Highly stable Ti3C2Tx MXene-based sandwich-like structure via interfacial self-assembly of nitrogen-rich polymer network for superior sodium-ion storage performance

To improve sluggish reaction kinetics and solve the severe self-stacking of MXene-based anodes for sodium ion batteries (SIBs), a novel highly stable sandwich-like structure with tunable interspace supported by dense N-rich polymer hydrogen-bonding network is synthesized for improving the pseudo-capacitance of Ti3C2Tx MXene. The interconnected MXene-based sandwich structure can establish the stable conductive framework, abundant active sites and tunable interspace that provide channels for rapid Na+ storage. Besides, the dense polymer hydrogen-bonding network can effectively prevent interlayer restacking for ultra-stable Na+ storage. After modification, the N contents of Ti3C2Tx MXene are increased to 21.63 at %. N-rich polymer network not only provides extra active sites for pseudo-capacitance Na+ storage, but also accelerates Na+ transport and charge transfer. As the anode for half-cell of SIBs, it shows excellent cycling performance of 148.4 mAh g−1 after 3000 cycles at 500 mA g−1 with capacity retention of 102.4 % and 123.4 mAh g−1 after 5000 cycles at 1000 mA g−1. The performance of full-cell based on the optimized composite anode and Na3V2(PO4)3 (NVP) cathode is superior to other MXene-based full-cell of SIBs. The novel sandwich-like structure delivers a perspective for enhancing the stability and achieving fast Na+ diffusion of layer structure by polymer hydrogen-bonding network.