高性能锂硫电池充放电过程的调控与机制分析  

Regulating and Understanding Charge-Discharge Process for High-Performance Lithium-Sulfur Batteries

作　　者：孙琪 何文辉[1,2] 逯乐慧 SUN Qi;HE Wen-Hui;LU Le-Hui(State Key Laboratory of Electroanalytical Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Changchun 130022,China;School of Applied Chemistry and Engineering,University of Science&Technology of China,Hefei 230026,China)

机构地区：[1]中国科学院长春应用化学研究所,电分析化学国家重点实验室,长春130022 [2]中国科学技术大学应用化学与工程学院,合肥230026

出　　处：《分析化学》2024年第11期1708-1716,共9页Chinese Journal of Analytical Chemistry

基　　金：国家自然科学基金项目(Nos.22374141,22134006,U2241287)资助。

摘　　要：锂硫电池的充放电循环为16电子转移过程,使得硫正极材料的比容量高达1675 mAh/g。然而,缓慢且复杂的动力学过程也导致了可溶性多硫化物的穿梭效应和低活性物质利用率。鉴于此,本研究采用顺铂作为氧化还原介质,通过多硫化物与顺铂间自发的氧化还原反应,调控锂硫电池充放电过程,并同时以顺铂为分子探针识别锂硫电池活性物质氧化还原反应路径。研究结果表明,引入顺铂可加快电荷转移动力学过程,调控氧化还原路径,并实现Li_(2)S_(2)到Li_(2)S的深度转化。引入顺铂后的锂硫电池的最大比容量达到1290 mAh/g,循环1000圈后,平均每圈容量衰减仅为0.017%,并且在具有实际应用价值的低电解液/硫比(2.5μL/mg)的软包电池中实现了318.8 Wh/kg的高能量密度。本研究通过原位拉曼光谱、电化学石英晶体微天平技术和质谱等表征手段对顺铂作用机制进行了探究,结果表明,顺铂可通过产生具有氧化还原活性的顺铂/多硫化物复合物调控锂硫电池反应路径,使缓慢迟滞的充放电过程被动力学更迅速的Pt^(4+)/Pt^(2+)对的氧化还原过程取代。本研究结果为合理利用功能化氧化还原介体解决锂硫电池中的关键问题提供了新思路。The charge-discharge process of lithium-sulfur battery is a 16-electron transfer process,which makes the specific capacity of the sulfur cathode up to 1675 mAh/g.However,the slow and complex kinetic process also results in shuttle effects and low availability of active substances for soluble polysulfides.In view of this,the use of cisplatin as a redox medium to regulate the charge-discharge process of lithium-sulfur batteries through the spontaneous redox reaction between polysulfide and cisplatin was reported.Meanwhile,cisplatin was used as a molecular probe to identify the redox reaction path of active substances in lithium-sulfur batteries.It was demonstrated that the introduction of cisplatin could accelerate charge transfer kinetics,regulate redox pathways and achieve deep transformation of Li_(2)S_(2) to Li_(2)S.The maximum specific capacity of the lithium-sulfur battery reached 1290 mAh/g,and the average capacity attenuation per cycle was only 0.017%after 1000 cycles,and the high energy density of 318.8 Wh/kg was achieved in the pouch cell with low electrolyte/sulfur ratio(2.5μL/mg)for practical application value.The mechanism of cisplatin was investigated by in-situ Raman spectroscopy,electrochemical quartz crystal microbalance,mass spectrometry and other characterization methods.The results showed that cisplatin could regulate the reaction path of lithium-sulfur batteries by generating redox active cisplatin/polysulfide complexes.The sluggish charge-discharge process was replaced by the more rapid redox process of Pt^(4+)/Pt^(2+)pairs.The results of this study provided a unique insight into the rational use of functionalized redox mediators to solve the key issues of lithium-sulfur batteries.

关 键 词：锂硫电池 顺铂 充放电过程 穿梭效应 原位表征技术 

分 类 号：TM912[电气工程—电力电子与电力传动]