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 (CO2) is the key to achieve the targets of peak carbon dioxide emissions and carbon neutrality. The Na-CO2 battery made with cheap alkali metal sodium and greenhouse gas CO2 is an effective strategy to consume CO2 and store clean renewable energy. However, the liquid electrolyte volatilization in the open battery system and inevitable dendrite growth restrict the application of Na-CO2 batteries. In this work, magnesium-doped Na3Zr2Si2PO12 (NZSP) was studied as a solid electrolyte for solid-state Na-CO2 batteries. The ionic conductivity of Na3.2Zr1.9Mg0.1Si2PO12 reaches 1.16 mS cm(-1) at room temperature by replacing Zr ions in Na3Zr2Si2PO12 with Mg ions, and the structural changes are analyzed by neutron powder diffraction. The composite electrolyte consisting of highly conductive Na3.2Zr1.9Mg0.1Si2PO12 and high processability poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is utilized for the first time to assemble a solid-state Na-CO2 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-CO2 batteries.

Automated summary

This work studies magnesium-doped Na3Zr2Si2PO12 as a solid electrolyte for solid-state Na-CO2 batteries, and utilizes a composite electrolyte composed of highly conductive Na3.2Zr1.9Mg0.1Si2PO12 and high processability PVDF-HFP to assemble a solid-state Na-CO2 battery, demonstrating promising performance.