Bi/Bi3Se4 nanoparticles embedded in hollow porous carbon nanorod: High rate capability material for potassium-ion batteries

Considering their superior theoretical capacity and low voltage plateau, bismuth (Bi)-based materials are being widely explored for application in potassium-ion batteries (PIBs). Unfortunately, pure Bi and Bi-based compounds suffer from severe electrochemical polarization, agglomeration, and dramatic volume fluctuations. To develop an advanced bismuth-based anode material with high reactivity and durability, in this work, the pyrolysis of Bi-based metal–organic frameworks and in-situ selenization techniques have been successfully used to produce a Bi-based composite with high capacity and unique structure, in which Bi/Bi3Se4 nanoparticles are encapsulated in carbon nanorods (Bi/Bi3Se4@CNR). Applied as the anode material of PIBs, the Bi/Bi3Se4@CNR displays fast potassium storage capability with 307.5 mA h g−1 at 20 A g−1 and durable cycle performance of 2000 cycles at 5 A g−1. Notably, the Bi/Bi3Se4@CNR also showed long cycle stability over 1600 cycles when working in a full cell system with potassium vanadate as the cathode material, which further demonstrates its promising potential in the field of PIBs. Additionally, the dual potassium storage mechanism of the Bi/Bi3Se4@CNR based on conversion and alloying reaction has also been revealed by in-situ X-ray diffraction.