Development of advanced energy storage system based on overall strategies on new materials and new interface

2019 Fiscal Year Final Research Report

• Project/Area Number: 15H05701
• Research Category: Grant-in-Aid for Specially Promoted Research
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering; Engineering
• Research Institution: The University of Tokyo
• Principal Investigator: YAMADA Atsuo 東京大学, 大学院工学系研究科, 教授 (30359690)
• Co-Investigator(Kenkyū-buntansha): OKUBO masashi 東京大学, 大学院工学系研究科, 准教授 (20453673) ; YAMADA yuki 東京大学, 大学院工学系研究科, 講師 (30598488) ; NISHIMURA shin-ichi 東京大学, 大学院工学系研究科, 主任研究員 (00549264) ; TATEYAMA yoshitaka 物質・材料研究機構, エネルギー・環境材料研究拠点, グループリーダー (70354149) ; HARADA yoshihisa 東京大学, 物性研究所, 教授 (70333317) ; ASAKURA daisuke 産業技術総合研究所, エネルギー・環境領域, 主任研究員 (80435619) ; NAKAI Hiromi 早稲田大学, 理工学術院, 教授 (00243056) ; OTANI minoru 産業技術総合研究所, 材料・化学領域, 研究チーム長 (50334040) ; YABUUCHI naoaki 横浜国立大学, 大学院工学研究院, 教授 (80529488)
• Project Period (FY): 2015 – 2019
• Keywords: 電池 / 電極 / 酸化還元 / 電解液 / 界面 / 第1原理計算 / 分子動力学計算

Outline of Final Research Achievements

Through careful overlooking and reconsiderations of materials science for energy storage by combined experimental, spectroscopic, and computational approach, we demonstrated several effective strategies and new materials, together with battery devices including functional interfaces. Towards activation of oxygen redox in solids to achieve much larger amount of charge storage, we established molecular-orbital principles and identified two metastable intermediate, alternate spin state and oxygen-oxygen bonding, which induce voltage hysteresis upon charge-discharge. To avoid such energy loss and activate stable oxygen redox, introduction of ordered vacancy showed promising by modulated electric states and self-reordering phenomenon induced by cooperative Coulombic interaction. Also, we discovered negative permittivity of water molecules confined in nanosheets that largely (1.7 times) increase interfacial capacitance. Increasing salt concentration was revealed to modulate coordination structure, electric state, and interface, to largely improve several battery functions. Particularly, aqueous systems have realized surprisingly wide stable voltage range exceeding 4 V (1.2 V in pure water). Besides, accumulating multi-functions into single solvent molecule have established a practical strategy for industry. A prototype battery cell realized cut-off voltage of 5.2 V with stable cycling over 1000 times, corresponding to 1.3 – 2.6 times larger energy density than that of lithium-ion batteries.

Academic Significance and Societal Importance of the Research Achievements

構築した学術体系のNature Energy誌4報等による積極的発信を通じた高い国際的認知と影響度により、新たな学際研究領域を創成しているばかりでなく、今後の高機能材料開発に向けた明確なプロトコルを提供しており、産業界・工学への大きな波及効果も見込まれる。

Free Research Field

化学