In Situ Defect Engineering in Carbon by Atomic Self‐Activation to Boost the Accessible Low‐Voltage Insertion for Advanced Potassium‐Ion Full‐Cells

Abstract Enhancing the low‐potential capacity of anode materials is significant in boosting the operating voltage of full‐cells and constructing high energy‐density energy storage devices. Graphitic carbons exhibit outstanding low‐potential potassium storage performance, but show a low K + diffusion kinetics. Herein, in situ defect engineering in graphitic nanocarbon is achieved by an atomic self‐activation strategy to boost the accessible low‐voltage insertion. Graphitic carbon layers grow on nanoscale‐nickel to form the graphitic nanosphere with short‐range ordered microcrystalline due to nickel graphitization catalyst. Meanwhile, the widely distributed K + in the precursor induces the activation of surrounding carbon atoms to in situ generate carbon vacancies as channels. The graphite microcrystals with defect channels realize reversible K + intercalation at low‐potential and accessible ion diffusion kinetics, contributing to high reversible capacity (209 mAh g −1 at 0.05 A g −1 under 0.8 V) and rate capacity (103.2 mAh g −1 at 1 A g −1 ). The full‐cell with Prussian blue cathode and graphitic nanocarbon anode maintains an obvious working platform at ca. 3.0 V. This work provides a strategy for the in situ design of carbon anode materials and gives insights into the potassium storage mechanism at low‐potential for high‐performance full‐cells.