Molybdenum Polysulfide Chalcogels as High-Capacity, Anion-Redox-Driven Electrode Materials for Li-Ion Batteries
Molybdenum Polysulfide Chalcogels as High-Capacity, Anion-Redox-Driven Electrode Materials for Li-Ion Batteries
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DOI：
10.1021/acs.chemmater.6b03656
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发表时间：
2016-11-22
影响因子：
8.6
通讯作者：
Seshadri, Ram
中科院分区：
文献类型：
--
作者：
Doan-Nguyen, Vicky V. T.;Subrahmanyam, Kota S.;Seshadri, Ram
转化反应电池中的硫阴极具有较高的重量容量，但存在寄生多硫化物穿梭。我们在这里证明了近似式MoS3.4的过渡金属硫凝胶作为锂离子电池的电极材料具有接近600 mAh g（-1）的高重量容量（在硫的基础上接近1000 mAh g(-1)）。过渡金属硫凝胶是无定形的，由无机连接剂连接的多硫化物链组成。连接体似乎在电极中起到“胶水”的作用，以防止多硫化物穿梭。Mo硫凝胶在碳酸盐和醚基电解质中起电极的作用，这进一步证明了多硫化物的溶解度不是一个限制问题。我们利用x射线光谱和operando对分布函数技术来阐明电极的结构演变。拉曼和x射线光电子能谱跟踪阴离子氧化还原驱动过程中产生的化学成分。我们发现Mo的氧化还原状态在整个电化学循环中保持不变，相应地，氧化还原是阴离子驱动的。
Sulfur cathodes in conversion reaction batteries offer high gravimetric capacity but suffer from parasitic polysulfide shuttling. We demonstrate here that transition metal chalcogels of approximate formula MoS3.4 achieve a high gravimetric capacity close to 600 mAh g(-1) (close to 1000 mAh g(-1) on a sulfur basis) as electrode materials for lithium-ion batteries. Transition metal chalcogels are amorphous and comprise polysulfide chains connected by inorganic linkers. The linkers appear to act as a "glue" in the electrode to prevent polysulfide shuttling. The Mo chalcogels function as electrodes in carbonate- and ether-based electrolytes, which further provides evidence of polysulfide solubility not being a limiting issue. We employ X-ray spectroscopy and operando pair distribution function techniques to elucidate the structural evolution of the electrode. Raman and X-ray photoelectron spectroscopy track the chemical moieties that arise during the anion-redox-driven processes. We find the redox state of Mo remains unchanged across the electrochemical cycling and, correspondingly, the redox is anion-driven.