Designing hollow Ti₃C₂@TiSe₂ composites for long cycle life of sodium-ion storage

The construction of an anode material with high electrical conductivity and long cycle stability was essential for the practical application of Sodium-ion batteries (SIBs). Hollow Ti3C2@TiSe2 composites were successfully synthesized using in situ selenization methods from MXene-derived materials. The composites obtained in this study exhibited an impressive reversible capacity, attaining a specific capacity of 561 mAh g(-1) when tested at a current density of 0.1 A g(-1).The specific capacity remained stable at 201 mAh g(-1) through 12,000 cycles at a high current density of 10 A g(-1). When utilizing Na3V2(PO4)(3)@C (NVP@C) as the cathode in a full cell, it demonstrated a sustained specific capacity of 138 mAh g(-1) over 50 cycles at a current density of 100 mA g(-1). Additionally, a capacity of 98 mAh g(-1) was maintained over 500 charge-discharge cycles at a higher current density of 1000 mA g(-1). The reaction mechanism of Na+ was confirmed through reaction kinetics and ex-situ XRD test. This study demonstrated that the special hollow structure comprised of Ti3C2 and TiSe2 enhanced the material's structural stability as well as the surface activity.