry Ar atmosphere by dissolving $LiCIO_4$ in a matrix of EC, PC and then dispersing polyacrylonitrile(PAN). Also adding some inorganic filler $Al_2O_3$. The dispersed solution heated at $120^{\circ}C$. The polymer electrolyte were characterized by EIS(Electrochemical Impedance Spectroscopy), TGA(Thermo Gravimetric analysis), DMA(Dynamic Mechanical Analyzer), DSC (Differential Scanning Calorimetry). The lithium ion yield is 0.29 when PAN-$Al_2O_3$ which was applied DC 5mV. The ionic conductivity of PAN, PAN-$Al_2O_3$ polymer electrolytes were showed $1.0{\times}10^{-4}S/cm$, $8.4{\times}10^{-4}S/cm$ at room temperature. When inorganic filler was added in the polymer electrolyte, ionic conductivity and lithium yield more larger than without inorganic filler.

• Journal of Electrochemical Science and Technology
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• 제2권4호
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• pp.198-203
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• 2011

A polymer electrolyte was prepared by using polyvinylidenefluoride-co-hexafluoropropylene (PVdF-HFP) or poly(ethylene glycol) dimethacrylate (PEGDMA) as polymer matrices, succinonitrile as an additive, and lithium perchlorate as a lithium salt. Compared to the polymer electrolyte employing PVdF-HFP, the PEGDMA-based polymer electrolyte exhibits substantially superior thermal stability when exposed to high temperatures. Nonetheless, the ionic conductivity of the PEGDMA-based polymer electrolyte was preserved in a wide temperature range between $-20^{\circ}C$ and $80^{\circ}C$.

• 전기화학회지
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• 제5권3호
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• pp.159-163
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• 2002

리튬 이차 전지에서 음극으로 리튬 금속은 매우 높은 에너지 밀도를 가치고 있으나 짧은 충방전 수명, 안정성 결여 및 고율 충방전특성 불량 등의 단점을 가지고 있다. 이는 리튬큼속과 전해액의 반응에 의해 표면보호막의 형성, 침상리튬 생성, 음극 표면적의 증가로 인한 리튬석출의 불균일성에 기인되어 싸이클 효율과 수명이 저하된다. 본 연구는 전해 액에 첨가제 benzene, toluene, tetramethylethylenediamine를 넣어 줌으로 전지 테스트에서 싸이클 효율과 수명이 향상됨을 확인 할 수 있었다. Impedance 측정결과 필름 저항의 감소와 전하전이 저항의 증가로 전해액의 첨가제가 리튬 표면에 새로운 층을 형성시킴으로서 이런 구성물들이 리튬과 전해액과의 반응성을 억제시킴과 동시에 리튬이 특이적으로 표면에 흡착되어 리튬의 석출 형태가 향상된 것으로 사료된다.

• Journal of Electrochemical Science and Technology
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• 제12권1호
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• pp.67-73
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• 2021

Nickel-rich lithium nickel-cobalt-manganese oxides (NCM) are viewed as promising cathode materials for lithium-ion batteries (LIBs); however, their poor cycling performance at high temperature is a critical hurdle preventing expansion of their applications. We propose the use of a functional electrolyte additive, triphenyl phosphate (TPPa), which can form an effective cathode-electrolyte interphase (CEI) layer on the surface of Ni-rich NCM cathode material by electrochemical reactions. Linear sweep voltammetry confirms that the TPPa additive is electrochemically oxidized at around 4.83 V (vs. Li/Li+) and it participates in the formation of a CEI layer on the surface of NCM811 cathode material. During high temperature cycling, TPPa greatly improves the cycling performance of NCM811 cathode material, as a cell cycled with TPPa-containing electrolyte exhibits a retention (133.7 mA h g-1) of 63.5%, while a cell cycled with standard electrolyte shows poor cycling retention (51.3%, 108.3 mA h g-1). Further systematic analyses on recovered NCM811 cathodes demonstrate the effectiveness of the TPPa-based CEI layer in the cell, as electrolyte decomposition is suppressed in the cell cycled with TPPa-containing electrolyte. This confirms that TPPa is effective at increasing the surface stability of NCM811 cathode material because the TPPa-initiated POx-based CEI layer prevents electrolyte decomposition in the cell even at high temperatures.

• ETRI Journal
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• 제26권4호
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• pp.285-291
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• 2004

We prepared a novel multi-functional dual-layer polymer electrolyte by impregnating the interconnected pores with an ethylene carbonate (EC)/dimethyl carbonate (DMC)/lithium hexafluorophosphate $(LiPF_6)$ solution. The first layer, based on a microporous polyethylene, is incompatible with a liquid electrolyte, and the second layer, based on poly (vinylidenefluoride-co-hexafluoropropylene), is submicroporous and compatible with an electrolyte solution. The maximum ionic conductivity is $7{\times}10^{-3}S/cm$ at ambient temperature. A unit cell using the optimum polymer electrolyte showed a reversible capacity of 198 mAh/g at the 500th cycle, which was about 87% of the initial value.

• 공업화학
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• 제34권4호
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• pp.365-382
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• 2023

A lithium metal anode with high energy density has the potential to revolutionize the field of energy storage systems (ESS) and electric vehicles (EVs) that utilize rechargeable lithium-based batteries. However, the formation of lithium dendrites during cycling reduces the performance of the battery while posing a significant safety risk. In this review, we discuss various strategies for achieving dendrite-free lithium metal anodes, including electrode surface modification, the use of electrolyte additives, and the implementation of protective layers. We analyze the advantages and limitations of each strategy, and provide a critical evaluation of the current state of the art. We also highlight the challenges and opportunities for further research and development in this field. This review aims to provide a comprehensive overview of the different approaches to achieving dendrite-free lithium metal anodes, and to guide future research toward the development of safer and more efficient lithium metal anodes.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.67-68
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• 2006

Solid polymer electrolyte is very important in the applications to high energy density lithium batteries of high safety. In this work, solid polymer electrolytes based on PE non-woven matrix, hybrid salt, and anion receptor were successfully prepared. They could provide high ion conduction phase with maintaining mechanical strength. They also showed high electrochemical stability and lithium ion transference number. This new type of solid polymer electrolyte is expected to be a good candidate for rechargeable solid state lithium secondary batteries.

• 한국전기전자재료학회논문지
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• 제18권1호
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• pp.68-74
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• 2005

In this work, polymerization conditions of the gel polymer electrolyte (GPE) were studied to obtain better electrochemical performances in a lithium-ion polymer battery. When the polymerization temperature and time of the GPE were 70$^{\circ}C$ and 70 min, respectively, the lithium polymer battery showed excellent a rate capability and cycleability. The TMPETA (trimethylolpropane ethoxylate triacrylate)/TEGDMA (triethylene glycol dimethacrylate)-based cells prepared under optimized polymerization conditions showed excellent rate capability and low-temperature performances: The discharge capacity of cells at 2 Crate showed 92.1 % against 0.2C rate. The cell at -20 $^{\circ}C$ also delivered 82.4 % of the discharge capacity at room temperature.

• Journal of Electrochemical Science and Technology
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• 제6권4호
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• pp.116-120
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• 2015

Lithium diffusivity of fluorine-free and -doped tin-nickel (Sn-Ni) film model electrodes with improved interfacial (solid electrolyte interphase (SEI)) stability has been determined, utilizing variable rate cyclic voltammetry (CV). The method for interfacial stabilization comprises fluorine-doping on the electrode together with the use of electrolyte including fluorinated ethylene carbonate (FEC) solvent and trimethyl phosphite additive. It is found that lithium diffusivity of Sn is largely dependent on the fluorine-doping on the Sn-Ni electrode and interfacial stability. Lithium diffusivity of fluorine-doped electrode is one order higher than that of fluorine-free electrode, which is ascribed to the enhanced electrical conductivity and interfacial stabilization effect.