Core-Shell PMIA@PVdF-HFP/Al 2 O 3 Nanofiber Mats In Situ Coaxial Electrospun on LiFePO 4 Electrode as Matrices for Gel Electrolytes

Gel electrolytes show certain advantages over conventional liquid and solid electrolytes, but their mechanical strength and surface adhesion to the electrode remain to be improved. To address the challenges, we design and fabricate herein the core-shell nanofiber mats on the LiFePO electrode as matrices for gel electrolytes, in which the core is poly( -phenylene isophthalamide) (PMIA) nanofiber and the shell are composite of Al O nanoparticles and poly(vinylidene fluoride- -hexafluoropropylene) (PVdF-HFP). The mechanical property of the core-shell polymeric nanofiber mats and their surface interaction with LiFePO electrode are characterized complementarily using dynamic thermomechanical analysis and scanning electron microscopy. The electrochemical properties of the gel electrolytes based on the as-prepared matrices after being loaded with lithium salt solution are studied systematically on half coin cells. It is found that the ultimate strength of the core-shell PMIA@PVdF-HFP/Al O mat can reach 6.70 MPa, 2 times higher than that of the PVdF-HFP/Al O nanofiber mat. Meanwhile, the shell PVdF-HFP/Al O can ensure manifest surface affinity to the LiFePO electrode and enhance lithium-ion conductance. Thus, the as-assembled LiFePO half coin cells using PMIA@PVdF-HFP/Al O gel electrolyte show good electrochemical performances, especially the long cycle stability with the capacity retention of 96.6% after 600 cycles under 1C.