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 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.
Jia et al. (Thu,) studied this question.