Two-Dimensional F-Ti3C2Tx@Ag Composite for an Extraordinary Long Cycle Lifetime with High Specific Capacity in an Aluminum Battery.

According to the current research, the graphene-like two-dimensional materials present excellent electrochemical performance in aluminum batteries. However, there is less research on emerging two-dimensional materials in aluminum batteries, and the energy storage mechanism is ambiguous. Herein, we modified the two-dimensional few layered Ti3C2Tx (F-Ti3C2Tx) with Ag+ and prepared a composite material F-Ti3C2Tx@Ag. The results of physical characterization show that Ag+ is reduced to Ag by Ti ions and is in situ grown on the surface and interlayer of F-Ti3C2Tx. More importantly, the electrochemical performance of the two-dimensional material F-Ti3C2Tx@Ag is studied in an aluminum battery and shows extraordinary long cycle lifetime with high specific capacity. The discharge specific capacity is about 150 mA h g-1 after 2000 cycles at a current density of 0.5 A g-1. Furthermore, the energy storage mechanism of F-Ti3C2Tx@Ag in aluminum batteries is studied, which shows that it is mainly the intercalation/de-intercalation of [AlCl4]-, accompanied by a small amount of Al3+ intercalating/de-intercalating. In addition, density functional theory (DFT) calculations are carried out to study the interaction between MXene@Ag and [AlCl4]- and between MXene and [AlCl4]-. The results show that [AlCl4]- anions are easier to intercalate/de-intercalate between the layers of Ti3C2O2-Ag.