A compact gel membrane (GM) with certain flexibility is facilely fabricated after a casted PEO/PVDF blend film is swelled by a LiPF 6 -based liquid electrolyte. The GM exhibits a suitable lithium ionic conductivity (0.28 mS cm À 1 at r.t., room temperature), a remarkable lithium-ion transference number (0.52 at r.t.), and high mechanical strength (19.0 MPa) in dry or wet state. Owing to the special comprehensive performance of the GM, dendritefree reversible lithium plating/stripping (up to 500 h) at a current density of 0.5 mA cm À 2 and a capacity of 0.25 mAh cm À 2 is achieved for Li metal anodes at r.t.. The suppression of lithium dendrite of the obtained GM is further demonstrated in Li/GM/LiFePO 4 cells with a high discharge capacity (142 mAh g À 1 at r.t. and 160 mAh g À 1 at 50°C) and a superior cycling stability. This research provides a new strategy for developing lithium metal batteries with high stability and long cycle life.

With the raw materials of poly(vinylidene-co-hexafluoropropylene) (P(VDF-HFP)) and polyamide 6 (PA6, nylon 6), a sandwich-structured composite membrane, PA6/P(VDF-HFP)/PA6, is fabricated via sequential layer-by-layer electrospinning. The nylon-based composite exhibits high absorption to organic liquid electrolyte (270 wt%) owing to its high porosity (90.35%), good mechanical property (17.11 MPa), and outstanding shut-down behavior from approximately 145 to 230 °C. Moreover, the dimensional shrink of a wet PA6 porous membrane immersed into liquid electrolyte is cured due to the existence of the P(VDF-HFP) middle layer. After swelling by the LiPF6-based organic liquid electrolyte, the obtained PA6/P(VDF-HFP)/PA6-based gel polymer electrolytes (GPE) shows high ionic conductivity at room temperature (4.2 mS cm−1), a wide electrochemical stable window (4.8 V), and low activation energy for Li+ ion conduction (4.68 kJ mol−1). Benefiting from the precise porosity structure made of the interlaced electrospinning nanofibers and the superior physicochemical properties of the nylon-based composite GPE, the reversible Li+ ion dissolution/deposition behaviors between the GPE and Li anode are successfully realized with the Li/Li symmetrical cells (current density: 1.0 mA cm−2; areal capacity: 1.0 mAh cm−2) proceeding over 400 h at a polarization voltage of no more than 70 mV. Furthermore, the nylon-based composite GPE in assembled Li/LiFePO4 cells displays good electrochemical stability, high discharge capacity, good cycle durability, and high rate capability. This research provides a new strategy to fabricate gel polymer electrolytes via the electrospinning technique for rechargeable lithium batteries with good electrochemical performance, high security, and low cost.