3D Flexible, Conductive, and Recyclable Ti₃C₂T_<i>x</i> MXene-Melamine Foam for High-Areal-Capacity and Long-Lifetime Alkali-Metal Anode.

Abstract

Alkali metals are ideal anodes for high-energy-density rechargeable batteries, while seriously hampered by limited cycle life and low areal capacities. To this end, rationally designed frameworks for dendrite-free and volume-changeless alkali-metal deposition at both high current densities and capacities are urgently required. Herein, a general 3D conductive Ti₃C₂T_<i>X</i> MXene-melamine foam (MXene-MF) is demonstrated as an elastic scaffold for dendrite-free, high-areal-capacity alkali anodes (Li, Na, K). Owing to the lithiophilic nature of F-terminated MXene, conductive macroporous network, and excellent mechanical toughness, the constructed MXene-MF synchronously achieves a high current density of 50 mA cm^-2 for Li plating, high areal capacity (50 mAh cm^-2) with high Coulombic efficiency (99%), and long lifetime (3800 h), surpassing the Li anodes reported recently. Meanwhile, MXene-MF shows flat voltage profiles for 720 h at 10 mA cm^-2 for the Na anode and 800 h at 5 mA cm^-2 for the K anode, indicative of the wide applicability. Notably, the high current density of 20 mA cm^-2 for 20 mAh cm^-2 for the Na anode, accompanying good recyclability was rarely achieved before. When coupled with sulfur or Na₃V₂(PO₄)₃ cathodes, the assembled MXene-MF alkali (Li, Na)-based full batteries showcase enhanced rate capability and cycling stability, demonstrating the potential of MXene-MF for advanced alkali-metal batteries.