Development of magnesium batteries using topotactic extraction/insertion reactions of oxide ions from/in transition metal oxides for cathode reactions

2015 Fiscal Year Final Research Report

• Project/Area Number: 26630493
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Energy engineering
• Research Institution: The University of Tokyo
• Principal Investigator: HIBINO Mitsuhiro 東京大学, 工学(系)研究科(研究院), 上席研究員 (20270910)
• Co-Investigator(Kenkyū-buntansha): MIZUNO Noritaka 東京大学, 大学院工学系研究科, 教授 (50181904)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 二次電池 / マグネシウム電池 / 正極材料 / ペロブスカイト型酸化物

Outline of Final Research Achievements

Perovskite-type SrFeO3 was applied to a cathode material of magnesium batteries. When a SrFeO3 cathode was used with a MgClO4/PC electrolyte solution and a Mg metal anode, SrFeO3 underwent extraction of oxide ions and changed into SrFeOx (x: between 2.75 and 3.0) in the early period of discharge, followed by a two phase coexistence reaction between a perovskite-type phase SrFeOx (x: near 2.75) and a brownmillerite-type phase SrFeO2.5. Thermodynamic consideration on the basis of relationship between the average valence number of iron ions and the number of charge transfer suggested that the oxide ions extracted from SrFeOx and magnesium ions in the electrolyte solution formed first MgO2 and then MgO. In the case that discharge was terminated in the stage of MgO2 formation, subsequent charge was possible. It resulted in a specific charge-discharge capacity of 60-70 mAh/g.

Free Research Field

固体電気化学