A High-Performance Solid-State Na–CO2 Battery with Poly(Vinylidene Fluoride-co-Hexafluoropropylene)−Na3.2Zr1.9Mg0.1Si2PO12 Electrolyte

The recovery and utilization of carbon dioxide (CO 2 ) is the key to achieve the targets of peak carbon dioxide emissions and carbon neutrality. The Na-CO 2 battery made with cheap alkali metal sodium and greenhouse gas CO 2 is an effective strategy to consume CO 2 and store clean renewable energy. However, the liquid electrolyte volatilization in the open battery system and inevitable dendrite growth restrict the application of Na-CO 2 batteries. In this work, magnesium-doped Na 3 Zr 2 Si 2 PO 12 (NZSP) was studied as a solid electrolyte for solid-state Na-CO 2 batteries. The ionic conductivity of Na 3.2 Zr 1.9 Mg 0.1 Si 2 PO 12 reaches 1.16 mS cm −1 at room temperature by replacing Zr ions in Na 3 Zr 2 Si 2 PO 12 with Mg ions, and the structural changes are analyzed by neutron powder diffraction. The composite electrolyte consisting of highly conductive Na 3.2 Zr 1.9 Mg 0.1 Si 2 PO 12 and high processability poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is utilized for the first time to assemble a solid-state Na-CO 2 battery. The cell shows a full discharge capacity of 7720 mAh g −1 at 200 mA g −1 . The middle gap voltage is lower than 2 V after 120 cycles at 200 mA g −1 and at a cut-off capacity of 500 mAh g −1 . This work demonstrates a promising strategy to design high-performance solid-state Na-CO 2 batteries.