Abstract
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.
基金项目
National Natural Science Foundation of China(22075027)
National Natural Science Foundation of China(52003030)
Starting Grant from Beijing Institute of Technology,China()
Fund of the State Key Laboratory of Explosion Science and Safety Protection(YBKT21-06)
Fund of the State Key Laboratory of Explosion Science and Safety Protection(YBKT23-05)
NETL
NSTL
万方数据