Journal Article

A Natural Polymer Captor for Immobilizing Polysulfide/Polyselenide in Working Li–SeS2 Batteries

Wang, Menglei, Wei, Yunhong, Wang, Boya, Zhang, Yin, Zhang, Yueying, Wu, Hao, Huang, Lingzhi, Guo, Yi, Jing, Peng, Wang, Qian, Zhang, Yun, Sun, Jingyu

2021

Overview

HighlightsTheoretical calculations reveal that Nicandra physaloides pectin can serve as Lewis base to realize strong interaction toward both lithium polysulfide and polyselenides.Nicandra physaloides pectin is introduced into a conductive double-carbon self-supporting film to build an anchoring and regulating interlayer for Li–SeS2 batteries.The Li–SeS2 pouch cells assembled with the interlayers deliver good flexibility and stability to demonstrate a viable strategy for developing working Li–SeS2 batteries.SeS2 has become a promising cathode material owing to its enhanced electrical conductivity over sulfur and higher theoretical specific capacity than selenium; however, the working Li–SeS2 batteries have to face the practical challenges from the severe shuttling of soluble dual intermediates of polysulfide and polyselenide, especially in high-SeS2-loading cathodes. Herein, a natural organic polymer, Nicandra physaloides pectin (NPP), is proposed to serve as an effective polysulfide/polyselenide captor to address the shuttling issues. Informed by theoretical calculations, NPP is competent to provide a Lewis base-based strong binding interaction with polysulfides/polyselenides via forming lithium bonds, and it can be homogeneously deposited onto a three-dimensional double-carbon conductive scaffold to finally constitute a polysulfide/polyselenide-immobilizing interlayer. Operando spectroscopy analysis validates the enhanced polysulfide/polyselenide trapping and high conversion efficiency on the constructed interlayer, hence bestowing the Li–SeS2 cells with ultrahigh rate capability (448 mAh g−1 at 10 A g−1), durable cycling lifespan (≈ 0.037% capacity attenuation rate per cycle), and high areal capacity (> 6.5 mAh cm−2) at high SeS2 loading of 15.4 mg cm−2. Importantly, pouch cells assembled with this interlayer exhibit excellent flexibility, decent rate capability with relatively low electrolyte-to-capacity ratio, and stable cycling life even under a low electrolyte condition, promising a low-cost, viable design protocol toward practical Li–SeS2 batteries.

• Publisher: Springer Nature B.V
• Subject: Attenuation / Bonding strength / Carbon / Cathodes / Cycles / Electrical resistivity / Electrode materials / Electrolytes / Electrolytic cells / Flexibility / Immobilization / Interlayers / Lewis base / Lithium / Mathematical analysis / Natural polymers / Pectin / Polysulfides / Selenium / Strong interactions (field theory)