Dynamic Supramolecular Polymer Electrolyte to Boost Ion Transport Kinetics and Interfacial Stability for Solid-State Batteries

Abstract

The key hurdle to the practical application of polymeric electrolytes in high-energy-density solid lithium-metal batteries is the sluggish Li⁺ mobility and inferior electrode/electrolyte interfacial stability. Herein, a dynamic supramolecular polymer electrolyte (SH-SPE) with loosely coordinating structure is synthesized based on poly(hexafluoroisopropyl methacrylate-co-N-methylmethacrylamide) (PHFNMA) and single-ion lithiated polyvinyl formal. The weak anti-cooperative H-bonds between the two polymers endow SH-SPE with a self-healing ability and improved toughness. Meanwhile, the good flexibility and widened energy gap of PHFNMA enable SH-SPE with efficient ion transport and superior interfacial stability in high-voltage battery systems. As a result, the as-prepared SH-SPE exhibits an ionic conductivity of 2.30 × 10⁻⁴ S cm⁻¹, lithium-ion transference number of 0.74, electrochemical stability window beyond 4.8 V, and tensile strength up to 11.9 MPa as well as excellent adaptability with volume change of the electrodes. In addition, no major electrolyte decomposition inside batteries made from SH-SPE and LiNi_0.8Mn_0.1Co_0.1O₂ cathode can be observed in the in situ differential electrochemical mass spectrometry test. This study provides a new methodology for the macromolecular design of polymer electrolytes to address the interfacial issues in high-voltage solid batteries.