We carried out redox-couple and counter-cation exchange in NASICON-type M_2(XO_4)_3 (M: Fe and Al; X: S, Mo and W) to control the cathode performance. The Fe^<3+>/Fe^<2+> redox potential in NASICON matrix is changed by the local crystalline field at the iron resulting from polarization of oxygen towards the counter cation in the polyanionic complex. It is confirmed by ^<57>Fe Mossbauer resonance, Fe-2p XPS, Mo K-XAFS and electrochemical measurements. This inductive effect in NASICON matrix is a significant material control technique for cathode design. We also found a promising anode candidate by ion exchange of Fe by Al in Fe_2(MoO_4)_3. The reversible capacity of Al_2(MoO_4)_3 reached almost 200mAh/g between 3.5V and 1.2V.
|Translated title of the contribution||Inductive Effect in NASICON-Type Cathodes for Lithium Secondary Batteries|
|Number of pages||5|
|Journal||The Reports of Institute of Advanced Material Study,Kyushu University|
|Publication status||Published - Dec 1999|