Single‐Molecule Confinement Induced Intrinsic Multi‐Electron Redox‐Activity to Enhance Supercapacitor Performance

Aggregation of polyoxometalates (POM) is largely responsible for the reduced performance of POM‐based energy‐storage systems. To address this challenge, here, the precise confinement of single Keggin‐type POM molecule in a porous carbon (PC) of unimodal super‐micropore (micro‐PC) is realized. Such precise single‐molecule confinement enables sufficient activity center exposure and maximum electron‐transfer from micro‐PC to POM, which well stabilizes the electron‐accepting molecules and thoroughly activates its inherent multi‐electron redox‐activity. In particular, the redox‐activities and electron‐accepting properties of the confined POM molecule are revealed to be super‐micropore pore size‐dependent by experiment and spectroscopy as well as theoretical calculation. Meanwhile, the molecularly dispersed POM molecules confined steadily in the “cage” of micro‐PC exhibit unprecedented large‐negative‐potential stability and multiple‐peak redox‐activity at an ultra‐low loading of ~11.4 wt%. As a result, the fabricated solid‐state supercapacitor achieves a remarkable areal capacitance, ultrahigh energy and power density of 443 mF cm −2 , 0.12 mWh cm −2 and 21.1 mW cm −2 , respectively. This work establishes a novel strategy for the precise confinement of single POM molecule, providing a versatile approach to inducing the intrinsic activity of POMs for advanced energy‐storage systems.