<scp>Electronegativity‐Induced Single‐Ion</scp> Conducting Polymer Electrolyte for <scp>Solid‐State</scp> Lithium Batteries
Tianyi Hou, Yumin Qian, Dinggen Li, Bo Xu, Zhenyu Huang, Xueting Liu, Haonan Wang, Bowen Jiang, Henghui Xu, Yunhui Huang
Abstract
The application of solid polymer electrolytes (SPEs) is severely impeded by the insufficient ionic conductivity and low Li + transference numbers ( t Li + ). Here, we report an iodine‐driven strategy to address both the two long‐standing issues of SPEs simultaneously. Electronegative iodine‐containing groups introduced on polymer chains effectively attract Li + ions, facilitate Li + transport, and promote the dissociation of Li salts. Meanwhile, iodine is also favorable to alleviate the strong O−Li + coordination through a Lewis acid–base interaction, further improving the ionic conductivity and t Li + . As a proof of concept, an iodinated single‐ion conducting polymer electrolyte (IPE) demonstrates a high ionic conductivity of 0.93 mS cm −1 and a high t Li + of 0.86 at 25 °C, which is among the best results ever reported for SPEs. Moreover, symmetric Li/Li cells with IPE achieve a long‐term stability over 2600 h through the in‐situ formed LiF‐rich interphase. As a result, Li−S battery with IPE maintains a high capacity of 623.7 mAh g −1 over 300 cycles with an average Coulombic efficiency of 99%. When matched with intercalation cathode chemistries, Li/IPE/LiFePO 4 and Li/IPE/LiNi 0.8 Mn 0.1 Co 0.1 O 2 solid‐state batteries also deliver high‐capacity retentions of 95% and 97% at 0.2 C after 120 cycles, respectively.