'Bubble-linking-bubble' hybrid fibers filled with ultrafine TiN: a robust and efficient platform achieving fast kinetics, strong ion anchoring and high areal loading for selenium sulfide

摘要

Building intricate one-dimensional structures is triggering unprecedented innovations in energy storage systems due to their good mechanical properties, fascinating physicochemical characteristics and superior electrochemical performance. Herein, we introduce a general strategy to prepare "bubble-linking-bubble" (BLB) hierarchical hybrid fibers, which are applied as robust, flexible and highly efficient hosts for selenium sulfides. TiN nanoparticles are enwrapped by a porous carbon matrix that fills hollow carbon bubbles. And then the bubbles are connected by short carbon nanorods to construct the BLB hybrid fiber. Both the porous carbon matrix and the hollow bubble shell together with the linking carbon rods build a continuous conductive framework that promotes fast electron transport. Meanwhile, the highly porous carbon matrix and the ultrafine TiN nanoparticles provide both physical and chemical entrapment to anchor polysulfides, manifesting high active material utilization and excellent cycling stability. Moreover, the BLB structure with good mechanical characteristics and high pliability facilitates construction of flexible electrodes. Accordingly, the BLB hybrid fiber is a highly efficient platform to synergistically promote fast kinetics, depress ion shuttling and enhance the energy storage capability of selenium sulfide. For the first time, the formation mechanism of the BLB hybrid fiber is specified. The crucial conditions for controlling the BLB structure are clarified, and moreover, the specific functions of each component in the BLB fiber are revealed. Taking advantage of the unique structure, the selenium sulfide@BLB hybrid fiber achieves superior high-rate properties and better cycling stability than the reference samples. Even with high areal mass loading, the electrodes still exhibit high areal capacities and good cycling stabilities under high current densities, demonstrating their high potential for practical applications. Therefore, this work not only introduces a novel platform to build high performance electrodes, but also provides a new approach to fabricate flexible electrodes towards practical applications.