Tuning functional two-dimensional MXene nanosheets to enable efficient sulfur utilization in lithium-sulfur batteries
Tuning functional two-dimensional MXene nanosheets to enable efficient sulfur utilization in lithium-sulfur batteries
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DOI：
10.1016/j.xcrp.2021.100480
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发表时间：
2021-07-21
影响因子：
8.9
通讯作者：
Kalra, Vibha
中科院分区：
文献类型：
--
作者：
Pai, Rahul;Natu, Varun;Kalra, Vibha
锂硫电池的实用性受到臭名昭著的多硫化物穿梭现象的严重阻碍，导致容量快速衰减。这个问题随着硫负载的增加而加剧，导致低库仑效率和循环寿命。在本文中，我们提出了一种简单的策略，通过使用二（氢化牛脂）苄基甲基氯化铵（DHT）的一步表面功能化，将疏水性硫和亲水性导电Ti 3C 2 Tz-MXene结合起来。后者使Ti 3C 2 Tz表面疏水，使其易于分散在溶解于二硫化碳（CS2）溶剂中的硫中。通过蒸发溶剂，我们用硫保形地涂覆DHTTi 3C 2 Tz（DMX）。所开发的复合材料具有更高的有效活性面积，能够有效地将多硫化锂（LiPs）捕获在阴极内的电活性位点上，从而在更高的硫负载下改善电化学性能。DMX/S阴极在类似于10.7 mg.cm（-2）的高硫负载下运行，并在150次循环中提供类似于7mAh.cm（-2）的稳定面积容量。此外，袋式电池配置中的DMX/S阴极在0.2C下类似于200次循环之后保持类似于770 mAh.g（-1）（85.5%保持率）。非原位研究阐明了LiPs-MXene相互作用的性质和表面官能化对改善性能的影响。
Practicality of lithium-sulfur batteries is severely hindered by the notorious polysulfide-shuttle phenomenon, leading to rapid capacity fade. This issue is aggravated with increase in sulfur loading, causing low-coulombic efficiency and cycle life. Herein, we present a facile strategy to combine hydrophobic sulfur and hydrophilic, conductive Ti3C2Tz-MXene via one-step surface functionalization using di(hydrogenated tallow)benzylmethyl ammonium chloride (DHT). The latter renders the Ti3C2Tz surface hydrophobic, making it readily dispersible in sulfur dissolved in a carbon disulfide (CS2) solvent. By evaporating the solvent, we conformally coat the DHTTi3C2Tz (DMX) with sulfur. The developed composite, with higher available active area, enables effective trapping of lithium polysulfides (LiPs) on the electroactive sites within the cathode, leading to improvement in electrochemical performance at higher sulfur loadings. The DMX/S cathodes function with high sulfur loading of similar to 10.7 mg.cm(-2) and deliver a stable areal capacity of similar to 7 mAh.cm(-2) for 150 cycles. Moreover, a DMX/S cathode in a pouch-cell configuration retains similar to 770 mAh.g(-1) after similar to 200 cycles at 0.2C (85.5% retention). Ex situ studies elucidate the nature of the LiPs-MXene interaction and the effect of surface functionalization towards improved performance.