Decoupling KOH Activation Path to Construct Graphitic Porous Carbon Anode for Enhanced Potassium Ion Storage
Fei Yuan, Ziyu Wu, Zhaojin Li, Qujiang Sun, Qiujun Wang, Ranran Li, Wei Wang, Di Zhang, Bo Wang
Abstract
Abstract Carbonaceous anodes with concurrently rich pore channels and plenty of continuous graphitic domains are highly desirable for potassium‐ion batteries by virtue of their excellent ion and electron transport ability, but the traditional activation strategy tends to cause an imbalance between graphitization and porosity. Herein, a graphitic porous carbon is successfully developed by introducing pre‐carbonization to change the KOH activation pathway. It is demonstrated that the introduced pre‐carbonization step greatly reduces oxygen content and promotes carbon microcrystals initial growth, which results in the formation of molten K 2 CO 3 rather than C‐O‐K species. As a result, the liquid‐phase reaction environment provided by molten K 2 CO 3 can drive isolated microcrystalline assemblies to form continuous graphitic domains. Benefiting from these synergistic merits, the optimized sample delivers excellent ion/electron migration kinetics, enabling 236.2 mAh g −1 at 2 A g −1 . Moreover, the pores composed of large sized micropores and newly formed mesopores accelerate electrolyte infiltration and increase capacitive contribution to a large extent, giving rise to a high capacity and superb cycling stability over 3000 cycles at 2 A g −1 . The assembled full cell can realize a high energy density of 104.6 Wh kg −1 at an ultra‐high‐power density of 3.26 kW kg −1 .