Pinned Electrode/Electrolyte Interphase and Its Formation Origin for Sulfurized Polyacrylonitrile Cathode in Stable Lithium Batteries
Xianhui Zhang, Peiyuan Gao, Zhaohui Wu, Mark Engelhard, Xia Cao, Hao Jia, Yaobin Xu, Haodong Liu, Chongmin Wang, Jun Liu, Ji‐Guang Zhang, Ping Liu, Wu Xu
Abstract
Sulfurized polyacrylonitrile (SPAN) represents one of the most promising directions for high-energy-density lithium (Li)-sulfur batteries. However, the practical application of Li||SPAN is currently limited by the insufficient chemical/electrochemical stability of electrode/electrolyte interphase (EEI). Here, a pinned EEI layer is designed for stabilizing a SPAN cathode by regulating the EEI formation mechanism in an advanced LiFSI/ether/fluorinated-ether electrolyte. Computational simulations and experimental investigations reveal that, benefiting from the nonsolvating nature, the fluorinated-ether can not only act as a protective shield to prevent the Li polysulfides dissolution but also, more importantly, endow a diffusion-controlled EEI formation process. It promotes the formation of a uniform, protective, and conductive EEI layer pinning into SPAN surface region, enabling the high loading Li||SPAN batteries with superior cycling stability, wide temperature performance, and high-rate capability. This design strategy opens an avenue for exploring advanced electrolytes for Li||SPAN batteries and guides the interface design for broad types of battery systems.