In Situ Fabrication of Porous CoxP Hierarchical Nanostructures on Carbon Fiber Cloth with Exceptional Performance for Sodium Storage

Superior high‐rate performance and ultralong cycling life have been constantly pursued for rechargeable sodium‐ion batteries (SIBs). In this work, a facile strategy is employed to successfully synthesize porous CoxP hierarchical nanostructures supported on a flexible carbon fiber cloth (CoxP@CFC), constructing a robust architecture of ordered nanoarrays. Via such a unique design, porous and bare structures can thoroughly expose the electroactive surfaces to the electrolyte, which is favorable for ultrafast sodium‐ion storage. In addition, the CFC provides an interconnected 3D conductive network to ensure firm electrical connection of the electrode materials. Besides the inherent flexibility of the CFC, the integration of the hierarchical structures of CoxP with the CFC, as well as the strong synergistic effect between them, effectively help to buffer the mechanical stress caused by repeated sodiation/desodiation, thereby guaranteeing the structural integrity of the overall electrode. Consequently, CoxP@CFC as an anode shows a record‐high capacity of 279 mAh g−1 at 5.0 A g−1 with almost no capacity attenuation after 9000 cycles. The mixed‐valence strategy and construction of an “all in one” electrode is employed to prepare flexible carbon fiber cloth supported porous CoxP hierarchical structures comprising nanoneedles and nanosheets. The as‐prepared CoxP@CFC electrode exhibits enhanced sodium‐storage performance with a high reversible capacity (814 mAh g−1), remarkable rate performance (279 mAh g−1 at 5.0 A g−1), and record ultralong cycling life (almost 100% capacity retention after 9000 cycles).