Heterostructures assembled from graphitic carbon nitride and Ti3C2Tx MXene as high-capacity cathode for aluminum batteries.

• Heterostructured g-C 3 N 4 /Ti 3 C 2 T x endows electrode with enhanced structural stability and fast charge transfer. • The heterostructured g-C 3 N 4 /Ti 3 C 2 T x delivers superior aluminum-storage performance. • The charge-discharge mechanism for g-C 3 N 4 /Ti 3 C 2 T x is reversible intercalation of chloroaluminate anions. [Display omitted] As a compelling complement to lithium batteries, rechargeable aluminum batteries (RABs) have attracted considerable attention because of abundant natural resources, high volumetric capacity, and safety property of aluminum metal. However, the deployment of RABs is hampered by the lack of favorable cathodes with high capacity and rapid kinetics. To address the long-unresolved issue of aluminum-storage capacity and rate, here we design a heterostructured g-C 3 N 4 /Ti 3 C 2 T x hybrid which offers a conductive supporting framework to maintain structural integrity and accelerate electronic transport. The energy storage mechanism of the heterostructured g-C 3 N 4 /Ti 3 C 2 T x cathode was demonstrated as the reversible intercalation of AlCl 4 − during cycling. Moreover, the battery-capacitance model mechanism in the heterostructured g-C 3 N 4 /Ti 3 C 2 T x hybrids may accelerate the kinetics of the electrode reactions. Furthermore, DFT calculations certify that heterostructured g-C 3 N 4 /Ti 3 C 2 T x possesses enhanced electrical conductivity and Al trapping capability. Accordingly, the heterostructured g-C 3 N 4 /Ti 3 C 2 T x cathode affords RABs with an excellent Al-storage property (237 mAh g-1 at 0.5 A g-1) and considerable rate capabilities (174 mAh g-1 at 4 A g-1) among state-of-the-art cathode materials for aluminum batteries. [ABSTRACT FROM AUTHOR]