Porous Ti3C2Tx/bismuthene self-supporting anode for sodium storage

MXenes exhibit notable advantages as anode materials for sodium-ion storage, attributed to their high electrical conductivity and pseudocapacitive energy storage mechanism. However, MXenes generally face the issues of low sodium storage capacity and severe restacking that hinder sodium ion transport. In this work, we integrate bismuthene that possesses high sodium storage capacity with porous Ti 3 C 2 T x to construct a self-supporting anode (PM/Bi-ene) for sodium-ion batteries (SIBs) by a facile vacuum-assisted filtration process. The bismuthene not only enhances sodium storage capacity, but also serves as a spacer to prevent Ti 3 C 2 T x nanoflakes from restacking. Thanks to the high electrical conductivity of Ti 3 C 2 T x , the electrode does not require the use of any conductive agent. Furthermore, the porous structure of Ti 3 C 2 T x accelerates sodium ion transport by lowering tortuosity of the ion pathways and alleviates the volume expansion of bismuthene. Benefiting from the synergetic enhancement of Ti 3 C 2 T x and bismuthene, the PM/Bi-ene anode demonstrates a significantly increased capacity of 187 mAh/g at 0.1 A/g, compared to 93 mAh/g at the same current density without bismuthene. Additionally, it exhibits excellent rate performance, achieving 157 mAh/g at a high current density of 5 A/g. Moreover, when the PM/Bi-ene anode is assembled into a full battery paired with Na 3 V 2 (PO 4 ) 3 cathode, the battery delivers a capacity of 132 mAh/g at a current density of 0.1 A/g, demonstrating promising application prospects. Utilizing spacers with high sodium storage capacity to suppress the restacking of MXenes offers a novel pathway for the fabrication of high-performance MXene-based sodium storage materials. • A flexible self-supporting porous Ti3C2Tx/bismuthene composite film with reduced tortuosity was fabricated. • The porous MXene nanoflakes buffer the stress induced by the volume change of bismuthene, leading to good cycling stability. • The composite anode exhibits enhanced performance compared to pure porous MXene and other Bi-containing MXene-based anodes.