Exogenous pillaring engineering toward stable layered potassium manganese oxide cathodes

Layered potassium manganese oxides (KMO) offer a theoretically high energy density but intrinsically suffer from insufficient structural stability driven by Jahn–Teller lattice distortion. Herein, we report a spatially distributed pillaring structure that enables synergistic bulk-surface optimization via exogenous pillars within the transition-metal interlayers. The engineered subsurface Sn segregation and robust bulk Ti–O covalent framework effectively suppress associated parasitic reactions. This synergistic structural regulation accelerates K+ diffusion kinetics and significantly boosts long-term cycling stability. Consequently, the co-doped KMO cathode delivers an initial discharge capacity of 117.8 mAh g−1 at 20 mA g−1 and retains 78.1% of its capacity after 300 cycles at 200 mA g−1. Furthermore, the full cell with a commercial graphite anode exhibits exceptional cycling stability, operating reliably for over 400 cycles at 200 mA g−1, demonstrating great potential for practical applications. This work offers a structural design strategy for advancing high-performance cathodes in potassium-ion batteries.