Autoxidation in amide-based electrolyte and its suppression for enhanced oxygen efficiency and cycle performance in non-aqueous lithium oxygen battery

Kim, Dong Wook,Lee, Dong Hun,Ahn, Su Mi,Kim, Do Youb,Suk, Jungdon,Choi, Dong Hoon,Kang, Yongku Elsevier 2017 Journal of Power Sources Vol.347 No.-

<P><B>Abstract</B></P> <P>In spite of several desirable properties such as high stability against superoxide anion and low vapor pressure, <I>N</I>-methyl-2-pyrrolidone (NMP) electrolyte is reported not suitable for use in lithium-oxygen (Li-O<SUB>2</SUB>) batteries because of severe degradation upon cycling and low oxygen efficiency. In this work, we find that NMP electrolyte is reactive with O<SUB>2</SUB> gas in the presence of lithium metal and such O<SUB>2</SUB>-consuming reaction (<I>i.e.,</I> autoxidation) is a possible cause for the poor performance in Li-O<SUB>2</SUB> batteries with NMP electrolyte. The autoxidation of NMP is verified by direct measurement of the depletion of O<SUB>2</SUB> gas in the hermetically sealed symmetric Li/Li cells via in-situ gas pressure analysis. In-situ differential electrochemical mass spectroscopy (DEMS) experiment reveals that the autoxidation resulted in significant O<SUB>2</SUB> consumption upon discharge, very low O<SUB>2</SUB> efficiency upon charge, and eventually fast capacity fading. Lithium nitrate (LiNO<SUB>3</SUB>), which provides a protective layer on the surface of lithium metal, is employed to suppress the autoxidation, leading to significantly enhanced oxygen efficiency and cycle life.</P> <P><B>Highlights</B></P> <P> <UL> <LI> NMP electrolyte is reactive with O<SUB>2</SUB> gas in the presence of lithium metal. </LI> <LI> Autoxidation is verified by in-situ gas pressure analysis and DEMS. </LI> <LI> Autoxidation results in low O<SUB>2</SUB> efficiency and fast capacity fading. </LI> <LI> LiNO<SUB>3</SUB> is employed to suppress the autoxidation. </LI> <LI> LiNO<SUB>3</SUB> is efficient in enhancing oxygen efficiency and cycle life. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Autoxidation and Photooxidation of Triacylglycerols Containing Conjugated Linoleic Acids

정문웅,최동성,오찬호,윤석후 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.6

Soybean, cottonseed, and corn oils were hydrogenated to obtain triacyglycerols containing conjugated linoleic acids. The oxidative stability of soybean oil, cottonseed oil, and corn oil was less with CLA than without CLA during autoxidation. However, the autoxidative stability of oils increased as the CLA content increased. During photooxidation of oils, the oxidative stability of oils was higher with CLA than without CLA, and the stability of oils increased as the CLA content increased. The mechanisms of autoxidation and photooxidation of oils were probably due to the contents and anti- and prooxidant activities of individual conjugated linoleic acids in bulk oil, and minor compounds present in oils.

Mechanism of DNA Cleavage Induced by Fe²⁺ Autoxidation

Kim, Jong-Moon,Kim, Seog-K. Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.3

This work investigated the difference between $Fe^{2+}$ autoxidation-induced and Fenton-type cleavage of pBR322 plasmid DNA. $^{\cdot}OH$ generation reactions in the absence and presence of $H_2O_2$ under various conditions were also investigated. Although both the $Fe^{2+}$ autoxidation and Fenton-type reactions showed DNA cleavage and $^{\cdot}OH$ generation, there were significant differences in their efficiencies and reaction rates. The rate and efficiency of the cleavage reaction were higher in the absence of 1.0 mM of $H_2O_2$ than in its presence in 20 mM phosphate buffer. In contrast, the $^{\cdot}OH$ generation reaction was more prominent in the presence of $H_2O_2$ and showed a pH-independent, fast initial reaction rate, but the rate was decreased in the absence of $H_2O_2$ at across the entire tested pH range. Studies using radical scavengers on DNA cleavage and $^{\cdot}OH$ generation reactions in both the absence and presence of $H_2O_2$ confirmed that both reactions spontaneously involved the active oxygen species $^{\cdot}OH$, ${O_2}^{\cdot-}$, $^1O_2$ and $H_2O_2$, indicating that a similar process may participate in both reactions. Based on the above observations, a new mechanism for the $Fe^{2+}$ autoxidation-induced DNA cleavage reaction is proposed.

Mechanism of DNA Cleavage Induced by Fe^(2+) Autoxidation

Jong Moon Kim,김석규 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.3

This work investigated the difference between Fe^(2+) autoxidation-induced and Fenton-type cleavage of pBR322plasmid DNA. ^(•)OH generation reactions in the absence and presence of H_2O_2 under various conditions were also investigated. Although both the Fe^(2+) autoxidation and Fenton-type reactions showed DNA cleavage and ^(•)OH generation, there were significant differences in their efficiencies and reaction rates. The rate and efficiency of the cleavage reaction were higher in the absence of 1.0 mM of H_2O_2 than in its presence in 20 mM phosphate buffer. In contrast, the ^(•)OH generation reaction was more prominent in the presence of H_2O_2 and showed a pH-independent, fast initial reaction rate, but the rate was decreased in the absence of H_2O_2 at across the entire tested pH range. Studies using radical scavengers on DNA cleavage and ^(•)OH generation reactions in both the absence and presence of H_2O_2 confirmed that both reactions spontaneously involved the active oxygen species ^(•)OH, O_2^(•−), ^(1)O_2 and H_2O_2, indicating that a similar process may participate in both reactions. Based on the above observations, a new mechanism for the Fe^(2+) autoxidation-induced DNA cleavage reaction is proposed.

수용성 모델시스템 내에서의 상업적 γ-Oryzanol의 C-7 산화 콜레스테롤 유도체 생성 저해효과

김주신 한국식품위생안전성학회 2008 한국식품위생안전성학회지 Vol.23 No.1

The inhibition of cholestero γ-oryzanol (0, 50, 100, and 300 pm)was studied in an aqueous model system for 20 h at pH 5.5 and 80C. The inhibition effectiveness of the commercialγ-oryzanol was followed by the retention of cholesterol and the formation of C-7 oxidized cholesterol derivatives(OCDs). Changes in the amount of γ-oryzanol in the aqueous system were determined during cholesterol autoxidation.A method to detect the levels of 7-ketocholesterol, 7α-hydroxycholesterol and 7β-hydroxycholesterol in an aqueousmodel system with γ-oryzanol was developed by using the hexane-ethyl acetate extraction system and high-perfor-mance liquid chromatography. Results showed that the levels of C-7 OCDs in an aqueous dispersion containing 300ppm of γ-oryzanol were not significantly (p>0.05) increased, when compared to other treatments (0, 50, and 100 pm),during the accelerated cholesterol oxidation.

Commercial ${\gamma}$-Oryzanol Inhibits the Formation of C-7 Oxidized Cholesterol Derivatives (OCDs) in an Aqueous Model System during Cholesterol Autoxidation

김주신,Kim, Joo-Shin The Korean Society of Food Hygiene and Safety 2008 한국식품위생안전성학회지 Vol.23 No.1

The inhibition of cholesterol autoxidation by commercial ${\gamma}$-Oryzanol (0, 50, 100, and 300 ppm) was studied in an aqueous model system for 20 h at pH 5.5 and $80^{\circ}C$. The inhibition effectiveness of the commercial ${\gamma}$-Oryzanol was followed by the retention of cholesterol and the formation of C-7 oxidized cholesterol derivatives (OCDs). Changes in the amount of ${\gamma}$-Oryzanol in the aqueous system were determined during cholesterol autoxidation. A method to detect the levels of 7-ketocholesterol, $7{\alpha}$-hydroxycholesterol and $7{\beta}$-hydroxycholesterol in an aqueous model system with ${\gamma}$-Oryzanol was developed by using the hexane-ethyl acetate extraction system and high-performance liquid chromatography. Results showed that the levels of C-7 OCDs in an aqueous dispersion containing 300 ppm of ${\gamma}$-Oryzanol were not significantly (p>0.05) increased, when compared to other treatments (0, 50, and 100 ppm), during the accelerated cholesterol oxidation. 미강 추출 상업용 유통 감마오리자놀의 콜레스테롤 자동산화에 의한 C-7 산화 콜레스테롤 유도체 생성 저해 효과가 수용성 모델 시스템을 이용하여 검토되었다. C-7 콜레스테롤 산화 유도체 (C-7 oxidized cholesterol derivatives: C-7 OCDs) 생성을 위해 콜레스테롤과 감마오리자놀이 분산된 수용성 모델시스템은 구리이온을 촉매로 pH 5.5와 $80^{\circ}C$의 가혹 조건에서 20시간 동안 반응되었다. 산화 유도 기간에 따른 C-7콜레스테롤 산화 유도체 (7-ketocholesterol, 7{\alpha}$-hydroxy-cholesterol과 7b-hydroxycholesterol)의 생성 정도와 감마오리자놀 및 콜레스테롤 변화 추이 정도가 핵산과 에틸아세테이트를 이용한 용매 추출법과 고속 액체크로마토그래프 (high-performance liquid chromatography) 테크닉을 이용 정량적으로 분석되었다. 분석 결과 콜레스테롤 산화 유도 기간에 따른 7-ketocholesterol 생성비율은 7-hydroxycholesterol 이성체 (${\alpha}$-형:${\beta}$-형) 대비 약 2:1의 비율로 생성되었으며, 7-hyoxycholesterol 이성체에 있어서는 ${\alpha}$-형 대비 ${\beta}$-형의 생성 정도가 약 1:2의 비율로 나타났고, 총 C-7 산화콜레스테롤의 생성은 상대적인 고농도(300 ppm) 감마오리자놀 처리 모델 시스템에서 효과적으로 저해되었다.

금강밀과 dark northern spring밀의 기울과 배아에서 추출한 기름의 자동산화 안정성 및 미량성분 비교

최현기(Hyunki Choi),최은옥(Eunok Choe) 한국식품과학회 2009 한국식품과학회지 Vol.41 No.6

금강밀 또는 Dark Northern Spring(DNS)밀의 기울과 배아로부터 추출한 유지(WBG유)를 빛을 차단하고 50℃에서 12일 동안 저장하면서 과산화물값, 지방산조성 변화로 자동산화안정성을 평가하였고 토코페롤과 토코트리엔올, 카로티노이드, 인지질 함량 변화도 함께 측정하였다. 금강밀과 DNS밀에서 추출한 WBG유는 초기 과산화물값에 뚜렷한 차이를 보이지 않았으나 금강밀 WBG유는 DNS밀 WBG유에 비해 높은 유리지방산값을 보였다. 또한 금강밀 WBG유는 DNS밀 WBG유보다 리놀레산이, DNS밀 WBG유는 금강밀 WBG유보다 올레산이 유의하게 더 많았다. 인지질 함량은 DNS밀 WBG유에서 많았으며 토코페롤과 카로티노이드 함량은 반대 경향을 보였다. 금강밀과 DNS밀에서 추출한 WBG유는 산화기간이 증가함에 따라 과산화물값이 유의하게 증가하였으며, 산화속도는 두 기름 사이에 유의한 차이가 없었다. 금강밀과 DNS밀 WBG유의 자동산화 중 카로티노이드와 인지질은 모두 유의한 차이를 보이며 분해되었고, 인지질함량이 WBG유의 자동산화정도와 높은 상관관계를 보여주었다. Autoxidative stability of wheat bran and germ oil extracted from Keumkang wheat (WBG-K) or Dark Northern Spring wheat (WBG-DNS) at 50℃ in the dark was compared by peroxide values (POV) and fatty acid composition by gas chromatography. Changes of minor compounds were monitored by HPLC. WBG-K showed significantly higher linoleic but lower oleic acid content than WBG-DNS. WBG-DNS contained more phospholipids but less tocopherols and carotenoids than WBG-K. POV of oils was increased during storage, with no significant difference in the oxidation rates between two oils. Tocopherols, carotenoids, and phospholipids in both oils were degraded during the autoxidation. Total phospholipids content showed the highest correlation with the degree of oxidation in WBG oils. The results clearly showed that both fatty acid composition and contents of tocopherols, carotenoids, and phospholipids co-affected the autoxidation of WBG oil.

Formation and Inhibition of Cholesterol Oxidation Products (COPs) in Foods; An Overview

김주신 한국응용과학기술학회 2023 한국응용과학기술학회지 Vol.40 No.5

Cholesterol is prone to oxidation, which results in the formation of cholesterol oxidation products (COPs). This occurs because it is a monounsaturated lipid with a double bond on C-5 position. Cholesterol in foods is mostly non-enzymatically oxidized by reactive oxygen species (ROS)-mediated auto-oxidative reaction. The COPs are found in many common foods of animal-origin and are formed during their manufacture process. The formation of COPs is mainly related to the temperature and the heating time the food is processed, storage condition, light exposure and level of activator present such as free radical. The level of COPs in processed foods could reach up to 1-10 % of the total cholesterol depending on the foods. The most predominant COPs in foods including meat, eggs, dairy products as well as other foods of animal origin were 7-ketocholesterol, 7 α-hydroxycholesterol (7α-OH), 7β-hydroxycholesterol (7β-OH), 5,6α-epoxycholesterol (5,6α-EP), 5,6β-epoxycholesterol (5,6β-EP), 25-hydoxycholesterol (25-OH), 20-hydroxycholesterol (20-OH) and cholestanetriol (triol). They are mainly formed non-enzymatically by cholesterol autoxidation. The COPs are known to be potentially more hazardous to human health than pure cholesterol. The procedure to block cholesterol oxidation in foods should be similar to that of lipid oxidation inhibition since both cholesterol and lipid oxidation go through the same free radical mechanism. The formation of COPs in foods can be stopped by decreasing heating time and temperature, controlling storage condition as well as adding antioxidants into food products. This review aims to present, discuss and respond to articles and studies published on the topics of the formation and inhibition of COPs in foods and key factors that might affect cholesterol oxidation. This review may be used as a basic guide to control the formation of COPs in the food industry.

Oxidative stability of oil-in-water emulsions with a-tocopherol, charged emulsifier, and different oxidative stress

이보라,김미자,이재환 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.6

a-Tocopherol is known to show different activity depending on the concentration and food matrix. Effects of a-tocopherol at the concentrations of 0, 0.1, 0.5, and 1.0 mM were determined in oil-in-water (O/W) emulsions containing anionic, neutral, and cationic emulsifiers under different types of oxidative stress including riboflavin photosensitization, photooxidation, and autoxidation. Headspace oxygen depletion, lipid hydroperoxides, and conjugated dienes were analyzed to determine the oxidative stability of O/W emulsions. a-Tocopherol served as an antioxidant in O/W emulsion with a cationic emulsifier irrespective of oxidative stress. a-Tocopherol acted as an antioxidant in O/W emulsion with a neutral emulsifier at riboflavin photosensitization while a prooxidant at photooxidation. However, in samples with an anionic emulsifier, a-tocopherol activity differed from the concentration and types of oxidative stress. Therefore, cationic transition metals or reactive oxygen species generated from RF photosensitization could play key roles of a-tocopherol in O/W emulsion.

Cervus nippon yesoensis (Japanese Yeso Deer) 사슴육에서의 색소 및 색소 안정성

M. Sekikawa,K. H. Han,K. Shimada,M. Fukushima,T. Ishikawa,C. H. Lee,M. Mikami Korean Society for Food Science of Animal Resource 2003 한국축산식품학회지 Vol.23 No.4

Color and its stability in venison, longissumus dorsi (LD) and quadriceps femoris (QF) muscles, from 8 wild Cervus nippon yesoensis (Japanese Yeso Deer) were investigated by means of the CIE L$^{*}a{*}b{*}$ measurement and autoxidation rate recorded using partially purified myoglobin. It was observed a common feature of the change of three mean values($L^{*}$, $a^{*}$ and $b^{*}$) in both LD and QF that mean value increased at 1 or 2 day post-mortem and then decreased during storage. The differences between 1 and 7 days was the largest in $a^{*}$ value than those in $L^{*}$ and $b^{*}$ values. The mean differences among storage days were only significant in $a^{*}$ except for $b^{*}$ of LD. It was same tendency that the mean difference of CIE $L^{*}$, $a^{*}$ and $b^{*}$ values during refrigerator storage was larger in $a^{*}$ than both in $L^{*}$ and $b^{*}$ reported in beef(Sekikawa et al., 1995) and venison(Stevenson et al., 1989) during storage. The smaller $a^{*}$ value was indicated that bright red of meat changed to dull red, brown red causing met-Mb formation. To compare of color stability with respects to the Mb autoxidation rate, we measured this rate of deer and horse muscles, because horse Mb was considered to have the fastest autoxidation rate among domestic animals, and we used crude Mb and pH 6.0, which might be reflected to the intact meat. Mean value of the autoxidation rate measured in this study in deer was 0.037 and that was 0.026 in horse(sigma). Although there was no significant mean difference and were different Mb purity between deer(A409/A 280 nm = 4.0) and horse(5.6), in generally Mb purity was the higher and the faster autoxidation rate, but this rate in deer was faster than in horse. These results might indicate that venison meat discolors at faster rate compared with beef.