Heteroatomic SenS8-n Molecules Confined in Nitrogen-Doped Mesoporous Carbons as Reversible Cathode Materials for High-Performance Lithium Batteries
Heteroatomic SenS8-n Molecules Confined in Nitrogen-Doped Mesoporous Carbons as Reversible Cathode Materials for High-Performance Lithium Batteries
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氮掺杂介孔碳中限制的杂原子 SenS8-n 分子作为高性能锂电池的可逆正极材料
DOI：
10.1021/acsnano.6b02315
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发表时间：
2016-09-01
期刊：
影响因子：
17.1
通讯作者：
Shi, Jianlin
中科院分区：
文献类型：
--
作者：
Sun, Fugen;Cheng, Hongye;Shi, Jianlin
采用易熔体浸渍的方法，将杂原子sen8 -n分子均匀包裹在氮掺杂介孔碳（NMCs）中，成功制备了高能锂电池用醚基电解质中的可逆正极材料。所得到的sen8 -n/NMC复合材料表现出高度可逆的电化学行为，其中硫化硒在放电充电循环中通过聚硫代硒化物中间体的可逆转化被回收。硫化硒分子的回收使sen8 -n/NMC阴极具有S和Se阴极的合理整合。密度泛函理论计算进一步表明，具有较高极化率的杂原子硫化硒分子比同原子硫化硒分子能更强地与nmc结合，从而更有效地抑制穿梭现象。因此，在氮掺杂碳的介孔约束下，最佳Se/S摩尔比为2/6的Se2S6/NMC复合材料具有优异的循环稳定性，初始库仑效率高达96.5%，在250 mA g（-1）下循环100次后具有883 mAh g（-1）的高可逆容量，在200次循环后具有780 mAh g（-1）的高可逆容量。这些令人鼓舞的结果表明，在介结构碳载体中，硫（如S、Se或Te）分子的杂原子化是提高锂电池用硫/碳基阴极电化学性能的一种很有前途的策略。
A reversible cathode material in an ether-based electrolyte for high-energy lithium batteries was successfully fabricated by homogeneously confining heteroatomic SenS8-n molecules into nitrogen-doped mesoporous carbons (NMCs) via a facile melt impregnation route. The resultant SenS8-n/NMC composites exhibit highly reversible electrochemical behavior, where selenium sulfides are recovered through the reversible conversion of polysulfoselenide intermediates during discharge charge cycles. The recovery of selenium sulfide molecules endows the SenS8-n/NMC cathodes with the rational integration of S and Se cathodes. Density functional theory calculations further reveal that heteroatomic selenium sulfide molecules with higher polarizability could bind more strongly with NMCs than homoatomic sulfur molecules, which provides more efficient suppression of the shuttling phenomenon. Therefore, with further assistance of mesopore confinement of the nitrogen-doped carbons, the Se2S6/NMC composite with an optimal Se/S mole ratio of 2/6 presents excellent cycle stability with a high initial Coulombic efficiency of 96.5% and a high reversible capacity of 883 mAh g(-1) after 100 cycles and 780 mAh g(-1) after 200 cycles at 250 mA g(-1). These encouraging results suggest that the heteroatomization of chalcogen (such as S, Se, or Te) molecules in mesostructured carbon hosts is a promising strategy in enhancing the electrochemical performances of chalcogen/carbon-based cathodes for Li batteries.