4^th European Chemistry Congress

Biography

Biography: Yutaka Moritomo

Abstract

Prussian blue analogues (PBAs:Na_xM[Fe(CN)₆]_y where M is a transition metal) have three-dimensional (3D) jungle-gym-type host framework and cubic nanopores, 0.5 nm at the edge. PBAs are promising cathode materials for lithium ion (LIBs) and sodium ion (SIBs) secondary batteries,[1-3] reflecting their nanoporous host framework. Actuially, thin film of Na_xCo[Fe(CN)₆]_0.90  shows high capacity of 135 mAh/g,[3] which is comparable to the value (= 140mAh/g) of actually-used LiCoO₂. The thin film electrode exhibits a high capacity of 121 mAh/g (90 % of the OCV value) even at 60 C. The discharge curve exhibits two plateaus at 3.8 and 3.4 V. By means of ex situ X-ray diffraction and absorption measurements, we have ascrived them the the redox processes of Fe and Co.[3]

            The thin film battery electrode is a nice platform for energy science, becauase the electrode is free free from carbon-based conducting material and polymer-based binder. With use of an optical battery cell and microscopy, we clarified the structural dynamics in the charge process (Li intercalation process) of Li_xCo[Fe(CN)₆]_0.90.[4] We cleary observed phase separation into the Li-rich and Li-poor domains of iorder of 10,000 nm. With use of the inelastic X-ray scattering technique, we clartified that local structures around Co²⁺ and Co³⁺ in Na_xCo[Fe(CN)₆]_0.90.