Reversible Mg-Ion Insertion in a Metastable One-Dimensional Polymorph of V2O5

The Li-ion paradigm of battery technology is constrained by the monovalency of the Li ion. A straightforward solution is to transition to multivalent-ion chemistries, where Mg2+ is the most obvious candidate because of its size and mass. The realization of Mg batteries has faced myriad obstacles, including a sparse selection of cathode materials demonstrating the ability to reversibly insert divalent ions. Here, we provide evidence of reversible...