The purpose of this study is to overcome the poor dimensional stability of poly(vinylidene fluoride) (PVDF)-based electrospun membranes for polymer electrolytes, a new type of composite fibrous membranes based on PVDF/poly(2-acrylamido-2-methylpropanesulfonic acid lithium) (PAMPSLi) blend systems with different blend ratios were fabricated by electrospinning method. Morphology of the composite fibrous membranes was evaluated by scanning electron microscopy. Average diameters of the membranes were less than 250 nm, which were far less than that of pure PVDF fibrous membrane (400 nm). Fourier transform infrared spectroscopy and Raman scattering were used to characterize the interactions of two polymers. Wide-angle X-ray diffraction and differential scanning calorimetry techniques were applied to investigate the crystal structure of composite fibrous membranes. Owning to the good miscibility between PVDF and PAMPSLi, no phase-separated microstructure was observed in composite fibrous membranes. The membranes possessed a good wettability by liquid electrolytes and exhibited an excellent dimensional stability even at high loading of electrolytes. The polymer electrolyte showed the ionic conductivity of 3.45 x 10(-3) S/cm at room temperature and electrochemical stability up to 5.4 V for the blend ratio of 5/1. PVDF/PAMPSLi (5/1)-based polymer electrolyte was observed much more suitable than polymer electrolytes with other ratios of PVDF/PAMPSLi for application in high-performance lithium rechargeable batteries.