Layered oxides with solid-solution reaction for high voltage potassium-ion batteries cathode

The development of high-performance potassium-ion batteries (PIBs) is challenged by the availability of stable cathode materials, which are known to undergo complex phase transitions and irreversible structural degradation especially charged to high voltage. Here, we reported a P2-type cathode in formula of K0.6Mn0.8Ni0.1Ti0.1O2 (KMNT), which exhibited a highly reversible K+ (de)intercalation capability up to 4.2 V. We demonstrated that the coexistence of Ni and Ti was able to not only suppress the structural damage related to the Jahn-Teller effect of Mn3+, a critical factor accounting for the performance degradation of Mn-based PIBs cathodes, but also restrain the detrimental lattice sliding of transition metal layers at high voltage. Accordingly, the structurally engineered KMNT showed a much favored solid-solution reaction with a successful elimination of the destructive phase degradation at deep depotassiation state. Our results highlighted the essential role played by the lattice design of cathode materials in modulating their electrochemical behavior for stable and high-performance PIBs.