Dendrite‐Free Sodium Metal Anodes Enabled by a Sodium Benzenedithiolate‐Rich Protection Layer

Abstract

Sodium metal is an ideal anode material for metal rechargeable batteries, owing to its high theoretical capacity (1166 mAh g−1), low cost, and earth‐abundance. However, the dendritic growth upon Na plating, stemming from unstable solid electrolyte interphase (SEI) film, is a major and most notable problem. Here, a sodium benzenedithiolate (PhS2Na2)‐rich protection layer is synthesized in situ on sodium by a facile method that effectively prevents dendrite growth in the carbonate electrolyte, leading to stabilized sodium metal electrodeposition for 400 cycles (800 h) of repeated plating/stripping at a current density of 1 mA cm−2. The organic salt, PhS2Na2, is found to be a critical component in the protection layer. This finding opens up a new and promising avenue, based on organic sodium slats, to stabilize sodium metals with a protection layer.

A Scalable Approach to Na2FeP2O7@Carbon/Expanded Graphite as a Low‐Cost and High‐Performance Cathode for Sodium‐Ion Batteries

“…[12][13][14] In recent year, considerable progresses have been reached in anode materials for SIBs, e. g. Sb@C, [4] FeTiO 3 @C, [5] Fe 7 Se 8 @C, [14] sodium metal. [15] Conversely, there is still an absence of suitable cathode materials. As is well known, typical P2 and O3 layer oxide cathodes still suffer serious capacity decay during the discharge/charge process, [16] and organic cathodes are inescapably hindered by the toxic raw material.…”

Solid Electrolyte Interphases on Sodium Metal Anodes

“…(e,f) Reproduced with permission. [ 141 ] Copyright 2020, Wiley. g) Schematic illustration of the in situ fabrication process of NaPS on Na metal.…”

“…Apart from the inorganic Na‐salt SEI, organic salts, such as sodium benzenedithiolate (PhS 2 Na 2 ), are identified as critical components in the protection layer for flat Na electrodeposition, which is an important finding for Na metal protection (Figure 8e). [ 141 ] The PhS 2 Na 2 ‐protected Na showcased a smooth surface, while very pronounced large‐surface‐area dendrites were present on the control sample shown in Figure 8f. Moreover, it is noteworthy that the thickness and composition of the protective layer can have a decisive influence on the stability of Na metal anodes.…”

Definable Two-Dimensional Mesoporous Polydopamine-Graphene Heterostructure as Multi-Functional Ion Redistributor for Ultrastable Sodium Metal Anodes

“…Unfortunately, its high reactive activity, large volume change, unstable solid electrolyte interface (SEI) and uncontrollable dendritic growth bring about low Coulombic e ciency, limited cyclability, and even safety risk for high-energy-density Na metal batteries, such as Na-S 10 and Na-O 2 batteries 11 , substantially inhibiting their actual applications 5,[12][13][14][15] . To overcome the issues, various strategies, including tailoring electrolyte formulation (e.g., highly concentrated electrolyte, uoroethylene carbonate additive) 16,17 , using solid-state electrolytes (gel polymer with boron nitride, Na 3 Zr 2 Si 2 PO 12 ) 18,19 , creating arti cial SEI (e.g., Al 2 O 3 , sodium benzenedithiolate, graphene) [20][21][22] , and designing nanostructured Na anodes (e.g., Na@O-functionalized carbon nanotube networks, Na@porous Al, Na@carbonized wood) 14,23,24 , have been developed to suppress the growth of Na dendrites and realize stable and safe Na metal anodes. Nevertheless, these designs usually revealed single chemical or physical function for regulating Na dendrites, and faced high processing cost and limited scalability.…”

“…Besides, constructing functional separators is considered as a more reliable and cost-effective way to realize uniform Na deposition from chemical molecule and physical structure levels [25][26][27] . From the viewpoint of molecular level, polymer brushes with abundant polar functional groups (e.g., C = O, -OH, -COOH and N-H) can enhance the electrolyte wettability, provide robust SEI interface, and thus easily homogenize the alkali-metal ion distribution and nucleation 21,[28][29][30][31][32] . In particular, two-dimensional (2D) graphene-like polymer materials (e.g., poly(N-isopropylacrylamide), polyacrylamide grafted graphene oxide (GO) and polypyrrole-GO heterostructure) with sheet-like structure, high speci c surface area (SSA), abundant surface chemistry and outstanding mechanical exibility, show tremendous advantage to regulate alkali-metal deposition and physically restrain dendrite puncture 22,28,29,33 .…”