High-Temperature Formation of a Functional Film at the Cathode/Electrolyte Interface in Lithium–Sulfur Batteries: An In Situ AFM Study

Angewandte Chemie - International Edition

4 years ago

High-Temperature Formation of a Functional Film at the Cathode/Electrolyte Interface in Lithium–Sulfur Batteries: An In Situ AFM Study

Rui Wen, Yu-Guo Guo, Li-Jun Wan, Yang Shi, Shuang-Yan Lang

Lithium–sulfur (Li–S) batteries have been attracting wide attention for their promising high specific capacity. A deep understanding of Li–S interfacial mechanism including the temperature (T) effect is required to meet the demands for battery modification and systematic study. Herein, the interfacial behavior during discharge/charge is investigated at high temperature (HT) of 60 °C in an electrolyte based on lithium bis(fluorosulfonyl) imide (LiFSI). By in situ atomic force microscopy (AFM), dynamic evolution of insoluble Li2S2 and Li2S is studied at the nanoscale. An in situ formed functional film can be directly monitored at 60 °C after Li2S nucleation. It retards side reactions and facilitates interfacial redox. The insight into the interfacial processes at HT provides direct evidence of the existence of the film and reveals its dynamic behavior, providing a new avenue for electrolyte design and performance enhancement. Caught on film: By electrochemical AFM investigation at 60 °C, in situ formation of a functional film can be directly monitored at a highly oriented pyrolytic graphite (HOPG) cathode/polysulfide electrolyte interface in Li–S batteries. The film forms by a LiF net capturing polysulfide (PS) intermediates by both physical confinement and chemical anchoring effects.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/anie.201706979