In-Operando FTIR Study on the Redox Behavior of Sulfurized Polyacrylonitrile as Cathode Material for Li–S Batteries
In-Operando FTIR Study on the Redox Behavior of Sulfurized Polyacrylonitrile as Cathode Material for Li–S Batteries
复制标题
DOI：
10.1021/acs.jpcc.3c03421
复制
发表时间：
2023-09
期刊：
影响因子：
--
通讯作者：
Rhyz Pereira;K. Sarode;A. Rafie;Aaron T Fafarman;V. Kalra
中科院分区：
文献类型：
--
作者：
Rhyz Pereira;K. Sarode;A. Rafie;Aaron T Fafarman;V. Kalra
锂硫电池已经显示出作为后锂离子电池化学的巨大潜力，其理论容量高达1675 mAh/g。然而，它们受到与活性材料和放电产物的绝缘性质以及电化学反应期间中间产物的溶解性相关的基本材料挑战。对后一个问题提出的许多解决方案之一是将硫链化学地锚在有机分子上以形成有机硫材料。硫化聚丙烯腈（SPAN）就是这样一种材料，已经显示出巨大的前景。虽然SPAN在碳酸盐电解质中表现出较长的循环寿命，但其在醚电解质中的可行性仅在包含高浓度硝酸锂的情况下才有可能。为了识别充电和放电循环中存在的化学物质，阐明容量衰减的机制，并理解为什么容量在硝酸锂存在下保持不变，我们将XPS事后分析与三个光谱区域的操作中FT-IR研究相结合。我们探测了键振动，我们已经分配到的碳-硫键，锚定硫链的有机硫骨架，硫-硫键的锂多硫化物中的电解质中的演变，和环伸展的杂环环化PAN骨架。我们提出的证据支持锂化的杂环骨架。我们确定了一个强大的阴极电解质界面的形成与硝酸锂存在的系统的一个关键特征。这允许保留C-S键并抑制否则会引起穿梭损失的多硫化物。
Lithium–sulfur batteries have shown tremendous potential as a post lithium-ion battery chemistry, with a theoretical capacity of up to 1675 mAh/g. However, they have suffered from fundamental material challenges related to the insulating nature of the active material and discharge products as well as the solubility of intermediary products during the electrochemical reaction . One of the many proposed solutions to the latter problem has been to anchor the sulfur chain chemically to an organic molecule to form an organosulfur material. Sulfurized polyacrylonitrile (SPAN) is one such material that has shown tremendous promise. While SPAN has demonstrated long cycle life in carbonate electrolytes, its viability in ether electrolytes is only possible with the inclusion of high concentrations of lithium nitrate. To identify the chemical species present in charge and discharge cycles, elucidate the mechanisms of capacity fade, and understand why capacity is retained in the presence of lithium nitrate, we combined post-mortem analysis by XPS with an in-operando FT-IR study of three spectral regions. We probed bond vibrations we have assigned to the carbon–sulfur bond that anchors sulfur chains to the organosulfur backbone, the sulfur–sulfur bond in lithium polysulfides that evolve in electrolyte, and ring stretches of the heteropolycyclic cyclized-PAN backbone. We present evidence in support of lithiation of the heteropolycyclic backbone. We identify the formation of a robust cathode–electrolyte interphase to be a critical feature of systems with lithium nitrate present. This allows for the retention of the C–S bond and the suppression of polysulfides that otherwise cause shuttling losses.