理论揭示锂硫电池第二放电平台的主要液固相转换机制  

Theoretically revealing the major liquid-to-solid phase conversion mechanism of the second plateau in lithium-sulfur batteries

作　　者：张洪毅 薛红涛 魏承东 孙杰 许健 汤富领 Hongyi Zhang;Hongtao Xue;Chengdong Wei;Jie Sun;Jian Xu;Fuling Tang(School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China)

机构地区：[1]School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China [2]State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China

出　　处：《Science China Materials》2024年第8期2683-2693,共11页中国科学（材料科学）（英文版）

基　　金：supported by the Major Science and Technology Project of Gansu Province(22ZD6GA008);the National Natural Science Foundation of China(11764027 and 12204210);the support from the State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology,for theoretical simulations。

摘　　要：锂硫电池因其高理论能量密度、环境友好和低廉的成本而被认为是前景广阔的新型储能设备,但在放电后半程中缓慢的还原动力学严重阻碍其实际应用.虽然各种先进的正极材料改善了反应动力学,但硫还原反应(SRR)的复杂机理给提高锂硫电池性能设下许多障碍.深入研究其电催化机理是指导阴极材料设计和应用的重要环节.本文将揭示从Li_(2)S_(3);向Li_(2)_(S))(2)/Li_(2)_(S)的转化机制,即揭示从液相多硫化物到固相多硫化物的硫还原反应.以Ti、V、Fe、Co和Ni单原子催化剂为正极催化材料,建立基于密度泛函理论计算的电催化模型.中间产物^(*)LiS、^(*)LiS_(2)被用作预测反应路径、速率决定步骤和过电位的描述因子.这项工作解释了放电后期可溶多硫化物向不溶多硫化物的转化机理,为设计先进的高性能锂硫电池电催化剂提供了指导.Lithium-sulfur(Li-S)batteries are considered promising new energy storage devices due to their high theoretical energy density,environmental friendliness,and low cost.The sluggish reduction kinetics during the second half of the discharge hampers the practical applications of Li-S batteries.Although the reaction kinetics has been improved by various advanced cathode materials,the complex mechanism of the sulfur reduction reaction(SRR)leaves many obstacles to guide people in improving Li-S battery performances.An indepth investigation of its electrocatalytic mechanism is an vital link to guide the design and application of cathode materials.Herein,the chemical mechanism from Li_(2)S_(3)to Li_(2)_(S)2/Li_(2)_(S)will be revealed,which also means that SRR from liquid-phase polysulfides to solid-phase polysulfides will be unveiled.An electrocatalytic model based on systematic density-functional theory calculations was developed using single-atom catalysts involving Ti,V,Fe,Co,and Ni as the cathodic catalytic materials.Intermediate products^(*)LiS and^(*)LiS_(2)are used as descriptors to predict reaction pathways,rate-determining steps and overpotentials.This work explains the conversion mechanism of soluble to insoluble polysulfides at the late discharge stage and guides for the design of advanced highperformance lithium-sulfur battery electrocatalysts.

关 键 词：锂硫电池 电催化剂 阴极材料 储能设备 正极材料 多硫化物 电催化机理 密度泛函理论计算 

分 类 号：O643.36[理学—物理化学] TM912[理学—化学]