Confined Bismuth–Organic Framework Anode for High‐Energy Potassium‐Ion Batteries

Abstract Metal–organic frameworks (MOFs) with inherent porosity, controllable structures, and designable components are recognized as attractive platforms for designing advanced electrodes of high‐performance potassium‐ion batteries (PIBs). However, the poor electrical conductivity and low theoretical capacity of many MOFs lead to inferior electrochemical performance. Herein, for the first time, a confined bismuth–organic framework with 3D porous matrix structure (Bi‐MOF) as anode for PIBs via a facile wet‐chemical approach is reported. Such a porous structure design with double active centers can simultaneously ensure the structure integrity and efficient charge transport to enable high‐capacity electrode with super cycling life. As a result, the Bi‐MOF for PIBs exhibits high reversible capacity (419 mAh g −1 at 0.1 A g −1 ), outstanding cycling stability (315 mAh g −1 at 0.5 A g −1 after 1200 cycles), and excellent full battery performance (a high energy density of 183 Wh kg −1 is achieved, outperforming all reported metal‐based anodes for PIBs). Moreover, the K + storage mechanisms of the Bi‐MOF are further unveiled by in situ Raman, ex situ high‐resolution transmission electron microscopy, and ex situ Fourier‐transform infrared spectroscopy. This ingenious electrode design may provide further guidance for the application of MOF in energy storage systems.