Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025, People's Republic of China.
Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
ACS Appl Mater Interfaces. 2022 Dec 7;14(48):53850-53859. doi: 10.1021/acsami.2c16362. Epub 2022 Nov 18.
The lithium (Li) ion and electron diffusion behaviors across the actual solid electrolyte interphase (SEI) play a critical role in regulating the Li nucleation and growth and improving the performance of lithium-sulfur (Li-S) batteries. To date, a number of researchers have pursued an SEI with high Li-ion conductivity while ignoring the Li dendrite growth caused by electron tunneling in the SEI. Herein, an artificial anti-electron tunneling layer with enriched lithium fluoride (LiF) and sodium fluoride (NaF) nanocrystals is constructed using a facile solution-soaking method. As evidenced theoretically and experimentally, the LiF/NaF artificial SEI exhibits an outstanding electron-blocking capability that can reduce electron tunneling, resulting in dendrite-free and dense Li deposition beneath the SEI, even with an ultrahigh areal capacity. In addition, the artificial anti-electron tunneling layer exhibits improved ionic conductivity and mechanical strength, compared to those of routine SEI. The symmetric cells with protected Li electrodes achieve a stable cycling of 1500 h. The LiF/NaF artificial SEI endows the Li-S full cells with long-term cyclability under conditions of high sulfur loading, lean electrolyte, and limited Li excess. This study provides a perspective on the design of the SEI for highly safe and practical Li-S batteries.
锂离子和电子在实际固体电解质界面（SEI）中的扩散行为对于调节锂成核和生长以及改善锂硫（Li-S）电池的性能起着至关重要的作用。迄今为止，许多研究人员追求具有高锂离子电导率的 SEI，而忽略了 SEI 中电子隧穿导致的锂枝晶生长。在此，我们通过简便的溶液浸泡法构建了一种具有丰富氟化锂（LiF）和氟化钠（NaF）纳米晶体的人工抗电子隧穿层。理论和实验都证明，LiF/NaF 人工 SEI 具有出色的电子阻挡能力，可以减少电子隧穿，从而在 SEI 下实现无枝晶且致密的锂沉积，即使在超高面积容量下也是如此。此外，与常规 SEI 相比，人工抗电子隧穿层具有更高的离子电导率和机械强度。受保护的 Li 电极的对称电池可稳定循环 1500 h。LiF/NaF 人工 SEI 赋予 Li-S 全电池在高硫载量、贫电解液和有限 Li 过量的条件下的长期循环稳定性。本研究为高安全性和实用 Li-S 电池的 SEI 设计提供了新视角。
