Adaptive 3D Cross‐Linked Single‐Ion Conducting Polymer Electrolytes Enable Powerful Interface for Solid State Batteries

Abstract Single‐ion conducting polymer electrolytes (SICPEs) are designed by covalently bonding anions to the polymers, which is attractive for mitigating anion aggregation‐derived polarization. However, one major challenge for developing SICPEs with higher ambient ionic conductivity comes at the expense of structural robustness. Here, boron ion‐centered lithium salt (LiT4PAB) with symmetric cross structure and terminal functional C═C was proposed as a units, and then 3D coordination electrolyte (LiPHB) was constructed via chemical cross‐linking of LiT4PAB with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP). The boron ion‐centered units catenated by single bonds show the abundant conformation transitions, enabling the deformable architecture of LiPHB with the aid of electrostatic interactions of diphenylsulfonimide. Therefore, LiPHB undergoes adaptive deformation when subjected to impact, achieving good ductility with elastic moduli of 1.4 GPa and a maximum elongation of 447.4%. Moreover, LiPHB demonstrates 3D single lithium‐ion transport channels to guide the homogeneous lithium deposition. As a results, lithium symmetric cells exhibit stable plating/stripping cycle for over 1500 h at 0.1 mA cm −2 at 30 °C. Li/LiPHB SICPEs/NCM811 solid‐state batteries deliver a capacity retention of 90.3% in 150 cycles at 30 °C and 0.2 C. Our study shed light on the design strategies of the dynamic single‐ion conducting polymer electrolytes for solid‐state batteries.