Rutile TiO2 as a novel anode material for Na-ion battery

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K05954
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Device related chemistry
• Research Institution: Tottori University
• Principal Investigator: USUI Hiroyuki 鳥取大学, 工学研究科, 准教授 (60423240)
• Research Collaborator: SAKAGUCHI hiroki ; DOMI yasuhiro
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: ルチル型TiO2 / ナトリウムイオン電池 / 負極 / Nbドーピング

Outline of Final Research Achievements

A sodium-ion battery is an attractive storage battery because it can be constructed of rare-metal-free materials. However, the Na+ diffusion in the negative electrode material is extremely slow due to the large size of Na+. Because of this, the rate of charge and discharge is very low, which hinders the practical use of this battery.
In this study, we succeeded in developing a rutile TiO2 negative electrode that does not contain rare elements, is low in cost, and has a wide size Na+ diffusion path. By Nb-doping into TiO2, its electronic conductivity is improved by more than 1000 times, and in addition, the size of the Na+ transfer path is expanded, creating a space where Na+ can move quickly. Therefore, the high-rate performance was improved.

Free Research Field

電気化学

Academic Significance and Societal Importance of the Research Achievements

アナターゼ相はイオン移動に適した三次元的な拡散経路を有するため，多くの研究がなされてきたが，国内ではルチル相に焦点を当てた研究は皆無であった．この背景の下，本研究ではルチル型TiO2にNbをドープすることで電子伝導性の低さを克服し，そのうえで粒子サイズに対する結晶子サイズの割合を高めることで，潜在的なイオン拡散能を開花させNa+充放電特性を発現させることに世界で初めて成功した．その学術的意義を裏付けるように，成果をまとめた論文（ACS Appl. Mater. Interfaces, 7 (2015) 6567.）の被引用数は発表後4年間で120回を超え，国内外で著しく高い注目を集めている．