MOF-derived hierarchical porous carbon octahedrons for aluminum-ion batteries

Rechargeable aluminum-ion batteries (AIBs) have aroused increasing interest due to good safety and economy, together with high theoretical volumetric capacities. Graphitized carbon materials and urea-based ionic liquid (IL) have been demonstrated as promising cathode materials and electrolyte of AIBs for high discharging voltage and low cost. Here we performed in situ Raman spectroscopy to investigate the reaction mechanism of Al/graphite in AlCl₃/urea mixture IL electrolyte. The experimental evidences demonstrated that poor reaction kinetics of graphite cathode in urea-based IL at room temperature restricts the rate performance and further applications. In this work, we presented hierarchical porous carbon octahedrons (HPCO) derived from Cu-based metal organic framework (MOF) as a promising cathode material of AIBs. Advanced scanning electron microscopy (SEM) technologies were employed to reveal the hierarchical porous architecture. Benefited from the unique hierarchical porous structure and robust graphitic carbon nature, the Al/HPCO batteries exhibited a well-maintained specific capacity of ∼60.8 mA h g⁻¹ after charge/discharge 200 cycles at a current density of 100 mA g⁻¹ and a much better rate performance than graphite paper (GP) electrodes. This may provide extensive solutions to future research on AIBs and practical applications of AIBs technically.