Forging Inspired Processing of Sodium-Fluorinated Graphene Composite as Dendrite-Free Anode for Long-Life Na–CO2 Cells

• Main Authors: Chen, X. (Author), Cheng, H. (Author), Lu, Y. (Author), Mao, Y. (Author), Tu, J. (Author), Xie, J. (Author), Xu, X. (Author), Zhang, T. (Author), Zhao, X. (Author), Zhu, T. (Author)
• Format: Article
• Language: English
• Published: John Wiley and Sons Inc 2022
• Subjects: Anodes; Carbon dioxide; Cells; composite anode; Cytology; Dendrite growth; Density functional theory; Earth's crust; Energy storage; Facile method; fluorinated graphene; Forging; Graphene; Graphene composites; Greenhouse gases; Inhibition effect; Limited capacity; Low voltages; Na dendrite; Na–CO2 battery; NaF-rich protecting layer; Phase interfaces; Sodium; Sodium compounds; Sodium metallography; Solid electrolyte interfaces; Solid electrolytes; Structural geology
• Online Access: View Fulltext in Publisher

 Na–CO2 batteries recently are emerging as promising energy-storage devices due to the abundance of Na in the earth's crust and the clean utilization of greenhouse gas CO2. However, similar to metallic Li, metallic Na also suffers from a serious issue of dendrite growth upon repeated cycling, while a facile method to solve this issue is still lacking. In this work, we report an effective, environmentally friendly method to inhibit Na dendrite growth by in situ constructing a stable, NaF-rich solid electrolyte interface (SEI) layer on metallic Na via adding a small amount (~3 wt%) of fluorinated graphene (FG) in bulk Na. Inspired by the forging processing, a uniform Na/FG composite was obtained by melting and repetitive FG-adsorbing/hammering processes. The Na/FG–Na/FG half cell exhibits a low voltage hysteresis of 110–140 mV over 700 h at a current density up to 5 mA cm−2 with an areal capacity as high as 5 mAh cm−2. Na–CO2 full cell with the Na/FG anode is able to sustain a stable cycling of 391 cycles at a limited capacity of 1000 mAh g−1. Long cycle life of the cell can be attributed to the protecting effect of the in situ fabricated NaF-rich SEI layer on metallic Na. Both experiments and density functional theory (DFT) calculations confirm the formation of the NaF-rich SEI layer. The inhibition effect of the NaF-rich SEI layer for Na dendrites is verified by in situ optical microscopy observations. © 2021 Zhengzhou University.