Hybrid Supercapacitors In article number 2410010, Eunho Lim, Jongkook Hwang, and co-workers report on mesoporous carbon spheres with a controlled degree of mesopore openings achieved through multiscale phase separation. The study demonstrates that opening mesopores enhances the accessibility of active sites and facilitates more efficient ion transport, ultimately improving the power density of potassium-ion storage.