2D MXenes are attractive for energy storage applications because of their high electronic conductivity. However, it is still highly challenging for improving the sluggish sodium (Na)-ion transport kinetics within the MXenes interlayers. Herein, a novel nitrogen-doped Ti₃C₂T_x MXene was synthesized by introducing the in situ polymeric sodium dicyanamide (Na-dca) to tune the complex terminations and then utilized as intercalation-type pseudocapacitive anode of Na-ion capacitors (NICs). The Na-dca can intercalate into the interlayers of Ti₃C₂T_x nanosheets and simultaneously form sodium tricyanomelaminate (Na₃TCM) by the catalyst-free trimerization. The as-prepared Ti₃C₂T_x/Na₃TCM exhibits a high N-doping of 5.6 at.% in the form of strong Ti–N bonding and stabilized triazine ring structure. Consequently, coupling Ti₃C₂T_x/Na₃TCM anode with different mass of activated carbon cathodes, the asymmetric MXene//carbon NICs are assembled. It is able to deliver high energy density (97.6 Wh kg⁻¹), high power output (16.5 kW kg⁻¹), and excellent cycling stability (≈ 82.6% capacitance retention after 8000 cycles).

2D MXene由于具有高电导率，因此对于储能应用很有吸引力。但是，改善MXenes中间层内缓慢的钠（Na）离子传输动力学仍然是极富挑战性的。在此，通过引入原位聚合双氰胺钠（Na-dca）来调节复杂的末端，从而合成了一种新型的氮掺杂的Ti ₃ C ₂ T _x MXene，然后将其用作Na离子电容器（NIC）的插层型伪电容阳极）。Na-dca可以插入Ti ₃ C ₂ T _x纳米片的中间层中，同时形成三氰化钠（Na ₃TCM）通过无催化剂三聚。所制备的Ti ₃ C ₂ T _x / Na ₃ TCM以牢固的Ti-N键和稳定的三嗪环结构形式表现出5.6 at。％的高N掺杂。因此，将Ti ₃ C ₂ T _x / Na ₃ TCM阳极与不同质量的活性炭阴极耦合在一起，组装了不对称MXene //碳NIC。它能够提供高能量密度（97.6 Wh kg ^-1），高功率输出（16.5 kW kg ^-1）和出色的循环稳定性（8000个循环后≈82.6％的电容保持率）。