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Interfacial Engineering for Stabilizing Thin Li Metal Electrode in Rechargeable Batteries
No full textLi metal batteries, high energy density cell design, Li dendrite growth, Li metal powder, interfacial engineeringLi metal anodes (LMAs) are among the most promising candidates to surpass the energy density limit of current Li-ion batteries because of their superior benefits, such as high theoretical capacity (3860 mAh g‒1) and lowest working voltage (−3.04 V vs SHE). Nevertheless, the use of LMAs has been limited because of their intrinsic properties, the thermodynamically unstable nature of the Li surface, uneven dendritic electro-deposition, and unlimited volume expansion upon prolonged cycling. Moreover, high-energy-density and large-scale cell design based on conventional Li foils has been limited owing to its original properties. In this regard, the use of Li metal powder (LMP) through the slurry coating process enables the fabrication of thin, large-area Li anodes for diverse applications, considering that increasing the pouch cell size by enlarging the electrode area is an effective method of achieving a desired cell energy density. Furthermore, the spherical shape of LMPs imparts a relatively high surface area, which can effectively reduce the current density. However, LMP-based electrodes also suffer from severe morphological drawbacks during long-term cycling, due to the porous structures and an imperfect Li2CO3 passivation layer. As a result, the spherical shape can be completely lost owing to extensive Li loss at individual LMPs, thereby deteriorating the conformal Li distribution.
In this thesis, the interfacial engineering of a thin Li metal anode based on LMPs is reported to overcome the above-mentioned limitations. The first part of this thesis highlights the importance of electrode design to mitigate Li dendrite formation. In addition, the Li dendrite formation behavior according to the polymer structure is discussed. Second, introducing a submicron-level carbon interlayer on a current collector is proposed to prevent its delamination, which leads to dead Li generation. Then, the relationship between interface failures and electrochemical performance is shown by quantifying the adhesive strength at the Li/Cu interface for the first time. Third, a 20-µm-thick, LiNO3-preplanted LMP electrode rationally designed for LMP surface stabilization is presented. Moreover, further validation with a high-loading cathode demonstrates the feasibility and versatility of the proposed method under practical conditions, along with advanced electrolytes. Finally, an electrolyte design with a new fluorinated linear carbonate additive is proposed as a cathode solid electrolyte interphase (CEI) and solid electrolyte interphase (SEI) stabilizer, which could enable the further stabilization of Li metal batteries (LMBs). We believe that our research approach will contribute to improving the specific energy and cycle life of batteries as well as enhance the safety and reliability of LMBs based on thin Li metal anodes by controlling the interfaces and interphase.리튬 금속 음극은 가장 높은 이론용량(3860mAh g‒1)과 낮은 환원 전위 (-3.04 vs. SHE)로 인해 흑연 음극 기반의 현 리튬 이온전지 에너지 밀도의 한계를 해결할 수 있는 차세대 전지의 음극재로서 재조명 받고 있다. 하지만, 리튬 금속 음극은 높은 반응성으로 인해 1) 충 방전 과정동안 표면에서의 반복적인 산화 환원 반응, 2) 불균일한 수지상의 리튬 덴드라이트 성장 및 3) 장기 사이클 시 무분별한 부피 팽창 등의 문제가 여전히 존재한다. 이는 전지의 수명특성이 급격하게 저하되는 것을 야기하며 특히 데드 리튬 발생 및 덴드라이트의 성장에 의한 전지의 내부 단락이 일어날 경우 화재 및 폭발 등 안전성의 문제와 이어질 수 있다. 또한, 전지의 상용화 관점에서 본다면 고에너지밀도의 전지 설계의 용이성을 높이기 위해 박막, 광폭의 리튬 금속 제조기술을 확보하는 것 또한 필수적이다.
리튬 분말 기반 복합전극은 광폭화/박막화에 유리하여 상용 전지의 유연한 설계가 용이하기 때문에 이를 달성하기 위한 방법 중 하나로 주목받고 있다. 또한 리튬 금속 분말의 넓은 표면적 및 3차원 구조는 표면에서의 유효전류밀도를 낮추어 리튬 덴드라이트 성장 및 전지 팽윤 현상 억제를 통한 성능확보에 기여할 수 있다. 하지만, 리튬 금속 분말 기반 전극은 다공성 구조와 불완전한 Li2CO3 보호막 층으로 인해 형태학적 열화와 불안정한 SEI 층을 형성하여 비가역적인 리튬 증착/탈리를 유도하고 장기 구동 성능에 매우 취약하다.
본 논문에서는 리튬 금속 분말 기반으로 박막 리튬 금속 음극을 제조하고 계면을 제어함으로써 이의 형태학적 열화 및 비가역적 리튬 덴드라이트 성장을 억제할 수 있는 다양한 연구 방향을 제시한다. 첫째, 리튬 덴드라이트 형성을 제어할 수 있는 전극 설계 인자를 도출하고, 특히 바인의 고분자 구조에 따른 전지의 성능 간에 관계에 대해 심층적으로 분석하였다. 둘째, 집전체에 서브 마이크론 수준의 탄소 중간층을 도입하여 전지의 형태학적 열화를 방지하는 방안을 소개하였다. 더 나아가 리튬 금속 음극과 집전체 계면의 접착 강도를 처음으로 정량화하여 리튬 층의 탈리와 전지의 열화 사이의 관계를 규명했다. 셋째, 리튬 금속 분말의 균일한 표면 개질과 지속적인 계면보호를 할 수 있는 20 μm 두께의 복합전극 설계기술을 소개하였으며 고로딩 양극과의 추가 검증을 통해 상용 전지 설계 및 다양한 전해액 조건에서도 호환가능성을 입증하였다. 마지막으로 새로운 불화 선형 카보네이트 첨가제가 도입된 새로운 전해질 설계를 소개하여 박막 리튬 금속 음극 기반 리튬 금속 배터리의 성능을 극대화할 수 있는 방안을 제시하였다.Ⅰ. Introduction
1.1 Strategies to improve the cell-energy density 1
1.2 Challenging issues of Li metal batteries 2
1.2.1 Lithium dendrite growth 2
1.2.2 Difficulties of the thin Li metal electrode fabrication 3
1.3 Research Goals 4
1.4 Reference 5
Ⅱ. Li formation controllable polymer structure in the Lithium-powder Electrodes
2.1 Introduction 7
2.2 Experimental Section/Methods 8
2.2.1 Materials 8
2.2.2 Electrode preparation 8
2.2.3 Cell Assembly 9
2.2.4. Electrochemical Analysis 9
2.2.5. SEM and EDX Analysis 9
2.2.6. SAICAS Measurement 9
2.3 Results & discussion 10
2.4 Conclusion 19
2.5 Reference 20
Ⅲ. Submicron Interlayer for Stabilizing Thin Li Metal Powder Electrode
3.1 Introduction 27
3.2 Experimental Section/Methods 28
3.2.1. Materials 28
3.2.2. Fabrication and characterization of carbon-coated Cu foil 29
3.2.3. Li/Cu half-cell test 29
3.2.4. Electrode Preparation 29
3.2.5. Cell Assembly 30
3.2.6. Electrochemical Analysis 30
3.2.7. Post-mortem analysis 30
3.3 Results & discussion 31
3.4 Conclusion 42
3.5 Reference 43
Ⅳ. Robust Cycling of Ultrathin Li-metal Enabled by Nitrate-Preplanted Li Powder
4.1 Introduction 48
4.2 Experimental Section/Methods 50
4.2.1. Materials 50
4.2.2. Preparation of LMP-based, composite electrodes 50
4.2.3 Preparation of NMC cathodes 50
4.2.4. Electrochemical Measurements 51
4.2.5. Characterizations 52
4.3 Results & discussion 52
4.4 Conclusion 73
4.5 Reference 74
Ⅴ. Ethyl 2-(2-fluoroethoxy)ethyl carbonate as a new electrolyte additive
5.1 Introduction 78
5.2 Experimental Section/Methods 79
5.2.1 Synthesis of the EFEEC additive 79
5.2.2 Preparation of the electrode and electrolyte 80
5.2.3 Electrochemical test 80
5.2.4. Postmortem analysis 81
5.3 Results & discussion 81
5.4 Conclusion 89
5.5 Reference 90
Summary in Korean 93DoctordCollectio
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
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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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