Dual-Function Lifepo4 Modified Separator For Low-Overpotential And Stable Li-S Battery

Lithium sulfide (Li2S) compounds as cathode materials for Lithium-sulfur (Li-S) battery have attracted more and more attention recently because of its high specific capacity, lower volume expansion and higher thermal stability of Li2S. However, high electrochemical barrier of the Li2S cathode and "shuttle effect" from S species on anode still block the development of Li-S batteries. Herein, LiFePO4 (LFP) is employed as dual-function separator modifier to establish hybrid cathode. The modified separator will reduce overpotential for effective and durable sulfur redox reactions at the same time, it can also efficiently immobilize the lithium polysulfides (LiPSs) through the Lewis acid-base interaction of LiPSs and LFP. The battery systems based on the asdeveloped LFP modified separator exhibit an excellent rate capability, high sulfur utilization and outstanding cycling performance. The capacity retention can reach 83.9% after 400 cycles at 0.2 C, and the capacity can reach 594 mAh g(-1) at up to 2 C. Current facile and low-cost strategy to modified Li-S battery systems on one hand offers an effective pathway to enhance electrochemical performance, on the other hand inspire new strategies on reducing the activation barrier of Li2S for improved sulfur electrochemistry as well. (C) 2021 Elsevier B.V. All rights reserved.