Introducing a 0.2 V sodium-ion battery anode: The Na2Ti3O7 to Na3 - xTi3O7 pathway

A new sodium storage pathway is unveiled for the anode Na2Ti3O7 which involves the newly discovered intermediate phase of Na-3 (-) xTi3O7. Details about this Na2Ti3O7 reversible arrow Na-3 (-) xTi3O7 sodium storage pathway and how it relates to the conventional Na2Ti3O7 reversible arrow Na4Ti3O7 pathway are mentioned. This Na2Ti3O7 reversible arrow Na-3 (-) xTi3O7 pathway has the lowest redox voltage of 0.2 V vs Na/Na+ ever reported for any non-carbon based sodium-ion battery anode along with moderately high capacity approaching 89 mAh/g, negligible polarization, excellent rate performance (up to 80 C, or 45s response) and good cycle life till 1500 cycles. These results indicate this pathway's potential as an anode for sodium-ion batteries meant for diverse applications. (C) 2015 Elsevier B.V. All rights reserved.