Spin-Lattice Coupling Studies of Electrode Material for 2nd Battery
By detailed structural analysis of electrode materials for rechargeable battery with neutron powder diffraction, we should understand an iso-structural change such as an oxygen ion tilting, a change of bond distance and an occupation variation etc. for studying the conduction mechanism. An iso-structural change in electrode is appeared by the charging/discharging, size-control, doping and spin ordering process. The control of iso-structure change as functions of several external conditions is very substantial to realize next generation 2nd battery with high-capacity, high-efficiency and good-safety. In this study, we have investigated the magnetic and crystal structure of electrode NaxFe3(PO4)2(P2O7) using neutron powder diffraction. We have observed that the spin ordering of Fe induces the iso-structure change of NaxFe3(PO4)2(P2O7). Even though the spin ordering of this material is happened at a very low temperature, the imagination about correlation between crystal and magnetic structure in electrode should be proposed us the clue to realize the new concept’ 2nd battery which the conduction property of electrode can be controlled by the spin ordering of magnetic ion.