Building Sodium Metal Battery with Polyisoprene-Based Air-Stable Single-Ion Gel Polymer Electrolyte

The intrinsically safe, flexible, single-ion gel polymer electrolytes with a high transference number (0.75) have been developed by making the proper blending of a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) copolymer and biocompatible poly((sulfamate-carboxylate) iso-prene) (PISC) when soaked in carbonate solvents. More interestingly, a steady conductivity of 1.81 x 10-5 S/cm is observed for 15 days under normal air exposure conditions (RH = 45%-61%, T = 25-31 degrees C). The sodium metal battery with an NVP cathode demonstrates charge/discharge cycling at 80 degrees C with 82% capacity retention at a C/5 rate after 45 cycles. To trigger cycling performance at room temperature, the gel is formed with a conventional liquid electrolyte and a capacity retention of 67.92% after 200 cycles (C/10 rate) even after air exposure to the electrolyte.