1,720,979 research outputs found
Development of Air Cathode Materials for Metal- Air Batteries
Get PDFFluctuation in oil price and the effect of global warming forced us to look for the replacement of this fossil fuel by advanced high energy density metal air batteries. To bring this advanced technology to commercialize market we need to have noble metals (such as Pt/C) and metal oxides (such as RuO2 and MnO2) as catalysts in cathode to facile the oxygen reduction reaction while discharging process and oxygen evolution reaction when recharging the battery. However, the replacement of these noble metal-based catalysts is due to often suffer from multiple disadvantages, including high cost, low selectivity, poor stability and detrimental environmental effects.
We developed one dimensional LaCo1-xNixO3-δ perovskites by simple electrospinning approach. We show that the progressive replacement of Co by Ni in the LaCo0.97O3- δ perovskite structure greatly altered the OER electrocatalytic activity and the La(Co0.71Ni0.25)0.96O3-δ composition exhibited the lowest overpotential of 324 at 10 mAcm-2 in 0.1M KOH. Subsequently as prepared La(Co0.71Ni0.25)0.96O3-δ nanostructured was used as cathode catalyst for aqueous zinc-air battery, which delivers high capacity of 705 mAh.g-1zinc in primary zinc-air battery. The rechargeable battery discharges with low overpotential of 0.792 V and 0.696 V at low capacity mode (400 mAh.g-1 catalyst) and high capacity mode (2500 mAh.g-1catalyst), respectively, this value is much lower than LaCo0.97O3-δ nanotube catalyst and precious Pt/C catalyst.
In the second part of thesis, we synthesized a thin film carbon coated SiO2 nanosphere by hydrothermal method and we utilized this material as cathode catalyst for lithium-air battery, it delivers a capacity of 18588 mAh.g-1 of catalyst material at high current density of 150 mAh.g-1, which is nearly twice the capacity of nitrogen doped carbon material at same current density, and for rechargeable battery it last for ten cycles at a cutoff capacity of 1000 mAh.g-1. Later to elucidate the working mechanism behind this metalloid oxide catalyst, we also reported the post mortem analysis of cathode material of lithium-oxygen battery. ⓒ 2016 DGISTChapter 1: Introduction 1--
1.1.Forward 1--
1.2.Status and complication of fuel cell technology 4--
1.3.PEM fuel cell 5--
1.4. Lithium-ion battery technology 7--
1.5.Metal-air battery 9--
1.6.Aqueous system 10--
1.6.1.Zinc-air battery 10--
1.6.2.Zinc metal anode 11--
1.6.3.Electrolyte 11--
1.6.4.Air cathode catalys 12--
1.7.Non-aqueous system 13--
1.7.1.Lithium-air battery 13--
Chapter 2: Air cathode catalyst for aqueous zinc-air battery 16--
2.1. Literature survey 16--
2.2 Scope of the work 19--
2.3. Experimental section 20--
2.3.1.Electrospinning approach 20--
2.3.2.Chemicals required 20--
2.3.3. Method 20--
2.3.4.Sol-gel approach 21--
2.3.5.Chemicals required 21--
2.3.6.Method 21--
2.4. Material characterization 23--
2.5. Electrochemical characterization 23--
2.5.1.Electrochemical setup 23--
2.5.2.Electrochemical active surface area 24--
2.6.Zinc-air battery setup 25--
2.7.Results and Discussion 27--
2.7.1.Structural characterization 27--
2.7.2.Electrochemical studies 40--
2.7.3.Zinc-air battery performance 51--
2.8.Summary 60--
Chapter 3: Nitrogen doped carbon coated SiO2 as air cathode catalyst for non-aqueous lithium-oxygen battery 61--
3.1.Literature survey 61--
3.2.Scope of the work 63--
3.3.Experimental section 63--
3.3.1.Hydrothermal approach 63--
3.3.2.Chemicals Required 64--
3.3.3.Synthesis procedure of SiO2 nanosphere 65--
3.3.4.Synthesis procedure of SiO2/NC nanosphere 65--
3.4.Material characterization 65--
3.5.Electrochemical characterization 66--
3.5.1.Electrochemical setup 66--
3.6.Lithium oxygen cell assembly and testing 67--
3.6.1.Air cathode preparation 67--
3.7.Results and discussion 69--
3.7.1.Structural analysis 69--
3.7.2.Electrochemical studies 73--
3.7.3.Lithium-oxygen battery performance 76--
3.8. Summary 83--
Conclusions 84--
Reference 86--
Acknowledgement 105불안정한 유가와 지구온난화는 화석연료를 대체할 수 있는 높은 에너지 밀도의 금속 공기 전지의 발전을 야기하였다. 이 진보된 기술을 상용화 하기 위해서는 충·방전 시 양극 및 음극에서 산소환원반응 및 산소발생반응을 일어나게 하기 위하여 귀금속(Pt/C) 및 금속 산화물(RuO2, MnO2) 촉매가 필요하다. 그러나 이러한 귀금속 기반의 촉매는 가격이 비싸며 낮은 선택성과 낮은 내구성, 홖경오염 이라는 문제점들을 지니고 있다.
우리는 간단한 전기방사법을 통해 일차원의 LaCo1-xNixO3-δ 페로브스카이트 촉매를 개발하였다. LaCo1-xNixO3-δ 페로브스카이트 구조 내에서 코발트를 니켈로 치환했을 때 OER 활성을 향상시킬 수 있으며, La(Co0.71Ni0.25)0.96O3-δ 구성 시 0.1M 의 KOH 에서 10mAcm-2 의 전류를 얻기 위해서는 324 mV 의 낮은 과전압이 요구됨을 확인하였다. 이를 전지에 홗용 시, La(Co0.71Ni0.25)0.96O3-δ 를 음극 촉매로 사용한 수용성 일차 아연-공기 전지에서는 높은 용량(705 mAh.g-1zinc)의 성능을 얻을 수 있었다. 재생 가능한 이차 아연-공기 전지로 제작 시, 전지 방전 과정에서 낮은 용량모드(400 mAh.g-1 catalyst) 에서는 0.792 V, 높은 용량모드(2500 mAh.g-1catalyst) 에서는 0.696 V 로 LaCo0.97O3-δ 나노 튜브 구조 기반촉매와 귀금속 촉매인 Pt/C 를 사용하였을 때 보다 훨씬 낮은 과전압을 필요로 함을 확인할 수 있었다.
학위논문의 두 번째 파트에서는 수열합성법을 통해 카본이 얇게 코팅된 SiO2 나노스피어(nanosphere)를 합성하였고, 리튬 공기 전지에 적용하여 150 mAh.g-1 의 높은 전류밀도에서 18588 mAh.g-1 의 용량을 지닌 음극 촉매로 사용하였다. 이는 같은 전류
밀도에서 질소가 도핑된 탄소보다 거의 2 배의 용량을 보였으며, 2 차 전지로 제조 시 1000mAh.g-1 의 차단용량에서 10 사이클이 지속되는 것을 확인하였다. 본 학위논문에서는 준금속 산화물 촉매의 작동 매커니즘을 설명하기 위해 리튬 공기 전지 음극 물질에 대한 분석 또한 함께 논의되었다. ⓒ 2016 DGISTMasterdCollectio
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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