A Dual-Layer Micro/nanostructured Fibrous Membrane with Enhanced Ionic Conductivity for Lithium-Ion Battery

Electrospun fiber-based composite membrane with interconnected porous structure has drawn significant attention for application in lithium-ion battery (LIB) owing to its high ion transportation. Here, we report a facile approach to fabricate the hierarchically micro/nanostructured ultrathin SiO2-PAN skin layer on the PAN-PU fibrous membrane surface via electrospinning and sequential electrospraying techniques. Benefiting from the synergistic effect of the micro/nanostructure and the superior electrolyte affinity of the SiO2-PAN skin layer, the as-prepared SiO2-PAN@PAN-PU membrane demonstrates the decreased pore size (1.18 mu m), enhanced ionic conductivity (1.4 mS cm(-1)) and robust electrochemical stability up to 5.08 V. Moreover, the introduction of skin layer endows the as-prepared SiO2-PAN@PANPU membrane with improved stress strength (15.7 MPa) and excellent thermostability of 200 degrees C. Compared with the PAN-PU and Celgard membranes, the dual-layer micro/nanostructured SiO2-PAN@PAN-PU fibrous membrane based Li/LiFePO4 cell assembled with high mass-loading LiFePO4 demonstrates a more stable cycling lifetime with a high discharge capacity (107.4 mAh g(-1) at the 105th cycles) and higher rate capability (75.2 mAh g(-1) at 1 C). The strategy using electrospraying technique demonstrated in this work will open the door to narrow fibrous membrane pore size and enhance ionic conductivity for potential application in the high-power LIB. (C) 2018 Elsevier Ltd. All rights reserved.