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Two Competing Reactions of Sulfurized Polyacrylonitrile Produce High-Performance Lithium–Sulfur Batteries
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2021-05-20 , DOI: 10.1021/acsami.1c06004
Huilan Li 1 , Wenying Xue 1 , Lina Wang 1 , Tianxi Liu 1, 2
Affiliation  

Sulfurized polyacrylonitrile (SPAN) is an attractive cathode candidate for the advanced lithium–sulfur (Li–S) batteries owing to its outstanding cyclic stability. Nevertheless, SPAN suffers from inadequate initial Coulombic efficiency (CE) induced by the sluggish reaction kinetics, which is primarily ascribed to the low Li-ion diffusivity and high electronic resistivity of the Li2S product. In this work, an optimal trace amount of soluble lithium polysulfide of Li2S8 is introduced as a redox mediator for a freestanding fibrous SPAN cathode to enhance the reversible oxidation efficiency of Li2S. During the delithiation process, the chemical interactions between Li2S and Li2S8 additive facilitate the electrochemical oxidation of Li2S, resulting in the transformation of not only C–S/S–S bonds in SPAN but also elemental sulfur. Benefiting from the synergistic effect of the two competing reactions, a high initial CE of 82.9% could be achieved at a current density of 200 mA g–1. Moreover, a superior capacity retention along with a high capacity of 1170 mAh g–1 up to the 400th cycle is available at 1000 mA g–1. The study offers a feasible approach for Li–S batteries toward the practical applications of SPAN.

中文翻译:

硫化聚丙烯腈的两个竞争反应产生高性能锂硫电池

由于其出色的循环稳定性,硫化聚丙烯腈(SPAN)是先进的锂硫(Li-S)电池的有吸引力的正极候选材料。然而,SPAN 受到反应动力学缓慢引起的初始库仑效率 (CE) 不足的影响,这主要归因于 Li 2 S 产品的低锂离子扩散率和高电阻率。在这项工作中,引入了最佳痕量的 Li 2 S 8可溶性多硫化锂作为独立纤维 SPAN 正极的氧化还原介质,以提高 Li 2 S的可逆氧化效率。在脱锂过程中,Li 之间的化学相互作用2 S 和 Li 2 S8添加剂促进了 Li 2 S的电化学氧化,不仅导致 SPAN 中 C-S/S-S 键的转变,而且还导致元素硫的转变。受益于两个竞争反应的协同效应,在 200 mA g –1的电流密度下可以实现 82.9% 的高初始 CE 。此外,在 1000 mA g –1 下可获得出色的容量保持率以及高达 1170 mAh g –1直至第 400 次循环的高容量。该研究为 Li-S 电池在 SPAN 的实际应用中提供了一种可行的方法。
更新日期:2021-06-02
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