P3 type layered oxide frameworks: An appealing family of insertion materials for K-ion batteries

K-ion batteries (KIBs) offer an efficient technological alterna-tive to the state-of-the-art Li-ion batteries (LIBs) as energy storage devices with similar chemistry, comparable energy densities, elemental economy and uniformly distributed abun-dant resources. Nonetheless, their practical implementation warrants robust cathode materials that can yield high gravi-metric/volumetric energy density, stable cycle life, and high -rate capability. In this scenario, P3 type layered oxides form an appealing family of KIB cathodes, which includes single tran-sition metal based KxMO2 (M = transition metals) and multiple transition metals based KxM11-yM2yO2 and KxM11-y-zM2yM3z O2 (M1, M2, M3 = transition metals). They possess easy and scalable synthesis, high reversible capacity, and adequate operating potential. The current review attempts to capture the most recent advancements in the P3 type KIB cathodes focusing on structural stability, structure-property correlation, and electrochemical performance with suggestions for further material optimization. Finally, the challenges and potential of these P3 type oxide cathodes have been addressed to guide their future research and development as intercalation materials.

Automated summary

K-ion batteries (KIBs) are an efficient alternative to Li-ion batteries (LIBs) with similar chemistry, energy densities, elemental economy, and abundant resources. P3 type layered oxides, including single transition metal based KxMO2 and multiple transition metals based KxM11-yM2yO2 and KxM11-y-zM2yM3z O2, show promise as cathodes for KIBs with their easy synthesis, high capacity, and suitable operating potential. This review summarizes recent advancements in P3 type KIB cathodes, focusing on structural stability, structure-property correlation, and electrochemical performance, and provides suggestions for further material optimization.