Production and purification of anhydrous sodium sulfide
Production and purification of anhydrous sodium sulfide
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DOI：
10.1080/17415993.2021.1907390
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发表时间：
2021-04-01
影响因子：
2.2
通讯作者：
Wolden, Colin A.
中科院分区：
文献类型：
--
作者：
Smith, William H.;Birnbaum, Jerry;Wolden, Colin A.
无水硫化钠（Na 2S）是钠硫电池的关键组分，也是一种重要的化学试剂。然而，无水Na 2S目前对于研究实验室之外的应用来说过于昂贵，并且纯度是一个问题。在此，我们比较了三种形式的无水Na 2S的性质：（i）商业供应的，（ii）通过商业水合物薄片的脱水和纯化产生的Na 2S（Na 2S中心点xH（2）O），和（iii）通过硫化氢与溶解的醇钠反应形成并通过溶剂蒸发回收的Na 2S。低成本的Na 2S水合物在150 ℃下真空退火产生无水Na 2S。该脱水材料保留了在市售Na 2S中也观察到的多硫化物（Na 2S（x））和氧硫杂质（SO（x））的杂质特征。杂质去除通常需要在非常高的温度（700-900摄氏度）下进行氢还原，但这里证明这可以在400摄氏度下实现，从而防止自动氧化并遵循由收缩核模型充分描述的动力学。基于溶液的方法导致在低温（100 ° C）下直接合成结晶Na 2S酸酐，而不需要进一步纯化。本文提出的两种方法本质上都是可扩展的，材料成本比无水Na 2S的当前价格低一到两个数量级。
Anhydrous sodium sulfide (Na2S) is a key component in sodium-sulfur batteries as well as an important chemical reagent. However, anhydrous Na2S is currently prohibitively expensive for applications outside of research labs, and purity is a concern. Herein, we compare the properties of three forms of anhydrous Na2S: (i) commercially supplied, (ii) Na2S produced through dehydration and purification of commercial hydrate flakes (Na2S center dot xH(2)O), and (iii) Na2S formed by the reaction of hydrogen sulfide with dissolved sodium alkoxide and recovered through solvent evaporation. Vacuum annealing of low-cost Na2S hydrate at 150 degrees C produced anhydrous Na2S. This dehydrated material retains impurity signatures attributed to polysulfide (Na2S (x) ) and oxysulfur impurities (SO (x) ) that were also observed in commercially supplied Na2S. Impurity removal typically requires hydrogen reduction at very high temperature (700-900 degrees C), but it is demonstrated here that this can instead be accomplished at 400 degrees C, preventing auto-oxidation and following kinetics well-described by a shrinking core model. The solution-based approach resulted in the direct synthesis of crystalline Na2S anhydride at low temperatures (100 degrees C) without need for further purification. Both approaches presented herein are inherently scalable with materials costs that are one to two orders of magnitude lower than the current price of anhydrous Na2S.