Single ion conducting sodium ion batteries enabled by a sodium ion exchanged poly(bis(4-carbonyl benzene sulfonyl)imide-co-2,5-diamino benzesulfonic acid) polymer electrolyte

A single ion conducting sodium ion battery was fabricated and its operability at 20 °C and 80 °C was successfully demonstrated. In the battery device, sodium ion transport was mediated by a polymer electrolyte membrane based on a sodium ion exchanged poly(bis(4-carbonyl benzene sulfonyl)imide-co-2.5-diamino benzesulfonic acid) macromolecule (NaPA). The cathode material Na3V2(PO4)3 was synthesized using a calcination method, while a sodium metal foil was used as the anode. The PVDF-HFP blended NaPA membrane served as a separator as well as an electrolyte. The NaPA ionomers were introduced into the cathode to replace PVDF to form well-constructed sodium ion transport channels to reduce internal ion transport resistance and interfacial resistance. The ionic conductivity of the NaPA blend film was 0.91 × 10− 4 S/cm at 20 °C and 4.1 × 10− 4 S/cm at 80 °C, on the same order of magnitude of Na-Nafion. The half-cell delivered around 70% of its theoretical reversible specific capacity at 0.2C.