Novel design and synthesis of 1D bamboo-like CNTs@Sn₄P₃@C coaxial nanotubes for long-term sodium ion storage

In this work, a novel bamboo-like carbon nanotubes@Sn₄P₃@carbon (BLCNTs@Sn₄P₃@C) coaxial nanotubes are designed and prepared using a newly developed hydrothermal method followed by a phophidation process. The prepared Sn₄P₃ nanoparticles are uniformly coated and wrapped on the one-dimensional (1D) bamboo-like CNTs, which is covered by a uniform carbon layer to form a sandwich-like structure with Sn₄P₃ in between. The inner CNT and outer carbon can effectively maintain the structural stability and serve as the good electron conductors. Additionally, the outer carbon coating layer can effectively keep BLCNTs@Sn₄P₃@C nanotubes separate each other, preventing aggregation of Sn₄P₃ during charge/discharge when this material is used as anode for sodium ion batteries. The anode of BLCNTs@Sn₄P₃@C shows excellent reversible capacity and a long cycling of over 2000 cycles. The unique design of coaxial nanotubes is greatly beneficial to the electrochemical performance of Sn₄P₃ for sodium ion storage.