Solid-state batteries hold immense promise to deliver both high energy density and enhanced safety for advanced energy storage applications. However, low ionic conductivity and high interfacial resistance remain key challenges in the overall performance of practical sodium-ion devices. Therefore, herein, we fabricate and investigate freestanding composite polymer electrolytes (CPEs) comprising ${\mathrm{Na}}_3{\mathrm{Zr}}_2{\mathrm{Si}}_2{\mathrm{PO}}_{12}$ (NZSP) nanopowder, poly(vinylidene fluoride-co-hexafluoropropylene), polypropylene carbonates (PVDF-HFP/PPC), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), or ionic liquids or succinonitrile (SCN). The effects of ionic liquids [N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (PMPFSI), N-propyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PMPTFSI), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI)] and SCN on the crystal and vibrational structure, chemical environments and morphology are systematically examined. Furthermore, all the plasticized membranes exhibit suppressed irregular Na growth in symmetric cells, indicating stable and reversible Na stripping/plating over 300 h at $0.01\mathrm{mA}{\mathrm{cm}}^{-2}$, having lower overpotential than the NZSP membrane. Notably, the CPEs are electrochemically stable up to 5.0 V and EMIFSI-based CPE demonstrates a good transference number (0.75). Intriguingly, we find that the EMIFSI-based CPE outperforms the other electrolytes in terms of specific capacity, enabling the ${\mathrm{Na}}_3{\mathrm{V}}_2({\mathrm{PO}}_4{)}_2{\mathrm{F}}_3/\mathrm{C}$ cathode to deliver about $94\mathrm{mAh}{\mathrm{g}}^{-1}$ at 0.1 C and $22\mathrm{mAh}{\mathrm{g}}^{-1}$ at 2 C while maintaining stable cycling for up to 150 cycles at 0.5 C. This study proposes an innovative strategy for solid-state batteries to realize safer and more efficient energy storage systems.

Close

PrevNext

View figure in article

• Electrochemical properties
• Electrochemistry
• Ionic conductivity
• Structural properties
• Batteries
• Composite materials
• Energy materials
• Polymers