In Situ Formation of Coordinated Polymer via Organic–Inorganic Hybridization Engineering Boosting High‐Efficiency Potassium Storage

Organic redox‐active molecules with merits of structure diversity and tunable properties are emerging as promising cathodes for the practical usage of potassium‐ion batteries (PIBs). However, the inferior cycle stability and sluggish charge‐carrier mobility are two main drawbacks hindering the practical application of organic cathode materials. Herein, highly conductive inorganic CuS is combined with small molecule‐based redox species (perylene‐3,4,9,10‐tetracarboxylic dianhydride, PTCDA) to form a novel organic–inorganic hybrid cathode (PTCDA/CuS) for PIBs, which could undergo electrochemical‐induced in situ self‐transformation of a sulfur‐linked and Cu2+‐coordinated PTCDA polymer (labeled as Cu@PTCDA‐SP). Benefiting from improved redox sites from activated carbonyl groups, high stability afforded by the sulfur‐bridging, isotropic amorphous nature, and 3D cross‐linked nanosheet morphologies, the resulting Cu@PTCDA‐SP cathode exhibits a high‐rate capacity involving trielectron enolization (vs 2‐electron transformation in PTCDA monomers) and long‐term cycle life (over 2800 cycles at 5 A g−1). This organic–inorganic hybridized cathode is very promising for PIBs. Additionally, the self‐transformation strategy provides new insight into the discovery of more electrochemically induced interaction between organic–inorganic hybrids toward high‐performance secondary batteries.