Se4+ Ion Decorated Highly Conductive Ti3C2 MXene: Promising Lithium-Ion Anodes with Enhanced Volumetric Capacity and Cyclic Performance

Two-dimensional transition metal carbide materials called MXenes show potential application for energy storage due to their remarkable electrical conductivity and low Le diffusion barrier. However, the lower capacity of MXene anodes limits their further application in lithium-ion batteries. Herein, with inspiration from the unique metal ion uptake behavior of highly conductive Ti3C2 MXene, we overcome this impediment by fabricating Sn4+ ion decorated Ti3C2 nanocomposites (PVP-Sn(IV)@Ti3C2) via a facile polyvinylpyrrolidone (PVP)-assisted liquid -phase immersion process. An amorphous Sn(IV) nanocomplex, about 6-7 nm in lateral size, has been homogeneously anchored on the surface of alk-Ti3C2 matrix by ion-exchange and electrostatic interactions. XRD and TEM results demonstrate the successful insertion of Sn4+ into the interlamination of an alkalization-intercalated Ti3C2 (alk-Ti3C2) matrix. Due to the possible pillar effect of Sn between layers of alk-Ti3C2 and the synergistic effect between the alk-Ti3C2 matrix and Sn, the nanocomposites exhibit a superior reversible volumetric capacity of 1375 mAh cm(-3) (635 mAh g(-1)) at 216.5 mA cm(-3) (100 mA g(-1)), which is significantly higher than that of a graphite electrode (550 mAh cm 3), and show excellent cycling stability after 50 cycles. Even at a high current density of 6495 mA cm(-3) (3 A g(-1)), these nanocomposites retain a stable specific capacity of 504.5 mAh cm(-3) (233 mAh g(-1)). These results demonstrate that PVP-Sn(IV)@Ti3C2 nanocomposites offer fascinating potential for high-performance lithium -ion batteries.