Soluble Electrolyte-Coordinated Sulfide Species Revealed in Al–S Batteries by Nuclear Magnetic Resonance Spectroscopy
Soluble Electrolyte-Coordinated Sulfide Species Revealed in Al–S Batteries by Nuclear Magnetic Resonance Spectroscopy
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DOI：
10.1021/acs.chemmater.2c00248
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发表时间：
2022-05
影响因子：
8.6
通讯作者：
Rahul Jay;A. Jadhav;Leo W. Gordon;R. Messinger
中科院分区：
文献类型：
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作者：
Rahul Jay;A. Jadhav;Leo W. Gordon;R. Messinger
近年来，可充电铝硫（Al-S）电池因其低成本、富土、安全和高理论容量的电极材料而引起了人们的极大兴趣。然而，Al-S电池表现出许多困扰其他金属硫电池系统的挑战，包括由于电解质可溶性反应中间体的形成而导致硫电极的显着容量衰减。本文采用含氯铝酸盐离子液体电解质对Al-S电池进行了从分子水平上的研究，采用多维固态27al MAS NMR、x射线光电子能谱（XPS）、x射线衍射（XRD）和电化学测量。在含有电解液浸泡分离器的循环硫电极上进行的固态27al单脉冲核磁共振测量显示，放电产物多种多样，并根据27al化学交换和章动核磁共振实验将其区分为液相和固相产物。在放电过程中，形成与alcl4 -氯铝酸盐阴离子配合的电解质可溶性硫化物，形成（SxAlCl4）y−电解质复合物。这些电解质配位的硫化物在充电后持续存在，导致活性质量的损失，这解释了在恒流循环中观察到的显著容量衰减。XPS， XRD和固态al核磁共振测量表明，固体无定形al2o3在放电后可逆形成。研究结果强调了了解电解质可溶性硫化物如何与多价金属硫电池中使用的复杂电活性物质协调的技术重要性，这可能会影响它们的可逆性和电化学性能。
Rechargeable aluminum–sulfur (Al–S) batteries have recently garnered significant interest to the low cost, earth abundance, safety, and high theoretical capacity of the electrode materials. However, Al–S batteries exhibit many challenges that plague other metal–sulfur battery systems, including significant capacity fade of the sulfur electrode due to the formation of electrolyte-soluble reaction intermediates. Here, Al–S cells using chloroaluminate-containing ionic liquid electrolytes were investigated up from the molecular level using multidimensional solid-state27Al MAS NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electrochemical measurements. Solid-state27Al single-pulse NMR measurements acquired on cycled sulfur electrodes containing electrolyte-soaked separator revealed multiple discharge products, which were distinguished into liquid- and solid-phase products based on27Al chemical exchange and nutation NMR experiments. During discharge, electrolyte-soluble sulfide species form that coordinate with the AlCl4–chloroaluminate anions, resulting in (SxAlCl4)y−electrolyte complexes. These electrolyte-coordinated sulfide species persist upon charge, resulting in the loss of active mass that explains the significant capacity fade observed upon galvanostatic cycling. XPS, XRD, and solid-state27Al NMR measurements reveal that solid amorphous Al2S3forms reversibly upon discharge. The results highlight the technological importance of understanding how electrolyte-soluble sulfide species coordinate with the complex electroactive species used in multivalent metal–sulfur batteries, which can affect their reversibility and electrochemical properties.