Effects of Substituting S with Cl on the Structural and Electrochemical Characteristics of Na₃SbS₄ Solid Electrolytes

Abstract

Herein, we report the synthesis of Na3–x SbS4–x Cl x (0 ≤ x ≤ 0.1) solid electrolytes using a liquid-phase method and describe their structural and electrochemical characteristics. A maximum room-temperature conductivity of 9.0 × 10–4 S cm–1 was achieved in the case of Na2.95SbS3.95Cl0.05 (Cl content = 1.25%). Rietveld analysis based on the X-ray diffraction data indicated that the altered structure due to Cl-substitution involved looser local bonding between Na and S (or Cl) around the Na1 site (Wyckoff 4d position); this site was also the underlying site for a three-dimensional ion-transport network, which comprised a structure that promoted fast ion transport. A bond valence sum mapping technique revealed that the specific crystal structure generated following Cl-substitution enabled the expansion of bottlenecks for Na+ conduction, especially along the c-axis. To investigate the effect of Cl doping in Na3SbS4 on the overall cell performance, the electrochemical performances of symmetric Na15Sn4/Na2.95SbS3.95Cl0.05 and Na2.90SbS3.90Cl0.10/Na15Sn4 cells were evaluated and compared with that of Na3SbS4. The introduction of NaCl into Na3SbS4 suppressed the increase in interfacial resistance that accompanied stripping/plating, thereby enhancing the cell’s electrochemical stability at 0 V versus Na/Na+.

Theoretical study on stability and ion transport property with halide doping of Na3SbS4 electrolyte for all-solid-state batteries

“…Meanwhile, experiments have demonstrated a room-temperature conductivity maximum by Cl doping, the values are 9.0 × 10 −4 S cm −1 and 2.9 × 10 −3 S cm −1 for x Cl = 0.05 and x Cl = 0.0625, respectively. 60,93,94 These measurements are consistent with the present DFT-MD data for Cl doping, but the experimental doping concentrations are noted to be slightly lower. Although a higher conductivity is exhibited by our prediction, our simulated doping level (at x Cl = 0.125) is apparently difficult to obtain experimentally because of decreased achievable SE pellet density.…”

Heavily Tungsten‐Doped Sodium Thioantimonate Solid‐State Electrolytes with Exceptionally Low Activation Energy for Ionic Diffusion

“…It is found that using two buffer layers of Na 3 SbS 4 to sandwich the solid electrolyte can greatly improve the EEI stability and the resulting ASSB shows good cycle performance with ah igh capacity maintained around 400 mAh g À1 ,asshown in Figure 3E and F. It should be noted that employing secondary EEI layers with enhanced electrochemical stability,s uch as Na 2.895 W 0.3 Sb 0.7 S 4 ,a re established approaches in ASSB research for enhancing the cycling lifetime. [38,77] Fore xample,i th as been found that hydrating the surface of Na 3 SbS 4 to form Na 3 SbS 4 •9 H 2 Ol eads to electrically insulating decomposition phases,such as NaH and Na 2 O. [78] This is effective in stabilizing the interface by blocking the flow of electrons necessary for further redox decomposition.…”

Nominally stoichiometric Na3(WxSixSb1−2x)S4 as a superionic solid electrolyte

“…32,46,47,51 In due course of research, the aliovalent doping of Na 3 MX 4 was executed to intentionally introduce such defects. [52][53][54][55][56][57][58][59][60] Among these, the most noteworthy improvement was made via the partial substitution of W 6+ for M 5+ to incorporate Na + vacancies in Na 3 SbS 4 . 56,61 Unprecedentedly high values for σ RT of 30-40 mS cm −1 were reported for Na ∼2.9 W ∼0.1 Sb ∼0.9 S 4 (sintered pellet), which highlighted the importance of defects.…”