LAUSR

Abstract The rational and oriented design of a proper electrode structure is crucial for the realization of desirable properties. Herein, we report the design and synthesis of freestanding hybrid films that feature desirable one-dimensional (1D) structure and favorable electrochemical properties for Li-ions batteries (LIBs). Briefly, by offering a water-steam originated from the real-time thermal decomposition reactions during the carbonization to etch the nanofibers in-situ, the hierarchical porosity and N, P co-doping are simultaneously introduced into carbon nanofibers skeleton. The synergistic effect of these two defects engineering expose more active sites, which can provide a substantial pseudocapacitance to boost the lithium storage performance. In addition, the in-situ coating structure formed by electrospinning process is also helpful to alleviate the volume expansion of Fe3O4. Therefore, the prepared hybrid films display the excellent results by delivering an areal capacity of 1.0 mAh cm-2 at 2 mA cm-2 after 200 cycles in the half-cell. Meanwhile, a practical coin-type full-cell also delivers an areal capacity of 0.62 mAh cm-2 at 0.5 mA cm-2 after 100 cycles. This work paves the way to constructing rational electrode materials with controllable defect engineering for energy-related applications.