Accelerated Li~+ Desolvation for Diffusion Booster Enabling Low-Temperature Sulfur Redox Kinetics via Electrocatalytic Carbon-Grazfted-CoP Porous Nanosheets

摘要

Lithium–sulfur (Li–S) batteries are famous for their high energy density andlow cost, but prevented by sluggish redox kinetics of sulfur species due todepressive Li ion diffusion kinetics, especially under low-temperatureenvironment. Herein, a combined strategy of electrocatalysis and pore sievingeffect is put forward to dissociate the Li~+ solvation structure to stimulate thefree Li~+ diffusion, further improving sulfur redox reaction kinetics. As aprotocol, an electrocatalytic porous diffusion-boosted nitrogen-dopedcarbon-grafted-CoP nanosheet is designed via forming the N–Co–P activestructure to release more free Li~+ to react with sulfur species, as fullyinvestigated by electrochemical tests, theoretical simulations and in situ/exsitu characterizations. As a result, the cells with diffusion booster achievedesirable lifespan of 800 cycles at 2 C and excellent rate capability(775 mAh g~(?1) at 3 C). Impressively, in a condition of high mass loading orlow-temperature environment, the cell with 5.7 mg cm~(?2) stabilizes an arealcapacity of 3.2 mAh cm~(?2) and the charming capacity of 647 mAh g~(?1) isobtained under 0 ℃ after 80 cycles, demonstrating a promising route ofproviding more free Li ions toward practical high-energy Li–S batteries.