Kang Seul-Gi, Kim Dae-Hyun, Kim Bo-Joong, Yoon Chang-Bun
Department of Advanced Materials Engineering, Tech University of Korea, Siheung-si 15073, Republic of Korea.
Materials (Basel). 2023 Mar 29;16(7):2751. doi: 10.3390/ma16072751.
Sulfide-based solid electrolytes exhibit good formability and superior ionic conductivity. However, these electrolytes can react with atmospheric moisture to generate HS gas, resulting in performance degradation. In this study, we attempted to improve the stability of the interface between Li metal and an argyrodite LiPsCl solid electrolyte by partially substituting P with Sn to form an Sn-S bond. The solid electrolyte was synthesized via liquid synthesis instead of the conventional mechanical milling method. X-ray diffraction analyses confirmed that solid electrolytes have an argyrodite structure and peak shift occurs as substitution increases. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses confirmed that the particle size gradually increased, and the components were evenly distributed. Moreover, electrochemical impedance spectroscopy and DC cycling confirmed that the ionic conductivity decreased slightly but that the cycling behavior was stable for about 500 h at X = 0.05. The amount of HS gas generated when the solid electrolyte is exposed to moisture was measured using a gas sensor. Stability against atmospheric moisture was improved. In conclusion, liquid-phase synthesis could be applied for the large-scale production of argyrodite-based Li6PS5Cl solid electrolytes. Moreover, Sn substitution improved the electrochemical stability of the solid electrolyte.
硫化物基固体电解质具有良好的可成型性和优异的离子导电性。然而，这些电解质会与大气中的水分发生反应，生成硫化氢气体，导致性能下降。在本研究中，我们试图通过用锡部分替代磷以形成Sn-S键，来提高锂金属与硫银锗矿型Li₆PS₅Cl固体电解质之间界面的稳定性。该固体电解质是通过液相合成法而非传统的机械球磨法合成的。X射线衍射分析证实，固体电解质具有硫银锗矿结构，且随着替代量的增加会发生峰位移。扫描电子显微镜和能量色散X射线光谱分析证实，粒径逐渐增大，且各组分分布均匀。此外，电化学阻抗谱和直流循环测试证实，离子电导率略有下降，但在X = 0.05时，循环行为在约500小时内保持稳定。使用气体传感器测量了固体电解质暴露于湿气时产生的硫化氢气体量。其对大气湿气的稳定性得到了提高。总之，液相合成法可应用于大规模生产硫银锗矿型Li₆PS₅Cl固体电解质。此外，锡替代提高了固体电解质的电化学稳定性。
