Supramolecular‐mediated ball‐in‐ball porous carbon nanospheres for ultrafast energy storage

Hierarchical porous carbons are the most viable electrode material for supercapacitors because of their balanced capacitive performance and chemical stability. Their pore connectivity plays a pivotal role in electrolyte transport, which is quantified by a new parameter, defined in this work as the longest possible pore separation (LPPS). Herein, we report hierarchical porous carbon nanospheres (HPC‐NS) with a unique ball‐in‐ball structure, which is achieved by the pyrolysis of a supramolecular complex of γ‐cyclodextrin (γ‐CD)/PEO‐PPO‐PEO (F127). This approach differs from the conventional soft‐templating method in that, apart from the assembly of the monomicelles that leads to the host nanospheres (approximately 300 nm), the γ‐CD‐containing monomicelles themselves are converted to small porous carbon nanospheres (