高浓度LiI实现硫正极稳定的高效利用  

High concentration Li Irealizes stable and efficient utilization of sulfur cathode

作　　者：王博[1] 王钊 屈超群[1] WANG Bo;WANG Zhao;QU Chao-qun(Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education,Jilin Normal University,Changchun 130103,China)

机构地区：[1]吉林师范大学功能材料物理与化学教育部重点实验室,吉林长春130103

出　　处：《分子科学学报》2023年第2期118-126,共9页Journal of Molecular Science

基　　金：国家自然科学基金资助项目(21905110)。

摘　　要：具有高比容量和低成本的锂硫电池被认为是下一代电池的重要候选者.然而,低的硫利用率、严重的穿梭效应以及金属锂负极枝晶的生长制约其实际应用.在电解液中引入添加剂被证实是一种简单有效的性能改善策略.为此,本文将高浓度的LiI引入到Li-S电池的常规电解液中,研究高浓度的LiI电解液对硫正极的利用、金属锂负极的保护以及对应电池电化学性能的影响.结果表明,高浓度的碘化锂电解液能够在金属锂负极表层形成稳定的保护层,抑制了锂枝晶的产生.与此同时,碘化锂的引入大幅度提高电池的比容量、有效改善电池的倍率性能和循环稳定性.通过优化发现,浓度为0.5 mol·L^(-1)的LiI具有最佳的电化学性能.采用此电解液的锂硫电池,在1 C倍率下,放电容量高达1200 mAh·g^(-1).200次循环之后,容量仍能保持在880 mAh·g^(-1),容量保持率接近75%.此外,电池展示了良好的倍率性能,在5 C倍率下,放电容量依然高达700 mAh·g^(-1).In recent years, with the rapid development of electric vehicles and large-scale energy storage, the rapid development of lithium-ion batteries has been promoted. The increasing demand puts forward higher requirements for the energy density of batteries. However, the energy density of the existing commercial lithium-ion batteries is up to their own limits. Therefore, it is much imperative to develop a battery system which contains higher energy density. Among the next battery generations, Lithium-sulfur batteries(Li-S) with high specific capacity and lower cost are considered to be more competitive. However, low sulfur utilization, badly shuttle effect, and growth of lithium dendrites on the lithium metal anode restrict its practical application. The introduction of additives into the electrolyte of Li-S batteries has been proved to be a simple and effective improvement strategy. For this reason, in this paper, we introduce high-concentration LiI into the conventional electrolyte of Li-S batteries to study the utilization of high-concentration LiI electrolyte for sulfur cathode, the protection for lithium metal anode, and the electrochemical performance of the corresponding batteries. The results show that the high-concentration lithium iodide electrolyte can form a stable protective layer on the surface of the lithium metal anode, inhibiting the production of lithium dendrites. At the same time, the introduction of lithium iodide greatly increases the specific capacity of the battery and effectively improves the rate performance and cycle stability of the battery. The Li-Li symmetrical cell with 0.5 mol·L~(-1) LiI electrolytes has a very high CE up to 98.1% for 100 cycles at 1.0 mA·cm^(-2). At 1 C rate, the Li-S battery with this electrolyte has a discharge capacity of 1 200 mAh·g^(-1). After 200 cycles, the capacity can still be maintained at 880 mAh·g^(-1), and the capacity retention rate is close to 75%. In addition, the battery shows good rate performance, and the discharge capacity is still as high as 7

关 键 词：锂硫电池 碘化锂 电解液 高比容量 锂负极 

分 类 号：O646[理学—物理化学]