Revealing the Charge Storage Mechanism in Porous Carbon to Achieve Efficient K Ion Storage

Abstract Constructing a porous structure is considered an appealing strategy to improve the electrochemical properties of carbon anodes for potassium‐ion batteries (PIBs). Nevertheless, the correlation between electrochemical K‐storage performance and pore structure has not been well elucidated, which hinders the development of high‐performance carbon anodes. Herein, various porous carbons are synthesized with porosity structures ranging from micropores to micro/mesopores and mesopores, and systematic investigations are conducted to establish a relationship between pore characteristics and K‐storage performance. It is found that micropores fail to afford accessible active sites for K ion storage, whereas mesopores can provide abundant surface adsorption sites, and the enlarged interlayer spacing facilitates the intercalation process, thus resulting in significantly improved K‐storage performances. Consequently, PCa electrode with a prominent mesoporous structure achieves the highest reversible capacity of 421.7 mAh g −1 and an excellent rate capability of 191.8 mAh g −1 at 5 C. Furthermore, the assembled potassium‐ion hybrid capacitor realizes an impressive energy density of 151.7 Wh kg −1 at a power density of 398 W kg −1 . The proposed work not only deepens the understanding of potassium storage in carbon materials with distinctive porosities but also paves a path toward developing high‐performance anodes for PIBs with customized energy storage capabilities.