Tailoring K$^+$/Vacancy Disordered Layered Oxide via Charge Engineering for Stabilizing High‐Performance Potassium‐Ion Batteries

Layered transition metal oxides represent attractive cathode candidates for potassium-ion batteries (PIBs), due to their high theoretical specific capacity. However, sluggish K$^+$ diffusion and structural instability, stemming from the inherent K$^+$/vacancy ordered structure, lead to poor rate performance and cycling stability. Herein, a charge-ion coupling engineering strategy, wherein transition-metal electronic structure is tuned to modulate interlayer K$^+$/vacancy configurations, is initially pioneered. Specifically, a K$^+$/vacancy-disordered P3-type structure is constructed via targeted transition metal (TM) doping in Mn/Co-based layered oxides. Exploiting the identical valence of Ti$^{4+}$ and Mn$^{4+}$ coupled with their divergent redox potential, the doping sites suppress charge ordering within TM slabs through modulating charge delocalization, thereby inducing interlayer K$^+$/vacancy disordering. The K$^+$/vacancy disordered K$_{0.5}$Mn$_{0.8}$Co$_{0.1}$Ti$_{0.1}$O$_2$ delivers long-term stability with 58.6 mAh g$^{−1}$ over 800 cycles at 1 A g$^{−1}$ and remarkable rate capability of 61.7 mAh g$^{−1}$ at 2 A g$^{−1}$, facilitating a highly reversible single-phase solid-solution reaction in K$_{0.5}$Mn$_{0.8}$Co$_{0.1}$Ti$_{0.1}$O$_2$ and enhancing the structural stability during K$^+$ extraction/insertion. ... mehrMeanwhile, molecular dynamics simulations demonstrate that the K$^+$/vacancy disordered structure contains interconnected channels enabling continuous and rapid K$^+$ diffusion. This work establishes a cation substitution strategy for manipulating K$^+$/vacancy order-disorder to develop high-performance, kinetically robust cathode materials for next-generation PIBs.