Cation-induced Ti₃C₂T_x MXene@melamine sponge aerogels with large layer spacing and high strength for high-performance...

The self-assembled aerogels are considered as an efficient strategy to address the aggregation and restacking of Ti₃C₂T_x MXene nanosheets for high-performance supercapacitors. However, the low mechanical strength of the MXene aerogel results in the structural collapse of the self-standing supercapacitor electrode materials. Herein, a low-cost melamine sponge (MS) absorbed different cations (H⁺, K⁺, Mg²⁺, Fe²⁺, Co²⁺, Ni²⁺ and Al³⁺), serves as a carrier and crosslinker for loading MXene hydrogel induced by the absorbed cations on the skeleton surface and the pores of MS, resulting in the high loading mass MXene aerogels with high mechanical strength. The experimental results show that the Mg-Ti₃C₂T_x@MS aerogel exhibits the maximum area capacitance of 702.22 mF cm^-2 at 3 mA cm^-2, and the area capacitance is still 603.12 mF cm^-2 even at 100 mA cm^-2, indicating the high rate capability with a capacitance retention of 85.89 %. It is worth noting that the constructed asymmetric supercapacitor with activated carbon achieves high energy densities of 104.53 μWh cm^-2 and 93.87 μWh cm^-2 at 800 μW cm^-2 and 7999 μW cm^-2, respectively. Furthermore, the asymmetric supercapacitor shows the high cycling stability with 90.2 % capacity retention after 10,000 cycles. This work provides a feasible strategy to prepare Ti₃C₂T_x MXene aerogels with large layer spacing and high strength for high-performance supercapacitors.