Disordering mechanism during Li ion intercalation in nano-rutile TiO₂

Abstract

Traditional Li-ion battery electrodes are highly crystalline materials in which the ions are intercalated between atomic layers or channels in the atomic lattice. Such electrodes are typically characterized by retaining their crystallinity for many charge-discharge cycles. However, a number of electrode materials undergo an irreversible loss of crystallinity upon Li-intercalation. Examples of such materials are rutile TiO2 and orthorhombic V2O5, which loses long range order upon intercalation of >0.8 and >2 Li, respectively [1,2]. Very little is presently known about neither the mechanism of such order-disorder phenomena nor about how ion storage occurs in disordered structures in subsequent charge-discharge cycles. This is in spite that such materials represent cheap and effective alternatives to their crystalline counterparts, i.e. recently amorphous V2O5 was shown to reversibly store close to double the amount of Na-ions as compared to crystalline V2O5 [3].