Structurally stable P3-type K0.45MnO2 cathode with a KTaO3 protective layer for high-performance potassium-ion batteries

Manganese-based layered oxides have emerged as promising cathode materials for potassium-ion batteries (KIBs) due to their low cost, high specific capacity, and elevated operating potential. However, their practical application is hindered by limited cycling stability, primarily due to Jahn-Teller distortion, poor interfacial stability, and sluggish electrochemical kinetics. In this study, a novel KTaO₃-coated K_0.45Mn_0.9Zn_0.1O₂ (KTO/KMZO-1) cathode was designed to enhance electrochemical performance through structural stabilization via Zn²⁺ substitution and surface modification using KTaO₃ coating. Structural analysis confirms that substituting Mn³⁺/Mn⁴⁺ with Zn²⁺ effectively alleviates Jahn-Teller distortion and expands K⁺ diffusion channels, improving ionic mobility. Meanwhile, the robust KTaO₃ coating enhances interfacial stability by mitigating side reactions at the cathode-electrolyte interface and promoting the formation of a uniform, inorganic-rich CEI layer. As a result, KTO/KMZO-1 exhibits excellent rate capability, delivering 71.05 mAh g^-1 at 400 mA g^-1, along with remarkable cycling stability, retaining 80.06 % of its initial capacity after 200 cycles at 200 mA g^-1 within a voltage range of 1.5–4.0 V. Furthermore, a full cell assembled with a KTO/KMZO-1 cathode and a hard carbon anode demonstrates superior electrochemical performance, achieving a reversible capacity of 58.77 mAh g^-1 after 200 cycles at 200 mA g^-1 with 77.2 % capacity retention. This study underscores the effectiveness of lattice stabilization and surface modification in enhancing the electrochemical properties of Mn-based layered oxide cathodes, offering a viable strategy for the development of durable and high-performance KIBs.