【公開日：2024.07.25】【最終更新日：2024.04.12】
課題データ / Project Data
課題番号 / Project Issue Number
23HK0134
利用課題名 / Title
New Phase Generation from Amorphous Structure: Atomic Rearrangements in Amorphous Nb-doped TiO2 through Electrochemical Lithium Insertion/extraction
利用した実施機関 / Support Institute
北海道大学 / Hokkaido Univ.
機関外・機関内の利用 / External or Internal Use
内部利用（ARIM事業参画者以外）/Internal Use (by non ARIM members)
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）物質・材料合成プロセス/Molecule & Material Synthesis
【重要技術領域 / Important Technology Area】（主 / Main）革新的なエネルギー変換を可能とするマテリアル/Materials enabling innovative energy conversion（副 / Sub）高度なデバイス機能の発現を可能とするマテリアル/Materials allowing high-level device functions to be performed
キーワード / Keywords
Generation of new crystalline structure from amorphous,電子顕微鏡/ Electronic microscope,放射光/ Synchrotron radiation,赤外・可視・紫外分光/ Infrared/visible/ultraviolet spectroscopy,二次電池/ Secondary battery,燃料電池/ Fuel cell,全固体電池/ All-solid battery,エネルギー貯蔵/ Energy storage,環境発電/ Energy Harvesting,自己修復材料/ Self-healing material,メタマテリアル/ Metamaterial,ハイブリッドボンディング/ Hybrid Bonding
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
孫 宇
所属名 / Affiliation
北海道大学 理学研究院 化学専攻 情報化学研究室
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
利用形態 / Support Type
（主 / Main）機器利用/Equipment Utilization（副 / Sub）,技術補助/Technical Assistance
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
Lithium-ion battery is currently the leading technology for electric vehicles and is quite attractive to the stationary energy storage for renewable energy resources. Consequently, great interest has been focused on searching electrode materials for large scale batteries that can satisfy requirements in cost, stability, and most importantly, safety for the successful market penetration.[1] In “Challenges for Rechargeable Li batteries” written by Prof. Goodenough, the investigations related to HOMO/LUMO in active materials, electrochemical potential controlling, and SEI (solid electrolyte interface) layer were discussed. Still, plenty of problems are remained in this field, waiting for both the fundamental understanding and technical improvements. Among these problems, the structure evolution during the Li+ ion insertion/extraction process is extremely important because 1) the critical degradation mechanism of many anode/cathode materials for Li+ ion battery is closely related to phase transformations at the surface/interface; 2) during the Li+ ion insertion/extraction process, the ratio of Li+ site/Li+ holes changes simultaneously. Sometimes, the cation or anion in the framework may move within the framework because of the Li+ ion insertion/extraction. The disordered or ordered atomic arrangement may lead to the distortion of crystalline structure or the formation of new phases or solid solutions. In addition, recent studies on other transition metal oxides have suggested that electrochemical cycling may present a new synthetic method to obtain novel structures and frameworks. In the system of pure TiO2, amorphous TiO2 underwent spontaneous phase transformation into a long-range-ordered/short-range-disordered cubic structure when cycled with Li+; while in the system of pure Nb2O5, amorphous Nb2O5 transformed to rock-salt crystalline structure. Both considered that atomic rearrangements can be initiated when Li+ reached a high concentration to minimize the system energy. However, the fundamental understanding of this synthetic method, ion pathway, transformation mechanism were not clear yet.
実験 / Experimental
In this work, we synthesized amorphous Nb-doped TiO2 by our previously developed method. Through the electrochemical lithium insertion/extraction, the crystalline structure evolution in amorphous Nb-doped TiO2 system was investigated through ex/in situ measurements. As references, pure TiO2 (anatase), pure Nb2O5 (orthorhombic) synthesized by the same method were characterized to clarify the atomic re-arrangements in amorphous Nb-doped TiO2. Through repeated Li ion insertion/extraction by CV measurements, we examined that how new phase generated.
結果と考察 / Results and Discussion
From HR-TEM measurements, we observed the formation of nanoparticles with the size of 3-5 nm. Combining with XRD measurements and electron diffraction pattern, we confirmed the new phase formation and identified the rock-salt structure. However, we could not identify the elements inside. Therefore, this month, we booked EELS-TEM again and try to identify the element inside.
図・表・数式 / Figures, Tables and Equations
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件