学位授与大学：京都大学 ; 取得学位: 博士(工学) ; 学位授与年月日: 2007-09-25 ; 学位の種類: 新制・課程博士 ; 学位記番号: 工博第2866号 ; 請求記号: 新制/工/1421 ; 整理番号: 25551 / The developments in microstructure and phase structure of Sn-based materials gave stable cyclability under the full charge and discharge conditions without the initial large irreversible capacity. Some important structures discovered and their mechanisms for improving the cyclability were discussed as follows. In Chapter 1, the electrode structure of Sn electrodes was discussed, where the theoretical capacity of Li4.4Sn was attained. Weak adhesion of Sn to the Cu foil prevented the powdered Sn electrodes prepared by a conventional slurry-coating process from providing the theoretical capacity of Sn metal from the initial cycle, where the Sn powder peeled off the Cu foil to be disconnected from the foil in electronic conductivity. The electrodeposition process improved the interface adhesion between Sn and Cu foil. The electrodeposited Sn film sticks tightly to the Cu foil after forming the intermediate Cu6Sn5 layer, and it reacts with lithium to the theoretical capacity of Li4.4Sn under the full charge-discharge condition with small irreversible capacity. The initial discharge capacity was 2.5 times as large as that of the graphite. In Chapter 2, the advanced phase structure of the electrodeposited Sn film was discussed, which improved the film in cyclability without a large loss of capacity. The Sn film-Cu foil interface adhesion was still weaker to be delaminated from the Cu foil. Also, the Sn film was pulverized and passivated by electrolyte reduction products. The film was disconnected from the Cu foil in electronic conductivity during the initial cycle and could not continue to react with lithium. The stepwise composition-graded phase structure improved the film in the interface adhesion and active material chemistry to provide better cyclability under the full charge-discharge condition without large sacrifice of their volumetric capacity. The phase structure consists of the Cu6Sn5 and Cu3Sn phases, where Cu6Sn5 phase is the active material with less volume change and electrolyte-reactivity and the Cu3Sn phase enhances the adhesion between the Cu6Sn5 phase and Cu foil. The annealing process formed the stepwise composition-graded phase structure, and the annealing condition controlled the structure to be optimized for better cyclability. In Chapter 3, the advanced microstructure of the electrodeposited Sn film was discussed, which improved the film with the stepwise composition-graded phase structure in cyclability. The annealed rough-surfaced Sn electrode showed better cyclability than the annealed flat-surfaced Sn electrode, even though they had the same stepwise composition-graded phase structure. The micro-columnar structure of the film improved the film in the interface adhesion. The structure self-organizes on the rough surface of the Cu foil during the first charge-discharge cycle. The film is divided into columns of about 10μm square by gaps to accommodate swelled film with much reduced internal stress and strain during the following charge, resulting in less pulverization and enhanced adhesion of the film to the foil. The wavy surface profile of the foil and moderate ductility of the film are critical factors to self-organize the micro-columnar structure of the film during charge and discharge. Close cyclability to typical graphite-anode cells was available for the small cell using the annealed rough-surfaced Sn electrode for 20 cycles. In Chapter 4, the electro co-deposited 79.8Sn-20.2Co alloy film was examined for electrochemical and structural properties, and the feasibility of formation of the microstructure was discussed. The micro-island structure was self-organized on the rough surface of the Cu foil during the first charge-discharge cycle, which is similar to the micro-columnar structure in mechanism for improving the cyclability as well as in the shape. As a result, the Sn-Co alloy electrode offered the same capacity at the 20th cycle as the initial capacity of about 60% of the theoretical capacity of Li4.4Sn. The mechanical properties of the film such as ductility and brittleness give another key for formation of the microstructure, in addition to the rough surface of the current collector foil. In Chapter 5, the anomalous cycle performance of the 79.8Sn-20.2Co alloy electrode was discussed in terms of morphology and phase structure of the film. The film showed four-step change in discharge capacity, which depends on the two-stage phase transformation and morphological change of the film. The film is transformed from the amorphous phase to a new phase with forming fcc-Co particles. The new phase is a key to stable reaction of the Sn-Co film with lithium. Although the new phase initially shows smaller capacity than the amorphous phase, the enlarged surface area of the film activates a new reaction of the new phase to increase capacity. As a result, the new phase provides as large capacity as the amorphous phase. In Chapter 6, the electro co-deposited 92.1Sn-7.9Co alloy film with the microstructure was examined for electrochemical and structural properties, which comprised the new phase of the 79.8Sn-20.2Co alloy film as electrodeposited, and the mechanism of the reaction stability of the new phase was discussed. The 92.1Sn-7.9Co alloy film had the nano-composite phase structure, where the less lithium-active crystalline phase surrounds the amorphous phase to accommodate volume change of the amorphous phase and prevent it from deteriorating, resulting in stable reaction of the amorphous phase with lithium to provide constant capacity. On the other hand, the morphological and phase structural changes of the film improve Li+ diffusion through the film-electrolyte interface, in the film, and in the amorphous phase to increase capacity. As a result, under the full charge-discharge condition, the 92.1Sn-7.9Co alloy film showed monotonous increase in discharge capacity from 663 mAh/g at the 1st cycle to 769 mAh/g at the 20th cycle, which is 77% of the theoretical capacity of Li4.4Sn. Since the phase transformation of the 79.8Sn-20.2Co alloy film caused deterioration of the adhesion between the film and current collector to degrade the cyclability of the film, the phase structure of the 92.1Sn-7.9Co film gives better cyclability when it is prepared in advance of the reaction. There should be still room for further stable cyclability in Sn-Co alloy films. For example, adding a third atom to the film composition may enhance the stability of the reaction of the amorphous phase. Not only electro co-deposition but various thin-filming processes will be proposed to control a three-or-more-component system. However, the adhesion of the film and Cu foil is the crucial factor for the stable cyclability, and the microstructure such as the micro-columnar structure and micro-island structure is the most fundamental and effective in enhancing the adhesion. The micro-columnar structure has been applied for Si and Ge systems and examined for its self-organization mechanism, cyclability, and other electrochemical properties. Some of the results have already reported [67-68]. The advanced lithium ion batteries of group 14 elements with the microstructure may become commercially available in near future. Also, the microstructure should be formed on the flat-surfaced foil with holes in the same stress-concentration mechanism as the rough-surfaced foil. Since the rough-surfaced Cu foil is formed by Cu electrodeposition, there are limitations to control the surface profile. However, the holes can be punched at intervals of a-micrometer-order by using physical processes such as a femto-second laser, resulting in formation of further size-controlled microstructure. Issues of the laser process are beam concentration to make holes of less than 10μm in diameter and long work time. A suitable grating should be a key to overcome the issues and find another potential of the microstructure. / Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第13395号 / 工博第2866号 / 新制||工||1421(附属図書館) / 25551 / UT51-2007-Q796 / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 平尾 一之, 教授 横尾 俊信, 教授 田中 勝久 / 学位規則第4条第1項該当

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15360号 / 工博第3239号 / 新制||工||1487(附属図書館) / 27838 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 森澤 眞輔, 教授 酒井 伸一, 教授 米田 稔 / 学位規則第4条第1項該当

在整個創業環境當中，除了新創公司、政府法令、人才環境等元素以外，投資型機構 也是重要的角色，而所謂創投的分類，也將會因投資標的的不同而有所不同，其中以社會 企業的投資機構，一般我們稱之為「影響力投資機構」，其投資績效不完全以財務報酬為主， 而是會量化所謂社會影響力來做衡量，此機構隨著全世界社會企業的創業潮流，重要性日 益提高，特別的營運模式也開始陸續出現研究。 然而台灣最早在十年前就已有社會影響力投資的概念出現，且相繼出現了許多機構在 推動與執行，產業內具備專業知識與技術的前輩與人才數量更是不勝枚舉，看似不管是資 金還是相關資源皆不缺乏的情況下，回歸到實際執行面上的發展卻不甚順利，許多社會影 響力投資機構相繼地遭遇如營運上的問題，以致於不得不做出像是轉型或是退出市場的決 策，使得台灣有一段時間始終缺乏一個好的典範。一直到 2014 年活水社企投資開發公司(B Current Impact Investment)的正式成立，才真正突破僵局，為台灣的社會影響力投資與社會企業生態再度開啟了新的篇章。 本研究藉由質化訪談的研究模式，實際走入台灣社會企業的現場，面對面蒐集產業面 的經營資訊與競爭策略，暸解作對代表的活水社投是如何辦到的，以時間軸的形式將創立前中後不同期間的經營重點整理並分析，最後輔以經典的投資案例進行必較，將現今台灣最新個案轉為研究資料，最後發現關鍵成功因素為「分散式股權結構」的組織設計模式。 在此架構下的影響力投資機構可以充分發揮各股東的背景與專業能力，互相協調發揮 綜效，同時因應不同的環境與個案條件都能有很好的適應性，這是以往集中式股權結構的 公司無法辦到的，同時他們不斷因應趨勢變化，如今也從個別投資人到公司規模投資機構， 加大了投資基金規模與穩健性，也因此使活水社投得以在不易生存的產業環境下生存下來， 並持續成長茁壯。

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21834号 / 農博第2347号 / 新制||農||1068(附属図書館) / 学位論文||H31||N5206(農学部図書室) / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 森 直樹, 教授 宮川 恒, 教授 奥本 裕 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(地域研究) / 甲第21903号 / 地博第249号 / 新制||地||92(附属図書館) / 京都大学大学院アジア・アフリカ地域研究研究科グローバル地域研究専攻 / (主査)教授 小杉 泰, 教授 中溝 和弥, 准教授 長岡 慎介 / 学位規則第4条第1項該当 / Doctor of Area Studies / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22509号 / 農博第2413号 / 新制||農||1078(附属図書館) / 学位論文||R2||N5289(農学部図書室) / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 矢﨑 一史, 教授 梅澤 俊明, 教授 木岡 紀幸 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・論文博士 / 博士(工学) / 乙第12928号 / 論工博第4121号 / 新制||工||1626(附属図書館) / 32138 / (主査)教授 平尾 一之, 教授 田中 勝久, 教授 三浦 清貴 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19961号 / 理博第4228号 / 新制||理||1607(附属図書館) / 33057 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 森 和俊, 教授 杤尾 豪人, 准教授 細川 暢子 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20093号 / 農博第2200号 / 新制||農||1046(附属図書館) / 学位論文||H29||N5027(農学部図書室) / 33209 / 京都大学大学院農学研究科農学専攻 / (主査)教授 土井 元章, 教授 田尾 龍太郎, 准教授 三瀬 和之 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(工学) / 甲第25288号 / 工博第5247号 / 新制||工||1999(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 辻 伸泰, 教授 安田 秀幸, 教授 岸田 恭輔 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM