Construction of Ultrastable Ultrathin Black Phosphorus Nanodisks Hybridized with Fe₃O₄ Nanoclusters and Iron (V)-Oxo Complex for Efficient Potassium Storage

The practical application of metalloid black phosphorus (BP) based anodes for potassium ion batteries is mainly impeded by its instability in air and irreversible/sluggish potassium storage behaviors. Herein, a 2D composite is purposefully conceptualized, where ultrathin BP nanodisks with Fe3O4 nanoclusters are hybridized with Lewis acid iron (V)-oxo complex (FC) nanosheets (denoted as BP@Fe3O4-NCs@FC). The introduced electron coordinate bridge between FC and BP, and hydrophobic surface of FC synergistically assure that BP@Fe3O4-NCs@FC is ultrastable in humid air. With the purposeful structural and componential design, the resultant BP@Fe3O4-NCs@FC anode is endowed with appealing electrochemical performance in terms of reversible capacity, rate behavior, and long-duration cycling stability in both half and full cells. Furthermore, the underlying formation and potassium-storage mechanisms of BP@Fe3O4-NCs@FC are tentatively proposed. The in-depth insights here will provide a crucial understanding in rational exploration of advanced anodes for next-generation PIBs.