Lithium Intercalation into the Jarosite-type Hydroxysulfate: a Topotactic Reversible Reaction from a Crystalline Phase to an Inorganic Polymer-like structure

by Muthaiyan Gnanavel , Valerie Pralong , Oleg I Lebedev , Vincent Caignaert , Philippe Bazin , and Bernard Raveau
Chemistry of Materials., Just Accepted Manuscript
DOI: 10.1021/cm501735t

Insertion of lithium into the jarosite hydroxysulfate NaFe3(SO4)2(OH)6 leads to an amorphous phase Li2+xNaFe3(SO4)2(OH)6 (with 0<x<0.5), through a biphasic mechanism. The latter phase exhibits reversible electrochemical lithium intercalation/deintercalation through a solid solution- like process, leading back to the oxidized jarosite LixNaFe3(SO4)2(OH)6 (with 0.3<x<0.6), with redox cycling at 2.82V and a capacity of 110 mAh/g at C/20. This unique topotactic reaction between an amorphous and a well crystallized phase is interpreted on the basis of the formation of an inorganic polymer.