Low-temperature-pyrolysis preparation of nanostructured graphite towards rapid potassium storage with high initial Coulombic efficiency

Industrially prepared artificial graphite (AG) is attractive for potassium-ion batteries (PIBs), but its rate performance is poor and the production process is energy intensive, so developing an efficient strategy to produce novel graphite with low energy consumption and high performance is economically important. Herein, a nanostructured graphite composed of multi-walled carbon nanotubes (MWCNTs) and graphite shells was prepared by one-pot method through low-temperature pyrolysis of iron-based metal-organic framework (MOF) and carbon source. The high graphitization degree of nanostructured graphite makes the initial Coulombic efficiency (ICE) exceed 80%, and the three-dimensional (3D) conductive network ensures a specific capacity of 234 mAh·g⁻¹ after 1000 cycles at a high current density of 500 mA·g⁻¹. In addition, the typical graphite potassium storage mechanism is also demonstrated by in situ X-ray diffraction (XRD) and in situ Raman spectroscopy, and its practicality is also proved by the voltage of the full cells. This work provides a feasible way to optimize the practical production process of AG and expand its application in energy storage.