A High‐Performance Solid‐State Na–CO₂ Battery with Poly(Vinylidene Fluoride‐co‐Hexafluoropropylene)−Na_3.2Zr_1.9Mg_0.1Si₂PO₁₂ Electrolyte

Abstract

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 highperformance solid-state Na-CO 2 batteries.

Fundamental Understanding of Nonaqueous and Hybrid Na–CO2 Batteries: Challenges and Perspectives

“…[99] Lu et al investigated magnesium-doped Na 3 Zr 2 Si 2 PO 12 as a solid electrolyte for Na-CO 2 batteries. [27] By substituting the Zr ions in Na 3 Zr 2 Si 2 PO 12 (NZSP) with Mg ions, the ionic conductivity of Na 3.2 Zr 1.9 Mg 0.1 Si 2 PO 12 (NZM1SP) achieved 1.16 mS cm −1 at ambient temperature. The Na-CO 2 [31] Copyright 2021, Elsevier.…”

“…Afterward, the electrochemical performances of Na-CO 2 batteries have been gradually improved by developing novel cathodes and efficient catalysts, as well as modifying the anode surface and regulating the electrolyte (Figure 1b). [22][23][24][25][26][27][28][29][30][31][32] Intriguingly, the first rechargeable hybrid Na-CO 2 battery with an aqueous catholyte was reported in 2018, which can continuously generate electrical energy during discharge, while hydrogen was produced during charging, rather than CO 2 . [13] Conceptually, in CO 2 aqueous electrolysis, water is considered to be a good medium to donate protons for CO 2 electrochemistry with tunable products when assisted by specific electrocatalysts.…”

“…Na 3.2 Zr 1.9 Mg 0.1 Si 2 PO 12 electrolyte. Reproduced with permission [27]. Copyright 2022, Wiley-VCH.…”

“…c) Simplified view of the structure of Na 3.2 Zr 1.9 Mg 0.1 Si 2 PO 12 , charge and discharge curves, and voltage variation of the cells with NZSP-PVDF-HFP and NZM1SP-PVDF-HFP electrolytes. Reproduced with permission [27]. Copyright 2022, Wiley-VCH.…”

Recent Advances in Rechargeable Metal–CO2 Batteries with Nonaqueous Electrolytes

“…The research group used Co-NCF (discussed later) catalyst cathode and got highly reversible and easier to decompose The open system rechargeable Na−CO 2 batteries involving liquid organic electrolytes pose some drawbacks, such as the growth of sodium dendrites, electrochemical instability of the liquid electrolyte, leakage, and evaporation of the flammable organic solvents�which particularly impede the high-temperature operation and pose safety issues. 151,231,234 For example, tetraglyme (TEGDME) is one of the liquid electrolytes commonly used in metal−air batteries. Despite its high boiling point (275.3 °C), it also volatilizes in liquid electrolyte-based Na−CO 2 batteries at room temperature.…”