Metal-Organic Coordination Enhanced Metallopolymer Electrolytes for Wide-Temperature Solid-State Lithium Metal Batteries.

Abstract

The practical application of polymer electrolytes is seriously hindered by the inferior Li+ ionic conductivity, low Li+ transference number (tLi+), and poor interfacial stability. Herein, a structurally novel metallopolymer is designed and synthesized by exploiting a molybdenum (Mo) paddle-wheel complex as a tetratopic linker to bridge organic and inorganic moieties at molecular level. The prepared metallopolymer possesses combined merits of outstanding mechanical and thermal stability, as well as a low glass transition temperature (Tg < -50 °C). Based on this metallopolymer, an advanced metal-organic coordination enhanced metallopolymer electrolyte (MPE) is developed for constructing high-performance solid-state lithium metal batteries (LMBs). Due to the unsaturated coordination of Mo atoms, the uniformly distributed Mo-polyoxometalates (Mo-POMs) in metallopolymer skeleton can effectively bis(fluorosulfonyl)imide anions (FSI-) and promote the dissociation of Li salts. Moreover, dynamic metal-organic coordination bonds endow the MPE with re-processability and self-healing, enabling it to accommodate electrode volume changes and maintain good interfacial contact. Consequently, the MPE achieves a competitive ionic conductivity of 0.712 mS cm-1 (25 °C), a high tLi+ (0.625), and a wide electrochemical stability window (> 5.0 V). This study presents a unique MPE design based on metal-organic coordination enhanced strategy, providing a promising solution for developing wide-temperature solid-state LMBs.