Integrating Chemical Pre‐Potassiation with Pre‐Modulated KF‐Rich Electrolyte Interfaces for Dual‐Carbon Potassium Ion Hybrid Capacitor

Abstract Herein, a chemical pre‐potassiation strategy via simultaneously treating both glucose derived carbon (GDC) anode and commercial activated carbon (CAC) cathode in potassium‐naphthalene‐tetrahydrofuran solution is developed for potassium ion hybrid capacitor (PIHC). Combined with in situ and ex situ characterizations, a radical reaction between pre‐potassiation reagent and carbon electrodes is confirmed, which not only deactivates electrochemical irreversible sites, but also promotes to pre‐form a uniform and dense KF‐rich electrolyte film on the electrodes. As a result, the pre‐potassiation treatment presents multiple advantages: (I) the initial Coulombic efficiency (CE) of the GDC anode increases from 45.4 % to 84.0 % with higher rate capability; (II) the CAC cathode exhibits the improved cycling CEs and stability due to the enhanced resistance to electrolyte oxidation at 4.2 V; (III) the assembled PIHC achieves a high energy density of 172.5 Wh kg −1 with cycling life over 10000 cycles.