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 Ti⁴⁺ and Mn⁴⁺ 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 K0.5Mn0.8Co0.1Ti0.1O₂ 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 K0.5Mn0.8Co0.1Ti0.1O₂ and enhancing the structural stability during K⁺ extraction/insertion. Meanwhile, 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.