Tetraglyme Based Electrolytes Enabled Excellent Cycling of Sodium Metal

Abstract

Sodium metal is a promising anode for batteries because of its high theoretical specific capacity (1165 mAh g-1) and great abundance and low cost. However, fundamental issues such as dendrite formation, “dead sodium” accumulation during cycling, fast SEI dissolution or continuous SEI growth bring challenges for stabilizing reversibility of sodium metal anode. Recent advances in electrolyte engineering and development of highly stable cathode materials have enables sodium metal batteries reaching high CE (>99 %) at room temperature1-5.Herein, we report a feasible pathway toward further stabilization of sodium metal anode using tetraglyme solvent (TEGDME) based electrolyte with various sodium salts (NaBF4, NaPF6, NaTFSI, NaFSI, NaClO4, NaOTf). It is demonstrated that a Na||Cu cell exhibited an average Coulombic efficiency of 99.9 % over 200, 850, and 1000 plating-stripping cycles when an electrolyte of 1M NaOTf in TEGDME, 1M NaPF6 in TEGDME, and 1M NaBF4 in TEGDME were used, respectively. Furthermore, 1M NaBF4 in TEGDME electrolyte also enabled excellent cycling stability of Na||Na3V2(PO4)2 batteries at high rate (1 C) for 1000 cycles with capacity retention of 90.8 %. References Seh, Z. W.; Sun, J.; Sun, Y.; Cui, Y. A Highly Reversible Room Temperature Sodium Metal Anode. ACS Cent. Sci. 2015, 1, 449−455.Cao, R.; Mishra, K.; Li, X.; Qian, J.; Engelhard, M. H.; Bowden, M. E.; Han, K. S.; Mueller, K. T.; Henderson, W. A.; Zhang, J.-G. Enabling Room Temperature Sodium Metal Batteries. Nano Energy 2016, 30, 825−830.Zheng, J.; Chen, S.; Zhao, W.; Song, J.; Engelhard, M.H.; Zhang, J.G. Extremely Stable Sodium Metal Batteries Enabled By Localized High-Concentration Electrolytes, ACS. Energy. Lett. 2018, 315−321.Goktas, M.; Bolli, C.; Buchkheim, J.; Berg, E. J; Novak, P.; Bonilla, F.; Rojo, T.; Komaba, S.; Kubota, K.; Adelhem, P.; Stable and Unstable Diglyme-Based Electrolytes for Batteries With Sodium or Graphite as Electrode., ACS Appl. Mater. Interfaces 2019, 11, 32844-32855.Le, P.M.L; Vo, D.T; Pan, H., Yan, J.; He, Y.; Cao, X.; Nguyen, H.V; Engelhard, M.H; Wang, C.; Xiao, J.; Zhang, J-G., Excellent Cycling Stability of Sodium Anode Enabled by a Stable Solid Electrolyte Interphase Formed in Ether-Based Electrolytes, Adv. Funct. Mater. 2020, 30, 2001151 Acknowledgement This work is supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the US Department of Energy (DOE) through the Advanced Battery Materials Research (BMR) program under contract no. DE-AC05-76RLO1830.