Enhancing the Dendrite Tolerance of NaSICON Electrolytes by Suppressing Edge Growth of Na Electrode along Ceramic Surface

Abstract

Solid‐state sodium batteries (SSNBs) have attracted extensive interest due to their high safety on the cell level, abundant material resources, and low cost. One of the major challenges in the development of SSNBs is the suppression of sodium dendrites during electrochemical cycling. The solid electrolyte Na3.4Zr2Si2.4P0.6O12 (NZSP) exhibits one of the best dendrite tolerances of all reported solid electrolytes (SEs), while it also shows interesting dendrite growth along the surface of NZSP rather than through the ceramic. Operando investigations and in situ scanning electron microscopy microelectrode experiments are conducted to reveal the Na plating mechanism. By blocking the surface from atmosphere access with a sodium‐salt coating, surface‐dendrite formation is prevented. The dendrite tolerance of Na | NZSP | Na symmetric cells is then increased to a critical current density (CCD) of 14 mA cm−2 and galvanostatic cycling of 1 mA cm−2 and 1 mAh cm−2 (half cycle) is demonstrated for more than 1000 h. Even if the current density is increased to 3 mA cm−2 or 5 mA cm−2, symmetric cells can still be operated for 180 h or 12 h, respectively.

Insight into the Evolution of Voids at the NASICON/Na Interface and Suppressing Void Accumulation by a Semiliquid Wetting Strategy

“…Interestingly, an abrupt polarization voltage drop occurs at the beginning of each stripping or plating process when severe polarization occurs in the last plating or stripping (here, we call this phenomenon the “initial voltage drop”). This phenomenon can be widely observed before cell failure in Na/NASICON/Na symmetric cells. ,,,,, Unfortunately, a detailed explanation of this phenomenon is lacking up to now.…”

“…The above studies revealed that morphological instability on cycling seems to widely exist for the inorganic solid-state electrolyte/Li (or Na) interface. However, the physicochemical properties of Na metal are different from those of Li, and the surface chemistry of solid-state electrolytes has a significant influence on the interface. − Therefore, the investigation of the void evolution of the NASICON/Na interface is meaningful. In addition, all of these studies use a three-electrode system to distinguish the interface kinetics of stripping and plating, where the fabrication of the reference electrode is complicated and error-prone.…”

Multifunctionalized Safe Separator Toward Practical Sodium‐Metal Batteries with High‐Performance under High Mass Loading

“…[46,47] Thus, the as-constructed functionalized NZSP@PP separator with high ionic conductivities, electron insulating nature and good mechanically robust composite NZSP+PVDF layers would be a promising solution in SMBs. [48] As shown in Figure S1 (Supporting Information), the as synthesized NZSP powders exhibit a well monoclinic NASICON phase (PDF #35-0412). [43,44] Cross-sectional scanning electron microscopy (SEM) image demonstrates that an ≈3 µm composite layer is uniformly coated onto the commercial PP separator (Figure 2a).…”

Recent progress and strategic perspectives of inorganic solid electrolytes: fundamentals, modifications, and applications in sodium metal batteries

“…499 By modifying the Na 490 Most recently, Ma et al proposed that the formation of sodium dendrites on the NZSPO surface can be prevented simply by blocking the atmosphere with a protective coating of sodium salts, such as NaNO 3 or NaCl, where the CCD of the symmetric Na/NZSPO/Na cell reaches 14 mA cm À2 . 508…”

“…This strategy can be achieved mostly by the control of processing conditions, selection of precursors, and adding dopants or additives to decorate the grain boundaries. 380,386,387,457,508 (4) To build a kinetically stable interface with a robust in situ formed SEI layer (Fig. 30(iv)).…”