Mg2+ induced Ti3C2Tx MXene@microfibrillated cellulose into composite aerogels in a framework of melamine sponge for high-rate performance supercapacitors

Inducing Ti₃C₂T_x MXene nanosheets to self-assemble into three-dimensional aerogels is an effective strategy to solve their accumulation and improve the performance of supercapacitors. However, MXene aerogels are prone to collapse in practical applications due to their low mechanical strength. Here, the low-cost melamine sponge (MS), which adsorbs Mg²⁺ ions on the skeleton surface serves as a support and induces the gelation of MXene nanosheets and microfibrillated cellulose (MFC) mixed solution to form composite hydrogels, and thereby obtaining MXene composite aerogels with high loading mass and mechanical strength. The experimental results show that the Mg-10%MFMX@MS aerogel has the largest area capacitance of 685.77 mF cm⁻² at a scan rate of 10 mV s⁻¹. Thanks to its excellent three-dimensional structure, even at a high scan rate of 1000 mV s⁻¹, the area capacitance is still 497.41 mF cm⁻², and the capacity retention rate is 72.53 %, showing high-rate performance. It is worth noting that the constructed asymmetric activated carbon supercapacitors achieved high energy densities of 128.78 μWh cm⁻² and 101.15 μWh cm⁻² at 850 μW cm⁻² and 17,000 μW cm⁻², respectively. In addition, the asymmetric supercapacitor has high cycling stability and a capacity retention rate of 115 % after 10,000 cycles. This work provides a feasible strategy for fabricating Ti₃C₂T_x MXene aerogels with high-rate performance and high strength.