The interest in Mn-based layered oxides for potassium-ion batteries (PIBs) cathodes stems primarily from their impressive capacity and economic viability. However, in Mn-based layered oxides, Mn usually exhibits oxidation states between 3+ and 4+. The existence of Mn³⁺ makes these materials susceptible to substantial Jahn-Teller distortions when K⁺ are inserted or extracted. This structural instability leads to an irreversible multiphase transformation, which in turn severely impacts the cycling performance and causes significant degradation. Therefore, suppressing the Jahn-Teller distortion to reduce the phase transition and improve cyclability is of great importance.