Layered Na₂Ti₃O₇/MgNaTi₃O₇/Mg_0.5NaTi₃O₇ Nanoribbons as High-Performance Anode of Rechargeable Mg-Ion Batteries

We report on layered Na2Ti3O7/MgNaTi3O7/Mg0.5NaTi3O7 nanoribbons for reversible electrochemical Mg storage. First, Mg2+ intercalation with irreversible Na+ deintercalation takes place in the first discharge process (Na2Ti3O7 + Mg2+ + e– → MgNaTi3O7 + Na+). Then, reversible Mg2+ insertion–extraction occurs in subsequent cycling processes (MgNaTi3O7 ↔ Mg0.5NaTi3O7 + 0.5Mg2+ + e–). This reaction with repeatable 0.5 M Mg2+ occupying the sites of Na+...