Tailoring Nitrogen Terminals on MXene Enables Fast Charging and Stable Cycling Na-Ion Batteries at Low Temperature

Abstract Sodium-ion batteries stand a chance of enabling fast charging ability and long lifespan while operating at low temperature (low-T). However, sluggish kinetics and aggravated dendrites present two major challenges for anodes to achieve the goal at low-T. Herein, we propose an interlayer confined strategy for tailoring nitrogen terminals on Ti3C2 MXene (Ti3C2-Nfunct) to address these issues. The introduction of nitrogen terminals endows Ti3C2-Nfunct with large interlayer space and charge redistribution, improved conductivity and sufficient adsorption sites for Na+, which improves the possibility of Ti3C2 for accommodating more Na atoms, further enhancing the Na+ storage capability of Ti3C2. As revealed, Ti3C2-Nfunct not only possesses a lower Na-ion diffusion energy barrier and charge transfer activation energy, but also exhibits Na+-solvent co-intercalation behavior to circumvent a high de-solvation energy barrier at low-T. Besides, the solid electrolyte interface dominated by inorganic compounds is more beneficial for the Na+ transfer at the electrode/electrolyte interface. Compared with of the unmodified sample, Ti3C2-Nfunct exhibits a twofold capacity (201 mAh g−1), fast-charging ability (18 min at 80% capacity retention), and great superiority in cycle life (80.9%@5000 cycles) at − 25 °C. When coupling with Na3V2(PO4)2F3 cathode, the Ti3C2-Nfunct//NVPF exhibits high energy density and cycle stability at − 25 °C.