Chemical Activation of S/Li_(2)S in Li-S Batteries by a Bidirectional Organic Redox Mediator  

作　　者：LI Chengqiu ZHOU Chaoyong MEI Shilin YAO Changjiang 

机构地区：[1]State Key Laboratory of Explosion Science and Safety Protection,School of Mechatronical Engineering,Beijing Institute of Technology,Beijing,100081,P.R.China [2]Xi’an Safty Energy Technology Co.,Ltd.,Xi’an,710299,P.R.China

出　　处：《Chemical Research in Chinese Universities》2024年第5期927-934,共8页高等学校化学研究（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.22075027,52003030);the Starting Grant from Beijing Institute of Technology,China,and the Fund of the State Key Laboratory of Explosion Science and Safety Protection(Nos.YBKT21-06,YBKT23-05).

摘　　要：The energy density and lifespan of prototype Li-S batteries under high sulfur loading and lean electrolyte have been mainly restricted by the incomplete interconversion between insulating S8 and Li2S.The introduction of an electrocatalyst has been preserved as an effective way to breakthrough the bottleneck of the interconversion rate.Herein,we demonstrate a novel bidirectional redox mediator,insoluble dithiobisphthalimide(DTPI),as the electrocatalyst for both S8 reduction and Li2S oxidation.Due to the dual-functional role of both electron/Li^(+)donor and acceptor,DTPI can efficiently accelerate the redox reactions during charge/discharge and significantly alleviate the incomplete conversion of sulfur species.Consequently,the Li-S batteries with DTPI deliver superior specific capacity and cycling stability in comparison with those without DTPI.Especially,the redox mediator is scalable for synthesis and the DTPI-based 5 A·h pouch cell delivers a specific discharge capacity of around 870 mA·h·g^(−1) at 0.1 C(1 C=1675 mA/g)without capacity fading over 80 cycles.The bidirectional catalysis mechanism has been studied through theoretical calculation and ex-situ characterization of the cathode materials.This work approves the effectiveness of bidirectional organic redox mediator in the construction of practical Li-S batteries.

关 键 词：Lithium-sulfur battery(LSB) Dithiobisphthalimide(DTPI) Organic redox mediator INTERCONVERSION 

分 类 号：TM91[电气工程—电力电子与电力传动]